Effects of O 2 and N 2/H 2 plasma treatments on the neuronal cell growth on single-walled carbon nanotube paper scaffolds

NASA Astrophysics Data System (ADS)

Yoon, Ok Ja; Lee, Hyun Jung; Jang, Yeong Mi; Kim, Hyun Woo; Lee, Won Bok; Kim, Sung Su; Lee, Nae-Eung

2011-08-01

The O 2 and N 2/H 2 plasma treatments of single-walled carbon nanotube (SWCNT) papers as scaffolds for enhanced neuronal cell growth were conducted to functionalize their surfaces with different functional groups and to roughen their surfaces. To evaluate the effects of the surface roughness and functionalization modifications of the SWCNT papers, we investigated the neuronal morphology, mitochondrial membrane potential, and acetylcholine/acetylcholinesterase levels of human neuroblastoma during SH-SY5Y cell growth on the treated SWCNT papers. Our results demonstrated that the plasma-chemical functionalization caused changes in the surface charge states with functional groups with negative and positive charges and then the increased surface roughness enhanced neuronal cell adhesion, mitochondrial membrane potential, and the level of neurotransmitter in vitro. The cell adhesion and mitochondrial membrane potential on the negatively charged SWCNT papers were improved more than on the positively charged SWCNT papers. Also, measurements of the neurotransmitter level showed an enhanced acetylcholine level on the negatively charged SWCNT papers compared to the positively charged SWCNT papers.

Effect of Atmospheric Plasma Treatment to Titanium Surface on Initial Osteoblast-Like Cell Spreading. .

PubMed

Kim, In-Hye; Son, Jun-Sik; Kwon, Tae-Yub; Kim, Kyo-Han

2015-01-01

Plasma treatments are becoming a popular method for modifying the characteristics of a range of substrate surfaces. Atmospheric pressure plasma is cost-efficient, safe and simple compared to high-pressure plasma. This study examined the effects of atmospheric pressure plasma to a titanium (Ti) surface on osteoblast-like cell (osteoblast) spreading and cellular networks. The characteristics of the Ti surface before and after the atmospheric plasma treatment were analyzed by X-ray photoemission spectroscopy (XPS), scanning electron microscopy (SEM), contact angle measurements, and an optical 3D profiling system. The morphology of osteoblasts attached to the Ti surfaces was observed by SEM and confocal laser scanning microscopy. The atmospheric pressure plasma made the Ti surfaces more hydrophilic. The osteoblasts that adhered to the untreated surface were round and spherical, whereas the cells covered a larger surface area on the plasma-treated surface. The plasma-treated Ti surface showed enhanced cell spreading and migration with more developed cellular networks. In conclusion, an atmospheric plasma treatment is a potential surface modifying method that can enhance the initial the cell affinity at the early stages in vitro.

Biocompatibility enhancement of rare earth magnesium alloy by laser surface processing

NASA Astrophysics Data System (ADS)

Nie, Shilin; Wang, Yuqing; Liu, Haifeng; Guan, Yingchun

2018-01-01

Although magnesium and magnesium alloys are considered biocompatible and biodegradable, insufficient biocompatibility in body fluid environment is still the major drawback of magnesium alloys for their successful applications as biodegradable orthopaedic implants. In this work, magnesium alloy surface with both enhanced corrosion resistance and better cell adhesion property was directly fabricated by laser surface processing. Laser surface melting was used to improve corrosion resistance of Mg-6Gd-0.6Ca alloy. After laser surface melting, laser surface texturing was utilized on melted surface for better cell adhesion property. The corrosion resistance of laser-treated and as-received samples were evaluated using electrochemical technique. The effect of laser surface treatment on phase and microstructure evolution was evaluated using scanning electron microscopy, optical microscopy and X-ray diffraction. This work investigated the effect of laser treatment on cell distribution across the surface of magnesium alloy substrates. Osteoblast was cultured on the laser-treated surface and as-received surface. Cell morphology was observed with a scanning electron microscopy, and cell viability was evaluated by optical density measurement.

Nanolayer formation on titanium by phosphonated gelatin for cell adhesion and growth enhancement

PubMed Central

Zhou, Xiaoyue; Park, Shin-Hye; Mao, Hongli; Isoshima, Takashi; Wang, Yi; Ito, Yoshihiro

2015-01-01

Phosphonated gelatin was prepared for surface modification of titanium to stimulate cell functions. The modified gelatin was synthesized by coupling with 3-aminopropylphosphonic acid using water-soluble carbodiimide and characterized by 31P nuclear magnetic resonance and gel permeation chromatography. Circular dichroism revealed no differences in the conformations of unmodified and phosphonated gelatin. However, the gelation temperature was changed by the modification. Even a high concentration of modified gelatin did not form a gel at room temperature. Time-of-flight secondary ion mass spectrometry showed direct bonding between the phosphonated gelatin and the titanium surface after binding. The binding behavior of phosphonated gelatin on the titanium surface was quantitatively analyzed by a quartz crystal microbalance. Ellipsometry showed the formation of a several nanometer layer of gelatin on the surface. Contact angle measurement indicated that the modified titanium surface was hydrophobic. Enhancement of the attachment and spreading of MC-3T3L1 osteoblastic cells was observed on the phosphonated gelatin-modified titanium. These effects on cell adhesion also led to growth enhancement. Phosphonation of gelatin was effective for preparation of a cell-stimulating titanium surface. PMID:26366080

Solid-state NMR on bacterial cells: selective cell wall signal enhancement and resolution improvement using dynamic nuclear polarization.

PubMed

Takahashi, Hiroki; Ayala, Isabel; Bardet, Michel; De Paëpe, Gaël; Simorre, Jean-Pierre; Hediger, Sabine

2013-04-03

Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance (NMR) has recently emerged as a powerful technique for the study of material surfaces. In this study, we demonstrate its potential to investigate cell surface in intact cells. Using Bacillus subtilis bacterial cells as an example, it is shown that the polarizing agent 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL) has a strong binding affinity to cell wall polymers (peptidoglycan). This particular interaction is thoroughly investigated with a systematic study on extracted cell wall materials, disrupted cells, and entire cells, which proved that TOTAPOL is mainly accumulating in the cell wall. This property is used on one hand to selectively enhance or suppress cell wall signals by controlling radical concentrations and on the other hand to improve spectral resolution by means of a difference spectrum. Comparing DNP-enhanced and conventional solid-state NMR, an absolute sensitivity ratio of 24 was obtained on the entire cell sample. This important increase in sensitivity together with the possibility of enhancing specifically cell wall signals and improving resolution really opens new avenues for the use of DNP-enhanced solid-state NMR as an on-cell investigation tool.

Light-absorption enhancement design of ultrathin perovskite solar cells with conformal structure

NASA Astrophysics Data System (ADS)

Tan, Xinyu; Sun, Lei; Deng, Can; Tu, Yiteng; Shen, Guangming; Tan, Fengxue; Guan, Li; Yan, Wensheng

2018-06-01

We report a structural design of ultrathin perovskite solar cells based on a conformal structure at the rear surface for potential applications in both single-junction and tandem cells. The light transmittances of the front and the rear surfaces are calculated in the wavelength range of 300–800 nm via the finite difference time domain numerical simulation method. Compared with the reference cell, significant photocurrent density enhancement of 27.5% and 29.7% are achieved when the ratios of height to width of the fluorine doped tin oxide nanoblock are 2 and 3, respectively. For the case with a hole transport material layer, the enhancements of photocurrent density enhancements are 19.2% and 29.0%, respectively. When back Au is removed, the photocurrent density also has notable enhancements of 23.3% and 45.9%, respectively. The achieved results are beneficial for the development of efficient ultrathin single-junction and tandem perovskite solar cells.

Enhanced in vitro biological activity generated by surface characteristics of anodically oxidized titanium--the contribution of the oxidation effect.

PubMed

Wurihan; Yamada, A; Suzuki, D; Shibata, Y; Kamijo, R; Miyazaki, T

2015-05-20

Anodically oxidized titanium surfaces, prepared by spark discharge, have micro-submicron surface topography and nano-scale surface chemistry, such as hydrophilic functional groups or hydroxyl radicals in parallel. The complexity of the surface characteristics makes it difficult to draw a clear conclusion as to which surface characteristic, of anodically oxidized titanium, is critical in each biological event. This study examined the in vitro biological changes, induced by various surface characteristics of anodically oxidized titanium with, or without, release of hydroxyl radicals onto the surface. Anodically oxidized titanium enhanced the expression of genes associated with differentiating osteoblasts and increased the degree of matrix mineralization by these cells in vitro. The phenotypes of cells on the anodically oxidized titanium were the same with, or without, release of hydroxyl radicals. However, the nanomechanical properties of this in vitro mineralized tissue were significantly enhanced on surfaces, with release of hydroxyl radicals by oxidation effects. In addition, the mineralized tissue, produced in the presence of bone morphogenetic protein-2 on bare titanium, had significantly weaker nanomechanical properties, despite there being higher osteogenic gene expression levels. We show that enhanced osteogenic cell differentiation on modified titanium is not a sufficient indicator of enhanced in vitro mineralization. This is based on the inferior mechanical properties of mineralized tissues, without either being cultured on a titanium surface with release of hydroxyl radicals, or being supplemented with lysyl oxidase family members.

Surface-Enhanced Raman Spectroscopy Study of 4-ATP on Gold Nanoparticles for Basal Cell Carcinoma Fingerprint Detection

NASA Astrophysics Data System (ADS)

Quynh, Luu Manh; Nam, Nguyen Hoang; Kong, K.; Nhung, Nguyen Thi; Notingher, I.; Henini, M.; Luong, Nguyen Hoang

2016-05-01

The surface-enhanced Raman signals of 4-aminothiophenol (4-ATP) attached to the surface of colloidal gold nanoparticles with size distribution of 2 to 5 nm were used as a labeling agent to detect basal cell carcinoma (BCC) of the skin. The enhanced Raman band at 1075 cm-1 corresponding to the C-S stretching vibration in 4-ATP was observed during attachment to the surface of the gold nanoparticles. The frequency and intensity of this band did not change when the colloids were conjugated with BerEP4 antibody, which specifically binds to BCC. We show the feasibility of imaging BCC by surface-enhanced Raman spectroscopy, scanning the 1075 cm-1 band to detect the distribution of 4-ATP-coated gold nanoparticles attached to skin tissue ex vivo.

Adhesion and proliferation of OCT-1 osteoblast-like cells on micro- and nano-scale topography structured poly(L-lactide).

PubMed

Wan, Yuqing; Wang, Yong; Liu, Zhimin; Qu, Xue; Han, Buxing; Bei, Jianzhong; Wang, Shenguo

2005-07-01

The impact of the surface topography of polylactone-type polymer on cell adhesion was to be concerned because the micro-scale texture of a surface can provide a significant effect on the adhesion behavior of cells on the surface. Especially for the application of tissue engineering scaffold, the pore size could have an influence on cell in-growth and subsequent proliferation. Micro-fabrication technology was used to generate specific topography to investigate the relationship between the cells and surface. In this study the pits-patterned surfaces of polystyrene (PS) film with diameters 2.2 and 0.45 microm were prepared by phase-separation, and the corresponding scale islands-patterned PLLA surface was prepared by a molding technique using the pits-patterned PS as a template. The adhesion and proliferation behavior of OCT-1 osteoblast-like cells morphology on the pits- and islands-patterned surface were characterized by SEM observation, cell attachment efficiency measurement and MTT assay. The results showed that the cell adhesion could be enhanced on PLLA and PS surface with nano-scale and micro-scale roughness compared to the smooth surfaces of the PLLA and PS. The OCT-1 osteoblast-like cells could grow along the surface with two different size islands of PLLA and grow inside the micro-scale pits of the PS. However, the proliferation of cells on the micro- and nano-scale patterned surface has not been enhanced compared with the controlled smooth surface.

Enhanced light absorption of solar cells and photodetectors by diffraction

DOEpatents

Zaidi, Saleem H.; Gee, James M.

2005-02-22

Enhanced light absorption of solar cells and photodetectors by diffraction is described. Triangular, rectangular, and blazed subwavelength periodic structures are shown to improve performance of solar cells. Surface reflection can be tailored for either broadband, or narrow-band spectral absorption. Enhanced absorption is achieved by efficient optical coupling into obliquely propagating transmitted diffraction orders. Subwavelength one-dimensional structures are designed for polarization-dependent, wavelength-selective absorption in solar cells and photodetectors, while two-dimensional structures are designed for polarization-independent, wavelength-selective absorption therein. Suitable one and two-dimensional subwavelength periodic structures can also be designed for broadband spectral absorption in solar cells and photodetectors. If reactive ion etching (RIE) processes are used to form the grating, RIE-induced surface damage in subwavelength structures can be repaired by forming junctions using ion implantation methods. RIE-induced surface damage can also be removed by post RIE wet-chemical etching treatments.

Mechanisms for Flow-Enhanced Cell Adhesion

PubMed Central

Zhu, Cheng; Yago, Tadayuki; Lou, Jizhong; Zarnitsyna, Veronika I.; McEver, Rodger P.

2009-01-01

Cell adhesion is mediated by specific receptor—ligand bonds. In several biological systems, increasing flow has been observed to enhance cell adhesion despite the increasing dislodging fluid shear forces. Flow-enhanced cell adhesion includes several aspects: flow augments the initial tethering of flowing cells to a stationary surface, slows the velocity and increases the regularity of rolling cells, and increases the number of rollingly adherent cells. Mechanisms for this intriguing phenomenon may include transport-dependent acceleration of bond formation and force-dependent deceleration of bond dissociation. The former includes three distinct transport modes: sliding of cell bottom on the surface, Brownian motion of the cell, and rotational diffusion of the interacting molecules. The latter involves a recently demonstrated counterintuitive behavior called catch bonds where force prolongs rather than shortens the lifetimes of receptor—ligand bonds. In this article, we summarize our recently published data that used dimensional analysis and mutational analysis to elucidate the above mechanisms for flow-enhanced leukocyte adhesion mediated by L-selectinligand interactions. PMID:18299992

Design of the sample cell in near-field surface-enhanced Raman scattering by finite difference time domain method

NASA Astrophysics Data System (ADS)

Li, Yaqin; Jian, Guoshu; Wu, Shifa

2006-11-01

The rational design of the sample cell may improve the sensitivity of surface-enhanced Raman scattering (SERS) detection in a high degree. Finite difference time domain (FDTD) simulations of the configuration of Ag film-Ag particles illuminated by plane wave and evanescent wave are performed to provide physical insight for design of the sample cell. Numerical solutions indicate that the sample cell can provide more "hot spots' and the massive field intensity enhancement occurs in these "hot spots'. More information on the nanometer character of the sample can be got because of gradient-field Raman (GFR) of evanescent wave.

Improved performance of flexible amorphous silicon solar cells with silver nanowires

NASA Astrophysics Data System (ADS)

Chen, Y. R.; Li, Z. Q.; Chen, X. H.; Liu, C.; Ye, X. J.; Wang, Z. B.; Sun, Z.; Huang, S. M.

2012-12-01

A novel hybrid electrode structure using Ag nanowires (NWs) to create surface plasmons to enhance light trapping is designed and applied on the front surface of hydrogenated amorphous silicon (a-Si:H) solar cells on steel substrates, targeting broad-band absorption enhancements. Ag NWs were synthesized using a soft and self-seeding process. The produced Ag NWs were deposited on indium tin oxide (ITO) glass substrates or the ITO layers of the as-prepared flexible a-Si:H solar cells to form Ag NW-ITO hybrid electrodes. The Ag NW-ITO hybrid electrodes were optimized to achieve maximum optical enhancement using surface plasmons and obtain good electrical contacts in cells. Finite-element electromagnetic simulations confirmed that the presence of the Ag NWs resulted in increased electromagnetic fields within the a-Si:H layer. Compared to the cell with conventional ITO electrode, the measured quantum efficiency of the best performing a-Si:H cell shows an obvious enhancement in the wavelength range from 330 nm to 600 nm. The cell based on the optimized Ag NW-ITO demonstrates an increase about 4% in short-circuit current density and over 6% in power conversion efficiency under AM 1.5 illumination.

Surface enhanced Raman scattering analyses of individual silver nanoaggregates on living single yeast cell wall

NASA Astrophysics Data System (ADS)

Sujith, Athiyanathil; Itoh, Tamitake; Abe, Hiroko; Anas, Abdul Aziz; Yoshida, Kenichi; Biju, Vasudevanpillai; Ishikawa, Mitsuru

2008-03-01

We labeled the living yeast cell surface (Saccharomyces cerevisiae strain W303-1A) by silver nanoparticles which can form nanoaggregates and found to show surface enhanced Raman scattering (SERS) activity. Blinking of SERS and its polarization dependence reveal that SERS signals are from amplified electromagnetic field at nanometric Ag nanoparticles gaps with single or a few molecules sensitivity. We tentatively assigned SERS spectra from a yeast cell wall to mannoproteins. Nanoaggregate-by-nanoaggregate variations and temporal fluctuations of SERS spectra are discussed in terms of inhomogeneous mannoprotein distribution on a cell wall and possible ways of Ag nanoaggregate adsorption, respectively.

Enhancement of local surface plasmon resonance (LSPR) effect by biocompatible metal clustering based on ZnO nanorods in Raman measurements.

PubMed

Lee, Sanghwa; Lee, Seung Ho; Paulson, Bjorn; Lee, Jae-Chul; Kim, Jun Ki

2018-06-20

The development of size-selective and non-destructive detection techniques for nanosized biomarkers has many reasons, including the study of living cells and diagnostic applications. We present an approach for Raman signal enhancement on biocompatible sensing chips based on surface enhancement Raman spectroscopy (SERS). A sensing chip was fabricated by forming a ZnO-based nanorod structure so that the Raman enhancement occurred at a gap of several tens to several hundred nanometers. The effect of coffee-ring formation was eliminated by introducing the porous ZnO nanorods for the bio-liquid sample. A peculiarity of this approach is that the gold sputtered on the ZnO nanorods initially grows at their heads forming clusters, as confirmed by secondary electron microscopy. This clustering was verified by finite element analysis to be the main factor for enhancement of local surface plasmon resonance (LSPR). This clustering property and the ability to adjust the size of the nanorods enabled the signal acquisition points to be refined using confocal based Raman spectroscopy, which could be applied directly to the sensor chip based on the optimization process in this experiment. It was demonstrated by using common cancer cell lines that cell growth was high on these gold-clad ZnO nanorod-based surface-enhanced Raman substrates. The porosity of the sensing chip, the improved structure for signal enhancement, and the cell assay make these gold-coated ZnO nanorods substrates promising biosensing chips with excellent potential for detecting nanometric biomarkers secreted by cells. Copyright © 2018 Elsevier B.V. All rights reserved.

Regulation of T-lymphocyte motility, adhesion and de-adhesion by a cell surface mechanism directed by low density lipoprotein receptor-related protein 1 and endogenous thrombospondin-1.

PubMed

Talme, Toomas; Bergdahl, Eva; Sundqvist, Karl-Gösta

2014-06-01

T lymphocytes are highly motile and constantly reposition themselves between a free-floating vascular state, transient adhesion and migration in tissues. The regulation behind this unique dynamic behaviour remains unclear. Here we show that T cells have a cell surface mechanism for integrated regulation of motility and adhesion and that integrin ligands and CXCL12/SDF-1 influence motility and adhesion through this mechanism. Targeting cell surface-expressed low-density lipoprotein receptor-related protein 1 (LRP1) with an antibody, or blocking transport of LRP1 to the cell surface, perturbed the cell surface distribution of endogenous thrombospondin-1 (TSP-1) while inhibiting motility and potentiating cytoplasmic spreading on intercellular adhesion molecule 1 (ICAM-1) and fibronectin. Integrin ligands and CXCL12 stimulated motility and enhanced cell surface expression of LRP1, intact TSP-1 and a 130,000 MW TSP-1 fragment while preventing formation of a de-adhesion-coupled 110 000 MW TSP-1 fragment. The appearance of the 130 000 MW TSP-1 fragment was inhibited by the antibody that targeted LRP1 expression, inhibited motility and enhanced spreading. The TSP-1 binding site in the LRP1-associated protein, calreticulin, stimulated adhesion to ICAM-1 through intact TSP-1 and CD47. Shear flow enhanced cell surface expression of intact TSP-1. Hence, chemokines and integrin ligands up-regulate a dominant motogenic pathway through LRP1 and TSP-1 cleavage and activate an associated adhesion pathway through the LRP1-calreticulin complex, intact TSP-1 and CD47. This regulation of T-cell motility and adhesion makes pro-adhesive stimuli favour motile responses, which may explain why T cells prioritize movement before permanent adhesion.

Enhancing Efficiency of Perovskite Solar Cells via Surface Passivation with Graphene Oxide Interlayer.

PubMed

Li, Hao; Tao, Leiming; Huang, Feihong; Sun, Qiang; Zhao, Xiaojuan; Han, Junbo; Shen, Yan; Wang, Mingkui

2017-11-08

Perovskite solar cells have been demonstrated as promising low-cost and highly efficient next-generation solar cells. Enhancing V OC by minimization the interfacial recombination kinetics can further improve device performance. In this work, we for the first time reported on surface passivation of perovskite layers with chemical modified graphene oxides, which act as efficient interlayer to reduce interfacial recombination and enhance hole extraction as well. Our modeling points out that the passivation effect mainly comes from the interaction between functional group (4-fluorophenyl) and under-coordinated Pb ions. The resulting perovskite solar cells achieved high efficient power conversion efficiency of 18.75% with enhanced high open circuit V OC of 1.11 V. Ultrafast spectroscopy, photovoltage/photocurrent transient decay, and electronic impedance spectroscopy characterizations reveal the effective passivation effect and the energy loss mechanism. This work sheds light on the importance of interfacial engineering on the surface of perovskite layers and provides possible ways to improve device efficiency.

Surface design of antibody-immobilized thermoresponsive cell culture dishes for recovering intact cells by low-temperature treatment.

PubMed

Kobayashi, Jun; Hayashi, Masaki; Ohno, Takahiro; Nishi, Masanori; Arisaka, Yoshinori; Matsubara, Yoshinori; Kakidachi, Hiroshi; Akiyama, Yoshikatsu; Yamato, Masayuki; Horii, Akihiro; Okano, Teruo

2014-11-01

Antibody-immobilized thermoresponsive poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide) [poly(IPAAm-co-CIPAAm)]-grafted cell culture surfaces were designed to enhance both the initial adhesion of weakly adhering cells and the ability of cells to detach in response to low temperature through the regulation of affinity binding between immobilized antibodies and antigens on the cellular surface. Ty-82 cells and neonatal normal human dermal fibroblasts (NHDFs), which express CD90 on the cell surface, adhered to anti-CD90 antibody-immobilized thermoresponsive surfaces at 37°C, a condition at which the grafted thermoresponsive polymer chains shrank. Adherent Ty-82 cells were detached from the surfaces by lowering the temperature to 20°C and applying external forces, such as pipetting, whereas cultured NHDF sheets spontaneously detached themselves from the surface in response to reduced temperature alone. When the temperature was decreased to 20°C, the swelling of grafted thermoresponsive polymer chains weakened the affinity binding between immobilized antibody and antigen on the cells due to the increasing steric hindrance of the polymer chains around the antigen-recognition site of the immobilized antibodies. No contamination was detected on cells harvested from covalently immobilized antibodies on the culture surfaces by low-temperature treatment, whereas a carryover of the antibody and avidin from the avidin-biotin binding surface was observed. Furthermore, the initial adhesion of adipose tissue-derived cells, which adhere weakly to PIPAAm-grafted surfaces, was enhanced on the antibody-immobilized thermoresponsive surfaces. © 2013 Wiley Periodicals, Inc.

Surface-enhanced Raman scattering (SERS) imaging of alkyne-tagged small molecule drug in live cells with endocytosed gold nanoparticles

NASA Astrophysics Data System (ADS)

Ando, Jun; Sekiya, Takumasa; Ka, Den; Yamakoshi, Hiroyuki; Dodo, Kosuke; Sodeoka, Mikiko; Kawata, Satoshi; Fujita, Katsumasa

2017-02-01

We propose the combination of alkyne-tag and surface-enhanced Raman scattering (SERS) spectroscopy to perform highly-sensitive and selective drug imaging in live cells. Gold nanoparticles are introduced in lysosomes through endocytosis as SERS agents, and the alkyne-tagged drugs are subsequently administered in cells. Raman microscopic observation reveals the arrival of drug in lysosome through enhanced Raman signal of alkyne. Since the peak of alkyne appears in Raman-silent region of biomolecules, selective detection of drugs is possible without background signal of endogenous molecules. From endocytosed gold nanoparticles in living HeLa cells, we observed distinct Raman signal from alkyne-tagged inhibitor of lysosomal enzyme.

Enhanced human bone marrow mesenchymal stem cell functions on cathodic arc plasma-treated titanium.

PubMed

Zhu, Wei; Teel, George; O'Brien, Christopher M; Zhuang, Taisen; Keidar, Michael; Zhang, Lijie Grace

2015-01-01

Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium's osseointegration involves inducing bio-mimetic nanotopography to enhance cell-implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC) attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications.

Glycosylation controls cooperative PECAM-VEGFR2-β3 integrin functions at the endothelial surface for tumor angiogenesis.

PubMed

Imamaki, Rie; Ogawa, Kazuko; Kizuka, Yasuhiko; Komi, Yusuke; Kojima, Soichi; Kotani, Norihiro; Honke, Koichi; Honda, Takashi; Taniguchi, Naoyuki; Kitazume, Shinobu

2018-05-02

Most of the angiogenesis inhibitors clinically used in cancer treatment target the vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathway. However, the current strategies for treating angiogenesis have limited efficacy. The issue of how to treat angiogenesis and endothelial dysfunction in cancer remains a matter of substantial debate. Here we demonstrate a glycosylation-dependent regulatory mechanism for tumor angiogenesis. St6gal1 -/- mice, lacking the α2,6-sialylation enzyme, were shown to exhibit impaired tumor angiogenesis through enhanced endothelial apoptosis. In a previous study, St6gal1 -/- endothelial cells exhibited a reduction in the cell surface residency of platelet endothelial cell adhesion molecule (PECAM). In this study, we found that cooperative functionality of PECAM-VEGFR2-integrin β3 was disturbed in St6gal1 -/- mice. First, cell surface PECAM-VEGFR2 complexes were lost, and both VEGFR2 internalization and the VEGFR-dependent signaling pathway were enhanced. Second, enhanced anoikis was observed, suggesting that the absence of α2,6-sialic acid leads to dysregulated integrin signaling. Notably, ectopic expression of PECAM increased cell surface integrin-β3, indicating that the reduction of cell surface integrin-β3 involves loss-of-endothelial PECAM. The results suggest that the cell surface stability of these glycoproteins is significantly reduced by the lack of α2,6-sialic acid, leading to abnormal signal transduction. The present findings highlight that α2,6-sialylation is critically involved in endothelial survival by controlling the cell surface stability and signal transduction of angiogenic molecules, and could be a novel target for anti-angiogenesis therapy.

SERS imaging of cell-surface biomolecules metabolically labeled with bioorthogonal Raman reporters.

PubMed

Xiao, Ming; Lin, Liang; Li, Zefan; Liu, Jie; Hong, Senlian; Li, Yaya; Zheng, Meiling; Duan, Xuanming; Chen, Xing

2014-08-01

Live imaging of biomolecules with high specificity and sensitivity as well as minimal perturbation is essential for studying cellular processes. Here, we report the development of a bioorthogonal surface-enhanced Raman scattering (SERS) imaging approach that exploits small Raman reporters for visualizing cell-surface biomolecules. The cells were cultured and imaged by SERS microscopy on arrays of Raman-enhancing nanoparticles coated on silicon wafers or glass slides. The Raman reporters including azides, alkynes, and carbondeuterium bonds are small in size and spectroscopically bioorthogonal (background-free). We demonstrated that various cell-surface biomolecules including proteins, glycans, and lipids were metabolically incorporated with the corresponding precursors bearing a Raman reporter and visualized by SERS microscopy. The coupling of SERS microscopy with bioorthogonal Raman reporters expands the capabilities of live-cell microscopy beyond the modalities of fluorescence and label-free imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced adhesion of osteoblastic cells on polystyrene films by independent control of surface topography and wettability.

PubMed

Yang, Seung Yun; Kim, Eung-Sam; Jeon, Gumhye; Choi, Kwan Yong; Kim, Jin Kon

2013-04-01

We independently controlled surface topography and wettability of polystyrene (PS) films by CF4 and oxygen plasma treatments, respectively, to evaluate the adhesion and proliferation of human fetal osteoblastic (hFOB) cells on the films. Among the CF4 plasma-treated PS films with the average surface roughness ranging from 0.9 to 70 nm, the highest adhesion of hFOB cells was observed on a PS film with roughness of ~11 nm. When this film was additionally treated by oxygen plasma to provide a hydrophilic surface with a contact angle less than 10°, the proliferation of bone-forming cell was further enhanced. Thus, the plasma-based independent modification of PS film into an optimum nanotexture for human osteoblast cells could be appplied to materials used in bone tissue engineering. Copyright © 2012 Elsevier B.V. All rights reserved.

Power enhancement of a μl-scale microbial fuel cells by surface roughness

NASA Astrophysics Data System (ADS)

Kim, Jihoon; Hwan Ko, Jin; Lee, Jaehyun; Jun Kim, Min; Byun, Doyoung

2014-06-01

In recent years, microbial fuel cells (MFCs) have gained much attention due to their potential to generate energy in a sustainable manner from living microorganisms. Research has shown that electrode design is a critical factor for MFCs power enhancement. In this study, we designed and fabricated MFCs energy-harvesting devices with living bacteria, and we investigated the effect of the surface roughness of the electrodes on power generation. In batch experiments of our MFCs, we found that the total power delivered could be enhanced using electrodes having rough surfaces with protruded micro-structures relative to that of electrodes with a flat surface. This was due to the delayed acidification resulting from the changes in bio-film formation between them.

Change in surface properties of zirconia and initial attachment of osteoblastlike cells with hydrophilic treatment.

PubMed

Watanabe, Hiroaki; Saito, Kensuke; Kokubun, Katsutoshi; Sasaki, Hodaka; Yoshinari, Masao

2012-01-01

The objectives of this study were to characterize change in surface properties of tetragonal zirconia polycrystals (TZP) after hydrophilic treatment, and to determine the effect of such changes on initial attachment of osteoblast-like cells. Roughened surfaces were produced by alumina-blasting and acid-etching. Hydrophilic treatment comprised application of immediately after blasting and acid-etching (Blast/Etch), oxygen plasma (O2-Plasma), ultraviolet light (UV). Specimens stored in air were used as a control. The water contact angle was determined and surface analysis was performed using an X-ray photoelectron spectroscopy. Blast/Etch, O2-Plasma and UV specimens showed superhydrophilicity, and these hydrophilic treatments to TZP elicited a marked decrease in carbon content and an increase in hydroxyl groups. Hydrophilic treatments enhanced initial attachment of osteoblast-like cells and a change in cell morphologies. These results indicate that Blast/Etch, O2-Plasma, or UV treatment has potential in the creation and maintenance of superhydrophilic surfaces and enhancing initial attachment of osteoblast-like cells.

Enhanced cell attachment and hemocompatibility of titanium by nanoscale surface modification through severe plastic integration of magnesium-rich islands and porosification.

PubMed

Rezaei, Masoud; Tamjid, Elnaz; Dinari, Ali

2017-10-11

Besides the wide applications of titanium and its alloys for orthopedic and biomedical implants, the biocompatible nature of titanium has emerged various surface modification techniques to enhance its bioactivity and osteointegration with living tissues. In this work, we present a new procedure for nanoscale surface modification of titanium implants by integration of magnesium-rich islands combined with controlled formation of pores and refinement of the surface grain structure. Through severe plastic deformation of the titanium surface with fine magnesium hydride powder, Mg-rich islands with varying sizes ranging from 100 nm to 1000 nm can be integrated inside a thin surface layer (100-500 µm) of the implant. Selective etching of the surface forms a fine structure of surface pores which their average size varies in the range of 200-500 nm depending on the processing condition. In vitro biocompatibility and hemocompatibility assays show that the Mg-rich islands and the induced surface pores significantly enhance cell attachment and biocompatibility without an adverse effect on the cell viability. Therefore, severe plastic integration of Mg-rich islands on titanium surface accompanying with porosification is a new and promising procedure with high potential for nanoscale modification of biomedical implants.

Role of Glucosyltransferase B in Interactions of Candida albicans with Streptococcus mutans and with an Experimental Pellicle on Hydroxyapatite Surfaces ▿ †

PubMed Central

Gregoire, S.; Xiao, J.; Silva, B. B.; Gonzalez, I.; Agidi, P. S.; Klein, M. I.; Ambatipudi, K. S.; Rosalen, P. L.; Bauserman, R.; Waugh, R. E.; Koo, H.

2011-01-01

Candida albicans and mutans streptococci are frequently detected in dental plaque biofilms from toddlers afflicted with early childhood caries. Glucosyltransferases (Gtfs) secreted by Streptococcus mutans bind to saliva-coated apatite (sHA) and to bacterial surfaces, synthesizing exopolymers in situ, which promote cell clustering and adherence to tooth enamel. We investigated the potential role Gtfs may play in mediating the interactions between C. albicans SC5314 and S. mutans UA159, both with each other and with the sHA surface. GtfB adhered effectively to the C. albicans yeast cell surface in an enzymatically active form, as determined by scintillation spectroscopy and fluorescence imaging. The glucans formed on the yeast cell surface were more susceptible to dextranase than those synthesized in solution or on sHA and bacterial cell surfaces (P < 0.05), indicating an elevated α-1,6-linked glucose content. Fluorescence imaging revealed that larger numbers of S. mutans cells bound to C. albicans cells with glucans present on their surface than to yeast cells without surface glucans (uncoated). The glucans formed in situ also enhanced C. albicans interactions with sHA, as determined by a novel single-cell micromechanical method. Furthermore, the presence of glucan-coated yeast cells significantly increased the accumulation of S. mutans on the sHA surface (versus S. mutans incubated alone or mixed with uncoated C. albicans; P < 0.05). These data reveal a novel cross-kingdom interaction that is mediated by bacterial GtfB, which readily attaches to the yeast cell surface. Surface-bound GtfB promotes the formation of a glucan-rich matrix in situ and may enhance the accumulation of S. mutans on the tooth enamel surface, thereby modulating the development of virulent biofilms. PMID:21803906

Photovoltaic cell and production thereof

DOEpatents

Narayanan, Srinivasamohan [Gaithersburg, MD; Kumar, Bikash [Bangalore, IN

2008-07-22

An efficient photovoltaic cell, and its process of manufacture, is disclosed wherein the back surface p-n junction is removed from a doped substrate having an oppositely doped emitter layer. A front surface and edges and optionally the back surface periphery are masked and a back surface etch is performed. The mask is not removed and acts as an anti-reflective coating, a passivating agent, or both. The photovoltaic cell retains an untextured back surface whether or not the front is textured and the dopant layer on the back surface is removed to enhance the cell efficiency. Optionally, a back surface field is formed.

ITO/gold nanoparticle/RGD peptide composites to enhance electrochemical signals and proliferation of human neural stem cells.

PubMed

Kim, Tae-Hyung; El-Said, Waleed Ahmed; An, Jeung Hee; Choi, Jeong-Woo

2013-04-01

A cell chip composed of ITO, gold nanoparticles (GNP) and RGD-MAP-C peptide composites was fabricated to enhance the electrochemical signals and proliferation of undifferentiated human neural stem cells (HB1.F3). The structural characteristics of the fabricated surfaces were confirmed by both scanning electron microscopy and surface-enhanced Raman spectroscopy. HB1.F3 cells were allowed to attach to various composites electrodes in the cell chip and the material-dependent effects on electrochemical signals and cell proliferation were analyzed. The ITO/60 nm GNP/RGD-MAP-C composite electrode was found to be the best material in regards to enhancing the voltammetric signals of HB1.F3 cells when exposed to cyclic voltammetry, as well as for increasing cell proliferation. Differential pulse voltammetry was performed to evaluate the adverse effects of doxorubicin on HB1.F3 cells. In these experiments, negative correlations between cell viability and chemical concentrations were obseved, which were more sensitive than MTT viability assay especially at low concentrations (<0.1 μg/mL). In this basic science study, a cell chip composed of ITO, gold nanoparticles and RGD-MAP-C peptide composites was fabricated to enhance electrochemical signals and proliferation of undifferentiated human neural stem cells (HB1.F3). The ITO/60 nm GNP/RGD-MAP-C composite electrode was found to best enhance the voltammetric signals of the studied cells. Copyright © 2013 Elsevier Inc. All rights reserved.

ZnT-1 enhances the activity and surface expression of T-type calcium channels through activation of Ras-ERK signaling.

PubMed

Mor, Merav; Beharier, Ofer; Levy, Shiri; Kahn, Joy; Dror, Shani; Blumenthal, Daniel; Gheber, Levi A; Peretz, Asher; Katz, Amos; Moran, Arie; Etzion, Yoram

2012-07-15

Zinc transporter-1 (ZnT-1) is a putative zinc transporter that confers cellular resistance from zinc toxicity. In addition, ZnT-1 has important regulatory functions, including inhibition of L-type calcium channels and activation of Raf-1 kinase. Here we studied the effects of ZnT-1 on the expression and function of T-type calcium channels. In Xenopus oocytes expressing voltage-gated calcium channel (CaV) 3.1 or CaV3.2, ZnT-1 enhanced the low-threshold calcium currents (I(caT)) to 182 ± 15 and 167.95 ± 9.27% of control, respectively (P < 0.005 for both channels). As expected, ZnT-1 also enhanced ERK phosphorylation. Coexpression of ZnT-1 and nonactive Raf-1 blocked the ZnT-1-mediated ERK phosphorylation and abolished the ZnT-1-induced augmentation of I(caT). In mammalian cells (Chinese hamster ovary), coexpression of CaV3.1 and ZnT-1 increased the I(caT) to 166.37 ± 6.37% compared with cells expressing CaV3.1 alone (P < 0.01). Interestingly, surface expression measurements using biotinylation or total internal reflection fluorescence microscopy indicated marked ZnT-1-induced enhancement of CaV3.1 surface expression. The MEK inhibitor PD-98059 abolished the ZnT-1-induced augmentation of surface expression of CaV3.1. In cultured murine cardiomyocytes (HL-1 cells), transient exposure to zinc, leading to enhanced ZnT-1 expression, also enhanced the surface expression of endogenous CaV3.1 channels. Consistently, in these cells, endothelin-1, a potent activator of Ras-ERK signaling, enhanced the surface expression of CaV3.1 channels in a PD-98059-sensitive manner. Our findings indicate that ZnT-1 enhances the activity of CaV3.1 and CaV3.2 through activation of Ras-ERK signaling. The augmentation of CaV3.1 currents by Ras-ERK activation is associated with enhanced trafficking of the channel to the plasma membrane.

Alkali-templated surface nanopatterning of chalcogenide thin films: a novel approach toward solar cells with enhanced efficiency.

PubMed

Reinhard, Patrick; Bissig, Benjamin; Pianezzi, Fabian; Hagendorfer, Harald; Sozzi, Giovanna; Menozzi, Roberto; Gretener, Christina; Nishiwaki, Shiro; Buecheler, Stephan; Tiwari, Ayodhya N

2015-05-13

Concepts of localized contacts and junctions through surface passivation layers are already advantageously applied in Si wafer-based photovoltaic technologies. For Cu(In,Ga)Se2 thin film solar cells, such concepts are generally not applied, especially at the heterojunction, because of the lack of a simple method yielding features with the required size and distribution. Here, we show a novel, innovative surface nanopatterning approach to form homogeneously distributed nanostructures (<30 nm) on the faceted, rough surface of polycrystalline chalcogenide thin films. The method, based on selective dissolution of self-assembled and well-defined alkali condensates in water, opens up new research opportunities toward development of thin film solar cells with enhanced efficiency.

Enhanced human osteoblast cell adhesion and proliferation on 316 LS stainless steel by means of CO2 laser surface treatment.

PubMed

Hao, L; Lawrence, J; Phua, Y F; Chian, K S; Lim, G C; Zheng, H Y

2005-04-01

An effective and novel technique for improving the biocompatibility of a biograde 316 LS stainless steel through the application of CO(2) laser treatment to modify the surface properties of the material is described herein. Different surface properties, such as surface roughness, surface oxygen content, and surface energy for CO(2) laser-treated 316 LS stainless steel, untreated, and mechanically roughened samples were analyzed, and their effects on the wettability characteristics of the material were studied. It was found that modification of the wettability characteristics of the 316 LS stainless steel following CO(2) laser treatment was achieved. This improvement was identified as being mainly due to the change in the polar component of the surface energy. One-day cell adhesion tests showed that cells not only adhered and spread better, but also grew faster on the CO(2) laser-treated sample than on either the untreated or mechanically roughened sample. Further, compared with the untreated sample, MTT cell proliferation analysis revealed that the mechanically roughed surface resulted in a slight enhancement, and CO(2) laser treatment brought about a significant increase in cell proliferation. An increase in the wettability of the 316 LS stainless steel was observed to positively correlate with the cell proliferation. (c) 2004 Wiley Periodicals, Inc.

On the Interaction between Marine Boundary Layer Cellular Cloudiness and Surface Heat Fluxes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazil, J.; Feingold, G.; Wang, Hailong

2014-01-02

The interaction between marine boundary layer cellular cloudiness and surface uxes of sensible and latent heat is investigated. The investigation focuses on the non-precipitating closed-cell state and the precipitating open-cell state at low geostrophic wind speed. The Advanced Research WRF model is used to conduct cloud-system-resolving simulations with interactive surface fluxes of sensible heat, latent heat, and of sea salt aerosol, and with a detailed representation of the interaction between aerosol particles and clouds. The mechanisms responsible for the temporal evolution and spatial distribution of the surface heat fluxes in the closed- and open-cell state are investigated and explained. Itmore » is found that the horizontal spatial structure of the closed-cell state determines, by entrainment of dry free tropospheric air, the spatial distribution of surface air temperature and water vapor, and, to a lesser degree, of the surface sensible and latent heat flux. The synchronized dynamics of the the open-cell state drives oscillations in surface air temperature, water vapor, and in the surface fluxes of sensible and latent heat, and of sea salt aerosol. Open-cell cloud formation, cloud optical depth and liquid water path, and cloud and rain water path are identified as good predictors of the spatial distribution of surface air temperature and sensible heat flux, but not of surface water vapor and latent heat flux. It is shown that by enhancing the surface sensible heat flux, the open-cell state creates conditions by which it is maintained. While the open-cell state under consideration is not depleted in aerosol, and is insensitive to variations in sea-salt fluxes, it also enhances the sea-salt flux relative to the closed-cell state. In aerosol-depleted conditions, this enhancement may replenish the aerosol needed for cloud formation, and hence contribute to the perpetuation of the open-cell state as well. Spatial homogenization of the surface fluxes is found to have only a small effect on cloud properties in the investigated cases. This indicates that sub-grid scale spatial variability in the surface flux of sensible and latent heat and of sea salt aerosol may not be required in large scale and global models to describe marine boundary layer cellular cloudiness.« less

Impact of cell shape in hierarchically structured plant surfaces on the attachment of male Colorado potato beetles (Leptinotarsa decemlineata)

PubMed Central

Seidel, Robin; Bohn, Holger Florian; Speck, Thomas

2012-01-01

Summary Plant surfaces showing hierarchical structuring are frequently found in plant organs such as leaves, petals, fruits and stems. In our study we focus on the level of cell shape and on the level of superimposed microstructuring, leading to hierarchical surfaces if both levels are present. While it has been shown that epicuticular wax crystals and cuticular folds strongly reduce insect attachment, and that smooth papillate epidermal cells in petals improve the grip of pollinators, the impact of hierarchical surface structuring of plant surfaces possessing convex or papillate cells on insect attachment remains unclear. We performed traction experiments with male Colorado potato beetles on nine different plant surfaces with different structures. The selected plant surfaces showed epidermal cells with either tabular, convex or papillate cell shape, covered either with flat films of wax, epicuticular wax crystals or with cuticular folds. On surfaces possessing either superimposed wax crystals or cuticular folds we found traction forces to be almost one order of magnitude lower than on surfaces covered only with flat films of wax. Independent of superimposed microstructures we found that convex and papillate epidermal cell shapes slightly enhance the attachment ability of the beetles. Thus, in plant surfaces, cell shape and superimposed microstructuring yield contrary effects on the attachment of the Colorado potato beetle, with convex or papillate cells enhancing attachment and both wax crystals or cuticular folds reducing attachment. However, the overall magnitude of traction force mainly depends on the presence or absence of superimposed microstructuring. PMID:22428097

Regulation of MT1-MMP and MMP-2 by leptin in cardiac fibroblasts involves Rho/ROCK-dependent actin cytoskeletal reorganization and leads to enhanced cell migration.

PubMed

Schram, Kristin; Ganguly, Riya; No, Eun Kyung; Fang, Xiangping; Thong, Farah S L; Sweeney, Gary

2011-05-01

Altered leptin action has been implicated in the pathophysiology of heart failure in obesity, a hallmark of which is extracellular matrix remodeling. Here, we characterize the direct influence of leptin on matrix metalloproteinase (MMP) activity in primary adult rat cardiac fibroblasts and focus on elucidating the molecular mechanisms responsible. Leptin increased expression and cell surface localization of membrane type 1 (MT1)-MMP, measured by cell surface biotinylation assay and antibody-based colorimetric detection of an exofacial epitope in intact cells. Coimmunoprecipitation analysis showed that leptin also induced the formation of a cluster of differentiation 44/MT1-MMP complex. Qualitative analysis using rhodamine-conjugated phalloidin immunofluorescence indicated that leptin stimulated actin cytoskeletal reorganization and enhanced stress fiber formation. Hence, we analyzed activation of Ras homolog gene family (Rho), member A GTPase activity and found a rapid increase in response to leptin that corresponded with increased phosphorylation of cofilin. Quantitative analysis of cytoskeleton reorganization upon separation of globular and filamentous actin by differential centrifugation confirmed the significant increase in filamentous to globular actin ratio in response to leptin, which was prevented by pharmacological inhibition of Rho (C3 transferase) or its downstream effector kinase Rho-associated coiled-coil-forming protein kinase (ROCK) (Y-27632). Inhibition of Rho or ROCK also attenuated leptin-stimulated increases in cell surface MT1-MMP content. Pro-MMP-2 is a known MT1-MMP substrate, and we observed that enhanced cell surface MT1-MMP in response to leptin resulted in enhanced extracellular activation of pro-MMP-2 measured by gelatin zymography, which was again attenuated by inhibition of Rho or ROCK. Using wound scratch assays, we observed enhanced cell migration, but not proliferation, measured by 5-bromo2'-deoxy-uridine incorporation, in response to leptin, again via a Rho-dependent signaling mechanism. Our results suggest that leptin regulates myocardial matrix remodeling by regulating the cell surface localization of MT1-MMP in adult cardiac fibroblasts via Rho/ROCK-dependent actin cytoskeleton reorganization. Subsequent pro-MMP-2 activation then contributes to stimulation of cell migration.

Hydrogenated amorphous silicon coatings may modulate gingival cell response

NASA Astrophysics Data System (ADS)

Mussano, F.; Genova, T.; Laurenti, M.; Munaron, L.; Pirri, C. F.; Rivolo, P.; Carossa, S.; Mandracci, P.

2018-04-01

Silicon-based materials present a high potential for dental implant applications, since silicon has been proven necessary for the correct bone formation in animals and humans. Notably, the addition of silicon is effective to enhance the bioactivity of hydroxyapatite and other biomaterials. The present work aims to expand the knowledge of the role exerted by hydrogen in the biological interaction of silicon-based materials, comparing two hydrogenated amorphous silicon coatings, with different hydrogen content, as means to enhance soft tissue cell adhesion. To accomplish this task, the films were produced by plasma enhanced chemical vapor deposition (PECVD) on titanium substrates and their surface composition and hydrogen content were analyzed by means of X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectrophotometry (FTIR) respectively. The surface energy and roughness were measured through optical contact angle analysis (OCA) and high-resolution mechanical profilometry respectively. Coated surfaces showed a slightly lower roughness, compared to bare titanium samples, regardless of the hydrogen content. The early cell responses of human keratinocytes and fibroblasts were tested on the above mentioned surface modifications, in terms of cell adhesion, viability and morphometrical assessment. Films with lower hydrogen content were endowed with a surface energy comparable to the titanium surfaces. Films with higher hydrogen incorporation displayed a lower surface oxidation and a considerably lower surface energy, compared to the less hydrogenated samples. As regards mean cell area and focal adhesion density, both a-Si coatings influenced fibroblasts, but had no significant effects on keratinocytes. On the contrary, hydrogen-rich films increased manifolds the adhesion and viability of keratinocytes, but not of fibroblasts, suggesting a selective biological effect on these cells.

Cancer Cell Glycocalyx Mediates Mechanostransduction and Flow-Regulated Invasion

PubMed Central

Qazi, Henry; Palomino, Rocio; Shi, Zhong-Dong; Munn, Lance L.; Tarbell, John M.

2014-01-01

Mammalian cells are covered by a surface proteoglycan (glycocalyx) layer, and it is known that blood vessel-lining endothelial cells use the glycocalyx to sense and transduce the shearing forces of blood flow into intracellular signals. Tumor cells in vivo are exposed to forces from interstitial fluid flow that may affect metastatic potential but are not reproduced by most in vitro cell motility assays. We hypothesized that glycocalyx-mediated mechanotransduction of interstitial flow shear stress is an un-recognized factor that can significantly enhance metastatic cell motility and play a role in augmentation of invasion. Involvement of MMP levels, cell adhesion molecules (CD44, α3 integrin), and glycocalyx components (heparan sulfate and hyaluronan) were investigated in a cell/collagen gel suspension model designed to mimic the interstitial flow microenvironment. Physiologic levels of flow upregulated MMP levels and enhanced the motility of metastatic cells. Blocking the flow-enhanced expression of MMP actvity or adhesion molecules (CD44 and integrins) resulted in blocking the flow-enhanced migratory activity. The presence of a glycocalyx-like layer was verified around tumor cells, and the degradation of this layer by hyaluronidase and heparinase blocked the flow-regulated invasion. This study shows for the first time that interstitial flow enhancement of metastatic cell motility can be mediated by the cell surface glycocalyx – a potential target for therapeutics. PMID:24077103

Applied electric field enhances DRG neurite growth: influence of stimulation media, surface coating and growth supplements

NASA Astrophysics Data System (ADS)

Wood, Matthew D.; Willits, Rebecca Kuntz

2009-08-01

Electrical therapies have been found to aid repair of nerve injuries and have been shown to increase and direct neurite outgrowth during stimulation. This enhanced neural growth existed even after the electric field (EF) or stimulation was removed, but the factors that may influence the enhanced growth, such as stimulation media or surface coating, have not been fully investigated. This study characterized neurite outgrowth and branching under various conditions: EF magnitude and application time, ECM surface coating, medium during EF application and growth supplements. A uniform, low-magnitude EF (24 or 44 V m-1) was applied to dissociated chick embryo dorsal root ganglia seeded on collagen or laminin-coated surfaces. During the growth period, cells were either exposed to NGF or N2, and during stimulation cells were exposed to either unsupplemented media (Ca2+) or PBS (no Ca2+). Parallel controls for each experiment included cells exposed to the chamber with no stimulation and cells remaining outside the chamber. After brief electrical stimulation (10 min), neurite length significantly increased 24 h after application for all conditions studied. Of particular interest, increased stimulation time (10-100 min) further enhanced neurite length on laminin but not on collagen surfaces. Neurite branching was not affected by stimulation on any surface, and no preferential growth of neurites was noted after stimulation. Overall, the results of this report suggest that short-duration electric stimulation is sufficient to enhance neurite length under a variety of conditions. While further data are needed to fully elucidate a mechanism for this increased growth, these data suggest that one focus of those investigations should be the interaction between the growth cone and the substrata.

In vitro bioactivity of micro metal injection moulded stainless steel with defined surface features.

PubMed

Bitar, Malak; Friederici, Vera; Imgrund, Philipp; Brose, Claudia; Bruinink, Arie

2012-05-04

Micrometre- and nanometre-scale surface structuring with ordered topography features may dramatically enhance orthopaedic implant integration. In this study we utilised a previously optimised micron metal injection moulding (µ-MIM) process to produce medical grade stainless steel surfaces bearing micrometre scale, protruding, hemispheres of controlled dimensions and spatial distribution. Additionally, the structured surfaces were characterised by the presence of submicrometre surface roughness resulting from metal grain boundary formation. Following cytocompatibility (cytotoxicity) evaluation using 3T3 mouse fibroblast cell line, the effect on primary human cell functionality was assessed focusing on cell attachment, shape and cytoskeleton conformation. In this respect, and by day 7 in culture, significant increase in focal adhesion size was associated with the microstructured surfaces compared to the planar control. The morphological conformation of the seeded cells, as revealed by fluorescence cytoskeleton labelling, also appeared to be guided in the vertical dimension between the hemisphere bodies. Quantitative evaluation of this guidance took place using live cytoplasm fluorescence labelling and image morphometry analysis utilising both, compactness and elongation shape descriptors. Significant increase in cell compactness was associated with the hemisphere arrays indicating collective increase in focused cell attachment to the hemisphere bodies across the entire cell population. Micrometre-scale hemisphere array patterns have therefore influenced cell attachment and conformation. Such influence may potentially aid in enhancing key cellular events such as, for example, neo-osteogenesis on implanted orthopaedic surfaces.

Cell-surface display of enzymes by the yeast Saccharomyces cerevisiae for synthetic biology.

PubMed

Tanaka, Tsutomu; Kondo, Akihiko

2015-02-01

In yeast cell-surface displays, functional proteins, such as cellulases, are genetically fused to an anchor protein and expressed on the cell surface. Saccharomyces cerevisiae, which is often utilized as a cell factory for the production of fuels, chemicals, and proteins, is the most commonly used yeast for cell-surface display. To construct yeast cells with a desired function, such as the ability to utilize cellulose as a substrate for bioethanol production, cell-surface display techniques for the efficient expression of enzymes on the cell membrane need to be combined with metabolic engineering approaches for manipulating target pathways within cells. In this Minireview, we summarize the recent progress of biorefinery fields in the development and application of yeast cell-surface displays from a synthetic biology perspective and discuss approaches for further enhancing cell-surface display efficiency. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

Enhanced human bone marrow mesenchymal stem cell functions on cathodic arc plasma-treated titanium

PubMed Central

Zhu, Wei; Teel, George; O’Brien, Christopher M; Zhuang, Taisen; Keidar, Michael; Zhang, Lijie Grace

2015-01-01

Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium’s osseointegration involves inducing bio-mimetic nanotopography to enhance cell–implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC) attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications. PMID:26677327

Cellular Responses Evoked by Different Surface Characteristics of Intraosseous Titanium Implants

PubMed Central

Feller, Liviu; Jadwat, Yusuf; Khammissa, Razia A. G.; Meyerov, Robin; Lemmer, Johan

2015-01-01

The properties of biomaterials, including their surface microstructural topography and their surface chemistry or surface energy/wettability, affect cellular responses such as cell adhesion, proliferation, and migration. The nanotopography of moderately rough implant surfaces enhances the production of biological mediators in the peri-implant microenvironment with consequent recruitment of differentiating osteogenic cells to the implant surface and stimulates osteogenic maturation. Implant surfaces with moderately rough topography and with high surface energy promote osteogenesis, increase the ratio of bone-to-implant contact, and increase the bonding strength of the bone to the implant at the interface. Certain features of implant surface chemistry are also important in enhancing peri-implant bone wound healing. It is the purpose of this paper to review some of the more important features of titanium implant surfaces which have an impact on osseointegration. PMID:25767803

Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization.

PubMed

Han, Guang; Müller, Werner E G; Wang, Xiaohong; Lilja, Louise; Shen, Zhijian

2015-02-01

Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 μm. An additional mesoporous titania top layer following the contour of the macropores, of 100-200 nm thickness and with a pore diameter of 10nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of microbubble ligation to cells on ultrasound signal enhancement: implications for targeted imaging.

PubMed

Lankford, Miles; Behm, Carolyn Z; Yeh, James; Klibanov, Alexander L; Robinson, Peter; Lindner, Jonathan R

2006-10-01

Molecular imaging with contrast-enhanced ultrasound (CEU) relies on the detection of microbubbles retained in regions of disease. The aim of this study was to determine whether microbubble attachment to cells influences their acoustic signal generation and stability. Biotinylated microbubbles were attached to streptavidin-coated plates to derive density versus intensity relations during low- and high-power imaging. To assess damping from microbubble attachment to solid or cell surfaces, in vitro imaging was performed for microbubbles charge-coupled to methacrylate spheres and for vascular cell adhesion molecule-1-targeted microbubbles attached to endothelial cells. Signal enhancement on plates increased according to acoustic power and microbubble site density up to 300 mm. Microbubble signal was reduced by attachment to solid spheres during high- and low-power imaging but was minimally reduced by attachment to endothelial cells and only at low power. Attachment of targeted microbubbles to rigid surfaces results in damping and a reduction of their acoustic signal, which is not seen when microbubbles are attached to cells. A reliable concentration versus intensity relationship can be expected from microbubble attachment to 2-dimensional surfaces until a very high site density is reached.

Graphene coating on the surface of CoCrMo alloy enhances the adhesion and proliferation of bone marrow mesenchymal stem cells.

PubMed

Zhang, Qi; Li, Kewen; Yan, Jinhong; Wang, Zhuo; Wu, Qi; Bi, Long; Yang, Min; Han, Yisheng

2018-03-18

The objective was to investigate whether a graphene coating could improve the surface bioactivity of a cobalt-chromium-molybdenum-based alloy (CoCrMo). Graphene was produced by chemical vapor deposition and transferred to the surface of the CoCrMo alloy using an improved wet transfer approach. The morphology of the samples was observed, and the adhesion force and stabilization of graphene coating were analyzed by a nanoscratch test and ultrasonication test. In an in vitro study, the adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs) cultured on the samples were quantified via an Alamar Blue assay and cell counting kit-8 (CCK-8) assay. The results showed that it is feasible to apply graphene to modify the surface of a CoCrMo alloy, and the enhancement of the adhesion and proliferation of BMSCs was also shown in the present study. In conclusion, graphene exhibits considerable potential for enhancing the surface bioactivity of CoCrMo alloy. Copyright © 2018 Elsevier Inc. All rights reserved.

Aggregation of nanoparticles in endosomes and lysosomes produces surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Lucas, Leanne J.; Chen, Xiaoke K.; Smith, Aaron J.; Korbelik, Mladen; Zeng, Haishan; Lee, Patrick W. K.; Hewitt, Kevin Cecil

2015-01-01

The purpose of this study was to explore the use of surface-enhanced Raman spectroscopy (SERS) to image the distribution of epidermal growth factor receptor (EGFR) in cells. To accomplish this task, 30-nm gold nanoparticles (AuNPs) tagged with antibodies to EGFR (1012 per mL) were incubated with cells (106 per mL) of the A431 human epidermoid carcinoma and normal human bronchial epithelial cell lines. Using the 632.8-nm excitation line of a He-Ne laser, Raman spectroscopy measurements were performed using a point mapping scheme. Normal cells show little to no enhancement. SERS signals were observed inside the cytoplasm of A431 cells with an overall enhancement of 4 to 7 orders of magnitude. Raman intensity maps of the 1450 and 1583 cm-1 peaks correlate well with the expected distribution of EGFR and AuNPs, aggregated following uptake by endosomes and lysosomes. Spectral features from tyrosine and tryptophan residues dominate the SERS signals.

Generation of Ca2+-independent sortase A mutants with enhanced activity for protein and cell surface labeling

PubMed Central

Jeong, Hee-Jin; Abhiraman, Gita C.; Story, Craig M.

2017-01-01

Sortase A, a calcium-dependent transpeptidase derived from Staphylococcus aureus, is used in a broad range of applications, such as the conjugation of fluorescent dyes and other moieties to proteins or to the surface of eukaryotic cells. In vivo and cell-based applications of sortase have been somewhat limited by the large range of calcium concentrations, as well as by the often transient nature of protein-protein interactions in living systems. In order to use sortase A for cell labeling applications, we generated a new sortase A variant by combining multiple mutations to yield an enzyme that was both calcium-independent and highly active. This variant has enhanced activity for both N- and C-terminal labeling, as well as for cell surface modification under physiological conditions. PMID:29200433

Enhanced tumor cell isolation by a biomimetic combination of E-selectin and anti-EpCAM: implications for the effective separation of circulating tumor cells (CTCs).

PubMed

Myung, Ja Hye; Launiere, Cari A; Eddington, David T; Hong, Seungpyo

2010-06-01

The selective detection of circulating tumor cells (CTCs) is of significant clinical importance for the clinical diagnosis and prognosis of cancer metastasis. However, largely because of the extremely low number of CTCs (as low as 1 in 10(9) hematologic cells) in the blood of patients, effective detection and separation of the rare cells remain a tremendous challenge. Cell rolling is known to play a key role in physiological processes such as the recruitment of leukocytes to sites of inflammation and selectin-mediated CTC metastasis. Furthermore, because CTCs typically express the epithelial-cell adhesion molecule (EpCAM) on the surface whereas normal hematologic cells do not, substrates with immobilized antibody against EpCAM may specifically interact with CTCs. In this article, we created biomimetic surfaces functionalized with P- and E-selectin and anti-EpCAM that induce different responses in HL-60 (used as a model of leukocytes in this study) and MCF-7 (a model of CTCs) cells. HL-60 and MCF-7 cells showed different degrees of interaction with P-/E-selectin and anti-EpCAM at a shear stress of 0.32 dyn/cm(2). HL-60 cells exhibited rolling on P-selectin-immobilized substrates at a velocity of 2.26 +/- 0.28 microm/s whereas MCF-7 cells had no interaction with the surface. Both cell lines, however, had interactions with E-selectin, and the rolling velocity of MCF-7 cells (4.24 +/- 0.31 microm/s) was faster than that of HL-60 cells (2.12 +/- 0.15 microm/s). However, only MCF-7 cells interacted with anti-EpCAM-coated surfaces, forming stationary binding under flow. More importantly, the combination of the rolling (E-selectin) and stationary binding (anti-EpCAM) resulted in substantially enhanced separation capacity and capture efficiency (more than 3-fold enhancement), as compared to a surface functionalized solely with anti-EpCAM that has been commonly used for CTC capture. Our results indicate that cell-specific detection and separation may be achieved through mimicking the biological processes of combined dynamic cell rolling and stationary binding, which will likely lead to a CTC detection device with significantly enhanced specificity and sensitivity without a complex fabrication process.

Antibody enhancement of free-flow electrophoresis

NASA Technical Reports Server (NTRS)

Cohly, H. H. P.; Morrison, Dennis R.; Atassi, M. Zouhair

1988-01-01

Specific T cell clones and antibodies (ABs) were developed to study the efficiency of purifying closely associated T cells using Continuous Flow Electrophoresis System. Enhanced separation is accomplished by tagging cells first with ABs directed against the antigenic determinants on the cell surface and then with ABs against the Fc portion of the first AB. This second AB protrudes sufficiently beyond the cell membrane and glycocalyx to become the major overall cell surface potential determinant and thus causes a reduction of electrophoretic mobility. This project was divided into three phases. Phase one included development of specific T cell clones and separation of these specific clones. Phase two extends these principles to the separation of T cells from spleen cells and immunized lymph node cells. Phase three applies this double antibody technique to the separation of T cytotoxic cells from bone marrow.

Enhancement of cell-cell contact by a nonmitogenic lectin increases blastogenic response and IL-2 release by mitogen-stimulated mouse thymocytes.

PubMed

Favero, J; Marti, J; Dornand, J; Bonnafous, J C; Mani, J C

1986-03-01

We have examined the influence of peanut agglutinin (PNA), a lectin which agglutinates but does not stimulate mouse thymocytes, on the responsiveness of these cells to concanavalin A (Con A) or galactose oxidase stimulation. Binding low amounts of PNA on unseparated mouse thymocytes pretreated with neuraminidase highly enhances the mitogenic response and the level of interleukin 2 release in the culture medium upon Con A stimulation. We have shown that PNA present on the cell surface acts as a crosslinking agent which favors intercellular binding between accessory cells (macrophages) and thymocytes, leading through this enhanced cooperation by cell-cell contact to an enhanced blastogenic response.

Improvement of the recombination and infrared light losses by rear surface chemical polishing in silicon heterojunction solar cells

NASA Astrophysics Data System (ADS)

Yang, Xueliang; Zhang, Yi; Li, Feng; Sun, Yun

2017-06-01

Rear surface chemical polishing (RSCP) was investigated for the improvement of the internal reflection and surface passivation of heterojunction solar cells with intrinsic thin layers (HIT). The HIT solar cells without or with RSCP treatment were prepared by plasma-enhanced chemical vapor deposition and physical vapor deposition techniques. Scanning electron microscopy results showed that rounding of the spires and V-groove bottom of the pyramid as well as smoothing of incline surface of the pyramid were achieved. These effects would decrease the loss of infrared light transmittance and interface recombination at the rear surface of the cells. To experimentally corroborate these two points, two special geometries, ITO/c-Si/hydrogenated amorphous silicon (a-Si:H)/ITO and a-Si:H/c-Si/a-Si:H, were introduced as a test of the reflectance/transmittance spectra and the minority carrier lifetime. Weakened transmittance and enhanced lifetime were observed for the sample with RSCP, which are responsible for the improvement of J sc and V oc, respectively. Therefore, RSCP is a promising candidate for improving the performance of HIT solar cells.

Molecular imaging with targeted perfluorocarbon nanoparticles: Quantification of the concentration dependence of contrast enhancement for binding to sparse cellular epitopes

PubMed Central

Marsh, Jon N.; Partlow, Kathryn C.; Abendschein, Dana R.; Scott, Michael J.; Lanza, Gregory M.; Wickline, Samuel A.

2007-01-01

Targeted, liquid perfluorocarbon nanoparticles are effective agents for acoustic contrast enhancement of abundant cellular epitopes (e.g. fibrin in thrombi) and for lower prevalence binding sites, such as integrins associated with tumor neovasculature. In this study we sought to delineate the quantitative relationship between the extent of contrast enhancement of targeted surfaces and the density (and concentration) of bound perfluorocarbon (PFC) nanoparticles. Two dramatically different substrates were utilized for targeting. In one set of experiments, the surfaces of smooth, flat, avidin-coated agar disks were exposed to biotinylated nanoparticles to yield a thin layer of targeted contrast. For the second set of measurements, we targeted PFC nanoparticles applied in thicker layers to cultured smooth muscle cells expressing the transmembrane glycoprotein “tissue factor” at the cell surface. An acoustic microscope was used to characterize reflectivity for all samples as a function of bound PFC (determined via gas chromatography). We utilized a formulation of low-scattering nanoparticles having oil-based cores to compete against high-scattering PFC nanoparticles for binding, to elucidate the dependence of contrast enhancement on PFC concentration. The relationship between reflectivity enhancement and bound PFC content varied in a curvilinear fashion, and exhibited an apparent asymptote (approximately 16 dB and 9 dB enhancement for agar and cell samples, respectively) at the maximum concentrations (~150 μg and ~1000 μg PFOB for agar and cell samples, respectively). Samples targeted with only oil-based nanoparticles exhibited mean backscatter values that were nearly identical to untreated samples (<1 dB difference), confirming the oil particles’ low-scattering behavior. The results of this study indicate that substantial contrast enhancement with liquid perfluorocarbon nanoparticles can be realized even in cases of partial surface coverage (as might be encountered when targeting sparsely populated epitopes), or when targeting surfaces with locally irregular topography. Furthermore, it may be possible to assess the quantity of bound cellular epitopes through acoustic means. PMID:17434667

Diffusion and cellular uptake of drugs in live cells studied with surface-enhanced Raman scattering probes

NASA Astrophysics Data System (ADS)

Bálint, Štefan; Rao, Satish; Sánchez, Mónica Marro; Huntošová, Veronika; Miškovský, Pavol; Petrov, Dmitri

2010-03-01

An understanding of the mechanisms of drug diffusion and uptake through cellular membranes is critical for elucidating drug action and in the development of effective drug delivery systems. We study these processes for emodin, a potential anticancer drug, in live cancer cells using surface-enhanced Raman scattering. Micrometer-sized silica beads covered by nanosized silver colloids are passively embedded into the cell and used as sensors of the drug. We demonstrate that the technique offers distinct advantages: the possibility to study the kinetics of drug diffusion through the cellular membrane toward specific cell organelles, the detection of lower drug concentrations compared to fluorescence techniques, and less damage imparted on the cell.

Cell Adhesion on RGD-Displaying Knottins with Varying Numbers of Tryptophan Amino Acids to Tune the Affinity for Assembly on Cucurbit[8]uril Surfaces.

PubMed

Sankaran, Shrikrishnan; Cavatorta, Emanuela; Huskens, Jurriaan; Jonkheijm, Pascal

2017-09-05

Cell adhesion is studied on multivalent knottins, displaying RGD ligands with a high affinity for integrin receptors, that are assembled on CB[8]-methylviologen-modified surfaces. The multivalency in the knottins stems from the number of tryptophan amino acid moieties, between 0 and 4, that can form a heteroternary complex with cucurbit[8]uril (CB[8]) and surface-tethered methylviologen (MV 2+ ). The binding affinity of the knottins with CB[8] and MV 2+ surfaces was evaluated using surface plasmon resonance spectroscopy. Specific binding occurred, and the affinity increased with the valency of tryptophans on the knottin. Additionally, increased multilayer formation was observed, attributed to homoternary complex formation between tryptophan residues of different knottins and CB[8]. Thus, we were able to control the surface coverage of the knottins by valency and concentration. Cell experiments with mouse myoblast (C2C12) cells on the self-assembled knottin surfaces showed specific integrin recognition by the RGD-displaying knottins. Moreover, cells were observed to elongate more on the supramolecular knottin surfaces with a higher valency, and in addition, more pronounced focal adhesion formation was observed on the higher-valency knottin surfaces. We attribute this effect to the enhanced coverage and the enhanced affinity of the knottins in their interaction with the CB[8] surface. Collectively, these results are promising for the development of biomaterials including knottins via CB[8] ternary complexes for tunable interactions with cells.

Differential responses of osteoblast lineage cells to nanotopographically-modified, microroughened titanium-aluminum-vanadium alloy surfaces.

PubMed

Gittens, Rolando A; Olivares-Navarrete, Rene; McLachlan, Taylor; Cai, Ye; Hyzy, Sharon L; Schneider, Jennifer M; Schwartz, Zvi; Sandhage, Kenneth H; Boyan, Barbara D

2012-12-01

Surface structural modifications at the micrometer and nanometer scales have driven improved success rates of dental and orthopaedic implants by mimicking the hierarchical structure of bone. However, how initial osteoblast-lineage cells populating an implant surface respond to different hierarchical surface topographical cues remains to be elucidated, with bone marrow mesenchymal stem cells (MSCs) or immature osteoblasts as possible initial colonizers. Here we show that in the absence of any exogenous soluble factors, osteoblastic maturation of primary human osteoblasts (HOBs) but not osteoblastic differentiation of MSCs is strongly influenced by nanostructures superimposed onto a microrough Ti6Al4V (TiAlV) alloy. The sensitivity of osteoblasts to both surface microroughness and nanostructures led to a synergistic effect on maturation and local factor production. Osteoblastic differentiation of MSCs was sensitive to TiAlV surface microroughness with respect to production of differentiation markers, but no further enhancement was found when cultured on micro/nanostructured surfaces. Superposition of nanostructures to microroughened surfaces affected final MSC numbers and enhanced production of vascular endothelial growth factor (VEGF) but the magnitude of the response was lower than for HOB cultures. Our results suggest that the differentiation state of osteoblast-lineage cells determines the recognition of surface nanostructures and subsequent cell response, which has implications for clinical evaluation of new implant surface nanomodifications. Copyright © 2012 Elsevier Ltd. All rights reserved.

Differential Responses of Osteoblast Lineage Cells to Nanotopographically-Modified, Microroughened Titanium-Aluminum-Vanadium Alloy Surfaces

PubMed Central

Gittens, Rolando A.; Olivares-Navarrete, Rene; McLachlan, Taylor; Cai, Ye; Hyzy, Sharon L.; Schneider, Jennifer M.; Schwartz, Zvi; Sandhage, Kenneth H.; Boyan, Barbara D.

2013-01-01

Surface structural modifications at the micrometer and nanometer scales have driven improved success rates of dental and orthopaedic implants by mimicking the hierarchical structure of bone. However, how initial osteoblast-lineage cells populating an implant surface respond to different hierarchical surface topographical cues remains to be elucidated, with bone marrow mesenchymal stem cells (MSCs) or immature osteoblasts as possible initial colonizers. Here we show that in the absence of any exogenous soluble factors, osteoblastic maturation of primary human osteoblasts (HOBs) but not osteoblastic differentiation of MSCs is strongly influenced by nanostructures superimposed onto a microrough Ti6Al4V (TiAlV) alloy. The sensitivity of osteoblasts to both surface microroughness and nanostructures led to a synergistic effect on maturation and local factor production. Osteoblastic differentiation of MSCs was sensitive to TiAlV surface microroughness with respect to production of differentiation markers, but no further enhancement was found when cultured on micro/nanostructured surfaces. Superposition of nanostructures to microroughened surfaces affected final MSC numbers and enhanced production of vascular endothelial growth factor (VEGF) but the magnitude of the response was lower than for HOB cultures. Our results suggest that the differentiation state of osteoblast-lineage cells determines the recognition of surface nanostructures and subsequent cell response, which has implications for clinical evaluation of new implant surface nanomodifications. PMID:22989383

Nanostructured Polyaniline Coating on ITO Glass Promotes the Neurite Outgrowth of PC 12 Cells by Electrical Stimulation.

PubMed

Wang, Liping; Huang, Qianwei; Wang, Jin-Ye

2015-11-10

A conducting polymer polyaniline (PANI) with nanostructure was synthesized on indium tin oxide (ITO) glass. The effect of electrical stimulation on the proliferation and the length of neurites of PC 12 cells was investigated. The dynamic protein adsorption on PANI and ITO surfaces in a cell culture medium was also compared with and without electrical stimulation. The adsorbed proteins were characterized using SDS-PAGE. A PANI coating on ITO surface was shown with 30-50 nm spherical nanostructure. The number of PC 12 cells was significantly greater on the PANI/ITO surface than on ITO and plate surfaces after cell seeding for 24 and 36 h. This result confirmed that the PANI coating is nontoxic to PC 12 cells. The electrical stimulation for 1, 2, and 4 h significantly enhanced the cell numbers for both PANI and ITO conducting surfaces. Moreover, the application of electrical stimulation also improved the neurite outgrowth of PC 12 cells, and the number of PC 12 cells with longer neurite lengths increased obviously under electrical stimulation for the PANI surface. From the mechanism, the adsorption of DMEM proteins was found to be enhanced by electrical stimulation for both PANI/ITO and ITO surfaces. A new band 2 (around 37 kDa) was observed from the collected adsorbed proteins when PC 12 cells were cultured on these surfaces, and culturing PC 12 cells also seemed to increase the amount of band 1 (around 90 kDa). When immersing PANI/ITO and ITO surfaces in a DMEM medium without a cell culture, the number of band 3 (around 70 kDa) and band 4 (around 45 kDa) proteins decreased compared to that of PC 12 cell cultured surfaces. These results are valuable for the design and improvement of the material performance for neural regeneration.

Enhanced photovoltaic performance of inverted pyramid-based nanostructured black-silicon solar cells passivated by an atomic-layer-deposited Al2O3 layer.

PubMed

Chen, Hong-Yan; Lu, Hong-Liang; Ren, Qing-Hua; Zhang, Yuan; Yang, Xiao-Feng; Ding, Shi-Jin; Zhang, David Wei

2015-10-07

Inverted pyramid-based nanostructured black-silicon (BS) solar cells with an Al2O3 passivation layer grown by atomic layer deposition (ALD) have been demonstrated. A multi-scale textured BS surface combining silicon nanowires (SiNWs) and inverted pyramids was obtained for the first time by lithography and metal catalyzed wet etching. The reflectance of the as-prepared BS surface was about 2% lower than that of the more commonly reported upright pyramid-based SiNW BS surface over the whole of the visible light spectrum, which led to a 1.7 mA cm(-2) increase in short circuit current density. Moreover, the as-prepared solar cells were further passivated by an ALD-Al2O3 layer. The effect of annealing temperature on the photovoltaic performance of the solar cells was investigated. It was found that the values of all solar cell parameters including short circuit current, open circuit voltage, and fill factor exhibit a further increase under an optimized annealing temperature. Minority carrier lifetime measurements indicate that the enhanced cell performance is due to the improved passivation quality of the Al2O3 layer after thermal annealing treatments. By combining these two refinements, the optimized SiNW BS solar cells achieved a maximum conversion efficiency enhancement of 7.6% compared to the cells with an upright pyramid-based SiNWs surface and conventional SiNx passivation.

Magnetic Beads Enhance Adhesion of NIH 3T3 Fibroblasts: A Proof-of-Principle In Vitro Study for Implant-Mediated Long-Term Drug Delivery to the Inner Ear

PubMed Central

Aliuos, Pooyan; Schulze, Jennifer; Schomaker, Markus; Reuter, Günter; Stolle, Stefan R. O.; Werner, Darja; Ripken, Tammo; Lenarz, Thomas; Warnecke, Athanasia

2016-01-01

Introduction Long-term drug delivery to the inner ear may be achieved by functionalizing cochlear implant (CI) electrodes with cells providing neuroprotective factors. However, effective strategies in order to coat implant surfaces with cells need to be developed. Our vision is to make benefit of electromagnetic field attracting forces generated by CI electrodes to bind BDNF-secreting cells that are labelled with magnetic beads (MB) onto the electrode surfaces. Thus, the effect of MB-labelling on cell viability and BDNF production were investigated. Materials and Methods Murine NIH 3T3 fibroblasts—genetically modified to produce BDNF—were labelled with MB. Results Atomic force and bright field microscopy illustrated the internalization of MB by fibroblasts after 24 h of cultivation. Labelling cells with MB did not expose cytotoxic effects on fibroblasts and allowed adhesion on magnetic surfaces with sufficient BDNF release. Discussion Our data demonstrate a novel approach for mediating enhanced long-term adhesion of BDNF-secreting fibroblasts on model electrode surfaces for cell-based drug delivery applications in vitro and in vivo. This therapeutic strategy, once transferred to cells suitable for clinical application, may allow the biological modifications of CI surfaces with cells releasing neurotrophic or other factors of interest. PMID:26918945

Atomic layer deposition of ruthenium surface-coating on porous platinum catalysts for high-performance direct ethanol solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Jeong, Heon Jae; Kim, Jun Woo; Jang, Dong Young; Shim, Joon Hyung

2015-09-01

Pt-Ru bi-metallic catalysts are synthesized by atomic layer deposition (ALD) of Ru surface-coating on sputtered Pt mesh. The catalysts are evaluated in direct ethanol solid oxide fuel cells (DESOFCs) in the temperature range of 300-500 °C. Island-growth of the ALD Ru coating is confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy (XPS) analyses. The performance of the DESOFCs is evaluated based on the current-voltage output and electrochemical impedance spectroscopy. Genuine reduction of the polarization impedance, and enhanced power output with improved surface kinetics are achieved with the optimized ALD Ru surface-coating compared to bare Pt. The chemical composition of the Pt/ALD Ru electrode surface after fuel cell operation is analyzed via XPS. Enhanced cell performance is clearly achieved, attributed to the effective Pt/ALD Ru bi-metallic catalysis, including oxidation of Cdbnd O by Ru, and de-protonation of ethanol and cleavage of C-C bonds by Pt, as supported by surface morphology analysis which confirms formation of a large amount of carbon on bare Pt after the ethanol-fuel-cell test.

Transport governs flow-enhanced cell tethering through L-selectin at threshold shear.

PubMed

Yago, Tadayuki; Zarnitsyna, Veronika I; Klopocki, Arkadiusz G; McEver, Rodger P; Zhu, Cheng

2007-01-01

Flow-enhanced cell adhesion is a counterintuitive phenomenon that has been observed in several biological systems. Flow augments L-selectin-dependent adhesion by increasing the initial tethering of leukocytes to vascular surfaces and by strengthening their subsequent rolling interactions. Tethering or rolling might be influenced by physical factors that affect the formation or dissociation of selectin-ligand bonds. We recently demonstrated that flow enhanced rolling of L-selectin-bearing microspheres or neutrophils on P-selectin glycoprotein ligand-1 by force decreased bond dissociation. Here, we show that flow augmented tethering of these microspheres or cells to P-selectin glycoprotein ligand-1 by three transport mechanisms that increased bond formation: sliding of the sphere bottom on the surface, Brownian motion, and molecular diffusion. These results elucidate the mechanisms for flow-enhanced tethering through L-selectin.

The effects of hierarchical micro/nanosurfaces decorated with TiO2 nanotubes on the bioactivity of titanium implants in vitro and in vivo

PubMed Central

Ding, Xianglong; Zhou, Lei; Wang, Jingxu; Zhao, Qingxia; Lin, Xi; Gao, Yan; Li, Shaobing; Wu, Jingyi; Rong, Mingdeng; Guo, Zehong; Lai, Chunhua; Lu, Haibin; Jia, Fang

2015-01-01

In the present work, a hierarchical hybrid micro/nanostructured titanium surface was obtained by sandblasting with large grit and acid etching (SLA), and nanotubes of different diameters (30 nm, 50 nm, and 80 nm) were superimposed by anodization. The effect of each SLA-treated surface decorated with nanotubes (SLA + 30 nm, SLA + 50 nm, and SLA + 80 nm) on osteogenesis was studied in vitro and in vivo. The human MG63 osteosarcoma cell line was used for cytocompatibility evaluation, which showed that cell adhesion and proliferation were dramatically enhanced on SLA + 30 nm. In comparison with cells grown on the other tested surfaces, those grown on SLA + 80 nm showed an enhanced expression of osteogenesis-related genes. Cell spread was also enhanced on SLA + 80 nm. A canine model was used for in vivo evaluation of bone bonding. Histological examination demonstrated that new bone was formed more rapidly on SLA-treated surfaces with nanotubes (especially SLA + 80 nm) than on those without nanotubes. All of these results indicate that SLA + 80 nm is favorable for promoting the activity of osteoblasts and early bone bonding. PMID:26635472

Hydroxy-Al and cell-surface negativity are responsible for the enhanced sensitivity of Rhodotorula taiwanensis to aluminum by increased medium pH.

PubMed

Zhao, Xue Qiang; Bao, Xue Min; Wang, Chao; Xiao, Zuo Yi; Hu, Zhen Min; Zheng, Chun Li; Shen, Ren Fang

2017-10-01

Aluminum (Al) is ubiquitous and toxic to microbes. High Al 3+ concentration and low pH are two key factors responsible for Al toxicity, but our present results contradict this idea. Here, an Al-tolerant yeast strain Rhodotorula taiwanensis RS1 was incubated in glucose media containing Al with a continuous pH gradient from pH 3.1-4.2. The cells became more sensitive to Al and accumulated more Al when pH increased. Calculations using an electrostatic model Speciation Gouy Chapman Stern indicated that, the increased Al sensitivity of cells was associated with AlOH 2+ and Al(OH) 2 + rather than Al 3+ . The alcian blue (a positively charged dye) adsorption and zeta potential determination of cell surface indicated that, higher pH than 3.1 increased the negative charge and Al adsorption at the cell surface. Taken together, the enhanced sensitivity of R. taiwanensis RS1 to Al from pH 3.1-4.2 was associated with increased hydroxy-Al and cell-surface negativity.

Comprehensive design of omnidirectional high-performance perovskite solar cells

PubMed Central

Zhang, Yutao; Xuan, Yimin

2016-01-01

The comprehensive design approach is established with coupled optical-electrical simulation for perovskite-based solar cell, which emerged as one of the most promising competitors to silicon solar cell for its low-cost fabrication and high PCE. The selection of structured surface, effect of geometry parameters, incident angle-dependence and polarization-sensitivity are considered in the simulation. The optical modeling is performed via the finite-difference time-domain method whilst the electrical properties are obtained by solving the coupled nonlinear equations of Poisson, continuity, and drift-diffusion equations. The optical and electrical performances of five different structured surfaces are compared to select a best structured surface for perovskite solar cell. The effects of the geometry parameters on the optical and electrical properties of the perovskite cell are analyzed. The results indicate that the light harvesting is obviously enhanced by the structured surface. The electrical performance can be remarkably improved due to the enhanced light harvesting of the designed best structured surface. The angle-dependence for s- and p-polarizations is investigated. The structured surface exhibits omnidirectional behavior and favorable polarization-insensitive feature within a wide incident angle range. Such a comprehensive design approach can highlight the potential of perovskite cell for power conversion in the full daylight. PMID:27405419

Comprehensive design of omnidirectional high-performance perovskite solar cells.

