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Sample records for agarose hydrogel particles

  1. Functional modification of agarose: a facile synthesis of a fluorescent agarose-tryptophan based hydrogel.

    PubMed

    Kondaveeti, Stalin; Prasad, Kamalesh; Siddhanta, A K

    2013-08-14

    Microwave assisted facile synthesis of a fluorescent agarose-l-tryptophan hydrogel material employing carbodiimide chemistry (dicyclohexylcarbodiimide/4-dimethylaminopyridine; DCC/DMAP) has been described. The product formed fluorescent hydrogel at 1-1.5% (w/v), exhibiting fluorescence emission in water (λmax 350 nm; 1x10(-4)M), which was significantly higher (ca. 65%) than that of tryptophan at the same concentration. Subsequently, the agarose ester was cross linked with the natural cross linker genipin to yield a blue hydrogel (G-Ag-TrpEst), confirming thereby the insertion of tryptophan moiety on to agarose backbone. Both the ester and cross linked hydrogels demonstrated gelling characteristics similar to agarose and were stable across a wide range of pH media (pHs 1.2, 7.0 and 12.5) under ambient conditions. These tryptophan containing fluorescent hydrogel materials may find applications in biomedical and pharmaceutical industries as potential radical scavengers and sensors.

  2. Chitosan/agarose hydrogels: cooperative properties and microfluidic preparation.

    PubMed

    Zamora-Mora, Vanessa; Velasco, Diego; Hernández, Rebeca; Mijangos, Carmen; Kumacheva, Eugenia

    2014-10-13

    The preparation of composite biopolymer hydrogels offers the capability to produce biocompatible and biodegradable materials with cooperative properties. In this paper, two natural polymers, namely, chitosan and agarose were employed to prepare composite hydrogels with dual pH and temperature properties. The elastic modulus of the composite hydrogels increased with agarose concentration reaching the value of 1 kPa for the chitosan/agarose gel with a 2% (w/v) concentration of agarose. In addition, composite gels exhibited a higher stability in acidic aqueous solutions, in comparison with agarose gels. The drug release properties of the composite hydrogels were tested by loading a model anticancer drug, 5-Fluorouracil, in the hydrogel interior. At pH=7.4, the cumulative release of 5-FU was ∼ 50% within 96 h and decreased to ∼ 33% at pH = 5.2, which was attributed to the different solubility of 5-FU as a function of pH. The preparation of composite microgels with controllable dimensions in the range from 42 to 18 μm and with narrow size distribution (polidispersity not exceeding 1.5%) was achieved by the microfluidic emulsification of an aqueous mixture of chitosan and agarose and subsequent gelation of the precursor droplets by cooling.

  3. Fabrication of multilayered vascular tissues using microfluidic agarose hydrogel platforms.

    PubMed

    Kinoshita, Keita; Iwase, Masaki; Yamada, Masumi; Yajima, Yuya; Seki, Minoru

    2016-11-01

    Vascular tissues fabricated in vitro are useful tools for studying blood vessel-related cellular physiologies and for constructing relatively large 3D tissues. An efficient strategy for fabricating vascular tissue models with multilayered, branched, and thick structures through the in situ hydrogel formation in fluidic channels is proposed. First, an aqueous solution of RGD-alginate containing smooth muscle cells (SMCs) is introduced into channel structures made of agarose hydrogel, forming a cell-embedding Ca-alginate hydrogel layer with a thickness of several hundred micrometers on the channel surface because of the Ca(2+) ions diffused from the agarose hydrogel matrix. Next, endothelial cells (ECs) are introduced and cultured for up to seven days to form hierarchically organized, multilayered vascular tissues. The factors affecting the thickness of the Ca-alginate hydrogel layer, and prepared several types of microchannels with different morphologies are examined. The fabricated vascular tissue models are easily recovered from the channel by simply detaching the agarose hydrogel plates. In addition, the effect of O2 tension (20 or 80%) on the viability and elastin production of SMCs during the perfusion culture is evaluated. This technique would pave a new way for vascular tissue engineering because it enables the facile production of morphologically in vivo vascular tissue-like structures that can be employed for various biomedical applications.

  4. Agarose and methylcellulose hydrogel blends for nerve regeneration applications

    NASA Astrophysics Data System (ADS)

    Martin, Benton C.; Minner, Eric J.; Wiseman, Sherri L.; Klank, Rebecca L.; Gilbert, Ryan J.

    2008-06-01

    Trauma sustained to the central nervous system is a debilitating problem for thousands of people worldwide. Neuronal regeneration within the central nervous system is hindered by several factors, making a multi-faceted approach necessary. Two factors contributing to injury are the irregular geometry of injured sites and the absence of tissue to hold potential nerve guides and drug therapies. Biocompatible hydrogels, injectable at room temperature, that rapidly solidify at physiological temperatures (37 °C) are beneficial materials that could hold nerve guidance channels in place and be loaded with therapeutic agents to aid wound healing. Our studies have shown that thermoreversible methylcellulose can be combined with agarose to create hydrogel blends that accommodate these properties. Three separate novel hydrogel blends were created by mixing methylcellulose with one of the three different agaroses. Gelation time tests show that the blends solidify at a faster rate than base methylcellulose at 37 °C. Rheological data showed that the elastic modulus of the hydrogel blends rapidly increases at 37 °C. Culturing experiments reveal that the morphology of dissociated dorsal root ganglion neurons was not altered when the hydrogels were placed onto the cells. The different blends were further assessed using dissolution tests, pore size evaluations using scanning electron microscopy and measuring the force required for injection. This research demonstrates that blends of agarose and methylcellulose solidify much more quickly than plain methylcellulose, while solidifying at physiological temperatures where agarose cannot. These hydrogel blends, which solidify at physiological temperatures naturally, do not require ultraviolet light or synthetic chemical cross linkers to facilitate solidification. Thus, these hydrogel blends have potential use in delivering therapeutics and holding scaffolding in place within the nervous system.

  5. Composites of Quasi-Colloidal Layered Double Hydroxide Nanoparticles and Agarose Hydrogels for Chromate Removal

    PubMed Central

    Gwak, Gyeong-Hyeon; Kim, Min-Kyu; Oh, Jae-Min

    2016-01-01

    Composite hydrogels were prepared that consisted of quasi-colloidal layered double hydroxide (LDH) nanoparticles and agarose via the electrophoretic method, starting from three different agarose concentrations of 0.5, 1, and 2 wt/v%. The composite hydrogel was identified to have a uniform distribution of LDH nanoparticles in agarose matrix. Microscopic studies revealed that the composite hydrogel had a homogeneous quasi-colloidal state of LDHs, while the simple mixture of LDH powder and agarose hydrogels did not. It was determined that agarose concentration of the starting hydrogel did not significantly influence the amount of LDH that developed in the composite. The chromate scavenging efficiency of the composite hydrogel and corresponding agarose or mixture hydrogel was evaluated with respect to time, and chromate concentration. In general, the composite hydrogels exhibited much higher chromate removal efficacy compared with agarose or mixture hydrogels. Through estimating chromate adsorption by LDH moiety in the composite or mixture hydrogel, it was suggested that the agarose component facilitated the stability and dispersibility of the quasi-colloidal state of LDH nanoparticles in the composite resulting in high adsorption efficacy. From Freundlich isotherm adsorption fitting, composites were determined to possess beneficial cooperative adsorption behavior with a high adsorption coefficient. PMID:28344282

  6. Injectable Amorphous Chitin-Agarose Composite Hydrogels for Biomedical Applications

    PubMed Central

    Priya, Murali Vishnu; Kumar, Rajendran Arun; Sivashanmugam, Amirthalingam; Nair, Shantikumar Vasudevan; Jayakumar, Rangasamy

    2015-01-01

    Injectable hydrogels are gaining popularity as tissue engineering constructs because of their ease of handling and minimal invasive delivery. Making hydrogels from natural polymers helps to overcome biocompatibility issues. Here, we have developed an Amorphous Chitin (ACh)-Agarose (Agr) composite hydrogel using a simpletechnique. Rheological studies, such as viscoelastic behavior (elastic modulus, viscous modulus, yield stress, and consistency), inversion test, and injectability test, were carried out for different ACh-Agr concentrations. The composite gel, having a concentration of 1.5% ACh and 0.25% Agr, showed good elastic modulus (17.3 kPa), yield stress (3.8 kPa), no flow under gravity, injectability, and temperature stability within the physiological range. Based on these studies, the optimum concentration for injectability was found to be 1.5% ACh and 0.25% Agr. This optimized concentration was used for further studies and characterized using FT-IR and SEM. FT-IR studies confirmed the presence of ACh and Agr in the composite gel. SEM results showed that the lyophilized composite gel had good porosity and mesh like networks. The cytocompatibility of the composite gel was studied using human mesenchymal stem cells (hMSCs). The composite gels showed good cell viability.These results indicated that this injectable composite gel can be used for biomedical applications. PMID:26308065

  7. Time Controlled Protein Release from Layer-by-Layer Assembled Multilayer Functionalized Agarose Hydrogels

    PubMed Central

    Mehrotra, Sumit; Lynam, Daniel; Maloney, Ryan; Pawelec, Kendell M.; Tuszynski, Mark H.; Lee, Ilsoon

    2009-01-01

    Axons of the adult central nervous system exhibit an extremely limited ability to regenerate after spinal cord injury. Experimentally generated patterns of axon growth are typically disorganized and randomly oriented. Support of linear axonal growth into spinal cord lesion sites has been demonstrated using arrays of uniaxial channels, templated with agarose hydrogel, and containing genetically engineered cells that secrete brain-derived neurotrophic factor (BDNF). However, immobilizing neurotrophic factors secreting cells within a scaffold is relatively cumbersome, and alternative strategies are needed to provide sustained release of BDNF from templated agarose scaffolds. Existing methods of loading the drug or protein into hydrogels cannot provide sustained release from templated agarose hydrogels. Alternatively, here it is shown that pH-responsive H-bonded poly(ethylene glycol)(PEG)/poly(acrylic acid)(PAA)/protein hybrid layer-by-layer (LbL) thin films, when prepared over agarose, provided sustained release of protein under physiological conditions for more than four weeks. Lysozyme, a protein similar in size and isoelectric point to BDNF, is released from the multilayers on the agarose and is biologically active during the earlier time points, with decreasing activity at later time points. This is the first demonstration of month-long sustained protein release from an agarose hydrogel, whereby the drug/protein is loaded separately from the agarose hydrogel fabrication process. PMID:20200599

  8. Porous Agarose-Based Semi-IPN Hydrogels: Characterization and Cell Affinity Studies.

    PubMed

    Vardar, E; Vert, Michel; Coudane, Jean; Hasirci, V; Hasirci, N

    2012-01-01

    Hydrogels are frequently considered for medical applications due to the ease of preparation in different forms and high water content that makes them comparable to natural tissues. However, these general properties are not sufficient to make any hydrogel suitable for cell attachment and growth which are necessary for their use in tissue regeneration. Besides, the high water content makes the hydrogels mechanically weak. The formation of semi-interpenetrating networks (semi-IPNs) can be used in attempts to enhance physical, mechanical and thermal properties. In this study, semi-IPNs of agarose were prepared with chitosan and alginate, two polyelectrolytes that are positively and negatively charged under physiological conditions, respectively. Zeta potential was used to confirm the formation of charged hydrogels. All hydrogels had ultimate compression strengths in the range of 91-210 Pa where the value for pure agarose was about 103 Pa. Chitosan increased the compressive strength about two folds whereas the alginate had opposite effects. The amount of strongly bound water present in the hydrogels were estimated from TGA and DSC analysis and the highest value was found for alginate-agarose hydrogels as about 15%. The attachment and the migration of L929 fibroblasts were monitored in vitro using the MTS assay and confocal microscopy. The highest cell proliferation and penetration were observed for positively charged chitosan-agarose semi-IPN hydrogels.

  9. Fabrication of Self-Healable and Patternable Polypyrrole/Agarose Hybrid Hydrogels for Smart Bioelectrodes.

    PubMed

    Park, Nokyoung; Chae, Seung Chul; Kim, Il Tae; Hur, Jaehyun

    2016-02-01

    We present a new class of electrically conductive, mechanically moldable, and thermally self-healable hybrid hydrogels. The hybrid gels consist of polypyrrole and agarose as the conductive component and self-healable matrix, respectively. By using the appropriate oxidizing agent under conditions of mild temperature, the polymerization of pyrrole occurred along the three-dimensional network of the agarose hydrogel matrix. In contrast to most commercially available hydrogels, the physical crosslinking of agarose gel allows for reversible gelation in the case of our hybrid gel, which could be manipulated by temperature variation, which controls the electrical on/off behavior of the hybrid gel electrode. Exploiting this property, we fabricated a hybrid conductive hydrogel electrode which also self-heals thermally. The novel composite material we report here will be useful for many technological and biological applications, especially in reactive biomimetic functions and devices, artificial muscles, smart membranes, smart full organic batteries, and artificial chemical synapses.

  10. Fenugreek hydrogel-agarose composite entrapped gold nanoparticles for acetylcholinesterase based biosensor for carbamates detection.

    PubMed

    Kestwal, Rakesh Mohan; Bagal-Kestwal, Dipali; Chiang, Been-Huang

    2015-07-30

    A biosensor was fabricated to detect pesticides in food samples. Acetylcholinesterase was immobilized in a novel fenugreek hydrogel-agarose matrix with gold nanoparticles. Transparent thin films with superior mechanical strength and stability were obtained with 2% fenugreek hydrogel and 2% agarose. Immobilization of acetylcholinesterase on the membrane resulted in high enzyme retention efficiency (92%) and a significantly prolonged shelf life of the enzyme (half-life, 55 days). Transmission electron microscopy revealed that, gold nanoparticles (10-20 nm in diameter) were uniformly dispersed in the fenugreek hydrogel-agarose-acetylcholinesterase membrane. This immobilized enzyme-gold nanoparticle dip-strip system detected various carbamates, including carbofuran, oxamyl, methomyl, and carbaryl, with limits of detection of 2, 21, 113, and 236 nM (S/N = 3), respectively. Furthermore, the fabricated biosensor exhibited good testing capabilities when used to detect carbamates added to various fruit and vegetable samples.

  11. Oxidized dextrins as alternative crosslinking agents for polysaccharides: application to hydrogels of agarose-chitosan.

    PubMed

    Gómez-Mascaraque, Laura G; Méndez, José Alberto; Fernández-Gutiérrez, Mar; Vázquez, Blanca; San Román, Julio

    2014-02-01

    Hydrogel networks that combine suitable physical and biomechanical characteristics for tissue engineering scaffolds are in demand. The aim of this work was the development of hydrogel networks based on agarose and chitosan using oxidized dextrins as low cytotoxicity crosslinking agents, paying special attention to the study of the influence of the polysaccharide composition and oxidation degree of the dextrins in the final characteristics of the network. The results show that the formation of an interpenetrating or a semi-interpenetrating polymer network was mainly dependent on a minimum agarose content and degree of oxidation of dextrin. Spectroscopic, thermal and swelling analysis revealed good compatibility with an absence of phase separation of polysaccharides at agarose:chitosan proportions of 50:50 and 25:75. The analysis of atomic force microscopy images showed the formation of a fibrillar microstructure whose distribution within the crosslinked chitosan depended mainly on the crosslinker. All materials exhibited the viscoelastic behaviour typical of gels, with a constant storage modulus independent of frequency for all compositions. The stiffness was strongly influenced by the degree of oxidation of the crosslinker. Cellular response to the hydrogels was studied with cells of different strains, and cell adhesion and proliferation was correlated with the homogeneity of the samples and their elastic properties. Some hydrogel formulations seemed to be candidates for tissue engineering applications such as wound healing or soft tissue regeneration.

  12. Hierarchically designed agarose and poly(ethylene glycol) interpenetrating network hydrogels for cartilage tissue engineering.

    PubMed

    DeKosky, Brandon J; Dormer, Nathan H; Ingavle, Ganesh C; Roatch, Christopher H; Lomakin, Joseph; Detamore, Michael S; Gehrke, Stevin H

    2010-12-01

    A new method for encapsulating cells in interpenetrating network (IPN) hydrogels of superior mechanical integrity was developed. In this study, two biocompatible materials-agarose and poly(ethylene glycol) (PEG) diacrylate-were combined to create a new IPN hydrogel with greatly enhanced mechanical performance. Unconfined compression of hydrogel samples revealed that the IPN displayed a fourfold increase in shear modulus relative to a pure PEG-diacrylate network (39.9 vs. 9.9 kPa) and a 4.9-fold increase relative to a pure agarose network (8.2 kPa). PEG and IPN compressive failure strains were found to be 71% ± 17% and 74% ± 17%, respectively, while pure agarose gels failed around 15% strain. Similar mechanical property improvements were seen when IPNs-encapsulated chondrocytes, and LIVE/DEAD cell viability assays demonstrated that cells survived the IPN encapsulation process. The majority of IPN-encapsulated chondrocytes remained viable 1 week postencapsulation, and chondrocytes exhibited glycosaminoglycan synthesis comparable to that of agarose-encapsulated chondrocytes at 3 weeks postencapsulation. The introduction of a new method for encapsulating cells in a hydrogel with enhanced mechanical performance is a promising step toward cartilage defect repair. This method can be applied to fabricate a broad variety of cell-based IPNs by varying monomers and polymers in type and concentration and by adding functional groups such as degradable sequences or cell adhesion groups. Further, this technology may be applicable in other cell-based applications where mechanical integrity of cell-containing hydrogels is of great importance.

  13. Agarose hydrogels embedded with pH-responsive diblock copolymer micelles for triggered release of substances.

    PubMed

    Jin, Naixiong; Morin, Emily A; Henn, Daniel M; Cao, Yu; Woodcock, Jeremiah W; Tang, Shuangcheng; He, Wei; Zhao, Bin

    2013-08-12

    Hybrid agarose hydrogels embedded with pH-responsive diblock copolymers micelles were developed to achieve functional hydrogels capable of stimulus-triggered drug release. Specifically, a well-defined poly(ethylene oxide) (PEO)-based diblock copolymer, PEO-b-poly(2-(N,N-diisopropylamino)ethyl methacrylate) (PEO(113)-b-PDPAEMA(31), where the subscripts represent the degrees of polymerization of two blocks), was synthesized by atom transfer radical polymerization. PDPAEMA is a pH-responsive polymer with a pKa value of 6.3. The PEO(113)-b-PDPAEMA(31) micelles were formed by a solvent-switching method, and their pH-dependent dissociation behavior was investigated by dynamic light scattering and fluorescence spectroscopy. Both studies indicated that the micelles were completely disassembled at pH = 6.40. The biocompatibility of PEO(113)-b-PDPAEMA(31) micelles was demonstrated by in vitro primary cortical neural culture. Hybrid agarose hydrogels were made by cooling 1.0 wt % agarose solutions that contained various amounts of PEO(113)-b-PDPAEMA(31) micelles at either 2 or 4 °C. Rheological measurements showed that the mechanical properties of gels were not significantly adversely affected by the incorporation of diblock copolymer micelles with a concentration as high as 5.0 mg/g. Using Nile Red as a model hydrophobic drug, its incorporation into the core of diblock copolymer micelles was demonstrated. Characterized by fluorescent spectroscopy, the release of Nile Red from the hybrid hydrogel was shown to be controllable by pH due to the responsiveness of the block copolymer micelles. Based on the prominent use of agarose gels as scaffolds for cell transplantation for neural repair, the hybrid hydrogels embedded with stimuli-responsive block copolymer micelles could allow the controlled delivery of hydrophobic neuroprotective agents to improve survival of transplanted cells in tune with signals from the surrounding pathological environment.

  14. Rheological and mechanical behavior of polyacrylamide hydrogels chemically crosslinked with allyl agarose for two-dimensional gel electrophoresis.

    PubMed

    Suriano, R; Griffini, G; Chiari, M; Levi, M; Turri, S

    2014-02-01

    Two-dimensional (2-D) gel electrophoresis currently represents one of the most standard techniques for protein separation. In addition to the most commonly employed polyacrylamide crosslinked hydrogels, acrylamide-agarose copolymers have been proposed as promising systems for separation matrices in 2-D electrophoresis, because of the good resolution of both high and low molecular mass proteins made possible by careful control and optimization of the hydrogel pore structure. As a matter of fact, a thorough understanding of the nature of the hydrogel pore structure as well as of the parameters by which it is influenced is crucial for the design of hydrogel systems with optimal sieving properties. In this work, a series of acrylamide-based hydrogels covalently crosslinked with different concentrations of allyl agarose (0.2-1%) is prepared and characterized by creep-recovery measurements, dynamic rheology and tensile tests, in the attempt to gain a clearer understanding of structure-property relationships in crosslinked polyacrylamide-based hydrogels. The rheological and mechanical properties of crosslinked acrylamide-agarose hydrogels are found to be greatly affected by crosslinker concentration. Dynamic rheological tests show that hydrogels with a percentage of allyl agarose between 0.2% and 0.6% have a low density of elastically effective crosslinks, explaining the good separation of high molecular mass proteins in 2-D gel electrophoresis. Over the same range of crosslinker concentration, creep-recovery measurements reveal the presence of non-permanent crosslinks in the hydrogel network that justifies the good resolution of low molecular mass proteins as well. In tensile tests, the hydrogel crosslinked with 0.4% of allyl agarose exhibits the best results in terms of mechanical strength and toughness. Our results show how the control of the viscoelastic and the mechanical properties of these materials allow the design of mechanically stable hydrogels with improved

  15. In vivo bioengineered ovarian tumors based on collagen, matrigel, alginate and agarose hydrogels: a comparative study.

    PubMed

    Zheng, Li; Hu, Xuefeng; Huang, Yuanjie; Xu, Guojie; Yang, Jinsong; Li, Li

    2015-01-29

    Scaffold-based tumor engineering is rapidly evolving the study of cancer progression. However, the effects of scaffolds and environment on tumor formation have seldom been investigated. In this study, four types of injectable hydrogels, namely, collagen type I, Matrigel, alginate and agarose gels, were loaded with human ovarian cancer SKOV3 cells and then injected into nude mice subcutaneously. The growth of the tumors in vitro was also investigated. After four weeks, the specimens were harvested and analyzed. We found that tumor formation by SKOV3 cells was best supported by collagen, followed by Matrigel, alginate, control (without scaffold) and agarose in vivo. The collagen I group exhibited a larger tumor volume with increased neovascularization and increased necrosis compared with the other materials. Further, increased MMP activity, upregulated expression of laminin and fibronectin and higher levels of HIF-1α and VEGF-A in the collagen group revealed that the engineered tumor is closer to human ovarian carcinoma. In order, collagen, Matrigel, alginate, control (without scaffold) and agarose exhibited decreases in tumor formation. All evidence indicated that the in vivo engineered tumor is scaffold-dependent. Bioactive hydrogels are superior to inert hydrogels at promoting tumor regeneration. In particular, biomimetic hydrogels are advantageous because they provide a microenvironment that mimics the ECM of natural tumors. On the other hand, typical features of cancer cells and the expression of genes related to cancer malignancy were far less similar to the natural tumor in vitro, which indicated the importance of culture environment in vivo. Superior to the in vitro culture, nude mice can be considered satisfactory in vivo 'bioreactors' for the screening of favorable cell vehicles for tumor engineering in vitro.

  16. Carbon dots rooted agarose hydrogel hybrid platform for optical detection and separation of heavy metal ions.

    PubMed

    Gogoi, Neelam; Barooah, Mayuri; Majumdar, Gitanjali; Chowdhury, Devasish

    2015-02-11

    A robust solid sensing platform for an on-site operational and accurate detection of heavy metal is still a challenge. We introduce chitosan based carbon dots rooted agarose hydrogel film as a hybrid solid sensing platform for detection of heavy metal ions. The fabrication of the solid sensing platform is centered on simple electrostatic interaction between the NH3+ group present in the carbon dots and the OH- groups present in agarose. Simply on dipping the hydrogel film strip into the heavy metal ion solution, in particular Cr6+, Cu2+, Fe3+, Pb2+, Mn2+, the strip displays a color change, viz., Cr6+→yellow, Cu2+→blue, Fe3+→brown, Pb2+→white, Mn2+→tan brown. The optical detection limit of the respective metal ion is found to be 1 pM for Cr6+, 0.5 μM for Cu2+, and 0.5 nM for Fe3+, Pb2+, and Mn2+ by studying the changes in UV-visible reflectance spectrum of the hydrogel film. Moreover, the hydrogel film finds applicability as an efficient filtration membrane for separation of these quintet heavy metal ions. The strategic fundamental feature of this sensing platform is the successful capability of chitosan to form colored chelates with transition metals. This proficient hybrid hydrogel solid sensing platform is thus the most suitable to employ as an on-site operational, portable, cheap colorimetric-optical detector of heavy metal ion with potential skill in their separation. Details of the possible mechanistic insight into the colorimetric detection and ion separation are also discussed.

  17. Agarose hydrogel microcompartments for imaging sleep- and wake-like behavior and nervous system development in Caenorhabditis elegans larvae.

    PubMed

    Bringmann, Henrik

    2011-09-30

    Caenorhabditis elegans larvae display specific behavior and development that is not observed in adults. For example, larvae go through a molting cycle that includes a sleep-like state prior to the molt. The study of these processes requires high-resolution long-term observation of individual animals. Here we describe a method for simultaneous culture and observation of several individual young C. elegans larvae inside agarose hydrogel-based arrayed microcompartments. We used agarose hydrogel microcompartments to observe and quantify larval specific sleep-wake-like behavior and to observe neuronal rewiring using confocal fluorescence microscopy without acute immobilization. We found no behavioral aberrations caused by area restriction. We show that worms cultured inside hydrogel microcompartments develop into normal adults. Thus, hydrogel microcompartments appear useful for long-term observation of larval behavior and development.

  18. In vivo remineralization of dentin using an agarose hydrogel biomimetic mineralization system

    NASA Astrophysics Data System (ADS)

    Han, Min; Li, Quan-Li; Cao, Ying; Fang, Hui; Xia, Rong; Zhang, Zhi-Hong

    2017-02-01

    A novel agarose hydrogel biomimetic mineralization system loaded with calcium and phosphate was used to remineralize dentin and induce the oriented densely parallel packed HA layer on defective dentin surface in vivo in a rabbit model. Firstly, the enamel of the labial surface of rabbits’ incisor was removed and the dentin was exposed to oral environment. Secondly, the hydrogel biomimetic mineralization system was applied to the exposed dentin surface by using a custom tray. Finally, the teeth were extracted and evaluated by scanning electron microscopy, X-ray diffraction, and nanoindentation test after a certain time of mineralization intervals. The regenerated tissue on the dentin surface was composed of highly organised HA crystals. Densely packed along the c axis, these newly precipitated HA crystals were perpendicular to the underlying dental surface with a tight bond. The demineralized dentin was remineralized and dentinal tubules were occluded by the grown HA crystals. The nanohardness and elastic modulus of the regenerated tissue were similar to natural dentin. The results indicated a potential clinical use for repairing dentin-exposed related diseases, such as erosion, wear, and dentin hypersensitivity.

  19. In vivo remineralization of dentin using an agarose hydrogel biomimetic mineralization system

    PubMed Central

    Han, Min; Li, Quan-Li; Cao, Ying; Fang, Hui; Xia, Rong; Zhang, Zhi-Hong

    2017-01-01

    A novel agarose hydrogel biomimetic mineralization system loaded with calcium and phosphate was used to remineralize dentin and induce the oriented densely parallel packed HA layer on defective dentin surface in vivo in a rabbit model. Firstly, the enamel of the labial surface of rabbits’ incisor was removed and the dentin was exposed to oral environment. Secondly, the hydrogel biomimetic mineralization system was applied to the exposed dentin surface by using a custom tray. Finally, the teeth were extracted and evaluated by scanning electron microscopy, X-ray diffraction, and nanoindentation test after a certain time of mineralization intervals. The regenerated tissue on the dentin surface was composed of highly organised HA crystals. Densely packed along the c axis, these newly precipitated HA crystals were perpendicular to the underlying dental surface with a tight bond. The demineralized dentin was remineralized and dentinal tubules were occluded by the grown HA crystals. The nanohardness and elastic modulus of the regenerated tissue were similar to natural dentin. The results indicated a potential clinical use for repairing dentin-exposed related diseases, such as erosion, wear, and dentin hypersensitivity. PMID:28167823

  20. Combination of fibrin-agarose hydrogels and adipose-derived mesenchymal stem cells for peripheral nerve regeneration

    NASA Astrophysics Data System (ADS)

    Carriel, Víctor; Garrido-Gómez, Juan; Hernández-Cortés, Pedro; Garzón, Ingrid; García-García, Salomé; Sáez-Moreno, José Antonio; Sánchez-Quevedo, María del Carmen; Campos, Antonio; Alaminos, Miguel

    2013-04-01

    Objective. The objective was to study the effectiveness of a commercially available collagen conduit filled with fibrin-agarose hydrogels alone or with fibrin-agarose hydrogels containing autologous adipose-derived mesenchymal stem cells (ADMSCs) in a rat sciatic nerve injury model. Approach. A 10 mm gap was created in the sciatic nerve of 48 rats and repaired using saline-filled collagen conduits or collagen conduits filled with fibrin-agarose hydrogels alone (acellular conduits) or with hydrogels containing ADMSCs (ADMSC conduits). Nerve regeneration was assessed in clinical, electrophysiological and histological studies. Main results. Clinical and electrophysiological outcomes were more favorable with ADMSC conduits than with the acellular or saline conduits, evidencing a significant recovery of sensory and motor functions. Histological analysis showed that ADMSC conduits produce more effective nerve regeneration by Schwann cells, with higher remyelination and properly oriented axonal growth that reached the distal areas of the grafted conduits, and with intensely positive expressions of S100, neurofilament and laminin. Extracellular matrix was also more abundant and better organized around regenerated nerve tissues with ADMSC conduits than those with acellular or saline conduits. Significance. Clinical, electrophysiological and histological improvements obtained with tissue-engineered ADMSC conduits may contribute to enhancing axonal regeneration by Schwann cells.

  1. Comparison of oligonucleotide migration in a bicontinuous cubic phase of monoolein and water and in a fibrous agarose hydrogel.

    PubMed

    Sanandaji, Nima; Carlsson, Nils; Voinova, Marina; Akerman, Björn

    2006-08-01

    Porous hydrogels such as agarose are commonly used to analyze DNA and water-soluble proteins by electrophoresis. More recently lyotropic liquid crystals, such as the diamond cubic phase formed by the lipid monoolein and water, has become a new type of well-defined porous structure of interest for both hydrophilic and amphiphilic analytes. Here we compare these two types of matrixes by investigating the nature of retardation they confer to an oligonucleotide that migrates in their respective aqueous phases. The retardation for a 25-mer oligonucleotide was found to be about 35-fold stronger in the cubic phase than in an agarose hydrogel modified to have the same average pore size. According to modelling, the strong retardation is primarily due to the fact that hydrodynamic interaction with the continuous monoolein membrane is a stronger source of friction than the steric interactions (collisions) with discrete gel fibres. A secondary effect is that the regular liquid crystal has a narrower pore-size distribution than the random network of the agarose gel. In agreement with experiments, these two effects together predict that the retardation in the cubic phase is a 30-fold stronger than in an agarose gel with the same average pore radius.

  2. Tuning mechanical performance of poly(ethylene glycol) and agarose interpenetrating network hydrogels for cartilage tissue engineering.

    PubMed

    Rennerfeldt, Deena A; Renth, Amanda N; Talata, Zsolt; Gehrke, Stevin H; Detamore, Michael S

    2013-11-01

    Hydrogels are attractive for tissue engineering applications due to their incredible versatility, but they can be limited in cartilage tissue engineering applications due to inadequate mechanical performance. In an effort to address this limitation, our team previously reported the drastic improvement in the mechanical performance of interpenetrating networks (IPNs) of poly(ethylene glycol) diacrylate (PEG-DA) and agarose relative to pure PEG-DA and agarose networks. The goal of the current study was specifically to determine the relative importance of PEG-DA concentration, agarose concentration, and PEG-DA molecular weight in controlling mechanical performance, swelling characteristics, and network parameters. IPNs consistently had compressive and shear moduli greater than the additive sum of either single network when compared to pure PEG-DA gels with a similar PEG-DA content. IPNs withstood a maximum stress of up to 4.0 MPa in unconfined compression, with increased PEG-DA molecular weight being the greatest contributing factor to improved failure properties. However, aside from failure properties, PEG-DA concentration was the most influential factor for the large majority of properties. Increasing the agarose and PEG-DA concentrations as well as the PEG-DA molecular weight of agarose/PEG-DA IPNs and pure PEG-DA gels improved moduli and maximum stresses by as much as an order of magnitude or greater compared to pure PEG-DA gels in our previous studies. Although the viability of encapsulated chondrocytes was not significantly affected by IPN formulation, glycosaminoglycan (GAG) content was significantly influenced, with a 12-fold increase over a three-week period in gels with a lower PEG-DA concentration. These results suggest that mechanical performance of IPNs may be tuned with partial but not complete independence from biological performance of encapsulated cells.

  3. Tuning mechanical performance of poly(ethylene glycol) and agarose interpenetrating network hydrogels for cartilage tissue engineering

    PubMed Central

    Rennerfeldt, DA; Renth, AN; Talata, Z; Gehrke, SH; Detamore, MS

    2013-01-01

    Hydrogels are attractive for tissue engineering applications due to their incredible versatility, but they can be limited in cartilage tissue engineering applications due to inadequate mechanical performance. In an effort to address this limitation, our team previously reported the drastic improvement in the mechanical performance of interpenetrating networks (IPNs) of poly(ethylene glycol) diacrylate (PEG-DA) and agarose relative to pure PEG-DA and agarose networks. The goal of the current study was specifically to determine the relative importance of PEG-DA concentration, agarose concentration, and PEG-DA molecular weight in controlling mechanical performance, swelling characteristics, and network parameters. IPNs consistently had compressive and shear moduli greater than the additive sum of either single network when compared to pure PEG-DA gels with a similar PEG-DA content. IPNs withstood a maximum stress of up to 4.0 MPa in unconfined compression, with increased PEG-DA molecular weight being the greatest contributing factor to improved failure properties. However, aside from failure properties, PEG-DA concentration was the most influential factor for the large majority of properties. Increasing the agarose and PEG-DA concentrations as well as the PEG-DA molecular weight of agarose/PEG-DA IPNs and pure PEG-DA gels improved moduli and maximum stresses by as much as an order of magnitude or greater compared to pure PEG-DA gels in our previous studies. Although the viability of encapsulated chondrocytes was not significantly affected by IPN formulation, glycosaminoglycan (GAG) content was significantly influenced, with a 12-fold increase over a three-week period in gels with a lower PEG-DA concentration. These results suggest that mechanical performance of IPNs may be tuned with partial but not complete independence from biological performance of encapsulated cells. PMID:23932504

  4. Agarose particle-templated porous bacterial cellulose and its application in cartilage growth in vitro.

    PubMed

    Yin, Na; Stilwell, Matthew D; Santos, Thiago M A; Wang, Huaping; Weibel, Douglas B

    2015-01-01

    Bacterial cellulose (BC) is a biocompatible hydrogel with a three-dimensional (3-D) structure formed by a dense network of cellulose nanofibers. A limitation of using BC for applications in tissue engineering is that the pore size of the material (∼0.02-10μm) is smaller than the dimensions of mammalian cells and prevents cells from penetrating into the material and growing into 3-D structures that mimic tissues. This paper describes a new route to porous bacterial cellulose (pBC) scaffolds by cultivating Acetobacter xylinum in the presence of agarose microparticles deposited on the surface of a growing BC pellicle. Monodisperse agarose microparticles with a diameter of 300-500μm were created using a microfluidic technique, layered on growing BC pellicles and incorporated into the polymer as A. xylinum cells moved upward through the growing pellicle. Removing the agarose microparticles by autoclaving produced BC gels containing a continuous, interconnected network of pores with diameters ranging from 300 to 500μm. Human P1 chondrocytes seeded on the scaffolds, replicated, invaded the 3-D porous network and distributed evenly throughout the substrate. Chondrocytes grown on pBC substrates displayed a higher viability compared to growth on the surface of unmodified BC substrates. The approach described in this paper introduces a new method for creating pBC substrates with user-defined control over the physical dimensions of the pore network, and demonstrates the application of these materials for tissue engineering.

  5. Quantitative Assessment of Macromolecular Concentration during Direct Infusion into an Agarose Hydrogel Phantom using Contrast-Enhanced MRI

    PubMed Central

    Chen, Xiaoming; Astary, Garrett W.; Sepulveda, Hector; Mareci, Thomas H.; Sarntinoranont, Malisa

    2011-01-01

    Convection-enhanced delivery (CED), i.e., direct tissue infusion, has emerged as a promising local drug delivery method for treating diseases of the nervous system. Determination of the spatial distribution of therapeutic agents after infusion is important in evaluating the efficacy of treatment, optimizing infusion protocols, and improving the understanding of drug pharmacokinetics. In this study, we provide a methodology to determine the concentration distribution of Gd-labeled tracers during infusion using contrast-enhanced MR imaging. To the best of our knowledge, MR studies that quantify concentration profiles for CED have not been previously reported. The methodology utilizes intrinsic material properties (T1 and R1) and reduces the effect of instrumental factors (e.g., inhomogeneity of MR detection field). As a methodology investigation, this study used an agarose hydrogel phantom as a tissue substitute for infusion. An 11.1 T magnet system was used to image infusion of Gd-DTPA labeled albumin (Gd-albumin) into the hydrogel. By using data from preliminary scans, Gd-albumin distribution was determined from the signal intensity of the MR images. As a validation test, MR-derived concentration profiles were found comparable to both results measured directly using quantitative optical imaging and results from a computational transport model in porous media. In future studies, the developed methodology will be used to quantitatively monitor the distribution of Gd-tracer following infusion directly into tissues. PMID:18583082

  6. Agarose hydrogel biomimetic mineralization model for the regeneration of enamel prismlike tissue.

    PubMed

    Cao, Ying; Mei, May Lei; Li, Quan-Li; Lo, Edward Chin Man; Chu, Chun Hung

    2014-01-08

    Laboratory studies have demonstrated that enamel-like mineralized tissue can be regenerated and used to repair enamel loss. This has implications for the management of noncarious tooth loss resulting from dental erosion, attrition, and abrasion. In this study, we designed a hydrogel biomimetic mineralization model for the regeneration of enamel-like mineralized tissue with a prismatic structure. The mineralized tissue, which was generated by the model on an etched enamel surface in the presence of 500 ppm fluoride, was analyzed with scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and the nanoindentation hardness test. The generated tissue had enamel prismlike layers containing well-defined hexagonal hydroxyapatite crystals. The modulus of elasticity and the nanohardness of the regenerated enamel prismlike tissue were similar to those of natural enamel. Thus, the regeneration of enamel using this hydrogel biomimetic mineralization model is a promising approach for the management of enamel loss.

  7. Anti-bacterial and anti-inflammatory pH-responsive tannic acid-carboxylated agarose composite hydrogels for wound healing.

    PubMed

    Ninan, Neethu; Forget, Aurélien; Shastri, V Prasad; Voelcker, Nicolas H; Blencowe, Anton

    2016-10-05

    pH-sensitive hydrogels play an important role in controlled drug release applications and have the potential to impact the management of wounds. In this study, we report the fabrication of novel carboxylated agarose/tannic acid hydrogel scaffolds cross-linked with zinc ions for the pH-controlled release of tannic acid. The resulting hydrogels exhibited negligible release of tannic acid at neutral and alkaline pH and sustained release at acidic pH, where they also displayed maximum swelling. The hydrogels also displayed favourable anti-bacterial and anti-inflammatory properties, and a lack of cytotoxicity towards 3T3 fibroblast cell lines. In simulated wound assays, significantly greater cell migration and proliferation was observed for cells exposed to tannic acid hydrogel extracts. In addition, the tannic acid hydrogels were able to suppress NO production in stimulated human macrophages in a concentration-dependent manner, indicating effective anti-inflammatory activity. Taken together, the cytocompatibility, anti-bacterial and anti-inflammatory characteristics of these novel pH-sensitive hydrogels make them promising candidates for wound dressings.

  8. Microneedle assisted micro-particle delivery from gene guns: experiments using skin-mimicking agarose gel.

    PubMed

    Zhang, Dongwei; Das, Diganta B; Rielly, Chris D

    2014-02-01

    A set of laboratory experiments has been carried out to determine if micro-needles (MNs) can enhance penetration depths of high-speed micro-particles delivered by a type of gene gun. The micro-particles were fired into a model target material, agarose gel, which was prepared to mimic the viscoelastic properties of porcine skin. The agarose gel was chosen as a model target as it can be prepared as a homogeneous and transparent medium with controllable and reproducible properties allowing accurate determination of penetration depths. Insertions of various MNs into gels have been analysed to show that the length of the holes increases with an increase in the agarose concentration. The penetration depths of micro-particle were analysed in relation to a number of variables, namely the operating pressure, the particle size, the size of a mesh used for particle separation and the MN dimensions. The results suggest that the penetration depths increase with an increase of the mesh pore size, because of the passage of large agglomerates. As these particles seem to damage the target surface, then smaller mesh sizes are recommended; here, a mesh with a pore size of 178 μm was used for the majority of the experiments. The operating pressure provides a positive effect on the penetration depth, that is it increases as pressure is increased. Further, as expected, an application of MNs maximises the micro-particle penetration depth. The maximum penetration depth is found to increase as the lengths of the MNs increase, for example it is found to be 1272 ± 42, 1009 ± 49 and 656 ± 85 μm at 4.5 bar pressure for spherical micro-particles of 18 ± 7 μm diameter when we used MNs of 1500, 1200 and 750 μm length, respectively.

  9. Hydroxyapatite formed on/in agarose gel induces activation of blood coagulation and platelets aggregation.

    PubMed

    Arimura, Shin-ichiro; Kawahara, Ko-ichi; Biswas, Kamal Krishna; Abeyama, Kazuhiro; Tabata, Masashi; Shimoda, Toru; Ogomi, Daisuke; Matsusaki, Michiya; Kato, Shinya; Ito, Takashi; Sugihara, Kazumasa; Akashi, Mitsuru; Hashiguchi, Teruto; Maruyama, Ikuro

    2007-05-01

    We reported earlier that hydroxyapatite (HA) formed on/in agarose gels (HA/agarose) produced by alternate soaking process is a bone-filling material possessing osteoconductive and hemostatic effects. This process could allow us to make bone-like apatite that was formed on/in organic polymer hydrogel matrices. Here, we investigated the mechanism of hemostasis induced by HA/agarose and found that HA/agarose, but not agarose or HA powder, significantly shortened activated partial thromboplastin time (APTT). While HA/agarose did not show significant platelet aggregation, it markedly enhanced adenosine diphosphate (ADP)-induced platelet aggregation. Moreover, Western blot analysis revealed selective adsorption of vitronectin onto HA/agarose. We also observed marked differences between HA powder and HA/agarose in their XRD patterns. The crystallinity of HA powder was much higher compared to that of HA/agarose. Furthermore, 50-100 nm of tube-form aggregations was observed in HA powder on the other hand 100-200 nm of particles was observed in HA/agarose by SEM observation. Thus 100-200 nm of low crystallized particles on the surface structure of HA/agarose may play an important role in hemostasis. Our results demonstrated a crucial role of HA/agarose in the mechanism of hemostasis and suggested a potential role for HA/agarose as a bone-grafting material.

  10. Novel Fabrication Strategies for Multifunctional Hydrogel Particles

    NASA Astrophysics Data System (ADS)

    Lewis, Chrisitna L.

    2011-12-01

    -diacrylate concentration effects hybridization and target DNA penetration depth. Additionally, the effects of probe DNA and photoinitiator concentration on target DNA hybridization and particle formation were examined. Finally, sequence-specificity and responsiveness down to single nanomolar concentrations was determined. The results demonstrate a simple, robust, and scalable batch procedure for manufacturing highly uniform hybridization assay particles in a well-controlled manner. Additionally, this work illustrates a novel batch fabrication technique, which offers advantages over the traditional, continuous (microfluidic) fabrication methods for DNA-conjugated microparticles. Together, these results identify multiple simple and well-controlled fabrication strategies for PEG-based, functional hydrogel microparticles, which contribute to the advancement and application of functional biomaterials.

  11. Particle-wall tribology of slippery hydrogel particle suspensions.

    PubMed

    Shewan, Heather M; Stokes, Jason R; Cloitre, Michel

    2017-03-08

    Slip is an important phenomenon that occurs during the flow of yield stress fluids like soft materials and pastes. Densely packed suspensions of hydrogel microparticles are used to show that slip is governed by the tribological interactions occurring between the samples and shearing surfaces. Both attractive/repulsive interactions between the dispersed particles and surface, as well as the viscoelasticity of the suspension, are found to play key roles in slip occurring within rheometric flows. We specifically discover that for two completely different sets of microgels, the sliding stress at which slip occurs scales with both the modulus of the particles and the bulk suspension modulus. This suggests that hysteresis losses within the viscoelastic particles contribute to friction forces and thus slip at the particle-surface tribo-contact. It is also found that slip during large amplitude oscillatory shear and steady shear flows share the same generic features.

  12. A Novel Aerosol Method for the Production of Hydrogel Particles

    PubMed Central

    Guzman-Villanueva, Diana; Smyth, Hugh D. C.; Herrera-Ruiz, Dea; El-Sherbiny, Ibrahim M.

    2012-01-01

    A novel method of generating hydrogel particles for various applications including drug delivery purposes was developed. This method is based on the production of hydrogel particles from sprayed polymeric nano/microdroplets obtained by a nebulization process that is immediately followed by gelation in a crosslinking fluid. In this study, particle synthesis parameters such as type of nebulizer, type of crosslinker, air pressure, and polymer concentration were investigated for their impact on the mean particle size, swelling behavior, and morphology of the developed particles. Spherical alginate-based hydrogel particles with a mean particle size in the range from 842 to 886 nm were obtained. Using statistical analysis of the factorial design of experiment it was found that the main factors influencing the size and swelling values of the particles are the alginate concentration and the air pressure. Thus, it was demonstrated that the method described in the current study is promising for the generation of hydrogel particles and it constitutes a relatively simple and low-cost system. PMID:23687513

  13. Homogeneous deposition of particles on hydrogels by absorption

    NASA Astrophysics Data System (ADS)

    Boulogne, François; Ingremeau, François; Dervaux, Julien; Limat, Laurent; Stone, Howard

    2016-11-01

    A drying drop containing solid particles, such as coffee, leaves a ring stain resulting from the accumulation of the particles near a contact line. In many industrial applications such as printing, coating or biological microtechnologies, these inhomogeneities must be avoided. To suppress the coffee stain effect, different strategies have been developed.In the present work, we propose to substitute the drying by absorption in hydrogels to extract the solvent of a colloidal drop. We study the deposition mechanisms of micrometer-sized particles on the surface of swelling hydrogels. To the best of our knowledge, we show for the first time that the particle deposition on these gels is homogeneous. Using fluorescence microscopy coupled with particle tracking techniques, we record the flow field inside the droplet and analyze the particle deposition mechanism. We rationalize our findings with a theoretical model for the absorption and the particle deposition dynamics that enables the measurement of the diffusion coefficient in the gels.

  14. Manufacturing of agarose-based chromatographic adsorbents--effect of ionic strength and cooling conditions on particle structure and mechanical strength.

    PubMed

    Ioannidis, Nicolas; Bowen, James; Pacek, Andrzej; Zhang, Zhibing

    2012-02-01

    The effect of ionic strength of agarose solution and quenching temperature of the emulsion on the structure and mechanical strength of agarose-based chromatographic adsorbents was investigated. Solutions of agarose containing different amounts of NaCl were emulsified at elevated temperature in mineral oil using a high-shear mixer. The hot emulsion was quenched at different temperatures leading to the gelation of agarose and formation of soft particles. Analysis of Atomic Force Microscopy (AFM) images of particle surfaces shows that pore size of particles increases with ionic strength and/or high quenching temperature. Additionally it has been found that the compressive strength of particles measured by micromanipulation also increases with ionic strength of the emulsion and/or high quenching temperature but these two parameters have no significant effect on the resulting particle size and particle size distribution. Results from both characterization methods were compared with Sepharose 4B, a commercial agarose-based adsorbent. This is the first report examining the effect of ionic strength and cooling conditions on the microstructure of micron-sized agarose beads for bioseparation.

  15. A study of saltation process using hydrogel particles

    NASA Astrophysics Data System (ADS)

    Wang, Stella; Zhao, Yuchen; Behringer, Robert

    2016-11-01

    Saltation is a natural process for sediments transported by flow, and occurs in situations such as wind-driven sand dunes in the dessert, and rivers or streams where fluid motion drives gravel. The onset of grain motions is set by the strength of the shear, and grains exhibit rolling, successive jumping where they are lifted by the turbulence. It is an open issue as to how the grain size affects saltation transport, particle velocities and mass fluxes, etc [1]., and also how the inelastic collision between grains affects saltation. Here, we describe a new saltation experiment using hydrogel particles immersed in uniform flow of water. Because the refraction indexes of particles and the fluid are nearly matched, the hydrogel particles can be imaged by a parallel light source, resulting in overlapping dark rings that not only reflect lateral positions, but also depths in one 2D image at one time. Mono-disperse particles are used and their size is adjusted by changing salt concentrations in the fluid. Preliminary results show that the softness of hydrogel particles leads to relatively large collisional losses. This property allows us to explore the phase diagram of saltation transport in the in-elastic collision regime. NSF-DMR-1206351 and the William M. Keck Foundation.

  16. Optimization of encoded hydrogel particles for nucleic acid quantification.

    PubMed

    Pregibon, Daniel C; Doyle, Patrick S

    2009-06-15

    The accurate quantification of nucleic acids is of utmost importance for clinical diagnostics, drug discovery, and basic science research. These applications require the concurrent measurement of multiple targets while demanding high-throughput analysis, high sensitivity, specificity between closely related targets, and a wide dynamic range. In attempt to create a technology that can simultaneously meet these demands, we recently developed a method of multiplexed analysis using encoded hydrogel particles. Here, we demonstrate tuning of hydrogel porosity with semi-interpenetrating networks of poly(ethylene glycol), develop a quantitative model to understand hybridization kinetics, and use the findings from these studies to enhance particle design for nucleic acid detection. With an optimized particle design and efficient fluorescent labeling scheme, we demonstrate subattomole sensitivity and single-nucleotide specificity for small RNA targets.

  17. Hydrolysis activities of the particle of agarose-Ce4+ complex for compounds containing phosphodiester or peptide bonds

    NASA Astrophysics Data System (ADS)

    Yu, Lina; Wang, Dongfeng; Su, Lin; Luo, Yi; Sun, Liping; Xue, Changhu

    2005-07-01

    Hydrolysis activities of PACC (particle of agarose-Ce4+ complex, newly made through double emulsification) for compounds containing phosphodiester or peptide bonds were studied. The results showed that PACC could hydrolyze organophosphorous pesticides not only in water but also in vegetable juice or tea extract. Hydrolysis rates of methamidophos, omethoate and chlorpyrifos in water are 32.39%, 27.12% and 46.62% respectively, those of chlorpyrifos and methamidophos in mung sprout juice 38.28% and 35.45% respectively, and that of chlorpyrifos in tea extract 59.76%. Hydrolysis rates of BSA (bovine serum albumin) in water and protein in tea extract by PACC increase by 54.30% and 86.46% respectively as compared with the control.

  18. Development of CMC hydrogels loaded with silver nano-particles for medical applications.

    PubMed

    Hebeish, Ali; Hashem, M; El-Hady, M M Abd; Sharaf, S

    2013-01-30

    Innovative CMC-based hydrogels with great potentials for usage in medical area were principally synthesized as per two strategies .The first involved reaction of epichlorohydrin in alkaline medium containing silver nitrate to yield silver nano-particles (AgNPs)-loaded CMC hydrogel. While CMC acted as stabilizing for AgNPs, trisodium citrate was added to the reaction medium to assist CMC in establishing reduction of Ag(+) to AgNPs. The second strategy entailed preparation of CMC hydrogel which assists the in situ preparation of AgNPs under the same conditions. In both strategies, factors affecting the characterization of AgNPs-loaded CMC hydrogels were studied. Analysis and characterization of the so obtained hydrogels were performed through monitoring swelling behavior, FTIR spectroscopy, SEM, EDX, UV-vis spectrophotometer and TEM. Antimicrobial activity of the hydrogels was examined and mechanisms involved in their synthesis were reported.

  19. Using dissipative particle dynamics to model micromechanics of responsive hydrogels

    NASA Astrophysics Data System (ADS)

    Alexeev, Alexander; Nikolov, Svetoslav; Fernandez de Las Nieves, Alberto

    2015-03-01

    The ability of responsive hydrogels to undergo complex and reversible shape transformations in response to external stimuli such as temperature, magnetic/electric fields, pH levels, and light intensity has made them the material of choice for tissue scaffolding, drug delivery, bio-adhesive, bio-sensing, and micro-sorting applications. The complex micromechanics and kinetics of these responsive networks however, currently hinders developments in the aforementioned areas. In order to better understand the mechanical properties of these systems and how they change during the volume transition we have developed a dissipative particle dynamics (DPD) model for responsive polymer networks. We use this model to examine the impact of the Flory-Huggins parameter on the bulk and shear moduli. In this fashion we evaluate how environmental factors can affect the micromechanical properties of these networks. Support from NSF CAREER Award (DMR-1255288) is gratefully acknowledged.

  20. Degradation potential of protocatechuate 3,4-dioxygenase from crude extract of Stenotrophomonas maltophilia strain KB2 immobilized in calcium alginate hydrogels and on glyoxyl agarose.

    PubMed

    Guzik, Urszula; Hupert-Kocurek, Katarzyna; Krysiak, Marta; Wojcieszyńska, Danuta

    2014-01-01

    Microbial intradiol dioxygenases have been shown to have a great potential for bioremediation; however, their structure is sensitive to various environmental and chemical agents. Immobilization techniques allow for the improvement of enzyme properties. This is the first report on use of glyoxyl agarose and calcium alginate as matrixes for the immobilization of protocatechuate 3,4-dioxygenase. Multipoint attachment of the enzyme to the carrier caused maintenance of its initial activity during the 21 days. Immobilization of dioxygenase in calcium alginate or on glyoxyl agarose resulted in decrease in the optimum temperature by 5 °C and 10 °C, respectively. Entrapment of the enzyme in alginate gel shifted its optimum pH towards high-alkaline pH while immobilization of the enzyme on glyoxyl agarose did not influence pH profile of the enzyme. Protocatechuate 3,4-dioygenase immobilized in calcium alginate showed increased activity towards 2,5-dihydroxybenzoate, caffeic acid, 2,3-dihydroxybenzoate, and 3,5-dihydroxybenzoate. Slightly lower activity of the enzyme was observed after its immobilization on glyoxyl agarose. Entrapment of the enzyme in alginate gel protected it against chelators and aliphatic alcohols while its immobilization on glyoxyl agarose enhanced enzyme resistance to inactivation by metal ions.

  1. Tuning the Receding Contact Angle on Hydrogels by Addition of Particles.

    PubMed

    Boulogne, François; Ingremeau, François; Limat, Laurent; Stone, Howard A

    2016-06-07

    Control of the swelling, chemical functionalization, and adhesivity of hydrogels are finding new applications in a wide range of material systems. We investigate experimentally the effect of adsorbed particles on hydrogels on the depinning of contact lines. In our experiments, a water drop containing polystyrene microspheres is deposited on a swelling hydrogel, which leads to the drop absorption and particle deposition. Two regimes are observed: a decreasing drop height with a pinned contact line followed by a receding contact line. We show that increasing the particles concentration increases the duration of the first regime and significantly decreases the total absorption time. The adsorbed particles increase the pinning force at the contact line. Finally, we develop a method to measure the receding contact angle with the consideration of the hydrogel swelling.

  2. The Effect of Particle Size on the Biodistribution of Low-modulus Hydrogel PRINT Particles

    PubMed Central

    Merkel, Timothy J.; Chen, Kai; Jones, Stephen W.; Pandya, Ashish A.; Tian, Shaomin; Napier, Mary E.; Zamboni, William E.; DeSimone, Joseph M.

    2012-01-01

    There is a growing recognition that the deformability of particles used for drug delivery plays a significant role on their biodistribution and circulation profile. Understanding these effects would provide a crucial tool for the rational design of drug delivery systems. While particles resembling red blood cells (RBCs) in size, shape and deformability have extended circulation times and altered biodistribution profiles compared to rigid, but otherwise similar particles, the in vivo behavior of such highly deformable particles of varied size has not been explored. We report the fabrication of a series of discoid, monodisperse, low-modulus hydrogel particles with diameters ranging from 0.8 to 8.9 μm, spanning sizes smaller than and larger than RBCs. We injected these particles into healthy mice, and tracked their concentration in the blood and their distribution into major organs. These deformable particles all demonstrated some hold up in filtration tissues like the lungs and spleen, followed by release back into the circulation, characterized by decreases in particles in these tissues with concomitant increases in particle concentration in blood. Particles similar to red blood cells in size demonstrated longer circulation times, suggesting that this size and shape of deformable particle is uniquely suited to avoid clearance. PMID:22705460

  3. Soft matter strategies for controlling food texture: formation of hydrogel particles by biopolymer complex coacervation

    NASA Astrophysics Data System (ADS)

    Wu, Bi-cheng; Degner, Brian; McClements, David Julian

    2014-11-01

    Soft matter physics principles can be used to address important problems in the food industry. Starch granules are widely used in foods to create desirable textural attributes, but high levels of digestible starch may pose a risk of diabetes. Consequently, there is a need to find healthier replacements for starch granules. The objective of this research was to create hydrogel particles from protein and dietary fiber with similar dimensions and functional attributes as starch granules. Hydrogel particles were formed by mixing gelatin (0.5 wt%) with pectin (0 to 0.2 wt%) at pH values above the isoelectric point of the gelatin (pH 9, 30 °C). When the pH was adjusted to pH 5, the biopolymer mixture spontaneously formed micron-sized particles due to electrostatic attraction of cationic gelatin with anionic pectin through complex coacervation. Differential interference contrast (DIC) microscopy showed that the hydrogel particles were translucent and spheroid, and that their dimensions were determined by pectin concentration. At 0.01 wt% pectin, hydrogel particles with similar dimensions to swollen starch granules (D3,2 ≈ 23 µm) were formed. The resulting hydrogel suspensions had similar appearances to starch pastes and could be made to have similar textural attributes (yield stress and shear viscosity) by adjusting the effective hydrogel particle concentration. These hydrogel particles may therefore be used to improve the texture of reduced-calorie foods and thereby help tackle obesity and diabetes.

  4. Rain water transport and storage in a model sandy soil with hydrogel particle additives.

    PubMed

    Wei, Y; Durian, D J

    2014-10-01

    We study rain water infiltration and drainage in a dry model sandy soil with superabsorbent hydrogel particle additives by measuring the mass of retained water for non-ponding rainfall using a self-built 3D laboratory set-up. In the pure model sandy soil, the retained water curve measurements indicate that instead of a stable horizontal wetting front that grows downward uniformly, a narrow fingered flow forms under the top layer of water-saturated soil. This rain water channelization phenomenon not only further reduces the available rain water in the plant root zone, but also affects the efficiency of soil additives, such as superabsorbent hydrogel particles. Our studies show that the shape of the retained water curve for a soil packing with hydrogel particle additives strongly depends on the location and the concentration of the hydrogel particles in the model sandy soil. By carefully choosing the particle size and distribution methods, we may use the swollen hydrogel particles to modify the soil pore structure, to clog or extend the water channels in sandy soils, or to build water reservoirs in the plant root zone.

  5. Modulating the morphology of hydrogel particles by thermal annealing: mixed biopolymer electrostatic complexes

    NASA Astrophysics Data System (ADS)

    Wu, Bi-cheng; McClements, David Julian

    2015-11-01

    Biopolymer hydrogel particles formed by electrostatic complexation of proteins and polysaccharides have various applications within the food and other industries, including as delivery systems for bioactive compounds, as texture modifiers, and as fat replacers. The functional attributes of these electrostatic complexes are strongly influenced by their morphology, which is determined by the molecular interactions between the biopolymer molecules. In this study, electrostatic complexes were formed using an amphoteric protein (gelatin) and an anionic polysaccharide (pectin). Gelatin undergoes a helix-to-coil transition when heated above a critical temperature, which impacts its molecular interactions and hydrogel formation. The aim of this research was to study the influence of thermal annealing on the properties of hydrogel particles formed by electrostatic complexation of gelatin and pectin. Hydrogel particles were fabricated by mixing 0.5 wt% gelatin and 0.01 wt% pectin at pH 10 (where both were negatively charged) at various temperatures, followed by acidification to pH 5 (where they have opposite charges) with controlled acidification and stirring. The gelation ({{T}\\text{g}} ) and melting temperature ({{T}\\text{m}} ) of the electrostatic complexes were measuring using a small amplitude oscillation test: {{T}\\text{g}}=26.3 °C and {{T}\\text{m}}=32.3 °C. Three annealing temperatures (5, 30 and 50 °C) corresponding to different regimes (T<{{T}\\text{g}} , {{T}\\text{g}}\\text{m}} , and T>{{T}\\text{m}} ) were selected to control the configuration of the gelatin chain. The effects of formation temperature, annealing temperature, and incubation time on the morphology of the hydrogel particles were characterized by turbidity, static light scattering, and microscopy. The results of this study will facilitate the rational design of hydrogel particles with specific particle dimensions and morphologies, which has important implications for tailoring their

  6. Particle Deformation and Concentration Polarization in Electroosmotic Transport of Hydrogels through Pores

    SciTech Connect

    Vlassiouk, Ivan V

    2013-01-01

    In this article, we report detection of deformable, hydrogel particles by the resistive-pulse technique using single pores in a polymer film. The hydrogels pass through the pores by electroosmosis and cause formation of a characteristic shape of resistive pulses indicating the particles underwent dehydration and deformation. These effects were explained via a non-homogeneous pressure distribution along the pore axis modeled by the coupled Poisson-Nernst-Planck and Navier Stokes equations. The local pressure drops are induced by the electroosmotic fluid flow. Our experiments also revealed the importance of concentration polarization in the detection of hydrogels. Due to the negative charges as well as branched, low density structure of the hydrogel particles, concentration of ions in the particles is significantly higher than in the bulk. As a result, when electric field is applied across the membrane, a depletion zone can be created in the vicinity of the particle observed as a transient drop of the current. Our experiments using pores with openings between 200 and 1600 nm indicated the concentration polarization dominated the hydrogels detection for pores wider than 450 nm. The results are of importance for all studies that involve transport of molecules, particles and cells through pores with charged walls. The developed inhomogeneous pressure distribution can potentially influence the shape of the transported species. The concentration polarization changes the interpretation of the resistive pulses; the observed current change does not necessarily reflect only the particle size but also the size of the depletion zone that is formed in the particle vicinity.

  7. Agarose gel electrophoresis.

    PubMed

    Smith, D R

    1993-01-01

    After digestion of DNA with a restriction enzyme (Chapter 50), it is usually necessary, for both preparative and analytical purposes, to separate and visualize the products. In most cases, where the products are between 200 and 20,000 bp long, this is achieved by agarose gel electrophoresis. Agarose is a linear polymer that is extracted from seaweed and sold as a white powder. The powder is melted in buffer and allowed to cool, whereby the agarose forms a gel by hydrogen bonding. The hardened matrix contains pores, the size of which depends on the concentration of agarose. The concentration of agarose is referred to as a percentage of agarose to volume of buffer (w/v), and agarose gels are normally in the range of 0.3 to 3%. Many different apparatus arrangements have been devised to run agarose gels; for example, they can be run horizontally or vertically, and the current can be conducted by wicks or the buffer solution. However, today, the "submarine" gel system is almost universally used. In this method, the agarose gel is formed on a supporting plate, and then the plate is submerged into a tank containing a suitable electrophoresis buffer. Wells are preformed in the agarose gel with the aid of a "comb" that is inserted into the cooling agarose before the agarose has gelled. Into these wells are loaded the sample to be analyzed, which has been mixed with a dense solution (a loading buffer) to ensure that the sample sinks into the wells.

  8. Swellable ciprofloxacin-loaded nano-in-micro hydrogel particles for local lung drug delivery.

    PubMed

    Du, Ju; El-Sherbiny, Ibrahim M; Smyth, Hugh D

    2014-12-01

    Incorporation of drug-loaded nanoparticles into swellable and respirable microparticles is a promising strategy to avoid rapid clearance from the lung and achieve sustained drug release. In this investigation, a copolymer of polyethylene glycol grafted onto phthaloyl chitosan (PEG-g-PHCs) was synthesized and then self-assembled with ciprofloxacin to form drug-loaded nanoparticles. The nanoparticles and free drug were encapsulated into respirable and swellable alginate micro hydrogel particles and assessed as a novel system for sustained pulmonary drug delivery. Particle size, morphology, dynamic swelling profile, and in vitro drug release were investigated. Results showed that drug-loaded nanoparticles with size of 218 nm were entrapped into 3.9-μm micro hydrogel particles. The dry nano-in-micro hydrogel particles exhibited a rapid initial swelling within 2 min and showed sustained drug release. Preliminary in vivo pharmacokinetic studies were performed with formulations delivered to rats by intratracheal insufflation. Ciprofloxacin concentrations in plasma and in lung tissue and lavage were measured up to 7 h. The swellable particles showed lower ciprofloxacin levels in plasma than the controlled group (a mixture of lactose with micronized ciprofloxacin), while swellable particles achieved higher concentrations in lung tissue and lavage, indicating the swellable particles could be used for controlling drug release and prolonging lung drug concentrations.

  9. Negative dielectrophoretic patterning with colloidal particles and encapsulation into a hydrogel.

    PubMed

    Suzuki, Masato; Yasukawa, Tomoyuki; Shiku, Hitoshi; Matsue, Tomokazu

    2007-03-27

    Microparticle patterns have been fabricated on a nonconductive glass substrate and a conductive indium tin oxide (ITO) substrate using negative dielectrophoresis (n-DEP). The patterned microparticles on the substrate were immobilized by covalent bonding or embedded into polymer sheets or strings. The patterning device consisted of an ITO interdigitated microband array (IDA) electrode as the template, a glass or ITO substrate, and a polyester film (10-microm thickness) as the spacer. A suspension of 2-microm-diameter polystyrene particles was introduced into the device between the upper IDA and the bottom glass or ITO support. An ac electrical signal (typically 20 Vpp, 3 MHz) was then applied to the IDA, resulting in the formation of line patterns with low electric field gradient regions on the bottom support. When the glass substrate was used as the bottom support, the particles aligned under the microband electrodes of the IDA within 5 s because the aligned areas on the support were regions with the weakest electric field; however, for the ITO support, the particles were directed to the regions under the electrode gap and aligned on the support because these regions had the weakest electric field. The width of the particle lines could be roughly controlled by regulating the initial concentration of the suspended particles. The particles forming the line and grid patterns with single-particle widths were immobilized by using a cross-linking reaction between the amino groups on the aligned particles and N-hydroxysuccinimide-activated ester on the glass substrate activated by succinimidyl 4-(p-maleimidophenyl)-butyrate (SMPB). The patterned particles were also embedded in a photoreactive hydrogel polymer. A prepolymer solution of poly(ethylene glycol) diacrylate (PEG-DA) was used as the suspension medium to maintain the particle patterns in the polymerized hydrogel sheet and string following photopolymerization. The hydrogel sheets with particle patterns were

  10. Conducting polymer electrodes printed on hydrogel.

    PubMed

    Sekine, Soichiro; Ido, Yuichiro; Miyake, Takeo; Nagamine, Kuniaki; Nishizawa, Matsuhiko

    2010-09-29

    We report herein the micropatterning of poly(3,4-ethylenedioxythiophene) (PEDOT) on a hydrogel, agarose, to provide a fully organic, moist, and flexible electrode. The PEDOT/agarose electrodes were prepared through two electrochemical processes: electropolymerization of PEDOT into the hydrogel and electrochemical-actuation-assisted peeling. We also present a typical application of the PEDOT/agarose electrode to the cultivation of contractile myotubes.

  11. Friction Reduction Using Self-Assembled Hydrogels

    NASA Astrophysics Data System (ADS)

    Mackel, Michael J.; Kornfield, Julia A.

    2007-03-01

    Friction of agarose-based hydrogels against bare glass is examined as a function of added linear polyelectrolyte using a stress rheometer to measure the angular velocity of a clean glass plate against the hydrogel surface as a function of applied torque and normal force. Incorporating linear dextran sulfate into 2 weight percent agarose hydrogel reduces friction on the hydrogel surface. The reduction of friction is a nonmonotonic function of dextran sulfate concentration: a 2 percent doping of dextran sulfate shows the minimum friction. Lubricity enhancement on the agarose doped with 2 percent dextran sulfate occurs at all normal forces examined (0.5, 1, 1.5, and 2 N) and is more pronounced at larger angular velocities. Rheological studies of agarose hydrogels doped with dextran sulfate suggest that the dextran sulfate does not interfere with the porous structure of the hydrogel when present in concentrations of 2 weight percent or less.

  12. In vitro apatite forming ability of type I collagen hydrogels containing bioactive glass and silica sol-gel particles.

    PubMed

    Eglin, David; Maalheem, Sonia; Livage, Jacques; Coradin, Thibaud

    2006-02-01

    Type I collagen hydrogel containing bioactive glass (CaO-P2O5-SiO2) and silica sol-gel micrometric particles were prepared and their in vitroapatite-forming ability in simulated body fluid assessed. X-ray diffraction and scanning electron microscopy analysis showed that bioactive glass particles entrapment in collagen matrix did not inhibit calcium phosphate formation and induced morphology variations on the crystalline phase precipitated on the hydrogel surface. The silica--collagen hydrogel composite precipitated calcium phosphate whereas silica particles and collagen hydrogel alone did not, indicating a possible synergetic effect between collagen and silica on the apatite-forming ability. Mechanisms of calcium phosphate precipitation and its relevance to biomaterial development are discussed.

  13. Characterization of hydrogel microstructure using laser tweezers particle tracking and confocal reflection imaging

    NASA Astrophysics Data System (ADS)

    Kotlarchyk, M. A.; Botvinick, E. L.; Putnam, A. J.

    2010-05-01

    Hydrogels are commonly used as extracellular matrix mimetics for applications in tissue engineering and increasingly as cell culture platforms with which to study the influence of biophysical and biochemical cues on cell function in 3D. In recent years, a significant number of studies have focused on linking substrate mechanical properties to cell function using standard methodologies to characterize the bulk mechanical properties of the hydrogel substrates. However, current understanding of the correlations between the microstructural mechanical properties of hydrogels and cell function in 3D is poor, in part because of a lack of appropriate techniques. Here we have utilized a laser tracking system, based on passive optical microrheology instrumentation, to characterize the microstructure of viscoelastic fibrin clots. Trajectories and mean square displacements were observed as bioinert PEGylated (PEG: polyethylene glycol) microspheres (1, 2 or 4.7 µm in diameter) diffused within confined pores created by the protein phase of fibrin hydrogels. Complementary confocal reflection imaging revealed microstructures comprised of a highly heterogeneous fibrin network with a wide range of pore sizes. As the protein concentration of fibrin gels was increased, our quantitative laser tracking measurements showed a corresponding decrease in particle mean square displacements with greater resolution and sensitivity than conventional imaging techniques. This platform-independent method will enable a more complete understanding of how changes in substrate mechanical properties simultaneously influence other microenvironmental parameters in 3D cultures.

  14. Characterization of hydrogel microstructure using laser tweezers particle tracking and confocal reflection imaging.

    PubMed

    Kotlarchyk, M A; Botvinick, E L; Putnam, A J

    2010-05-19

    Hydrogels are commonly used as extracellular matrix mimetics for applications in tissue engineering and increasingly as cell culture platforms with which to study the influence of biophysical and biochemical cues on cell function in 3D. In recent years, a significant number of studies have focused on linking substrate mechanical properties to cell function using standard methodologies to characterize the bulk mechanical properties of the hydrogel substrates. However, current understanding of the correlations between the microstructural mechanical properties of hydrogels and cell function in 3D is poor, in part because of a lack of appropriate techniques. Here we have utilized a laser tracking system, based on passive optical microrheology instrumentation, to characterize the microstructure of viscoelastic fibrin clots. Trajectories and mean square displacements were observed as bioinert PEGylated (PEG: polyethylene glycol) microspheres (1, 2 or 4.7 μm in diameter) diffused within confined pores created by the protein phase of fibrin hydrogels. Complementary confocal reflection imaging revealed microstructures comprised of a highly heterogeneous fibrin network with a wide range of pore sizes. As the protein concentration of fibrin gels was increased, our quantitative laser tracking measurements showed a corresponding decrease in particle mean square displacements with greater resolution and sensitivity than conventional imaging techniques. This platform-independent method will enable a more complete understanding of how changes in substrate mechanical properties simultaneously influence other microenvironmental parameters in 3D cultures.

  15. A functional agarose-hydroxyapatite scaffold for osteochondral interface regeneration

    PubMed Central

    Khanarian, Nora T.; Haney, Nora M.; Burga, Rachel A.; Lu, Helen H.

    2013-01-01

    Regeneration of the osteochondral interface is critical for integrative and functional cartilage repair. This study focuses on the design and optimization of a hydrogel-ceramic composite scaffold of agarose and hydroxyapatite (HA) for calcified cartilage formation. The first study objective was to compare the effects of HA on non-hypertrophic and hypertrophic chondrocytes cultured in the composite scaffold. Specifically, cell growth, biosynthesis, hypertrophy, and scaffold mechanical properties were evaluated. Next, the ceramic phase of the scaffold was optimized in terms of particle size (200 nm vs. 25 µm) and dose (0–6 w/v%). It was observed that while deep zone chondrocyte (DZC) biosynthesis and hypertrophy remained unaffected, hypertrophic chondrocytes measured higher matrix deposition and mineralization potential with the addition of HA. Most importantly, higher matrix content translated into significant increases in both compressive and shear mechanical properties. While cell hypertrophy was independent of ceramic size, matrix deposition was higher only with the addition of micron-sized ceramic particles. In addition, the highest matrix content, mechanical properties and mineralization potential were found in scaffolds with 3% micro-HA, which approximates both the mineral aggregate size and content of the native interface. These results demonstrate that the biomimetic hydrogel-ceramic composite is optimal for calcified cartilage formation and is a promising design strategy for osteochondral interface regeneration. PMID:22531222

  16. Influence of clay particles on microfluidic-based preparation of hydrogel composite microsphere

    NASA Astrophysics Data System (ADS)

    Hong, Joung Sook

    2016-05-01

    For the successful fabrication of a hydrogel composite microsphere, this study aimed to investigate the influence of clay particles on microsphere formation in a microfluidic device which has flow focusing and a 4.5:1 contraction channel. A poly alginic acid solution (2.0 wt.%) with clay particles was used as the dispersed phase to generate drops in an oil medium, which then merged with drops of a CaCl2 solution for gelation. Drop generations were observed with different flow rates and particles types. When the flow rate increased, drop generation was enhanced and drop size decreased by the build-up of more favorable hydrodynamic flow conditions to detach the droplets. The addition of a small amount of particles insignificantly changed the drop generation behavior even though it reduced interfacial tension and increased the viscosity of the solution. Instead, clays particles significantly affected hydro-gelation depending on the hydrophobicity of particles, which produced further heterogeneity in the shape and size of microsphere.

  17. Microscale mechanisms of agarose-induced disruption of collagen remodeling.

    PubMed

    Ulrich, Theresa A; Lee, Tae Geol; Shon, Hyun Kyong; Moon, Dae Won; Kumar, Sanjay

    2011-08-01

    Cells are strongly influenced by the local structure and mechanics of the extracellular matrix (ECM). We recently showed that adding agarose to soft collagen ECMs can mechanically stiffen these hydrogels by two orders of magnitude while limiting 3D cell motility, which we speculated might derive from agarose-mediated inhibition of collagen fiber deformation and remodeling. Here, we directly address this hypothesis by investigating the effects of agarose on cell-collagen interactions at the microscale. Addition of agarose progressively restricts cell spreading, reduces stress fiber and focal adhesion assembly, and inhibits macroscopic gel compaction. While time-of-flight secondary ion mass spectrometry and scanning electron microscopy fail to reveal agarose-induced alterations in collagen ligand presentation, the latter modality shows that agarose strongly impairs cell-directed assembly of large collagen bundles. Agarose-mediated inhibition of cell spreading and cytoarchitecture can be rescued by β-agarase digestion or by covalently crosslinking the matrix with glutaraldehyde. Based on these results, we argue that cell spreading and motility on collagen requires local matrix stiffening, which can be achieved via cell-mediated fiber remodeling or by chemically crosslinking the fibers. These findings provide new mechanistic insights into the regulatory function of agarose and bear general implications for cell adhesion and motility in fibrous ECMs.

  18. Direct Observation of Phase Transition Dynamics in Suspensions of Soft Colloidal Hydrogel Particles

    NASA Astrophysics Data System (ADS)

    Cho, Jae Kyu; Meng, Zhiyong; Lyon, L. Andrew; Breedveld, Victor

    2008-07-01

    Due to the tunability of their softness and volume as a function of temperature, poly(N-isopropylacrylamide) (pNIPAm) hydrogel particles have emerged as a model system for soft colloidal spheres. By introducing AAc as comonomer, one can also tune the particle volume via pH. We report on the phase behavior of these stimuli-responsive colloids as measured with a microdialysis cell. This device, which integrates microfluidics with Particle Tracking Video-microscopy allows for simple and quick investigation of the phase behavior of suspensions the soft colloidal hydrogel as a function of pH as well as its packing density. In particular, we demonstrate the existence of an unusually broad liquid/crystal coexistence region as a function of effective particle volume fraction. Additionally, we reveal that nonequilibrium jammed states can be created in the coexistence region upon sudden large changes of pH. The phase diagram is indicative of complex interparticle interactions with weakly attractive components.

  19. Development of Bioadhesive Chitosan Superporous Hydrogel Composite Particles Based Intestinal Drug Delivery System

    PubMed Central

    Modhia, Ishan; Mehta, Anant; Patel, Rupal; Patel, Chhagan

    2013-01-01

    Bioadhesive superporous hydrogel composite (SPHC) particles were developed for an intestinal delivery of metoprolol succinate and characterized for density, porosity, swelling, morphology, and bioadhesion studies. Chitosan and HPMC were used as bioadhesive and release retardant polymers, respectively. A 32 full factorial design was applied to optimize the concentration of chitosan and HPMC. The drug loaded bioadhesive SPHC particles were filled in capsule, and the capsule was coated with cellulose acetate phthalate and evaluated for drug content, in vitro drug release, and stability studies. To ascertain the drug release kinetics, the drug release profiles were fitted for mathematical models. The prepared system remains bioadhesive up to eight hours in intestine and showed Hixson-Crowell release with anomalous nonfickian type of drug transport. The application of SPHC polymer particles as a biomaterial carrier opens a new insight into bioadhesive drug delivery system and could be a future platform for other molecules for intestinal delivery. PMID:23984380

  20. Oxidative stability of n-3 fatty acids encapsulated in filled hydrogel particles and of pork meat systems containing them.

    PubMed

    Salcedo-Sandoval, Lorena; Cofrades, Susana; Ruiz-Capillas, Claudia; Matalanis, Alison; McClements, D Julian; Decker, Eric A; Jiménez-Colmenero, Francisco

    2015-10-01

    The effect of storage time (2°C, 19 days) and heating (70°C, 30 min) on physical characteristics and oxidative stability of fish oil encapsulated in filled hydrogel particles was determined and compared with a conventional oil-in-water (O/W) emulsion with the same oil content (8.5%). Subsequently they were used to enrich meat systems with n-3 LCPUFAs, and their lipid oxidation was evaluated and compared with two other meat systems: one containing all animal fat and another with fish oil added directly. Filled hydrogel particles were more effective in lowering the oxidation rate than O/W emulsion, even when thermal treatment was applied. Oxidative stability over the storage time was best in the n-3 LCPUFA-enriched meat system containing filled hydrogel particles, in which TBARS levels were up to 62% lower than other systems containing fish oil. Hydrogel particles offer a promising means of controlling lipid oxidation in n-3 LCPUFA-enriched meat products.

  1. Effect of the hydration on the biomechanical properties in a fibrin-agarose tissue-like model.

    PubMed

    Scionti, Giuseppe; Moral, Monica; Toledano, Manuel; Osorio, Raquel; Durán, Juan D G; Alaminos, Miguel; Campos, Antonio; López-López, Modesto T

    2014-08-01

    The effect of hydration on the biomechanical properties of fibrin and fibrin-agarose (FA) tissue-like hydrogels is reported. Native hydrogels with approximately 99.5% of water content and hydrogels with water content reduced until 90% and 80% by means of plastic compression (nanostructuration) were generated. The biomechanical properties of the hydrogels were investigated by tensile, compressive, and shear tests. Experimental results indicate that nanostructuration enhances the biomechanical properties of the hydrogels. This improvement is due to the partial draining of the water that fills the porous network of fibers that the plastic compression generates, which produces a denser material, as confirmed by scanning electron microscopy. Results also indicate that the characteristic compressive and shear parameters increase with agarose concentration, very likely due to the high water holding capacity of agarose, which reduces the compressibility and gives consistency to the hydrogels. However, results of tensile tests indicate a weakening of the hydrogels as agarose concentration increases, which evidences the anisotropic nature of these biomaterials. Interestingly, we found that by adjusting the water and agarose contents it is possible to tune the biomechanical properties of FA hydrogels for a broad range, within which the properties of many native tissues fall.

  2. A new agarose gel model

    SciTech Connect

    Hasenfeld, A.; Pepke, E.; Lim, H.A.; Cantor, C.R.

    1993-12-31

    A new agarose gel model is introduced, which corresponds to what the authors believe agarose gels look like microscopically. While the scientific literature is filled with studies of the microscopic structure of agarose, the fact remains that there is no unambiguous and exact model of its underlying structure. Given this, the authors are left to construct their own model numerically.

  3. Function, structure, and stability of enzymes confined in agarose gels.

    PubMed

    Kunkel, Jeffrey; Asuri, Prashanth

    2014-01-01

    Research over the past few decades has attempted to answer how proteins behave in molecularly confined or crowded environments when compared to dilute buffer solutions. This information is vital to understanding in vivo protein behavior, as the average spacing between macromolecules in the cell cytosol is much smaller than the size of the macromolecules themselves. In our study, we attempt to address this question using three structurally and functionally different model enzymes encapsulated in agarose gels of different porosities. Our studies reveal that under standard buffer conditions, the initial reaction rates of the agarose-encapsulated enzymes are lower than that of the solution phase enzymes. However, the encapsulated enzymes retain a higher percentage of their activity in the presence of denaturants. Moreover, the concentration of agarose used for encapsulation had a significant effect on the enzyme functional stability; enzymes encapsulated in higher percentages of agarose were more stable than the enzymes encapsulated in lower percentages of agarose. Similar results were observed through structural measurements of enzyme denaturation using an 8-anilinonaphthalene-1-sulfonic acid fluorescence assay. Our work demonstrates the utility of hydrogels to study protein behavior in highly confined environments similar to those present in vivo; furthermore, the enhanced stability of gel-encapsulated enzymes may find use in the delivery of therapeutic proteins, as well as the design of novel strategies for biohybrid medical devices.

  4. Chemotaxis: Under Agarose Assay.

    PubMed

    Brazill, Derrick

    2016-01-01

    The unicellular eukaryote Dictyostelium discoideum represents a superb model for examining chemotaxis. Under vegetative conditions, the amoebae are chemotactically responsive to pterins, such as folate. Under starved conditions, they lose their sensitivity to pterins, and become chemotactically responsive to cAMP. As an NIH model system, Dictyostelium offers a variety of advantages in studying chemotaxis, including its conservation of mammalian signaling pathways, its ease of growth, and its genetic tractability. In this chapter, we describe the use of the under agarose chemotaxis assay to identify proteins involved in controlling motility and directional sensing in Dictyostelium discoideum. Given the similarities between Dictyostelium and mammalian cells, this allows us to dissect the conserved pathways involved in eukaryotic chemotaxis.

  5. Microencapsulation of probiotics in hydrogel particles: enhancing Lactococcus lactis subsp. cremoris LM0230 viability using calcium alginate beads.

    PubMed

    Yeung, Timothy W; Arroyo-Maya, Izlia J; McClements, David J; Sela, David A

    2016-04-01

    Probiotics are beneficial microbes often added to food products to enhance the health and wellness of consumers. A major limitation to producing efficacious functional foods containing probiotic cells is their tendency to lose viability during storage and gastrointestinal transit. In this study, the impact of encapsulating probiotics within food-grade hydrogel particles to mitigate sensitivity to environmental stresses was examined. Confocal fluorescence microscopy confirmed that Lactococcus lactis were trapped within calcium alginate beads formed by dripping a probiotic-alginate mixture into a calcium solution. Encapsulation improved the viability of the probiotics during aerobic storage: after seven days, less than a two-log reduction was observed in encapsulated cells stored at room temperature, demonstrating that a high concentration of cells survived relative to non-encapsulated bacteria. These hydrogel beads may have applications for improving the stability and efficacy of probiotics in functional foods.

  6. Facile Use of Cationic Hydrogel Particles for Surface Modification of Planar Substrates Toward Multifunctional Neural Permissive Surfaces: An in Vitro Investigation.

    PubMed

    Morin, Emily A; Tang, Shuangcheng; Rogers, Katie Lou; He, Wei

    2016-03-02

    Synthetic materials such as silicon have been commonly used for neural interfacing applications but are intrinsically noninteractive with neurons. Here, a facile approach has been developed to integrate both chemical and topographical cues to impart neural permissiveness for such materials. The approach simply exploits the basic phenomenon of electrostatically driven adsorption of colloidal particles onto a solid material and applies it to a cationic hydrogel particle system that we have developed recently based on "click" reaction of epoxide and amine. The particle adsorption process can be tuned by varying the adsorption time and the concentration of the original colloidal suspension, both of which directly control the surface densities of the adsorbed hydrogel particles. Using the PC12 cell line and primary cortical neurons derived from chick embryo, we demonstrate that the particle-adsorbed surface readily supports robust cell adhesion and differentiation. Although the extent of neural permissiveness exhibited by such particle-adsorbed surface was comparable to the cationic polyethylenimine-coated control surface, the adsorbed hydrogel particles offer a unique reservoir function to the modified surface that is unparalleled by the control. The successful loading of hydrophobic dye of nile red to the surface adsorbed hydrogel particles indicates that the modified surface not only provides physical support of neurons, but also can be explored in the future to exert localized therapeutic actions favorable for neural interfacing.

  7. In-situ photo-assisted deposition of silver particles on hydrogel fibers for antibacterial applications.

    PubMed

    Raho, Riccardo; Paladini, Federica; Lombardi, Fiorella Anna; Boccarella, Sandro; Zunino, Benedetta; Pollini, Mauro

    2015-10-01

    Silver nanoparticles (AgNPs) have attracted intensive research interest and have been recently incorporated in polymers, medical devices, hydrogels and burn dressings to control the proliferation of microorganisms. In this study a novel silver antibacterial coating was deposited for the first time on hydrogel fibers through an in-situ photo-chemical reaction. Hydrogel blends obtained by mixing different percentages of silver-treated and untreated fibers were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four different fluids, such as phosphate buffered saline (PBS), simulated body fluid (SBF), chemical simulated wound fluid (cSWF), and deionized water (DI water), were used for evaluating the swelling properties. The results obtained confirmed that the presence of silver did not affect the properties of the hydrogel. Moreover, the results obtained through inductively coupled plasma mass spectrometry (ICP-MS) demonstrated very low silver release values, thus indicating the perfect adhesion of the silver coating to the substrate. Good antibacterial capabilities were demonstrated by any hydrogel blend on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) through agar diffusion tests and optical density readings.

  8. Hydrogel microparticles for biosensing

    PubMed Central

    Le Goff, Gaelle C.; Srinivas, Rathi L.; Hill, W. Adam; Doyle, Patrick S.

    2015-01-01

    Due to their hydrophilic, biocompatible, and highly tunable nature, hydrogel materials have attracted strong interest in the recent years for numerous biotechnological applications. In particular, their solution-like environment and non-fouling nature in complex biological samples render hydrogels as ideal substrates for biosensing applications. Hydrogel coatings, and later, gel dot surface microarrays, were successfully used in sensitive nucleic acid assays and immunoassays. More recently, new microfabrication techniques for synthesizing encoded particles from hydrogel materials have enabled the development of hydrogel-based suspension arrays. Lithography processes and droplet-based microfluidic techniques enable generation of libraries of particles with unique spectral or graphical codes, for multiplexed sensing in biological samples. In this review, we discuss the key questions arising when designing hydrogel particles dedicated to biosensing. How can the hydrogel material be engineered in order to tune its properties and immobilize bioprobes inside? What are the strategies to fabricate and encode gel particles, and how can particles be processed and decoded after the assay? Finally, we review the bioassays reported so far in the literature that have used hydrogel particle arrays and give an outlook of further developments of the field. PMID:26594056

  9. Application of an acoustoelectronic technique to study ordered microstructured disperse systems with biological objects in a hydrogel

    NASA Astrophysics Data System (ADS)

    Anisimkin, V. I.; Pokusaev, B. G.; Skladnev, D. A.; Sorokin, V. V.; Tyupa, D. V.

    2016-11-01

    Using acoustoelectronic sensors not containing sensitive coatings, we studied a series of microbiological preparations: yeast cells and bacteria, as well as virus particles, immobilized in hydrogels of different concentration. The obtained measurement data on the acoustic characteristics make it possible to (1) reveal the presence of biological objects in both fluid media and agarose-based hydrogels of various concentration; (2) establish the physical mechanism that results in acoustoelectronic detection; (3) evaluate changes in the concentration of biological objects and their electric conductivity. The data confirm the possibility of applying the acoustoelectronic technique to detect microbiological objects and observe their growth in hydrogel media. We discus the limitations and drawbacks of the acoustoelectronic technique.

  10. The mechanical microenvironment of high concentration agarose for applying deformation to primary chondrocytes.

    PubMed

    Zignego, Donald L; Jutila, Aaron A; Gelbke, Martin K; Gannon, Daniel M; June, Ronald K

    2014-06-27

    Cartilage and chondrocytes experience loading that causes alterations in chondrocyte biological activity. In vivo chondrocytes are surrounded by a pericellular matrix with a stiffness of ~25-200kPa. Understanding the mechanical loading environment of the chondrocyte is of substantial interest for understanding chondrocyte mechanotransduction. The first objective of this study was to analyze the spatial variability of applied mechanical deformations in physiologically stiff agarose on cellular and sub-cellular length scales. Fluorescent microspheres were embedded in physiologically stiff agarose hydrogels. Microsphere positions were measured via confocal microscopy and used to calculate displacement and strain fields as a function of spatial position. The second objective was to assess the feasibility of encapsulating primary human chondrocytes in physiologically stiff agarose. The third objective was to determine if primary human chondrocytes could deform in high-stiffness agarose gels. Primary human chondrocyte viability was assessed using live-dead imaging following 24 and 72h in tissue culture. Chondrocyte shape was measured before and after application of 10% compression. These data indicate that (1) displacement and strain precision are ~1% and 6.5% respectively, (2) high-stiffness agarose gels can maintain primary human chondrocyte viability of >95%, and (3) compression of chondrocytes in 4.5% agarose can induce shape changes indicative of cellular compression. Overall, these results demonstrate the feasibility of using high-concentration agarose for applying in vitro compression to chondrocytes as a model for understanding how chondrocytes respond to in vivo loading.

  11. Mullins effect behaviour under compression in micelle-templated silica and micelle-templated silica/agarose systems.

    PubMed

    Puértolas, J A; Vadillo, J L; Sánchez-Salcedo, S; Nieto, A; Gómez-Barrena, E; Vallet-Regí, M

    2012-02-01

    The mechanical properties of bioceramic conformed pieces based on micelle-templated silica (MTS) such as SBA15, MCM41 and MCM48 as well as MTS/agarose systems have been evaluated under static and cyclic compressive tests. The MTS pieces exhibited a brittle behaviour. Agarose, a biocompatible and biodegradable hydrogel, has been used to shape ceramic-agarose pieces following a low temperature shaping method. Agarose conferred toughness, ductility and a rubbery consistency up to a 60% strain in ceramic MTS/agarose systems leading to a maximum strength of 10-50 MPa, without losing their initial cylindrical structure. This combination of ceramic and organic matrix contributes to avoiding the inherent brittleness of the bioceramic and enhances the compression resistance of hydrogel. The presence of mechanical hysteresis, permanent deformation after the first cycle and recovery of the master monotonous curve of MTS/agarose systems indicate a Mullins-like effect similar to that found in carbon-filled rubber systems. We report this type of mechanical behaviour, the Mullins effect, for the first time in MTS bioceramics and MTS bioceramic/agarose systems.

  12. Multi-responsive hybrid particles: thermo-, pH-, photo-, and magneto-responsive magnetic hydrogel cores with gold nanorod optical triggers

    NASA Astrophysics Data System (ADS)

    Rittikulsittichai, Supparesk; Kolhatkar, Arati G.; Sarangi, Subhasis; Vorontsova, Maria A.; Vekilov, Peter G.; Brazdeikis, Audrius; Randall Lee, T.

    2016-06-01

    The research strategy described in this manuscript harnesses the attractive properties of hydrogels, gold nanorods (Aurods), and magnetic nanoparticles (MNPs) by synthesizing one unique multi-responsive nanostructure. This novel hybrid structure consists of silica-coated magnetic particles encapsulated within a thermo-responsive P(NIPAM-co-AA) hydrogel network on which Aurods are assembled. Furthermore, this research demonstrates that these composite particles respond to several forms of external stimuli (temperature, pH, light, and/or applied magnetic field) owing to their specific architecture. Exposure of the hybrid particles to external stimuli led to a systematic and reversible variation in the hydrodynamic diameter (swelling-deswelling) and thus in the optical properties of the hybrid particles (red-shifting of the plasmon band). Such stimuli-responsive volume changes can be effectively exploited in drug-delivery applications.The research strategy described in this manuscript harnesses the attractive properties of hydrogels, gold nanorods (Aurods), and magnetic nanoparticles (MNPs) by synthesizing one unique multi-responsive nanostructure. This novel hybrid structure consists of silica-coated magnetic particles encapsulated within a thermo-responsive P(NIPAM-co-AA) hydrogel network on which Aurods are assembled. Furthermore, this research demonstrates that these composite particles respond to several forms of external stimuli (temperature, pH, light, and/or applied magnetic field) owing to their specific architecture. Exposure of the hybrid particles to external stimuli led to a systematic and reversible variation in the hydrodynamic diameter (swelling-deswelling) and thus in the optical properties of the hybrid particles (red-shifting of the plasmon band). Such stimuli-responsive volume changes can be effectively exploited in drug-delivery applications. Electronic supplementary information (ESI) available: Contains detailed information about the synthesis of

  13. Agarose-dextran gels as synthetic analogs of glomerular basement membrane: water permeability.

    PubMed Central

    White, Jeffrey A; Deen, William M

    2002-01-01

    Novel agarose-dextran hydrogels were synthesized and their suitability as experimental models of glomerular basement membrane was examined by measuring their Darcy (hydraulic) permeabilities (kappa). Immobilization of large dextran molecules in agarose was achieved by electron beam irradiation. Composite gels were made with agarose volume fractions (phi(a)) of 0.04 or 0.08 and dextran volume fractions (phi(d)) ranging from 0 to 0.02 (fiber volume/gel volume), using either of two dextran molecular weights (500 or 2000). At either agarose concentration and for either size of dextran, kappa decreased markedly as the amount of dextran was increased. Statistically significant deviations from the value of kappa for pure agarose were obtained for remarkably small volume fractions of dextran: phi(d) > or = 0.0003 for phi(a) = 0.04 and phi(d) > or = 0.001 for phi(a) = 0.08. The Darcy permeabilities were much more sensitive to phi(d) than to phi(a), and were as much as 26 times smaller than those of pure agarose. Although phi(d) was an important variable, dextran molecular weight was not. The effects of dextran addition on kappa were described fairly well using simple structural idealizations. At high agarose concentrations, the dextran chains behaved as fine fibers interspersed among coarse agarose fibrils, whereas, at low concentrations, the dextran molecules began to resemble spherical obstacles embedded in agarose gels. The ability to achieve physiologically relevant Darcy permeabilities with these materials (as low as 1.6 nm2) makes them an attractive experimental model for glomerular basement membrane and possibly other extracellular matrices. PMID:11916864

  14. Blinking suppression of single quantum dots in agarose gel

    SciTech Connect

    Ko, H. C.; Yuan, C. T.; Tang, Jau; Lin, S. H.

    2010-01-04

    Fluorescence blinking is commonly observed in single molecule/particle spectroscopy, but it is an undesirable feature in many applications. We demonstrated that single CdSe/ZnS quantum dots in agarose gel exhibited suppressed blinking behavior. In addition, the long-time exponential bending tail of the power-law blinking statistics was found to be influenced by agarose gel concentration. We suggest that electron transfer from the light state to the dark state might be blocked due to electrostatic surrounding of gel with inherent negatively charged fibers.

  15. Hydrothermally Treated Chitosan Hydrogel Loaded with Copper and Zinc Particles as a Potential Micronutrient-Based Antimicrobial Feed Additive

    PubMed Central

    Rajasekaran, Parthiban; Santra, Swadeshmukul

    2015-01-01

    Large-scale use of antibiotics in food animal farms as growth promoters is considered as one of the driving factors behind increasing incidence of microbial resistance. Several alternatives are under investigation to reduce the amount of total antibiotics used in order to avoid any potential transmission of drug resistant microbes to humans through food chain. Copper sulfate and zinc oxide salts are used as feed supplement as they exhibit antimicrobial properties in addition to being micronutrients. However, higher dosage of copper and zinc (often needed for growth promoting effect) to animals is not advisable because of potential environmental toxicity arising from excreta. Innovative strategies are needed to utilize the complete potential of trace minerals as growth promoting feed supplements. To this end, we describe here the development and preliminary characterization of hydrothermally treated chitosan as a delivery vehicle for copper and zinc nanoparticles that could act as a micronutrient-based antimicrobial feed supplement. Material characterization studies showed that hydrothermal treatment makes a chitosan hydrogel that rearranged to capture the copper and zinc metal particles. Systemic antimicrobial assays showed that this chitosan biopolymer matrix embedded with copper (57.6 μg/ml) and zinc (800 μg/ml) reduced the load of model gut bacteria (target organisms of growth promoting antibiotics), such as Escherichia coli, Enterococcus faecalis, Staphylococcus aureus, and Lactobacillus fermentum under in vitro conditions. Particularly, the chitosan/copper/zinc hydrogel exhibited significantly higher antimicrobial effect against L. fermentum, one of the primary targets of antibiotic growth promoters. Additionally, the chitosan matrix ameliorated the cytotoxicity levels of metal supplements when screened against a murine macrophage cell line RAW 264.7 and in TE-71, a murine thymic epithelial cell line. In this proof-of-concept study, we show that by using

  16. A simple route to synthesize conductive stimuli-responsive polypyrrole nanocomposite hydrogel particles with strong magnetic properties and their performance for removal of hexavalent chromium ions from aqueous solution

    NASA Astrophysics Data System (ADS)

    Ahmad, Hasan; Rahman, Mohammad Mostafizar; Ali, Mohammad Azgar; Minami, Hideto; Tauer, Klaus; Gafur, Mohammad Abdul; Rahman, Mohammad Mahbubor

    2016-08-01

    A combination of maghemite polypyrrole (PPy/γ-Fe2O3) and stimuli-responsive properties in the same hydrogel microspheres is expected to enhance their application potential in various fields such as tissue engineering, regenerative medicine, biosensors, biomedical applications and removal of heavy metals from waste water, catalysis etc. In this investigation a simple two step process is used to prepare conductive stimuli-responsive polypyrrole (PPy) composite hydrogel particles with strong magnetic properties. Poly(styrene-methacrylic acid-N-isopropylacrylamide-polyethelene glycol methacrylate) or P(S-NIPAM-MAA-PEGMA) hydrogel seed particles are first prepared by soap-free precipitation copolymerization. The copolymer hydrogel particles exhibited both temperature- and pH-responsive volume phase transition. Conductive P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe2O3 nanocomposite hydrogel particles are then prepared by seeded chemical oxidative polymerization of pyrrole in the presence of P(S-NIPAM-MAA-PEGMA) hydrogel seed particles using FeCl3 as a oxidant and p-toluene sulfonic acid (p-TSA) as a dopant. In the reaction system FeCl3 functioned as a source of Fe(III) for the formation of γ-Fe2O3. This reaction also requires the initial presence of Fe(II) provided by the addition of FeCl2. The size and size distribution, surface structure, and morphology of the prepared conductive composite hydrogel particles are confirmed by FTIR, electron micrographs, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV-visible spectroscopy. The performance of nanocomposite hydrogel particles has been evaluated for the removal of hexavalent chromium (Cr) ions from water.

  17. Brain derived neurotrophic factor release from layer-by-layer coated agarose nerve guidance scaffolds.

    PubMed

    Lynam, Daniel A; Shahriari, Dena; Wolf, Kayla J; Angart, Phillip A; Koffler, Jacob; Tuszynski, Mark H; Chan, Christina; Walton, Patrick; Sakamoto, Jeffrey

    2015-05-01

    Agarose nerve guidance scaffolds (NGS) seeded with cells expressing brain derived neurotrophic factor (BDNF) have demonstrated robust nerve regeneration in the rat central nervous system. The purpose of this work was to explore whether agarose NGS coated with hydrogen-bonded layer-by-layer (HLbL) could provide an acellular method of delivering prolonged and consistent dosages of active BDNF. Our results show that HLbL-coated agarose NGS could release BDNF over 10days in consistent dosages averaging 80.5±12.5(SD)ng/mL. Moreover, the BDNF released from HLbL was confirmed active by in vitro cell proliferation assays. To our knowledge, this is the first report demonstrating that HLbL assembled onto a hydrogel can provide consistent, prolonged release of active BDNF in clinically relevant dosages.

  18. Agarose-Based Substrate Modification Technique for Chemical and Physical Guiding of Neurons In Vitro.

    PubMed

    Krumpholz, Katharina; Rogal, Julia; El Hasni, Akram; Schnakenberg, Uwe; Bräunig, Peter; Bui-Göbbels, Katrin

    2015-08-26

    A new low cost and highly reproducible technique is presented that provides patterned cell culture substrates. These allow for selective positioning of cells and a chemically and mechanically directed guiding of their extensions. The patterned substrates consist of structured agarose hydrogels molded from reusable silicon micro templates. These templates consist of pins arranged equidistantly in squares, connected by bars, which mold corresponding wells and channels in the nonadhesive agarose hydrogel. Subsequent slice production with a standard vibratome, comprising the described template pattern, completes substrate production. Invertebrate neurons of locusts and pond snails are used for this application as they offer the advantage over vertebrate cells as being very large and suitable for cultivation in low cell density. Their neurons adhere to and grow only on the adhesive areas not covered by the agarose. Agarose slices of 50 μm thickness placed on glass, polystyrene, or MEA surfaces position and immobilize the neurons in the wells, and the channels guide their neurite outgrowth toward neighboring wells. In addition to the application with invertebrate neurons, the technique may also provide the potential for the application of a wide range of cell types. Long-term objective is the achievement of isolated low-density neuronal networks on MEAs or different culture substrates for various network analysis applications.

  19. 3D printing enables separation of orthogonal functions within a hydrogel particle.

    PubMed

    Raman, Ritu; Clay, Nicholas E; Sen, Sanjeet; Melhem, Molly; Qin, Ellen; Kong, Hyunjoon; Bashir, Rashid

    2016-06-01

    Multifunctional particles with distinct physiochemical phases are required by a variety of applications in biomedical engineering, such as diagnostic imaging and targeted drug delivery. This motivates the development of a repeatable, efficient, and customizable approach to manufacturing particles with spatially segregated bioactive moieties. This study demonstrates a stereolithographic 3D printing approach for designing and fabricating large arrays of biphasic poly (ethylene glycol) diacrylate (PEGDA) gel particles. The fabrication parameters governing the physical and biochemical properties of multi-layered particles are thoroughly investigated, yielding a readily tunable approach to manufacturing customizable arrays of multifunctional particles. The advantage in spatially organizing functional epitopes is examined by loading superparamagnetic iron oxide nanoparticles (SPIONs) and bovine serum albumin (BSA) in separate layers of biphasic PEGDA gel particles and examining SPION-induced magnetic resonance (MR) contrast and BSA-release kinetics. Particles with spatial segregation of functional moieties have demonstrably higher MR contrast and BSA release. Overall, this study will contribute significant knowledge to the preparation of multifunctional particles for use as biomedical tools.

  20. A composite scaffold of MSC affinity peptide-modified demineralized bone matrix particles and chitosan hydrogel for cartilage regeneration

    PubMed Central

    Meng, Qingyang; Man, Zhentao; Dai, Linghui; Huang, Hongjie; Zhang, Xin; Hu, Xiaoqing; Shao, Zhenxing; Zhu, Jingxian; Zhang, Jiying; Fu, Xin; Duan, Xiaoning; Ao, Yingfang

    2015-01-01

    Articular cartilage injury is still a significant challenge because of the poor intrinsic healing potential of cartilage. Stem cell-based tissue engineering is a promising technique for cartilage repair. As cartilage defects are usually irregular in clinical settings, scaffolds with moldability that can fill any shape of cartilage defects and closely integrate with the host cartilage are desirable. In this study, we constructed a composite scaffold combining mesenchymal stem cells (MSCs) E7 affinity peptide-modified demineralized bone matrix (DBM) particles and chitosan (CS) hydrogel for cartilage engineering. This solid-supported composite scaffold exhibited appropriate porosity, which provided a 3D microenvironment that supports cell adhesion and proliferation. Cell proliferation and DNA content analysis indicated that the DBM-E7/CS scaffold promoted better rat bone marrow-derived MSCs (BMMSCs) survival than the CS or DBM/CS groups. Meanwhile, the DBM-E7/CS scaffold increased matrix production and improved chondrogenic differentiation ability of BMMSCs in vitro. Furthermore, after implantation in vivo for four weeks, compared to those in control groups, the regenerated issue in the DBM-E7/CS group exhibited translucent and superior cartilage-like structures, as indicated by gross observation, histological examination, and assessment of matrix staining. Overall, the functional composite scaffold of DBM-E7/CS is a promising option for repairing irregularly shaped cartilage defects. PMID:26632447

  1. A composite scaffold of MSC affinity peptide-modified demineralized bone matrix particles and chitosan hydrogel for cartilage regeneration

    NASA Astrophysics Data System (ADS)

    Meng, Qingyang; Man, Zhentao; Dai, Linghui; Huang, Hongjie; Zhang, Xin; Hu, Xiaoqing; Shao, Zhenxing; Zhu, Jingxian; Zhang, Jiying; Fu, Xin; Duan, Xiaoning; Ao, Yingfang

    2015-12-01

    Articular cartilage injury is still a significant challenge because of the poor intrinsic healing potential of cartilage. Stem cell-based tissue engineering is a promising technique for cartilage repair. As cartilage defects are usually irregular in clinical settings, scaffolds with moldability that can fill any shape of cartilage defects and closely integrate with the host cartilage are desirable. In this study, we constructed a composite scaffold combining mesenchymal stem cells (MSCs) E7 affinity peptide-modified demineralized bone matrix (DBM) particles and chitosan (CS) hydrogel for cartilage engineering. This solid-supported composite scaffold exhibited appropriate porosity, which provided a 3D microenvironment that supports cell adhesion and proliferation. Cell proliferation and DNA content analysis indicated that the DBM-E7/CS scaffold promoted better rat bone marrow-derived MSCs (BMMSCs) survival than the CS or DBM/CS groups. Meanwhile, the DBM-E7/CS scaffold increased matrix production and improved chondrogenic differentiation ability of BMMSCs in vitro. Furthermore, after implantation in vivo for four weeks, compared to those in control groups, the regenerated issue in the DBM-E7/CS group exhibited translucent and superior cartilage-like structures, as indicated by gross observation, histological examination, and assessment of matrix staining. Overall, the functional composite scaffold of DBM-E7/CS is a promising option for repairing irregularly shaped cartilage defects.

  2. Silk microfiber-reinforced silk hydrogel composites for functional cartilage tissue repair

    PubMed Central

    Yodmuang, Supansa; McNamara, Stephanie L.; Nover, Adam B.; Mandal, Biman B.; Agarwal, Monica; Kelly, Terri-Ann N.; Chao, Pen-hsiu Grace; Hung, Clark; Kaplan, David L.; Vunjak-Novakovic, Gordana

    2014-01-01

    Cartilage tissue lacks an intrinsic capacity for self-regeneration due to slow matrix turnover, a limited supply of mature chondrocytes and insufficient vasculature. Although cartilage tissue engineering has achieved some success using agarose as a scaffolding material, major challenges of agarose-based cartilage repair, including non-degradability, poor tissue–scaffold integration and limited processing capability, have prompted the search for an alternative biomaterial. In this study, silk fiber–hydrogel composites (SF–silk hydrogels) made from silk microfibers and silk hydrogels were investigated for their potential use as a support material for engineered cartilage. We demonstrated the use of 100% silk-based fiber–hydrogel composite scaffolds for the development of cartilage constructs with properties comparable to those made with agarose. Cartilage constructs with an equilibrium modulus in the native tissue range were fabricated by mimicking the collagen fiber and proteoglycan composite architecture of native cartilage using biocompatible, biodegradable silk fibroin from Bombyx mori. Excellent chondrocyte response was observed on SF–silk hydrogels, and fiber reinforcement resulted in the development of more mechanically robust constructs after 42 days in culture compared to silk hydrogels alone. Thus, we demonstrate the versatility of silk fibroin as a composite scaffolding material for use in cartilage tissue repair to create functional cartilage constructs that overcome the limitations of agarose biomaterials, and provide a much-needed alternative to the agarose standard. PMID:25281788

  3. Silk microfiber-reinforced silk hydrogel composites for functional cartilage tissue repair.

    PubMed

    Yodmuang, Supansa; McNamara, Stephanie L; Nover, Adam B; Mandal, Biman B; Agarwal, Monica; Kelly, Terri-Ann N; Chao, Pen-hsiu Grace; Hung, Clark; Kaplan, David L; Vunjak-Novakovic, Gordana

    2015-01-01

    Cartilage tissue lacks an intrinsic capacity for self-regeneration due to slow matrix turnover, a limited supply of mature chondrocytes and insufficient vasculature. Although cartilage tissue engineering has achieved some success using agarose as a scaffolding material, major challenges of agarose-based cartilage repair, including non-degradability, poor tissue-scaffold integration and limited processing capability, have prompted the search for an alternative biomaterial. In this study, silk fiber-hydrogel composites (SF-silk hydrogels) made from silk microfibers and silk hydrogels were investigated for their potential use as a support material for engineered cartilage. We demonstrated the use of 100% silk-based fiber-hydrogel composite scaffolds for the development of cartilage constructs with properties comparable to those made with agarose. Cartilage constructs with an equilibrium modulus in the native tissue range were fabricated by mimicking the collagen fiber and proteoglycan composite architecture of native cartilage using biocompatible, biodegradable silk fibroin from Bombyx mori. Excellent chondrocyte response was observed on SF-silk hydrogels, and fiber reinforcement resulted in the development of more mechanically robust constructs after 42 days in culture compared to silk hydrogels alone. Thus, we demonstrate the versatility of silk fibroin as a composite scaffolding material for use in cartilage tissue repair to create functional cartilage constructs that overcome the limitations of agarose biomaterials, and provide a much-needed alternative to the agarose standard.

  4. Nondenaturing electrophoresis of lipoproteins in agarose and polyacrylamide gradient gels

    SciTech Connect

    Shore, V.G.

    1989-12-19

    The plasma lipoproteins frequently are classified according to density and/or electrophoretic mobility. The lipoprotein classes differ characteristically also in particle size and apolipoprotein composition. Each class is heterogeneous in size and composition as well. Nondenaturing electrophoresis in agarose gels and polyacrylamide gradient gels are complementary analytical methods for classification of lipoproteins and determining distribution profiles of the major classes. In addition, gradient gel electrophoresis (GGE) has a high resolving capability for subfractionating each class according to particle size. Combination of gel electrophoresis with immunoblotting yields information on heterogeneity in apolipoprotein distribution. 14 refs., 6 figs., 3 tabs.

  5. Effect of decellularized adipose tissue particle size and cell density on adipose-derived stem cell proliferation and adipogenic differentiation in composite methacrylated chondroitin sulphate hydrogels.

    PubMed

    Brown, Cody F C; Yan, Jing; Han, Tim Tian Y; Marecak, Dale M; Amsden, Brian G; Flynn, Lauren E

    2015-07-30

    An injectable composite scaffold incorporating decellularized adipose tissue (DAT) as a bioactive matrix within a hydrogel phase capable of in situ polymerization would be advantageous for adipose-derived stem cell (ASC) delivery in the filling of small or irregular soft tissue defects. Building on previous work, the current study investigates DAT milling methods and the effects of DAT particle size and cell seeding density on the response of human ASCs encapsulated in photo-cross-linkable methacrylated chondroitin sulphate (MCS)-DAT composite hydrogels. DAT particles were generated by milling lyophilized DAT and the particle size was controlled through the processing conditions with the goal of developing composite scaffolds with a tissue-specific 3D microenvironment tuned to enhance adipogenesis. ASC proliferation and adipogenic differentiation were assessed in vitro in scaffolds incorporating small (average diameter of 38   ±   6 μm) or large (average diameter of 278   ±   3 μm) DAT particles in comparison to MCS controls over a period of up to 21 d. Adipogenic differentiation was enhanced in the composites incorporating the smaller DAT particles and seeded at the higher density of 5   ×   10(5) ASCs/scaffold, as measured by glycerol-3-phosphate dehydrogenase (GPDH) enzyme activity, semi-quantitative analysis of perilipin expression and oil red O staining of intracellular lipid accumulation. Overall, this study demonstrates that decellularized tissue particle size can impact stem cell differentiation through cell-cell and cell-matrix interactions, providing relevant insight towards the rational design of composite biomaterial scaffolds for adipose tissue engineering.

  6. Diffusion coefficient in hydrogel under high-frequency ultrasound

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Akira; Tanaka, Kei; Kumata, Tatsuya; Watanabe, Yoshiaki; Miyata, Shogo; Furukawa, Katsuko; Ushida, Takashi

    2007-03-01

    Modulating hydrogel properties by external stimuli can be applied for drug delivery system. For example, ultrasound can enhance drug release from hydrogel by the mechanism which is not fully understood. We measured diffusion coefficient in hydrogel under high-frequency ultrasound to understand mass transport property. To estimate diffusion coefficient, FRAP (fluorescence recovery after photobleaching) technique was applied with time-lapse fluorescence microscopy and we analyzed fluorescence recovery after photobleaching of FITC-dextran (4˜40 kDa) which was fully fused in agarose gel (1˜3 %). As a result, diffusion coefficient was altered when agarose gel was sonicated by 1MHz ultrasound with 400kPa (peak-peak). We discussed several possible underlying mechanisms such as cavitation, heat and phase transition with extended experimental data.

  7. Enhanced detection of gold nanoparticles in agarose gel electrophoresis.

    PubMed

    Hasenoehrl, Carina; Alexander, Colleen M; Azzarelli, Nicholas N; Dabrowiak, James C

    2012-04-01

    Gel electrophoresis is a powerful tool in gold nanoparticle (AuNP) research. While the technique is sensitive to the size, charge, and shape of particles, its optimal performance requires a relatively large amount of AuNP in the loading wells for visible detection of bands. We here describe a novel and more sensitive method for detecting AuNPs in agarose gels that involves staining the gel with the common organic fluorophore fluorescein, to produce AuNP band intensities that are linear with nanoparticle concentration and almost an order of magnitude larger than those obtained without staining the gel.

  8. In situ assembly of antifouling/bacterial silver nanoparticle-hydrogel composites with controlled particle release and matrix softening.

    PubMed

    Baek, Kwanghyun; Liang, Jing; Lim, Wan Ting; Zhao, Huimin; Kim, Dong Hyun; Kong, Hyunjoon

    2015-07-22

    Controlling bacterial contamination has been a major challenge for protecting human health and welfare. In this context, hydrogels loaded with silver nanoparticles have been used to prevent biofilm formation on substrates of interest. However, such gel composites are often plagued by rapid loss of silver nanoparticles and matrix softening, and thus the gel becomes less effective for antifouling. To this end, this study demonstrates that in situ photoreaction of an aqueous mixture of silver nitrates, poly(ethylene glycol) diacrylate, and vinylpyrrolidone results in a silver nanoparticle-laden hydrogel composite with minimal nanoparticle loss and matrix softening due to enhanced binding between nanoparticles and the gel. The resulting gel composite successfully inhibits the bacterial growth in media and the bacterial adhesion to surfaces of interest. We suggest that the results of this study serve to advance quality of materials with antifouling/bacterial activities.

  9. Synthesis of protein-loaded hydrogel particles in an aqueous two-phase system for coincident antigen and CpG oligonucleotide delivery to antigen-presenting cells.

    PubMed

    Jain, Siddhartha; Yap, Woon Teck; Irvine, Darrell J

    2005-01-01

    Materials that effectively deliver protein antigens together with activating ligands to antigen-presenting cells are sought for improved nonviral vaccines. To this end, we synthesized protein-loaded poly(ethylene glycol) (PEG)-based hydrogel particles by cross-linking PEG within the polymer-rich phase of an emulsion formed by a poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) triblock copolymer in saturated aqueous salt solution. These particles (500-nm diameter) contained high levels of encapsulated protein (approximately 75% of dry mass), which was selectively released by proteolytic enzymes normally present in the phagosomal/endosomal compartments of dendritic cells (DCs). For co-delivery of cellular activation signals, gel particles were surface-modified by sequential adsorption of poly(l-arginine) and CpG oligonucleotides. DCs pulsed with protein-loaded particles activated naïve T cells in vitro approximately 10-fold more efficiently than DCs incubated with soluble protein. This organic solvent-free strategy for protein encapsulation within submicron-sized hydrophilic particles is attractive for macromolecule delivery to a variety of phagocytic and nonphagocytic cells.

  10. An agarose gel-based neurosphere culture system leads to enrichment of neuronal lineage cells in vitro.

    PubMed

    Park, Kyuhee; Nam, Yeonju; Choi, Yongmun

    2015-05-01

    Stem cell-based therapy holds great potential especially for neurological disorders. However, clinical applications await further understanding of many aspects of stem cell differentiation and development of technology enabling manipulation of stem cells into desired cell types in the central nervous system. Here, we developed a new method that leads to enrichment of neuronal lineage cells in neural stem cell cultures. The protocol involves cultivation of primary cells derived from the forebrains of rat E18 embryos above a layer of nonadhesive hard agarose gel in the form of neurospheres. In contrast to the neurospheres that were cultured above an anti-adhesive hydrogel layer, the primary cells that were cultured above a layer of agarose gel preferentially differentiated into β-III tubulin-positive neurons when allowed to undergo differentiation in vitro.In an effort to investigate the mechanism behind this observation, we found that the gene expression of a vertebrate neuronal determination gene (neurogenin1) was enhanced in the neurospheres that proliferated above a layer of agarose gel as compared with the control, and the gene expression level of neurogenin1 was quite well correlated with the rigidity of agarose gel. These results indicate that agarose gel can contribute, at least in part, to enrich neuronal progenitors and immature postmitotic neurons during neurosphere formation and may provide additional information to establish efficient protocols for the neural stem cell-based study.

  11. Raspberry-like poly(γ-glutamic acid) hydrogel particles for pH-dependent cell membrane passage and controlled cytosolic delivery of antitumor drugs

    PubMed Central

    Cho, Sun-Hee; Hong, Ji Hyeon; Noh, Young-Woock; Lee, Eunji; Lee, Chang-Soo; Lim, Yong Taik

    2016-01-01

    In this research, we synthesized bioderived poly(amino acid) hydrogel particles that showed pH-dependent membrane-disrupting properties and controlled cytosolic delivery of antitumor drugs. Poly(γ-glutamic acid) (γ-PGA) that has been produced extensively using bacteria, especially those of Bacillus subtilis species, was modified with cholesterol (γ-PGA/Chol), and the γ-PGA/Chol conjugates were used to form polymeric nanoparticles the size of 21.0±1.1 nm in aqueous solution. When the polymeric nanoparticles were mixed with doxorubicin (Dox), raspberry-like hydrogel particles (RBHPs) were formed by the electrostatic interaction between the cationically charged Dox and the anionically charged nanoparticles. The average size and surface charge of the RBHPs in aqueous solution were 444.9±122.5 nm and −56.44 mV, respectively. The loaded amount of Dox was approximately 63.9 μg/mg of RBHPs. The RBHPs showed controlled drug release behavior in both in vitro and ex vivo cell-based experiments. Through fluorescence microscopy and fluorescence-activated cell sorting, the cellular uptake of RBHPs into human cervical cancer cells (HeLa) was analyzed. The cytotoxic effect, evaluated by the methyl tetrazolium salt assay, was dependent on both the concentration of RBHPs and the treatment time. The pH-dependent membrane-disrupting properties of the RBHPs and the subsequent cytosolic delivery of Dox were evaluated using a standard hemolysis assay. Upon an increase in hydrophobicity at the lysosomal acidic pH, RBHPs could easily interact, penetrate cell membranes, and destabilize them. Taken together, the data suggested that RBHPs could be used as drug delivery carriers after loading with other therapeutic drugs, such as proteins or small interfering RNA for cancer therapy. PMID:27822040

  12. Recycling of superfine resolution agarose gel.

    PubMed

    Seng, T-Y; Singh, R; Faridah, Q Z; Tan, S-G; Alwee, S S R S

    2013-07-08

    Genetic markers are now routinely used in a wide range of applications, from forensic DNA analysis to marker-assisted plant and animal breeding. The usual practice in such work is to extract the DNA, prime the markers of interest, and sift them out by electrically driving them through an appropriate matrix, usually a gel. The gels, made from polyacrylamide or agarose, are of high cost, limiting their greater applications in molecular marker work, especially in developing countries where such technology has great potential. Trials using superfine resolution (SFR) agarose for SSR marker screening showed that it is capable of resolving SSR loci and can be reused up to 14 times, thus greatly reducing the cost of each gel run. Furthermore, for certain applications, low concentrations of agarose sufficed and switching to lithium borate buffer, instead of the conventional Tris-borate-ethylenediaminetetraacetic acid buffer, will further save time and cost. The 2.5% gel was prepared following the Agarose SFR(TM) manual by adding 2.5 g agarose powder into 100 mL 1X lithium borate buffer in a 250-mL flask with rapid stirring. Two midigels (105 x 83 mm, 17 wells) or 4 minigels (50 x 83 mm, 8 wells), 4 mm thickness can be prepared from 100 mL gel solution. A total of 1680 PCR products amplified using 140 SSR markers from oil palm DNA samples were tested in this study using SFR recycled gel. As average, the gel can be recycled 8 times with good resolution, but can be recycled up to 14 times before the resolutions get blurred.

  13. Agarose-assisted micro-contact printing for high-quality biomolecular micro-patterns.

    PubMed

    Jang, Min Jee; Nam, Yoonkey

    2015-05-01

    Micro-contact printing has been developed to print biomolecules, such as cell adhesive molecules, proteins, or DNAs, on a substrate, which can serve as experimental platforms for investigating biological issues and engineering biosensors. Despite the popularity of this method, it has been technically challenging to use a conventional stamp made of a hydrophobic polydimethoxysilane (PDMS) elastomer that often requires surface treatments to facilitate the inking and stamping of biomolecules. In this work, we proposed a new surface modification method for a PDMS stamp using agarose hydrogel and demonstrated the applications to the design of micro-patterned substrates with biomolecules. By using a simple bench-top dip-coating method with a commercial syringe pump to steadily pull out the stamp from boiled agarose solution, we coated an agarose layer on the stamp. It consequentially enhanced the transferability of ink molecules to the target substrate and the uniformity of printed patterns compared to the traditional methods for treating stamp surface such as surfactant coating and temporary oxidation with air plasma. In addition, this microstamping method was also used to produce patterns of proteins with the preservation of bioactivity, which could guide neuronal growth. Thus, we demonstrated the applicability to the interface designs of biochips and biosensors.

  14. A tailored three-dimensionally printable agarose-collagen blend allows encapsulation, spreading, and attachment of human umbilical artery smooth muscle cells.

    PubMed

    Köpf, Marius; Campos, Daniela F Duarte; Blaeser, Andreas; Sen, Kshama S; Fischer, Horst

    2016-05-20

    In recent years, novel biofabrication technologies have enabled the rapid manufacture of hydrogel-cell suspensions into tissue-imitating constructs. The development of novel materials for biofabrication still remains a challenge due to a gap between contradicting requirements such as three-dimensional printability and optimal cytocompatibility. We hypothesise that blending of different hydrogels could lead to a novel material with favourable biological and printing properties. In our work, we combined agarose and type I collagen in order to develop a hydrogel blend capable of long-term cell encapsulation of human umbilical artery smooth muscle cells (HUASMCs) and 3D drop-on-demand printing. Different blends were prepared with 0.25%, 0.5%, 0.75%, and 1.5% agarose and 0.2% type I collagen. The cell morphology of HUASMCs and the printing accuracy were assessed for each agarose-collagen combination, keeping the content of collagen constant. The hydrogel blend which displayed sufficient cell spreading and printing accuracy (0.5% agarose, 0.2% type I collagen, AGR0.5COLL0.2) was then characterised based on swelling and degradation over 21 days and mechanical stiffness. The cellular response regarding cell attachment of HUASMCs embedded in the hydrogel blend was further studied using SEM, TEM, and TPLSM. Printing trials were fabricated in a drop-on-demand printing process. The swelling and degradation evaluation showed an average of 20% mass loss and less than 10% swelling. AGR0.5COLL0.2 exhibited significant increase in stiffness compared to pure agarose and type I collagen. In addition, columns of AGR0.5COLL0.2 three centimeters in height were successfully printed submerged in cooled perfluorocarbon, proving the intrinsic printability of the hydrogel blend. Ultimately, a promising novel hydrogel blend showing cell spreading and attachment as well as suitability for bioprinting was identified and could, for example, serve in the manufacture of in vitro 3D models to

  15. Crosslinking of agarose bioplastic using citric acid.

    PubMed

    Awadhiya, Ankur; Kumar, David; Verma, Vivek

    2016-10-20

    We report chemical crosslinking of agarose bioplastic using citric acid. Crosslinking was confirmed using Fourier transform infrared (FTIR) spectroscopy. The effects of crosslinking on the tensile strength, swelling, thermal stability, and degradability of the bioplastic were studied in detail. The tensile strength of the bioplastic films increased from 25.1MPa for control films up to a maximum of 52.7MPa for citric acid crosslinked films. At 37°C, the amount of water absorbed by crosslinked agarose bioplastic was only 11.5% of the amount absorbed by non-crosslinked controls. Thermogravimetric results showed that the crosslinked samples retain greater mass at high temperature (>450°C) than control samples. Moreover, while the crosslinked films were completely degradable, the rate of degradation was lower compared to non-crosslinked controls.

  16. Nondenaturing agarose gel electrophoresis of RNA.

    PubMed

    Rio, Donald C; Ares, Manuel; Hannon, Gregory J; Nilsen, Timothy W

    2010-06-01

    INTRODUCTION Perhaps the most important and certainly the most often used technique in RNA analysis is gel electrophoresis. Because RNAs are negatively charged, they migrate toward the anode in the presence of electric current. The gel acts as a sieve to selectively impede the migration of the RNA in proportion to its mass, given that its mass is generally proportional to its charge. Because mass is approximately related to chain length, the length of an RNA is more generally determined by its migration. In addition, topology (i.e., circularity) can affect migration, making RNAs appear longer on the gel than they actually are. There are two common types of gel: polyacrylamide and agarose. For most applications involving RNAs of < or =600 nucleotides, denaturing acrylamide gels are most appropriate. In contrast, agarose gels are generally used to analyze RNAs of > or =600 nucleotides, and are especially useful for analysis of mRNAs (e.g., by Northern blotting). RNA analysis on agarose gels is essentially identical to DNA analysis (except that the gel boxes used must be dedicated to RNA work or to other ribonuclease-free work). Here we describe the use of straightforward Tris borate, EDTA (TBE) gels for routine analysis. These gels are appropriate for determining the quantity and integrity of RNA before using it for other applications. This procedure should not be used to determine size with accuracy, because the RNA will not remain in its extended state throughout the run.

  17. Sequential assembly of 3D perfusable microfluidic hydrogels.

    PubMed

    He, Jiankang; Zhu, Lin; Liu, Yaxiong; Li, Dichen; Jin, Zhongmin

    2014-11-01

    Bottom-up tissue engineering provides a promising way to recreate complex structural organizations of native organs in artificial constructs by assembling functional repeating modules. However, it is challenging for current bottom-up strategies to simultaneously produce a controllable and immediately perfusable microfluidic network in modularly assembled 3D constructs. Here we presented a bottom-up strategy to produce perfusable microchannels in 3D hydrogels by sequentially assembling microfluidic modules. The effects of agarose-collagen composition on microchannel replication and 3D assembly of hydrogel modules were investigated. The unique property of predefined microchannels in transporting fluids within 3D assemblies was evaluated. Endothelial cells were incorporated into the microfluidic network of 3D hydrogels for dynamic culture in a house-made bioreactor system. The results indicated that the sequential assembly method could produce interconnected 3D predefined microfluidic networks in optimized agarose-collagen hydrogels, which were fully perfusable and successfully functioned as fluid pathways to facilitate the spreading of endothelial cells. We envision that the presented method could be potentially used to engineer 3D vascularized parenchymal constructs by encapsulating primary cells in bulk hydrogels and incorporating endothelial cells in predefined microchannels.

  18. Variably elastic hydrogel patterned via capillary action in microchannels.

    PubMed

    Dong, Rui; Jensen, Tor W; Engberg, Kristin; Nuzzo, Ralph G; Leckband, Deborah E

    2007-01-30

    Agarose hydrogels of varied elastic modulus can be patterned into 100-microm-wide channels with wall heights of 60 microm. After modifying the hydrogels with chloroacetic acid (acid gels), they are amenable to modification with amine-containing ligands using EDC-NHS chemistry. Using both rheometry and atomic force microscopy (AFM) nanoindentation measurements, the elastic modulus of unmodified hydrogels increases linearly from 3.6 +/- 0.5 kPa to 45.2 +/- 5.5 kPa for 0.5 to 2.0 wt/vol % hydrogel, respectively. The elastic modulus of acid gels is 2.2 +/- 0.3 kPa to 16.2 +/- 1.6 kPa for 0.5 to 2.0 wt/vol %, respectively. No further changes were measured after further modifying the acid gels with fibronectin. Confocal images of rhodamine-modified acid gels show that the optimal filling viscosity of the agarose solutions is between 1 and 4 cP. This new method of patterning allows for the creation of substrates that take advantage of both micron-scale patterns and variably elastic hydrogels.

  19. Growth in Agarose of Human Cells Infected with Cytomegalovirus

    PubMed Central

    Lang, David J.; Montagnier, Luc; Latarjet, Raymond

    1974-01-01

    After infection by human cytomegalovirus (CMV), human diploid fibroblasts could grow in agarose medium for several generations. Clones of infected cells grew for weeks, although in every case they ultimately underwent lysis owing to the cytopathic effect of the virus. Virus was inoculated at high dilution and after UV irradiation in an effort to derive cells infected with noninfectious defective particles still capable of inducing cell stimulation. Dilute or irradiated virus occasionally yielded large colonies of replicating cells, although permanent transformation was not observed. One clone derived from UV-CMV-infected cells was passaged four times before undergoing lysis. During these passages the cells exhibited alterations in morphology and orientation. Images PMID:4367907

  20. Swelling kinetics of microgels embedded in a polyacrylamide hydrogel matrix.

    PubMed

    Huang, Na; Guan, Ying; Zhu, X X; Zhang, Yongjun

    2014-06-23

    Composite hydrogels--macroscopic hydrogels with embedded microgel particles--are expected to respond to external stimuli quickly because microgels swell much faster than bulky gels. In this work, the kinetics of the pH-induced swelling of a composite hydrogel are studied using turbidity measurements. The embedded microgel is a pH- and thermosensitive poly(N-isopropylacrylamide-co-acrylic acid) microgel and the hydrogel matrix is polyacrylamide. A rapid pH-induced swelling of the embedded microgel particles is observed, confirming that composite hydrogels respond faster than ordinary hydrogels. However, compared with the free microgels, the swelling of the embedded microgel is much slower. Diffusion of OH(-) into the composite hydrogel film is identified as the main reason for the slow swelling of the embedded microgel particles, as the time of the pH-induced swelling of this film is comparable to that of OH(-) diffusion into the film. The composition of the hydrogel matrix does not significantly change the characteristic swelling time of the composite hydrogel film. However, the swelling pattern of the film changes with composition of the hydrogel matrix.

  1. Effect of strain on viscoelastic behavior of fresh, swelled and mineralized PVP-CMC hydrogel

    NASA Astrophysics Data System (ADS)

    Saha, Nabanita; Vyroubal, Radek; Shah, Rushita; Kitano, Takeshi; Saha, Petr

    2013-04-01

    Mineralization of calcium carbonate (CaCO3) in hydrogel matrix is one of the most interesting topics of research by material scientists for the development of bio-inspired polymeric biomaterial for biomedical applications especially for bone tissue regeneration. As per our knowledge there was no work reported about rheological properties of CaCO3 mineralized hydrogel though some works have done on mineralization of CaCO3 in various gel membranes, and also it was reported about the viscoelastic properties of Agarose, Cellulose, PVA and PVPCMC hydrogels. This paper mainly focuses about the effect of strain on viscoelastic properties of fresh, swelled and mineralized (CaCO3) PVP-CMC hydrogel. All these three types of hydrogel sustain (or keep) strictly the elastic properties when low strain (1%) is applied, but at higher strain (10%) the viscoelastic moduli (G' and G") show significant change, and the nature of these materials turned from elastic to viscous.

  2. Oriented Attachment of Recombinant Proteins to Agarose-Coated Magnetic Nanoparticles by Means of a β-Trefoil Lectin Domain.

    PubMed

    Acebrón, Iván; Ruiz-Estrada, Amalia G; Luengo, Yurena; Morales, María Del Puerto; Guisán, José Manuel; Mancheño, José Miguel

    2016-11-16

    Design of generic methods aimed at the oriented attachment of proteins at the interfacial environment of magnetic nanoparticles currently represents an active field of research. With this in mind, we have prepared and characterized agarose-coated maghemite nanoparticles to set up a platform for the attachment of recombinant proteins fused to the β-trefoil lectin domain LSL150, a small protein that combines fusion tag properties with agarose-binding capacity. Analysis of the agarose-coated nanoparticles by dynamic light scattering, Fourier transform infrared spectroscopy, and thermogravimetric studies shows that decoupling particle formation from agarose coating provides better results in terms of coating efficiency and particle size distribution. LSL150 interacts with these agarose-coated nanoparticles exclusively through the recognition of the sugars of the polymer, forming highly stable complexes, which in turn can be dissociated ad hoc with the competing sugar lactose. Characterization of the complexes formed with the fusion proteins LSL-EGFP (LSL-tagged enhanced green fluorescent protein from Aquorea victoria) and LSL-BTL2 (LSL-tagged lipase from Geobacillus thermocatenolatus) provided evidence supporting a topologically oriented binding of these molecules to the interface of the agarose-coated nanoparticles. This is consistent with the marked polarity of the β-trefoil structure where the sugar-binding sites and the N- and C-terminus ends are at opposed sides. In summary, LSL150 displays topological and functional features expected from a generic molecular adaptor for the oriented attachment of proteins at the interface of agarose-coated nanoparticles.

  3. Hybrid hydrogel photonic barcodes for multiplex detection of tumor markers.

    PubMed

    Xu, Yueshuang; Zhang, Xiaoping; Luan, Chengxin; Wang, Huan; Chen, Baoan; Zhao, Yuanjin

    2017-01-15

    Barcodes-based suspension array have for demonstrated values in multiplex assay of tumor markers. Photonic barcodes which are encoded by their characteristic reflection peaks are the important supports for suspension array due to their stable code, low fluorescent background and high surface-volume ratio. Attempts to develop this technology tend to improve the function of the photonic barcodes. Here, we present a new type of hybrid hydrogel photonic barcodes for efficient multiplex assays. This photonic barcodes are hybrid inverse opal hydrogel composed of poly(ethylene glycol) diacrylate (PEG-DA) and agarose. The polymerized PEG-DA hydrogel could guarantee the stabilities of the inverse opal structure and its resultant code, while the agarose could offer active chemical groups for the probe immobilization and homogeneous water surrounding for the bioassay. In addition, the interconnected pores inverse opal structure could provide channels for biomolecules diffusing and reaction into the voids of barcodes. These features imparted the hybrid hydrogel photonic barcodes with limits of detection (LOD) of 0.78ng/mL for carcinoembryonic antigen (CEA) and 0.21ng/mL for α-fetoprotein (AFP), respectively. It was also demonstrated that the proposed barcodes showed acceptable accuracy and detection reproducibility, and the results were in acceptable agreement with those from common clinic method for the detections of practical clinical samples. Thus, our technique provides a new platform for simultaneous multiplex immunoassay.

  4. Supplementation of exogenous adenosine 5'-triphosphate enhances mechanical properties of 3D cell-agarose constructs for cartilage tissue engineering.

    PubMed

    Gadjanski, Ivana; Yodmuang, Supansa; Spiller, Kara; Bhumiratana, Sarindr; Vunjak-Novakovic, Gordana

    2013-10-01

    Formation of tissue-engineered cartilage is greatly enhanced by mechanical stimulation. However, direct mechanical stimulation is not always a suitable method, and the utilization of mechanisms underlying mechanotransduction might allow for a highly effective and less aggressive alternate means of stimulation. In particular, the purinergic, adenosine 5'-triphosphate (ATP)-mediated signaling pathway is strongly implicated in mechanotransduction within the articular cartilage. We investigated the effects of transient and continuous exogenous ATP supplementation on mechanical properties of cartilaginous constructs engineered using bovine chondrocytes and human mesenchymal stem cells (hMSCs) encapsulated in an agarose hydrogel. For both cell types, we have observed significant increases in equilibrium and dynamic compressive moduli after transient ATP treatment applied in the fourth week of cultivation. Continuous ATP treatment over 4 weeks of culture only slightly improved the mechanical properties of the constructs, without major changes in the total glycosaminoglycan (GAG) and collagen content. Structure-function analyses showed that transiently ATP-treated constructs, and in particular those based on hMSCs, had the highest level of correlation between compositional and mechanical properties. Transiently treated groups showed intense staining of the territorial matrix for GAGs and collagen type II. These results indicate that transient ATP treatment can improve functional mechanical properties of cartilaginous constructs based on chondrogenic cells and agarose hydrogels, possibly by improving the structural organization of the bulk phase and territorial extracellular matrix (ECM), that is, by increasing correlation slopes between the content of the ECM components (GAG, collagen) and mechanical properties of the construct.

  5. Agarose gel as biomaterial or scaffold for implantation surgery: characterization, histological and histomorphometric study on soft tissue response.