PubMed

Zhang, Yutao; Xuan, Yimin

2016-07-13

The comprehensive design approach is established with coupled optical-electrical simulation for perovskite-based solar cell, which emerged as one of the most promising competitors to silicon solar cell for its low-cost fabrication and high PCE. The selection of structured surface, effect of geometry parameters, incident angle-dependence and polarization-sensitivity are considered in the simulation. The optical modeling is performed via the finite-difference time-domain method whilst the electrical properties are obtained by solving the coupled nonlinear equations of Poisson, continuity, and drift-diffusion equations. The optical and electrical performances of five different structured surfaces are compared to select a best structured surface for perovskite solar cell. The effects of the geometry parameters on the optical and electrical properties of the perovskite cell are analyzed. The results indicate that the light harvesting is obviously enhanced by the structured surface. The electrical performance can be remarkably improved due to the enhanced light harvesting of the designed best structured surface. The angle-dependence for s- and p-polarizations is investigated. The structured surface exhibits omnidirectional behavior and favorable polarization-insensitive feature within a wide incident angle range. Such a comprehensive design approach can highlight the potential of perovskite cell for power conversion in the full daylight.

Double-chimera proteins to enhance recruitment of endothelial cells and their progenitor cells.

PubMed

Behjati, M; Kazemi, M; Hashemi, M; Zarkesh-Esfahanai, S H; Bahrami, E; Hashemi-Beni, B; Ahmadi, R

2013-08-20

Enhanced attraction of selective vascular reparative cells is of great importance in order to increase vascular patency after endovascular treatments. We aimed to evaluate efficient attachment of endothelial cells and their progenitors on surfaces coated with mixture of specific antibodies, L-selectin and VE-cadherin, with prohibited platelet attachment. The most efficient conditions for coating of L-selectin-Fc chimera and VE-cadherin-Fc chimera proteins were first determined by protein coating on ELISA plates. The whole processes were repeated on titanium substrates, which are commonly used to coat stents. Endothelial progenitor cells (EPCs) and human umbilical vein endothelial cells (HUVECs) were isolated and characterized by flow cytometry. Cell attachment, growth, proliferation, viability and surface cytotoxicity were evaluated using nuclear staining and MTT assay. Platelet and cell attachment were evaluated using scanning electron microscopy. Optimal concentration of each protein for surface coating was 50 ng/ml. The efficacy of protein coating was both heat and pH independent. Calcium ions had significant impact on simultaneous dual-protein coating (P<0.05). Coating stability data revealed more than one year stability for these coated proteins at 4°C. L-selectin and VE-cadherin (ratio of 50:50) coated surface showed highest EPC and HUVEC attachment, viability and proliferation compared to single protein coated and non-coated titanium surfaces (P<0.05). This double coated surface did not show any cytotoxic effect. Surfaces coated with L-selectin and VE-cadherin are friendly surface for EPC and endothelial cell attachment with less platelet attachment. These desirable factors make the L-selectin and VE-cadherin coated surfaces perfect candidate endovascular device. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Laser-modified titanium surfaces enhance the osteogenic differentiation of human mesenchymal stem cells.

PubMed

Bressel, Tatiana A B; de Queiroz, Jana Dara Freires; Gomes Moreira, Susana Margarida; da Fonseca, Jéssyca T; Filho, Edson A; Guastaldi, Antônio Carlos; Batistuzzo de Medeiros, Silvia Regina

2017-11-28

Titanium surfaces have been modified by various approaches with the aim of improving the stimulation of osseointegration. Laser beam (Yb-YAG) treatment is a controllable and flexible approach to modifying surfaces. It creates a complex surface topography with micro and nano-scaled patterns, and an oxide layer that can improve the osseointegration of implants, increasing their usefulness as bone implant materials. Laser beam irradiation at various fluences (132, 210, or 235 J/cm 2 ) was used to treat commercially pure titanium discs to create complex surface topographies. The titanium discs were investigated by scanning electron microscopy, X-ray diffraction, and measurement of contact angles. The surface generated at a fluence of 235 J/cm 2 was used in the biological assays. The behavior of mesenchymal stem cells from an umbilical cord vein was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, a mineralization assay, and an alkaline phosphatase activity assay and by carrying out a quantitative real-time polymerase chain reaction for osteogenic markers. CHO-k1 cells were also exposed to titanium discs in the MTT assay. The best titanium surface was that produced by laser beam irradiation at 235 J/cm 2 fluence. Cell proliferation analysis revealed that the CHO-k1 and mesenchymal stem cells behaved differently. The laser-processed titanium surface increased the proliferation of CHO-k1 cells, reduced the proliferation of mesenchymal stem cells, upregulated the expression of the osteogenic markers, and enhanced alkaline phosphatase activity. The laser-treated titanium surface modulated cellular behavior depending on the cell type, and stimulated osteogenic differentiation. This evidence supports the potential use of laser-processed titanium surfaces as bone implant materials, and their use in regenerative medicine could promote better outcomes.

In vitro fibroblast and pre-osteoblastic cellular responses on laser surface modified Ti-6Al-4V.

PubMed

Chikarakara, Evans; Fitzpatrick, Patricia; Moore, Eric; Levingstone, Tanya; Grehan, Laura; Higginbotham, Clement; Vázquez, Mercedes; Bagga, Komal; Naher, Sumsun; Brabazon, Dermot

2014-12-29

The success of any implant, dental or orthopaedic, is driven by the interaction of implant material with the surrounding tissue. In this context, the nature of the implant surface plays a direct role in determining the long term stability as physico-chemical properties of the surface affect cellular attachment, expression of proteins, and finally osseointegration. Thus to enhance the degree of integration of the implant into the host tissue, various surface modification techniques are employed. In this work, laser surface melting of titanium alloy Ti-6Al-4V was carried out using a CO2 laser with an argon gas atmosphere. Investigations were carried out to study the influence of laser surface modification on the biocompatibility of Ti-6Al-4V alloy implant material. Surface roughness, microhardness, and phase development were recorded. Initial knowledge of these effects on biocompatibility was gained from examination of the response of fibroblast cell lines, which was followed by examination of the response of osteoblast cell lines which is relevant to the applications of this material in bone repair. Biocompatibility with these cell lines was analysed via Resazurin cell viability assay, DNA cell attachment assay, and alamarBlue metabolic activity assay. Laser treated surfaces were found to preferentially promote cell attachment, higher levels of proliferation, and enhanced bioactivity when compared to untreated control samples. These results demonstrate the tremendous potential of this laser surface melting treatment to significantly improve the biocompatibility of titanium implants in vivo.

Polymer-coated surface enhanced Raman scattering (SERS) gold nanoparticles for multiplexed labeling of chronic lymphocytic leukemia cells

NASA Astrophysics Data System (ADS)

MacLaughlin, Christina M.; Parker, Edward P. K.; Walker, Gilbert C.; Wang, Chen

2012-01-01

The ease and flexibility of functionalization and inherent light scattering properties of plasmonic nanoparticles make them suitable contrast agents for measurement of cell surface markers. Immunophenotyping of lymphoproliferative disorders is traditionally undertaken using fluorescence detection methods which have a number of limitations. Herein, surface-enhanced Raman scattering (SERS) gold nanoparticles conjugated to monoclonal antibodies are used for the selective targeting of CD molecules on the surface of chronic lymphocytic leukemia (CLL) cells. Raman-active reporters were physisorbed on to the surface of 60 nm spherical Au nanoparticles, the particles were coated with 5kDa polyethylene glycol (PEG) including functionalities for conjugation to monoclonal IgG1 antibodies. A novel method for quantifying the number of antibodies bound to SERS probes on an individual basis as opposed to obtaining averages from solution was demonstrated using metal dots in transmission electron microscopy (TEM). The specificity of the interaction between SERS probes and surface CD molecules of CLL cells was assessed using Raman spectroscopy and dark field microscopy. An in-depth study of SERS probe targeting to B lymphocyte marker CD20 was undertaken, and proof-of-concept targeting using different SERS nanoparticle dyes specific for cell surface CD19, CD45 and CD5 demonstrated using SERS spectroscopy.

Effect of electrical discharging on formation of nanoporous biocompatible layer on Ti-6Al-4V alloys.

PubMed

Yang, Tzu-Sen; Huang, Mao-Suan; Wang, Mao-Sheng; Lin, Ming-Hong; Tsai, Meng-Yuan; Wang, Pei-Yi Wang

2013-08-01

In this study, the electrical discharge machining (EDM) was formed on the surface of the Ti-6Al-4V (Ti64) specimen. The properties of adhesion and proliferation of MG-63 cells were evaluated the interactions between the EDM-treated layer and cells. The incorporation of oxygen roughened the EDM-treated specimen surface on a microscale, where the nanoscale pores were superimposed. The EDM-treated layer, which can generate the thick anatase TiO2 on the Ti64 surface, afforded a cytocompatible environment. In cell culture, alkaline phosphatase activity and osteocalcin can be dramatically enhanced on the EDM-treated surfaces when compared with the untreated surface. In addition, the increase in peak currents to the EDM functionalization led to enhancement of multiple osteoblast functions. This study reveals that the chemistry and crystallinity of the EDM-treated layer played important roles in affecting osteoblastic responses to the specimens, which provided insight into the development of new biomedical implant surfaces.

Leptin-mediated regulation of MT1-MMP localization is KIF1B dependent and enhances gastric cancer cell invasion.

PubMed

Dong, Zhaogang; Xu, Xiaofei; Du, Lutao; Yang, Yongmei; Cheng, Huanhuan; Zhang, Xin; Li, Zewu; Wang, Lili; Li, Juan; Liu, Hui; Qu, Xun; Wang, Chuanxin

2013-05-01

Leptin overexpression is closely correlated with gastric cancer (GC) invasion, but its exact effect and the underlying mechanism in tumorigenesis remain poorly understood. Membrane type 1-matrix metalloproteinase (MT1-MMP), a surface-anchored 'master switch' proteinase, is overexpressed and plays crucial roles in tumor invasion. Here, we characterized the influence of leptin on the generation and surface localization of MT1-MMP in GC and elucidated its molecular mechanisms. Our results revealed that leptin promoted GC cell invasion in vitro by upregulating MT1-MMP expression. Furthermore, cell surface biotinylation assay and flow cytometry demonstrated that the surface expression of MT1-MMP was also enhanced by leptin, and knockdown of kinesin family member 1B (KIF1B, a microtubule plus end-directed monomeric motor protein) by small interference RNA inhibited this process. Notably, coimmunoprecipitation analysis indicated that leptin enhanced the interaction of MT1-MMP with KIF1B in a time-dependent manner, which consequently contributed to GC cell invasion. Moreover, leptin increased MT1-MMP or KIF1B expression by the protein kinase B (AKT) pathway and extracellular signal-regulated kinase 1/2 partially participated in this process. However, only AKT was implicated in the leptin-mediated membrane localization of MT1-MMP. Immunohistochemistry analysis revealed that leptin, MT1-MMP and KIF1B are overexpressed in GC tissues, and they positively correlated with clinical stage and lymph node metastasis. These observations indicate that this regulatory network exists in vivo. Taken together, our findings suggest that leptin is an effective intracellular stimulator of MT1-MMP and that leptin-enhanced cell surface localization of MT1-MMP is dependent on KIF1B, which consequently plays a critical role in GC invasion.

Novel Surface-Enhanced Raman Scattering-based Assays for Ultra-sensitive Detection of Human Pluripotent Stem Cells

PubMed Central

Han, Jingjia; Qian, Ximei; Wu, Qingling; Jha, Rajneesh; Duan, Jinshuai; Yang, Zhou; Maher, Kevin O.; Nie, Shuming; Xu, Chunhui

2017-01-01

Human pluripotent stem cells (hPSCs) are a promising cell source for regenerative medicine, but their derivatives need to be rigorously evaluated for residual stem cells to prevent teratoma formation. Here, we report the development of novel surface-enhanced Raman scattering (SERS)-based assays that can detect trace numbers of undifferentiated hPSCs in mixed cell populations in a highly specific, ultra-sensitive, and time-efficient manner. By targeting stem cell surface markers SSEA-5 and TRA-1-60 individually or simultaneously, these SERS assays were able to identify as few as 1 stem cell in 106 cells, a sensitivity (0.0001%) which was ~2,000 to 15,000-fold higher than that of flow cytometry assays. Using the SERS assay, we demonstrate that the aggregation of hPSC-based cardiomyocyte differentiation cultures into 3D spheres significantly reduced SSEA-5+ and TRA-1-60+ cells compared with parallel 2D cultures. Thus, SERS may provide a powerful new technology for quality control of hPSC-derived products for preclinical and clinical applications. PMID:27509304

Protein profiling of single epidermal cell types from Arabidopsis thaliana using surface-enhanced laser desorption and ionization technology.

PubMed

Ebert, Berit; Melle, Christian; Lieckfeldt, Elke; Zöller, Daniela; von Eggeling, Ferdinand; Fisahn, Joachim

2008-08-25

Here, we describe a novel approach for investigating differential protein expression within three epidermal cell types. In particular, 3000 single pavement, basal, and trichome cells from leaves of Arabidopsis thaliana were harvested by glass micro-capillaries. Subsequently, these single cell samples were joined to form pools of 100 individual cells and analyzed using the ProteinChip technology; SELDI: surface-enhanced laser desorption and ionization. As a result, numerous protein signals that were differentially expressed in the three epidermal cell types could be detected. One of these proteins was characterized by tryptical digestion and subsequent identification via tandem quadrupole-time of flight (Q-TOF) mass spectrometry. Down regulation of this sequenced small subunit precursor of ribulose-1,5 bisphosphate carboxylase(C) oxygenase(O) (RuBisCo) in trichome and basal cells indicates the sink status of these cell types that are located on the surface of A. thaliana source leaves. Based on the obtained protein profiles, we suggest a close functional relationship between basal and trichome cells at the protein level.

Tuning Surface Chemistry of Polyetheretherketone by Gold Coating and Plasma Treatment

NASA Astrophysics Data System (ADS)

Novotná, Zdeňka; Rimpelová, Silvie; Juřík, Petr; Veselý, Martin; Kolská, Zdeňka; Hubáček, Tomáš; Borovec, Jakub; Švorčík, Václav

2017-06-01

Polyetheretherketone (PEEK) has good chemical and biomechanical properties that are excellent for biomedical applications. However, PEEK exhibits hydrophobic and other surface characteristics which cause limited cell adhesion. We have investigated the potential of Ar plasma treatment for the formation of a nanostructured PEEK surface in order to enhance cell adhesion. The specific aim of this study was to reveal the effect of the interface of plasma-treated and gold-coated PEEK matrices on adhesion and spreading of mouse embryonic fibroblasts. The surface characteristics (polarity, surface chemistry, and structure) before and after treatment were evaluated by various experimental techniques (gravimetry, goniometry, X-ray photoelectron spectroscopy (XPS), and electrokinetic analysis). Further, atomic force microscopy (AFM) was employed to examine PEEK surface morphology and roughness. The biological response of cells towards nanostructured PEEK was evaluated in terms of cell adhesion, spreading, and proliferation. Detailed cell morphology was evaluated by scanning electron microscopy (SEM). Compared to plasma treatment, gold coating improved PEEK wettability. The XPS method showed a decrease in the carbon concentration with increasing time of plasma treatment. Cell adhesion determined on the interface between plasma-treated and gold-coated PEEK matrices was directly proportional to the thickness of a gold layer on a sample. Our results suggest that plasma treatment in a combination with gold coating could be used in biomedical applications requiring enhanced cell adhesion.

Patterning of novel breast implant surfaces by enhancing silicone biocompatibility, using biomimetic topographies.

PubMed

Barr, S; Hill, E; Bayat, A

2010-04-26

Silicone biocompatibility is dictated by cell-surface interaction and its understanding is important in the field of implantation. The role of surface topography and its associated cellular morphology needs investigation to identify qualities that enhance silicone surface biocompatability. This study aims to create well-defined silicone topographies and examine how breast tissue-derived fibroblasts react and align to these surfaces. Photolithographic microelectronic techniques were modified to produce naturally inspired topographies in silicone, which were cultured with breast tissue-derived human fibroblasts. Using light, immunofluorescent and atomic force microscopy, the cytoskeletal reaction of fibroblasts to these silicone surfaces was investigated. Numerous, well-defined micron-sized pillars, pores, grooves, and ridges were manufactured and characterized in medical grade silicone. Inimitable immunofluorescent microscopy represented in our high magnification images of vinculin, vimentin, and the actin cytoskeleton highlights the differences in fibroblast adhesion between fabricated silicone surfaces. These unique figures illustrate that fibroblast adhesion and the reactions these cells have to silicone can be manipulated to enhance biointegration between the implant and the breast tissue. An alteration of fibroblast phenotype was also observed, exhibiting the propensity of these surfaces to induce categorical remodeling of fibroblasts. This unique study shows that fibroblast reactions to silicone topographies can be tailored to induce physiological changes in cells. This paves the way for further research necessary to develop more biocompatible constructs capable of eliminating capsular contracture by subverting the foreign body response.

Nanoscale imaging of photocurrent enhancement by resonator array photovoltaic coatings.

PubMed

Ha, Dongheon; Yoon, Yohan; Zhitenev, Nikolai B

2018-04-06

Nanoscale surface patterning commonly used to increase absorption of solar cells can adversely impact the open-circuit voltage due to increased surface area and recombination. Here, we demonstrate absorptivity and photocurrent enhancement using silicon dioxide (SiO 2 ) nanosphere arrays on a gallium arsenide (GaAs) solar cell that do not require direct surface patterning. Due to the combined effects of thin-film interference and whispering gallery-like resonances within nanosphere arrays, there is more than 20% enhancement in both absorptivity and photocurrent. To determine the effect of the resonance coupling between nanospheres, we perform a scanning photocurrent microscopy based on a near-field scanning optical microscopy measurement and find a substantial local photocurrent enhancement. The nanosphere-based antireflection coating (ARC), made by the Meyer rod rolling technique, is a scalable and a room-temperature process; and, can replace the conventional thin-film-based ARCs requiring expensive high-temperature vacuum deposition.

Nanoscale imaging of photocurrent enhancement by resonator array photovoltaic coatings

NASA Astrophysics Data System (ADS)

Ha, Dongheon; Yoon, Yohan; Zhitenev, Nikolai B.

2018-04-01

Nanoscale surface patterning commonly used to increase absorption of solar cells can adversely impact the open-circuit voltage due to increased surface area and recombination. Here, we demonstrate absorptivity and photocurrent enhancement using silicon dioxide (SiO2) nanosphere arrays on a gallium arsenide (GaAs) solar cell that do not require direct surface patterning. Due to the combined effects of thin-film interference and whispering gallery-like resonances within nanosphere arrays, there is more than 20% enhancement in both absorptivity and photocurrent. To determine the effect of the resonance coupling between nanospheres, we perform a scanning photocurrent microscopy based on a near-field scanning optical microscopy measurement and find a substantial local photocurrent enhancement. The nanosphere-based antireflection coating (ARC), made by the Meyer rod rolling technique, is a scalable and a room-temperature process; and, can replace the conventional thin-film-based ARCs requiring expensive high-temperature vacuum deposition.

Nano-patterned SU-8 surface using nanosphere-lithography for enhanced neuronal cell growth

NASA Astrophysics Data System (ADS)

Kim, Eunhee; Yoo, Seung-Jun; Kim, Eunjung; Kwon, Tae-Hwan; Zhang, Li; Moon, Cheil; Choi, Hongsoo

2016-04-01

Mimicking the nanoscale surface texture of the extracellular matrix can affect the regulation of cellular behavior, including adhesion, differentiation, and neurite outgrowth. In this study, SU-8-based polymer surfaces with well-ordered nanowell arrays were fabricated using nanosphere lithography with polystyrene nanoparticles. We show that the SU-8 surface with nanowells resulted in similar neuronal development of rat pheochromocytoma (PC12) cells compared with an unpatterned poly-L-lysine (PLL)-coated SU-8 surface. Additionally, even after soaking the substrate in cell culture medium for two weeks, cells on the nanowell SU-8 surface showed long-term neurite outgrowth compared to cells on the PLL-coated SU-8 surface. The topographical surface modification of the nanowell array demonstrates potential as a replacement for cell adhesive material coatings such as PLL, for applications requiring long-term use of polymer-based implantable devices.

The substrate matters in the Raman spectroscopy analysis of cells

PubMed Central

Mikoliunaite, Lina; Rodriguez, Raul D.; Sheremet, Evgeniya; Kolchuzhin, Vladimir; Mehner, Jan; Ramanavicius, Arunas; Zahn, Dietrich R.T.

2015-01-01

Raman spectroscopy is a powerful analytical method that allows deposited and/or immobilized cells to be evaluated without complex sample preparation or labeling. However, a main limitation of Raman spectroscopy in cell analysis is the extremely weak Raman intensity that results in low signal to noise ratios. Therefore, it is important to seize any opportunity that increases the intensity of the Raman signal and to understand whether and how the signal enhancement changes with respect to the substrate used. Our experimental results show clear differences in the spectroscopic response from cells on different surfaces. This result is partly due to the difference in spatial distribution of electric field at the substrate/cell interface as shown by numerical simulations. We found that the substrate also changes the spatial location of maximum field enhancement around the cells. Moreover, beyond conventional flat surfaces, we introduce an efficient nanostructured silver substrate that largely enhances the Raman signal intensity from a single yeast cell. This work contributes to the field of vibrational spectroscopy analysis by providing a fresh look at the significance of the substrate for Raman investigations in cell research. PMID:26310910

The substrate matters in the Raman spectroscopy analysis of cells

NASA Astrophysics Data System (ADS)

Mikoliunaite, Lina; Rodriguez, Raul D.; Sheremet, Evgeniya; Kolchuzhin, Vladimir; Mehner, Jan; Ramanavicius, Arunas; Zahn, Dietrich R. T.

2015-08-01

Raman spectroscopy is a powerful analytical method that allows deposited and/or immobilized cells to be evaluated without complex sample preparation or labeling. However, a main limitation of Raman spectroscopy in cell analysis is the extremely weak Raman intensity that results in low signal to noise ratios. Therefore, it is important to seize any opportunity that increases the intensity of the Raman signal and to understand whether and how the signal enhancement changes with respect to the substrate used. Our experimental results show clear differences in the spectroscopic response from cells on different surfaces. This result is partly due to the difference in spatial distribution of electric field at the substrate/cell interface as shown by numerical simulations. We found that the substrate also changes the spatial location of maximum field enhancement around the cells. Moreover, beyond conventional flat surfaces, we introduce an efficient nanostructured silver substrate that largely enhances the Raman signal intensity from a single yeast cell. This work contributes to the field of vibrational spectroscopy analysis by providing a fresh look at the significance of the substrate for Raman investigations in cell research.

A bio-recognition device developed onto nano-crystals of carbonate apatite for cell-targeted gene delivery.

PubMed

Chowdhury, E H; Akaike, Toshihiro

2005-05-20

The DNA delivery to mammalian cells is an essential tool for analyzing gene structure, regulation, and function. The approach holds great promise for the further development of gene therapy techniques and DNA vaccination strategies to treat and control diseases. Here, we report on the establishment of a cell-specific gene delivery and expression system by physical adsorption of a cell-recognition molecule on the nano-crystal surface of carbonate apatite. As a model, DNA/nano-particles were successfully coated with asialofetuin to facilitate uptake by hepatocyte-derived cell lines through the asialoglycoprotein receptor (ASGPr) and albumin to prevent non-specific interactions of the particles with cell-surface. The resulting composite particles with dual surface properties could accelerate DNA uptake and enhance expression to a notable extent. Nano-particles coated with transferrin in the same manner dramatically enhanced transgene expression in the corresponding receptor-bearing cells and thus our newly developed strategy represents a universal phenomenon for anchoring a bio-recognition macromolecule on the apatite crystal surface for targeted gene delivery, having immediate applications in basic research laboratories and great promise for gene therapy. (c) 2005 Wiley Periodicals, Inc.

The Otto Aufranc Award: enhanced biocompatibility of stainless steel implants by titanium coating and microarc oxidation.

PubMed

Lim, Young Wook; Kwon, Soon Yong; Sun, Doo Hoon; Kim, Yong Sik

2011-02-01

Stainless steel is one of the most widely used biomaterials for internal fixation devices, but is not used in cementless arthroplasty implants because a stable oxide layer essential for biocompatibility cannot be formed on the surface. We applied a Ti electron beam coating, to form oxide layer on the stainless steel surface. To form a thicker oxide layer, we used a microarc oxidation process on the surface of Ti coated stainless steel. Modification of the surface using Ti electron beam coating and microarc oxidation could improve the ability of stainless steel implants to osseointegrate. The ability of cells to adhere to grit-blasted, titanium-coated, microarc-oxidated stainless steel in vitro was compared with that of two different types of surface modifications, machined and titanium-coated, and microarc-oxidated. We performed energy-dispersive x-ray spectroscopy and scanning electron microscopy investigations to assess the chemical composition and structure of the stainless steel surfaces and cell morphology. The biologic responses of an osteoblastlike cell line (SaOS-2) were examined by measuring proliferation (cell proliferation assay), differentiation (alkaline phosphatase activity), and attraction ability (cell migration assay). Cell proliferation, alkaline phosphatase activity, migration, and adhesion were increased in the grit-blasted, titanium-coated, microarc-oxidated group compared to the two other groups. Osteoblastlike cells on the grit-blasted, titanium-coated, microarc-oxidated surface were strongly adhered, and proliferated well compared to those on the other surfaces. The surface modifications we used (grit blasting, titanium coating, microarc oxidation) enhanced the biocompatibility (proliferation and migration of osteoblastlike cells) of stainless steel. This process is not unique to stainless steel; it can be applied to many metals to improve their biocompatibility, thus allowing a broad range of materials to be used for cementless implants.

Surface functionalized magnetic nanoparticles for cancer therapy applications

NASA Astrophysics Data System (ADS)

Wydra, Robert John

Despite recent advances, cancer remains the second leading cause of deaths in the United States. Magnetic nanoparticles have found various applications in cancer research as drug delivery platforms, enhanced contrast agents for improved diagnostic imaging, and the delivery of thermal energy as standalone therapy. Iron oxide nanoparticles absorb the energy from an alternating magnetic field and convert it into heat through Brownian and Neel relaxations. To better utilize magnetic nanoparticles for cancer therapy, surface functionalization is essential for such factors as decreasing cytotoxicity of healthy tissue, extending circulation time, specific targeting of cancer cells, and manage the controlled delivery of therapeutics. In the first study, iron oxide nanoparticles were coated with a poly(ethylene glycol) (PEG) based polymer shell. The PEG coating was selected to prevent protein adsorption and thus improve circulation time and minimize host response to the nanoparticles. Thermal therapy application feasibility was demonstrated in vitro with a thermoablation study on lung carcinoma cells. Building on the thermal therapy demonstration with iron oxide nanoparticles, the second area of work focused on intracellular delivery. Nanoparticles can be appropriately tailored to enter the cell and deliver energy on the nanoscale eliminating individual cancer cells. The underlying mechanism of action is still under study, and we were interested in determining the role of reactive oxygen species (ROS) catalytically generated from the surface of iron oxide nanoparticles in this measured cytotoxicity. When exposed to an AMF, the nanoscale heating effects are capable of enhancing the Fenton-like generation of ROS determined through a methylene blue degradation assay. To deliver this enhanced ROS effect to cells, monosaccharide coated nanoparticles were developed and successfully internalized by colon cancer cell lines. Upon AMF exposure, there was a measured increase in cellular ROS and apoptosis that was attributed to lysosomal disruption since the surface functionalization selected inhibited the Fenton-like surface chemistry. To overcome this surface inhibition, a biodegradable poly(beta-amino ester) (PBAE) polymer coating was synthesized to deliver bare iron oxide to intracellular components. Delivering enhanced ROS to cancer cells is a promising new route of therapy that deserves future studies.

Induced Infiltration of Hole-Transporting Polymer into Photocatalyst for Staunch Polymer-Metal Oxide Hybrid Solar Cells.

PubMed

Park, Jong Hwan; Jung, Youngsuk; Yang, Yooseong; Shin, Hyun Suk; Kwon, Soonchul

2016-10-05

For efficient solar cells based on organic semiconductors, a good mixture of photoactive materials in the bulk heterojunction on the length scale of several tens of nanometers is an important requirement to prevent exciton recombination. Herein, we demonstrate that nanoporous titanium dioxide inverse opal structures fabricated using a self-assembled monolayer method and with enhanced infiltration of electron-donating polymers is an efficient electron-extracting layer, which enhances the photovoltaic performance. A calcination process generates an inverse opal structure of titanium dioxide (<70 nm of pore diameters) providing three-dimensional (3D) electron transport pathways. Hole-transporting polymers was successfully infiltrated into the pores of the surface-modified titanium dioxide under vacuum conditions at 200 °C. The resulting geometry expands the interfacial area between hole- and electron-transport materials, increasing the thickness of the active layer. The controlled polymer-coating process over titanium dioxide materials enhanced photocurrent of the solar cell device. Density functional theory calculations show improved interfacial adhesion between the self-assembled monolayer-modified surface and polymer molecules, supporting the experimental result of enhanced polymer infiltration into the voids. These results suggest that the 3D inverse opal structure of the surface-modified titanium dioxide can serve as a favorable electron-extracting layer in further enhancing optoelectronic performance based on organic or organic-inorganic hybrid solar cell.

Titania-polymeric powder coatings with nano-topography support enhanced human mesenchymal cell responses.

PubMed

Mozumder, Mohammad Sayem; Zhu, Jesse; Perinpanayagam, Hiran

2012-10-01

Titanium implant osseointegration is dependent on the cellular response to surface modifications and coatings. Titania-enriched nanocomposite polymeric resin coatings were prepared through the application of advanced ultrafine powder coating technology. Their surfaces were readily modified to create nano-rough (<100 nm) surface nano-topographies that supported human embryonic palatal mesenchymal cell responses. Energy dispersive x-ray spectroscopy confirmed continuous and homogenous coatings with a similar composition and even distribution of titanium. Scanning electron microscopy (SEM) showed complex micro-topographies, and atomic force microscopy revealed intricate nanofeatures and surface roughness. Cell counts, mitochondrial enzyme activity reduction of yellow 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to dark purple, SEM, and inverted fluorescence microscopy showed a marked increase in cell attachment, spreading, proliferation, and metabolic activity on the nanostructured surfaces. Reverse Transcription- Polymerase Chain Reaction (RT-PCR) analysis showed that type I collagen and Runx2 expression were induced, and Alizarin red staining showed that mineral deposits were abundant in the cell cultures grown on nanosurfaces. This enhancement in human mesenchymal cell attachment, growth, and osteogenesis were attributed to the nanosized surface topographies, roughness, and moderate wetting characteristics of the coatings. Their dimensional similarity to naturally occurring matrix proteins and crystals, coupled with their increased surface area for protein adsorption, may have facilitated the response. Therefore, this application of ultrafine powder coating technology affords highly biocompatible surfaces that can be readily modified to accentuate the cellular response. Copyright © 2012 Wiley Periodicals, Inc.

Biofunctionalization of a titanium surface with a nano-sawtooth structure regulates the behavior of rat bone marrow mesenchymal stem cells

PubMed Central

Zhang, Wenjie; Li, Zihui; Liu, Yan; Ye, Dongxia; Li, Jinhua; Xu, Lianyi; Wei, Bin; Zhang, Xiuli; Liu, Xuanyong; Jiang, Xinquan

2012-01-01

Background: The topography of an implant surface can serve as a powerful signaling cue for attached cells and can enhance the quality of osseointegration. A series of improved implant surfaces functionalized with nanoscale structures have been fabricated using various methods. Methods: In this study, using an H2O2 process, we fabricated two size-controllable sawtooth-like nanostructures with different dimensions on a titanium surface. The effects of the two nano-sawtooth structures on rat bone marrow mesenchymal stem cells (BMMSCs) were evaluated without the addition of osteoinductive chemical factors. Results: These new surface modifications did not adversely affect cell viability, and rat BMMSCs demonstrated a greater increase in proliferation ability on the surfaces of the nano-sawtooth structures than on a control plate. Furthermore, upregulated expression of osteogenic-related genes and proteins indicated that the nano-sawtooth structures promote osteoblastic differentiation of rat BMMSCs. Importantly, the large nano-sawtooth structure resulted in the greatest cell responses, including increased adhesion, proliferation, and differentiation. Conclusion: The enhanced adhesion, proliferation, and osteogenic differentiation abilities of rat BMMSCs on the nano-sawtooth structures suggest the potential to induce improvements in bone-titanium integration in vivo. Our study reveals the key role played by the nano-sawtooth structures on a titanium surface for the fate of rat BMMSCs and provides insights into the study of stem cell-nanostructure relationships and the related design of improved biomedical implant surfaces. PMID:22927760

Surface enhanced raman spectroscopy technique in rapid detection of live and dead salmonella cells

USDA-ARS?s Scientific Manuscript database

Many research proved that Surface Enhanced Raman Spectroscopy (SERS) can detect pathogens rapidly and accurately. In this study, a silver metal substrate was used for the selected common food pathogen Salmonella typhimurium bacteria. Nano silver rods were deposited on a thin titanium coating over t...

Modification of anti-bacterial surface properties of textile polymers by vacuum arc ion source implantation

NASA Astrophysics Data System (ADS)

Nikolaev, A. G.; Yushkov, G. Yu.; Oks, E. M.; Oztarhan, A.; Akpek, A.; Hames-Kocabas, E.; Urkac, E. S.; Brown, I. G.

2014-08-01

Ion implantation provides an important technology for the modification of material surface properties. The vacuum arc ion source is a unique instrument for the generation of intense beams of metal ions as well as gaseous ions, including mixed metal-gas beams with controllable metal:gas ion ratio. Here we describe our exploratory work on the application of vacuum arc ion source-generated ion beams for ion implantation into polymer textile materials for modification of their biological cell compatibility surface properties. We have investigated two specific aspects of cell compatibility: (i) enhancement of the antibacterial characteristics (we chose to use Staphylococcus aureus bacteria) of ion implanted polymer textile fabric, and (ii) the "inverse" concern of enhancement of neural cell growth rate (we chose Rat B-35 neuroblastoma cells) on ion implanted polymer textile. The results of both investigations were positive, with implantation-generated antibacterial efficiency factor up to about 90%, fully comparable to alternative conventional (non-implantation) approaches and with some potentially important advantages over the conventional approach; and with enhancement of neural cell growth rate of up to a factor of 3.5 when grown on suitably implanted polymer textile material.

Label-free surface-enhanced Raman scattering imaging to monitor the metabolism of antitumor drug 6-mercaptopurine in living cells.

PubMed

Han, Guangmei; Liu, Renyong; Han, Ming-Yong; Jiang, Changlong; Wang, Jianping; Du, Shuhu; Liu, Bianhua; Zhang, Zhongping

2014-12-02

The molecular processes of drugs from cellular uptake to intracellular distribution as well as the intracellular interaction with the target molecule are critically important for the development of new antitumor drugs. In this work, we have successfully developed a label-free surface-enhanced Raman scattering (SERS) technique to monitor and visualize the metabolism of antitumor drug 6-mercaptopurine in living cells. It has been clearly demonstrated that Au@Ag NPs exhibit an excellent Raman enhancement effect to both 6-mercaptopurine and its metabolic product 6-mercaptopurine-ribose. Their different ways to absorb at the surface of Au@Ag NPs lead to the obvious spectral difference for distinguishing the antitumor drug and its metabolite by SERS spectra. The Au@Ag NPs can easily pass through cell membranes in a large amount and sensitively respond to the biological conversion of 6-mercaptopurine in tumor cells. The Raman imaging can visualize the real-time distribution of 6-mercaptopurine and its biotransformation with the concentrations in tumor cells. The SERS-based method reported here is simple and efficient for the assessments of drug efficacy and the understanding of the molecular therapeutic mechanism of antitumor drugs at the cellular level.

Matrigel immobilization on the shish-kebab structured poly(ɛ-caprolactone) nanofibers for skin tissue engineering

NASA Astrophysics Data System (ADS)

Jing, Xin; Mi, Hao-Yang; Peng, Xiang-Fang; Turng, Lih-Sheng

2016-03-01

Surface properties of tissue engineering scaffolds such as topography, hydrophilicity, and functional groups play a vital role in cell adhesion, migration, proliferation, and apoptosis. First, poly(ɛ-caprolactone) (PCL) shish-kebab scaffolds (PCL-SK), which feature a three-dimensional structure comprised of electrospun PCL nanofibers covered by periodic, self-induced PCL crystal lamellae on the surface, was created to mimic the nanotopography of native collagen fibrils in the extracellular matrix (ECM). Second, matrigel was covalently immobilized on the surface of alkaline hydrolyzed PCL-SK scaffolds to enhance their hydrophilicity. This combined approach not only mimics the nanotopography of native collagen fibrils, but also simulates the surface features of collagen fibrils for cell growth. To investigate the viability of such scaffolds, HEF1 fibroblast cell assays were conducted and the results revealed that the nanotopography of the PCL-SK scaffolds facilitated cell adhesion and proliferation. The matrigel functionalization on PCL-SK scaffolds further enhanced cellular response, which suggested elevated biocompatibility and greater potential for skin tissue engineering applications.

The Role of Titanium Surface Microtopography on Adhesion, Proliferation, Transformation, and Matrix Deposition of Corneal Cells.

PubMed

Zhou, Chengxin; Lei, Fengyang; Chodosh, James; Paschalis, Eleftherios I

2016-04-01

Titanium (Ti) is an excellent implantable biomaterial that can be further enhanced by surface topography optimization. Despite numerous data from orthopedics and dentistry, the effect of Ti surface topography on ocular cells is still poorly understood. In light of the recent adaptation of Ti in the Boston Keratoprosthesis artificial cornea, we attempted to perform an extended evaluation of the effect of Ti surface topography on corneal cell adhesion, proliferation, cytotoxicity, transformation, and matrix deposition. Different surface topographies were generated on medical grade Ti-6Al-4V-ELI (extra-low interstitial), with linearly increased roughness (polished to grit blasted). Biological response was evaluated in vitro using human corneal limbal epithelial (HCLE) cells, stromal fibroblasts (HCF), and endothelial cells (HCEnC). None of the Ti surface topographies caused cytotoxicity to any of the three corneal cell types. However, rough Ti surface inhibited HCLE and HCF cell adhesion and proliferation, while HCEnC proliferation was unaffected. Long-term experiments with HCF revealed that rough Ti surface with R(a) (the arithmetic average of the profile height from the mean line) ≥ 1.15 μm suppressed HCF focal adhesion kinase phosphorylation, changed fibroblast morphology, and caused less aligned and reduced deposition of collagen matrix as compared to smooth Ti (R(a) ≤ 0.08 μm). In the presence of transforming growth factor β1 (TGFβ1) stimulation, rough Ti inhibited alpha-smooth muscle actin (α-SMA) expression and collagen deposition, leading to decreased myofibroblast transformation and disorganization of the collagen fibrils as compared to smooth Ti. This study suggests that Ti surface topography regulates corneal cell behavior in a tissue-dependent manner that varies across the corneal strata. Contrary to the accepted paradigm, smooth surface topography can enhance cell adhesion and proliferation and increase matrix deposition by corneal cells.

A novel method for detection of phosphorylation in single cells by surface enhanced Raman scattering (SERS) using composite organic-inorganic nanoparticles (COINs).

PubMed

Shachaf, Catherine M; Elchuri, Sailaja V; Koh, Ai Leen; Zhu, Jing; Nguyen, Lienchi N; Mitchell, Dennis J; Zhang, Jingwu; Swartz, Kenneth B; Sun, Lei; Chan, Selena; Sinclair, Robert; Nolan, Garry P

2009-01-01

Detection of single cell epitopes has been a mainstay of immunophenotyping for over three decades, primarily using fluorescence techniques for quantitation. Fluorescence has broad overlapping spectra, limiting multiplexing abilities. To expand upon current detection systems, we developed a novel method for multi-color immuno-detection in single cells using "Composite Organic-Inorganic Nanoparticles" (COINs) Raman nanoparticles. COINs are Surface-Enhanced Raman Scattering (SERS) nanoparticles, with unique Raman spectra. To measure Raman spectra in single cells, we constructed an automated, compact, low noise and sensitive Raman microscopy device (Integrated Raman BioAnalyzer). Using this technology, we detected proteins expressed on the surface in single cells that distinguish T-cells among human blood cells. Finally, we measured intracellular phosphorylation of Stat1 (Y701) and Stat6 (Y641), with results comparable to flow cytometry. Thus, we have demonstrated the practicality of applying COIN nanoparticles for measuring intracellular phosphorylation, offering new possibilities to expand on the current fluorescent technology used for immunoassays in single cells.

A Novel Method for Detection of Phosphorylation in Single Cells by Surface Enhanced Raman Scattering (SERS) using Composite Organic-Inorganic Nanoparticles (COINs)

PubMed Central

Shachaf, Catherine M.; Elchuri, Sailaja V.; Koh, Ai Leen; Zhu, Jing; Nguyen, Lienchi N.; Mitchell, Dennis J.; Zhang, Jingwu; Swartz, Kenneth B.; Sun, Lei; Chan, Selena; Sinclair, Robert; Nolan, Garry P.

2009-01-01

Background Detection of single cell epitopes has been a mainstay of immunophenotyping for over three decades, primarily using fluorescence techniques for quantitation. Fluorescence has broad overlapping spectra, limiting multiplexing abilities. Methodology/Principal Findings To expand upon current detection systems, we developed a novel method for multi-color immuno-detection in single cells using “Composite Organic-Inorganic Nanoparticles” (COINs) Raman nanoparticles. COINs are Surface-Enhanced Raman Scattering (SERS) nanoparticles, with unique Raman spectra. To measure Raman spectra in single cells, we constructed an automated, compact, low noise and sensitive Raman microscopy device (Integrated Raman BioAnalyzer). Using this technology, we detected proteins expressed on the surface in single cells that distinguish T-cells among human blood cells. Finally, we measured intracellular phosphorylation of Stat1 (Y701) and Stat6 (Y641), with results comparable to flow cytometry. Conclusions/Significance Thus, we have demonstrated the practicality of applying COIN nanoparticles for measuring intracellular phosphorylation, offering new possibilities to expand on the current fluorescent technology used for immunoassays in single cells. PMID:19367337

The usefulness of three-dimensional cell culture in induction of cancer stem cells from esophageal squamous cell carcinoma cell lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujiwara, Daisuke; Kato, Kazunori, E-mail: kzkatou@juntendo.ac.jp; Department of Atopy Research Center, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421

2013-05-17

Highlights: •Spheroids were created from esophageal carcinoma cells using NanoCulture® Plates. •The proportion of strongly ALDH-positive cells increased in 3-D culture. •Expression of cancer stem cell-related genes was enhanced in 3-D culture. •CA-9 expression was enhanced, suggesting hypoxia had been induced in 3-D culture. •Drug resistance was increased. 3-D culture is useful for inducing cancer stem cells. -- Abstract: In recent years, research on resistance to chemotherapy and radiotherapy in cancer treatment has come under the spotlight, and researchers have also begun investigating the relationship between resistance and cancer stem cells. Cancer stem cells are assumed to be present inmore » esophageal cancer, but experimental methods for identification and culture of these cells have not yet been established. To solve this problem, we created spheroids using a NanoCulture® Plate (NCP) for 3-dimensional (3-D) cell culture, which was designed as a means for experimentally reproducing the 3-D structures found in the body. We investigated the potential for induction of cancer stem cells from esophageal cancer cells. Using flow cytometry we analyzed the expression of surface antigen markers CD44, CD133, CD338 (ABCG2), CD318 (CDCP1), and CD326 (EpCAM), which are known cancer stem cell markers. None of these surface antigen markers showed enhanced expression in 3-D cultured cells. We then analyzed aldehyde dehydrogenase (ALDH) enzymatic activity using the ALDEFLUOR reagent, which can identify immature cells such as stem cells and precursor cells. 3-D-cultured cells were strongly positive for ALDH enzyme activity. We also analyzed the expression of the stem cell-related genes Sox-2, Nanog, Oct3/4, and Lin28 using RT-PCR. Expression of Sox-2, Nanog, and Lin28 was enhanced. Analysis of expression of the hypoxic surface antigen marker carbonic anhydrase-9 (CA-9), which is an indicator of cancer stem cell induction and maintenance, revealed that CA-9 expression was enhanced, suggesting that hypoxia had been induced. Comparison of cancer drug resistance using cisplatin and doxorubicin in 3-D-cultured esophageal cancer cells showed that cancer drug resistance had increased. These results indicate that 3-D culture of esophageal squamous cell carcinoma lines is a useful method for inducing cancer stem cells.« less

Thermodynamic limit to photonic-plasmonic light-trapping in thin films on metals

NASA Astrophysics Data System (ADS)

Schiff, E. A.

2011-11-01

We calculate the maximum optical absorptance enhancements in thin semiconductor films on metals due to structures that diffuse light and couple it to surface plasmon polaritons. The calculations can be used to estimate plasmonic effects on light-trapping in solar cells. The calculations are based on the statistical distribution of energy in the electromagnetic modes of the structure, which include surface plasmon polariton modes at the metal interface as well as the trapped waveguide modes in the film. The enhancement has the form 4n2+nλ/h (n - film refractive index, λ - optical wavelength, h - film thickness), which is an increase beyond the non-plasmonic "classical" enhancement 4n2. Larger resonant enhancements occur for wavelengths near the surface plasmon frequency; these add up to 2 mA/cm2 to the photocurrent of a solar cell based on a 500 nm film of crystalline silicon. We also calculated the effects of plasmon dissipation in the metal. Dissipation rates typical of silver reverse the resonant enhancement effect for silicon, but a non-resonant enhancement remains.

Desialylation of glycoconjugates on the surface of monocytes activates the extracellular signal-related kinases ERK 1/2 and results in enhanced production of specific cytokines.

PubMed

Stamatos, Nicholas M; Curreli, Sabrina; Zella, Davide; Cross, Alan S

2004-02-01

Modulation of the sialic acid content of cell-surface glycoproteins and glycolipids influences the functional capacity of cells of the immune system. The role of sialidase(s) and the consequent desialylation of cell surface glycoconjugates in the activation of monocytes have not been established. In this study, we show that desialylation of glycoconjugates on the surface of purified monocytes using exogenous neuraminidase (NANase) activated extracellular signal-regulated kinase 1/2 (ERK 1/2), an intermediate in intracellular signaling pathways. Elevated levels of phosphorylated ERK 1/2 were detected in desialylated monocytes after 2 h of NANase treatment, and increased amounts persisted for at least 2 additional hours. Desialylation of cell surface glycoconjugates also led to increased production of interleukin (IL)-6, macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta by NANase-treated monocytes that were maintained in culture. Neither increased levels of phosphorylated ERK 1/2 nor enhanced production of cytokines were detected when NANase was heat-inactivated before use, demonstrating the specificity of NANase action. Treatment of monocytes with gram-negative bacterial lipopolysaccharide (LPS) also led to enhanced production of IL-6, MIP-1alpha, and MIP-1beta. The amount of each of these cytokines that was produced was markedly increased when monocytes were desialylated with NANase before exposure to LPS. These results suggest that changes in the sialic acid content of surface glycoconjugates influence the activation of monocytes.

Enhanced biomimic bactericidal surfaces by coating with positively-charged ZIF nano-dagger arrays.

PubMed

Yuan, Yuan; Zhang, Yugen

2017-10-01

Cicada wing surfaces are covered with dense patterns of nano-pillar structure that prevent bacterial growth by rupturing adhered microbial cells. To mimic the natural nano-pillar structure, we developed a general and simple method to grow metal organic framework (MOF) nano-dagger arrays on a wide range of surfaces. These nano-daggers possess high bactericidal activity, with log reduction >7 for Escherichia coli and Staphylococcus aureus. It was hypothesized that the positively-charged ZIF-L nano-dagger surfaces enhance bacterial cell adhesion, facilitating selective and efficient bacteria killing by the rigid and sharp nano-dagger tips. This research provides a safe and clean antimicrobial surface technology which does not require external chemicals and will not cause drug resistance. Copyright © 2017 Elsevier Inc. All rights reserved.

Polyvinylpyrrolidone- (PVP-) coated silver aggregates for high performance surface-enhanced Raman scattering in living cells.

PubMed

Tan, Xuebin; Wang, Zhuyuan; Yang, Jing; Song, Chunyuan; Zhang, Ruohu; Cui, Yiping

2009-11-04

A biocompatible and stable surface-enhanced Raman scattering (SERS) probe has been successfully synthesized through a simple route with silver aggregates. Polyvinylpyrrolidone (PVP), a biocompatible polymer, was utilized to control the aggregation process and improve the chemical stability of the aggregates. Extinction spectroscopy and TEM results show the aggregation degree and core-shell structure of the probe. It is found that when we employ 4-mercaptobenzoic acid (4MBA), crystal violet (CV), Rhodamine 6G (R6G) or 4,4'-bipyridine molecules as Raman reporters, the SERS signal from the proposed probe can remain at a high level under aggressive chemical environments, even after being incorporated into living cells. In comparison with the traditional probes without the PVP shell, the new ones exhibit strong surface-enhanced effects and low toxicity towards living cells. We demonstrate that the PVP-coated silver aggregates are highly SERS effective, for which the fabrication protocol is advantageous in its simplicity and reproducibility.

Surface engineered biosensors for the early detection of cancer

NASA Astrophysics Data System (ADS)

Islam, Muhymin

Cancer commences in the building block of human body which is cells and in most of the cases remains silent at early stage. Diseases are only expressed at molecular and cellular level at primary stages. Recognition of diseases at this micro and nano level might reduce the mortality rate of cancer significantly. This research work aimed to introduce novel electronic biosensors for for identification of cancer at cellular level. The dissertation study focuses on 1) Label-Free Isolation of Metastatic Tumor Cells Using Filter Based Microfluidic device; 2) Nanotextured Polymer Substrates for Enhanced Cancer Cell Isolation and Cell Growth; 3) Nanotextured Microfluidic Channel for Electrical Profiling and Detection of Tumor Cells from Blood; and 4) Single Biochip for the Detection of Tumor Cells by Electrical Profile and Surface Immobilized Aptamer. Standard silicon processing techniques were followed to fabricate all of the biosensors. Nantoextruing and surface functionalizon were also incorporated to elevate the efficiency of the devices. The first approach aimed to detect cancer cells from blood based on their mechanophysical properties. Cancer cells are larger than blood cells but highly elastic in nature. These cells can squeeze through small microchannels much smaller than their size. The cross sectional area of the microchannels was optimized to isolate tumor cells from blood. Nanotextured polymer substrates, a platform inspired from the natural basement membrane was used to enhance the isolation and growth of tumor cells. Micro reactive ion etching was performed to have better control on features of nantoxtured surfaces and did not require any template. Next, electrical measurement of ionic current was performed across single microchannel to detect tumor cells from blood. Later, nanotexturing enhanced the efficiency of the device by selectively altering the translocation profile of cancer cells. Eventually aptamer functionalized nanotextured polymer surface was integrated with current measurement facilities in a single biochip to discriminate tumor cells from blood with higher efficiency and selectivity. This biochip can be an implemented as a point-of-care device for the early detection of cancer at cellular level.

Development of drug loaded nanoparticles for tumor targeting. Part 1: Synthesis, characterization, and biological evaluation in 2D cell cultures.

PubMed

El-Dakdouki, Mohammad H; Puré, Ellen; Huang, Xuefei

2013-05-07

Nanoparticles (NPs) are being extensively studied as carriers for drug delivery, but they often have limited penetration inside tumors. We envision that by targeting an endocytic receptor on the cell surface, the uptake of NPs can be significantly enhanced through receptor mediated endocytosis. In addition, if the receptor is recycled to the cell surface, the NP cargo can be transported out of the cells, which is then taken up by neighboring cells thus enhancing solid tumor penetration. To validate our hypothesis, in the first of two articles, we report the synthesis of doxorubicin (DOX)-loaded, hyaluronan (HA) coated silica nanoparticles (SNPs) containing a highly fluorescent core to target CD44, a receptor expressed on the cancer cell surface. HA was conjugated onto amine-functionalized SNPs prepared through an oil-water microemulsion method. The immobilization of the cytotoxic drug DOX was achieved through an acid sensitive hydrazone linkage. The NPs were fully characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurements, thermogravimetric analysis (TGA), UV-vis absorbance, and nuclear magnetic resonance (NMR). Initial biological evaluation experiments demonstrated that compared to ligand-free SNPs, the uptake of HA-SNPs by the CD44-expressing SKOV-3 ovarian cancer cells was significantly enhanced when evaluated in the 2D monolayer cell culture. Mechanistic studies suggested that cellular uptake of HA-SNPs was mainly through CD44 mediated endocytosis. HA-SNPs with immobilized DOX were endocytosed efficiently by the SKOV-3 cells as well. The enhanced tumor penetration and drug delivery properties of HA-SNPs will be evaluated in 3D tumor models in the subsequent paper.

Clustering of adhesion receptors following exposure of insect blood cells to foreign surfaces.

PubMed

Nardi, James B; Zhuang, Shufei; Pilas, Barbara; Bee, Charles Mark; Kanost, Michael R

2005-05-01

Cell-mediated immune responses of insects involve interactions of two main classes of blood cells (hemocytes) known as granular cells and plasmatocytes. In response to a foreign surface, these hemocytes suddenly transform from circulating, non-adherent cells to cells that interact and adhere to each other and the foreign surface. This report presents evidence that during this adhesive transformation the extracellular matrix (ECM) proteins lacunin and a ligand for peanut agglutinin (PNA) lectin are released by granular cells and bind to surfaces of both granular cells and plasmatocytes. ECM protein co-localizes on cell surfaces with the adhesive receptors integrin and neuroglian, a member of the immunoglobulin superfamily. The ECM protein(s) secreted by granular cells are hypothesized to interact with adhesion receptors such as neuroglian and integrin by cross linking and clustering them on hemocyte surfaces. This clustering of receptors is known to enhance the adhesiveness (avidity) of interacting mammalian immune cells. The formation of ring-shaped clusters of these adhesion receptors on surfaces of insect immune cells represents an evolutionary antecedent of the mammalian immunological synapse.

Low-dose gemcitabine induces major histocompatibility complex class I-related chain A/B expression and enhances an antitumor innate immune response in pancreatic cancer.

PubMed

Miyashita, Tomoharu; Miki, Kenji; Kamigaki, Takashi; Makino, Isamu; Nakagawara, Hisatoshi; Tajima, Hidehiro; Takamura, Hiroyuki; Kitagawa, Hirohisa; Fushida, Sachio; Ahmed, Ali K; Duncan, Mark D; Harmon, John W; Ohta, Tetsuo

2017-02-01

We investigated the effect of gemcitabine (GEM), a key drug for pancreatic cancer treatment, on the expression of cell surface MICA/B in pancreatic cancer cells and resulting cytotoxicity of γδ T cells. We assessed the effect of GEM on the upregulation of cell surface MICA/B expression by flow cytometry, utilizing six pancreatic cancer cell lines. MICA and CD16 expressions from resected pancreatic cancer patient specimens, which received neoadjuvant chemotherapy (NAC) with GEM, were analyzed by immunohistochemistry. GEM could increase MICA/B expression on cell surface in pancreatic cancer cell lines (in 2 of 6 cell lines). This effect was most effectively at concentration not affecting cell growth of GEM (0.001 μM), because MICA/B negative population was appeared at concentration at cytostatic and cytotoxic effect to cell growth (0.1 and 10 μM). The cytotoxic activity of γδ T cells against PANC-1 was detected and functions through interactions between NKG2D and MICA/B. However, the enhancement of NKG2D-dependent cytotoxicity with increased MICA/B expression, by GEM treatment, was not observed. In addition, soluble MIC molecules were released from pancreatic cancer cell lines in culture supernatant with GEM treatment. Immunohistochemical staining demonstrated that MICA expression in tumor cells and CD16 positive cells surrounding tumors were significantly higher in the NAC group compared to that of the control group. There was a significant correlation between NAC and MICA expression, as well as NAC and CD16 positive cell expression. The present results indicate that low-dose GEM-induced MICA/B expression enhances innate immune function rather than cytotoxicity in pancreatic cancer. In addition, our result suggests that the inhibition of cleavage and release of MIC molecules from the tumor surface could potentially improve NKG2D-dependent cytotoxicity.

The role of endothelial cell attachment to elastic fibre molecules in the enhancement of monolayer formation and retention, and the inhibition of smooth muscle cell recruitment.

PubMed

Williamson, Matthew R; Shuttleworth, Adrian; Canfield, Ann E; Black, Richard A; Kielty, Cay M

2007-12-01

The endothelium is an essential modulator of vascular tone and thrombogenicity and a critical barrier between the vessel wall and blood components. In tissue-engineered small-diameter vascular constructs, endothelial cell detachment in flow can lead to thrombosis and graft failure. The subendothelial extracellular matrix provides stable endothelial cell anchorage through interactions with cell surface receptors, and influences the proliferation, migration, and survival of both endothelial cells and smooth muscle cells. We have tested the hypothesis that these desired physiological characteristics can be conferred by surface coatings of natural vascular matrix components, focusing on the elastic fiber molecules, fibrillin-1, fibulin-5 and tropoelastin. On fibrillin-1 or fibulin-5-coated surfaces, endothelial cells exhibited strong integrin-mediated attachment in static conditions (82% and 76% attachment, respectively) and flow conditions (67% and 78% cell retention on fibrillin-1 or fibulin-5, respectively, at 25 dynes/cm2), confluent monolayer formation, and stable functional characteristics. Adhesion to these two molecules also strongly inhibited smooth muscle cell migration to the endothelial monolayer. In contrast, on elastin, endothelial cells attached poorly, did not spread, and had markedly impaired functional properties. Thus, fibrillin-1 and fibulin-5, but not elastin, can be exploited to enhance endothelial stability, and to inhibit SMC migration within vascular graft scaffolds. These findings have important implications for the design of vascular graft scaffolds, the clinical performance of which may be enhanced by exploiting natural cell-matrix biology to regulate cell attachment and function.

Effect of core quantum-dot size on power-conversion-efficiency for silicon solar-cells implementing energy-down-shift using CdSe/ZnS core/shell quantum dots.

PubMed

Baek, Seung-Wook; Shim, Jae-Hyoung; Seung, Hyun-Min; Lee, Gon-Sub; Hong, Jin-Pyo; Lee, Kwang-Sup; Park, Jea-Gun

2014-11-07

Silicon solar cells mainly absorb visible light, although the sun emits ultraviolet (UV), visible, and infrared light. Because the surface reflectance of a textured surface with SiNX film on a silicon solar cell in the UV wavelength region (250-450 nm) is higher than ∼27%, silicon solar-cells cannot effectively convert UV light into photo-voltaic power. We implemented the concept of energy-down-shift using CdSe/ZnS core/shell quantum-dots (QDs) on p-type silicon solar-cells to absorb more UV light. CdSe/ZnS core/shell QDs demonstrated clear evidence of energy-down-shift, which absorbed UV light and emitted green-light photoluminescence signals at a wavelength of 542 nm. The implementation of 0.2 wt% (8.8 nm QDs layer) green-light emitting CdSe/ZnS core/shell QDs reduced the surface reflectance of the textured surface with SiNX film on a silicon solar-cell from 27% to 15% and enhanced the external quantum efficiency (EQE) of silicon solar-cells to around 30% in the UV wavelength region, thereby enhancing the power conversion efficiency (PCE) for p-type silicon solar-cells by 5.5%.

Astrocytes Increase ATP Exocytosis Mediated Calcium Signaling in Response to Microgroove Structures

PubMed Central

Singh, Ajay V.; Raymond, Michael; Pace, Fabiano; Certo, Anthony; Zuidema, Jonathan M.; McKay, Christopher A.; Gilbert, Ryan J.; Lu, X. Lucas; Wan, Leo Q.

2015-01-01

Following central nervous system (CNS) injury, activated astrocytes form glial scars, which inhibit axonal regeneration, leading to long-term functional deficits. Engineered nanoscale scaffolds guide cell growth and enhance regeneration within models of spinal cord injury. However, the effects of micro-/nanosize scaffolds on astrocyte function are not well characterized. In this study, a high throughput (HTP) microscale platform was developed to study astrocyte cell behavior on micropatterned surfaces containing 1 μm spacing grooves with a depth of 250 or 500 nm. Significant changes in cell and nuclear elongation and alignment on patterned surfaces were observed, compared to on flat surfaces. The cytoskeleton components (particularly actin filaments and focal adhesions) and nucleus-centrosome axis were aligned along the grooved direction as well. More interestingly, astrocytes on micropatterned surfaces showed enhanced mitochondrial activity with lysosomes localized at the lamellipodia of the cells, accompanied by enhanced adenosine triphosphate (ATP) release and calcium activities. These data indicate that the lysosome-mediated ATP exocytosis and calcium signaling may play an important role in astrocytic responses to substrate topology. These new findings have furthered our understanding of the biomechanical regulation of astrocyte cell–substrate interactions, and may benefit the optimization of scaffold design for CNS healing. PMID:25597401

Plasmonic excitation-assisted optical and electric enhancement in ultra-thin solar cells: the influence of nano-strip cross section

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabaeian, Mohammad, E-mail: sabaiean@scu.ac.ir; Heydari, Mehdi; Ajamgard, Narges

The effects of Ag nano-strips with triangle, rectangular and trapezoid cross sections on the optical absorption, generation rate, and short-circuit current density of ultra-thin solar cells were investigated. By putting the nano-strips as a grating structure on the top of the solar cells, the waveguide, surface plasmon polariton (SPP), and localized surface plasmon (LSP) modes, which are excited with the assistance of nano-strips, were evaluated in TE and TM polarizations. The results show, firstly, the TM modes are more influential than TE modes in optical and electrical properties enhancement of solar cell, because of plasmonic excitations in TM mode. Secondly,more » the trapezoid nano-strips reveal noticeable impact on the optical absorption, generation rate, and short-circuit current density enhancement than triangle and rectangular ones. In particular, the absorption of long wavelengths which is a challenge in ultra-thin solar cells is significantly improved by using Ag trapezoid nano-strips.« less

Enhancement of cell growth on honeycomb-structured polylactide surface using atmospheric-pressure plasma jet modification

NASA Astrophysics Data System (ADS)

Cheng, Kuang-Yao; Chang, Chia-Hsing; Yang, Yi-Wei; Liao, Guo-Chun; Liu, Chih-Tung; Wu, Jong-Shinn

2017-02-01

In this paper, we compare the cell growth results of NIH-3T3 and Neuro-2A cells over 72 h on flat and honeycomb structured PLA films without and with a two-step atmospheric-pressure nitrogen-based plasma jet treatment. We developed a fabrication system used for forming of a uniform honeycomb structure on PLA surface, which can produce two different pore sizes, 3-4 μm and 7-8 μm, of honeycomb pattern. We applied a previously developed nitrogen-based atmospheric-pressure dielectric barrier discharge (DBD) jet system to treat the PLA film without and with honeycomb structure. NIH-3T3 and a much smaller Neuro-2A cells were cultivated on the films under various surface conditions. The results show that the two-step plasma treatment in combination with a honeycomb structure can enhance cell growth on PLA film, should the cell size be not too smaller than the pore size of honeycomb structure, e.g., NIH-3T3. Otherwise, cell growth would be better on flat PLA film, e.g., Neuro-2A.

Carbon nanowall scaffold to control culturing of cervical cancer cells

NASA Astrophysics Data System (ADS)

Watanabe, Hitoshi; Kondo, Hiroki; Okamoto, Yukihiro; Hiramatsu, Mineo; Sekine, Makoto; Baba, Yoshinobu; Hori, Masaru

2014-12-01

The effect of carbon nanowalls (CNWs) on the culturing rate and morphological control of cervical cancer cells (HeLa cells) was investigated. CNWs with different densities were grown using plasma-enhanced chemical vapor deposition and subjected to post-growth plasma treatment for modification of the surface terminations. Although the surface wettability of the CNWs was not significantly dependent on the CNW densities, the cell culturing rates were significantly dependent. Morphological changes of the cells were not significantly dependent on the density of CNWs. These results indicate that plasma-induced surface morphology and chemical terminations enable nanobio applications using carbon nanomaterials.

Effect of surface pre-treatments on biocompatibility of magnesium.

PubMed

Lorenz, Carla; Brunner, Johannes G; Kollmannsberger, Philip; Jaafar, Leila; Fabry, Ben; Virtanen, Sannakaisa

2009-09-01

This study reports the influence of Mg surface passivation on the survival rate of human HeLa cells and mouse fibroblasts in cell culture experiments. Polished samples of commercially pure Mg show high reactivity in the cell culture medium, leading to a pH shift in the alkaline direction, and therefore cell adhesion and survival is strongly impaired. Passivation of the Mg surface in 1M NaOH can strongly enhance cell survival. The best initial cell adhesion is observed for Mg samples incubated in simulated body fluid (M-SBF), which leads to the formation of a biomimetic, amorphous Ca/Mg-phosphate layer with high surface roughness. This surface layer, however, passivates and seals the Mg surface only partially. Subsequent Mg dissolution leads to a significantly stronger pH increase compared to NaOH-passivated samples, which prevents long-term cell survival. These results demonstrate that surface passivation with NaOH and M-SBF together with the associated changes of surface reactivity, chemistry and roughness provide a viable strategy to facilitate cell survival on otherwise non-biocompatible Mg surfaces.

Investigation of surface endothelialization on biomedical nitinol (NiTi) alloy: Effects of surface micropatterning combined with plasma nanocoatings.

PubMed

Shen, Yang; Wang, Guixue; Chen, Liang; Li, Hao; Yu, Ping; Bai, Mengjun; Zhang, Qin; Lee, James; Yu, Qingsong

2009-11-01

Plasma nanocoated films with trimethylsilane-oxygen monomers showed outstanding biocompatibility in our previous studies. In this study, endothelialization on biomedical nitinol alloy surfaces was systematically investigated. Our study focuses on elucidating the effects of surface micropatternings with micropores and microgrooves combined with plasma nanocoating. Plasma nanocoatings with controlled thickness between 40 and 50 nm were deposited onto micropatterned nitinol surface in a direct current plasma reactor. Bovine aortic endothelial cells were cultured in vitro on these nitinol samples for 1, 3 and 5 days. It was found that rougher surfaces could enhance cell adhesion compared with the smoother surfaces; the surfaces patterned with micropores showed much more endothelialization than microgrooved surface after a 3 days culture. The cell culture results also showed that plasma nanocoatings significantly further increased cell proliferation and cell adhesion on the micropatterned nitinol surfaces, as compared with non-plasma nanocoated surface of nitinol samples. The surface micropatternings combined with plasma nanocoatings could improve the cell adhesion and accelerate surface endothelialization after implantation of intravascular stents, which is expected to reduce in-stent restenosis.

Chronic lithium treatment up-regulates cell surface Na(V)1.7 sodium channels via inhibition of glycogen synthase kinase-3 in adrenal chromaffin cells: enhancement of Na(+) influx, Ca(2+) influx and catecholamine secretion after lithium withdrawal.

PubMed

Yanagita, Toshihiko; Maruta, Toyoaki; Nemoto, Takayuki; Uezono, Yasuhito; Matsuo, Kiyotaka; Satoh, Shinya; Yoshikawa, Norie; Kanai, Tasuku; Kobayashi, Hideyuki; Wada, Akihiko

2009-09-01

In cultured bovine adrenal chromaffin cells expressing Na(V)1.7 isoform of voltage-dependent Na(+) channels, we have previously reported that lithium chloride (LiCl) inhibits function of Na(+) channels independent of glycogen synthase kinase-3 (GSK-3) (Yanagita et al., 2007). Here, we further examined the effects of chronic lithium treatment on Na(+) channels. LiCl treatment (1-30 mM, > or = 12 h) increased cell surface [(3)H]saxitoxin ([(3)H]STX) binding by approximately 32% without altering the affinity of [(3)H]STX binding. This increase was prevented by cycloheximide and actinomycin D. SB216763 and SB415286 (GSK-3 inhibitors) also increased cell surface [(3)H]STX binding by approximately 31%. Simultaneous treatment with LiCl and SB216763 or SB415286 did not produce an increased effect on [(3)H]STX binding compared with either treatment alone. LiCl increased Na(+) channel alpha-subunit mRNA level by 32% at 24 h. LiCl accelerated alpha-subunit gene transcription by 35% without altering alpha-subunit mRNA stability. In LiCl-treated cells, LiCl inhibited veratridine-induced (22)Na(+) influx as in untreated cells. However, washout of LiCl after chronic treatment enhanced veratridine-induced (22)Na(+) influx, (45)Ca(2+) influx and catecholamine secretion by approximately 30%. Washout of LiCl after 24 h treatment shifted concentration-response curve of veratridine upon (22)Na(+) influx upward, without altering its EC(50) value. Ptychodiscus brevis toxin-3 allosterically enhanced veratridine-induced (22)Na(+) influx by two-fold in untreated and LiCl-treated cells. Whole-cell patch-clamp analysis indicated that I-V curve and steady-state inactivation/activation curves were comparable between untreated and LiCl-treated cells. Thus, GSK-3 inhibition by LiCl up-regulated cell surface Na(V)1.7 via acceleration of alpha-subunit gene transcription, enhancing veratridine-induced Na(+) influx, Ca(2+) influx and catecholamine secretion.

Evaluation of mechanism of cold atmospheric pressure plasma assisted polymerization of acrylic acid on low density polyethylene (LDPE) film surfaces: Influence of various gaseous plasma pretreatment

NASA Astrophysics Data System (ADS)

Ramkumar, M. C.; Pandiyaraj, K. Navaneetha; Arun Kumar, A.; Padmanabhan, P. V. A.; Uday Kumar, S.; Gopinath, P.; Bendavid, A.; Cools, P.; De Geyter, N.; Morent, R.; Deshmukh, R. R.

2018-05-01

Owing to its exceptional physiochemical properties, low density poly ethylene (LDPE) has wide range of tissue engineering applications. Conversely, its inadequate surface properties make LDPE an ineffectual candidate for cell compatible applications. Consequently, plasma-assisted polymerization with a selected precursor is a good choice for enhancing its biocompatibility. The present investigation studies the efficiency of plasma polymerization of acrylic acid (AAC) on various gaseous plasma pretreated LDPE films by cold atmospheric pressure plasma, to enhance its cytocompatibility. The change in chemical composition and surface topography of various gaseous plasma pretreated and acrylic deposited LDPE films has been assessed by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The changes in hydrophilic nature of surface modified LDPE films were studied by contact angle (CA) analysis. Cytocompatibility of the AAC/LDPE films was also studied in vitro, using RIN-5F cells. The results acquired by the XPS and AFM analysis clearly proved that cold atmospheric pressure (CAP) plasma assisted polymerization of AAC enhances various surface properties including carboxylic acid functional group density and increased surface roughness on various gaseous plasma treated AAC/LDPE film surfaces. Moreover, contact angle analysis clearly showed that the plasma polymerized samples were hydrophilic in nature. In vitro cytocompatibility analysis undoubtedly validates that the AAC polymerized various plasma pretreated LDPE films surfaces stimulate cell distribution and proliferation compared to pristine LDPE films. Similarly, cytotoxicity analysis indicates that the AAC deposited various gaseous plasma pretreated LDPE film can be considered as non-toxic as well as stimulating cell viability significantly. The cytocompatible properties of AAC polymerized Ar + O2 plasma pretreated LDPE films were found to be more pronounced compared to the other plasma pretreated AAC/LDPE films.

Engineering of global regulators and cell surface properties toward enhancing stress tolerance in Saccharomyces cerevisiae.

PubMed

Kuroda, Kouichi; Ueda, Mitsuyoshi

2017-12-01

Microbial cell factories are subject to various stresses, leading to the reductions of metabolic activity and bioproduction efficiency. Therefore, the development of stress-tolerant microorganisms is important for improving bio-production efficiency. Recently, modifications of cell surface properties and master regulators have been shown to be effective approaches for enhancing stress tolerance. The cell surface is an attractive target owing to its interactions with the environment and its role in transmitting environmental information. Cell surface engineering in yeast has enabled the convenient modification of cell surface properties. Displaying random peptide libraries and subsequent screening can successfully improve stress tolerance. Furthermore, master regulators including transcription factors are also promising target to be engineered because stress tolerance is determined by many cooperative factors and modification of master regulators can simultaneously affect the expression of multiple downstream genes. The key single amino acid mutations in transcription factors have been identified by analyzing tolerant yeasts that were isolated by adaptive evolution under stress conditions. This enabled the reconstruction of stress-tolerant yeast without burdening cells by introducing the identified mutations. Therefore, for the construction of stress-tolerant yeast from any strains, these two approaches are promising alternatives to conventional overexpression and deletion of stress-related genes. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Effects of Structural Properties of Electrospun TiO2 Nano-fiber Meshes on their Osteogenic Potential

PubMed Central

Wang, Xiaokun; Gittens, Rolando A.; Song, Rosemary; Tannenbaum, Rina; Olivares-Navarrete, Rene; Schwartz, Zvi; Chen, Haifeng; Boyan, Barbara D.

2011-01-01

Ideal outcomes in the field of tissue engineering and regenerative medicine involve biomaterials that can enhance cell differentiation and production of local factors for natural tissue regeneration without the use of systemic drugs. Biomaterials typically used in tissue engineering applications include polymeric scaffolds that mimic the 3-D structural environment of the native tissue, but these are often functionalized with proteins or small peptides to improve their biological performance. For bone applications, titanium (Ti) implants, or more appropriately the titania (TiO2) passive oxide layer formed on their surface, have been shown to enhance osteoblast differentiation in vitro and to promote osseointegration in vivo. In this study we evaluated the effect on osteoblast differentiation of pure TiO2 nano-fiber meshes with different surface micro-roughness and nano-fiber diameters, prepared by the electrospinning method. MG63 cells were seeded on TiO2 meshes, and cell number, differentiation markers and local factor production were analyzed. The results showed that cells grew throughout the entire surfaces and with similar morphology in all groups. Cell number was sensitive to surface micro-roughness, whereas cell differentiation and local factor production was regulated by both surface roughness and nano-fiber diameter. These results indicate that scaffold structural cues alone can be used to drive cell differentiation and create an osteogenic environment without the use of exogenous factors. PMID:22075122

Early osteoblast responses to orthopedic implants: Synergy of surface roughness and chemistry of bioactive ceramic coating.

PubMed

Aniket; Reid, Robert; Hall, Benika; Marriott, Ian; El-Ghannam, Ahmed

2015-06-01

Pro-osteogenic stimulation of bone cells by bioactive ceramic-coated orthopedic implants is influenced by both surface roughness and material chemistry; however, their concomitant impact on osteoblast behavior is not well understood. The aim of this study is to investigate the effects of nano-scale roughness and chemistry of bioactive silica-calcium phosphate nanocomposite (SCPC50) coated Ti-6Al-4V on modulating early bone cell responses. Cell attachment was higher on SCPC50-coated substrates compared to the uncoated controls; however, cells on the uncoated substrate exhibited greater spreading and superior quality of F-actin filaments than cells on the SCPC50-coated substrates. The poor F-actin filament organization on SCPC50-coated substrates is thought to be due to the enhanced calcium uptake by the ceramic surface. Dissolution analyses showed that an increase in surface roughness was accompanied by increased calcium uptake, and increased phosphorous and silicon release, all of which appear to interfere with F-actin assembly and osteoblast morphology. Moreover, cell attachment onto the SCPC50-coated substrates correlated with the known adsorption of fibronectin, and was independent of surface roughness. High-throughput genome sequencing showed enhanced expression of extracellular matrix and cell differentiation related genes. These results demonstrate a synergistic relationship between bioactive ceramic coating roughness and material chemistry resulting in a phenotype that leads to early osteoblast differentiation. © 2014 Wiley Periodicals, Inc.

Patterning of Novel Breast Implant Surfaces by Enhancing Silicone Biocompatibility, Using Biomimetic Topographies

PubMed Central

Barr, S.; Hill, E.; Bayat, A.

2010-01-01

Introduction and Aims: Silicone biocompatibility is dictated by cell-surface interaction and its understanding is important in the field of implantation. The role of surface topography and its associated cellular morphology needs investigation to identify qualities that enhance silicone surface biocompatability. This study aims to create well-defined silicone topographies and examine how breast tissue–derived fibroblasts react and align to these surfaces. Methods: Photolithographic microelectronic techniques were modified to produce naturally inspired topographies in silicone, which were cultured with breast tissue–derived human fibroblasts. Using light, immunofluorescent and atomic force microscopy, the cytoskeletal reaction of fibroblasts to these silicone surfaces was investigated. Results: Numerous, well-defined micron-sized pillars, pores, grooves, and ridges were manufactured and characterized in medical grade silicone. Inimitable immunofluorescent microscopy represented in our high magnification images of vinculin, vimentin, and the actin cytoskeleton highlights the differences in fibroblast adhesion between fabricated silicone surfaces. These unique figures illustrate that fibroblast adhesion and the reactions these cells have to silicone can be manipulated to enhance biointegration between the implant and the breast tissue. An alteration of fibroblast phenotype was also observed, exhibiting the propensity of these surfaces to induce categorical remodeling of fibroblasts. Conclusions: This unique study shows that fibroblast reactions to silicone topographies can be tailored to induce physiological changes in cells. This paves the way for further research necessary to develop more biocompatible constructs capable of eliminating capsular contracture by subverting the foreign body response. PMID:20458346

Comparative evaluation of the three different surface treatments - conventional, laser and Nano technology methods in enhancing the surface characteristics of commercially pure titanium discs and their effects on cell adhesion: An in vitro study.

PubMed

Vignesh; Nayar, Sanjna; Bhuminathan; Mahadevan; Santhosh, S

2015-04-01

The surface area of the titanium dental implant materials can be increased by surface treatments without altering their shape and form, thereby increasing the biologic properties of the biomaterial. A good biomaterial helps in early cell adhesion and cell signaling. In this study, the commercially pure titanium surfaces were prepared to enable machined surfaces to form a control material and to be compared with sandblasted and acid-etched surfaces, laser treated surfaces and titanium dioxide (20 nm) Nano-particle coated surfaces. The surface elements were characterized. The biocompatibility was evaluated by cell culture in vitro using L929 fibroblasts. The results suggested that the titanium dioxide Nano-particle coated surfaces had good osteoconductivity and can be used as a potential method for coating the biomaterial.

Tunable plasmon-enhanced broadband light harvesting for perovskite solar cells

NASA Astrophysics Data System (ADS)

Que, Meidan; Zhu, Liangliang; Yang, Yawei; Liu, Jie; Chen, Peng; Chen, Wei; Yin, Xingtian; Que, Wenxiu

2018-04-01

In this work, we report a reliable method for synthesizing (Au, Au/Ag core)/(TiO2 shell) nanostructures with their plasmonic wavelengths covering the visible light region for perovskite solar cells. The mono- and bi-metallic core-shell nanoparticles exhibit tunable localized surface plasmon resonance wavelength and function as "light tentacle" to improve the photo-electricity conversion efficiency. Plasmonic nanoparticles with different sizes and shapes, different thicknesses of TiO2 shell and Ag interlayer are found to have a strong influence on the localized surface plasmon resonance enhancement effect. The experimental photovoltaic performance of perovskite solar cells is significantly enhanced when the plasmonic nanoparticles are embedded inmesoporous TiO2 scaffolds. A champion photo-electricity conversion efficiency of 17.85% is achieved with nanoparticles (Au/Ag, λLSPR = 650 nm), giving a 18.7% enhancement over that of the pristine device (15.04%). Finite-difference time-domain simulations show that nanorod Au in mesoporus TiO2 scaffold induces the most intense electromagnetic coupling, and provides a novel emitter for photon flux in mesoporous perovskite solar cells. These theoretical results are consistent with the corresponding experimental those. Thus, enhancing the incident light intensities around 650 nm will be most favorable to the improvement of the photo-electricity conversion efficiency of perovskite solar cells.

Enhancement of the orientational order parameter of nematic liquid crystals in thin cells.

PubMed

Dhara, Surajit; Madhusudana, N V

2004-04-01

Abstract. We report measurements of birefringence (Delta n) of several nematic liquid crystals having transverse as well as longitudinal dipole moments in thin (1.4 to 2.3 microm) and thick (7 to 16 microm) cells. Rubbed polyimide-coated glass plates are used to get planar alignment of the nematic director in these cells. We find significant enhancement (6 to 18%) of Delta n (proportional to S, where S is the orientational order parameter) in thin cells in all compounds with aromatic cores even at temperatures far approximately 20 degrees C) below the nematic-isotropic transition point. The enhancement is larger in compounds having several phenyl rings and lower if the number of phenyl rings is reduced. In a compound that does not have an aromatic core no significant enhancement is observed, implying that the strength of the surface potential depends on the aromaticity of the cores. Assuming a perfect orientational order at the surface, calculations based on the Landau-de Gennes theory show that the thickness averaged enhancement of S is sharply reduced as the temperature is lowered in the nematic phase. The measured order parameter S is further enhanced in thin cells because of the stiffening of the elastic constant which reduces the thermal fluctuations of the nematic director. The combined effect is however too small at low temperatures to account for the experimental data.

Novel surface-enhanced Raman scattering-based assays for ultra-sensitive detection of human pluripotent stem cells.

PubMed

Han, Jingjia; Qian, Ximei; Wu, Qingling; Jha, Rajneesh; Duan, Jinshuai; Yang, Zhou; Maher, Kevin O; Nie, Shuming; Xu, Chunhui

2016-10-01

Human pluripotent stem cells (hPSCs) are a promising cell source for regenerative medicine, but their derivatives need to be rigorously evaluated for residual stem cells to prevent teratoma formation. Here, we report the development of novel surface-enhanced Raman scattering (SERS)-based assays that can detect trace numbers of undifferentiated hPSCs in mixed cell populations in a highly specific, ultra-sensitive, and time-efficient manner. By targeting stem cell surface markers SSEA-5 and TRA-1-60 individually or simultaneously, these SERS assays were able to identify as few as 1 stem cell in 10(6) cells, a sensitivity (0.0001%) which was ∼2000 to 15,000-fold higher than that of flow cytometry assays. Using the SERS assay, we demonstrate that the aggregation of hPSC-based cardiomyocyte differentiation cultures into 3D spheres significantly reduced SSEA-5(+) and TRA-1-60(+) cells compared with parallel 2D cultures. Thus, SERS may provide a powerful new technology for quality control of hPSC-derived products for preclinical and clinical applications. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

MC3T3-E1 Cells on Titanium Surfaces with Nanometer Smoothness and Fibronectin Immobilization

PubMed Central

Hayakawa, Tohru; Yoshida, Eiji; Yoshimura, Yoshitaka; Uo, Motohiro; Yoshinari, Masao

2012-01-01

The present study was aimed to evaluate the viability and total protein contents of osteoblast-like cells on the titanium surface with different surface mechanical treatment, namely, nanometer smoothing (Ra: approximately 2.0 nm) and sandblasting (Ra: approximately 1.0 μm), and biochemical treatment, namely, with or without fibronectin immobilization. Fibronectin could be easily immobilized by tresyl chloride-activation technique. MC3T3-E1 cells were seeded on the different titanium surfaces. Cell viability was determined by MTT assay. At 1 day of cell culture, there were no significant differences in cell viability among four different titanium surfaces. At 11 days, sandblasted titanium surface with fibronectin immobilization showed the significantly highest cell viability than other titanium surface. No significant differences existed for total protein contents among four different titanium surfaces at 11 days of cell culture. Scanning electron microscopy observation revealed that smoothness of titanium surface produced more spread cell morphologies, but that fibronectin immobilization did not cause any changes of the morphologies of attached cells. Fibronectin immobilization provided greater amount of the number of attached cells and better arrangement of attached cells. In conclusion, the combination of sandblasting and fibronectin immobilization enhanced the cell viability and fibronectin immobilization providing better arrangements of attached cells. PMID:22675359

Biological Response of Human Bone Marrow-Derived Mesenchymal Stem Cells to Commercial Tantalum Coatings with Microscale and Nanoscale Surface Topographies

NASA Astrophysics Data System (ADS)

Skoog, Shelby A.; Kumar, Girish; Goering, Peter L.; Williams, Brian; Stiglich, Jack; Narayan, Roger J.

2016-06-01

Tantalum is a promising orthopaedic implant coating material due to its robust mechanical properties, corrosion resistance, and excellent biocompatibility. Previous studies have demonstrated improved biocompatibility and tissue integration of surface-treated tantalum coatings compared to untreated tantalum. Surface modification of tantalum coatings with biologically inspired microscale and nanoscale features may be used to evoke optimal tissue responses. The goal of this study was to evaluate commercial tantalum coatings with nanoscale, sub-microscale, and microscale surface topographies for orthopaedic and dental applications using human bone marrow-derived mesenchymal stem cells (hBMSCs). Tantalum coatings with different microscale and nanoscale surface topographies were fabricated using a diffusion process or chemical vapor deposition. Biological evaluation of the tantalum coatings using hBMSCs showed that tantalum coatings promote cellular adhesion and growth. Furthermore, hBMSC adhesion to the tantalum coatings was dependent on surface feature characteristics, with enhanced cell adhesion on sub-micrometer- and micrometer-sized surface topographies compared to hybrid nano-/microstructures. Nanostructured and microstructured tantalum coatings should be further evaluated to optimize the surface coating features to promote osteogenesis and enhance osseointegration of tantalum-based orthopaedic implants.

Conjugation of arginine-glycine-aspartic acid peptides to poly(ethylene oxide)-b-poly(epsilon-caprolactone) micelles for enhanced intracellular drug delivery to metastatic tumor cells.