    PubMed

    Varoni, Elena; Tschon, Matilde; Palazzo, Barbara; Nitti, Paola; Martini, Lucia; Rimondini, Lia

    2012-01-01

    Maxillofacial, orthopedic, oral, and plastic surgery require materials for tissue augmentation, guided regeneration, and tissue engineering approaches. In this study, the aim was to develop and characterize a new extrudable hydrogel, based on agarose gel (AG; 1.5% wt) and to evaluate the local effects after subcutaneous implantation in comparison with collagen and hyaluronic acid. AG chemical-physical properties were ascertained through Fourier transform infrared (FT-IR) spectroscopy and rheological analysis. In vivo subcutaneous implants were performed, and histological and histomorphometric evaluations were done at 1, 4, 12, and 16 weeks. FT-IR confirmed that spectroscopic properties were the same for the baseline agarose and rheological characterization established that AG is a weak hydrogel. Subcutaneous AG implants induced new vessels and fibrous tissue formation rich in neutrophils; the capsule thickness around AG increased until the 12th week but remained thinner than those around hyaluronic acid and collagen. At 16 weeks, the thickness of the capsule significantly decreased around all materials. This study confirmed that 1.5% wt AG possesses some of the most important features of the ideal biocompatible material: safety, effectiveness, costless, and easily obtained with specific chemical and geometrical characters; the AG can represent a finely controllable and biodegradable polymeric system for cells and drug delivery applications.

  6. Hydrogels dispersed by doped rare earth fluoride nanocrystals: ionic liquid dispersion and down/up-conversion luminescence.

    PubMed

    Yan, Zhi-Yuan; Jia, Li-Ping; Yan, Bing

    2014-01-01

    Two typical kinds of rare earth fluoride nanocrystals codoped with rare earth ions (Eu(3+) and Tm(3+)/Er(3+),Yb(3+)) are synthesized and dispersed in ionic liquid compound (1-chlorohexane-3-methylimidazolium chloride, abbreviated as [C6mim][Cl]). Assisted by agarose, the luminescent hydrogels are prepared homogeneously. The down/up-conversion luminescence of these hydrogels can be realized for the dispersed rare earth fluoride nanocrystals. The results provide a strategy to prepare luminescent (especially up-conversion luminescent) hydrogels with ionic liquid to disperse rare earth fluoride nanocrystals.

  7. Agarose encapsulated mesoporous carbonated hydroxyapatite nanocomposites powder for drug delivery.

    PubMed

    Kolanthai, Elayaraja; Abinaya Sindu, P; Thanigai Arul, K; Sarath Chandra, V; Manikandan, E; Narayana Kalkura, S

    2017-01-01

    The powder composites are predominantly used for filling of voids in bone and as drug delivery carrier to prevent the infection or inflammatory reaction in the damaged tissues. The objective of this work was to study the synthesis of agarose encapsulation on carbonated hydroxyapatite powder and their biological and drug delivery properties. Mesoporous, nanosized carbonated hydroxyapatite/agarose (CHAp/agarose) powder composites were prepared by solvothermal method and subsequently calcined to study the physico-chemical changes, if it subjected to thermal exposure. The phase of the as-synthesized powder was CHAp/agarose whereas the calcinated samples were non-stoichiometric HAp. The CHAp/agarose nanorods were of length 10-80nm and width 40-190nm for the samples synthesized at temperatures 120°C (ST120) and 150°C (ST150). The calcination process produced spheres (10-50nm) and rods with reduced size (40-120nm length and 20-30nm width). Composites were partially dissolved in SBF solution followed by exhibited better bioactivity than non-stoichiometric HAp confirmed by gravimetric method. Hemo and biocompatibility remained unaffected by presence of agarose or carbonate in the HAp. Specific surface area of the composites was high and exhibited an enhanced amoxicillin and 5-fluorouracil release than the calcined samples. The composites demonstrated a strong antimicrobial activity against E. coli, S. aureus and S. epidermidis. The ST120 showed prolonged drug (AMX and 5-Fcil) release and antimicrobial efficacy than ST150 and calcined samples. This technique would be simple and rapid for composites preparation, to produce high quality crystalline, resorbable, mesoporous and bioactive nanocomposite (CHAp/agarose) powders. This work provides new insight into the role of agarose coated on bioceramics by solvothermal technique and suggests that CHAp/agarose composites powders are promising materials for filling of void in bone and drug delivery applications.

  8. Agarose gel electrophoresis for the separation of DNA fragments.

    PubMed

    Lee, Pei Yun; Costumbrado, John; Hsu, Chih-Yuan; Kim, Yong Hoon

    2012-04-20

    Agarose gel electrophoresis is the most effective way of separating DNA fragments of varying sizes ranging from 100 bp to 25 kb(1). Agarose is isolated from the seaweed genera Gelidium and Gracilaria, and consists of repeated agarobiose (L- and D-galactose) subunits(2). During gelation, agarose polymers associate non-covalently and form a network of bundles whose pore sizes determine a gel's molecular sieving properties. The use of agarose gel electrophoresis revolutionized the separation of DNA. Prior to the adoption of agarose gels, DNA was primarily separated using sucrose density gradient centrifugation, which only provided an approximation of size. To separate DNA using agarose gel electrophoresis, the DNA is loaded into pre-cast wells in the gel and a current applied. The phosphate backbone of the DNA (and RNA) molecule is negatively charged, therefore when placed in an electric field, DNA fragments will migrate to the positively charged anode. Because DNA has a uniform mass/charge ratio, DNA molecules are separated by size within an agarose gel in a pattern such that the distance traveled is inversely proportional to the log of its molecular weight(3). The leading model for DNA movement through an agarose gel is "biased reptation", whereby the leading edge moves forward and pulls the rest of the molecule along(4). The rate of migration of a DNA molecule through a gel is determined by the following: 1) size of DNA molecule; 2) agarose concentration; 3) DNA conformation(5); 4) voltage applied, 5) presence of ethidium bromide, 6) type of agarose and 7) electrophoresis buffer. After separation, the DNA molecules can be visualized under uv light after staining with an appropriate dye. By following this protocol, students should be able to: Understand the mechanism by which DNA fragments are separated within a gel matrix Understand how conformation of the DNA molecule will determine its mobility through a gel matrix Identify an agarose solution of appropriate

  9. Thermoreversible gelation in aqueous binary solvents of chemically modified agarose.

    PubMed

    Dahmani, Mohammed; Ramzi, Mohamed; Rochas, Cyrille; Guenet, Jean-Michel

    2003-01-15

    The thermoreversible gelation of chemically modified agarose has been studied in aqueous binary solvents (dimethyl sulfoxide and a series of formamide) by differential calorimetry, mechanical testing, and small-angle neutron scattering. The temperature-composition phase diagrams have been established. It is concluded that gelation is promoted by the formation of ternary complexes modified agarose/water/cosolvent, wherein the cosolvent mediates the interaction between chains through the formation of electrostatic interactions.

  10. Hydrogel Bioprinted Microchannel Networks for Vascularization of Tissue Engineering Constructs

    PubMed Central

    Bertassoni, Luiz E.; Cecconi, Martina; Manoharan, Vijayan; Nikkhah, Mehdi; Hjortnaes, Jesper; Cristino, Ana Luiza; Barabaschi, Giada; Demarchi, Danilo; Dokmeci, Mehmet R.; Yang, Yunzhi; Khademhosseini, Ali

    2014-01-01

    Vascularization remains a critical challenge in tissue engineering. The development of vascular networks within densely populated and metabolically functional tissues facilitate transport of nutrients and removal of waste products, thus preserving cellular viability over a long period of time. Despite tremendous progress in fabricating complex tissue constructs in the past few years, approaches for controlled vascularization within hydrogel based engineered tissue constructs have remained limited. Here, we report a three dimensional (3D) micromolding technique utilizing bioprinted agarose template fibers to fabricate microchannel networks with various architectural features within photo cross linkable hydrogel constructs. Using the proposed approach, we were able to successfully embed functional and perfusable microchannels inside methacrylated gelatin (GelMA), star poly (ethylene glycol-co-lactide) acrylate (SPELA), poly (ethylene glycol) dimethacrylate (PEGDMA) and poly (ethylene glycol) diacrylate (PEGDA) hydrogels at different concentrations. In particular, GelMA hydrogels were used as a model to demonstrate the functionality of the fabricated vascular networks in improving mass transport, cellular viability and differentiation within the cell-laden tissue constructs. In addition, successful formation of endothelial monolayers within the fabricated channels was confirmed. Overall, our proposed strategy represents an effective technique for vascularization of hydrogel constructs with useful applications in tissue engineering and organs on a chip. PMID:24860845

  11. Diffusion of macromolecules in agarose gels: comparison of linear and globular configurations.

    PubMed Central

    Pluen, A; Netti, P A; Jain, R K; Berk, D A

    1999-01-01

    The diffusion coefficients (D) of different types of macromolecules (proteins, dextrans, polymer beads, and DNA) were measured by fluorescence recovery after photobleaching (FRAP) both in solution and in 2% agarose gels to compare transport properties of these macromolecules. Diffusion measurements were conducted with concentrations low enough to avoid macromolecular interactions. For gel measurements, diffusion data were fitted according to different theories: polymer chains and spherical macromolecules were analyzed separately. As chain length increases, diffusion coefficients of DNA show a clear shift from a Rouse-like behavior (DG congruent with N0-0.5) to a reptational behavior (DG congruent with N0-2.0). The pore size, a, of a 2% agarose gel cast in a 0.1 M PBS solution was estimated. Diffusion coefficients of the proteins and the polymer beads were analyzed with the Ogston model and the effective medium model permitting the estimation of an agarose gel fiber radius and hydraulic permeability of the gels. Not only did flexible macromolecules exhibit greater mobility in the gel than did comparable-size rigid spherical particles, they also proved to be a more useful probe of available space between fibers. PMID:10388779

  12. DNA electrophoresis in agarose gels: A new mobility vs. DNA length dependence

    NASA Astrophysics Data System (ADS)

    Beheshti, Afshin

    2002-04-01

    Separations were performed on double stranded DNA (dsDNA) using electrophoresis. Electrophoresis is the steady transport of particles under the influence of an external electric field. Double stranded DNA fragments ranging in length from 200 base pairs (bp) to 194,000 bp (0.34 nm = 1 bp) were electrophoresed at agarose gel concentrations T = 0.4%--1.5%. The electric field was varied from 0.62 V/cm to 6.21 V/cm. A wide range of electric fields and gel concentrations were used to study the usefulness of a new interpolation equation, 1mL =1mL-( 1mL-1 ms)e-L/g , where mL,ms , and g are independent free fitting parameters. The long length mobility limit is interpreted as mL , the short length mobility limit is ms , and g is the crossover between the long length limit and the short length limit. This exponential relation fit very well (chi2 ≥ 0.999) when there are two smooth transitions observed in the "reptation plots" (plotting 3mL/m∘ vs. L) (J. Rousseau, G. Drouin, and G. W. Slater, Phys Rev Lett. 1997, 79, 1945--1948). Fits deviate from the data when three different slopes were observed in the reptation plots. Reptation plots were used to determine a phase diagram for dsDNA migration regimes. The phase diagrams define different regions where mechanisms for molecular transport affect the migration of dsDNA in agarose gels during electrophoresis. The parameters from the equation have also been interpreted to provide a physical description of the structure of the agarose gel by calculating the pore sizes. The relations between the values for the pore sizes and the phase diagrams are interpreted to better understand the migration of the DNA through agarose gels.

  13. Functionalized Agarose Self-Healing Ionogels Suitable for Supercapacitors.

    PubMed

    Trivedi, Tushar J; Bhattacharjya, Dhrubajyoti; Yu, Jong-Sung; Kumar, Arvind

    2015-10-12

    Agarose has been functionalized (acetylated/carbanilated) in an ionic liquid (IL) medium of 1-butyl-3-methylimidazolium acetate at ambient conditions. The acetylated agarose showed a highly hydrophobic nature, whereas the carbanilated agarose could be dissolved in water as well as in the IL medium. Thermoreversible ionogels were obtained by cooling the IL sols of carbanilated agarose at room temperature. The ionogel prepared from a protic-aprotic mixed-IL system (1-butyl-3-methylimidazolium chloride and N-(2-hydroxyethyl)ammonium formate) demonstrated a superior self-healing property, as confirmed from rheological measurements. The superior self-healing property of such an ionogel has been attributed to the unique inter-intra hydrogen-bonding network of functional groups inserted in the agarose. The ionogel was tested as a flexible solid electrolyte for an activated-carbon-based supercapacitor cell. The measured specific capacitance was found to be comparable with that of a liquid electrolyte system at room temperature and was maintained for up to 1000 charge-discharge cycles. Such novel functionalized-biopolymer self-healing ionogels with flexibility and good conductivity are desirable for energy-storage devices and electronic skins with superior lifespans and robustness.

  14. Self-assembled rosette nanotube/hydrogel composites for cartilage tissue engineering.

    PubMed

    Chen, Yupeng; Bilgen, Bahar; Pareta, Rajesh A; Myles, Andrew J; Fenniri, Hicham; Ciombor, Deborah McK; Aaron, Roy K; Webster, Thomas J

    2010-12-01

    Recently, hydrogels (alginate, agarose, polyethylene glycol, etc.) have been investigated as promising cartilage-healing materials. To further improve cell-material interactions or mechanical properties of such hydrogel scaffolds, many materials (such as ceramics or carbon nanotubes) have been added to produce composites with tailored properties. In this study, rosette nanotubes (RNTs, self-assembled nanotubes built from DNA base pairs), hydrogels, and cells (specifically, fibroblast-like type-B synoviocytes [SFB cells] and chondrocytes) were combined via a novel electrospinning technique to generate three-dimensional implantable scaffolds for cartilage repair. Importantly, results of this study showed that electrospun RNT/hydrogel composites improved both SFB cell and chondrocyte functions. RNT/hydrogel composites promoted SFB cell chondrogenic differentiation in 2 week culture experiments. Further, studies demonstrated that RNTs enhanced hydrogel adhesive strength to severed collagen. Results of this study thus provided a nanostructured scaffold that enhanced SFB cell adhesion, viability, and chondrogenic differentiation compared to nanosmooth hydrogels without RNTs. This study provided an alternative cartilage regenerative material derived from RNTs that could be directly electrospun into cartilage defects (with SFB cells and/or chondrocytes) to bond to severed collagen and promote cell adhesion, viability, and subsequent functions.

  15. Interpenetrating network formation in gellan--agarose gel composites.

    PubMed

    Amici, E; Clark, A H; Normand, V; Johnson, N B

    2000-01-01

    Thermal, mechanical, turbidity, and microscope evidence is provided which strongly suggests molecular interpenetrating network (IPN) formation by mixtures of the bacterial and seaweed polysaccharides gellan and agarose. There is no evidence for synergistic coupling of the networks, and simple phase separation (demixing) can definitely be ruled out. Some changes in the gellan gelling behavior are suggested, however, by the increased gellan effective concentrations implicit in cure curve data. The dependence of this effect on the agarose nominal concentration seems consistent with a previous model that focused on gelling parameters, and changes in these rather than real concentration effects. In large deformation mechanical tests, the influence of agarose added to gellan is to re-enforce the network (higher compression and shear moduli, higher stresses-to-break) without significantly changing the strain to break, or the gellan brittle failure mechanism.

  16. Spleen-specific suppression of TNF-alpha by cationic hydrogel-delivered antisense nucleotides for the prevention of arthritis in animal models.

    PubMed

    Dong, Lei; Xia, Suhua; Chen, Huan; Chen, Jiangning; Zhang, Junfeng

    2009-09-01

    This study developed a transplantable platform based on cationic hydrogels to deliver antisense oligodeoxynucleotides (ASOs) targeting the mRNA of TNF-alpha. Cationic agarose (c-agarose) was obtained by conjugating ethylenediamine to agarose via an N,N'-carbonyldiimidazole (CDI)-activation method. ASO-c-agarose system was constructed by mixing ASO in cationic agarose gel of proper concentration and gelation temperature. In vivo assessment of ASO distribution suggested that the system specifically target to spleen, wherein the c-agarose-delivered ASO had a concentration remarkably 50-fold higher than that of the naked ASO. The distribution of c-agarose-delivered ASO was scarcely detectable in liver and kidney. Next, three types of animal models were setup to evaluate the therapeutic efficacies of ASO-Gel, including the adjuvant-induced arthritis (AA), carrageen/lipopolysaccharide (LPS)-induced arthritis (CLA) and collagen-induced arthritis (CIA) models. The effects of ASO-c-agarose in alleviating inflammation and tissue destruction were evidenced in more than 90% of the testing animals, with decrease of main inflammatory cytokines, lightening of joint swelling and tissue damage, as well as increase in their body weights. All these findings suggest that this highly operable devise for the conveyance of antisense nucleotides together with its spleen-targeting property, could become a useful means of antisense-based therapeutics against rheumatoid arthritis and other diseases.

  17. Monolithic cryogels made of agarose-chitosan composite and loaded with agarose beads for purification of immunoglobulin G.

    PubMed

    Sun, Sijuan; Tang, Yuhai; Fu, Qiang; Liu, Xuan; Guo, Li'an; Zhao, Yanding; Chang, Chun

    2012-05-01

    In order to obtain a novel absorbent with high adsorption capacity for the purification of immunoglobulin G (IgG), continuous supermacroporous agarose beads embedded agarose-chitosan composite monolithic cryogels (agarose-chitosan cryogels) were prepared by cryo-copolymerization of agarose-chitosan blend solutions with glutaraldehyde as the crosslinker in the presence of agarose beads. After coupling 2-mercaptopyridine onto divinylsulfone-activated matrix, the obtained cryogels were used for the purification of IgG. The microstructure morphologies of the cryogels were analyzed by scanning electron microscopy. The results showed that the obtained cryogels possess interconnected pores of 10-100 μm size. The specific surface area was 350 m(2)/g with maximum adsorption capacity of IgG 71.4 mg/g. The cryogels showed workable stability, and can be reused at least 15 times without significant loss in adsorption capacity. IgG purity after one-step purification from human plasma was monitored by electrophoresis and the average recovery was estimated to be 90%.

  18. Evaluation of the friction coefficient, the radial stress, and the damage work during needle insertions into agarose gels.

    PubMed

    Urrea, Fabián A; Casanova, Fernando; Orozco, Gustavo A; García, José J

    2016-03-01

    Agarose hydrogels have been extensively used as a phantom material to mimic the mechanical behavior of soft biological tissues, e.g. in studies aimed to analyze needle insertions into the organs producing tissue damage. To better predict the radial stress and damage during needle insertions, this study was aimed to determine the friction coefficient between the material of commercial catheters and hydrogels. The friction coefficient, the tissue damage and the radial stress were evaluated at 0.2, 1.8, and 10mm/s velocities for 28, 30, and 32 gauge needles of outer diameters equal to 0.36, 0.31, and 0.23mm, respectively. Force measurements during needle insertions and retractions on agarose gel samples were used to analyze damage and radial stress. The static friction coefficient (0.295±0.056) was significantly higher than the dynamic (0.255±0.086). The static and dynamic friction coefficients were significantly smaller for the 0.2mm/s velocity compared to those for the other two velocities, and there was no significant difference between the friction coefficients for 1.8 and 10mm/s. Radial stress averages were 131.2±54.1, 248.3±64.2, and 804.9±164.3Pa for the insertion velocity of 0.2, 1.8, and 10mm/s, respectively. The radial stress presented a tendency to increase at higher insertion velocities and needle size, which is consistent with other studies. However, the damage work did not show to be a good predictor of tissue damage, which appears to be due to simplifications in the analytical model. Differently to other approaches, the method proposed here based on radial stress may be extended in future studies to quantity tissue damage in vivo along the entire needle track.

  19. Anomalous diffusion of poly(ethylene oxide) in agarose gels.

    PubMed

    Brenner, Tom; Matsukawa, Shingo

    2016-11-01

    We report on the effect of probe size and diffusion time of poly(ethylene) oxide in agarose gels. Time-dependence of the diffusion coefficient, reflecting anomalous diffusion, was observed for poly(ethylene) oxide chains with hydrodynamic radii exceeding about 20nm at an agarose concentration of 2%. The main conclusion is that the pore distribution includes pores that are only several nm across, in agreement with scattering reports in the literature. Interpretation of the diffusion coefficient dependence on the probe size based on a model of entangled rigid rods yielded a rod length of 72nm.

  20. Separation of long RNA by agarose-formaldehyde gel electrophoresis.

    PubMed

    Mansour, Farrah H; Pestov, Dimitri G

    2013-10-01

    We describe a method to facilitate electrophoretic separation of high-molecular-weight RNA species, such as ribosomal RNAs and their precursors, on agarose-formaldehyde gels. Two alternative "pK-matched" buffer systems were substituted for the traditionally used Mops-based conductive medium. The key advantages include shortened run times, a 5-fold reduction in formaldehyde concentration, a significantly improved resolution of long RNAs, and consistency in separation. The new procedure has a streamlined work flow that helps to minimize errors and is broadly applicable to agarose gel electrophoresis of RNA samples and their subsequent analysis by Northern blotting.

  1. Properties of cellulase immobilized on agarose gel with spacer

    SciTech Connect

    Chim-anage, P.; Kashiwagi, Y.; Magae, Y.; Ohta, T.; Sasaki, T.

    1986-12-01

    Cellulase produced by fungus Trichoderma viride was immobilized on agarose beads (Sepharose 4B) activated by cyanogen bromide and also on activated agarose beads that contained spacer arm (activated Ch-Sepharose 4B and Affi-Gel 15). The CMCase activity retained by immobilized cellulase on activated Sepharose containing the spacer tended to be higher than that immobilized without spacer, although the extent of protein immobilization was lower. Also, the higher substrate specificity for cellulase immobilized on beads with spacer was obtained for cellobiose, acid-swollen cellulose, or cellulose powder. The hydrolysis product from their substrates was mainly glucose. 10 references.

  2. Biomimetic Hydrogel Materials

    DOEpatents

    Bertozzi, Carolyn , Mukkamala, Ravindranath , Chen, Oing , Hu, Hopin , Baude, Dominique

    2003-04-22

    Novel biomimetic hydrogel materials and methods for their preparation. Hydrogels containing acrylamide-functionalized carbohydrate, sulfoxide, sulfide or sulfone copolymerized with a hydrophilic or hydrophobic copolymerizing material selected from the group consisting of an acrylamide, methacrylamide, acrylate, methacrylate, vinyl and a derivative thereof present in concentration from about 1 to about 99 wt %. and methods for their preparation. The method of use of the new hydrogels for fabrication of soft contact lenses and biomedical implants.

  3. Biomimetic hydrogel materials

    SciTech Connect

    Bertozzi, Carolyn; Mukkamala, Ravindranath; Chen, Qing; Hu, Hopin; Baude, Dominique

    2000-01-01

    Novel biomimetic hydrogel materials and methods for their preparation. Hydrogels containing acrylamide-functionalized carbohydrate, sulfoxide, sulfide or sulfone copolymerized with a hydrophilic or hydrophobic copolymerizing material selected from the group consisting of an acrylamide, methacrylamide, acrylate, methacrylate, vinyl and a derivative thereof present in concentration from about 1 to about 99 wt %. and methods for their preparation. The method of use of the new hydrogels for fabrication of soft contact lenses and biomedical implants.

  4. Antifouling properties of hydrogels

    NASA Astrophysics Data System (ADS)

    Murosaki, Takayuki; Ahmed, Nafees; Gong, Jian Ping

    2011-12-01

    Marine sessile organisms easily adhere to submerged solids such as rocks, metals and plastics, but not to seaweeds and fishes, which are covered with soft and wet 'hydrogel'. Inspired by this fact, we have studied long-term antifouling properties of hydrogels against marine sessile organisms. Hydrogels, especially those containing hydroxy group and sulfonic group, show excellent antifouling activity against barnacles both in laboratory assays and in the marine environment. The extreme low settlement on hydrogels in vitro and in vivo is mainly caused by antifouling properties against the barnacle cypris.

  5. Hydrogel Actuation by Electric Field Driven Effects

    NASA Astrophysics Data System (ADS)

    Morales, Daniel Humphrey

    Hydrogels are networks of crosslinked, hydrophilic polymers capable of absorbing and releasing large amounts of water while maintaining their structural integrity. Polyelectrolyte hydrogels are a subset of hydrogels that contain ionizable moieties, which render the network sensitive to the pH and the ionic strength of the media and provide mobile counterions, which impart conductivity. These networks are part of a class of "smart" material systems that can sense and adjust their shape in response to the external environment. Hence, the ability to program and modulate hydrogel shape change has great potential for novel biomaterial and soft robotics applications. We utilized electric field driven effects to manipulate the interaction of ions within polyelectrolyte hydrogels in order to induce controlled deformation and patterning. Additionally, electric fields can be used to promote the interactions of separate gel networks, as modular components, and particle assemblies within gel networks to develop new types of soft composite systems. First, we present and analyze a walking gel actuator comprised of cationic and anionic gel legs attached by electric field-promoted polyion complexation. We characterize the electro-osmotic response of the hydrogels as a function of charge density and external salt concentration. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices in aqueous solutions. An 'ionoprinting' technique is presented with the capability to topographically structure and actuate hydrated gels in two and three dimensions by locally patterning ions induced by electric fields. The bound charges change the local mechanical properties of the gel to induce relief patterns and evoke localized stress, causing rapid folding in air. The ionically patterned hydrogels exhibit programmable temporal and spatial shape transitions which can be tuned by the duration and/or strength of

  6. Agarose coated spherical micro resonator for humidity measurements.

    PubMed

    Mallik, Arun Kumar; Liu, Dejun; Kavungal, Vishnu; Wu, Qiang; Farrell, Gerald; Semenova, Yuliya

    2016-09-19

    A new type of fiber optic relative humidity (RH) sensor based on an agarose coated silica microsphere resonator is proposed and experimentally demonstrated. Whispering gallery modes (WGMs) in the micro resonator are excited by evanescent coupling using a tapered fiber with ~3.3 µm waist diameter. A change in the relative humidity of the surrounding the resonator air induces changes in the refractive index (RI) and thickness of the Agarose coating layer. These changes in turn lead to a spectral shift of the WGM resonances, which can be related to the RH value after a suitable calibration. Studies of the repeatability, long-term stability, measurement accuracy and temperature dependence of the proposed sensor are carried out. The RH sensitivity of the proposed sensor depends on the concentration of the agarose gel which determines the initial thickness of the deposited coating layer. Studies of the micro- resonators with coating layers fabricated from gels with three different Agarose concentrations of 0.5%, 1.125% and 2.25 wt./vol.% showed that an increase in the initial thickness of the coating material results in an increase in sensitivity but also leads to a decrease of quality factor (Q) of the micro resonator. The highest sensitivity achieved in our experiments was 518 pm/%RH in the RH range from 30% to 70%. The proposed sensor offers the advantages of a very compact form factor, low hysteresis, good repeatability, and low cross sensitivity to temperature.

  7. Quaternary ammonium substituted agarose as surface coating for capillary electrophoresis.

    PubMed

    Ullsten, Sara; Söderberg, Lennart; Folestad, Staffan; Markides, Karin E

    2004-05-01

    A novel positively charged polymer of quaternary ammonium substituted agarose (Q-agarose) has been synthesized and explored for use as a coating in capillary electrophoresis. The fast and simple coating procedure is based on a multi-site electrostatic interaction between the polycationic agarose polymer and the negatively charged fused-silica surface. By simply flushing fused-silica capillaries with hot polymer solution a positively charged, hydrophilic deactivation layer is achieved. The polymer surface provides an intermediate electroosmotic flow of reversed direction, over a range of pH 2-11, compared to unmodified fused-silica. The coating procedure was highly reproducible with an RSD of 4%, evaluated as the electroosmotic flow mobility for 30 capillaries prepared at 10 different occasions. The application of Q-agarose coated capillaries in separation science was investigated using a set of basic drugs and model proteins and peptides. Due to the intermediate electroosmotic flow generated, the resolution of basic drugs could be increased, compared to using bare fused-silica capillaries. Moreover, the coating enabled separation of proteins and peptides with efficiencies up to 300.000 plates m(-1).

  8. A constitutive model of nanocomposite hydrogels with nanoparticle crosslinkers

    NASA Astrophysics Data System (ADS)

    Wang, Qiming; Gao, Zheming

    2016-09-01

    Nanocomposite hydrogels with only nanoparticle crosslinkers exhibit extraordinarily higher stretchability and toughness than the conventional organically crosslinked hydrogels, thus showing great potential in the applications of artificial muscles and cartilages. Despite their potential, the microscopic mechanics details underlying their mechanical performance have remained largely elusive. Here, we develop a constitutive model of the nanoparticle hydrogels to elucidate the microscopic mechanics behaviors, including the microarchitecture and evolution of the nanoparticle crosslinked polymer chains during the mechanical deformation. The constitutive model enables us to understand the Mullins effect of the nanocomposite hydrogels, and the effects of nanoparticle concentrations and sizes on their cyclic stress-strain behaviors. The theory is quantitatively validated by the tensile tests on a nanocomposite hydrogel with nanosilica crosslinkers. The theory can also be extended to explain the mechanical behaviors of existing hydrogels with nanoclay crosslinkers, and the necking instability of the composite hydrogels with both nanoparticle crosslinkers and organic crosslinkers. We expect that this constitutive model can be further exploited to reveal mechanics behaviors of novel particle-polymer chain interactions, and to design unprecedented hydrogels with both high stretchability and toughness.

  9. Synthesis and characterization of a chitosan based nanocomposite injectable hydrogel.

    PubMed

    Wang, Qianqian; Chen, Dajun

    2016-01-20

    The aim of the current study was to enhance the mechanical property of chitosan/β-glycerophosphate disodium salt (CS/GP) injectable hydrogels. A novel nanocomposite injectable hydrogel was prepared by introducing attapulgite (ATP) nano particles into the CS/GP hydrogels. The mechanical properties of the composite hydrogels with two different water contents were characterized by tensile test, the results shown that the tensile strength and elongation at break of composite hydrogels both increased obviously with increasing of ATP content. And, in our testing range, the maximum values of tensile strength and elongation at break were both more than 5 times larger than that of neat CS/GP hydrogel. We discussed this enhancement effect in detail by Scanning electron microscope observations (SEM) and Fourier transform infrared spectroscopy testing (FT-IR). The SEM images of composite hydrogels shown quite different from the neat CS/GP hydrogel, where the pores were more tightly and with some uniform and smaller holes dispersed on the wall. FT-IR test results revealed that the introduction of ATP increased the cross-link density because of the hydrogen bonds formation between ATP nanoparticles and CS molecules. Also, we studied the impact of ATP introduction on gelation speed through tracking the dynamic process of the sol-gel transition by means of rheological measurement, and the results shown that the reaction rate increased significantly with the increase of ATP concentration.

  10. Composites of Polymer Hydrogels and Nanoparticulate Systems for Biomedical and Pharmaceutical Applications

    PubMed Central

    Zhao, Fuli; Yao, Dan; Guo, Ruiwei; Deng, Liandong; Dong, Anjie; Zhang, Jianhua

    2015-01-01

    Due to their unique structures and properties, three-dimensional hydrogels and nanostructured particles have been widely studied and shown a very high potential for medical, therapeutic and diagnostic applications. However, hydrogels and nanoparticulate systems have respective disadvantages that limit their widespread applications. Recently, the incorporation of nanostructured fillers into hydrogels has been developed as an innovative means for the creation of novel materials with diverse functionality in order to meet new challenges. In this review, the fundamentals of hydrogels and nanoparticles (NPs) were briefly discussed, and then we comprehensively summarized recent advances in the design, synthesis, functionalization and application of nanocomposite hydrogels with enhanced mechanical, biological and physicochemical properties. Moreover, the current challenges and future opportunities for the use of these promising materials in the biomedical sector, especially the nanocomposite hydrogels produced from hydrogels and polymeric NPs, are discussed. PMID:28347111

  11. Modification of agarose with carboxylation and grafting dopamine for promotion of its cell-adhesiveness.

    PubMed

    Su, Yixue; Chu, Bin; Gao, Yuan; Wu, Chaoxi; Zhang, Lingmin; Chen, Peng; Wang, Xiaoying; Tang, Shunqing

    2013-02-15

    In order to improve bioactivity of agarose, we modified agarose by carboxylation and grafting dopamine. Under alkaline condition, carboxylated agarose was prepared using 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation system by oxidizing C(6) hydroxyl on D-galactose ring into carboxyl group, and the maximum value of the degree of carboxylation reached 30%. With the increase of the amount of oxidant, the molecular weight of the carboxylated agarose decreased to 4 kDa by gel permeation chromatography (GPC) measure. Carboxylated agarose reacted with dopamine through EDC condensation reaction to obtain agarose grafting dopamine (Ag-g-DA), and the grafting rate of dopamine was determined to be 9.3% by UV spectroscopy at 280 nm. The structures of these modified agaroses were determined by FT-IR and (13)C NMR. Both carboxylated agarose and Ag-g-DA showed no cytotoxicity and promoted cell-adhesiveness.

  12. Tissue responses against tissue-engineered cartilage consisting of chondrocytes encapsulated within non-absorbable hydrogel.

    PubMed

    Kanazawa, Sanshiro; Fujihara, Yuko; Sakamoto, Tomoaki; Asawa, Yukiyo; Komura, Makoto; Nagata, Satoru; Takato, Tsuyoshi; Hoshi, Kazuto

    2013-01-01

    To disclose the influence of foreign body responses raised against a non-absorbable hydrogel consisting of tissue-engineered cartilage, we embedded human/canine chondrocytes within agarose and transplanted them into subcutaneous pockets in nude mice and donor beagles. One month after transplantation, cartilage formation was observed in the experiments using human chondrocytes in nude mice. No significant invasion of blood cells was noted in the areas where the cartilage was newly formed. Around the tissue-engineered cartilage, agarose fragments, a dense fibrous connective tissue and many macrophages were observed. On the other hand, no cartilage tissue was detected in the autologous transplantation of canine chondrocytes. Few surviving chondrocytes were observed in the agarose and no accumulation of blood cells was observed in the inner parts of the transplants. Localizations of IgG and complements were noted in areas of agarose, and also in the devitalized cells embedded within the agarose. Even if we had inhibited the proximity of the blood cells to the transplanted cells, the survival of the cells could not be secured. We suggest that these cytotoxic mechanisms seem to be associated not only with macrophages but also with soluble factors, including antibodies and complements.

  13. The complete enzymatic saccharification of agarose and its application to simultaneous saccharification and fermentation of agarose for ethanol production.

    PubMed

    Kim, Hee Taek; Lee, Saeyoung; Kim, Kyoung Heon; Choi, In-Geol

    2012-03-01

    A sugar platform equipped with acetic acid, multiple agarases and neoagarobiose hydrolase (NABH) converted recalcitrant agar polysaccharide into monosugars, which was evaluated by simultaneous saccharification and fermentation (SSF). The sugar platform was divided into chemical liquefaction and enzymatic saccharification. The chemical liquefaction was carried out in mild conditions (using a dilute acetic acid at 80°C for 1-6h) to avoid the production of fermentation inhibitors and hence the highest degree of liquefaction of 95.6% (w/w) was obtained. We mimicked the natural agarolytic pathway using three microbial agarases (Aga16B, Aga50D and DagA) and NABH, and the enzyme system converted 79.1% of agarose to monosugars. The chemical liquefaction and SSF of 30 g/l agarose resulted in 4.4 g/l ethanol concentration and 49.3% of the theoretical ethanol yield to d-galactose. This is the first report on the complete enzymatic conversion of agarose into its monosugars and the SSF of agarose into ethanol.

  14. Hydrogels Constructed from Engineered Proteins.

    PubMed

    Li, Hongbin; Kong, Na; Laver, Bryce; Liu, Junqiu

    2016-02-24

    Due to their various potential biomedical applications, hydrogels based on engineered proteins have attracted considerable interest. Benefitting from significant progress in recombinant DNA technology and protein engineering/design techniques, the field of protein hydrogels has made amazing progress. The latest progress of hydrogels constructed from engineered recombinant proteins are presented, mainly focused on biorecognition-driven physical hydrogels as well as chemically crosslinked hydrogels. The various bio-recognition based physical crosslinking strategies are discussed, as well as chemical crosslinking chemistries used to engineer protein hydrogels, and protein hydrogels' various biomedical applications. The future perspectives of this fast evolving field of biomaterials are also discussed.

  15. Microscale Strategies for Generating Cell-Encapsulating Hydrogels

    PubMed Central

    Selimović, Šeila; Oh, Jonghyun; Bae, Hojae; Dokmeci, Mehmet; Khademhosseini, Ali

    2013-01-01

    Hydrogels in which cells are encapsulated are of great potential interest for tissue engineering applications. These gels provide a structure inside which cells can spread and proliferate. Such structures benefit from controlled microarchitectures that can affect the behavior of the enclosed cells. Microfabrication-based techniques are emerging as powerful approaches to generate such cell-encapsulating hydrogel structures. In this paper we introduce common hydrogels and their crosslinking methods and review the latest microscale approaches for generation of cell containing gel particles. We specifically focus on microfluidics-based methods and on techniques such as micromolding and electrospinning. PMID:23626908

  16. Hypoxia-Inducible Hydrogels

    PubMed Central

    Park, Kyung Min; Gerecht, Sharon

    2014-01-01

    Oxygen is vital for the existence of all multicellular organisms, acting as a signaling molecule regulating cellular activities. Specifically, hypoxia, which occurs when the partial pressure of oxygen falls below 5%, plays a pivotal role during development, regeneration, and cancer. Here we report a novel hypoxia-inducible (HI) hydrogel composed of gelatin and ferulic acid that can form hydrogel networks via oxygen consumption in a laccase-mediated reaction. Oxygen levels and gradients within the hydrogels can be accurately controlled and precisely predicted. We demonstrate that HI hydrogels guide vascular morphogenesis in vitro via hypoxia-inducible factors activation of matrix metalloproteinases and promote rapid neovascularization from the host tissue during subcutaneous wound healing. The HI hydrogel is a new class of biomaterials that may prove useful in many applications, ranging from fundamental studies of developmental, regenerative and disease processes through the engineering of healthy and diseased tissue models towards the treatment of hypoxia-regulated disorders. PMID:24909742

  17. Radiation synthesis and characterization of nanosilver/gelatin/carboxymethyl chitosan hydrogel

    NASA Astrophysics Data System (ADS)

    Zhou, Ying; Zhao, Yinghui; Wang, Lu; Xu, Ling; Zhai, Maolin; Wei, Shicheng

    2012-05-01

    A series of antibacterial hydrogels were fabricated from an aqueous solution of AgNO3, gelatin and carboxymethyl chitosan (CM-chitosan) by radiation-induced reduction and crosslinking at ambient temperature. The nanosilver particles were in situ synthesized accompanying with the formation of gelatin/CM-chitosan hydrogel. Transmission Electron Microscope and UV-vis analysis have verified the formation and homogeneous distribution of nanosilver particles in the hydrogel matrix. The nanosilver/gelatin/CM-chitosan hydrogels possessed interconnected porous structure, had a compressive modulus of 44 to 56 kPa, and could absorb 62 to 108 times of deionized water to its dry weight. Furthermore, the hydrogels were found to have sound antibacterial effect on Escherichia coli (E. coli), and their antibacterial ability could be significantly enhanced by the increasing of AgNO3 content. The comprehensive results of this study suggest that nanosilver/gelatin/CM-chitosan hydrogels have potential as an antibacterial wound dressing.

  18. Synthesis and patterning of hydrogel-nanoparticle composites.

    SciTech Connect

    Martin, L. A.; Mancini, D. C.; Rich, L. E.; Divan, R.; Center for Nanoscale Materials; Missouri Univ. of Science and Technology

    2008-01-01

    We have developed a novel method for patterning nanoscale composite hydrogel materials on silicon through electron beam lithography. Gold particles were introduced into poly N-isopropylacrylamide (PNIPAam) patterned by e-beam lithography. By including BAC, the polymer can covalently bond to the colloidal gold nanoparticles. Such composites can be stable for long periods of time. We describe the structure, quality, and properties of the resulting patterned hydrogel-nanoparticle composite films.

  19. Polymerization of hydrogels inside self-assembled block copolymer vesicles.

    PubMed

    Gaspard, Jeffery; Hahn, Mariah S; Silas, James A

    2009-11-17

    Block copolymer vesicles are powerful tools for investigating cell adhesion since they display the fluid, deformable, semipermeable membrane properties of lipid vesicles while having greater chemical and mechanical stability. The aim of the present study was to fabricate block copolymer vesicles containing hydrogel interiors in order to extend achievable vesicle properties and, thereby, their range of cell-like behaviors. Block copolymer vesicles based on poly(butadiene-b-ethylene oxide) were demonstrated to compartmentalize and retain acrylamide solutions through particle dialysis and to allow for subsequent in situ hydrogel polymerization. Small molecule leakage studies of the resulting particles indicated that the cross-link density of the hydrogel interiors had minimal impact on vesicle permeability to small molecules (<430 Da) relative to vesicle membrane properties. In contrast, particle deformation analyses indicated that initial vesicle surface approach and adhesion was dominated by its membrane properties, whereas its ultimate deformation was primarily governed by the hydrogel interior. Thus, the hydrogel-containing vesicles allowed orthogonal control of particle surface and mechanical properties. Analysis of particle behavior in terms of Gibb's free energy minimization indicated that vesicle adhesion energy, membrane tension, and internal osmotic pressure dominated particle adhesion and deformation. Combined, the present work demonstrates the potential for designing compartmentalized, hierarchical polymer-based cell mimics with broadly tunable dynamic-mechanical properties and surface properties.

  20. Cytoplasmic polyhedrosis virus classification by electropherotype; validation by serological analyses and agarose gel electrophoresis.

    PubMed

    Mertens, P P; Crook, N E; Rubinstein, R; Pedley, S; Payne, C C

    1989-01-01

    Serological analyses of several different cytoplasmic polyhedrosis viruses (CPVs), including two type 1 CPVs from Bombyx mori, type 1 CPV from Dendrolimus spectabilis, type 12 CPV from Autographa gamma, type 2 CPV from Inachis io, type 5 CPV from Orgyia pseudotsugata and type 5 CPV from Heliothis armigera, demonstrated a close correlation between the antigenic properties of the polyhedrin or virus particle structural proteins and the genomic dsRNA electropherotypes. The dsRNAs of these viruses were analysed by electrophoresis in 3% and 10% polyacrylamide gels with a discontinuous Tris-HCl/Tris-glycine buffer system or by 1% agarose gel electrophoresis using a continuous Tris-acetate-EDTA buffer system. Electrophoretic analysis in agarose gels was found to be the most suitable for the classification of CPV isolates into electropherotypes, and the results obtained showed a close correlation with the observed antigenic relationships between different virus isolates. However, electrophoretic analysis in 10% polyacrylamide gels was most sensitive for the detection of intra-type variation and the presence of mixed virus isolates.

  1. Responsive Hydrogel Nanoparticles for Pulmonary Delivery.

    PubMed

    Stocke, Nathanael A; Arnold, Susanne M; Hilt, J Zach

    2015-10-01

    Nanoparticles represent one of the most widely studied classes of advanced drug delivery platforms in recent years due to a wide range of unique properties and capabilities that can be utilized to improve upon traditional drug administration. Conversely, hydrogel nanoparticles (HNPs) - also called nanogels - represent a unique class of materials that combine the intrinsic advantages of nanotechnology with the inherent capabilities of hydrogels. Responsive hydrogels pose a particularly interesting class of materials that can sense and respond to external stimuli and previous reports of inhalable hydrogel particles have highlighted their potential in pulmonary delivery. Here, we synthesized two different pH-responsive HNPs, designated HNP120 and HNP270, by incorporating functional monomers with a common crosslinker and characterized their physicochemical properties. One of the HNP systems was selected for incorporation into a composite dry powder by spray drying, and the aerodynamic performance of the resulting powder was evaluated. The HNP120s displayed a hydrodynamic diameter of approximately 120 nm in their fully swollen state and a minimal diameter of around 80 nm while the HNP270s were approximately 270 nm and 115 nm, respectively. Electron microscopy confirmed particle size- and morphological uniformity of the HNPs. The HNP120s were spray dried into composite dry powders for inhalation and cascade impaction studies showed good aerosol performance with a mass median aerosol diameter (MMAD) of 4.82 ± 0.37 and a fine particle fraction > 30%. The HNPs released from the spray dried composites retained their responsive behavior thereby illustrating the potential for these materials as intelligent drug delivery systems that combine the advantages of nanotechnology, lung targeting through pulmonary delivery, and stimuli-responsive hydrogels.

  2. Blood grouping based on PCR methods and agarose gel electrophoresis.

    PubMed

    Sell, Ana Maria; Visentainer, Jeane Eliete Laguila

    2015-01-01

    The study of erythrocyte antigens continues to be an intense field of research, particularly after the development of molecular testing methods. More than 300 specificities have been described by the International Society for Blood Transfusion as belonging to 33 blood group systems. The polymerase chain reaction (PCR) is a central tool for red blood cells (RBC) genotyping. PCR and agarose gel electrophoresis are low cost, easy, and versatile in vitro methods for amplifying defined target DNA (RBC polymorphic region). Multiplex-PCR, AS-PCR (Specific Allele Polymerase Chain Reaction), and RFLP-PCR (Restriction Fragment Length Polymorphism-Polymerase Chain Reaction) techniques are usually to identify RBC polymorphisms. Furthermore, it is an easy methodology to implement. This chapter describes the PCR methodology and agarose gel electrophoresis to identify the polymorphisms of the Kell, Duffy, Kidd, and MNS blood group systems.

  3. Electric birefrigence imaging of DNA in agarose electrophoresis gels

    SciTech Connect

    Lanan, M.

    1992-01-01

    Electric birefringence imaging (EBI) provides sensitive, non-invasive detection of double-stranded DNA in agarose gels. Quasi-monochromatic, visible light is transmitted through an electrophoresis gel which is placed between plastic film polarizers. A slow-scan video camera equipped with a 12 bit A/D converter records the images. Under electrophoresis running conditions, hydrodynamically-induced gel distortion is shown to be the major source of birefringence for fragments smaller than 23 kbp. The birefringence generated approximates the DNA concentration gradient in the electric field direction. The stress-optic coefficient of 1% agarose gel is measured by mechanical compression and used to evaluate the magnitude of the induced stress on the gel during electrophoresis. Multi-linear regression analysis is used to quantitatively test the model for EBI signals. Birefringence attributed to localized electrokinetic gel distortion and to intrinsic DNA birefringence is studied by fitting ethidium bromide fluorescence profiles to EBI results. Fluorescence polarization imaging is used to assess the influence of localized gel distortion on nucleic acid orientation across a fragment band. It is shown that DNA aligns parallel, on average, with an applied electric field independent of its location within a band. Both EBI sensitivity and quantitation are improved through image processing techniques which separate the DNA Kerr effect and induced electrokinetic distortion contributions. Under standard electrophoresis conditions, detection limits of 8 ng DNA per well are obtained in hydroxyethylated agarose without signal averaging. Maintaining constant gel temperature is shown to improve the quality of the images. Stress patterns in agarose gels during DC and field-inversion gel electrophoresis (FIGE) of nucleic acid fragments of varying sizes are mapped using EBI. In addition, online EBI monitoring during FIGE of megabase pair DNA size standards is demonstrated.

  4. Contemporary issues in hydrogels research

    SciTech Connect

    Peppas, N.A.

    1993-12-31

    The last ten years has seen an explosion in hydrogels research, the result of improved understanding of the structure and behavior of these water-swollen, crosslinked polymers. After the early developments of Flory And Katchalsky in the 1940s, the great Czechoslovakian researchers of the 1960s and Andrade, Hoffman, Ratner and Merrill of the early 1970s, hydrogels have again attracted significant research interest, especially through the imaginative research of Tanaka in the 1980s and others. Eight general areas of contemporary research in hydrogels are identified: (i) kinetic analysis of the copolymerization/crosslinking reactions used in hydrogel preparation; (ii) gelation and percolation theories; (iii) novel methods for tailor-made copolymers with desirable functional groups, or biodegradable chains; (iv) biomimetic hydrogels; (V) hydrogels of controlled porous structure; (vi) ultrapure hydrogels devoid of crosslinking agents, emulsifiers, etc.; (vii) critical phenomena in hydrogels; and (viii) behavior of anionic, cationic and amphiphilic hydrogels.

  5. Posing for a picture: vesicle immobilization in agarose gel

    PubMed Central

    Lira, Rafael B.; Steinkühler, Jan; Knorr, Roland L.; Dimova, Rumiana; Riske, Karin A.

    2016-01-01

    Taking a photo typically requires the object of interest to stand still. In science, imaging is potentiated by optical and electron microscopy. However, living and soft matter are not still. Thus, biological preparations for microscopy usually include a fixation step. Similarly, immobilization strategies are required for or substantially facilitate imaging of cells or lipid vesicles, and even more so for acquiring high-quality data via fluorescence-based techniques. Here, we describe a simple yet efficient method to immobilize objects such as lipid vesicles with sizes between 0.1 and 100 μm using agarose gel. We show that while large and giant unilamellar vesicles (LUVs and GUVs) can be caged in the pockets of the gel meshwork, small molecules, proteins and micelles remain free to diffuse through the gel and interact with membranes as in agarose-free solutions, and complex biochemical reactions involving several proteins can proceed in the gel. At the same time, immobilization in agarose has no adverse effect on the GUV size and stability. By applying techniques such as FRAP and FCS, we show that the lateral diffusion of lipids is not affected by the gel. Finally, our immobilization strategy allows capturing high-resolution 3D images of GUVs. PMID:27140695

  6. Posing for a picture: vesicle immobilization in agarose gel

    NASA Astrophysics Data System (ADS)

    Lira, Rafael B.; Steinkühler, Jan; Knorr, Roland L.; Dimova, Rumiana; Riske, Karin A.

    2016-05-01

    Taking a photo typically requires the object of interest to stand still. In science, imaging is potentiated by optical and electron microscopy. However, living and soft matter are not still. Thus, biological preparations for microscopy usually include a fixation step. Similarly, immobilization strategies are required for or substantially facilitate imaging of cells or lipid vesicles, and even more so for acquiring high-quality data via fluorescence-based techniques. Here, we describe a simple yet efficient method to immobilize objects such as lipid vesicles with sizes between 0.1 and 100 μm using agarose gel. We show that while large and giant unilamellar vesicles (LUVs and GUVs) can be caged in the pockets of the gel meshwork, small molecules, proteins and micelles remain free to diffuse through the gel and interact with membranes as in agarose-free solutions, and complex biochemical reactions involving several proteins can proceed in the gel. At the same time, immobilization in agarose has no adverse effect on the GUV size and stability. By applying techniques such as FRAP and FCS, we show that the lateral diffusion of lipids is not affected by the gel. Finally, our immobilization strategy allows capturing high-resolution 3D images of GUVs.

  7. Antifouling properties of hydrogels

    PubMed Central

    Murosaki, Takayuki; Ahmed, Nafees; Ping Gong, Jian

    2011-01-01

    Marine sessile organisms easily adhere to submerged solids such as rocks, metals and plastics, but not to seaweeds and fishes, which are covered with soft and wet ‘hydrogel’. Inspired by this fact, we have studied long-term antifouling properties of hydrogels against marine sessile organisms. Hydrogels, especially those containing hydroxy group and sulfonic group, show excellent antifouling activity against barnacles both in laboratory assays and in the marine environment. The extreme low settlement on hydrogels in vitro and in vivo is mainly caused by antifouling properties against the barnacle cypris. PMID:27877456

  8. Giant unilamellar vesicles formed by hybrid films of agarose and lipids display altered mechanical properties.

    PubMed

    Lira, Rafael B; Dimova, Rumiana; Riske, Karin A

    2014-10-07

    Giant unilamellar vesicles (GUVs) are presumably the current most popular biomimetic membrane model. Preparation of GUVs in physiological conditions using the classical electroformation method is challenging. To circumvent these difficulties, a new method was recently reported, by which GUVs spontaneously swell from hybrid films of agarose and lipids. However, agarose is left encapsulated in the vesicles in different amounts. In this work, we thoroughly characterize the mechanical properties of these agarose-GUVs in response to electric pulses, which induce vesicle deformation and can lead to membrane poration. We show that the relaxation dynamics of deformed vesicles, both in the presence and absence of poration, is significantly slowed down for agarose-GUVs when compared to agarose-free GUVs. In the presence of poration, agarose polymers prevent complete pore closure and lead to high membrane permeability. A fraction of the vesicles were found to encapsulate agarose in the form of a gel-like meshwork. These vesicles rupture and open up after electroporation and the meshwork is expelled through a macropore. When the agarose-GUVs are heated above the melting temperature of agarose for 2 h before use, vesicle response is (partially) recovered due to substantial release of encapsulated agarose during temperature treatment. Our findings reveal potential artifactual behavior of agarose-GUVs in processes involving morphological changes in the membrane as well as poration.

  9. Disease proteomics of high-molecular-mass proteins by two-dimensional gel electrophoresis with agarose gels in the first dimension (Agarose 2-DE).

    PubMed

    Oh-Ishi, Masamichi; Maeda, Tadakazu

    2007-04-15

    Agarose gel is the preferred electrophoretic medium currently used for separating high molecular mass (HMM) proteins (MW>100 kDa). Agarose gels are widely used for both SDS-agarose gel electrophoresis and agarose isoelectric focusing (IEF). A two-dimensional gel electrophoresis method employing agarose gels in the first dimension (agarose 2-DE) that is sufficiently good at separating up to 1.5mg of HMM proteins with molecular masses as large as 500 kDa has been used to separate proteins from various diseased tissues and cells. Although resolution of the agarose 2-DE pattern always depends on the tissue being analyzed, sample preparation procedures including (i) protein extraction with an SDS sample buffer; (ii) ultracentrifugation of a tissue homogenate; and (iii) 1% SDS in both stacking and separation gels of the second-dimension SDS-PAGE gel, are generally effective for HMM protein detection. In a comprehensive prostate cancer proteome study using agarose 2-DE, the HMM region of the gel was rich in proteins of particular gene/protein expression groups (39.1% of the HMM proteins but only 28.4% of the LMM ones were classified as transcription/translation-related proteins). Examples include transcription factors, DNA or RNA binding proteins, and ribosomal proteins. To understand oxidative stress-induced cellular damage at the protein level, a novel proteomic method, in which protein carbonyls were derivatized with biotin hydrazide followed by agarose 2-DE, was useful for detecting HMM protein carbonyls in tissues of both a diabetes model Ostuka Long-Evans Tokushima Fatty (OLETF) rat and a control Long-Evans Tokushima Otsuka (LETO) rat. In this paper, we review the use of agarose gels for separation of HMM proteins and disease proteomics of HMM proteins in general, with particular attention paid to our proteome analyzes based on the use of agarose 2-DE for protein separation followed by the use of mass spectrometry for protein identification.

  10. The Effect of Swelling Ratio on the Coulter Underestimation of Hydrogel Microsphere Diameters

    PubMed Central

    Pellegrini, Michael; Cherukupalli, Abhimanyu; Medini, Michael; Falkowski, Ron

    2015-01-01

    It has been demonstrated that the diameters of porous particles are underestimated by Coulter measurements. This phenomenon has also been observed in hydrogel particles, but not characterized. Since the Coulter principle uses the displacement of electrolyte to determine particle size, electrolyte contained within the swelled hydrogel microparticles results in an underestimate of actual particle diameters. The increased use of hydrogel microspheres in biomedical applications has led to the increased application of the Coulter principle to evaluate the size distribution of microparticles. A relationship between the swelling ratio of the particles and their reported Coulter diameters will permit calculation of the actual diameters of these particles. Using polyethylene glycol diacrylate hydrogel microspheres, we determined a correction factor that relates the polymer swelling ratio and the reported Coulter diameters to their actual size. PMID:26414785

  11. Control hydrogel-hyaluronic acid aggregation toward the design of biomimetic superlubricants.

    PubMed

    Seekell, Raymond P; Dever, Rachel; Zhu, Yingxi

    2014-07-14

    Healthy synovial fluids (SFs) are complex fluids consisting of biopolymers, globule proteins, and lipids and regarded as superlubricants to provide nearly life-long low friction and wear protection of synovial joints in mammals. In this paper, we report that the intricate lubricious mixture can be simulated by the aggregation of hyaluronic acid (HA) and hydrogel particles in aqueous suspensions. In the HA aqueous suspensions added with synthetic polymer microgels, we have effectively captured the bulk rheological properties of healthy SFs. It is also confirmed by light scattering and fluorescence microscopic characterization that added hydrogel particles can enhance the HA network by hydrogel-mediated hydrogen bonding, leading to the fractal HA-hydrogel aggregating networks in aqueous suspensions. The potential application of HA-hydrogel particle aggregates as biomimetic superlubricants is supported by the comparable low friction at high load to that of healthy SFs.

  12. Polymer hydrogels: Chaperoning vaccines

    NASA Astrophysics Data System (ADS)

    Staats, Herman F.; Leong, Kam W.

    2010-07-01

    A cationic nanosized hydrogel (nanogel) shows controlled antigen delivery in vivo following intranasal administration and hence holds promise for a clinically effective adjuvant-free and needle-free vaccine system.

  13. Composite hydrogel scaffolds with controlled pore opening via biodegradable hydrogel porogen degradation.

    PubMed

    Hawkins, Ashley M; Milbrandt, Todd A; Puleo, David A; Hilt, J Zach

    2014-02-01

    Poly(β-amino ester) (PBAE) biodegradable hydrogel systems have garnered much attention in recent years due to their appealing properties for biomedical applications. These hydrogel systems exhibit properties similar to natural soft tissue, degrade in aqueous environments, and have easily tunable properties that have been well studied and understood. In most cases, tissue engineering scaffolds must possess a three-dimensional interconnected porous network for tissue ingrowth and construct vascularization. Here, PBAE properties were explored and systems were selected to serve as both the pore-forming agent and the outer matrix of a scaffold that exhibits controlled pore opening upon degradation. To our knowledge, this is the first demonstration of a biodegradable hydrogel porogen system entrapped in a degradable hydrogel outer matrix. Scaffolds were prepared, and the degradation, compressive moduli, and porosity were analyzed. An added advantage of a degradable porogen is the potential for controlled drug release, and a model protein was released from the porogen particles to demonstrate this application. Finally, pluripotent cells seeded onto predegraded scaffolds were viable during the first 24 h of exposure, and furthermore, cell tracking confirmed the presence of cells within the pores of the scaffold. Overall, these present studies demonstrate the possibility of using these biodegradable hydrogel porogen-matrix systems as tissue engineering scaffolding materials.

  14. Reversible Polymer Hydrogels

    DTIC Science & Technology

    2008-12-01

    glucosamine hydrochloride was dissolved in 100 mL of de- ionized water and placed in an ice bath at >5oC and purged with N2 gas for 20 minutes; 3.25...Temperature sensitive hydrogels based on N-isopropyl acrylamide (NIPA) and acryloyl glucosamine (AG) were synthesized using ammonium persulfate (APS) as...hydrogels by copolymerization of poly (N-isopropylacrylamide) (NIPA), and acryloyl glucosamine (AG) a derivative of chi- tosan, a biopolymer from

  15. Swelling/deswelling of Toroidal Hydrogels

    NASA Astrophysics Data System (ADS)

    Chang, Ya-Wen; Dimitriyev, Michael; Marquez, Samantha; Goldbart, Paul; Fernandez-Nieves, Alberto

    2014-03-01

    Swelling/deswelling of hydrogel spheres proceeds with the increase/decrease of particle radius that corresponds to the change in overall volume. When the hydrogel has a toroidal geometry, which is characterized by two principal radii -radius from the center of the donut hole to the center of the tube, and the tube radius, it is not obvious how swelling proceeds. We prepare thermo-sensitive poly(N-isopropylacrylamide) pNIPAM toroidal gel particles of different aspect ratios. At equilibrium deswelling, i.e., slow heating rate, we find that the aspect ratio remains constant for both fat and thin tori. This is explained by linear elasticity. On the other hand, when the heating rate is sufficiently high, the toroid buckles due to the presence of a water-impermeable skin layer that develops in the initial deswelling stages. Acknowledgement: We thank Dr. Manuel Marquez, YNano LLC for financial support

  16. Stem Cells in Aggregate Form to Enhance Chondrogenesis in Hydrogels

    PubMed Central

    Sridharan, BanuPriya; Lin, Staphany M.; Hwu, Alexander T.; Laflin, Amy D.; Detamore, Michael S.

    2015-01-01

    There are a variety of exciting hydrogel technologies being explored for cartilage regenerative medicine. Our overall goal is to explore whether using stem cells in an aggregate form may be advantageous in these applications. 3D stem cell aggregates hold great promise as they may recapitulate the in vivo skeletal tissue condensation, a property that is not typically observed in 2D culture. We considered two different stem cell sources, human umbilical cord Wharton’s jelly cells (hWJCs, currently being used in clinical trials) and rat bone marrow-derived mesenchymal stem cells (rBMSCs). The objective of the current study was to compare the influence of cell phenotype, aggregate size, and aggregate number on chondrogenic differentiation in a generic hydrogel (agarose) platform. Despite being differing cell sources, both rBMSC and hWJC aggregates were consistent in outperforming cell suspension control groups in biosynthesis and chondrogenesis. Higher cell density impacted biosynthesis favorably, and the number of aggregates positively influenced chondrogenesis. Therefore, we recommend that investigators employing hydrogels consider using cells in an aggregate form for enhanced chondrogenic performance. PMID:26719986

  17. Dynamic compression of chondrocyte-agarose constructs reveals new candidate mechanosensitive genes.

    PubMed

    Bougault, Carole; Aubert-Foucher, Elisabeth; Paumier, Anne; Perrier-Groult, Emeline; Huot, Ludovic; Hot, David; Duterque-Coquillaud, Martine; Mallein-Gerin, Frédéric

    2012-01-01

    Articular cartilage is physiologically exposed to repeated loads. The mechanical properties of cartilage are due to its extracellular matrix, and homeostasis is maintained by the sole cell type found in cartilage, the chondrocyte. Although mechanical forces clearly control the functions of articular chondrocytes, the biochemical pathways that mediate cellular responses to mechanical stress have not been fully characterised. The aim of our study was to examine early molecular events triggered by dynamic compression in chondrocytes. We used an experimental system consisting of primary mouse chondrocytes embedded within an agarose hydrogel; embedded cells were pre-cultured for one week and subjected to short-term compression experiments. Using Western blots, we demonstrated that chondrocytes maintain a differentiated phenotype in this model system and reproduce typical chondrocyte-cartilage matrix interactions. We investigated the impact of dynamic compression on the phosphorylation state of signalling molecules and genome-wide gene expression. After 15 min of dynamic compression, we observed transient activation of ERK1/2 and p38 (members of the mitogen-activated protein kinase (MAPK) pathways) and Smad2/3 (members of the canonical transforming growth factor (TGF)-β pathways). A microarray analysis performed on chondrocytes compressed for 30 min revealed that only 20 transcripts were modulated more than 2-fold. A less conservative list of 325 modulated genes included genes related to the MAPK and TGF-β pathways and/or known to be mechanosensitive in other biological contexts. Of these candidate mechanosensitive genes, 85% were down-regulated. Down-regulation may therefore represent a general control mechanism for a rapid response to dynamic compression. Furthermore, modulation of transcripts corresponding to different aspects of cellular physiology was observed, such as non-coding RNAs or primary cilium. This study provides new insight into how chondrocytes respond

  18. Biomineral/Agarose Composite Gels Enhance Proliferation of Mesenchymal Stem Cells with Osteogenic Capability

    PubMed Central

    Suzawa, Yoshika; Kubo, Norihiko; Iwai, Soichi; Yura, Yoshiaki; Ohgushi, Hajime; Akashi, Mitsuru

    2015-01-01

    Hydroxyapatite (HA) or calcium carbonate (CaCO3) formed on an organic polymer of agarose gel is a biomaterial that can be used for bone tissue regeneration. However, in critical bone defects, the regeneration capability of these materials is limited. Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into bone forming osteoblasts. In this study, we loaded MSCs on HA- or CaCO3-formed agarose gel and cultured them with dexamethasone, which triggers the osteogenic differentiation of MSCs. High alkaline phosphatase activity was detected on both the HA- and CaCO3-formed agarose gels; however, basal activity was only detected on bare agarose gel. Bone-specific osteocalcin content was detected on CaCO3-formed agarose gel on Day 14 of culture, and levels subsequently increased over time. Similar osteocalcin content was detected on HA-formed agarose on Day 21 and levels increased on Day 28. In contrast, only small amounts of osteocalcin were found on bare agarose gel. Consequently, osteogenic capability of MSCs was enhanced on CaCO3-formed agarose at an early stage, and both HA- and CaCO3-formed agarose gels well supported the capability at a later stage. Therefore, MSCs loaded on either HA- or CaCO3-formed agarose could potentially be employed for the repair of critical bone defects. PMID:26110392

  19. Biomineral/Agarose Composite Gels Enhance Proliferation of Mesenchymal Stem Cells with Osteogenic Capability.

    PubMed

    Suzawa, Yoshika; Kubo, Norihiko; Iwai, Soichi; Yura, Yoshiaki; Ohgushi, Hajime; Akashi, Mitsuru

    2015-06-23

    Hydroxyapatite (HA) or calcium carbonate (CaCO3) formed on an organic polymer of agarose gel is a biomaterial that can be used for bone tissue regeneration. However, in critical bone defects, the regeneration capability of these materials is limited. Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into bone forming osteoblasts. In this study, we loaded MSCs on HA- or CaCO3-formed agarose gel and cultured them with dexamethasone, which triggers the osteogenic differentiation of MSCs. High alkaline phosphatase activity was detected on both the HA- and CaCO3-formed agarose gels; however, basal activity was only detected on bare agarose gel. Bone-specific osteocalcin content was detected on CaCO3-formed agarose gel on Day 14 of culture, and levels subsequently increased over time. Similar osteocalcin content was detected on HA-formed agarose on Day 21 and levels increased on Day 28. In contrast, only small amounts of osteocalcin were found on bare agarose gel. Consequently, osteogenic capability of MSCs was enhanced on CaCO3-formed agarose at an early stage, and both HA- and CaCO3-formed agarose gels well supported the capability at a later stage. Therefore, MSCs loaded on either HA- or CaCO3-formed agarose could potentially be employed for the repair of critical bone defects.

  20. Nanocomposite hydrogels for biomedical applications

    PubMed Central

    Gaharwar, Akhilesh K.

    2014-01-01

    Hydrogels mimic native tissue microenvironment due to their porous and hydrated molecular structure. An emerging approach to reinforce polymeric hydrogels and to include multiple functionalities focuses on incorporating nanoparticles within the hydrogel network. A wide range of nanoparticles, such as carbon-based, polymeric, ceramic, and metallic nanomaterials can be integrated within the hydrogel networks to obtain nanocomposites with superior properties and tailored functionality. Nanocomposite hydrogels can be engineered to possess superior physical, chemical, electrical, and biological properties. This review focuses on the most recent developments in the field of nanocomposite hydrogels with emphasis on biomedical and pharmaceutical applications. In particular, we discuss synthesis and fabrication of nanocomposite hydrogels, examine their current limitations and conclude with future directions in designing more advanced nanocomposite hydrogels for biomedical and biotechnological applications. PMID:24264728

  1. A new preclinical 3-dimensional agarose colony formation assay.

    PubMed

    Kajiwara, Yoshinori; Panchabhai, Sonali; Levin, Victor A

    2008-08-01

    The evaluation of new drug treatments and combination treatments for gliomas and other cancers requires a robust means to interrogate wide dose ranges and varying times of drug exposure without stain-inactivation of the cells (colonies). To this end, we developed a 3-dimensional (3D) colony formation assay that makes use of GelCount technology, a new cell colony counter for gels and soft agars. We used U251MG, SNB19, and LNZ308 glioma cell lines and MiaPaCa pancreas adenocarcinoma and SW480 colon adenocarcinoma cell lines. Colonies were grown in a two-tiered agarose that had 0.7% agarose on the bottom and 0.3% agarose on top. We then studied the effects of DFMO, carboplatin, and SAHA over a 3-log dose range and over multiple days of drug exposure. Using GelCount we approximated the area under the curve (AUC) of colony volumes as the sum of colony volumes (microm2xOD) in each plate to calculate IC50 values. Adenocarcinoma colonies were recognized by GelCount scanning at 3-4 days, while it took 6-7 days to detect glioma colonies. The growth rate of MiaPaCa and SW480 cells was rapid, with 100 colonies counted in 5-6 days; glioma cells grew more slowly, with 100 colonies counted in 9-10 days. Reliable log dose versus AUC curves were observed for all drugs studied. In conclusion, the GelCount method that we describe is more quantitative than traditional colony assays and allows precise study of drug effects with respect to both dose and time of exposure using fewer culture plates.

  2. Polymer hydrogel functionalized with biodegradable nanoparticles as composite system for controlled drug delivery.

    PubMed

    Rossi, Filippo; Ferrari, Raffaele; Castiglione, Franca; Mele, Andrea; Perale, Giuseppe; Moscatelli, Davide

    2015-01-09

    The possibility to direct pharmacological treatments targeting specific cell lines using polymer nanoparticles is one of the main novelties and perspectives in nanomedicine. However, sometimes, the ability to maintain NPs localized at the site of the injection that work as a drug reservoir can represent a good and complementary option. In this direction we built a composite material made of polymeric hydrogel functionalized with polymer NPs. ϵ-caprolactone and polyethylene glycol have been copolymerized in a two-step synthesis of PEGylated NPs, while hydrogel was synthesized through polycondensation between NPs, agarose and branched polyacrylic acid. NP functionalization was verified with Fourier transform infrared spectroscopy (FTIR), high resolution magic angle spinning-nuclear magnetic resonance (HRMAS-NMR) spectroscopy and release kinetics from a hydrogel matrix and compared with NPs only physically entrapped into a hydrogel matrix. The characteristics of the resulting composite hydrogel-NPs system were studied both in terms of rheological properties and in its ability to sustain the release of To-Pro3, used as a drug mimetic compound to represent a promising drug delivery device.

  3. Polymer hydrogel functionalized with biodegradable nanoparticles as composite system for controlled drug delivery

    NASA Astrophysics Data System (ADS)

    Rossi, Filippo; Ferrari, Raffaele; Castiglione, Franca; Mele, Andrea; Perale, Giuseppe; Moscatelli, Davide

    2015-01-01

    The possibility to direct pharmacological treatments targeting specific cell lines using polymer nanoparticles is one of the main novelties and perspectives in nanomedicine. However, sometimes, the ability to maintain NPs localized at the site of the injection that work as a drug reservoir can represent a good and complementary option. In this direction we built a composite material made of polymeric hydrogel functionalized with polymer NPs. ɛ-caprolactone and polyethylene glycol have been copolymerized in a two-step synthesis of PEGylated NPs, while hydrogel was synthesized through polycondensation between NPs, agarose and branched polyacrylic acid. NP functionalization was verified with Fourier transform infrared spectroscopy (FTIR), high resolution magic angle spinning-nuclear magnetic resonance (HRMAS-NMR) spectroscopy and release kinetics from a hydrogel matrix and compared with NPs only physically entrapped into a hydrogel matrix. The characteristics of the resulting composite hydrogel-NPs system were studied both in terms of rheological properties and in its ability to sustain the release of To-Pro3, used as a drug mimetic compound to represent a promising drug delivery device.

  4. Microscale characterization of the viscoelastic properties of hydrogel biomaterials using dual-mode ultrasound elastography.

    PubMed

    Hong, Xiaowei; Stegemann, Jan P; Deng, Cheri X

    2016-05-01

    Characterization of the microscale mechanical properties of biomaterials is a key challenge in the field of mechanobiology. Dual-mode ultrasound elastography (DUE) uses high frequency focused ultrasound to induce compression in a sample, combined with interleaved ultrasound imaging to measure the resulting deformation. This technique can be used to non-invasively perform creep testing on hydrogel biomaterials to characterize their viscoelastic properties. DUE was applied to a range of hydrogel constructs consisting of either hydroxyapatite (HA)-doped agarose, HA-collagen, HA-fibrin, or preosteoblast-seeded collagen constructs. DUE provided spatial and temporal mapping of local and bulk displacements and strains at high resolution. Hydrogel materials exhibited characteristic creep behavior, and the maximum strain and residual strain were both material- and concentration-dependent. Burger's viscoelastic model was used to extract characteristic parameters describing material behavior. Increased protein concentration resulted in greater stiffness and viscosity, but did not affect the viscoelastic time constant of acellular constructs. Collagen constructs exhibited significantly higher modulus and viscosity than fibrin constructs. Cell-seeded collagen constructs became stiffer with altered mechanical behavior as they developed over time. Importantly, DUE also provides insight into the spatial variation of viscoelastic properties at sub-millimeter resolution, allowing interrogation of the interior of constructs. DUE presents a novel technique for non-invasively characterizing hydrogel materials at the microscale, and therefore may have unique utility in the study of mechanobiology and the characterization of hydrogel biomaterials.

  5. Two-dimensional agarose gel electrophoresis of DNA topoisomers.

    PubMed

    Roca, Joaquim

    2009-01-01

    The electrophoretic velocity of a duplex DNA ring is mainly determined by its overall shape. Consequently, DNA topoisomers of opposite supercoiling handedness can have identical gel velocity, and topoisomers highly supercoiled cannot be separated beyond some point. These problems are overcome by two-dimensional agarose gel electrophoresis, which involves two successive electrophoresis steps in one gel slab. The first and second electrophoresis steps are conducted in orthogonal directions with different concentrations of DNA intercalating agents. These compounds alter the overall shape of the DNA and, thereby, change the relative mobility of individual DNA topoisomers.

  6. [Preparation, characterization and surface-enhanced Raman properties of agarose gel/gold nanoparticles hybrid].

    PubMed

    Ma, Xiao-yuan; Liu, Ying; Wang, Zhou-ping

    2014-08-01

    Agarose gel/gold nanoparticles hybrid was prepared by adding gold nanoparticles to preformed agarose gel. Naniocomposite structures and properties were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV-Vis-NIR absorption spectroscopy. Experimental data indicated a uniform distribution of gold nanoparticles adsorbed on agarose gel network And the excellent optical absorption properties were shown. Based on the swelling-contraction characteristics of agarose gel and the adjustable localized surface plasmon resonance (LSPR) of the gold nanoparticles, the nano-composites were used as surface enhanced Raman scattering (SERS) substrate to detect the Raman signal molecules Nile blue A. Results revealed that the porous structure of the agarose gel provided a good carrier for the enrichment of the gold nanoparticles. The gold nanoparticles dynamic hot-spot effect arising from the agarose gel contraction loss of water in the air greatly enhanced the Raman signal.

  7. Design of biomimetic super-lubricants by hydrogel-biopolymer aggregates

    NASA Astrophysics Data System (ADS)

    Seekell, Raymond; Dever, Rachel; Zhu, Yingxi

    2013-03-01

    Inspired by the superb lubricity of natural synovial fluids for moving articular cartilage joints, we investigate a biomimetic artificial lubricant based on a hydrogel-biopolymer mixture with optimized rheological properties at a microscopic level. Specifically, we examine the structure and rheological relationship of stimuli-responsive poly (N-isopropylacrylamide) (PNIPAM) hydrogel added with hyaluronic acid (HA) to simulate the complexes of HA with a globule protein, lubricin, which are credited as the two key lubricious constituents in natural synovial fluids. By combined microscopic structural characterization and rheology measurement, we tune the rheological and frictional behaviors of HA solutions by optimizing the content of added micron-sized PNIPAM hydrogel particles to form stable PNIPAM-HA network. In a recent work on using zwitterionic hydrogel particles instead of negatively charged PNIPAM, comparable structure and rheological properties of hydrogel-HA aggregates are observed, which may give insight to design new biocompatible lubricants and lubricious coatings for medical ramification.

  8. Surface chemistry and size influence the release of model therapeutic nanoparticles from poly(ethylene glycol) hydrogels

    NASA Astrophysics Data System (ADS)

    Hume, Stephanie L.; Jeerage, Kavita M.

    2013-05-01

    Nanoparticles have emerged as promising therapeutic and diagnostic tools, due to their unique physicochemical properties. The specific core and surface chemistries, as well as nanoparticle size, play critical roles in particle transport and interaction with biological tissue. Localized delivery of therapeutics from hydrogels is well established, but these systems generally release molecules with hydrodynamic radii less than 5 nm. Here, model nanoparticles with biologically relevant surface chemistries and diameters between 10 and 35 nm are analyzed for their release from well-characterized hydrogels. Functionalized gold nanoparticles or quantum dots were encapsulated in three-dimensional poly(ethylene glycol) hydrogels with varying mesh size. Nanoparticle size, surface chemistry, and hydrogel mesh size all influenced the release of particles from the hydrogel matrix. Size influenced nanoparticle release as expected, with larger particles releasing at a slower rate. However, citrate-stabilized gold nanoparticles were not released from hydrogels. Negatively charged carboxyl or positively charged amine-functionalized quantum dots were released from hydrogels at slower rates than neutrally charged PEGylated nanoparticles of similar size. Transmission electron microscopy images of gold nanoparticles embedded within hydrogel sections demonstrated uniform particle distribution and negligible aggregation, independent of surface chemistry. The nanoparticle-hydrogel interactions observed in this work will aid in the development of localized nanoparticle delivery systems.

  9. Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior.

    PubMed

    Sun, Xiao; Heckscher, Ellie S

    2016-11-26

    Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat open surfaces is complex, including: pausing, turning, and meandering. This complexity in the repertoire of movement hinders detailed analysis of the events occurring during a single crawl stride cycle. To overcome this obstacle, linear agarose channels were made that constrain larval behavior to straight, sustained, rhythmic crawling. In principle, because agarose channels and the Drosophila larval body are both optically clear, the movement of larval structures labeled by genetically-encoded fluorescent probes can be monitored in intact, freely-moving larvae. In the past, larvae were placed in linear channels and crawling at the level of whole organism, segment, and muscle were analyzed(1). In the future, larvae crawling in channels can be used for calcium imaging to monitor neuronal activity. Moreover, these methods can be used with larvae of any genotype and with any researcher-designed channel. Thus the protocol presented below is widely applicable for studies using the Drosophila larva as a model to understand motor control.

  10. Microfluidic hydrogels for tissue engineering.

    PubMed

    Huang, Guo You; Zhou, Li Hong; Zhang, Qian Cheng; Chen, Yong Mei; Sun, Wei; Xu, Feng; Lu, Tian Jian

    2011-03-01

    With advanced properties similar to the native extracellular matrix, hydrogels have found widespread applications in tissue engineering. Hydrogel-based cellular constructs have been successfully developed to engineer different tissues such as skin, cartilage and bladder. Whilst significant advances have been made, it is still challenging to fabricate large and complex functional tissues due mainly to the limited diffusion capability of hydrogels. The integration of microfluidic networks and hydrogels can greatly enhance mass transport in hydrogels and spatiotemporally control the chemical microenvironment of cells, mimicking the function of native microvessels. In this review, we present and discuss recent advances in the fabrication of microfluidic hydrogels from the viewpoint of tissue engineering. Further development of new hydrogels and microengineering technologies will have a great impact on tissue engineering.

  11. A Novel Domperidone Hydrogel: Preparation, Characterization, Pharmacokinetic, and Pharmacodynamic Properties

    PubMed Central

    Zhang, Chun-Hui; Zhao, Bing-Xiang; Huang, Yue; Wang, Ying; Ke, Xi-Yu; Zhao, Bo-Jun; Zhang, Xuan; Zhang, Qiang

    2011-01-01

    The purpose of the present study was to prepare a novel domperidone hydrogel. The domperidone dispersion was prepared by the solvent evaporation method. The characteristics of domperidone dispersion were measured by dynamic light scattering (DLS), scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffractometry, and solubility test, respectively. Domperidone hydrogel was prepared by directly incorporating the domperidone dispersion in Carbopol hydrogel to increase its mucoadhesive properties to gastrointestinal tract (GIT). The in vivo pharmacokinetic and pharmacodynamic studies were investigated to evaluate the relative oral bioavailability and the propulsion efficacy of domperidone hydrogel as compared with market domperidone tablet (Motilium tablet). The particle size of domperidone dispersion in distilled water was 454.0 nm. The results of DSC and X-ray indicated that domperidone in dispersion was in amorphous state. The solubility of domperidone in the dispersion in distilled water, pH of 1, 5, and 7 buffer solution was 45.7-, 63.9-, 13.1-, and 3.7-fold higher than that of raw domperidone, respectively. The area under the plasma concentration curve (AUC0–24) in domperidone hydrogel was 2.2-fold higher than that of tablet. The prolonged propulsion efficacy in the domperidone hydrogel group compared to that in tablet group was observed in the pharmacodynamic test. PMID:21490756

  12. A novel domperidone hydrogel: preparation, characterization, pharmacokinetic, and pharmacodynamic properties.

    PubMed

    Zhang, Chun-Hui; Zhao, Bing-Xiang; Huang, Yue; Wang, Ying; Ke, Xi-Yu; Zhao, Bo-Jun; Zhang, Xuan; Zhang, Qiang

    2011-01-01

    The purpose of the present study was to prepare a novel domperidone hydrogel. The domperidone dispersion was prepared by the solvent evaporation method. The characteristics of domperidone dispersion were measured by dynamic light scattering (DLS), scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffractometry, and solubility test, respectively. Domperidone hydrogel was prepared by directly incorporating the domperidone dispersion in Carbopol hydrogel to increase its mucoadhesive properties to gastrointestinal tract (GIT). The in vivo pharmacokinetic and pharmacodynamic studies were investigated to evaluate the relative oral bioavailability and the propulsion efficacy of domperidone hydrogel as compared with market domperidone tablet (Motilium tablet). The particle size of domperidone dispersion in distilled water was 454.0 nm. The results of DSC and X-ray indicated that domperidone in dispersion was in amorphous state. The solubility of domperidone in the dispersion in distilled water, pH of 1, 5, and 7 buffer solution was 45.7-, 63.9-, 13.1-, and 3.7-fold higher than that of raw domperidone, respectively. The area under the plasma concentration curve (AUC(0-24)) in domperidone hydrogel was 2.2-fold higher than that of tablet. The prolonged propulsion efficacy in the domperidone hydrogel group compared to that in tablet group was observed in the pharmacodynamic test.

  13. Hydrogels in Regenerative Medicine

    PubMed Central

    Slaughter, Brandon V.; Khurshid, Shahana S.; Fisher, Omar Z.; Khademhosseini, Ali

    2015-01-01

    Hydrogels, due to their unique biocompatibility, flexible methods of synthesis, range of constituents, and desirable physical characteristics, have been the material of choice for many applications in regenerative medicine. They can serve as scaffolds that provide structural integrity to tissue constructs, control drug and protein delivery to tissues and cultures, and serve as adhesives or barriers between tissue and material surfaces. In this work, the properties of hydrogels that are important for tissue engineering applications and the inherent material design constraints and challenges are discussed. Recent research involving several different hydrogels polymerized from a variety of synthetic and natural monomers using typical and novel synthetic methods are highlighted. Finally, special attention is given to the microfabrication techniques that are currently resulting in important advances in the field. PMID:20882499

  14. Improved Skin Penetration Using In Situ Nanoparticulate Diclofenac Diethylamine in Hydrogel Systems: In Vitro and In Vivo Studies.

    PubMed

    Sengupta, Soma; Banerjee, Sarita; Sinha, Biswadip; Mukherjee, Biswajit

    2016-04-01

    Delivering diclofenac diethylamine transdermally by means of a hydrogel is an approach to reduce or avoid systemic toxicity of the drug while providing local action for a prolonged period. In the present investigation, a process was developed to produce nanosize particles (about 10 nm) of diclofenac diethylamine in situ during the development of hydrogel, using simple mixing technique. Hydrogel was developed with polyvinyl alcohol (PVA) (5.8% w/w) and carbopol 71G (1.5% w/w). The formulations were evaluated on the basis of field emission scanning electron microscopy, texture analysis, and the assessment of various physiochemical properties. Viscosity (163-165 cps for hydrogel containing microsize drug particles and 171-173 cps for hydrogel containing nanosize drug particles, respectively) and swelling index (varied between 0.62 and 0.68) data favor the hydrogels for satisfactory topical applications. The measured hardness of the different hydrogels was uniform indicating a uniform spreadability. Data of in vitro skin (cadaver) permeation for 10 h showed that the enhancement ratios of the flux of the formulation containing nanosize drug (without the permeation enhancer) were 9.72 and 1.30 compared to the formulation containing microsized drug and the marketed formulations, respectively. In vivo plasma level of the drug increased predominantly for the hydrogel containing nanosize drug-clusters. The study depicts a simple technique for preparing hydrogel containing nanosize diclofenac diethylamine particles in situ, which can be commercially viable. The study also shows the advantage of the experimental transdermal hydrogel with nanosize drug particles over the hydrogel with microsize drug particles.

  15. Supplementation of Exogenous Adenosine 5′-Triphosphate Enhances Mechanical Properties of 3D Cell–Agarose Constructs for Cartilage Tissue Engineering

    PubMed Central

    Gadjanski, Ivana; Yodmuang, Supansa; Spiller, Kara; Bhumiratana, Sarindr

    2013-01-01

    Formation of tissue-engineered cartilage is greatly enhanced by mechanical stimulation. However, direct mechanical stimulation is not always a suitable method, and the utilization of mechanisms underlying mechanotransduction might allow for a highly effective and less aggressive alternate means of stimulation. In particular, the purinergic, adenosine 5′-triphosphate (ATP)-mediated signaling pathway is strongly implicated in mechanotransduction within the articular cartilage. We investigated the effects of transient and continuous exogenous ATP supplementation on mechanical properties of cartilaginous constructs engineered using bovine chondrocytes and human mesenchymal stem cells (hMSCs) encapsulated in an agarose hydrogel. For both cell types, we have observed significant increases in equilibrium and dynamic compressive moduli after transient ATP treatment applied in the fourth week of cultivation. Continuous ATP treatment over 4 weeks of culture only slightly improved the mechanical properties of the constructs, without major changes in the total glycosaminoglycan (GAG) and collagen content. Structure–function analyses showed that transiently ATP-treated constructs, and in particular those based on hMSCs, had the highest level of correlation between compositional and mechanical properties. Transiently treated groups showed intense staining of the territorial matrix for GAGs and collagen type II. These results indicate that transient ATP treatment can improve functional mechanical properties of cartilaginous constructs based on chondrogenic cells and agarose hydrogels, possibly by improving the structural organization of the bulk phase and territorial extracellular matrix (ECM), that is, by increasing correlation slopes between the content of the ECM components (GAG, collagen) and mechanical properties of the construct. PMID:23651296

  16. Adhesion in hydrogel contacts.

    PubMed

    Torres, J R; Jay, G D; Kim, K-S; Bothun, G D

    2016-05-01

    A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.

  17. Adhesion in hydrogel contacts

    NASA Astrophysics Data System (ADS)

    Torres, J. R.; Jay, G. D.; Kim, K.-S.; Bothun, G. D.

    2016-05-01

    A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.

  18. Magnetic barcoded hydrogel microparticles for multiplexed detection.

    PubMed

    Bong, Ki Wan; Chapin, Stephen C; Doyle, Patrick S

    2010-06-01

    Magnetic polymer particles have been used in a wide variety of applications ranging from targeting and separation to diagnostics and imaging. Current synthesis methods have limited these particles to spherical or deformations of spherical morphologies. In this paper, we report the use of stop flow lithography to produce magnetic hydrogel microparticles with a graphical code region, a probe region, and a magnetic tail region. These anisotropic multifunctional magnetic polymer particles are an enhanced version of previously synthesized "barcoded" particles (Science, 2007, 315, 1393-1396) developed for the sensitive and rapid multiplexed sensing of nucleic acids. The newly added magnetic region has acquired dipole moments in the presence of weak homogeneous magnetic fields, allowing the particles to align along the applied field direction. The novel magnetic properties have led to practical applications in the efficient orientation and separation of the barcoded microparticles during biological assays without disrupting detection capabilities.

  19. Evaluation of genipin-crosslinked chitosan hydrogels as a potential carrier for silver sulfadiazine nanocrystals.

    PubMed

    Gao, Lei; Gan, Hui; Meng, Zhiyun; Gu, Ruolan; Wu, Zhuona; Zhu, Xiaoxia; Sun, Wenzhong; Li, Jian; Zheng, Ying; Sun, Tao; Dou, Guifang

    2016-12-01

    In the present study genipin crosslinked chitosan (CHI) hydrogels, which had been constructed and reported in our previous studies (Gao et al., 2014 [22]), were further evaluated for their advantage as a carrier for silver sulfadiazine (AgSD) nanocrystal systems. Firstly, AgSD nanocrystals with a mean particle size of 289nm were prepared by wet milling method and encapsulated into genipin crosslinked CHI hydrogels. AgSD nanocrystals displayed a uniform distribution and very good physical stability in the hydrogel network. Swelling-dependent release pattern was found for AgSD nanocrystals from hydrogels and the release profile could be well fitted with Peppas equation. When AgSD nanocrystals were encapsulated in hydrogels their fibroblast cytotoxicity decreased markedly, and their antibacterial effects against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were still comparable to unencapsulated AgSD nanocrystals. In vivo evaluation in excision and burn cutaneous wound models in mice showed that AgSD nanocrystal hydrogels markedly decreased the expression of inflammatory cytokine IL-6, but increased the levels of growth factors VEGF-A and TGF-β1. Histopathologically, the wounds treated by hydrogels containing AgSD nanocrystals showed the best healing state compared with commercial AgSD cream, hydrogels containing AgSD bulk powders and blank hydrogels. The wounds treated by AgSD nanocrystal hydrogels were dominated by marked fibroblast proliferation, new blood vessels and thick regenerated epithelial layer. Sirius Red staining assay indicated that AgSD nanocrystal hydrogels resulted in more collagen deposition characterized by a large proportion of type I fibers. Our study suggested that genipin-crosslinked CHI hydrogel was a potential carrier for local antibacterial nanomedicines.

  20. Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

    PubMed Central

    2015-01-01

    In this review we intend to provide a relatively comprehensive summary of the work of supramolecular hydrogelators after 2004 and to put emphasis particularly on the applications of supramolecular hydrogels/hydrogelators as molecular biomaterials. After a brief introduction of methods for generating supramolecular hydrogels, we discuss supramolecular hydrogelators on the basis of their categories, such as small organic molecules, coordination complexes, peptides, nucleobases, and saccharides. Following molecular design, we focus on various potential applications of supramolecular hydrogels as molecular biomaterials, classified by their applications in cell cultures, tissue engineering, cell behavior, imaging, and unique applications of hydrogelators. Particularly, we discuss the applications of supramolecular hydrogelators after they form supramolecular assemblies but prior to reaching the critical gelation concentration because this subject is less explored but may hold equally great promise for helping address fundamental questions about the mechanisms or the consequences of the self-assembly of molecules, including low molecular weight ones. Finally, we provide a perspective on supramolecular hydrogelators. We hope that this review will serve as an updated introduction and reference for researchers who are interested in exploring supramolecular hydrogelators as molecular biomaterials for addressing the societal needs at various frontiers. PMID:26646318

  1. Nanoparticle gel electrophoresis: bare charged spheres in polyelectrolyte hydrogels.

    PubMed

    Li, Fei; Hill, Reghan J

    2013-03-15

    Nanoparticle gel electrophoresis has recently emerged as an attractive means of separating and characterizing nanoparticles. Consequently, a theory that accounts for electroosmotic flow in the gel, and coupling of the nanoparticle and hydrogel electrostatics and hydrodynamics, is required, particularly for gels in which the mesh size is comparable to or smaller than the particle radii. Here, we present an electrokinetic model for charged, spherical colloidal particles undergoing electrophoresis in charged (polyelectrolyte) hydrogels: the gel-electrophoresis analogue of Henry's theory for electrophoresis in Newtonian electrolytes. We compare numerically exact solutions of the model with several independent asymptotic approximations, identifying regions in the parameter space where these approximations are accurate or break down. As previously assumed in the literature, Henry's formula, modified by the addition of a constant electroosmotic flow mobility, is accurate only for nanoparticles that are small compared to the hydrogel mesh size. We derived an exact analytical solution of the full model by judiciously modifying the theory of Allison et al. for uncharged gels, drawing on the superposition methodology of Doane et al. to account for hydrogel charge. This furnishes accurate and economical mobility predictions for the entire parameter space. The present model suggests that nanoparticle size separations (with diameters ≲40 nm) are optimal at low ionic strength, with a gel mesh size that is selected according to the particle charging mechanism. For weakly charged particles, optimal size separation is achieved when the Brinkman screening length is matched to the mean particle size.

  2. An agarose-gel based method for transporting cell lines.

    PubMed

    Yang, Lingzhi; Li, Chufang; Chen, Ling; Li, Zhiyuan

    2009-12-16

    Cryopreserved cells stored in dry ice or liquid nitrogen is the classical method for transporting cells between research laboratories in different cities around the world in order to maintain cell viability. An alternative method is to ship the live cells in flasks filled with cell culture medium. Both methods have limitations of either a requirement on special shipping container or short times for the cells to survive on the shipping process. We have recently developed an agarose gel based method for directly transporting the live adherent cells in cell culture plates or dishes in ambient temperature. This convenient method simplifies the transportation of live cells in long distance that can maintain cells in good viability for several days.

  3. Cloning of DNA fragments: ligation reactions in agarose gel.

    PubMed

    Furtado, Agnelo

    2014-01-01

    Ligation reactions to ligate a desired DNA fragment into a vector can be challenging to beginners and especially if the amount of the insert is limiting. Although additives known as crowding agents, such as PEG 8000, added to the ligation mixes can increase the success one has with ligation reactions, in practice the amount of insert used in the ligation can determine the success or the failure of the ligation reaction. The method described here, which uses insert DNA in gel slice added directly into the ligation reaction, has two benefits: (a) using agarose as the crowding agent and (b) reducing steps of insert purification. The use of rapid ligation buffer and incubation of the ligation reaction at room temperature greatly increase the efficiency of the ligation reaction even for blunt-ended ligation.

  4. Bleach Gel: A Simple Agarose Gel for Analyzing RNA Quality

    PubMed Central

    Aranda, Patrick S.; LaJoie, Dollie M.; Jorcyk, Cheryl L.

    2013-01-01

    RNA-based applications requiring high quality, non-degraded RNA are a foundational element of many research studies. As such, it is paramount that the integrity of experimental RNA is validated prior to cDNA synthesis or other downstream applications. In the absence of expensive equipment such as microfluidic electrophoretic devices, and as an alternative to the costly and time-consuming standard formaldehyde gel, RNA quality can be quickly analyzed by adding small amounts of commercial bleach to TAE buffer-based agarose gels prior to electrophoresis. In the presence of low concentrations of bleach, the secondary structure of RNA is denatured and potential contaminating RNases are destroyed. Because of this, the ‘bleach gel’ is a functional approach that addresses the need for an inexpensive and safe way to evaluate RNA integrity and will improve the ability of researchers to rapidly analyze RNA quality. PMID:22222980

  5. Pore size of agarose gels by atomic force microscopy.

    PubMed

    Pernodet, N; Maaloum, M; Tinland, B

    1997-01-01

    The pore size of agarose gel in water at different concentrations was directly measured using atomic force microscopy (AFM). The experiment was specially designed to work under aqueous conditions and allows direct observation of the "unperturbed" gel without invasive treatment. The pore size a as a function of gel concentration C shows a power law dependence a approximately C-gamma, where gamma lies between the prediction of the Ogston model for a random array of straight chains, 0.5, and the value predicted by De Gennes for a network of flexible chains, 0.75. We confirm that gels present a wide pore size distribution and show that it narrows as the concentration increases.

  6. Bleach gel: a simple agarose gel for analyzing RNA quality.

    PubMed

    Aranda, Patrick S; LaJoie, Dollie M; Jorcyk, Cheryl L

    2012-01-01

    RNA-based applications requiring high-quality, non-degraded RNA are a foundational element of many research studies. As such, it is paramount that the integrity of experimental RNA is validated prior to cDNA synthesis or other downstream applications. In the absence of expensive equipment such as microfluidic electrophoretic devices, and as an alternative to the costly and time-consuming standard formaldehyde gel, RNA quality can be quickly analyzed by adding small amounts of commercial bleach to TAE buffer-based agarose gels prior to electrophoresis. In the presence of low concentrations of bleach, the secondary structure of RNA is denatured and potential contaminating RNases are destroyed. Because of this, the 'bleach gel' is a functional approach that addresses the need for an inexpensive and safe way to evaluate RNA integrity and will improve the ability of researchers to rapidly analyze RNA quality.

  7. A polarized photobleaching study of DNA reorientation in agarose gels

    SciTech Connect

    Scalettar, B.A.; Klein, M.P. ); Selvin, P.R.; Hearst, J.E. Univ. of California, Berkeley ); Axelrod, D. )

    1990-05-22

    Polarized fluorescence recovery after photobleaching (pFRAP) has been used to study the internal dynamics of relatively long DNA molecules embedded in gels that range in concentration from 1% to 5% agarose. The data indicate that, even in very congested gels, rapid internal relaxation of DNA is largely unhindered; however, interactions with gel matrices apparently do perturb the larger amplitude, more slowly (microseconds to milliseconds) relaxing internal motions of large DNAs. The relationship between this work and recent studies which indicate that internal motions of DNA play an important role in the separation achieved with pulsed-field gel electrophoresis techniques is discussed. The polarized photobleaching technique is also analyzed in some detail. In particular, it is shown that reversible photobleaching phenomena are probably related to depletion of the ground state by intersystem crossing to the triplet state.

  8. Enzyme-responsive hydrogel microparticles for pulmonary drug delivery.

    PubMed

    Secret, Emilie; Kelly, Stefan J; Crannell, Kelsey E; Andrew, Jennifer S

    2014-07-09

    Poly(ethylene glycol) based hydrogel microparticles were developed for pulmonary drug delivery. Hydrogels are particularly attractive for pulmonary delivery because they can be size engineered for delivery into the bronchi, yet also swell upon reaching their destination to avoid uptake and clearance by alveolar macrophages. To develop enzyme-responsive hydrogel microparticles for pulmonary delivery a new synthesis method based on a solution polymerization was developed. This method produces spherical poly(ethylene glycol) (PEG) microparticles from high molecular weight poly(ethylene glycol) diacrylate (PEGDA)-based precursors that incorporate peptides in the polymer chain. Specifically, we have synthesized hydrogel microparticles that degrade in response to matrix metalloproteinases that are overexpressed in pulmonary diseases. Small hydrogel microparticles with sizes suitable for lung delivery by inhalation were obtained from solid precursors when PEGDA was dissolved in water at a high concentration. The average diameter of the particles was between 2.8 and 4 μm, depending on the molecular weight of the precursor polymer used and its concentration in water. The relation between the physical properties of the particles and their enzymatic degradation is also reported, where an increased mesh size corresponds to increased degradation.

  9. Intelligent hydrogels for drug delivery system.

    PubMed

    He, Liumin; Zuo, Qinhua; Xie, Shasha; Huang, Yuexin; Xue, Wei

    2011-09-01

    Intelligent hydrogel, also known as smart hydrogels, are materials with great potential for development in drug delivery system. Intelligent hydrogel also has the ability to perceive as a signal structure change and stimulation. The review introduces the temperature-, pH-, electric signal-, biochemical molecule-, light- and pressure- sensitive hydrogels. Finally, we described the application of intelligent hydrogel in drug delivery system and the recent patents involved for hydrogel in drug delivery.

  10. Regenerative behavior of biomineral/agarose composite gels as bone grafting materials in rat cranial defects.

    PubMed

    Suzawa, Yoshika; Funaki, Takafumi; Watanabe, Junji; Iwai, Soichi; Yura, Yoshiaki; Nakano, Takayoshi; Umakoshi, Yukichi; Akashi, Mitsuru

    2010-06-01

    The main objective of this study was to evaluate the biological behavior of Hydroxyapatite (HAp)/agarose and calcium carbonate (CaCO3)/agarose composite gels by an alternate soaking process used for the treatment of surgically produced bone defects in rat cranium. We designed the following four groups: (i) HAp (HAp/agarose composite gel), (ii) CaCO3 (CaCO3/agarose composite gel), (iii) Agarose (bare agarose gel), and (iv) Defect (no filling materials). We subdivided (i) (ii) (iii) into two application types as a (I) Homogenized Group (homogenized materials) and a (II) Disk Group (disk shaped materials). We assessed samples by radiological and histological analyses 0, 4, and 8 weeks after implantation. The results indicated that the composite gels showed higher radiopacity in microfocus-computed tomography (muCT) images and showed higher volume in quantitative analyses using Dual Energy X-ray Absorptiometry (DEXA) and Peripheral Quantitative Computed Tomography (pQCT) than the Agarose and Defect groups. The histological examination showed characteristic images due to each application form. Consequently, HAp and CaCO3/agarose composite gels can be expected to accelerate the speed of producing more new bone associated with osteogenesis. These novel biomaterials play an important role as an alternative biocompatible and biodegradable bone grafting filler material for autogenous bone.

  11. High-quality substrate for fluorescence enhancement using agarose-coated silica opal film.

    PubMed

    Xu, Ming; Li, Juan; Sun, Liguo; Zhao, Yuanjin; Xie, Zhuoying; Lv, Linli; Zhao, Xiangwei; Xiao, Pengfeng; Hu, Jing; Lv, Mei; Gu, Zhongze

    2010-08-01

    To improve the sensitivity of fluorescence detection in biochip, a new kind of substrates was developed by agarose coating on silica opal film. In this study, silica opal film was fabricated on glass substrate using the vertical deposition technique. It can provide stronger fluorescence signals and thus improve the detection sensitivity. After coating with agarose, the hybrid film could provide a 3D support for immobilizing sample. Comparing with agarose-coated glass substrate, the agarose-coated opal substrates could selectively enhance particular fluorescence signals with high sensitivity when the stop band of the silica opal film in the agarose-coated opal substrate overlapped the fluorescence emission wavelength. A DNA hybridization experiment demonstrated that fluorescence intensity of special type of agarose-coated opal substrates was about four times that of agarose-coated glass substrate. These results indicate that the optimized agarose-coated opal substrate can be used for improving the sensitivity of fluorescence detection with high quality and selectivity.

  12. Engineering Cellular Microenvironments with Photo- and Enzymatically Responsive Hydrogels: Toward Biomimetic 3D Cell Culture Models.

    PubMed

    Tam, Roger Y; Smith, Laura J; Shoichet, Molly S

    2017-03-27

    Conventional cell culture techniques using 2D polystyrene or glass have provided great insight into key biochemical mechanisms responsible for cellular events such as cell proliferation, differentiation, and cell-cell interactions. However, the physical and chemical properties of 2D culture in vitro are dramatically different than those found in the native cellular microenvironment in vivo. Cells grown on 2D substrates differ significantly from those grown in vivo, and this explains, in part, why many promising drug candidates discovered through in vitro drug screening assays fail when they are translated to in vivo animal or human models. To overcome this obstacle, 3D cell culture using biomimetic hydrogels has emerged as an alternative strategy to recapitulate native cell growth in vitro. Hydrogels, which are water-swollen polymers, can be synthetic or naturally derived. Many methods have been developed to control the physical and chemical properties of the hydrogels to match those found in specific tissues. Compared to 2D culture, cells cultured in 3D gels with the appropriate physicochemical cues can behave more like they naturally do in vivo. While conventional hydrogels involve modifications to the bulk material to mimic the static aspects of the cellular microenvironment, recent progress has focused on using more dynamic hydrogels, the chemical and physical properties of which can be altered with external stimuli to better mimic the dynamics of the native cellular microenvironment found in vivo. In this Account, we describe our progress in designing stimuli-responsive, optically transparent hydrogels that can be used as biomimetic extracellular matrices (ECMs) to study cell differentiation and migration in the context of modeling the nervous system and cancer. Specifically, we developed photosensitive agarose and hyaluronic acid hydrogels that are activated by single or two-photon irradiation for biomolecule immobilization at specific volumes within the 3D

  13. Preparation of gold nanoparticles-agarose gel composite and its application in SERS detection

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyuan; Xia, Yu; Ni, Lili; Song, Liangjing; Wang, Zhouping

    2014-03-01

    Agarose gel/gold nanoparticles hybrid was prepared by adding gold nanoparticles to preformed agarose gel. Nanocomposite structures and properties were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV-Vis-NIR absorption spectroscopy. Based on the swelling-contraction characteristics of agarose gel and the adjustable localized surface plasmon resonance (LSPR) of the gold nanoparticles, the nanocomposites were used as surface enhanced Raman scattering (SERS) substrate to detect the Raman signal molecules (NBA, MBA, 1NAT). Results revealed that the porous structure of the agarose gel provided a good carrier for the enrichment of the gold nanoparticles. The gold nanoparticles dynamic hot-spot effect arising from the agarose gel contraction loss of water in the air greatly enhanced the Raman signal. Furthermore, the gel could be cleaned with washing solution and recycling could be achieved for Raman detection.

  14. Preparation of gold nanoparticles-agarose gel composite and its application in SERS detection.

    PubMed

    Ma, Xiaoyuan; Xia, Yu; Ni, Lili; Song, Liangjing; Wang, Zhouping

    2014-01-01

    Agarose gel/gold nanoparticles hybrid was prepared by adding gold nanoparticles to preformed agarose gel. Nanocomposite structures and properties were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV-Vis-NIR absorption spectroscopy. Based on the swelling-contraction characteristics of agarose gel and the adjustable localized surface plasmon resonance (LSPR) of the gold nanoparticles, the nanocomposites were used as surface enhanced Raman scattering (SERS) substrate to detect the Raman signal molecules (NBA, MBA, 1NAT). Results revealed that the porous structure of the agarose gel provided a good carrier for the enrichment of the gold nanoparticles. The gold nanoparticles dynamic hot-spot effect arising from the agarose gel contraction loss of water in the air greatly enhanced the Raman signal. Furthermore, the gel could be cleaned with washing solution and recycling could be achieved for Raman detection.

  15. Cyclodextrin Inclusion Polymers Forming Hydrogels

    NASA Astrophysics Data System (ADS)

    Li, Jun

    This chapter reviews the advances in the developments of supramolecular hydrogels based on the polypseudorotaxanes and polyrotaxanes formed by inclusion complexes of cyclodextrins threading onto polymer chains. Both physical and chemical supramolecular hydrogels of many different types are discussed with respect to their preparation, structure, property, and gelation mechanism. A large number of physical supramolecular hydrogels were formed induced by self-assembly of densely packed cyclodextrin rings threaded on polymer or copolymer chains acting as physical crosslinking points. The thermo-reversible and thixotropic properties of these physical supramolecular hydrogels have inspired their applications as injectable drug delivery systems. Chemical supramolecular hydrogels synthesized from polypseudorotaxanes and polyrotaxanes were based on the chemical crosslinking of either the cyclodextrin molecules or the included polymer chains. The chemical supramolecular hydrogels were often made biodegradable through incorporation of hydrolyzable threading polymers, end caps, or crosslinkers, for their potential applications as biomaterials.

  16. Interpenetrating hydrogels of O-carboxymethyl Tamarind gum and alginate for monitoring delivery of acyclovir.

    PubMed

    Jana, Sougata; Sharma, Rashmi; Maiti, Sabyasachi; Sen, Kalyan Kumar

    2016-11-01

    In this work, an interpenetrating hydrogel network was constructed using varying combination of O-carboxymethyl Tamarind gum (CTG) and alginate by Ca(+2) ion induced gelation method. The hydrogels were characterized by FTIR spectroscopy, Field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and differential scanning calorimetry (DSC) analyses. The hydrogels were spherical in shape with rough surface textures. Depending on the alginate: CTG mass ratio, the hydrogel particles entrapped a maximum of ∼70% acyclovir. The drug release from interpenetrating hydrogels was 18-23% in HCl solution (pH1.2) in 2h. The drug release became faster in phosphate buffer solution (pH6.8) as the proportion of CTG was increased from 25% to 50%. However, the drug release was still slower than that observed for hydrogel particles of sodium alginate alone. Overall, the drug release tendency of the particles was higher in phosphate buffer solution than that in HCl solution. The non-Fickian drug release behavior was assumed after fitting the drug release data into Korsmeyer-Peppas model. The drug release was found to control by diffusion and swelling kinetics of the hydrogels. Thus, CTG gum could effectively retard drug release when used in combination with sodium alginate at an optimized mass ratio.

  17. PIXE investigation of in vitro release of chloramphenicol across polyvinyl alcohol/acrylamide hydrogel

    NASA Astrophysics Data System (ADS)

    Rihawy, M. S.; Alzier, A.; Allaf, A. W.

    2011-09-01

    Hydrogels based on polyvinyl alcohol and different amounts of acrylamide monomer were prepared by thermal cross-linking in the solid state. The hydrogels were investigated for drug delivery system applications. Chloramphenicol was adopted as a model drug to study its release behavior. Particle induced X-ray emission was utilized to study the drug release behavior across the hydrogels and a comparison study with ultraviolet measurements was performed. Fourier Transform Infrared measurements were carried out for molecular characterization. The releasing behavior of the drug exhibits a decrease and a subsequent increase in the release rate, as the acrylamide monomer increases. Characterization of the hydrogels has shown a competitive behavior between crosslinking with AAm acrylamide monomer or oligomerized version, depending on the amount added to prepare the hydrogels.

  18. Polysaccharide hydrogels with tunable stiffness and provasculogenic properties via α-helix to β-sheet switch in secondary structure

    PubMed Central

    Forget, Aurelien; Christensen, Jon; Lüdeke, Steffen; Kohler, Esther; Tobias, Simon; Matloubi, Maziar; Thomann, Ralf; Shastri, V. Prasad

    2013-01-01

    Mechanical aspects of the cellular environment can influence cell function, and in this context hydrogels can serve as an instructive matrix. Here we report that physicochemical properties of hydrogels derived from polysaccharides (agarose, κ-carrageenan) having an α-helical backbone can be tailored by inducing a switch in the secondary structure from α-helix to β-sheet through carboxylation. This enables the gel modulus to be tuned over four orders of magnitude (G′ 6 Pa–3.6 × 104 Pa) independently of polymer concentration and molecular weight. Using carboxylated agarose gels as a screening platform, we demonstrate that soft-carboxylated agarose provides a unique environment for the polarization of endothelial cells in the presence of soluble and bound signals, which notably does not occur in fibrin and collagen gels. Furthermore, endothelial cells organize into freestanding lumens over 100 μm in length. The finding that a biomaterial can modulate soluble and bound signals provides impetus for exploring mechanobiology paradigms in regenerative therapies. PMID:23886665

  19. A comparison of self-assembly and hydrogel encapsulation as a means to engineer functional cartilaginous grafts using culture expanded chondrocytes.

    PubMed

    Mesallati, Tariq; Buckley, Conor T; Kelly, Daniel J

    2014-01-01

    Despite an increased interest in the use of hydrogel encapsulation and cellular self-assembly (often termed "self-aggregating" or "scaffold-free" approaches) for tissue-engineering applications, to the best of our knowledge, no study to date has been undertaken to directly compare both approaches for generating functional cartilaginous grafts. The objective of this study was to directly compare self-assembly (SA) and agarose hydrogel encapsulation (AE) as a means to engineer such grafts using passaged chondrocytes. Agarose hydrogels (5 mm diameter × 1.5 mm thick) were seeded with chondrocytes at two cell seeding densities (900,000 cells or 4 million cells in total per hydrogel), while SA constructs were generated by adding the same number of cells to custom-made molds. Constructs were either supplemented with transforming growth factor (TGF)-β3 for 6 weeks, or only supplemented with TGF-β3 for the first 2 weeks of the 6 week culture period. The SA method was only capable of generating geometrically uniform cartilaginous tissues at high seeding densities (4 million cells). At these high seeding densities, we observed that total sulphated glycosaminoglycan (sGAG) and collagen synthesis was greater with AE than SA, with higher sGAG retention also observed in AE constructs. When normalized to wet weight, however, SA constructs exhibited significantly higher levels of collagen accumulation compared with agarose hydrogels. Furthermore, it was possible to engineer such functionality into these tissues in a shorter timeframe using the SA approach compared with AE. Therefore, while large numbers of chondrocytes are required to engineer cartilaginous grafts using the SA approach, it would appear to lead to the faster generation of a more hyaline-like tissue, with a tissue architecture and a ratio of collagen to sGAG content more closely resembling native articular cartilage.

  20. Chitosan Hydrogel Structure Modulated by Metal Ions

    PubMed Central

    Nie, Jingyi; Wang, Zhengke; Hu, Qiaoling

    2016-01-01

    As one of the most important polysaccharide, chitosan (CS) has generated a great deal of interest for its desirable properties and wide applications. In the utilization of CS materials, hydrogel is a major and vital branch. CS has the ability to coordinate with many metal ions by a chelation mechanism. While most researchers focused on the applications of complexes between CS and metal ions, the complexes can also influence gelation process and structure of CS hydrogel. In the present work, such influence was studied with different metal ions, revealing two different kinds of mechanisms. Strong affinity between CS and metal ions leads to structural transition from orientation to multi-layers, while weak affinity leads to composite gel with in-situ formed inorganic particles. The study gave a better understanding of the gelation mechanism and provided strategies for the modulation of hydrogel morphology, which benefited the design of new CS-based materials with hierarchical structure and facilitated the utilization of polysaccharide resources. PMID:27777398

  1. Chitosan Hydrogel Structure Modulated by Metal Ions

    NASA Astrophysics Data System (ADS)

    Nie, Jingyi; Wang, Zhengke; Hu, Qiaoling

    2016-10-01

    As one of the most important polysaccharide, chitosan (CS) has generated a great deal of interest for its desirable properties and wide applications. In the utilization of CS materials, hydrogel is a major and vital branch. CS has the ability to coordinate with many metal ions by a chelation mechanism. While most researchers focused on the applications of complexes between CS and metal ions, the complexes can also influence gelation process and structure of CS hydrogel. In the present work, such influence was studied with different metal ions, revealing two different kinds of mechanisms. Strong affinity between CS and metal ions leads to structural transition from orientation to multi-layers, while weak affinity leads to composite gel with in-situ formed inorganic particles. The study gave a better understanding of the gelation mechanism and provided strategies for the modulation of hydrogel morphology, which benefited the design of new CS-based materials with hierarchical structure and facilitated the utilization of polysaccharide resources.

  2. A photolabile hydrogel for guided three-dimensional cell growth and migration

    NASA Astrophysics Data System (ADS)

    Luo, Ying; Shoichet, Molly S.

    2004-04-01

    Tissue engineering aims to replace, repair or regenerate tissue/organ function, by delivering signalling molecules and cells on a three-dimensional (3D) biomaterials scaffold that supports cell infiltration and tissue organization. To control cell behaviour and ultimately induce structural and functional tissue formation on surfaces, planar substrates have been patterned with adhesion signals that mimic the spatial cues to guide cell attachment and function. The objective of this study is to create biochemical channels in 3D hydrogel matrices for guided axonal growth. An agarose hydrogel modified with a cysteine compound containing a sulphydryl protecting group provides a photolabile substrate that can be patterned with biochemical cues. In this transparent hydrogel we immobilized the adhesive fibronectin peptide fragment, glycine-arginine-glycine-aspartic acid-serine (GRGDS), in selected volumes of the matrix using a focused laser. We verified in vitro the guidance effects of GRGDS oligopeptide-modified channels on the 3D cell migration and neurite outgrowth. This method for immobilizing biomolecules in 3D matrices can generally be applied to any optically clear hydrogel, offering a solution to construct scaffolds with programmed spatial features for tissue engineering applications.

  3. Temperature Mapping in Hydrogel Matrices Using Unmodified Digital Camera.

    PubMed

    Darwish, Ghinwa H; Fakih, Hassan H; Karam, Pierre

    2017-02-09

    We report a simple, generally applicable, and noninvasive fluorescent method for mapping thermal fluctuations in hydrogel matrices using an unmodified commercially available digital single-lens reflex camera (DSLR). The nanothermometer is based on the complexation of short conjugated polyelectrolytes, poly(phenylene ethynylene) carboxylate, with an amphiphilic polymer, polyvinylpyrrolidone, which is in turn trapped within the porous network of a gel matrix. Changes in the temperature lead to a fluorescent ratiometric response with a maximum relative sensitivity of 2.0% and 1.9% at 45.0 °C for 0.5% agarose and agar, respectively. The response was reversible with no observed hysteresis when samples were cycled between 20 and 40 °C. As a proof of concept, the change in fluorescent signal/color was captured using a digital camera. The images were then dissected into their red-green-blue (RGB) components using a Matlab routine. A linear correlation was observed between the hydrogel temperature and the green and blue intensity channels. The reported sensor has the potential to provide a wealth of information when thermal fluctuations mapped in soft gels matrices are correlated with chemical or physical processes.

  4. Characterization and swelling-deswelling properties of wheat straw cellulose based semi-IPNs hydrogel.

    PubMed

    Liu, Jia; Li, Qian; Su, Yuan; Yue, Qinyan; Gao, Baoyu

    2014-07-17

    A novel wheat straw cellulose-g-poly(potassium acrylate)/polyvinyl alcohol (WSC-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was prepared by polymerizing wheat straw and an aqueous solution of acrylic acid (AA), and further semi-interpenetrating with PVA occurred during the chemosynthesis. The swelling and deswelling properties of WSC-g-PKA/PVA semi-IPNs hydrogel and WSC-g-PKA hydrogel were studied and compared in various pH solutions, salt solutions, temperatures, particle sizes and ionic strength. The results indicated that both hydrogels had the largest swelling capacity at pH=6, and the effect of ions on the swelling of hydrogels was in the order: Na(+)>K(+)>Mg(2+)>Ca(2+). The Schott's pseudo second order model can be effectively used to evaluate swelling kinetics of hydrogels. Moreover, the semi-IPNs hydrogel had improved swelling-deswelling properties compared with that of WSC-g-PKA hydrogel.

  5. Construction of Modular Hydrogel Sheets for Micropatterned Macro-scaled 3D Cellular Architecture.

    PubMed

    Son, Jaejung; Bae, Chae Yun; Park, Je-Kyun

    2016-01-11

    Hydrogels can be patterned at the micro-scale using microfluidic or micropatterning technologies to provide an in vivo-like three-dimensional (3D) tissue geometry. The resulting 3D hydrogel-based cellular constructs have been introduced as an alternative to animal experiments for advanced biological studies, pharmacological assays and organ transplant applications. Although hydrogel-based particles and fibers can be easily fabricated, it is difficult to manipulate them for tissue reconstruction. In this video, we describe a fabrication method for micropatterned alginate hydrogel sheets, together with their assembly to form a macro-scale 3D cell culture system with a controlled cellular microenvironment. Using a mist form of the calcium gelling agent, thin hydrogel sheets are easily generated with a thickness in the range of 100 - 200 µm, and with precise micropatterns. Cells can then be cultured with the geometric guidance of the hydrogel sheets in freestanding conditions. Furthermore, the hydrogel sheets can be readily manipulated using a micropipette with an end-cut tip, and can be assembled into multi-layered structures by stacking them using a patterned polydimethylsiloxane (PDMS) frame. These modular hydrogel sheets, which can be fabricated using a facile process, have potential applications of in vitro drug assays and biological studies, including functional studies of micro- and macrostructure and tissue reconstruction.

  6. Removal of digoxin from plasma using monoclonal anti-digoxin antibodies immobilized on agarose

    SciTech Connect

    Brizgys, M.; Pincus, S.; Rollins, D.E.

    1986-05-01

    Monoclonal anti-digoxin antibodies (dig-Ab) have been covalently coupled to agarose supports to evaluate them as part of an extracorporeal device for removal of digoxin from the circulation. The agarose supports studied were Sepharose CL-6B, agarose-polyacrolein microsphere (APAM) beads, Bio Gel A-5m and Affi-gel 15 (Bio-Rad). Antibody concentrations between 2 and 4 mg/g gel were coupled to the agarose beads which were then placed in glass columns. Bovine ..cap alpha..-globulin coupled to the agarose supports was used as a control. Binding capacity and affinity of the immobilized antibody were determined by perfusing the dig-Ab agarose beads with a plasma solution containing /sup 3/H-digoxin and various concentrations of digoxin. The binding capacity of the immobilized dig-Ab was 30% of the theoretical value for Sepharose, Bio Gel and Affigel, and 10% of the theoretical value for dig-Ab coupled to APAM beads. The affinity of the immobilized dig-Ab was 10-100 fold less than non-immobilized Ab (3.4 x 10/sup 8/M/sup -1/. The APAM beads showed a significant decrease in binding of digoxin as the flow rate was increased from 0.5 to 5.0 ml/min. These data demonstrate that dig-Ab coupled to agarose and incorporated into a column can be used to remove digoxin from plasma in vitro.

  7. Laminin active peptide/agarose matrices as multifunctional biomaterials for tissue engineering.

    PubMed

    Yamada, Yuji; Hozumi, Kentaro; Aso, Akihiro; Hotta, Atsushi; Toma, Kazunori; Katagiri, Fumihiko; Kikkawa, Yamato; Nomizu, Motoyoshi

    2012-06-01

    Cell adhesive peptides derived from extracellular matrix components are potential candidates to afford bio-adhesiveness to cell culture scaffolds for tissue engineering. Previously, we covalently conjugated bioactive laminin peptides to polysaccharides, such as chitosan and alginate, and demonstrated their advantages as biomaterials. Here, we prepared functional polysaccharide matrices by mixing laminin active peptides and agarose gel. Several laminin peptide/agarose matrices showed cell attachment activity. In particular, peptide AG73 (RKRLQVQLSIRT)/agarose matrices promoted strong cell attachment and the cell behavior depended on the stiffness of agarose matrices. Fibroblasts formed spheroid structures on the soft AG73/agarose matrices while the cells formed a monolayer with elongated morphologies on the stiff matrices. On the stiff AG73/agarose matrices, neuronal cells extended neuritic processes and endothelial cells formed capillary-like networks. In addition, salivary gland cells formed acini-like structures on the soft matrices. These results suggest that the peptide/agarose matrices are useful for both two- and three-dimensional cell culture systems as a multifunctional biomaterial for tissue engineering.

  8. Magnetically Aligned Supramolecular Hydrogels

    PubMed Central

    Wallace, Matthew; Cardoso, Andre Zamith; Frith, William J; Iggo, Jonathan A; Adams, Dave J

    2014-01-01

    The magnetic-field-induced alignment of the fibrillar structures present in an aqueous solution of a dipeptide gelator, and the subsequent retention of this alignment upon transformation to a hydrogel upon the addition of CaCl2 or upon a reduction in solution pH is reported. Utilising the switchable nature of the magnetic field coupled with the slow diffusion of CaCl2, it is possible to precisely control the extent of anisotropy across a hydrogel, something that is generally very difficult to do using alternative methods. The approach is readily extended to other compounds that form viscous solutions at high pH. It is expected that this work will greatly expand the utility of such low-molecular-weight gelators (LMWG) in areas where alignment is key. PMID:25345918

  9. Enzyme actuated bioresponsive hydrogels

    NASA Astrophysics Data System (ADS)

    Wilson, Andrew Nolan

    Bioresponsive hydrogels are emerging with technological significance in targeted drug delivery, biosensors and regenerative medicine. Conferred with the ability to respond to specific biologically derived stimuli, the design challenge is in effectively linking the conferred biospecificity with an engineered response tailored to the needs of a particular application. Moreover, the fundamental phenomena governing the response must support an appropriate dynamic range and limit of detection. The design of these systems is inherently complicated due to the high interdependency of the governing phenomena that guide the sensing, transduction, and the actuation response of hydrogels. To investigate the dynamics of these materials, model systems may be used which seek to interrogate the system dynamics by uni-variable experimentation and limit confounding phenomena such as: polymer-solute interactions, polymer swelling dynamics and biomolecular reaction-diffusion concerns. To this end, a model system, alpha-chymotrypsin (Cht) (a protease) and a cleavable peptide-chromogen (pro-drug) covalently incorporated into a hydrogel, was investigated to understand the mechanisms of covalent loading and release by enzymatic cleavage in bio-responsive delivery systems. Using EDC and Sulfo-NHS, terminal carboxyl groups of N-succinyl-Ala-Ala-Pro-Phe p-nitroanilide, a cleavable chromogen, were conjugated to primary amines of a hydrated poly(HEMA)-based hydrogel. Hydrogel discs were incubated in buffered Cht causing enzyme-mediated cleavage of the peptide and concomitant release of the chromophore for monitoring. To investigate substrate loading and the effects of hydrogel morphology on the system, the concentration of the amino groups (5, 10, 20, and 30 mol%) and the cross-linked density (1, 5, 7, 9 and 12 mol%) were independently varied. Loading-Release Efficiency of the chromogen was shown to exhibit a positive relation to increasing amino groups (AEMA). The release rates demonstrated a

  10. Enzyme Induced Formation of Monodisperse Hydrogel Nanoparticles Tunable in Size

    SciTech Connect

    Bocharova, Vera; Sharp, Danna; Jones, Aaron; Cheng, Shiwang; Griffin, Philip J.; Agapov, Alexander L.; Voylov, Dmitry; Wang, Yangyang; Kisliuk, Alexander; Melman, Artem; Sokolov, Alexei P.

    2015-03-09

    Here, we report a novel approach to synthesize monodisperse hydrogel nanoparticles that are tunable in size. The distinctive feature of our approach is the use of a multicopper oxidase enzyme, laccase, as both a biocatalyst and template for nanoparticle growth. We utilize the ferroxidase activity of laccase to initiate localized production of iron(III) cations from the oxidation of iron(II) cations. We demonstrate that nanoparticles are formed in a dilute polymer solution of alginate as a result of cross-linking between alginate and enzymatically produced iron(III) cations. Exerting control over the enzymatic reaction allows for nanometer-scale tuning of the hydrogel nanoparticle radii in the range of 30–100 nm. Moreover, the nanoparticles and their growth kinetics were characterized via dynamic light scattering, atomic force microscopy, and UV–vis spectroscopy. Our finding opens up a new avenue for the synthesis of tunable nanoscale hydrogel particles for biomedical applications.

  11. Mediating conducting polymer growth within hydrogels by controlling nucleation

    NASA Astrophysics Data System (ADS)

    Patton, A. J.; Green, R. A.; Poole-Warren, L. A.

    2015-01-01

    This study examines the efficacy of primary and secondary nucleation for electrochemical polymerisation of conductive polymers within poly(vinyl alcohol) methacrylate hydrogels. The two methods of nucleation investigated were a primary heterogeneous mechanism via introduction of conductive bulk metallic glass (Mg64Zn30Ca5Na1) particles and a secondary mechanism via introduction of "pre-polymerised" conducting polymer within the hydrogel (PEDOT:PSS). Evidence of nucleation was not seen in the bulk metallic glass loaded gels, however, the PEDOT:PSS loaded gels produced charge storage capacities over 15 mC/cm2 when sufficient polymer was loaded. These studies support the hypothesis that secondary nucleation is an efficient approach to producing stand-alone conducting hydrogels.

  12. Promotion of Cell Growth and Adhesion of a Peptide Hydrogel Scaffold via mTOR/Cadherin Signaling.

    PubMed

    Wei, Guojun; Wang, Liping; Dong, Daming; Teng, Zhaowei; Shi, Zuowei; Wang, Kaifu; An, Gang; Guan, Ying; Han, Bo; Yao, Meng; Xian, Cory J

    2017-02-18

    Understanding neurite outgrowth, orientation, and migration is important for the design of biomaterials that interface with the neural tissue. However, the molecular signaling alternations have not been well elucidated to explain the impact of hydrogels on cell morphology. In our previous studies, a silk fibroin peptide (SF16) hydrogel was found to be an effective matrix for the viability, morphology and proliferation of PC12 rat pheocrhomocytoma cells. We found that PC12 cells in the peptide hydrogel exhibited adhesive morphology compared to those cultured in agarose or collagen. Moreover, we identified that cell adhesion molecules (E- and N-cadherin) controlled by mTOR signaling were highly induced in PC12 cells cultured in the SF16 peptide hydrogel. Our findings suggest that the SF16 peptide might be suitable to be a cell-adhesion material in cell culture or tissue engineering, and mTOR/cadherin signaling is required for the cell adhesion in the SF16-peptide hydrogel. This article is protected by copyright. All rights reserved.

  13. A new three dimensional biomimetic hydrogel to deliver factors secreted by human mesenchymal stem cells in spinal cord injury.

    PubMed

    Caron, Ilaria; Rossi, Filippo; Papa, Simonetta; Aloe, Rossella; Sculco, Marika; Mauri, Emanuele; Sacchetti, Alessandro; Erba, Eugenio; Panini, Nicolò; Parazzi, Valentina; Barilani, Mario; Forloni, Gianluigi; Perale, Giuseppe; Lazzari, Lorenza; Veglianese, Pietro

    2016-01-01

    Stem cell therapy with human mesenchymal stem cells (hMSCs) represents a promising strategy in spinal cord injury (SCI). However, both systemic and parenchymal hMSCs administrations show significant drawbacks as a limited number and viability of stem cells in situ. Biomaterials able to encapsulate and sustain hMSCs represent a viable approach to overcome these limitations potentially improving the stem cell therapy. In this study, we evaluate a new agarose/carbomer based hydrogel which combines different strategies to optimize hMSCs viability, density and delivery of paracrine factors. Specifically, we evaluate a new loading procedure on a lyophilized scaffold (soaked up effect) that reduces mechanical stress in encapsulating hMSCs into the hydrogel. In addition, we combine arginine-glycine-aspartic acid (RGD) tripeptide and 3D extracellular matrix deposition to increase the capacity to attach and maintain healthy hMSCs within the hydrogel over time. Furthermore, the fluidic diffusion from the hydrogel toward the injury site is improved by using a cling film that oriented efficaciously the delivery of paracrine factors in vivo. Finally, we demonstrate that an improved combination as here proposed of hMSCs and biomimetic hydrogel is able to immunomodulate significantly the pro-inflammatory environment in a SCI mouse model, increasing M2 macrophagic population and promoting a pro-regenerative environment in situ.

  14. Biomaterial characteristics and application of silicone rubber and PVA hydrogels mimicked in organ groups for prostate brachytherapy.

    PubMed

    Li, Pan; Jiang, Shan; Yu, Yan; Yang, Jun; Yang, Zhiyong

    2015-09-01

    It is definite that transparent material with similar structural characteristics and mechanical properties to human tissue is favorable for experimental study of prostate brachytherapy. In this paper, a kind of transparent polyvinyl alcohol (PVA) hydrogel and silicone rubber are developed as suitable substitutions for human soft tissue. Segmentation and 3D reconstruction of medical image are performed to manufacture the mould of organ groups through rapid prototyping technology. Micro-structure observation, force test and CCD deformation test have been conducted to investigate the structure and mechanical properties of PVA hydrogel used in organ group mockup. Scanning electron microscope (SEM) image comparison results show that PVA hydrogel consisting of 3 g PVA, 17 g de-ionized water, 80 g dimethyl-sulfoxide (DMSO), 4 g NaCl, 1.5 g NaOH, 3 g epichlorohydrin (ECH) and 7 freeze/thaw cycles reveals similar micro-structure to human prostate tissue. Through the insertion force comparison between organ group mockup and clinical prostate brachytherapy, PVA hydrogel and silicone rubber are found to have the same mechanical properties as prostate tissue and muscle. CCD deformation test results show that insertion force suffers a sharp decrease and a relaxation of tissue deformation appears when needle punctures the capsule of prostate model. The results exhibit that organ group mockup consisting of PVA hydrogel, silicone rubber, membrane and agarose satisfies the needs of prostate brachytherapy simulation in general and can be used to mimic the soft tissues in pelvic structure.

  15. Complexation hydrogels for intestinal delivery of interferon beta and calcitonin.

    PubMed

    Kamei, Noriyasu; Morishita, Mariko; Chiba, Hitomi; Kavimandan, Nikhil J; Peppas, Nicholas A; Takayama, Kozo

    2009-03-04

    Recent studies have suggested that complexation hydrogels poly(methacrylic acid-g-ethylene glycol) (henceforth designated as P(MAA-g-EG)) exhibit high insulin incorporation efficiency, rapid insulin release in the intestine based on their pH-dependent complexation properties, enzyme-inhibiting effects and mucoadhesive characteristics. Therefore, they are promising carriers for insulin delivery via an oral route. As we designed these hydrogels as carriers suitable for oral administration of various peptide/protein drugs, in this study we aimed at investigating the applicability of P(MAA-g-EG) hydrogels to improving the intestinal absorption of various peptide/protein drugs. High loading efficiency into hydrogels was observed for insulin, calcitonin, and interferon beta. In addition, polymer microparticles loaded with calcitonin and interferon beta exhibited complexation/decomplexation and pH-sensitive release behavior. The molecular weight and chemical structure appeared to affect the efficiency of loading and release depending on the peptides and proteins. Furthermore, a drastic reduction of plasma calcium concentration accompanied by calcium absorption and a dose-dependent enhancement of plasma interferon beta concentration were observed after the administration of particles loaded with calcitonin or interferon beta into closed rat ileal segments. These findings indicate that P(MAA-g-EG) hydrogels are promising carriers for administration of various peptides and proteins via an oral route.

  16. Hydrogel films and coatings by swelling-induced gelation.

    PubMed

    Moreau, David; Chauvet, Caroline; Etienne, François; Rannou, François P; Corté, Laurent

    2016-11-22

    Hydrogel films used as membranes or coatings are essential components of devices interfaced with biological systems. Their design is greatly challenged by the need to find mild synthesis and processing conditions that preserve their biocompatibility and the integrity of encapsulated compounds. Here, we report an approach to produce hydrogel films spontaneously in aqueous polymer solutions. This method uses the solvent depletion created at the surface of swelling polymer substrates to induce the gelation of a thin layer of polymer solution. Using a biocompatible polymer that self-assembles at high concentration [poly(vinyl alcohol)], hydrogel films were produced within minutes to hours with thicknesses ranging from tens to hundreds of micrometers. A simple model and numerical simulations of mass transport during swelling capture the experiments and predict how film growth depends on the solution composition, substrate geometry, and swelling properties. The versatility of the approach was verified with a variety of swelling substrates and hydrogel-forming solutions. We also demonstrate the potential of this technique by incorporating other solutes such as inorganic particles to fabricate ceramic-hydrogel coatings for bone anchoring and cells to fabricate cell-laden membranes for cell culture or tissue engineering.

  17. Starch nanocrystals based hydrogel: Construction, characterizations and transdermal application.

    PubMed

    Bakrudeen, Haja Bava; Sudarvizhi, C; Reddy, B S R

    2016-11-01

    Bio-based nanocomposites were prepared using starch nanocrystals obtained by acid hydrolysis of native starches using different acid sources. In recent times, focuses on starch nanocrystals (SNCs) have been increasing in number of research works dedicated to the development of bio-nanocomposites by blending with different biopolymeric matrices. The work mainly deals with the preparation of starch nanocrystals using different native starches by acid hydrolysis using hydrochloric acid and trifluroacetic acid. The as-prepared starch nanocrystals are having high crystallinity and more platelet morphologies, and used as a drug carrying filler material in the hydrogel formulations with the care of different polymer matrices. The condensed work also concentrates on the dispersion of antiviral drug in the hydrogels, which are applied onto biocompatible bio-membrane to be formulating a complete transdermal patch. The acid hydrolysed starch nanocrystals were thoroughly characterized using TEM, SEM, particle size analysis and zeta potential. Their thermal stability and the crystalline properties were also characterized using TG-DSC and XRD respectively. The physiochemical interaction and compatibility between the drug and the SNCs filler in the polymeric hydrogels were evaluated using FT-IR analysis. The formulated hydrogels were subjected to evaluation of in vitro permeation studies using Franz diffusion studies. The in vitro study was indicated substantial guarantee for the fabrication of drug dispersed in polymeric hydrogels using SNCs as filler matrices for a successful transdermal drug delivery.

  18. Self-Adjustable Adhesion of Polyampholyte Hydrogels.

    PubMed

    Roy, Chanchal Kumar; Guo, Hong Lei; Sun, Tao Lin; Ihsan, Abu Bin; Kurokawa, Takayuki; Takahata, Masakazu; Nonoyama, Takayuki; Nakajima, Tasuku; Gong, Jian Ping

    2015-12-02

    Developing nonspecific, fast, and strong adhesives that can glue hydrogels and biotissues substantially promotes the application of hydrogels as biomaterials. Inspired by the ubiquitous adhesiveness of bacteria, it is reported that neutral polyampholyte hydrogels, through their self-adjustable surface, can show rapid, strong, and reversible adhesion to charged hydrogels and biological tissues through the Coulombic interaction.

  19. Cartilage tissue engineering application of injectable gelatin hydrogel with in situ visible-light-activated gelation capability in both air and aqueous solution.

    PubMed

    Lin, Hang; Cheng, Anthony Wai-Ming; Alexander, Peter G; Beck, Angela M; Tuan, Rocky S

    2014-09-01

    Chondroprogenitor cells encapsulated in a chondrogenically supportive, three-dimensional hydrogel scaffold represents a promising, regenerative approach to articular cartilage repair. In this study, we have developed an injectable, biodegradable methacrylated gelatin (mGL)-based hydrogel capable of rapid gelation via visible light (VL)-activated crosslinking in air or aqueous solution. The mild photocrosslinking conditions permitted the incorporation of cells during the gelation process. Encapsulated human-bone-marrow-derived mesenchymal stem cells (hBMSCs) showed high, long-term viability (up to 90 days) throughout the scaffold. To assess the applicability of the mGL hydrogel for cartilage tissue engineering, we have evaluated the efficacy of chondrogenesis of the encapsulated hBMSCs, using hBMSCs seeded in agarose as control. The ability of hBMSC-laden mGL constructs to integrate with host tissues after implantation was further investigated utilizing an in vitro cartilage repair model. The results showed that the mGL hydrogel, which could be photopolymerized in air and aqueous solution, supports hBMSC growth and TGF-β3-induced chondrogenesis. Compared with agarose, mGL constructs laden with hBMSCs are mechanically stronger with time, and integrate well with native cartilage tissue upon implantation based on push-out mechanical testing. VL-photocrosslinked mGL scaffold thus represents a promising scaffold for cell-based repair and resurfacing of articular cartilage defects.

  20. Constructing 3D heterogeneous hydrogels from electrically manipulated prepolymer droplets and crosslinked microgels

    PubMed Central

    Chiang, Min-Yu; Hsu, Yao-Wen; Hsieh, Hsin-Yi; Chen, San-Yuan; Fan, Shih-Kang

    2016-01-01

    Formation of multifunctional, heterogeneous, and encoded hydrogel building blocks, or microgels, by crosslinking and assembly of microgels are two essential steps in establishing hierarchical, complicated, and three-dimensional (3D) hydrogel architectures that recapitulate natural and biological structures or originate new materials by design. However, for the variety of the hydrogel materials crosslinked differently and for the varied scales of microgels and architectures, the formation and assembly processes are usually performed separately, which increases the manufacturing complexity of designed hydrogel materials. We show the construction of hydrogel architectures through programmable formation and assembly on an electromicrofluidic platform, adopting two reciprocal electric manipulations (electrowetting and dielectrophoresis) to manipulate varied objects (i) in multiple phases, including prepolymer liquid droplets and crosslinked microgels, (ii) on a wide range of scales from micrometer functional particles or cells to millimeter-assembled hydrogel architectures, and (iii) with diverse properties, such as conductive and dielectric droplets that are photocrosslinkable, chemically crosslinkable, or thermally crosslinkable. Prepolymer droplets, particles, and dissolved molecules are electrically addressable to adjust the properties of the microgel building blocks in liquid phase that subsequently undergo crosslinking and assembly in a flexible sequence to accomplish heterogeneous and seamless hydrogel architectures. We expect the electromicrofluidic platform to become a general technique to obtain 3D complex architectures. PMID:27819046

  1. Hydroxyethyl starch-based polymers for the controlled release of biomacromolecules from hydrogel microspheres.

    PubMed

    Wöhl-Bruhn, Stefanie; Bertz, Andreas; Harling, Steffen; Menzel, Henning; Bunjes, Heike

    2012-08-01

    Hydrogels are promising delivery systems for the controlled release of biomacromolecules. Based on previous studies, hydrogels were prepared from crosslinkable hydroxyethyl starch with new linker groups to improve mechanical and release properties of the resulting hydrogels. Polyethylene glycol methacrylate with two different spacer lengths was used to obtain polymers (HES-P(EG)(n)MA) with increased hydrophilicity and degradability, whereas a polymer with methacrylate linker directly at the starch backbone (HES-MA) resulted in a less degradable polymer. Hydrogel disks were obtained by UV crosslinking and characterized by swelling and rheological measurements. The hydrogel strength was strongly influenced by the polymer concentration. Using a water-in-water emulsion process, hydrogel microspheres were prepared. The influence of the type of the linker, the degree of substitution and the phase ratio in the production process on the properties of the microspheres was investigated. Depending on the preparation parameters, particles with narrow particle size distribution and encapsulation efficiencies of up to more than 80% for FITC-dextran 70 kDa (FD70) were obtained. Incorporated FITC-labeled IgG showed a faster release from hydrogel microspheres than FD70. The release rate of incorporated FD70 could be adjusted by using different polymers (HES-P(EG)(10)MA>HES-P(EG)(6)MA>HES-MA).