PubMed

Xiong, Xiao-Bing; Mahmud, Abdullah; Uludağ, Hasan; Lavasanifar, Afsaneh

2007-03-01

An arginine-glycine-aspartic acid (RGD) containing model peptide was conjugated to the surface of poly(ethylene oxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL) micelles as a ligand that can recognize adhesion molecules overexpressed on the surface of metastatic cancer cells, that is, integrins, and that can enhance the micellar delivery of encapsulated hydrophobic drug into a tumor cell. Toward this goal, PEO-b-PCL copolymers bearing acetal groups on the PEO end were synthesized, characterized, and assembled to polymeric micelles. The acetal group on the surface of the PEO-b-PCL micelles was converted to reactive aldehyde under acidic condition at room temperature. An RGD-containing linear peptide, GRGDS, was conjugated on the surface of the aldehyde-decorated PEO-b-PCL micelles by incubation at room temperature. A hydrophobic fluorescent probe, that is, DiI, was physically loaded in prepared polymeric micelles to imitate hydrophobic drugs loaded in micellar carrier. The cellular uptake of DiI loaded GRGDS-modified micelles by melanoma B16-F10 cells was investigated at 4 and 37 degrees C by fluorescent spectroscopy and confocal microscopy techniques and was compared to the uptake of DiI loaded valine-PEO-b-PCL micelles (as the irrelevant ligand decorated micelles) and free DiI. GRGDS conjugation to polymeric micelles significantly facilitated the cellular uptake of encapsulated hydrophobic DiI most probably by intergrin-mediated cell attachment and endocytosis. The results indicate that acetal-terminated PEO-b-PCL micelles are amenable for introducing targeting moieties on the surface of polymeric micelles and that RGD-peptide conjugated PEO-b-PCL micelles are promising ligand-targeted carriers for enhanced drug delivery to metastatic tumor cells.

Microstructured Titanium Regulates Interleukin Production by Osteoblasts, an Effect Modulated by Exogenous BMP-2

PubMed Central

Hyzy, Sharon; Olivares-Navarrete, Rene; Hutton, Daphne L.; Tan, Christian; Boyan, Barbara D.; Schwartz, Zvi

2013-01-01

Microtextured implant surfaces increase osteoblast differentiation in vitro and enhance bone-to-implant contact in vivo and clinically. These implants may be used in combination with recombinant human bone morphogenetic protein 2 (rhBMP-2) to enhance peri-implant bone formation. However, the effect of surface modifications alone or in combination with rhBMP-2 on osteoblast-produced inflammatory microenvironment is unknown. MG63 cells were cultured on tissue culture polystyrene or titanium substrates: smooth pretreated (PT, Ra=0.2μm), sandblasted/acid-etched (SLA, Ra=3.2μm), or hydrophilic-SLA (modSLA). Expression and protein production of pro-inflammatory interleukins (IL1b, IL6, IL8, IL17) and anti-inflammatory interleukins (IL10) were measured in cells with or without rhBMP-2. To determine which BMP signaling pathways were involved, cultures were incubated with BMP pathway inhibitors to blocking Smad (dorsomorphin), TAB/TAK1 ((5Z)-7-oxozeaenol), or PKA (H-8) signaling. Culture on rough SLA and modSLA surfaces decreased pro-inflammatory interleukins and increased anti-inflammatory IL10. This effect was negated in cells treated with rhBMP-2, which caused an increase in pro-inflammatory interleukins and a decrease in anti-inflammatory interleukins through TAB/TAK signaling. The results suggest that surface microtexture modulates the inflammatory process during osseointegration, an effect that may enhance healing. However, rhBMP-2 in combination with microtextured titanium implants can influence the effect of cells on these surfaces, and may adversely affect cells involved in osseointegration. PMID:23123301

Plasmon Enhanced Hetero-Junction Solar Cell

NASA Astrophysics Data System (ADS)

Long, Gen; Ching, Levine; Sadoqi, Mostafa; Xu, Huizhong

2015-03-01

Here we report a systematic study of plasmon-enhanced hetero-junction solar cells made of colloidal quantum dots (PbS) and nanowires (ZnO), with/without metal nanoparticles (Au). The structure of solar cell devices was characterized by AFM, SEM and profilometer, etc. The power conversion efficiencies of solar cell devices were characterized by solar simulator (OAI TriSOL, AM1.5G Class AAA). The enhancement in the photocurrent due to introduction of metal nanoparticles was obvious. We believe this is due to the plasmonic effect from the metal nanoparticles. The correlation between surface roughness, film uniformity and device performance was also studied.

Ions, metabolites, and cells: Water as a reporter of surface conditions during bacterial growth.

PubMed

Jarisz, Tasha A; Lane, Sarah; Gozdzialski, Lea; Hore, Dennis K

2018-06-14

Surface-specific nonlinear vibrational spectroscopy, combined with bulk solution measurements and imaging, is used to study the surface conditions during the growth of E. coli. As a result of the silica high surface charge density, the water structure at the silica-aqueous interface is known to be especially sensitive to pH and ionic strength, and surface concentration profiles develop that can be appreciably different from the bulk solution conditions. We illustrate that, in the presence of growing cells, a unique surface micro-environment is established as a result of metabolites accumulating on the silica surface. Even in the subsequent absence of the cells, this surface layer works to reduce the interfacial ionic strength as revealed by the enhanced signal from surface water molecules. In the presence of growing cells, an additional boost in surface water signal is attributed to a local pH that is higher than that of the bulk solution.

Ions, metabolites, and cells: Water as a reporter of surface conditions during bacterial growth

NASA Astrophysics Data System (ADS)

Jarisz, Tasha A.; Lane, Sarah; Gozdzialski, Lea; Hore, Dennis K.

2018-06-01

Surface-specific nonlinear vibrational spectroscopy, combined with bulk solution measurements and imaging, is used to study the surface conditions during the growth of E. coli. As a result of the silica high surface charge density, the water structure at the silica-aqueous interface is known to be especially sensitive to pH and ionic strength, and surface concentration profiles develop that can be appreciably different from the bulk solution conditions. We illustrate that, in the presence of growing cells, a unique surface micro-environment is established as a result of metabolites accumulating on the silica surface. Even in the subsequent absence of the cells, this surface layer works to reduce the interfacial ionic strength as revealed by the enhanced signal from surface water molecules. In the presence of growing cells, an additional boost in surface water signal is attributed to a local pH that is higher than that of the bulk solution.

GARP-TGF-β complexes negatively regulate regulatory T cell development and maintenance of peripheral CD4+ T cells in vivo.

PubMed

Zhou, Angela X; Kozhaya, Lina; Fujii, Hodaka; Unutmaz, Derya

2013-05-15

The role of surface-bound TGF-β on regulatory T cells (Tregs) and the mechanisms that mediate its functions are not well defined. We recently identified a cell-surface molecule called Glycoprotein A Repetitions Predominant (GARP), which is expressed specifically on activated Tregs and was found to bind latent TGF-β and mediate a portion of Treg suppressive activity in vitro. In this article, we address the role of GARP in regulating Treg and conventional T cell development and immune suppression in vivo using a transgenic mouse expressing GARP on all T cells. We found that, despite forced expression of GARP on all T cells, stimulation through the TCR was required for efficient localization of GARP to the cell surface. In addition, IL-2 signals enhanced GARP cell surface expression specifically on Tregs. GARP-transgenic CD4(+) T cells and Tregs, especially those expressing higher levels of GARP, were significantly reduced in the periphery. Mature Tregs, but not conventional CD4(+) T cells, were also reduced in the thymus. CD4(+) T cell reduction was more pronounced within the effector/memory subset, especially as the mouse aged. In addition, GARP-overexpressing CD4(+) T cells stimulated through the TCR displayed reduced proliferative capacity, which was restored by inhibiting TGF-β signaling. Furthermore, inhibiting TGF-β signals greatly enhanced surface expression of GARP on Tregs and blocked the induction of Foxp3 in activated CD4(+) T cells overexpressing GARP. These findings suggest a role for GARP in natural and induced Treg development through activation of bound latent TGF-β and signaling, which negatively regulates GARP expression on Tregs.

Micro/nano hierarchical structured titanium treated by NH4OH/H2O2 for enhancing cell response

PubMed Central

Yuan, Xin; Kang, Yi; Zuo, Jun; Xie, Youneng; Ma, Li; Ren, Xuelei; Bian, Zeyu; Zhou, Kechao; Wang, Xiyang; Yu, Zhiming

2018-01-01

In this paper, two kinds of titanium surfaces with novel micro/nano hierarchical structures, namely Etched (E) surface and Sandblast and etched (SE) surface, were successfully fabricated by NH4OH and H2O2 mixture. And their cellular responses of MG63 were investigated compared with Sandblast and acid-etching (SLA) surface. Scanning electron microscope (SEM), Surface profiler, X-ray photoelectron spectroscopy (XPS), and Contact angle instrument were employed to assess the surface morphologies, roughness, chemistry and wettability respectively. Hierarchical structures with micro holes of 10–30 μm in diameter and nano pits of tens of nanometers in diameter formed on both E and SE surfaces. The size of micro holes is very close to osteoblast cell, which makes them wonderful beds for osteoblast. Moreover, these two kinds of surfaces possess similar roughness and superior hydrophilicity to SLA. Reactive oxygen species were detected on E and SE surface, and thus considerable antimicrobial performance and well fixation can be speculated on them. The cell experiments also demonstrated a boost in cell attachment, and that proliferation and osteogenic differentiation were achieved on them, especially on SE surface. The results indicate that the treatment of pure titanium with H2O2/NH4OH is an effective technique to improve the initial stability of implants and enhance the osseointegration, which may be a promising surface treatment to titanium implant. PMID:29723214

Efficiency enhancement of organic solar cells using transparent plasmonic Ag nanowire electrodes.

PubMed

Kang, Myung-Gyu; Xu, Ting; Park, Hui Joon; Luo, Xiangang; Guo, L Jay

2010-10-15

Surface plasmon enhanced photo-current and power conversion efficiency of organic solar cells using periodic Ag nanowires as transparent electrodes are reported, as compared to the device with conventional ITO electrodes. External quantum efficiencies are enhanced about 2.5 fold around the peak solar spectrum wavelength of 560 nm, resulting in 35% overall increase in power conversion efficiency than the ITO control device under normal unpolarized light.

Enhanced Lifetime of Polymer Solar Cells by Surface Passivation of Metal Oxide Buffer Layers.

PubMed

Venkatesan, Swaminathan; Ngo, Evan; Khatiwada, Devendra; Zhang, Cheng; Qiao, Qiquan

2015-07-29

The role of electron selective interfaces on the performance and lifetime of polymer solar cells were compared and analyzed. Bilayer interfaces consisting of metal oxide films with cationic polymer modification namely poly ethylenimine ethoxylated (PEIE) were found to enhance device lifetime compared to bare metal oxide films when used as an electron selective cathode interface. Devices utilizing surface-modified metal oxide layers showed enhanced lifetimes, retaining up to 85% of their original efficiency when stored in ambient atmosphere for 180 days without any encapsulation. The work function and surface potential of zinc oxide (ZnO) and ZnO/PEIE interlayers were evaluated using Kelvin probe and Kelvin probe force microscopy (KPFM) respectively. Kelvin probe measurements showed a smaller reduction in work function of ZnO/PEIE films compared to bare ZnO films when aged in atmospheric conditions. KPFM measurements showed that the surface potential of the ZnO surface drastically reduces when stored in ambient air for 7 days because of surface oxidation. Surface oxidation of the interface led to a substantial decrease in the performance in aged devices. The enhancement in the lifetime of devices with a bilayer interface was correlated to the suppressed surface oxidation of the metal oxide layers. The PEIE passivated surface retained a lower Fermi level when aged, which led to lower trap-assisted recombination at the polymer-cathode interface. Further photocharge extraction by linearly increasing voltage (Photo-CELIV) measurements were performed on fresh and aged samples to evaluate the field required to extract maximum charges. Fresh devices with a bare ZnO cathode interlayer required a lower field than devices with ZnO/PEIE cathode interface. However, aged devices with ZnO required a much higher field to extract charges while aged devices with ZnO/PEIE showed a minor increase compared to the fresh devices. Results indicate that surface modification can act as a suitable passivation layer to suppress oxidation in metal oxide thin films for enhanced lifetime in inverted organic solar cells.

Genetic modification of mesenchymal stem cells to express a single-chain antibody against EGFRvIII on the cell surface.

PubMed

Balyasnikova, Irina V; Franco-Gou, Rosa; Mathis, J Michael; Lesniak, Maciej S

2010-06-01

Human adult mesenchymal stem cells (hMSCs) are under active investigation as cellular carriers for gene therapy. hMSCs possess natural tropism toward tumours; however, the targeting of hMSCs to specific cell populations within tumours is unexplored. In the case of glioblastoma multiforme (GBM), at least half of the tumours express EGFRvIII on the cell surface, an ideal target for antibody-mediated gene/drug delivery. In this study, we investigated the feasibility of genetically modifying hMSCs to express a single-chain antibody (scFv) to EGFRvIII on their surfaces. Nucleofection was used to transfect hMSCs with cDNA encoding scFv EGFRvIII fused with PDGFR or human B7-1 transmembrane domains. The expression of scFv EGFRvIII on the cell surface was assessed by FACS. A stable population of scFv EGFRvIII-expressing hMSCs was selected, based on antibiotic resistance, and enriched using FACS. We found that nucleofection allows the efficient expression of scFv EGFRvIII on the cell surface of hMSCs. hMSCs transfected with the construct encoding scFv EGFRvIII as a fusion with PDGFRtm showed scFv EGFRvIII expression in up to 86% of cells. Most importantly, human MSCs expressing scFv against EGFRvIII demonstrated enhanced binding to U87-EGFRvIII cells in vitro and significantly increased retention in human U87-EGFRvIII-expressing tumours in vivo. In summary, we provide the first conclusive evidence of genetic modification of hMSCs with a single-chain antibody against an antigen expressed on the surface of tumour cells, thereby opening up a new venue for enhanced delivery of gene therapy applications in the context of malignant brain cancer. Copyright 2009 John Wiley & Sons, Ltd.

Plasma treatment induces internal surface modifications of electrospun poly(L-lactic) acid scaffold to enhance protein coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin Seo, Hyok; Hee Lee, Mi; Kwon, Byeong-Ju

2013-08-21

Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion andmore » maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold and the penetration efficiency with fibronectin was investigated. Field-emission scanning electron microscope images showed that some grooves were formed on the PLLA fibers after plasma treatment. X-ray photoelectron spectroscopy data also showed chemical changes in the PLLA structure. After plasma treatment, -CN (285.76 eV) was increased in C1s and -NH{sub 2} (399.70 eV) was increased significantly and –N=CH (400.80 eV) and –NH{sub 3}{sup +} (402.05 eV) were newly appeared in N1s. These changes allowed fibronectin to penetrate into the PLLA scaffold; this could be observed by confocal microscopy. In conclusion, helium atmospheric pressure plasma treatment was effective in modifying the polymeric scaffold, making it hydrophilic, and this treatment can also be used in tissue engineering research as needed to make polymers hydrophilic.« less

Engineering Novel and Improved Biocatalysts by Cell Surface Display

PubMed Central

Smith, Mason R.; Khera, Eshita; Wen, Fei

2017-01-01

Biocatalysts, especially enzymes, have the ability to catalyze reactions with high product selectivity, utilize a broad range of substrates, and maintain activity at low temperature and pressure. Therefore, they represent a renewable, environmentally friendly alternative to conventional catalysts. Most current industrial-scale chemical production processes using biocatalysts employ soluble enzymes or whole cells expressing intracellular enzymes. Cell surface display systems differ by presenting heterologous enzymes extracellularly, overcoming some of the limitations associated with enzyme purification and substrate transport. Additionally, coupled with directed evolution, cell surface display is a powerful platform for engineering enzymes with enhanced properties. In this review, we will introduce the molecular and cellular principles of cell surface display and discuss how it has been applied to engineer enzymes with improved properties as well as to develop surface-engineered microbes as whole-cell biocatalysts. PMID:29056821

Dual-Color Fluorescence Imaging of EpCAM and EGFR in Breast Cancer Cells with a Bull's Eye-Type Plasmonic Chip.

PubMed

Izumi, Shota; Yamamura, Shohei; Hayashi, Naoko; Toma, Mana; Tawa, Keiko

2017-12-19

Surface plasmon field-enhanced fluorescence microscopic observation of a live breast cancer cell was performed with a plasmonic chip. Two cell lines, MDA-MB-231 and Michigan Cancer Foundation-7 (MCF-7), were selected as breast cancer cells, with two kinds of membrane protein, epithelial cell adhesion molecule (EpCAM) and epidermal growth factor receptor (EGFR), observed in both cells. The membrane proteins are surface markers used to differentiate and classify breast cancer cells. EGFR and EpCAM were detected with Alexa Fluor ® 488-labeled anti-EGFR antibody (488-EGFR) and allophycocyanin (APC)-labeled anti-EpCAM antibody (APC-EpCAM), respectively. In MDA-MB231 cells, three-fold plus or minus one and seven-fold plus or minus two brighter fluorescence of 488-EGFR were observed on the 480-nm pitch and the 400-nm pitch compared with that on a glass slide. Results show the 400-nm pitch is useful. Dual-color fluorescence of 488-EGFR and APC-EpCAM in MDA-MB231 was clearly observed with seven-fold plus or minus two and nine-fold plus or minus three, respectively, on the 400-nm pitch pattern of a plasmonic chip. Therefore, the 400-nm pitch contributed to the dual-color fluorescence enhancement for these wavelengths. An optimal grating pitch of a plasmonic chip improved a fluorescence image of membrane proteins with the help of the surface plasmon-enhanced field.

Cell recognition molecule L1 promotes embryonic stem cell differentiation through the regulation of cell surface glycosylation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Ying; Department of Clinical Laboratory, Second Affiliated Hospital of Dalian Medical University, Dalian 116023; Huang, Xiaohua

2013-10-25

Highlights: •Down-regulating FUT9 and ST3Gal4 expression blocks L1-induced neuronal differentiation of ESCs. •Up-regulating FUT9 and ST3Gal4 expression in L1-ESCs depends on the activation of PLCγ. •L1 promotes ESCs to differentiate into neuron through regulating cell surface glycosylation. -- Abstract: Cell recognition molecule L1 (CD171) plays an important role in neuronal survival, migration, differentiation, neurite outgrowth, myelination, synaptic plasticity and regeneration after injury. Our previous study has demonstrated that overexpressing L1 enhances cell survival and proliferation of mouse embryonic stem cells (ESCs) through promoting the expression of FUT9 and ST3Gal4, which upregulates cell surface sialylation and fucosylation. In the present study,more » we examined whether sialylation and fucosylation are involved in ESC differentiation through L1 signaling. RNA interference analysis showed that L1 enhanced differentiation of ESCs into neurons through the upregulation of FUT9 and ST3Gal4. Furthermore, blocking the phospholipase Cγ (PLCγ) signaling pathway with either a specific PLCγ inhibitor or knockdown PLCγ reduced the expression levels of both FUT9 and ST3Gal4 mRNAs and inhibited L1-mediated neuronal differentiation. These results demonstrate that L1 promotes neuronal differentiation from ESCs through the L1-mediated enhancement of FUT9 and ST3Gal4 expression.« less

Nanotextured PDMS Substrates for Enhanced Roughness and Aptamer Immobilization for Cancer Cell Capture

NASA Astrophysics Data System (ADS)

Islam, Muhymin; Mahmood, Arif; Bellah, Md.; Kim, Young-Tae; Iqbal, Samir

2014-03-01

Detection of circulating tumor cells (CTCs) in the early stages of cancer is requires very sensitive approach. Nanotextured polydimethylsiloxane (PDMS) substrates were fabricated by micro reactive ion etching (Micro-RIE) to have better control on surface morphology and to improve the affinity of PDMS surfaces to capture cancer cells using surface immobilized aptamers. The aptamers were specific to epidermal growth factor receptors (EGFR) present in cell membranes, and overexpressed in tumor cells. We also investigated the effect of nano-scale features on cell capturing by implementing various surfaces of different roughnesses. Three different recipes were used to prepare nanotextured PDMS by micro-RIE using oxygen (O2) and carbon tetrafluoride (CF4). The measured average roughness of three nanotextured PDMS surfaces were found to impact average densities of captured cells. In all cases, nanotextured PDMS facilitated cell capturing possibly due to increased effective surface area of roughened substrates at nanoscale. It was also observed that cell capture efficiency was higher for higher surface roughness. The nanotextured PDMS substrates are thus useful for cancer cytology devices.

Surface decoration by Spirulina polysaccharide enhances the cellular uptake and anticancer efficacy of selenium nanoparticles.

PubMed

Yang, Fang; Tang, Quanming; Zhong, Xueyun; Bai, Yan; Chen, Tianfeng; Zhang, Yibo; Li, Yinghua; Zheng, Wenjie

2012-01-01

A simple and solution-phase method for functionalization of selenium nanoparticles (SeNPs) with Spirulina polysaccharides (SPS) has been developed in the present study. The cellular uptake and anticancer activity of SPS-SeNPs were also evaluated. Monodisperse and homogeneous spherical SPS-SeNPs with diameters ranging from 20 nm to 50 nm were achieved under optimized conditions, which were stable in the solution phase for at least 3 months. SPS surface decoration significantly enhanced the cellular uptake and cytotoxicity of SeNPs toward several human cancer cell lines. A375 human melanoma cells were found extremely susceptible to SPS-SeNPs with half maximal (50%) inhibitory concentration value of 7.94 μM. Investigation of the underlying mechanisms revealed that SPS-SeNPs inhibited cancer cell growth through induction of apoptosis, as evidenced by an increase in sub-G(1) cell population, deoxyribonucleic acid fragmentation, chromatin condensation, and phosphatidylserine translocation. Results suggest that the strategy to use SPS as a surface decorator could be an effective way to enhance the cellular uptake and anticancer efficacy of nanomaterials. SPS-SeNPs may be a potential candidate for further evaluation as a chemopreventive and chemotherapeutic agent against human cancers.

Surface decoration by Spirulina polysaccharide enhances the cellular uptake and anticancer efficacy of selenium nanoparticles

PubMed Central

Yang, Fang; Tang, Quanming; Zhong, Xueyun; Bai, Yan; Chen, Tianfeng; Zhang, Yibo; Li, Yinghua; Zheng, Wenjie

2012-01-01

A simple and solution-phase method for functionalization of selenium nanoparticles (SeNPs) with Spirulina polysaccharides (SPS) has been developed in the present study. The cellular uptake and anticancer activity of SPS-SeNPs were also evaluated. Monodisperse and homogeneous spherical SPS-SeNPs with diameters ranging from 20 nm to 50 nm were achieved under optimized conditions, which were stable in the solution phase for at least 3 months. SPS surface decoration significantly enhanced the cellular uptake and cytotoxicity of SeNPs toward several human cancer cell lines. A375 human melanoma cells were found extremely susceptible to SPS-SeNPs with half maximal (50%) inhibitory concentration value of 7.94 μM. Investigation of the underlying mechanisms revealed that SPS-SeNPs inhibited cancer cell growth through induction of apoptosis, as evidenced by an increase in sub-G1 cell population, deoxyribonucleic acid fragmentation, chromatin condensation, and phosphatidylserine translocation. Results suggest that the strategy to use SPS as a surface decorator could be an effective way to enhance the cellular uptake and anticancer efficacy of nanomaterials. SPS-SeNPs may be a potential candidate for further evaluation as a chemopreventive and chemotherapeutic agent against human cancers. PMID:22359460

Electron-beam induced current characterization of back-surface field solar cells using a chopped scanning electron microscope beam

NASA Technical Reports Server (NTRS)

Luke, K. L.; Cheng, L.-J.

1984-01-01

A chopped electron beam induced current (EBIC) technique for the chacterization of back-surface field (BSF) solar cells is presented. It is shown that the effective recombination velocity of the low-high junction forming the back-surface field of BSF cells, in addition to the diffusion length and the surface recombination velocity of the surface perpendicular to both the p-n and low-high junctions, can be determined from the data provided by a single EBIC scan. The method for doing so is described and illustrated. Certain experimental considerations taken to enhance the quality of the EBIC data are also discussed.

Enhanced proliferation of PC12 neural cells on untreated, nanotextured glass coverslips

NASA Astrophysics Data System (ADS)

Islam, Muhymin; Atmaramani, Rahul; Mukherjee, Siddhartha; Ghosh, Santaneel; Iqbal, Samir M.

2016-10-01

Traumatic injury to the central nervous system is a significant health problem. There is no effective treatment available partly because of the complexity of the system. Implementation of multifunctional micro- and nano-device based combinatorial therapeutics can provide biocompatible and tunable approaches to perform on-demand release of specific drugs. This can help the damaged cells to improve neuronal survival, regeneration of axons, and their reconnection to appropriate targets. Nano-topological features induced rapid cell growth is especially important towards the design of effective platforms to facilitate damaged neural circuit reconstruction. In this study, for the first time, feasibility of neuron-like PC12 cell growth on untreated and easy to prepare nanotextured surfaces has been carried out. The PC12 neuron-like cells were cultured on micro reactive ion etched nanotextured glass coverslips. The effect of nanotextured topology as physical cue for the growth of PC12 cells was observed exclusively, eliminating the possible influence(s) of the enhanced concentration of coated materials on the surface. The cell density was observed to increase by almost 200% on nanotextured coverslips compared to plain coverslips. The morphology study indicated that PC12 cell attachment and growth on the nanotextured substrates did not launch any apoptotic machinery of the cell. Less than 5% cells deformed and depicted condensed nuclei with apoptotic bodies on nanotextured surfaces which is typical for the normal cell handling and culture. Enhanced PC12 cell proliferation by such novel and easy to prepare substrates is not only attractive for neurite outgrowth and guidance, but may be used to increase the affinity of similar cancerous cells (ex: B35 neuroblastoma) and rapid proliferation thereafter—towards the development of combinatorial theranostics to diagnose and treat aggressive cancers like neuroblastoma.

Improving polymer/nanocrystal hybrid solar cell performance via tuning ligand orientation at CdSe quantum dot surface.

PubMed

Fu, Weifei; Wang, Ling; Zhang, Yanfang; Ma, Ruisong; Zuo, Lijian; Mai, Jiangquan; Lau, Tsz-Ki; Du, Shixuan; Lu, Xinhui; Shi, Minmin; Li, Hanying; Chen, Hongzheng

2014-11-12

Achieving superior solar cell performance based on the colloidal nanocrystals remains challenging due to their complex surface composition. Much attention has been devoted to the development of effective surface modification strategies to enhance electronic coupling between the nanocrystals to promote charge carrier transport. Herein, we aim to attach benzenedithiol ligands onto the surface of CdSe nanocrystals in the "face-on" geometry to minimize the nanocrystal-nanocrystal or polymer-nanocrystal distance. Furthermore, the "electroactive" π-orbitals of the benzenedithiol are expected to further enhance the electronic coupling, which facilitates charge carrier dissociation and transport. The electron mobility of CdSe QD films was improved 20 times by tuning the ligand orientation, and high performance poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT):CdSe nanocrystal hybrid solar cells were also achieved, showing a highest power conversion efficiency of 4.18%. This research could open up a new pathway to improve further the performance of colloidal nanocrystal based solar cells.

Matrigel immobilization on the shish-kebab structured poly(ε-caprolactone) nanofibers for skin tissue engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jing, Xin, E-mail: jingxinscut@gmail.com; Mi, Hao-Yang; Wisconsin Institutes for Discovery, University of Wisconsin-Madison, 53715

Surface properties of tissue engineering scaffolds such as topography, hydrophilicity, and functional groups play a vital role in cell adhesion, migration, proliferation, and apoptosis. First, poly(ε-caprolactone) (PCL) shish-kebab scaffolds (PCL-SK), which feature a three-dimensional structure comprised of electrospun PCL nanofibers covered by periodic, self-induced PCL crystal lamellae on the surface, was created to mimic the nanotopography of native collagen fibrils in the extracellular matrix (ECM). Second, matrigel was covalently immobilized on the surface of alkaline hydrolyzed PCL-SK scaffolds to enhance their hydrophilicity. This combined approach not only mimics the nanotopography of native collagen fibrils, but also simulates the surface featuresmore » of collagen fibrils for cell growth. To investigate the viability of such scaffolds, HEF1 fibroblast cell assays were conducted and the results revealed that the nanotopography of the PCL-SK scaffolds facilitated cell adhesion and proliferation. The matrigel functionalization on PCL-SK scaffolds further enhanced cellular response, which suggested elevated biocompatibility and greater potential for skin tissue engineering applications.« less

Involvement of up-regulated Necl-5/Tage4/PVR/CD155 in the loss of contact inhibition in transformed NIH3T3 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minami, Yukiko; Department of Surgery and Clinical Oncology, Osaka University Graduate School of Medicine/Faculty of Medicine, Suita 565-0871, Osaka; Ikeda, Wataru

2007-01-26

Normal cells show contact inhibition of cell movement and proliferation, but this is lost following transformation. We found that Necl-5, originally identified as a poliovirus receptor and up-regulated in many cancer cells, enhances growth factor-induced cell movement and proliferation. We showed that when cells contact other cells, Necl-5 interacts in trans with nectin-3 and is removed by endocytosis from the cell surface, resulting in a reduction of cell movement and proliferation. We show here that up-regulation of the gene encoding Necl-5 by the oncogene V12-Ki-Ras causes enhanced cell movement and proliferation. Upon cell-cell contact, de novo synthesis of Necl-5 exceedsmore » the rate of Necl-5 endocytosis, eventually resulting in a net increase in the amount of Necl-5 at the cell surface. In addition, expression of the gene encoding nectin-3 is markedly reduced in transformed cells. Thus, up-regulation of Necl-5 following transformation contributes to the loss of contact inhibition in transformed cells.« less

Effect of surface roughness on osteogenesis in vitro and osseointegration in vivo of carbon fiber-reinforced polyetheretherketone–nanohydroxyapatite composite

PubMed Central

Deng, Yi; Liu, Xiaochen; Xu, Anxiu; Wang, Lixin; Luo, Zuyuan; Zheng, Yunfei; Deng, Feng; Wei, Jie; Tang, Zhihui; Wei, Shicheng

2015-01-01

As United States Food and Drug Administration-approved implantable material, carbon fiber-reinforced polyetheretherketone (CFRPEEK) possesses an adjustable elastic modulus similar to cortical bone and is a prime candidate to replace surgical metallic implants. The bioinertness and inferior osteogenic properties of CFRPEEK, however, limit its clinical application as orthopedic/dental implants. In this study, CFRPEEK–nanohydroxyapatite ternary composites (PEEK/n-HA/CF) with variable surface roughness have been successfully fabricated. The effect of surface roughness on their in vitro cellular responses of osteoblast-like MG-63 cells (attachment, proliferation, apoptosis, and differentiation) and in vivo osseointegration is evaluated. The results show that the hydrophilicity and the amount of Ca ions on the surface are significantly improved as the surface roughness of composite increases. In cell culture tests, the results reveal that the cell proliferation rate and the extent of osteogenic differentiation of cells are a function of the size of surface roughness. The composite with moderate surface roughness significantly increases cell attachment/proliferation and promotes the production of alkaline phosphatase (ALP) activity and calcium nodule formation compared with the other groups. More importantly, the PEEK/n-HA/CF implant with appropriate surface roughness exhibits remarkably enhanced bioactivity and osseointegration in vivo in the animal experiment. These findings will provide critical guidance for the design of CFRPEEK-based implants with optimal roughness to regulate cellular behaviors, and to enhance biocompability and osseointegration. Meanwhile, the PEEK/n-HA/CF ternary composite with optimal surface roughness might hold great potential as bioactive biomaterial for bone grafting and tissue engineering applications. PMID:25733834

Detection of mast cell secretion by using surface enhanced Raman scattering

NASA Astrophysics Data System (ADS)

Li, Juan; Li, Ren; Zheng, Liqin; Wang, Yuhua; Xie, Shusen; Lin, Juqiang

2016-10-01

Acupuncture can cause a remarkable increase in degranulation of the mast cells, which has attracted the interest of researchers since the 1980s. Surface-enhanced Raman scattering (SERS) could obtain biochemical information with high sensitivity and specificity. In this study, SERS was used to detect the degree of degranulation of mast cells according to different incubate time. Mast cells was incubated with culture medium for 0 h, 12 h and 24 h, then centrifuge the culture medium, decant the supernatant, and discard the mast cell. SERS was performed to obtain the biochemical fingerprinting signatures of the centrifuged medium. The spectra data are then analyzed by spectral peaks attribution and the principal component analysis (PCA). The measured Raman spectra of the two groups were separated well by PCA. It indicated that mast cells had secreted some substances into cultured medium though degranulation did not happen.

CMTM3 (CKLF-Like Marvel Transmembrane Domain 3) Mediates Angiogenesis by Regulating Cell Surface Availability of VE-Cadherin in Endothelial Adherens Junctions.

PubMed

Chrifi, Ihsan; Louzao-Martinez, Laura; Brandt, Maarten; van Dijk, Christian G M; Burgisser, Petra; Zhu, Changbin; Kros, Johan M; Duncker, Dirk J; Cheng, Caroline

2017-06-01

Decrease in VE-cadherin adherens junctions reduces vascular stability, whereas disruption of adherens junctions is a requirement for neovessel sprouting during angiogenesis. Endocytosis plays a key role in regulating junctional strength by altering bioavailability of cell surface proteins, including VE-cadherin. Identification of new mediators of endothelial endocytosis could enhance our understanding of angiogenesis. Here, we assessed the function of CMTM3 (CKLF-like MARVEL transmembrane domain 3), which we have previously identified as highly expressed in Flk1 + endothelial progenitor cells during embryonic development. Using a 3-dimensional coculture of human umbilical vein endothelial cells-GFP (green fluorescent protein) and pericytes-RFP (red fluorescent protein), we demonstrated that siRNA-mediated CMTM3 silencing in human umbilical vein endothelial cells impairs angiogenesis. In vivo CMTM3 inhibition by morpholino injection in developing zebrafish larvae confirmed that CMTM3 expression is required for vascular sprouting. CMTM3 knockdown in human umbilical vein endothelial cells does not affect proliferation or migration. Intracellular staining demonstrated that CMTM3 colocalizes with early endosome markers EEA1 (early endosome marker 1) and Clathrin + vesicles and with cytosolic VE-cadherin in human umbilical vein endothelial cells. Adenovirus-mediated CMTM3 overexpression enhances endothelial endocytosis, shown by an increase in Clathrin + , EEA1 + , Rab11 + , Rab5 + , and Rab7 + vesicles. CMTM3 overexpression enhances, whereas CMTM3 knockdown decreases internalization of cell surface VE-cadherin in vitro. CMTM3 promotes loss of endothelial barrier function in thrombin-induced responses, shown by transendothelial electric resistance measurements in vitro. In this study, we have identified a new regulatory function for CMTM3 in angiogenesis. CMTM3 is involved in VE-cadherin turnover and is a regulator of the cell surface pool of VE-cadherin. Therefore, CMTM3 mediates cell-cell adhesion at adherens junctions and contributes to the control of vascular sprouting. © 2017 American Heart Association, Inc.

In situ monitoring of biomolecular processes in living systems using surface-enhanced Raman scattering

NASA Astrophysics Data System (ADS)

Altunbek, Mine; Kelestemur, Seda; Culha, Mustafa

2015-12-01

Surface-enhanced Raman scattering (SERS) continues to strive to gather molecular level information from dynamic biological systems. It is our ongoing effort to utilize the technique for understanding of the biomolecular processes in living systems such as eukaryotic and prokaryotic cells. In this study, the technique is investigated to identify cell death mechanisms in 2D and 3D in vitro cell culture models, which is a very important process in tissue engineering and pharmaceutical applications. Second, in situ biofilm formation monitoring is investigated to understand how microorganisms respond to the environmental stimuli, which inferred information can be used to interfere with biofilm formation and fight against their pathogenic activity.

Designing a Binding Interface for Control of Cancer Cell Adhesion via 3D Topography and Metabolic Oligosaccharide Engineering

PubMed Central

Du, Jian; Che, Pao-Lin; Wang, Zhi-Yun; Aich, Udayanath; Yarema, Kevin J.

2011-01-01

This study combines metabolic oligosaccharide engineering (MOE), a technology where the glycocalyx of living cells is endowed with chemical features not normally found in sugars, with custom-designed three dimensional biomaterial substrates to enhance the adhesion of cancer cells and control their morphology and gene expression. Specifically, Ac5ManNTGc, a thiol-bearing analogue of N-acetyl-d-mannosamine (ManNAc) was used to introduce thiolated sialic acids into the glycocalyx of human Jurkat T-lymphoma derived cells. In parallel 2D films and 3D electrospun nanofibrous scaffolds were prepared from polyethersulfone (PES) and (as controls) left unmodified or aminated. Alternately, the materials were malemided or gold-coated to provide bioorthogonal binding partners for the thiol groups newly expressed on the cell surface. Cell attachment was modulated by both the topography of the substrate surface and by the chemical compatibility of the binding interface between the cell and the substrate; a substantial increase in binding for normally non-adhesive Jurkat line for 3D scaffold compared to 2D surfaces with an added degree of adhesion resulting from chemoselective binding to malemidede-derivatived or gold-coated surfaces. In addition, the morphology of the cells attached to the 3D scaffolds via MOE-mediated adhesion was dramatically altered and the expression of genes involved in cell adhesion changed in a time-dependent manner. This study showed that cell adhesion could be enhanced, gene expression modulated, and cell fate controlled by introducing the 3D topograhical cues into the growth substrate and by creating a glycoengineered binding interface where the chemistry of both the cell surface and biomaterials scaffold was controlled to facilitate a new mode of carbohydrate-mediated adhesion. PMID:21549424

SiN{sub x} layers on nanostructured Si solar cells: Effective for optical absorption and carrier collection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Yunae; Kim, Eunah; Gwon, Minji

2015-10-12

We compared nanopatterned Si solar cells with and without SiN{sub x} layers. The SiN{sub x} layer coating significantly improved the internal quantum efficiency of the nanopatterned cells at long wavelengths as well as short wavelengths, whereas the surface passivation helped carrier collection of flat cells mainly at short wavelengths. The surface nanostructured array enhanced the optical absorption and also concentrated incoming light near the surface in broad wavelength range. Resulting high density of the photo-excited carriers near the surface could lead to significant recombination loss and the SiN{sub x} layer played a crucial role in the improved carrier collection ofmore » the nanostructured solar cells.« less

The Otto Aufranc Award: Enhanced Biocompatibility of Stainless Steel Implants by Titanium Coating and Microarc Oxidation

PubMed Central

Lim, Young Wook; Kwon, Soon Yong; Sun, Doo Hoon

2010-01-01

Background Stainless steel is one of the most widely used biomaterials for internal fixation devices, but is not used in cementless arthroplasty implants because a stable oxide layer essential for biocompatibility cannot be formed on the surface. We applied a Ti electron beam coating, to form oxide layer on the stainless steel surface. To form a thicker oxide layer, we used a microarc oxidation process on the surface of Ti coated stainless steel. Modification of the surface using Ti electron beam coating and microarc oxidation could improve the ability of stainless steel implants to osseointegrate. Questions/purposes The ability of cells to adhere to grit-blasted, titanium-coated, microarc-oxidated stainless steel in vitro was compared with that of two different types of surface modifications, machined and titanium-coated, and microarc-oxidated. Methods We performed energy-dispersive x-ray spectroscopy and scanning electron microscopy investigations to assess the chemical composition and structure of the stainless steel surfaces and cell morphology. The biologic responses of an osteoblastlike cell line (SaOS-2) were examined by measuring proliferation (cell proliferation assay), differentiation (alkaline phosphatase activity), and attraction ability (cell migration assay). Results Cell proliferation, alkaline phosphatase activity, migration, and adhesion were increased in the grit-blasted, titanium-coated, microarc-oxidated group compared to the two other groups. Osteoblastlike cells on the grit-blasted, titanium-coated, microarc-oxidated surface were strongly adhered, and proliferated well compared to those on the other surfaces. Conclusions The surface modifications we used (grit blasting, titanium coating, microarc oxidation) enhanced the biocompatibility (proliferation and migration of osteoblastlike cells) of stainless steel. Clinical Relevance This process is not unique to stainless steel; it can be applied to many metals to improve their biocompatibility, thus allowing a broad range of materials to be used for cementless implants. PMID:20936386

Surface modification and endothelialization of biomaterials as potential scaffolds for vascular tissue engineering applications.

PubMed

Ren, Xiangkui; Feng, Yakai; Guo, Jintang; Wang, Haixia; Li, Qian; Yang, Jing; Hao, Xuefang; Lv, Juan; Ma, Nan; Li, Wenzhong

2015-08-07

Surface modification and endothelialization of vascular biomaterials are common approaches that are used to both resist the nonspecific adhesion of proteins and improve the hemocompatibility and long-term patency of artificial vascular grafts. Surface modification of vascular grafts using hydrophilic poly(ethylene glycol), zwitterionic polymers, heparin or other bioactive molecules can efficiently enhance hemocompatibility, and consequently prevent thrombosis on artificial vascular grafts. However, these modified surfaces may be excessively hydrophilic, which limits initial vascular endothelial cell adhesion and formation of a confluent endothelial lining. Therefore, the improvement of endothelialization on these grafts by chemical modification with specific peptides and genes is now arousing more and more interest. Several active peptides, such as RGD, CAG, REDV and YIGSR, can be specifically recognized by endothelial cells. Consequently, graft surfaces that are modified by these peptides can exhibit targeting selectivity for the adhesion of endothelial cells, and genes can be delivered by targeting carriers to specific tissues to enhance the promotion and regeneration of blood vessels. These methods could effectively accelerate selective endothelial cell recruitment and functional endothelialization. In this review, recent developments in the surface modification and endothelialization of biomaterials in vascular tissue engineering are summarized. Both gene engineering and targeting ligand immobilization are promising methods to improve the clinical outcome of artificial vascular grafts.

REEPs Are Membrane Shaping Adapter Proteins That Modulate Specific G Protein-Coupled Receptor Trafficking by Affecting ER Cargo Capacity

PubMed Central

Ho, Vincent K.; Angelotti, Timothy

2013-01-01

Receptor expression enhancing proteins (REEPs) were identified by their ability to enhance cell surface expression of a subset of G protein-coupled receptors (GPCRs), specifically GPCRs that have proven difficult to express in heterologous cell systems. Further analysis revealed that they belong to the Yip (Ypt-interacting protein) family and that some REEP subtypes affect ER structure. Yip family comparisons have established other potential roles for REEPs, including regulation of ER-Golgi transport and processing/neuronal localization of cargo proteins. However, these other potential REEP functions and the mechanism by which they selectively enhance GPCR cell surface expression have not been clarified. By utilizing several REEP family members (REEP1, REEP2, and REEP6) and model GPCRs (α2A and α2C adrenergic receptors), we examined REEP regulation of GPCR plasma membrane expression, intracellular processing, and trafficking. Using a combination of immunolocalization and biochemical methods, we demonstrated that this REEP subset is localized primarily to ER, but not plasma membranes. Single cell analysis demonstrated that these REEPs do not specifically enhance surface expression of all GPCRs, but affect ER cargo capacity of specific GPCRs and thus their surface expression. REEP co-expression with α2 adrenergic receptors (ARs) revealed that this REEP subset interacts with and alter glycosidic processing of α2C, but not α2A ARs, demonstrating selective interaction with cargo proteins. Specifically, these REEPs enhanced expression of and interacted with minimally/non-glycosylated forms of α2C ARs. Most importantly, expression of a mutant REEP1 allele (hereditary spastic paraplegia SPG31) lacking the carboxyl terminus led to loss of this interaction. Thus specific REEP isoforms have additional intracellular functions besides altering ER structure, such as enhancing ER cargo capacity, regulating ER-Golgi processing, and interacting with select cargo proteins. Therefore, some REEPs can be further described as ER membrane shaping adapter proteins. PMID:24098485

A feasibility study for in vitro evaluation of fixation between prosthesis and bone with bone marrow-derived mesenchymal stem cells.

PubMed

Morita, Yusuke; Yamasaki, Kenichi; Hattori, Koji

2010-10-01

It is difficult to quantitatively evaluate adhesive strength between an implant and the neighboring bone using animal experiments, because the degree of fixation of an implant depends on differences between individuals and the clearance between the material and the bone resulting from surgical technique. A system was designed in which rat bone marrow cells were used to quantitatively evaluate the adhesion between titanium alloy plates and bone plates in vitro. Three kinds of surface treatment were used: a sand-blasted surface, a titanium-sprayed surface and a titanium-sprayed surface coated with hydroxyapatite. Bone marrow cells obtained from rat femora were seeded on the titanium alloy plates, and the cells were cultured between the titanium alloy plates and the bone plates sliced from porcine ilium for 2 weeks. After cultivation, adhesive strength was measured using a tensile test, after which DNA amount and Alkaline phosphatase activity were measured. The seeded cells accelerated adhesion of the titanium alloy plate to the bone plate. Adhesive strength of the titanium-sprayed surface was lower than that of the sand-blasted surface because of lower initial contact area, although there was no difference in Alkaline phosphatase activity between two surface treatments. A hydroxyapatite coating enhanced adhesive strength between the titanium alloy palate and the bone plate, as well as enhancing osteogenic differentiation of bone marrow cells. It is believed that this novel experimental method can be used to simultaneously evaluate the osteogenic differentiation and the adhesive strength of an implant during in vitro cultivation. 2010 Elsevier Ltd. All rights reserved.

Treatment of Silk Fibroin with Poly(ethylene glycol) for the Enhancement of Corneal Epithelial Cell Growth

PubMed Central

Suzuki, Shuko; Dawson, Rebecca A.; Chirila, Traian V.; Shadforth, Audra M. A.; Hogerheyde, Thomas A.; Edwards, Grant A.; Harkin, Damien G.

2015-01-01

A silk protein, fibroin, was isolated from the cocoons of the domesticated silkworm (Bombyx mori) and cast into membranes to serve as freestanding templates for tissue-engineered corneal cell constructs to be used in ocular surface reconstruction. In this study, we sought to enhance the attachment and proliferation of corneal epithelial cells by increasing the permeability of the fibroin membranes and the topographic roughness of their surface. By mixing the fibroin solution with poly(ethylene glycol) (PEG) of molecular weight 300 Da, membranes were produced with increased permeability and with topographic patterns generated on their surface. In order to enhance their mechanical stability, some PEG-treated membranes were also crosslinked with genipin. The resulting membranes were thoroughly characterized and compared to the non-treated membranes. The PEG-treated membranes were similar in tensile strength to the non-treated ones, but their elastic modulus was higher and elongation lower, indicating enhanced rigidity. The crosslinking with genipin did not induce a significant improvement in mechanical properties. In cultures of a human-derived corneal epithelial cell line (HCE-T), the PEG treatment of the substratum did not improve the attachment of cells and it enhanced only slightly the cell proliferation in the longer term. Likewise, primary cultures of human limbal epithelial cells grew equally well on both non-treated and PEG-treated membranes, and the stratification of cultures was consistently improved in the presence of an underlying culture of irradiated 3T3 feeder cells, irrespectively of PEG-treatment. Nevertheless, the cultures grown on the PEG-treated membranes in the presence of feeder cells did display a higher nuclear-to-cytoplasmic ratio suggesting a more proliferative phenotype. We concluded that while the treatment with PEG had a significant effect on some structural properties of the B. mori silk fibroin (BMSF) membranes, there were minimal gains in the performance of these materials as a substratum for corneal epithelial cell growth. The reduced mechanical stability of freestanding PEG-treated membranes makes them a less viable choice than the non-treated membranes. PMID:26034883

Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells.

PubMed

Vermang, Bart; Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika; Kotipalli, Ratan; Henry, Frederic; Flandre, Denis

2014-10-01

Reducing absorber layer thickness below 500 nm in regular Cu(In,Ga)Se 2 (CIGS) solar cells decreases cell efficiency considerably, as both short-circuit current and open-circuit voltage are reduced because of incomplete absorption and high Mo/CIGS rear interface recombination. In this work, an innovative rear cell design is developed to avoid both effects: a highly reflective rear surface passivation layer with nano-sized local point contact openings is employed to enhance rear internal reflection and decrease the rear surface recombination velocity significantly, as compared with a standard Mo/CIGS rear interface. The formation of nano-sphere shaped precipitates in chemical bath deposition of CdS is used to generate nano-sized point contact openings. Evaporation of MgF 2 coated with a thin atomic layer deposited Al 2 O 3 layer, or direct current magnetron sputtering of Al 2 O 3 are used as rear surface passivation layers. Rear internal reflection is enhanced substantially by the increased thickness of the passivation layer, and also the rear surface recombination velocity is reduced at the Al 2 O 3 /CIGS rear interface. (MgF 2 /)Al 2 O 3 rear surface passivated ultra-thin CIGS solar cells are fabricated, showing an increase in short circuit current and open circuit voltage compared to unpassivated reference cells with equivalent CIGS thickness. Accordingly, average solar cell efficiencies of 13.5% are realized for 385 nm thick CIGS absorber layers, compared with 9.1% efficiency for the corresponding unpassivated reference cells.

Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells

PubMed Central

Vermang, Bart; Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika; Kotipalli, Ratan; Henry, Frederic; Flandre, Denis

2014-01-01

Reducing absorber layer thickness below 500 nm in regular Cu(In,Ga)Se2 (CIGS) solar cells decreases cell efficiency considerably, as both short-circuit current and open-circuit voltage are reduced because of incomplete absorption and high Mo/CIGS rear interface recombination. In this work, an innovative rear cell design is developed to avoid both effects: a highly reflective rear surface passivation layer with nano-sized local point contact openings is employed to enhance rear internal reflection and decrease the rear surface recombination velocity significantly, as compared with a standard Mo/CIGS rear interface. The formation of nano-sphere shaped precipitates in chemical bath deposition of CdS is used to generate nano-sized point contact openings. Evaporation of MgF2 coated with a thin atomic layer deposited Al2O3 layer, or direct current magnetron sputtering of Al2O3 are used as rear surface passivation layers. Rear internal reflection is enhanced substantially by the increased thickness of the passivation layer, and also the rear surface recombination velocity is reduced at the Al2O3/CIGS rear interface. (MgF2/)Al2O3 rear surface passivated ultra-thin CIGS solar cells are fabricated, showing an increase in short circuit current and open circuit voltage compared to unpassivated reference cells with equivalent CIGS thickness. Accordingly, average solar cell efficiencies of 13.5% are realized for 385 nm thick CIGS absorber layers, compared with 9.1% efficiency for the corresponding unpassivated reference cells. PMID:26300619

Efficiency enhancement of silicon nanowire solar cells by using UV/Ozone treatments and micro-grid electrodes

NASA Astrophysics Data System (ADS)

Chen, Junyi; Subramani, Thiyagu; Sun, Yonglie; Jevasuwan, Wipakorn; Fukata, Naoki

2018-05-01

Silicon nanowire solar cells were fabricated by metal catalyzed electroless etching (MCEE) followed by thermal chemical vapor deposition (CVD). In this study, we investigated two effects, a UV/ozone treatment and the use of a micro-grid electrodes, to enhance light absorption and reduce the optic losses in the solar cell device. The UV/ozone treatment successfully improved the conversion efficiency. The micro-grid electrodes were then applied in solar cell devices subjected to a back surface field (BSF) treatment and rapid thermal annealing (RTA). These effects improved the conversion efficiency from 9.4% to 10.9%. Moreover, to reduce surface recombination and improve the continuity of front electrodes, we optimized the etching time of the MCEE process, giving a high efficiency of 12.3%.

Self-Assembled ZnO Nanosheet-Based Spherical Structure as Photoanode in Dye-Sensitized Solar Cells

NASA Astrophysics Data System (ADS)

Ameri, Mohsen; Raoufi, Meysam; Zamani-Meymian, M.-R.; Samavat, Feridoun; Fathollahi, M.-R.; Mohajerani, Ezeddin

2018-03-01

High surface area and enhanced light scattering of ZnO nanosheet aggregates have made them a promising active layer candidate material for fabrication of nanostructure dye-sensitized solar cells. Here, we propose a facile preparation method of such ZnO nanosheet structures, and in order to verify their applicability as photoanode material for dye-sensitized solar cells, we employ morphological, optical, structural and electrical measurements. The results reveal the high surface area available for dye molecules for enhancing adsorption, high light scattering and competitive power conversion efficiencies compared to the works in literature. Finally, the device is optimized with respect to the photoanode thickness. The favorable features shown here can extend the application of the structure to other types of sensitization-based perovskite and quantum dot solar cells.

Target-specific cellular uptake of PLGA nanoparticles coated with poly(L-lysine)-poly(ethylene glycol)-folate conjugate.

PubMed

Kim, Sun Hwa; Jeong, Ji Hoon; Chun, Ki Woo; Park, Tae Gwan

2005-09-13

Poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles with anionic surface charge were surface coated with cationic di-block copolymer, poly(L-lysine)-poly(ethylene glycol)-folate (PLL-PEG-FOL) conjugate, for enhancing their site-specific intracellular delivery against folate receptor overexpressing cancer cells. The PLGA nanoparticles coated with the conjugate were characterized in terms of size, surface charge, and change in surface composition by XPS. By employing the flow cytometry method and confocal image analysis, the extent of cellular uptake was comparatively evaluated under various conditions. PLL-PEG-FOL coated PLGA nanoparticles demonstrated far greater extent of cellular uptake to KB cells, suggesting that they were mainly taken up by folate receptor-mediated endocytosis. The enhanced cellular uptake was also observed even in the presence of serum proteins, possibly due to the densely seeded PEG chains. The PLL-PEG-FOL coated PLGA nanoparticles could be potentially applied for cancer cell targeted delivery of various therapeutic agents.

Experimental study on rat NK cell activity improvement by laser acupoint irradiation

NASA Astrophysics Data System (ADS)

Yang, Dongxiao; Chen, Xiufeng; Ruan, Buqing; Yang, Feng

1998-08-01

To study the improvement of the natural killer (NK) cell activity by semiconductor laser acupoint irradiation, rats were used in this experiment and were injected immunosuppressant in their abdomen. The immunoassay was made after the surface irradiation and inner irradiation at Baihui point by semiconductor laser. The NK cell activity is an important index of immunologic function. The results showed that the NK cell activity after laser acupoint irradiation was enhanced. This enhancement is relatively important in the clinical therapy of tumor.

Self-assembled monolayers of alendronate on Ti6Al4V alloy surfaces enhance osteogenesis in mesenchymal stem cells

NASA Astrophysics Data System (ADS)

Rojo, Luis; Gharibi, Borzo; McLister, Robert; Meenan, Brian J.; Deb, Sanjukta

2016-07-01

Phosphonates have emerged as an alternative for functionalization of titanium surfaces by the formation of homogeneous self-assembled monolayers (SAMs) via Ti-O-P linkages. This study presents results from an investigation of the modification of Ti6Al4V alloy by chemisorption of osseoinductive alendronate using a simple, effective and clean methodology. The modified surfaces showed a tailored topography and surface chemistry as determined by SEM microscopy and RAMAN spectroscopy. X-ray photoelectron spectroscopy revealed that an effective mode of bonding is created between the metal oxide surface and the phosphate residue of alendronate, leading to formation of homogenous drug distribution along the surface. In-vitro studies showed that alendronate SAMs induce differentiation of hMSC to a bone cell phenotype and promote bone formation on modified surfaces. Here we show that this novel method for the preparation of functional coatings on titanium-based medical devices provides osseoinductive bioactive molecules to promote enhanced integration at the site of implantation.

Self-assembled monolayers of alendronate on Ti6Al4V alloy surfaces enhance osteogenesis in mesenchymal stem cells

PubMed Central

Rojo, Luis; Gharibi, Borzo; McLister, Robert; Meenan, Brian J.; Deb, Sanjukta

2016-01-01

Phosphonates have emerged as an alternative for functionalization of titanium surfaces by the formation of homogeneous self-assembled monolayers (SAMs) via Ti-O-P linkages. This study presents results from an investigation of the modification of Ti6Al4V alloy by chemisorption of osseoinductive alendronate using a simple, effective and clean methodology. The modified surfaces showed a tailored topography and surface chemistry as determined by SEM microscopy and RAMAN spectroscopy. X-ray photoelectron spectroscopy revealed that an effective mode of bonding is created between the metal oxide surface and the phosphate residue of alendronate, leading to formation of homogenous drug distribution along the surface. In-vitro studies showed that alendronate SAMs induce differentiation of hMSC to a bone cell phenotype and promote bone formation on modified surfaces. Here we show that this novel method for the preparation of functional coatings on titanium-based medical devices provides osseoinductive bioactive molecules to promote enhanced integration at the site of implantation. PMID:27468811

Mining for osteogenic surface topographies: In silico design to in vivo osseo-integration.

PubMed

Hulshof, Frits F B; Papenburg, Bernke; Vasilevich, Aliaksei; Hulsman, Marc; Zhao, Yiping; Levers, Marloes; Fekete, Natalie; de Boer, Meint; Yuan, Huipin; Singh, Shantanu; Beijer, Nick; Bray, Mark-Anthony; Logan, David J; Reinders, Marcel; Carpenter, Anne E; van Blitterswijk, Clemens; Stamatialis, Dimitrios; de Boer, Jan

2017-08-01

Stem cells respond to the physicochemical parameters of the substrate on which they grow. Quantitative material activity relationships - the relationships between substrate parameters and the phenotypes they induce - have so far poorly predicted the success of bioactive implant surfaces. In this report, we screened a library of randomly selected designed surface topographies for those inducing osteogenic differentiation of bone marrow-derived mesenchymal stem cells. Cell shape features, surface design parameters, and osteogenic marker expression were strongly correlated in vitro. Furthermore, the surfaces with the highest osteogenic potential in vitro also demonstrated their osteogenic effect in vivo: these indeed strongly enhanced bone bonding in a rabbit femur model. Our work shows that by giving stem cells specific physicochemical parameters through designed surface topographies, differentiation of these cells can be dictated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fabrication of Biocompatible Potassium Sodium Niobate Piezoelectric Ceramic as an Electroactive Implant

PubMed Central

Chen, Wei; Yu, Zunxiong; Pang, Jinshan; Yu, Peng; Tan, Guoxin; Ning, Chengyun

2017-01-01

The discovery of piezoelectricity in natural bone has attracted extensive research in emulating biological electricity for various tissue regeneration. Here, we carried out experiments to build biocompatible potassium sodium niobate (KNN) ceramics. Then, influence substrate surface charges on bovine serum albumin (BSA) protein adsorption and cell proliferation on KNN ceramics surfaces was investigated. KNN ceramics with piezoelectric constant of ~93 pC/N and relative density of ~93% were fabricated. The adsorption of protein on the positive surfaces (Ps) and negative surfaces (Ns) of KNN ceramics with piezoelectric constant of ~93 pC/N showed greater protein adsorption capacity than that on non-polarized surfaces (NPs). Biocompatibility of KNN ceramics was verified through cell culturing and live/dead cell staining of MC3T3. The cells experiment showed enhanced cell growth on the positive surfaces (Ps) and negative surfaces (Ns) compared to non-polarized surfaces (NPs). These results revealed that KNN ceramics had great potential to be used to understand the effect of surface potential on cells processes and would benefit future research in designing piezoelectric materials for tissue regeneration. PMID:28772704

Fabrication of Biocompatible Potassium Sodium Niobate Piezoelectric Ceramic as an Electroactive Implant.

PubMed

Chen, Wei; Yu, Zunxiong; Pang, Jinshan; Yu, Peng; Tan, Guoxin; Ning, Chengyun

2017-03-26

The discovery of piezoelectricity in natural bone has attracted extensive research in emulating biological electricity for various tissue regeneration. Here, we carried out experiments to build biocompatible potassium sodium niobate (KNN) ceramics. Then, influence substrate surface charges on bovine serum albumin (BSA) protein adsorption and cell proliferation on KNN ceramics surfaces was investigated. KNN ceramics with piezoelectric constant of ~93 pC/N and relative density of ~93% were fabricated. The adsorption of protein on the positive surfaces (Ps) and negative surfaces (Ns) of KNN ceramics with piezoelectric constant of ~93 pC/N showed greater protein adsorption capacity than that on non-polarized surfaces (NPs). Biocompatibility of KNN ceramics was verified through cell culturing and live/dead cell staining of MC3T3. The cells experiment showed enhanced cell growth on the positive surfaces (Ps) and negative surfaces (Ns) compared to non-polarized surfaces (NPs). These results revealed that KNN ceramics had great potential to be used to understand the effect of surface potential on cells processes and would benefit future research in designing piezoelectric materials for tissue regeneration.

[Cordyceps sinensis enhances lymphocyte proliferation and CD markers expression in simulated microgravity environment].

PubMed

Hao, Tong; Li, Jun-Jie; Du, Zhi-Yan; Duan, Cui-Mi; Wang, Yan-Meng; Wang, Chang-Yong; Song, Jing-Ping; Wang, Lin-Jie; Li, Ying-Hui; Wang, Yan

2012-10-01

This study was aimed to explore the effect of cordyceps sinensis enhancing lymphocyte proliferation and surface CD marker expression in simulated microgravity environment. The splenic lymphocytes were separated from mice and cultured in the rotary cell culture system simulated microgravity environment. The cells were treated with different concentration of cordyceps sinensis solution (0, 6.25, 12.5, 25 and 50 µg/ml) for 24, 48 and 72 h respectively, then the cells were harvested, and analyzed for cell proliferation and the expression of cell surface markers (CD4 and CD8). The results showed that under simulated microgravity environment, the lymphocyte proliferation was inhibited. When the concentration of cordyceps sinensis was 25 or 50 µg/ml, the lymphocyte proliferation, CD4 and CD8 expressions all increased, but 50 µg/ml cordyceps sinensis could inhibit the proliferation ability with the time prolonging. It is concluded that the suitable concentration of cordyceps sinensis displayed the ability to enhance the lymphocyte proliferation and CD marker expression in simulated microgravity environment. These results may be valuable for screening drugs which can be potentially against immunosuppression under simulated microgravity.

Biomimetic coatings enhance tribocorrosion behavior and cell responses of commercially pure titanium surfaces

PubMed Central

Marques, Isabella da Silva Vieira; Alfaro, Maria Fernanda; Saito, Miki Taketomi; da Cruz, Nilson Cristino; Takoudis, Christos; Landers, Richard; Mesquita, Marcelo Ferraz; Nociti Junior, Francisco Humberto; Mathew, Mathew T.; Sukotjo, Cortino; Barão, Valentim Adelino Ricardo

2016-01-01

Biofunctionalized surfaces for implants are currently receiving much attention in the health care sector. Our aims were (1) to create bioactive Ti-coatings doped with Ca, P, Si, and Ag produced by microarc oxidation (MAO) to improve the surface properties of biomedical implants, (2) to investigate the TiO2 layer stability under wear and corrosion, and (3) to evaluate human mesenchymal stem cells (hMSCs) responses cultured on the modified surfaces. Tribocorrosion and cell experiments were performed following the MAO treatment. Samples were divided as a function of different Ca/P concentrations and treatment duration. Higher Ca concentration produced larger porous and harder coatings compared to the untreated group (p < 0.001), due to the presence of rutile structure. Free potentials experiments showed lower drops (−0.6 V) and higher coating lifetime during sliding for higher Ca concentration, whereas lower concentrations presented similar drops (−0.8 V) compared to an untreated group wherein the drop occurred immediately after the sliding started. MAO-treated surfaces improved the matrix formation and osteogenic gene expression levels of hMSCs. Higher Ca/P ratios and the addition of Ag nanoparticles into the oxide layer presented better surface properties, tribocorrosive behavior, and cell responses. MAO is a promising technique to enhance the biological, chemical, and mechanical properties of dental implant surfaces. PMID:27514370

Biomimetic coatings enhance tribocorrosion behavior and cell responses of commercially pure titanium surfaces.

PubMed

Marques, Isabella da Silva Vieira; Alfaro, Maria Fernanda; Saito, Miki Taketomi; da Cruz, Nilson Cristino; Takoudis, Christos; Landers, Richard; Mesquita, Marcelo Ferraz; Nociti Junior, Francisco Humberto; Mathew, Mathew T; Sukotjo, Cortino; Barão, Valentim Adelino Ricardo

2016-09-11

Biofunctionalized surfaces for implants are currently receiving much attention in the health care sector. Our aims were (1) to create bioactive Ti-coatings doped with Ca, P, Si, and Ag produced by microarc oxidation (MAO) to improve the surface properties of biomedical implants, (2) to investigate the TiO2 layer stability under wear and corrosion, and (3) to evaluate human mesenchymal stem cells (hMSCs) responses cultured on the modified surfaces. Tribocorrosion and cell experiments were performed following the MAO treatment. Samples were divided as a function of different Ca/P concentrations and treatment duration. Higher Ca concentration produced larger porous and harder coatings compared to the untreated group (p < 0.001), due to the presence of rutile structure. Free potentials experiments showed lower drops (-0.6 V) and higher coating lifetime during sliding for higher Ca concentration, whereas lower concentrations presented similar drops (-0.8 V) compared to an untreated group wherein the drop occurred immediately after the sliding started. MAO-treated surfaces improved the matrix formation and osteogenic gene expression levels of hMSCs. Higher Ca/P ratios and the addition of Ag nanoparticles into the oxide layer presented better surface properties, tribocorrosive behavior, and cell responses. MAO is a promising technique to enhance the biological, chemical, and mechanical properties of dental implant surfaces.

Electric-field enhanced performance in catalysis and solid-state devices involving gases

DOEpatents

Blackburn, Bryan M.; Wachsman, Eric D.; Van Assche, IV, Frederick Martin

2015-05-19

Electrode configurations for electric-field enhanced performance in catalysis and solid-state devices involving gases are provided. According to an embodiment, electric-field electrodes can be incorporated in devices such as gas sensors and fuel cells to shape an electric field provided with respect to sensing electrodes for the gas sensors and surfaces of the fuel cells. The shaped electric fields can alter surface dynamics, system thermodynamics, reaction kinetics, and adsorption/desorption processes. In one embodiment, ring-shaped electric-field electrodes can be provided around sensing electrodes of a planar gas sensor.

UV-killed Staphylococcus aureus enhances adhesion and differentiation of osteoblasts on bone-associated biomaterials.

PubMed

Somayaji, Shankari N; Huet, Yvette M; Gruber, Helen E; Hudson, Michael C

2010-11-01

Titanium alloys (Ti) are the preferred material for orthopedic applications. However, very often, these metallic implants loosen over a long period and mandate revision surgery. For implant success, osteoblasts must adhere to the implant surface and deposit a mineralized extracellular matrix (ECM). Here, we utilized UV-killed Staphylococcus aureus as a novel osteoconductive coating for Ti surfaces. S. aureus expresses surface adhesins capable of binding to bone and biomaterials directly. Furthermore, interaction of S. aureus with osteoblasts activates growth factor-related pathways that potentiate osteogenesis. Although UV-killed S. aureus cells retain their bone-adhesive ability, they do not stimulate significant immune modulator expression. All of the abovementioned properties were utilized for a novel implant coating so as to promote osteoblast recruitment and subsequent cell functions on the bone-implant interface. In this study, osteoblast adhesion, proliferation, and mineralized ECM synthesis were measured on Ti surfaces coated with fibronectin with and without UV-killed bacteria. Osteoblast adhesion was enhanced on Ti alloy surfaces coated with bacteria compared to uncoated surfaces, while cell proliferation was sustained comparably on both surfaces. Osteoblast markers such as collagen, osteocalcin, alkaline phosphatase activity, and mineralized nodule formation were increased on Ti alloy coated with bacteria compared to uncoated surfaces.

PEG attachment to osteoblasts enhances mechanosensitivity.

PubMed

Hamamura, Kazunori; Weng, Yiming; Zhao, Jun; Yokota, Hiroki; Xie, Dong

2008-06-01

Fluid flow induces proliferation and differentiation of osteoblasts, and fibrous structure like a primary cilium on a cell surface contributes to flow sensing and flow-driven gene regulation. We address a question: Does attachment of synthetic polymers on a cell surface enhance mechanosensitivity of osteoblasts? Using MC3T3 osteoblast cells (C4 clone) and a PEG polymer, one of whose termini was covalently linked to a succinimidyl succinate group (functionalized PEG-PEGSS), we examined attachment of PEGSS to osteoblasts and evaluated its effects on the mRNA expression of stress-responsive genes. AFM images exhibited globular PEGSS conformation of approximately 100 nm in size, and SEM images confirmed the attachment of a cluster of pancake-like PEGSS molecules on the osteoblast surface. Compared to control cells incubated with unfunctionalized PEG, real-time PCR revealed that RNA upregulation of c-fos, egr1, ATF3 and Cox2 genes was magnified in the cells incubated with PEGSS. These results support a PEG-induced increase in mechanosensitivity of osteoblasts and indicate that the described approach would be useful to accelerate growth and development of osteoblasts for bone repair and tissue engineering.

Surface Modifications of Dental Ceramic Implants with Different Glass Solder Matrices: In Vitro Analyses with Human Primary Osteoblasts and Epithelial Cells

PubMed Central

Mick, Enrico

2014-01-01

Ceramic materials show excellent esthetic behavior, along with an absence of hypersensitivity, making them a possible alternative implant material in dental surgery. However, their surface properties enable only limited osseointegration compared to titanium implants. Within this study, a novel surface coating technique for enhanced osseointegration was investigated biologically and mechanically. Specimens of tetragonal zirconia polycrystal (TZP) and aluminum toughened zirconia (ATZ) were modified with glass solder matrices in two configurations which mainly consisted of SiO2, Al2O3, K2O, and Na2O. The influence on human osteoblastic and epithelial cell viability was examined by means of a WST-1 assay as well as live/dead staining. A C1CP-ELISA was carried out to verify procollagen type I production. Uncoated/sandblasted ceramic specimens and sandblasted titanium surfaces were investigated as a reference. Furthermore, mechanical investigations of bilaterally coated pellets were conducted with respect to surface roughness and adhesive strength of the different coatings. These tests could demonstrate a mechanically stable implant coating with glass solder matrices. The coated ceramic specimens show enhanced osteoblastic and partly epithelial viability and matrix production compared to the titanium control. Hence, the new glass solder matrix coating could improve bone cell growth as a prerequisite for enhanced osseointegration of ceramic implants. PMID:25295270

Surface modifications of dental ceramic implants with different glass solder matrices: in vitro analyses with human primary osteoblasts and epithelial cells.

PubMed

Markhoff, Jana; Mick, Enrico; Mitrovic, Aurica; Pasold, Juliane; Wegner, Katharina; Bader, Rainer

2014-01-01

Ceramic materials show excellent esthetic behavior, along with an absence of hypersensitivity, making them a possible alternative implant material in dental surgery. However, their surface properties enable only limited osseointegration compared to titanium implants. Within this study, a novel surface coating technique for enhanced osseointegration was investigated biologically and mechanically. Specimens of tetragonal zirconia polycrystal (TZP) and aluminum toughened zirconia (ATZ) were modified with glass solder matrices in two configurations which mainly consisted of SiO2, Al2O3, K2O, and Na2O. The influence on human osteoblastic and epithelial cell viability was examined by means of a WST-1 assay as well as live/dead staining. A C1CP-ELISA was carried out to verify procollagen type I production. Uncoated/sandblasted ceramic specimens and sandblasted titanium surfaces were investigated as a reference. Furthermore, mechanical investigations of bilaterally coated pellets were conducted with respect to surface roughness and adhesive strength of the different coatings. These tests could demonstrate a mechanically stable implant coating with glass solder matrices. The coated ceramic specimens show enhanced osteoblastic and partly epithelial viability and matrix production compared to the titanium control. Hence, the new glass solder matrix coating could improve bone cell growth as a prerequisite for enhanced osseointegration of ceramic implants.

Epithelial Microvilli Establish an Electrostatic Barrier to Microbial Adhesion

PubMed Central

Bennett, Kaila M.; Walker, Sharon L.

2014-01-01

Microvilli are membrane extensions on the apical surface of polarized epithelia, such as intestinal enterocytes and tubule and duct epithelia. One notable exception in mucosal epithelia is M cells, which are specialized for capturing luminal microbial particles; M cells display a unique apical membrane lacking microvilli. Based on studies of M cell uptake under different ionic conditions, we hypothesized that microvilli may augment the mucosal barrier by providing an increased surface charge density from the increased membrane surface and associated glycoproteins. Thus, electrostatic charges may repel microbes from epithelial cells bearing microvilli, while M cells are more susceptible to microbial adhesion. To test the role of microvilli in bacterial adhesion and uptake, we developed polarized intestinal epithelial cells with reduced microvilli (“microvillus-minus,” or MVM) but retaining normal tight junctions. When tested for interactions with microbial particles in suspension, MVM cells showed greatly enhanced adhesion and uptake of particles compared to microvillus-positive cells. This preference showed a linear relationship to bacterial surface charge, suggesting that microvilli resist binding of microbes by using electrostatic repulsion. Moreover, this predicts that pathogen modification of electrostatic forces may contribute directly to virulence. Accordingly, the effacement effector protein Tir from enterohemorrhagic Escherichia coli O157:H7 expressed in epithelial cells induced a loss of microvilli with consequent enhanced microbial binding. These results provide a new context for microvillus function in the host-pathogen relationship, based on electrostatic interactions. PMID:24778113

Tuning the surface microstructure of titanate coatings on titanium implants for enhancing bioactivity of implants

PubMed Central

Wang, Hui; Lai, Yue-Kun; Zheng, Ru-Yue; Bian, Ye; Zhang, Ke-Qin; Lin, Chang-Jian

2015-01-01

Biological performance of artificial implant materials is closely related to their surface characteristics, such as microtopography, and composition. Therefore, convenient fabrication of artificial implant materials with a cell-friendly surface structure and suitable composition was of great significance for current tissue engineering. In this work, titanate materials with a nanotubular structure were successfully fabricated through a simple chemical treatment. Immersion test in a simulated body fluid and in vitro cell culture were used to evaluate the biological performance of the treated samples. The results demonstrate that the titanate layer with a nanotubular structure on Ti substrates can promote the apatite-inducing ability remarkably and greatly enhance cellular responses. This highlights the potential of such titanate biomaterials with the special nanoscale structure and effective surface composition for biomedical applications such as bone implants. PMID:26089665

Hybrid silicon honeycomb/organic solar cells with enhanced efficiency using surface etching.

PubMed

Liu, Ruiyuan; Sun, Teng; Liu, Jiawei; Wu, Shan; Sun, Baoquan

2016-06-24

Silicon (Si) nanostructure-based photovoltaic devices are attractive for their excellent optical and electrical performance, but show lower efficiency than their planar counterparts due to the increased surface recombination associated with the high surface area and roughness. Here, we demonstrate an efficiency enhancement for hybrid nanostructured Si/polymer solar cells based on a novel Si honeycomb (SiHC) structure using a simple etching method. SiHC structures are fabricated using a combination of nanosphere lithography and plasma treatment followed by a wet chemical post-etching. SiHC has shown superior light-trapping ability in comparison with the other Si nanostructures, along with a robust structure. Anisotropic tetramethylammonium hydroxide etching not only tunes the final surface morphologies of the nanostructures, but also reduces the surface roughness leading to a lower recombination rate in the hybrid solar cells. The suppressed recombination loss, benefiting from the reduced surface-to-volume ratio and roughness, has resulted in a high open-circuit voltage of 600 mV, a short-circuit current of 31.46 mA cm(-2) due to the light-trapping ability of the SiHCs, and yields a power conversion efficiency of 12.79% without any other device structure optimization.

Effect of l-lysine-assisted surface grafting for nano-hydroxyapatite on mechanical properties and in vitro bioactivity of poly(lactic acid-co-glycolic acid).

PubMed

Liuyun, Jiang; Lixin, Jiang; Chengdong, Xiong; Lijuan, Xu; Ye, Li

2016-01-01

It is promising and challenging to study surface modification for nano-hydroxyapatite to improve the dispersion and enhance the mechanical properties and bioactivity of poly(lactic acid-co-glycolic acid). In this paper, we designed an effective new surface grafting with the assist of l-lysine for nano-hydroxyapatite, and the nano-hydroxyapatite surface grafted with the assist of l-lysine (g-nano-hydroxyapatite) was incorporated into poly(lactic acid-co-glycolic acid) to develop a series of g-nano-hydroxyapatite/poly(lactic acid-co-glycolic acid) nano-composites. The surface modification reaction for nano-hydroxyapatite, the mechanical properties, and in vitro human osteoblast-like cell (MG-63) response were characterized and investigated by Fourier transformation infrared, thermal gravimetric analysis, dispersion test, electromechanical universal tester, differential scanning calorimeter measurements, and in vitro cells culture experiment. The results showed that the grafting amount on the surface of nano-hydroxyapatite was enhanced with the increase of l-lysine, and the dispersion of nano-hydroxyapatite was improved more, so that it brought about better promotion crystallization and more excellent mechanical enhancement effect for poly(lactic acid-co-glycolic acid), comparing with the unmodified nano-hydroxyapatite. Moreover, the cells' attachment and proliferation results confirmed that the incorporation of the g-nano-hydroxyapatite into poly(lactic acid-co-glycolic acid) exhibited better biocompatibility than poly(lactic acid-co-glycolic acid). The above results indicated that the new surface grafting with the assist of l-lysine for nano-hydroxyapatite was an ideal novel surface modification method, which brought about better mechanical enhancement effect and in vitro bioactivity for poly(lactic acid-co-glycolic acid) with adding higher g-nano-hydroxyapatite content, suggesting it had a great potential to be used as bone fracture internal fixation materials in future. © The Author(s) 2015.

Surface Modification of Biodegradable Polymers towards Better Biocompatibility and Lower Thrombogenicity

PubMed Central

Rudolph, Andreas; Teske, Michael; Illner, Sabine; Kiefel, Volker; Sternberg, Katrin; Grabow, Niels; Wree, Andreas; Hovakimyan, Marina

2015-01-01

Purpose Drug-eluting stents (DES) based on permanent polymeric coating matrices have been introduced to overcome the in stent restenosis associated with bare metal stents (BMS). A further step was the development of DES with biodegradable polymeric coatings to address the risk of thrombosis associated with first-generation DES. In this study we evaluate the biocompatibility of biodegradable polymer materials for their potential use as coating matrices for DES or as materials for fully bioabsorbable vascular stents. Materials and Methods Five different polymers, poly(L-lactide) PLLA, poly(D,L-lactide) PDLLA, poly(L-lactide-co-glycolide) P(LLA-co-GA), poly(D,L-lactide-co-glycolide) P(DLLA-co-GA) and poly(L-lactide-co-ε-caprolactone), P(LLA-co-CL) were examined in vitro without and with surface modification. The surface modification of polymers was performed by means of wet-chemical (NaOH and ethylenediamine (EDA)) and plasma-chemical (O2 and NH3) processes. The biocompatibility studies were performed on three different cell types: immortalized mouse fibroblasts (cell line L929), human coronary artery endothelial cells (HCAEC) and human umbilical vein endothelial cells (HUVEC). The biocompatibility was examined quantitatively using in vitro cytotoxicity assay. Cells were investigated immunocytochemically for expression of specific markers, and morphology was visualized using confocal laser scanning (CLSM) and scanning electron (SEM) microscopy. Additionally, polymer surfaces were examined for their thrombogenicity using an established hemocompatibility test. Results Both endothelial cell types exhibited poor viability and adhesion on all five unmodified polymer surfaces. The biocompatibility of the polymers could be influenced positively by surface modifications. In particular, a reproducible effect was observed for NH3-plasma treatment, which enhanced the cell viability, adhesion and morphology on all five polymeric surfaces. Conclusion Surface modification of polymers can provide a useful approach to enhance their biocompatibility. For clinical application, attempts should be made to stabilize the plasma modification and use it for coupling of biomolecules to accelerate the re-endothelialization of stent surfaces in vivo. PMID:26641662

Endothelial cell behaviour on gas-plasma-treated PLA surfaces: the roles of surface chemistry and roughness.

PubMed

Shah, Amita; Shah, Sarita; Mani, Gopinath; Wenke, Joseph; Agrawal, Mauli

2011-04-01

Glow-discharge gas-plasma (GP) treatment has been shown to induce surface modifications such that cell adhesion and growth are enhanced. However, it is not known which gas used in GP treatment is optimal for endothelial cell function. Polylactic acid (PLA) films treated oxygen, argon, or nitrogen GP were characterized using contact angles, scanning electron microscopy, atomic force microscopy, optical profilometry, and x-ray photoelectron spectroscopy. All three GP treatments decreased the carbon atomic concentration and surface roughness and increased the oxygen atomic concentration. Human umbilical vein endothelial cells were cultured on the PLA films for up to 7 days. Based on proliferation and live/dead assays, surface chemistry was shown to have the greatest effect on the attachment, proliferation, and viability of these cells, while roughness did not have a significant influence. Of the different gases, endothelial cell viability, attachment and proliferation were most significantly increased on PLA surfaces treated with oxygen and argon gas plasma. Copyright © 2010 John Wiley & Sons, Ltd.

Nanotopography Promotes Pancreatic Differentiation of Human Embryonic Stem Cells and Induced Pluripotent Stem Cells.

PubMed

Kim, Jong Hyun; Kim, Hyung Woo; Cha, Kyoung Je; Han, Jiyou; Jang, Yu Jin; Kim, Dong Sung; Kim, Jong-Hoon

2016-03-22

Although previous studies suggest that nanotopographical features influence properties and behaviors of stem cells, only a few studies have attempted to derive clinically useful somatic cells from human pluripotent stem cells using nanopatterned surfaces. In the present study, we report that polystyrene nanopore-patterned surfaces significantly promote the pancreatic differentiation of human embryonic and induced pluripotent stem cells. We compared different diameters of nanopores and showed that 200 nm nanopore-patterned surfaces highly upregulated the expression of PDX1, a critical transcription factor for pancreatic development, leading to an approximately 3-fold increase in the percentage of differentiating PDX1(+) pancreatic progenitors compared with control flat surfaces. Furthermore, in the presence of biochemical factors, 200 nm nanopore-patterned surfaces profoundly enhanced the derivation of pancreatic endocrine cells producing insulin, glucagon, or somatostatin. We also demonstrate that nanopore-patterned surface-induced upregulation of PDX1 is associated with downregulation of TAZ, suggesting the potential role of TAZ in nanopore-patterned surface-mediated mechanotransduction. Our study suggests that appropriate cytokine treatments combined with nanotopographical stimulation could be a powerful tool for deriving a high purity of desired cells from human pluripotent stem cells.

Gold Nanoparticles-Enhanced Proton Exchange Membrane (PEM) Fuel Cell

NASA Astrophysics Data System (ADS)

Li, Hongfei; Pan, Cheng; Liu, Ping; Zhu, Yimei; Adzic, Radoslav; Rafailovich, Miriam

Proton exchange membrane fuel cells have drawn great attention and been taken as a promising alternated energy source. One of the reasons hamper the wider application of PEM fuel cell is the catalytic poison effect from the impurity of the gas flow. Haruta has predicted that gold nanoparticles that are platelet shaped and have direct contact with the metal oxide substrate to be the perfect catalysts of the CO oxidization, yet the synthesis method is difficult to apply in the Fuel Cell. In our approach, thiol-functionalized gold nanoparticles were synthesized through two-phase method developed by Brust et al. We deposit these Au particles with stepped surface directly onto the Nafion membrane in the PEM fuel cell by Langmuir-Blodgett method, resulting in over 50% enhancement of the efficiency of the fuel cell. DFT calculations were conducted to understand the theory of this kind of enhancement. The results indicated that only when the particles were in direct surface contact with the membrane, where AuNPs attached at the end of the Nafion side chains, it could reduce the energy barrier for the CO oxidation that could happen at T<300K.

Aluminum reduction cell electrode

DOEpatents

Payne, J.R.

1983-09-20

The invention is directed to an anode-cathode structure for an electrolytic cell for the reduction of alumina wherein the structure is comprised of a carbon anode assembly which straddles a wedge-shaped refractory hard metal cathode assembly having steeply sloped cathodic surfaces, each cathodic surface being paired in essentially parallel planar relationship with an anode surface. The anode-cathode structure not only takes into account the structural weakness of refractory hard metal materials but also permits the changing of the RHM assembly during operation of the cell. Further, the anode-cathode structure enhances the removal of anode gas from the interpolar gap between the anode and cathode surfaces. 10 figs.

Aluminum reduction cell electrode

DOEpatents

Payne, John R.

1983-09-20

The invention is directed to an anode-cathode structure for an electrolytic cell for the reduction of alumina wherein the structure is comprised of a carbon anode assembly which straddles a wedge-shaped refractory hard metal cathode assembly having steeply sloped cathodic surfaces, each cathodic surface being paired in essentially parallel planar relationship with an anode surface. The anode-cathode structure not only takes into account the structural weakness of refractory hard metal materials but also permits the changing of the RHM assembly during operation of the cell. Further, the anode-cathode structure enhances the removal of anode gas from the interpolar gap between the anode and cathode surfaces.

Biofilm development by blastospores and hyphae of Candida albicans on abraded denture acrylic resin surfaces.

PubMed

Jackson, Sarah; Coulthwaite, Lisa; Loewy, Zvi; Scallan, Anthony; Verran, Joanna

2014-10-01

Candida albicans is a known etiologic agent of denture stomatitis. Candida hyphae exhibit the ability to respond directionally to environmental stimuli. This characteristic is thought to be important in the penetration of substrata such as resilient denture liners and host epithelium. It has been suggested that hyphal production also enhances adhesion and survival of Candida on host and denture surfaces. Surface roughness, in addition, can enhance adhesion where stronger interactions occur between cells and surface features of similar dimensions. The purpose of this study was to assess the development of hyphal and blastospore biofilms on abraded denture acrylic resin specimens and measure the ease of removal of these biofilms. Biofilms were grown for 48 hours on abraded 1-cm² denture acrylic resin specimens from adhered hyphal phase C albicans or from adhered blastospores. Subsequently, all specimens were stained with Calcofluor White and examined with confocal scanning laser microscopy. Biofilms were removed by vortex mixing in sterile phosphate buffered saline solution. Removed cells were filtered (0.2-μm pore size). Filters were dried at 37°C for 24 hours for dry weight measurements. Any cells that remained on the acrylic resin specimens were stained with 0.03% acridine orange and examined with epifluorescence microscopy. Biofilms grown from both cell types contained all morphologic forms of C albicans. Although the underlying surface topography did not affect the amount of biofilm produced, biofilms grown from hyphal phase Candida were visibly thicker and had greater biomass (P<.05). These biofilms were less easily removed from the denture acrylic resin, especially in the case of rougher surfaces, evidenced by the higher numbers of retained cells (P≤.05). The presence of hyphae in early Candida biofilms increased biofilm mass and resistance to removal. Increased surface roughness enhances retention of hyphae and yeast cells, and, therefore, will facilitate plaque regrowth. Therefore, minimization of denture abrasion during cleaning is desirable. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Nanotubular topography enhances the bioactivity of titanium implants.

PubMed

Huang, Jingyan; Zhang, Xinchun; Yan, Wangxiang; Chen, Zhipei; Shuai, Xintao; Wang, Anxun; Wang, Yan

2017-08-01

Surface modification on titanium implants plays an important role in promoting mesenchymal stem cell (MSC) response to enhance osseointegration persistently. In this study, nano-scale TiO 2 nanotube topography (TNT), micro-scale sand blasted-acid etched topography (SLA), and hybrid sand blasted-acid etched/nanotube topography (SLA/TNT) were fabricated on the surfaces of titanium implants. Although the initial cell adherence at 60 min among TNT, SLA and TNT/SLA was not different, SLA and SLA/TNT presented to be rougher and suppressed the proliferation of MSC. TNT showed hydrophilic surface and balanced promotion of cellular functions. After being implanted in rabbit femur models, TNT displayed the best osteogenesis inducing ability as well as strong bonding strength to the substrate. These results indicate that nano-scale TNT provides favorable surface topography for improving the clinical performance of endosseous implants compared with micro and hybrid micro/nano surfaces, suggesting a promising and reliable surface modification strategy of titanium implants for clinical application. Copyright © 2017 Elsevier Inc. All rights reserved.

Combined surface-enhanced Raman spectroscopy biotags and microfluidic platform for quantitative ratiometric discrimination between noncancerous and cancerous cells in flow

NASA Astrophysics Data System (ADS)

Pallaoro, Alessia; Hoonejani, Mehran R.; Braun, Gary B.; Meinhart, Carl; Moskovits, Martin

2013-01-01

Surface-enhanced Raman spectroscopy (SERS) biotags (SBTs) that carry peptides as cell recognition moieties were made from polymer-encapsulated silver nanoparticle dimers, infused with unique Raman reporter molecules. We previously demonstrated their potential use for identification of malignant cells, a central goal in cancer research, through a multiplexed, ratiometric method that can confidently distinguish between cancerous and noncancerous epithelial prostate cells in vitro based on receptor overexpression. Progress has been made toward the application of this quantitative methodology for the identification of cancer cells in a microfluidic flow-focusing device. Beads are used as cell mimics to evaluate the devices. Cells (and beads) are simultaneously incubated with two sets of SBTs while in suspension, then injected into the device for laser interrogation under flow. Each cell event is characterized by a composite Raman spectrum, deconvoluted into its single components to ultimately determine their relative contribution. We have found that using SBTs ratiometrically can provide cell identification in flow, insensitive to normal causes of uncertainty in optical measurements such as variations in focal plane, cell concentration, autofluorescence, and turbidity.

TiO2 -enriched polymeric powder coatings support human mesenchymal cell spreading and osteogenic differentiation.

PubMed

Mozumder, Mohammad Sayem; Zhu, Jesse; Perinpanayagam, Hiran

2011-06-01

Novel polymeric powder coatings (PPC) were prepared by ultrafine powder coating technology and shown to support human mesenchymal cell attachment and growth. PPC surfaces enriched with nano-TiO(2) (nTiO(2)) showed enhanced cellular responses, and were compared to commercially pure titanium (cpTi). After cell attachment and growth, osteogenic differentiation and bone matrix formation ensures osseointegration for implantable biomaterials. Therefore, the objective of this study was to determine if mesenchymal cells grown on PPC could undergo osteogenic differentiation by inducing Runx2 and bone matrix proteins, and then initiate mineralization. Atomic force microscopy revealed intricate three-dimensional micro-topographies, and the measures of nano-roughness and porosity were similar for all PPC surfaces. Scanning electron microscopy showed that the cells attached and spread out over all of the surfaces. After 1 week in osteogenic media, RT-PCR analysis showed the induction of Runx2, the up-regulation of type I collagen, and the initial detection of alkaline phosphatase and bone sialoprotein. After 4 weeks, Alizarin Red staining showed mineral deposition. However, cell spreading and osteogenic differentiation were significantly (P < 0.05) higher on the cpTi controls than on the PPC surfaces. Furthermore, spreading and differentiation were consistently higher on the titanium-enriched PPC-2, -3 and -4 than on the titanium-free PPC-1. Therefore, despite the presence of complex micro-topographies and nano-features, titanium-enrichment enhanced the cellular response, and pure titanium still provided the best substrate. These findings confirm the cytocompatibility of these novel polymeric coatings and suggest that titanium-enrichment and nTiO(2) additives may enhance their performance.

Sensitive electrochemiluminescence biosensor based on Au-ITO hybrid bipolar electrode amplification system for cell surface protein detection.

PubMed

Wu, Mei-Sheng; Yuan, Da-Jing; Xu, Jing-Juan; Chen, Hong-Yuan

2013-12-17

Here we developed a novel hybrid bipolar electrode (BPE)-electrochemiluminescence (ECL) biosensor based on hybrid bipolar electrode (BPE) for the measurement of cancer cell surface protein using ferrocence (Fc) labeled aptamer as signal recognition and amplification probe. According to the electric neutrality of BPE, the cathode of U-shaped ITO BPE was electrochemically deposited by Au nanoparticles (NPs) to enhance its conductivity and surface area, decrease the overpotential of O2 reduction, which would correspondingly increase the oxidation current of Ru(bpy)3(2+)/tripropylamine (TPA) on the anode of BPE and resulting a ∼4-fold enhancement of ECL intensity. Then a signal amplification strategy was designed by introducing Fc modified aptamer on the anode surface of BPE through hybridization for detecting the amount of mucin-1 on MCF-7 cells. The presence of Fc could not only inhibit the oxidation of Ru(bpy)3(2+) because of its lower oxidation potential, its oxidation product Fc(+) could also quench the ECL of Ru(bpy)3(2+)/TPA by efficient energy-transfer from the excited-state Ru(bpy)3(2+)* to Fc(+), making the ECL intensity greatly quenched. On the basis of the cathodic Au NPs induced ECL enhancing coupled with anodic Fc induced signal quenching amplification, the approach allowed detection of mucin-1 aptamer at a concentration down to 0.5 fM and was capable of detecting a minimum of 20 MCF-7 cells. Besides, the amount of mucin-1 on MCF-7 cells was calculated to be 9041 ± 388 molecules/cell. This approach therefore shows great promise in bioanalysis.

Comparison of candidate materials for a synthetic osteo-odonto keratoprosthesis device.

PubMed

Tan, Xiao Wei; Perera, A Promoda P; Tan, Anna; Tan, Donald; Khor, K A; Beuerman, Roger W; Mehta, Jodhbir S

2011-01-05

Osteo-odonto keratoprosthesis is one of the most successful forms of keratoprosthesis surgery for end-stage corneal and ocular surface disease. There is a lack of detailed comparison studies on the biocompatibilities of different materials used in keratoprosthesis. The aim of this investigation was to compare synthetic bioinert materials used for keratoprosthesis surgery with hydroxyapatite (HA) as a reference. Test materials were sintered titanium oxide (TiO(2)), aluminum oxide (Al(2)O(3)), and yttria-stabilized zirconia (YSZ) with density >95%. Bacterial adhesion on the substrates was evaluated using scanning electron microscopy and the spread plate method. Surface properties of the implant discs were scanned using optical microscopy. Human keratocyte attachment and proliferation rates were assessed by cell counting and MTT assay at different time points. Morphologic analysis and immunoblotting were used to evaluate focal adhesion formation, whereas cell adhesion force was measured with a multimode atomic force microscope. The authors found that bacterial adhesion on the TiO(2), Al(2)O(3), and YSZ surfaces were lower than that on HA substrates. TiO(2) significantly promoted keratocyte proliferation and viability compared with HA, Al(2)O(3,) and YSZ. Immunofluorescent imaging analyses, immunoblotting, and atomic force microscope measurement revealed that TiO(2) surfaces enhanced cell spreading and cell adhesion compared with HA and Al(2)O(3). TiO(2) is the most suitable replacement candidate for use as skirt material because it enhanced cell functions and reduced bacterial adhesion. This would, in turn, enhance tissue integration and reduce device failure rates during keratoprosthesis surgery.

Strategies for the chemical and biological functionalization of scaffolds for cardiac tissue engineering: a review.

PubMed

Tallawi, Marwa; Rosellini, Elisabetta; Barbani, Niccoletta; Cascone, Maria Grazia; Rai, Ranjana; Saint-Pierre, Guillaume; Boccaccini, Aldo R

2015-07-06

The development of biomaterials for cardiac tissue engineering (CTE) is challenging, primarily owing to the requirement of achieving a surface with favourable characteristics that enhances cell attachment and maturation. The biomaterial surface plays a crucial role as it forms the interface between the scaffold (or cardiac patch) and the cells. In the field of CTE, synthetic polymers (polyglycerol sebacate, polyethylene glycol, polyglycolic acid, poly-l-lactide, polyvinyl alcohol, polycaprolactone, polyurethanes and poly(N-isopropylacrylamide)) have been proven to exhibit suitable biodegradable and mechanical properties. Despite the fact that they show the required biocompatible behaviour, most synthetic polymers exhibit poor cell attachment capability. These synthetic polymers are mostly hydrophobic and lack cell recognition sites, limiting their application. Therefore, biofunctionalization of these biomaterials to enhance cell attachment and cell material interaction is being widely investigated. There are numerous approaches for functionalizing a material, which can be classified as mechanical, physical, chemical and biological. In this review, recent studies reported in the literature to functionalize scaffolds in the context of CTE, are discussed. Surface, morphological, chemical and biological modifications are introduced and the results of novel promising strategies and techniques are discussed.

Strategies for the chemical and biological functionalization of scaffolds for cardiac tissue engineering: a review

PubMed Central

Tallawi, Marwa; Rosellini, Elisabetta; Barbani, Niccoletta; Cascone, Maria Grazia; Rai, Ranjana; Saint-Pierre, Guillaume; Boccaccini, Aldo R.

2015-01-01

The development of biomaterials for cardiac tissue engineering (CTE) is challenging, primarily owing to the requirement of achieving a surface with favourable characteristics that enhances cell attachment and maturation. The biomaterial surface plays a crucial role as it forms the interface between the scaffold (or cardiac patch) and the cells. In the field of CTE, synthetic polymers (polyglycerol sebacate, polyethylene glycol, polyglycolic acid, poly-l-lactide, polyvinyl alcohol, polycaprolactone, polyurethanes and poly(N-isopropylacrylamide)) have been proven to exhibit suitable biodegradable and mechanical properties. Despite the fact that they show the required biocompatible behaviour, most synthetic polymers exhibit poor cell attachment capability. These synthetic polymers are mostly hydrophobic and lack cell recognition sites, limiting their application. Therefore, biofunctionalization of these biomaterials to enhance cell attachment and cell material interaction is being widely investigated. There are numerous approaches for functionalizing a material, which can be classified as mechanical, physical, chemical and biological. In this review, recent studies reported in the literature to functionalize scaffolds in the context of CTE, are discussed. Surface, morphological, chemical and biological modifications are introduced and the results of novel promising strategies and techniques are discussed. PMID:26109634

Unified Electromagnetic-Electronic Design of Light Trapping Silicon Solar Cells

PubMed Central

Boroumand, Javaneh; Das, Sonali; Vázquez-Guardado, Abraham; Franklin, Daniel; Chanda, Debashis

2016-01-01

A three-dimensional unified electromagnetic-electronic model is developed in conjunction with a light trapping scheme in order to predict and maximize combined electron-photon harvesting in ultrathin crystalline silicon solar cells. The comparison between a bare and light trapping cell shows significant enhancement in photon absorption and electron collection. The model further demonstrates that in order to achieve high energy conversion efficiency, charge separation must be optimized through control of the doping profile and surface passivation. Despite having a larger number of surface defect states caused by the surface patterning in light trapping cells, we show that the higher charge carrier generation and collection in this design compensates the absorption and recombination losses and ultimately results in an increase in energy conversion efficiency. The fundamental physics behind this specific design approach is validated through its application to a 3 μm thick functional light trapping solar cell which shows 192% efficiency enhancement with respect to the bare cell of same thickness. Such a unified design approach will pave the path towards achieving the well-known Shockley-Queisser (SQ) limit for c-Si in thin-film (<30 μm) geometries. PMID:27499446

Augmented liver targeting of exosomes by surface modification with cationized pullulan.

PubMed

Tamura, Ryo; Uemoto, Shinji; Tabata, Yasuhiko

2017-07-15

Exosomes are membrane nanoparticles containing biological substances that are employed as therapeutics in experimental inflammatory models. Surface modification of exosomes for better tissue targetability and enhancement of their therapeutic ability was recently attempted mainly using gene transfection techniques. Here, we show for the first time that the surface modification of exosomes with cationized pullulan, which has the ability to target hepatocyte asialoglycoprotein receptors, can target injured liver and enhance the therapeutic effect of exosomes. Surface modification can be achieved by a simple mixing of original exosomes and cationized pullulan and through an electrostatic interaction of both substances. The exosomes modified with cationized pullulan were internalized into HepG2 cells in vitro to a significantly greater extent than unmodified ones and this internalization was induced through the asialoglycoprotein receptor that was specifically expressed on HepG2 cells and hepatocytes. When injected intravenously into mice with concanavalin A-induced liver injury, the modified exosomes accumulated in the liver tissue, resulting in an enhanced anti-inflammatory effect in vivo. It is concluded that the surface modification with cationized pullulan promoted accumulation of the exosomes in the liver and the subsequent biological function, resulting in a greater therapeutic effect on liver injury. Exosomes have shown potentials as therapeutics for various inflammatory disease models. This study is the first to show the specific accumulation of exosomes in the liver and enhanced anti-inflammatory effect via the surface modification of exosomes using pullulan, which is specifically recognized by the asialoglycoprotein receptor (AGPR) on HepG2 cells and hepatocytes. The pullulan was expressed on the surface of PKH-labeled exosomes, and it led increased accumulation of PKH into HepG2 cells, whereas the accumulation was canceled by AGPR inhibitor. In the mouse liver injury model, the modification of PKH-labeled exosomes with pullulan enabled increased accumulation of PKH specifically in the injured liver. Furthermore the greater therapeutic effects against the liver injury compared with unmodified original exosomes was observed. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Cockroach protease allergen induces allergic airway inflammation via epithelial cell activation

PubMed Central

Kale, Sagar L.; Agrawal, Komal; Gaur, Shailendra Nath; Arora, Naveen

2017-01-01

Protease allergens are known to enhance allergic inflammation but their exact role in initiation of allergic reactions at mucosal surfaces still remains elusive. This study was aimed at deciphering the role of serine protease activity of Per a 10, a major cockroach allergen in initiation of allergic inflammation at mucosal surfaces. We demonstrate that Per a 10 increases epithelial permeability by disruption of tight junction proteins, ZO-1 and occludin, and enhances the migration of Monocyte derived dendritic cell precursors towards epithelial layer as exhibited by trans-well studies. Per a 10 exposure also leads to secretion of IL-33, TSLP and intracellular Ca2+ dependent increase in ATP levels. Further, in vivo experiments revealed that Per a 10 administration in mice elevated allergic inflammatory parameters along with high levels of IL-33, TSLP, IL-1α and uric acid in the mice lungs. We next demonstrated that Per a 10 cleaves CD23 (low affinity IgE receptor) from the surface of PBMCs and purified B cells and CD25 (IL-2 receptor) from the surface of PBMCs and purified T cells in an activity dependent manner, which might favour Th2 responses. In conclusion, protease activity of Per a 10 plays a significant role in initiation of allergic airway inflammation at the mucosal surfaces. PMID:28198394

Fabrication and characterization of carboxymethyl cellulose novel microparticles for bone tissue engineering.

PubMed

Gaihre, Bipin; Jayasuriya, Ambalangodage C

2016-12-01

In this study we developed carboxymethyl cellulose (CMC) microparticles through ionic crosslinking with the aqueous ion complex of zirconium (Zr) and further complexing with chitosan (CS) and determined the physio-chemical and biological properties of these novel microparticles. In order to assess the role of Zr, microparticles were prepared in 5% and 10% (w/v) zirconium tetrachloride solution. Scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS) results showed that Zr was uniformly distributed on the surface of the microparticles as a result of which uniform groovy surface was obtained. We found that Zr enhances the surface roughness of the microparticles and stability studies showed that it also increases the stability of microparticles in phosphate buffered saline. The crosslinking of anionic CMC with cationic Zr and CS was confirmed by Fourier transform infrared spectroscopy (FTIR) results. The response of murine pre-osteoblasts (OB-6) when cultured with microparticles was investigated. Live/dead cell assay showed that microparticles did not induce any cytotoxic effects as cells were attaching and proliferating on the well plate as well as along the surface of microparticles. In addition, SEM images showed that microparticles support the attachment of cells and they appeared to be directly interacting with the surface of microparticle. Within 10days of culture most of the top surface of microparticles was covered with a layer of cells indicating that they were proliferating well throughout the surface of microparticles. We observed that Zr enhances the cell attachment and proliferation as more cells were present on microparticles with 10% Zr. These promising results show the potential applications of CMC-Zr microparticles in bone tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

Facile and rapid synthesis of Pd nanodendrites for electrocatalysis and surface-enhanced Raman scattering applications

NASA Astrophysics Data System (ADS)

Kannan, Palanisamy; Dolinska, Joanna; Maiyalagan, Thandavarayan; Opallo, Marcin

2014-09-01

Numerous properties from metal nanostructures can be tuned by controlling both their size and shape. In particular, the latter is extremely important because the type of crystalline surface affects the surface electronic density. This paper describes a simple approach to the synthesis of highly-structured, anisotropic palladium nanostructured dendrites. They were obtained using an eco-friendly biomolecule 5-hydroxytryptophan, which acts as both a reducing and stabilizing agent. The growth mechanism is proposed for the evolution of dendrites morphology. It was found that the concentration of 5-hydroxytryptophan played a vital role on the morphology of the nanostructured Pd dendrites. This nanomaterial shows enhanced electrocatalytic performance towards the oxidation of formic acid, and it exhibits surface-enhanced Raman scattering properties towards the prostate specific antigen. These properties may be explored in fuel cells and biosensors, respectively.Numerous properties from metal nanostructures can be tuned by controlling both their size and shape. In particular, the latter is extremely important because the type of crystalline surface affects the surface electronic density. This paper describes a simple approach to the synthesis of highly-structured, anisotropic palladium nanostructured dendrites. They were obtained using an eco-friendly biomolecule 5-hydroxytryptophan, which acts as both a reducing and stabilizing agent. The growth mechanism is proposed for the evolution of dendrites morphology. It was found that the concentration of 5-hydroxytryptophan played a vital role on the morphology of the nanostructured Pd dendrites. This nanomaterial shows enhanced electrocatalytic performance towards the oxidation of formic acid, and it exhibits surface-enhanced Raman scattering properties towards the prostate specific antigen. These properties may be explored in fuel cells and biosensors, respectively. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02896a

Enhanced charge carrier transport properties in colloidal quantum dot solar cells via organic and inorganic hybrid surface passivation† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6ta06835a Click here for additional data file.

PubMed Central

Hong, John; Hou, Bo; Lim, Jongchul; Pak, Sangyeon; Kim, Byung-Sung; Cho, Yuljae; Lee, Juwon; Lee, Young-Woo; Giraud, Paul; Lee, Sanghyo; Park, Jong Bae; Morris, Stephen M.; Snaith, Henry J.; Kim, Jong Min

2016-01-01

Colloidal quantum dots (CQDs) are extremely promising as photovoltaic materials. In particular, the tunability of their electronic band gap and cost effective synthetic procedures allow for the versatile fabrication of solar energy harvesting cells, resulting in optimal device performance. However, one of the main challenges in developing high performance quantum dot solar cells (QDSCs) is the improvement of the photo-generated charge transport and collection, which is mainly hindered by imperfect surface functionalization, such as the presence of surface electronic trap sites and the initial bulky surface ligands. Therefore, for these reasons, finding effective methods to efficiently decorate the surface of the as-prepared CQDs with new short molecular length chemical structures so as to enhance the performance of QDSCs is highly desirable. Here, we suggest employing hybrid halide ions along with the shortest heterocyclic molecule as a robust passivation structure to eliminate surface trap sites while decreasing the charge trapping dynamics and increasing the charge extraction efficiency in CQD active layers. This hybrid ligand treatment shows a better coordination with Pb atoms within the crystal, resulting in low trap sites and a near perfect removal of the pristine initial bulky ligands, thereby achieving better conductivity and film structure. Compared to halide ion-only treated cells, solar cells fabricated through this hybrid passivation method show an increase in the power conversion efficiency from 5.3% for the halide ion-treated cells to 6.8% for the hybrid-treated solar cells. PMID:29308200

Multilayer Choline Phosphate Molecule Modified Surface with Enhanced Cell Adhesion but Resistance to Protein Adsorption.

PubMed

Chen, Xingyu; Yang, Ming; Liu, Botao; Li, Zhiqiang; Tan, Hong; Li, Jianshu

2017-08-22

Choline phosphate (CP), which is a new zwitterionic molecule, and has the reverse order of phosphate choline (PC) and could bind to the cell membrane though the unique CP-PC interaction. Here we modified a glass surface with multilayer CP molecules using surface-initiated atom-transfer radical polymerization (SI-ATRP) and the ring-opening method. Polymeric brushes of (dimethylamino)ethyl methacrylate (DMAEMA) were synthesized by SI-ATRP from the glass surface. Then the grafted PDMAEMA brushes were used to introduce CP groups to fabricate the multilayer CP molecule modified surface. The protein adsorption experiment and cell culture test were used to evaluate the biocompatibility of the modified surfaces by using human umbilical veinendothelial cells (HUVECs). The protein adsorption results demonstrated that the multilayer CP molecule decorated surface could prevent the adsorption of fibrinogen and serum protein. The adhesion and proliferation of cells were improved significantly on the multilayer CP molecule modified surface. Therefore, the biocompatibility of the material surface could be improved by the modified multilayer CP molecule, which exhibits great potential for biomedical applications, e.g., scaffolds in tissue engineering.

Enhanced Charge Collection with Passivation Layers in Perovskite Solar Cells.

PubMed

Lee, Yong Hui; Luo, Jingshan; Son, Min-Kyu; Gao, Peng; Cho, Kyung Taek; Seo, Jiyoun; Zakeeruddin, Shaik M; Grätzel, Michael; Nazeeruddin, Mohammad Khaja

2016-05-01

The Al2 O3 passivation layer is beneficial for mesoporous TiO2 -based perovskite solar cells when it is deposited selectively on the compact TiO2 surface. Such a passivation layer suppressing surface recombination can be formed by thermal decomposition of the perovskite layer during post-annealing. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced neurite outgrowth of PC-12 cells on graphene-monolayer-coated substrates as biomimetic cues

NASA Astrophysics Data System (ADS)

Lee, Jong Ho; Shin, Yong Cheol; Jin, Oh Seong; Han, Dong-Wook; Kang, Seok Hee; Hong, Suck Won; Kim, Jong Man

2012-11-01

Neurons are electrically excitable cells that transmit and process information in the nervous system. Recently, the differentiation of human neural stem cells to neurons has been shown to be enhanced on graphene substrates, and differentiated neurons have been shown to be able to still carry electrical signals when stimulated by graphene electrodes. Graphene films grown by using chemical vapor deposition were transferred onto glass coverslips by using the scooping method and were then coated with fetal bovine serum for a neuronal cell culture. The graphene substrates as biomimetic cues have been shown to enhance the neurite outgrowth of PC-12 cells. Our findings suggest that graphene has a unique surface property that can promote neuronal cells, which should open tremendous opportunities in neuroscience, neural engineering and regenerative medicine.

Simple surface engineering of polydimethylsiloxane with polydopamine for stabilized mesenchymal stem cell adhesion and multipotency

PubMed Central

Chuah, Yon Jin; Koh, Yi Ting; Lim, Kaiyang; Menon, Nishanth V.; Wu, Yingnan; Kang, Yuejun

2015-01-01

Polydimethylsiloxane (PDMS) has been extensively exploited to study stem cell physiology in the field of mechanobiology and microfluidic chips due to their transparency, low cost and ease of fabrication. However, its intrinsic high hydrophobicity renders a surface incompatible for prolonged cell adhesion and proliferation. Plasma-treated or protein-coated PDMS shows some improvement but these strategies are often short-lived with either cell aggregates formation or cell sheet dissociation. Recently, chemical functionalization of PDMS surfaces has proved to be able to stabilize long-term culture but the chemicals and procedures involved are not user- and eco-friendly. Herein, we aim to tailor greener and biocompatible PDMS surfaces by developing a one-step bio-inspired polydopamine coating strategy to stabilize long-term bone marrow stromal cell culture on PDMS substrates. Characterization of the polydopamine-coated PDMS surfaces has revealed changes in surface wettability and presence of hydroxyl and secondary amines as compared to uncoated surfaces. These changes in PDMS surface profile contribute to the stability in BMSCs adhesion, proliferation and multipotency. This simple methodology can significantly enhance the biocompatibility of PDMS-based microfluidic devices for long-term cell analysis or mechanobiological studies. PMID:26647719

Enhancement of bile resistance in Lactobacillus plantarum strains by soy lecithin.

PubMed

Hu, B; Tian, F; Wang, G; Zhang, Q; Zhao, J; Zhang, H; Chen, W

2015-07-01

This study evaluated the effect of soy lecithin on the bile resistance of Lactobacillus plantarum. Six strains were cultured in MRS broth supplemented with soy lecithin at different concentrations. The strains incubated in MRS broth with 1·0% soy lecithin showed no inhibitory effect on cell growth. After culturing in MRS broth with 0·2-1·0% soy lecithin, the survival rate of harvested cells increased significantly (P < 0·05) in the 0·3% bile challenge compared with the no added soy lecithin group. The cells incubated with 0·6% soy lecithin were able to grow in an MRS broth with a higher bile salt content. The surface hydrophobicity and cell leakage in the bile challenge were assessed to reveal the physical changes caused by the addition of soy lecithin. The cell surface hydrophobicity was enhanced and the membrane integrity in the bile challenge increased after culturing with soy lecithin. A shift in the fatty acid composition was also observed, illustrating the cell membrane change in the soy lecithin culture. In this study, we report for the first time the beneficial effect of adding soy lecithin to an MRS broth on subsequent bile tolerance of Lactobacillus plantarum. Soy lecithin had no inhibitory effect on strain viability but significantly enhanced bile resistance. Surface hydrophobicity and cell integrity increased in strains cultured with soy lecithin. The observed shift in the cell fatty acid composition indicated changes to the cell membrane. As soy lecithin is safe for use in the food industry, its protective effects can be harnessed for the development of bile-sensitive strains with health-benefit functions for use in probiotic products. © 2015 The Society for Applied Microbiology.

Enhanced MC3T3-E1 preosteoblast response and bone formation on the addition of nano-needle and nano-porous features to microtopographical titanium surfaces.

PubMed

Zhuang, X-M; Zhou, B; Ouyang, J-L; Sun, H-P; Wu, Y-L; Liu, Q; Deng, F-L

2014-08-01

Micro/nanotopographical modifications on titanium surfaces constitute a new process to increase osteoblast response to enhance bone formation. In this study, we utilized alkali heat treatment at high (SB-AH1) and low temperatures (SB-AH2) to nano-modify sandblasted titanium with microtopographical surfaces. Then, we evaluated the surface properties, biocompatibility and osteogenic capability of SB-AH1 and SB-AH2 in vitro and in vivo, and compared these with conventional sandblast-acid etching (SLA) and Ti control surfaces. SB-AH1 and SB-AH2 surfaces exhibited micro/nanotopographical modifications of nano-needle structures and nano-porous network layers, respectively, compared with the sole microtopographical surface of macro and micro pits on the SLA surface and the relatively smooth surface on the Ti control. SB-AH1 and SB-AH2 showed different roughness and elemental components, but similar wettability. MC3T3-E1 preosteoblasts anchored closely on the nanostructures of SB-AH1 and SB-AH2 surfaces, and these two surfaces more significantly enhanced cell proliferation and alkaline phosphatase (ALP) activity than others, while the SB-AH2 surface exhibited better cell proliferation and higher ALP activity than SB-AH1. All four groups of titanium domes with self-tapping screws were implanted in rabbit calvarial bone models, and these indicated that SB-AH1 and SB-AH2 surfaces achieved better peri-implant bone formation and implant stability, while the SB-AH2 surface achieved the best percentage of bone-implant contact (BIC%). Our study demonstrated that the micro/nanotopographical surface generated by sandblasting and alkali heat treatment significantly enhanced preosteoblast proliferation, ALP activity and bone formation in vitro and in vivo, and nano-porous network topography may further induce better preosteoblast proliferation, ALP activity and BIC%.

In situ, accurate, surface-enhanced Raman scattering detection of cancer cell nucleus with synchronous location by an alkyne-labeled biomolecular probe.

PubMed

Zhang, Jing; Liang, Lijia; Guan, Xin; Deng, Rong; Qu, Huixin; Huang, Dianshuai; Xu, Shuping; Liang, Chongyang; Xu, Weiqing

2018-01-01

A surface-enhanced Raman scattering (SERS) method for in situ detection and analysis of the intranuclear biomolecular information of a cell has been developed based on a small, biocompatible, nuclear-targeting alkyne-tagged deoxyribonucleic acid (DNA) probe (5-ethynyl-2'-deoxyuridine, EDU) that can specially accumulate in the cell nucleus during DNA replications to precisely locate the nuclear region without disturbance in cell biological activities and functions. Since the specific alkyne group shows a Raman peak in the Raman-silent region of cells, it is an interior label to visualize the nuclear location synchronously in real time when measuring the SERS spectra of a cell. Because no fluorescent-labeled dyes were used for locating cell nuclei, this method is simple, nondestructive, non- photobleaching, and valuable for the in situ exploration of vital physiological processes with DNA participation in cell organelles. Graphical abstract A universal strategy was developed to accurately locate the nuclear region and obtain precise molecular information of cell nuclei by SERS.

Nanoengineered Plasmonic Hybrid Systems for Bio-nanotechnology

NASA Astrophysics Data System (ADS)

Leong, Kirsty

Plasmonic hybrid systems are fabricated using a combination of lithography and layer-by-layer directed self-assembly approaches to serve as highly sensitive nanosensing devices. This layer-by-layer directed self-assembly approach is utilized as a hybrid methodology to control the organization of quantum dots (QDs), nanoparticles, and biomolecules onto inorganic nanostructures with site-specific attachment and functionality. Here, surface plasmon-enhanced nanoarrays are fabricated where the photoluminescence of quantum dots and conjugated polymer nanoarrays are studied. This study was performed by tuning the localized surface plasmon resonance and the distance between the emitter and the metal surface using genetically engineered polypeptides as binding agents and biotin-streptavidin binding as linker molecules. In addition, these nanoarrays were also chemically modified to support the immobilization and label-free detection of DNA using surface enhanced Raman scattering. The surface of the nanoarrays was chemically modified using an acridine containing molecule which can act as an intercalating agent for DNA. The self-assembled monolayer (SAM) showed the ability to immobilize and intercalate DNA onto the surface. This SAM system using surface enhanced Raman scattering (SERS) serves as a highly sensitive methodology for the immobilization and label-free detection of DNA applicable into a wide range of bio-diagnostic platforms. Other micropatterned arrays were also fabricated using a combination of soft lithography and surface engineering. Selective single cell patterning and adhesion was achieved through chemical modifications and surface engineering of poly(dimethylsiloxane) surface. The surface of each microwell was functionally engineered with a SAM which contained an aldehyde terminated fused-ring aromatic thiolated molecule. Cells were found to be attracted and adherent to the chemically modified microwells. By combining soft lithography and surface engineering, a simple methodology produced single cell arrays on biocompatible substrates. Thus the design of plasmonic devices relies heavily on the nature of the plasmonic interactions between nanoparticles in the devices which can potentially be fabricated into lab-on-a-chip devices for multiplex sensing capabilities.

Development of an electro-responsive platform for the controlled transfection of mammalian cells

NASA Astrophysics Data System (ADS)

Hook, Andrew L.; Thissen, Helmut W.; Hayes, Jason P.; Voelcker, Nicolas H.

2005-02-01

The recent development of living microarrays as novel tools for the analysis of gene expression in an in-situ environment promises to unravel gene function within living organisms. In order to significantly enhance microarray performance, we are working towards electro-responsive DNA transfection chips. This study focuses on the control of DNA adsorption and desorption by appropriate surface modification of highly doped p++ silicon. Silicon was modified by plasma polymerisation of allylamine (ALAPP), a non-toxic surface that sustains cell growth. Subsequent high surface density grafting of poly(ethylene oxide) formed a layer resistant to biomolecule adsorption and cell attachment. Spatially controlled excimer laser ablation of the surface produced micron resolution patterns of re-exposed plasma polymer whilst the rest of the surface remained non-fouling. We observed electro-stimulated preferential adsorption of DNA to the ALAPP surface and subsequent desorption by the application of a negative bias. Cell culture experiments with HEK 293 cells demonstrated efficient and controlled transfection of cells using the expression of green fluorescent protein as a reporter. Thus, these chemically patterned surfaces are promising platforms for use as living microarrays.

Biofunctionalization of silicone rubber with microgroove-patterned surface and carbon-ion implantation to enhance biocompatibility and reduce capsule formation.

PubMed

Lei, Ze-Yuan; Liu, Ting; Li, Wei-Juan; Shi, Xiao-Hua; Fan, Dong-Li

Silicone rubber implants have been widely used to repair soft tissue defects and deformities. However, poor biocompatibility can elicit capsule formation, usually resulting in prosthesis contracture and displacement in long-term usage. To overcome this problem, this study investigated the properties of silicone rubber materials with or without a microgroove-patterned surface and with or without carbon (C)-ion implantation. Atomic force microscopy, X-ray photoelectron spectroscopy, and a water contact angle test were used to characterize surface morphology and physicochemical properties. Cytocompatibility was investigated by a cell adhesion experiment, immunofluorescence staining, a Cell Counting Kit-8 assay, and scanning electron microscopy in vitro. Histocompatibility was evaluated by studying the inflammatory response and fiber capsule formation that developed after subcutaneous implantation in rats for 7 days, 15 days, and 30 days in vivo. Parallel microgrooves were found on the surfaces of patterned silicone rubber (P-SR) and patterned C-ion-implanted silicone rubber (PC-SR). Irregular larger peaks and deeper valleys were present on the surface of silicone rubber implanted with C ions (C-SR). The silicone rubber surfaces with microgroove patterns had stable physical and chemical properties and exhibited moderate hydrophobicity. PC-SR exhibited moderately increased dermal fibroblast cell adhesion and growth, and its surface microstructure promoted orderly cell growth. Histocompatibility experiments on animals showed that both the anti-inflammatory and antifibrosis properties of PC-SR were slightly better than those of the other materials, and there was also a lower capsular contracture rate and less collagen deposition around implants made from PC-SR. Although the surface chemical properties, dermal fibroblast cell growth, and cell adhesion were not changed by microgroove pattern modification, a more orderly cell arrangement was obtained, leading to enhanced biocompatibility and reduced capsule formation. Thus, this approach to the modification of silicone rubber, in combination with C-ion implantation, should be considered for further investigation and application.

RhoA-Mediated Functions in C3H10T1/2 Osteoprogenitors Are Substrate Topography Dependent.

PubMed

Ogino, Yoichiro; Liang, Ruiwei; Mendonça, Daniela B S; Mendonça, Gustavo; Nagasawa, Masako; Koyano, Kiyoshi; Cooper, Lyndon F

2016-03-01

Surface topography broadly influences cellular responses. Adherent cell activities are regulated, in part, by RhoA, a member of the Rho-family of GTPases. In this study, we evaluated the influence of surface topography on RhoA activity and associated cellular functions. The murine mesenchymal stem cell line C3H10T1/2 cells (osteoprogenitor cells) were cultured on titanium substrates with smooth topography (S), microtopography (M), and nanotopography (N) to evaluate the effect of surface topography on RhoA-mediated functions (cell spreading, adhesion, migration, and osteogenic differentiation). The influence of RhoA activity in the context of surface topography was also elucidated using RhoA pharmacologic inhibitor. Following adhesion, M and N adherent cells developed multiple projections, while S adherent cells had flattened and widespread morphology. RhoA inhibitor induced remarkable longer and thinner cytoplasmic projections on all surfaces. Cell adhesion and osteogenic differentiation was topography dependent with S < M and N surfaces. RhoA inhibition increased adhesion on S and M surfaces, but not N surfaces. Cell migration in a wound healing assay was greater on S versus M versus N surfaces and RhoA inhibitor increased S adherent cell migration, but not N adherent cell migration. RhoA inhibitor enhanced osteogenic differentiation in S adherent cells, but not M or N adherent cells. RhoA activity was surface topography roughness dependent (S < M, N). RhoA activity and -mediated functions are influenced by surface topography. Smooth surface adherent cells appear highly sensitive to RhoA function, while nano-scale topography adherent cell may utilize alternative cellular signaling pathway(s) to influence adherent cellular functions regardless of RhoA activity. © 2015 Wiley Periodicals, Inc.

Dual-Function Au@Y2O3:Eu3+ Smart Film for Enhanced Power Conversion Efficiency and Long-Term Stability of Perovskite Solar Cells.

PubMed

Kim, Chang Woo; Eom, Tae Young; Yang, In Seok; Kim, Byung Su; Lee, Wan In; Kang, Yong Soo; Kang, Young Soo

2017-07-28

In the present study, a dual-functional smart film combining the effects of wavelength conversion and amplification of the converted wave by the localized surface plasmon resonance has been investigated for a perovskite solar cell. This dual-functional film, composed of Au nanoparticles coated on the surface of Y 2 O 3 :Eu 3+ phosphor (Au@Y 2 O 3 :Eu 3+ ) nanoparticle monolayer, enhances the solar energy conversion efficiency to electrical energy and long-term stability of photovoltaic cells. Coupling between the Y 2 O 3 :Eu 3+ phosphor monolayer and ultraviolet solar light induces the latter to be converted into visible light with a quantum yield above 80%. Concurrently, the Au nanoparticle monolayer on the phosphor nanoparticle monolayer amplifies the converted visible light by up to 170%. This synergy leads to an increased solar light energy conversion efficiency of perovskite solar cells. Simultaneously, the dual-function film suppresses the photodegradation of perovskite by UV light, resulting in long-term stability. Introducing the hybrid smart Au@Y 2 O 3 :Eu 3+ film in perovskite solar cells increases their overall solar-to-electrical energy conversion efficiency to 16.1% and enhances long-term stability, as compared to the value of 15.2% for standard perovskite solar cells. The synergism between the wavelength conversion effect of the phosphor nanoparticle monolayer and the wave amplification by the localized surface plasmon resonance of the Au nanoparticle monolayer in a perovskite solar cell is comparatively investigated, providing a viable strategy of broadening the solar spectrum utilization.

Effect of Hydrofluoric Acid Etching Time on Titanium Topography, Chemistry, Wettability, and Cell Adhesion

PubMed Central

Zahran, R.; Rosales Leal, J. I.; Rodríguez Valverde, M. A.; Cabrerizo Vílchez, M. A.

2016-01-01

Titanium implant surface etching has proven an effective method to enhance cell attachment. Despite the frequent use of hydrofluoric (HF) acid, many questions remain unresolved, including the optimal etching time and its effect on surface and biological properties. The objective of this study was to investigate the effect of HF acid etching time on Ti topography, surface chemistry, wettability, and cell adhesion. These data are useful to design improved acid treatment and obtain an improved cell response. The surface topography, chemistry, dynamic wetting, and cell adhesiveness of polished Ti surfaces were evaluated after treatment with HF acid solution for 0, 2; 3, 5, 7, or 10 min, revealing a time-dependent effect of HF acid on their topography, chemistry, and wetting. Roughness and wetting increased with longer etching time except at 10 min, when roughness increased but wetness decreased. Skewness became negative after etching and kurtosis tended to 3 with longer etching time. Highest cell adhesion was achieved after 5–7 min of etching time. Wetting and cell adhesion were reduced on the highly rough surfaces obtained after 10-min etching time. PMID:27824875

[Construction of a multiple-scale implant surface with super-hydrophilicity].

PubMed

Luo, Qiao-jie; Li, Xiao-dong; Huang, Ying; Zhao, Shi-fang

2012-05-01

To construct a multiple-scale organized implant surface with super-hydrophilicity. The SiC paper polished titanium disc was sandblasted and treated with HF/HNO₃ and HCl/H₂SO₄, then acid-etched with H₂SO₄/H₂O₂. The physicochemical properties of the surfaces were characterized by scanning electron microscope, static state contact angle and X-ray diffraction. MC3T3-E1 cells were used to evaluate the effects of the surface on the cell adhesion, proliferation and differentiation. The acid-etching process with a mixture of H₂SO₄/H₂O₂ superimposed the nano-scale structure on the micro-scale texture. The multiple-scale implant surface promoted its hydrophilicity and was more favorable to the responses of osteoprogenitor cells, characterized by increased DNA content, enhanced ALP activity and promoted OC production. A multiple-scale implant surface with super-hydrophilicity has been constructed in this study, which facilitates cell proliferation and adhesion.

Effects of topographical and mechanical property alterations induced by oxygen plasma modification on stem cell behavior.

PubMed

Yang, Yong; Kulangara, Karina; Lam, Ruby T S; Dharmawan, Rena; Leong, Kam W

2012-10-23

Polymeric substrates intended for cell culture and tissue engineering are often surface-modified to facilitate cell attachment of most anchorage-dependent cell types. The modification alters the surface chemistry and possibly topography. However, scant attention has been paid to other surface property alterations. In studying oxygen plasma treatment of polydimethylsiloxane (PDMS), we show that oxygen plasma treatment alters the surface chemistry and, consequently, the topography and elasticity of PDMS at the nanoscale level. The elasticity factor has the predominant effect, compared with the chemical and topographical factors, on cell adhesions of human mesenchymal stem cells (hMSCs). The enhanced focal adhesions favor cell spreading and osteogenesis of hMSCs. Given the prevalent use of PDMS in biomedical device construction and cell culture experiments, this study highlights the importance of understanding how oxygen plasma treatment would impact subsequent cell-substrate interactions. It helps explain inconsistency in the literature and guides preparation of PDMS-based biomedical devices in the future.

Graphene Quantum Dot Layers with Energy-Down-Shift Effect on Crystalline-Silicon Solar Cells.

PubMed

Lee, Kyung D; Park, Myung J; Kim, Do-Yeon; Kim, Soo M; Kang, Byungjun; Kim, Seongtak; Kim, Hyunho; Lee, Hae-Seok; Kang, Yoonmook; Yoon, Sam S; Hong, Byung H; Kim, Donghwan

2015-09-02

Graphene quantum dot (GQD) layers were deposited as an energy-down-shift layer on crystalline-silicon solar cell surfaces by kinetic spraying of GQD suspensions. A supersonic air jet was used to accelerate the GQDs onto the surfaces. Here, we report the coating results on a silicon substrate and the GQDs' application as an energy-down-shift layer in crystalline-silicon solar cells, which enhanced the power conversion efficiency (PCE). GQD layers deposited at nozzle scan speeds of 40, 30, 20, and 10 mm/s were evaluated after they were used to fabricate crystalline-silicon solar cells; the results indicate that GQDs play an important role in increasing the optical absorptivity of the cells. The short-circuit current density was enhanced by about 2.94% (0.9 mA/cm(2)) at 30 mm/s. Compared to a reference device without a GQD energy-down-shift layer, the PCE of p-type silicon solar cells was improved by 2.7% (0.4 percentage points).

Influence of various superhydrophilic treatments of titanium on the initial attachment, proliferation, and differentiation of osteoblast-like cells.

PubMed

Yamamura, Keisuke; Miura, Tadashi; Kou, I; Muramatsu, Takashi; Furusawa, Masahiro; Yoshinari, Masao

2015-01-01

The purpose of this study was to investigate the influence of superhydrophilic treatments of titanium on the behavior of osteoblastlike cells. Superhydrophilic specimens were prepared with sandblast and acid-etching (DW), oxygen plasma (Plasma) and ultraviolet light (UV), and were stored in distilled water for 3 days immediately after these treatments. Specimens stored in air for 3 weeks were used as a control Air group. Initial cell attachment, proliferation, alkaline phosphatase activity, and osteocalcin secretion of mouse osteoblast-like cells MC3T3-E1 were enhanced more on superhydrophilic groups than were Air specimens. On confocal laser scanning microscope images of cell morphology, the expression of actin filaments was observed on the superhydrophilic groups, whereas relatively little actin filament expression was seen on the Air surfaces on all culture periods. These results indicate that DW, Plasma, or UV treatment has potential for the creation and maintenance of superhydrophilic surfaces and the enhancement of the initial attachment, proliferation, and differentiation of osteoblast-like cells.

Effect of heparin and alendronate coating on titanium surfaces on inhibition of osteoclast and enhancement of osteoblast function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moon, Ho-Jin; Yun, Young-Pil; Han, Choong-Wan

2011-09-23

Highlights: {yields} We examine bone metabolism of engineered alendronate attached to Ti surfaces. {yields} Alendronate-immobilized Ti enhances activation of osteoblast differentiation. {yields} Alendronate-immobilized Ti inhibits osteoclast differentiation. {yields} Alendronate-immobilized Ti may be a bioactive implant with dual functions. -- Abstract: The failure of orthopedic and dental implants has been attributed mainly to loosening of the implant from host bone, which may be due to weak bonding of the implant material to bone tissue. Titanium (Ti) is used in the field of orthopedic and dental implants because of its excellent biocompatibility and outstanding mechanical properties. Therefore, in the field of materialsmore » science and tissue engineering, there has been extensive research to immobilize bioactive molecules on the surface of implant materials in order to provide the implants with improved adhesion to the host bone tissue. In this study, chemically active functional groups were introduced on the surface of Ti by a grafting reaction with heparin and then the Ti was functionalized by immobilizing alendronate onto the heparin-grafted surface. In the MC3T3-E1 cell osteogenic differentiation study, the alendronate-immobilized Ti substrates significantly enhanced alkaline phosphatase activity (ALP) and calcium content. Additionally, nuclear factor kappa B ligand (RANKL)-induced osteoclast differentiation of RAW264.7 cells was inhibited with the alendronate-immobilized Ti as confirmed by TRAP analysis. Real time PCR analysis showed that mRNA expressions of osteocalcin and osteopontin, which are markers for osteogenesis, were upregulated in MC3T3-E1 cells cultured on alendronate-immobilized Ti. The mRNA expressions of TRAP and Cathepsin K, markers for osteoclastogenesis, in RAW264.7 cells cultured on alendronate-immobilized Ti were down-regulated. Our study suggests that alendronate-immobilized Ti may be a bioactive implant with dual functions to enhance osteoblast differentiation and to inhibit osteoclast differentiation simultaneously.« less

The role of surface charge density in cationic liposome-promoted dendritic cell maturation and vaccine-induced immune responses

NASA Astrophysics Data System (ADS)

Ma, Yifan; Zhuang, Yan; Xie, Xiaofang; Wang, Ce; Wang, Fei; Zhou, Dongmei; Zeng, Jianqiang; Cai, Lintao

2011-05-01

Cationic liposomes have emerged as a novel adjuvant and antigen delivery system to enhance vaccine efficacy. However, the role of surface charge density in cationic liposome-regulated immune responses has not yet been elucidated. In the present study, we prepared a series of DOTAP/DOPC cationic liposomes with different surface densities by incorporating varying amounts of DOPC (a neutral lipid) into DOTAP (a cationic lipid). The results showed that DOTAP/DOPC cationic liposome-regulated immune responses relied on the surface charge density, and might occur through ROS signaling. The liposomes with a relatively high charge density, such as DOTAP/DOPC 5 : 0 and 4 : 1 liposomes, potently enhanced dendritic cell maturation, ROS generaion, antigen uptake, as well as the production of OVA-specific IgG2a and IFN-γ. In contrast, low-charge liposomes, such as DOTAP/DOPC 1 : 4 liposome, failed to promote immune responses even at high concentrations, confirming that the immunoregulatory effect of cationic liposomes is mostly attributable to their surface charge density. Moreover, the DOTAP/DOPC 1 : 4 liposome suppressed anti-OVA antibody responses in vivo. Overall, maintaining an appropriate surface charge is crucial for optimizing the adjuvant effect of cationic liposomes and enhancing the efficacy of liposome-based vaccines.

Ketone isosteres of 2-N-acetamidosugars as substrates for metabolic cell surface engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hang, Howard C.; Bertozzi, Carolyn R.

2000-08-22

Novel chemical reactivity can be engendered on cell surfaces by the metabolic incorporation of unnatural sugars into cell surface glycoconjuagtes. 2-N-Acetamido sugars such as GalNAc and GlcNAc are abundant components of cell surface glycoconjugates, and hence attractive targets for metabolic cell surface engineering. Here we report (1) the synthesis of isosteric analogs bearing a ketone group in place of the N-acetamido group, and (2) evaluation of their metabolic incorporation into mammalian cell surface glycans. A ketone isostere of GalNAc was metabolized by CHO cells through the salvage pathway and delivered to O-linked glycoproteins on the cell surface. Its residence atmore » the core position of O-linked glycans is suggested by studies with a-benzyl GalNAc, an inhibitor of O-linked oligosaccharide extension. A mutant CHO cell line lacking endogenous UDP-GalNAc demonstrated enhanced metabolism of the GalNAc analog, suggesting that competition with native intermediates might limits enzymatic transformation in mammalian cells. A ketone isostere of GlcNAc could not be detected on CHO or human cell surfaces after incubation. Thus, the enzymes in the GlcNAc salvage pathway might be less permissive of unnatural substrates than those comprising the GalNAc salvage pathway. Alternatively, high levels of endogenous GlcNAc derivatives might compete with the ketone isostere and prevent its incorporation into oligosaccharides.« less

Polyethyleneimine Coating Enhances the Cellular Uptake of Mesoporous Silica Nanoparticles and Allows Safe Delivery of siRNA and DNA Constructs

PubMed Central

Xia, Tian; Kovochich, Michael; Liong, Monty; Meng, Huan; Kabehie, Sanaz; Zink, Jeffrey I.; Nel, Andre E.

2014-01-01

Surface-functionalized mesoporous silica nanoparticles (MSNP) can be used as an efficient and safe carrier for bioactive molecules. In order to make the MSNP a more efficient delivery system, we modified the surface of the particles by a functional group that enhances cellular uptake and allows nucleic acid delivery in addition to traditional drug delivery. Non-covalent attachment of polyethyleneimine (PEI) polymers to the surface not only increases MSNP cellular uptake, but also generates a cationic surface to which DNA and siRNA constructs could be attached. While efficient for intracellular delivery of these nucleic acids, the 25 KD PEI polymer unfortunately changes the safety profile of the MSNP that is otherwise very safe. By experimenting with several different polymer molecular weights, it was possible to retain high cellular uptake and transfection efficiency while reducing or even eliminating cationic MSNP cytotoxicity. The particles coated with the 10 KD PEI polymer was particularly efficient for transducing HEPA-1 cells with a siRNA construct that was capable of knocking down GFP expression. Similarly, transfection of a GFP plasmid induced effective expression of the fluorescent protein in > 70% cells in the population. These outcomes were quantitatively assessed by confocal microscopy and flow cytometry. We also demonstrated that the enhanced cellular uptake of the non-toxic cationic MSNP enhance the delivery of the hydrophobic anticancer drug, paclitaxel, to pancreatic cancer cells. In summary, we demonstrate that by a careful selection of PEI size, it is possible to construct cationic MSNP that are capable of nucleotide and enhanced drug delivery with minimal or no cytotoxicity. This novel use of a cationic MSNP extends its therapeutic use potential. PMID:19739605

The influence of surface properties of plasma-etched polydimethylsiloxane (PDMS) on cell growth and morphology.

PubMed

Pennisi, Cristian P; Zachar, Vladimir; Gurevich, Leonid; Patriciu, Andrei; Struijk, Johannes J

2010-01-01

Polydimethylsiloxane (PDMS) or silicone rubber is a widely used implant material. Approaches to promote tissue integration to PDMS are desirable to avoid clinical problems associated with sliding and friction between tissue and implant. Plasma-etching is a useful way to control cell behavior on PDMS without additional coatings. In this work, different plasma processing conditions were used to modify the surface properties of PDMS substrates. Surface nanotopography and wettability were measured to study their effect on in vitro growth and morphology of fibroblasts. While fluorinated plasma treatments produced nanorough hydrophobic and superhydrophobic surfaces that had negative or little influences on cellular behavior, water vapor/oxygen plasma produced smooth hydrophillic surfaces that enhanced cell growth.

Influence of diligent disintegration on anaerobic biomass and performance of microbial fuel cell.

PubMed

Divyalakshmi, Palanisamy; Murugan, Devaraj; Rai, Chockalingam Lajapathi

2017-12-01

To enhance the performance of microbial fuel cells (MFC) by increasing the surface area of cathode and diligent mechanical disintegration of anaerobic biomass. Tannery effluent and anaerobic biomass were used. The increase in surface area of the cathode resulted in 78% COD removal, with the potential, current density, power density and coulombic efficiency of 675 mV, 147 mA m -2 , 33 mW m -2 and 3.5%, respectively. The work coupled with increased surface area of the cathode with diligent mechanical disintegration of the biomass, led to a further increase in COD removal of 82% with the potential, current density, power density and coulombic efficiency of 748 mV, 229 mA m -2 , 78 mW m -2 and 6% respectively. Mechanical disintegration of the biomass along with increased surface area of cathode enhances power generation in vertical MFC reactors using tannery effluent as fuel.

Development of Raman Spectroscopy as a Clinical Diagnostic Tool

NASA Astrophysics Data System (ADS)

Borel, Santa

Raman spectroscopy is the collection of inelastically scattered light in which the spectra contain biochemical information of the probed cells or tissue. This work presents both targeted and untargeted ways that the technique can be exploited in biological samples. First, surface enhanced Raman scattering (SERS) gold nanoparticles conjugated to targeting antibodies were shown to be successful for multiplexed detection of overexpressed surface antigens in lung cancer cell lines. Further work will need to optimize the conjugation technique to preserve the strong binding affinity of the antibodies. Second, untargeted Raman microspectroscopy combined with multivariate statistical analysis was able to successfully differentiate mouse ovarian surface epithelial (MOSE) cells and spontaneously transformed ovarian surface epithelial (STOSE) cells with high accuracy. The differences between the two groups were associated with increased nucleic acid content in the STOSE cells. This shows potential for single cell detection of ovarian cancer.

Insulin promotes cell migration by regulating PSA-NCAM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monzo, Hector J.; Coppieters, Natacha; Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland

Cellular interactions with the extracellular environment are modulated by cell surface polysialic acid (PSA) carried by the neural cell adhesion molecule (NCAM). PSA-NCAM is involved in cellular processes such as differentiation, plasticity, and migration, and is elevated in Alzheimer's disease as well as in metastatic tumour cells. Our previous work demonstrated that insulin enhances the abundance of cell surface PSA by inhibiting PSA-NCAM endocytosis. In the present study we have identified a mechanism for insulin-dependent inhibition of PSA-NCAM turnover affecting cell migration. Insulin enhanced the phosphorylation of the focal adhesion kinase leading to dissociation of αv-integrin/PSA-NCAM clusters, and promoted cellmore » migration. Our results show that αv-integrin plays a key role in the PSA-NCAM turnover process. αv-integrin knockdown stopped PSA-NCAM from being endocytosed, and αv-integrin/PSA-NCAM clusters co-labelled intracellularly with Rab5, altogether indicating a role for αv-integrin as a carrier for PSA-NCAM during internalisation. Furthermore, inhibition of p-FAK caused dissociation of αv-integrin/PSA-NCAM clusters and counteracted the insulin-induced accumulation of PSA at the cell surface and cell migration was impaired. Our data reveal a functional association between the insulin/p-FAK-dependent regulation of PSA-NCAM turnover and cell migration through the extracellular matrix. Most importantly, they identify a novel mechanism for insulin-stimulated cell migration. - Highlights: • Insulin modulates PSA-NCAM turnover through upregulation of p-FAK. • P-FAK modulates αv-integrin/PSA-NCAM clustering. • αv-integrin acts as a carrier for PSA-NCAM endocytosis. • Cell migration is promoted by cell surface PSA. • Insulin promotes PSA-dependent migration in vitro.« less

Microfluidic Channels on Nanopatterned Substrates: Monitoring Protein Binding to Lipid Bilayers with Surface-Enhanced Raman Spectroscopy

PubMed Central

Banerjee, Amrita; Perez-Castillejos, R.; Hahn, D.; Smirnov, Alex I.; Grebel, H.

2013-01-01

We used Surface Enhanced Raman Spectroscopy (SERS) to detect binding events between streptavidin and biotinylated lipid bilayers. The binding events took place at the surface between microfluidic channels and anodized aluminum oxide (AAO) with the latter serving as substrates. The bilayers were incorporated in the substrate pores. It was revealed that non-bound molecules were easily washed away and that large suspended cells (Salmonella enterica) are less likely to interfere with the monitoring process: when focusing to the lower surface of the channel, one may resolve mostly the bound molecules. PMID:24932024

Micro-fluidic channels on nanopatterned substrates: Monitoring protein binding to lipid bilayers with surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Banerjee, Amrita; Perez-Castillejos, R.; Hahn, D.; Smirnov, Alex I.; Grebel, H.

2010-04-01

We used surface-enhanced Raman spectroscopy (SERS) to detect binding events between streptavidin and biotinylated lipid bilayers. The binding events took place at the surface between micro-fluidic channels and anodized aluminum oxide (AAO) with the latter serving as substrates. The bilayers were incorporated in the substrate pores. It was revealed that non-bound molecules were easily washed away and that large suspended cells ( Salmonella enterica) are less likely to interfere with the monitoring process: when focusing to the lower surface of the channel, one may resolve mostly the bound molecules.

Enhanced light absorption of silicon solar cells with dielectric nanostructured back reflector

NASA Astrophysics Data System (ADS)

Ren, Rui; Zhong, Zheng

2018-06-01

This paper investigates the light absorption property of nanostructured dielectric reflectors in silicon thin film solar cells using numerical simulation. Flat thin film solar cell with ZnO nanostructured back reflector can produce comparable photocurrent to the control model with Ag nanostructured back reflector. Furthermore, when it is integrated with nano-pillar surface decoration, a photocurrent density of 29.5 mA/cm2 can be achieved, demonstrating a photocurrent enhancement of 5% as compared to the model with Ag nanostructured back reflector.

Conatumumab (AMG 655) coated nanoparticles for targeted pro-apoptotic drug delivery.

PubMed

Fay, Francois; McLaughlin, Kirsty M; Small, Donna M; Fennell, Dean A; Johnston, Patrick G; Longley, Daniel B; Scott, Christopher J

2011-11-01

Colloidal nanoparticle drug delivery systems have attracted much interest for their ability to enable effective formulation and delivery of therapeutic agents. The selective delivery of these nanoparticles to the disease site can be enhanced by coating the surface of the nanoparticles with targeting moieties, such as antibodies. In this current work, we demonstrate that antibodies on the surface of the particles can also elicit key biological effects. Specifically, we demonstrate the induction of apoptosis in colorectal HCT116 cancer cells using PLGA nanoparticles coated with Conatumumab (AMG 655) death receptor 5-specific antibodies (DR5-NP). We show that DR5-NP preferentially target DR5-expressing cells and present a sufficient density of antibody paratopes to induce apoptosis via DR5, unlike free AMG 655 or non-targeted control nanoparticles. We also demonstrate that DR5-targeted nanoparticles encapsulating the cytotoxic drug camptothecin are effectively targeted to the tumour cells, thereby producing enhanced cytotoxic effects through simultaneous drug delivery and apoptosis induction. These results demonstrate that antibodies on nanoparticulate surfaces can be exploited for dual modes of action to enhance the therapeutic utility of the modality. Copyright © 2011 Elsevier Ltd. All rights reserved.

Cell Surface Expression of Bacterial Esterase A by Saccharomyces cerevisiae and Its Enhancement by Constitutive Activation of the Cellular Unfolded Protein Response▿ †

PubMed Central

Breinig, Frank; Diehl, Björn; Rau, Sabrina; Zimmer, Christian; Schwab, Helmut; Schmitt, Manfred J.

2006-01-01

Yeast cell surface display is a powerful tool for expression and immobilization of biocatalytically active proteins on a unicellular eukaryote. Here bacterial carboxylesterase EstA from Burkholderia gladioli was covalently anchored into the cell wall of Saccharomyces cerevisiae by in-frame fusion to the endogenous yeast proteins Kre1p, Cwp2p, and Flo1p. When p-nitrophenyl acetate was used as a substrate, the esterase specific activities of yeast expressing the protein fusions were 103 mU mg−1 protein for Kre1/EstA/Cwp2p and 72 mU mg−1 protein for Kre1/EstA/Flo1p. In vivo cell wall targeting was confirmed by esterase solubilization after laminarinase treatment and immunofluorescence microscopy. EstA expression resulted in cell wall-associated esterase activities of 2.72 U mg−1 protein for Kre1/EstA/Cwp2p and 1.27 U mg−1 protein for Kre1/EstA/Flo1p. Furthermore, esterase display on the yeast cell surface enabled the cells to effectively grow on the esterase-dependent carbon source glycerol triacetate (Triacetin). In the case of Kre1/EstA/Flo1p, in vivo maturation within the yeast secretory pathway and final incorporation into the wall were further enhanced when there was constitutive activation of the unfolded protein response pathway. Our results demonstrate that esterase cell surface display in yeast, which, as shown here, is remarkably more effective than EstA surface display in Escherichia coli, can be further optimized by activating the protein folding machinery in the eukaryotic secretion pathway. PMID:16980424

Cell surface expression of bacterial esterase A by Saccharomyces cerevisiae and its enhancement by constitutive activation of the cellular unfolded protein response.

PubMed

Breinig, Frank; Diehl, Björn; Rau, Sabrina; Zimmer, Christian; Schwab, Helmut; Schmitt, Manfred J

2006-11-01

Yeast cell surface display is a powerful tool for expression and immobilization of biocatalytically active proteins on a unicellular eukaryote. Here bacterial carboxylesterase EstA from Burkholderia gladioli was covalently anchored into the cell wall of Saccharomyces cerevisiae by in-frame fusion to the endogenous yeast proteins Kre1p, Cwp2p, and Flo1p. When p-nitrophenyl acetate was used as a substrate, the esterase specific activities of yeast expressing the protein fusions were 103 mU mg(-1) protein for Kre1/EstA/Cwp2p and 72 mU mg(-1) protein for Kre1/EstA/Flo1p. In vivo cell wall targeting was confirmed by esterase solubilization after laminarinase treatment and immunofluorescence microscopy. EstA expression resulted in cell wall-associated esterase activities of 2.72 U mg(-1) protein for Kre1/EstA/Cwp2p and 1.27 U mg(-1) protein for Kre1/EstA/Flo1p. Furthermore, esterase display on the yeast cell surface enabled the cells to effectively grow on the esterase-dependent carbon source glycerol triacetate (Triacetin). In the case of Kre1/EstA/Flo1p, in vivo maturation within the yeast secretory pathway and final incorporation into the wall were further enhanced when there was constitutive activation of the unfolded protein response pathway. Our results demonstrate that esterase cell surface display in yeast, which, as shown here, is remarkably more effective than EstA surface display in Escherichia coli, can be further optimized by activating the protein folding machinery in the eukaryotic secretion pathway.

The Role of PD-1 Ligand in Immune Evasion by Breast Cancer

DTIC Science & Technology

2005-05-01

with anti-CD11c-PE and either anti-PD-L1-FITC or anti-PD-L2-FITC and an- alyzed by flow cytometry . 1260 BLOCKADE OF PD-L ON DC ENHANCES T CELL... surface staining. . In order to accomplish these epitope blocking studies, we made 300.19 and CHO cells transfected with PD-L1 or PD-L2. For anti...Key Research Accomplishments 1. PD-L1 but not PD-L2 is highly expressed on the cell surface of breast cancer cells but not on normal breast

Reaction temperature sensing (RTS)-based control for Li-ion battery safety

PubMed Central

Zhang, Guangsheng; Cao, Lei; Ge, Shanhai; Wang, Chao-Yang; Shaffer, Christian E.; Rahn, Christopher D.

2015-01-01

We report reaction temperature sensing (RTS)-based control to fundamentally enhance Li-ion battery safety. RTS placed at the electrochemical interface inside a Li-ion cell is shown to detect temperature rise much faster and more accurately than external measurement of cell surface temperature. We demonstrate, for the first time, that RTS-based control shuts down a dangerous short-circuit event 3 times earlier than surface temperature- based control and prevents cell overheating by 50 °C and the resultant cell damage. PMID:26658957

Front surface passivation of silicon solar cells with antireflection coating

NASA Technical Reports Server (NTRS)

Crotty, G.; Daud, T.; Kachare, R.

1987-01-01

It is demonstrated that the deposition and postdeposition sintering of an antireflection (AR) coating in hydrogen acts to passivate silicon solar cells. Cells with and without an SiO2 passivating layer, coated with a TiO(x)/Al2O3 AR coating, showed comparable enhancements in short-wavelength spectral response and in open-circuit voltage Voc after sintering at 400 C for 5 min in a hydrogen ambient. The improvement in Voc of cells without SiO2 is attributed to front-surface passivation by the AR coating during processing.

Cell-secreted flavins bound to membrane cytochromes dictate electron transfer reactions to surfaces with diverse charge and pH.

PubMed

Okamoto, Akihiro; Kalathil, Shafeer; Deng, Xiao; Hashimoto, Kazuhito; Nakamura, Ryuhei; Nealson, Kenneth H

2014-07-11

The variety of solid surfaces to and from which microbes can deliver electrons by extracellular electron transport (EET) processes via outer-membrane c-type cytochromes (OM c-Cyts) expands the importance of microbial respiration in natural environments and industrial applications. Here, we demonstrate that the bifurcated EET pathway of OM c-Cyts sustains the diversity of the EET surface in Shewanella oneidensis MR-1 via specific binding with cell-secreted flavin mononucleotide (FMN) and riboflavin (RF). Microbial current production and whole-cell differential pulse voltammetry revealed that RF and FMN enhance EET as bound cofactors in a similar manner. Conversely, FMN and RF were clearly differentiated in the EET enhancement by gene-deletion of OM c-Cyts and the dependency of the electrode potential and pH. These results indicate that RF and FMN have specific binding sites in OM c-Cyts and highlight the potential roles of these flavin-cytochrome complexes in controlling the rate of electron transfer to surfaces with diverse potential and pH.

PCR-free Quantification of Multiple Splice Variants in Cancer Gene by Surface Enhanced Raman Spectroscopy

PubMed Central

Sun, Lan; Irudayaraj, Joseph

2009-01-01

We demonstrate a surface enhanced Raman spectroscopy (SERS) based array platform to monitor gene expression in cancer cells in a multiplex and quantitative format without amplification steps. A strategy comprising of DNA/RNA hybridization, S1 nuclease digestion, and alkaline hydrolysis was adopted to obtain DNA targets specific to two splice junction variants Δ(9, 10) and Δ(5) of the breast cancer susceptibility gene 1 (BRCA1) from MCF-7 and MDA-MB-231 breast cancer cell lines. These two targets were identified simultaneously and their absolute quantities were estimated by a SERS strategy utilizing the inherent plasmon-phonon Raman mode of gold nanoparticle probes as a self-referencing standard to correct for variability in surface enhancement. Results were then validated by reverse transcription PCR (RT-PCR). Our proposed methodology could be expanded to a higher level of multiplexing for quantitative gene expression analysis of any gene without any amplification steps. PMID:19780515

Impact of silica nanoparticle surface chemistry on protein corona formation and consequential interactions with biological cells.

PubMed

Kurtz-Chalot, Andréa; Villiers, Christian; Pourchez, Jérémie; Boudard, Delphine; Martini, Matteo; Marche, Patrice N; Cottier, Michèle; Forest, Valérie

2017-06-01

Nanoparticles (NP) physico-chemical features greatly influence NP/cell interactions. NP surface functionalization is often used to improve NP biocompatibility or to enhance cellular uptake. But in biological media, the formation of a protein corona adds a level of complexity. The aim of this study was to investigate in vitro the influence of NP surface functionalization on their cellular uptake and the biological response induced. 50nm fluorescent silica NP were functionalized either with amine or carboxylic groups, in presence or in absence of polyethylene glycol (PEG). NP were incubated with macrophages, cellular uptake and cellular response were assessed in terms of cytotoxicity, pro-inflammatory response and oxidative stress. The NP protein corona was also characterized by protein mass spectroscopy. Results showed that NP uptake was enhanced in absence of PEG, while NP adsorption at the cell membrane was fostered by an initial positively charged NP surface. NP toxicity was not correlated with NP uptake. NP surface functionalization also influenced the formation of the protein corona as the profile of protein binding differed among the NP types. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhanced electrochemical sensing of leukemia cells using drug/lipid co-immobilized on the conducting polymer layer.

PubMed

Gurudatt, N G; Naveen, M Halappa; Ban, Changill; Shim, Yoon-Bo

2016-12-15

Electrochemical biosensors using five anticancer drug and lipid molecules attached on the conducting polymer layer to obtain the orientation of drug molecules toward cancer cells, were evaluated as sensing materials and their performances were compared. Conjugation of the drug molecules with a lipid, phosphatidylcholine (PC) has enhanced the sensitivity towards leukemia cells and differentiates cancer cells from normal cells. The composition of each layer of sensor probe was confirmed by electrochemical and surface characterization experiments. Both impedance spectroscopy and voltammetry show the enhanced interaction of leukemia cells using the drug/lipid modified sensor probe. As the number of leukemia cells increased, the charge transfer resistance (Rct) in impedance spectra increased and the amine oxidation peak current of drug molecules in voltammograms decreased at around 0.7-1.0V. Of test drug molecules, raltitrexed (Rtx) showed the best performance for the cancer cells detection. Cancer and normal cell lines from different origins were examined to evaluate the degree of expression of folate receptors (FR) on cells surface, where cervical HeLa cell line was found to be shown the highest expression of the receptor. Impedance and chronoamperometric experiments for leukemia cell line (Jurkat E6-1) showed linear dynamic ranges of 1.0×10(3)-2.5×10(5) cells/mL and 1.0×10(3)-8.0×10(3) cells/mL with detection limits of 68±5 cells/mL and 21±3 cells/mL, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Rapid, controllable growth of silver nanostructured surface-enhanced Raman scattering substrates for red blood cell detection

NASA Astrophysics Data System (ADS)

Zhang, Shu; Tian, Xueli; Yin, Jun; Liu, Yu; Dong, Zhanmin; Sun, Jia-Lin; Ma, Wanyun

2016-04-01

Silver nanostructured films suitable for use as surface-enhanced Raman scattering (SERS) substrates are prepared in just 2 hours by the solid-state ionics method. By changing the intensity of the external direct current, we can readily control the surface morphology and growth rate of the silver nanostructured films. A detailed investigation of the surface enhancement of the silver nanostructured films using Rhodamine 6G (R6G) as a molecular probe revealed that the enhancement factor of the films was up to 1011. We used the silver nanostructured films as substrates in SERS detection of human red blood cells (RBCs). The SERS spectra of RBCs on the silver nanostructured film could be clearly detected at a laser power of just 0.05 mW. Comparison of the SERS spectra of RBCs obtained from younger and older donors showed that the SERS spectra depended on donor age. A greater proportion of the haemoglobin in the RBCs of older donors was in the deoxygenated state than that of the younger donors. This implies that haemoglobin of older people has lower oxygen-carrying capacity than that of younger people. Overall, the fabricated silver substrates show promise in biomedical SERS spectral detection.

Current collection from the space plasma through defects in high voltage solar array insulation. Ph.D. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Stillwell, R. P.

1983-01-01

For spacecraft operation in the near Earth environment, solar cell arrays constitute the major source of reliable long term power. Optimization of mass and power efficiency results in a general requirement for high voltage solar arrays. The space plasma environment, though, can result in large currents being collected by exposed solar cells. The solution of a protective covering of transparent insulation is not a complete solution, inasmuch as defects in the insulation result in anomalously large currents being collected through the defects. Tests simulating the electron collection from small defects in an insulation have shown that there are two major collection modes. The first mode involves current enhancement by means of a surface phenomenon involving the surrounding insulator. In the second mode the current collection is enhanced by vaporization and ionization of the insulators materials, in addition to the surface enhancement of the first mode. A model for the electron collection is the surface enhanced collection mode was developed. The model relates the secondary electron emission yield to the electron collection. It correctly predicts the qualitative effects of hole size, sample temperature and roughening of sample surface. The theory was also shown to predict electron collection within a factor of two for the polymers teflon and polyimide.

Osteogenic potential of in situ TiO2 nanowire surfaces formed by thermal oxidation of titanium alloy substrate

NASA Astrophysics Data System (ADS)

Tan, A. W.; Ismail, R.; Chua, K. H.; Ahmad, R.; Akbar, S. A.; Pingguan-Murphy, B.

2014-11-01

Titanium dioxide (TiO2) nanowire surface structures were fabricated in situ by a thermal oxidation process, and their ability to enhance the osteogenic potential of primary osteoblasts was investigated. Human osteoblasts were isolated from nasal bone and cultured on a TiO2 nanowires coated substrate to assess its in vitro cellular interaction. Bare featureless Ti-6Al-4V substrate was used as a control surface. Initial cell adhesion, cell proliferation, cell differentiation, cell mineralization, and osteogenic related gene expression were examined on the TiO2 nanowire surfaces as compared to the control surfaces after 2 weeks of culturing. Cell adhesion and cell proliferation were assayed by field emission scanning electron microscope (FESEM) and Alamar Blue reduction assay, respectively. The nanowire surfaces promoted better cell adhesion and spreading than the control surface, as well as leading to higher cell proliferation. Our results showed that osteoblasts grown onto the TiO2 nanowire surfaces displayed significantly higher production levels of alkaline phosphatase (ALP), extracellular (ECM) mineralization and genes expression of runt-related transcription factor (Runx2), bone sialoprotein (BSP), ostoepontin (OPN) and osteocalcin (OCN) compared to the control surfaces. This suggests the potential use of such surface modification on Ti-6Al-4V substrates as a promising means to improve the osteointegration of titanium based implants.

Influence of physicochemical properties of laser-modified polystyrene on bovine serum albumin adsorption and rat C6 glioma cell behavior.

PubMed

Wang, Xuefeng; Ohlin, C André; Lu, Qinghua; Hu, Jun

2006-09-15

Biomaterial surface modification is an efficient way of improving cell-material interactions. In this study, sub-micrometer laser-induced periodic surface structures (LIPSS) were produced on polystyrene by laser irradiation. FT-IR analysis confirmed that this treatment also led to surface oxidation and anisotropic orientation of the produced carbonyl groups. As a consequence, the surface energy of the laser-treated polystyrene was 1.45 times that of the untreated polystyrene, as measured by contact-angle goniometry. Protein adsorption and rat C6 glioma cell behavior on the two substrates were investigated, showing that the changed physicochemical properties of laser-modified polystyrene surface led to an increase in the quantity of adsorbed bovine serum albumin and significantly affected the behavior of rat C6 glioma cells. In the early stages of cell spreading, cells explored their microenvironment using filopodium as the main sensor. Moreover, cells actively aligned themselves along the direction of LIPSS gradually and cell attachment and proliferation were significantly enhanced. 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006.

In-Situ Probing Plasmonic Energy Transfer in Cu(In, Ga)Se2 Solar Cells by Ultrabroadband Femtosecond Pump-Probe Spectroscopy.

PubMed

Chen, Shih-Chen; Wu, Kaung-Hsiung; Li, Jia-Xing; Yabushita, Atsushi; Tang, Shih-Han; Luo, Chih Wei; Juang, Jenh-Yih; Kuo, Hao-Chung; Chueh, Yu-Lun

2015-12-18

In this work, we demonstrated a viable experimental scheme for in-situ probing the effects of Au nanoparticles (NPs) incorporation on plasmonic energy transfer in Cu(In, Ga)Se2 (CIGS) solar cells by elaborately analyzing the lifetimes and zero moment for hot carrier relaxation with ultrabroadband femtosecond pump-probe spectroscopy. The signals of enhanced photobleach (PB) and waned photoinduced absorption (PIA) attributable to surface plasmon resonance (SPR) of Au NPs were in-situ probed in transient differential absorption spectra. The results suggested that substantial carriers can be excited from ground state to lower excitation energy levels, which can reach thermalization much faster with the existence of SPR. Thus, direct electron transfer (DET) could be implemented to enhance the photocurrent of CIGS solar cells. Furthermore, based on the extracted hot carrier lifetimes, it was confirmed that the improved electrical transport might have been resulted primarily from the reduction in the surface recombination of photoinduced carriers through enhanced local electromagnetic field (LEMF). Finally, theoretical calculation for resonant energy transfer (RET)-induced enhancement in the probability of exciting electron-hole pairs was conducted and the results agreed well with the enhanced PB peak of transient differential absorption in plasmonic CIGS film. These results indicate that plasmonic energy transfer is a viable approach to boost high-efficiency CIGS solar cells.

Morphological and proteomic analysis of biofilms from the Antarctic archaeon, Halorubrum lacusprofundi.

PubMed

Liao, Y; Williams, T J; Ye, J; Charlesworth, J; Burns, B P; Poljak, A; Raftery, M J; Cavicchioli, R

2016-11-22

Biofilms enhance rates of gene exchange, access to specific nutrients, and cell survivability. Haloarchaea in Deep Lake, Antarctica, are characterized by high rates of intergenera gene exchange, metabolic specialization that promotes niche adaptation, and are exposed to high levels of UV-irradiation in summer. Halorubrum lacusprofundi from Deep Lake has previously been reported to form biofilms. Here we defined growth conditions that promoted the formation of biofilms and used microscopy and enzymatic digestion of extracellular material to characterize biofilm structures. Extracellular DNA was found to be critical to biofilms, with cell surface proteins and quorum sensing also implicated in biofilm formation. Quantitative proteomics was used to define pathways and cellular processes involved in forming biofilms; these included enhanced purine synthesis and specific cell surface proteins involved in DNA metabolism; post-translational modification of cell surface proteins; specific pathways of carbon metabolism involving acetyl-CoA; and specific responses to oxidative stress. The study provides a new level of understanding about the molecular mechanisms involved in biofilm formation of this important member of the Deep Lake community.

Morphological and proteomic analysis of biofilms from the Antarctic archaeon, Halorubrum lacusprofundi

PubMed Central

Liao, Y.; Williams, T. J.; Ye, J.; Charlesworth, J.; Burns, B. P.; Poljak, A.; Raftery, M. J.; Cavicchioli, R.

2016-01-01

Biofilms enhance rates of gene exchange, access to specific nutrients, and cell survivability. Haloarchaea in Deep Lake, Antarctica, are characterized by high rates of intergenera gene exchange, metabolic specialization that promotes niche adaptation, and are exposed to high levels of UV-irradiation in summer. Halorubrum lacusprofundi from Deep Lake has previously been reported to form biofilms. Here we defined growth conditions that promoted the formation of biofilms and used microscopy and enzymatic digestion of extracellular material to characterize biofilm structures. Extracellular DNA was found to be critical to biofilms, with cell surface proteins and quorum sensing also implicated in biofilm formation. Quantitative proteomics was used to define pathways and cellular processes involved in forming biofilms; these included enhanced purine synthesis and specific cell surface proteins involved in DNA metabolism; post-translational modification of cell surface proteins; specific pathways of carbon metabolism involving acetyl-CoA; and specific responses to oxidative stress. The study provides a new level of understanding about the molecular mechanisms involved in biofilm formation of this important member of the Deep Lake community. PMID:27874045

Surface plasmon enhanced cell microscopy with blocked random spatial activation

NASA Astrophysics Data System (ADS)

Son, Taehwang; Oh, Youngjin; Lee, Wonju; Yang, Heejin; Kim, Donghyun

2016-03-01

We present surface plasmon enhanced fluorescence microscopy with random spatial sampling using patterned block of silver nanoislands. Rigorous coupled wave analysis was performed to confirm near-field localization on nanoislands. Random nanoislands were fabricated in silver by temperature annealing. By analyzing random near-field distribution, average size of localized fields was found to be on the order of 135 nm. Randomly localized near-fields were used to spatially sample F-actin of J774 cells (mouse macrophage cell-line). Image deconvolution algorithm based on linear imaging theory was established for stochastic estimation of fluorescent molecular distribution. The alignment between near-field distribution and raw image was performed by the patterned block. The achieved resolution is dependent upon factors including the size of localized fields and estimated to be 100-150 nm.

Investigation of back surface fields effect on bifacial solar cells

NASA Astrophysics Data System (ADS)

Sepeai, Suhaila; Sulaiman, M. Y.; Sopian, Kamaruzzaman; Zaidi, Saleem H.

2012-11-01

A bifacial solar cell, in contrast with a conventional monofacial solar cell, produces photo-generated current from both front and back sides. Bifacial solar cell is an attractive candidate for enhancing photovoltaic (PV) market competitiveness as well as supporting the current efforts to increase efficiency and lower material costs. This paper reports on the fabrication of bifacial solar cells using phosphorus-oxytrichloride (POCl3) emitter formation on p-type, nanotextured silicon (Si) wafer. Backside surface field was formed through Al-diffusion using conventional screen-printing process. Bifacial solar cells with a structure of n+pp+ with and without back surface field (BSF) were fabricated in which silicon nitride (SiN) anti reflection and passivation films were coated on both sides, followed by screen printing of Argentum (Ag) and Argentum/Aluminum (Ag/Al) on front and back contacts, respectively. Bifacial solar cells without BSF exhibited open circuit voltage (VOC) of 535 mV for front and 480 mV for back surface. With Al-alloyed BSF bifacial solar cells, the VOC improved to 580 mV for the front surface and 560 mV for the back surface. Simulation of bifacial solar cells using PC1D and AFORS software demonstrated good agreement with experimental results. Simulations showed that best bifacial solar cells are achieved through a combination of high lifetime wafer, low recombination back surface field, reduced contact resistance, and superior surface passivation.

Nanotextured titanium surfaces stimulate spreading, migration, and growth of rat mast cells.

PubMed

Marcatti Amarú Maximiano, William; Marino Mazucato, Vivian; Tambasco de Oliveira, Paulo; Célia Jamur, Maria; Oliver, Constance

2017-08-01

Titanium is a biomaterial widely used in dental and orthopedic implants. Since tissue-implant interactions occur at the nanoscale level, nanotextured titanium surfaces may affect cellular activity and modulate the tissue response that occurs at the tissue-implant interface. Therefore, the characterization of diverse cell types in response to titanium surfaces with nanotopography is important for the rational design of implants. Mast cells are multifunctional cells of the immune system that release a range of chemical mediators involved in the inflammatory response that occurs at the tissue-implant interface. Therefore, the aim of this study was to investigate the effects of the nanotopography of titanium surfaces on the physiology of mast cells. The results show that the nanotopography of titanium surfaces promoted the spreading of mast cells, which was accompanied by the reorganization of the cytoskeleton. Also, the nanotopography of titanium surfaces enhanced cell migration and cell growth, but did not alter the number of adherent cells in first hours of culture or affect focal adhesions and mediator release. Thus, the results show that nanotopography of titanium surfaces can affect mast cell physiology, and represents an improved strategy for the rational production of surfaces that stimulate tissue integration with the titanium implants. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2150-2161, 2017. © 2017 Wiley Periodicals, Inc.

Infinite Coordination Polymer Nano- and Micro-Particles

DTIC Science & Technology

2015-06-12

Mirkin, Tobin J. Marks, Joseph T. Hupp. SiO2 Aerogel-templated, Porous TiO2 Photoanodes for Enhanced Performances in Dye-Sensitized Solar Cells ...nano-scale ICPs and their selective surface functionalization, we examined if indeed these ICP-DNA hybrid structures could enter cells and...surface functionalization. In particular, we aimed to utilize this fundamental understanding for the realization of nano-scale ICP-biomolecule hybrids

Surface functionalization of nanobiomaterials for application in stem cell culture, tissue engineering, and regenerative medicine.