  2. Rapid self-healing hydrogels

    PubMed Central

    Phadke, Ameya; Zhang, Chao; Arman, Bedri; Hsu, Cheng-Chih; Mashelkar, Raghunath A.; Lele, Ashish K.; Tauber, Michael J.; Arya, Gaurav; Varghese, Shyni

    2012-01-01

    Synthetic materials that are capable of autonomous healing upon damage are being developed at a rapid pace because of their many potential applications. Despite these advancements, achieving self-healing in permanently cross-linked hydrogels has remained elusive because of the presence of water and irreversible cross-links. Here, we demonstrate that permanently cross-linked hydrogels can be engineered to exhibit self-healing in an aqueous environment. We achieve this feature by arming the hydrogel network with flexible-pendant side chains carrying an optimal balance of hydrophilic and hydrophobic moieties that allows the side chains to mediate hydrogen bonds across the hydrogel interfaces with minimal steric hindrance and hydrophobic collapse. The self-healing reported here is rapid, occurring within seconds of the insertion of a crack into the hydrogel or juxtaposition of two separate hydrogel pieces. The healing is reversible and can be switched on and off via changes in pH, allowing external control over the healing process. Moreover, the hydrogels can sustain multiple cycles of healing and separation without compromising their mechanical properties and healing kinetics. Beyond revealing how secondary interactions could be harnessed to introduce new functions to chemically cross-linked polymeric systems, we also demonstrate various potential applications of such easy-to-synthesize, smart, self-healing hydrogels. PMID:22392977

  3. Agarose Gel Electrophoresis Reveals Structural Fluidity of a Phage T3 DNA Packaging Intermediate

    PubMed Central

    Serwer, Philip; Wright, Elena T.

    2012-01-01

    We find a new aspect of DNA packaging-associated structural fluidity for phage T3 capsids. The procedure is (1) glutaraldehyde cross-linking of in vivo DNA packaging intermediates for stabilization of structure and then (2) determining of effective radius by two-dimensional agarose gel electrophoresis (2d-AGE). The intermediates are capsids with incompletely packaged DNA (ipDNA) and without an external DNA segment; these intermediates are called ipDNA-capsids. We initially increase production of ipDNA-capsids by raising NaCl concentration during in vivo DNA packaging. By 2d-AGE, we find a new state of contracted shell for some particles of one previously identified ipDNA-capsid. The contracted shell-state is found when ipDNA length/mature DNA length (F) is above 0.17, but not at lower F. Some contracted-shell ipDNA-capsids have the phage tail; others do not. The contracted-shell ipDNA-capsids are explained by premature DNA maturation cleavage that makes accessible a contracted-shell intermediate of a cycle of the T3 DNA packaging motor. The analysis of ipDNA-capsids, rather than intermediates with uncleaved DNA, provides a simplifying strategy for a complete biochemical analysis of in vivo DNA packaging. PMID:22222979

  4. Agarose gel electrophoresis and polyacrylamide gel electrophoresis for visualization of simple sequence repeats.

    PubMed

    Anderson, James; Wright, Drew; Meksem, Khalid

    2013-01-01

    In the modern age of genetic research there is a constant search for ways to improve the efficiency of plant selection. The most recent technology that can result in a highly efficient means of selection and still be done at a low cost is through plant selection directed by simple sequence repeats (SSRs or microsatellites). The molecular markers are used to select for certain desirable plant traits without relying on ambiguous phenotypic data. The best way to detect these is the use of gel electrophoresis. Gel electrophoresis is a common technique in laboratory settings which is used to separate deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) by size. Loading DNA and RNA onto gels allows for visualization of the size of fragments through the separation of DNA and RNA fragments. This is achieved through the use of the charge in the particles. As the fragments separate, they form into distinct bands at set sizes. We describe the ability to visualize SSRs on slab gels of agarose and polyacrylamide gel electrophoresis.

  5. Agarose gel electrophoresis reveals structural fluidity of a phage T3 DNA packaging intermediate.

    PubMed

    Serwer, Philip; Wright, Elena T

    2012-01-01

    We find a new aspect of DNA packaging-associated structural fluidity for phage T3 capsids. The procedure is (i) glutaraldehyde cross-linking of in vivo DNA packaging intermediates for the stabilization of structure and then (ii) determining effective radius by two-dimensional agarose gel electrophoresis (2D-AGE). The intermediates are capsids with incompletely packaged DNA (ipDNA) and without an external DNA segment; these intermediates are called ipDNA-capsids. We initially increase the production of ipDNA-capsids by raising NaCl concentration during in vivo DNA packaging. By 2D-AGE, we find a new state of contracted shell for some particles of one previously identified ipDNA-capsid. The contracted shell-state is found when the ipDNA length/mature DNA length (F) is above 0.17, but not at lower F. Some contracted-shell ipDNA-capsids have the phage tail; others do not. The contracted-shell ipDNA-capsids are explained by premature DNA maturation cleavage that makes accessible a contracted-shell intermediate of a cycle of the T3 DNA packaging motor. The analysis of ipDNA-capsids, rather than intermediates with uncleaved DNA, provides a simplifying strategy for a complete biochemical analysis of in vivo DNA packaging.

  6. DNA-functionalized hydrogels for confined membrane-free in vitro transcription/translation.

    PubMed

    Thiele, J; Ma, Y; Foschepoth, D; Hansen, M M K; Steffen, C; Heus, H A; Huck, W T S

    2014-08-07

    We microfluidically fabricate bio-orthogonal DNA-functionalized porous hydrogels from hyaluronic acid that are employed in in vitro transcription/translation (IVTT) of a green fluorescent protein. By co-encapsulating individual hydrogel particles and the IVTT machinery in water-in-oil microdroplets, we study protein expression in a defined reaction volume. Our approach enables precise control over protein expression rates by gene dosage. We show that gene transcription and translation are confined to the membrane-free hydrogel matrix, which contributes to the design of membrane-free protocells.

  7. Sodium dodecyl sulfate-agarose gel electrophoresis for the detection and isolation of amyloid curli fibers.

    PubMed

    Sitaras, Chris; Naghavi, Mahsa; Herrington, Muriel B

    2011-01-15

    Curli are amyloid-like fibers on the surface of some strains of Escherichia coli and Salmonella enteritidis. We tested the use of horizontal sodium dodecyl sulfate (SDS)-agarose gel electrophoresis to detect, isolate, and quantitate curli. Cell extracts fractionated in SDS-agarose gels and stained with Coomassie blue exhibited a soluble fraction that entered the gel and an insoluble fraction that remained in the well. Much more insoluble material was observed with curli-proficient strains than with strains that do not make curli. Both highly purified curli and the insoluble material isolated from an SDS-agarose gel could be dissociated into monomers when treated with formic acid. For quantitation, we immobilized samples in SDS-agarose prior to electrophoresis. This avoids losses during the staining of the gel. Our methods provide a rapid and simple fractionation of curli using equipment that is readily available.

  8. Effect of ultrasound on the separation of DNA fragments in agarose gel electrophoresis

    SciTech Connect

    Ma, Yinfa; Yeung, E.S. )

    1990-06-01

    Since its first use in 1966 interest in and the applications of electrophoresis of DNA fragments in agarose gel have grown rapidly. Nowadays, agarose gel electrophoresis has become a standard technique with high resolving power for the analysis of DNA structure, for example for the determination of the length of DNA fragments obtained by the action of restriction enzymes. The electrophoretic mobility ({mu}) of DNA fragments is influenced by various parameters-molecular weight, gel concentration, temperature, electric field, and DNA-agarose affinity. A comprehensive study of the influence of these main parameters has been reported. In this paper, the authors investigate a new effect on the electrophoretic mobility of DNA fragments in agarose gels, viz. the influence of ultrasound.

  9. Induced Motion by Asymmetric Enzymatic Degradation of Hydrogels

    NASA Astrophysics Data System (ADS)

    Hou, Jennifer; Cohen, Adam

    2012-02-01

    Biological hydrogels are continuously turned over through secretion and degradation. This non-equilibrium flux is critical to understanding cellular and molecular transport through biogels such as mucus and the extracellular matrix. Gel-digesting enzymes can drastically change the physical and chemical properties of the hydrogel environment. We report that a spatial gradient in the degradation of two gel/enzyme systems--gelatin/trypsin and hyaluronan/hyaluronidase--leads to directional motion of particles embedded in the gel in the direction of higher enzyme concentration. We study the rate at which the degradation front propagates through the gel and the ensuing velocity of the embedded particles, as functions of enzyme and gel concentrations. We propose that asymmetric degradation leads to asymmetric swelling, which transports particles up the enzyme concentration gradient.

  10. Elastic and macroporous agarose-gelatin cryogels with isotropic and anisotropic porosity for tissue engineering.

    PubMed

    Tripathi, Anuj; Kathuria, Neeraj; Kumar, Ashok

    2009-09-01

    The focus of this work was to design a macroporous scaffold with controlled porosity in isotropic and anisotropic manner for tissue-engineering applications. Agarose-gelatin scaffolds were synthesized by cryogelation method, in which agarose was used to improve the mechanical characteristics and gelatin-provided amiable property of elasticity, cell adhesion, and cell proliferation in the scaffold. Agarose-gelatin (8%) cryogels synthesized in two different solvent systems (i.e., water and 0.1% acetic acid) at subzero temperature (-12 degrees C) showed well-interconnected porous structure. The agarose-gelatin cryogel synthesized in water solvent system (WSS) showed gradient porosity with an average pore diameter of a monolith (four sections from bottom to top; height 5 mm and diameter 13 mm each) ranging from 76 to 187 microm. The monolith of agarose-gelatin synthesized in 0.1% acetic acid solvent system (0.1% ASS) did not show any remarkable difference in average pore diameter of a monolith to their whole column length as revealed by scanning electron microscopy (SEM). These cryogels swelled up to approximately 90% of their capacity within 1 min. The aggregate tensile modulus showed good elasticity of the cryogels, in which agarose-gelatin synthesized in WSS showed higher tensile modulus, that is, 380.23 +/- 63.97 kPa in comparison with agarose-gelatin synthesized in 0.1% ASS, i.e., 278.08 +/- 94.08 kPa. The unconfined fatigue observation with varying strain (10-40%) and varying frequencies (2 and 5 Hz) showed no deformation of cryogels. The fibroblast (Cos-7) cell line seeded on the scaffold displayed good cell attachment in both types of cryogels and MTT assay showed good cell compatibility and favorable conditions for cell proliferation. These results indicate that agarose-gelatin cryogels can be a promising material of choice for tissue-engineering applications.

  11. A simple and effective SuperBuffer for DNA agarose electrophoresis.

    PubMed

    Zhang, Jun-He; Wang, Fang; Wang, Tian-Yun

    2011-11-01

    In the paper, we describe a unique effective electrophoresis buffer for DNA agarose electrophoresis, called SuperBuffer. Using this buffer, electrophoresis could be performed within 10 min at voltages as high as 25V/cm. In addition, DNA fragments of different lengths could be isolated clearly even at lower agarose gel concentrations and the DNA recovery efficiency was higher than that of the TAE/TBE running buffers. The SuperBuffer still retained its electrophoretic effect even after several uses.

  12. Ultra-deep desulfurization via reactive adsorption on peroxophosphomolybdate/agarose hybrids.

    PubMed

    Xu, Jian; Li, Huacheng; Wang, Shengtian; Luo, Fang; Liu, Yunyu; Wang, Xiaohong; Jiang, Zijiang

    2014-09-01

    A catalyst system composed of peroxophosphomolybdates as catalytic center and agarose as matrix material had been designed. The [C16H33N(CH3)3]3[PO4{MoO(O2)2}4]/agarose (C16PMo(O2)2/agarose) hybrid was found to be active for oxidation desulfurization (ODS) of dibenzothiophene (DBT) or real fuel into corresponding sulfone by H2O2 as an oxidant, while the sulfur content could be reduced to 5ppm. The higher activity comes from its components including [PO4{MoO(O2)2}4] catalytic sites, the hydrophobic quaternary ammonium cation affinity to low polarity substrates, and agarose matrix affinity to H2O2 and sulfone. During the oxidative reaction, the mass transfer resistance between H2O2 and organic sulfurs could be decreased and the reaction rate could increase by the assistance of agarose and hydrophobic tails of [C16H33N(CH3)3]3[PO4{MoO(O2)2}4]. Meanwhile, the oxidative products could be adsorbed by agarose matrix to give clean fuel avoiding the post-treatment. In addition, the hybrid was easily regenerated to be reused.

  13. A microfluidic device for on-chip agarose microbead generation with ultralow reagent consumption.

    PubMed

    Desbois, Linda; Padirac, Adrien; Kaneda, Shohei; Genot, Anthony J; Rondelez, Yannick; Hober, Didier; Collard, Dominique; Fujii, Teruo

    2012-01-01

    Water-in-oil microdroplets offer microreactors for compartmentalized biochemical reactions with high throughput. Recently, the combination with a sol-gel switch ability, using agarose-in-oil microdroplets, has increased the range of possible applications, allowing for example the capture of amplicons in the gel phase for the preservation of monoclonality during a PCR reaction. Here, we report a new method for generating such agarose-in-oil microdroplets on a microfluidic device, with minimized inlet dead volume, on-chip cooling, and in situ monitoring of biochemical reactions within the gelified microbeads. We used a flow-focusing microchannel network and successfully generated agarose microdroplets at room temperature using the "push-pull" method. This method consists in pushing the oil continuous phase only, while suction is applied to the device outlet. The agarose phase present at the inlet is thus aspirated in the device, and segmented in microdroplets. The cooling system consists of two copper wires embedded in the microfluidic device. The transition from agarose microdroplets to microbeads provides additional stability and facilitated manipulation. We demonstrate the potential of this method by performing on-chip a temperature-triggered DNA isothermal amplification in agarose microbeads. Our device thus provides a new way to generate microbeads with high throughput and no dead volume for biochemical applications.

  14. Encapsulation of chondrocytes in high-stiffness agarose microenvironments for in vitro modeling of osteoarthritis mechanotransduction.

    PubMed

    Jutila, Aaron A; Zignego, Donald L; Schell, William J; June, Ronald K

    2015-05-01

    In articular cartilage, chondrocytes reside within a gel-like pericellular matrix (PCM). This matrix provides a mechanical link through which joint loads are transmitted to chondrocytes. The stiffness of the PCM decreases in the most common degenerative joint disease, osteoarthritis. To develop a system for modeling the stiffness of both the healthy and osteoarthritic PCM, we determined the concentration-stiffness relationships for agarose. We extended these results to encapsulate chondrocytes in agarose of physiological stiffness. Finally, we assessed the relevance of stiffness for chondrocyte mechanotransduction by examining the biological response to mechanical loading for cells encapsulated in low- and high-stiffness gels. We achieved agarose equilibrium stiffness values as large as 51.3 kPa. At 4.0% agarose, we found equilibrium moduli of 34.3 ± 1.65 kPa, and at 4.5% agarose, we found equilibrium moduli of 35.7 ± 0.95 kPa. Cyclical tests found complex moduli of ~100-300 kPa. Viability was >96% for all studies. We observed distinct metabolomic responses in >500 functional small molecules describing changes in cell physiology, between primary human chondrocytes encapsulated in 2.0 and 4.5% agarose indicating that the gel stiffness affects cellular mechanotransduction. These data demonstrate both the feasibility of modeling the chondrocyte pericellular matrix stiffness and the importance of the physiological pericellular stiffness for understanding chondrocyte mechanotransduction.

  15. Hydrogels and scaffolds for immunomodulation.

    PubMed

    Singh, Ankur; Peppas, Nicholas A

    2014-10-01

    For over two decades, immunologists and biomaterials scientists have co-existed in parallel world with the rationale of understanding the molecular profile of immune responses to vaccination, implantation, and treating incurable diseases. Much of the field of biomaterial-based immunotherapy has relied on evaluating model antigens such as chicken egg ovalbumin in mouse models but their relevance to humans has been point of much discussion. Nevertheless, such model antigens have provided important insights into the mechanisms of immune regulation and served as a proof-of-concept for plethora of biomaterial-based vaccines. After years of extensive development of numerous biomaterials for immunomodulation, it is only recently that an experimental scaffold vaccine implanted beneath the skin has begun to use the human model to study the immune responses to cancer vaccination by co-delivering patient-derived tumor lysates and immunomodulatory proteins. If successful, this scaffold vaccine will change the way we approached untreatable cancers, but more importantly, will allow a faster and more rational translation of therapeutic regimes to other cancers, chronic infections, and autoimmune diseases. Most materials reviews have focused on immunomodulatory adjuvants and micro-nano-particles. Here we provide an insight into emerging hydrogel and scaffold based immunomodulatory approaches that continue to demonstrate efficacy against immune associated diseases.

  16. Viscoelastic behaviour of hydrogel-based composites for tissue engineering under mechanical load.

    PubMed

    Kocen, Rok; Gasik, Michael; Gantar, Ana; Novak, Saša

    2017-03-06

    Along with biocompatibility, bioinductivity and appropriate biodegradation, mechanical properties are also of crucial importance for tissue engineering scaffolds. Hydrogels, such as gellan gum (GG), are usually soft materials, which may benefit from the incorporation of inorganic particles, e.g. bioactive glass, not only due to the acquired bioactivity, but also due to improved mechanical properties. They exhibit complex viscoelastic properties, which can be evaluated in various ways. In this work, to reliably evaluate the effect of the bioactive glass (BAG) addition on viscoelastic properties of the composite hydrogel, we employed and compared the three most commonly used techniques, analyzing their advantages and limitations: monotonic uniaxial unconfined compression, small amplitude oscillatory shear (SAOS) rheology and dynamic mechanical analysis (DMA). Creep and small amplitude dynamic strain-controlled tests in DMA are suggested as the best ways for the characterization of mechanical properties of hydrogel composites, whereas the SAOS rheology is more useful for studying the hydrogel's processing kinetics, as it does not induce volumetric changes even at very high strains. Overall, the results confirmed a beneficial effect of BAG (nano)particles on the elastic modulus of the GG-BAG composite hydrogel. The Young's modulus of 6.6 ± 0.8 kPa for the GG hydrogel increased by two orders of magnitude after the addition of 2 wt.% BAG particles (500-800 kPa).

  17. Hyaluronic Acid-Based Hydrogels: from a Natural Polysaccharide to Complex Networks

    PubMed Central

    Xu, Xian; Jha, Amit K.; Harrington, Daniel A.; Farach-Carson, Mary C.; Jia, Xinqiao

    2012-01-01

    Hyaluronic acid (HA) is one of nature's most versatile and fascinating macromolecules. Being an essential component of the natural extracellular matrix (ECM), HA plays an important role in a variety of biological processes. Inherently biocompatible, biodegradable and non-immunogenic, HA is an attractive starting material for the construction of hydrogels with desired morphology, stiffness and bioactivity. While the interconnected network extends to the macroscopic level in HA bulk gels, HA hydrogel particles (HGPs, microgels or nanogels) confine the network to microscopic dimensions. Taking advantage of various scaffold fabrication techniques, HA hydrogels with complex architecture, unique anisotropy, tunable viscoelasticity and desired biologic outcomes have been synthesized and characterized. Physical entrapment and covalent integration of hydrogel particles in a secondary HA network give rise to hybrid networks that are hierarchically structured and mechanically robust, capable of mediating cellular activities through the spatial and temporal presentation of biological cues. This review highlights recent efforts in converting a naturally occurring polysaccharide to drug releasing hydrogel particles, and finally, complex and instructive macroscopic networks. HA-based hydrogels are promising materials for tissue repair and regeneration. PMID:22419946

  18. High-resolution synchrotron X-ray analysis of bioglass-enriched hydrogels.

    PubMed

    Gorodzha, Svetlana; Douglas, Timothy E L; Samal, Sangram K; Detsch, Rainer; Cholewa-Kowalska, Katarzyna; Braeckmans, Kevin; Boccaccini, Aldo R; Skirtach, Andre G; Weinhardt, Venera; Baumbach, Tilo; Surmeneva, Maria A; Surmenev, Roman A

    2016-05-01

    Enrichment of hydrogels with inorganic particles improves their suitability for bone regeneration by enhancing their mechanical properties, mineralizability, and bioactivity as well as adhesion, proliferation, and differentiation of bone-forming cells, while maintaining injectability. Low aggregation and homogeneous distribution maximize particle surface area, promoting mineralization, cell-particle interactions, and homogenous tissue regeneration. Hence, determination of the size and distribution of particles/particle agglomerates in the hydrogel is desirable. Commonly used techniques have drawbacks. High-resolution techniques (e.g., SEM) require drying. Distribution in the dry state is not representative of the wet state. Techniques in the wet state (histology, µCT) are of lower resolution. Here, self-gelling, injectable composites of Gellan Gum (GG) hydrogel and two different types of sol-gel-derived bioactive glass (bioglass) particles were analyzed in the wet state using Synchrotron X-ray radiation, enabling high-resolution determination of particle size and spatial distribution. The lower detection limit volume was 9 × 10(-5) mm(3) . Bioglass particle suspensions were also studied using zeta potential measurements and Coulter analysis. Aggregation of bioglass particles in the GG hydrogels occurred and aggregate distribution was inhomogeneous. Bioglass promoted attachment of rat mesenchymal stem cells (rMSC) and mineralization.

  19. Biomimetic fiber assembled gradient hydrogel to engineer glycosaminoglycan enriched and mineralized cartilage: An in vitro study.

    PubMed

    Mohan, Neethu; Wilson, Jijo; Joseph, Dexy; Vaikkath, Dhanesh; Nair, Prabha D

    2015-12-01

    The study investigated the potential of electrospun fiber assembled hydrogel, with physical gradients of chondroitin sulfate (CS) and sol-gel-derived bioactive glass (BG), to engineer hyaline and mineralized cartilage in a single 3D system. Electrospun poly(caprolactone) (PCL) fibers incorporated with 0.1% w/w of CS (CSL) and 0.5% w/w of CS (CSH), 2.4% w/w of BG (BGL) and 12.5% w/w of BG (BGH) were fabricated. The CS showed a sustained release up to 3 days from CSL and 14 days from CSH fibers. Chondrocytes secreted hyaline like matrix with higher sulfated glycosaminoglycans (sGAG), collagen type II and aggrecan on CSL and CSH fibers. Mineralization was observed on BGL and BGH fibers when incubated in simulated body fluid for 14 days. Chondrocytes cultured on these fibers secreted a mineralized matrix that consisted of sGAG, hypertrophic proteins, collagen type X, and osteocalcin. The CS and BG incorporated PCL fiber mats were assembled in an agarose-gelatin hydrogel to generate a 3D hybrid scaffold. The signals in the fibers diffused and generated continuous opposing gradients of CS (chondrogenic signal) and BG (mineralization) in the hydrogel. The chondrocytes were encapsulated in hybrid scaffolds; live dead assay at 48 h showed viable cells. Cells maintained their phenotype and secreted specific extracellular matrix (ECM) in response to signals within the hydrogel. Continuous opposing gradients of sGAG enriched and mineralized ECM were observed surrounding each cell clusters on gradient hydrogel after 14 days of culture in response to the physical gradients of raw materials CS and BG. A construct with gradient mineralization might accelerate integration to subchondral bone during in vivo regeneration.

  20. In Vivo Bioluminescent Tracking of Mesenchymal Stem Cells Within Large Hydrogel Constructs

    PubMed Central

    Allen, Ashley B.; Gazit, Zulma; Su, Susan; Stevens, Hazel Y.

    2014-01-01

    The use of multicomponent scaffolds for cell implantation has necessitated sophisticated techniques for tracking of cell survival in vivo. Bioluminescent imaging (BLI) has emerged as a noninvasive tool for evaluating the therapeutic potential of cell-based tissue engineering strategies. However, the ability to use BLI measurements to longitudinally assess large 3D cellular constructs in vivo and the effects of potential confounding factors are poorly understood. In this study, luciferase-expressing human mesenchymal stem cells (hMSCs) were delivered subcutaneously within agarose and RGD-functionalized alginate hydrogel vehicles to investigate the impact of construct composition and tissue formation on BLI signal. Results showed that alginate constructs exhibited twofold greater BLI counts than agarose constructs at comparable hMSC doses. However, each hydrogel type produced a linear correlation between BLI counts and live cell number, indicating that within a given material, relative differences in cell number could be accurately assessed at early time points. The survival efficiency of delivered hMSCs was highest for the lower cell doses embedded within alginate matrix. BLI signal remained predictive of live cell number through 1 week in vivo, although the strength of correlation decreased over time. Irrespective of hydrogel type or initial hMSC seeding dose, all constructs demonstrated a degree of vascularization and development of a fibrotic capsule after 1 week. Formation of tissue within and adjacent to the constructs was accompanied by an attenuation of BLI signal during the initial period of the image acquisition time-frame. In alginate constructs only, greater vessel volume led to a delayed rise in BLI signal following luciferin delivery. This study identified vascular and fibrotic tissue ingrowth as potential confounding variables for longitudinal BLI studies. Further investigation into the complexities of noninvasive BLI data acquisition from

  1. Antimicrobial chitosan-PVA hydrogel as a nanoreactor and immobilizing matrix for silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Agnihotri, Shekhar; Mukherji, Soumyo; Mukherji, Suparna

    2012-09-01

    Hydrogels are water-insoluble crosslinked hydrophilic networks capable of retaining a large amount of water. The present work aimed to develop a novel chitosan-PVA-based hydrogel which could behave both as a nanoreactor and an immobilizing matrix for silver nanoparticles (AgNPs) with promising antibacterial applications. The hydrogel containing AgNPs were prepared by repeated freeze-thaw treatment using varying amounts of the crosslinker, followed by in situ reduction with sodium borohydride as a reducing agent. Characterization studies established that the hydrogel provides a controlled and uniform distribution of nanoparticles within the polymeric network without addition of any further stabilizer. The average particle size was found to be 13 nm with size distribution from 8 to 21 nm as per HR-TEM studies. Swelling studies confirmed that higher amount of crosslinker and silver incorporation inside the gel matrices significantly enhanced the porosity and chain entanglement of the polymeric species of the hydrogel, respectively. The AgNP-hydrogel exhibited good antibacterial activity and was found to cause significant reduction in microbial growth ( Escherichia coli) in 12 h while such activity was not observed for the hydrogel without AgNPs.

  2. Preparation of collagen/hydroxyapatite/alendronate hybrid hydrogels as potential scaffolds for bone regeneration.

    PubMed

    Ma, Xin; He, Zhiwei; Han, Fengxuan; Zhong, Zhiyuan; Chen, Liang; Li, Bin

    2016-07-01

    Development of biomimetic scaffolds represents a promising direction in bone tissue engineering. In this study, we designed a two-step process to prepare a type of biomimetic hybrid hydrogels that were composed of collagen, hydroxyapatite (HAP) and alendronate (ALN), an anti-osteoporosis drug. First, water-soluble ALN-conjugated HAP (HAP-ALN) containing 4.0wt.% of ALN was synthesized by treating HAP particles with ALN. Hydrogels were then formed from HAP-ALN conjugate and collagen under physiological conditions using genipin (GNP) as the crosslinker. Depending on the ALN/collagen molar ratio and GNP concentration, the gelation time of hydrogels ranged from 5 to 37min. Notably, these hybrid hydrogels exhibited markedly improved mechanical property (storage modulus G'=38-187kPa), higher gel contents, and lower swelling ratios compared to the hydrogels prepared from collagen alone under similar conditions. Moreover, they showed tunable degradation behaviors against collagenase. The collagen/HAP-ALN hybrid hydrogels supported the adhesion and growth of murine MC3T3-E1 osteoblastic cells well. Such tough yet enzymatically degradable hybrid hydrogels hold potential as scaffolds for bone tissue engineering.

  3. Synthetically simple, highly resilient hydrogels.

    PubMed

    Cui, Jun; Lackey, Melissa A; Madkour, Ahmad E; Saffer, Erika M; Griffin, David M; Bhatia, Surita R; Crosby, Alfred J; Tew, Gregory N

    2012-03-12

    Highly resilient synthetic hydrogels were synthesized by using the efficient thiol-norbornene chemistry to cross-link hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polydimethylsiloxane (PDMS) polymer chains. The swelling and mechanical properties of the hydrogels were controlled by the relative amounts of PEG and PDMS. The fracture toughness (G(c)) was increased to 80 J/m(2) as the water content of the hydrogel decreased from 95% to 82%. In addition, the mechanical energy storage efficiency (resilience) was more than 97% at strains up to 300%. This is comparable with one of the most resilient materials known: natural resilin, an elastic protein found in many insects, such as in the tendons of fleas and the wings of dragonflies. The high resilience of these hydrogels can be attributed to the well-defined network structure provided by the versatile chemistry, low cross-link density, and lack of secondary structure in the polymer chains.

  4. Zwitterionic Hydrogel-Biopolymer Assembly towards Biomimetic Superlubricants

    NASA Astrophysics Data System (ADS)

    Seekell, Raymond; Zhu, Elaine

    2014-03-01

    One superlubricant in nature is the synovial fluid (SF), comprising of a high molecular weight polysaccharide, hyaluronic acid (HA), and a globule protein, lubricin. In this bio-inspired materials research, we have explored hydrogel particles to mimic lubricin as a ``ball-bearing'' and control their interaction with the viscoelastic HA matrix. Biocompatible poly(N-[2-(Methacyloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide) (PMSA) hydrogel particles are synthesized to examine the electrostatic induced assembly of PMSA-HA supramolecular complexes in aqueous solutions. Fluorescence microscopy and rheology experiments have characterized the tunable network structure and viscoelastic properties of PMSA-HA aggregates by HA concentration and ionic conditions in aqueous solution. When being grafted to a solid surface, the PMSA-HA composite thin film exhibits superior low biofouling and friction performance, suggesting great promises as artificial superlubricants.

  5. Characterizing the viscoelastic properties of thin hydrogel-based constructs for tissue engineering applications.

    PubMed

    Ahearne, Mark; Yang, Ying; El Haj, Alicia J; Then, Kong Y; Liu, Kuo-Kang

    2005-12-22

    We present a novel indentation method for characterizing the viscoelastic properties of alginate and agarose hydrogel based constructs, which are often used as a model system of soft biological tissues. A sensitive long working distance microscope was used for measuring the time-dependent deformation of the thin circular hydrogel membranes under a constant load. The deformation of the constructs was measured laterally. The elastic modulus as a function of time can be determined by a large deformation theory based on Mooney-Rivlin elasticity. A viscoelastic theory, Zener model, was applied to correlate the time-dependent deformation of the constructs with various gel concentrations, and the creep parameters can therefore be quantitatively estimated. The value of Young's modulus was shown to increase in proportion with gel concentration. This finding is consistent with other publications. Our results also showed the great capability of using the technique to measure gels with incorporated corneal stromal cells. This study demonstrates a novel and convenient technique to measure mechanical properties of hydrogel in a non-destructive, online and real-time fashion. Thus this novel technique can become a valuable tool for soft tissue engineering.

  6. Hydrogel-derived non-precious electrocatalysts for efficient oxygen reduction.

    PubMed

    You, Bo; Yin, Peiqun; Zhang, Junli; He, Daping; Chen, Gaoli; Kang, Fei; Wang, Huiqiao; Deng, Zhaoxiang; Li, Yadong

    2015-07-01

    The development of highly active, cheap and robust oxygen reduction reaction (ORR) electrocatalysts to replace precious metal platinum is extremely urgent and challenging for renewable energy devices. Herein we report a novel, green and especially facile hydrogel strategy to construct N and B co-doped nanocarbon embedded with Co-based nanoparticles as an efficient non-precious ORR catalyst. The agarose hydrogel provides a general host matrix to achieve a homogeneous distribution of key precursory components including cobalt (II) acetate and buffer salts, which, upon freeze-drying and carbonization, produces the highly active ORR catalyst. The gel buffer containing Tris base, boric acid and ethylenediaminetetraacetic acid, commonly adopted for pH and ionic strength control, plays distinctively different roles here. These include a green precursor for N- and B-doping, a salt porogen and a Co(2+) chelating agent, all contributing to the excellent ORR activity. This hydrogel-based process is potentially generalizable for many other catalytic materials.

  7. Hydrogel-derived non-precious electrocatalysts for efficient oxygen reduction

    PubMed Central

    You, Bo; Yin, Peiqun; Zhang, Junli; He, Daping; Chen, Gaoli; Kang, Fei; Wang, Huiqiao; Deng, Zhaoxiang; Li, Yadong

    2015-01-01

    The development of highly active, cheap and robust oxygen reduction reaction (ORR) electrocatalysts to replace precious metal platinum is extremely urgent and challenging for renewable energy devices. Herein we report a novel, green and especially facile hydrogel strategy to construct N and B co-doped nanocarbon embedded with Co-based nanoparticles as an efficient non-precious ORR catalyst. The agarose hydrogel provides a general host matrix to achieve a homogeneous distribution of key precursory components including cobalt (II) acetate and buffer salts, which, upon freeze-drying and carbonization, produces the highly active ORR catalyst. The gel buffer containing Tris base, boric acid and ethylenediaminetetraacetic acid, commonly adopted for pH and ionic strength control, plays distinctively different roles here. These include a green precursor for N- and B-doping, a salt porogen and a Co2+ chelating agent, all contributing to the excellent ORR activity. This hydrogel-based process is potentially generalizable for many other catalytic materials. PMID:26130371

  8. Structural design of a double-layered porous hydrogel for effective mass transport.

    PubMed

    Kim, Hyejeong; Kim, Hyeon Jeong; Huh, Hyung Kyu; Hwang, Hyung Ju; Lee, Sang Joon

    2015-03-01

    Mass transport in porous materials is universal in nature, and its worth attracts great attention in many engineering applications. Plant leaves, which work as natural hydraulic pumps for water uptake, have evolved to have the morphological structure for fast water transport to compensate large water loss by leaf transpiration. In this study, we tried to deduce the advantageous structural features of plant leaves for practical applications. Inspired by the tissue organization of the hydraulic pathways in plant leaves, analogous double-layered porous models were fabricated using agarose hydrogel. Solute transport through the hydrogel models with different thickness ratios of the two layers was experimentally observed. In addition, numerical simulation and theoretical analysis were carried out with varying porosity and thickness ratio to investigate the effect of structural factors on mass transport ability. A simple parametric study was also conducted to examine unveiled relations between structural factors. As a result, the porosity and thickness ratio of the two layers are found to govern the mass transport ability in double-layered porous materials. The hydrogel models with widely dispersed pores at a fixed porosity, i.e., close to a homogeneously porous structure, are mostly turned out to exhibit fast mass transport. The present results would provide a new framework for fundamental design of various porous structures for effective mass transport.

  9. Hydrogel-derived non-precious electrocatalysts for efficient oxygen reduction

    NASA Astrophysics Data System (ADS)

    You, Bo; Yin, Peiqun; Zhang, Junli; He, Daping; Chen, Gaoli; Kang, Fei; Wang, Huiqiao; Deng, Zhaoxiang; Li, Yadong

    2015-07-01

    The development of highly active, cheap and robust oxygen reduction reaction (ORR) electrocatalysts to replace precious metal platinum is extremely urgent and challenging for renewable energy devices. Herein we report a novel, green and especially facile hydrogel strategy to construct N and B co-doped nanocarbon embedded with Co-based nanoparticles as an efficient non-precious ORR catalyst. The agarose hydrogel provides a general host matrix to achieve a homogeneous distribution of key precursory components including cobalt (II) acetate and buffer salts, which, upon freeze-drying and carbonization, produces the highly active ORR catalyst. The gel buffer containing Tris base, boric acid and ethylenediaminetetraacetic acid, commonly adopted for pH and ionic strength control, plays distinctively different roles here. These include a green precursor for N- and B-doping, a salt porogen and a Co2+ chelating agent, all contributing to the excellent ORR activity. This hydrogel-based process is potentially generalizable for many other catalytic materials.

  10. Micropatterning of hydrogels on locally hydrophilized regions on PDMS by stepwise solution dipping and in situ gelation.

    PubMed

    Sugaya, Sari; Kakegawa, Shunta; Fukushima, Shizuka; Yamada, Masumi; Seki, Minoru

    2012-10-02

    This study presents a simple but highly versatile method of fabricating picoliter-volume hydrogel patterns on poly(dimethylsiloxane) (PDMS) substrates. Hydrophilic regions were prepared on hydrophobic PDMS plates by trapping and melting functional polymer particles and performing subsequent reactions with partially oxidized dextran. Small aliquots of a gelation solution were selectively trapped on the hydrophilic areas by a simple dipping process that was utilized to make thin hydrogel patterns by the in situ gelation of a sol solution. Using this process, we successfully formed calcium alginate, collagen I, and chitosan hydrogels with a thickness of several micrometers and shapes that followed the hydrophilized regions. In addition, alginate and collagen gel patterns were used to capture cells with different adhesion properties selectively on or off the hydrogel structures. The presented strategy could be applicable to the preparation of a variety of hydrogels for the development of functional biosensors, bioreactors, and cell cultivation platforms.

  11. A versatile strategy to fabricate hydrogel-silver nanocomposites and investigation of their antimicrobial activity.

    PubMed

    Thomas, V; Yallapu, Murali Mohan; Sreedhar, B; Bajpai, S K

    2007-11-01

    In this study, hydrogel-silver nanocomposites have been synthesized by a unique methodology, which involves formation of silver nanoparticles within swollen poly (acrylamide-co-acrylic acid) hydrogels. The formation of silver nanoparticles was confirmed by transmission electron microscopy (TEM) and surface plasmon resonance (SPR) which was obtained at 406 nm. The TEM of hydrogel-silver nanocomposites showed almost uniform distribution of nanoparticles throughout the gel networks. Most of the particles, as revealed from the particle-size distribution curve, were 24-30 nm in size. The X-ray diffraction pattern also confirmed the face centered cubic (fcc) structure of silver nanoparticles. The nanocomposites demonstrated excellent antibacterial effects on Escherichia coli (E. coli). The antibacterial activity depended on size of the nanocomposites, amount of silver nanoparticles, and amount of monomer acid present within the hydrogel-silver nanocomposites. It was also found that immersion of plain hydrogel in 20 mg/30 ml AgNO(3) solution yielded nanocomparticle-hydrogel composites with optimum bactericidal activity.

  12. High-water-content mouldable polyvinyl alcohol-borax hydrogels reinforced by well-dispersed cellulose nanoparticles: dynamic rheological properties and hydrogel formation mechanism.

    PubMed

    Han, Jingquan; Lei, Tingzhou; Wu, Qinglin

    2014-02-15

    Cellulose nanoparticle (CNP) reinforced polyvinyl alcohol-borax (PB) hydrogels were produced via a facile approach in an aqueous system. The effects of particle size, aspect ratio, crystal structure, and surface charge of CNPs on the rheological properties of the composite hydrogels were investigated. The rheological measurements confirmed the incorporation of well-dispersed CNPs to PB system significantly enhanced the viscoelasticity and stiffness of hydrogels. The obtained free-standing, high elasticity and mouldable hydrogels exhibited self-recovery under continuous step strain and thermo-reversibility under temperature sweep. With the addition of cellulose I nanofibers, a 19-fold increase in the high-frequency plateau of storage modulus was obtained compared with that of the pure PB. CNPs acted as multifunctional crosslinking agents and nanofillers to physically and chemically bridge the 3D network hydrogel. The plausible mechanism for the multi-complexation between CNPs, polyvinyl alcohol and borax was proposed to understand the relationship between the 3D network and hydrogel properties.

  13. Synthesis and characterization of zinc chloride containing poly(acrylic acid) hydrogel by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Park, Jong-Seok; Kuang, Jia; Gwon, Hui-Jeong; Lim, Youn-Mook; Jeong, Sung-In; Shin, Young-Min; Seob Khil, Myung; Nho, Young-Chang

    2013-07-01

    In this study, the characterization of zinc chloride incorporated into a poly(acrylic acid) (PAAc) hydrogel prepared by gamma-ray irradiation was investigated. Zinc chloride powder with different concentrations was dissolved in the PAAc solution, and it was crosslinked with gamma-ray irradiation. The effects of various parameters such as zinc ion concentration and irradiation doses on characteristics of the hydrogel formed were investigated in detail for obtaining an antibacterial wound dressing. In addition, the gel content, pH-sensitive (pH 4 or 7) swelling ratio, and UV-vis absorption spectra of the zinc particles in the hydrogels were characterized. Moreover, antibacterial properties of these new materials against Staphylococcus aureus and Escherichia coli strains were observed on solid growth media. The antibacterial tests indicated that the zinc chloride containing PAAc hydrogels have good antibacterial activity.

  14. Application of carboxymethylcellulose hydrogel based silver nanocomposites on cotton fabrics for antibacterial property.

    PubMed

    Bozaci, Ebru; Akar, Emine; Ozdogan, Esen; Demir, Asli; Altinisik, Aylin; Seki, Yoldas

    2015-12-10

    In this study, fumaric acid (FA) crosslinked carboxymethylcellulose (CMC) hydrogel (CMCF) based silver nanocomposites were coated on cotton fabric for antibacterial property for the first time. The performance of the nanocomposite treated cotton fabric was tested for different mixing times of hydrogel solution, padding times and concentrations of silver. The cotton fabrics treated with CMC hydrogel based silver nanocomposites demonstrated 99.9% reduction for both Staphylococcus aureus (Sa) and Klebsiella pneumonia (Kp). After one cycle washing processes of treated cotton fabric, there is no significant variation observed in antibacterial activity. From SEM and AFM analyses, silver particles in nano-size, homogenously distributed, were observed. The treated samples were also evaluated by tensile strength, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) analysis, fluid absorbency properties, and whiteness index. The treatment of cotton fabric with CMCF hydrogel did not affect the whiteness considerably, but increased the absorbency values of cotton.

  15. Mucin Agarose Gel Electrophoresis: Western Blotting for High-molecular-weight Glycoproteins.

    PubMed

    Ramsey, Kathryn A; Rushton, Zachary L; Ehre, Camille

    2016-06-14

    Mucins, the heavily-glycosylated proteins lining mucosal surfaces, have evolved as a key component of innate defense by protecting the epithelium against invading pathogens. The main role of these macromolecules is to facilitate particle trapping and clearance while promoting lubrication of the mucosa. During protein synthesis, mucins undergo intense O-glycosylation and multimerization, which dramatically increase the mass and size of these molecules. These post-translational modifications are critical for the viscoelastic properties of mucus. As a result of the complex biochemical and biophysical nature of these molecules, working with mucins provides many challenges that cannot be overcome by conventional protein analysis methods. For instance, their high-molecular-weight prevents electrophoretic migration via regular polyacrylamide gels and their sticky nature causes adhesion to experimental tubing. However, investigating the role of mucins in health (e.g., maintaining mucosal integrity) and disease (e.g., hyperconcentration, mucostasis, cancer) has recently gained interest and mucins are being investigated as a therapeutic target. A better understanding of the production and function of mucin macromolecules may lead to novel pharmaceutical approaches, e.g., inhibitors of mucin granule exocytosis and/or mucolytic agents. Therefore, consistent and reliable protocols to investigate mucin biology are critical for scientific advancement. Here, we describe conventional methods to separate mucin macromolecules by electrophoresis using an agarose gel, transfer protein into nitrocellulose membrane, and detect signal with mucin-specific antibodies as well as infrared fluorescent gel reader. These techniques are widely applicable to determine mucin quantitation, multimerization and to test the effects of pharmacological compounds on mucins.

  16. Biologically inspired rosette nanotubes and nanocrystalline hydroxyapatite hydrogel nanocomposites as improved bone substitutes

    NASA Astrophysics Data System (ADS)

    Zhang, Lijie; Rodriguez, Jose; Raez, Jose; Myles, Andrew J.; Fenniri, Hicham; Webster, Thomas J.

    2009-04-01

    Today, bone diseases such as bone fractures, osteoporosis and bone cancer represent a common and significant public health problem. The design of biomimetic bone tissue engineering materials that could restore and improve damaged bone tissues provides exciting opportunities to solve the numerous problems associated with traditional orthopedic implants. Therefore, the objective of this in vitro study was to create a biomimetic orthopedic hydrogel nanocomposite based on the self-assembly properties of helical rosette nanotubes (HRNs), the osteoconductive properties of nanocrystalline hydroxyapatite (HA), and the biocompatible properties of hydrogels (specifically, poly(2-hydroxyethyl methacrylate), pHEMA). HRNs are self-assembled nanomaterials that are formed from synthetic DNA base analogs in water to mimic the helical nanostructure of collagen in bone. In this study, different geometries of nanocrystalline HA were controlled by either hydrothermal or sintering methods. 2 and 10 wt% nanocrystalline HA particles were well dispersed into HRN hydrogels using ultrasonication. The nanocrystalline HA and nanocrystalline HA/HRN hydrogels were characterized by x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical testing studies revealed that the well dispersed nanocrystalline HA in HRN hydrogels possessed improved mechanical properties compared to hydrogel controls. In addition, the results of this study provided the first evidence that the combination of either 2 or 10 wt% nanocrystalline HA and 0.01 mg ml-1 HRNs in hydrogels greatly increased osteoblast (bone-forming cell) adhesion up to 236% compared to hydrogel controls. Moreover, this study showed that HRNs stimulated HA nucleation and mineralization along their main axis in a way that is very reminiscent of the HA/collagen assembly pattern in natural bone. In summary, the presently observed excellent properties of the biomimetic nanocrystalline HA/HRN hydrogel composites

  17. Biologically inspired rosette nanotubes and nanocrystalline hydroxyapatite hydrogel nanocomposites as improved bone substitutes.

    PubMed

    Zhang, Lijie; Rodriguez, Jose; Raez, Jose; Myles, Andrew J; Fenniri, Hicham; Webster, Thomas J

    2009-04-29

    Today, bone diseases such as bone fractures, osteoporosis and bone cancer represent a common and significant public health problem. The design of biomimetic bone tissue engineering materials that could restore and improve damaged bone tissues provides exciting opportunities to solve the numerous problems associated with traditional orthopedic implants. Therefore, the objective of this in vitro study was to create a biomimetic orthopedic hydrogel nanocomposite based on the self-assembly properties of helical rosette nanotubes (HRNs), the osteoconductive properties of nanocrystalline hydroxyapatite (HA), and the biocompatible properties of hydrogels (specifically, poly(2-hydroxyethyl methacrylate), pHEMA). HRNs are self-assembled nanomaterials that are formed from synthetic DNA base analogs in water to mimic the helical nanostructure of collagen in bone. In this study, different geometries of nanocrystalline HA were controlled by either hydrothermal or sintering methods. 2 and 10 wt% nanocrystalline HA particles were well dispersed into HRN hydrogels using ultrasonication. The nanocrystalline HA and nanocrystalline HA/HRN hydrogels were characterized by x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical testing studies revealed that the well dispersed nanocrystalline HA in HRN hydrogels possessed improved mechanical properties compared to hydrogel controls. In addition, the results of this study provided the first evidence that the combination of either 2 or 10 wt% nanocrystalline HA and 0.01 mg ml(-1) HRNs in hydrogels greatly increased osteoblast (bone-forming cell) adhesion up to 236% compared to hydrogel controls. Moreover, this study showed that HRNs stimulated HA nucleation and mineralization along their main axis in a way that is very reminiscent of the HA/collagen assembly pattern in natural bone. In summary, the presently observed excellent properties of the biomimetic nanocrystalline HA/HRN hydrogel composites

  18. Solvent-impregnated agarose gel liquid phase microextraction of polycyclic aromatic hydrocarbons in water.

    PubMed

    Loh, Saw Hong; Sanagi, Mohd Marsin; Wan Ibrahim, Wan Aini; Hasan, Mohamed Noor

    2013-08-09

    A new microextraction procedure termed agarose gel liquid phase microextraction (AG-LPME) combined with gas chromatography-mass spectrometry (GC-MS) was developed for the determination of selected polycyclic aromatic hydrocarbons (PAHs) in water. The technique utilized an agarose gel disc impregnated with the acceptor phase (1-octanol). The extraction procedure was performed by allowing the solvent-impregnated agarose gel disc to tumble freely in the stirred sample solution. After extraction, the agarose gel disc was removed and subjected to centrifugation to disrupt its framework and to release the impregnated solvent, which was subsequently withdrawn and injected into the GC-MS for analysis. Under optimized extraction conditions, the new method offered high enrichment factors (89-177), trace level LODs (9-14ngL(-1)) and efficient extraction with good relative recoveries in the range of 93.3-108.2% for spiked drinking water samples. AG-LPME did not exhibit any problems related to solvent dissolution, and it provided high extraction efficiencies that were comparable to those of hollow fiber liquid phase microextraction (HF-LPME) and significantly higher than those of agarose film liquid phase microextraction (AF-LPME). This technique employed a microextraction format and utilized an environmentally compatible solvent holder that supported the green chemistry concept.

  19. Single-molecule measurements of trapped and migrating circular DNA during electrophoresis in agarose gels.

    PubMed

    Cole, Kenneth D; Gaigalas, Adolfas; Akerman, Björn

    2006-11-01

    The effect of agarose gel concentration and field strength on the electrophoretic trapping of open (relaxed) circular DNA was investigated using microscopic measurements of individual molecules stained with a fluorescent dye. Three open circles with sizes of 52.5, 115, and 220 kbp were trapped by the electric field (6 V/cm) and found to be predominately fixed and stretched at a single point in the gel. The length of the stretched circles did not significantly change with agarose concentration of the gels (mass fractions of 0.0025, 0.01, and 0.02). The relaxation kinetics of the trapped circles was also measured in the gels. The relaxation of the large open circles was found to be a slow process, taking several seconds. The velocity and average length of the 52.5 kbp open circles and 48.5 kbp linear DNA were measured during electrophoresis in the agarose gels. The velocity increased when the agarose concentrations were lowered, but the average length of the open-circle DNA (during electrophoresis) did not significantly change with agarose gel concentrations. The circles move through the gels by cycles of stretching and relaxation during electrophoresis. Linear dichroism was also used to investigate the trapping and alignment of the 52.5 kbp open circles. The results in this study provide information that can be used to improve electrophoretic separations of circular DNA, an important form of genetic material and commonly used to clone DNA.

  20. Rapid agarose gel electrophoretic mobility shift assay for quantitating protein: RNA interactions.

    PubMed

    Ream, Jennifer A; Lewis, L Kevin; Lewis, Karen A

    2016-10-15

    Interactions between proteins and nucleic acids are frequently analyzed using electrophoretic mobility shift assays (EMSAs). This technique separates bound protein:nucleic acid complexes from free nucleic acids by electrophoresis, most commonly using polyacrylamide gels. The current study utilizes recent advances in agarose gel electrophoresis technology to develop a new EMSA protocol that is simpler and faster than traditional polyacrylamide methods. Agarose gels are normally run at low voltages (∼10 V/cm) to minimize heating and gel artifacts. In this study we demonstrate that EMSAs performed using agarose gels can be run at high voltages (≥20 V/cm) with 0.5 × TB (Tris-borate) buffer, allowing for short run times while simultaneously yielding high band resolution. Several parameters affecting band and image quality were optimized for the procedure, including gel thickness, agarose percentage, and applied voltage. Association of the siRNA-binding protein p19 with its target RNA was investigated using the new system. The agarose gel and conventional polyacrylamide gel methods generated similar apparent binding constants in side-by-side experiments. A particular advantage of the new approach described here is that the short run times (5-10 min) reduce opportunities for dissociation of bound complexes, an important concern in non-equilibrium nucleic acid binding experiments.

  1. Agarose-based microfluidic device for point-of-care concentration and detection of pathogen.

    PubMed

    Li, Yiwei; Yan, Xinghua; Feng, Xiaojun; Wang, Jie; Du, Wei; Wang, Yachao; Chen, Peng; Xiong, Liang; Liu, Bi-Feng

    2014-11-04

    Preconcentration of pathogens from patient samples represents a great challenge in point-of-care (POC) diagnostics. Here, a low-cost, rapid, and portable agarose-based microfluidic device was developed to concentrate biological fluid from micro- to picoliter volume. The microfluidic concentrator consisted of a glass slide simply covered by an agarose layer with a binary tree-shaped microchannel, in which pathogens could be concentrated at the end of the microchannel due to the capillary effect and the strong water permeability of the agarose gel. The fluorescent Escherichia coli strain OP50 was used to demonstrate the capacity of the agarose-based device. Results showed that 90% recovery efficiency could be achieved with a million-fold volume reduction from 400 μL to 400 pL. For concentration of 1 × 10(3) cells mL(-1) bacteria, approximately ten million-fold enrichment in cell density was realized with volume reduction from 100 μL to 1.6 pL. Urine and blood plasma samples were further tested to validate the developed method. In conjugation with fluorescence immunoassay, we successfully applied the method to the concentration and detection of infectious Staphylococcus aureus in clinics. The agarose-based microfluidic concentrator provided an efficient approach for POC detection of pathogens.

  2. Direct noninvasive measurement and numerical modeling of depth-dependent strains in layered agarose constructs.

    PubMed

    Griebel, A J; Khoshgoftar, M; Novak, T; van Donkelaar, C C; Neu, C P

    2014-06-27

    Biomechanical factors play an important role in the growth, regulation, and maintenance of engineered biomaterials and tissues. While physical factors (e.g. applied mechanical strain) can accelerate regeneration, and knowledge of tissue properties often guide the design of custom materials with tailored functionality, the distribution of mechanical quantities (e.g. strain) throughout native and repair tissues is largely unknown. Here, we directly quantify distributions of strain using noninvasive magnetic resonance imaging (MRI) throughout layered agarose constructs, a model system for articular cartilage regeneration. Bulk mechanical testing, giving both instantaneous and equilibrium moduli, was incapable of differentiating between the layered constructs with defined amounts of 2% and 4% agarose. In contrast, MRI revealed complex distributions of strain, with strain transfer to softer (2%) agarose regions, resulting in amplified magnitudes. Comparative studies using finite element simulations and mixture (biphasic) theory confirmed strain distributions in the layered agarose. The results indicate that strain transfer to soft regions is possible in vivo as the biomaterial and tissue changes during regeneration and maturity. It is also possible to modulate locally the strain field that is applied to construct-embedded cells (e.g. chondrocytes) using stratified agarose constructs.

  3. Preparation of monodisperse and size-controlled poly(ethylene glycol) hydrogel nanoparticles using liposome templates.

    PubMed

    An, Se Yong; Bui, Minh-Phuong Ngoc; Nam, Yun Jung; Han, Kwi Nam; Li, Cheng Ai; Choo, Jaebum; Lee, Eun Kyu; Katoh, Shigeo; Kumada, Yoichi; Seong, Gi Hun

    2009-03-01

    Liposomes were used as templates to prepare size-controlled and monodisperse poly(ethylene glycol) (PEG) hydrogel nanoparticles. The procedure for the preparation of PEG nanoparticles using liposomes consists of encapsulation of photopolymerizable PEG hydrogel solution into the cavity of the liposomes, extrusion through a membrane with a specific pore size, and photopolymerization of the contents inside the liposomes by UV irradiation. The size distributions of the prepared particles were 1.32+/-0.16 microm (12%), 450+/-62 nm (14%), and 94+/-12 nm (13%) after extrusion through membrane filters with pore sizes of 1 microm, 400 nm, and 100 nm, respectively. With this approach, it is also possible to modify the surface of the hydrogel nanoparticles with various functional groups in a one-step procedure. To functionalize the surface of a PEG nanoparticle, methoxy poly(ethylene glycol)-aldehyde was added as copolymer to the hydrogel-forming components and aldehyde-functionalized PEG nanoparticles could be obtained easily by UV-induced photopolymerization, following conjugation with poly-L-lysine-FITC through amine-aldehyde coupling. The prepared PEG particles showed strong fluorescence from FITC on the edge of the particles using confocal microscopy. The immobilization of biomaterials such as enzymes in hydrogel particles could be performed with loading beta-galactosidases during the hydration step for liposome preparation without additional procedures. The resorufin produced by applying resorufin beta-D-galactopyranoside as the substrate showed the fluorescence under the confocal microscopy.

  4. Cellulose gel dispersion: From pure hydrogel suspensions to encapsulated oil-in-water emulsions.

    PubMed

    Napso, Sofia; Rein, Dmitry M; Khalfin, Rafail; Kleinerman, Olga; Cohen, Yachin

    2016-01-01

    Cellulose hydrogel particles were fabricated from molecularly-dissolved cellulose/IL solutions. The characteristics of the formed hydrogels (cellulose content, particles' size and porosity) were determined as a function of cellulose concentration in the precursor solutions. There is a significant change in the hydrogel structure when the initial cellulose solution concentration increases above about 7-9%wt. These changes include increase of the cellulose content in the hydrogel, and decrease in its pore size. The finest cellulose particle dispersions can be obtained using low concentration cellulose/IL solutions (cellulose concentration in dispersion less than 2%wt.) or hydrogels (concentration less than 1%wt.) in a dispersing medium consisting of IL with no more than 20%wt. water. Stable paraffin oil-in-water emulsions are achieved by mixing oil and water with cellulose/IL solutions. The optimal conditions for obtaining the finest particles (about 20μm in diameter) are attained using cellulose solutions of concentration between 0.7 and 4%wt. at temperature of 70°C and oil/cellulose mass ratios between 1 and 1.5.

  5. A Photonic Crystal Protein Hydrogel Sensor for Candida albicans.

    PubMed

    Cai, Zhongyu; Kwak, Daniel H; Punihaole, David; Hong, Zhenmin; Velankar, Sachin S; Liu, Xinyu; Asher, Sanford A

    2015-10-26

    We report two-dimensional (2D) photonic crystal (PC) sensing materials that selectively detect Candida albicans (C. albicans). These sensors utilize Concanavalin A (Con A) protein hydrogels with a 2D PC embedded on the Con A protein hydrogel surface, that multivalently and selectively bind to mannan on the C. albicans cell surface to form crosslinks. The resulting crosslinks shrink the Con A protein hydrogel, reduce the 2D PC particle spacing, and blue-shift the light diffracted from the PC. The diffraction shifts can be visually monitored, measured with a spectrometer, or determined from the Debye diffraction ring diameter. Our unoptimized hydrogel sensor has a detection limit of around 32 CFU/mL for C. albicans. This sensor distinguishes between C. albicans and those microbes devoid of cell-surface mannan such as the gram-negative bacterium E. coli. This sensor provides a proof-of-concept for utilizing recognition between lectins and microbial cell surface carbohydrates to detect microorganisms in aqueous environments.

  6. Supramolecular hydrogels as drug delivery systems.

    PubMed

    Saboktakin, Mohammad Reza; Tabatabaei, Roya Mahdavi

    2015-04-01

    Drug delivery from a hydrogel carrier implanted under the kidney capsule is an innovative way to induce kidney tissue regeneration and/or prevent kidney inflammation or fibrosis. We report here on the development of supramolecular hydrogels for this application. Chain-extended hydrogelators containing hydrogen bonding units in the main chain, and bifunctional hydrogelators end-functionalized with hydrogen bonding moieties, were made. The influence of these hydrogels on the renal cortex when implanted under the kidney capsule was studied. The overall tissue response to these hydrogels was found to be mild, and minimal damage to the cortex was observed, using the infiltration of macrophages, formation of myofibroblasts, and the deposition of collagen III as relevant read-out parameters. Differences in tissue response to these hydrogels could be related to the different physico-chemical properties of the three hydrogels.

  7. Patterns in swelling hydrogels

    NASA Astrophysics Data System (ADS)

    MacMinn, Chris; Bertrand, Thibault; Peixinho, Jorge; Mukhopadhyay, Shomeek

    2016-11-01

    Swelling is a process in which a porous material spontaneously grows by absorbing additional pore fluid. Polymeric hydrogels are highly deformable materials that can experience very large volume changes during swelling. This allows a small amount of dry gel to absorb a large amount of fluid, making gels extremely useful in applications from moisture control to drug delivery. However, a well-known consequence of these extreme volume changes is the emergence of a striking morphological instability. We study the transient mechanics of this instability here by combining a theoretical model with a series of simple experiments, focusing on the extent to which this instability can be controlled by manipulating the rate of swelling.

  8. Two methods that facilitate autoradiography of small /sup 32/P-labeled DNA fragments following electrophoresis in agarose gels

    SciTech Connect

    Cockerill, P.N.

    1988-02-01

    Two methods which permit detection by autoradiography of small /sup 32/P-labeled DNA fragments resolved by agarose gel electrophoresis are described. Agarose gel electrophoresis poses problems for autoradiography as (i) the gels are normally too thick to allow autoradiography without being dried first, and (ii) fragments of DNA of 1000 bp or less in length are readily lost during drying. In this study DNA fragments as small as 121 bp have been retained in agarose gels upon drying. This has been achieved by either (i) first fixing the DNA with the cationic detergent cetyltrimethylammonium bromide, or (ii) drying the agarose gels onto Zeta-Probe charge-modified membranes.

  9. Preparation of DNA and protein micro arrays on glass slides coated with an agarose film

    PubMed Central

    Afanassiev, Victor; Hanemann, Vera; Wölfl, Stefan

    2000-01-01

    A thin layered agarose film on microscope slides provides a versatile support for the preparation of arrayed molecular libraries. An activation step leading to the formation of aldehyde groups in the agarose creates reactive sites that allow covalent immobilization of molecules containing amino groups. Arrays of oligonucleotides and PCR products were prepared by tip printing. After hybridization with complementary fluorescence labeled nucleic acid probes strong fluorescence signals of sequence-specific binding to the immobilized probes were detected. The intensity of the fluorescence signals was proportional to the relative amount of immobilized oligonucleotides and to the concentration of the fluorescence labeled probe. We also used the agarose film-coated slides for the preparation of protein arrays. In combination with specific fluorescence labeled antibodies these protein arrays can be used for fluorescence linked immune assays. With this approach different protein tests can be performed in parallel in a single reaction with minimal amounts of the binding reagents. PMID:10871389

  10. Maintenance of biological activity of pertussis toxin radioiodinated while bound to fetuin-agarose

    SciTech Connect

    Armstrong, G.D.; Peppler, M.S.

    1987-05-01

    We developed a method to produce radioiodinated pertussis toxin (PT) which was active in the goose erythrocyte agglutination and CHO cell assay systems. The procedure used fetuin coupled to agarose to prevent inactivation of the toxin during the iodination reaction. Analysis of the labeled PT by affinity chromatography on fetuin-agarose and wheat germ agglutinin-agarose and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that there were minimal amounts of labeled fetuin or other contaminants in the labeled PT preparations. All five of the subunits of the toxin appeared to be labeled by the procedure. The labeling method will facilitate further investigations into the nature of the interaction and activity of PT in host tissues.

  11. Quantitative determination of glycine in aqueous solution using glutamate dehydrogenase-immobilized glyoxal agarose beads.

    PubMed

    Keskin, Semra Yilmazer; Keskin, Can Serkan

    2014-01-01

    In this study, an enzymatic procedure for the determination of glycine (Gly) was developed by using a column containing immobilized glutamate dehydrogenase (GDH) on glyoxal agarose beads. Ammonia is produced from the enzymatic reactions between Gly and GDH with NAD(+) in phosphate buffer medium. The indophenol blue method was used for ammonia detection based on the spectrophotometric measurements of blue-colored product absorbing at 640 nm. The calibration graph is linear in the range of 0.1-10 mM of Gly concentrations. The effect of pH, temperature, and time interval was studied to find column stability, and also the interference effects of other amino acids was investigated. The interaction between GDH and glyoxal agarose beads was analyzed by Fourier transform infrared (FTIR) spectroscopy. The morphology of the immobilized and non-immobilized agarose beads were characterized by atomic force microscopy (AFM).

  12. Hydrogels with covalent and noncovalent crosslinks

    NASA Technical Reports Server (NTRS)

    Kilck, Kristi L. (Inventor); Yamaguchi, Nori (Inventor)

    2013-01-01

    A method for targeted delivery of therapeutic compounds from hydrogels is presented. The method involves administering to a cell a hydrogel in which a therapeutic compound is noncovalently bound to heparin. The hydrogel may contain covalent and non-covalent crosslinks.

  13. Confined Flocculation of Ionic Pollutants by Poly(L-dopa)-Based Polyelectrolyte Complexes in Hydrogel Beads for Three-Dimensional, Quantitative, Efficient Water Decontamination.

    PubMed

    Yu, Li; Liu, Xiaokong; Yuan, Weichang; Brown, Lauren Joan; Wang, Dayang

    2015-06-16

    The development of simple and recyclable adsorbents with high adsorption capacity is a technical imperative for water treatment. In this work, we have successfully developed new adsorbents for the removal of ionic pollutants from water via encapsulation of polyelectrolyte complexes (PECs) made from positively charged poly(allylamine hydrochloride) (PAH) and negatively charged poly(l-3,4-dihydroxyphenylalanine) (PDopa), obtained via the self-polymerization of l-3,4-dihydroxyphenylalanine (l-Dopa). Given the outstanding mass transport through the hydrogel host matrixes, the PDopa-PAH PEC guests loaded inside can effectively and efficiently remove various ionic pollutants, including heavy metal ions and ionic organic dyes, from water. The adsorption efficiency of the PDopa-PAH PECs can be quantitatively correlated to and tailored by the PDopa-to-PAH molar ratio. Because PDopa embodies one catechol group, one carboxyl group, and one amino group in each repeating unit, the resulting PDopa-PAH PECs exhibit the largest capacity of adsorption of heavy metal ions compared to available adsorbents. Because both PDopa and PAH are pH-sensitive, the PDopa-PAH PEC-loaded agarose hydrogel beads can be easily and completely recovered after the adsorption of ionic pollutants by adjusting the pH of the surrounding media. The present strategy is similar to the conventional process of using PECs to flocculate ionic pollutants from water, while in our system flocculation is confined to the agarose hydrogel beads, thus allowing easy separation of the resulting adsorbents from water.

  14. Fabrication of superporous agarose beads for protein adsorption: effect of CaCO3 granules content.

    PubMed

    Du, Kai-Feng; Bai, Shu; Dong, Xiao-Yan; Sun, Yan

    2010-09-10

    Agarose gels were fabricated by water-in-oil emulsification with the addition of CaCO(3) granules at 8-16 wt%. Thus agarose beads of different superporosities were produced after dissolving the solid porogen. The superporous agarose (SA) and homogeneous agarose gels were double cross-linked and modified with diethylaminoethyl chloride to produce anion exchangers. We have proposed to use a superporous replica (porous titania microspheres) to examine the superporous structure and pore size distribution of the soft gel. The replica was prepared with the agarose gel entrapping CaCO(3) granules by a sol-gel-templating method. It was found that the superpores created by CaCO(3) granules were uniformly distributed and ranged from 0.95 microm to 1.33 microm. The physical properties of the gels were significantly affected by the porogen content. Importantly, by increasing the solid porogen to 12 wt%, the bed permeability and effective porosity increased about 48% and 33%, respectively. Further increase in the porogen to 16 wt% led to a decrease of the mechanical strength. With increasing superpores in the beads, the dynamic adsorption capacity of the packed columns increased obviously at 305-916 cm/h. Besides, the column efficiency changed less with increasing flow velocity up to 1200 cm/h. It was concluded that the use of 12 wt% CaCO(3) granules in agarose solution was beneficial for the fabrication of the SA gel with good mechanical stability and promising performance for protein chromatography.

  15. Enzymatic liquefaction of agarose above the sol-gel transition temperature using a thermostable endo-type β-agarase, Aga16B.

    PubMed

    Kim, Jung Hyun; Yun, Eun Ju; Seo, Nari; Yu, Sora; Kim, Dong Hyun; Cho, Kyung Mun; An, Hyun Joo; Kim, Jae-Han; Choi, In-Geol; Kim, Kyoung Heon

    2017-02-01

    The main carbohydrate of red macroalgae is agarose, a heterogeneous polysaccharide composed of D-galactose and 3,6-anhydro-L-galactose. When saccharifying agarose by enzymes, the unique physical properties of agarose, namely the sol-gel transition and the near-insolubility of agarose in water, limit the accessibility of agarose to the enzymes. Due to the lower accessibility of agarose to enzymes in the gel state than to the sol state, it is important to prevent the sol-gel transition by performing the enzymatic liquefaction of agarose at a temperature higher than the sol-gel transition temperature of agarose. In this study, a thermostable endo-type β-agarase, Aga16B, originating from Saccharophagus degradans 2-40(T), was characterized and introduced in the liquefaction process. Aga16B was thermostable up to 50 °C and depolymerized agarose mainly into neoagarooligosaccharides with degrees of polymerization 4 and 6. Aga16B was applied to enzymatic liquefaction of agarose at 45 °C, which was above the sol-gel transition temperature of 1 % (w/v) agarose (∼35 °C) when cooling agarose. This is the first systematic demonstration of enzymatic liquefaction of agarose, enabled by determining the sol-gel temperature of agarose under specific conditions and by characterizing the thermostability of an endo-type β-agarase.