PubMed

Rana, Deepti; Ramasamy, Keerthana; Leena, Maria; Jiménez, Constanza; Campos, Javier; Ibarra, Paula; Haidar, Ziyad S; Ramalingam, Murugan

2016-05-01

Stem cell-based approaches offer great application potential in tissue engineering and regenerative medicine owing to their ability of sensing the microenvironment and respond accordingly (dynamic behavior). Recently, the combination of nanobiomaterials with stem cells has paved a great way for further exploration. Nanobiomaterials with engineered surfaces could mimic the native microenvironment to which the seeded stem cells could adhere and migrate. Surface functionalized nanobiomaterial-based scaffolds could then be used to regulate or control the cellular functions to culture stem cells and regenerate damaged tissues or organs. Therefore, controlling the interactions between nanobiomaterials and stem cells is a critical factor. However, surface functionalization or modification techniques has provided an alternative approach for tailoring the nanobiomaterials surface in accordance to the physiological surrounding of a living cells; thereby, enhancing the structural and functional properties of the engineered tissues and organs. Currently, there are a variety of methods and technologies available to modify the surface of biomaterials according to the specific cell or tissue properties to be regenerated. This review highlights the trends in surface modification techniques for nanobiomaterials and the biological relevance in stem cell-based tissue engineering and regenerative medicine. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:554-567, 2016. © 2016 American Institute of Chemical Engineers.

Sub-50-nm self-assembled nanotextures for enhanced broadband antireflection in silicon solar cells.

PubMed

Rahman, Atikur; Ashraf, Ahsan; Xin, Huolin; Tong, Xiao; Sutter, Peter; Eisaman, Matthew D; Black, Charles T

2015-01-21

Materials providing broadband light antireflection have applications as highly transparent window coatings, military camouflage, and coatings for efficiently coupling light into solar cells and out of light-emitting diodes. In this work, densely packed silicon nanotextures with feature sizes smaller than 50 nm enhance the broadband antireflection compared with that predicted by their geometry alone. A significant fraction of the nanotexture volume comprises a surface layer whose optical properties differ substantially from those of the bulk, providing the key to improved performance. The nanotexture reflectivity is quantitatively well-modelled after accounting for both its profile and changes in refractive index at the surface. We employ block copolymer self-assembly for precise and tunable nanotexture design in the range of ~10-70 nm across macroscopic solar cell areas. Implementing this efficient antireflection approach in crystalline silicon solar cells significantly betters the performance gain compared with an optimized, planar antireflection coating.

Graphene-based photovoltaic cells for near-field thermal energy conversion

PubMed Central

Messina, Riccardo; Ben-Abdallah, Philippe

2013-01-01

Thermophotovoltaic devices are energy-conversion systems generating an electric current from the thermal photons radiated by a hot body. While their efficiency is limited in far field by the Schockley-Queisser limit, in near field the heat flux transferred to a photovoltaic cell can be largely enhanced because of the contribution of evanescent photons, in particular for a source supporting a surface mode. Unfortunately, in the infrared where these systems operate, the mismatch between the surface-mode frequency and the semiconductor gap reduces drastically the potential of this technology. In this paper we propose a modified thermophotovoltaic device in which the cell is covered by a graphene sheet. By discussing the transmission coefficient and the spectral properties of the flux, we show that both the cell efficiency and the produced current can be enhanced, paving the way to promising developments for the production of electricity from waste heat. PMID:23474891

Graphene-based photovoltaic cells for near-field thermal energy conversion.

PubMed

Messina, Riccardo; Ben-Abdallah, Philippe

2013-01-01

Thermophotovoltaic devices are energy-conversion systems generating an electric current from the thermal photons radiated by a hot body. While their efficiency is limited in far field by the Schockley-Queisser limit, in near field the heat flux transferred to a photovoltaic cell can be largely enhanced because of the contribution of evanescent photons, in particular for a source supporting a surface mode. Unfortunately, in the infrared where these systems operate, the mismatch between the surface-mode frequency and the semiconductor gap reduces drastically the potential of this technology. In this paper we propose a modified thermophotovoltaic device in which the cell is covered by a graphene sheet. By discussing the transmission coefficient and the spectral properties of the flux, we show that both the cell efficiency and the produced current can be enhanced, paving the way to promising developments for the production of electricity from waste heat.

High efficiency silicon nanowire/organic hybrid solar cells with two-step surface treatment.

PubMed

Wang, Jianxiong; Wang, Hao; Prakoso, Ari Bimo; Togonal, Alienor Svietlana; Hong, Lei; Jiang, Changyun; Rusli

2015-03-14

A simple two-step surface treatment process is proposed to boost the efficiency of silicon nanowire/PEDOT:PSS hybrid solar cells. The Si nanowires (SiNWs) are first subjected to a low temperature ozone treatment to form a surface sacrificial oxide, followed by a HF etching process to partially remove the oxide. TEM investigation demonstrates that a clean SiNW surface is achieved after the treatment, in contrast to untreated SiNWs that have Ag nanoparticles left on the surface from the metal-catalyzed etching process that is used to form the SiNWs. The cleaner SiNW surface achieved and the thin layer of residual SiO2 on the SiNWs have been found to improve the performance of the hybrid solar cells. Overall, the surface recombination of the hybrid SiNW solar cells is greatly suppressed, resulting in a remarkably improved open circuit voltage of 0.58 V. The power conversion efficiency has also increased from about 10% to 12.4%. The two-step surface treatment method is promising in enhancing the photovoltaic performance of the hybrid silicon solar cells, and can also be applied to other silicon nanostructure based solar cells.

Bacterial lipopolysaccharide binding enhances virion stability and promotes environmental fitness of an enteric virus

PubMed Central

Robinson, Christopher M.; Jesudhasan, Palmy R.; Pfeiffer, Julie K.

2014-01-01

Summary Enteric viruses, including poliovirus and reovirus, encounter a vast microbial community in the mammalian gastrointestinal tract, which has been shown to promote virus replication and pathogenesis. Investigating the underlying mechanisms, we find that poliovirus binds bacterial surface polysaccharides, which enhances virion stability and cell attachment by increasing binding to the viral receptor. Additionally, we identified a poliovirus mutant, VP1-T99K, with reduced lipopolysaccharide (LPS) binding. Although T99K and WT poliovirus cell attachment, replication and pathogenesis in mice are equivalent, following peroral inoculation of mice, VP1-T99K poliovirus was unstable in feces. Consequently, the ratio of mutant virus in feces is reduced following additional cycles of infection in mice. Thus, the mutant virus incurs a fitness cost when environmental stability is a factor. These data suggest that poliovirus binds bacterial surface polysaccharides, enhancing cell attachment and environmental stability, potentially promoting transmission to a new host. PMID:24439896

Three-dimensional intracellular structure of a whole rice mesophyll cell observed with FIB-SEM.

PubMed

Oi, Takao; Enomoto, Sakiko; Nakao, Tomoyo; Arai, Shigeo; Yamane, Koji; Taniguchi, Mitsutaka

2017-07-01

Ultrathin sections of rice leaf blades observed two-dimensionally using a transmission electron microscope (TEM) show that the chlorenchyma is composed of lobed mesophyll cells, with intricate cell boundaries, and lined with chloroplasts. The lobed cell shape and chloroplast positioning are believed to enhance the area available for the gas exchange surface for photosynthesis in rice leaves. However, a cell image revealing the three-dimensional (3-D) ultrastructure of rice mesophyll cells has not been visualized. In this study, a whole rice mesophyll cell was observed using a focused ion beam scanning electron microscope (FIB-SEM), which provides many serial sections automatically, rapidly and correctly, thereby enabling 3-D cell structure reconstruction. Rice leaf blades were fixed chemically using the method for conventional TEM observation, embedded in resin and subsequently set in the FIB-SEM chamber. Specimen blocks were sectioned transversely using the FIB, and block-face images were captured using the SEM. The sectioning and imaging were repeated overnight for 200-500 slices (each 50 nm thick). The resultant large-volume image stacks ( x = 25 μm, y = 25 μm, z = 10-25 μm) contained one or two whole mesophyll cells. The 3-D models of whole mesophyll cells were reconstructed using image processing software. The reconstructed cell models were discoid shaped with several lobes around the cell periphery. The cell shape increased the surface area, and the ratio of surface area to volume was twice that of a cylinder having the same volume. The chloroplasts occupied half the cell volume and spread as sheets along the cell lobes, covering most of the inner cell surface, with adjacent chloroplasts in close contact with each other. Cellular and sub-cellular ultrastructures of a whole mesophyll cell in a rice leaf blade are demonstrated three-dimensionally using a FIB-SEM. The 3-D models and numerical information support the hypothesis that rice mesophyll cells enhance their CO 2 absorption with increased cell surface and sheet-shaped chloroplasts. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Vibrational fingerprinting of bacterial pathogens by surface enhanced Raman scattering (SERS)

NASA Astrophysics Data System (ADS)

Premasiri, W. Ranjith; Moir, D. T.; Ziegler, Lawrence D.

2005-05-01

The surface enhanced Raman scattering (SERS) spectra of vegetative whole-cell bacteria were obtained using in-situ grown gold nanoparticle cluster-covered silicon dioxide substrates excited at 785 nm. SERS spectra of Gram-negative bacteria; E. coli and S. typhimurium, and Gram-positive bacteria; B. subtilis, B. cereus, B. thuringeinsis and B. anthracis Sterne, have been observed. Raman enhancement factors of ~104-105 per cell are found for both Gram positive and Gram negative bacteria on this novel SERS substrate. The bacterial SERS spectra are species specific and exhibit greater species differentiation and reduced spectral congestion than their corresponding non-SERS (bulk) Raman spectra. Fluorescence observed in the 785 nm excited bulk Raman emission of Bacillus species is not apparent in the corresponding SERS spectra. The surface enhancement effect allows the observation of Raman spectra at the single cell level excited by low incident laser powers (< 3 mW) and short data acquisition times (~20 sec.). Comparison with previous SERS studies suggests that these SERS vibrational signatures are sensitively dependent on the specific morphology and nature of the SERS active substrate. Exposure to biological environments, such as human blood serum, has an observable effect on the bacterial SERS spectra. However, reproducible, species specific SERS vibrational fingerprints are still obtained. The potential of SERS for detection and identification of bacteria with species specificity on these gold nanoparticle coated substrates is demonstrated by these results.

Mesoporous silica nanoparticles engineered for ultrasound-induced uptake by cancer cells.

PubMed

Paris, Juan L; Manzano, Miguel; Cabañas, M Victoria; Vallet-Regí, María

2018-04-05

A novel smart hierarchical ultrasound-responsive mesoporous silica nanocarrier for cancer therapy is presented here. This dynamic nanosystem has been designed to display different surface characteristics during its journey towards tumor cells. Initially, the anticancer-loaded nanocarriers are shielded with a polyethylene glycol layer. Upon exposure to high frequency ultrasound, the polymer shell detaches from the nanoparticles, exposing a positively charged surface. This favors the internalization in human osteosarcoma cells, where the release of topotecan takes place, drastically enhancing the cytotoxic effect.

Enhancement of Power Conversion Efficiency of TiO₂-Based Dye-Sensitized Solar Cells on Various Acid Treatment.

PubMed

Sireesha, Pedaballi; Sun, Wei-Gang; Su, Chaochin; Kathirvel, Sasipriya; Lekphet, Woranan; Akula, Suri Babu; Li, Wen-Ri

2017-01-01

The surface modification of the TiO2 photoelectrode film is one of the promising ways to improve the photovoltaic performance of dye-sensitized solar cell (DSSC). In this work for the acid treatment of TiO2 powder, fluorine containing compounds such as trifluoroacetic acid was carried out to enhance the properties of photoanode. In order to investigate the effect of trifluoroacetyl group, the TiO2 nanopowders were also treated with different acids such as acetic acid, nitric acid, hydrochloric acid, and sulfuric acid and their properties were compared. The TiO2 powders treated with both acetic acid and TFA have possessed smooth surface morphologies as well as enhanced particle dispersions with reduced particle sizes. Photoelectrodes prepared for these two kinds of TiO2 powders accommodated high amounts of dye loading and exhibited excellent light transmittance (wavelength region of 400–600 nm). Electrochemical impedance spectroscopy analysis showed the smallest radius of the semicircle which indicates the enhanced rate of electron transport for the cell based photoelectrode with trifluoroacetic acid treated TiO2 powder. The solar cell from the untreated TiO2 film showed the power conversion efficiency of 8.86% and the highest efficiency of 9.51% was achieved by the cell fabricated from trifluoroacetic acid treated TiO2 film.

On Field-Effect Photovoltaics: Gate Enhancement of the Power Conversion Efficiency in a Nanotube/Silicon-Nanowire Solar Cell.

PubMed

Petterson, Maureen K; Lemaitre, Maxime G; Shen, Yu; Wadhwa, Pooja; Hou, Jie; Vasilyeva, Svetlana V; Kravchenko, Ivan I; Rinzler, Andrew G

2015-09-30

Recent years have seen a resurgence of interest in crystalline silicon Schottky junction solar cells distinguished by the use of low density of electronic states (DOS) nanocarbons (nanotubes, graphene) as the metal contacting the Si. Recently, unprecedented modulation of the power conversion efficiency in a single material system has been demonstrated in such cells by the use of electronic gating. The gate field induced Fermi level shift in the low-DOS carbon serves to enhance the junction built-in potential, while a gate field induced inversion layer at the Si surface, in regions remote from the junction, keeps the photocarriers well separated there, avoiding recombination at surface traps and defects (a key loss mechanism). Here, we extend these results into the third dimension of a vertical Si nanowire array solar cell. A single wall carbon nanotube layer engineered to contact virtually each n-Si nanowire tip extracts the minority carriers, while an ionic liquid electrolytic gate drives the nanowire body into inversion. The enhanced light absorption of the vertical forest cell, at 100 mW/cm(2) AM1.5G illumination, results in a short-circuit current density of 35 mA/cm(2) and associated power conversion efficiency of 15%. These results highlight the use of local fields as opposed to surface passivation as a means of avoiding front surface recombination. A deleterious electrochemical reaction of the silicon due to the electrolyte gating is shown to be caused by oxygen/water entrained in the ionic liquid electrolyte. While encapsulation can avoid the issue, a nonencapsulation-based approach is also implemented.

On Field-Effect Photovoltaics: Gate Enhancement of the Power Conversion Efficiency in a Nanotube/Silicon-Nanowire Solar Cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petterson, Maureen K.; Lemaitre, Maxime G.; Shen, Yu

Recent years have seen a resurgence of interest in crystalline silicon Schottky junction solar cells distinguished by the use of low density of electronic states (DOS) nanocarbons (nanotubes, graphene) as the metal contacting the Si. Recently, unprecedented modulation of the power conversion efficiency in a single material system has been demonstrated in such cells by the use of electronic gating. The gate field induced Fermi level shift in the low-DOS carbon serves to enhance the junction built-in potential, while a gate field induced inversion layer at the Si surface, in regions remote from the junction, keeps the photocarriers well separatedmore » there, avoiding recombination at surface traps and defects (a key loss mechanism). Here, we extend these results into the third dimension of a vertical Si nanowire array solar cell. A single wall carbon nanotube layer engineered to contact virtually each n-Si nanowire tip extracts the minority carriers, while an ionic liquid electrolytic gate drives the nanowire body into inversion. The enhanced light absorption of the vertical forest cell, at 100 mW/cm 2 AM1.5G illumination, results in a short-circuit current density of 35 mA/cm 2 and associated power conversion efficiency of 15%. These results highlight the use of local fields as opposed to surface passivation as a means of avoiding front surface recombination. Finally, a deleterious electrochemical reaction of the silicon due to the electrolyte gating is shown to be caused by oxygen/water entrained in the ionic liquid electrolyte. While encapsulation can avoid the issue, a nonencapsulation-based approach is also implemented.« less

On Field-Effect Photovoltaics: Gate Enhancement of the Power Conversion Efficiency in a Nanotube/Silicon-Nanowire Solar Cell

DOE PAGES

Petterson, Maureen K.; Lemaitre, Maxime G.; Shen, Yu; ...

2015-09-09

Recent years have seen a resurgence of interest in crystalline silicon Schottky junction solar cells distinguished by the use of low density of electronic states (DOS) nanocarbons (nanotubes, graphene) as the metal contacting the Si. Recently, unprecedented modulation of the power conversion efficiency in a single material system has been demonstrated in such cells by the use of electronic gating. The gate field induced Fermi level shift in the low-DOS carbon serves to enhance the junction built-in potential, while a gate field induced inversion layer at the Si surface, in regions remote from the junction, keeps the photocarriers well separatedmore » there, avoiding recombination at surface traps and defects (a key loss mechanism). Here, we extend these results into the third dimension of a vertical Si nanowire array solar cell. A single wall carbon nanotube layer engineered to contact virtually each n-Si nanowire tip extracts the minority carriers, while an ionic liquid electrolytic gate drives the nanowire body into inversion. The enhanced light absorption of the vertical forest cell, at 100 mW/cm 2 AM1.5G illumination, results in a short-circuit current density of 35 mA/cm 2 and associated power conversion efficiency of 15%. These results highlight the use of local fields as opposed to surface passivation as a means of avoiding front surface recombination. Finally, a deleterious electrochemical reaction of the silicon due to the electrolyte gating is shown to be caused by oxygen/water entrained in the ionic liquid electrolyte. While encapsulation can avoid the issue, a nonencapsulation-based approach is also implemented.« less

Cell-surface prion protein interacts with glycosaminoglycans.

PubMed Central

Pan, Tao; Wong, Boon-Seng; Liu, Tong; Li, Ruliang; Petersen, Robert B; Sy, Man-Sun

2002-01-01

We used ELISA and flow cytometry to study the binding of prion protein PrP to glycosaminoglycans (GAGs). We found that recombinant human PrP (rPrP) binds GAGs including chondroitin sulphate A, chondroitin sulphate B, hyaluronic acid, and heparin. rPrP binding to GAGs occurs via the N-terminus, a region known to bind divalent cations. Additionally, rPrP binding to GAGs is enhanced in the presence of Cu2+ and Zn2+, but not Ca2+ and Mn2+. rPrP binds heparin strongest, and the binding is inhibited by certain heparin analogues, including heparin disaccharide and sulphate-containing monosaccharides, but not by acetylated heparin. Full-length normal cellular prion protein (PrPC), but not N-terminally truncated PrPC species, from human brain bind GAGs in a similar Cu2+/Zn2+-enhanced fashion. We found that GAGs specifically bind to a synthetic peptide corresponding to amino acid residues 23-35 in the N-terminus of rPrP. We further demonstrated that while both wild-type PrPC and an octapeptide-repeat-deleted mutant PrP produced by transfected cells bound heparin at the cell surface, the PrP N-terminal deletion mutant and non-transfectant control failed to bind heparin. Binding of heparin to wild-type PrPC on the cell surface results in a reduction of the level of cell-surface PrPC. These results provide strong evidence that PrPC is a surface receptor for GAGs. PMID:12186633

Insulin promotes cell migration by regulating PSA-NCAM.

PubMed

Monzo, Hector J; Coppieters, Natacha; Park, Thomas I H; Dieriks, Birger V; Faull, Richard L M; Dragunow, Mike; Curtis, Maurice A

2017-06-01

Cellular interactions with the extracellular environment are modulated by cell surface polysialic acid (PSA) carried by the neural cell adhesion molecule (NCAM). PSA-NCAM is involved in cellular processes such as differentiation, plasticity, and migration, and is elevated in Alzheimer's disease as well as in metastatic tumour cells. Our previous work demonstrated that insulin enhances the abundance of cell surface PSA by inhibiting PSA-NCAM endocytosis. In the present study we have identified a mechanism for insulin-dependent inhibition of PSA-NCAM turnover affecting cell migration. Insulin enhanced the phosphorylation of the focal adhesion kinase leading to dissociation of αv-integrin/PSA-NCAM clusters, and promoted cell migration. Our results show that αv-integrin plays a key role in the PSA-NCAM turnover process. αv-integrin knockdown stopped PSA-NCAM from being endocytosed, and αv-integrin/PSA-NCAM clusters co-labelled intracellularly with Rab5, altogether indicating a role for αv-integrin as a carrier for PSA-NCAM during internalisation. Furthermore, inhibition of p-FAK caused dissociation of αv-integrin/PSA-NCAM clusters and counteracted the insulin-induced accumulation of PSA at the cell surface and cell migration was impaired. Our data reveal a functional association between the insulin/p-FAK-dependent regulation of PSA-NCAM turnover and cell migration through the extracellular matrix. Most importantly, they identify a novel mechanism for insulin-stimulated cell migration. Copyright © 2017 Elsevier Inc. All rights reserved.

An organic surface modifier to produce a high work function transparent electrode for high performance polymer solar cells.

PubMed

Choi, Hyosung; Kim, Hak-Beom; Ko, Seo-Jin; Kim, Jin Young; Heeger, Alan J

2015-02-04

Modification of an ITO electrode with small-molecule organic surface modifier, 4-chloro-benzoic acid (CBA), via a simple spin-coating method produces a high-work-function electrode with high transparency and a hydrophobic surface. As an alternative to PEDOT:PSS, CBA modification achieves efficiency enhancement up to 8.5%, which is attributed to enhanced light absorption within the active layer and smooth hole transport from the active layer to the anode. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gold nanorods as contrast agents for biological imaging: optical properties, surface conjugation, and photothermal effects†

PubMed Central

Tong, Ling; Wei, Qingshan; Wei, Alexander; Cheng, Ji-Xin

2009-01-01

Gold nanorods (NRs) have plasmon-resonant absorption and scattering in the near-infrared (NIR) region, making them attractive probes for in vitro and in vivo imaging. In the cellular environment, NRs can provide scattering contrast for darkfield microscopy, or emit a strong two-photon luminescence (TPL) due to plasmon-enhanced two-photon absorption. NRs have also been employed in biomedical imaging modalities such as optical coherence tomography (OCT) or photoacoustic tomography (PAT). Careful control over surface chemistry enhances the capacity of NRs as biological imaging agents by enabling cell-specific targeting, and by increasing their dispersion stability and circulation lifetimes. NRs can also efficiently convert optical energy into heat, and inflict localized damage to tumor cells. Laser-induced heating of NRs can disrupt cell membrane integrity and homeostasis, resulting in Ca2+ influx and the depolymerization of the intracellular actin network. The combination of plasmon-resonant optical properties, intense local photothermal effects, and robust surface chemistry render gold NRs as promising theragnostic agents. PMID:19161395

Optical pumping and xenon NMR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raftery, M. Daniel

1991-11-01

Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping 129Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to highmore » magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the 131Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.« less

Optical pumping and xenon NMR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raftery, M.D.

1991-11-01

Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping [sup 129]Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas tomore » high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the [sup 131]Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.« less

Synergetic scattering of SiO2 and Ag nanoparticles for light-trapping enhancement in organic bulk heterojunction

NASA Astrophysics Data System (ADS)

Yang, Huan; Ding, Qiuyu; Li, Ben Q.; Jiang, Xinbing; Zhang, Manman

2018-02-01

Though noble metal nanoparticles have been explored to enhance the performance of the organic solar cell, effect of dielectric nanoparticles, and coupled effect of dielectric and metal nanoparticles, have rarely been reported, if at all, on organic solar cell. This work reports an experimental study on synergetic scattering of SiO2 and Ag nanoparticles in a bulk organic heterojunction for the broadband light absorption enhancement. The wavelength scale SiO2 particles were arranged as a monolayer on the surface of the solar cell to guide incident light into the active layer and prolong the effective optical length of the entered energy. This is achieved by the excitation of whispering gallery modes in SiO2 nanoparticles and by leaky mode radiation. When small size Ag particles were incorporated into the transport layer of the solar cell, synergetic scattering of SiO2 and Ag nanoparticles is formed by coupling of the whispering gallery mode of closely arranged SiO2 particles atop and collaborative localized surface plasma resonance scattering of Ag nanoparticles dispersed in the transport layer. As a result, the performance of the organic solar cell is greatly enhanced and the short-circuit current density has an improvement of 42.47%. Therefore, the organic solar cell incorporated with SiO2 and Ag particles presents a meaningful strategy to achieve high energy-harvesting performance. [Figure not available: see fulltext.

Size, charge and concentration dependent uptake of iron oxide particles by non-phagocytic cells.

PubMed

Thorek, Daniel L J; Tsourkas, Andrew

2008-09-01

A promising new direction for contrast-enhanced magnetic resonance (MR) imaging involves tracking the migration and biodistribution of superparamagnetic iron oxide (SPIO)-labeled cells in vivo. Despite the large number of cell labeling studies that have been performed with SPIO particles of differing size and surface charge, it remains unclear which SPIO configuration provides optimal contrast in non-phagocytic cells. This is largely because contradictory findings have stemmed from the variability and imprecise control over surface charge, the general need and complexity of transfection and/or targeting agents, and the limited number of particle configurations examined in any given study. In the present study, we systematically evaluated the cellular uptake of SPIO in non-phagocytic T cells over a continuum of particle sizes ranging from 33nm to nearly 1.5microm, with precisely controlled surface properties, and without the need for transfection agents. SPIO labeling of T cells was analyzed by flow cytometry and contrast enhancement was determined by relaxometry. SPIO uptake was dose-dependent and exhibited sigmoidal charge dependence, which was shown to saturate at different levels of functionalization. Efficient labeling of cells was observed for particles up to 300nm, however, micron-sized particle uptake was limited. Our results show that an unconventional highly cationic particle configuration at 107nm maximized MR contrast of T cells, outperforming the widely utilized USPIO (<50nm).

Size, Charge and Concentration Dependent Uptake of Iron Oxide Particles by Non-Phagocytic Cells

PubMed Central

Thorek, Daniel L.J.; Tsourkas, Andrew

2008-01-01

A promising new direction for contrast-enhanced magnetic resonance (MR) imaging involves tracking the migration and biodistribution of superparamagnetic iron oxide (SPIO)-labeled cells in vivo. Despite the large number of cell labeling studies that have been performed with SPIO particles of differing size and surface charge, it remains unclear which SPIO configuration provides optimal contrast in non-phagocytic cells. This is largely because contradictory findings have stemmed from the variability and imprecise control over surface charge, the general need and complexity of transfection and/or targeting agents, and the limited number of particle configurations examined in any given study. In the present study, we systematically evaluated the cellular uptake of SPIO in non-phagocytic T cells over a continuum of particle sizes ranging from 33 nm to nearly 1.5 μm, with precisely controlled surface properties, and without the need for transfection agents. SPIO labeling of T cells was analyzed by flow cytometry and contrast enhancement was determined by relaxometry. SPIO uptake was dose dependent and exhibited sigmoidal charge dependence, which was shown to saturate at different levels of functionalization. Efficient labeling of cells was observed for particles up to 300nm, however micron-sized particle uptake was limited. Our results show that an unconventional highly cationic particle configuration at 107 nm maximized MR contrast of T cells, outperforming the widely utilized USPIO (<50 nm). PMID:18533252

Protein-scaffold Directed Nanoscale Assembly of T Cell Ligands: Artificial Antigen Presentation with Defined Valency, Density and Ratio.

PubMed

Smith, Mason R; Tolbert, Stephanie V; Wen, Fei

2018-05-07

Tuning antigen presentation to T cells is a critical step in investigating key aspects of T cell activation. However, existing technologies have limited ability to control the spatial and stoichiometric organization of T cell ligands on 3D surfaces. Here, we developed an artificial antigen presentation platform based on protein-scaffold directed assembly that allows fine control over the spatial and stoichiometric organization of T cell ligands on a 3D yeast-cell surface. Using this system, we observed that the T cell activation threshold on a 3D surface is independent of peptide-major histocompatibility complex (pMHC) valency, but instead determined by the overall pMHC surface density. When intercellular adhesion molecule 1 (ICAM-1) was co-assembled with pMHC, it enhanced antigen recognition sensitivity by 6-fold. Further, T cells responded with different magnitudes to varying ratios of pMHC and ICAM-1 and exhibited a maximum response at a ratio of 15% pMHC and 85% ICAM-1, introducing an additional parameter for tuning T cell activation. This protein-scaffold directed assembly technology is readily transferrable to acellular surfaces for translational research as well as large-scale T-cell manufacturing.

Polydopamine-mediated surface modification of scaffold materials for human neural stem cell engineering.

PubMed

Yang, Kisuk; Lee, Jung Seung; Kim, Jin; Lee, Yu Bin; Shin, Heungsoo; Um, Soong Ho; Kim, Jeong Beom; Park, Kook In; Lee, Haeshin; Cho, Seung-Woo

2012-10-01

Surface modification of tissue engineering scaffolds and substrates is required for improving the efficacy of stem cell therapy by generating physicochemical stimulation promoting proliferation and differentiation of stem cells. However, typical surface modification methods including chemical conjugation or physical absorption have several limitations such as multistep, complicated procedures, surface denaturation, batch-to-batch inconsistencies, and low surface conjugation efficiency. In this study, we report a mussel-inspired, biomimetic approach to surface modification for efficient and reliable manipulation of human neural stem cell (NSC) differentiation and proliferation. Our study demonstrates that polydopamine coating facilitates highly efficient, simple immobilization of neurotrophic growth factors and adhesion peptides onto polymer substrates. The growth factor or peptide-immobilized substrates greatly enhance differentiation and proliferation of human NSCs (human fetal brain-derived NSCs and human induced pluripotent stem cell-derived NSCs) at a level comparable or greater than currently available animal-derived coating materials (Matrigel) with safety issues. Therefore, polydopamine-mediated surface modification can provide a versatile platform technology for developing chemically defined, safe, functional substrates and scaffolds for therapeutic applications of human NSCs. Copyright © 2012 Elsevier Ltd. All rights reserved.

Enhanced Conversion Efficiency of III–V Triple-junction Solar Cells with Graphene Quantum Dots

PubMed Central

Lin, Tzu-Neng; Santiago, Svette Reina Merden S.; Zheng, Jie-An; Chao, Yu-Chiang; Yuan, Chi-Tsu; Shen, Ji-Lin; Wu, Chih-Hung; Lin, Cheng- An J.; Liu, Wei-Ren; Cheng, Ming-Chiang; Chou, Wu-Ching

2016-01-01

Graphene has been used to synthesize graphene quantum dots (GQDs) via pulsed laser ablation. By depositing the synthesized GQDs on the surface of InGaP/InGaAs/Ge triple-junction solar cells, the short-circuit current, fill factor, and conversion efficiency were enhanced remarkably. As the GQD concentration is increased, the conversion efficiency in the solar cell increases accordingly. A conversion efficiency of 33.2% for InGaP/InGaAs/Ge triple-junction solar cells has been achieved at the GQD concentration of 1.2 mg/ml, corresponding to a 35% enhancement compared to the cell without GQDs. On the basis of time-resolved photoluminescence, external quantum efficiency, and work-function measurements, we suggest that the efficiency enhancement in the InGaP/InGaAs/Ge triple-junction solar cells is primarily caused by the carrier injection from GQDs to the InGaP top subcell. PMID:27982073

In vitro mesenchymal stem cell response to a CO2 laser modified polymeric material.

PubMed

Waugh, D G; Hussain, I; Lawrence, J; Smith, G C; Cosgrove, D; Toccaceli, C

2016-10-01

With an ageing world population it is becoming significantly apparent that there is a need to produce implants and platforms to manipulate stem cell growth on a pharmaceutical scale. This is needed to meet the socio-economic demands of many countries worldwide. This paper details one of the first ever studies in to the manipulation of stem cell growth on CO2 laser surface treated nylon 6,6 highlighting its potential as an inexpensive platform to manipulate stem cell growth on a pharmaceutical scale. Through CO2 laser surface treatment discrete changes to the surfaces were made. That is, the surface roughness of the nylon 6,6 was increased by up to 4.3μm, the contact angle was modulated by up to 5° and the surface oxygen content increased by up to 1atom %. Following mesenchymal stem cell growth on the laser treated samples, it was identified that CO2 laser surface treatment gave rise to an enhanced response with an increase in viable cell count of up to 60,000cells/ml when compared to the as-received sample. The effect of surface parameters modified by the CO2 laser surface treatment on the mesenchymal stem cell response is also discussed along with potential trends that could be identified to govern the mesenchymal stem cell response. Copyright © 2016. Published by Elsevier B.V.

Substrate porosity enhances chondrocyte attachment, spreading, and cartilage tissue formation in vitro.

PubMed

Spiteri, C G; Pilliar, R M; Kandel, R A

2006-09-15

Tissue engineering is being explored as a new approach to treat damaged cartilage. As the biomaterial used may influence tissue formation, the effects of substrate geometry on chondrocyte behavior in vitro were examined. Articular chondrocytes were isolated and cultured on the surface of smooth, rough, porous-coated, and fully porous Ti-6Al-4V substrates. The percentage of chondrocytes that attached to each substrate at 24 h was determined. After 24 and 72 h, chondrocytes were visualized by scanning electron microscopy and cell areas were measured. Collagen and proteoglycan accumulation within the first 24 h was determined by incorporation with [3H]-proline and [35S]-SO4, respectively. Chondrocyte attachment as well as matrix accumulation was enhanced as substrate surface area increased. Cell areas on the fully porous substrate were over four times greater than on any other substrate by 72 h in culture. After 8 weeks in culture, a continuous layer of cartilaginous tissue formed only on the surface of the fully porous substrate. This suggests that fully porous Ti-6Al-4V substrates provide the conditions that favor cartilage tissue formation by influencing cell attachment and extent of cell spreading. Understanding how substrate porosity influences chondrocyte behavior may help identify methods to further enhance cartilage tissue formation in vitro. 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006.

Titania nanotubes with adjustable dimensions for drug reservoir sites and enhanced cell adhesion.

PubMed

Çalışkan, Nazlı; Bayram, Cem; Erdal, Ebru; Karahaliloğlu, Zeynep; Denkbaş, Emir Baki

2014-02-01

This study aims to generate a bactericidal agent releasing surface via nanotube layer on titanium metal and to investigate how aspect ratio of nanotubes affects drug elution time and cell proliferation. Titania nanotube layers were generated on metal surfaces by anodic oxidation at various voltage and time parameters. Gentamicin loading was carried out via simple pipetting and the samples were tested against S. aureus for the efficacy of the applied modification. Drug releasing time and cell proliferation were also tested in vitro. Titania nanotube layers with varying diameters and lengths were prepared after anodization and anodizing duration was found as the most effective parameter for amount of loaded drug and drug releasing time. Drug elution lasted up to 4 days after anodizing for 80 min of the samples, whereas release completed in 24 h when the samples were anodized for 20 min. All processed samples had bactericidal properties against S. aureus organism except unmodified titanium, which was also subjected to drug incorporation step. The anodization also enhanced water wettability and cell adhesion results. Anodic oxidation is an effective surface modification to enhance tissue-implant interactions and also resultant titania layer can act as a drug reservoir for the release of bactericidal agents. The use of implants as local drug eluting devices is promising but further in vivo testing is required. Copyright © 2013 Elsevier B.V. All rights reserved.

Fabrication of Nanostructures on Implantable Biomaterials for Biocompatibility Enhancement and Infection Resistance

NASA Astrophysics Data System (ADS)

Liu, Luting

An implant or implantable medical device, which is used to replace or restore the function of traumatized or degenerated tissues or organs, or acts as a fraction of or the whole biological structure, has been used in many different parts of the body for various applications (such as orthopedics, cardiovascular stents, or drug delivery systems for medical treatment). The best performance of the vast majority of implants is achieved when the biomaterial used promotes some biological activity (such as bone regeneration) while minimizing undesirable activity (such as infection, one of the most common reasons for the failure of many implants). The surface of the implant, through its interactions with proteins, bacteria and tissue forming cells, plays a critical role in the success or failure of the implant. Therefore, in this study, we sought to employ various nanofabrication techniques for tailoring implant surfaces to minimize bacteria and promote mammalian cell functions without using drugs. Titanium (Ti) and polyetheretherketone (PEEK) are commonly used biomaterials in orthopedic implants. Further surface modification is needed to support osseointegration while inhibiting bacteria attachment. Herein, temperature controlled atomic layer deposition (ALD) was utilized to provide unique nanostructured TiO2 coatings on commercial Ti. In vitro bacteria experiments revealed that the nano-TiO2 coatings showed promising antimicrobial efficacy towards Gram-positive bacteria (S. aureus), Gram-negative bacteria (E. coli) and antibiotic-resistant bacteria ( MRSA). Impressively, cell results indicated that this nano-TiO 2 coating stimulated osteoblast (or bone forming cell) adhesion and proliferation while suppressing undesirable fibroblast functions. The same procedure was performed on PEEK and also resulted in enhanced osteoblast functions and produced antimicrobial properties. In another study, to isolate the effect of surface chemistry on cell and bacteria activities, a simple template-molding method (in which a material with a special structure is used as a template to imprint its structure onto another material) with nanotubular anodized Ti was used to formulate a physical nanostructured pattern on a PDMS (a commonly used polymeric catheter material) surface without changing its surface chemistry. Results showed that increased PDMS surface nanoscale roughness alone inhibited both Gram-negative ( E. coli) and Gram-positive (S. aureus) bacteria adhesion and growth without using antibiotics while remaining non-toxic to fibroblasts and endothelial cells. A model was developed for the first time to correlate bacteria responses to nanoscale roughness with initial protein adsorption (specifically, casein protein, which is well known for preventing bacteria attachment). Data also revealed that an increase in nanoscale roughness and greater surface hydrophilicity together contributed to increased protein adsorption, which may decrease the interactions at the bacteria-nanorough surface interface and achieve effective antimicrobial properties. Mechanistically, this thesis also investigated the influence of specific surface properties (i.e., nanoscale surface roughness, surface wettability and associated surface energy) on cell and bacteria functions. Results showed a direct proportional linear correlation of surface energy with surface roughness. It was found that surface energy plays a major role in determining cell and bacteria functions, and specifically all proposed nanofabricated samples with an initial surface energy at 40 mJ/m2 showed relatively promising antibacterial properties and desirable cellular functions. Overall, the results of this study provided alternative, inexpensive, methods for fabricating various implant surfaces with nanostructures to enhance biocompatibility and prevent bacterial attachment simultaneously, which will be beneficial for numerous biomedical applications.

Role and mechanism of cell-surface hydrophobicity in the adaptation of Sphingobium hydrophobicum to electronic-waste contaminated sediment.

PubMed

Chen, Xingjuan; Song, Da; Xu, Jingjing; Li, Enze; Sun, Guoping; Xu, Meiying

2018-03-01

Sphingomonads are isolated at exceptionally high frequency from organic polluted environments and assumed to be more hydrophobic than other Gram-negative bacteria. However, the potential roles of cell-surface hydrophobicity (CSH) in the cell survival in polluted environment, as well as the mechanisms underlying the CSH of sphingomonads, remain unclear. Sphingobium hydrophobicum C1 T is a highly hydrophobic sphingomonad isolated from electronic-waste contaminated sediment. In this study, we found that exposure to the typical pollutants in electronic-waste contaminated sediment, such as the heavy metal ion Pb and the organic compound deca-brominated diphenyl ether (deca-BDE), resulted in the development of even higher CSH of the hydrophobic strain C1 T ; but no significant change was observed in the low CSH of its hydrophilic variant C2. The hydrophobic strain C1 T achieved higher biomass yield in standing conditions and adsorbed more amounts of hydrophobic deca-BDE than its hydrophilic variant C2, suggesting that the high CSH potentially enhanced the adaptation of hydrophobic strain to colonize in sediment and adsorb hydrophobic nutrients. The identification of the bacterial cell-surface constituents showed that the high CSH of S. hydrophobicum was contributed greatly by outer-membrane proteins, particularly membrane transporters functioning as enhancers for nutrient uptake and stress sustainment. This study will enhance our understanding of the adaptive strategies of sphingomonads in contaminated environments. It will be of great importance to enhance the CSH of sphingomonads and utilize them in cleaning up the environment from organic pollution.

Enhancement of photovoltaic cell performance using periodic triangular gratings

NASA Astrophysics Data System (ADS)

Bordatchev, Evgueni; Tauhiduzzaman, Mohammed; Dey, Rajat

2014-01-01

The solar energy industry strives to produce more efficient and yet cost effective solar panels each consisting of an array of photovoltaic (PV) cells. The goal of this study was to enhance the performance of PV cells through increasing the cells' optical efficiency defined as a percentage of surface incident light that reaches the PV material. This was achieved through the reduction of waveguide decoupling loss and Fresnel reflection losses by integrating specific nonimaging micro-optical structures on the top surface of existing PV cells. Due to this integration, optical efficiency and performance were increased through the enhancement of light trapping, light guiding, and in-coupling functionalities. Periodic triangular gratings (PTGs) were designed, nonsequentially modeled, optimized, and fabricated in polydimethylsiloxane as proposed micro-optical structures. Then the performance of PV cells with and without integrated PTGs was evaluated and compared. Initial optical simulation results show that an original PV cell (without PTG) exhibits an average optical efficiency of 32.7% over a range of incident light angles between 15 and 90 deg. Integration of the PTG allows the capture of incoming sunlight by total internal reflection (TIR), whence it is reflected back onto the PV cell for multiple consecutive chances for absorption and PV conversion. Geometry of the PTG was optimized with respect to an angle of light incidence of {15, 30, 45, 60, 75, 90} deg. Optical efficiency of the geometrically optimized PTGs was then analyzed under the same set of incident light angles and a maximum optical efficiency of 54.1% was observed for a PV cell with integrated PTG optimized at 90 deg. This is a 53.3% relative improvement in optical performance when compared to an original PV cell. Functional PTG prototypes were then fabricated with optical surface quality (below 10 nm Ra) and integrated with PV cells demonstrating an increase in maximum power by 1.08 mW/cm (7.6% improvement in PV performance) and in short circuit current by 2.39 mA/cm (6.4% improvement).

Chemo-spectroscopic sensor for carboxyl terminus overexpressed in carcinoma cell membrane.

PubMed

Stanca, Sarmiza E; Matthäus, Christian; Neugebauer, Ute; Nietzsche, Sandor; Fritzsche, Wolfgang; Dellith, Jan; Heintzmann, Rainer; Weber, Karina; Deckert, Volker; Krafft, Christoph; Popp, Jürgen

2015-10-01

Certain carboxyl groups of the plasma membrane are involved in tumorgenesis processes. A gold core-hydroxyapatite shell (AuHA) nanocomposite is introduced as chemo-spectroscopic sensor to monitor these carboxyl groups of the cell membrane. Hydroxyapatite (HA) plays the role both of a chemical detector and of a biocompatible Raman marker. The principle of detection is based on chemical interaction between the hydroxyl groups of the HA and the carboxyl terminus of the proteins. The AuHA exhibits a surface enhanced Raman scattering (SERS) signal at 954 cm(-1) which can be used for its localization. The bio-sensing capacity of AuHA towards human skin epidermoid carcinoma (A431) and Chinese hamster ovary (CHO) cell lines is investigated using Raman microspectroscopic imaging. The localization of AuHA on cells is correlated with scanning electron microscopy, transmission electron microscopy and structured illumination fluorescence microscopy. This qualitative approach is a step towards a quantitative study of the proteins terminus. This method would enable further studies on the molecular profiling of the plasma membrane, in an attempt to provide accurate cell identification. Using a gold core-hydroxyapatite shell (AuHA) nanocomposite, the authors in this paper showed the feasibility of detecting and differentiating cell surface molecules by surface enhanced Raman scattering. Copyright © 2015 Elsevier Inc. All rights reserved.

SERS-Active Nanoinjector for Intracellular Spectroscopy

NASA Astrophysics Data System (ADS)

Vitol, Elina; Orynbayeva, Zulfiya; Bouchard, Michael; Azizkhan-Clifford, Jane; Friedman, Gary; Gogotsi, Yury

2009-03-01

We developed a multifunctional nanopipette which allows simultaneous cell injection and intacellular surface-enhanced Raman spectroscopy (SERS) analysis. SERS spectra contain the characteristic frequencies of molecular bond vibrations. This is a unique method for studying cell biochemistry and physiology on a single organelle level. Unlike the fluorescence spectroscopy, it does not require any specific staining. The principle of SERS is based on very large electromagnetic field enhancement localized around a nano-rough metallic surface. Gold colloids are widely used SERS substrates. Previously, the colloidal nanoparticles were introduced into a cell by the mechanism of endocytosis. The disadvantage of this method is the uncontrollable aggregation and distribution of gold nanoparticles inside a cell which causes a significant uncertainty in the origin of the acquired data. At the same time, the nanoparticle uptake is irreversible. We present a SERS-active nanoinjector, coated with gold nanoparticles, which enables selective signal acquisition from any point-of-interest inside a cell. The nanoinjector provides a highly localized SERS signal with sub-nanometer resolution in real time.

Amyloid-β peptide on sialyl-Lewis(X)-selectin-mediated membrane tether mechanics at the cerebral endothelial cell surface.

PubMed

Askarova, Sholpan; Sun, Zhe; Sun, Grace Y; Meininger, Gerald A; Lee, James C-M

2013-01-01

Increased deposition of amyloid-β peptide (Aβ) at the cerebral endothelial cell (CEC) surface has been implicated in enhancement of transmigration of monocytes across the brain blood barrier (BBB) in Alzheimer's disease (AD). In this study, quantitative immunofluorescence microscopy (QIM) and atomic force microscopy (AFM) with cantilevers biofunctionalized by sialyl-Lewis(x) (sLe(x)) were employed to investigate Aβ-altered mechanics of membrane tethers formed by bonding between sLe(x) and p-selectin at the CEC surface, the initial mechanical step governing the transmigration of monocytes. QIM results indicated the ability for Aβ to increase p-selectin expression at the cell surface and promote actin polymerization in both bEND3 cells (immortalized mouse CECs) and human primary CECs. AFM data also showed the ability for Aβ to increase cell stiffness and adhesion probability in bEND3 cells. On the contrary, Aβ lowered the overall force of membrane tether formation (Fmtf ), and produced a bimodal population of Fmtf , suggesting subcellular mechanical alterations in membrane tethering. The lower Fmtf population was similar to the results obtained from cells treated with an F-actin-disrupting drug, latrunculin A. Indeed, AFM results also showed that both Aβ and latrunculin A decreased membrane stiffness, suggesting a lower membrane-cytoskeleton adhesion, a factor resulting in lower Fmtf . In addition, these cerebral endothelial alterations induced by Aβ were abrogated by lovastatin, consistent with its anti-inflammatory effects. In sum, these results demonstrated the ability for Aβ to enhance p-selectin expression at the CEC surface and induce cytoskeleton reorganization, which in turn, resulted in changes in membrane-cytoskeleton adhesion and membrane tethering, mechanical factors important in transmigration of monocytes through the BBB.

Amyloid-β Peptide on Sialyl-LewisX-Selectin-Mediated Membrane Tether Mechanics at the Cerebral Endothelial Cell Surface

PubMed Central

Askarova, Sholpan; Sun, Zhe; Sun, Grace Y.; Meininger, Gerald A.; Lee, James C-M.

2013-01-01

Increased deposition of amyloid-β peptide (Aβ) at the cerebral endothelial cell (CEC) surface has been implicated in enhancement of transmigration of monocytes across the brain blood barrier (BBB) in Alzheimer's disease (AD). In this study, quantitative immunofluorescence microscopy (QIM) and atomic force microscopy (AFM) with cantilevers biofunctionalized by sialyl-Lewisx (sLex) were employed to investigate Aβ-altered mechanics of membrane tethers formed by bonding between sLex and p-selectin at the CEC surface, the initial mechanical step governing the transmigration of monocytes. QIM results indicated the ability for Aβ to increase p-selectin expression at the cell surface and promote actin polymerization in both bEND3 cells (immortalized mouse CECs) and human primary CECs. AFM data also showed the ability for Aβ to increase cell stiffness and adhesion probability in bEND3 cells. On the contrary, Aβ lowered the overall force of membrane tether formation (Fmtf), and produced a bimodal population of Fmtf, suggesting subcellular mechanical alterations in membrane tethering. The lower Fmtf population was similar to the results obtained from cells treated with an F-actin-disrupting drug, latrunculin A. Indeed, AFM results also showed that both Aβ and latrunculin A decreased membrane stiffness, suggesting a lower membrane-cytoskeleton adhesion, a factor resulting in lower Fmtf. In addition, these cerebral endothelial alterations induced by Aβ were abrogated by lovastatin, consistent with its anti-inflammatory effects. In sum, these results demonstrated the ability for Aβ to enhance p-selectin expression at the CEC surface and induce cytoskeleton reorganization, which in turn, resulted in changes in membrane-cytoskeleton adhesion and membrane tethering, mechanical factors important in transmigration of monocytes through the BBB. PMID:23593361

Magnesium ion implantation on a micro/nanostructured titanium surface promotes its bioactivity and osteogenic differentiation function

PubMed Central

Wang, Guifang; Li, Jinhua; Zhang, Wenjie; Xu, Lianyi; Pan, Hongya; Wen, Jin; Wu, Qianju; She, Wenjun; Jiao, Ting; Liu, Xuanyong; Jiang, Xinquan

2014-01-01

As one of the important ions associated with bone osseointegration, magnesium was incorporated into a micro/nanostructured titanium surface using a magnesium plasma immersion ion-implantation method. Hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 30 minutes (Mg30) and hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 60 minutes (Mg60) were used as test groups. The surface morphology, chemical properties, and amount of magnesium ions released were evaluated by field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, field-emission transmission electron microscopy, and inductively coupled plasma-optical emission spectrometry. Rat bone marrow mesenchymal stem cells (rBMMSCs) were used to evaluate cell responses, including proliferation, spreading, and osteogenic differentiation on the surface of the material or in their medium extraction. Greater increases in the spreading and proliferation ability of rBMMSCs were observed on the surfaces of magnesium-implanted micro/nanostructures compared with the control plates. Furthermore, the osteocalcin (OCN), osteopontin (OPN), and alkaline phosphatase (ALP) genes were upregulated on both surfaces and in their medium extractions. The enhanced cell responses were correlated with increasing concentrations of magnesium ions, indicating that the osteoblastic differentiation of rBMMSCs was stimulated through the magnesium ion function. The magnesium ion-implanted micro/nanostructured titanium surfaces could enhance the proliferation, spreading, and osteogenic differentiation activity of rBMMSCs, suggesting they have potential application in improving bone-titanium integration. PMID:24940056

4-phenylbutyrate enhances the cell surface expression and the transport capacity of wild-type and mutated bile salt export pumps.

PubMed

Hayashi, Hisamitsu; Sugiyama, Yuichi

2007-06-01

Progressive familial intrahepatic cholestasis type 2 (PFIC2) is caused by a mutation in the bile salt export pump (BSEP/ABCB11) gene. We previously reported that E297G and D482G BSEP, which are frequently found mutations in European patients, result in impaired membrane trafficking, whereas both mutants retain their transport function. The dysfunctional localization is probably attributable to the retention of BSEP in endoplasmic reticulum (ER) followed by proteasomal degradation. Because sodium 4-phenylbutyrate (4PBA) has been shown to restore the reduced cell surface expression of mutated plasma membrane proteins, in the current study, we investigated the effect of 4PBA treatment on E297G and D482G BSEP. Transcellular transport and cell surface biotinylation studies using Madin-Darby canine kidney (MDCK) II cells demonstrated that 4PBA treatment increased functional cell surface expression of wild-type (WT), E297G, and D482G BSEP. The prolonged half-life of cell surface-resident BSEP with 4PBA treatment was responsible for this result. Moreover, treatment of Sprague-Dawley rats with 4PBA resulted in an increase in BSEP expression at the canalicular membrane, which was accompanied by an increase in the biliary excretion of [(3)H]taurocholic acid (TC). 4PBA treatment with a clinically achievable concentration enhances the cell surface expression and the transport capacity of WT, E297G, and D482G BSEP in MDCK II cells, and also induces functional BSEP expression at the canalicular membrane and bile acid transport via canalicular membrane in vivo. 4PBA is a potential pharmacological agent for treating not only PFIC2 patients with E297G and D482G mutations but also other cholestatic patients, in whom the BSEP expression at the canalicular membrane is reduced.

Surface enhanced Raman spectroscopy analysis of HeLa cells using a multilayer substrate

NASA Astrophysics Data System (ADS)

Aguilar-Hernández, I. A.; Pichardo-Molina, J. L.; Lopez-Luke, T.; Ornelas-Soto, N.

2017-08-01

Single cell analysis can provide important information regarding cell composition, and can be used for biomedical applications. In this work, a SERS active substrate formed by 3 layers of gold nanospheres and a final layer of gold nanocubes was used for the label-free SERS analysis of HeLa cells. Nanocubes were selected due to the high electromagnetic enhancement expected in nanoparticles with sharp corners. Significant improvement in the reproducibility and quality of SERS spectra was found when compared to the spectra obtained using a nanosphere-only substrate and normal Raman spectroscopy.

Improvement of organic solar cells by flexible substrate and ITO surface treatments

NASA Astrophysics Data System (ADS)

Cheng, Yuang-Tung; Ho, Jyh-Jier; Wang, Chien-Kun; Lee, William; Lu, Chih-Chiang; Yau, Bao-Shun; Nain, Jhen-Liang; Chang, Shun-Hsyung; Chang, Chiu-Cheng; Wang, Kang L.

2010-10-01

In this paper, surface treatments on polyethylene terephthalate with polymeric hard coating (PET-HC) substrates are described. The effect of the contact angle on the treatment is first investigated. It has been observed that detergent is quite effective in removing organic contamination on the flexible PET-HC substrates. Next, using a DC-reactive magnetron sputter, indium tin oxide (ITO) thin films of 90 nm are grown on a substrate treated by detergent. Then, various ITO surface treatments are made for improving the performance of the finally developed organic solar cells with structure Al/P3HT:PCBM/PEDOT:PSS/ITO/PET. It is found that the parameters of the ITO including resistivity, carrier concentration, transmittance, surface morphology, and work function depended on the surface treatments and significantly influence the solar cell performance. With the optimal conditions for detergent treatment on flexible PET substrates, the ITO film with a resistivity of 5.6 × 10 -4 Ω cm and average optical transmittance of 84.1% in the visible region are obtained. The optimal ITO surface treated by detergent for 5 min and then by UV ozone for 20 min exhibits the best WF value of 5.22 eV. This improves about 8.30% in the WF compared with that of the untreated ITO film. In the case of optimal treatment with the organic photovoltaic device, meanwhile, 36.6% enhancement in short circuit current density ( Jsc) and 92.7% enhancement in conversion efficiency ( η) over the untreated solar cell are obtained.

Antimicrobial design of titanium surface that kill sessile bacteria but support stem cells adhesion

NASA Astrophysics Data System (ADS)

Zhu, Chen; Bao, Ni-Rong; Chen, Shuo; Zhao, Jian-Ning

2016-12-01

Implant-related bacterial infection is one of the most severe postoperative complications in orthopedic or dental surgery. In this context, from the perspective of surface modification, increasing efforts have been made to enhance the antibacterial capability of titanium surface. In this work, a hierarchical hybrid surface architecture was firstly constructed on titanium surface by two-step strategy of acid etching and H2O2 aging. Then silver nanoparticles were firmly immobilized on the hierarchical surface by ion implantation, showing no detectable release of silver ions from surface. The designed titanium surface showed good bioactivity. More importantly, this elaborately designed titanium surface can effectively inactivate the adherent S. aureus on surface by virtue of a contact-killing mode. Meanwhile, the designed titanium surface can significantly facilitate the initial adhesion and spreading behaviors of bone marrow mesenchymal stem cells (MSCs) on titanium. The results suggested that, the elaborately designed titanium surface might own a cell-favoring ability that can help mammalian cells win the initial adhesion race against bacteria. We hope the present study can provide a new insight for the better understanding and designing of antimicrobial titanium surface, and pave the way to satisfying clinical requirements.

Enhanced in vitro biocompatibility of ultrafine-grained biomedical NiTi alloy with microporous surface

NASA Astrophysics Data System (ADS)

Zheng, C. Y.; Nie, F. L.; Zheng, Y. F.; Cheng, Y.; Wei, S. C.; Valiev, R. Z.

2011-08-01

Bulk ultrafine-grained Ni 50.8Ti 49.2 alloy (UFG-NiTi) was successfully fabricated by equal-channel angular pressing (ECAP) technique in the present study, and to further improve its surface biocompatibility, surface modification techniques including sandblasting, acid etching and alkali treatment were employed to produce either irregularly roughened surface or microporous surface or hierarchical porous surface with bioactivity. The effect of the above surface treatments on the surface roughness, wettability, corrosion behavior, ion release, apatite forming ability and cytocompatibility of UFG-NiTi alloy were systematically investigated with the coarse-grained NiTi alloy as control. The pitting corrosion potential ( Epit) was increased from 393 mV (SCE) to 704 mV (SCE) with sandblasting and further increased to 1539 mV (SCE) with following acid etching in HF/HNO 3 solution. All the above surface treatment increased the apatite forming ability of UFG-NiTi in varying degrees when soaked them in simulated body fluid (SBF). Meanwhile, both sandblasting and acid etching could promote the cytocompatibility for osteoblasts: sandblasting enhanced cell attachment and acid etching increased cell proliferation. The different corrosion behavior, apatite forming ability and cellular response of UFG-NiTi after different surface modifications are attributed to the topography and wettability of the resulting surface oxide layer.

Selective fibronectin adsorption against albumin and enhanced stem cell attachment on helium atmospheric pressure glow discharge treated titanium

NASA Astrophysics Data System (ADS)

Han, Inho; Vagaska, Barbora; Joo Park, Bong; Lee, Mi Hee; Jin Lee, Seung; Park, Jong-Chul

2011-06-01

Successful tissue integration of implanted medical devices depends on appropriate initial cellular response. In this study, the effect of helium atmospheric pressure glow discharge (He-APGD) treatment of titanium on selective protein adsorption and the initial attachment processes and focal adhesion formation of osteoprogenitor cells and stem cells were examined. Titanium disks were treated in a self-designed He-APGD system. Initial attachment of MC3T3-E1 mouse pre-osteoblasts and human mesenchymal stem cells (MSCs) was evaluated by MTT assay and plasma membrane staining followed by morphometric analysis. Fibronectin adsorption was investigated by Enzyme-Linked ImmunoSorbant Assay. MSCs cell attachment to treated and non-treated titanium disks coated with different proteins was verified also in serum-free culture. Organization of actin cytoskeleton and focal adhesions was evaluated microscopically. He-APGD treatment effectively modified the titanium surfaces by creating a super-hydrophilic surface, which promoted selectively higher adsorption of fibronectin, a protein of critical importance for cell/biomaterial interaction. In two different types of cells, the He-APGD treatment enhanced the number of attaching cells as well as their attachment area. Moreover, cells had higher organization of actin cytoskeleton and focal adhesions. Faster acceptance of the material by the progenitor cells in the early phases of tissue integration after the implantation may significantly reduce the overall healing time; therefore, titanium treatment with He-APGD seems to be an effective method of surface modification of titanium for improving its tissue inductive properties.

Study of Mesoporous Silica Nanoparticles' (MSNs) intracellular trafficking and their application as drug delivery vehicles

NASA Astrophysics Data System (ADS)

Yanes, Rolando Eduardo

Mesoporous silica nanoparticles (MSNs) are attractive drug delivery vehicle candidates due to their biocompatibility, stability, high surface area and efficient cellular uptake. In this dissertation, I discuss three aspects of MSNs' cellular behavior. First, MSNs are targeted to primary and metastatic cancer cell lines, then their exocytosis from cancer cells is studied, and finally they are used to recover intracellular proteins. Targeting of MSNs to primary cancer cells is achieved by conjugating transferrin on the surface of the mesoporous framework, which resulted in enhancement of nanoparticle uptake and drug delivery efficacy in cells that overexpress the transferrin receptor. Similarly, RGD peptides are used to target metastatic cancer cell lines that over-express integrin alphanubeta3. A circular RGD peptide is bound to the surface of MSNs and the endocytosis and cell killing efficacy of camptothecin loaded nanoparticles is significantly improved in cells that express the target receptor. Besides targeting, I studied the ultimate fate of phosphonate coated mesoporous silica nanoparticles inside cells. I discovered that the nanoparticles are exocytosed from cells through lysosomal exocytosis. The nanoparticles are exocytosed in intact form and the time that they remain inside the cells is affected by the surface properties of the nanoparticles and the type of cells. Cells that have a high rate of lysosomal exocytosis excrete the nanoparticles rapidly, which makes them more resistant to drug loaded nanoparticles because the amount of drug that is released inside the cell is limited. When the exocytosis of MSNs is inhibited, the cell killing efficacy of nanoparticles loaded with camptothecin is enhanced. The discovery that MSNs are exocytosed by cells led to a study to determine if proteins could be recovered from the exocytosed nanoparticles. The procedure to isolate exocytosed zinc-doped iron core MSNs and identify the proteins bound to them was developed. This serves as a foundation to use MSNs as protein harvesting tools and investigate protein expression in cancer cells.

Enhanced separation of membranes during free flow zonal electrophoresis in plants.

PubMed

Barkla, Bronwyn J; Vera-Estrella, Rosario; Pantoja, Omar

2007-07-15

Free flow zonal electrophoresis (FFZE) is a versatile technique that allows for the separation of cells, organelles, membranes, and proteins based on net surface charge during laminar flow through a thin aqueous layer. We have been optimizing the FFZE technique to enhance separation of plant vacuolar membranes (tonoplast) from other endomembranes to pursue a directed proteomics approach to identify novel tonoplast transporters. Addition of ATP to a mixture of endomembranes selectively enhanced electrophoretic mobility of acidic vesicular compartments during FFZE toward the positive electrode. This has been attributed to activation of the V-ATPase generating a more negative membrane potential outside the vesicles, resulting in enhanced migration of acidic vesicles, including tonoplast, to the anode (Morré, D. J.; Lawrence, J.; Safranski, K.; Hammond, T.; Morré, D. M. J. Chromatogr., A 1994, 668, 201-213). We confirm that ATP does induce a redistribution of membranes during FFZE of microsomal membranes isolated from several plant species, including Arabidopsis thaliana, Thellungiella halophila, Mesembryanthemum crystallinum, and Ananas comosus. However, we demonstrate, using V-ATPase-specific inhibitors, nonhydrolyzable ATP analogs, and ionophores to dissipate membrane potential, that the ATP-dependent migrational shift of membranes under FFZE is not due to activation of the V-ATPase. Addition of EDTA to chelate Mg2+, leading to the production of the tetravalent anionic form of ATP, resulted in a further enhancement of membrane migration toward the anode, and manipulation of cell surface charge by addition of polycations also influenced the ATP-dependent migration of membranes. We propose that ATP enhances the mobility of endomembranes by screening positive surface charges on the membrane surface.

Novel β-TCP Coated Titanium Nanofiber Surface for Enhanced Bone Growth.

PubMed

Lim, Hyun-Pil; Park, Sang-Won; Yun, Kwi-Dug; Park, Chan; Ji, Min-Kyung; Oh, Gye-Jeong; Lee, Jong-Tak; Lee, Kwangmin

2018-02-01

In this study, we examined the effect of β-tricalcium phosphate (β-TCP) coating on alkali-treated CP Grade II titanium surface via RF magnetron sputtering on osteoblast like cell (MC3T3-E1) viability and bone formation in rat tibia. The specimens were divided into three groups; commercially pure titanium (control group), alkali-treated titanium with nanofiber structure (NF group) and β-TCP coating on alkali-treated titanium with nanofiber structure (TNF group). The surface characteristics of specimens were observed under a field emission scanning electron microscope (FE-SEM), and contact angle was measured. The cell viability was assessed in vitro after 1 day, 3 days and 7 days. Implants of 2.0 mm diameter and 5.0 mm length were inserted into the tibia of rats. After 4 wks, the histomorphometric analysis was performed. Group NF and group TNF showed improved hydrophilicity of Ti. Group TNF showed significantly higher cell viability (P < 0.05) after 7 days. The bone to implant contact (BIC) ratio of the control group, NF group, and TNF group were 32.3%, 35.5%, and 63.9%, respectively. The study results suggested that β-TCP coated alkali-treated titanium surface via RF magnetron sputtering might be effective in implant dentistry due to enhanced hydrophilicity, improved cell response, and better osseointegration.

An SU-8-based microprobe with a nanostructured surface enhances neuronal cell attachment and growth

NASA Astrophysics Data System (ADS)

Kim, Eunhee; Kim, Jin-Young; Choi, Hongsoo

2017-12-01

Microprobes are used to repair neuronal injury by recording electrical signals from neuronal cells around the surface of the device. Following implantation into the brain, the immune response results in formation of scar tissue around the microprobe. However, neurons must be in close proximity to the microprobe to enable signal recording. A common reason for failure of microprobes is impaired signal recording due to scar tissue, which is not related to the microprobe itself. Therefore, the device-cell interface must be improved to increase the number of neurons in contact with the surface. In this study, we developed nanostructured SU-8 microprobes to support neuronal growth. Nanostructures of 200 nm diameter and depth were applied to the surface of microprobes, and the attachment and neurite outgrowth of PC12 cells on the microprobes were evaluated. Neuronal attachment and neurite outgrowth on the nanostructured microprobes were significantly greater than those on non-nanostructured microprobes. The enhanced neuronal attachment and neurite outgrowth on the nanostructured microprobes occurred in the absence of an adhesive coating, such as poly- l-lysine, and so may be useful for implantable devices for long-term use. Therefore, nanostructured microprobes can be implanted without adhesive coating, which can cause problems in vivo over the long term.

Laser surface treatment of polyamide and NiTi alloy and the effects on mesenchymal stem cell response

NASA Astrophysics Data System (ADS)

Waugh, D. G.; Lawrence, J.; Shukla, P.; Chan, C.; Hussain, I.; Man, H. C.; Smith, G. C.

2015-07-01

Mesenchymal stem cells (MSCs) are known to play important roles in development, post-natal growth, repair, and regeneration of mesenchymal tissues. What is more, surface treatments are widely reported to affect the biomimetic nature of materials. This paper will detail, discuss and compare laser surface treatment of polyamide (Polyamide 6,6), using a 60 W CO2 laser, and NiTi alloy, using a 100 W fiber laser, and the effects of these treatments on mesenchymal stem cell response. The surface morphology and composition of the polyamide and NiTi alloy were studied by scanning electron microscopy (SEM) and X-ray photoemission spectroscopy (XPS), respectively. MSC cell morphology cell counting and viability measurements were done by employing a haemocytometer and MTT colorimetric assay. The success of enhanced adhesion and spreading of the MSCs on each of the laser surface treated samples, when compared to as-received samples, is evidenced in this work.

Accelerated cell-surface interlocking on plasma polymer-modified porous ceramics.

PubMed

Rebl, Henrike; Finke, Birgit; Schmidt, Jürgen; Mohamad, Heba S; Ihrke, Roland; Helm, Christiane A; Nebe, J Barbara

2016-12-01

Excellent osseointegration of permanent implants is crucial for the long lasting success of the implantation. To improve the osseointegrative potential, bio-inert titanium alloy surfaces (Ti6Al4V) are modified by plasma chemical oxidation (PCO®) of the titanium-oxide layer to a non-stoichiometric, amorphous calcium phosphate layer. The native titanium-oxide film measuring only a few nanometers is converted by PCO® to a thick porous calcium phosphate layer of about 10μm. In a second step the PCO surface is combined with a cell adhesive plasma-polymerized allylamine (PPAAm) nano film (5 and 50nm). Independent of the PPAAm coating homogeneity, the human osteoblast-like MG-63 cells show a remarkable increase in cell size and well-developed filopodia. Analyses of the actin cytoskeleton reveal that the cells mold to the pore shape of the PPAAm-covered PCO, thereby establishing a strong attachment to the surface. Interestingly, we could demonstrate that even though our untreated PCO shows excellent hydrophilicity, this alone is not sufficient to facilitate fast cell spreading, but the positive surface charges mediated by PPAAm. This multilayer composite material guarantees enhanced interlocking of the cells with the porous surface. Copyright © 2016 Elsevier B.V. All rights reserved.

Surface passivation of InP solar cells with InAlAs layers

NASA Technical Reports Server (NTRS)

Jain, Raj K.; Flood, Dennis J.; Landis, Geoffrey A.

1993-01-01

The efficiency of indium phosphide solar cells is limited by high values of surface recombination. The effect of a lattice-matched In(0.52)Al(0.48)As window layer material for InP solar cells, using the numerical code PC-1D is investigated. It was found that the use of InAlAs layer significantly enhances the p(+)n cell efficiency, while no appreciable improvement is seen for n(+)p cells. The conduction band energy discontinuity at the heterojunction helps in improving the surface recombination. An optimally designed InP cell efficiency improves from 15.4 percent to 23 percent AMO for a 10 nm thick InAlAs layer. The efficiency improvement reduces with increase in InAlAs layer thickness, due to light absorption in the window layer.

Bone Marrow Transplantation Results in Human Donor Blood Cells Acquiring and Displaying Mouse Recipient Class I MHC and CD45 Antigens on Their Surface

PubMed Central

Yamanaka, Nobuko; Wong, Christine J.; Gertsenstein, Marina; Casper, Robert F.; Nagy, Andras; Rogers, Ian M.

2009-01-01

Background Mouse models of human disease are invaluable for determining the differentiation ability and functional capacity of stem cells. The best example is bone marrow transplants for studies of hematopoietic stem cells. For organ studies, the interpretation of the data can be difficult as transdifferentiation, cell fusion or surface antigen transfer (trogocytosis) can be misinterpreted as differentiation. These events have not been investigated in hematopoietic stem cell transplant models. Methodology/Principal Findings In this study we investigated fusion and trogocytosis involving blood cells during bone marrow transplantation using a xenograft model. We report that using a standard SCID repopulating assay almost 100% of the human donor cells appear as hybrid blood cells containing both mouse and human surface antigens. Conclusion/Significance Hybrid cells are not the result of cell-cell fusion events but appear to be due to efficient surface antigen transfer, a process referred to as trogocytosis. Antigen transfer appears to be non-random and includes all donor cells regardless of sub-type. We also demonstrate that irradiation preconditioning enhances the frequency of hybrid cells and that trogocytosis is evident in non-blood cells in chimera mice. PMID:20046883

Reproducible surface-enhanced Raman quantification of biomarkers in multicomponent mixtures.

PubMed

De Luca, Anna Chiara; Reader-Harris, Peter; Mazilu, Michael; Mariggiò, Stefania; Corda, Daniela; Di Falco, Andrea

2014-03-25

Direct and quantitative detection of unlabeled glycerophosphoinositol (GroPIns), an abundant cytosolic phosphoinositide derivative, would allow rapid evaluation of several malignant cell transformations. Here we report label-free analysis of GroPIns via surface-enhanced Raman spectroscopy (SERS) with a sensitivity of 200 nM, well below its apparent concentration in cells. Crucially, our SERS substrates, based on lithographically defined gold nanofeatures, can be used to predict accurately the GroPIns concentration even in multicomponent mixtures, avoiding the preliminary separation of individual compounds. Our results represent a critical step toward the creation of SERS-based biosensor for rapid, label-free, and reproducible detection of specific molecules, overcoming limits of current experimental methods.

New Monoclonal Antibodies to Defined Cell Surface Proteins on Human Pluripotent Stem Cells.

PubMed

O'Brien, Carmel M; Chy, Hun S; Zhou, Qi; Blumenfeld, Shiri; Lambshead, Jack W; Liu, Xiaodong; Kie, Joshua; Capaldo, Bianca D; Chung, Tung-Liang; Adams, Timothy E; Phan, Tram; Bentley, John D; McKinstry, William J; Oliva, Karen; McMurrick, Paul J; Wang, Yu-Chieh; Rossello, Fernando J; Lindeman, Geoffrey J; Chen, Di; Jarde, Thierry; Clark, Amander T; Abud, Helen E; Visvader, Jane E; Nefzger, Christian M; Polo, Jose M; Loring, Jeanne F; Laslett, Andrew L

2017-03-01

The study and application of human pluripotent stem cells (hPSCs) will be enhanced by the availability of well-characterized monoclonal antibodies (mAbs) detecting cell-surface epitopes. Here, we report generation of seven new mAbs that detect cell surface proteins present on live and fixed human ES cells (hESCs) and human iPS cells (hiPSCs), confirming our previous prediction that these proteins were present on the cell surface of hPSCs. The mAbs all show a high correlation with POU5F1 (OCT4) expression and other hPSC surface markers (TRA-160 and SSEA-4) in hPSC cultures and detect rare OCT4 positive cells in differentiated cell cultures. These mAbs are immunoreactive to cell surface protein epitopes on both primed and naive state hPSCs, providing useful research tools to investigate the cellular mechanisms underlying human pluripotency and states of cellular reprogramming. In addition, we report that subsets of the seven new mAbs are also immunoreactive to human bone marrow-derived mesenchymal stem cells (MSCs), normal human breast subsets and both normal and tumorigenic colorectal cell populations. The mAbs reported here should accelerate the investigation of the nature of pluripotency, and enable development of robust cell separation and tracing technologies to enrich or deplete for hPSCs and other human stem and somatic cell types. Stem Cells 2017;35:626-640. © 2016 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Cell surface engineering of microorganisms towards adsorption of heavy metals.

PubMed

Li, Peng-Song; Tao, Hu-Chun

2015-06-01

Heavy metal contamination has become a worldwide environmental concern due to its toxicity, non-degradability and food-chain bioaccumulation. Conventional physical and chemical treatment methods for heavy metal removal have disadvantages such as cost-intensiveness, incomplete removal, secondary pollution and the lack of metal specificity. Microbial biomass-based biosorption is one of the approaches gaining increasing attention because it is effective, cheap, and environmental friendly and can work well at low concentrations. To enhance the adsorption properties of microbial cells to heavy metal ions, the cell surface display of various metal-binding proteins/peptides have been performed using a cell surface engineering approach. The surface engineering of Gram-negative bacteria, Gram-positive bacteria and yeast towards the adsorption of heavy metals are reviewed in this article. The problems and future perspectives of this technology are discussed.

Ion-implanted polytetrafluoroethylene enhances Saccharomyces cerevisiae biofilm formation for improved immobilization

PubMed Central

Tran, Clara T. H.; Kondyurin, Alexey; Hirsh, Stacey L.; McKenzie, David R.; Bilek, Marcela M. M.

2012-01-01

The surface of polytetrafluoroethylene (PTFE) was modified using plasma immersion ion implantation (PIII) with the aim of improving its ability to immobilize yeast. The density of immobilized cells on PIII-treated and -untreated PTFE was compared as a function of incubation time over 24 h. Rehydrated yeast cells attached to the PIII-treated PTFE surface more rapidly, with higher density, and greater attachment strength than on the untreated surface. The immobilized yeast cells were removed mechanically or chemically with sodium hydroxide and the residues left on the surfaces were analysed with Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). The results revealed that the mechanism of cell attachment on both surfaces differs and a model is presented for each. Rapid attachment on the PIII-treated surface occurs through covalent bonds of cell wall proteins and the radicals on the treated surface. In contrast, on the untreated surface, only physisorbed molecules were found in the residue and lipids were more highly concentrated than proteins. The presence of lipids in the residue was found to be a consequence of damage to the plasma membrane during the rehydration process and the increased cell stress was also apparent by the amount of Hsp12 in the protein residue. The immobilized yeast cells on PIII-treated PTFE were found to be as active as yeast cells in suspension. PMID:22696486

Development of nanoparticle applications in cell imaging, bioassay and reactive oxygen species detection based on surface-enhanced raman spectroscopy

NASA Astrophysics Data System (ADS)

Huang, Yiming

Surface-enhanced Raman scattering (SERS) has been developed over forty years with a wide variety of applications. Signals enhanced from single molecule absorbed on the surface of metallic nanoparticles can be up to 14-order-of-magnitude. This is due to the resonance between the optical field and surface plasmon of the metal substrate. Nanoshells have been chosen as substrates since they do not need to pre-aggregate due to their tunable optical property. We developed Raman imaging system by incorporating functionalized nanoshells, cells and SERS. Nanoshells have been coated with different self-assembled monolayers containing poly(ethylene glycol) (PEG) molecules. Probes have been designed by coating nanoshells with Raman active PEG molecules and delivered into macrophage cells. The imaging technique requires less preparation and provides the information of nanoshells in semi-quantitative way in vitro. We developed half-sandwich bioassay by detecting low volume of antigens on nitrocellulose membrane, detected by SERS. Antibodies were grafted to the surface of nanoshells and were conjugated to the antigens on the nitrocellulose membrane for detection. Raman active PEGs were conjugated onto the metal substrate for recognition and quantification. The benefits of this assay are that it is faster, easier to execute and requires less volume of antigen to conjugate onto the substrate. We also developed reactive oxygen species (ROS) sensors by incubating PEGs and either 4-nitrobenzenethiol (4-NBT) or 4-mercaptophenol (4-MP) on the surface of nanoshells. By analyzing the changes of SERS spectrum, the production of hydroxyl radicals produced in the Fenton reaction can be tracked in low concentrations. The sensors were designed to track ROS production within cells when they are under oxidative stress. The methods developed in this thesis are versatile, and can be broadly applied to the study of different subtracts, such as gold colloid.

Enhancement of Cell Attachment to a Substrate Coated with Oral Bacterial Endotoxin by Plasma Fibronectin

DTIC Science & Technology

1983-01-01

root surfaces is unpredict- human gingival fibroblasts (Aleo. De Renzis able (World Workshop in PeriodonticN & Farber 1975). Clearly, if new attachment...1966). of periodontal tissues to a tooth is to be A preliminary characterization of the made possible, therapeutic measures must FIBRONECTIN ENHANCES...CELL ATTACHMENT 155 list he developed it remove. alter. or other- population of bacteria wsithin the gingival wise inactivate the toxic principle of

Light trapping and electrical transport in thin-film solar cells with randomly rough textures

NASA Astrophysics Data System (ADS)

Kowalczewski, Piotr; Bozzola, Angelo; Liscidini, Marco; Claudio Andreani, Lucio

2014-05-01

Using rigorous electro-optical calculations, we predict a significant efficiency enhancement in thin-film crystalline silicon (c-Si) solar cells with rough interfaces. We show that an optimized rough texture allows one to reach the Lambertian limit of absorption in a wide absorber thickness range from 1 to 100 μm. The improvement of efficiency due to the roughness is particularly substantial for thin cells, for which light trapping is crucial. We consider Auger, Shockley-Read-Hall (SRH), and surface recombination, quantifying the importance of specific loss mechanisms. When the cell performance is limited by intrinsic Auger recombination, the efficiency of 24.4% corresponding to the wafer-based PERL cell can be achieved even if the absorber thickness is reduced from 260 to 10 μm. For cells with material imperfections, defect-based SRH recombination contributes to the opposite trends of short-circuit current and open-circuit voltage as a function of the absorber thickness. By investigating a wide range of SRH parameters, we determine an optimal absorber thickness as a function of material quality. Finally, we show that the efficiency enhancement in textured cells persists also in the presence of surface recombination. Indeed, in our design the efficiency is limited by recombination at the rear (silicon absorber/back reflector) interface, and therefore it is possible to engineer the front surface to a large extent without compromising on efficiency.

Development of functional biointerfaces by surface modification of polydimethylsiloxane with bioactive chlorogenic acid.

PubMed

Wu, Ming; He, Jia; Ren, Xiao; Cai, Wen-Sheng; Fang, Yong-Chun; Feng, Xi-Zeng

2014-04-01

The effect of physicochemical surface properties and chemical structure on the attachment and viability of bacteria and mammalian cells has been extensively studied for the development of biologically relevant applications. In this study, we report a new approach that uses chlorogenic acid (CA) to modify the surface wettability, anti-bacterial activity and cell adhesion properties of polydimethylsiloxane (PDMS). The chemical structure of the surface was obtained by X-ray photoelectron spectroscopy (XPS), the roughness was measured by atomic force microscopy (AFM), and the water contact angle was evaluated for PDMS substrates both before and after CA modification. Molecular modelling showed that the modification was predominately driven by van der Waals and electrostatic interactions. The exposed quinic-acid moiety improved the hydrophilicity of CA-modified PDMS substrates. The adhesion and viability of E. coli and HeLa cells were investigated using fluorescence and phase contrast microscopy. Few viable bacterial cells were found on CA-coated PDMS surfaces compared with unmodified PDMS surfaces. Moreover, HeLa cells exhibited enhanced adhesion and increased spreading on the modified PDMS surface. Thus, CA-coated PDMS surfaces reduced the ratio of viable bacterial cells and increased the adhesion of HeLa cells. These results contribute to the purposeful design of anti-bacterial surfaces for medical device use. Copyright © 2013 Elsevier B.V. All rights reserved.

Hybrid micro/nano-topography of a TiO2 nanotube-coated commercial zirconia femoral knee implant promotes bone cell adhesion in vitro.

PubMed

Frandsen, Christine J; Noh, Kunbae; Brammer, Karla S; Johnston, Gary; Jin, Sungho

2013-07-01

Various approaches have been studied to engineer the implant surface to enhance bone in-growth properties, particularly using micro- and nano-topography. In this study, the behavior of osteoblast (bone) cells was analyzed in response to a titanium oxide (TiO2) nanotube-coated commercial zirconia femoral knee implant consisting of a combined surface structure of a micro-roughened surface with the nanotube coating. The osteoblast cells demonstrated high degrees of adhesion and integration into the surface of the nanotube-coated implant material, indicating preferential cell behavior on this surface when compared to the bare implant. The results of this brief study provide sufficient evidence to encourage future studies. The development of such hierarchical micro- and nano-topographical features, as demonstrated in this work, can provide insightful designs for advanced bone-inducing material coatings on ceramic orthopedic implant surfaces. Copyright © 2013 Elsevier B.V. All rights reserved.

Biological Functionalization of Drug Delivery Carriers to Bypass Size Restrictions of Receptor-Mediated Endocytosis Independently from Receptor Targeting

PubMed Central

Ansar, Maria; Serrano, Daniel; Papademetriou, Iason; Bhowmick, Tridib Kumar; Muro, Silvia

2014-01-01

Targeting of drug carriers to cell-surface receptors involved in endocytosis is commonly used for intracellular drug delivery. However, most endocytic receptors mediate uptake via clathrin or caveolar pathways associated with ≤200-nm vesicles, restricting carrier design. We recently showed that endocytosis mediated by intercellular adhesion molecule 1 (ICAM-1), which differs from clathrin- and caveolar-mediated pathways, allows uptake of nano- and micro-carriers in cell culture and in vivo due to recruitment of cellular sphingomyelinases to the plasmalemma. This leads to ceramide generation at carrier binding sites and formation of actin stress-fibers, enabling engulfment and uptake of a wide size-range of carriers. Here we adapted this paradigm to enhance uptake of drug carriers targeted to receptors associated with size-restricted pathways. We coated sphingomyelinase onto model (polystyrene) submicro- and micro-carriers targeted to clathrin-associated mannose-6-phosphate receptor. In endothelial cells, this provided ceramide enrichment at the cell surface and actin stress-fiber formation, modifying the uptake pathway and enhancing carrier endocytosis without affecting targeting, endosomal transport, cell-associated degradation, or cell viability. This improvement depended on the carrier size and enzyme dose, and similar results were observed for other receptors (transferrin receptor) and cell types (epithelial cells). This phenomenon also enhanced tissue accumulation of carriers after intravenous injection in mice. Hence, it is possible to maintain targeting toward a selected receptor while bypassing natural size-restrictions of its associated endocytic route by functionalization of drug carriers with biological elements mimicking the ICAM-1 pathway. This strategy holds considerable promise to enhance flexibility of design of targeted drug delivery systems. PMID:24237309

Biological functionalization of drug delivery carriers to bypass size restrictions of receptor-mediated endocytosis independently from receptor targeting.

PubMed

Ansar, Maria; Serrano, Daniel; Papademetriou, Iason; Bhowmick, Tridib Kumar; Muro, Silvia

2013-12-23

Targeting of drug carriers to cell-surface receptors involved in endocytosis is commonly used for intracellular drug delivery. However, most endocytic receptors mediate uptake via clathrin or caveolar pathways associated with ≤200-nm vesicles, restricting carrier design. We recently showed that endocytosis mediated by intercellular adhesion molecule 1 (ICAM-1), which differs from clathrin- and caveolae-mediated pathways, allows uptake of nano- and microcarriers in cell culture and in vivo due to recruitment of cellular sphingomyelinases to the plasmalemma. This leads to ceramide generation at carrier binding sites and formation of actin stress-fibers, enabling engulfment and uptake of a wide size-range of carriers. Here we adapted this paradigm to enhance uptake of drug carriers targeted to receptors associated with size-restricted pathways. We coated sphingomyelinase onto model (polystyrene) submicro- and microcarriers targeted to clathrin-associated mannose-6-phosphate receptor. In endothelial cells, this provided ceramide enrichment at the cell surface and actin stress-fiber formation, modifying the uptake pathway and enhancing carrier endocytosis without affecting targeting, endosomal transport, cell-associated degradation, or cell viability. This improvement depended on the carrier size and enzyme dose, and similar results were observed for other receptors (transferrin receptor) and cell types (epithelial cells). This phenomenon also enhanced tissue accumulation of carriers after intravenous injection in mice. Hence, it is possible to maintain targeting toward a selected receptor while bypassing natural size restrictions of its associated endocytic route by functionalization of drug carriers with biological elements mimicking the ICAM-1 pathway. This strategy holds considerable promise to enhance flexibility of design of targeted drug delivery systems.

Reaction and Aggregation Dynamics of Cell Surface Receptors

NASA Astrophysics Data System (ADS)

Wang, Michelle Dong

This dissertation is composed of both theoretical and experimental studies of cell surface receptor reaction and aggregation. Project I studies the reaction rate enhancement due to surface diffusion of a bulk dissolved ligand with its membrane embedded target, using numerical calculations. The results show that the reaction rate enhancement is determined by ligand surface adsorption and desorption kinetic rates, surface and bulk diffusion coefficients, and geometry. In particular, we demonstrate that the ligand surface adsorption and desorption kinetic rates, rather than their ratio (the equilibrium constant), are important in rate enhancement. The second and third projects are studies of acetylcholine receptor clusters on cultured rat myotubes using fluorescence techniques after labeling the receptors with tetramethylrhodamine -alpha-bungarotoxin. The second project studies when and where the clusters form by making time-lapse movies. The movies are made from overlay of the pseudocolored total internal reflection fluorescence (TIRF) images of the cluster, and the schlieren images of the cell cultures. These movies are the first movies made using TIRF, and they clearly show the cluster formation from the myoblast fusion, the first appearance of clusters, and the eventual disappearance of clusters. The third project studies the fine structural features of individual clusters observed under TIRF. The features were characterized with six parameters by developing a novel fluorescence technique: spatial fluorescence autocorrelation. These parameters were then used to study the feature variations with age, and with treatments of drugs (oligomycin and carbachol). The results show little variation with age. However, drug treatment induced significant changes in some parameters. These changes were different for oligomycin and carbachol, which indicates that the two drugs may eliminate clusters through different mechanisms.

Current Approach in Surface Plasmons for Thin Film and Wire Array Solar Cell Applications

PubMed Central

Zhou, Keya; Guo, Zhongyi; Liu, Shutian; Lee, Jung-Ho

2015-01-01

Surface plasmons, which exist along the interface of a metal and a dielectric, have been proposed as an efficient alternative method for light trapping in solar cells during the past ten years. With unique properties such as superior light scattering, optical trapping, guide mode coupling, near field concentration, and hot-electron generation, metallic nanoparticles or nanostructures can be tailored to a certain geometric design to enhance solar cell conversion efficiency and to reduce the material costs. In this article, we review current approaches on different kinds of solar cells, such as crystalline silicon (c-Si) and amorphous silicon (a-Si) thin film solar cells, organic solar cells, nanowire array solar cells, and single nanowire solar cells. PMID:28793457

Interactions of Histophilus somni with Host Cells.

PubMed

Behling-Kelly, Erica; Rivera-Rivas, Jose; Czuprynski, Charles J

2016-01-01

Histophilus somni resides as part of the normal microflora in the upper respiratory tract of healthy cattle. From this site, the organism can make its way into the lower respiratory tract, where it is one of the important bacterial agents of the respiratory disease complex. If H. somni cells disseminate to the bloodstream, they frequently result in thrombus formation. A series of in vitro investigations have examined potential mechanisms that might contribute to such thrombus formation. Earlier work showed that H. somni can stimulate some bovine endothelial cells to undergo apoptosis. More recent studies indicate that H. somni stimulates endothelial cell tissue factor activity and disrupts intercellular junctions. The net effect is to enhance procoagulant activity on the endothelium surface and to make the endothelial monolayer more permeable to molecules, leukocytes, and perhaps H. somni cells. H. somni also activates bovine platelets, which also can enhance tissue factor activity on the endothelium surface. When exposed to H. somni, bovine neutrophils and mononuclear phagocytes form extracellular traps in vitro. Ongoing research is investigating how the interplay among endothelial cells, platelets, and leukocytes might contribute to the thrombus formation seen in infected cattle.

Cell-based cartilage repair strategies in the horse.

PubMed

Ortved, Kyla F; Nixon, Alan J

2016-02-01

Damage to the articular cartilage surface is common in the equine athlete and, due to the poor intrinsic healing capabilities of cartilage, can lead to osteoarthritis (OA). Joint disease and OA are the leading cause of retirement in equine athletes and currently there are no effective treatments to stop the progression of OA. Several different cell-based strategies have been investigated to bolster the weak regenerative response of chondrocytes. Such techniques aim to restore the articular surface and prevent further joint degradation. Cell-based cartilage repair strategies include enhancement of endogenous repair mechanisms by recruitment of stem cells from the bone marrow following perforation of the subchondral bone plate; osteochondral implantation; implantation of chondrocytes that are maintained in defects by either a membrane cover or scaffold, and transplantation of mesenchymal stem cells into cartilage lesions. More recently, bioengineered cartilage and scaffoldless cartilage have been investigated for enhancing repair. This review article focuses on the multitude of cell-based repair techniques for cartilage repair across several species, with special attention paid to the horse. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fortifying the Bone-Implant Interface Part 1: An In Vitro Evaluation of 3D-Printed and TPS Porous Surfaces.

PubMed

MacBarb, Regina F; Lindsey, Derek P; Bahney, Chelsea S; Woods, Shane A; Wolfe, Mark L; Yerby, Scott A

2017-01-01

An aging society and concomitant rise in the incidence of impaired bone health have led to the need for advanced osteoconductive spinal implant surfaces that promote greater biological fixation ( e.g. for interbody fusion cages, sacroiliac joint fusion implants, and artificial disc replacements). Additive manufacturing, i.e. 3D-printing, may improve bone integration by generating biomimetic spinal implant surfaces that mimic bone morphology. Such surfaces may foster an enhanced cellular response compared to traditional implant surfacing processes. This study investigated the response of human osteoblasts to additive manufactured (AM) trabecular-like titanium implant surfaces compared to traditionally machined base material with titanium plasma spray (TPS) coated surfaces, with and without a nanocrystalline hydroxyapatite (HA) coating. For TPS-coated discs, wrought Ti6Al4V ELI was machined and TPS-coating was applied. For AM discs, Ti6Al4V ELI powder was 3D-printed to form a solid base and trabecular-like porous surface. The HA-coating was applied via a precipitation dip-spin method. Surface porosity, pore size, thickness, and hydrophilicity were characterized. Initial cell attachment, proliferation, alkaline phosphatase (ALP) activity, and calcium production of hFOB cells ( n =5 per group) were measured. Cells on AM discs exhibited expedited proliferative activity. While there were no differences in mean ALP expression and calcium production between TPS and AM discs, calcium production on the AM discs trended 48% higher than on TPS discs ( p =0.07). Overall, HA-coating did not further enhance results compared to uncoated TPS and AM discs. Results demonstrate that additive manufacturing allows for controlled trabecular-like surfaces that promote earlier cell proliferation and trends toward higher calcium production than TPS coating. Results further showed that nanocrystalline HA may not provide an advantage on porous titanium surfaces. Additive manufactured porous titanium surfaces may induce a more osteogenic environment compared to traditional TPS, and thus present as an attractive alternative to TPS-coating for orthopedic spinal implants.

Use of a corrugated surface to enhance radiation tolerance in a GaAs solar cell

NASA Technical Reports Server (NTRS)

Leon, Rosa P.; Piszczor, Michael F., Jr.

1985-01-01

The use of a corrugated surface on a GaAs solar cell and its effects on radiation resistance were studied. A compute code was developed to determine the performance of the cell for various geometric parameters. The large optical absorption coefficient of GaAs allows grooves to be only 4-5 micrometers deep. Using accepted material parameters for GaAs solar cells the theoretical performances were compared for various corrugated cells before and after minority carrier diffusion length degradation. The total power output was maximized for both n(+)/p and p(+)/n cells. Optimum values of 1.0-1.5 and 5.0 micrometers for groove and ridge widths respectively were determined.

Adenosine Deaminase Enhances the Immunogenicity of Human Dendritic Cells from Healthy and HIV-Infected Individuals

PubMed Central

Massanella, Marta; Rodríguez-García, Marta; Blanco, Julià; Gatell, José M.; García, Felipe; Gallart, Teresa; Lluis, Carme; Mallol, Josefa

2012-01-01

ADA is an enzyme implicated in purine metabolism, and is critical to ensure normal immune function. Its congenital deficit leads to severe combined immunodeficiency (SCID). ADA binding to adenosine receptors on dendritic cell surface enables T-cell costimulation through CD26 crosslinking, which enhances T-cell activation and proliferation. Despite a large body of work on the actions of the ecto-enzyme ADA on T-cell activation, questions arise on whether ADA can also modulate dendritic cell maturation. To this end we investigated the effects of ADA on human monocyte derived dendritic cell biology. Our results show that both the enzymatic and non-enzymatic activities of ADA are implicated in the enhancement of CD80, CD83, CD86, CD40 and CCR7 expression on immature dendritic cells from healthy and HIV-infected individuals. These ADA-mediated increases in CD83 and costimulatory molecule expression is concomitant to an enhanced IL-12, IL-6, TNF-α, CXCL8(IL-8), CCL3(MIP1-α), CCL4(MIP-1β) and CCL5(RANTES) cytokine/chemokine secretion both in healthy and HIV-infected individuals and to an altered apoptotic death in cells from HIV-infected individuals. Consistently, ADA-mediated actions on iDCs are able to enhance allogeneic CD4 and CD8-T-cell proliferation, globally yielding increased iDC immunogenicity. Taken together, these findings suggest that ADA would promote enhanced and correctly polarized T-cell responses in strategies targeting asymptomatic HIV-infected individuals. PMID:23240012

Novel materials to enhance corneal epithelial cell migration on keratoprosthesis.

PubMed

Karkhaneh, Akbar; Mirzadeh, Hamid; Ghaffariyeh, Alireza; Ebrahimi, Abdolali; Honarpisheh, Nazafarin; Hosseinzadeh, Masud; Heidari, Mohammad Hossein

2011-03-01

To introduce a new modification for silicone optical core Keratoprosthesis. Using mixtures of 2-hydroxyethyl methacrylate and acrylic acid polydimethylsiloxane (PDMS) films were modified with two-step oxygen plasma treatment, and then type I collagen was immobilised onto this modified surfaces. Both the biocompatibility of the modified films and cell behaviour on the surface of these films were investigated by in vitro tests, and formation of epithelial cell layer was evaluated by implantation of the modified films in the corneas of 10 rabbits. In vitro studies indicated that the number of attached and proliferated cells onto modified PDMS in comparison with the unmodified PDMS significantly increased. Histological studies showed that corneal epithelial cells migrated on the anterior surface of the modified films after 1week. The corneal epithelial cell formed an incomplete monolayer cellular sheet after 10days. A complete epithelialisation on the modified surface was formed after 21days. The epithelial layer persisted on the anterior surface of implant after 1-month and 3-month follow-up. This method may have potential use in silicone optical core Keratoprosthesis.

Cell behavior on gallium nitride surfaces: peptide affinity attachment versus covalent functionalization.

PubMed

Foster, Corey M; Collazo, Ramon; Sitar, Zlatko; Ivanisevic, Albena

2013-07-02

Gallium nitride is a wide band gap semiconductor that demonstrates a unique set of optical and electrical properties as well as aqueous stability and biocompatibility. This combination of properties makes gallium nitride a strong candidate for use in chemical and biological applications such as sensors and neural interfaces. Molecular modification can be used to enhance the functionality and properties of the gallium nitride surface. Here, gallium nitride surfaces were functionalized with a PC12 cell adhesion promoting peptide using covalent and affinity driven attachment methods. The covalent scheme proceeded by Grignard reaction and olefin metathesis while the affinity driven scheme utilized the recognition peptide isolated through phage display. This study shows that the method of attaching the adhesion peptide influences PC12 cell adhesion and differentiation as measured by cell density and morphological analysis. Covalent attachment promoted monolayer and dispersed cell adhesion while affinity driven attachment promoted multilayer cell agglomeration. Higher cell density was observed on surfaces modified using the recognition peptide. The results suggest that the covalent and affinity driven attachment methods are both suitable for promoting PC12 cell adhesion to the gallium nitride surface, though each method may be preferentially suited for distinct applications.

The B7-1 Cytoplasmic Tail Enhances Intracellular Transport and Mammalian Cell Surface Display of Chimeric Proteins in the Absence of a Linear ER Export Motif

PubMed Central

Lin, Yi-Chieh; Chen, Bing-Mae; Lu, Wei-Cheng; Su, Chien-I; Prijovich, Zeljko M.; Chung, Wen-Chuan; Wu, Pei-Yu; Chen, Kai-Chuan; Lee, I-Chiao; Juan, Ting-Yi; Roffler, Steve R.

2013-01-01

Membrane-tethered proteins (mammalian surface display) are increasingly being used for novel therapeutic and biotechnology applications. Maximizing surface expression of chimeric proteins on mammalian cells is important for these applications. We show that the cytoplasmic domain from the B7-1 antigen, a commonly used element for mammalian surface display, can enhance the intracellular transport and surface display of chimeric proteins in a Sar1 and Rab1 dependent fashion. However, mutational, alanine scanning and deletion analysis demonstrate the absence of linear ER export motifs in the B7 cytoplasmic domain. Rather, efficient intracellular transport correlated with the presence of predicted secondary structure in the cytoplasmic tail. Examination of the cytoplasmic domains of 984 human and 782 mouse type I transmembrane proteins revealed that many previously identified ER export motifs are rarely found in the cytoplasmic tail of type I transmembrane proteins. Our results suggest that efficient intracellular transport of B7 chimeric proteins is associated with the structure rather than to the presence of a linear ER export motif in the cytoplasmic tail, and indicate that short (less than ~ 10-20 amino acids) and unstructured cytoplasmic tails should be avoided to express high levels of chimeric proteins on mammalian cells. PMID:24073236

Physics of a rapid CD4 lymphocyte count with colloidal gold.

PubMed

Hansen, P; Barry, D; Restell, A; Sylvia, D; Magnin, O; Dombkowski, D; Preffer, F

2012-03-01

The inherent surface charges and small diameters that confer colloidal stability to gold particle conjugates (immunogold) are detrimental to rapid cell surface labeling and distinct cluster definition in flow cytometric light scatter assays. Although the inherent immunogold surface charge prevents self aggregation when stored in liquid suspension, it also slows binding to cells to timeframes of hours and inhibits cell surface coverage. Although the small diameter of immunogold particles prevents settling when in liquid suspension, small particles have small light scattering cross sections and weak light scatter signals. We report a new, small particle lyophilized immunogold reagent that maintains activity after 42°C storage for a year and can be rapidly dissolved into stable liquid suspension for use in labelling cells with larger particle aggregates that have enhanced scattering cross section. Labeling requires less than 1 min at 20°C, which is ∼30 times faster than customary fluorescent antibody labeling. The labeling step involves neutralizing the surface charge of immunogold and creating specifically bound aggregates of gold on the cell surface. This process provides distinct side-scatter cluster separation with blue laser light at 488 nm, which is further improved by using red laser light at 640 nm. Similar comparisons using LED light sources showed less improvement with red light, thereby indicating that coherent light scatter is of significance in enhancing side-scatter cluster separation. The physical principles elucidated here for this technique are compatible with most flow cytometers; however, future studies of its clinical efficacy should be of primary interest in point-of-care applications where robust reagents and rapid results are important. Copyright © 2011 International Society for Advancement of Cytometry.

RGD-conjugated rod-like viral nanoparticles on 2D scaffold improved bone differentiation of mesenchymal stem cells

NASA Astrophysics Data System (ADS)

Wang, Qian; Pongkwan, Sitasuwan; Lee, L.; Li, Kai; Nguyen, Huong

2014-05-01

Viral nanoparticles have uniform and well-defined nano-structures and can be produced in large quantities. Several plant viral nanoparticles have been tested in biomedical applications due to the lack of mammalian cell infectivity. We are particularly interested in using Tobacco mosaic virus (TMV), which has been demonstrated to enhance bone tissue regeneration, as a tuneable nanoscale building block for biomaterials development. Unmodified TMV particles have been shown to accelerate osteogenic differentiation of adult stem cells by synergistically upregulating BMP2 and IBSP expression with dexamethasone. However, the lack of affinity to mammalian cell surface resulted in low initial cell adhesion. In this study, to increase cell binding capacity of TMV based material the chemical functionalization of TMV with arginine-glycine-aspartic acid (RGD) peptide was explored. An azide-derivatized RGD peptide was “clicked” to tyrosine residues on TMV outer surface via an efficient copper(I) catalysed azide-alkyne cycloaddition reaction. The ligand spacing is calculated to be 2-4 nm, which could offer a polyvalent ligand clustering effect for enhanced cell receptor signalling, further promoting the proliferation and osteogenic differentiation of bone marrow derived mesenchymal stem cells.

An Hsp70 peptide initiates NK cell killing of leukemic blasts after stem cell transplantation.

PubMed

Gross, Catharina; Holler, Ernst; Stangl, Stefan; Dickinson, Anne; Pockley, A Graham; Asea, Alexzander A; Mallappa, Nagaraja; Multhoff, Gabriele

2008-04-01

In contrast to solid tumors, leukemic blasts frequently present both Hsp70 and HLA-E on their cell surface and thereby present activating and inhibitory signals to CD94(+) NK cells. In the first 12 months after stem cell transplantation (SCT) CD94(+) NK cells clearly dominate over CD3(+)/CD16(-)/56(-) T and CD3(+)/CD16(+)/56(+) NK-like T cells. An incubation of post-SCT-derived peripheral blood lymphocytes with the Hsp70 peptide TKD and IL-15 enhances the cell surface density of CD56/CD94 and initiates the cytolytic activity of NK cells against Hsp70/HLA-E double-positive autologous and allogeneic leukemic blasts. Hsp70 was identified as the target structure for TKD-activated NK cells.

Perchlorates on Mars enhance the bacteriocidal effects of UV light.

PubMed

Wadsworth, Jennifer; Cockell, Charles S

2017-07-06

Perchlorates have been identified on the surface of Mars. This has prompted speculation of what their influence would be on habitability. We show that when irradiated with a simulated Martian UV flux, perchlorates become bacteriocidal. At concentrations associated with Martian surface regolith, vegetative cells of Bacillus subtilis in Martian analogue environments lost viability within minutes. Two other components of the Martian surface, iron oxides and hydrogen peroxide, act in synergy with irradiated perchlorates to cause a 10.8-fold increase in cell death when compared to cells exposed to UV radiation after 60 seconds of exposure. These data show that the combined effects of at least three components of the Martian surface, activated by surface photochemistry, render the present-day surface more uninhabitable than previously thought, and demonstrate the low probability of survival of biological contaminants released from robotic and human exploration missions.

Effect of Functional Groups on Biodegradation and Pre-osteoblastic Cell Response on the Plasma-Polymerized Magnesium Surface

NASA Astrophysics Data System (ADS)

Ko, Yeong-Mu; Lee, Kang; Kim, Byung-Hoon

2013-01-01

Magnesium (Mg) is light, has biocompatibility, and has mechanical properties close to those of natural bone. However, pure Mg severely corrodes in a physiological environment, which may result in fracture prior to substantial tissue healing. In this study, the Mg surface was modified by depositing a thin polymeric film containing COOH, NH2, and OH groups through plasma polymerization of acrylic acid, allyl amine, and allyl alcohol in order to improve its anticorrosion and bioactive properties. The -COOH group had a significant effect on bonelike apatite formation compared with -NH2 and -OH. It was also concluded that a bonelike-apatite formed COOH/Mg surface was more effective for reducing biodegradation rate than the other surfaces. The results of in vitro cell test revealed significantly enhanced cell proliferation and differentiation on the COOH/Mg and NH2/Mg surfaces compared with other surfaces.

Enhanced preferential cytotoxicity through surface modification: synthesis, characterization and comparative in vitro evaluation of TritonX-100 modified and unmodified zinc oxide nanoparticles in human breast cancer cell (MDA-MB-231).

PubMed

Kc, Biplab; Paudel, Siddhi Nath; Rayamajhi, Sagar; Karna, Deepak; Adhikari, Sandeep; Shrestha, Bhupal G; Bisht, Gunjan

2016-01-01

Nanoparticles (NPs) are receiving increasing interest in biomedical research owing to their comparable size with biomolecules, novel properties and easy surface engineering for targeted therapy, drug delivery and selective treatment making them a better substituent against traditional therapeutic agents. ZnO NPs, despite other applications, also show selective anticancer property which makes it good option over other metal oxide NPs. ZnO NPs were synthesized by chemical precipitation technique, and then surface modified using Triton X-100. Comparative study of cytotoxicity of these modified and unmodified NPs on breast cancer cell line (MDA-MB-231) and normal cell line (NIH 3T3) were carried out. ZnO NPsof average size 18.67 ± 2.2 nm and Triton-X modified ZnO NPs of size 13.45 ± 1.42 nm were synthesized and successful characterization of synthesized NPs was done by Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), transmission electron microscopy (TEM) analysis. Surface modification of NPs was proved by FT-IR analysis whereas structure and size by XRD analysis. Morphological analysis was done by TEM. Cell viability assay showed concentration dependent cytotoxicity of ZnO NPs in breast cancer cell line (MDA-MB-231) whereas no positive correlation was found between cytotoxicity and increasing concentration of stress in normal cell line (NIH 3T3) within given concentration range. Half maximum effective concentration (EC50) value for ZnO NPs was found to be 38.44 µg/ml and that of modified ZnO NPs to be 55.24 µg/ml for MDA-MB-231. Crystal violet (CV) staining image showed reduction in number of viable cells in NPs treated cell lines further supporting this result. DNA fragmentation assay showed fragmented bands indicating that the mechanism of cytotoxicity is through apoptosis. Although use of surfactant decreases particle size, toxicity of modified ZnO NPs were still less than unmodified NPs on MDA-MB-231 contributed by biocompatible surface coating. Both samples show significantly less toxicity towards NIH 3T3 in concentration independent manner. But use of Triton-X, a biocompatible polymer, enhances this preferentiality effect. Since therapeutic significance should be analyzed through its comparative effect on both normal and cancer cells, possible application of biocompatible polymer modified nanoparticles as therapeutic agent holds better promise.Graphical abstractSurface coating, characterization and comparative in vitro cytotoxicity study on MDA-MB 231 and NIH 3T3 of ZnO NPs showing enhanced preferentiality by biocompatible surface modification.

Enhanced Broadband Electromagnetic Absorption in Silicon Film with Photonic Crystal Surface and Random Gold Grooves Reflector

PubMed Central

Chen, Zhi-Hui; Qiao, Na; Yang, Yibiao; Ye, Han; Liu, Shaoding; Wang, Wenjie; Wang, Yuncai

2015-01-01

We show a hybrid structure consisting of Si film with photonic crystal surface and random triangular gold grooves reflector at the bottom, which is capable of realizing efficient, broad-band, wide-angle optical absorption. It is numerically demonstrated that the enhanced absorption in a broad wavelength range (0.3–9.9 μm) due to the scattering effect of both sides of the structure and the created resonance modes. Larger thickness and period are favored to enhance the absorption in broader wavelength range. Substantial electric field concentrates in the grooves of surface photonic crystal and in the Si film. Our structure is versatile for solar cells, broadband photodetection and stealth coating. PMID:26238270

Surface tailored single walled carbon nanotubes as catalyst support for direct methanol fuel cell

NASA Astrophysics Data System (ADS)

Kireeti, Kota V. M. K.; Jha, Neetu

2017-10-01

A strategy for tuning the surface property of Single Walled Carbon Nanotubes (SWNTs) for enhanced methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) along with methanol tolerance is presented. The surface functionality is tailored using controlled acid and base treatment. Acid treatment leads to the attachment of carboxylic carbon (CC) fragments to SWNT making it hydrophilic (P3-SWNT). Base treatment of P3-SWNT with 0.05 M NaOH reduces the CCs and makes it hydrophobic (P33-SWNT). Pt catalyst supported on the P3-SWNT possesses enhanced MOR whereas that supported on P33-SWNT not only enhances ORR kinetics but also possess good tolerance towards methanol oxidation as verified by the electrochemical technique.

Cloning and Characterization of the Mouse Hepatitis Virus Receptor

DTIC Science & Technology

1991-02-11

materials. Viruses may also adhere to cell surfaces non-specifically through electrostatic interactions (Tardieu et al., 1982). Virus particles might be... viruses can utilize more than one type of receptor and that specific virus receptors may be present in low numbers on the cell surface or may be labile...known example of this type of interaction is the enhancement of virus infection by antibodies, which has been demonstrated for several viruses

Bacterial cellulose-polyaniline nano-biocomposite: A porous media hydrogel bioanode enhancing the performance of microbial fuel cell

NASA Astrophysics Data System (ADS)

Mashkour, Mehrdad; Rahimnejad, Mostafa; Mashkour, Mahdi

2016-09-01

Microbial fuel cells (MFCs) are one of the possible renewable energy supplies which microorganisms play an active role in bio-oxidize reactions of a substrate such as glucose. Electrode materials and surface modifications are highly effective tools in enhancing MFCs' Performance. In this study, new composite anodes are fabricated. Bacterial cellulose (BC) is used as continuous phase and polyaniline (PANI) as dispersed one which is synthesized by in situ chemical oxidative polymerization on BC's fibers. With hydrogel nature of BC as a novel feature and polyaniline conductivity there meet the favorable conditions to obtain an active microbial biofilm on anode surface. Maximum power density of 117.76 mW/m2 in current density of 617 mA/m2 is achieved for BC/PANI anode. The amounts demonstrate a considerable enhancement compared with graphite plate (1 mW/m2 and 10 mA/m2).

Unveiling NIR Aza-Boron-Dipyrromethene (BODIPY) Dyes as Raman Probes: Surface-Enhanced Raman Scattering (SERS)-Guided Selective Detection and Imaging of Human Cancer Cells.

PubMed

Adarsh, Nagappanpillai; Ramya, Adukkadan N; Maiti, Kaustabh Kumar; Ramaiah, Danaboyina

2017-10-12

The development of new Raman reporters has attracted immense attention in diagnostic research based on surface enhanced Raman scattering (SERS) techniques, which is a well established method for ultrasensitive detection through molecular fingerprinting and imaging. Herein, for the first time, we report the unique and efficient Raman active features of the selected aza-BODIPY dyes 1-6. These distinctive attributes could be extended at the molecular level to allow detection through SERS upon adsorption onto nano-roughened gold surface. Among the newly revealed Raman reporters, the amino substituted derivative 4 showed high signal intensity at very low concentrations (ca. 0.4 μm for 4-Au). Interestingly, an efficient nanoprobe has been constructed by using gold nanoparticles as SERS substrate, and 4 as the Raman reporter (4-Au@PEG), which unexpectedly showed efficient recognition of three human cancer cells (lung: A549, cervical: HeLa, Fibrosarcoma: HT-1080) without any specific surface marker. We observed well reflected and resolved Raman mapping and characteristic signature peaks whereas, such recognition was not observed in normal fibroblast (3T3L1) cells. To confirm these findings, a SERS nanoprobe was conjugated with a specific tumour targeting marker, EGFR (Epidermal Growth Factor Receptor), a well known targeted agent for Human Fibrosarcoma (HT1080). This nanoprobe efficiently targeted the surface marker of HT1080 cells, threreby demonstrating its use as an ultrasensitive Raman probe for detection and targeted imaging, leaving normal cells unaffected. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facile synthesis of terminal-alkyne bioorthogonal molecules for live -cell surface-enhanced Raman scattering imaging through Au-core and silver/dopamine-shell nanotags.

PubMed

Chen, Meng; Zhang, Ling; Yang, Bo; Gao, Mingxia; Zhang, Xiangmin

2018-03-01

Alkyne is unique, specific and biocompatible in the Raman-silent region of the cell, but there still remains a challenge to achieve ultrasensitive detection in living systems due to its weak Raman scattering. Herein, a terminal alkyne ((E)-2-[4-(ethynylbenzylidene)amino]ethane-1-thiol (EBAE)) with surface-enhanced Raman scattering is synthesized. The EBAE molecule possesses S- and C-termini, which can be directly bonded to gold nanoparticles and dopamine/silver by forming the Au-S chemical bond and the carbon-metal bond, respectively. The distance between Raman reporter and AuNPs/AgNPs can be reduced, contributing to forming hot-spot-based SERS substrate. The alkyne functionalized nanoparticles are based on Au core and encapsulating polydopamine shell, defined as Au-core and dopamine/Ag-shell (ACDS). The bimetallic ACDS induce strong SERS signals for molecular imaging that arise from the strong electromagnetic field. Furthermore, the EBAE provides a distinct peak in the cellular Raman-silent region with nearly zero background interference. The EBAE Raman signals could be tremendously enhanced when the Raman reporter is located at the middle of the Au-core and dopamine/Ag-shell. Therefore, this work could have huge potential benefits for the highly sensitive detection of intercellular information delivery by connecting the recognition molecules in biomedical diagnostics. Graphical abstract Terminal-alkyne-functionalized Au-core and silver/dopamine-shell nanotags for live-cell surface-enhanced Raman scattering imaging.

Glass-wool study of laser-induced spin currents en route to hyperpolarized Cs salt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishikawa, Kiyoshi

2011-07-15

The nuclear spin polarization of optically pumped Cs atoms flows to the surface of Cs hydride in a vapor cell. A fine glass wool lightly coated with the salt helps greatly increase the surface area in contact with the pumped atoms and enhance the spin polarization of the salt nuclei. Even though the glass wool randomly scatters the pump light, the atomic vapor can be polarized with unpolarized light in a magnetic field. The measured enhancement in the salt enables study of the polarizations of light and atomic nuclei very near the salt surface.

Tailoring of TiO2 films by H2SO4 treatment and UV irradiation to improve anticoagulant ability and endothelial cell compatibility.

PubMed

Liao, Yuzhen; Li, Linhua; Chen, Jiang; Yang, Ping; Zhao, Ansha; Sun, Hong; Huang, Nan

2017-07-01

Surfaces with dual functions that simultaneously exhibit good anticoagulant ability and endothelial cell (EC) compatibility are desirable for blood contact materials. However, these dual functions have rarely been achieved by inorganic materials. In this study, titanium dioxide (TiO 2 ) films were treated by sulphuric acid (H 2 SO 4 ) and ultraviolet (UV) irradiation successively (TiO 2 H 2 SO 4 -UV), resulting in good anticoagulant ability and EC compatibility simultaneously. We found that UV irradiation improved the anticoagulant ability of TiO 2 films significantly while enhancing EC compatibility, though not significantly. The enhanced anticoagulant ability could be related to the oxidation of surface-adsorbed hydrocarbons and increased hydrophilicity. The H 2 SO 4 treatment improved the anticoagulant ability of TiO 2 films slightly, while UV irradiation improved the anticoagulant ability strongly. The enhanced EC compatibility could be related to the increased surface roughness and positive charges on the surface of the TiO 2 films. Furthermore, the time-dependent degradation of the enhanced EC compatibility and anticoagulant ability of TiO 2 H 2 SO 4 -UV was observed. In summary, TiO 2 H 2 SO 4 -UV expressed both excellent anticoagulant ability and good EC compatibility at the same time, which could be desirable for blood contact materials. However, the compatibility of TiO 2 H 2 SO 4 -UV with smooth muscle cells (SMCs) and macrophages was also improved. More effort is still needed to selectively improve EC compatibility on TiO 2 films for better re-endothelialization. Copyright © 2017 Elsevier B.V. All rights reserved.

Grating-coupled surface plasmon enhanced short-circuit current in organic thin-film photovoltaic cells.

PubMed

Baba, Akira; Aoki, Nobutaka; Shinbo, Kazunari; Kato, Keizo; Kaneko, Futao

2011-06-01

In this study, we demonstrate the fabrication of grating-coupled surface plasmon resonance (SPR) enhanced organic thin-film photovoltaic cells and their improved photocurrent properties. The cell consists of a grating substrate/silver/P3HT:PCBM/PEDOT:PSS structure. Blu-ray disk recordable substrates are used as the diffraction grating substrates on which silver films are deposited by vacuum evaporation. P3HT:PCBM films are spin-coated on silver/grating substrates. Low conductivity PEDOT:PSS/PDADMAC layer-by-layer ultrathin films deposited on P3HT:PCBM films act as the hole transport layer, whereas high conductivity PEDOT:PSS films deposited by spin-coating act as the anode. SPR excitations are observed in the fabricated cells upon irradiation with white light. Up to a 2-fold increase in the short-circuit photocurrent is observed when the surface plasmon (SP) is excited on the silver gratings as compared to that without SP excitation. The finite-difference time-domain simulation indicates that the electric field in the P3HT:PCBM layer can be increased using the grating-coupled SP technique. © 2011 American Chemical Society

Gold Nanoparticles-enabled Efficient Dual Delivery of Anticancer Therapeutics to HeLa Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farooq, Muhammad U.; Novosad, Valentyn; Rozhkova, Elena A.

Colloidal gold nanoparticles (AuNPs) are of interest as non-toxic carriers for drug delivery owing to their advanced properties, such as extensive surface-to-volume ratio and possibilities for tailoring their charge, hydrophilicity and functionality through surface chemistries. To date, various biocompatible polymers have been used for surface decoration of AuNPs to enhance their stability, payloads capacity and cellular uptake. This study describes a facile one-step method to synthesize stable AuNPs loaded with combination of two anticancer therapeutics, -bleomycin and doxorubicin. Anticancer activities, cytotoxicity, uptake and intracellular localization of the AuNPs were demonstrated in HeLa cells. We show that the therapeutic efficacy ofmore » the nanohybrid drug was strongly enhanced by the active targeting by the nanoscale delivery system to HeLa cells with a significant decrease of the half-maximal effective drug concentration, through blockage of HeLa cancer cell cycle. These results provide rationale for further progress of AuNPs-assisted combination chemotherapy using two drugs at optimized effective concentrations which act via different mechanisms thus decreasing possibilities of development of the cancer drug resistance, reduction of systemic drug toxicity and improvement of outcomes of chemotherapy.« less

Osteoblastic cell response to spark plasma-sintered zirconia/titanium cermets.

PubMed

Fernandez-Garcia, Elisa; Guillem-Marti, Jordi; Gutierrez-Gonzalez, Carlos F; Fernandez, Adolfo; Ginebra, Maria-Pau; Lopez-Esteban, Sonia

2015-01-01

Ceramic/metal composites, cermets, arise from the idea to combine the dissimilar properties in the pure materials. This work aims to study the biocompatibility of new micro-nanostructured 3 Y-TZP/Ti materials with 25, 50 and 75 vol.% Ti, which have been successfully obtained by spark slasma sintering technology, as well as to correlate their surface properties (roughness, wettability and chemical composition) with the osteoblastic cell response. All samples had isotropic and slightly waved microstructure, with sub-micrometric average roughness. Composites with 75 vol.% Ti had the highest surface hydrophilicity. Surface chemical composition of the cermets correlated well with the relative amounts used for their fabrication. A cell viability rate over 80% dismissed any cytotoxicity risk due to manufacturing. Cell adhesion and early differentiation were significantly enhanced on materials containing the nanostructured 3 Y-TZP phase. Proliferation and differentiation of SaOS-2 were significantly improved in their late-stage on the composite with 75 vol.% Ti that, from the osseointegration standpoint, is presented as an excellent biomaterial for bone replacement. Thus, spark plasma sintering is consolidated as a suitable technology for manufacturing nanostructured biomaterials with enhanced bioactivity. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

The type II cGMP dependent protein kinase regulates GluA1 levels at the plasma membrane of developing cerebellar granule cells

PubMed Central

Incontro, Salvatore; Ciruela, Francisco; Ziff, Edward; Hofmann, Franz; Sánchez-Prieto, José; Torres, Magdalena

2014-01-01

Trafficking of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) is regulated by specific interactions with other proteins and by post-translational mechanisms, such as phosphorylation. We have found that the type II cGMP-dependent protein kinase (cGKII) phosphorylates GluA1 (formerly GluR1) at S845, augmenting the surface expression of AMPARs at both synaptic and extrasynaptic sites. Activation of cGKII by 8-Br-cGMP enhances the surface expression of GluA1, whereas its inhibition or suppression effectively diminished the expression of this protein at the cell surface. In granule cells, NMDA receptor activation (NMDAR) stimulates nitric oxide and cGMP production, which in turn activates cGKII and induces the phosphorylation of GluA1, promoting its accumulation in the plasma membrane. GluA1 is mainly incorporated into calcium permeable AMPARs as exposure to 8-Br-cGMP or NMDA activation enhanced AMPA-elicited calcium responses that are sensitive to NASPM inhibition. We summarize evidence for an increase of calcium permeable AMPA receptors downstream of NMDA receptor activation that might be relevant for granule cell development and plasticity. PMID:23545413

Gold Nanoparticles-enabled Efficient Dual Delivery of Anticancer Therapeutics to HeLa Cells

DOE PAGES

Farooq, Muhammad U.; Novosad, Valentyn; Rozhkova, Elena A.; ...

2018-02-13

Colloidal gold nanoparticles (AuNPs) are of interest as non-toxic carriers for drug delivery owing to their advanced properties, such as extensive surface-to-volume ratio and possibilities for tailoring their charge, hydrophilicity and functionality through surface chemistries. To date, various biocompatible polymers have been used for surface decoration of AuNPs to enhance their stability, payloads capacity and cellular uptake. This study describes a facile one-step method to synthesize stable AuNPs loaded with combination of two anticancer therapeutics, -bleomycin and doxorubicin. Anticancer activities, cytotoxicity, uptake and intracellular localization of the AuNPs were demonstrated in HeLa cells. We show that the therapeutic efficacy ofmore » the nanohybrid drug was strongly enhanced by the active targeting by the nanoscale delivery system to HeLa cells with a significant decrease of the half-maximal effective drug concentration, through blockage of HeLa cancer cell cycle. These results provide rationale for further progress of AuNPs-assisted combination chemotherapy using two drugs at optimized effective concentrations which act via different mechanisms thus decreasing possibilities of development of the cancer drug resistance, reduction of systemic drug toxicity and improvement of outcomes of chemotherapy.« less

Surface science studies on titania for solar fuel applications

NASA Astrophysics Data System (ADS)

Hadsell, Courtney Sara Mathews

Titanium dioxide (titania) is a well-studied material for various applications including but not limited to, paint, sunscreen, pharmaceuticals and solar cell applications (photocatalysis.) It can be found in three main crystal forms; rutile, anatase, and brookite and this work will focus on the anatase form which has been heavily studied for its potential in dye sensitized solar cells (DSSCs.) I propose that aqueous and photo dye stability can be improved by taking special care to the exposed surface of anatase. Additionally, the theoretical maximum open circuit voltage of a DSSC is dependent upon which surface is exposed to the electrolyte. Previous works in this area have not been rigorous with respect to the surface and morphology of titania being used. Standard synthesis techniques of anatase lead to a crystal that generally has 94% of the titania (101) surface exposed, and the other 6% is the higher energy (001) surface. The (101) surface has 5 & 6-fold coordinated titania whereas the (001) surface only has 5-fold (under) coordinated titania. This under-coordination leads to enhanced reactivity of the (001) surface which has been demonstrated by dissassociative adsorption of water, and catalysis applications. Much theoretical work has focused on the minority (001) surface because up until recently synthesizing anatase with enhanced exposure of the (001) surface has been difficult. The initial materials for this study will be multilayer titania nanotubes (TiNTs) and nanosheets (TiNS) which have been previously characterized by my predecessor. The TiNTs and TiNS have 100% exposed (001)-like surface. Both of these materials show enhanced stability of phosphonated dye binding as compared to the current standard of anatase nanoparticles (NPs) however, due to their limited thermal stability the potential of incorporating the TiNTs and TiNSs into devices has been eliminated in this study. To overcome the device limitations I will synthesis a novel titania nanotile (ntile) material which will have enhancement of the (001) surface while an increased thermal stability allowing for incorporation into a device. These ntiles will be created from a hydrothermal hydrolysis reaction between titanium n-butoxide (TiBuOx) and hydrofluoric acid (HF.) I will characterize this novel material and demonstrate the enhanced dye binding as well as the device capabilities.

A nanodiamond-fluorescein conjugate for cell studies

NASA Astrophysics Data System (ADS)

Pedroso-Santana, Seidy; Fleitas-Salazar, Noralvis; Sarabia-Sainz, Andrei; Silva-Campa, Erika; Burgara-Estrella, Alexel; Angulo-Molina, Aracely; Melendrez, Rodrigo; Pedroza-Montero, Martin; Riera, Raul

2018-03-01

The use of nanodiamonds in studies with living systems generally involves the modification of their surfaces with functional groups. Fluorescent molecules can be attached to these groups, so that one can know the exact position of the particles in each moment of the interaction with the cells. Here we modify the surface of detonation nanodiamonds and nitrogen-vacancy center nanodiamonds using carboxylation and hydroxylation procedures. Subsequent reactions with silicates and cysteine, before addition of fluorescein allow to obtain fluorescent nano-conjugates. We used confocal microscopy to observe the position of nanodiamonds interacting with HeLa cells. At 3 h post-incubation the green fluorescence is localized in extracellular rounded like-vesicles assemblies while at 24 h the conjugates can be observed inside the cells. The measurement of the fluorescence emitted by both conjugates allowed to find an enhanced emission of fluorescein isothiocyanate (FITC) when the nitrogen-vacancy center is present. We propose the existence of a fluorescence enhancement by electron transference process. The procedure described in this work allows the functionalization of nanodiamonds with FITC and other molecules using functional surface groups and small size mediators. Also, as was proved in our work, the nanodiamond-fluorescein conjugates can be used to track nanoparticles position within the cell. Localization studies are particularly important for drug delivery applications of nanodiamonds.

Soybean extracts increase cell surface ZIP4 abundance and cellular zinc levels: a potential novel strategy to enhance zinc absorption by ZIP4 targeting.

PubMed

Hashimoto, Ayako; Ohkura, Katsuma; Takahashi, Masakazu; Kizu, Kumiko; Narita, Hiroshi; Enomoto, Shuichi; Miyamae, Yusaku; Masuda, Seiji; Nagao, Masaya; Irie, Kazuhiro; Ohigashi, Hajime; Andrews, Glen K; Kambe, Taiho

2015-12-01

Dietary zinc deficiency puts human health at risk, so we explored strategies for enhancing zinc absorption. In the small intestine, the zinc transporter ZIP4 functions as an essential component of zinc absorption. Overexpression of ZIP4 protein increases zinc uptake and thereby cellular zinc levels, suggesting that food components with the ability to increase ZIP4 could potentially enhance zinc absorption via the intestine. In the present study, we used mouse Hepa cells, which regulate mouse Zip4 (mZip4) in a manner indistinguishable from that in intestinal enterocytes, to screen for suitable food components that can increase the abundance of ZIP4. Using this ZIP4-targeting strategy, two such soybean extracts were identified that were specifically able to decrease mZip4 endocytosis in response to zinc. These soybean extracts also effectively increased the abundance of apically localized mZip4 in transfected polarized Caco2 and Madin-Darby canine kidney cells and, moreover, two apically localized mZip4 acrodermatitis enteropathica mutants. Soybean components were purified from one extract and soyasaponin Bb was identified as an active component that increased both mZip4 protein abundance and zinc levels in Hepa cells. Finally, we confirmed that soyasaponin Bb is capable of enhancing cell surface endogenous human ZIP4 in human cells. Our results suggest that ZIP4 targeting may represent a new strategy to improve zinc absorption in humans. © 2015 Authors; published by Portland Press Limited.

Elastin-like polypeptide matrices for enhancing adeno-associated virus-mediated gene delivery to human neural stem cells.

PubMed

Kim, J-S; Chu, H S; Park, K I; Won, J-I; Jang, J-H

2012-03-01

The successful development of efficient and safe gene delivery vectors continues to be a major obstacle to gene delivery in stem cells. In this study, we have developed an elastin-like polypeptide (ELP)-mediated adeno-associated virus (AAV) delivery system for transducing fibroblasts and human neural stem cells (hNSCs). AAVs have significant promise as therapeutic vectors because of their safety and potential for use in gene targeting in stem cell research. ELP has been recently employed as a biologically inspired 'smart' biomaterial that exhibits an inverse temperature phase transition, thereby demonstrating promise as a novel drug carrier. The ELP that was investigated in this study was composed of a repetitive penta-peptide with [Val-Pro-Gly-Val-Gly]. A novel AAV variant, AAV r3.45, which was previously engineered by directed evolution to enhance transduction in rat NSCs, was nonspecifically immobilized onto ELPs that were adsorbed beforehand on a tissue culture polystyrene surface (TCPS). The presence of different ELP quantities on the TCPS led to variations in surface morphology, roughness and wettability, which were ultimately key factors in the modulation of cellular transduction. Importantly, with substantially reduced viral quantities compared with bolus delivery, ELP-mediated AAV delivery significantly enhanced delivery efficiency in fibroblasts and hNSCs, which have great potential for use in tissue engineering applications and neurodegenerative disorder treatments, respectively. The enhancement of cellular transduction in stem cells, as well as the feasibility of ELPs for utilization in three-dimensional scaffolds, will contribute to the advancement of gene therapy for stem cell research and tissue regenerative medicine.

KSHV cell attachment sites revealed by ultra sensitive tyramide signal amplification (TSA) localize to membrane microdomains that are up-regulated on mitotic cells.

PubMed

Garrigues, H Jacques; Rubinchikova, Yelena E; Rose, Timothy M

2014-03-01

Cell surface structures initiating attachment of Kaposi's sarcoma-associated herpesvirus (KSHV) were characterized using purified hapten-labeled virions visualized by confocal microscopy with a sensitive fluorescent enhancement using tyramide signal amplification (TSA). KSHV attachment sites were present in specific cellular domains, including actin-based filopodia, lamellipodia, ruffled membranes, microvilli and intercellular junctions. Isolated microdomains were identified on the dorsal surface, which were heterogeneous in size with a variable distribution that depended on cellular confluence and cell cycle stage. KSHV binding domains ranged from scarce on interphase cells to dense and continuous on mitotic cells, and quantitation of bound virus revealed a significant increase on mitotic compared to interphase cells. KSHV also bound to a supranuclear domain that was distinct from microdomains in confluent and interphase cells. These results suggest that rearrangement of the cellular membrane during mitosis induces changes in cell surface receptors implicated in the initial attachment stage of KSHV entry. Copyright © 2014 Elsevier Inc. All rights reserved.

Antibacterial titanium nano-patterned arrays inspired by dragonfly wings

NASA Astrophysics Data System (ADS)

Bhadra, Chris M.; Khanh Truong, Vi; Pham, Vy T. H.; Al Kobaisi, Mohammad; Seniutinas, Gediminas; Wang, James Y.; Juodkazis, Saulius; Crawford, Russell J.; Ivanova, Elena P.

2015-11-01

Titanium and its alloys remain the most popular choice as a medical implant material because of its desirable properties. The successful osseointegration of titanium implants is, however, adversely affected by the presence of bacterial biofilms that can form on the surface, and hence methods for preventing the formation of surface biofilms have been the subject of intensive research over the past few years. In this study, we report the response of bacteria and primary human fibroblasts to the antibacterial nanoarrays fabricated on titanium surfaces using a simple hydrothermal etching process. These fabricated titanium surfaces were shown to possess selective bactericidal activity, eliminating almost 50% of Pseudomonas aeruginosa cells and about 20% of the Staphylococcus aureus cells coming into contact with the surface. These nano-patterned surfaces were also shown to enhance the aligned attachment behavior and proliferation of primary human fibroblasts over 10 days of growth. These antibacterial surfaces, which are capable of exhibiting differential responses to bacterial and eukaryotic cells, represent surfaces that have excellent prospects for biomedical applications.

Antibacterial titanium nano-patterned arrays inspired by dragonfly wings

PubMed Central

Bhadra, Chris M.; Khanh Truong, Vi; Pham, Vy T. H.; Al Kobaisi, Mohammad; Seniutinas, Gediminas; Wang, James Y.; Juodkazis, Saulius; Crawford, Russell J.; Ivanova, Elena P.

2015-01-01

Titanium and its alloys remain the most popular choice as a medical implant material because of its desirable properties. The successful osseointegration of titanium implants is, however, adversely affected by the presence of bacterial biofilms that can form on the surface, and hence methods for preventing the formation of surface biofilms have been the subject of intensive research over the past few years. In this study, we report the response of bacteria and primary human fibroblasts to the antibacterial nanoarrays fabricated on titanium surfaces using a simple hydrothermal etching process. These fabricated titanium surfaces were shown to possess selective bactericidal activity, eliminating almost 50% of Pseudomonas aeruginosa cells and about 20% of the Staphylococcus aureus cells coming into contact with the surface. These nano-patterned surfaces were also shown to enhance the aligned attachment behavior and proliferation of primary human fibroblasts over 10 days of growth. These antibacterial surfaces, which are capable of exhibiting differential responses to bacterial and eukaryotic cells, represent surfaces that have excellent prospects for biomedical applications. PMID:26576662

Electrochemical surface modification of carbon mesh anode to improve the performance of air-cathode microbial fuel cells.

PubMed

Luo, Jianmei; Chi, Meiling; Wang, Hongyu; He, Huanhuan; Zhou, Minghua

2013-12-01

A convenient and promising alternative to surface modification of carbon mesh anode was fulfilled by electrochemical oxidation in the electrolyte of nitric acid or ammonium nitrate at ambient temperature. It was confirmed that such an anode modification method was low cost and effective not only in improving the efficiency of power generation in microbial fuel cells (MFCs) for synthetic wastewater treatment, but also helping to reduce the period for MFCs start-up. The MFCs with anode modification in electrolyte of nitric acid performed the best, achieving a Coulombic efficiency enhancement of 71 %. As characterized, the electrochemical modification resulted in the decrease of the anode potential and internal resistance but the increase of current response and nitrogen-containing and oxygen-containing functional groups on the carbon surface, which might contribute to the enhancement on the performances of MFCs.

Enhancement in photovoltaic properties of silicon solar cells by surface plasmon effect of palladium nanoparticles

NASA Astrophysics Data System (ADS)

Atyaoui, Malek; Atyaoui, Atef; Khalifa, Marwen; Elyagoubi, Jalel; Dimassi, Wissem; Ezzaouia, Hatem

2016-04-01

This work presents the surface Plasmon effect of Palladium nanoparticles (Pd NPs) on the photovoltaic properties of silicon solar cells. Pd NPs were deposited on the p-type silicon base of the n+/p junction using a chemical deposition method in an aqueous solution containing Palladium (II) Nitrate (PdNO3)2 and Ammonium Hydroxide (NH4OH) followed by a thermal treatment at 500 °C under nitrogen atmosphere. Chemical composition and surface morphology of the treated silicon base were examined by energy dispersive X-ray (EDX) spectroscopy, scanning electronic microscopy (SEM) and Atomic Force Microscopy (AFM). The effect of the deposited Pd NPs on the electrical properties was evaluated by the internal quantum efficiency (IQE) and current-voltage (I-V) measurements. The results indicate that the formation of the Pd NPs is accompanied by an enhanced light absorption and improved photovoltaic parameters.

Bone Cell–materials Interactions and Ni Ion Release of Anodized Equiatomic NiTi Alloy

PubMed Central

Bernard, Sheldon A.; Balla, Vamsi Krishna; Davies, Neal M.; Bose, Susmita; Bandyopadhyay, Amit

2011-01-01

Laser processed NiTi alloy was anodized for different durations in H2SO4 electrolyte with varying pH to create biocompatible surfaces with low Ni ion release as well as bioactive surfaces to enhance biocompatibility and bone cell-materials interactions. The anodized surfaces were assessed for their in vitro cell-materials interactions using human fetal osteoblast (hFOB) cells for 3, 7 and 11 days, and Ni ion release up to 8 weeks in simulated body fluids. The results were correlated with surface morphologies of anodized surfaces characterized using field-emission scanning electron microscopy (FESEM). The results show that the anodization creates a surface with nano/micro roughness depending on anodization conditions. The hydrophilicity of NiTi surface was found to improve after anodization due to lower contact angles in cell media, which dropped from 32° to < 5°. The improved wettability of anodized surfaces is further corroborated by their high surface energy comparable to that of cp Ti. Relatively high surface energy, especially polar component, and nano/micro surface features of anodized surfaces significantly increased the number of living cells and their adherence and growth on these surfaces. Finally, a significant drop in Ni ion release from 268 ± 11 to 136 ± 15 ppb was observed for NiTi surfaces after anodization. This work indicates that anodization of NiTi alloy has a positive influence on the surface energy and surface morphology, which in turn improve bone cell-materials interactions and reduce Ni ion release in vitro. PMID:21232641

Bone cell-materials interactions and Ni ion release of anodized equiatomic NiTi alloy.

PubMed

Bernard, Sheldon A; Balla, Vamsi Krishna; Davies, Neal M; Bose, Susmita; Bandyopadhyay, Amit

2011-04-01

A laser processed NiTi alloy was anodized for different times in H(2)SO(4) electrolyte with varying pH to create biocompatible surfaces with low Ni ion release as well as bioactive surfaces to enhance biocompatibility and bone cell-material interactions. The anodized surfaces were assessed for their in vitro cell-material interactions using human fetal osteoblast (hFOB) cells for 3, 7 and 11 days, and Ni ion release up to 8 weeks in simulated body fluids. The results were correlated with the surface morphologies of anodized surfaces characterized using field-emission scanning electron microscopy (FESEM). The results show that anodization creates a surface with nano/micro-roughness depending on the anodization conditions. The hydrophilicity of the NiTi surface was found to improve after anodization, as shown by the lower contact angles in cell medium, which dropped from 32° to <5°. The improved wettability of anodized surfaces is further corroborated by their high surface energy, comparable with that of commercially pure Ti. Relatively high surface energies, especially the polar component, and nano/micro surface features of anodized surfaces significantly increased the number of living cells and their adherence and growth on these surfaces. Finally, a significant drop in Ni ion release from 268±11 to 136±15 ppb was observed for NiTi surfaces after anodization. This work indicates that anodization of a NiTi alloy has a positive influence on the surface energy and surface morphology, which in turn improves bone cell-material interactions and reduces Ni ion release in vitro. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Highly narrow nanogap-containing Au@Au core-shell SERS nanoparticles: size-dependent Raman enhancement and applications in cancer cell imaging

NASA Astrophysics Data System (ADS)

Hu, Chongya; Shen, Jianlei; Yan, Juan; Zhong, Jian; Qin, Weiwei; Liu, Rui; Aldalbahi, Ali; Zuo, Xiaolei; Song, Shiping; Fan, Chunhai; He, Dannong

2016-01-01

Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on the surface of cancer cells. First, plasmonic nanostructures are made of gold nanoparticles (~15 nm) coated with gold shells, between which a highly narrow and uniform nanogap (~1.1 nm) is formed owing to polyA anchored on the Au cores. The well controlled distribution of Raman reporter molecules, such as 4,4'-dipyridyl (44DP) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), are readily encoded in the nanogap and can generate strong, reproducible SERS signals. In addition, we have investigated the size-dependent SERS activity of GCNPs and found that with the same laser wavelength, the Raman enhancement discriminated between particle sizes. The maximum Raman enhancement was achieved at a certain threshold of particle size (~76 nm). High narrow nanogap-containing Au@Au core-shell SERS tags (GCTs) were prepared via the functionalization of hyaluronic acid (HA) on GCNPs, which recognized the CD44 receptor, a tumor-associated surface biomarker. And it was shown that GCTs have a good targeting ability to tumour cells and promising prospects for multiplex biomarker detection.Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on the surface of cancer cells. First, plasmonic nanostructures are made of gold nanoparticles (~15 nm) coated with gold shells, between which a highly narrow and uniform nanogap (~1.1 nm) is formed owing to polyA anchored on the Au cores. The well controlled distribution of Raman reporter molecules, such as 4,4'-dipyridyl (44DP) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), are readily encoded in the nanogap and can generate strong, reproducible SERS signals. In addition, we have investigated the size-dependent SERS activity of GCNPs and found that with the same laser wavelength, the Raman enhancement discriminated between particle sizes. The maximum Raman enhancement was achieved at a certain threshold of particle size (~76 nm). High narrow nanogap-containing Au@Au core-shell SERS tags (GCTs) were prepared via the functionalization of hyaluronic acid (HA) on GCNPs, which recognized the CD44 receptor, a tumor-associated surface biomarker. And it was shown that GCTs have a good targeting ability to tumour cells and promising prospects for multiplex biomarker detection. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06919j

Enhanced conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film by acid treatment for indium tin oxide-free organic solar cells

NASA Astrophysics Data System (ADS)

Lin, Chun-Chiao; Huang, Chih-Kuo; Hung, Yu-Chieh; Chang, Mei-Ying

2016-08-01

An acid treatment is used in the enhancement of the conductivity of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) thin film, which is often used as the anode in organic solar cells. There are three types of acid treatment for PEDOT:PSS thin film: hydrochloric, sulfuric, and phosphoric acid treatments. In this study, we examine and compare these three ways with each other for differences in conductivity. Hydrochloric acid results in the highest conductivity enhancement, from 0.3 to 1109 S/cm. We also discuss the optical transmittance, conductivity, surface roughness, surface morphology, and stability, as well as the factors that can influence device efficiency. The devices are fabricated using an acid-treated PEDOT:PSS thin film as the anode. The highest power conversion efficiency was 1.32%, which is a large improvement over that of the unmodified organic solar cell (0.21%). It is comparable to that obtained when using indium tin oxide (ITO) as an electrode, ca. 1.46%.

The Role of Membrane Curvature in Nanoscale Topography-Induced Intracellular Signaling.

PubMed

Lou, Hsin-Ya; Zhao, Wenting; Zeng, Yongpeng; Cui, Bianxiao

2018-05-15

Over the past decade, there has been growing interest in developing biosensors and devices with nanoscale and vertical topography. Vertical nanostructures induce spontaneous cell engulfment, which enhances the cell-probe coupling efficiency and the sensitivity of biosensors. Although local membranes in contact with the nanostructures are found to be fully fluidic for lipid and membrane protein diffusions, cells appear to actively sense and respond to the surface topography presented by vertical nanostructures. For future development of biodevices, it is important to understand how cells interact with these nanostructures and how their presence modulates cellular function and activities. How cells recognize nanoscale surface topography has been an area of active research for two decades before the recent biosensor works. Extensive studies show that surface topographies in the range of tens to hundreds of nanometers can significantly affect cell functions, behaviors, and ultimately the cell fate. For example, titanium implants having rough surfaces are better for osteoblast attachment and host-implant integration than those with smooth surfaces. At the cellular level, nanoscale surface topography has been shown by a large number of studies to modulate cell attachment, activity, and differentiation. However, a mechanistic understanding of how cells interact and respond to nanoscale topographic features is still lacking. In this Account, we focus on some recent studies that support a new mechanism that local membrane curvature induced by nanoscale topography directly acts as a biochemical signal to induce intracellular signaling, which we refer to as the curvature hypothesis. The curvature hypothesis proposes that some intracellular proteins can recognize membrane curvatures of a certain range at the cell-to-material interface. These proteins then recruit and activate downstream components to modulate cell signaling and behavior. We discuss current technologies allowing the visualization of membrane deformation at the cell membrane-to-substrate interface with nanometer precision and demonstrate that vertical nanostructures induce local curvatures on the plasma membrane. These local curvatures enhance the process of clathrin-mediated endocytosis and affect actin dynamics. We also present evidence that vertical nanostructures can induce significant deformation of the nuclear membrane, which can affect chromatin distribution and gene expression. Finally, we provide a brief perspective on the curvature hypothesis and the challenges and opportunities for the design of nanotopography for manipulating cell behavior.

Multiplexed Molecular Imaging of Fresh Tissue Surfaces Enabled by Convection-Enhanced Topical Staining with SERS-Coded Nanoparticles.

PubMed

Wang, Yu W; Doerksen, Josh D; Kang, Soyoung; Walsh, Daniel; Yang, Qian; Hong, Daniel; Liu, Jonathan T C

2016-10-01

There is a need for intraoperative imaging technologies to guide breast-conserving surgeries and to reduce the high rates of re-excision for patients in which residual tumor is found at the surgical margins during postoperative pathology analyses. Feasibility studies have shown that utilizing topically applied surface-enhanced Raman scattering (SERS) nanoparticles (NPs), in conjunction with the ratiometric imaging of targeted versus untargeted NPs, enables the rapid visualization of multiple cell-surface biomarkers of cancer that are overexpressed at the surfaces of freshly excised breast tissues. In order to reliably and rapidly perform multiplexed Raman-encoded molecular imaging of large numbers of biomarkers (with five or more NP flavors), an enhanced staining method has been developed in which tissue surfaces are cyclically dipped into an NP-staining solution and subjected to high-frequency mechanical vibration. This dipping and mechanical vibration (DMV) method promotes the convection of the SERS NPs at fresh tissue surfaces, which accelerates their binding to their respective biomarker targets. By utilizing a custom-developed device for automated DMV staining, this study demonstrates the ability to simultaneously image four cell-surface biomarkers of cancer at the surfaces of fresh human breast tissues with a mixture of five flavors of SERS NPs (four targeted and one untargeted control) topically applied for 5 min and imaged at a spatial resolution of 0.5 mm and a raster-scanned imaging rate of >5 cm 2 min -1 . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electroactive BaTiO3 nanoparticle-functionalized fibrous scaffolds enhance osteogenic differentiation of mesenchymal stem cells

PubMed Central

Li, Yiping; Dai, Xiaohan; Bai, Yunyang; Liu, Yun; Wang, Yuehong; Liu, Ousheng; Yan, Fei; Tang, Zhangui; Zhang, Xuehui; Deng, Xuliang

2017-01-01

It has been proven that the surface topographic cues of fiber arrangement can induce osteogenic differentiation of mesenchymal stem cells. However, this effect alone is weak and insufficient to meet the needs of regenerative medicine. In this work, electroactivity concept was introduced to enhance the osteoinductivity of fibrous scaffolds. The randomly oriented and aligned electroactive fibrous scaffolds of poly-(l-lactic acid) (PLLA) with incorporation of ferroelectric ceramic BaTiO3 (BTO) nanoparticles (NPs) were fabricated by electrospinning. Physicochemical properties, including fiber morphology, microstructure, composition, thermal stability, surface roughness, and surface wettability, of these fibrous scaffolds were studied. The dielectric properties of the scaffolds were evaluated. The results showed that the randomly oriented BTO/PLLA composite fibrous scaffolds had the highest dielectric permittivity of 1.19, which is of the same order of magnitude as the natural bone. The combined effects of fiber orientation and electrical activity on the osteogenic responses of bone marrow mesenchymal stem cells (BM-MSCs) were specifically investigated. Randomly oriented composite fibrous scaffolds significantly promoted polygonal spreading and encouraged early osteogenic differentiation in BM-MSCs, whereas aligned composite fibrous scaffolds promoted cell elongation and discouraged osteogenic differentiation. These results evidenced that randomly fiber orientation and biomimetic electric activity have combining effects on osteogenic differentiation of BM-MSCs. Our findings indicate that coupling effects of multi-physical properties should be paid more attention to mimic the microenvironment for enhancing osteogenic differentiation of BM-MSCs. PMID:28603415

Recent advancements in plasmon-enhanced promising third-generation solar cells

NASA Astrophysics Data System (ADS)

Thrithamarassery Gangadharan, Deepak; Xu, Zhenhe; Liu, Yanlong; Izquierdo, Ricardo; Ma, Dongling

2017-01-01

The unique optical properties possessed by plasmonic noble metal nanostructures in consequence of localized surface plasmon resonance (LSPR) are useful in diverse applications like photovoltaics, sensing, non-linear optics, hydrogen generation, and photocatalytic pollutant degradation. The incorporation of plasmonic metal nanostructures into solar cells provides enhancement in light absorption and scattering cross-section (via LSPR), tunability of light absorption profile especially in the visible region of the solar spectrum, and more efficient charge carrier separation, hence maximizing the photovoltaic efficiency. This review discusses about the recent development of different plasmonic metal nanostructures, mainly based on Au or Ag, and their applications in promising third-generation solar cells such as dye-sensitized solar cells, quantum dot-based solar cells, and perovskite solar cells.

The fabrication of well-interconnected polycaprolactone/hydroxyapatite composite scaffolds, enhancing the exposure of hydroxyapatite using the wire-network molding technique.

PubMed

Cho, Yong Sang; Hong, Myoung Wha; Jeong, Hoon-Jin; Lee, Seung-Jae; Kim, Young Yul; Cho, Young-Sam

2017-11-01

In this study, the fabrication method was proposed for the well-interconnected polycaprolactone/hydroxyapatite composite scaffold with exposed hydroxyapatite using modified WNM technique. To characterize well-interconnected scaffolds in terms of hydroxyapatite exposure, several assessments were performed as follows: morphology, mechanical property, wettability, calcium ion release, and cell response assessments. The results of these assessments were compared with those of control scaffolds which were fabricated by precision extruding deposition (PED) apparatus. The control PED scaffolds have interconnected pores with nonexposed hydroxyapatite. Consequently, cell attachment of proposed WNM scaffold was improved by increased hydrophilicity and surface roughness of scaffold surface resulting from the exposure of hydroxyapatite particles and fabrication process using powders. Moreover, cell proliferation and differentiation of WNM scaffold were increased, because the exposure of hydroxyapatite particles may enhance cell adhesion and calcium ion release. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2315-2325, 2017. © 2016 Wiley Periodicals, Inc.

Enhanced pattern resolution, swelling-behaviour and biocompatibility of bioimprinted casein microdevices

NASA Astrophysics Data System (ADS)

Hashemi, Azadeh; de Decker, Fanny; Orcheston-Findlay, Louise; Ali, M. Azam; Alkaisi, Maan M.; Nock, Volker

2017-11-01

This work introduces casein microstructures with surface features as a biodegradable biomedical platform technology for enhancing tissue-engineering applications. An optimized fabrication process is presented to reduce the hydrophobicity of intermediate polydimethylsiloxane (PDMS) molds and to transfer high-resolution regular and biomimetic features onto the surface of casein devices. Four different cross-linking reagents, glutaraldehyde, formaldehyde, citric acid and transglutaminase (TG) were investigated to increase the degradation time of casein and their influence on swelling and biocompatibility of the films was studied. TG was found to be the only cross-linker to effectively increase the degradation time and show reduced film swelling after immersion into media, while remaining compatible with cell-culture. The maximum expansion of the films cross-linked via TG was 33% after 24 hours of immersion in cell-culture media. C2C12 cells were successfully cultured on the patterned films for up to 72 hours. The patterned biodegradable casein substrates presented here have promising applications in stem-cell engineering, regenerative medicine, and implantable devices.

Cellular imaging by targeted assembly of hot-spot SERS and photoacoustic nanoprobes using split-fluorescent protein scaffolds.

PubMed

Köker, Tuğba; Tang, Nathalie; Tian, Chao; Zhang, Wei; Wang, Xueding; Martel, Richard; Pinaud, Fabien

2018-02-09

The in cellulo assembly of plasmonic nanomaterials into photo-responsive probes is of great interest for many bioimaging and nanophotonic applications but remains challenging with traditional nucleic acid scaffolds-based bottom-up methods. Here, we address this quandary using split-fluorescent protein (FP) fragments as molecular glue and switchable Raman reporters to assemble gold or silver plasmonic nanoparticles (NPs) into photonic clusters directly in live cells. When targeted to diffusing surface biomarkers in cancer cells, the NPs self-assemble into surface-enhanced Raman-scattering (SERS) nanoclusters having hot spots homogenously seeded by the reconstruction of full-length FPs. Within plasmonic hot spots, autocatalytic activation of the FP chromophore and near-field amplification of its Raman fingerprints enable selective and sensitive SERS imaging of targeted cells. This FP-driven assembly of metal colloids also yields enhanced photoacoustic signals, allowing the hybrid FP/NP nanoclusters to serve as contrast agents for multimodal SERS and photoacoustic microscopy with single-cell sensitivity.

n-MoS2/p-Si Solar Cells with Al2O3 Passivation for Enhanced Photogeneration.

PubMed

Rehman, Atteq Ur; Khan, Muhammad Farooq; Shehzad, Muhammad Arslan; Hussain, Sajjad; Bhopal, Muhammad Fahad; Lee, Sang Hee; Eom, Jonghwa; Seo, Yongho; Jung, Jongwan; Lee, Soo Hong

2016-11-02

Molybdenum disulfide (MoS 2 ) has recently emerged as a promising candidate for fabricating ultrathin-film photovoltaic devices. These devices exhibit excellent photovoltaic performance, superior flexibility, and low production cost. Layered MoS 2 deposited on p-Si establishes a built-in electric field at MoS 2 /Si interface that helps in photogenerated carrier separation for photovoltaic operation. We propose an Al 2 O 3 -based passivation at the MoS 2 surface to improve the photovoltaic performance of bulklike MoS 2 /Si solar cells. Interestingly, it was observed that Al 2 O 3 passivation enhances the built-in field by reduction of interface trap density at surface. Our device exhibits an improved power conversion efficiency (PCE) of 5.6%, which to our knowledge is the highest efficiency among all bulklike MoS 2 -based photovoltaic cells. The demonstrated results hold the promise for integration of bulklike MoS 2 films with Si-based electronics to develop highly efficient photovoltaic cells.

Cooperative therapeutic anti-tumor effect of IL-15 agonist ALT-803 and co-targeting soluble NKG2D ligand sMIC

PubMed Central

Basher, Fahmin; Jeng, Emily K.; Wong, Hing; Wu, Jennifer

2016-01-01

Shedding of the human NKG2D ligand MIC (MHC class I-chain-related molecule) from tumor cell surfaces correlates with progression of many epithelial cancers. Shedding-derived soluble MIC (sMIC) enables tumor immune escape through multiple immune suppressive mechanisms, such as disturbing natural killer (NK) cell homeostatic maintenance, impairing NKG2D expression on NK cells and effector T cells, and facilitating the expansion of arginase I+ myeloid suppressor cells. Our recent study has demonstrated that sMIC is an effective cancer therapeutic target. Whether targeting tumor-derived sMIC would enhance current active immunotherapy is not known. Here, we determined the in vivo therapeutic effect of an antibody co-targeting sMIC with the immunostimulatory IL-15 superagonist complex, ALT-803, using genetically engineered transplantable syngeneic sMIC+ tumor models. We demonstrate that combined therapy of a nonblocking antibody neutralizing sMIC and ALT-803 improved the survival of animals bearing sMIC+ tumors in comparison to monotherapy. We further demonstrate that the enhanced therapeutic effect with combined therapy is through concurrent augmentation of NK and CD8 T cell anti-tumor responses. In particular, expression of activation-induced surface molecules and increased functional potential by cytokine secretion are improved greatly by the administration of combined therapy. Depletion of NK cells abolished the cooperative therapeutic effect. Our findings suggest that administration of the sMIC-neutralizing antibody can enhance the anti-tumor effects of ALT-803. With ALT-803 currently in clinical trials to treat progressive solid tumors, the majority of which are sMIC+, our findings provide a rationale for co-targeting sMIC to enhance the therapeutic efficacy of ALT-803 or other IL-15 agonists. PMID:26625316

Cooperative therapeutic anti-tumor effect of IL-15 agonist ALT-803 and co-targeting soluble NKG2D ligand sMIC.

PubMed

Basher, Fahmin; Jeng, Emily K; Wong, Hing; Wu, Jennifer

2016-01-05

Shedding of the human NKG2D ligand MIC (MHC class I-chain-related molecule) from tumor cell surfaces correlates with progression of many epithelial cancers. Shedding-derived soluble MIC (sMIC) enables tumor immune escape through multiple immune suppressive mechanisms, such as disturbing natural killer (NK) cell homeostatic maintenance, impairing NKG2D expression on NK cells and effector T cells, and facilitating the expansion of arginase I+ myeloid suppressor cells. Our recent study has demonstrated that sMIC is an effective cancer therapeutic target. Whether targeting tumor-derived sMIC would enhance current active immunotherapy is not known. Here, we determined the in vivo therapeutic effect of an antibody co-targeting sMIC with the immunostimulatory IL-15 superagonist complex, ALT-803, using genetically engineered transplantable syngeneic sMIC+ tumor models. We demonstrate that combined therapy of a nonblocking antibody neutralizing sMIC and ALT-803 improved the survival of animals bearing sMIC+ tumors in comparison to monotherapy. We further demonstrate that the enhanced therapeutic effect with combined therapy is through concurrent augmentation of NK and CD8 T cell anti-tumor responses. In particular, expression of activation-induced surface molecules and increased functional potential by cytokine secretion are improved greatly by the administration of combined therapy. Depletion of NK cells abolished the cooperative therapeutic effect. Our findings suggest that administration of the sMIC-neutralizing antibody can enhance the anti-tumor effects of ALT-803. With ALT-803 currently in clinical trials to treat progressive solid tumors, the majority of which are sMIC+, our findings provide a rationale for co-targeting sMIC to enhance the therapeutic efficacy of ALT-803 or other IL-15 agonists.

Surface etching technologies for monocrystalline silicon wafer solar cells

NASA Astrophysics Data System (ADS)

Tang, Muzhi

With more than 200 GW of accumulated installations in 2015, photovoltaics (PV) has become an important green energy harvesting method. The PV market is dominated by solar cells made from crystalline silicon wafers. The engineering of the wafer surfaces is critical to the solar cell cost reduction and performance enhancement. Therefore, this thesis focuses on the development of surface etching technologies for monocrystalline silicon wafer solar cells. It aims to develop a more efficient alkaline texturing method and more effective surface cleaning processes. Firstly, a rapid, isopropanol alcohol free texturing method is successfully demonstrated to shorten the process time and reduce the consumption of chemicals. This method utilizes the special chemical properties of triethylamine, which can form Si-N bonds with wafer surface atoms. Secondly, a room-temperature anisotropic emitter etch-back process is developed to improve the n+ emitter passivation. Using this method, 19.0% efficient screen-printed aluminium back surface field solar cells are developed that show an efficiency gain of 0.15% (absolute) compared with conventionally made solar cells. Finally, state-of-the-art silicon surface passivation results are achieved using hydrogen plasma etching as a dry alternative to the classical hydrofluoric acid wet-chemical process. The effective native oxide removal and the hydrogenation of the silicon surface are shown to be the reasons for the excellent level of surface passivation achieved with this novel method.

Surface enhanced Raman scattering spectroscopic waveguide

DOEpatents

Lascola, Robert J; McWhorter, Christopher S; Murph, Simona H

2015-04-14

A waveguide for use with surface-enhanced Raman spectroscopy is provided that includes a base structure with an inner surface that defines a cavity and that has an axis. Multiple molecules of an analyte are capable of being located within the cavity at the same time. A base layer is located on the inner surface of the base structure. The base layer extends in an axial direction along an axial length of an excitation section. Nanoparticles are carried by the base layer and may be uniformly distributed along the entire axial length of the excitation section. A flow cell for introducing analyte and excitation light into the waveguide and a method of applying nanoparticles may also be provided.

Bio-active molecules modified surfaces enhanced mesenchymal stem cell adhesion and proliferation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mobasseri, Rezvan; Center for Nanofibers & Nanotechnology, Department of Mechanical Engineering, National University of Singapore, 117576; Tian, Lingling

Surface modification of the substrate as a component of in vitro cell culture and tissue engineering, using bio-active molecules including extracellular matrix (ECM) proteins or peptides derived ECM proteins can modulate the surface properties and thereby induce the desired signaling pathways in cells. The aim of this study was to evaluate the behavior of human bone marrow mesenchymal stem cells (hBM-MSCs) on glass substrates modified with fibronectin (Fn), collagen (Coll), RGD peptides (RGD) and designed peptide (R-pept) as bio-active molecules. The glass coverslips were coated with fibronectin, collagen, RGD peptide and R-peptide. Bone marrow mesenchymal stem cells were cultured on differentmore » substrates and the adhesion behavior in early incubation times was investigated using scanning electron microscopy (SEM) and confocal microscopy. The MTT assay was performed to evaluate the effect of different bio-active molecules on MSCs proliferation rate during 24 and 72 h. Formation of filopodia and focal adhesion (FA) complexes, two steps of cell adhesion process, were observed in MSCs cultured on bio-active molecules modified coverslips, specifically in Fn coated and R-pept coated groups. SEM image showed well adhesion pattern for MSCs cultured on Fn and R-pept after 2 h incubation, while the shape of cells cultured on Coll and RGD substrates indicated that they might experience stress condition in early hours of culture. Investigation of adhesion behavior, as well as proliferation pattern, suggests R-peptide as a promising bio-active molecule to be used for surface modification of substrate in supporting and inducing cell adhesion and proliferation. - Highlights: • Bioactive molecules modified surface is a strategy to design biomimicry scaffold. • Bi-functional Tat-derived peptide (R-pept) enhanced MSCs adhesion and proliferation. • R-pept showed similar influences to fibronectin on FA formation and attachment.« less

Surface potential-governed cellular osteogenic differentiation on ferroelectric polyvinylidene fluoride trifluoroethylene films.

PubMed

Tang, Bolin; Zhang, Bo; Zhuang, Junjun; Wang, Qi; Dong, Lingqing; Cheng, Kui; Weng, Wenjian

2018-07-01

Surface potential of biomaterials can dramatically influence cellular osteogenic differentiation. In this work, a wide range of surface potential on ferroelectric polyvinylidene fluoride trifluoroethylene (P(VDF-TrFE)) films was designed to get insight into the interfacial interaction of cell-charged surface. The P(VDF-TrFE) films poled by contact electric poling at various electric fields obtained well stabilized surface potential, with wide range from -3 to 915 mV. The osteogenic differentiation level of cells cultured on the films was strongly dependent on surface potential and reached the optimum at 391 mV in this system. Binding specificity assay indicated that surface potential could effectively govern the binding state of the adsorbed fibronectin (FN) with integrin. Molecular dynamic (MD) simulation further revealed that surface potential brought a significant difference in the relative distance between RGD and synergy PHSRN sites of adsorbed FN, resulting in a distinct integrin-FN binding state. These results suggest that the full binding of integrin α5β1 with both RGD and PHSRN sites of FN possesses a strong ability to activate osteogenic signaling pathway. This work sheds light on the underlying mechanism of osteogenic differentiation behavior on charged material surfaces, and also provides a guidance for designing a reasonable charged surface to enhance osteogenic differentiation. The ferroelectric P(VDF-TrFE) films with steady and a wide range of surface potential were designed to understand underlying mechanism of cell-charged surface interaction. The results showed that the charged surface well favored upregulation of osteogenic differentiation of MC3T3-E1 cells, and more importantly, a highest level occurred on the film with a moderate surface potential. Experiments and molecular dynamics simulation demonstrated that the surface potential could govern fibronectin conformation and then the integrin-fibronectin binding. We propose that a full binding state of integrin α5β1 with fibronectin induces effective activation of integrin-mediated FAK/ERK signaling pathway to upregulate cellular osteogenic differentiation. This work provides a guidance for designing a reasonable charged surface to enhance osteogenic differentiation. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Enhanced Optical Breakdown in KB Cells Labeled with Folate-Targeted Silver/Dendrimer Composite Nanodevices

PubMed Central

Tse, Christine; Zohdy, Marwa J.; Ye, Jing Yong; O'Donnell, Matthew; Lesniak, Wojciech; Balogh, Lajos

2010-01-01

Enhanced optical breakdown of KB cells (a human oral epidermoid cancer cell known to overexpress folate receptors) targeted with silver/dendrimer composite nanodevices (CNDs) is described. CNDs {(Ag0}25-PAMAM_E5.(NH2)42(NGly)74(NFA)2.7} were fabricated by reactive encapsulation, using a biocompatible template of dendrimer-folic acid (FA) conjugates. Preferential uptake of the folate-targeted CNDs (of various treatment concentrations and surface functionality) by KB cells was visualized with confocal microscopy and transmission electron microscopy (TEM). Intracellular laser-induced optical breakdown (LIOB) threshold and dynamics were detected and characterized by high-frequency ultrasonic monitoring of resulting transient bubble events. When irradiated with a near-infrared (NIR), femtosecond laser, the CND-targeted KB cells acted as well-confined activators of laser energy, enhancing nonlinear energy absorption, exhibiting a significant reduction in breakdown threshold, and thus selectively promoting intracellular LIOB. PMID:20883823

Detection and imaging of quorum sensing in Pseudomonas aeruginosa biofilm communities by surface-enhanced resonance Raman scattering

PubMed Central

Bodelón, Gustavo; Montes-García, Verónica; López-Puente, Vanesa; Hill, Eric H.; Hamon, Cyrille; Sanz-Ortiz, Marta N.; Rodal-Cedeira, Sergio; Costas, Celina; Celiksoy, Sirin; Pérez-Juste, Ignacio; Scarabelli, Leonardo; Porta, Andrea La; Pérez-Juste, Jorge; Pastoriza-Santos, Isabel

2016-01-01

Most bacteria in nature exist as biofilms, which support intercellular signaling processes such as quorum sensing (QS), a cell-to-cell communication mechanism that allows bacteria to monitor and respond to cell density and changes in the environment. Because QS and biofilms are involved in the ability of bacteria to cause disease, there is a need for the development of methods for the non-invasive analysis of QS in natural bacterial populations. Here, by using surface-enhanced resonance Raman scattering spectroscopy, we report rationally designed nanostructured plasmonic substrates for the in-situ, label-free detection of a QS signaling metabolite in growing Pseudomonas aeruginosa biofilms and microcolonies. The in situ, non-invasive plasmonic imaging of QS in biofilms provides a powerful analytical approach for studying intercellular communication on the basis of secreted molecules as signals. PMID:27500808

Surface chemistry governs cellular tropism of nanoparticles in the brain

NASA Astrophysics Data System (ADS)

Song, Eric; Gaudin, Alice; King, Amanda R.; Seo, Young-Eun; Suh, Hee-Won; Deng, Yang; Cui, Jiajia; Tietjen, Gregory T.; Huttner, Anita; Saltzman, W. Mark

2017-05-01

Nanoparticles are of long-standing interest for the treatment of neurological diseases such as glioblastoma. Most past work focused on methods to introduce nanoparticles into the brain, suggesting that reaching the brain interstitium will be sufficient to ensure therapeutic efficacy. However, optimized nanoparticle design for drug delivery to the central nervous system is limited by our understanding of their cellular deposition in the brain. Here, we investigated the cellular fate of poly(lactic acid) nanoparticles presenting different surface chemistries, after administration by convection-enhanced delivery. We demonstrate that nanoparticles with `stealth' properties mostly avoid internalization by all cell types, but internalization can be enhanced by functionalization with bio-adhesive end-groups. We also show that association rates measured in cultured cells predict the extent of internalization of nanoparticles in cell populations. Finally, evaluating therapeutic efficacy in an orthotopic model of glioblastoma highlights the need to balance significant uptake without inducing adverse toxicity.

In situ intracellular spectroscopy with surface enhanced Raman spectroscopy (SERS)-enabled nanopipettes.

PubMed

Vitol, Elina A; Orynbayeva, Zulfiya; Bouchard, Michael J; Azizkhan-Clifford, Jane; Friedman, Gary; Gogotsi, Yury

2009-11-24

We report on a new analytical approach to intracellular chemical sensing that utilizes a surface-enhanced Raman spectroscopy (SERS)-enabled nanopipette. The probe is comprised of a glass capillary with a 100-500 nm tip coated with gold nanoparticles. The fixed geometry of the gold nanoparticles allows us to overcome the limitations of the traditional approach for intracellular SERS using metal colloids. We demonstrate that the SERS-enabled nanopipettes can be used for in situ analysis of living cell function in real time. In addition, SERS functionality of these probes allows tracking of their localization in a cell. The developed probes can also be applied for highly sensitive chemical analysis of nanoliter volumes of chemicals in a variety of environmental and analytical applications.

Detection of thiopurine methyltransferase activity in lysed red blood cells by means of lab-on-a-chip surface enhanced Raman spectroscopy (LOC-SERS).

PubMed

März, Anne; Mönch, Bettina; Rösch, Petra; Kiehntopf, Michael; Henkel, Thomas; Popp, Jürgen

2011-07-01

In this contribution, the great potential of surface enhanced Raman spectroscopy (SERS) in a lab-on-a-chip (LOC) device for the detection of analyte molecules in a complex environment is demonstrated. Using LOC-SERS, the enzyme activity of thiopurine S-methyltransferase (TPMT) is analysed and identified in lysed red blood cells. The conversion of 6-mercaptopurine to 6-methylmercaptopurine catalysed by TPMT is observed as it gives evidence for the enzyme activity. Being able to determine the TPMT activity before starting a treatment using 6-mercaptopurine, an optimized dosage can be applied to each patient and serious toxicity appearing within thiopurine treatment will be prevented.

A density gradient of VAPG peptides on a cell-resisting surface achieves selective adhesion and directional migration of smooth muscle cells over fibroblasts.