  16. Encoding physico-chemical cues in synthetic hydrogels by triple helix assembly of collagen mimetic peptides

    NASA Astrophysics Data System (ADS)

    Stahl, Patrick

    The ECM is a complex natural system evolved to promote proliferation and differentiation of cells during tissue development. In order to create synthetic biomaterials for studying cell-scaffold interactions and ultimately for engineering tissues, scientists strive to recapitulate many characteristics of ECM by developing hydrogels that contain mechanical cues and biochemical signals such as adhesion moieties and cell growth factors. While synthetic hydrogels bypass limitations of naturally-derived materials (e.g. transfer of pathogens), nature provides inspiration to enhance the functionality of synthetic hydrogels through biomimetic approaches. The collagen triple helix is the basis for the supramolecular structure of collagen in the ECM, and its adaptation in collagen mimetic peptides (CMPs) has provided hybridization mechanisms that can be employed in the formation and functionalization of synthetic hydrogels. The aim of this dissertation is to develop novel poly(ethylene glycol) (PEG)-based hydrogels that employ CMP triple helix assembly as a non-covalent yet target-specific tool to encode physical and chemical cues into the hydrogel with spatial control. We demonstrate that multi-arm PEG functionalized with CMPs form hydrogels supported by physical crosslinks mediated by CMP triple helix. Particle tracking microrheology shows that these physical crosslinks are sensitive to temperature as well as addition of exogenous CMPs that can disrupt crosslinks by competing for triple helix formation. This physical crosslink disruption enables the modulation of bulk hydrogel elasticity and the introduction of local stiffness gradients in PEG-CMP hydrogels. We also present photopolymerized PEG diacrylate (PEGDA) hydrogels displaying CMPs that can be further conjugated to CMPs with bioactive moieties via triple helix hybridization. Encoding these hydrogels with cell-adhesive CMPs induces cell spreading and proliferation. We further demonstrate generation of gradients and

  17. Ag-nanoparticle fractionation by low melting point agarose gel electrophoresis

    NASA Astrophysics Data System (ADS)

    Guarrotxena, Nekane; Braun, Gary

    2012-10-01

    The separation of surface-enhanced raman scattering (SERS)-active Ag-multi-nanoparticle (NP) assemblies by low melting point agarose gel electrophoresis was accomplished here by controlling surface charge using NP capping agents, and the pore size of agarose gel matrix. Detailed transmission electron microscopy analysis of excised gel fractions showed dimers and small clusters to have the greatest SERS activity and a mobility in between the monomers and large aggregates. This strategy enables one to: (1) stabilize small multispherical Ag clusters against further aggregation during purification; (2) fractionate and recover spherical assemblies by nuclearity; and (3) analyze SERS-enhancements for each fraction to optimize purification conditions.

  18. A simple, efficient, and economical method for recovering DNA from agarose gel.

    PubMed

    Fan, Chang-Fa; Mei, Xing-Guo

    2005-01-01

    A simple method of recovering DNA from agarose gel that is fast, inexpensive, and friendly both to operators and environment is described. Two rows of wells are made in an agarose gel, and a DNA sample is loaded into the well nearest to the negative pole for separation by electrophoresis. Recovery is accomplished by pipetting the DNA-containing TAE buffer from the well near the positive pole after target DNA fragments have migrated into the well. A recovery rate of up to 94 +/- 2.3% was observed with this method.

  19. Analysis of supercoiled DNA by agarose gel electrophoresis using low-conducting sodium threonine medium.

    PubMed

    Ishido, Tomomi; Ishikawa, Mitsuru; Hirano, Ken

    2010-05-01

    We describe a new low-ionic-strength sodium threonine (STh) medium with the advantage of avoiding relative DNA band migration changes following electrophoresis of supercoiled DNA in agarose gel when substituted for the standard conductive medium of TBE (Tris-boric acid-ethylenediaminetetraacetic acid [EDTA]) or TAE (Tris-acetic acid-EDTA) or the low-ionic-strength sodium boric acid medium. Low-ionic-strength STh medium provided better resolution, less heat generation, and prevention of relative migration order changes among linear, covalently closed circular-, and open circular-formed DNA in the range of 2-10 kilobase pairs in 1% agarose gel electrophoresis.

  20. Novel Hydrogels from Renewable Resources

    NASA Astrophysics Data System (ADS)

    Karaaslan, Muzafer Ahmet

    2011-12-01

    The cell wall of most plant biomass from forest and agricultural resources consists of three major polymers, cellulose, hemicellulose and lignin. Of these, hemicelluloses have gained increasing attention as sustainable raw materials. In the first part of this study, novel pH-sensitive semi-IPN hydrogels based on hemicelluloses and chitosan were prepared using glutaraldehyde as the crosslinking agent. The hemicellulose isolated from aspen was analyzed for sugar content by HPLC, and its molecular weight distribution was determined by high performance size exclusion chromatography. Results revealed that hemicellulose had a broad molecular weight distribution with a fair amount of polymeric units, together with xylose, arabinose and glucose. The effect of hemicellulose content on mechanical properties and swelling behavior of hydrogels were investigated. The semi-IPNs hydrogel structure was confirmed by FT-IR, X-ray study and ninhydrin assay method. X-ray analysis showed that higher hemicellulose contents yielded higher crystallinity. Mechanical properties were mainly dependent on the crosslink density and average molecular weight between crosslinks. Swelling ratios increased with increasing hemicellulose content and were high at low pH values due to repulsion between similarly charged groups. In vitro release study of a model drug showed that these semi-IPN hydrogels could be used for controlled drug delivery into gastric fluid. The aim of the second part of this study was to control the crosslink density and the mechanical properties of hemicellulose/chitosan semi-IPN hydrogels by changing the crosslinking sequence. It has been hypothesized that by performing the crosslinking step before introducing hemicellulose, covalent crosslinking of chitosan would not be hindered and therefore more and/or shorter crosslinks could be formed. Furthermore, additional secondary interactions and crystalline domains introduced through hemicellulose could be favorable in terms of

  1. A photonic crystal hydrogel suspension array for the capture of blood cells from whole blood

    NASA Astrophysics Data System (ADS)

    Zhang, Bin; Cai, Yunlang; Shang, Luoran; Wang, Huan; Cheng, Yao; Rong, Fei; Gu, Zhongze; Zhao, Yuanjin

    2016-02-01

    Diagnosing hematological disorders based on the separation and detection of cells in the patient's blood is a significant challenge. We have developed a novel barcode particle-based suspension array that can simultaneously capture and detect multiple types of blood cells. The barcode particles are polyacrylamide (PAAm) hydrogel inverse opal microcarriers with characteristic reflection peak codes that remain stable during cell capture on their surfaces. The hydrophilic PAAm hydrogel scaffolds of the barcode particles can entrap various plasma proteins to capture different cells in the blood, with little damage to captured cells.Diagnosing hematological disorders based on the separation and detection of cells in the patient's blood is a significant challenge. We have developed a novel barcode particle-based suspension array that can simultaneously capture and detect multiple types of blood cells. The barcode particles are polyacrylamide (PAAm) hydrogel inverse opal microcarriers with characteristic reflection peak codes that remain stable during cell capture on their surfaces. The hydrophilic PAAm hydrogel scaffolds of the barcode particles can entrap various plasma proteins to capture different cells in the blood, with little damage to captured cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06368j

  2. Magnetic hydrogel with high coercivity

    SciTech Connect

    Sözeri, H.; Alveroğlu, E.; Kurtan, U.; Şenel, M.; Baykal, A.

    2013-08-01

    Highlights: • Polyacrylamide (PAAm) hydrogels containing magnetic BaFe{sub 12}O{sub 19} nanoparticles have been prepared. • Magnetization measurements reveal that hydrogels have hard magnetic properties with high coercivity. • Magnetic nanoparticles makes the gel more homogeneous and do not diffuse out of the gel during water intake. • These gels are useful in applications as wastewater treatment once gels are magnetized before its usage. - Abstract: This study investigates the synthesis and characterization of polyacrylamide (PAAm) hydrogels containing magnetic BaFe{sub 12}O{sub 19} nanoparticles. Structural, electrical, and magnetic characterization of the gels have been performed with X-ray powder diffractometry, scanning electron microscopy, DC conductivity, magnetization and fluorescence spectroscopy techniques. The preparation and characterization of polyacrylamide (PAAm) hydrogels that contain 5 and 10 mg BaFe{sub 12}O{sub 19} (16 and 21 nm diameter) nanoparticles are described herein. It is seen from the fluorescence spectra that, nanoparticles surrounded to pyranine molecules so that some of pyranine molecules could not bound to the polymer strands. Electrical measurements show that presence of nanoparticles make the gel more homogeneous. Magnetization measurements reveal that hydrogels have hard magnetic properties with quite high coercivity of 4.2 kOe, which does not change with swelling. This feature makes these gels useful in applications as wastewater treatment if they are magnetized before use.

  3. Microfluidics assisted generation of innovative polysaccharide hydrogel microparticles.

    PubMed

    Marquis, M; Davy, J; Cathala, B; Fang, A; Renard, D

    2015-02-13

    Capillary flow-based approach such as microfluidic devices offer a number of advantages over conventional flow control technology because they ensure highly versatile geometry and can be used to produce monodisperse spherical and non-spherical polymeric microparticles. Based on the principle of a flow-focusing device to emulsify the coflow of aqueous solutions in an organic phase, we were able to produce the following innovative polysaccharide hydrogel microparticles: - Janus hydrogel microparticles made of pectin–pectin (homo Janus) and pectin–alginate (hetero Janus) were produced. The efficiency of separation of the two hemispheres was investigated by confocal scanning laser microscopy (CSLM) of previously labelled biopolymers. The Janus structure was confirmed by subjecting each microparticle hemisphere to specific enzymatic degradation. As a proof of concept, free BSA or BSA grafted with dextran, were encapsulated in each hemisphere of the hetero Janus hydrogel microparticles. While BSA, free or grafted with dextran, was always confined in the alginate hemisphere, a fraction of BSA diffused from the pectin to the alginate hemisphere. Methoxy groups along the pectin chain will be responsible of the decrease of the number of attractive electrostatic interactions occurring between amino groups of BSA and carboxylic groups of pectin. - Pectin hydrogel microparticles of complex shapes were successfully produced by combining on-chip the phenomenon of gelation and water diffusion induced self-assembly, using dimethyl carbonate as continuous phase, or by deformation of the pre-gelled droplets off-chip at a fluid–fluid interface. Sphere, oblate ellipsoid, torus or mushroom-type morphologies were thus obtained. Moreover, it was established that after crossing the interface during their collect, mushroom-type microparticles did not migrate in the calcium or DMC phase but stayed at the liquid–liquid interface. These new and original hydrogel microparticles will

  4. Reductively-responsive siRNA-conjugated hydrogel nanoparticles for gene silencing

    PubMed Central

    Dunn, Stuart S.; Tian, Shaomin; Blake, Steven; Wang, Jin; Galloway, Ashley L.; Murphy, Andrew; Pohlhaus, Patrick D.; Rolland, Jason P.; Napier, Mary E.; DeSimone, Joseph M.

    2012-01-01

    A critical need still remains for effective delivery of RNA interference (RNAi) therapeutics to target tissues and cells. Self-assembled lipid- and polymer-based systems have been most extensively explored for transfection with small interfering RNA (siRNA) in liver and cancer therapies. Safety and compatibility of materials implemented in delivery systems must be ensured to maximize therapeutic indices. Hydrogel nanoparticles of defined dimensions and compositions, prepared via a particle molding process that is a unique off-shoot of soft lithography known as PRINT (Particle Replication in Non-wetting Templates), were explored in these studies as delivery vectors. Initially, siRNA was encapsulated in particles through electrostatic association and physical entrapment. Dose-dependent gene silencing was elicited by PEGylated hydrogels at low siRNA doses without cytotoxicity. To prevent disassociation of cargo from particles after systemic administration or during post-fabrication processing for surface functionalization, a polymerizable siRNA pro-drug conjugate with a degradable, disulfide linkage was prepared. Triggered release of siRNA from the prodrug hydrogels was observed under a reducing environment while cargo retention and integrity were maintained under physiological conditions. Gene silencing efficiency and cytocompatibility were optimized by screening the amine content of the particles. When appropriate control siRNA cargos were loaded into hydrogels, gene knockdown was only encountered for hydrogels containing releasable, target-specific siRNAs, accompanied by minimal cell death. Further investigation into shape, size, and surface decoration of siRNA-conjugated hydrogels should enable efficacious targeted in vivo RNAi therapies. PMID:22475061

  5. Catalysis of Supramolecular Hydrogelation.

    PubMed

    Trausel, Fanny; Versluis, Frank; Maity, Chandan; Poolman, Jos M; Lovrak, Matija; van Esch, Jan H; Eelkema, Rienk

    2016-07-19

    One often thinks of catalysts as chemical tools to accelerate a reaction or to have a reaction run under more benign conditions. As such, catalysis has a role to play in the chemical industry and in lab scale synthesis that is not to be underestimated. Still, the role of catalysis in living systems (cells, organisms) is much more extensive, ranging from the formation and breakdown of small molecules and biopolymers to controlling signal transduction cascades and feedback processes, motility, and mechanical action. Such phenomena are only recently starting to receive attention in synthetic materials and chemical systems. "Smart" soft materials could find many important applications ranging from personalized therapeutics to soft robotics to name but a few. Until recently, approaches to control the properties of such materials were largely dominated by thermodynamics, for instance, looking at phase behavior and interaction strength. However, kinetics plays a large role in determining the behavior of such soft materials, for instance, in the formation of kinetically trapped (metastable) states or the dynamics of component exchange. As catalysts can change the rate of a chemical reaction, catalysis could be used to control the formation, dynamics, and fate of supramolecular structures when the molecules making up these structures contain chemical bonds whose formation or exchange are susceptible to catalysis. In this Account, we describe our efforts to use synthetic catalysts to control the properties of supramolecular hydrogels. Building on the concept of synthesizing the assembling molecule in the self-assembly medium from nonassembling precursors, we will introduce the use of catalysis to change the kinetics of assembler formation and thereby the properties of the resulting material. In particular, we will focus on the synthesis of supramolecular hydrogels where the use of a catalyst provides access to gel materials with vastly different appearance and mechanical

  6. Evaluation of Multifunctional Polysaccharide Hydrogels with Varying Stiffness for Bone Tissue Engineering

    PubMed Central

    Zuidema, Jonathan M.; Venuto, Kathryn N.; Macione, James; Dai, Guohao; Gilbert, Ryan J.; Kotha, Shiva P.

    2013-01-01

    The use of hydrogels for bone regeneration has been limited due to their inherent low modulus to support cell adhesion and proliferation as well as their susceptibility to bacterial infections at the wound site. To overcome these limitations, we evaluated multifunctional polysaccharide hydrogels of varying stiffness to obtain the optimum stiffness at which the gels (1) induce proliferation of human dermal fibroblasts, human umbilical vascular endothelial cells (HUVECs), and murine preosteoblasts (MC3T3-E1), (2) induce osteoblast differentiation and mineralization, and (3) exhibit an antibacterial activity. Rheological studies demonstrated that the stiffness of hydrogels made of a polysaccharide blend of methylcellulose, chitosan, and agarose was increased by crosslinking the chitosan component to different extents with increasing amounts of genipin. The gelation time decreased (from 210 to 60 min) with increasing genipin concentrations. Proliferation of HUVECs decreased by 10.7 times with increasing gel stiffness, in contrast to fibroblasts and osteoblasts, where it increased with gel stiffness by 6.37 and 7.8 times, respectively. At day 14 up to day 24, osteoblast expression of differentiation markers—osteocalcin, osteopontin—and early mineralization marker—alkaline phosphatase, were significantly enhanced in the 0.5% (w/v) crosslinked gel, which also demonstrated enhanced mineralization by day 25. The antibacterial efficacy of the hydrogels decreased with the increasing degree of crosslinking as demonstrated by biofilm formation experiments, but gels crosslinked with 0.5% (w/v) genipin still demonstrated significant bacterial inhibition. Based on these results, gels crosslinked with 0.5% (w/v) genipin, where 33% of available groups on chitosan were crosslinked, exhibited a stiffness of 502±64.5 Pa and demonstrated the optimal characteristics to support bone regeneration. PMID:23724786

  7. Tough photoluminescent hydrogels doped with lanthanide.

    PubMed

    Wang, Mei Xiang; Yang, Can Hui; Liu, Zhen Qi; Zhou, Jinxiong; Xu, Feng; Suo, Zhigang; Yang, Jian Hai; Chen, Yong Mei

    2015-03-01

    Photoluminescent hydrogels have emerged as novel soft materials with potential applications in many fields. Although many photoluminescent hydrogels have been fabricated, their scope of usage has been severely limited by their poor mechanical performance. Here, a facile strategy is reported for preparing lanthanide (Ln)-alginate/polyacrylamide (PAAm) hydrogels with both high toughness and photoluminescence, which has been achieved by doping Ln(3+) ions (Ln = Eu, Tb, Eu/Tb) into alginate/PAAm hydrogel networks, where Ln(3+) ions serve as both photoluminescent emitters and physical cross-linkers. The resulting hydrogels exhibit versatile advantages including excellent mechanical properties (∼ MPa strength, ≈ 20 tensile strains, ≈ 10(4) kJ m(-3) energy dissipation), good photoluminescent performance, tunable emission color, excellent processability, and cytocompatibility. The developed tough photoluminescent hydrogels hold great promises for expanding the usage scope of hydrogels.

  8. Morphological effect on swelling behaviour of hydrogel

    SciTech Connect

    Yacob, Norzita; Hashim, Kamaruddin

    2014-02-12

    Hydrogels are hydrophilic polymer networks that are capable of imbibing large amounts of water. In this work, hydrogels prepared from natural and synthetic polymers were irradiated by using electron beam irradiation. The morphology of hydrogel inter-polymeric network (IPN) was investigated using Scanning Electron Microscopy (SEM). The studies reveal correlations between pore sizes of IPN with degree of cross-linking. This relation also has an effect on swelling properties of the hydrogel. The results indicated that hydrogel with smaller pore size, as a result of much dense IPN, would decrease water uptake capacity. Combination of natural and synthetic polymers to form hydrogel affects the pore size and swelling property of the hydrogel as compared to each component of polymer.

  9. Controlled release of ketorolac through nanocomposite films of hydrogel and LDH nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, Zhi Ping; Gu, Zi; Cheng, Xiaoxi; Rasoul, Firas; Whittaker, Andrew K.; Lu, Gao Qing Max

    2011-03-01

    A novel nanocomposite film for sustained release of anionic ophthalmic drugs through a double-control process has been examined in this study. The film, made as a drug-loaded contact lens, consists principally of a polymer hydrogel of 2-hydroxyethyl methacrylate (HEMA), in whose matrix MgAl-layered double hydroxide (MgAl-LDH) nanoparticles intercalated with the anionic drug are well dispersed. Such nanocomposite films (hydrogel-LDH-drug) contained 0.6-0.8 mg of MgAl-LDH and 0.08-0.09 mg of the ophthalmic drug (ketorolac) in 1.0 g of hydrogel. MgAl-drug-LDH nanoparticles were prepared with the hydrodynamic particle size of 40-200 nm. TEM images show that these nanoparticles are evenly dispersed in the hydrogel matrix. In vitro release tests of hydrogel-LDH-drug in pH 7.4 PBS solution at 32 °C indicate a sustained release profile of the loaded drug for 1 week. The drug release undergoes a rapid initial burst and then a monotonically decreasing rate up to 168 h. The initial burst release is determined by the film thickness and the polymerization conditions, but the following release rate is very similar, with the effective diffusion coefficient being nearly constant (3.0 × 10-12 m2/s). The drug release from the films is mechanistically attributed to anionic exchange and the subsequent diffusion in the hydrogel matrix.

  10. Synthetically Simple, Highly Resilient Hydrogels

    PubMed Central

    Cui, Jun; Lackey, Melissa A.; Madkour, Ahmad E.; Saffer, Erika M.; Griffin, David M.; Bhatia, Surita R.; Crosby, Alfred J.; Tew, Gregory N.

    2014-01-01

    Highly resilient synthetic hydrogels were synthesized by using the efficient thiol-norbornene chemistry to cross-link hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polydimethylsiloxane (PDMS) polymer chains. The swelling and mechanical properties of the hydrogels were well-controlled by the relative amounts of PEG and PDMS. In addition, the mechanical energy storage efficiency (resilience) was more than 97% at strains up to 300%. This is comparable with one of the most resilient materials known: natural resilin, an elastic protein found in many insects, such as in the tendons of fleas and the wings of dragonflies. The high resilience of these hydrogels can be attributed to the well-defined network structure provided by the versatile chemistry, low cross-link density, and lack of secondary structure in the polymer chains. PMID:22372639

  11. Forward osmosis desalination using polymer hydrogels as a draw agent: influence of draw agent, feed solution and membrane on process performance.

    PubMed

    Li, Dan; Zhang, Xinyi; Simon, George P; Wang, Huanting

    2013-01-01

    We have previously reported the use of hydrogel particles as the draw agent for forward osmosis desalination. In the present work, the effects of draw agent, feed concentration and membrane on the process performance were systematically examined. Our results showed that the incorporation of carbon filler particles in polymer hydrogels led to enhanced swelling ratios of the draw agents and thus higher water fluxes in the FO process. The composite polymer hydrogel particles of sizes ranging from 100 μm to 200 μm as draw agents induced greater water fluxes in FO desalination as compared with those with larger particle sizes (500-700 μm). Similar to other types of draw solutes, as the salt concentration in the feed increased, the water flux created by the polymer hydrogel draw agent decreased; the use of a cellulose triacetate forward osmosis membrane resulted in higher water flux compared with the use of a polyamide composite reverse osmosis membrane.

  12. Hydrogels and their medical applications

    NASA Astrophysics Data System (ADS)

    Rosiak, Janusz M.; Yoshii, Fumio

    1999-05-01

    Biomaterials play a key role in most approaches for engineering tissues as substitutes for functional replacement, for components of devices related to therapy and diagnosis, for drug delivery systems and supportive scaffolds for guided tissue growth. Modern biomaterials could be composed of various components, e.g. metals, ceramics, natural tissues, polymers. In this last group, the hydrogels, hydrophilic polymeric gels with requested biocompatibility and designed interaction with living surrounding seem to be one of the most promising group of biomaterials. Especially, if they are formed by means of ionizing radiation. In early 1950s, the pioneers of the radiation chemistry of polymers began some experiments with radiation crosslinking of hydrophilic polymers. However, hydrogels were analyzed mainly from the point of view of the phenomenon associated with radiation synthesis, with topology of network and relation between radiation parameters of the processes. Fundamental monographs on radiation polymer physics and chemistry written by A. Charlesby (Atomic Radition and polymers, Pergamon Press, Oxford, 1960) and A. Chapiro (Radiation Chemistry of Polymeric Systems, Interscience, New York, 1962) proceed from this time. The noticeable interest in the application of radiation techniques to obtain hydrogels for biomedical purposes began in the late sixties as a result of the papers and patents invented by Japanese and American scientists, headed by Kaetsu in Japan and Hoffman in USA. Immobilization of biologically active species in hydrogel matrices, their use as drug delivery systems and enzyme traps as well as the modification of material surfaces to improve biocompatibility and their ability to bond antigens and antibodies had been the main subjects of these investigations. In this article a brief summary of investigations on mechanism and kinetics of radiation formation of hydrogels as well as some examples of commercialized hydrogel biomaterials have been

  13. Impact of saccharides on the drying kinetics of agarose gels measured by in-situ interferometry

    NASA Astrophysics Data System (ADS)

    Mao, Bosi; Divoux, Thibaut; Snabre, Patrick

    2017-01-01

    Agarose gels are viscoelastic soft solids that display a porous microstructure filled with water at 90% w/w or more. Despite an extensive use in food industry and microbiology, little is known about the drying kinetics of such squishy solids, which suffers from a lack of time-resolved local measurements. Moreover, only scattered empirical observations are available on the role of the gel composition on the drying kinetics. Here we study by in-situ interferometry the drying of agarose gels of various compositions cast in Petri dishes. The gel thinning is associated with the displacement of interference fringes that are analyzed using an efficient spatiotemporal filtering method, which allows us to assess local thinning rates as low as 10 nm/s with high accuracy. The gel thinning rate measured at the center of the dish appears as a robust observable to quantify the role of additives on the gel drying kinetics and compare the drying speed of agarose gels loaded with various non-gelling saccharides of increasing molecular weights. Our work shows that saccharides systematically decrease the agarose gel thinning rate up to a factor two, and exemplifies interferometry as a powerful tool to quantify the impact of additives on the drying kinetics of polymer gels.

  14. Impact of saccharides on the drying kinetics of agarose gels measured by in-situ interferometry

    PubMed Central

    Mao, Bosi; Divoux, Thibaut; Snabre, Patrick

    2017-01-01

    Agarose gels are viscoelastic soft solids that display a porous microstructure filled with water at 90% w/w or more. Despite an extensive use in food industry and microbiology, little is known about the drying kinetics of such squishy solids, which suffers from a lack of time-resolved local measurements. Moreover, only scattered empirical observations are available on the role of the gel composition on the drying kinetics. Here we study by in-situ interferometry the drying of agarose gels of various compositions cast in Petri dishes. The gel thinning is associated with the displacement of interference fringes that are analyzed using an efficient spatiotemporal filtering method, which allows us to assess local thinning rates as low as 10 nm/s with high accuracy. The gel thinning rate measured at the center of the dish appears as a robust observable to quantify the role of additives on the gel drying kinetics and compare the drying speed of agarose gels loaded with various non-gelling saccharides of increasing molecular weights. Our work shows that saccharides systematically decrease the agarose gel thinning rate up to a factor two, and exemplifies interferometry as a powerful tool to quantify the impact of additives on the drying kinetics of polymer gels. PMID:28112236

  15. Drying techniques for the visualisation of agarose-based chromatography media by scanning electron microscopy.

    PubMed

    Nweke, Mauryn C; Turmaine, Mark; McCartney, R Graham; Bracewell, Daniel G

    2017-03-01

    The drying of chromatography resins prior to scanning electron microscopy is critical to image resolution and hence understanding of the bead structure at sub-micron level. Achieving suitable drying conditions is especially important with agarose-based chromatography resins, as over-drying may cause artefact formation, bead damage and alterations to ultrastructural properties; and under-drying does not provide sufficient resolution for visualization under SEM. This paper compares and contrasts the effects of two drying techniques, critical point drying and freeze drying, on the morphology of two agarose based resins (MabSelect™/dw ≈85 µm and Capto™ Adhere/dw ≈75 µm) and provides a complete method for both. The results show that critical point drying provides better drying and subsequently clearer ultrastructural visualization of both resins under SEM. Under this protocol both the polymer fibers (thickness ≈20 nm) and the pore sizes (diameter ≈100 nm) are clearly visible. Freeze drying is shown to cause bead damage to both resins, but to different extents. MabSelect resin encounters extensive bead fragmentation, whilst Capto Adhere resin undergoes partial bead disintegration, corresponding with the greater extent of agarose crosslinking and strength of this resin. While freeze drying appears to be the less favorable option for ultrastructural visualization of chromatography resin, it should be noted that the extent of fracturing caused by the freeze drying process may provide some insight into the mechanical properties of agarose-based chromatography media.

  16. Molecular stretching of long DNA in agarose gel using alternating current electric fields.

    PubMed Central

    Kaji, Noritada; Ueda, Masanori; Baba, Yoshinobu

    2002-01-01

    We demonstrate a novel method for stretching a long DNA molecule in agarose gel with alternating current (AC) electric fields. The molecular motion of a long DNA (T4 DNA; 165.6 kb) in agarose gel was studied using fluorescence microscopy. The effects of a wide range of field frequencies, field strengths, and gel concentrations were investigated. Stretching was only observed in the AC field when a frequency of approximately 10 Hz was used. The maximal length of the stretched DNA had the longest value when a field strength of 200 to 400 V/cm was used. Stretching was not sensitive to a range of agarose gel concentrations from 0.5 to 3%. Together, these experiments indicate that the optimal conditions for stretching long DNA in an AC electric field are a frequency of 10 Hz with a field strength of 200 V/cm and a gel concentration of 1% agarose. Using these conditions, we were able to successfully stretch Saccharomyces cerevisiae chromosomal DNA molecules (225-2,200 kb). These results may aid in the development of a novel method to stretch much longer DNA, such as human chromosomal DNA, and may contribute to the analysis of a single chromosomal DNA from a single cell. PMID:11751320

  17. Quantitation of Alkaline Phosphatase Isoenzymes Using Agarose Containing Wheat Germ Lectin

    DTIC Science & Technology

    1989-07-01

    SIl Quantitation of Alkaline Phosphatase Isoenzymes Using Agarose Containing Wheat Germ Lectin A thesis submitted in partial fulfillment of the...16 Wheat Germ Lectin Electrophoresis to Quantitate Alkaline Phosphatase Isoenzymes ................ 16 Alkaline Phosphatase Isoenzyme...vs Polyacrylamide Gel Electrophoresis ......................... 40 Clinical Correlation Using Wheat Germ Lectin 45 Placental Alkaline Phosphatase

  18. Can You Solve the Crime? Using Agarose Electrophoresis To Identify an Unknown Colored Protein.

    ERIC Educational Resources Information Center

    Wiltfong, Cynthia L.; Chester, Emily; Albertin, Faith; Smith, Julia; Hall, Judith C.; Arth, Emily C.; Martin, Stephanie

    2003-01-01

    Describes a lab that introduces agarose electrophoresis techniques and basic information on proteins to middle school and high school students. Insists that, built around a scenario in which students must solve a crime, the lab has real-world applications that should spark student interest. (KHR)

  19. Enhanced Resolution of DNA Separation Using Agarose Gel Electrophoresis Doped with Graphene Oxide.

    PubMed

    Li, Jialiang; Yang, Yushi; Mao, Zhou; Huang, Wenjie; Qiu, Tong; Wu, Qingzhi

    2016-12-01

    In this work, a novel agarose gel electrophoresis strategy has been developed for separation of DNA fragments by doping graphene oxide (GO) into agarose gel. The results show that the addition of GO into agarose gel significantly improved the separation resolution of DNA fragments by increasing the shift distances of both the single DNA fragments and the adjacent DNA fragments and completely eliminating the background noise derived from the diffusion of the excessive ethidium bromide (EB) dye in the gel after electrophoresis. The improved resolution of DNA fragments in GO-doped agarose gel could be attributed to the successive adsorption-desorption processes between DNA fragments and GO sheets, while the elimination of the background noise could be attributed to the adsorption of the excessive EB dye on the surface of GO sheets and high fluorescence quenching efficiency of GO. These results provide promising potential for graphene and its derivate utilized in various electrophoresis techniques for separation and detection of DAN fragments and other biomolecules.

  20. Enhanced Resolution of DNA Separation Using Agarose Gel Electrophoresis Doped with Graphene Oxide

    NASA Astrophysics Data System (ADS)

    Li, Jialiang; Yang, Yushi; Mao, Zhou; Huang, Wenjie; Qiu, Tong; Wu, Qingzhi

    2016-09-01

    In this work, a novel agarose gel electrophoresis strategy has been developed for separation of DNA fragments by doping graphene oxide (GO) into agarose gel. The results show that the addition of GO into agarose gel significantly improved the separation resolution of DNA fragments by increasing the shift distances of both the single DNA fragments and the adjacent DNA fragments and completely eliminating the background noise derived from the diffusion of the excessive ethidium bromide (EB) dye in the gel after electrophoresis. The improved resolution of DNA fragments in GO-doped agarose gel could be attributed to the successive adsorption-desorption processes between DNA fragments and GO sheets, while the elimination of the background noise could be attributed to the adsorption of the excessive EB dye on the surface of GO sheets and high fluorescence quenching efficiency of GO. These results provide promising potential for graphene and its derivate utilized in various electrophoresis techniques for separation and detection of DAN fragments and other biomolecules.

  1. Rapid recovery of DNA from agarose gel slices by coupling electroelution with monolithic SPE.

    PubMed

    Yu, Shengbing; Yang, Shuixian; Zhou, Ping; Zhou, Ke; Wang, Jing; Chen, Xiangdong

    2009-06-01

    An amino silica monolithic column prepared by in situ polymerization of tetraethoxysilane and N-(beta-aminoethyl)-gamma-aminopropyltriethoxysilane was firstly applied to recover DNA from agarose gel slices by coupling electroelution with monolithic SPE. DNA was electroeluted from the agarose gel slices onto the amino silica monolithic column. The DNA adsorbed on this monolithic column was then recovered using sodium phosphate solution at pH 10. The whole recovery procedure could be completed within 10 min because the use of amino silica monolithic column accelerated the DNA capture and facilitated the DNA release. Electroelution conditions, such as buffer pH, buffer concentration and applied voltage, were online optimized. The average yield for herring sperm DNA, pBR 322 DNA and lambda DNA recovered from 1.0% w/v agarose gel slices were 55+/-4, 50+/-6 and 42+/-7% (n=3), respectively. The polymerase chain reaction performance of pGM plasmid recovered from agarose gel slices demonstrated that the method could provide high-quality DNA for downstream processes. The combination of electroelution with monolithic SPE allows a rapid, simple and efficient DNA recovery method. This technique is especially useful for applications that need to purify small starting amounts of DNA.

  2. Electrophoresis of DNA in agarose gels, polyacrylamide gels and in free solution.

    PubMed

    Stellwagen, Nancy C

    2009-06-01

    This review describes the electrophoresis of curved and normal DNA molecules in agarose gels, polyacrylamide gels and in free solution. These studies were undertaken to clarify why curved DNA molecules migrate anomalously slowly in polyacrylamide gels but not in agarose gels. Two milestone papers are cited, in which Ferguson plots were used to estimate the effective pore size of agarose and polyacrylamide gels. Subsequent studies on the effect of the electric field on agarose and polyacrylamide gel matrices, DNA interactions with the two gel matrices, and the effect of curvature on the free solution mobility of DNA are also described. The combined results suggest that the anomalously slow mobilities observed for curved DNA molecules in polyacrylamide gels are primarily due to preferential interactions of curved DNAs with the polyacrylamide gel matrix; the restrictive pore size of the matrix is of lesser importance. In free solution, DNA mobilities increase with increasing molecular mass until leveling off at a plateau value of (3.17 +/- 0.01) x 10(-4) cm2/V s in 40 mM Tris-acetate-EDTA buffer at 20 degrees C. Curved DNA molecules migrate anomalously slowly in free solution as well as in polyacrylamide gels, explaining why the Ferguson plots of curved and normal DNAs containing the same number of base pairs extrapolate to different mobilities at zero gel concentration.

  3. Modified gel preparation for distinct DNA fragment analysis in agarose gel electrophoresis.

    PubMed

    Lee, S V; Bahaman, A R

    2010-08-01

    Agarose gel electrophoresis is the standard method that is used to separate, identify, and purify DNA fragments. However, this method is time-consuming and capable of separating limited range of fragments. A new technique of gel preparation was developed to improve the DNA fragment analysis via electrophoresis.

  4. Modification of agarose: 6-aminoagarose mediated syntheses of fluorogenic pyridine carboxylic acid amides.

    PubMed

    Kondaveeti, Stalin; Mehta, Gaurav K; Siddhanta, A K

    2014-06-15

    A facile 6-aminoagarose (AA) mediated synthesis of new fluorogenic amides of agarose with nicotinic (AA-NA) and picolinic acids (AA-PA) employing carbodiimide chemistry have been described. 6-Amino agarose (AA) was synthesized in a facile Mitsunobu-inspired microwave mediated method involving the reaction of agarose with phthalimide in presence of diisopropyl azodicarboxylate and triphenylphosphene (DIAD/TPP) followed by hydrazinolysis. All compounds were characterized by GPC, UV spectrophotometry, fluorescence spectroscopy, FT-IR, (1)H and (13)C NMR spectra. The fluorescence emissions (λmax 430 and 412 nm) of 1 × 10(-3)M solutions of AA-NA and AA-PA in water were significantly higher (ca. 82% and ca. 90%) than those of the molar equivalents (0.2mg) of NA and PA present in the 1 × 10(-3)M solutions of the amides, respectively. These fluorogenic pyridine carboxylic acid amides of agarose may find applications as sensors in biomedical and pharmaceutical industries.

  5. Purification of antibodies against N-homocysteinylated proteins by affinity chromatography on Nomega-homocysteinyl-aminohexyl-Agarose.

    PubMed

    Perła, Joanna; Undas, Anetta; Twardowski, Tomasz; Jakubowski, Hieronim

    2004-08-05

    Modification with homocysteine (Hcy)-thiolactone leads to the formation of N-Hcy-Lys-protein. Although N-Hcy-Lys-proteins are immunogenic, pure antibodies have not yet been obtained. Here we describe synthesis and application of Nomega-homocysteinyl-aminohexyl-Agarose for affinity purification of anti-N-Hcy-Lys-protein antibodies. Nomega-homocysteinyl-aminohexyl-Agarose was prepared by N-homocysteinylation of omega-aminohexyl-Agarose with Hcy-thiolactone. Immune serum was obtained from rabbits inoculated with N-Hcy-Lys-keyhole limpet hemocyanine and IgG fraction prepared by chromatography on protein A-Agarose. Anti-N-Hcy-Lys-protein IgG was adsorbed on Nomega-homocysteinyl-aminohexyl-Agarose column at pH 8.6 and eluted with a pH 2.3 buffer. Enzyme-linked immunosorbent assays demonstrate that the antibody recognizes specifically N-homocysteinylated variants of hemoglobin, albumin, transferrin, and antitrypsin.

  6. Self-Healing Nanocomposite Hydrogel with Well-Controlled Dynamic Mechanics

    NASA Astrophysics Data System (ADS)

    Li, Qiaochu; Mishra, Sumeet; Chen, Pangkuan; Tracy, Joseph; Holten-Andersen, Niels

    Network dynamics is a crucial factor that determines the macroscopic self-healing rate and efficiency in polymeric hydrogel materials, yet its controllability is seldom studied in most reported self-healing hydrogel systems. Inspired by mussel's adhesion chemistry, we developed a novel approach to assemble inorganic nanoparticles and catechol-decorated PEG polymer into a hydrogel network. When utilized as reversible polymer-particle crosslinks, catechol-metal coordination bonds yield a unique gel network with dynamic mechanics controlled directly by interfacial crosslink structure. Taking advantage of this structure-property relationship at polymer-particle interfaces, we next designed a hierarchically structured hybrid gel with two distinct relaxation timescales. By tuning the relative contribution of the two hierarchical relaxation modes, we are able to finely control the gel's dynamic mechanical behavior from a viscoelastic fluid to a stiff solid, yet preserving its fast self-healing property without the need for external stimuli.

  7. The rotation and translation of non-spherical particles in homogeneous isotropic turbulence

    NASA Astrophysics Data System (ADS)

    Byron, Margaret

    The motion of particles suspended in environmental turbulence is relevant to many scientific fields, from sediment transport to biological interactions to underwater robotics. At very small scales and simple shapes, we are able to completely mathematically describe the motion of inertial particles; however, the motion of large aspherical particles is significantly more complex, and current computational models are inadequate for large or highly-resolved domains. Therefore, we seek to experimentally investigate the coupling between freely suspended particles and ambient turbulence. A better understanding of this coupling will inform not only engineering and physics, but the interactions between small aquatic organisms and their environments. In the following pages, we explore the roles of shape and buoyancy on the motion of passive particles in turbulence, and allow these particles to serve as models for meso-scale aquatic organisms. We fabricate cylindrical and spheroidal particles and suspend them in homogeneous, isotropic turbulence that is generated via randomly-actuated jet arrays. The particles are fabricated with agarose hydrogel, which is refractive-index-matched to the surrounding fluid (water). Both the fluid and the particle are seeded with passive tracers, allowing us to perform Particle Image Velocimetry (PIV) simultaneously on the particle and fluid phase. To investigate the effects of shape, particles are fabricated at varying aspect ratios; to investigate the effects of buoyancy, particles are fabricated at varying specific gravities. Each particle type is freely suspended at a volume fraction of F=0.1%, for which four-way coupling interactions are negligible. The suspended particles are imaged together with the surrounding fluid and analyzed using stereoscopic PIV, which yields three velocity components in a two-dimensional measurement plane. Using image thresholding, the results are separated into simultaneous fluid-phase and solid-phase velocity

  8. Enhancement of in vitro and in vivo function of agarose-encapsulated porcine islets by changes in the islet microenvironment.

    PubMed

    Holdcraft, Robert W; Gazda, Lawrence S; Circle, Lisa; Adkins, Hollie; Harbeck, Steven G; Meyer, Eric D; Bautista, Melissa A; Martis, Prithy C; Laramore, Melissa A; Vinerean, Horatiu V; Hall, Richard D; Smith, Barry H

    2014-01-01

    The transplantation of porcine islets of Langerhans to treat type 1 diabetes may provide a solution to the demand for insulin-producing cells. Porcine islets encapsulated in agarose-agarose macrobeads have been shown to function in nonimmunosuppressed xenogeneic models of both streptozotocin-induced and autoimmune type 1 diabetes. One advantage of agarose encapsulation is the ability to culture macrobeads for extended periods, permitting microbiological and functional assessment. Herein we describe optimization of the agarose matrix that results in improved islet function. Porcine islets (500 IEQs) from retired breeding sows were encapsulated in 1.5% SeaKem Gold (SG), 0.8% SG, or 0.8% Litex (Li) agarose, followed by an outer capsule of 5% SG agarose. Insulin production by the encapsulated islets exhibited an agarose-specific effect with 20% (0.8% SG) to 50% (0.8% Li) higher initial insulin production relative to 1.5% SG macrobeads. Insulin production was further increased by 40-50% from week 2 to week 12 in both agarose types at the 0.8% concentration, whereas islets encapsulated in 1.5% SG agarose increased insulin production by approximately 20%. Correspondingly, fewer macrobeads were required to restore normoglycemia in streptozotocin-induced diabetic female CD(SD) rats that received 0.8% Li (15 macrobeads) or 0.8% SG (17 macrobeads) as compared to 1.5% SG (19 macrobeads). Islet cell proliferation was also observed during the first 2 months postencapsulation, peaking at 4 weeks, where approximately 50% of islets contained proliferative cells, including β-cells, regardless of agarose type. These results illustrate the importance of optimizing the microenvironment of encapsulated islets to improve islet performance and advance the potential of islet xenotransplantation for the treatment of type 1 diabetes.

  9. Ultrasonic wave propagation assessment of native cartilage explants and hydrogel scaffolds for tissue engineering

    PubMed Central

    Kohles, Sean S.; Mason, Shelley S.; Adams, Anya P.; Berg, Robert J.; Blank, Jessica; Gibson, Fay; Righetti, Johnathan; Washington, Iesha S.; Saha, Asit K.

    2012-01-01

    Non-destructive techniques characterising the mechanical properties of cells, tissues, and biomaterials provide baseline metrics for tissue engineering design. Ultrasonic wave propagation and attenuation has previously demonstrated the dynamics of extracellular matrix synthesis in chondrocyte-seeded hydrogel constructs. In this paper, we describe an ultrasonic method to analyse two of the construct elements used to engineer articular cartilage in real-time, native cartilage explants and an agarose biomaterial. Results indicated a similarity in wave propagation velocity ranges for both longitudinal (1500–1745 m/s) and transverse (350–950 m/s) waveforms. Future work will apply an acoustoelastic analysis to distinguish between the fluid and solid properties including the cell and matrix biokinetics as a validation of previous mathematical models. PMID:23565122

  10. A templated agarose scaffold for axon guidance in the central and peripheral nervous system

    NASA Astrophysics Data System (ADS)

    Gros, Thomas Richard

    This thesis examined the hypothesis that axonal guidance could be improved in the central and peripheral nervous systems using a highly linearized templated agarose scaffold. In the present study we examined whether a templated agarose scaffold improved axon retention across a large central nervous system (CNS) lesion and how cellular and axonal orientation was affected within the scaffold channels. The "physical" guidance from the scaffold was applied to an existing CNS "chemical" guidance strategy, shown to promote axons beyond the lesion site, to enhance the number of crossing axons in larger, disorganized, lesions. Specifically, there was the greatest number of long-tract sensory axons reaching the distal aspect of the lesion when the templated agarose scaffold was combined with a neurotrophic source of NT-3 beyond the lesion site and a conditioning lesion, to enhance chemical axon guidance and the intrinsic growth state of axons, respectively. When comparing the scaffold implant to a cell suspension grafts, we found a higher retention of long-tract ascending (sensory) axons and descending (motor) axons crossing large lesions (2mm). The enhanced axon retention may be attributed to the finding that cellular orientation within the scaffold channels is highly linear, thus promoting a less tortuous environment for axon orientation and bridging. Although an enhanced number of axons were able to cross the lesion, the axons did not repenetrate the host tissue due to a reactive cell layer, present only in scaffold the implant groups. Additionally, a peripheral nerve conduit, with the agarose scaffold as the core, displayed biocompatiablility and supported axon growth and vasculature beyond the clinically applicable distance of 4mm. Thus, the templated agarose scaffold enhances axon retention and guidance within CNS injury sites and has potential applications to the PNS.

  11. Non-toxic agarose/gelatin-based microencapsulation system containing gallic acid for antifungal application.

    PubMed

    Lam, P-L; Gambari, R; Kok, S H-L; Lam, K-H; Tang, J C-O; Bian, Z-X; Lee, K K-H; Chui, C-H

    2015-02-01

    Aspergillus niger (A. niger) is a common species of Aspergillus molds. Cutaneous aspergillosis usually occurs in skin sites near intravenous injection and approximately 6% of cutaneous aspergillosis cases which do not involve burn or HIV-infected patients are caused by A. niger. Biomaterials and biopharmaceuticals produced from microparticle-based drug delivery systems have received much attention as microencapsulated drugs offer an improvement in therapeutic efficacy due to better human absorption. The frequently used crosslinker, glutaraldehyde, in gelatin-based microencapsulation systems is considered harmful to human beings. In order to tackle the potential risks, agarose has become an alternative polymer to be used with gelatin as wall matrix materials of microcapsules. In the present study, we report the eco-friendly use of an agarose/gelatin-based microencapsulation system to enhance the antifungal activity of gallic acid and reduce its potential cytotoxic effects towards human skin keratinocytes. We used optimal parameter combinations, such as an agarose/gelatin ratio of 1:1, a polymer/oil ratio of 1:60, a surfactant volume of 1% w/w and a stirring speed of 900 rpm. The minimum inhibitory concentration of microencapsulated gallic acid (62.5 µg/ml) was significantly improved when compared with that of the original drug (>750 µg/ml). The anti-A. niger activity of gallic acid -containing microcapsules was much stronger than that of the original drug. Following 48 h of treatment, skin cell survival was approximately 90% with agarose/gelatin microcapsules containing gallic acid, whereas cell viability was only 25-35% with free gallic acid. Our results demonstrate that agarose/gelatin-based microcapsules containing gallic acid may prove to be helpful in the treatment of A. niger-induced skin infections near intravenous injection sites.

  12. pH-responsive and enzymatically-responsive hydrogel microparticles for the oral delivery of therapeutic proteins: Effects of protein size, crosslinking density, and hydrogel degradation on protein delivery.

    PubMed

    Koetting, Michael Clinton; Guido, Joseph Frank; Gupta, Malvika; Zhang, Annie; Peppas, Nicholas A

    2016-01-10

    Two potential platform technologies for the oral delivery of protein therapeutics were synthesized and tested. pH-responsive poly(itaconic acid-co-N-vinyl-2-pyrrolidone) (P(IA-co-NVP)) hydrogel microparticles were tested in vitro with model proteins salmon calcitonin, urokinase, and rituximab to determine the effects of particle size, protein size, and crosslinking density on oral delivery capability. Particle size showed no significant effect on overall delivery potential but did improve percent release of encapsulated protein over the micro-scale particle size range studied. Protein size was shown to have a significant impact on the delivery capability of the P(IA-co-NVP) hydrogel. We show that when using P(IA-co-NVP) hydrogel microparticles with 3 mol% tetra(ethylene glycol) dimethacrylate crosslinker, a small polypeptide (salmon calcitonin) loads and releases up to 45 μg/mg hydrogel while the mid-sized protein urokinase and large monoclonal antibody rituximab load and release only 19 and 24 μg/mg hydrogel, respectively. We further demonstrate that crosslinking density offers a simple method for tuning hydrogel properties to variously sized proteins. Using 5 mol% TEGDMA crosslinker offers optimal performance for the small peptide, salmon calcitonin, whereas lower crosslinking density of 1 mol% offers optimal performance for the much larger protein rituximab. Finally, an enzymatically-degradable hydrogels of P(MAA-co-NVP) crosslinked with the peptide sequence MMRRRKK were synthesized and tested in simulated gastric and intestinal conditions. These hydrogels offer ideal loading and release behavior, showing no degradative release of encapsulated salmon calcitonin in gastric conditions while yielding rapid and complete release of encapsulated protein within 1h in intestinal conditions.

  13. Repairable, nanostructured biomimetic hydrogels

    NASA Astrophysics Data System (ADS)

    Firestone, M.; Brombosz, S.; Grubjesic, S.

    2013-03-01

    Proteins facilitate many key cellular processes, including signal recognition and energy transduction. The ability to harness this evolutionarily-optimized functionality could lead to the development of protein-based systems useful for advancing alternative energy storage and conversion. The future of protein-based, however, requires the development of materials that will stabilize, order and control the activity of the proteins. Recently we have developed a synthetic approach for the preparation of a durable biomimetic chemical hydrogel that can be reversibly swollen in water. The matrix has proven ideal for the stable encapsulation of both water- and membrane-soluble proteins. The material is composed of an aqueous dispersion of a diacrylate end-derivatized PEO-PPO-PEO macromer, a saturated phospholipid and a zwitterionic co-surfactant that self-assembles into a nanostructured physical gel at room temperature as determined by X-ray scattering. The addition of a water soluble PEGDA co-monomer and photoinitator does not alter the self-assembled structure and UV irradiation serves to crosslink the acrylate end groups on the macromer with the PEGDA forming a network within the aqueous domains as determined by FT-IR. More recently we have begun to incorporate reversible crosslinks employing Diels-Alder chemistry, allowing for the extraction and replacement of inactive proteins. The ability to replenish the materials with active, non-denatured forms of protein is an important step in advancing these materials for use in nanostructured devices This work was supported by the Office of Basic Energy Sciences, Division of Materials Sciences, USDoE under Contract No. DE-AC02-06CH11357.

  14. Polyvinyl alcohol hydrogels for iontohporesis

    NASA Astrophysics Data System (ADS)

    Bera, Prasanta; Alam, Asif Ali; Arora, Neha; Tibarewala, Dewaki Nandan; Basak, Piyali

    2013-06-01

    Transdermal therapeutic systems propound controlled release of active ingredients through the skin into the systemic circulation in a predictive manner. Drugs administered through these systems escape first-pass metabolism and maintain a steady state scenario similar to a continuous intravenous infusion for up to several days. The iontophoresis deal with the systemic delivery of the bioactive agents (drug) by applying an electric current. It is basically an injection without the needle. The iontophoretic system requires a gel-based matrix to accommodate the bioactive agent. Hydrogels have been used by many investigators in controlled-release drug delivery systems because of their good tissue compatibility and easy manipulation of swelling level and, thereby, solute permeability. In this work we have prepared polyvinyl alcohol (PVA) hydrogel. We have cross linked polyvinyl alcohol chemically with Glutaraldehyde with different wt%. FTIR study reveals the chemical changes during cross linking. Swelling in water, is done to have an idea about drug loading and drug release from the membrane. After drug loading to the hydrogels, we have studied the drug release property of the hydrogels using salicylic acid as a model drug.

  15. Conductive hydrogel containing 3-ionene

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping Siao (Inventor)

    1977-01-01

    Cationic polyelectrolytes formed by the polymerization in absence of oxygen of a monomer of the general formula: dispersed ##STR1## where x is 3 or more than 6 and Z is I, Br or Cl to form high charge density linear polymers are dispered in a water-soluble polymer such as polyvinyl alcohol to form a conductive hydrogel.

  16. Immobilization of Aspergillus oryzae β-galactosidase in an agarose matrix functionalized by four different methods and application to the synthesis of lactulose.

    PubMed

    Guerrero, Cecilia; Vera, Carlos; Serna, Nestor; Illanes, Andrés

    2017-02-07

    Aspergillus oryzae β-galactosidase was immobilized in monofunctional glyoxyl-agarose and heterofunctional supports (amino-glyoxyl, carboxy-glyoxyl and chelate-glyoxyl agarose), for obtaining highly active and stable catalysts for lactulose synthesis. Specific activities of the amino-glyoxyl agarose, carboxy-glyoxyl agarose and chelate-glyoxyl agarose derivatives were 3676, 430 and 454IU/g biocatalyst with half-life values at 50°C of 247, 100 and 100h respectively. Specific activities of 3490, 2559 and 1060IU/g were obtained for fine, standard and macro agarose respectively. High immobilization yield (39.4%) and specific activity of 7700IU/g was obtained with amino-glyoxyl-agarose as support. The highest yields of lactulose synthesis were obtained with monofunctional glyoxyl-agarose. Selectivity of lactulose synthesis was influenced by the support functionalization: glyoxyl-agarose and amino-glyoxyl-agarose derivatives retained the selectivity of the free enzyme, while selectivity with the carboxy-glyoxyl-agarose and chelate-glyoxyl-agarose derivatives was reduced, favoring the synthesis of transgalactosylated oligosaccharides over lactulose.

  17. Peptide hydrogelation triggered by enzymatic induced pH switch

    NASA Astrophysics Data System (ADS)

    Cheng, Wei; Li, Ying

    2016-07-01

    It remains challenging to develop methods that can precisely control the self-assembling kinetics and thermodynamics of peptide hydrogelators to achieve hydrogels with optimal properties. Here we report the hydrogelation of peptide hydrogelators by an enzymatically induced pH switch, which involves the combination of glucose oxidase and catalase with D-glucose as the substrate, in which both the gelation kinetics and thermodynamics can be controlled by the concentrations of D-glucose. This novel hydrogelation method could result in hydrogels with higher mechanical stability and lower hydrogelation concentrations. We further illustrate the application of this hydrogelation method to differentiate different D-glucose levels.

  18. Massively parallel single-molecule and single-cell emulsion reverse transcription polymerase chain reaction using agarose droplet microfluidics.

    PubMed

    Zhang, Huifa; Jenkins, Gareth; Zou, Yuan; Zhu, Zhi; Yang, Chaoyong James

    2012-04-17

    A microfluidic device for performing single copy, emulsion Reverse Transcription Polymerase Chain Reaction (RT-PCR) within agarose droplets is presented. A two-aqueous-inlet emulsion droplet generator was designed and fabricated to produce highly uniform monodisperse picoliter agarose emulsion droplets with RT-PCR reagents in carrier oil. Template RNA or cells were delivered from one inlet with RT-PCR reagents/cell lysis buffer delivered separately from the other. Efficient RNA/cell encapsulation and RT-PCR at the single copy level was achieved in agarose-in-oil droplets, which, after amplification, can be solidified into agarose beads for further analysis. A simple and efficient method to graft primer to the polymer matrix using 5'-acrydite primer was developed to ensure highly efficient trapping of RT-PCR products in agarose. High-throughput single RNA molecule/cell RT-PCR was demonstrated in stochastically diluted solutions. Our results indicate that single-molecule RT-PCR can be efficiently carried out in agarose matrix. Single-cell RT-PCR was successfully performed which showed a clear difference in gene expression level of EpCAM, a cancer biomarker gene, at the single-cell level between different types of cancer cells. This work clearly demonstrates for the first time, single-copy RT-PCR in agarose droplets. We believe this will open up new possibilities for viral RNA detection and single-cell transcription analysis.

  19. A facile one-pot synthesis of a fluorescent agarose-O-naphthylacetyl adduct with slow release properties.

    PubMed

    Kondaveeti, Stalin; Chejara, Dharmesh R; Siddhanta, A K

    2013-10-15

    A microwave assisted facile synthesis of a fluorescent 6-O-naphthylacetyl agarose (NA-agarose) employing carbodiimide chemistry (dicyclohexylcarbodiimide/4-dimethylaminopyridine) has been described. NA-agarose was characterized by TGA, GPC, UV spectrophotometry, fluorescence spectroscopy, FT-IR, (1)H and (13)C NMR spectra, exhibiting that in NA-agarose the naphthylacetyl group was attached to the backbone of the agarose polymer. The hydrolysis of NA-agarose in heterogeneous aqueous phase showed that the 1-naphthyl acetic acid (NAA), a plant growth regulator, got released in a controlled manner, the release rate being dependent on the hydrophilicity of the polymer adduct as well as on pH and temperature. The fluorescence emission (λmax 332 nm) of NA-agarose (1×10(-3) M) in ethylene glycol was significantly higher (ca. 82%) than that of the molar equivalent of NAA content in the product i.e. 0.08 mg in 1×10(-3) M solution. The resulting polymer would be of potential utility as a sustained release plant growth regulator and sensory applications.

  20. Bonding of synthetic hydrogels with fibrin as the glue to engineer hydrogel-based biodevices.

    PubMed

    Nagamine, Kuniaki; Okamoto, Kohei; Kaji, Hirokazu; Nishizawa, Matsuhiko

    2014-07-01

    We show the fibrous protein fibrin can serve as biocompatible glue with which to bind synthetic cationic or anionic hydrogels together. Both the bonding to and detachment from the hydrogels by fibrin (gelation and degradation, respectively) proceeded enzymatically under physiological conditions. We built a hydrogel-based actuator to demonstrate the method.

  1. Hydrogels for Engineering of Perfusable Vascular Networks.

    PubMed

    Liu, Juan; Zheng, Huaiyuan; Poh, Patrina S P; Machens, Hans-Günther; Schilling, Arndt F

    2015-07-14

    Hydrogels are commonly used biomaterials for tissue engineering. With their high-water content, good biocompatibility and biodegradability they resemble the natural extracellular environment and have been widely used as scaffolds for 3D cell culture and studies of cell biology. The possible size of such hydrogel constructs with embedded cells is limited by the cellular demand for oxygen and nutrients. For the fabrication of large and complex tissue constructs, vascular structures become necessary within the hydrogels to supply the encapsulated cells. In this review, we discuss the types of hydrogels that are currently used for the fabrication of constructs with embedded vascular networks, the key properties of hydrogels needed for this purpose and current techniques to engineer perfusable vascular structures into these hydrogels. We then discuss directions for future research aimed at engineering of vascularized tissue for implantation.

  2. Hydrogels for Engineering of Perfusable Vascular Networks

    PubMed Central

    Liu, Juan; Zheng, Huaiyuan; Poh, Patrina S. P.; Machens, Hans-Günther; Schilling, Arndt F.

    2015-01-01

    Hydrogels are commonly used biomaterials for tissue engineering. With their high-water content, good biocompatibility and biodegradability they resemble the natural extracellular environment and have been widely used as scaffolds for 3D cell culture and studies of cell biology. The possible size of such hydrogel constructs with embedded cells is limited by the cellular demand for oxygen and nutrients. For the fabrication of large and complex tissue constructs, vascular structures become necessary within the hydrogels to supply the encapsulated cells. In this review, we discuss the types of hydrogels that are currently used for the fabrication of constructs with embedded vascular networks, the key properties of hydrogels needed for this purpose and current techniques to engineer perfusable vascular structures into these hydrogels. We then discuss directions for future research aimed at engineering of vascularized tissue for implantation. PMID:26184185

  3. Chitosan based hydrogels: characteristics and pharmaceutical applications

    PubMed Central

    Ahmadi, F.; Oveisi, Z.; Samani, S. Mohammadi; Amoozgar, Z.

    2015-01-01

    Hydrogel scaffolds serve as semi synthetic or synthetic extra cellular matrix to provide an amenable environment for cellular adherence and cellular remodeling in three dimensional structures mimicking that of natural cellular environment. Additionally, hydrogels have the capacity to carry small molecule drugs and/or proteins, growth factors and other necessary components for cell growth and differentiation. In the context of drug delivery, hydrogels can be utilized to localize drugs, increase drugs concentration at the site of action and consequently reduce off-targeted side effects. The current review aims to describe and classify hydrogels and their methods of production. The main highlight is chitosan-based hydrogels as biocompatible and medically relevant hydrogels for drug delivery. PMID:26430453

  4. Nanostructure controlled sustained delivery of human growth hormone using injectable, biodegradable, pH/temperature responsive nanobiohybrid hydrogel

    NASA Astrophysics Data System (ADS)

    Singh, Narendra K.; Nguyen, Quang Vinh; Kim, Bong Sup; Lee, Doo Sung

    2015-02-01

    The clinical efficacy of a therapeutic protein, the human growth hormone (hGH), is limited by its short plasma half-life and premature degradation. To overcome this limitation, we proposed a new protein delivery system by the self-assembly and intercalation of a negatively charged hGH onto a positively charged 2D-layered double hydroxide nanoparticle (LDH). The LDH-hGH ionic complex, with an average particle size of approximately 100 nm, retards hGH diffusion. Nanobiohybrid hydrogels (PAEU/LDH-hGH) were prepared by dispersing the LDH-hGH complex into a cationic pH- and temperature-sensitive injectable PAEU copolymer hydrogel to enhance sustained hGH release by dual ionic interactions. Biodegradable copolymer hydrogels comprising poly(β-amino ester urethane) and triblock poly(ε-caprolactone-lactide)-poly(ethylene glycol)-poly-(ε-caprolactone-lactide) (PCLA-PEG-PCLA) were synthesized and characterized. hGH was self-assembled and intercalated onto layered LDH nanoparticles through an anion exchange technique. X-ray diffraction and zeta potential results showed that the LDH-hGH complex was prepared successfully and that the PAEU/LDH-hGH nanobiohybrid hydrogel had a disordered intercalated nanostructure. The biocompatibility of the nanobiohybrid hydrogel was confirmed by an in vitro cytotoxicity test. The in vivo degradation of pure PAEU and its nanobiohybrid hydrogels was investigated and it showed a controlled degradation of the PAEU/LDH nanobiohybrids compared with the pristine PAEU copolymer hydrogel. The LDH-hGH loaded injectable hydrogels suppressed the initial burst release of hGH and extended the release period for 13 days in vitro and 5 days in vivo. The developed nanohybrid hydrogel has the potential for application as a protein carrier to improve patient compliance.The clinical efficacy of a therapeutic protein, the human growth hormone (hGH), is limited by its short plasma half-life and premature degradation. To overcome this limitation, we proposed a new

  5. Fast deswelling of nanocomposite polymer hydrogels via magnetic field-induced heating for emerging FO desalination.

    PubMed

    Razmjou, Amir; Barati, Mohammad Reza; Simon, George P; Suzuki, Kiyonori; Wang, Huanting

    2013-06-18

    Freshwater shortage is one of the most pressing global issues. Forward osmosis (FO) desalination technology is emerging for freshwater production from saline water, which is potentially more energy-efficient than the current reverse osmosis process. However, the lack of a suitable draw solute is the major hurdle for commercial implementation of the FO desalination technology. We have previously reported that thermoresponsive hydrogels can be used as the draw agent for a FO process, and this new hydrogel-driven FO process holds promise for further development for practical application. In the present work, magnetic field-induced heating is explored for the purpose of developing a more effective way to recover water from swollen hydrogel draw agents. The composite hydrogel particles are prepared by copolymerization of sodium acrylate and N-isopropylacrylamide in the presence of magnetic nanoparticles (γ-Fe2O3, <50 nm). The results indicate that the magnetic heating is an effective and rapid method for dewatering of hydrogels by generating the heat more uniformly throughout the draw agent particles, and thus, a dense skin layer commonly formed via conventional heating from the outside of the particle is minimized. The FO dewatering performance is affected by the loading of magnetic nanoparticles and magnetic field intensity. Significantly enhanced liquid water recovery (53%) is achieved under magnetic heating, as opposed to only around 7% liquid water recovery obtained via convection heating. Our study shows that the magnetic heating is an attractive alternative stimulus for the extraction of highly desirable liquid water from the draw agent in the polymer hydrogel-driven forward osmosis process.

  6. Hydrogel nanoparticle based immunoassay

    DOEpatents

    Liotta, Lance A; Luchini, Alessandra; Petricoin, Emanuel F; Espina, Virginia

    2015-04-21

    An immunoassay device incorporating porous polymeric capture nanoparticles within either the sample collection vessel or pre-impregnated into a porous substratum within fluid flow path of the analytical device is presented. This incorporation of capture particles within the immunoassay device improves sensitivity while removing the requirement for pre-processing of samples prior to loading the immunoassay device. A preferred embodiment is coreshell bait containing capture nanoparticles which perform three functions in one step, in solution: a) molecular size sieving, b) target analyte sequestration and concentration, and c) protection from degradation. The polymeric matrix of the capture particles may be made of co-polymeric materials having a structural monomer and an affinity monomer, the affinity monomer having properties that attract the analyte to the capture particle. This device is useful for point of care diagnostic assays for biomedical applications and as field deployable assays for environmental, pathogen and chemical or biological threat identification.

  7. Enzyme Induced Formation of Monodisperse Hydrogel Nanoparticles Tunable in Size

    DOE PAGES

    Bocharova, Vera; Sharp, Danna; Jones, Aaron; ...

    2015-03-09

    Here, we report a novel approach to synthesize monodisperse hydrogel nanoparticles that are tunable in size. The distinctive feature of our approach is the use of a multicopper oxidase enzyme, laccase, as both a biocatalyst and template for nanoparticle growth. We utilize the ferroxidase activity of laccase to initiate localized production of iron(III) cations from the oxidation of iron(II) cations. We demonstrate that nanoparticles are formed in a dilute polymer solution of alginate as a result of cross-linking between alginate and enzymatically produced iron(III) cations. Exerting control over the enzymatic reaction allows for nanometer-scale tuning of the hydrogel nanoparticle radiimore » in the range of 30–100 nm. Moreover, the nanoparticles and their growth kinetics were characterized via dynamic light scattering, atomic force microscopy, and UV–vis spectroscopy. Our finding opens up a new avenue for the synthesis of tunable nanoscale hydrogel particles for biomedical applications.« less

  8. Functionalized Nanolipobubbles Embedded Within a Nanocomposite Hydrogel: a Molecular Bio-imaging and Biomechanical Analysis of the System.

    PubMed

    Mufamadi, Maluta S; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Modi, Girish; Naidoo, Dinesh; Iyuke, Sunny E; Pillay, Viness

    2016-05-17

    The purpose of this study was to explore the use of molecular bio-imaging systems and biomechanical dynamics to elucidate the fate of a nanocomposite hydrogel system prepared by merging FITC-labeled nanolipobubbles within a cross-linked hydrogel network. The nanocomposite hydrogel system was characterized by size distribution analysis and zeta potential as well as shears thinning behavior, elastic modulus (G'), viscous loss moduli (G"), TEM, and FTIR. In addition, molecular bio-imaging via Vevo ultrasound and Cell-viZio techniques evaluated the stability and distribution of the nanolipobubbles within the cross-linked hydrogel. FITC-labeled and functionalized nanolipobubbles had particle sizes between 135 and 158 nm (PdI = 0.129 and 0.190) and a zeta potential of -34 mV. TEM and ultrasound imaging revealed the uniformity and dimensional stability of the functionalized nanolipobubbles pre- and post-embedment into the cross-linked hydrogel. Biomechanical characterization of the hydrogel by shear thinning behavior was governed by the polymer concentration and the cross-linker, glutaraldehyde. Ultrasound analysis and Cell-viZio bio-imaging were highly suitable to visualize the fluorescent image-guided nanolipobubbles and their morphology post-embedment into the hydrogel to form the NanoComposite system. Since the nanocomposite is intended for targeted treatment of neurodegenerative disorders, the distribution of the functionalized nanolipobubbles into PC12 neuronal cells was also ascertained via confocal microscopy. Results demonstrated effective release and localization of the nanolipobubbles within PC12 neuronal cells. The molecular structure of the synthetic surface peptide remained intact for an extended period to ensure potency for targeted delivery from the hydrogel ex vivo. These findings provide further insight into the properties of nanocomposite hydrogels for specialized drug delivery.

  9. Photocrosslinkable Gelatin Hydrogel for Epidermal Tissue Engineering.

    PubMed

    Zhao, Xin; Lang, Qi; Yildirimer, Lara; Lin, Zhi Yuan; Cui, Wenguo; Annabi, Nasim; Ng, Kee Woei; Dokmeci, Mehmet R; Ghaemmaghami, Amir M; Khademhosseini, Ali

    2016-01-07

    Natural hydrogels are promising scaffolds to engineer epidermis. Currently, natural hydrogels used to support epidermal regeneration are mainly collagen- or gelatin-based, which mimic the natural dermal extracellular matrix but often suffer from insufficient and uncontrollable mechanical and degradation properties. In this study, a photocrosslinkable gelatin (i.e., gelatin methacrylamide (GelMA)) with tunable mechanical, degradation, and biological properties is used to engineer the epidermis for skin tissue engineering applications. The results reveal that the mechanical and degradation properties of the developed hydrogels can be readily modified by varying the hydrogel concentration, with elastic and compressive moduli tuned from a few kPa to a few hundred kPa, and the degradation times varied from a few days to several months. Additionally, hydrogels of all concentrations displayed excellent cell viability (>90%) with increasing cell adhesion and proliferation corresponding to increases in hydrogel concentrations. Furthermore, the hydrogels are found to support keratinocyte growth, differentiation, and stratification into a reconstructed multilayered epidermis with adequate barrier functions. The robust and tunable properties of GelMA hydrogels suggest that the keratinocyte laden hydrogels can be used as epidermal substitutes, wound dressings, or substrates to construct various in vitro skin models.