PubMed

Yu, Shan; Zuo, Xingang; Shen, Tao; Duan, Yiyuan; Mao, Zhengwei; Gao, Changyou

2018-05-01

Selective adhesion and migration of smooth muscle cells (SMCs) over fibroblasts (FIBs) is required to prevent adventitia fibrosis in vascular regeneration. In this study, a uniform cell-resisting layer of poly(ethylene glycol) (PEG) with a density gradient of azide groups was generated on a substrate by immobilizing two kinds of PEG molecules in a gradient manner. A density gradient of alkynyl-functionalized Val-Ala-Pro-Gly (VAPG) peptides was then prepared on the PEG layer via click chemistry. The VAPG density gradient was characterized by fluorescence imaging, revealing the gradual enhancement of the fluorescent intensity along the substrate direction. The adhesion and mobility of SMCs were selectively enhanced on the VAPG density gradient, leading to directional migration toward the higher peptide density (up to 84%). In contrast, the adhesion and mobility of FIBs were significantly weakened. The net displacement of SMCs also significantly increased compared with that on tissue culture polystyrene (TCPS) and that of FIBs on the gradient. The mitogen-activated protein kinase (MAPK) signaling pathways related to cell migration were studied, showing higher expressions of functional proteins from SMCs on the VAPG-modified surface in a density-dependent manner. For the first time the selective adhesion and directional migration of SMCs over FIBs was achieved by an elaborative design of a gradient surface, leading to a new insight in design of novel vascular regenerative materials. Selective cell adhesion and migration guided by regenerative biomaterials are extremely important for the regeneration of targeted tissues, which can avoid the drawbacks of incorrect and uncontrolled responses of tissue cells to implants. For example, selectivity of smooth muscle cells (SMCs) over fibroblasts (FIBs) is required to prevent adventitia fibrosis in vascular regeneration. Herein we prepare a uniform cell-repelling layer, on which SMCs-selective Val-Ala-Pro-Gly (VAPG) peptides are immobilized in a continuous manner. Selective adhesion and enhanced and directional migration of SMCs over FIBs are achieved by the interplay of cell-repelling layer and gradient SMCs-selective VAPG peptides, paving a new way for the design of novel vascular grafts with enhanced biological performance. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Potential for Enhanced Therapeutic Activity of Biological Cancer Therapies with Doxycycline Combination

PubMed Central

Tang, Hui; Sampath, Padma; Yan, Xinmin; Thorne, Stephen H

2012-01-01

Despite significant strides made in the clinical translation of adoptive immune cell therapies, it is apparent that many tumors incorporate strategies to avoid recognition by receptors expressed on the immune cells, such as NKG2D. Strategies that stabilize the expression of ligands for these receptors may enhance the therapeutic potential of these and related therapies. Doxycycline inhibits matrix metalloproteinases (MMPs) that act to cleave the extracellular domain of MICA/B, ligands for the NKG2D receptor. Doxycycline treatment blocked shedding of MICA/B from a panel of human tumor cells, but also acted to increase their expression and cell surface translocation, possibly through its action on ATM. This meant that many tumor cells displayed increased MICA/B expression and enhanced susceptibility to CIK cells. Interestingly, doxycycline also selectively enhanced the replication of oncolytic vaccinia in many tumor cell lines, leading to increased sensitivity to these therapies. Combination (CIK-oncolytic vaccinia) therapies used in conjunction with doxycyline led to increased anti-tumor effects. The unexpected and pleiotropic beneficial anti-tumor effects of doxycycline on both immune cell and oncolytic viral therapies make it an excellent candidate for rapid clinical testing. PMID:23282955

Global phenotypic characterisation of human platelet lysate expanded MSCs by high-throughput flow cytometry.

PubMed

Reis, Monica; McDonald, David; Nicholson, Lindsay; Godthardt, Kathrin; Knobel, Sebastian; Dickinson, Anne M; Filby, Andrew; Wang, Xiao-Nong

2018-03-02

Mesenchymal stromal cells (MSCs) are a promising cell source to develop cell therapy for many diseases. Human platelet lysate (PLT) is increasingly used as an alternative to foetal calf serum (FCS) for clinical-scale MSC production. To date, the global surface protein expression of PLT-expended MSCs (MSC-PLT) is not known. To investigate this, paired MSC-PLT and MSC-FCS were analysed in parallel using high-throughput flow cytometry for the expression of 356 cell surface proteins. MSC-PLT showed differential surface protein expression compared to their MSC-FCS counterpart. Higher percentage of positive cells was observed in MSC-PLT for 48 surface proteins, of which 13 were significantly enriched on MSC-PLT. This finding was validated using multiparameter flow cytometry and further confirmed by quantitative staining intensity analysis. The enriched surface proteins are relevant to increased proliferation and migration capacity, as well as enhanced chondrogenic and osteogenic differentiation properties. In silico network analysis revealed that these enriched surface proteins are involved in three distinct networks that are associated with inflammatory responses, carbohydrate metabolism and cellular motility. This is the first study reporting differential cell surface protein expression between MSC-PLT and MSC-FSC. Further studies are required to uncover the impact of those enriched proteins on biological functions of MSC-PLT.

Thiol-Reactive Star Polymers Display Enhanced Association with Distinct Human Blood Components.

PubMed

Glass, Joshua J; Li, Yang; De Rose, Robert; Johnston, Angus P R; Czuba, Ewa I; Khor, Song Yang; Quinn, John F; Whittaker, Michael R; Davis, Thomas P; Kent, Stephen J

2017-04-12

Directing nanoparticles to specific cell types using nonantibody-based methods is of increasing interest. Thiol-reactive nanoparticles can enhance the efficiency of cargo delivery into specific cells through interactions with cell-surface proteins. However, studies to date using this technique have been largely limited to immortalized cell lines or rodents, and the utility of this technology on primary human cells is unknown. Herein, we used RAFT polymerization to prepare pyridyl disulfide (PDS)-functionalized star polymers with a methoxy-poly(ethylene glycol) brush corona and a fluorescently labeled cross-linked core using an arm-first method. PDS star polymers were examined for their interaction with primary human blood components: six separate white blood cell subsets, as well as red blood cells and platelets. Compared with control star polymers, thiol-reactive nanoparticles displayed enhanced association with white blood cells at 37 °C, particularly the phagocytic monocyte, granulocyte, and dendritic cell subsets. Platelets associated with more PDS than control nanoparticles at both 37 °C and on ice, but they were not activated in the duration examined. Association with red blood cells was minor but still enhanced with PDS nanoparticles. Thiol-reactive nanoparticles represent a useful strategy to target primary human immune cell subsets for improved nanoparticle delivery.

Co-immobilization of active antibiotics and cell adhesion peptides on calcium based biomaterials.

PubMed

Palchesko, Rachelle N; Buckholtz, Gavin A; Romeo, Jared D; Gawalt, Ellen S

2014-07-01

Two bioactive molecules with unrelated functions, vancomycin and a cell adhesion peptide, were immobilized on the surface of a potential bone scaffold material, calcium aluminum oxide. In order to accomplish immobilization and retain bioactivity three sequential surface functionalization strategies were compared: 1.) vancomycin was chemically immobilized before a cell adhesion peptide (KRSR), 2.) vancomycin was chemically immobilized after KRSR and 3.) vancomycin was adsorbed after binding the cell adhesion peptide. Both molecules remained on the surface and active using all three reaction sequences and after autoclave sterilization based on osteoblast attachment, bacterial turbidity and bacterial zone inhibition test results. However, the second strategy was superior at enhancing osteoblast attachment and significantly decreasing bacterial growth when compared to the other sequences. Copyright © 2014 Elsevier B.V. All rights reserved.

Intracellular Acidosis Promotes Mitochondrial Apoptosis Pathway: Role of EMMPRIN Down-regulation via Specific Single-chain Fv Intrabody

PubMed Central

Thammasit, Patcharin; Sangboonruang, Sirikwan; Suwanpairoj, Supattara; Khamaikawin, Wannisa; Intasai, Nutjeera; Kasinrerk, Watchara; Tayapiwatana, Chatchai; Tragoolpua, Khajornsak

2015-01-01

Extracellular matrix metalloproteinase inducer (EMMPRIN) is a human leukocyte surface molecule that is enriched on the surface of many cancer cells, and it plays an important role in proliferation and metastasis. In this study, we utilized the chimeric adenoviral vector Ad5/F35 carrying gene encoding scFv against EMMPRIN (scFv-M6-1B9) to down-regulate EMMPRIN cell surface expression and investigated programmed cell death response in colorectal cancer (CRC) cell, Caco-2. The scFv-M6-1B9 intrabody exhibits robust activity in reducing EMMPRIN cell surface expression. This approach led to the inducing of apoptosis, which was relative to the increasing of apoptotic bodies in sub-G1 peak, phosphatidylserine externalization, as well as TUNEL-positive cells. In addition, real-time RT-PCR and western blotting analysis indicated that apoptosis was enhanced through the mitochondrial pathway, a marked reduction of Bcl-2, leading to the translocation of cytochrome c and also the dramatic activation of caspase-3. Moreover, carcinoembryonic antigen (CEA), a tumor marker for CRC, was found to have significantly diminished in both secreted protein and mRNA levels. In conclusion, these findings suggest that EMMPRIN down-regulation by scFv-M6-1B9 intrabody has great potential in enhancing the efficacy of apoptosis induction through the mitochondrial pathway and in effecting a decline in the CEA level. Thus, its benefits could be applied to project the future prospects for targeted gene therapy and therapeutic application in monitoring colorectal cancer. PMID:25663946

Annexin A8 controls leukocyte recruitment to activated endothelial cells via cell surface delivery of CD63

NASA Astrophysics Data System (ADS)

Poeter, Michaela; Brandherm, Ines; Rossaint, Jan; Rosso, Gonzalo; Shahin, Victor; Skryabin, Boris V.; Zarbock, Alexander; Gerke, Volker; Rescher, Ursula

2014-04-01

To enable leukocyte adhesion to activated endothelium, the leukocyte receptor P-selectin is released from Weibel-Palade bodies (WPB) to the endothelial cell surface where it is stabilized by CD63. Here we report that loss of annexin A8 (anxA8) in human umbilical vein endothelial cells (HUVEC) strongly decreases cell surface presentation of CD63 and P-selectin, with a concomitant reduction in leukocyte rolling and adhesion. We confirm the compromised leukocyte adhesiveness in inflammatory-activated endothelial venules of anxA8-deficient mice. We find that WPB of anxA8-deficient HUVEC contain less CD63, and that this is caused by improper transport of CD63 from late multivesicular endosomes to WPB, with CD63 being retained in intraluminal vesicles. Consequently, reduced CD63 cell surface levels are seen following WPB exocytosis, resulting in enhanced P-selectin re-internalization. Our data support a model in which anxA8 affects leukocyte recruitment to activated endothelial cells by supplying WPB with sufficient amounts of the P-selectin regulator CD63.

Neurogenic differentiation of human umbilical cord mesenchymal stem cells on aligned electrospun polypyrrole/polylactide composite nanofibers with electrical stimulation

NASA Astrophysics Data System (ADS)

Zhou, Junfeng; Cheng, Liang; Sun, Xiaodan; Wang, Xiumei; Jin, Shouhong; Li, Junxiang; Wu, Qiong

2016-09-01

Adult central nervous system (CNS) tissue has a limited capacity to recover after trauma or disease. Recent medical cell therapy using polymeric biomaterialloaded stem cells with the capability of differentiation to specific neural population has directed focuses toward the recovery of CNS. Fibers that can provide topographical, biochemical and electrical cues would be attractive for directing the differentiation of stem cells into electro-responsive cells such as neuronal cells. Here we report on the fabrication of an electrospun polypyrrole/polylactide composite nanofiber film that direct or determine the fate of mesenchymal stem cells (MSCs), via combination of aligned surface topography, and electrical stimulation (ES). The surface morphology, mechanical properties and electric properties of the film were characterized. Comparing with that on random surface film, expression of neurofilament-lowest and nestin of human umbilical cord mesenchymal stemcells (huMSCs) cultured on film with aligned surface topography and ES were obviously enhanced. These results suggest that aligned topography combining with ES facilitates the neurogenic differentiation of huMSCs and the aligned conductive film can act as a potential nerve scaffold.

Synergistic Effects of a Calcium Phosphate/Fibronectin Coating on the Adhesion of Periodontal Ligament Stem Cells Onto Decellularized Dental Root Surfaces.

PubMed

Lee, Jung-Seok; Kim, Hyun-Suk; Park, So-Yon; Kim, Tae-Wan; Jung, Jae-Suk; Lee, Jong-Bin; Kim, Chang-Sung

2015-01-01

This study aimed to enhance the attachment of periodontal ligament stem cells (PDLSCs) onto the decellularized dental root surface using surface coating with fibronectin and/or calcium phosphate (CaP) and to evaluate the activity of PDLSCs attached to a coated dental root surface following tooth replantation. PDLSCs were isolated from five dogs, and the other dental roots were used as a scaffold for carrying PDLSCs and then assigned to one of four groups according to whether their surface was coated with CaP, fibronectin, CaP/fibronectin, or left uncoated (control). Fibronectin increased the adhesion of PDLSCs onto dental root surfaces compared to both the control and CaP-coated groups, and simultaneous surface coating with CaP and fibronectin significantly accelerated and increased PDLSC adhesion compared to the fibronectin-only group. On in vivo tooth replantation, functionally oriented periodontal new attachment was observed on the CaP/fibronectin-coated dental roots to which autologous PDLSCs had adhered, while in the control condition, dental root replantation was associated only with root resorption and ankylosis along the entire root length. CaP and fibronectin synergistically enhanced the attachment of PDLSCs onto dental root surfaces, and autologous PDLSCs could produce de novo periodontal new attachment in an experimental in vivo model.

Probing the nanoscale interaction forces and elastic properties of organic and inorganic materials using force-distance (F-D) spectroscopy

NASA Astrophysics Data System (ADS)

Vincent, Abhilash

Due to their therapeutic applications such as radical scavenging, MRI contrast imaging, Photoluminescence imaging, drug delivery, etc., nanoparticles (NPs) have a significant importance in bio-nanotechnology. The reason that prevents the utilizing NPs for drug delivery in medical field is mostly due to their biocompatibility issues (incompatibility can lead to toxicity and cell death). Changes in the surface conditions of NPs often lead to NP cytotoxicity. Investigating the role of NP surface properties (surface charges and surface chemistry) on their interactions with biomolecules (Cells, protein and DNA) could enhance the current understanding of NP cytotoxicity. Hence, it is highly beneficial to the nanotechnology community to bring more attention towards the enhancement of surface properties of NPs to make them more biocompatible and less toxic to biological systems. Surface functionalization of NPs using specific ligand biomolecules have shown to enhance the protein adsorption and cellular uptake through more favorable interaction pathways. Cerium oxide NPs (CNPs also known as nanoceria) are potential antioxidants in cell culture models and understanding the nature of interaction between cerium oxide NPs and biological proteins and cells are important due to their therapeutic application (especially in site specific drug delivery systems). The surface charges and surface chemistry of CNPs play a major role in protein adsorption and cellular uptake. Hence, by tuning the surface charges and by selecting proper functional molecules on the surface, CNPs exhibiting strong adhesion to biological materials can be prepared. By probing the nanoscale interaction forces acting between CNPs and protein molecules using Atomic Force Microscopy (AFM) based force-distance (F-D) spectroscopy, the mechanism of CNP-protein adsorption and CNP cellular uptake can be understood more quantitatively. The work presented in this dissertation is based on the application of AFM in studying the interaction forces as well as the mechanical properties of nanobiomaterials. The research protocol employed in the earlier part of the dissertation is specifically aimed to understand the operation of F-D spectroscopy technique. The elastic properties of thin films of silicon dioxide NPs were investigated using F-D spectroscopy in the high force regime of few 100 nN to 1 microN. Here, sol-gel derived porous nanosilica thin films of varying surface morphology, particle size and porosity were prepared through acid and base catalyzed process. AFM nanoindentation experiments were conducted on these films using the F-D spectroscopy mode and the nanoscale elastic properties of these films were evaluated. The major contribution of this dissertation is a study exploring the interaction forces acting between CNPs and transferrin proteins in picoNewton scale regime using the force-distance spectroscopy technique. This study projects the importance of obtaining appropriate surface charges and surface chemistry so that the NP can exhibit enhanced protein adsorption and NP cellular uptake.

Glycovariant anti-CD37 monospecific protein therapeutic exhibits enhanced effector cell-mediated cytotoxicity against chronic and acute B cell malignancies

PubMed Central

Rafiq, Sarwish; Siadak, Anthony; Butchar, Jonathan P.; Cheney, Carolyn; Lozanski, Gerard; Jacob, Naduparambil K.; Lapalombella, Rosa; McGourty, Jackie; Moledor, Meghan; Lowe, Richard; Setter, Ben; Jones, Jeffrey; Flynn, Joseph M.; Andritsos, Leslie; Devine, Steven; Mo, Xiaokui; Jarjoura, David; Tridandapani, Susheela; Algate, Paul; Byrd, John C.; Muthusamy, Natarajan

2013-01-01

TRU-016 is a SMIPTM (monospecific protein therapeutic) molecule against the tetraspanin transmembrane family protein CD37 that is currently in Phase 2 trials in Chronic Lymphocytic Leukemia (CLL) and Non-Hodgkin Lymphoma (NHL). In an attempt to enhance the ADCC function of SMIP-016, the chimeric version of TRU-016, SMIP-016GV was engineered with a modification in a glycosylation site in the Fc domain. The wild-type and glycovariant SMIP proteins mediate comparable Type I antibody-like direct cytotoxicity in the presence of anti-human Fc crosslinker and show a similar tyrosine phosphorylation pattern post-treatment. However, NK cells stimulated with the SMIP-016GV exhibit enhanced activation and release 3-fold more interferon-γ compared with SMIP-016. SMIP-016GV shows enhanced ADCC function against cells expressing CD37 with NK cell effectors derived from both normal and CLL-affected individuals. Enhanced ADCC is observed against CLL cells and is sustained at concentrations of SMIP-016GV as low at 5E−6 µg/mL on cells expressing minimal CD37 antigen. In support of the biological relevance of this, SMIP-016GV mediates effective ADCC against primary acute lymphoblastic leukemia (ALL) cells with low surface expression of CD37. Collectively, these data suggest potential use of the novel therapeutic agent SMIP-016GV with enhanced effector function for B cell malignancies, including CLL and ALL therapy. PMID:23883821

Micro Solar Cells with Concentration and Light Trapping Optics

NASA Astrophysics Data System (ADS)

Li, Lanfang; Breuckner, Eric; Corcoran, Christopher; Yao, Yuan; Xu, Lu; Nuzzo, Ralph

2013-03-01

Compared with conventional bulk plate semiconductor solar cells, micro solar cells provide opportunity for novel design geometry and provide test bed for light trapping at the device level as well as module level. Surface recombination, however, will have to be addressed properly as the much increased surface area due to the reduced dimension is more prominent in these devices than conventional solar cells. In this poster, we present experimental demonstration of silicon micro solar cells with concentration and light trapping optics. Silicon micro solar cell with optimized surface passivation and doping profile that exhibit high efficiency is demonstrated. Effective incorporation of high quantum yield fluorescent centers in the polymer matrix into which micro solar cell was encapsulated was investigated for luminescent solar concentration application. Micro-cell on a semi-transparent, nanopatterned reflector formed by soft-imprint lithography was investigated for near field effect related solar conversion performance enhancement. This work is supported by the DOE `Light-Material Interactions in Energy Conversion' Energy Frontier Research Center under grant DE-SC0001293

An optimized surface plasmon photovoltaic structure using energy transfer between discrete nano-particles.

PubMed

Lin, Albert; Fu, Sze-Ming; Chung, Yen-Kai; Lai, Shih-Yun; Tseng, Chi-Wei

2013-01-14

Surface plasmon enhancement has been proposed as a way to achieve higher absorption for thin-film photovoltaics, where surface plasmon polariton(SPP) and localized surface plasmon (LSP) are shown to provide dense near field and far field light scattering. Here it is shown that controlled far-field light scattering can be achieved using successive coupling between surface plasmonic (SP) nano-particles. Through genetic algorithm (GA) optimization, energy transfer between discrete nano-particles (ETDNP) is identified, which enhances solar cell efficiency. The optimized energy transfer structure acts like lumped-element transmission line and can properly alter the direction of photon flow. Increased in-plane component of wavevector is thus achieved and photon path length is extended. In addition, Wood-Rayleigh anomaly, at which transmission minimum occurs, is avoided through GA optimization. Optimized energy transfer structure provides 46.95% improvement over baseline planar cell. It achieves larger angular scattering capability compared to conventional surface plasmon polariton back reflector structure and index-guided structure due to SP energy transfer through mode coupling. Via SP mediated energy transfer, an alternative way to control the light flow inside thin-film is proposed, which can be more efficient than conventional index-guided mode using total internal reflection (TIR).

Nano-hydroxyapatite-coated metal-ceramic composite of iron-tricalcium phosphate: Improving the surface wettability, adhesion and proliferation of mesenchymal stem cells in vitro.

PubMed

Surmeneva, Maria A; Kleinhans, Claudia; Vacun, Gabriele; Kluger, Petra Juliane; Schönhaar, Veronika; Müller, Michaela; Hein, Sebastian Boris; Wittmar, Alexandra; Ulbricht, Mathias; Prymak, Oleg; Oehr, Christian; Surmenev, Roman A

2015-11-01

Thin radio-frequency magnetron sputter deposited nano-hydroxyapatite (HA) films were prepared on the surface of a Fe-tricalcium phosphate (Fe-TCP) bioceramic composite, which was obtained using a conventional powder injection moulding technique. The obtained nano-hydroxyapatite coated Fe-TCP biocomposites (nano-HA-Fe-TCP) were studied with respect to their chemical and phase composition, surface morphology, water contact angle, surface free energy and hysteresis. The deposition process resulted in a homogeneous, single-phase HA coating. The ability of the surface to support adhesion and the proliferation of human mesenchymal stem cells (hMSCs) was studied using biological short-term tests in vitro. The surface of the uncoated Fe-TCP bioceramic composite showed an initial cell attachment after 24h of seeding, but adhesion, proliferation and growth did not persist during 14 days of culture. However, the HA-Fe-TCP surfaces allowed cell adhesion, and proliferation during 14 days. The deposition of the nano-HA films on the Fe-TCP surface resulted in higher surface energy, improved hydrophilicity and biocompatibility compared with the surface of the uncoated Fe-TCP. Furthermore, it is suggested that an increase in the polar component of the surface energy was responsible for the enhanced cell adhesion and proliferation in the case of the nano-HA-Fe-TCP biocomposites. Copyright © 2015 Elsevier B.V. All rights reserved.

Sulforaphane counteracts aggressiveness of pancreatic cancer driven by dysregulated Cx43-mediated gap junctional intercellular communication

PubMed Central

Zhang, Yiyao; Isayev, Orkhan; Heilmann, Katharina; Schoensiegel, Frank; Liu, Li; Nessling, Michelle; Richter, Karsten; Labsch, Sabrina; Nwaeburu, Clifford C.; Mattern, Juergen; Gladkich, Jury; Giese, Nathalia; Werner, Jens; Schemmer, Peter; Gross, Wolfgang; Gebhard, Martha M.; Gerhauser, Clarissa; Schaefer, Michael; Herr, Ingrid

2014-01-01

The extreme aggressiveness of pancreatic ductal adenocarcinoma (PDA) has been associated with blocked gap junctional intercellular communication (GJIC) and the presence of cancer stem cells (CSCs). We examined whether disturbed GJIC is responsible for a CSC phenotype in established and primary cancer cells and patient tissue of PDA using interdisciplinary methods based in physiology, cell and molecular biology, histology and epigenetics. Flux of fluorescent dyes and gemcitabine through gap junctions (GJs) was intact in less aggressive cells but not in highly malignant cells with morphological dysfunctional GJs. Among several connexins, only Cx43 was expressed on the cell surface of less aggressive and GJIC-competent cells, whereas Cx43 surface expression was absent in highly malignant, E-cadherin-negative and GJIC-incompetent cells. The levels of total Cx43 protein and Cx43 phosphorylated at Ser368 and Ser279/282 were high in normal tissue but low to absent in malignant tissue. si-RNA-mediated inhibition of Cx43 expression in GJIC-competent cells prevented GJIC and induced colony formation and the expression of stem cell-related factors. The bioactive substance sulforaphane enhanced Cx43 and E-cadherin levels, inhibited the CSC markers c-Met and CD133, improved the functional morphology of GJs and enhanced GJIC. Sulforaphane altered the phosphorylation of several kinases and their substrates and inhibition of GSK3, JNK and PKC prevented sulforaphane-induced CX43 expression. The sulforaphane-mediated expression of Cx43 was not correlated with enhanced Cx43 RNA expression, acetylated histone binding and Cx43 promoter de-methylation, suggesting that posttranslational phosphorylation is the dominant regulatory mechanism. Together, the absence of Cx43 prevents GJIC and enhances aggressiveness, whereas sulforaphane counteracts this process, and our findings highlight dietary co-treatment as a viable treatment option for PDA. PMID:24742583

Sulforaphane counteracts aggressiveness of pancreatic cancer driven by dysregulated Cx43-mediated gap junctional intercellular communication.

PubMed

Forster, Tobias; Rausch, Vanessa; Zhang, Yiyao; Isayev, Orkhan; Heilmann, Katharina; Schoensiegel, Frank; Liu, Li; Nessling, Michelle; Richter, Karsten; Labsch, Sabrina; Nwaeburu, Clifford C; Mattern, Juergen; Gladkich, Jury; Giese, Nathalia; Werner, Jens; Schemmer, Peter; Gross, Wolfgang; Gebhard, Martha M; Gerhauser, Clarissa; Schaefer, Michael; Herr, Ingrid

2014-03-30

The extreme aggressiveness of pancreatic ductal adenocarcinoma (PDA) has been associated with blocked gap junctional intercellular communication (GJIC) and the presence of cancer stem cells (CSCs). We examined whether disturbed GJIC is responsible for a CSC phenotype in established and primary cancer cells and patient tissue of PDA using interdisciplinary methods based in physiology, cell and molecular biology, histology and epigenetics. Flux of fluorescent dyes and gemcitabine through gap junctions (GJs) was intact in less aggressive cells but not in highly malignant cells with morphological dysfunctional GJs. Among several connexins, only Cx43 was expressed on the cell surface of less aggressive and GJIC-competent cells, whereas Cx43 surface expression was absent in highly malignant, E-cadherin-negative and GJIC-incompetent cells. The levels of total Cx43 protein and Cx43 phosphorylated at Ser368 and Ser279/282 were high in normal tissue but low to absent in malignant tissue. si-RNA-mediated inhibition of Cx43 expression in GJIC-competent cells prevented GJIC and induced colony formation and the expression of stem cell-related factors. The bioactive substance sulforaphane enhanced Cx43 and E-cadherin levels, inhibited the CSC markers c-Met and CD133, improved the functional morphology of GJs and enhanced GJIC. Sulforaphane altered the phosphorylation of several kinases and their substrates and inhibition of GSK3, JNK and PKC prevented sulforaphane-induced CX43 expression. The sulforaphane-mediated expression of Cx43 was not correlated with enhanced Cx43 RNA expression, acetylated histone binding and Cx43 promoter de-methylation, suggesting that posttranslational phosphorylation is the dominant regulatory mechanism. Together, the absence of Cx43 prevents GJIC and enhances aggressiveness, whereas sulforaphane counteracts this process, and our findings highlight dietary co-treatment as a viable treatment option for PDA.

Performance Improvement of Polymer Solar Cells by Surface-Energy-Induced Dual Plasmon Resonance.

PubMed

Yao, Mengnan; Shen, Ping; Liu, Yan; Chen, Boyuan; Guo, Wenbin; Ruan, Shengping; Shen, Liang

2016-03-09

The surface plasmon resonance (SPR) effect of metal nanoparticles (MNPs) is effectively applied on polymer solar cells (PSCs) to improve power conversion efficiency (PCE). However, universality of the reported results mainly focused on utilizing single type of MNPs to enhance light absorption only in specific narrow wavelength range. Herein, a surface-energy-induced dual MNP plasmon resonance by thermally evaporating method was presented to achieve the absorption enhancement in wider range. The differences of surface energy between silver (Ag), gold (Au), and tungsten trioxide (WO3) compared by contact angle images enable Ag and Au prefer to respectively aggregate into isolated islands rather than films at the initial stage of the evaporation process, which was clearly demonstrated in the atomic force microscopy (AFM) measurement. The sum of plasmon-enhanced wavelength range induced by both Ag NPs (350-450 nm) and Au NPs (450-600 nm) almost cover the whole absorption spectra of active layers, which compatibly contribute a significant efficiency improvement from 4.57 ± 0.16 to 6.55 ± 0.12% compared to the one without MNPs. Besides, steady state photoluminescence (PL) measurements provide strong evidence that the SPR induced by the Ag-Au NPs increase the intensity of light absorption. Finally, ultraviolet photoelectron spectroscopy (UPS) reveals that doping Au and Ag causes upper shift of both the work function and valence band of WO3, which is directly related to hole collection ability. We believe the surface-energy-induced dual plasmon resonance enhancement by simple thermally evaporating technique might pave the way toward higher-efficiency PSCs.

Nitride coating enhances endothelialization on biomedical NiTi shape memory alloy.

PubMed

Ion, Raluca; Luculescu, Catalin; Cimpean, Anisoara; Marx, Philippe; Gordin, Doina-Margareta; Gloriant, Thierry

2016-05-01

Surface nitriding was demonstrated to be an effective process for improving the biocompatibility of implantable devices. In this study, we investigated the benefits of nitriding the NiTi shape memory alloy for vascular stent applications. Results from cell experiments indicated that, compared to untreated NiTi, a superficial gas nitriding treatment enhanced the adhesion of human umbilical vein endothelial cells (HUVECs), cell spreading and proliferation. This investigation provides data to demonstrate the possibility of improving the rate of endothelialization on NiTi by means of nitride coating. Copyright © 2016 Elsevier B.V. All rights reserved.

Graphene/CdTe heterostructure solar cell and its enhancement with photo-induced doping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Shisheng, E-mail: shishenglin@zju.edu.cn; Chen, Hongsheng; State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027

2015-11-09

We report a type of solar cell based on graphene/CdTe Schottky heterostructure, which can be improved by surface engineering as graphene is atomic thin. By coating a layer of ultrathin CdSe quantum dots onto graphene/CdTe heterostructure, the power conversion efficiency is increased from 2.08% to 3.10%. Photo-induced doping is mainly accounted for this enhancement, as evidenced by field effect transport, Raman, photoluminescence, and quantum efficiency measurements. This work demonstrates a feasible way of improving the performance of graphene/semiconductor heterostructure solar cells by combining one dimensional with two dimensional materials.

Human mesenchymal stem cell behavior on femtosecond laser-textured Ti-6Al-4V surfaces.

PubMed

Cunha, Alexandre; Zouani, Omar Farouk; Plawinski, Laurent; Botelho do Rego, Ana Maria; Almeida, Amélia; Vilar, Rui; Durrieu, Marie-Christine

2015-01-01

The aim of the present work was to investigate ultrafast laser surface texturing as a surface treatment of Ti-6Al-4V alloy dental and orthopedic implants to improve osteoblastic commitment of human mesenchymal stem cells (hMSCs). Surface texturing was carried out by direct writing with an Yb:KYW chirped-pulse regenerative amplification laser system with a central wavelength of 1030 nm and a pulse duration of 500 fs. The surface topography and chemical composition were investigated by scanning electron microscopy and x-ray photoelectron spectroscopy, respectively. Three types of surface textures with potential interest to improve implant osseointegration can be produced by this method: laser-induced periodic surface structures (LIPSSs); nanopillars (NPs); and microcolumns covered with LIPSSs, forming a bimodal roughness distribution. The potential of the laser treatment in improving hMSC differentiation was assessed by in vitro study of hMSCs spreading, adhesion, elongation and differentiation using epifluorescence microscopy at different times after cell seeding, after specific stainings and immunostainings. Cell area and focal adhesion area were lower on the laser-textured surfaces than on a polished reference surface. Obviously, the laser-textured surfaces have an impact on cell shape. Osteoblastic commitment was observed independently of the surface topography after 2 weeks of cell seeding. When the cells were cultured (after 4 weeks of seeding) in osteogenic medium, LIPSS- and NP- textured surfaces enhanced matrix mineralization and bone-like nodule formation as compared with polished and microcolumn-textured surfaces. The present work shows that surface nanotextures consisting of LIPSSs and NPs can, potentially, improve hMSC differentiation into an osteoblastic lineage.

Enhancing the Hydrophilicity and Cell Attachment of 3D Printed PCL/Graphene Scaffolds for Bone Tissue Engineering

PubMed Central

Wang, Weiguang; Caetano, Guilherme; Ambler, William Stephen; Blaker, Jonny James; Frade, Marco Andrey; Mandal, Parthasarathi; Diver, Carl; Bártolo, Paulo

2016-01-01

Scaffolds are physical substrates for cell attachment, proliferation, and differentiation, ultimately leading to the regeneration of tissues. They must be designed according to specific biomechanical requirements, i.e., certain standards in terms of mechanical properties, surface characteristics, porosity, degradability, and biocompatibility. The optimal design of a scaffold for a specific tissue strongly depends on both materials and manufacturing processes, as well as surface treatment. Polymeric scaffolds reinforced with electro-active particles could play a key role in tissue engineering by modulating cell proliferation and differentiation. This paper investigates the use of an extrusion-based additive manufacturing system to produce poly(ε-caprolactone) (PCL)/pristine graphene scaffolds for bone tissue applications and the influence of chemical surface modification on their biological behaviour. Scaffolds with the same architecture but different concentrations of pristine graphene were evaluated from surface property and biological points of view. Results show that the addition of pristine graphene had a positive impact on cell viability and proliferation, and that surface modification leads to improved cell response. PMID:28774112

Enhancing the Hydrophilicity and Cell Attachment of 3D Printed PCL/Graphene Scaffolds for Bone Tissue Engineering.

PubMed

Wang, Weiguang; Caetano, Guilherme; Ambler, William Stephen; Blaker, Jonny James; Frade, Marco Andrey; Mandal, Parthasarathi; Diver, Carl; Bártolo, Paulo

2016-12-07

Scaffolds are physical substrates for cell attachment, proliferation, and differentiation, ultimately leading to the regeneration of tissues. They must be designed according to specific biomechanical requirements, i.e., certain standards in terms of mechanical properties, surface characteristics, porosity, degradability, and biocompatibility. The optimal design of a scaffold for a specific tissue strongly depends on both materials and manufacturing processes, as well as surface treatment. Polymeric scaffolds reinforced with electro-active particles could play a key role in tissue engineering by modulating cell proliferation and differentiation. This paper investigates the use of an extrusion-based additive manufacturing system to produce poly( ε -caprolactone) (PCL)/pristine graphene scaffolds for bone tissue applications and the influence of chemical surface modification on their biological behaviour. Scaffolds with the same architecture but different concentrations of pristine graphene were evaluated from surface property and biological points of view. Results show that the addition of pristine graphene had a positive impact on cell viability and proliferation, and that surface modification leads to improved cell response.

A new nano-enhanced technology proposed to quantify intracellular detection of radiation-induced metabolic processes.

PubMed

Malak, Henryk; Richmond, Robert; Dicello, J F

2011-02-01

A new approach to intracellular detection and imaging of metabolic processes and pathways is presented that uses surface plasmon resonance to enhance interactions between photon-absorbing metabolites and metal nanoparticles in contact with cells in vitro or in vivo. Photon absorption in the nanoparticles creates plasmon fields, enhancing intrinsic metabolite fluorescence, thereby increasing absorption and emission rates, creating new spectral emission bands, shortening fluorescence lifetimes, becoming more photo-stable and increasing fluorescent resonance energy transfer efficiency. Because the cells remain viable, it is proposed that the method may be used to interrogate cells prior to and after irradiation, with the potential for automated analyses of intracellular interactive pathways associated with radiation exposures at lower doses than existing technologies. The design and concepts of the instrument are presented along with data for unexposed cells.

Modulation of hydrogel nanoparticle intracellular trafficking by multivalent surface engineering with tumor targeting peptide

NASA Astrophysics Data System (ADS)

Karamchand, Leshern; Kim, Gwangseong; Wang, Shouyan; Hah, Hoe Jin; Ray, Aniruddha; Jiddou, Ruba; Koo Lee, Yong-Eun; Philbert, Martin A.; Kopelman, Raoul

2013-10-01

Surface engineering of a hydrogel nanoparticle (NP) with the tumor-targeting ligand, F3 peptide, enhances both the NP's binding affinity for, and internalization by, nucleolin overexpressing tumor cells. Remarkably, the F3-functionalized NPs consistently exhibited significantly lower trafficking to the degradative lysosomes than the non-functionalized NPs, in the tumor cells, after internalization. This is attributed to the non-functionalized NPs, but not the F3-functionalized NPs, being co-internalized with Lysosome-associated Membrane Protein-1 (LAMP1) from the surface of the tumor cells. Furthermore, it is shown that the intracellular trafficking of the F3-functionalized NPs differs significantly from that of the molecular F3 peptides (untethered to NPs). This has important implications for designing effective, chemically-responsive, controlled-release and multifunctional nanodrugs for multi-drug-resistant cancers.Surface engineering of a hydrogel nanoparticle (NP) with the tumor-targeting ligand, F3 peptide, enhances both the NP's binding affinity for, and internalization by, nucleolin overexpressing tumor cells. Remarkably, the F3-functionalized NPs consistently exhibited significantly lower trafficking to the degradative lysosomes than the non-functionalized NPs, in the tumor cells, after internalization. This is attributed to the non-functionalized NPs, but not the F3-functionalized NPs, being co-internalized with Lysosome-associated Membrane Protein-1 (LAMP1) from the surface of the tumor cells. Furthermore, it is shown that the intracellular trafficking of the F3-functionalized NPs differs significantly from that of the molecular F3 peptides (untethered to NPs). This has important implications for designing effective, chemically-responsive, controlled-release and multifunctional nanodrugs for multi-drug-resistant cancers. Electronic supplementary information (ESI) available: Effect of Potassium depletion on F3 peptide subcellular localization, MTT cytotoxicity data for endocytic inhibitors, size and morphology characterizations of hydrogel PAA nanocarriers, and optimization data for nanocarrier surface functionalization with PEG molecules and F3 peptides. See DOI: 10.1039/c3nr00908d

Chemical and physical effects on the adhesion, maturation, and survival of monocytes, macrophages, and foreign body giant cells

NASA Astrophysics Data System (ADS)

Collier, Terry Odell, III

Injury caused by biomedical device implantation initiates inflammatory and wound healing responses. Cells migrate to the site of injury to degrade bacteria and toxins, create new vasculature, and form new and repair injured tissue. Blood-proteins rapidly adsorb onto the implanted material surface and express adhesive ligands which mediate cell adhesion on the material surface. Monocyte-derived macrophages and multi-nucleated foreign body giant cells adhere to the surface and degrade the surface of the material. Due to the role of macrophage and foreign body giant cell on material biocompatibility and biostability, the effects of surface chemistry, surface topography and specific proteins on the maturation and survival of monocytes, macrophages and foreign body giant cells has been investigated. Novel molecularly designed materials were used to elucidate the dynamic interactions which occur between inflammatory cells, proteins and surfaces. The effect of protein and protein adhesion was investigated using adhesive protein depleted serum conditions on RGD-modified and silane modified surfaces. The effects of surface chemistry were investigated using temperature responsive surfaces of poly (N-isopropylacrylamide) and micropatterned surfaces of N-(2 aminoethyl)-3-aminopropyltrimethoxysilane regions on an interpenetrating polymer network of polyacrylamide and poly(ethylene glycol). The physical effects were investigated using polyimide scaffold materials and polyurethane materials with surface modifying end groups. The depletion of immunoglobulin G caused decreased levels of macrophage adhesion, foreign body giant cell formation and increased levels of apoptosis. The temporal nature of macrophage adhesion was observed with changing effectiveness of adherent cell detachment with time, which correlated to increased expression of beta1 integrin receptors on detached macrophages with time. The limited ability of the micropatterned surface, polyimide scaffold and surface modified polyurethane materials to control macrophage adhesion indicates the complexity of macrophage adhesion and protein adsorption onto a surface. These studies have indicated components and adhesive mechanisms which can be utilized to create materials with enhanced resistance to macrophage adhesion and/or degradative abilities.

Methionine Deprivation Induces a Targetable Vulnerability in Triple-negative Breast Cancer Cells by Enhancing TRAIL Receptor-2 Expression

PubMed Central

Strekalova, Elena; Malin, Dmitry; Good, David M.; Cryns, Vincent L.

2015-01-01

Purpose Many neoplasms are vulnerable to methionine deficiency by mechanisms that are poorly understood. Because gene profiling studies have revealed that methionine depletion increases TNF-related apoptosis-inducing ligand receptor-2 (TRAIL-R2) mRNA, we postulated that methionine stress sensitizes breast cancer cells to proapoptotic TRAIL-R2 agonists. Experimental Design Human triple (ER/PR/HER2)-negative breast carcinoma cell lines were cultured in control or methionine-free media. The effects of methionine depletion on TRAIL receptor expression and sensitivity to chemotherapy or a humanized agonistic TRAIL-R2 monoclonal antibody (lexatumumab) were determined. The melanoma-associated antigen MAGED2 was silenced to delineate its functional role in sensitizing TNBC cells to methionine stress. An orthotopic TNBC model was utilized to evaluate the effects of dietary methionine deficiency, lexatumumab or the combination. Results Methionine depletion sensitized TNBC cells to lexatumumab-induced caspase activation and apoptosis by increasing TRAIL-R2 mRNA and cell surface expression. MCF-10A cells transformed by oncogenic H-Ras, but not untransformed cells, and matrix-detached TNBC cells were highly sensitive to the combination of lexatumumab and methionine depletion. Proteomics analyses revealed that MAGED2, which has been reported to reduce TRAIL-R2 expression, was suppressed by methionine stress. Silencing MAGED2 recapitulated features of methionine deprivation, including enhanced mRNA and cell surface expression of TRAIL receptors and increased sensitivity to TRAIL receptor agonists. Dietary methionine deprivation enhanced the antitumor effects of lexatumumab in an orthotopic metastatic TNBC model. Conclusion Methionine depletion exposes a targetable defect in TNBC cells by increasing TRAIL-R2 expression. Our findings provide the foundation for a clinical trial combining dietary methionine restriction and TRAIL-R2 agonists. PMID:25724522

A light-regulated type I pilus contributes to Acinetobacter baumannii biofilm, motility and virulence functions.

PubMed

Wood, Cecily R; Ohneck, Emily J; Edelmann, Richard E; Actis, Luis A

2018-06-11

Transcriptional analyses of A. baumannii ATCC 17978 showed that the expression of A1S_2091 was enhanced in cells cultured in darkness at 24°C through a process that depended on the BlsA photoreceptor. Disruption of A1S_2091, a component of the A1S_2088-A1S_2091 polycistronic operon predicted to code for a type I chaperone/usher pilus assembly system, abolished surface motility and pellicle formation but significantly enhanced biofilm formation on plastic by bacteria cultured under darkness. Based on these observations, the A1S_2088-A1S_2091 operon was named the p hoto- r egulated p ilus ABCD ( prpABCD ) operon, with A1S_2091 coding for the PrpA pilin subunit. Unexpectedly, the comparative analyses of ATCC 17978 and prpA isogenic mutant cells cultured at 37°C showed the expression of light-regulated biofilm biogenesis and motility functions under a temperature condition that drastically affects BlsA production and its light sensing activity. These assays also suggest that 17978 cells produce alternative light-regulated adhesins and/or pili systems that enhance bacterial adhesion and biofilm formation both at 24°C and 37°C on plastic as well as on the surface of polarized A549 alveolar epithelial cells, where formation of bacterial filaments and cell chains was significantly enhanced. The inactivation of prpA also resulted in a significant reduction in virulence when tested using the Galleria mellonella virulence model. All these observations provide strong evidence showing the capacity of A. baumannii to sense light and interact with biotic and abiotic surfaces using undetermined alternative sensing and regulatory systems as well as alternative adherence and motility cellular functions that allow this pathogen to persist in different ecological niches. Copyright © 2018 American Society for Microbiology.

Correlation between substratum roughness and wettability, cell adhesion, and cell migration.

PubMed

Lampin, M; Warocquier-Clérout; Legris, C; Degrange, M; Sigot-Luizard, M F

1997-07-01

Cell adhesion and spreading of chick embryo vascular and corneal explants grown on rough and smooth poly (methyl methacrylate) (PMMA) were analyzed to test the cell response specificity to substratum surface properties. Different degrees of roughness were obtained by sand-blasting PMMA with alumina grains. Hydrophilic and hydrophobic components of the surface free energy (SFE) were calculated according to Good-van Oss's model. Contact angles were determined using a computerized angle meter. The apolar component of the SFE gamma s(LW), increased with a slight roughness whereas the basic component, gamma s-, decreased. The acido-basic properties disappeared as roughness increased. Incubation of PMMA in culture medium, performed to test the influence if the biological environment, allowed surface adsorption of medium proteins which annihilated roughness effect and restored hydrophilic properties. An organotypic culture assay was carried out in an attempt to relate the biocompatibility to substratum surface state. Cell migration was calculated from the area of cell layer. Cellular adhesion was determined by measuring the kinetic of release of enzymatically dissociated cells. A slight roughness raised the migration are to an upper extent no matter which cell type. Enhancement of the cell adhesion potential was related to the degree of roughness and the hydrophobicity.

The Macrophage Galactose-Type Lectin Can Function as an Attachment and Entry Receptor for Influenza Virus

PubMed Central

Ng, Wy Ching; Liong, Stella; Tate, Michelle D.; Irimura, Tatsuro; Denda-Nagai, Kaori; Brooks, Andrew G.; Londrigan, Sarah L.

2014-01-01

Specific protein receptors that mediate internalization and entry of influenza A virus (IAV) have not been identified for any cell type. Sialic acid (SIA), the primary attachment factor for IAV hemagglutinin, is expressed by numerous cell surface glycoproteins and glycolipids, confounding efforts to identify specific receptors involved in virus infection. Lec1 Chinese hamster ovary (CHO) epithelial cells express cell surface SIA and bind IAV yet are largely resistant to infection. Here, we demonstrate that expression of the murine macrophage galactose-type lectin 1 (MGL1) by Lec1 cells enhanced Ca2+-dependent IAV binding and restored permissivity to infection. Lec1 cells expressing MGL1 were infected in the presence or absence of cell surface SIA, indicating that MGL1 can act as a primary receptor or as a coreceptor with SIA. Lec1 cells expressing endocytosis-deficient MGL1 mediated Ca2+-dependent IAV binding but were less sensitive to IAV infection, indicating that direct internalization via MGL1 can result in cellular infection. Together, these studies identify MGL1 as a cell surface glycoprotein that can act as an authentic receptor for both attachment and infectious entry of IAV. PMID:24257596

Surface modification of PLGA nanoparticles by carbopol to enhance mucoadhesion and cell internalization.

PubMed

Surassmo, Suvimol; Saengkrit, Nattika; Ruktanonchai, Uracha Rungsardthong; Suktham, Kunat; Woramongkolchai, Noppawan; Wutikhun, Tuksadon; Puttipipatkhachorn, Satit

2015-06-01

Mucoadhesive poly (lactic-co-glycolic acid) (PLGA) nanoparticles having a modified shell-matrix derived from polyvinyl alcohol (PVA) and Carbopol (CP), a biodegradable polymer coating, to improve the adhesion and cell transfection properties were developed. The optimum formulations utilized a CP concentration in the range of 0.05-0.2%w/v, and were formed using modified emulsion-solvent evaporation technique. The resulting CP-PLGA nanoparticles were characterized in terms of their physical and chemical properties. The absorbed CP on the PLGA shell-matrix was found to affect the particle size and surface charge, with 0.05% CP giving rise to smooth spherical particles (0.05CP-PLGA) with the smallest size (285.90 nm), and strong negative surface charge (-25.70 mV). The introduction of CP results in an enhancement of the mucoadhesion between CP-PLGA nanoparticles and mucin particles. In vitro cell internalization studies highlighted the potential of 0.05CP-PLGA nanoparticles for transfection into SiHa cells, with uptake being time dependent. Additionally, cytotoxicity studies of CP-PLGA nanoparticles against SiHa cancer cells indicated that low concentrations of the nanoparticles were non-toxic to cells (cell viability >80%). From the various formulations studied, 0.05CP-PLGA nanoparticles proved to be the optimum model carrier having the required mucoadhesive profile and could be an alternative therapeutic efficacy carrier for targeted mucosal drug delivery systems with biodegradable polymer. Copyright © 2015 Elsevier B.V. All rights reserved.

DAP12 impacts trafficking and surface stability of killer immunoglobulin-like receptors on natural killer cells

PubMed Central

Mulrooney, Tiernan J.; Posch, Phillip E.; Hurley, Carolyn Katovich

2013-01-01

KIR aid in the regulation of NK cell activity. In this study, the effect of the interaction between the KIR2DS and their adapter, DAP12, was investigated beyond the previously defined signaling function. Flow cytometry analysis showed enhanced KIR2DS surface expression on NKL cells when cotransfected with DAP12. Conversely, KIR2DS4 surface expression on primary cells was decreased when the cells were treated with DAP12-specific siRNA. Treatment of the KIR2DS and DAP12-transfected cells with CHX or BFA repressed KIR2DS surface expression, revealing a role for DAP12 in trafficking newly synthesized KIR to the cell surface. Immunoprecipitation of DAP12 revealed an interaction of DAP12 with an immature isoform of KIR2DS, indicating that the interaction likely initiates within the ER. An internalization assay demonstrated a significant impact of DAP12 on KIR2DS surface stability. Confocal microscopy showed that internalized KIR2DS molecules are recruited to lysosomal compartments independent of DAP12 expression. Our results suggest that in vivo conditions that adversely affect DAP12 expression will indirectly reduce surface expression and stability of KIR2DS. These effects could significantly impact ligand recognition and strength of signaling through KIR2DS molecules. PMID:23715743

Focused ultrasound delivery of Raman nanoparticles across the blood-brain barrier: potential for targeting experimental brain tumors.

PubMed

Diaz, Roberto Jose; McVeigh, Patrick Z; O'Reilly, Meaghan A; Burrell, Kelly; Bebenek, Matthew; Smith, Christian; Etame, Arnold B; Zadeh, Gelareh; Hynynen, Kullervo; Wilson, Brian C; Rutka, James T

2014-07-01

Spectral mapping of nanoparticles with surface enhanced Raman scattering (SERS) capability in the near-infrared range is an emerging molecular imaging technique. We used magnetic resonance image-guided transcranial focused ultrasound (TcMRgFUS) to reversibly disrupt the blood-brain barrier (BBB) adjacent to brain tumor margins in rats. Glioma cells were found to internalize SERS capable nanoparticles of 50nm or 120nm physical diameter. Surface coating with anti-epidermal growth factor receptor antibody or non-specific human immunoglobulin G, resulted in enhanced cell uptake of nanoparticles in-vitro compared to nanoparticles with methyl terminated 12-unit polyethylene glycol surface. BBB disruption permitted the delivery of SERS capable spherical 50 or 120nm gold nanoparticles to the tumor margins. Thus, nanoparticles with SERS imaging capability can be delivered across the BBB non-invasively using TcMRgFUS and have the potential to be used as optical tracking agents at the invasive front of malignant brain tumors. This study demonstrates the use of magnetic resonance image-guided transcranial focused ultrasound to open the BBB and enable spectral mapping of nanoparticles with surface enhanced Raman scattering (SERS)-based molecular imaging for experimental tumor tracking. Copyright © 2014 Elsevier Inc. All rights reserved.

Effect of water and alkali modifications on ETS-10 for the cycloaddition of CO2 to propylene oxide.

PubMed

Doskocil, Eric J

2005-02-17

Sodium oxide (NaOx) impregnated Engelhard Titanosilicate-10 (ETS-10) molecular sieve catalysts were prepared to enhance the basicity associated with ETS-10 and subsequently investigated for the cycloaddition of carbon dioxide to propylene oxide to produce propylene carbonate. For dry NaOx-modified ETS-10 catalysts that contained no adsorbed water, a maximum yield of propylene carbonate was achieved at a loading of 2.0 excess NaOx species per unit cell. However, the greatest enhancements in the rate of reaction were observed when small amounts of water were adsorbed onto the unmodified ETS-10 catalyst immediately prior to reaction. Surface-bound water appears to enhance the surface Bronsted acidity of the unmodified ETS-10 catalyst via the formation of surface -OH groups at lower water loadings, producing a surface of better-tuned acid-base bifunctional characteristics for the cycloaddition reaction. At levels of hydration greater than 12.5% by mass, the yield of propylene carbonate was further enhanced, but at a smaller rate than that observed at lower rehydration levels, which is more indicative of an enhanced transport effect. Adsorption microcalorimetry of carbon dioxide indicated that, at loadings less than 2.0 NaOx per unit cell, the total uptake of the CO2 adsorption sites required for the reaction were less than in the parent ETS-10 material. However, at higher levels of NaOx occlusion, where the total uptake and strength of the adsorption sites exceeded those observed for the as-received ETS-10 material, the cycloaddition activity of this catalyst suffered due to the reduced pore volume and surface area. It appears that precise tuning of both the surface acidity and basicity is crucial in creating an effective acid-base bifunctional ETS-10 catalyst for the cycloaddition reaction investigated.

Enhancement of Ebola Virus Infection via Ficolin-1 Interaction with the Mucin Domain of GP Glycoprotein.

PubMed

Favier, Anne-Laure; Gout, Evelyne; Reynard, Olivier; Ferraris, Olivier; Kleman, Jean-Philippe; Volchkov, Viktor; Peyrefitte, Christophe; Thielens, Nicole M

2016-06-01

Ebola virus infection requires the surface viral glycoprotein to initiate entry into the target cells. The trimeric glycoprotein is a highly glycosylated viral protein which has been shown to interact with host C-type lectin receptors and the soluble complement recognition protein mannose-binding lectin, thereby enhancing viral infection. Similarly to mannose-binding lectin, ficolins are soluble effectors of the innate immune system that recognize particular glycans at the pathogen surface. In this study, we demonstrate that ficolin-1 interacts with the Zaire Ebola virus (EBOV) glycoprotein, and we characterized this interaction by surface plasmon resonance spectroscopy. Ficolin-1 was shown to bind to the viral glycoprotein with a high affinity. This interaction was mediated by the fibrinogen-like recognition domain of ficolin-1 and the mucin-like domain of the viral glycoprotein. Using a ficolin-1 control mutant devoid of sialic acid-binding capacity, we identified sialylated moieties of the mucin domain to be potential ligands on the glycoprotein. In cell culture, using both pseudotyped viruses and EBOV, ficolin-1 was shown to enhance EBOV infection independently of the serum complement. We also observed that ficolin-1 enhanced EBOV infection on human monocyte-derived macrophages, described to be major viral target cells,. Competition experiments suggested that although ficolin-1 and mannose-binding lectin recognized different carbohydrate moieties on the EBOV glycoprotein, the observed enhancement of the infection likely depended on a common cellular receptor/partner. In conclusion, ficolin-1 could provide an alternative receptor-mediated mechanism for enhancing EBOV infection, thereby contributing to viral subversion of the host innate immune system. A specific interaction involving ficolin-1 (M-ficolin), a soluble effector of the innate immune response, and the glycoprotein (GP) of EBOV was identified. Ficolin-1 enhanced virus infection instead of tipping the balance toward its elimination. An interaction between the fibrinogen-like recognition domain of ficolin-1 and the mucin-like domain of Ebola virus GP occurred. In this model, the enhancement of infection was shown to be independent of the serum complement. The facilitation of EBOV entry into target host cells by the interaction with ficolin-1 and other host lectins shunts virus elimination, which likely facilitates the survival of the virus in infected host cells and contributes to the virus strategy to subvert the innate immune response. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Surface acoustic wave actuated cell sorting (SAWACS).

PubMed

Franke, T; Braunmüller, S; Schmid, L; Wixforth, A; Weitz, D A

2010-03-21

We describe a novel microfluidic cell sorter which operates in continuous flow at high sorting rates. The device is based on a surface acoustic wave cell-sorting scheme and combines many advantages of fluorescence activated cell sorting (FACS) and fluorescence activated droplet sorting (FADS) in microfluidic channels. It is fully integrated on a PDMS device, and allows fast electronic control of cell diversion. We direct cells by acoustic streaming excited by a surface acoustic wave which deflects the fluid independently of the contrast in material properties of deflected objects and the continuous phase; thus the device underlying principle works without additional enhancement of the sorting by prior labelling of the cells with responsive markers such as magnetic or polarizable beads. Single cells are sorted directly from bulk media at rates as fast as several kHz without prior encapsulation into liquid droplet compartments as in traditional FACS. We have successfully directed HaCaT cells (human keratinocytes), fibroblasts from mice and MV3 melanoma cells. The low shear forces of this sorting method ensure that cells survive after sorting.

Surface-enhanced FAST CARS: en route to quantum nano-biophotonics

NASA Astrophysics Data System (ADS)

Voronine, Dmitri V.; Zhang, Zhenrong; Sokolov, Alexei V.; Scully, Marlan O.

2018-02-01

Quantum nano-biophotonics as the science of nanoscale light-matter interactions in biological systems requires developing new spectroscopic tools for addressing the challenges of detecting and disentangling weak congested optical signals. Nanoscale bio-imaging addresses the challenge of the detection of weak resonant signals from a few target biomolecules in the presence of the nonresonant background from many undesired molecules. In addition, the imaging must be performed rapidly to capture the dynamics of biological processes in living cells and tissues. Label-free non-invasive spectroscopic techniques are required to minimize the external perturbation effects on biological systems. Various approaches were developed to satisfy these requirements by increasing the selectivity and sensitivity of biomolecular detection. Coherent anti-Stokes Raman scattering (CARS) and surface-enhanced Raman scattering (SERS) spectroscopies provide many orders of magnitude enhancement of chemically specific Raman signals. Femtosecond adaptive spectroscopic techniques for CARS (FAST CARS) were developed to suppress the nonresonant background and optimize the efficiency of the coherent optical signals. This perspective focuses on the application of these techniques to nanoscale bio-imaging, discussing their advantages and limitations as well as the promising opportunities and challenges of the combined coherence and surface enhancements in surface-enhanced coherent anti-Stokes Raman scattering (SECARS) and tip-enhanced coherent anti-Stokes Raman scattering (TECARS) and the corresponding surface-enhanced FAST CARS techniques. Laser pulse shaping of near-field excitations plays an important role in achieving these goals and increasing the signal enhancement.

Fabrication and surface modification of macroporous poly(L-lactic acid) and poly(L-lactic-co-glycolic acid) (70/30) cell scaffolds for human skin fibroblast cell culture.

PubMed

Yang, Jian; Shi, Guixin; Bei, Jianzhong; Wang, Shenguo; Cao, Yilin; Shang, Qingxin; Yang, Guanghui; Wang, Wenjing

2002-12-05

The fabrication and surface modification of a porous cell scaffold are very important in tissue engineering. Of most concern are high-density cell seeding, nutrient and oxygen supply, and cell affinity. In the present study, poly(L-lactic acid) and poly(L-lactic-co-glycolic acid) (70/30) cell scaffolds with different pore structures were fabricated. An improved method based on Archimedes' Principle for measuring the porosity of scaffolds, using a density bottle, was developed. Anhydrous ammonia plasma treatment was used to modify surface properties to improve the cell affinity of the scaffolds. The results show that hydrophilicity and surface energy were improved. The polar N-containing groups and positive charged groups also were incorporated into the sample surface. A low-temperature treatment was used to maintain the plasma-modified surface properties effectively. It would do help to the further application of plasma treatment technique. Cell culture results showed that pores smaller than 160 microm are suitable for human skin fibroblast cell growth. Cell seeding efficiency was maintained at above 99%, which is better than the efficiency achieved with the common method of prewetting by ethanol. The plasma-treatment method also helped to resolve the problem of cell loss during cell seeding, and the negative effects of the ethanol trace on cell culture were avoided. The results suggest that anhydrous ammonia plasma treatment enhances the cell affinity of porous scaffolds. Mass transport issues also have been considered. Copyright 2002 Wiley Periodicals, Inc.

Anti-CD22/CD20 Bispecific antibody with enhanced trogocytosis for treatment of Lupus.

PubMed

Rossi, Edmund A; Chang, Chien-Hsing; Goldenberg, David M

2014-01-01

The humanized anti-CD22 antibody, epratuzumab, has demonstrated therapeutic activity in clinical trials of lymphoma, leukemia and autoimmune diseases, treating currently over 1500 cases of non-Hodgkin lymphoma, acute lymphoblastic leukemias, Waldenström's macroglobulinemia, Sjögren's syndrome, and systemic lupus erythematosus. Because epratuzumab reduces on average only 35% of circulating B cells in patients, and has minimal antibody-dependent cellular cytotoxicity and negligible complement-dependent cytotoxicity when evaluated in vitro, its therapeutic activity may not result completely from B-cell depletion. We reported recently that epratuzumab mediates Fc/FcR-dependent membrane transfer from B cells to effector cells via trogocytosis, resulting in a substantial reduction of multiple BCR modulators, including CD22, CD19, CD21, and CD79b, as well as key cell adhesion molecules, including CD44, CD62L, and β7 integrin, on the surface of B cells in peripheral blood mononuclear cells obtained from normal donors or SLE patients. Rituximab has clinical activity in lupus, but failed to achieve primary endpoints in a Phase III trial. This is the first study of trogocytosis mediated by bispecific antibodies targeting neighboring cell-surface proteins, CD22, CD20, and CD19, as demonstrated by flow cytometry and immunofluorescence microscopy. We show that, compared to epratuzumab, a bispecific hexavalent antibody comprising epratuzumab and veltuzumab (humanized anti-CD20 mAb) exhibits enhanced trogocytosis resulting in major reductions in B-cell surface levels of CD19, CD20, CD21, CD22, CD79b, CD44, CD62L and β7-integrin, and with considerably less immunocompromising B-cell depletion that would result with anti-CD20 mAbs such as veltuzumab or rituximab, given either alone or in combination with epratuzumab. A CD22/CD19 bispecific hexavalent antibody, which exhibited enhanced trogocytosis of some antigens and minimal B-cell depletion, may also be therapeutically useful. The bispecific antibody is a candidate for improved treatment of lupus and other autoimmune diseases, offering advantages over administration of the two parental antibodies in combination.

Concise Review: Cell Surface N-Linked Glycoproteins as Potential Stem Cell Markers and Drug Targets.

PubMed

Boheler, Kenneth R; Gundry, Rebekah L

2017-01-01

Stem cells and their derivatives hold great promise to advance regenerative medicine. Critical to the progression of this field is the identification and utilization of antibody-accessible cell-surface proteins for immunophenotyping and cell sorting-techniques essential for assessment and isolation of defined cell populations with known functional and therapeutic properties. Beyond their utility for cell identification and selection, cell-surface proteins are also major targets for pharmacological intervention. Although comprehensive cell-surface protein maps are highly valuable, they have been difficult to define until recently. In this review, we discuss the application of a contemporary targeted chemoproteomic-based technique for defining the cell-surface proteomes of stem and progenitor cells. In applying this approach to pluripotent stem cells (PSCs), these studies have improved the biological understanding of these cells, led to the enhanced use and development of antibodies suitable for immunophenotyping and sorting, and contributed to the repurposing of existing drugs without the need for high-throughput screening. The utility of this latter approach was first demonstrated with human PSCs (hPSCs) through the identification of small molecules that are selectively toxic to hPSCs and have the potential for eliminating confounding and tumorigenic cells in hPSC-derived progeny destined for research and transplantation. Overall, the cutting-edge technologies reviewed here will accelerate the development of novel cell-surface protein targets for immunophenotyping, new reagents to improve the isolation of therapeutically qualified cells, and pharmacological studies to advance the treatment of intractable diseases amenable to cell-replacement therapies. Stem Cells Translational Medicine 2017;6:131-138. © 2016 The Authors Stem Cells Translational Medicine published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Enhancement of the p27Kip1-mediated antiproliferative effect of trastuzumab (Herceptin) on HER2-overexpressing tumor cells.

PubMed

Marches, Radu; Uhr, Jonathan W

2004-11-10

The oncogenic activity of the overexpressed HER2 tyrosine kinase receptor requires its localization in the plasma membrane. The antitumor effect of anti-HER2 antibodies (Abs) is mainly dependent on receptor downregulation and comprises p27Kip1-mediated G1 cell cycle arrest. However, one major limitation of anti-HER2 therapy is the reversibility of tumor growth inhibition after discontinuation of treatment caused by the mitogenic signaling associated with cell surface receptor re-expression. We found that the level of p27Kip1 upregulation, inhibition of Cdk2 activity and magnitude of G1 arrest induced by the humanized Ab trastuzumab (Herceptin, HCT) on BT474 and SKBr3 HER2-overexpressing breast cancer cells correlates with the level of cell surface receptor. Thus, continuous exposure of cells to HCT for 72 hr results in downregulation of the cell surface receptor and a concurrent increase in the level of p27Kip1 protein. Discontinuation of Ab exposure after the first 8 hr results in failure to upregulate p27Kip1 and arrest of cell cycle progression. We show that the lysosomotropic amine chloroquine (CQ) augments receptor internalization in HER2-overexpressing cells either pretreated or continuously treated with HCT and leads to an increased and sustained inhibitory effect. The enhanced CQ-dependent loss of functional HER2 from the cell surface resulted in sustained inactivation of the serine/threonine kinase Akt, upregulation of p27Kip1 protein and inhibition of cyclin E/Cdk2 activity. Potentiation of the inhibitory effect of HCT by CQ was directly related to loss of HER2 from the plasma membrane since prevention of Ab-mediated receptor endocytosis by engagement of the receptor with immobilized HCT abrogated the effect of CQ.

Immobilization of heparin/poly-(L)-lysine nanoparticles on dopamine-coated surface to create a heparin density gradient for selective direction of platelet and vascular cells behavior.

PubMed

Liu, Tao; Liu, Yang; Chen, Yuan; Liu, Shihui; Maitz, Manfred F; Wang, Xue; Zhang, Kun; Wang, Jian; Wang, Yuan; Chen, Junying; Huang, Nan

2014-05-01

Restenosis, thrombosis formation and delayed endothelium regeneration continue to be problematic for coronary artery stent therapy. To improve the hemocompatibility of the cardiovascular implants and selectively direct vascular cell behavior, a novel kind of heparin/poly-l-lysine (Hep/PLL) nanoparticle was developed and immobilized on a dopamine-coated surface. The stability and structural characteristics of the nanoparticles changed with the Hep:PLL concentration ratio. A Hep density gradient was created on a surface by immobilizing nanoparticles with various Hep:PLL ratios on a dopamine-coated surface. Antithrombin III binding quantity was significantly enhanced, and in plasma the APTT and TT times as coagulation tests were prolonged, depending on the Hep density. A low Hep density is sufficient to prevent platelet adhesion and activation. The sensitivity of vascular cells to the Hep density is very different: high Hep density inhibits the growth of all vascular cells, while low Hep density could selectively inhibit smooth muscle cell hyperplasia but promote endothelial progenitor cells and endothelial cell proliferation. These observations provide important guidance for modification of surface heparinization. We suggest that this method will provide a potential means to construct a suitable platform on a stent surface for selective direction of vascular cell behavior with low side effects. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Identification of distinct topographical surface microstructures favoring either undifferentiated expansion or differentiation of murine embryonic stem cells.

PubMed

Markert, Lotte D'Andrea; Lovmand, Jette; Foss, Morten; Lauridsen, Rune Hoff; Lovmand, Michael; Füchtbauer, Ernst-Martin; Füchtbauer, Annette; Wertz, Karin; Besenbacher, Flemming; Pedersen, Finn Skou; Duch, Mogens

2009-11-01

The potential of embryonic stem (ES) cells for both self-renewal and differentiation into cells of all three germ layers has generated immense interest in utilizing these cells for tissue engineering or cell-based therapies. However, the ability to culture undifferentiated ES cells without the use of feeder cells as well as means to obtain homogeneous, differentiated cell populations devoid of residual pluripotent ES cells still remain major challenges. Here we have applied murine ES cells to topographically microstructured surface libraries, BioSurface Structure Arrays (BSSA), and investigated whether these could be used to (i) identify topographically microstructured growth supports alleviating the need for feeder cells for expansion of undifferentiated ES cells and (ii) identify specific types of microstructures enforcing differentiation of ES cells. The BSSA surfaces arrays consisted of 504 different topographical microstructures each located in a tester field of 3 x 3 mm. The murine ES cell lines CJ7 and KH2 were seeded upon the BSSA libraries and specific topographical structures facilitating either undifferentiated ES cell growth or enhancing spreading indicative of differentiation of the ES cells were identified. Secondly serial passage of undifferentiated CJ7 ES cells on selected microstructures, identified in the screening of these BSSA libraries, showed that these cells had retained germ-line potential. These results indicate that one specific type of topographical surface microstructures, identified by the BSSA technology, can substitute for feeder cells and that another subset may be used to eliminate undifferentiated ES cells from a population of differentiated ES cells.

Surface microstructures of daisy florets (Asteraceae) and characterization of their anisotropic wetting.

PubMed

Koch, Kerstin; Bennemann, Michael; Bohn, Holger F; Albach, Dirk C; Barthlott, Wilhelm

2013-09-01

The surface microstructures on ray florets of 62 species were characterized and compared with modern phylogenetic data of species affiliation in Asteraceae to determine sculptural patterns and their occurrence in the tribes of Asteraceae. Their wettability was studied to identify structural-induced droplet adhesion, which can be used for the development of artificial surfaces for water harvesting and passive surface water transport. The wettability was characterized by contact angle (CA) and tilt angle measurements, performed on fresh ray florets and their epoxy resin replica. The CAs on ray florets varied between 104° and 156°, but water droplets did not roll off when surface was tilted at 90°. Elongated cell structures and cuticle folding orientated in the same direction as the cell elongation caused capillary forces, leading to anisotropic wetting, with extension of water droplets along the length axis of epidermis cells. The strongest elongation of the droplets was also supported by a parallel, cell-overlapping cuticle striation. In artificial surfaces made of epoxy replica of ray florets, this effect was enhanced. The distribution of the identified four structural types exhibits a strong phylogenetic signal and allows the inference of an evolutionary trend in the modification of floret epidermal cells.

HIV-1 Promotes Intake of Leishmania Parasites by Enhancing Phosphatidylserine-Mediated, CD91/LRP-1-Dependent Phagocytosis in Human Macrophages

PubMed Central

Lodge, Robert; Ouellet, Michel; Barat, Corinne; Andreani, Guadalupe; Kumar, Pranav; Tremblay, Michel J.

2012-01-01

Over the past decade, the number of reported human immunodeficiency virus type-1 (HIV-1)/Leishmania co-infections has risen dramatically, particularly in regions where both diseases are endemic. Although it is known that HIV-1 infection leads to an increase in susceptibility to Leishmania infection and leishmaniasis relapse, little remains known on how HIV-1 contributes to Leishmania parasitaemia. Both pathogens infect human macrophages, and the intracellular growth of Leishmania is increased by HIV-1 in co-infected cultures. We now report that uninfected bystander cells, not macrophages productively infected with HIV-1, account for enhanced phagocytosis and higher multiplication of Leishmania parasites. This effect can be driven by HIV-1 Tat protein and transforming growth factor-beta (TGF-β). Furthermore, we show for the first time that HIV-1 infection increases surface expression of phosphatidylserine receptor CD91/LRP-1 on human macrophages, thereby leading to a Leishmania uptake by uninfected bystander cells in HIV-1-infected macrophage populations. The more important internalization of parasites is due to interactions between the scavenger receptor CD91/LRP-1 and phosphatidylserine residues exposed at the surface of Leishmania. We determined also that enhanced CD91/LRP-1 surface expression occurs rapidly following HIV-1 infection, and is triggered by the activation of extracellular TGF-β. Thus, these results establish an intricate link between HIV-1 infection, Tat, surface CD91/LRP-1, TGF-β, and enhanced Leishmania phosphatidylserine-mediated phagocytosis. PMID:22412921

Immobilization of gold nanoparticles on cell culture surfaces for safe and enhanced gold nanoparticle-mediated laser transfection.

PubMed

Kalies, Stefan; Heinemann, Dag; Schomaker, Markus; Gentemann, Lara; Meyer, Heiko; Ripken, Tammo

2014-01-01

In comparison to standard transfection methods, gold nanoparticle-mediated laser transfection has proven to be a versatile alternative. This is based on its minor influence on cell viability and its high efficiency, especially for the delivery of small molecules like small interfering RNA. However, in order to transfer it to routine usage, a safety aspect is of major concern: The avoidance of nanoparticle uptake by the cells is desired. The immobilization of the gold nanoparticles on cell culture surfaces can address this issue. In this study, we achieved this by silanization of the appropriate surfaces and the binding of gold nanoparticles to them. Comparable perforation efficiencies to the previous approaches of gold nanoparticle-mediated laser transfection with free gold nanoparticles are demonstrated. The uptake of the immobilized particles by the cells is unlikely. Consequently, these investigations offer the possibility of bringing gold nanoparticle-mediated laser transfection closer to routine usage.

Optimized organic photovoltaics with surface plasmons

NASA Astrophysics Data System (ADS)

Omrane, B.; Landrock, C.; Aristizabal, J.; Patel, J. N.; Chuo, Y.; Kaminska, B.

2010-06-01

In this work, a new approach for optimizing organic photovoltaics using nanostructure arrays exhibiting surface plasmons is presented. Periodic nanohole arrays were fabricated on gold- and silver-coated flexible substrates, and were thereafter used as light transmitting anodes for solar cells. Transmission measurements on the plasmonic thin film made of gold and silver revealed enhanced transmission at specific wavelengths matching those of the photoactive polymer layer. Compared to the indium tin oxide-based photovoltaic cells, the plasmonic solar cells showed overall improvements in efficiency up to 4.8-fold for gold and 5.1-fold for the silver, respectively.

Enhancing the corrosion resistance of the 2205 duplex stainless steel bipolar plates in PEMFCs environment by surface enriched molybdenum

NASA Astrophysics Data System (ADS)

Jinlong, Lv; Zhuqing, Wang; Tongxiang, Liang; Ken, Suzuki; Hideo, Miura

Surface molybdenum enrichment on 2205 duplex stainless steel was obtained by the ball milling technique. The electrochemical results showed molybdenum enrichment on the surface of 2205 duplex stainless steel improved its corrosion resistance in a typical proton exchange membrane fuel cell environment. This was mainly attributed to higher molybdenum content in the passive film formed on 2205 duplex stainless steel after ball milling. The decreased donor and acceptor concentrations improved significantly the corrosion resistance of surface molybdenum-enriched 2205 duplex stainless steel bipolar plates in the simulated cathodic proton exchange membrane fuel cells environment. In addition, the interfacial contact resistance of the 2205 duplex stainless steel bipolar plates slightly decreased due to surface molybdenum enrichment.

Surface modification of TiO2 nanotubes with osteogenic growth peptide to enhance osteoblast differentiation.

PubMed

Lai, Min; Jin, Ziyang; Su, Zhiguo

2017-04-01

To investigate the influence of surface-biofunctionalized substrates on osteoblast behavior, a layer of aligned TiO 2 nanotubes with a diameter of around 70nm was fabricated on titanium surface by anodization, and then osteogenic growth peptide (OGP) was conjugated onto TiO 2 nanotubes through the intermediate layer of polydopamine. The morphology, composition and wettability of different surfaces were characterized by field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements, respectively. The effects of OGP-modified TiO 2 nanotube substrates on the morphology, proliferation and differentiation of osteoblasts were examined in vitro. Immunofluorescence staining revealed that the OGP-functionalized TiO 2 nanotubes were favorable for cell spreading. However, there was no significant difference in cell proliferation observed among the different groups. Cells grown onto OGP-functionalized TiO 2 nanotubes showed significantly higher (p<0.05 or p<0.01) levels of alkaline phosphatase (ALP) and mineralization after 4, 7 and 14days of culture, respectively. Cells grown on OGP-functionalized TiO 2 nanotubes had significantly higher (p<0.05 or p<0.01) expression of osteogenic-related genes including runt related transcription factor 2 (Runx2), ALP, collagen type I (Col I), osteopontin (OPN) and osteocalcin (OC) after 14days of culture. These data suggest that surface functionalization of TiO 2 nanotubes with OGP was beneficial for cell spreading and differentiation. This study provides a novel platform for the development and fabrication of titanium-based implants that enhance the propensity for osseointegration between the native tissue and implant interface. Copyright © 2016 Elsevier B.V. All rights reserved.

CD4-CCR5 interaction in intracellular compartments contributes to receptor expression at the cell surface

PubMed Central

Achour, Lamia; Scott, Mark G.H.; Shirvani, Hamasseh; Thuret, Alain; Bismuth, Georges; Labbé-Jullié, Catherine; Marullo, Stefano

2009-01-01

The association of CD4, a glycoprotein involved in T cell development and antigen recognition, and CCR5, a chemotactic G protein-coupled receptor, which regulates trafficking and effector functions of immune cells, forms the main receptor for the human immunodeficiency virus HIV. We observed that the vast majority of CCR5 is maintained within the intracellular compartments of primary T lymphocytes and in a monocytic cell line, contrasting with its relative low density at the cell surface. The CCR5-CD4 association, which occurs in the endoplasmic reticulum, enhanced CCR5 export to the plasma membrane in a concentration–dependent manner, whereas inhibition of endogenous CD4 with small interfering RNAs decreased cell surface expression of endogenous CCR5. This effect was specific for CCR5, as CD4 did not affect cell distribution of CXCR4, the other HIV co-receptor. These results reveal a previously unappreciated role of CD4, which contributes to regulate CCR5 export to the plasma membrane. PMID:19064722

The effect of oxygen plasma pretreatment and incubation in modified simulated body fluids on the formation of bone-like apatite on poly(lactide-co-glycolide) (70/30).

PubMed

Qu, Xue; Cui, Wenjin; Yang, Fei; Min, Changchun; Shen, Hong; Bei, Jianzhong; Wang, Shenguo

2007-01-01

In this study, biodegradable poly(lactide-co-glycolide) (PLGA) (70/30) films and scaffolds were first treated with oxygen plasma and then incubated in a modified simulated body fluid 1.5SBF0 to prepare a bone-like apatite layer. The formation of the apatite and its influence on osteoblast-like cells growth were investigated. It was found that the bone-like apatite formability of PLGA(70/30) was enhanced by plasma pretreatment. The changes of surface chemistry and surface topography induced by oxygen plasma treatment were both effective for apatite formation. The apatite formability increased with increasing plasma-treating time. Under a treating condition of 20 W for 30 min, oxygen plasma treatment could penetrate into the inner scaffold. After 6 days incubation, the apatite formed in plasma-treated scaffold was better distributed than in untreated scaffold, and the weight and mechanical strength of the plasma-treated scaffold were both enhanced. Compared with PLGA(70/30), the apatite layer formed on oxygen plasma-treated PLGA(70/30) surface enhanced adhesion and proliferation of OCT-1 osteoblast-like cell, but had no significant effect on cell's ALP activity at day 7. A prolonged investigation is being in process to further verify the bone-like apatite effects on osteogenic differentiation.

Short- and medium-chain fatty acids enhance the cell surface expression and transport capacity of the bile salt export pump (BSEP/ABCB11).

PubMed

Kato, Takuya; Hayashi, Hisamitsu; Sugiyama, Yuichi

2010-09-01

The reduced expression of the bile salt export pump (BSEP/ABCB11) at the canalicular membrane is associated with cholestasis-induced hepatotoxicity due to the accumulation of bile acids in hepatocytes. We previously reported that 4-phenylbutyrate (4PBA), an approved drug for urea cycle disorders, is a promising agent for intrahepatic cholestasis because it increases both the cell surface expression and the transport capacity of BSEP. In the present study, we searched for effective compounds other than 4PBA by focusing on short- and medium-chain fatty acids, which have similar characteristics to 4PBA such as their low-molecular-weight and a carboxyl group. In transcellular transport studies using Madin-Darby canine kidney (MDCK) II cells, all short- and medium-chain fatty acids tested except for formate, acetate, and hexanoic acid showed more potent effects on wild type (WT) BSEP-mediated [3H]taurocholate transport than did 4PBA. The increase in WT BSEP transport with butyrate and octanoic acid treatment correlated with an increase in its expression at the cell surface. Two PFIC2-type variants, E297G and D482G BSEP, were similarly affected with both compounds treatment. The prolonged half-life of cell surface-resident WT BSEP was responsible for this increased octanoic acid-stimulated transport, but not for that of butyrate. In conclusion, short- and medium-chain fatty acids have potent effects on the increase in WT and PFIC2-type BSEP-mediated transport in MDCK II cells. Although both short- and medium-chain fatty acids enhance the transport capacity of WT and PFIC2-type BSEP by inducing those expressions at the cell surface, the underlying mechanism seems to differ between fatty acids. 2010 Elsevier B.V. All rights reserved.

E-beam deposited Ag-nanoparticles plasmonic organic solar cell and its absorption enhancement analysis using FDTD-based cylindrical nano-particle optical model.

PubMed

Kim, Richard S; Zhu, Jinfeng; Park, Jeung Hun; Li, Lu; Yu, Zhibin; Shen, Huajun; Xue, Mei; Wang, Kang L; Park, Gyechoon; Anderson, Timothy J; Pei, Qibing

2012-06-04

We report the plasmon-assisted photocurrent enhancement in Ag-nanoparticles (Ag-NPs) embedded PEDOT:PSS/P3HT:PCBM organic solar cells, and systematically investigate the causes of the improved optical absorption based on a cylindrical Ag-NPs optical model which is simulated with a 3-Dimensional finite difference time domain (FDTD) method. The proposed cylindrical Ag-NPs optical model is able to explain the optical absorption enhancement by the localized surface plasmon resonance (LSPR) modes, and to provide a further understanding of Ag-NPs shape parameters which play an important role to determine the broadband absorption phenomena in plasmonic organic solar cells. A significant increase in the power conversion efficiency (PCE) of the plasmonic solar cell was experimentally observed and compared with that of the solar cells without Ag-NPs. Finally, our conclusion was made after briefly discussing the electrical effects of the fabricated plasmonic organic solar cells.

Lenalidomide enhances the function of chimeric antigen receptor T cells against the epidermal growth factor receptor variant III by enhancing immune synapses.

PubMed

Kuramitsu, S; Ohno, M; Ohka, F; Shiina, S; Yamamichi, A; Kato, A; Tanahashi, K; Motomura, K; Kondo, G; Kurimoto, M; Senga, T; Wakabayashi, T; Natsume, A

2015-10-01

The epidermal growth factor receptor variant III (EGFRvIII) is exclusively expressed on the cell surface in ~50% of glioblastoma multiforme (GBM). This variant strongly and persistently activates the phosphatidylinositol 3-kinase-Akt signaling pathway in a ligand-independent manner resulting in enhanced tumorigenicity, cellular motility and resistance to chemoradiotherapy. Our group generated a recombinant single-chain variable fragment (scFv) antibody specific to the EGFRvIII, referred to as 3C10-scFv. In the current study, we constructed a lentiviral vector transducing the chimeric antigen receptor (CAR) that consisted of 3C10-scFv, CD3ζ, CD28 and 4-1BB (3C10-CAR). The 3C10-CAR-transduced peripheral blood mononuclear cells (PBMCs) and CD3(+) T cells specifically lysed the glioma cells that express EGFRvIII. Moreover, we demonstrated that CAR CD3(+) T cells migrated to the intracranial xenograft of GBM in the mice treated with 3C10-CAR PBMCs. An important and novel finding of our study was that a thalidomide derivative lenalidomide induced 3C10-CAR PBMC proliferation and enhanced the persistent antitumor effect of the cells in vivo. Lenalidomide also exhibited enhanced immunological synapses between the effector cells and the target cells as determined by CD11a and F-actin polymerization. Collectively, lentiviral-mediated transduction of CAR effectors targeting the EGFRvIII showed specific efficacy, and lenalidomide even intensified CAR cell therapy by enhanced formation of immunological synapses.

Synergistic influence of polyoxometalate surface corona towards enhancing the antibacterial performance of tyrosine-capped Ag nanoparticles.

PubMed

Daima, Hemant K; Selvakannan, P R; Kandjani, Ahmad E; Shukla, Ravi; Bhargava, Suresh K; Bansal, Vipul

2014-01-21

We illustrate a new strategy to improve the antibacterial potential of silver nanoparticles (AgNPs) by their surface modification with the surface corona of biologically active polyoxometalates (POMs). The stable POM surface corona was achieved by utilising zwitterionic tyrosine amino acid as a pH-switchable reducing and capping agent of AgNPs. The general applicability of this approach was demonstrated by developing surface coronas of phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) around AgNPs. Our investigations on Gram negative bacterium Escherichia coli demonstrate that in conjugation with AgNPs, the surface corona of POMs enhances the physical damage to the bacterial cells due to synergistic antibacterial action of AgNPs and POMs, and the ability of tyrosine-reduced AgNPs (AgNPs(Y)) to act as an excellent carrier and stabiliser for the POMs. The further extension of this study towards Gram positive bacterium Staphylococcus albus showed a similar toxicity pattern, whereas these nanomaterials were found to be biocompatible for PC3 epithelial mammalian cells, suggesting the potential of these materials towards specific antimicrobial targeting for topical wound healing applications. The outcomes of this work show that facile tailorability of nanostructured surfaces may play a considerable role in controlling the biological activities of different nanomaterials.

Mitigated reactive oxygen species generation leads to an improvement of cell proliferation on poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] functionalized polydimethylsiloxane surfaces.

PubMed

Yu, Ling; Shi, ZhuanZhuan; Gao, LiXia; Li, ChangMing

2015-09-01

In vitro cell-based analysis is strongly affected by material's surface chemical properties. The cell spreading, migration, and proliferation on a substrate surface are initiated and controlled by successful adhesion, particularly for anchor-dependent cells. Unfortunately, polydimethylsiloxane (PDMS), one of the most used polymeric materials for construction of microfluidic and miniaturized biomedical analytic devices, is not a cell-friendly surface because of its inherent hydrophobic property. Herein, a poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] (poly(GMA-co-pEGMA)) polymer brush was synthesized on a PDMS surface through a surface-initiated atom-transfer radical polymerization method. Contact angle and Fourier transform infrared characterization show that the poly (GMA-co-pEGMA) polymer brush functionalization can increase wettability of PDMS and introduce epoxy, hydroxyl, and ether groups into PDMS surface. In vitro cell growth assay demonstrates that cell adhesion and proliferation on poly(GMA-co-pEGMA) polymer brush-functionalized PDMS (poly(GMA-co-pEGMA)@PDMS) are better than on pristine PDMS. Additionally, immobilization of collagen type I (CI) and fibronectin (FN) on poly(GMA-co-pEGMA)@PDMS is better than direct coating of CI and FN on pristine PDMS to promote cell adhesion. Furthermore, increased intracellular reactive oxygen species and cell mitochondrial membrane depolarization, two indicators of cell oxidative stress, are observed from cells growing on pristine PDMS, but not from those on poly(GMA-co-pEGMA)@PDMS. Collectively, we demonstrate that poly(GMA-co-pEGMA) functionalization can enhance cell adhesion and proliferation on PDMS, and thus can be potentially used for microfluidic cell assay devices for cellular physiology study or drug screening. © 2015 Wiley Periodicals, Inc.

Plasmonic nanoparticles enhanced dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Xu, Qi; Liu, Fang; Meng, Weisi; Huang, Yidong

2013-12-01

Here we present investigations on utilizing two kinds of plasmonic nanoparticles (NPs) to enhance the efficiency of dye sensitized solar cells (DSCs). The Au@PVP NPs is proposed and present the specialty of adhesiveness to dye molecules, which could help to localize additional dye molecules near the plasmonic NPs, hence increasing the optical absorption consequently the power conversion efficiency (PCE) of the DSCs by 30% from 3.3% to 4.3%. Meanwhile, an irregular Au-Ag alloy popcorn-shaped NPs (popcorn NPs) with plenty of fine structures is also proposed and realized to enhance the light absorption of DSC. A pronounced absorption enhancement in a broadband wavelength range is observed due to the excitation of localized surface plasmon at different wavelengths. The PCE is enhanced by 32% from 5.94% to 7.85%.

A hybrid substratum for primary hepatocyte culture that enhances hepatic functionality with low serum dependency

PubMed Central

Meng, Qingyuan; Tao, Chunsheng; Qiu, Zhiye; Akaike, Toshihiro; Cui, Fuzhai; Wang, Xiumei

2015-01-01

Cell culture systems have proven to be crucial for the in vitro maintenance of primary hepatocytes and the preservation of hepatic functional expression at a high level. A poly-(N-p-vinylbenzyl-4-O-β-D-galactopyranosyl-D-gluconamide) matrix can recognize cells and promote liver function in a spheroid structure because of a specific galactose–asialoglycoprotein receptor interaction. Meanwhile, a fusion protein, E-cadherin-Fc, when incubated with various cells, has shown an enhancing effect on cellular viability and metabolism. Therefore, a hybrid substratum was developed for biomedical applications by using both of these materials to combine their advantages for primary hepatocyte cultures. The isolated cells showed a monolayer aggregate morphology on the coimmobilized surface and displayed higher functional expression than cells on traditional matrices. Furthermore, the hybrid system, in which the highest levels of cell adhesion and hepatocellular metabolism were achieved with the addition of 1% fetal bovine serum, showed a lower serum dependency than the collagen/gelatin-coated surface. Accordingly, this substrate may attenuate the negative effects of serum and further contribute to establishing a defined culture system for primary hepatocytes. PMID:25848252

Structural alterations in Pseudomonas aeruginosa by zingerone contribute to enhanced susceptibility to antibiotics, serum and phagocytes.

PubMed

Kumar, Lokender; Chhibber, Sanjay; Harjai, Kusum

2014-11-04

Excessive use of antibiotics has led to evolutionary adaptation resulting in emergence of multidrug resistance in P. aeruginosa. The aim of the present study was oriented towards exploiting zingerone (active component of ginger) in making P. aeruginosa more susceptible to killing with antibiotics, humoral/cellular defences and studying its underlying mechanism. Effect of zingerone treatment on antibiotic susceptibility, serum, and phagocytic killing of P. aeruginosa was studied. The underlying mechanism was evaluated in terms of cell surface hydrophobicity, alginate and LPS production. TNF-α and MIP-2 cytokine production by mouse macrophages was also checked. Structural analysis was carried out using scanning electron microscopy (SEM) and liquid chromatography-mass spectrometry (LC-MS) analysis. Zingerone treated cells showed increased susceptibility to variety of antibiotics, serum as well as macrophages (p<0.05). Zingerone treatment significantly reduced cell surface hydrophobicity, alginate and LPS production (p<0.05). Zingerone treated cells showed significant decrease in TNF-α and MIP-2 cytokine production as compared to non-treated cells. Coupled with this, reduction in the production of extracellular protective matrix and modulation of chemical structure of LPS was also observed by scanning electron microscopy and liquid chromatography-mass spectrometric (LC-MS) respectively. Zingerone significantly influence surface structure of P. aeruginosa which contributes towards enhanced susceptibility to antibiotics and innate immune system. Use of phytochemicals may prove to be a novel therapeutic approach by enhancing susceptibility of pathogenic microorganisms to antibiotics and immune system. Zingerone has proved to be one such agent which can be employed as a potential anti-virulent drug candidate against P. aeruginosa infections. Copyright © 2014 Elsevier Inc. All rights reserved.

Reduction and shaping of graphene-oxide by laser-printing for controlled bone tissue regeneration and bacterial killing

NASA Astrophysics Data System (ADS)

Palmieri, Valentina; Barba, Marta; Di Pietro, Lorena; Gentilini, Silvia; Chiara Braidotti, Maria; Ciancico, Carlotta; Bugli, Francesca; Ciasca, Gabriele; Larciprete, Rosanna; Lattanzi, Wanda; Sanguinetti, Maurizio; De Spirito, Marco; Conti, Claudio; Papi, Massimiliano

2018-01-01

Graphene and graphene oxide (GO) are capable of inducing stem cells differentiation into bone tissue with variable efficacy depending on reductive state of the material. Thus, modulation of osteogenic process and of bone mineral density distribution is theoretically possible by controlling the GO oxidative state. In this study, we laser-printed GO surfaces in order to obtain both a local photo-thermal GO reduction and the formation of nano-wrinkles along precise geometric pattern. Initially, after cells adhered on the surface, stem cells migrated and accumulated on the reduced and wrinkled surface. When the local density of the stem cells on the reduced stripes was high, cells started to proliferate and occupy the oxidized/flat area. The designed surfaces morphology guided stem cell orientation and the reduction accelerated differentiation. Furthermore the reduced sharp nano-wrinkles were able to enhance the GO antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), a common cause of prosthetic joints infections. This strategy can offer a revolution in present and future trends of scaffolds design for regenerative medicine.

Porous SiO2 nanofiber grafted novel bioactive glass-ceramic coating: A structural scaffold for uniform apatite precipitation and oriented cell proliferation on inert implant.

PubMed

Das, Indranee; De, Goutam; Hupa, Leena; Vallittu, Pekka K

2016-05-01

A composite bioactive glass-ceramic coating grafted with porous silica nanofibers was fabricated on inert glass to provide a structural scaffold favoring uniform apatite precipitation and oriented cell proliferation. The coating surfaces were investigated thoroughly before and after immersion in simulated body fluid. In addition, the proliferation behavior of fibroblast cells on the surface was observed for several culture times. The nanofibrous exterior of this composite bioactive coating facilitated homogeneous growth of flake-like carbonated hydroxyapatite layer within a short period of immersion. Moreover, the embedded porous silica nanofibers enhanced hydrophilicity which is required for proper cell adhesion on the surface. The cells proliferated well following a particular orientation on the entire coating by the assistance of nanofibrous scaffold-like structural matrix. This newly engineered composite coating was effective in creating a biological structural matrix favorable for homogeneous precipitation of calcium phosphate, and organized cell growth on the inert glass surface. Copyright © 2016 Elsevier B.V. All rights reserved.

Specific Biomimetic Hydroxyapatite Nanotopographies Enhance Osteoblastic Differentiation and Bone Graft Osteointegration

PubMed Central

Loiselle, Alayna E.; Wei, Lai; Faryad, Muhammad; Paul, Emmanuel M.; Lewis, Gregory S.; Gao, Jun; Lakhtakia, Akhlesh

2013-01-01

Impaired healing of cortical bone grafts represents a significant clinical problem. Cadaveric bone grafts undergo extensive chemical processing to decrease the risk of disease transmission; however, these processing techniques alter the bone surface and decrease the osteogenic potential of cells at the healing site. Extensive work has been done to optimize the surface of bone grafts, and hydroxyapatite (HAP) and nanotopography both increase osteoblastic differentiation. HAP is the main mineral component of bone and can enhance osteoblastic differentiation and bone implant healing in vivo, while nanotopography can enhance osteoblastic differentiation, adhesion, and proliferation. This is the first study to test the combined effects of HAP and nanotopographies on bone graft healing. With the goal of identifying the optimized surface features to improve bone graft healing, we tested the hypothesis that HAP-based nanotopographic resurfacing of bone grafts improves integration of cortical bone grafts by enhancing osteoblastic differentiation. Here we show that osteoblastic cells cultured on processed bones coated with specific-scale (50–60 nm) HAP nanotopographies display increased osteoblastic differentiation compared to cells on uncoated bone, bones coated with poly-l-lactic acid nanotopographies, or other HAP nanotopographies. Further, bone grafts coated with 50–60-nm HAP exhibited increased formation of new bone and improved healing, with mechanical properties equivalent to live autografts. These data indicate the potential for specific HAP nanotopographies to not only increase osteoblastic differentiation but also improve bone graft incorporation, which could significantly increase patient quality of life after traumatic bone injuries or resection of an osteosarcoma. PMID:23510012

Radiation induces an antitumour immune response to mouse melanoma.

PubMed

Perez, Carmen A; Fu, Allie; Onishko, Halina; Hallahan, Dennis E; Geng, Ling

2009-12-01

Irradiation of cancer cells can cause immunogenic death. We used mouse models to determine whether irradiation of melanoma can enhance the host antitumour immune response and function as an effective vaccination strategy, and investigated the molecular mechanisms involved in this radiation-induced response. For in vivo studies, C57BL6/J mice and the B16F0 melanoma cell line were used in a lung metastasis model, intratumoural host immune activation assays, and tumour growth delay studies. In vitro studies included a dendritic cell (DC) phagocytosis assay, detection of cell surface exposure of the protein calreticulin (CRT), and small interfering RNA (siRNA)-mediated depletion of CRT cellular levels. Irradiation of cutaneous melanomas prior to their resection resulted in more than 20-fold reduction in lung metastases after systemic challenge with untreated melanoma cells. A syngeneic vaccine derived from irradiated melanoma cells also induced adaptive immune response markers in irradiated melanoma implants. Our data indicate a trend for radiation-induced increase in melanoma cell surface exposure of CRT, which is involved in the enhanced phagocytic activity of DC against irradiated melanoma cells (VIACUC). The present study suggests that neoadjuvant irradiation of cutaneous melanoma tumours prior to surgical resection can stimulate an endogenous anti-melanoma host immune response.

Cancer cell membrane-coated magnetic nanoparticles for MR/NIR fluorescence dual-modal imaging and photodynamic therapy.

PubMed

Li, Jiong; Wang, Xuandong; Zheng, Dongye; Lin, Xinyi; Wei, Zuwu; Zhang, Da; Li, Zhuanfang; Zhang, Yun; Wu, Ming; Liu, Xiaolong

2018-05-22

Theranostic nanoprobes integrated with dual-modal imaging and therapeutic functions, such as photodynamic therapy (PDT), have exhibited significant potency in cancer treatments due to their high imaging accuracy and non-invasive advantages for cancer elimination. However, biocompatibility and highly efficient accumulation of these nanoprobes in tumor are still unsatisfactory for clinical application. In this study, a photosensitizer -loaded magnetic nanobead with surface further coated with a layer of cancer cell membrane (SSAP-Ce6@CCM) was designed to improve the biocompatibility and cellular uptake and ultimately achieve enhanced MR/NIR fluorescence imaging and PDT efficacy. Compared with similar nanobeads without CCM coating, SSAP-Ce6@CCM showed significantly enhanced cellular uptake, as evidenced by Prussian blue staining, confocal laser scanning microscopy (CLSM) and flow cytometric analysis. Consequently, SSAP-Ce6@CCM displayed a more distinct MR/NIR imaging ability and more obvious photo-cytotoxicity towards cancer cells under 670 nm laser irradiation. Furthermore, the enhanced PDT effect benefited from the surface coating of cancer cell membrane was demonstrated in SMMC-7721 tumor-bearing mice through tumor growth observation and tumor tissue pathological examination. Therefore, this CCM-disguised nanobead that integrated the abilities of MR/NIR fluorescence dual-modal imaging and photodynamic therapy might be a promising theranostic platform for tumor treatment.

Poly(γ-glutamic acid)-coated lipoplexes loaded with Doxorubicin for enhancing the antitumor activity against liver tumors

NASA Astrophysics Data System (ADS)

Qi, Na; Tang, Bo; Liu, Guang; Liang, Xingsi

2017-05-01

The study was to develop poly-γ-glutamic acid (γ-PGA)-coated Doxorubicin (Dox) lipoplexes that enhance the antitumor activity against liver tumors. γ-PGA-coated lipoplexes were performed by electrostatistically attracting to the surface of cationic charge liposomes with anionic γ-PGA. With the increasing of γ-PGA concentration, the particle size of γ-PGA-coated Dox lipoplexes slightly increased, the zeta potential from positive shifted to negative, and the entrapment efficiency (EE) were no significant change. The release rate of γ-PGA-coated Dox lipoplexes slightly increased at acidic pH, the accelerated Dox release might be attributed to greater drug delivery to tumor cells, resulting in a higher antitumor activity. Especially, γ-PGA-coated Dox lipoplexes exhibited higher cellular uptake, significant in vitro cytotoxicity in HepG2 cells, and improved in vivo antitumor efficacy toward HepG2 hepatoma-xenografted nude models in comparison with Dox liposomes and free Dox solution. In addition, the analysis results via flow cytometry showed that γ-PGA-coated Dox lipoplexes induce S phase cell cycle arrest and significantly increased apoptosis rate of HepG2 cells. In conclusion, the presence of γ-PGA on the surface of Dox lipoplexes enhanced antitumor effects of liver tumors.

Surface-Enhanced Raman Scattering Active Plasmonic Nanoparticles with Ultrasmall Interior Nanogap for Multiplex Quantitative Detection and Cancer Cell Imaging.

PubMed

Li, Jiuxing; Zhu, Zhi; Zhu, Bingqing; Ma, Yanli; Lin, Bingqian; Liu, Rudi; Song, Yanling; Lin, Hui; Tu, Song; Yang, Chaoyong

2016-08-02

Due to its large enhancement effect, nanostructure-based surface-enhanced Raman scattering (SERS) technology had been widely applied for bioanalysis and cell imaging. However, most SERS nanostructures suffer from poor signal reproducibility, which hinders the application of SERS nanostructures in quantitative detection. We report an etching-assisted approach to synthesize SERS-active plasmonic nanoparticles with 1 nm interior nanogap for multiplex quantitative detection and cancer cell imaging. Raman dyes and methoxy poly(ethylene glycol) thiol (mPEG-SH) were attached to gold nanoparticles (AuNPs) to prepare gold cores. Next, Ag atoms were deposited on gold cores in the presence of Pluronic F127 to form a Ag shell. HAuCl4 was used to etch the Ag shell and form an interior nanogap in Au@AgAuNPs, leading to increased Raman intensity of dyes. SERS intensity distribution of Au@AgAuNPs was found to be more uniform than that of aggregated AuNPs. Finally, Au@AgAuNPs were used for multiplex quantitative detection and cancer cell imaging. With the advantages of simple and rapid preparation of Au@AgAuNPs with highly uniform, stable, and reproducible Raman intensity, the method reported here will widen the applications of SERS-active nanoparticles in diagnostics and imaging.

Effect of bone sialoprotein and collagen coating on cell attachment to TICER and pure titanium implant surfaces.

PubMed

Graf, H-L; Stoeva, S; Armbruster, F P; Neuhaus, J; Hilbig, H

2008-07-01

To improve integration between implants and biological tissues, this study compared bone sialoprotein (BSP) as a surface-coating material against the major organic and inorganic components of bone, collagen type I and hydroxyapatite (TICER). The expression of osteocalcin, osteonectin and transforming growth factor ss was evaluated using immunohistochemical staining procedures. The distribution patterns of osteoblasts on the surface of pure titanium with a smooth machined surface and a rough surface (TICER) were determined by image processing using confocal laser scanning microscopy. The results compared to uncoated control materials showed that, at all times investigated, the number of cells on the surface of the TICER and pure titanium samples differed significantly (P<0.1), demonstrating the superiority of TICER over pure titanium in this respect. For pure titanium implants, collagen-precoated surfaces were not beneficial for the attachment of bone-derived cells with the exception of day 3 in vitro (P<0.01). BSP-precoated implant surfaces displayed non-significantly higher numbers of settled cells. BSP-precoated implant surfaces were beneficial for osteoinduction as revealed by osteocalcin and osteonectin expression. BSP precoating of the rough TICER implant surface enhanced the osteoinductive effect much more than did collagen precoating. These results contribute to the consideration of at least two distinct pathways of osseointegration.

The interaction between LYVE-1 with hyaluronan on the cell surface may play a role in the diversity of adhesion to cancer cells.

PubMed

Du, Yan; Liu, Hua; He, Yiqing; Liu, Yiwen; Yang, Cuixia; Zhou, Muqing; Wang, Wenjuan; Cui, Lian; Hu, Jiajie; Gao, Feng

2013-01-01

Hyaluronan (HA), a simple disaccharide unit, can polymerize and is considered a primary component of the extracellular matrix, which has a wide range of biological functions. In recent years, HA was found on the surface of tumor cells. According to previous reports, differing HA content on the cell surface of tumor cells is closely related to lymph node metastases, but the mechanisms mediating this process remained unclear. This research intended to study the surface content of HA on tumor cells and analyze cell adhesive changes caused by the interaction between HA and its lymphatic endothelial receptor (LYVE-1). We screened and observed high HA content on HS-578T breast cells and low HA content on MCF-7 breast cells through particle exclusion, immunofluorescence and flow cytometry experiments. The expression of LYVE-1, the lymph-vessel specific HA receptor, was consistent with our previous report and enhanced the adhesion of HA(high)-HS-578T cells to COS-7(LYVE-1(+)) through HA in cell static adhesion and dynamic parallel plate flow chamber experiments. MCF-7 breast cells contain little HA on the surface; however, our results showed little adhesion difference between MCF-7 cells and COS-7(LYVE-1(+)) and COS-7(LYVE-1(-)) cells. Similar results were observed concerning the adhesion of HS-578T cells or MCF-7 cells to SVEC4-10 cells. Furthermore, we observed for the first time that the cell surface HA content of high transfer tumor cells was rich, and we visualized the cross-linking of HA cable structures, which may activate LYVE-1 on lymphatic endothelial cells, promoting tumor adhesion. In summary, high-low cell surface HA content of tumor cells through the interaction with LYVE-1 leads to adhesion differences.

Preparing neural stem/progenitor cells in PuraMatrix hydrogel for transplantation after brain injury in rats: A comparative methodological study.

PubMed

Aligholi, Hadi; Rezayat, Seyed Mahdi; Azari, Hassan; Ejtemaei Mehr, Shahram; Akbari, Mohammad; Modarres Mousavi, Seyed Mostafa; Attari, Fatemeh; Alipour, Fatemeh; Hassanzadeh, Gholamreza; Gorji, Ali

2016-07-01

Cultivation of neural stem/progenitor cells (NS/PCs) in PuraMatrix (PM) hydrogel is an option for stem cell transplantation. The efficacy of a novel method for placing adult rat NS/PCs in PM (injection method) was compared to encapsulation and surface plating approaches. In addition, the efficacy of injection method for transplantation of autologous NS/PCs was studied in a rat model of brain injury. NS/PCs were obtained from the subventricular zone (SVZ) and cultivated without (control) or with scaffold (three-dimensional cultures; 3D). The effect of different approaches on survival, proliferation, and differentiation of NS/PCs were investigated. In in vivo study, brain injury was induced 45 days after NS/PCs were harvested from the SVZ and phosphate buffered saline, PM, NS/PCs, or PM+NS/PCs were injected into the brain lesion. There was an increase in cell viability and proliferation after injection and surface plating of NS/PCs compared to encapsulation and neural differentiation markers were expressed seven days after culturing the cells. Using injection method, transplantation of NS/PCs cultured in PM resulted in significant reduction of lesion volume, improvement of neurological deficits, and enhancement of surviving cells. In addition, the transplanted cells could differentiate in to neurons, astrocytes, or oligodendrocytes. Our results indicate that the injection and surface plating methods enhanced cell survival and proliferation of NS/PCs and suggest the injection method as a promising approach for transplantation of NS/PCs in brain injury. Copyright © 2016 Elsevier B.V. All rights reserved.

Improving Si solar cell performance using Mn:ZnSe quantum dot-doped PLMA thin film

PubMed Central

2013-01-01

Poly(lauryl methacrylate) (PLMA) thin film doped with Mn:ZnSe quantum dots (QDs) was spin-deposited on the front surface of Si solar cell for enhancing the solar cell efficiency via photoluminescence (PL) conversion. Significant solar cell efficiency enhancements (approximately 5% to 10%) under all-solar-spectrum (AM0) condition were observed after QD-doped PLMA coatings. Furthermore, the real contribution of the PL conversion was precisely assessed by investigating the photovoltaic responses of the QD-doped PLMA to monochromatic and AM0 light sources as functions of QD concentration, combined with reflectance and external quantum efficiency measurements. At a QD concentration of 1.6 mg/ml for example, among the efficiency enhancement of 5.96%, about 1.04% was due to the PL conversion, and the rest came from antireflection. Our work indicates that for the practical use of PL conversion in solar cell performance improvement, cautions are to be taken, as the achieved efficiency enhancement might not be wholly due to the PL conversion. PMID:23787125

Surface Modified Biodegradable Electrospun Membranes as a Carrier for Human Embryonic Stem Cell-Derived Retinal Pigment Epithelial Cells.

PubMed

Sorkio, Anni; Porter, Patrick J; Juuti-Uusitalo, Kati; Meenan, Brian J; Skottman, Heli; Burke, George A

2015-09-01

Human embryonic stem cell-derived retinal pigment epithelial (hESC-RPE) cells are currently undergoing clinical trials to treat retinal degenerative diseases. Transplantation of hESC-RPE cells in conjuction with a supportive biomaterial carrier holds great potential as a future treatment for retinal degeneration. However, there has been no such biodegradable material that could support the growth and maturation of hESC-RPE cells so far. The primary aim of this work was to create a thin porous poly (L-lactide-co-caprolactone) (PLCL) membrane that could promote attachment, proliferation, and maturation of the hESC-RPE cells in serum-free culture conditions. The PLCL membranes were modified by atmospheric pressure plasma processing and coated with collagen IV to enhance cell growth and maturation. Permeability of the membranes was analyzed with an Ussing chamber system. Analysis with scanning electron microscopy, contact angle measurement, atomic force microscopy, and X-ray photoelectron spectroscopy demonstrated that plasma surface treatment augments the surface properties of the membrane, which enhances the binding and conformation of the protein. Cell proliferation assays, reverse transcription-polymerase chain reaction, indirect immunofluoresence staining, trans-epithelial electrical resistance measurements, and in vitro phagocytosis assay clearly demonstrated that the plasma treated PLCL membranes supported the adherence, proliferation, maturation and functionality of hESC-RPE cells in serum-free culture conditions. Here, we report for the first time, how PLCL membranes can be modified with atmospheric pressure plasma processing to enable the formation of a functional hESC-RPE monolayer on a porous biodegradable substrate, which have a potential as a tissue-engineered construct for regenerative retinal repair applications.

Conversion of Stationary to Invasive Tumor Initiating Cells (TICs): Role of Hypoxia in Membrane Type 1-Matrix Metalloproteinase (MT1-MMP) Trafficking

PubMed Central

Li, Jian; Zucker, Stanley; Pulkoski-Gross, Ashleigh; Kuscu, Cem; Karaayvaz, Mihriban; Ju, Jingfang; Yao, Herui; Song, Erwei; Cao, Jian

2012-01-01

Emerging evidence has implicated the role of tumor initiating cells (TICs) in the process of cancer metastasis. The mechanism underlying the conversion of TICs from stationary to invasive remains to be characterized. In this report, we employed less invasive breast cancer TICs, SK-3rd, that displays CD44high/CD24low with high mammosphere-forming and tumorigenic capacities, to investigate the mechanism by which stationary TICs are converted to invasive TICs. Invasive ability of SK-3rd TICs was markedly enhanced when the cells were cultured under hypoxic conditions. Given the role of membrane type 1-matrix metalloproteinase (MT1-MMP) in cancer invasion/metastasis, we explored a possible involvement of MT1-MMP in hypoxia-induced TIC invasion. Silencing of MT1-MMP by a shRNA approach resulted in diminution of hypoxia-induced cell invasion in vitro and metastasis in vivo. Under hypoxic conditions, MT1-MMP redistributed from cytoplasmic storage pools to the cell surface of TICs, which coincides with the increased cell invasion. In addition, CD44, a cancer stem-like cell marker, inversely correlated with increased cell surface MT1-MMP. Interestingly, cell surface MT1-MMP gradually disappeared when the hypoxia-treated cells were switched to normoxia, suggesting the plasticity of TICs in response to oxygen content. Furthermore, we dissected the pathways leading to upregulated MT1-MMP in cytoplasmic storage pools under normoxic conditions, by demonstrating a cascade involving Twist1-miR10b-HoxD10 leading to enhanced MT1-MMP expression in SK-3rd TICs. These observations suggest that MT1-MMP is a key molecule capable of executing conversion of stationary TICs to invasive TICs under hypoxic conditions and thereby controlling metastasis. PMID:22679501

SaOS-2 cell response to macro-porous boron-incorporated TiO2 coating prepared by micro-arc oxidation on titanium.

PubMed

Huang, Qianli; Elkhooly, Tarek A; Liu, Xujie; Zhang, Ranran; Yang, Xing; Shen, Zhijian; Feng, Qingling

2016-10-01

The aims of the present study were to develop boron-incorporated TiO2 coating (B-TiO2 coating) through micro-arc oxidation (MAO) and subsequently evaluate the effect of boron incorporation on the in vitro biological performance of the coatings. The physicochemical properties of B-TiO2 coating and its response to osteoblast like cells (SaOS-2) were investigated compared to the control group without boron (TiO2 coating). The morphological and X-ray diffraction results showed that both coatings exhibited similar surface topography and phase composition, respectively. However, the incorporation of B led to an enhancement in the surface hydrophilicity of B-TiO2 coating. The spreading of SaOS-2 cells on B-TiO2 coating was faster than that on TiO2 coating. The proliferation rate of SaOS-2 cells cultured on B-TiO2 decreased after 5days of culture compared to that on TiO2 coating. SaOS-2 cells cultured on B-TiO2 coating exhibited an enhanced alkaline phosphatase (ALP) activity, Collagen I synthesis and in vitro mineralization compared to those on TiO2 coating. The present findings suggest that B-TiO2 coating is a promising candidate surface for orthopedic implants. Copyright © 2016 Elsevier B.V. All rights reserved.

Inhibition and enhancement of microbial surface colonization: the role of silicate composition

USGS Publications Warehouse

Roberts, Jennifer A.

2004-01-01

Classical treatment of cell attachment by models of filtration or coulombic attraction assumes that attachment of cells to mineral surfaces would be controlled by factors such as response to predation, collision efficiency, or coulombic attraction between the charged groups at the mineral and cell surfaces. In the study reported here, the passive model of attachment was investigated using a native microbial consortium and a variety of Al- and Fe-bearing silicates and oxides to determine if other controls, such as mineral composition, also influence the interaction between cells and surfaces. Results from in situ colonization studies in an anaerobic groundwater at pH 6.8 combined with most probable number analyses (MPN) of surface-adherent cells demonstrate that electrostatic effects dominate microbial colonization on positively charged oxide surfaces regardless of mineral composition. In contrast, on negatively charged silicate minerals and glasses, the solid phase composition is a factor in determining the extent of microbial colonization, as well as the diversity of the attached community. In particular, silicates containing more than 1.2% Al exhibit less biomass than Al-poor silicates and MPN suggests a shift in community diversity, possibly indicating Al toxicity on these surfaces. When Fe is present in the silicate, however, this trend is reversed and abundant colonization of the surface is observed. Here, microorganisms preferentially colonize those silicate surfaces that offer beneficial nutrients and avoid those that contain potentially toxic elements.

In vitro biocompatibility of magnesium-incorporated submicro-porous titanium oxide surface produced by hydrothermal treatment

NASA Astrophysics Data System (ADS)

Park, Jin-Woo; Kim, Youn-Jeong; Jang, Je-Hee; An, Chang-Hyeon

2010-11-01

This study investigated the surface characteristics and in vitro biocompatibility of titanium (Ti) oxide surface incorporating magnesium ions (Mg), produced by hydrothermal treatment using an alkaline Mg-containing solution, for future biomedical applications. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and optical profilometry. Mouse calvaria-derived osteoblastic cell (MC3T3-E1) attachment, spreading, proliferation, alkaline phosphatase (ALP) activity, and osteoblastic gene expression on Mg-containing surfaces were compared with untreated Ti surfaces. Hydrothermal treatment resulted in Mg-incorporated Ti oxide layer with submicro-porous surface structures approximately 2 μm in thickness. ICP-AES analysis revealed Mg ions release from treated surfaces into the solution. The Mg-incorporated surface displayed significantly increased cellular attachment and ALP activity compared with untreated surface ( p < 0.05), and supported better cell spreading. Real-time polymerase chain reaction analysis showed notably higher mRNA expression of the osteoblast transcription factor genes (Dlx5, Runx2) and the osteoblast phenotype genes (ALP, bone sialoprotein and osteocalcin) in cells grown on the Mg-incorporated surfaces than untreated surfaces. These results demonstrate that the Mg-incorporated submicro-porous Ti oxide surface produced by hydrothermal treatment may improve implant osseointegration by enhancing the attachment, spreading and differentiation of osteoblastic cells.

Single and multijunction silicon based thin film solar cells on a flexible substrate with absorber layers made by hot-wire CVD

NASA Astrophysics Data System (ADS)

Li, Hongbo

2007-09-01

With the worldwide growing concern about reliable energy supply and the environmental problems of fossil and nuclear energy production, the need for clean and sustainable energy sources is evident. Solar energy conversion, such as in photovoltaic systems, can play a major role in the urgently needed energy transition in electricity production. Solar cells based on thin film silicon and its alloys are a promising candidate that is capable of fulfilling the fast increasing demand of a reliable solar cell supply. The conventional method to deposit silicon thin films is based on plasma enhanced chemical vapour deposition (PECVD) techniques, which have the disadvantage of increasing film inhomogeneity at a high deposition rate when scaling up for the industrial production. In this thesis, we study the possibility of making high efficiency single and multijunction thin film silicon solar cells with the so-called hot-wire CVD technique, in which no strong electromagnetic field is involved in the deposition. Therefore, the up-scaling for industrial production is straightforward. We report and discuss our findings on the correlation of substrate surface rms roughness and the main output parameter of a solar cell, the open circuit voltage Voc of c-Si:H n i p cells. By considering all the possible reasons that could influence the Voc of such cells, we conclude that the near linear correlation of Voc and substrate surface rms roughness is the result the two most probable reasons: the unintentional doping through the cracks originated near the valleys of the substrate surface due to the in-diffusion of impurities, and the high density electrical defects formed by the collision of columnar silicon structures. Both of them relate to the morphology of substrate surface. Therefore, to have the best cell performance on a rough substrate surface, a good control on the substrate surface morphology is necessary. Another issue influencing the performance of c-Si:H solar cells is the change in layer crystallinity during the growth of the c-Si:H i-layer. For PECVD deposited cells, it is often found that the layer crystallinity is enhanced with increasing film thickness. We found for Hot-wire deposited cells, however, the opposite development in material structure: the material becomes amorphous near the end of the deposition. This results in a deterioration of cell performance. We therefore introduce a so-called H2 reverse profiling technique, in which H2 is increased during the c-Si:H i-layer deposition. With this technique, a cell with an efficiency of 8.5% has been reached, which is in line with the best reported PECVD cells deposited on the same type of substrate. In the literature, carrier transport in c-Si:H cells has been a topic for debate. In this thesis, we present our finding of photogating effect on the spectral response of c-Si:H solar cells. When measured under coloured bias light, the apparent quantum efficiency value of a c-Si:H cell can be largely enhanced. This phenomenon is a typical result of trapping induced field modification in the bulk of a drift type solar cell. The discovery of this phenomenon has experimentally proved that field-driven transport to a large extend exist in a c-Si:H solar cell.

Room-Temperature Atomic Layer Deposition of Al2 O3 : Impact on Efficiency, Stability and Surface Properties in Perovskite Solar Cells.

PubMed

Kot, Malgorzata; Das, Chittaranjan; Wang, Zhiping; Henkel, Karsten; Rouissi, Zied; Wojciechowski, Konrad; Snaith, Henry J; Schmeisser, Dieter

2016-12-20

In this work, solar cells with a freshly made CH 3 NH 3 PbI 3 perovskite film showed a power conversion efficiency (PCE) of 15.4 % whereas the one with 50 days aged perovskite film only 6.1 %. However, when the aged perovskite was covered with a layer of Al 2 O 3 deposited by atomic layer deposition (ALD) at room temperature (RT), the PCE value was clearly enhanced. X-ray photoelectron spectroscopy study showed that the ALD precursors are chemically active only at the perovskite surface and passivate it. Moreover, the RT-ALD-Al 2 O 3 -covered perovskite films showed enhanced ambient air stability. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Revealing the cell-material interface with nanometer resolution by FIB-SEM

PubMed Central

Santoro, Francesca; Zhao, Wenting; Joubert, Lydia-Marie; Duan, Liting; Schnitker, Jan; van de Burgt, Yoeri; Lou, Hsin-Ya; Liu, Bofei; Salleo, Alberto; Cui, Lifeng; Cui, Yi; Cui, Bianxiao

2018-01-01

The interface between cells and non-biological surfaces regulates cell attachment, chronic tissue responses, and ultimately the success of medical implants or biosensors. Clinical and laboratory studies show that topological features of the surface profoundly influences cellular responses, e.g. titanium surfaces with nano- and microtopographical structures enhance osteoblast attachment and host-implant integration as compare to smooth surface. To understand how cells and tissues respond to different topographical features, it is of critical importance to directly visualize the cell-materials interface at the relevant nanometer length scale. Here, we present a new method for in situ examination of the cell-to-material interface at any desired location, based on focused-ion beam milling and scanning electron microscopy imaging (FIB-SEM) to resolve the cell membrane-to-material interface with 10 nm resolution. By examining how cell membranes interact with topographical features such as nanoscale protrusions or invaginations, we discovered that the cell membrane readily deforms inward and wraps around protruding structures, but hardly deforms outward to contour invaginating structures. This asymmetric membrane response (inward vs. outward deformation) causes the cleft width between the cell membrane and the nanostructure surface to vary for more than an order of magnitude. Our results suggest that surface topology is a crucial consideration for the development of medical implants or biosensors whose performances are strongly influenced by the cell-to-material interface. We anticipate that the method can be used to explore the direct interaction of cells/tissue with medical devices such as metal implants in the future. PMID:28682058

The establishment of Saccharomyces boulardii surface display system using a single expression vector.

PubMed

Wang, Tiantian; Sun, Hui; Zhang, Jie; Liu, Qing; Wang, Longjiang; Chen, Peipei; Wang, Fangkun; Li, Hongmei; Xiao, Yihong; Zhao, Xiaomin

2014-03-01

In the present study, an a-agglutinin-based Saccharomyces boulardii surface display system was successfully established using a single expression vector. Based on the two protein co-expression vector pSP-G1 built by Partow et al., a S. boulardii surface display vector-pSDSb containing all the display elements was constructed. The display results of heterologous proteins were confirmed by successfully displaying enhanced green fluorescent protein (EGFP) and chicken Eimeria tenella Microneme-2 proteins (EtMic2) on the S. boulardii cell surface. The DNA sequence of AGA1 gene from S. boulardii (SbAGA1) was determined and used as the cell wall anchor partner. This is the first time heterologous proteins have been displayed on the cell surface of S. boulardii. Because S. boulardii is probiotic and eukaryotic, its surface display system would be very valuable, particularly in the development of a live vaccine against various pathogenic organisms especially eukaryotic pathogens such as protistan parasites. Copyright © 2013 Elsevier Inc. All rights reserved.

Enhanced photovoltaic performance of Sb2S3-sensitized solar cells through surface treatments

NASA Astrophysics Data System (ADS)

Ye, Qing; Xu, Yafeng; Chen, Wenyong; Yang, Shangfeng; Zhu, Jun; Weng, Jian

2018-05-01

Efficient antimony sulfide (Sb2S3)-sensitized solar cells were obtained by a sequential treatment with thioacetamide (TA) and 1-decylphosphonic acid (DPA). Compared with the untreated Sb2S3-sensitized solar cells, the power conversion efficiency of the treated Sb2S3 solar cells was improved by 1.80% to 3.23%. The TA treatment improved the Sb2S3 films by reducing impurities and decreasing the film's surface defects, which inhibited the emergence of recombination centers. The DPA treatment reduced the recombination between hole transport materials (HTMs) and the Sb2S3. Therefore, we have presented an efficient strategy to improve the performance of Sb2S3-sensitized solar cells.

Addressing of LnCaP Cell Using Magnetic Particles Assisted Impedimetric Microelectrode.

PubMed

Nguyen, Dung Thi Xuan; Tran, Trong Binh; Nguyen, Phuong-Diem; Min, Junhong

2016-03-01

In this study, we provide a facile, effective technique for a simple isolation and enrichment of low metastatic prostate tumor cell LNCaP using biocompatible, magnetic particles asissted impedimetric sensing system. Hydrophobic cell membrane anchors (BAM) were generated onto magnetic particles which diameters vary from 50 nm to 5 μm and were used to capture LNCaP cells from the suspension. Finally, magnetic particle-LNCaP complex were addressed onto the surface of the interdigitated microelectrode (IDM). Cell viability was monitored by our laboratory developed-technique Electrical Cell Substrate Impedance Sensing (ECIS). The results reavealed that 50 nm-magnetic particles showed best performance in terms of cell separation and cell viability. This technique provides a simple and efficient method for the direct addressing of LNCaP cell on the surface and enhances better understanding of cell behavior for cancer management in the near future.

Synergistic influence of polyoxometalate surface corona towards enhancing the antibacterial performance of tyrosine-capped Ag nanoparticles

NASA Astrophysics Data System (ADS)

Daima, Hemant K.; Selvakannan, P. R.; Kandjani, Ahmad E.; Shukla, Ravi; Bhargava, Suresh K.; Bansal, Vipul

2013-12-01

We illustrate a new strategy to improve the antibacterial potential of silver nanoparticles (AgNPs) by their surface modification with the surface corona of biologically active polyoxometalates (POMs). The stable POM surface corona was achieved by utilising zwitterionic tyrosine amino acid as a pH-switchable reducing and capping agent of AgNPs. The general applicability of this approach was demonstrated by developing surface coronas of phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) around AgNPs. Our investigations on Gram negative bacterium Escherichia coli demonstrate that in conjugation with AgNPs, the surface corona of POMs enhances the physical damage to the bacterial cells due to synergistic antibacterial action of AgNPs and POMs, and the ability of tyrosine-reduced AgNPs (AgNPsY) to act as an excellent carrier and stabiliser for the POMs. The further extension of this study towards Gram positive bacterium Staphylococcus albus showed a similar toxicity pattern, whereas these nanomaterials were found to be biocompatible for PC3 epithelial mammalian cells, suggesting the potential of these materials towards specific antimicrobial targeting for topical wound healing applications. The outcomes of this work show that facile tailorability of nanostructured surfaces may play a considerable role in controlling the biological activities of different nanomaterials.We illustrate a new strategy to improve the antibacterial potential of silver nanoparticles (AgNPs) by their surface modification with the surface corona of biologically active polyoxometalates (POMs). The stable POM surface corona was achieved by utilising zwitterionic tyrosine amino acid as a pH-switchable reducing and capping agent of AgNPs. The general applicability of this approach was demonstrated by developing surface coronas of phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) around AgNPs. Our investigations on Gram negative bacterium Escherichia coli demonstrate that in conjugation with AgNPs, the surface corona of POMs enhances the physical damage to the bacterial cells due to synergistic antibacterial action of AgNPs and POMs, and the ability of tyrosine-reduced AgNPs (AgNPsY) to act as an excellent carrier and stabiliser for the POMs. The further extension of this study towards Gram positive bacterium Staphylococcus albus showed a similar toxicity pattern, whereas these nanomaterials were found to be biocompatible for PC3 epithelial mammalian cells, suggesting the potential of these materials towards specific antimicrobial targeting for topical wound healing applications. The outcomes of this work show that facile tailorability of nanostructured surfaces may play a considerable role in controlling the biological activities of different nanomaterials. Electronic supplementary information (ESI) available: XRD analysis (Fig. S1); cytotoxicity profile (Fig. S2) and optical images of human PC3 cells (Fig. S3) treated with nanomaterials; FTIR vibrational modes arising from different materials (Table S1); and relative concentrations of Ag and POMs present in modified AgNPs used for biological studies (Table S2). See DOI: 10.1039/c3nr03806h

Mechanism of Surface-Enhanced Raman Scattering Based on 3D Graphene-TiO2 Nanocomposites and Application to Real-Time Monitoring of Telomerase Activity in Differentiation of Stem Cells.

PubMed

Zheng, Tingting; Feng, Enduo; Wang, Zhiqiang; Gong, Xueqing; Tian, Yang

2017-10-25

With a burst development of new nanomaterials for plasmon-free surface-enhanced Raman scattering (SERS), the understanding of chemical mechanism (CM) and further applications have become more and more attractive. Herein, a novel SERS platform was specially designed through electrochemical deposition of graphene onto TiO 2 nanoarrays (EG-TiO 2 ). The developed EG-TiO 2 nanocomposite SERS platform possessed remarkable Raman activity using copper phthalocyanine (CuPc) as a probe molecule. X-ray photoelectron spectroscopy measurement revealed that the chemical bond Ti-O-C was formed at the interface between graphene and TiO 2 in EG-TiO 2 nanocomposites. Both experimental and theoretical results demonstrated that the obvious Raman enhancement was attributed to TiO 2 -induced Fermi level shift of graphene, resulting in effective charge transfer between EG-TiO 2 nanocomposites and molecules. Taking advantage of a marked Raman response of the CuPc molecule on the EG-TiO 2 nanocomposite surface as well as specific recognition of CuPc toward multiple telomeric G-quadruplex, EG-TiO 2 nanocomposites were tactfully employed as the SERS substrate for selective and ultrasensitive determination of telomerase activity, with a low detection limit down to 2.07 × 10 -16 IU. Interestingly, the self-cleaning characteristic of EG-TiO 2 nanocomposites under visible light irradiation successfully provided a recycling ability for this plasmon-free EG-TiO 2 substrate. The present SERS biosensor with high analytical performance, such as high selectivity and sensitivity, has been further explored to determine telomerase activity in stem cells as well as to count the cell numbers. More importantly, using this useful tool, it was discovered that telomerase activity plays an important role in the proliferation and differentiation from human mesenchymal stem cells to neural stem cells. This work has not only established an approach for gaining fundamental insights into the chemical mechanism (CM) of Raman enhancement but also has opened a new way in the investigation of long-term dynamics of stem cell differentiation and clinical drug screening.

Fortifying the Bone-Implant Interface Part 1: An In Vitro Evaluation of 3D-Printed and TPS Porous Surfaces

PubMed Central

Lindsey, Derek P.; Bahney, Chelsea S.; Woods, Shane A.; Wolfe, Mark L.; Yerby, Scott A.

2017-01-01

Background An aging society and concomitant rise in the incidence of impaired bone health have led to the need for advanced osteoconductive spinal implant surfaces that promote greater biological fixation (e.g. for interbody fusion cages, sacroiliac joint fusion implants, and artificial disc replacements). Additive manufacturing, i.e. 3D-printing, may improve bone integration by generating biomimetic spinal implant surfaces that mimic bone morphology. Such surfaces may foster an enhanced cellular response compared to traditional implant surfacing processes. Methods This study investigated the response of human osteoblasts to additive manufactured (AM) trabecular-like titanium implant surfaces compared to traditionally machined base material with titanium plasma spray (TPS) coated surfaces, with and without a nanocrystalline hydroxyapatite (HA) coating. For TPS-coated discs, wrought Ti6Al4V ELI was machined and TPS-coating was applied. For AM discs, Ti6Al4V ELI powder was 3D-printed to form a solid base and trabecular-like porous surface. The HA-coating was applied via a precipitation dip-spin method. Surface porosity, pore size, thickness, and hydrophilicity were characterized. Initial cell attachment, proliferation, alkaline phosphatase (ALP) activity, and calcium production of hFOB cells (n=5 per group) were measured. Results Cells on AM discs exhibited expedited proliferative activity. While there were no differences in mean ALP expression and calcium production between TPS and AM discs, calcium production on the AM discs trended 48% higher than on TPS discs (p=0.07). Overall, HA-coating did not further enhance results compared to uncoated TPS and AM discs. Conclusions Results demonstrate that additive manufacturing allows for controlled trabecular-like surfaces that promote earlier cell proliferation and trends toward higher calcium production than TPS coating. Results further showed that nanocrystalline HA may not provide an advantage on porous titanium surfaces. Clinical Relevance Additive manufactured porous titanium surfaces may induce a more osteogenic environment compared to traditional TPS, and thus present as an attractive alternative to TPS-coating for orthopedic spinal implants. PMID:28765799

Surface multiheme c-type cytochromes from Thermincola potens: Implications for dissimilatory metal reduction by Gram-positive bacteria

NASA Astrophysics Data System (ADS)

Carlson, H. K.; Iavarone, A. T.; Gorur, A.; Yeo, B. S.; Tran, R.; Melnyk, R. A.; Mathies, R. A.; Auer, M.; Coates, J. D.

2011-12-01

Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they have been shown to be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or the humic substances analog, anthraquinone-2,6-disulfonate (AQDS). The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS and that several MHCs are localized to the cell wall or cell surface of T. potens. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results are the first direct evidence for cell-wall associated cytochromes and MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium.

Enhancing wear resistance of working bodies of grinder through lining crushed material

NASA Astrophysics Data System (ADS)

Romanovich, A. A.; Annenko, D. M.; Romanovich, M. A.; Apukhtina, I. V.

2018-03-01

The article presents the analysis of directions of increasing wear resistance of working surfaces of rolls. A technical solution developed at the level of the invention is proposed, which is simple to implement in production conditions and which makes it possible to protect the roll surface from heavy wear due to surfacing of wear-resistant mesh material, cells of which are filling with grinding material in the process of work. Retaining them enables one to protect the roll surface from wear. The paper dwells on conditions of pressing materials in cells of eccentric rolls on the working surface with a grid of rectangular shape. The paper presents an equation for calculation of the cell dimension that provides the lining of the working surface by a mill material with respect to its properties. The article presents results of comparative studies on the grinding process of a press roller grinder (PRG) between rolls with and without a fusion-bonded mesh. It is clarified that the lining of rolls working surface slightly reduces the quality of the grinding, since the material thickness in the cell is small and has a finely divided and compacted structure with high strength.

Final technical report for project titled Quantitative Characterization of Cell Aggregation/Adhesion as Predictor for Distribution and Transport of Microorganisms in Subsurface Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, April Z.; Wan, Kai-tak

This project aims to explore and develop enabling methodology and techniques for nano-scale characterization of microbe cell surface contact mechanics, interactions and adhesion quantities that allow for identification and quantification of indicative properties related to microorganism migration and transport behavior in porous media and in subsurface environments. Microbe transport has wide impact and therefore is of great interest in various environmental applications such as in situ or enhanced subsurface bioremediation,filtration processes for water and wastewater treatments and protection of drinking water supplies. Although great progress has been made towards understanding the identities and activities of these microorganisms in the subsurface,more » to date, little is known of the mechanisms that govern the mobility and transport of microorganisms in DOE’s contaminated sites, making the outcomes of in situ natural attenuation or contaminant stability enhancement unpredictable. Conventionally, movement of microorganisms was believed to follows the rules governing solute (particle) transport. However, recent studies revealed that cell surface properties, especially those pertaining to cell attachment/adhesion and aggregation behavior, can cause the microbe behavior to deviate from non-viable particles and hence greatly influence the mobility and distribution of microorganisms in porous media.This complexity highlights the need to obtain detailed information of cell-cell and cell-surface interactions in order to improve and refine the conceptual and quantitative model development for fate and transport of microorganisms and contaminant in subsurface. Traditional cell surface characterization methods are not sufficient to fully predict the deposition rates and transport behaviors of microorganism observed. A breakthrough of methodology that would allow for quantitative and molecular-level description of intrinsic cell surface properties indicative for cell-surface interactions is essential for the field. To tackle this, we have developed a number of new Bio-nanomechanical techniques, including reflection interference contrast microscopy (RICM) and bio-AFM (Atomic Force Microscopy), for cell adhesion-detachment measurement of the long-range surface interactions, in combination with mathematical modeling, which would allow us to characterize the mechanical behavior from single cell to multi-cell aggregate, critical thresholds for large scale coaggregation and transportation of cells and aggregates in the presence of long range inter-surface forces etc. Although some technical and mathematical challenges remain, the preliminary results promise great breakthrough potential. In this study, we investigated the cellular surface characteristics of representative bio-remediating microorganisms relevant to DOE IFRC (Integrated Field-Scale Subsurface Research Challenges) sites and their transport behaviors in porous media, aiming to draw a groundbreaking correlation between the micro-scale genetic and biological origin-based cell surface properties, the consequent mechanical adhesion and aggregation behaviors, and the macro-scale microbial mobility and retention in porous media, which are unavailable in the literature. The long-term goal is to significantly improve the mechanistic and quantitative understanding of microbial mobility, sorption, and transport within reactive transport models as needed to manipulate subsurface contaminant fate and transport predictions.« less

Regeneration of Corneal Epithelium With Dental Pulp Stem Cells Using a Contact Lens Delivery System.

PubMed

Kushnerev, Evgeny; Shawcross, Susan G; Sothirachagan, Shankari; Carley, Fiona; Brahma, Arun; Yates, Julian M; Hillarby, M Chantal

2016-10-01

The corneal epithelium is sloughed off surface of the eye by the action of blinking and is continually replaced by division and maturation of the limbal stem cells (LSCs). In the case of injury or disease, LSCs can be lost or damaged to a point at which the corneal epithelial layer is no longer maintained. leading to LSC deficiencies (LSCDs). When this occurs, the opaque conjunctiva overgrows the anterior surface of the eye, leading to vision impairment or loss. Dental pulp stem cells (DPSCs) are promising candidates as autologous LSC substitutes. In this study, contact lenses (CLs) are used as a novel medical device to deliver DPSCs onto corneal surface to enhance corneal epithelium regeneration. Dental pulp stem cells labeled with green fluorescent Qtracker 525 were seeded onto the pretreated CLs, allowed to adhere, then delivered to debrided human corneas. Expression of KRT3, 12, 13, and 19 was investigated by immunostaining, then standard and confocal microscopy. Dental pulp stem cells were successfully isolated, labeled, and delivered to the corneal surface using CLs. Following removal of CLs, confocal microscopy showed that the DPSCs had migrated onto the cornea. Coexpression of KRT12 and green fluorescent Qtracker 525 confirmed that the DPSCs had transdifferentiated into corneal epithelial progenitors. Delimitation of KRT 19 and green fluorescence provides evidence that Qtracker 525-labeled DPSCs establish a barrier to the invasion of the cornea by conjunctiva. In this study we show that DPSCs, delivered using CLs, can be used to enhance repair and regeneration of the human corneal epithelium.

Method for producing textured substrates for thin-film photovoltaic cells

DOEpatents

Lauf, R.J.

1996-04-02

The invention pertains to the production of ceramic substrates used in the manufacture of thin-film photovoltaic cells used for directly converting solar energy to electrical energy. Elongated ribbon-like sheets of substrate precursor containing a mixture of ceramic particulates, a binder, and a plasticizer are formed and then while green provided with a mechanically textured surface region used for supporting the thin film semiconductor of the photovoltaic cell when the sheets of the substrate precursor are subsequently cut into substrate-sized shapes and then sintered. The textured surface pattern on the substrate provides enhanced light trapping and collection for substantially increasing the, solar energy conversion efficiency of thin-film photovoltaic cells. 4 figs.

Method for producing textured substrates for thin-film photovoltaic cells

DOEpatents

Lauf, R.J.

1994-04-26

The invention pertains to the production of ceramic substrates used in the manufacture of thin-film photovoltaic cells used for directly converting solar energy to electrical energy. Elongated ribbon-like sheets of substrate precursor containing a mixture of ceramic particulates, a binder, and a plasticizer are formed and then while green provided with a mechanically textured surface region used for supporting the thin film semiconductor of the photovoltaic cell when the sheets of the substrate precursor are subsequently cut into substrate-sized shapes and then sintered. The textured surface pattern on the substrate provides enhanced light trapping and collection for substantially increasing the solar energy conversion efficiency of thin-film photovoltaic cells. 4 figures.

Method for producing textured substrates for thin-film photovoltaic cells

DOEpatents

Lauf, Robert J.

1994-01-01

The invention pertains to the production of ceramic substrates used in the manufacture of thin-film photovoltaic cells used for directly converting solar energy to electrical energy. Elongated ribbon-like sheets of substrate precursor containing a mixture of ceramic particulates, a binder, and a plasticizer are formed and then while green provided with a mechanically textured surface region used for supporting the thin film semiconductor of the photovoltaic cell when the sheets of the substrate precursor are subsequently cut into substrate-sized shapes and then sintered. The textured surface pattern on the substrate provides enhanced light trapping and collection for substantially increasing the solar energy conversion efficiency of thin-film photovoltaic cells.

Method for producing textured substrates for thin-film photovoltaic cells

DOEpatents

Lauf, Robert J.

1996-01-01

The invention pertains to the production of ceramic substrates used in the manufacture of thin-film photovoltaic cells used for directly converting solar energy to electrical energy. Elongated ribbon-like sheets of substrate precursor containing a mixture of ceramic particulates, a binder, and a plasticizer are formed and then while green provided with a mechanically textured surface region used for supporting the thin film semiconductor of the photovoltaic cell when the sheets of the substrate precursor are subsequently cut into substrate-sized shapes and then sintered. The textured surface pattern on the substrate provides enhanced light trapping and collection for substantially increasing the, solar energy conversion efficiency of thin-film photovoltaic cells.

Direct association of thioredoxin-1 (TRX) with macrophage migration inhibitory factor (MIF): regulatory role of TRX on MIF internalization and signaling.

PubMed

Son, Aoi; Kato, Noriko; Horibe, Tomohisa; Matsuo, Yoshiyuki; Mochizuki, Michika; Mitsui, Akira; Kawakami, Koji; Nakamura, Hajime; Yodoi, Junji

2009-10-01

Thioredoxin-1 (TRX) is a small (14 kDa) multifunctional protein with the redox-active site Cys-Gly-Pro-Cys. Macrophage migration inhibitory factor (MIF) is a 12 kDa cytokine belonging to the TRX family. Historically, when we purified TRX from the supernatant of ATL-2 cells, a 12 kDa protein was identified along with TRX, which was later proved to be MIF. Here, we show that TRX and MIF form a complex in the cell and the culture supernatant of ATL-2 cells. Using a BIAcore assay, we confirmed that TRX has a specific affinity with MIF. We also found that extracellular MIF was more effectively internalized into the ATL-2 cells expressing TRX on the cell surface, than the Jurkat T cells which do not express surface TRX. Moreover, anti-TRX antibody blocked the MIF internalization, suggesting that the cell surface TRX is involved in MIF internalization into the cells. Furthermore, anti-TRX antibody inhibited MIF-mediated enhancement of TNF-alpha production from macrophage RAW264.7 cells. These results suggest that the cell surface TRX serves as one of the MIF binding molecules or MIF receptor component and inhibits MIF-mediated inflammatory signals.

Inhibition of cell surface mediated plasminogen activation by a monoclonal antibody against alpha-Enolase.

PubMed

López-Alemany, Roser; Longstaff, Colin; Hawley, Stephen; Mirshahi, Massoud; Fábregas, Pere; Jardí, Merce; Merton, Elizabeth; Miles, Lindsey A; Félez, Jordi

2003-04-01

Localization of plasmin activity on leukocyte surfaces plays a critical role in fibrinolysis as well as in pathological and physiological processes in which cells must degrade the extracellular matrix in order to migrate. The binding of plasminogen to leukocytic cell lines induces a 30- to 80-fold increase in the rate of plasminogen activation by tissue-type (tPA) and urokinase-type (uPA) plasminogen activators. In the present study we have examined the role of alpha-enolase in plasminogen activation on the cell surface. We produced and characterized a monoclonal antibody (MAb) 11G1 against purified alpha-enolase, which abrogated about 90% of cell-dependent plasminogen activation by either uPA or tPA on leukocytoid cell lines of different lineages: B-lymphocytic, T-lymphocytic, granulocytic, and monocytic cells. In addition, MAb 11G1 also blocked enhancement of plasmin formation by peripheral blood neutrophils and monocytes. In contrast, MAb 11G1 did not affect plasmin generation in the presence of fibrin, indicating that this antibody did not interact with fibrinolytic components in the absence of cells. These data suggest that, although leukocytic cells display several molecules that bind plasminogen, alpha-enolase is responsible for the majority of the promotion of plasminogen activation on the surfaces of leukocytic cells. Copyright 2003 Wiley-Liss, Inc.

Trade-offs of the opto-electrical properties of a-Si:H solar cells based on MOCVD BZO films.

PubMed

Chen, Ze; Zhang, Xiao-dan; Liang, Jun-hui; Fang, Jia; Liang, Xue-jiao; Sun, Jian; Zhang, De-kun; Chen, Xin-liang; Huang, Qian; Zhao, Ying

2015-01-07

Boron-doped zinc oxide (BZO) films, deposited by metal-organic chemical vapor deposition (MOCVD), have been widely used as front electrodes in thin-film solar cells due to their native pyramidal surface structure, which results in efficient light trapping. This light trapping effect can enhance the short-circuit current density (Jsc) of solar cells. However, nanocracks or voids in the silicon active layer may form when the surface morphology of the BZO is too sharp; this usually leads to degraded electrical properties of the cells, such as open-circuit voltage (Voc) and the fill factor (FF), which in turn decreases efficiency (Eff) [Bailat et al., Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on. IEEE, 2006, vol. 2, pp. 1533-1536]. In this paper, an etching and coating method was proposed to modify the sharp "pyramids" on the surface of the BZO films. As a result, an evident enhancement was achieved for these modified, BZO-based cells' Voc, FF, and Eff, although the Jsc exhibited a small decrease. In order to increase the Jsc and maintain the improved electrical properties (Voc, FF) of the cell, a thin BZO coating, deposited by MOCVD, was introduced to coat the sputtering-treated BZO film. Finally, we optimized the trade-off among the Voc, FF, and Jsc, that is, we identified a regime with an increase of the Jsc as well as a further improvement of the other electrical properties.

Large-scale expansion of Wharton's jelly-derived mesenchymal stem cells on gelatin microbeads, with retention of self-renewal and multipotency characteristics and the capacity for enhancing skin wound healing.

PubMed

Zhao, Guifang; Liu, Feilin; Lan, Shaowei; Li, Pengdong; Wang, Li; Kou, Junna; Qi, Xiaojuan; Fan, Ruirui; Hao, Deshun; Wu, Chunling; Bai, Tingting; Li, Yulin; Liu, Jin Yu

2015-03-19

Successful stem cell therapy relies on large-scale generation of stem cells and their maintenance in a proliferative multipotent state. This study aimed to establish a three-dimension culture system for large-scale generation of hWJ-MSC and investigated the self-renewal activity, genomic stability and multi-lineage differentiation potential of such hWJ-MSC in enhancing skin wound healing. hWJ-MSC were seeded on gelatin microbeads and cultured in spinning bottles (3D). Cell proliferation, karyotype analysis, surface marker expression, multipotent differentiation (adipogenic, chondrogenic, and osteogenic potentials), and expression of core transcription factors (OCT4, SOX2, NANOG, and C-MYC), as well as their efficacy in accelerating skin wound healing, were investigated and compared with those of hWJ-MSC derived from plate cultres (2D), using in vivo and in vitro experiments. hWJ-MSC attached to and proliferated on gelatin microbeads in 3D cultures reaching a maximum of 1.1-1.30×10(7) cells on 0.5 g of microbeads by days 8-14; in contrast, hWJ-MSC derived from 2D cultures reached a maximum of 6.5 -11.5×10(5) cells per well in a 24-well plate by days 6-10. hWJ-MSC derived by 3D culture incorporated significantly more EdU (P<0.05) and had a significantly higher proliferation index (P<0.05) than those derived from 2D culture. Immunofluorescence staining, real-time PCR, flow cytometry analysis, and multipotency assays showed that hWJ-MSC derived from 3D culture retained MSC surface markers and multipotency potential similar to 2D culture-derived cells. 3D culture-derived hWJ-MSC also retained the expression of core transcription factors at levels comparable to their 2D culture counterparts. Direct injection of hWJ-MSC derived from 3D or 2D cultures into animals exhibited similar efficacy in enhancing skin wound healing. Thus, hWJ-MSC can be expanded markedly in gelatin microbeads, while retaining MSC surface marker expression, multipotent differential potential, and expression of core transcription factors. These cells also efficiently enhanced skin wound healing in vivo, in a manner comparable to that of hWJ-MSC obtained from 2D culture.

Tracking the intracellular drug release from graphene oxide using surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Huang, Jie; Zong, Cheng; Shen, He; Cao, Yuhua; Ren, Bin; Zhang, Zhijun

2013-10-01

We have developed a graphene oxide (GO)-based nanoplatform simultaneously loaded with a chemical drug and Ag nanoparticles (NPs), and employed it to study the drug release from GO in living cells by surface-enhanced Raman spectroscopy (SERS). In our strategy, doxorubicin (DOX), a typical model anticancer drug, was loaded onto chemically prepared GO by means of π-π stacking, while the Ag NPs were covalently modified onto GO. After incubation of the DOX- and Ag NPs-loaded GO with Ca Ski cells for several hours, DOX will detach from the GO in an acidic environment due to the pH-dependent π-π interaction between DOX and GO. Real-time measurement of SERS signals of DOX using the GO loaded with Ag NPs as a SERS-active substrate allows us to monitor the process of the drug release inside the living cell. The SERS results reveal that DOX is initially released from the GO surface inside the lysosomes, then escapes into the cytoplasm, and finally enters the nucleus, while GO, the nanocarrier, remains within the cytoplasm, without entering the nucleus.We have developed a graphene oxide (GO)-based nanoplatform simultaneously loaded with a chemical drug and Ag nanoparticles (NPs), and employed it to study the drug release from GO in living cells by surface-enhanced Raman spectroscopy (SERS). In our strategy, doxorubicin (DOX), a typical model anticancer drug, was loaded onto chemically prepared GO by means of π-π stacking, while the Ag NPs were covalently modified onto GO. After incubation of the DOX- and Ag NPs-loaded GO with Ca Ski cells for several hours, DOX will detach from the GO in an acidic environment due to the pH-dependent π-π interaction between DOX and GO. Real-time measurement of SERS signals of DOX using the GO loaded with Ag NPs as a SERS-active substrate allows us to monitor the process of the drug release inside the living cell. The SERS results reveal that DOX is initially released from the GO surface inside the lysosomes, then escapes into the cytoplasm, and finally enters the nucleus, while GO, the nanocarrier, remains within the cytoplasm, without entering the nucleus. Electronic supplementary information (ESI) available: Cytotoxicity of Ag-GO SERS image after the cell incubated with Ag-GO for 2 h fluorescence images of Ca Ski cells. See DOI: 10.1039/c3nr03264g

Bio-sensing with butterfly wings: naturally occurring nano-structures for SERS-based malaria parasite detection.

PubMed

Garrett, Natalie L; Sekine, Ryo; Dixon, Matthew W A; Tilley, Leann; Bambery, Keith R; Wood, Bayden R

2015-09-07

Surface enhanced Raman scattering (SERS) is a powerful tool with great potential to provide improved bio-sensing capabilities. The current 'gold-standard' method for diagnosis of malaria involves visual inspection of blood smears using light microscopy, which is time consuming and can prevent early diagnosis of the disease. We present a novel surface-enhanced Raman spectroscopy substrate based on gold-coated butterfly wings, which enabled detection of malarial hemozoin pigment within lysed blood samples containing 0.005% and 0.0005% infected red blood cells.

Surface enhanced Raman scattering of biospecies on anodized aluminum oxide films

NASA Astrophysics Data System (ADS)

Zhang, C.; Smirnov, A. I.; Hahn, D.; Grebel, H.

2007-06-01

Traditionally, aluminum and anodized aluminum oxide films (AAO) are not the platforms of choice for surface-enhanced raman scattering (SERS) experiments despite of the aluminum's large negative permittivity value. Here we examine the usefulness of aluminum and nanoporous alumina platforms for detecting soft biospecies ranging from bacterial spores to protein markers. We used these flat platforms to examine SERS of a model protein (cytochrome c from bovine heart tissue) and bacterial cells (spores of Bacillus subtilis ATCC13933 used as Anthrax simulant) and demonstrated clear Raman amplification.

Effects of a hybrid micro/nanorod topography-modified titanium implant on adhesion and osteogenic differentiation in rat bone marrow mesenchymal stem cells.

PubMed

Zhang, Wenjie; Li, Zihui; Huang, Qingfeng; Xu, Ling; Li, Jinhua; Jin, Yuqin; Wang, Guifang; Liu, Xuanyong; Jiang, Xinquan

2013-01-01

Various methods have been used to modify titanium implant surfaces with the aim of achieving better osseointegration. In this study, we fabricated a clustered nanorod structure on an acid-etched, microstructured titanium plate surface using hydrogen peroxide. We also evaluated biofunctionalization of the hybrid micro/nanorod topography on rat bone marrow mesenchymal stem cells. Scanning electron microscopy and x-ray diffraction were used to investigate the surface topography and phase composition of the modified titanium plate. Rat bone marrow mesenchymal stem cells were cultured and seeded on the plate. The adhesion ability of the cells was then assayed by cell counting at one, 4, and 24 hours after cell seeding, and expression of adhesion-related protein integrin β1 was detected by immunofluorescence. In addition, a polymerase chain reaction assay, alkaline phosphatase and Alizarin Red S staining assays, and osteopontin and osteocalcin immunofluorescence analyses were used to evaluate the osteogenic differentiation behavior of the cells. The hybrid micro/nanoscale texture formed on the titanium surface enhanced the initial adhesion activity of the rat bone marrow mesenchymal stem cells. Importantly, the hierarchical structure promoted osteogenic differentiation of these cells. This study suggests that a hybrid micro/nanorod topography on a titanium surface fabricated by treatment with hydrogen peroxide followed by acid etching might facilitate osseointegration of a titanium implant in vivo.

Immobilisation of a thrombopoietin peptidic mimic by self-assembled monolayers for culture of CD34+ cells.

PubMed

Lee, Eun-Ju; Be, Cheang Ly; Vinson, Andrew R; Riches, Andrew G; Fehr, Friederike; Gardiner, James; Gengenbach, Thomas R; Winkler, David A; Haylock, David

2015-01-01

Compared to soluble cytokines, surface-tethered ligands can deliver biological signalling with precise control of spatial positioning and concentration. A strategy that immobilises ligand molecules on a surface in a uniform orientation using non-cleavable linkages under physiological conditions would enhance the specific and systemic delivery of signalling in the local environment. We used mixed self-assembled monolayers (SAMs) of oxyamine- and oligo(ethylene glycol)-terminated thiols on gold to covalently install aldehyde- or ketone-functionalised ligands via oxime conjugation. Characterisation by electrochemistry and X-ray photoelectron spectroscopy showed quantitative immobilisation of the ligands on SAM surfaces. The thrombopoietin mimetic peptide, RILL, was immobilised on SAMs and the bioactivity of the substrate was demonstrated by culturing factor-dependent cells. We also optimised the immobilisation and wash conditions so that the peptide was not released into the culture medium and the immobilised RILL could be re-used for consecutive cell cultures. The surface also supported the growth of haematopoietic CD34+ cells comparable to the standard thrombopoietin-supplemented culture. Furthermore, the RILL-immobilised SAM surface was as effective in expanding uncommitted CD34+ cells as standard culture. The stimulatory effect of surface-tethered ligands in haematopoietic stem cell expansion supports the use of ligand immobilisation strategies to replicate the haematopoietic stem cell niche. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Soluble fragments of e-cadherin cell-adhesion molecule increase in urinary-excretion of cancer-patients, potentially indicating its shedding from epithelial tumor-cells.

PubMed

Katayama, M; Hirai, S; Yasumoto, M; Nishikawa, K; Nagata, S; Otsuka, M; Kamihagi, K; Kato, I

1994-11-01

E-cadherin (Ecad) is well known to be a calcium-ion-dependent cell-cell adhesion molecule expressed mostly in epithelial tissues. Previous immunohistochemical studies suggested that this cell adhesion molecule acts as an invasion suppressor and is negligibly detected in cancer metastatic regions. Soluble Ecad fragments derived from the proteolysed membrane-associated form were detected in culture supernatants of two cell lines, COLO 205 and A-431, with normal distribution of cell surface Ecad. Soluble Ecad levels released into culture of COLO 205 exhibiting reduced cell-cell adhesion were apparently elevated above those of A-431 with tight cell-cell adhesion. Furthermore, human circulation and urine continuously contain soluble Ecad which consists mainly of homogeneous 75-85 kDa extracellular domains. Soluble Ecad urinary level per urinary creatinine level was found to be significantly elevated in 53% of patients suffering from various types of cancers including lung, liver, stomach, colon and rectal cancers, as compared with those in the age-matched healthy subjects. These results suggest that dysfunction of cell surface Ecad is responsible for its enhanced proteolytic shedding in tumorigenesis, which may lead to the decrease of cell surface Ecads. Furthermore, excretion of high levels of soluble Ecad fragments potentially indicates the progression of epithelial tumors excessively degrading cell surface Ecad in clinical subjects.

Immobilization of cross linked Col-I-OPN bone matrix protein on aminolysed PCL surfaces enhances initial biocompatibility of human adipogenic mesenchymal stem cells (hADMSC)

NASA Astrophysics Data System (ADS)

Kim, Young-Hee; Jyoti, Md. Anirban; Song, Ho-Yeon

2014-06-01

In bone tissue engineering surface modification is considered as one of the important ways of fabricating successful biocompatible material. Addition of biologically active functionality on the surfaces has been tried for improving the overall biocompatibility of the system. In this study poly-ɛ-caprolactone film surfaces have been modified through aminolysis and immobilization process. Collagen type I (COL-I) and osteopontin (OPN), which play an important role in osteogenesis, was immobilized onto PCL films followed by aminolysis treatment using 1,6-hexanediamine. Characterization of animolysed and immobilized surfaces were done by a number techniques using scanning electron microscopy (SEM), FT-IR, XPS, ninhydrin staining, SDS-PAGE and confocal microscopy and compared between the modified and un-modified surfaces. Results of the successive experiments showed that aminolysis treatment was homogeneously achieved which helped to entrap or immobilize Col-I-OPN proteins on surfaces of PCL film. In vitro studies with human adipogenic mesenchymal stem cells (hADMSC) also confirmed the attachment and proliferation of cells was better in modified PCL surfaces than the unmodified surfaces. SEM, confocal microscopy and MTT assay showed a significant increase in cell spreading, attachment and proliferations on the biofunctionalized surfaces compared to the unmodified PCL surfaces at all-time points indicating the success of surface biofunctionalization.

A Rhizavidin Monomer with Nearly Multimeric Avidin-Like Binding Stability Against Biotin Conjugates.

PubMed

Lee, Jeong Min; Kim, Jung A; Yen, Tzu-Chi; Lee, In Hwan; Ahn, Byungjun; Lee, Younghoon; Hsieh, Chia-Lung; Kim, Ho Min; Jung, Yongwon

2016-03-01

Developing a monomeric form of an avidin-like protein with highly stable biotin binding properties has been a major challenge in biotin-avidin linking technology. Here we report a monomeric avidin-like protein-enhanced monoavidin-with off-rates almost comparable to those of multimeric avidin proteins against various biotin conjugates. Enhanced monoavidin (eMA) was developed from naturally dimeric rhizavidin by optimally maintaining protein rigidity during monomerization and additionally shielding the bound biotin by diverse engineering of the surface residues. eMA allowed the monovalent and nonperturbing labeling of head-group-biotinylated lipids in bilayer membranes. In addition, we fabricated an unprecedented 24-meric avidin probe by fusing eMA to a multimeric cage protein. The 24-meric avidin and eMA were utilized to demonstrate how artificial clustering of cell-surface proteins greatly enhances the internalization rates of assembled proteins on live cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inverse Optimization of Plasmonic and Antireflective Grating in Thin Film PV Cells

NASA Astrophysics Data System (ADS)

Hajimirza, Shima; Howell, John

2012-06-01

This work addresses inverse optimization of three dimensional front and back surface texture grating specifications, for the purpose of shaping the absorptivity spectrum of silicon thin film cells in targeted ways. Periodic plasmonic gratings with dimensions comparable or less than the incident light wavelength are known to enhance light absorption. We consider surface patterning of amorphous silicon (a-Si) thin films using front and/or back metallic nanostrips and ITO coatings, and show that wideband enhancement in unpolarized absorptivity spectrum can be achieved when back reflectors are used. The overall short circuit current enhancement using such structures is significant and can be as high as 97%. For TM-polarized wave it can be even higher as reported in previous work. In this work however, we focus on the optimization for the more realistic unpolarized radiation which is of significantly higher complexity. In addition, optimization is done with respect to two objective functions independently: spectral absorptivity and gain-bandwidth product of the absorptivity spectrum.

Enzymes and other agents that enhance cell wall extensibility

NASA Technical Reports Server (NTRS)

Cosgrove, D. J.

1999-01-01

Polysaccharides and proteins are secreted to the inner surface of the growing cell wall, where they assemble into a network that is mechanically strong, yet remains extensible until the cells cease growth. This review focuses on the agents that directly or indirectly enhance the extensibility properties of growing walls. The properties of expansins, endoglucanases, and xyloglucan transglycosylases are reviewed and their postulated roles in modulating wall extensibility are evaluated. A summary model for wall extension is presented, in which expansin is a primary agent of wall extension, whereas endoglucanases, xyloglucan endotransglycosylase, and other enzymes that alter wall structure act secondarily to modulate expansin action.

Second-surface silvered glass solar mirrors of very high reflectance

NASA Astrophysics Data System (ADS)

Butel, Guillaume P.; Coughenour, Blake M.; Macleod, H. Angus; Kennedy, Cheryl E.; Olbert, Blain H.; Angel, J. Roger P.

2011-10-01

This paper reports methods developed to maximize the overall reflectance second-surface silvered glass. The reflectance at shorter wavelengths is increased with the aid of a dielectric enhancing layer between the silver and the glass, while at longer wavelengths it is enhanced by use of glass with negligible iron content. The calculated enhancement of reflectance, compared to unenhanced silver on standard low-iron float glass, corresponds to a 4.4% increase in reflectance averaged across the full solar spectrum, appropriate for CSP, and 2.7% for CPV systems using triple junction cells. An experimental reflector incorporating these improvements, of drawn crown glass and a silvered second-surface with dielectric boost, was measured at NREL to have 95.4% solar weighted reflectance. For comparison, non-enhanced, wetsilvered reflectors of the same 4 mm thickness show reflectance ranging from 91.6 - 94.6%, depending on iron content. A potential drawback of using iron-free drawn glass is reduced concentration in high concentration systems because of the inherent surface errors. This effect is largely mitigated for glass shaped by slumping into a concave mold, rather than by bending.

Cell Adhesion on Surface-Functionalized Magnesium.

PubMed

Wagener, Victoria; Schilling, Achim; Mainka, Astrid; Hennig, Diana; Gerum, Richard; Kelch, Marie-Luise; Keim, Simon; Fabry, Ben; Virtanen, Sannakaisa

2016-05-18

The biocompatibility of commercially pure magnesium-based (cp Mg) biodegradable implants is compromised of strong hydrogen evolution and surface alkalization due to high initial corrosion rates of cp Mg in the physiological environment. To mitigate this problem, the addition of corrosion-retarding alloying elements or coating of implant surfaces has been suggested. In the following work, we explored the effect of organic coatings on long-term cell growth. cp Mg was coated with aminopropyltriehtoxysilane + vitamin C (AV), carbonyldiimidazole (CDI), or stearic acid (SA). All three coatings have been previously suggested to reduce initial corrosion and to enhance protein adsorption and hence cell adhesion on magnesium surfaces. Endothelial cells (DH1+/+) and osteosarcoma cells (MG63) were cultured on coated samples for up to 20 days. To quantify Mg corrosion, electrochemical impedance spectroscopy (EIS) was measured after 1, 3, and 5 days of cell culture. We also investigated the speed of initial cell spreading after seeding using fluorescently labeled fibroblasts (NIH/3T3). Hydrogen evolution after contact with cell culture medium was markedly decreased on AV- and SA-coated Mg compared to uncoated Mg. These coatings also showed improved cell adhesion and spreading after 24 h of culture comparable to tissue-treated plastic surfaces. On AV-coated cp Mg, a confluent layer of endothelial cells formed after 5 days and remained intact for up to 20 days. Together, these data demonstrate that surface coating with AV is a viable strategy for improving long-term biocompatibility of cp Mg-based implants. EIS measurements confirmed that the presence of a confluent cell layer increased the corrosion resistance.

In vitro biomechanical properties, fluorescence imaging, surface-enhanced Raman spectroscopy, and photothermal therapy evaluation of luminescent functionalized CaMoO4:Eu@Au hybrid nanorods on human lung adenocarcinoma epithelial cells

PubMed Central

Li, Qifei; Parchur, Abdul K.; Zhou, Anhong

2016-01-01

Abstract Highly dispersible Eu3+-doped CaMoO4@Au-nanorod hybrid nanoparticles (HNPs) exhibit optical properties, such as plasmon resonances in the near-infrared region at 790 nm and luminescence at 615 nm, offering multimodal capabilities: fluorescence imaging, surface-enhanced Raman spectroscopy (SERS) detection and photothermal therapy (PTT). HNPs were conjugated with a Raman reporter (4-mercaptobenzoic acid), showing a desired SERS signal (enhancement factor 5.0 × 105). The HNPs have a heat conversion efficiency of 25.6%, and a hyperthermia temperature of 42°C could be achieved by adjusting either concentration of HNPs, or laser power, or irradiation time. HNPs were modified with antibody specific to cancer biomarker epidermal growth factor receptor, then applied to human lung cancer (A549) and mouse hepatocyte cells (AML12), and in vitro PTT effect was studied. In addition, the biomechanical properties of A549 cells were quantified using atomic force microscopy. This study shows the potential applications of these HNPs in fluorescence imaging, SERS detection, and PTT with good photostability and biocompatibility. PMID:27877887

Enhancing biodegradation and energy generation via roughened surface graphite electrode in microbial desalination cell.

PubMed

Ebrahimi, Atieh; Yousefi Kebria, Daryoush; Najafpour Darzi, Ghasem

2017-09-01

The microbial desalination cell (MDC) is known as a newly developed technology for water and wastewater treatment. In this study, desalination rate, organic matter removal and energy production in the reactors with and without desalination function were compared. Herein, a new design of plain graphite called roughened surface graphite (RSG) was used as the anode electrode in both microbial fuel cell (MFC) and MDC reactors for the first time. Among the three type of anode electrodes investigated in this study, RSG electrode produced the highest power density and salt removal rate of 10.81 W/m 3 and 77.6%, respectively. Such a power density was 2.33 times higher than the MFC reactor due to the junction potential effect. In addition, adding the desalination function to the MFC reactor enhanced columbic efficiency from 21.8 to 31.4%. These results provided a proof-of-concept that the use of MDC instead of MFC would improve wastewater treatment efficiency and power generation, with an added benefit of water desalination. Furthermore, RSG can successfully be employed in an MDC or MFC, enhancing the bio-electricity generation and salt removal.

The Missing Link in Epstein-Barr Virus Immune Evasion: the BDLF3 Gene Induces Ubiquitination and Downregulation of Major Histocompatibility Complex Class I (MHC-I) and MHC-II

PubMed Central

Quinn, Laura L.; Williams, Luke R.; White, Claire; Forrest, Calum; Rowe, Martin

2015-01-01

ABSTRACT The ability of Epstein-Barr virus (EBV) to spread and persist in human populations relies on a balance between host immune responses and EBV immune evasion. CD8+ cells specific for EBV late lytic cycle antigens show poor recognition of target cells compared to immediate early and early antigen-specific CD8+ cells. This phenomenon is due in part to the early EBV protein BILF1, whose immunosuppressive activity increases with lytic cycle progression. However, published data suggest the existence of a hitherto unidentified immune evasion protein further enhancing protection against late EBV antigen-specific CD8+ cells. We have now identified the late lytic BDLF3 gene as the missing link accounting for efficient evasion during the late lytic cycle. Interestingly, BDLF3 also contributes to evasion of CD4+ cell responses to EBV. We report that BDLF3 downregulates expression of surface major histocompatibility complex (MHC) class I and class II molecules in the absence of any effect upon other surface molecules screened, including CD54 (ICAM-1) and CD71 (transferrin receptor). BDLF3 both enhanced internalization of surface MHC molecules and reduced the rate of their appearance at the cell surface. The reduced expression of surface MHC molecules correlated with functional protection against CD8+ and CD4+ T cell recognition. The molecular mechanism was identified as BDLF3-induced ubiquitination of MHC molecules and their subsequent downregulation in a proteasome-dependent manner. IMPORTANCE Immune evasion is a necessary feature of viruses that establish lifelong persistent infections in the face of strong immune responses. EBV is an important human pathogen whose immune evasion mechanisms are only partly understood. Of the EBV immune evasion mechanisms identified to date, none could explain why CD8+ T cell responses to late lytic cycle genes are so infrequent and, when present, recognize lytically infected target cells so poorly relative to CD8+ T cells specific for early lytic cycle antigens. The present work identifies an additional immune evasion protein, BDLF3, that is expressed late in the lytic cycle and impairs CD8+ T cell recognition by targeting cell surface MHC class I molecules for ubiquitination and proteasome-dependent downregulation. Interestingly, BDLF3 also targets MHC class II molecules to impair CD4+ T cell recognition. BDLF3 is therefore a rare example of a viral protein that impairs both the MHC class I and class II antigen-presenting pathways. PMID:26468525

The Missing Link in Epstein-Barr Virus Immune Evasion: the BDLF3 Gene Induces Ubiquitination and Downregulation of Major Histocompatibility Complex Class I (MHC-I) and MHC-II.

PubMed

Quinn, Laura L; Williams, Luke R; White, Claire; Forrest, Calum; Zuo, Jianmin; Rowe, Martin

2016-01-01

The ability of Epstein-Barr virus (EBV) to spread and persist in human populations relies on a balance between host immune responses and EBV immune evasion. CD8(+) cells specific for EBV late lytic cycle antigens show poor recognition of target cells compared to immediate early and early antigen-specific CD8(+) cells. This phenomenon is due in part to the early EBV protein BILF1, whose immunosuppressive activity increases with lytic cycle progression. However, published data suggest the existence of a hitherto unidentified immune evasion protein further enhancing protection against late EBV antigen-specific CD8(+) cells. We have now identified the late lytic BDLF3 gene as the missing link accounting for efficient evasion during the late lytic cycle. Interestingly, BDLF3 also contributes to evasion of CD4(+) cell responses to EBV. We report that BDLF3 downregulates expression of surface major histocompatibility complex (MHC) class I and class II molecules in the absence of any effect upon other surface molecules screened, including CD54 (ICAM-1) and CD71 (transferrin receptor). BDLF3 both enhanced internalization of surface MHC molecules and reduced the rate of their appearance at the cell surface. The reduced expression of surface MHC molecules correlated with functional protection against CD8(+) and CD4(+) T cell recognition. The molecular mechanism was identified as BDLF3-induced ubiquitination of MHC molecules and their subsequent downregulation in a proteasome-dependent manner. Immune evasion is a necessary feature of viruses that establish lifelong persistent infections in the face of strong immune responses. EBV is an important human pathogen whose immune evasion mechanisms are only partly understood. Of the EBV immune evasion mechanisms identified to date, none could explain why CD8(+) T cell responses to late lytic cycle genes are so infrequent and, when present, recognize lytically infected target cells so poorly relative to CD8(+) T cells specific for early lytic cycle antigens. The present work identifies an additional immune evasion protein, BDLF3, that is expressed late in the lytic cycle and impairs CD8(+) T cell recognition by targeting cell surface MHC class I molecules for ubiquitination and proteasome-dependent downregulation. Interestingly, BDLF3 also targets MHC class II molecules to impair CD4(+) T cell recognition. BDLF3 is therefore a rare example of a viral protein that impairs both the MHC class I and class II antigen-presenting pathways. Copyright © 2015, American Society for Microbiology. All Rights Reserved.