  10. Clinical and Antibiofilm Efficacy of Antimicrobial Hydrogels

    PubMed Central

    Finnegan, Simon; Percival, Steven L.

    2015-01-01

    Significance: Hydrogels have been shown to have a significant role to play in wound healing. Hydrogels are used to assist in the management of dry, sloughy, or necrotic wounds. However, recent scientific evidence has shown that biofilms delay wound healing and increase a wound propensity to infection. It is therefore essential that hydrogels incorporating antimicrobials demonstrate efficacy on biofilms. Consequently, it is the aim of this article to review the efficacy of hydrogels, incorporating antimicrobials, on wounds with specific reference to their efficacy on biofilms. Recent Advances: Technologies being developed for the management of wounds are rapidly expanding. In particularly next-generation hydrogels, incorporating copolymers, have been reported to enable the smart release of antimicrobials. This has led to the development of a more tailored patient-specific antimicrobial hydrogel therapy. Critical Issues: Evidence relating to the efficacy of hydrogels, incorporating antimicrobials, on biofilms within both the in vitro and in vivo environments is lacking. Future Direction: Studies that investigate the efficacy of antimicrobial hydrogel wound dressings on both in vivo and in vitro biofilms are important. However, there is a significant need for better and more reproducible in vivo biofilm models. Until this is possible, data generated from appropriate and representative in vitro models will help to assist researchers and clinicians in evaluating antimicrobial and antibiofilm hydrogel technology for the extrapolation of efficacy data relevant to biofilms present in the in vivo environment. PMID:26155382

  11. Clinical and Antibiofilm Efficacy of Antimicrobial Hydrogels.

    PubMed

    Finnegan, Simon; Percival, Steven L

    2015-07-01

    Significance: Hydrogels have been shown to have a significant role to play in wound healing. Hydrogels are used to assist in the management of dry, sloughy, or necrotic wounds. However, recent scientific evidence has shown that biofilms delay wound healing and increase a wound propensity to infection. It is therefore essential that hydrogels incorporating antimicrobials demonstrate efficacy on biofilms. Consequently, it is the aim of this article to review the efficacy of hydrogels, incorporating antimicrobials, on wounds with specific reference to their efficacy on biofilms. Recent Advances: Technologies being developed for the management of wounds are rapidly expanding. In particularly next-generation hydrogels, incorporating copolymers, have been reported to enable the smart release of antimicrobials. This has led to the development of a more tailored patient-specific antimicrobial hydrogel therapy. Critical Issues: Evidence relating to the efficacy of hydrogels, incorporating antimicrobials, on biofilms within both the in vitro and in vivo environments is lacking. Future Direction: Studies that investigate the efficacy of antimicrobial hydrogel wound dressings on both in vivo and in vitro biofilms are important. However, there is a significant need for better and more reproducible in vivo biofilm models. Until this is possible, data generated from appropriate and representative in vitro models will help to assist researchers and clinicians in evaluating antimicrobial and antibiofilm hydrogel technology for the extrapolation of efficacy data relevant to biofilms present in the in vivo environment.

  12. Isoelectric focusing in agarose gel for detection of oligoclonal bands in cerebrospinal and other biological fluids.

    PubMed

    Csako, Gyorgy

    2012-01-01

    Isoelectric focusing (IEF) coupled with immunodetection (immunofixation or immunoblotting) has become the leading technique for the detection and study of oligoclonal bands (OCBs) in cerebrospinal fluid (CSF) and also is increasingly used in other body fluids such as the tear and serum. Limited commercial availability of precast agarose IEF gels for research and a need for customization prompted reporting a detailed general protocol for the preparation and casting of agarose IEF gel along with sample, control, and isoelectric point marker preparation and carrying out the focusing itself for CSF OCBs. However, the method is readily adaptable to the use of other body fluid specimens and, possibly, research specimens such as culture fluids as well.

  13. Agarose gel structure using atomic force microscopy: gel concentration and ionic strength effects.

    PubMed

    Maaloum, M; Pernodet, N; Tinland, B

    1998-07-01

    Agarose gels have been studied by atomic force microscopy (AFM). The experiments were especially designed to work in aqueous conditions, allowing direct observation of the "unperturbed" gel without invasive treatment. AFM images clearly show strong dependence of pore diameter and its distribution on ionic strength of the solvent. As the ionic strength increases, the distribution becomes broader and the position of its maximum shifts toward higher values. The evolution of the distribution curves indicates that gels become more homogeneous with decreasing Tris-borate-EDTA (TBE) buffer concentration. An empirical law of the mean pore diameter as a function of the ionic strength is established. In agreement with our previous work we found that, for a given ionic strength, the pore diameter increases when the agarose concentration decreases and that the wide pore diameter distribution narrows as the gel concentration increases.

  14. Two-dimensional agarose gel electrophoresis for analysis of DNA replication.

    PubMed

    Villwock, Sandra K; Aparicio, Oscar M

    2014-01-01

    The initiation, elongation, and termination of DNA replication are each associated with distinct, nonlinear DNA structures that can be resolved and identified by two-dimensional (2D) agarose gel electrophoresis. This method involves: isolation of genomic DNA while preserving fragile replication structures, digestion of the DNA with a restriction enzyme, separation of DNA by size and shape through two distinct stages of agarose gel electrophoresis, and Southern blotting to probe for the specific sequence(s) of interest. The method has been most commonly used to determine the activity level of putative replication origin-containing sequences, and has also been used to analyze replication timing, fork progression, fork pausing, fork stalling and collapse, termination, and recombinational repair.

  15. Single-Step RNA Extraction from Different Hydrogel-Embedded Mesenchymal Stem Cells for Quantitative Reverse Transcription-Polymerase Chain Reaction Analysis.

    PubMed

    Köster, Natascha; Schmiermund, Alexandra; Grubelnig, Stefan; Leber, Jasmin; Ehlicke, Franziska; Czermak, Peter; Salzig, Denise

    2016-06-01

    For many tissue engineering applications, cells such as human mesenchymal stem cells (hMSCs) must be embedded in hydrogels. The analysis of embedded hMSCs requires RNA extraction, but common extraction procedures often produce low yields and/or poor quality RNA. We systematically investigated four homogenization methods combined with eight RNA extraction protocols for hMSCs embedded in three common hydrogel types (alginate, agarose, and gelatin). We found for all three hydrogel types that using liquid nitrogen or a rotor-stator produced low RNA yields, whereas using a microhomogenizer or enzymatic/chemical hydrogel digestion achieved better yields regardless of which extraction protocol was subsequently applied. The hot phenol extraction protocol generally achieved the highest A260 values (representing up to 40.8 μg RNA per 10(6) cells), but the cetyltrimethylammonium bromide (CTAB) method produced RNA of better quality, with A260/A280 and A260/A230 ratios and UV spectra similar to the pure RNA control. The RNA produced by this method was also suitable as a template for endpoint and quantitative reverse transcription-PCR (qRT-PCR), achieving low Ct values of ∼20. The prudent choice of hydrogel homogenization and RNA extraction methods can ensure the preparation of high-quality RNA that generates reliable endpoint and quantitative RT-PCR data. We therefore propose a universal method that is suitable for the extraction of RNA from cells embedded in all three hydrogel types commonly used for tissue engineering.

  16. Characterization of a heterogeneous chicken plasma protein, HEF, by analytical isotachophoresis in agarose gel.

    PubMed

    Nicolaisen, E M

    1985-02-22

    Chicken plasma contains proteins that associate with immunoglobulin. One of these proteins enhances the titre of haemagglutinating alloantibodies, and it was therefore named HEF, haemagglutination enhancing factor. A purified HEF preparation mixed with ampholytes splits into four bands in analytical agarose isotachophoresis. One of the HEF bands can be separated from two others with beta-alanine as discrete spacer. The separated HEF populations differ in molecular size and in their ability to enhance agglutination.

  17. Minimizing inhibition of PCR-STR typing using digital agarose droplet microfluidics.

    PubMed

    Geng, Tao; Mathies, Richard A

    2015-01-01

    The presence of PCR inhibitors in forensic and other biological samples reduces the amplification efficiency, sometimes resulting in complete PCR failure. Here we demonstrate a high-performance digital agarose droplet microfluidics technique for single-cell and single-molecule forensic short tandem repeat (STR) typing of samples contaminated with high concentrations of PCR inhibitors. In our multifaceted strategy, the mitigation of inhibitory effects is achieved by the efficient removal of inhibitors from the porous agarose microgel droplets carrying the DNA template through washing and by the significant dilution of targets and remaining inhibitors to the stochastic limit within the ultralow nL volume droplet reactors. Compared to conventional tube-based bulk PCR, our technique shows enhanced (20 ×, 10 ×, and 16 ×) tolerance of urea, tannic acid, and humic acid, respectively, in STR typing of GM09948 human lymphoid cells. STR profiling of single cells is not affected by small soluble molecules like urea and tannic acid because of their effective elimination from the agarose droplets; however, higher molecular weight humic acid still partially inhibits single-cell PCR when the concentration is higher than 200 ng/μL. Nevertheless, the full STR profile of 9948 male genomic DNA contaminated with 500 ng/μL humic acid was generated by pooling and amplifying beads carrying single-molecule 9948 DNA PCR products in a single secondary reaction. This superior performance suggests that our digital agarose droplet microfluidics technology is a promising approach for analyzing low-abundance DNA targets in the presence of inhibitors.

  18. Confirmation of soybean plastid rRNAs by formaldehyde denaturing agarose gel electrophoresis.

    PubMed

    Zhu, Y Q; Zheng, Y; Chen, H B; Huang, L Q

    2014-10-27

    Owing to their prokaryotic origin, plastid rRNAs are mainly 23s/16s/5s rRNAs. We present a novel plant RNA isolation method in this paper. Also, not only the eukaryotic 28s (26s, 25s)/18s rRNAs but the prokaryotic 26s/23s rRNAs as well were demonstrated in a single sample for the first time by formaldehyde denaturing agarose gel electrophoresis.

  19. Novel injectable, self-gelling hydrogel-microparticle composites for bone regeneration consisting of gellan gum and calcium and magnesium carbonate microparticles.

    PubMed

    Douglas, Timothy E L; Łapa, Agata; Reczyńska, Katarzyna; Krok-Borkowicz, Małgorzata; Pietryga, Krzysztof; Samal, Sangram Keshari; Declercq, Heidi A; Schaubroeck, David; Boone, Marijn; Van der Voort, Pascal; De Schamphelaere, Karel; Stevens, Christian V; Bliznuk, Vitaliy; Balcaen, Lieve; Parakhonskiy, Bogdan V; Vanhaecke, Frank; Cnudde, Veerle; Pamuła, Elżbieta; Skirtach, Andre G

    2016-11-21

    The suitability of hydrogel biomaterials for bone regeneration can be improved by incorporation of an inorganic phase in particle form, thus maintaining hydrogel injectability. In this study, carbonate microparticles containing different amounts of calcium (Ca) and magnesium (Mg) were added to solutions of the anionic polysaccharide gellan gum (GG) to crosslink GG by release of Ca(2+) and Mg(2+) from microparticles and thereby induce formation of hydrogel-microparticle composites. It was hypothesized that increasing Mg content of microparticles would promote GG hydrogel formation. The effect of Mg incorporation on cytocompatibility and cell growth was also studied. Microparticles were formed by mixing Ca(2+) and Mg(2+) and [Formula: see text] ions in varying concentrations. Microparticles were characterized physiochemically and subsequently mixed with GG solution to form hydrogel-microparticle composites. The elemental Ca:Mg ratio in the mineral formed was similar to the Ca:Mg ratio of the ions added. In the absence of Mg, vaterite was formed. At low Mg content, magnesian calcite was formed. Increasing the Mg content further caused formation of amorphous mineral. Microparticles of vaterite and magnesium calcite did not induce GG hydrogel formation, but addition of Mg-richer amorphous microparticles induced gelation within 20 min. Microparticles were dispersed homogeneously in hydrogels. MG-63 osteoblast-like cells were cultured in eluate from hydrogel-microparticle composites and on the composites themselves. All composites were cytocompatible. Cell growth was highest on composites containing particles with an equimolar Ca:Mg ratio. In summary, carbonate microparticles containing a sufficient amount of Mg induced GG hydrogel formation, resulting in injectable, cytocompatible hydrogel-microparticle composites.

  20. Control of the pore architecture in three-dimensional hydroxyapatite-reinforced hydrogel scaffolds

    PubMed Central

    Román, Jesús; Cabañas, María Victoria; Peña, Juan; Vallet-Regí, María

    2011-01-01

    Hydrogels (gellan or agarose) reinforced with nanocrystalline carbonated hydroxyapatite (nCHA) were prepared by the GELPOR3D technique. This simple method is characterized by compositional flexibility; it does not require expensive equipment, thermal treatment, or aggressive or toxic solvents, and yields a three-dimensional (3D) network of interconnected pores 300–900 μm in size. In addition, an interconnected porosity is generated, yielding a hierarchical porous architecture from the macro to the molecular scale. This porosity depends on both the drying/preservation technology (freeze drying or oven drying at 37 ○C) and on the content and microstructure of the reinforcing ceramic. For freeze-dried samples, the porosities were approximately 30, 66 and below 3% for pore sizes of 600–900 μm, 100–200 μm and 50–100 nm, respectively. The pore structure depends much on the ceramic content, so that higher contents lead to the disappearance of the characteristic honeycomb structure observed in low-ceramic scaffolds and to a lower fraction of the 100–200-μm-sized pores. The nature of the hydrogel did not affect the pore size distribution but was crucial for the behavior of the scaffolds in a hydrated medium: gellan-containing scaffolds showed a higher swelling degree owing to the presence of more hydrophilic groups. PMID:27877422

  1. Control of the pore architecture in three-dimensional hydroxyapatite-reinforced hydrogel scaffolds.

    PubMed

    Román, Jesús; Cabañas, María Victoria; Peña, Juan; Vallet-Regí, María

    2011-08-01

    Hydrogels (gellan or agarose) reinforced with nanocrystalline carbonated hydroxyapatite (nCHA) were prepared by the GELPOR3D technique. This simple method is characterized by compositional flexibility; it does not require expensive equipment, thermal treatment, or aggressive or toxic solvents, and yields a three-dimensional (3D) network of interconnected pores 300-900 μm in size. In addition, an interconnected porosity is generated, yielding a hierarchical porous architecture from the macro to the molecular scale. This porosity depends on both the drying/preservation technology (freeze drying or oven drying at 37 (○)C) and on the content and microstructure of the reinforcing ceramic. For freeze-dried samples, the porosities were approximately 30, 66 and below 3% for pore sizes of 600-900 μm, 100-200 μm and 50-100 nm, respectively. The pore structure depends much on the ceramic content, so that higher contents lead to the disappearance of the characteristic honeycomb structure observed in low-ceramic scaffolds and to a lower fraction of the 100-200-μm-sized pores. The nature of the hydrogel did not affect the pore size distribution but was crucial for the behavior of the scaffolds in a hydrated medium: gellan-containing scaffolds showed a higher swelling degree owing to the presence of more hydrophilic groups.

  2. Methods for determining agent concentration profiles in agarose gel during convection-enhanced delivery.

    PubMed

    Sindhwani, Nikhil; Ivanchenko, Oleksandr; Lueshen, Eric; Prem, Komal; Linninger, Andreas A

    2011-03-01

    Convection-enhanced delivery (CED) is a promising technique to deliver large molecular weight drugs to the human brain for treatment of Parkinson's, Alzheimer's, or brain tumors. Researchers have used agarose gels to study mechanisms of agent transport in soft tissues like brain due to its similar mechanical and transport properties. However, inexpensive quantitative techniques to precisely measure achieved agent distribution in agarose gel phantoms during CED are missing. Such precise measurements of concentration distribution are needed to optimize drug delivery. An optical experimental method to accurately quantify agent concentration in agarose is presented. A novel geometry correction algorithm is used to determine real concentrations from observable light intensities captured by a digital camera. We demonstrate the technique in dye infusion experiments that provide cylindrical and spherical distributions when infusing with porous membrane and conventional single-port catheters, respectively. This optical method incorporates important parameters, such as optimum camera exposure, captured camera intensity calibration, and use of collimated light source for maximum precision. We compare experimental results with numerical solutions to the convection diffusion equation. The solutions of convection-diffusion equations in the cylindrical and spherical domains were found to match the experimental data obtained by geometry correction algorithm.

  3. One-pot synthesis of fluorescent polysaccharides: adenine grafted agarose and carrageenan.

    PubMed

    Oza, Mihir D; Prasad, Kamalesh; Siddhanta, A K

    2012-08-01

    New fluorescent polysaccharides were synthesized by grafting the nucleobase adenine on to the backbones of agarose and κ-carrageenan, which were characterized by FT-IR, (13)C NMR, TGA, XRD, UV, and fluorescence properties. The synthesis involved a rapid water based potassium persulfate (KPS) initiated method under microwave irradiation. The emission spectra of adenine grafted agarose and κ-carrageenan were recorded in aqueous (5×10(-5) M) solution, exhibiting λ(em,max) 347 nm by excitation at 261 nm, affording ca. 30% and 40% enhanced emission intensities, respectively compared to that of pure adenine solution in the same concentration. Similar emission intensity was recorded in the pure adenine solution at its molar equivalent concentrations present in the 5×10(-5) M solution of the agarose and carrageenan grafted products, that is, 3.28×10(-5) M and 4.5×10(-5) M respectively. These fluorescent adenine grafted products may have potential utility in various sensor applications.

  4. Pellet pestle homogenization of agarose gel slices at 45 degrees C for deoxyribonucleic acid extraction.

    PubMed

    Kurien, B T; Kaufman, K M; Harley, J B; Scofield, R H

    2001-09-15

    A simple method for extracting DNA from agarose gel slices is described. The extraction is rapid and does not involve harsh chemicals or sophisticated equipment. The method involves homogenization of the excised gel slice (in Tris-EDTA buffer), containing the DNA fragment of interest, at 45 degrees C in a microcentrifuge tube with a Kontes pellet pestle for 1 min. The "homogenate" is then centrifuged for 30 s and the supernatant is saved. The "homogenized" agarose is extracted one more time and the supernatant obtained is combined with the previous supernatant. The DNA extracted using this method lent itself to restriction enzyme analysis, ligation, transformation, and expression of functional protein in bacteria. This method was found to be applicable with 0.8, 1.0, and 2.0% agarose gels. DNA fragments varying from 23 to 0.4 kb were extracted using this procedure and a yield ranging from 40 to 90% was obtained. The yield was higher for fragments 2.0 kb and higher (70-90%). This range of efficiency was maintained when the starting material was kept between 10 and 300 ng. The heat step was found to be critical since homogenization at room temperature failed to yield any DNA. Extracting DNA with our method elicited an increased yield (up to twofold) compared with that extracted with a commercial kit. Also, the number of transformants obtained using the DNA extracted with our method was at least twice that obtained using the DNA extracted with the commercial kit.

  5. Laser interferometric analysis of glucose and sucrose diffusion in agarose gel.

    PubMed

    Wąsik, Sławomir; Arabski, Michał; Dworecki, Kazimierz; Janoska, Joanna; Semaniak, Jacek; Szary, Karol; Slęzak, Andrzej

    2014-01-01

    The paper presents the investigation results of glucose and sucrose diffusion in agarose gel studied with laser interferometry method and the results of fluorescence analysis of the macroscopic gel structure. The diffusion kinetics of these substances released from aqueous solutions of a molar concentration of 0.05 M into the agarose solutions of concentrations of 0.5% and 3% in two gravitational configurations of measuring system was analysed. In the first configuration the solute diffused according, whereas in the second one - opposite to the gravitational force. The diffusion was analysed in the time period between 120 and 2400 s with a time interval of Δt = 120 s. We observed that the convective instabilities were damped well by the agarose gel, which gives the possibility of the interferometric studies of the diffusive transport for other substances in different gravitational configurations of the system. The time characteristics of glucose and sucrose fluxes in both configurations of the system and the gravitational polarisation coefficient values were obtained. The substantial differences in fluxes of glucose and sucrose diffused according and opposite to the gravitational force were observed. Additionally, we observed the differences between the diffusive fluxes of these substances in both configurations in dependence on the gel solution concentration (which is associated with gel porosity dependent on its concentration) and the kind of diffused substance.

  6. A rapid sandwich immunoassay for human fetuin A using agarose-3-aminopropyltriethoxysilane modified microtiter plate.

    PubMed

    Vashist, Sandeep Kumar; Schneider, E Marion; Luong, John H T

    2015-07-09

    A rapid sandwich immunoassay (IA) with enhanced signal response for human fetuin A (HFA) was developed by modifying the surface of a KOH-treated polystyrene microtiter plate (MTP) with agarose and 3-aminopropyltriethoxysilane (APTES). The agarose-APTES complex binds covalently to the hydroxyl moiety of the MTP plate to serve as a binding platform for bioconjugation of EDC-activated anti-HFA antibody (Ab) via carbodiimide coupling. The one-step kinetics-based sandwich enzyme-linked immunosorbent assay (ELISA) enabled the detection of HFA in 30 min with a limit of detection (LOD) and a linear range of 0.02 ng mL(-1) and 1-243 ng mL(-1), respectively. It detected HFA spiked in diluted human whole blood and serum, and HFA in ethylenediaminetetraacetic acid (EDTA)-plasma of patients with high precision similar to that of conventional ELISA. The anti-HFA Ab-bound agarose-functionalized MTPs retained their functional activity after 6 weeks of storage in 0.1 M PBS, pH 7.4 at 4 °C.

  7. Selective bacterial patterning using the submerged properties of microbeads on agarose gel.

    PubMed

    Park, Sung Jun; Bae, Hyeoni; Ko, Seong Young; Min, Jung-Joon; Park, Jong-Oh; Park, Sukho

    2013-10-01

    We proposed a new bacteria patterning method on the restricted region of microbeads, using the submerged property of polystyrene microbeads on various concentrations of agarose gel. Moreover, we fabricated a bacterial microrobot using attenuated Salmonella typhimurium through the new patterning methods. We controlled the submerged degree of polystyrene microbeads through the regulation of the hardness of the agarose gel. The polystyrene microbeads on agarose gel were transferred onto a poly-dimethylsiloxane (PDMS) surface for easy manipulation of the microbeads. Then, we treated the polystyrene microbeads on the PDMS surface with antibacterial adherent factors, such as O2 plasma and bovine serum albumin (BSA). The Salmonella typhimurium was attached to the entire surface of the untreated polystyrene microbeads, whereas Salmonella typhimurium were only attached to the restricted surface region of the treated polystyrene microbeads through the proposed patterning method. The bacteria-attached microbeads gain motility by the propulsion of the attached bacteria, and the selective-bacteria-attached microbeads showed enhanced motility. Compared with whole-bacteria-attached polystyrene microbeads (1.74 ± 1.62 μm/s), the selective bacteria-attached polystyrene microbeads, using O2 plasma and BSA, showed 9.18 ± 1.88 μm/s and 14.65 ± 8.66 μm/s faster moving velocities, respectively. Through the results, we expected that the proposed patterning methodology of microbeads could contribute to the development of biomedical bacterial microrobots.

  8. Xenotransplantation of islets enclosed in agarose microcapsule carrying soluble complement receptor 1.

    PubMed

    Luan, Nguyen Minh; Iwata, Hiroo

    2012-11-01

    Strong immunological reactions remain a major barrier to treating diabetic patients using xenogeneic islets. In a previous study, we developed a method for enclosing islets with agarose microbeads carrying soluble complement receptor 1 (sCR1-Mics), a potent complement inhibitor in both classical and alternative complement activation pathways. This is the follow-up in vivo study to evaluate the protective effect of these sCR1-Mics using a xenotransplantation model (rats to mice). ACI/NSIc rat islets enclosed in sCR1-Mics were transplanted into the intraperitoneal cavity of diabetic C57BL/6 mice without immunosuppression therapy. Transplantation of islets in plain agarose microbeads (Mics) was used as a reference. While islets enclosed in plain Mics were rapidly destroyed (graft survival in recipients of 1000 islets: 11.6±3.8 days), transplantation of islets in sCR1-Mics significantly prolonged graft survival (34.1±3.2 days). Moreover, intraperitoneal glucose tolerance tests revealed that islets in sCR1-Mics normalized blood glucose levels in a similar manner as islets in pancreas of normal mice. In conclusion, sCR1 immobilized onto agarose microbeads exerted some protective effect in xenogeneic islets resulting in prolonged graft survival.

  9. Response surface methodology-based optimisation of agarose gel electrophoresis for screening and electropherotyping of rotavirus.

    PubMed

    Mishra, Vikas; Nag, Vijaya Lakshmi; Tandon, Ritu; Awasthi, Shally

    2010-04-01

    Management of rotavirus diarrhoea cases and prevention of nosocomial infection require rapid diagnostic method at the patient care level. Diagnostic tests currently available are not routinely used due to economic or sensitivity/specificity constraints. Agarose-based sieving media and running conditions were modulated by using central composite design and response surface methodology for screening and electropherotyping of rotaviruses. The electrophoretic resolution of rotavirus genome was calculated from input parameters characterising the gel matrix structure and running conditions. Resolution of rotavirus genome was calculated by densitometric analysis of the gel. The parameters at critical values were able to resolve 11 segmented rotavirus genome. Better resolution and electropherotypic variation in 11 segmented double-stranded RNA genome of rotavirus was detected at 1.96% (w/v) agarose concentration, 0.073 mol l(-1) ionic strength of Tris base-boric acid-ethylenediamine tetraacetic acid buffer (1.4x) and 4.31 h of electrophoresis at 4.6 V cm(-1) electric field strength. Modified agarose gel electrophoresis can replace other methods as a simplified alternative for routine detection of rotavirus where it is not in practice.

  10. Capillary blotting of glycosaminoglycans on nitrocellulose membranes after agarose-gel electrophoresis separation.

    PubMed

    Volpi, Nicola; Maccari, Francesca

    2009-01-01

    A method for the blotting and immobilizing of several nonsulfated and sulfated complex polysaccharides on membranes made hydrophilic and positively charged by cationic detergent after their separation by conventional agarose gel electrophoresis is illustrated. This new approach to the study of glycosaminoglycans (GAGs) utilizes the capacity of agarose gel electrophoresis to separate single species of polysaccharides from mixtures and the membrane technology for further preparative and analytical uses.Nitrocellulose membranes are derivatized with the cationic detergent cetylpyridinium chloride and mixtures of GAGs are capillary blotted after their separation in agarose gel electrophoresis. Single purified species of variously sulfated polysaccharides are transferred on derivatized membranes with an efficiency of 100% and stained with alcian blue (irreversible staining) and toluidine blue (reversible staining). This enables a lower amount limit of detection of 0.1 microg. Nonsulfated polyanions, for example hyaluronic acid, may also be transferred to membranes with a limit of detection of approximately 0.1-0.5 microg after irreversible or reversible staining. The membranes may be stained with reversible staining and the same lanes are used for immunological detection or other applications.

  11. Homogeneous tosylation of agarose as an approach toward novel functional polysaccharide materials.

    PubMed

    Gericke, Martin; Heinze, Thomas

    2015-01-01

    The homogeneous tosylation of agarose was studied with respect to the effects of reaction parameters, such as reaction medium, time, and molar ratio, on the reaction course, the degree of substitution (DS) with tosyl/chloro deoxy groups, and the molecular structure. Tosyl agaroses (TOSA) with DS tosyl ≤ 1 .81 could be obtained in completely homogeneous reactions by using N,N-dimethylacetamide (DMA)/LiCl or 1,3-dimethyl-2-imidazolidinone (DMI) as solvents. The products were characterized by FT-IR and NMR spectroscopy and it was demonstrated that two types of substitution pattern can be achieved: (i) non-preferential substitution at position 6 of the 1 → 3-linked β-d-galactose unit (G-6) and position 2 of the 1 → 4-linked 3,6-anyhdro-α-L-galactose unit (LA-2) and (ii) regioselective tosylation at G-6, depending on whether the reaction is performed with or without LiCl. Finally, the nucleophilic displacement reaction of TOSA was studied using azide and ethylenediamine as representative nucleophiles. Novel deoxy-agarose derivatives were obtained that showed an interesting solubility behavior and will be used for creating functional polysaccharide materials.

  12. A detailed study of homogeneous agarose/hydroxyapatite nanocomposites for load-bearing bone tissue.

    PubMed

    Hu, Jingxiao; Zhu, Youjia; Tong, Hua; Shen, Xinyu; Chen, Li; Ran, Jiabing

    2016-01-01

    Agarose/hydroxyapatite (agar/HA) nanocomposites for load-bearing bone substitutes were successfully fabricated via a novel in situ precipitation method. Observation via SEM and TEM revealed that the spherical inorganic nanoparticles of approximately 50 nm were well dispersed in the organic matrix, and the crystallographic area combined closely with the amorphous area. The uniform dispersion of HA nanoparticles had prominent effect on improving the mechanical properties of the agar/HA nanocomposites (the highest elastic modulus: 1104.42 MPa; the highest compressive strength: 400.039 MPa), which proved to be potential load-bearing bone substitutes. The thermal stability of agarose and nanocomposites was also studied. The MG63 osteoblast-like cells on the composite disks displayed fusiform and polygonal morphology in the presence of HA, suggesting that the cell maturation was promoted. The results of cell proliferation and cell differentiation indicated that the cells cultured on the agar/HA composite disks significantly increased the alkaline phosphatase activity and calcium deposition. The structural role of agarose in the composite system was investigated to better understand the effect of biopolymer on structure and properties of the composites. The optimal properties were the result of a comprehensive synergy of the components.

  13. Chondroitin sulfate-derivatized agarose beads: a new system for studying cation binding to glycosaminoglycans

    SciTech Connect

    Hunter, G.K.

    1987-09-01

    Chondroitin sulfate (CS) has been covalently attached to aminoethyl-agarose beads in a carbodiimide-catalyzed reaction. In this process, an amide bond is formed between carboxylate groups on the glycosaminoglycan (GAG) and the primary amine groups of the beads. Under optimal conditions, up to 160 micrograms of CS is attached per milligram of beads. CS-agarose beads have been used to study Ca binding to GAGs. The beads are mixed with a solution containing CaCl/sub 2/ and /sup 45/Ca and allowed to sediment under unit gravity. An aliquot of supernatant is then removed and /sup 45/Ca activity is determined to quantitate remaining (free) Ca. Using this system, it was shown that CS binds approximately 0.7 Ca/disaccharide unit at saturation. Under the conditions used, the apparent association constant (KA) is approximately 14 mM. In principle, this derivatization protocol may be used to attach any proteoglycan or GAG (except keratan sulfate) to an insoluble support. CS-agarose beads provide a rapid, simple, and relatively artifact-free system for studying cation-GAG interactions.

  14. Aqueous phase catalytic conversion of agarose to 5-hydroxymethylfurfural by metal chlorides

    SciTech Connect

    Yan, Lishi; Laskar, Dhrubojyoti D.; Lee, Suh-Jane; Yang, Bin

    2013-12-14

    Abstract: 5-HMF is a key intermediate for producing chemicals and fuels that can substitute for today’s petroleum-derived feedstocks. A series of metal chlorides, including NaCl, CaCl2, MgCl2, ZnCl2, CuCl2, FeCl3, and CrCl3, were comparatively investigated to catalyze agarose degradation for production of 5-HMF at temperature 180 oC, 200 oC, and 220 oC for 30 min, with catalyst concentration of 0.5% (w/w), 1% (w/w) and 5% (w/w), and substrate concentration of 2% (w/w). Our results revealed that alkali metal chlorides and alkali earth metal chlorides such as NaCl, CaCl2 and MgCl2 gave better 5-HMF yield compared with transition metal chlorides including ZnCl2, CrCl3, CuCl2 and FeCl3. 1% (w/w) MgCl2 was the more favorable catalyst for 5-HMF production from agarose, and resulted in 40.7% 5-HMF yield but no levulinic acid or lactic acid at 200 oC, 35 min. The reaction pathways of agarose degradation catalyzed by MgCl2 were also discussed.

  15. Dynamic Hybrid Materials: Hydrogel Actuators and Catalytic Microsystems

    NASA Astrophysics Data System (ADS)

    Zarzar, Lauren Dell

    Dynamic materials which can sense changes in their surroundings and subsequently respond or adapt by autonomously altering their functionality, surface chemistry, transparency, color, wetting behavior, adhesiveness, shape, etc. are primed to be integral components of future "smart" technologies. However, such systems can be quite complex and often require intricate coordination between both chemical and mechanical inputs/outputs as well as the combination of multiple materials working cooperatively to achieve the proper functionality. It is critical to not only understand the fundamental behaviors of existing dynamic chemo-mechanical systems, but also to apply that knowledge and explore new avenues for design of novel materials platforms which could provide a basis for future adaptive technologies. Part 1 explores the use of environmentally-sensitive hydrogels, either alone or within arrays of high-aspect-ratio nano/microstructures, as chemo-mechanical actuators. Chapters 1 through 7 describe a bio-inspired approach to the design of hybrid actuating surfaces in which the volume-changing hydrogel acts as the "muscle" that reversibly actuates the microstructured "bone". In particular, the different actuation mechanisms arising from variations in how the hydrogel is integrated into the structure array, how chemical signals can be used to manipulate actuation parameters, and finally how such a system may be used for applications ranging from adaptive optics to manipulation of chemical reactions are described. Chapter 8 discusses the use of responsive hydrogel scaffolds as a means to mechanically compress cells and direct differentiation. Part II explores dynamic microsystems involving the integration of catalytic sites within intricately structured 3D microenvironments. Specifically, we explore a generalizable and straightforward route to fabricate microscale patterns of nanocrystalline platinum and palladium using multiphoton lithography. The catalytic, electrical

  16. Bundle Formation in Biomimetic Hydrogels.

    PubMed

    Jaspers, Maarten; Pape, A C H; Voets, Ilja K; Rowan, Alan E; Portale, Giuseppe; Kouwer, Paul H J

    2016-08-08

    Bundling of single polymer chains is a crucial process in the formation of biopolymer network gels that make up the extracellular matrix and the cytoskeleton. This bundled architecture leads to gels with distinctive properties, including a large-pore-size gel formation at very low concentrations and mechanical responsiveness through nonlinear mechanics, properties that are rarely observed in synthetic hydrogels. Using small-angle X-ray scattering (SAXS), we study the bundle formation and hydrogelation process of polyisocyanide gels, a synthetic material that uniquely mimics the structure and mechanics of biogels. We show how the structure of the material changes at the (thermally induced) gelation point and how factors such as concentration and polymer length determine the architecture, and with that, the mechanical properties. The correlation of the gel mechanics and the structural parameters obtained from SAXS experiments is essential in the design of future (synthetic) mimics of biopolymer networks.

  17. Enhanced skin delivery of aceclofenac via hydrogel-based solid lipid nanoparticles.

    PubMed

    Raj, Rakesh; Mongia, Pooja; Ram, Alpana; Jain, N K

    2016-09-01

    The aim of the present study was to develop solid lipid nanoparticles (SLN) and formulate a hydrogel for enhanced topical delivery of aceclofenac (ACF). The SLN were prepared by the ultrasonic emulsification method and optimized on the basis of stirring speed and lipid content. The optimized formulation was characterized for particle size (189 ± 9.2 nm), polydispersity index (PDI) (0.162 ± 0.02), zeta potential (-32.51 ± 0.12 mV), entrapment efficiency (86.51 ± 2.46%), surface morphology, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). In vivo performance of ACF-loaded SLN hydrogel showed prolonged inhibition of edema, as compared to that observed using plain ACF hydrogel, after 24 h. The results demonstrated that the ACF-SLN formulation for skin targeting could be a promising carrier for topical delivery of ACF.

  18. Controlled release of theophylline from poly(vinyl alcohol) hydrogels/porous silicon nanostructured systems

    NASA Astrophysics Data System (ADS)

    Cervantes-Rincón, N.; Medellín-Rodríguez, F. J.; Escobar-Barrios, V. A.; Palestino, G.

    2013-03-01

    In this research, hybrid hydrogels of poly (vinyl alcohol)/ porous silicon (PSi)/theophylline were synthesized by the freezing and thawing method. We evaluated the influence of the synthesis parameters of the poly (vinyl alcohol) (PVA) hydrogels in relation to their ability to swell and drug released. The parameters studied (using an experimental design developed in Minitab 16) were the polymer concentration, the freezing temperature and the number of freezing/thawing (f/t) cycles. Nanostructured porous silicon particles (NsPSi) and theophylline were added within the polymer matrix to increase the drug charge and the polymer mechanical strength. The hybrid hydrogels were characterized by Infrared Spectroscopy Fourier Transform (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC), drug delivery kinetics were engineered according to the desired drug release schedule.

  19. Fewer Bacteria Adhere to Softer Hydrogels

    PubMed Central

    Kolewe, Kristopher W.; Peyton, Shelly R.; Schiffman, Jessica D.

    2015-01-01

    Clinically, biofilm-associated infections commonly form on intravascular catheters and other hydrogel surfaces. The overuse of antibiotics to treat these infections has led to the spread of antibiotic resistance and underscores the importance of developing alternative strategies that delay the onset of biofilm formation. Previously, it has been reported that during surface contact, bacteria can detect surfaces through subtle changes in the function of their motors. However, how the stiffness of a polymer hydrogel influences the initial attachment of bacteria is unknown. Systematically, we investigated poly(ethylene glycol) dimethacrylate (PEGDMA) and agar hydrogels that were twenty times thicker than the cumulative size of bacterial cell appendages, as a function of Young’s moduli. Soft (44.05 – 308.5 kPa), intermediate (1495 – 2877 kPa), and stiff (5152 – 6489 kPa) hydrogels were synthesized. Escherichia coli and Staphylococcus aureus attachment onto the hydrogels was analyzed using confocal microscopy after 2 and 24 hr incubation periods. Independent of hydrogel chemistry and incubation time, E. coli and S. aureus attachment correlated positively to increasing hydrogel stiffness. For example, after a 24 hr incubation period, there were 52% and 82% less E. coli adhered to soft PEGDMA hydrogels, than to the intermediate and stiff PEGDMA hydrogels, respectively. A 62% and 79% reduction in the area coverage by the Gram-positive microbe S. aureus occurred after 24 hr incubation on the soft versus intermediate and stiff PEGDMA hydrogels. We suggest that hydrogel stiffness is an easily tunable variable that, potentially, could be used synergistically with traditional antimicrobial strategies to reduce early bacterial adhesion, and therefore the occurrence of biofilm-associated infections. PMID:26291308

  20. Polymersomes containing a hydrogel network for high stability and controlled release.

    PubMed

    Kim, Shin-Hyun; Kim, Jin Woong; Kim, Do-Hoon; Han, Sang-Hoon; Weitz, David A

    2013-01-14

    Capillary microfluidic devices are used to prepare monodisperse polymersomes consisting of a hydrogel core and a bilayer membrane of amphiphilic diblock-copolymers. To make polymersomes, water-in-oil-in-water double-emulsion drops are prepared as templates through single-step emulsification in a capillary microfluidic device. The amphiphile-laden middle oil phase of the double-emulsion drop dewets from the surface of the innermost water drop, which contains hydrogel prepolymers; this dewetting leads to the formation of a bilayer membrane. Subsequently, the oil phase completely separates from the innermost water drop, leaving a polymersome. Upon UV illumination of the polymersome, the prepolymers encapsulated within the interior are crosslinked, forming a hydrogel core. The hydrogel network within the polymersomes facilitates sustained release of the encapsulated materials and increases the stability of the polymersomes through the formation of a scaffold to support the bilayer. In addition, this approach provides a facile method to make monodisperse hydrogel particles directly dispersed in water.

  1. A Novel Nanosilver/Nanosilica Hydrogel for Bone Regeneration in Infected Bone Defects.

    PubMed

    Zhang, Shiwen; Guo, Yuchen; Dong, Yuliang; Wu, Yunshu; Cheng, Lei; Wang, Yongyue; Xing, Malcolm; Yuan, Quan

    2016-06-01

    Treating bone defects in the presence of infection is a formidable clinical challenge. The use of a biomaterial with the dual function of bone regeneration and infection control is a novel therapeutic approach to this problem. In this study, we fabricated an innovative, dual-function biocomposite hydrogel containing nanosilver and nanosilica (nAg/nSiO2) particles and evaluated its characteristics using FT-IR, SEM, swelling ratio, and stiffness assays. The in vitro antibacterial analysis showed that this nAg/nSiO2 hydrogel inhibited both Gram-positive and Gram-negative bacteria. In addition, this nontoxic material could promote osteogenic differentiation of rat bone marrow stromal cells (BMSCs). We then created infected bone defects in rat calvaria in order to evaluate the function of the hydrogel in vivo. The hydrogel demonstrated effective antibacterial ability while promoting bone regeneration in these defects. Our results indicate that this nAg/nSiO2 hydrogel has the potential to both control infection and to promote bone healing in contaminated defects.

  2. Investigation of pectin/starch hydrogel as a carrier for oral delivery of probiotic bacteria.

    PubMed

    Dafe, Alireza; Etemadi, Hossein; Dilmaghani, Azita; Mahdavinia, Gholam Reza

    2017-04-01

    The present study highlights the fabrication of novel food-grade hydrogel particles based on pectin and starch for probiotic colon delivery. Lactobacillus plantarum ATCC:13643 (L. plantarum) cells were encapsulated in pectin/starch hydrogels by extrusion method. Four batches were formulated with different ratios of starch/pectin solutions. Optical and scanning electron microscopy obviously showed the random distribution of L. plantarum throughout the hydrogel network. The viability of encapsulated cells in simulated gastric fluid (SGF) and bile salt solution was significantly higher when compared to nonencapsulated cells. Results demonstrated that encapsulated cells in pectin/starch hydrogels were resistant against adverse conditions of the gastro-intestinal tract and bile salt solution compared to non-encapsulated cells. After sequential exposure to simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) for 2h almost complete death of free cells was observed however the numbers of surviving cells were 5.15 and 6.67 Log CFU/g for pectin and pectin/starch hydrogel, respectively.

  3. Rapid Self-Integrating, Injectable Hydrogel for Tissue Complex Regeneration.

    PubMed

    Hou, Sen; Wang, Xuefei; Park, Sean; Jin, Xiaobing; Ma, Peter X

    2015-07-15

    A novel rapid self-integrating, injectable, and bioerodible hydrogel is developed for bone-cartilage tissue complex regeneration. The hydrogels are able to self-integrate to form various structures, as can be seen after dying some hydrogel disks pink with rodamine. This hydrogel is demonstrated to engineer cartilage-bone complex.

  4. Agarose and polyacrylamide gel electrophoresis methods for molecular mass analysis of 5- to 500-kDa hyaluronan.

    PubMed

    Bhilocha, Shardul; Amin, Ripal; Pandya, Monika; Yuan, Han; Tank, Mihir; LoBello, Jaclyn; Shytuhina, Anastasia; Wang, Wenlan; Wisniewski, Hans-Georg; de la Motte, Carol; Cowman, Mary K

    2011-10-01

    Agarose and polyacrylamide gel electrophoresis systems for the molecular mass-dependent separation of hyaluronan (HA) in the size range of approximately 5-500 kDa were investigated. For agarose-based systems, the suitability of different agarose types, agarose concentrations, and buffer systems was determined. Using chemoenzymatically synthesized HA standards of low polydispersity, the molecular mass range was determined for each gel composition over which the relationship between HA mobility and logarithm of the molecular mass was linear. Excellent linear calibration was obtained for HA molecular mass as low as approximately 9 kDa in agarose gels. For higher resolution separation, and for extension to molecular masses as low as approximately 5 kDa, gradient polyacrylamide gels were superior. Densitometric scanning of stained gels allowed analysis of the range of molecular masses present in a sample as well as calculation of weight-average and number-average values. The methods were validated for polydisperse HA samples with viscosity-average molecular masses of 112, 59, 37, and 22 kDa at sample loads of 0.5 μg (for polyacrylamide) to 2.5 μg (for agarose). Use of the methods for electrophoretic mobility shift assays was demonstrated for binding of the HA-binding region of aggrecan (recombinant human aggrecan G1-IGD-G2 domains) to a 150-kDa HA standard.

  5. Multi-walled carbon nanotube-impregnated agarose film microextraction of polycyclic aromatic hydrocarbons in green tea beverage.

    PubMed

    Loh, Saw Hong; Sanagi, Mohd Marsin; Wan Ibrahim, Wan Aini; Hasan, Mohamed Noor

    2013-03-15

    A new microextraction procedure termed multi-walled carbon nanotube-impregnated agarose film microextraction (MWCNT-AFME) has been developed. The method utilized multi-walled carbon nanotubes (MWCNTs) immobilized in agarose film to serve as adsorbent in solid phase microextraction (SPME). The film was prepared by mixing the MWCNTs in agarose solution and drying the mixture in oven. Extraction of selected polycyclic aromatic hydrocarbons was performed by inserting a needle through circular MWCNT-impregnated agarose films (5 mm diameter) and the assembly was dipped into an agitated sample solution prior to micro high performance liquid chromatography-ultraviolet analysis. Back extraction was then performed using ultrasonication of the films in 100 μL of solvent. The film was discarded after single use, thus avoiding any analyte carry-over effect. Due to the mesoporous nature of the agarose film, the MWCNTs were immobilized easily within the film and thus allowing for close contact between adsorbent and analytes. Under the optimized extraction conditions, the technique achieved trace LODs in the range of 0.1 to 50 ng L(-1) for the targeted analytes, namely fluoranthene, phenanthrene and benzo[a]pyrene. The method was successfully applied to the analysis of spiked green tea beverage samples with good relative recoveries in the range of 91.1 to 107.2%. The results supported the feasibility of agarose to serve as adsorbent holder in SPME which then minimizes the consumption of chemicals and disposal cost of organic wastes.

  6. Poly(vinylamine) microgel-dextran composite hydrogels: characterisation; properties and pH-triggered degradation.

    PubMed

    McCann, Judith; Behrendt, Jonathan M; Yan, Junfeng; Halacheva, Silvia; Saunders, Brian R

    2015-07-01

    The present study involves an investigation of the formation, characterisation and triggered-degradation of mixed dispersions involving cationic poly(vinylamine-co-bis(ethyl vinylamine) ether) (PVAM-BEVAME) microgel (MG) particles and partially oxidised dextran (Dexox). In this approach to colloidal hydrogel composite formation, imine bonds were formed by reaction between aldehyde groups of Dexox and the primary amine groups on the MG particles. The composite hydrogels contained MG particles that were externally cross-linked by Dexox to form an elastically effective network with high storage modulus (G') values and low tanδ (=G″/G', where G″ is the loss modulus) values. The G' values for the MG-Dexox gels increased exponentially with increasing mass ratio (MR) of Dexox to MG. Interestingly, the yield strains determined from rheology also increased with MR and yield strains of up to 130% were measured. Au nanoparticles of comparable size to the Dexox chains adsorbed to the surface of the MG particles, which suggests that the pore size of the MG particles may have been smaller than that of the Dexox coils. The MG-Dexox gels were also subjected to acidic conditions to demonstrate pH-triggered gel network breakdown via imine bond cleavage. We show that new PVAM MG/aldehyde mixtures studied here for the first time form ductile and versatile colloidal gels and our new method provides a route to increasing ductility of hydrogels containing MG particles.

  7. Design of Hydrogels for Biomedical Applications.

    PubMed

    Kamata, Hiroyuki; Li, Xiang; Chung, Ung-Il; Sakai, Takamasa

    2015-11-18

    Hydrogels are considered key tools for the design of biomaterials, such as wound dressings, drug reservoirs, and temporary scaffolds for cells. Despite their potential, conventional hydrogels have limited applicability under wet physiological conditions because they suffer from the uncontrollable temporal change in shape: swelling takes place immediately after the installation. Swollen hydrogels easily fail under mechanical stress. The morphological change may cause not only the slippage from the installation site but also local nerve compression. The design of hydrogels that can retain their original shape and mechanical properties in an aqueous environment is, therefore, of great importance. On the one hand, the controlled degradation of used hydrogels has to be realized in some biomedical applications. This Progress Report provides a brief overview of the recent progress in the development of hydrogels for biomedical applications. Practical approaches to control the swelling properties of hydrogels are discussed. The designs of hydrogels with controlled degradation properties as well as the theoretical models to predict the degradation behavior are also introduced. Moreover, current challenges and limitation toward biomedical applications are discussed, and future directions are offered.

  8. Soy-based Hydrogels for Biomedical Applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soy based hydrogels were prepared by ring-opening polymerization of epoxidized soybean oil, following hydrolysis of formed polymers. The hydrogels were evaluated loading and releasing water-soluble anticancer drug doxorubin (Dox). The results suggest that this new system offers a great potential t...

  9. Soy-Based Hydrogels for Biomedical Applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soy based hydrogels were prepared by ring-opening polymerization of epoxidized soybean oil, flowing hydrolysis of formed polymer. The hydrogels were evaluated loading and release water-soluble anticancer drug doxorubin (Dox). The results suggested that this new system may offer great potential to ...

  10. Highly Stretchable, Strain Sensing Hydrogel Optical Fibers.

    PubMed

    Guo, Jingjing; Liu, Xinyue; Jiang, Nan; Yetisen, Ali K; Yuk, Hyunwoo; Yang, Changxi; Khademhosseini, Ali; Zhao, Xuanhe; Yun, Seok-Hyun

    2016-12-01

    A core-clad fiber made of elastic, tough hydrogels is highly stretchable while guiding light. Fluorescent dyes are easily doped into the hydrogel fiber by diffusion. When stretched, the transmission spectrum of the fiber is altered, enabling the strain to be measured and also its location.

  11. Flexible hydrogel-based functional composite materials

    DOEpatents

    Song, Jie; Saiz, Eduardo; Bertozzi, Carolyn R; Tomasia, Antoni P

    2013-10-08

    A composite having a flexible hydrogel polymer formed by mixing an organic phase with an inorganic composition, the organic phase selected from the group consisting of a hydrogel monomer, a crosslinker, a radical initiator, and/or a solvent. A polymerization mixture is formed and polymerized into a desired shape and size.

  12. Investigating hydrogel dosimeter decomposition by chemical methods

    NASA Astrophysics Data System (ADS)

    Jordan, Kevin

    2015-01-01

    The chemical oxidative decomposition of leucocrystal violet micelle hydrogel dosimeters was investigated using the reaction of ferrous ions with hydrogen peroxide or sodium bicarbonate with hydrogen peroxide. The second reaction is more effective at dye decomposition in gelatin hydrogels. Additional chemical analysis is required to determine the decomposition products.

  13. Engineering a morphogenetically active hydrogel for bioprinting of bioartificial tissue derived from human osteoblast-like SaOS-2 cells.

    PubMed

    Neufurth, Meik; Wang, Xiaohong; Schröder, Heinz C; Feng, Qingling; Diehl-Seifert, Bärbel; Ziebart, Thomas; Steffen, Renate; Wang, Shunfeng; Müller, Werner E G

    2014-10-01

    Sodium alginate hydrogel, stabilized with gelatin, is a suitable, biologically inert matrix that can be used for encapsulating and 3D bioprinting of bone-related SaOS-2 cells. However, the cells, embedded in this matrix, remain in a non-proliferating state. Here we show that addition of an overlay onto the bioprinted alginate/gelatine/SaOS-2 cell scaffold, consisting of agarose and the calcium salt of polyphosphate [polyP·Ca(2+)-complex], resulted in a marked increase in cell proliferation. In the presence of 100 μm polyP·Ca(2+)-complex, the cells proliferate with a generation time of approximately 47-55 h. In addition, the hardness of the alginate/gelatin hydrogel substantially increases in the presence of the polymer. The reduced Young's modulus for the alginate/gelatin hydrogel is approximately 13-14 kPa, and this value drops to approximately 0.5 kPa after incubation of the cell containing scaffolds for 5 d. In the presence of 100 μm polyP·Ca(2+)-complex, the reduced Young's modulus increases to about 22 kPa. The hardness of the polyP·Ca(2+)-complex containing hydrogel remains essentially constant if cells are absent in the matrix, but it drops to 3.2 kPa after a 5 d incubation period in the presence of SaOS-2 cells, indicating that polyP·Ca(2+)-complex becomes metabolized, degraded, by the cells. The alginate/gelatine-agarose system with polyP·Ca(2+)-complex cause a significant increase in the mineralization of the cells. SEM analyses revealed that the morphology of the mineral nodules formed on the surface of the cells embedded in the alginate/gelatin hydrogel do not significantly differ from the nodules on cells growing in monolayer cultures. The newly developed technique, using cells encapsulated into an alginate/gelatin hydrogel and a secondary layer containing the morphogenetically active, growth promoting polymer polyP·Ca(2+)-complex opens new possibilities for the application of 3D bioprinting in bone tissue engineering.

  14. Development of cloud point extraction using pH-sensitive hydrogel for preconcentration and determination of malachite green.

    PubMed

    Bahram, Morteza; Keshvari, Foroogh; Najafi-Moghaddam, Peyman

    2011-08-15

    A novel and sensitive cloud point extraction procedure using pH-sensitive hydrogel was developed for preconcentration and spectrophotometric determination of trace amounts of malachite green (MG). In this extraction method, appropriate amounts of poly(styrene-alt-maleic acid), as a pH-sensitive hydrogel, and HCl were added respectively into the aqueous sample so a cloudy solution was formed. The cloudy phase consists of hydrogel particles distributed entirely into the aqueous phase. Organic or inorganic compounds having the potential to interact with polymer particles (chemical interaction or physical adsorption) could be extracted to cloudy phase. After centrifuging, these particles of hydrogel were sedimented in the bottom of sample tube. The sedimented hydrogel-rich phase was diluted with acetonitrile and its absorbance was measured at 617 nm (λ(max) of malachite green in hydrogel). Central composite design and response surface method were applied to design the experiments and optimize the experimental parameters such as, concentration of hydrogel and HCl, extraction time and salting out effect. Under the optimum conditions, the linear range was 1 × 10(-8)-5 × 10(-7)mol L(-1) malachite green with a correlation coefficient of 0.992. The limit of detection (S/N=3) was 4.1 × 10(-9) mol L(-1). Relative standard deviation (RSD) for 7 replicate determinations of 10(-7) mol L(-1) malachite green was 3.03%. In this work, the concentration factor of 20 was reached. Also the improvement factor of the proposed method was 23. The advantages of this method are simplicity of operation, rapidity and low cost.

  15. Agarose gels

    NASA Astrophysics Data System (ADS)

    2016-11-01

    Discovered in 17th-century Japan, agar is a jelly-like substance obtained by boiling algae, and it is widely used as a gelling agent for desserts in Japanese, Indian, Philippine and Vietnamese cuisine.

  16. Thin Hydrogel Films for Optical Biosensor Applications

    PubMed Central

    Mateescu, Anca; Wang, Yi; Dostalek, Jakub; Jonas, Ulrich

    2012-01-01

    Hydrogel materials consisting of water-swollen polymer networks exhibit a large number of specific properties highly attractive for a variety of optical biosensor applications. This properties profile embraces the aqueous swelling medium as the basis of biocompatibility, non-fouling behavior, and being not cell toxic, while providing high optical quality and transparency. The present review focuses on some of the most interesting aspects of surface-attached hydrogel films as active binding matrices in optical biosensors based on surface plasmon resonance and optical waveguide mode spectroscopy. In particular, the chemical nature, specific properties, and applications of such hydrogel surface architectures for highly sensitive affinity biosensors based on evanescent wave optics are discussed. The specific class of responsive hydrogel systems, which can change their physical state in response to externally applied stimuli, have found large interest as sophisticated materials that provide a complex behavior to hydrogel-based sensing devices. PMID:24957962

  17. Hybrid hydrogels produced by ionizing radiation technique

    NASA Astrophysics Data System (ADS)

    Oliveira, M. J. A.; Amato, V. S.; Lugão, A. B.; Parra, D. F.

    2012-09-01

    The interest in biocompatible hydrogels with particular properties has increased considerably in recent years due to their versatile applications in biomedicine, biotechnology, pharmacy, agriculture and controlled release of drugs. The use of hydrogels matrices for particular drug-release applications has been investigated with the synthesis of modified polymeric hydrogel of PVAl and 0.5, 1.0, 1.5% nano-clay. They were processed using gamma radiation from Cobalt-60 source at 25 kGy dose. The characterization of the hydrogels was conducted and toxicity was evaluated. The dried hydrogel was analyzed for thermogravimetry analysis (TGA), infrared spectroscopy (FTIR) and swelling in solutions of different pH. The membranes have no toxicity. The nano-clay influences directly the equilibrium swelling.

  18. Polymer-induced compression of biological hydrogels

    NASA Astrophysics Data System (ADS)

    Datta, Sujit; Preska Steinberg, Asher; Ismagilov, Rustem

    Hydrogels - such as mucus, blood clots, and the extracellular matrix - provide critical functions in biological systems. However, little is known about how their structure is influenced by many of the polymeric materials they come into contact with regularly. Here, we focus on one critically important biological hydrogel: colonic mucus. While several biological processes are thought to potentially regulate the mucus hydrogel structure, the polymeric composition of the gut environment has been ignored. We use Flory-Huggins solution theory to characterize polymer-mucus interactions. We find that gut polymers, including those small enough to penetrate the mucus hydrogel, can in fact alter mucus structure, changing its equilibrium degree of swelling and forcing it to compress. The extent of compression increases with increasing polymer concentration and size. We use experiments on mice to verify these predictions with common dietary and therapeutic gut polymers. Our results provide a foundation for investigating similar, previously overlooked, polymer-induced effects in other biological hydrogels.

  19. Elastic, Conductive, Polymeric Hydrogels and Sponges

    PubMed Central

    Lu, Yun; He, Weina; Cao, Tai; Guo, Haitao; Zhang, Yongyi; Li, Qingwen; Shao, Ziqiang; Cui, Yulin; Zhang, Xuetong

    2014-01-01

    As a result of inherent rigidity of the conjugated macromolecular chains resulted from the delocalized π-electron system along the polymer backbone, it has been a huge challenge to make conducting polymer hydrogels elastic by far. Herein elastic and conductive polypyrrole hydrogels with only conducting polymer as the continuous phase have been simply synthesized in the indispensable conditions of 1) mixed solvent, 2) deficient oxidant, and 3) monthly secondary growth. The elastic mechanism and oxidative polymerization mechanism on the resulting PPy hydrogels have been discussed. The resulting hydrogels show some novel properties, e.g., shape memory elasticity, fast functionalization with various guest objects, and fast removal of organic infectants from aqueous solutions, all of which cannot be observed from traditional non-elastic conducting polymer counterparts. What's more, light-weight, elastic, and conductive organic sponges with excellent stress-sensing behavior have been successfully achieved via using the resulting polypyrrole hydrogels as precursors. PMID:25052015

  20. Hydrogels made from chitosan and silver nitrate.

    PubMed

    Kozicki, Marek; Kołodziejczyk, Marek; Szynkowska, Małgorzata; Pawlaczyk, Aleksandra; Leśniewska, Ewa; Matusiak, Aleksandra; Adamus, Agnieszka; Karolczak, Aleksandra

    2016-04-20

    This work describes a gelation of chitosan solution with silver nitrate. Above the critical concentration of chitosan (c*), continuous hydrogels of chitosan-silver can be formed. At lower concentrations, the formation of nano- and micro-hydrogels is discussed. The sol-gel analysis was performed to characterise the hydrogels' swelling properties. Moreover, the following were employed: (i) mechanical testing of hydrogels, (ii) inductively coupled plasma-optical emission spectroscopy (ICP-OES) for the measurement of silver concentration, (iii) scanning electron microscopy (SEM) to examine the morphology of products obtained, and (iv) dynamic light scattering (DLS) and UV-vis spectrophotometry to examine products formed at low concentration of chitosan (chydrogels were used for modification of cotton fabric in order to give it antimicrobial properties. The products obtained acted against Escherichia coli and Bacillus subtilis apart from the chitosan used that showed no such activity.

  1. Preparation and properties of regenerated cellulose hydrogels

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Xie, F.; Li, H.; Li, W.; Li, W. J.; Li, Y. W.

    2017-02-01

    The regenerated cellulose (RCE) hydrogels were successfully prepared via an easy and green environmental method in N-methylmorpholine-N-oxide (NMMO) aqueous solution. The effect of cellulose content on the thermostability properties, swelling behavior and retention rate of hydrogels was investigated. The thermostability of RCE hydrogels was slightly enhanced with the addition of 8 wt% cellulose, the highest decomposition temperature rose from 335 °C to 352 °C, and the least heat loss is about 75.60%. The equilibrium swelling ratio increases from 394.12% for 3% cellulose hydrogels to 619.46% for 8% cellulose hydrogels. The retention ratio increases from 1.13% to 28.46%.

  2. Simple approach to reinforce hydrogels with cellulose nanocrystals

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Han, Chun-Rui; Xu, Feng; Sun, Run-Cang

    2014-05-01

    The physical crosslinking of colloidal nanoparticles via dynamic and directional non-covalent interactions has led to significant advances in composite hydrogels. In this paper, we report a simple approach to fabricate tough, stretchable and hysteretic isotropic nanocomposite hydrogels, where rod-like cellulose nanocrystals (CNCs) are encapsulated by flexible polymer chains of poly(N,N-dimethylacrylamide) (PDMA). The CNC-PDMA colloidal clusters build a homogeneously cross-linked network and lead to significant reinforcing effect of the composites. Hierarchically structured CNC-PDMA clusters, from isolated particles to an interpenetrated network, are observed by transmission electron microscopy measurements. Dynamic shear oscillation measurements are applied to demystify the differences in network rheological behaviors, which were compared with network behaviors of chemically cross-linked PDMA counterparts. Tensile tests indicate that the hybrid hydrogels possess higher mechanical properties and a more efficient energy dissipation mechanism. In particular, with only 0.8 wt% of CNC loading, a 4.8-fold increase in Young's modulus, 9.2-fold increase in tensile strength, and 5.8-fold increase in fracture strain are achieved, which is ascribed to a combination of CNC reinforcement in the soft matrix and CNC-PDMA colloidal cluster conformational rearrangement under stretching. Physical interactions within networks serve as reversible sacrificial bonds that dissociate upon deformation, exhibiting large hysteresis as an energy dissipation mechanism via cluster mobility. This result contrasts with the case of chemically cross-linked PDMA counterparts where the stress relaxation is slow due to the permanent cross-links and low resistance against crack propagation within the covalent network.The physical crosslinking of colloidal nanoparticles via dynamic and directional non-covalent interactions has led to significant advances in composite hydrogels. In this paper, we report

  3. Novel neonicotinoid-agarose affinity column for Drosophila and Musca nicotinic acetylcholine receptors.

    PubMed

    Tomizawa, M; Latli, B; Casida, J E

    1996-10-01

    Neonicotinoids such as the insecticide imidacloprid (IMI) act as agonists at the insect nicotinic acetylcholine receptor (nAChR). Head membranes of Drosophila melanogaster and Musca domestica have a single high-affinity binding site for [3H]IMI with KD values of 1-2 nM and Bmax values of 560-850 fmol/mg of protein. Locusta and Periplaneta nAChRs isolated with an alpha-bungarotoxin (alpha-BGT)-agarose affinity column are known to be alpha-subunit homooligomers. This study uses 1-[N-(6-chloro-3-pyridylmethyl)-N-ethyl]amino-1-amino-2-nitroethene++ + (which inhibits [3H]IMI binding to Drosophila and Musca head membranes at 2-3 nM) to develop a neonicotinoid-agarose affinity column. The procedure-introduction of Triton-solubilized Drosophila or Musca head membranes into this neonicotinoid-based column, elution with IMI, and analysis by lithium dodecyl sulfate-polyacrylamicle gel electrophoresis-gives only three proteins (69, 66, and 61 kDa) tentatively assigned as putative subunits of the nAChR; the same three proteins are obtained with Musca using the alpha-BGT-agarose affinity column. Photoaffinity labeling of the Drosophila and Musca putative subunits from the neonicotinoid column with 125I-alpha-BGT-4-azidosalicylic acid gives a labeled derivative of 66-69 kDa. The yield is 2-5 micrograms of receptor protein from 1 g of Drosophila or Musca heads. Neonicotinoid affinity chromatography to isolate native Drosophila and Musca receptors will facilitate studies on the structure and function of insect nAChRs.

  4. Acoustic transfer of protein crystals from agarose pedestals to micromeshes for high-throughput screening.

    PubMed

    Cuttitta, Christina M; Ericson, Daniel L; Scalia, Alexander; Roessler, Christian G; Teplitsky, Ella; Joshi, Karan; Campos, Olven; Agarwal, Rakhi; Allaire, Marc; Orville, Allen M; Sweet, Robert M; Soares, Alexei S

    2015-01-01

    Acoustic droplet ejection (ADE) is an emerging technology with broad applications in serial crystallography such as growing, improving and manipulating protein crystals. One application of this technology is to gently transfer crystals onto MiTeGen micromeshes with minimal solvent. Once mounted on a micromesh, each crystal can be combined with different chemicals such as crystal-improving additives or a fragment library. Acoustic crystal mounting is fast (2.33 transfers s(-1)) and all transfers occur in a sealed environment that is in vapor equilibrium with the mother liquor. Here, a system is presented to retain crystals near the ejection point and away from the inaccessible dead volume at the bottom of the well by placing the crystals on a concave agarose pedestal (CAP) with the same chemical composition as the crystal mother liquor. The bowl-shaped CAP is impenetrable to crystals. Consequently, gravity will gently move the crystals into the optimal location for acoustic ejection. It is demonstrated that an agarose pedestal of this type is compatible with most commercially available crystallization conditions and that protein crystals are readily transferred from the agarose pedestal onto micromeshes with no loss in diffraction quality. It is also shown that crystals can be grown directly on CAPs, which avoids the need to transfer the crystals from the hanging drop to a CAP. This technology has been used to combine thermolysin and lysozyme crystals with an assortment of anomalously scattering heavy atoms. The results point towards a fast nanolitre method for crystal mounting and high-throughput screening.

  5. Acoustic transfer of protein crystals from agarose pedestals to micromeshes for high-throughput screening

    SciTech Connect

    Cuttitta, Christina M.; Ericson, Daniel L.; Scalia, Alexander; Roessler, Christian G.; Teplitsky, Ella; Joshi, Karan; Campos, Olven; Agarwal, Rakhi; Allaire, Marc; Orville, Allen M.; Sweet, Robert M.; Soares, Alexei S.

    2015-01-01

    An acoustic high-throughput screening method is described for harvesting protein crystals and combining the protein crystals with chemicals such as a fragment library. Acoustic droplet ejection (ADE) is an emerging technology with broad applications in serial crystallography such as growing, improving and manipulating protein crystals. One application of this technology is to gently transfer crystals onto MiTeGen micromeshes with minimal solvent. Once mounted on a micromesh, each crystal can be combined with different chemicals such as crystal-improving additives or a fragment library. Acoustic crystal mounting is fast (2.33 transfers s{sup −1}) and all transfers occur in a sealed environment that is in vapor equilibrium with the mother liquor. Here, a system is presented to retain crystals near the ejection point and away from the inaccessible dead volume at the bottom of the well by placing the crystals on a concave agarose pedestal (CAP) with the same chemical composition as the crystal mother liquor. The bowl-shaped CAP is impenetrable to crystals. Consequently, gravity will gently move the crystals into the optimal location for acoustic ejection. It is demonstrated that an agarose pedestal of this type is compatible with most commercially available crystallization conditions and that protein crystals are readily transferred from the agarose pedestal onto micromeshes with no loss in diffraction quality. It is also shown that crystals can be grown directly on CAPs, which avoids the need to transfer the crystals from the hanging drop to a CAP. This technology has been used to combine thermolysin and lysozyme crystals with an assortment of anomalously scattering heavy atoms. The results point towards a fast nanolitre method for crystal mounting and high-throughput screening.

  6. Acoustic transfer of protein crystals from agarose pedestals to micromeshes for high-throughput screening

    DOE PAGES

    Cuttitta, Christina M.; Ericson, Daniel L.; Scalia, Alexander; ...

    2014-06-01

    Acoustic droplet ejection (ADE) is an emerging technology with broad applications in serial crystallography such as growing, improving and manipulating protein crystals. One application of this technology is to gently transfer crystals onto MiTeGen micromeshes with minimal solvent. Once mounted on a micromesh, each crystal can be combined with different chemicals such as crystal-improving additives or a fragment library. Acoustic crystal mounting is fast (2.33 transfers s-1) and all transfers occur in a sealed environment that is in vapor equilibrium with the mother liquor. Here, a system is presented to retain crystals near the ejection point and away from themore » inaccessible dead volume at the bottom of the well by placing the crystals on a concave agarose pedestal (CAP) with the same chemical composition as the crystal mother liquor. The bowl-shaped CAP is impenetrable to crystals. Consequently, gravity will gently move the crystals into the optimal location for acoustic ejection. It is demonstrated that an agarose pedestal of this type is compatible with most commercially available crystallization conditions and that protein crystals are readily transferred from the agarose pedestal onto micromeshes with no loss in diffraction quality. It is also shown that crystals can be grown directly on CAPs, which avoids the need to transfer the crystals from the hanging drop to a CAP. This technology has been used to combine thermolysin and lysozyme crystals with an assortment of anomalously scattering heavy atoms. The results point towards a fast nanolitre method for crystal mounting and high-throughput screening.« less

  7. Rheological characterization of human fibrin and fibrin-agarose oral mucosa substitutes generated by tissue engineering.

    PubMed

    Rodríguez, I A; López-López, M T; Oliveira, A C X; Sánchez-Quevedo, M C; Campos, A; Alaminos, M; Durán, J D G

    2012-08-01

    In regenerative medicine, the generation of biocompatible substitutes of tissues by in vitro tissue engineering must fulfil certain requirements. In the case of human oral mucosa, the rheological properties of tissues deserve special attention because of their influence in the acoustics and biomechanics of voice production. This work is devoted to the rheological characterization of substitutes of the connective tissue of the human oral mucosa. Two substitutes, composed of fibrin and fibrin-agarose, were prepared in cell culture for periods in the range 1-21 days. The time evolution of the rheological properties of both substitutes was studied by two different experimental procedures: steady-state and oscillatory measurements. The former allows the plastic behaviour of the substitutes to be characterized by estimating their yield stress; the latter is employed to quantify their viscoelastic responses by obtaining the elastic (G') and viscous (G'') moduli. The results demonstrate that both substitutes are characterized by a predominant elastic response, in which G' (order 100 Pa) is roughly one order of magnitude larger than G'' (order 10 Pa). But the most relevant insight is the stability, throughout the 21 days of culture time, of the rheological quantities in the case of fibrin-agarose, whereas the fibrin substitute shows a significant hardening. This result provides evidence that the addition to fibrin of a small amount of agarose allows the rheological stability of the oral mucosa substitute to be maintained. This feature, together with its viscoelastic similitude with native tissues, makes this biomaterial appropriate for potential use as a scaffold in regenerative therapies of human oral mucosa.

  8. Acoustic transfer of protein crystals from agarose pedestals to micromeshes for high-throughput screening

    SciTech Connect

    Cuttitta, Christina M.; Ericson, Daniel L.; Scalia, Alexander; Roessler, Christian G.; Teplitsky, Ella; Joshi, Karan; Campos, Olven; Agarwal, Rakhi; Allaire, Marc; Orville, Allen M.; Sweet, Robert M.; Soares, Alexei S.

    2014-06-01

    Acoustic droplet ejection (ADE) is an emerging technology with broad applications in serial crystallography such as growing, improving and manipulating protein crystals. One application of this technology is to gently transfer crystals onto MiTeGen micromeshes with minimal solvent. Once mounted on a micromesh, each crystal can be combined with different chemicals such as crystal-improving additives or a fragment library. Acoustic crystal mounting is fast (2.33 transfers s-1) and all transfers occur in a sealed environment that is in vapor equilibrium with the mother liquor. Here, a system is presented to retain crystals near the ejection point and away from the inaccessible dead volume at the bottom of the well by placing the crystals on a concave agarose pedestal (CAP) with the same chemical composition as the crystal mother liquor. The bowl-shaped CAP is impenetrable to crystals. Consequently, gravity will gently move the crystals into the optimal location for acoustic ejection. It is demonstrated that an agarose pedestal of this type is compatible with most commercially available crystallization conditions and that protein crystals are readily transferred from the agarose pedestal onto micromeshes with no loss in diffraction quality. It is also shown that crystals can be grown directly on CAPs, which avoids the need to transfer the crystals from the hanging drop to a CAP. This technology has been used to combine thermolysin and lysozyme crystals with an assortment of anomalously scattering heavy atoms. The results point towards a fast nanolitre method for crystal mounting and high-throughput screening.

  9. Subpopulations of liver coated vesicles resolved by preparative agarose gel electrophoresis

    SciTech Connect

    Kedersha, N.L.; Hill, D.F.; Kronquist, K.E.; Rome, L.H.

    1986-01-01

    Rat liver clathrin coated vesicles (CVs) were separated into several distinct subpopulations using non-sieving concentrations of agarose, which allowed the separation of species differing primarily in surface charge. Using preparative agarose electrophoresis, the CVs were recovered and analyzed for differences in morphology, coat protein composition, and stripped vesicle protein composition. Coat proteins from difference populations appeared identical on SDS PAGE, and triskelions stripped from the different populations showed the same mobility on the agarose gel, suggesting that the mobility differences observed in intact CVs were due to differences in the surface charge of underlying vesicles rather than to variations in their clathrin coats. Stripped CVs exhibited considerable heterogeneity when analyzed by Western blotting: the fast-migrating population was enriched in the mannose 6-phosphate receptor, secretory acetyl-choline esterase, and an M/sub r/ 195,000 glycoprotein. The slow-migrating population of CVs was enriched in the asialoglycoprotein receptor, and it appeared to contain all detectable concanavalin A-binding polypeptides as well as the bulk of detectable WGA-binding proteins. When CVs were prepared from /sup 125/I-asialoorosomucoid-perfused rat liver, ligand was found in the slow-migrating CVs, suggesting that these were endocytic in origin. Morphological differences were also observed: the fast-migrating population was enriched in smaller CVs, whereas the slow-migrating population exhibited an enrichment in larger CVs. As liver consists largely of hepatocytes, these subpopulations appear to originate from the same cell type and probably represent CVs of different intracellular origin and destination.

  10. Ultrathin, freestanding, stimuli-responsive, porous membranes from polymer hydrogel-brushes

    NASA Astrophysics Data System (ADS)

    Kang, Chengjun; Ramakrishna, Shivaprakash N.; Nelson, Adrienne; Cremmel, Clement V. M.; Vom Stein, Helena; Spencer, Nicholas D.; Isa, Lucio; Benetti, Edmondo M.

    2015-07-01

    The fabrication of freestanding, sub-100 nm-thick, pH-responsive hydrogel membranes with controlled nano-morphology, based on modified poly(hydroxyethyl methacrylate) (PHEMA) is presented. Polymer hydrogel-brush films were first synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequently detached from silicon substrates by UV-induced photo-cleavage of a specially designed linker within the initiator groups. The detachment was also assisted by pH-induced osmotic forces generated within the films in the swollen state. The mechanical properties and morphology of the freestanding films were studied by atomic force microscopy (AFM). Inclusion of nanopores of controlled diameter was accomplished by performing SI-ATRP from initiator-coated surfaces that had previously been patterned with polystyrene nanoparticles. Assembly parameters and particle sizes could be varied, in order to fabricate nanoporous hydrogel-brush membranes with tunable pore coverage and characteristics. Additionally, due to the presence of weak polyacid functions within the hydrogel, the membranes exhibited pH-dependent thickness in water and reversible opening/closing of the pores.The fabrication of freestanding, sub-100 nm-thick, pH-responsive hydrogel membranes with controlled nano-morphology, based on modified poly(hydroxyethyl methacrylate) (PHEMA) is presented. Polymer hydrogel-brush films were first synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequently detached from silicon substrates by UV-induced photo-cleavage of a specially designed linker within the initiator groups. The detachment was also assisted by pH-induced osmotic forces generated within the films in the swollen state. The mechanical properties and morphology of the freestanding films were studied by atomic force microscopy (AFM). Inclusion of nanopores of controlled diameter was accomplished by performing SI-ATRP from initiator-coated surfaces that had

  11. Alginate Hydrogel: A Shapeable and Versatile Platform for in Situ Preparation of Metal-Organic Framework-Polymer Composites.

    PubMed

    Zhu, He; Zhang, Qi; Zhu, Shiping

    2016-07-13

    This work reports a novel in situ growth approach for incorporating metal-organic framework (MOF) materials into an alginate substrate, which overcomes the challenges of processing MOF particles into specially shaped structures for real industrial applications. The MOF-alginate composites are prepared through the post-treatment of a metal ion cross-linked alginate hydrogel with a MOF ligand solution. MOF particles are well distributed and embedded in and on the surface of the composites. The macroscopic shape of the composite can be designed by controlling the shape of the corresponding hydrogel; thus MOF-alginate beads, fibers, and membranes are obtained. In addition, four different MOF-alginate composites, including HKUST-1-, ZIF-8-, MIL-100(Fe)-, and ZIF-67-alginate, were successfully prepared using different metal ion cross-linked alginate hydrogels. The mechanism of formation is revealed, and the composite is demonstrated to be an effective absorbent for water purification.

  12. Quantitation of pyrimidine dimer contents of nonradioactive deoxyribonucleic acid by electrophoresis in alkaline agarose gels

    SciTech Connect

    Sutherland, B.M.; Shih, A.G.

    1983-02-15

    We have developed a method of quantitating the pyrimidine dimer content of nonradioactive DNAs. DNA samples are treated with the UV-endonuclease from Micrococcus luteus and then separated according to molecular weight by electrophoresis on alkaline agarose gels. From their migration relative to known molecular weight standards, their median molecular weight and thus the number of dimers per DNA molecule in each sample can be calculated. Results of action spectra for dimer formation in T7 bacteriophage measured by this method agree well with action spectra for T7 killing. In addition, the method gives dimer yields in good agreement with those obtained by others using alkaline sucrose gradient sedimentation.

  13. Plasmid DNA replication and topology as visualized by two-dimensional agarose gel electrophoresis.

    PubMed

    Schvartzman, J B; Martínez-Robles, M L; Hernández, P; Krimer, D B

    2010-01-01

    During the last 20 years, two-dimensional agarose gel electrophoresis combined with other techniques such as Polymerase Chain Reaction, helicase assay and electron microscopy, helped to characterize plasmid DNA replication and topology. Here we describe some of the most important findings that were made using this method including the characterization of uni-directional replication, replication origin interference, DNA breakage at the forks, replication fork blockage, replication knotting, replication fork reversal, the interplay of supercoiling and catenation and other changes in DNA topology that take place as replication progresses.

  14. Plasmid DNA topology assayed by two-dimensional agarose gel electrophoresis.

    PubMed

    Schvartzman, Jorge B; Martínez-Robles, María-Luisa; Hernández, Pablo; Krimer, Dora B

    2013-01-01

    Two-dimensional (2D) agarose gel electrophoresis is nowadays one of the best methods available to analyze DNA molecules with different masses and shapes. The possibility to use nicking enzymes and intercalating agents to change the twist of DNA during only one or in both runs, improves the capacity of 2D gels to discern molecules that apparently may look alike. Here we present protocols where 2D gels are used to understand the structure of DNA molecules and its dynamics in living cells. This knowledge is essential to comprehend how DNA topology affects and is affected by all the essential functions that DNA is involved in: replication, transcription, repair and recombination.

  15. Thermosensitive and Mucoadhesive Pluronic-Hydroxypropylmethylcellulose Hydrogel Containing the Mini-CD4 M48U1 Is a Promising Efficient Barrier against HIV Diffusion through Macaque Cervicovaginal Mucus

    PubMed Central

    Aka-Any-Grah, Armelle; Dereuddre-Bosquet, Nathalie; Martin, Loïc; Lievin-Le-Moal, Vanessa; Le Grand, Roger; Nicolas, Valérie; Gibellini, Davide; Lembo, David; Poüs, Christian; Koffi, Armand; Ponchel, Gilles

    2015-01-01

    To be efficient, vaginal microbicide hydrogels should form a barrier against viral infections and prevent virus spreading through mucus. Multiple particle tracking was used to quantify the mobility of 170-nm fluorescently labeled COOH-modified polystyrene particles (COOH-PS) into thermosensitive hydrogels composed of amphiphilic triblock copolymers with block compositions EOn-POm-EOn (where EO refers to ethylene oxide and PO to propylene oxide) containing mucoadhesive hydroxypropylmethylcellulose (HPMC). COOH-PS were used to mimic the size and the surface charge of HIV-1. Analysis of COOH-PS trajectories showed that particle mobility was decreased by Pluronic hydrogels in comparison with cynomolgus macaque cervicovaginal mucus and hydroxyethylcellulose hydrogel (HEC; 1.5% by weight [wt%]) used as negative controls. Formulation of the peptide mini-CD4 M48U1 used as an anti-HIV-1 molecule into a mixture of Pluronic F127 (20 wt%) and HPMC (1 wt%) did not affect its anti-HIV-1 activity in comparison with HEC hydrogel. The 50% inhibitory concentration (IC50) was 0.53 μg/ml (0.17 μM) for M48U1-HEC and 0.58 μg/ml (0.19 μM) for M48U1-F127-HPMC. The present work suggests that hydrogels composed of F127-HPMC (20/1 wt%, respectively) can be used to create an efficient barrier against particle diffusion in comparison to conventional HEC hydrogels. PMID:25645853

  16. Thermosensitive and mucoadhesive pluronic-hydroxypropylmethylcellulose hydrogel containing the mini-CD4 M48U1 is a promising efficient barrier against HIV diffusion through macaque cervicovaginal mucus.

    PubMed

    Bouchemal, Kawthar; Aka-Any-Grah, Armelle; Dereuddre-Bosquet, Nathalie; Martin, Loïc; Lievin-Le-Moal, Vanessa; Le Grand, Roger; Nicolas, Valérie; Gibellini, Davide; Lembo, David; Poüs, Christian; Koffi, Armand; Ponchel, Gilles

    2015-04-01

    To be efficient, vaginal microbicide hydrogels should form a barrier against viral infections and prevent virus spreading through mucus. Multiple particle tracking was used to quantify the mobility of 170-nm fluorescently labeled COOH-modified polystyrene particles (COOH-PS) into thermosensitive hydrogels composed of amphiphilic triblock copolymers with block compositions EOn-POm-EOn (where EO refers to ethylene oxide and PO to propylene oxide) containing mucoadhesive hydroxypropylmethylcellulose (HPMC). COOH-PS were used to mimic the size and the surface charge of HIV-1. Analysis of COOH-PS trajectories showed that particle mobility was decreased by Pluronic hydrogels in comparison with cynomolgus macaque cervicovaginal mucus and hydroxyethylcellulose hydrogel (HEC; 1.5% by weight [wt%]) used as negative controls. Formulation of the peptide mini-CD4 M48U1 used as an anti-HIV-1 molecule into a mixture of Pluronic F127 (20 wt%) and HPMC (1 wt%) did not affect its anti-HIV-1 activity in comparison with HEC hydrogel. The 50% inhibitory concentration (IC50) was 0.53 μg/ml (0.17 μM) for M48U1-HEC and 0.58 μg/ml (0.19 μM) for M48U1-F127-HPMC. The present work suggests that hydrogels composed of F127-HPMC (20/1 wt%, respectively) can be used to create an efficient barrier against particle diffusion in comparison to conventional HEC hydrogels.

  17. RF-interrogatable hydrogel-actuated biosensor

    SciTech Connect

    Hoel, Z; Wang, A W; Darrow, C B; Lee, A P; McConaghy, C F; Krulevitch, P; Gilman, A; Satcher, J H; Lane, S M

    2000-01-10

    The authors present a novel micromachined sensor that couples a swellable hydrogel with capacitive detection. The hydrogel swells in response to analyte concentration, exerting contact pressure on a deformable conducting membrane. Results are presented for characterization of a PHEMA hydrogel swelling in response to a calcium nitrate solution. Pressure-deflection measurements are performed on NiTi-based membranes. Hydrogel-actuated deflections of the membranes are measured. These measurements are correlated to determine the pressure generating characteristics of the hydrogel. Membrane deflection techniques have not previously been employed for hydrogel characterization. The PHEMA sample exhibited greatest sensitivity in the pH range of 6.0--6.5 and performed an average of 2.8 Joules of work per m{sup 3} per pH unit in response to ambient conditions over the pH range 3.5--6.5. The membrane deflections correspond to capacitive shifts of about 4 pF per pH unit for a capacitive transducer with initial gap of 100 {micro}m, capacitor plate area of 18.5 mm{sup 2} , and initial hydrogel volume of 11 {micro}L.

  18. Designing hydrogels for controlled drug delivery

    NASA Astrophysics Data System (ADS)

    Li, Jianyu; Mooney, David J.

    2016-12-01

    Hydrogel delivery systems can leverage therapeutically beneficial outcomes of drug delivery and have found clinical use. Hydrogels can provide spatial and temporal control over the release of various therapeutic agents, including small-molecule drugs, macromolecular drugs and cells. Owing to their tunable physical properties, controllable degradability and capability to protect labile drugs from degradation, hydrogels serve as a platform on which various physiochemical interactions with the encapsulated drugs occur to control drug release. In this Review, we cover multiscale mechanisms underlying the design of hydrogel drug delivery systems, focusing on physical and chemical properties of the hydrogel network and the hydrogel-drug interactions across the network, mesh and molecular (or atomistic) scales. We discuss how different mechanisms interact and can be integrated to exert fine control in time and space over drug presentation. We also collect experimental release data from the literature, review clinical translation to date of these systems and present quantitative comparisons between different systems to provide guidelines for the rational design of hydrogel delivery systems.

  19. Ultrathin hydrogel films for rapid optical biosensing.

    PubMed

    Zhang, Xi; Guan, Ying; Zhang, Yongjun

    2012-01-09

    Novel biosensors have been designed by reporting an analyte-induced (de)swelling of a stimuli-responsive hydrogel (usually in a form of thin film) with a suitable optical transducer. These simple, inexpensive hydrogel biosensors are highly desirable, however, their practical applications have been hindered, largely because of their slow response. Here we show that quick response hydrogel sensors can be designed from ultrathin hydrogel films. By the adoption of layer-by-layer assembly, a simple but versatile approach, glucose-sensitive hydrogel films with thickness on submicrometer or micrometer scale, which is 2 orders of magnitude thinner than films used in ordinary hydrogel sensors, can be facilely fabricated. The hydrogel films can not only respond to the variation in glucose concentration, but also report the event via the shift of Fabry-Perot fringes using the thin film itself as Fabry-Perot cavity. The response is linear and reversible. More importantly, the response is quite fast, making it possible to be used for continuous glucose monitoring.

  20. Hierarchically structured, hyaluronic acid-based hydrogel matrices via the covalent integration of microgels into macroscopic networks$

    PubMed Central

    Jha, Amit K.; Malik, Manisha S.; Farach-Carson, Mary C.; Duncan, Randall L.; Jia, Xinqiao

    2010-01-01

    We aimed to develop biomimetic hydrogel matrices that not only exhibit structural hierarchy and mechanical integrity, but also present biological cues in a controlled fashion. To this end, photocrosslinkable, hyaluronic acid (HA)-based hydrogel particles (HGPs) were synthesized via an inverse emulsion crosslinking process followed by chemical modification with glycidyl methacrylate (GMA). HA modified with GMA (HA-GMA) was employed as the soluble macromer. Macroscopic hydrogels containing covalently integrated hydrogel particles (HA-c-HGP) were prepared by radical polymerization of HA-GMA in the presence of crosslinkable HGPs. The covalent linkages between the hydrogel particles and the secondary HA matrix resulted in the formation of a diffuse, fibrilar interface around the particles. Compared to the traditional bulk gels synthesized by photocrosslinking of HA-GMA, these hydrogels exhibited a reduced sol fraction and a lower equilibrium swelling ratio. When tested under uniaxial compression, the HA-c-HGP gels were more pliable than the HA-p-HGP gels and fractured at higher strain than the HA-GMA gels. Primary bovine chondrocytes were photoencapsulated in the HA matrices with minimal cell damage. The 3D microenvironment created by HA-GMA and HA HGPs not only maintained the chondrocyte phenotype but also fostered the production of cartilage specific extracellular matrix. To further improve the biological activities of the HA-c-HGP gels, bone morphogenetic protein 2 (BMP-2) was loaded into the immobilized HGPs. BMP-2 was released from the HA-c-HGP gels in a controlled manner with reduced initial burst over prolonged periods of time. The HA-c-HGP gels are promising candidates for use as bioactive matrices for cartilage tissue engineering. PMID:20936090

  1. Photopatterning of Hydrogel Microarrays in Closed Microchips.

    PubMed

    Gumuscu, Burcu; Bomer, Johan G; van den Berg, Albert; Eijkel, Jan C T

    2015-12-14

    To date, optical lithography has been extensively used for in situ patterning of hydrogel structures in a scale range from hundreds of microns to a few millimeters. The two main limitations which prevent smaller feature sizes of hydrogel structures are (1) the upper glass layer of a microchip maintains a large spacing (typically 525 μm) between the photomask and hydrogel precursor, leading to diffraction of UV light at the edges of mask patterns, (2) diffusion of free radicals and monomers results in irregular polymerization near the illumination interface. In this work, we present a simple approach to enable the use of optical lithography to fabricate hydrogel arrays with a minimum feature size of 4 μm inside closed microchips. To achieve this, we combined two different techniques. First, the upper glass layer of the microchip was thinned by mechanical polishing to reduce the spacing between the photomask and hydrogel precursor, and thereby the diffraction of UV light at the edges of mask patterns. The polishing process reduces the upper layer thickness from ∼525 to ∼100 μm, and the mean surface roughness from 20 to 3 nm. Second, we developed an intermittent illumination technique consisting of short illumination periods followed by relatively longer dark periods, which decrease the diffusion of monomers. Combination of these two methods allows for fabrication of 0.4 × 10(6) sub-10 μm sized hydrogel patterns over large areas (cm(2)) with high reproducibility (∼98.5% patterning success). The patterning method is tested with two different types of photopolymerizing hydrogels: polyacrylamide and polyethylene glycol diacrylate. This method enables in situ fabrication of well-defined hydrogel patterns and presents a simple approach to fabricate 3-D hydrogel matrices for biomolecule separation, biosensing, tissue engineering, and immobilized protein microarray applications.

  2. Mechanical and structural contribution of non-fibrillar matrix in uniaxial tension: a collagen-agarose co-gel model.

    PubMed

    Lake, Spencer P; Barocas, Victor H

    2011-07-01

    The mechanical role of non-fibrillar matrix and the nature of its interaction with the collagen network in soft tissues remain poorly understood, in part because of the lack of a simple experimental model system to quantify these interactions. This study's objective was to examine mechanical and structural properties of collagen-agarose co-gels, utilized as a simplified model system, to understand better the relationships between the collagen network and non-fibrillar matrix. We hypothesized that the presence of agarose would have a pronounced effect on microstructural reorganization and mechanical behavior. Samples fabricated from gel solutions containing 1.0 mg/mL collagen and 0, 0.125, or 0.25% w/v agarose were evaluated via scanning electron microscopy, incremental tensile stress-relaxation tests, and polarized light imaging. While the incorporation of agarose did not dramatically alter collagen network morphology, agarose led to concentration-dependent changes in mechanical and structural properties. Specifically, resistance of co-gels to volume change corresponded with differences in fiber reorientation and elastic/viscoelastic mechanics. Results demonstrate strong relationships between tissue properties and offer insight into behavior of tissues of varying Poisson's ratio and fiber kinematics. Results also suggest that non-fibrillar material may have significant effects on properties of artificial and native tissues even in tension, which is generally assumed to be collagen dominated.

  3. Tailor-made cell patterning using a near-infrared-responsive composite gel composed of agarose and carbon nanotubes.

    PubMed

    Koga, Haruka; Sada, Takao; Fujigaya, Tsuyohiko; Nakashima, Naotoshi; Nakazawa, Kohji

    2013-03-01

    Micropatterning is useful for regulating culture environments. We developed a highly efficient near-infrared-(NIR)-responsive gel and established a new technique that enables cell patterning by NIR irradiation. As a new culture substratum, we designed a tissue culture plate that was coated with a composite gel composed of agarose and carbon nanotubes (CNTs). A culture plate coated with agarose only showed no response to NIR irradiation. In contrast, NIR laser irradiation induced heat generation by CNTs; this permitted local solation of the CNT/agarose gel, and consequently, selective cell-adhesive regions were exposed on the tissue culture plate. The solation area was controlled by the NIR intensity, magnification of the object lens and CNT concentration in the gel. Furthermore, we formed circular patterns of HeLa cells and linear patterns of 3T3 cells on the same culture plate through selective and stepwise NIR irradiation of the CNT/agarose gel, and we also demonstrated that individual 3T3 cells migrated along a linear path formed on the CNT/agarose gel by NIR irradiation. These results indicate that our technique is useful for tailor-made cell patterning of stepwise and/or complex cell patterns, which has various biological applications such as stepwise co-culture and the study of cell migration.

  4. Exploring the roles of integrin binding and cytoskeletal reorganization during mesenchymal stem cell mechanotransduction in soft and stiff hydrogels subjected to dynamic compression.

    PubMed

    Steward, Andrew J; Wagner, Diane R; Kelly, Daniel J

    2014-10-01

    The objective of this study was to explore how the response of mesenchymal stem cells (MSCs) to dynamic compression (DC) depends on their pericellular environment and the development of their cytoskeleton. MSCs were first seeded into 3% agarose hydrogels, stimulated with the chondrogenic growth factor TGF-β3 and exposed to DC (~10% strain at 1Hz) for 1h on either day 7, 14, or 21 of culture. At each time point, the actin, vimentin and tubulin networks of the MSCs were assessed using confocal microscopy. Similar to previous results, MSCs displayed a temporal response to DC; however, no dramatic changes in gross cytoskeletal organization were observed with time in culture. Vinculin (a membrane-cytoskeletal protein in focal adhesions) staining appeared more intense with time in culture. We next aimed to explore how changes to the pericellular environment, independent of the duration of exposure to TGF-β3, would influence the response of MSCs to DC. To this end, MSCs were encapsulated into either 'soft' or 'stiff' agarose hydrogels that are known to differentially support pericellular matrix (PCM) development. The application of DC led to greater relative increases in the expression of chondrogenic marker genes in the stiffer hydrogels, where the MSCs were found to have a more well developed PCM. These increases in gene expression were not observed following the addition of RGDS, an integrin blocker, suggesting that integrin binding plays a role in determining the response of MSCs to DC. Microtubule organization in MSCs was found to adapt in response to DC, but this effect was not integrin mediated, as this cytoskeletal reorganization was also observed in the presence of RGDS. In conclusion, although the PCM, integrin binding, and cytoskeletal reorganization are all involved in mechanotransduction of DC, none of these factors in isolation was able to completely explain the temporal mechanosensitivity of MSCs to dynamic compression.

  5. Use of leucocyte migration under agarose to study spontaneous and directed locomotion of leucocytes.

    PubMed Central

    Repo, H; Kostiala, A A; Kosunen, T U

    1978-01-01

    Three different cell attractants, together with the parallel use of the leucocyte migration agarose test (LMAT) and the leading front modification (LFM) of the Boyden chamber technique, were employed in studying whether the maximal migration of normal human polymorphonuclear leucocytes (PMNs) is higher toward an attractant (chemotaxis) than in the same attractant incorporated in the culture media (chemokinesis). Using LMAT, the maximal migration distance toward zymosan activated serum (ZAS) was found to be significantly longer than that under agarose mixed with ZAS, thus indicating a chemotactic effect exerted by ZAS. When bacterial culture filtrate (BCF) and casein were used as attractants, the corresponding difference was not significant, implying that the stimulatory effect of these substances on cell migration could be explained by increased random locomotion (chemokinesis) alone. In LFM, the migration rate was significantly higher along a casein gradient than without a gradient. Using ZAS, however, only chemokinesis could be demonstrated. BCF was found to attract PMNs into membrane filters only in the presence of human serum albumin. These observations give credence to the view that both LMAT and LFM are applicable to the in vitro assessment of chemotaxis and chemokinesis but the attractant of choice for this is different in each of the two methods. Images Figure 1 PMID:359465

  6. Cell fractionation with affinity ligands conjugated to agarose-polyacrolein microsphere beads.

    PubMed

    Margel, S; Ofarim, M; Eshhar, Z

    1983-07-01

    A new effective insoluble support useful for cell fractionation based on agarose-polyacrolein microsphere beads (APAMB) of diameters 150--250 micrometers has been developed. The synthesized polyacrolein (PA) microspheres, of average diameter 0.2 micrometer, are provided with reactive aldehyde groups through which various ligands containing primary amino groups are bound covalently in a single step at physiological pH. Antibodies coupled to the microspheres are very effective for labelling of cell surface receptors on human red blood cells and mouse lymphoid cells. APAMB were obtained by encapsulating the PA microspheres with agarose. Antibodies and lectins bound to the APAMB serve to construct affinity columns for the separation of red blood cells and murine lymphocyte subpopulations. Anti-human red blood cell antibodies coupled to anti-immunoglobulin APAMB are effective in separating human from turkey red blood cells, whereas either anti-Thy 1.2 anti-immunoglobulin antibodies or soybean agglutinin coupled to APAMB have proved useful for the separation of T and B cells from heterogeneous population of spleen cells. The separation procedure is simple, rapid and effective. The viability of the fractionated cells is unaffected by the procedure and the recovery of the cells is high: between 80% and 100%.

  7. Agarose gel-coated LPG based on two sensing mechanisms for relative humidity measurement.

    PubMed

    Miao, Yinping; Zhang, Kaikiang; Yuam, Yujie; Liu, Bo; Zhang, Hao; Liu, Yan; Yao, Jianquan

    2013-01-01

    A relative humidity (RH) sensor based on long-period grating (LPG) with different responses is proposed by utilizing agarose gel as the sensitive cladding film. The spectral characteristic is discussed as the ambient humidity level ranges from 25% to 95% RH. Since increment of RH will result in volume expansion and refractive index increment of the agarose gel, the LPG is sensitive to applied strain and ambient refractive index; both the resonance wavelength and coupling intensity present particular responses to RH within two different RH ranges (25%-65% RH and 65%-96% RH). The coupling intensity decreases within a lower RH range while it increases throughout a higher RH range. The resonance wavelength is sensitive to the higher RH levels, and the highest sensitivity reaches 114.7 pm/% RH, and shares the same RH turning point with coupling intensity response. From a practical perspective, the proposed RH sensor would find its potential applications in high humidity level, temperature-independent RH sensing and multiparameter sensing based on wavelength/power hybrid demodulation and even static RH alarm for automatic monitoring of a particular RH value owing to the nonmonotonic RH dependence of the transmission power within the whole tested RH range.

  8. Method for trapping affinity chromatography of transcription factors using aldehyde-hydrazide coupling to agarose.

    PubMed

    Jia, Yinshan; Jarrett, Harry W

    2015-08-01

    The use of a method of coupling DNA was investigated for trapping and purifying transcription factors. Using the GFP-C/EBP (CAAT/enhancer binding protein) fusion protein as a model, trapping gives higher purity and comparable yield to conventional affinity chromatography. The chemistry used is mild and was shown to have no detrimental effect on GFP fluorescence or GFP-C/EBP DNA binding. The method involves introducing a ribose nucleotide to the 3' end of a DNA sequence. Reaction with mM NaIO4 (sodium metaperiodate) produces a dialdehyde of ribose that couples to hydrazide-agarose. The DNA is combined at nM concentration with a nuclear extract or other protein mixture, and DNA-protein complexes form. The complex is then coupled to hydrazide-agarose for trapping the DNA-protein complex and the protein eluted by increasing NaCl concentration. Using a different oligonucleotide with the proximal E-box sequence from the human telomerase promoter, USF-2 transcription factor was purified by trapping, again with higher purity than results from conventional affinity chromatography and similar yield. Other transcription factors binding E-boxes, including E2A, c-Myc, and Myo-D, were also purified, but myogenin and NFκB were not. Therefore, this approach proved to be valuable for both affinity chromatography and the trapping approach.

  9. A Novel Agarolytic β-Galactosidase Acts on Agarooligosaccharides for Complete Hydrolysis of Agarose into Monomers

    PubMed Central

    Lee, Chan Hyoung; Kim, Hee Taek; Yun, Eun Ju; Lee, Ah Reum; Kim, Sa Rang; Kim, Jae-Han; Choi, In-Geol

    2014-01-01

    Marine red macroalgae have emerged to be renewable biomass for the production of chemicals and biofuels, because carbohydrates that form the major component of red macroalgae can be hydrolyzed into fermentable sugars. The main carbohydrate in red algae is agarose, and it is composed of d-galactose and 3,6-anhydro-l-galactose (AHG), which are alternately bonded by β1-4 and α1-3 linkages. In this study, a novel β-galactosidase that can act on agarooligosaccharides (AOSs) to release galactose was discovered in a marine bacterium (Vibrio sp. strain EJY3); the enzyme is annotated as Vibrio sp. EJY3 agarolytic β-galactosidase (VejABG). Unlike the lacZ-encoded β-galactosidase from Escherichia coli, VejABG does not hydrolyze common substrates like lactose and can act only on the galactose moiety at the nonreducing end of AOS. The optimum pH and temperature of VejABG on an agarotriose substrate were 7 and 35°C, respectively. Its catalytic efficiency with agarotriose was also similar to that with agaropentaose or agaroheptaose. Since agarotriose lingers as the unreacted residual oligomer in the currently available saccharification system using β-agarases and acid prehydrolysis, the agarotriose-hydrolyzing capability of this novel β-galactosidase offers an enormous advantage in the saccharification of agarose or agar in red macroalgae for its use as a biomass feedstock for fermentable sugar production. PMID:25038102

  10. Simulated moving bed separation of agarose-hydrolyzate components for biofuel production from marine biomass.

    PubMed

    Kim, Pung-Ho; Nam, Hee-Geun; Park, Chanhun; Wang, Nien-Hwa Linda; Chang, Yong Keun; Mun, Sungyong

    2015-08-07

    The economically-efficient separation of galactose, levulinic acid (LA), and 5-hydroxymethylfurfural (5-HMF) in acid hydrolyzate of agarose has been a key issue in the area of biofuel production from marine biomass. To address this issue, an optimal simulated moving bed (SMB) process for continuous separation of the three agarose-hydrolyzate components with high purities, high yields, and high throughput was developed in this study. As a first step for this task, the adsorption isotherm and mass-transfer parameters of each component on the qualified adsorbent were determined through a series of multiple frontal experiments. The determined parameters were then used in optimizing the SMB process for the considered separation. Finally, the optimized SMB process was tested experimentally using a self-assembled SMB unit with four zones. The SMB experimental results and the relevant computer simulations verified that the developed process in this study was quite successful in the economically-efficient separation of galactose, LA, and 5-HMF in a continuous mode with high purities and high yields. It is thus expected that the developed SMB process in this study will be able to serve as one of the trustworthy ways of improving the economic feasibility of biofuel production from marine biomass.

  11. Location of Biomarkers and Reagents within Agarose Beads of a Programmable Bio-nano-chip

    PubMed Central

    Jokerst, Jesse V.; Chou, Jie; Camp, James P.; Wong, Jorge; Lennart, Alexis; Pollard, Amanda A.; Floriano, Pierre N.; Christodoulides, Nicolaos; Simmons, Glennon W.; Zhou, Yanjie; Ali, Mehnaaz F.

    2012-01-01

    The slow development of cost-effective medical microdevices with strong analytical performance characteristics is due to a lack of selective and efficient analyte capture and signaling. The recently developed programmable bio-nano-chip (PBNC) is a flexible detection device with analytical behavior rivaling established macroscopic methods. The PBNC system employs ≈300 μm-diameter bead sensors composed of agarose “nanonets” that populate a microelectromechanical support structure with integrated microfluidic elements. The beads are an efficient and selective protein-capture medium suitable for the analysis of complex fluid samples. Microscopy and computational studies probe the 3D interior of the beads. The relative contributions that the capture and detection of moieties, analyte size, and bead porosity make to signal distribution and intensity are reported. Agarose pore sizes ranging from 45 to 620 nm are examined and those near 140 nm provide optimal transport characteristics for rapid (<15 min) tests. The system exhibits efficient (99.5%) detection of bead-bound analyte along with low (≈2%) nonspecific immobilization of the detection probe for carcinoembryonic antigen assay. Furthermore, the role analyte dimensions play in signal distribution is explored, and enhanced methods for assay building that consider the unique features of biomarker size are offered. PMID:21290601

  12. Agarose gel shift assay reveals that calreticulin favors substrates with a quaternary structure in solution.

    PubMed

    Boelt, Sanne Grundvad; Houen, Gunnar; Højrup, Peter

    2015-07-15

    Here we present an agarose gel shift assay that, in contrast to other electrophoresis approaches, is loaded in the center of the gel. This allows proteins to migrate in either direction according to their isoelectric points. Therefore, the presented assay enables a direct visualization, separation, and prefractionation of protein interactions in solution independent of isoelectric point. We demonstrate that this assay is compatible with immunochemical methods and mass spectrometry. The assay was used to investigate interactions with several potential substrates for calreticulin, a chaperone that is involved in different biological aspects through interaction with other proteins. The current analytical assays used to investigate these interactions are mainly spectroscopic aggregation assays or solid phase assays that do not provide a direct visualization of the stable protein complex but rather provide an indirect measure of interactions. Therefore, no interaction studies between calreticulin and substrates in solution have been investigated previously. The results presented here indicate that calreticulin has a preference for substrates with a quaternary structure and primarily β-sheets in their secondary structure. It is also demonstrated that the agarose gel shift assay is useful in the study of other protein interactions and can be used as an alternative method to native polyacrylamide gel electrophoresis.

  13. Agarose-gel electrophoresis for the quality assurance and purity of heparin formulations.

    PubMed

    Volpi, Nicola; Buzzega, Dania

    2012-01-01

    The adulteration of raw heparin (Hep) with a synthetic oversulfated chondroitin sulfate (OSCS) not found in nature produced in 2007-2008 a global crisis giving rise to the development of additional, new and specific methods for its quality assurance and purity. In this study, a simple and sensitive agarose-gel electrophoresis method has been developed for the visualization of OSCS in Hep samples along with other natural glycosaminoglycans possibly present as "process-related impurities", in particular dermatan sulfate (DS) and chondroitin sulfate (CS). Agarose-gel electrophoresis under non-conventional conditions is able to separate OSCS from Hep with its two components, the slow-moving and fast-moving species, DS and CS by performing separation for 15 h (overnight) and under high voltage (100 mA, ∼200 V). Densitometric scanning enabled us to calculate a limit of detection of ∼0.5 μg OSCS with a linear behaviour from 0.1 to 5 μg, comparable to CS/DS. Contaminated samples from Hep manufacturers were analyzed and quantitative data were found comparable to previous studies. Due to its capacity to process many samples in a single run and to the equipment commonly available in laboratories, this analytical method would be suitable for the identification and quantification of contamination by other polysaccharides, in particular OSCS and DS, within Hep preparations and formulations.

  14. Detection of genotoxic insult as DNA strand breaks in fish blood cells by agarose gel electrophoresis

    SciTech Connect

    Theodorakis, C.W. ); D'Surney, S.J. . Dept. of Biology); Shugart, L.R. . Environmental Sciences Division)

    1994-07-01

    DNA, isolated from the blood cells of bluegill sunfish (Lepomis macrochirus) exposed in the lab to bedded sediment collected from a site contaminated with genotoxic compounds (i.e., PAHs, PCBs, and heavy metals), was examined for strand breakage by agarose gel electrophoresis. Before electrophoresis the blood cells were embedded in agarose plugs and incubated with proteinase. After electrophoresis under both neutral (pH 7) or alkaline (pH 12) conditions, the median molecular length (MML) of the DNA distributed in the gel was determined. These quantitative measures were used to estimate the difference in the number of double- and single-strand breaks between DNA preparations. Both types of strand breakage were found to be greater in fish exposed to sediment contaminated with genotoxic compounds as compared to nonexposed fish. A statistically significant correlation was demonstrated between the MML value obtained by the electrophoretic assay reported here and the F value (measure of DNA double-strandedness) obtained by the alkaline unwinding assay.

  15. Improved agarose gel electrophoresis method and molecular mass calculation for high molecular mass hyaluronan.

    PubMed

    Cowman, Mary K; Chen, Cherry C; Pandya, Monika; Yuan, Han; Ramkishun, Dianne; LoBello, Jaclyn; Bhilocha, Shardul; Russell-Puleri, Sparkle; Skendaj, Eraldi; Mijovic, Jovan; Jing, Wei

    2011-10-01

    The molecular mass of the polysaccharide hyaluronan (HA) is an important determinant of its biological activity and physicochemical properties. One method currently used for the analysis of the molecular mass distribution of an HA sample is gel electrophoresis. In the current work, an improved agarose gel electrophoresis method for analysis of high molecular mass HA is presented and validated. HA mobility in 0.5% agarose minigels was found to be linearly related to the logarithm of molecular mass in the range from approximately 200 to 6000 kDa. A sample load of 2.5 μg for polydisperse HA samples was employed. Densitometric scanning of stained gels allowed analysis of the range of molecular masses present in the sample as well as calculation of weight-average and number-average values. The method was validated for a polydisperse HA sample with a weight-average molecular mass of approximately 2000 kDa. Excellent agreement was found between the weight-average molecular mass determined by electrophoresis and that determined by rheological measurement of the solution viscosity. The revised method was then used to show that heating solutions of HA at 100°C, followed by various cooling procedures, had no effect on the HA molecular mass distribution.

  16. Dependence of light attenuation and backscattering on collagen concentration and chondrocyte density in agarose scaffolds.

    PubMed

    Puhakka, P H; Ylärinne, J H; Lammi, M J; Saarakkala, S; Tiitu, V; Kröger, H; Virén, T; Jurvelin, J S; Töyräs, J

    2014-11-07

    Optical coherence tomography (OCT) has been applied for high resolution imaging of articular cartilage. However, the contribution of individual structural elements of cartilage on OCT signal has not been thoroughly studied. We hypothesize that both collagen and chondrocytes, essential structural components of cartilage, act as important light scatterers and that variation in their concentrations can be detected by OCT through changes in backscattering and attenuation. To evaluate this hypothesis, we established a controlled model system using agarose scaffolds embedded with variable collagen concentrations and chondrocyte densities. Using OCT, we measured the backscattering coefficient (µb) and total attenuation coefficient (µt) in these scaffolds. Along our hypothesis, light backscattering and attenuation in agarose were dependent on collagen concentration and chondrocyte density. Significant correlations were found between µt and chondrocyte density (ρ = 0.853, p < 0.001) and between µt and collagen concentration (ρ = 0.694, p < 0.001). µb correlated significantly with chondrocyte density (ρ = 0.504, p < 0.001) but not with collagen concentration (ρ = 0.103, p = 0.422) of the scaffold. Thus, quantitation of light backscattering and, especially, attenuation could be valuable when evaluating the integrity of soft tissues, such as articular cartilage with OCT.

  17. Covalent attachment of lipases on glyoxyl-agarose beads: application in fruit flavor and biodiesel synthesis.

    PubMed

    Mendes, Adriano A; de Castro, Heizir F; Giordano, Raquel L C

    2014-09-01

    The aim of this work was to prepare biocatalysts to catalyze the synthesis of butyl butyrate by esterification reaction, and the synthesis of biodiesel by transesterification of palm and babassu oils with ethanol. Lipase preparations Lipolase® (TLL1) and Lipex® 100 L (TLL2) from Thermomyces lanuginosus and Lipase AK from Pseudomonas fluorescens (PFL) were immobilized on glyoxyl-agarose beads prepared by activation with glycidol (Gly) and epichlorohydrin (Epi). The influence of immobilization time, lipase source and activating agents on the catalytic activity of the biocatalysts were evaluated in both aqueous and organic media. TLL1 immobilized on glyoxyl-agarose by 24 h of incubation resulted biocatalysts with high hydrolytic activity (varying from 1347.3 to 1470.0 IU/g of support) and thermal-stability, around 300-fold more stable than crude TLL1 extract. The maximum load of immobilized TLL1 was around 20 mg of protein/g of support. The biocatalyst prepared exhibited high activity and operational stability on the butyl butyrate synthesis by esterification after five successive cycles of 24 h each (conversion around 85-90%). Immobilized TLL1 and PFL were active in the synthesis of biodiesel by transesterification reaction. Maximum transesterification yield (≥98.5% after 48 h of reaction at 45°C) was provided by using palm oil as feedstock.

  18. Novel Crosslinked Graft Copolymer of Methacrylic Acid and Collagen as a Protein-Based Superabsorbent Hydrogel with Salt and Ph-Responsiveness Properties

    NASA Astrophysics Data System (ADS)

    Sadeghi, Mohammad; Hamzeh, Alireza

    2008-08-01

    In this paper, a novel protein-based superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of methacrylic acid (MAA) onto collagen, using ammonium persulfate (APS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. The hydrogel structure was confirmed using FTIR spectroscopy. We were systematically optimized the certain variables of the graft copolymerization (i.e. the monomer, the initiator, and the crosslinker concentration) to achieve a hydrogel with maximum swelling capacity. Under the optimized conditions concluded, maximum capacity of swelling in distilled water was found to be 415 g/g. The swelling kinetics of the synthesized hydrogels with various particle sizes was preliminarily investigated. Absorbency in aqueous chloride salt solutions indicated that the swelling capacity decreased with an increase in the ionic strength of the swelling medium. The swelling of superabsorbing hydrogels was also measured in solutions with pH ranged from 1 to 13. The synthesized hydrogel exhibited a pH-responsiveness character so that a swelling-collapsing pulsatile behavior was recorded at pHs 2 and 7. This behavior makes the synthesized hydrogels as an excellent candidate for controlled delivery of bioactive agents.

  19. Fabricating customized hydrogel contact lens

    NASA Astrophysics Data System (ADS)

    Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

    2016-10-01

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies.

  20. Fabricating customized hydrogel contact lens

    PubMed Central

    Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

    2016-01-01

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies. PMID:27748361

  1. Supercooled Water in Supramolecular Hydrogels

    NASA Astrophysics Data System (ADS)

    Wiener, Clinton; Vogt, Bryan; Weiss, R. A.

    The suppression of water crystallization with appreciable water supercooling is challenging due to its large enthalpy of fusion. A common theme to supercool water is to confine the water in the pores of microporous/mesoporous solids where mechanical confinement prevents water crystallization. Nature takes a different approach with crystallization suppression through a combination of preferential adsorption on ice nuclei and confinement between hydrophobic residues using organic components only. Here, we demonstrate that mechanically robust confinement within a hard material is not necessary to significantly supercool water. In this case, a supramolecular hydrogel, based on a random amphiphilic copolymer, is used to provide soft confinement of water between the hydrophobic aggregates with an interdomain spacing <8 nm. Small angle neutron scattering (SANS) provides insight into the structural evolution of the supramolecular structure of the hydrogel on supercooling. The structural changes are sensitive to the composition of the copolymer as determined by contrast variation SANS. Similarly, the dynamics of both the copolymer and water are probed using quasielastic neutron scattering (QENS). Using QENS, a highly mobile water phase (tau ~23 ps) is identified to be present even when slowly cooling to as low as 220K.

  2. Fabricating customized hydrogel contact lens.

    PubMed

    Childs, Andre; Li, Hao; Lewittes, Daniella M; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F

    2016-10-17

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young's modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies.

  3. Native agarose gel electrophoresis and electroelution: A fast and cost-effective method to separate the small and large hepatitis B capsids.

    PubMed

    Yoon, Kam Yee; Tan, Wen Siang; Tey, Beng Ti; Lee, Khai Wooi; Ho, Kok Lian

    2013-01-01

    Hepatitis B core antigen (HBcAg) expressed in Escherichia coli is able to self-assemble into large and small capsids comprising 240 (triangulation number T = 4) and 180 (triangulation number T = 3) subunits, respectively. Conventionally, sucrose density gradient ultracentrifugation and SEC have been used to separate these capsids. However, good separation of the large and small particles with these methods is never achieved. In the present study, we employed a simple, fast, and cost-effective method to separate the T = 3 and T = 4 HBcAg capsids by using native agarose gel electrophoresis followed by an electroelution method (NAGE-EE). This is a direct, fast, and economic method for isolating the large and small HBcAg particles homogenously based on the hydrodynamic radius of the spherical particles. Dynamic light scattering analysis demonstrated that the T = 3 and T = 4 HBcAg capsids prepared using the NAGE-EE method are monodisperse with polydispersity values of ∼15% and ∼13%, respectively. ELISA proved that the antigenicity of the capsids was not affected in the purification process. Overall, NAGE-EE produced T = 3 and T = 4 capsids with a purity above 90%, and the recovery was 34% and 50%, respectively (total recovery of HBcAg is ∼84%), and the operation time is 15 and 4 times lesser than that of the sucrose density gradient ultracentrifugation and SEC, respectively.

  4. Comparation of effectiveness of silicone hydrogel contact lens and hydrogel contact lens in patients after LASEK

    PubMed Central

    Xie, Wen-Juan; Zeng, Jin; Cui, Ying; Li, Juan; Li, Zhong-Ming; Liao, Wei-Xiong; Yang, Xiao-Hong

    2015-01-01

    AIM To conduct a comparative study of effectiveness of silicone hydrogel contact lens and hydrogel contact lens, which are used in patients after laser-assisted subepithelial keratomileusis (LASEK). METHODS Sixty-three patients (121 eyes) with a spherical equivalent ≤-5.0 D were chosen after undergoing LASEK in 2012 at Guangdong General Hospital. They were randomly divided into 2 groups. The silicone hydrogel group included 32 cases (61 eyes) that wore silicone hydrogel contact lenses for 4-6d after the operation, while the hydrogel group included 31 cases (60 eyes) who wore hydrogel contact lenses for 4-6d after the operation. Patients' self-reported postoperative symptoms (including pain, photophobia, tears, and foreign body sensation) were evaluated. The healing time of the corneal epithelium, the visual acuity of patients without contact lens after epithelial healing, and the incidence of delayed corneal epithelial shedding were also assessed. The follow-up time was 1mo. RESULTS Postoperative symptoms were milder in the silicone hydrogel group than in the hydrogel group. There were significant differences in pain, foreign body sensation, and photophobia between the 2 groups (P<0.05), although there was no significant difference in postoperative tearing (P>0.05). The healing time of the corneal epithelium in the silicone hydrogel lens group was markedly shorter than that in the hydrogel group (4.07±0.25 vs 4.33±0.82d, t=2.43, P=0.02). Visual acuity without contact lenses after healing of the corneal epithelium was better in the silicone hydrogel group compared with the hydrogel group (χ2=7.76, P=0.02). There was no significant difference in the occurrence of delayed corneal epithelial shedding between the 2 groups (P>0.05). CONCLUSION Patients with LASEK using silicon hydrogel contact lenses had less discomfort and shorter corneal epithelial healing time compared with those using hydrogel contact lenses, suggesting that silicon hydrogel contact lenses may

  5. Kinetics of desorption of KCL from polyvinyl alcohol-borate hydrogel in aqueous-alcoholic solvents at different temperatures

    NASA Astrophysics Data System (ADS)

    Saeed, Rehana; Abdeen, Zain Ul

    2015-11-01

    Desorption kinetics of adsorbed KCl from Polyvinyl alcohol borate hydrogel was studied by conductivity method in aqueous system and aqueous binary solvent system using 50% aqueous-methanol, aqueous- ethanol and aqueous-propanol at different temperature ranging from 293 to 313 K. Desorption process follows pseudo first order and intra particle diffusion kinetics was analyzed on the basis of linear regression coefficient R 2 and chi square test χ2 values. The process of desorption of KCl from hydrogel was favorable in aqueous system, the study reveals the fact that the polarity of solvent influenced the kinetics of desorption, on decrement of polarity of solvent rate, rate constant and intra particle rate constant decreases. Based on intra particle kinetic equation fitting it was concluded that desorption was initiated by removal of ions from surface of hydrogel later on ions interacted inside the cross linked unit was also become free. Temperature enhances the rate, rate constant and intra particle rate constant. Thermodynamic parameters attributed towards the fact that the process of desorption of KCl from hydrogel is non-spontaneous in nature.

  6. Microfabrication of hydrogels for biomedical applications

    NASA Astrophysics Data System (ADS)

    Yu, Tianyue; Chiellini, Federica; Schmaljohan, Dirk; Solaro, Roberto; Ober, Christopher K.

    2002-07-01

    Hydrogels have gained general acceptance as biocompatible materials and are the basis of many promising applications in tissue engineering, drug release formulations and biosensors. Polymer processing techniques that can generate miniature hydrogel microstructures are not only critical as scaffolds for tissue re-growth but also very effective for increasing the efficiency of drug delivery and biosensors. Our approach is to use both optical and soft lithographic methods to microfabricate hydrogels. In this paper, we describe a photolithographic process to pattern hydrogel materials and analyze factors influencing sensitivity and lateral resolution. The model system we are investigating is based on 2-hydroxyethyl methacrylate (HEMA), which is well known for its non-toxicity and its widespread use in the contact lens industry.

  7. Biologically-Based Self-Assembling Hydrogels

    DTIC Science & Technology

    2002-04-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP014396 TITLE: Biologically-Based Self-Assembling Hydrogels DISTRIBUTION...Based Self-Assembling Hydrogels Brandon L. Seal and Alyssa Panitch Department of Bioengineering, Arizona State University Tempe, AZ 85287-9709, U.S.A...Factor Xllla substrate were synthesized and conjugated to methacroylated dextran or acrylated poly(ethylene glycol). Peptide-conjugated dextran was added

  8. Multitriggered Shape-Memory Acrylamide-DNA Hydrogels.

    PubMed

    Lu, Chun-Hua; Guo, Weiwei; Hu, Yuwei; Qi, Xiu-Juan; Willner, Itamar

    2015-12-23

    Acrylamide-acrylamide nucleic acids are cross-linked by two cooperative functional motives to form shaped acrylamide-DNA hydrogels. One of the cross-linking motives responds to an external trigger, leading to the dissociation of one of the stimuli-responsive bridges, and to the transition of the stiff shaped hydrogels into soft shapeless states, where the residual bridging units, due to the chains entanglement, provide an intrinsic memory for the reshaping of the hydrogels. Subjecting the shapeless states to counter stimuli restores the dissociated bridges, and regenerates the original shape of the hydrogels. By the cyclic dissociation and reassembly of the stimuli-responsive bridges, the reversible switchable transitions of the hydrogels between stiff shaped hydrogel structures and soft shapeless states are demonstrated. Shaped hydrogels bridged by K(+)-stabilized G-quadruplexes/duplex units, by i-motif/duplex units, or by two different duplex bridges are described. The cyclic transitions of the hydrogels between shaped and shapeless states are stimulated, in the presence of appropriate triggers and counter triggers (K(+) ion/crown ether; pH = 5.0/8.0; fuel/antifuel strands). The shape-memory hydrogels are integrated into shaped two-hydrogel or three-hydrogel hybrid structures. The cyclic programmed transitions of selective domains of the hybrid structures between shaped hydrogel and shapeless states are demonstrated. The possible applications of the shape-memory hydrogels for sensing, inscription of information, and controlled release of loads are discussed.

  9. A Hydrogel Derived From Decellularized Dermal Extracellular Matrix

    PubMed Central

    Wolf, Matthew T.; Daly, Kerry A.; Brennan-Pierce, Ellen P.; Johnson, Scott A.; Carruthers, Christopher; D’Amore, Antonio; Nagarkar, Shailesh P.; Velankar, Sachin S.; Badylak, Stephen F.

    2012-01-01

    The ECM of mammalian tissues has been used as a scaffold to facilitate the repair and reconstruction of numerous tissues. Such scaffolds are prepared in many forms including sheets, powders, and hydrogels. ECM hydrogels provide advantages such as injectability, the ability to fill an irregularly shaped space, and the inherent bioactivity of native matrix. However, material properties of ECM hydrogels and the effect of these properties upon cell behavior are neither well understood nor controlled. The objective of this study was to prepare and determine the structure, mechanics, and the cell response in vitro and in vivo of ECM hydrogels prepared from decellularized porcine dermis and urinary bladder tissues. Dermal ECM hydrogels were characterized by a more dense fiber architecture and greater mechanical integrity than urinary bladder ECM hydrogels, and showed a dose dependent increase in mechanical properties with ECM concentration. In vitro, dermal ECM hydrogels supported greater C2C12 myoblast fusion, and less fibroblast infiltration and less fibroblast mediated hydrogel contraction than urinary bladder ECM hydrogels. Both hydrogels were rapidly infiltrated by host cells, primarily macrophages, when implanted in a rat abdominal wall defect. Both ECM hydrogels degraded by 35 days in vivo, but UBM hydrogels degraded more quickly, and with greater amounts of myogenesis than dermal ECM. These results show that ECM hydrogel properties can be varied and partially controlled by the scaffold tissue source, and that these properties can markedly affect cell behavior. PMID:22789723

  10. Binding of human fibroblast interferon to concanavalin A-agarose. Involvement of carbohydrate recognition and hydrophobic interaction.

    PubMed

    Davey, M W; Sulkowski, E; Carter, W A

    1976-02-10

    Human fibroblast interferon binds to a concanavalin A-agarose (Con A-Sepharose) equilibrated with methyl alpha-D-mannopyranoside, or levan; in contrast, it is only partially retarded on a similar column equilibrated with ethylene glycol. Interferon does not bind, however, to a lectin column equilibrated with both methyl alpha-D-mannopyranoside and ethylene glycol. Thus, a hydrophobic interaction between fibroblast interferon and the immobilized lectin seems to account for a large portion of the binding forces involved. Other hydrophobic solutes, such as dioxane, 1, 2-propanediol, and tetraethylammonium chloride, were found equally or more efficient than ethylene glycol in displacing interferon from the lectin column. The elution pattern of interferon from a concanavalin A-agarose (Con A-Sepharose) column, at a constant ehtylene glycol concentration and with an increasing mannoside concentration, reveals the existence of four distinct interferon components. The selective adsorption to and elution from a concanavalin A-agarose (Con A-Sepharose) column resulted in about a 3000-fold purification of human fibroblast interferon and complete recovery of activity. The specific activity of the partially purified interferon preparation is about 5 X 10(7) units per mg of protein. The chromatographic behavior of human leukocyte interferon is remarkable in that it does not bind to concanavalin A-agarose at all indicating the absence of carbohydrate moieties recognizable by the lectin, or if present, their masked status. When concanavalin A was coupled to an agarose matrix (cyanogen bromide activated) at pH 8.0 and 6.0 human fibroblast interferon bound to both lectin-agarose adsorbents and could be recovered with methyl alpha-D-mannopyranoside. Concanavalin A, immobilized directly on agarose matrix at pH 8.0 and 6.0, thus displays only carbohydrate recognition toward interferon. By contrast, unless a hydrophobic solute was included in the solvent containing methyl mannoside

  11. Directionality of replication fork movement determined by two-dimensional native-native DNA agarose gel electrophoresis.

    PubMed

    Ivessa, Andreas S

    2013-01-01

    The analysis of replication intermediates by the neutral-neutral two-dimensional agarose gel technique allows determining the chromosomal positions where DNA replication initiates, whether replication forks pause or stall at specific sites, or whether two DNA molecules undergo DNA recombination events. This technique does not, however, immediately tell in which direction replication forks migrate through the DNA region under investigation. Here, we describe the procedure to determine the direction of replication fork progression by carrying out a restriction enzyme digest of DNA imbedded in agarose after the completion of the first dimension of a 2D gel.

  12. Hydrogel: Preparation, characterization, and applications: A review.

    PubMed

    Ahmed, Enas M

    2015-03-01

    Hydrogel products constitute a group of polymeric materials, the hydrophilic structure of which renders them capable of holding large amounts of water in their three-dimensional networks. Extensive employment of these products in a number of industrial and environmental areas of application is considered to be of prime importance. As expected, natural hydrogels were gradually replaced by synthetic types due to their higher water absorption capacity, long service life, and wide varieties of raw chemical resources. Literature on this subject was found to be expanding, especially in the scientific areas of research. However, a number of publications and technical reports dealing with hydrogel products from the engineering points of view were examined to overview technological aspects covering this growing multidisciplinary field of research. The primary objective of this article is to review the literature concerning classification of hydrogels on different bases, physical and chemical characteristics of these products, and technical feasibility of their utilization. It also involved technologies adopted for hydrogel production together with process design implications, block diagrams, and optimized conditions of the preparation process. An innovated category of recent generations of hydrogel materials was also presented in some details.

  13. Vortex-Induced Injectable Silk Fibroin Hydrogels

    PubMed Central

    Yucel, Tuna; Cebe, Peggy; Kaplan, David L.

    2009-01-01

    Abstract A novel, to our knowledge, technique was developed to control the rate of β-sheet formation and resulting hydrogelation kinetics of aqueous, native silk solutions. Circular dichroism spectroscopy indicated that vortexing aqueous solutions of silkworm silk lead to a transition from an overall protein structure that is initially rich in random coil to one that is rich in β-sheet content. Dynamic oscillatory rheology experiments collected under the same assembly conditions as the circular dichroism experiments indicated that the increase in β-sheet content due to intramolecular conformational changes and intermolecular self-assembly of the silk fibroin was directly correlated with the subsequent changes in viscoelastic properties due to hydrogelation. Vortexing low-viscosity silk solutions lead to orders-of-magnitude increase in the complex shear modulus, G∗, and formation of rigid hydrogels (G∗ ≈ 70 kPa for 5.2 wt % protein concentration). Vortex-induced, β-sheet-rich silk hydrogels consisted of permanent, physical, intermolecular crosslinks. The hydrogelation kinetics could be controlled easily (from minutes to hours) by changing the vortex time, assembly temperature and/or protein concentration, providing a useful timeframe for cell encapsulation. The stiffness of preformed hydrogels recovered quickly, immediately after injection through a needle, enabling the potential use of these systems for injectable cell delivery scaffolds. PMID:19804736

  14. Hydrogel: Preparation, characterization, and applications: A review

    PubMed Central

    Ahmed, Enas M.

    2013-01-01

    Hydrogel products constitute a group of polymeric materials, the hydrophilic structure of which renders them capable of holding large amounts of water in their three-dimensional networks. Extensive employment of these products in a number of industrial and environmental areas of application is considered to be of prime importance. As expected, natural hydrogels were gradually replaced by synthetic types due to their higher water absorption capacity, long service life, and wide varieties of raw chemical resources. Literature on this subject was found to be expanding, especially in the scientific areas of research. However, a number of publications and technical reports dealing with hydrogel products from the engineering points of view were examined to overview technological aspects covering this growing multidisciplinary field of research. The primary objective of this article is to review the literature concerning classification of hydrogels on different bases, physical and chemical characteristics of these products, and technical feasibility of their utilization. It also involved technologies adopted for hydrogel production together with process design implications, block diagrams, and optimized conditions of the preparation process. An innovated category of recent generations of hydrogel materials was also presented in some details. PMID:25750745

  15. Development of a thermosensitive hydrogel system for local delivery of (188)Re colloid drugs.

    PubMed

    Huang, Feng-Yun; Huang, Ling-Kuen; Lin, Wan-Yu; Luo, Tsai-Yueh; Tsai, Chang-Shu; Hsieh, Bor-Tsung

    2009-01-01

    A novel internal radiation therapy (IRT) mode intended for controlled local delivery of (188)Re-Tin colloid was developed by using chitosan-based thermosensitive hydrogel. Chitosan (C) and beta-glycerophosphate (beta-GP) were used to prepare the thermosensitive hydrogel (C/GP). The prepared C/GP hydrogel featured a rapid sol-gel transition within 5min after it was brought into an environment of 37 degrees C. (188)Re-Tin colloid was prepared with labeling efficiency of 93.9+/-0.6%, and could be increased to more than 98% following centrifugation. The average particle size of (188)Re-Tin colloid was 12.1+/-1.2microm, with only 7.2+/-1.5% less than 1microm. Scintigraphic study showed that (188)Re-Tin colloid contained in the C/GP hydrogel was localized (>91%) around the injection site for up to 48h post injection, verifying the intended function of the IRT design. The developed novel form of IRT in this study could be an effective treatment mode for regional radiotherapy.

  16. Release behavior and bioefficacy of imazethapyr formulations based on biopolymeric hydrogels.

    PubMed

    Kumar, Vikas; Singh, Anupama; Das, T K; Sarkar, Dhruba Jyoti; Singh, Shashi Bala; Dhaka, Rashmi; Kumar, Anil

    2017-03-08

    Controlled release formulations of imazethapyr herbicide have been developed employing guar gum-g-cl-polyacrylate/bentonite clay hydrogel composite (GG-HG) and guar gum-g-cl-PNIPAm nano hydrogel (GG-NHG) as carriers, to assess the suitability of biopolymeric hydrogels as controlled herbicide release devices. The kinetics of imazethapyr release from the developed formulations was studied in water and it revealed that the developed formulations of imazethapyr behaved as slow release formulations as compared to commercial formulation. The calculated diffusion exponent (n) values showed that Fickian diffusion was the predominant mechanism of imazethapyr release from the developed formulations. Time for release of half of the loaded imazethapyr (t1/2) ranged between 0.06 and 4.8 days in case of GG-NHG and 4.4 and 12.6 days for the GG-HG formulations. Weed control index (WCI) of GG-HG and GG-NHG formulations was similar to that of the commercial formulation and the herbicidal effect was observed for relatively longer period. Guar gum-based biopolymeric hydrogels in both macro and nano particle size range can serve as potential carriers in developing slow release herbicide formulations.

  17. Fabrication of hydrogel-encapsulated silica core bound with chitosan chains for efficient drug delivery

    NASA Astrophysics Data System (ADS)

    Byeol Bae, Saet; Lee, Sang Wha

    2016-06-01

    In this study, hydrogel-encapsulated silica nanoparticles were facilely prepared through the following three consecutive steps: i) silica nanoparticles (SNPs) were synthesized via a sol-gel reaction of tetraethyl orthosilicate (TEOS) with ammonium hydroxide, ii) the resulting SNPs were functionalized with 3-(trimethoxysilyl)-propylmethacrylate (TPM) ligand with an olefin group, and iii) the TPM-functionalized SNPs were encapsulated with poly(N-isopropylacrylamide-co-acrylic acid), NIPAM-co-AAc hydrogels by using a radical polymerization reaction of the co-monomers at the following ratio: \\text{NIPAM}:\\text{AAc} = 91:9 wt %. The lower critical solution temperature (LCST) of the encapsulated hydrogels with a moiety of carboxylic groups was slightly above physiological temperature and they demonstrated a thermo-sensitive variation of particle size. The hydrogel-encapsulated SNPs (SNPs@Hyd) were finally bound with chitosan chains, which are bio-friendly and non-toxic polymers. When compared to SNPs@Hyd, chitosan-coated SNPs@Hyd (SNPs@Hyd@Chi) exhibited prolonged drug (ibuprofen) release and stable structural integrity during the release test.

  18. Designing a bio-inspired self-propelling hydrogel micro-swimmer

    NASA Astrophysics Data System (ADS)

    Nikolov, Svetoslav; Yeh, Peter; Alexeev, Alexander

    2014-11-01

    Artificial micro-swimmers have found numerous applications in microfluidics, drug delivery systems, and nanotechnology. In our current research we use dissipative particle dynamics to design and optimize a self-propelling hydrogel micro-swimmer with an X-shaped flat geometry and bi-layered hydrogel structure. The two polymeric layers that bind to each other have identical material properties but distinctive chemical responses to external stimuli. In the presence of outside stimuli one of the layers swells where the other remains passive resulting in hydrogel bending. Our simulations demonstrate that under periodic applications of an external stimulus this actuation routine is capable of creating time-irreversible motion in a low Reynolds number environment. Initially, when the external stimulus is introduced a forward stroke is initiated, as the swimmer first expands and then bends. When the outside stimulus is removed the forward stroke is terminated and a backward stroke begins, as the swimmer contracts and then straightens. Propulsion results due to the difference in momentum exchange between the forward and backward strokes. We use our simulations to probe how alterations in the material properties of the bi-layered hydrogel can affect swimming performance. Support from NSF CAREER Award (DMR-1255288) is gratefully acknowledged.

  19. Microparticles Produced by the Hydrogel Template Method for Sustained Drug Delivery

    PubMed Central

    Lu, Ying; Sturek, Michael; Park, Kinam

    2014-01-01

    Polymeric microparticles have been used widely for sustained drug delivery. Current methods of microparticle production can be improved by making homogeneous particles in size and shape, increasing the drug loading, and controlling the initial burst release. In the current study, the hydrogel template method was used to produce homogeneous poly(lactide-co-glycolide) (PLGA) microparticles and to examine formulation and process-related parameters. Poly(vinyl alcohol) (PVA) was used to make hydrogel templates. The parameters examined include PVA molecular weight, type of PLGA (as characterized by lactide content, inherent viscosity), polymer concentration, drug concentration and composition of solvent system. Three model compounds studied were risperidone, methylprednisolone acetate and paclitaxel. The ability of the hydrogel template method to produce microparticles with good conformity to template was dependent on molecular weight of PVA and viscosity of the PLGA solution. Drug loading and encapsulation efficiency were found to be influenced by PLGA lactide content, polymer concentration and composition of the solvent system. The drug loading and encapsulation efficiency were 28.7% and 82% for risperidone, 31.5% and 90% for methylprednisolone acetate, and 32.2 % and 92 % for paclitaxel, respectively. For all three drugs, release was sustained for weeks, and the in vitro release profile of risperidone was comparable to that of microparticles prepared using the conventional emulsion method. The hydrogel template method provides a new approach of manipulating microparticles. PMID:24333903

  20. Microwave-assisted fabrication of chitosan-hydroxyapatite superporous hydrogel composites as bone scaffolds.

    PubMed

    Beşkardeş, Işıl Gerçek; Demirtaş, Tuğrul Tolga; Durukan, Müge Dağlı; Gümüşderelioğlu, Menemşe

    2015-11-01

    In this study, a novel scaffold fabrication method was developed by combining microwave irradiation and gas foaming. Chitosan superporous hydrogels (SPHs) and chitosan-hydroxyapatite (HA) superporous hydrogel composites (SPHCs) were prepared by using this method in the presence of crosslinking agent, glyoxal, and a gas-blowing agent, NaHCO3. In order to examine the effect of HA on composite structure and cellular behaviour, two types of HA particles, i.e. spherical beads in 45-80 µm diameter and powder form, were used. While rapid heating with microwave irradiation enhances gas blowing, pH increment, which is accelerated by NaHCO3 decomposition, provides better crosslinking. Thus, interconnected and well-established macroporous hydrogels/hydrogel composites were produced easily and rapidly (~1 min). Cell culture studies, which were carried out under static and dynamic conditions with MC3T3-E1 pre-osteoblastic cells, indicated that chitosan-HA bead SPHCs supported cellular proliferation and osteoblastic differentiation better than chitosan SPHs and chitosan-HA powder SPHCs. In conclusion, simultaneous gas foaming and microwave crosslinking can be evaluated for the preparation of composite scaffolds which have superior properties for bone tissue engineering.

  1. VISCOELASTIC PROPERTIES OF A BIOLOGICAL HYDROGEL PRODUCED FROM SOYBEAN OIL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hydrogels formed from biopolymers or natural sources have special advantages because of their biodegradable and biocompatible properties. The viscoelastic properties of a newly developed biological hydrogel made from modified vegetable oil, epoxidized soybean oil (ESO) were investigated. The mater...

  2. Bioerodible calcium sulfate/poly(β-amino ester) hydrogel composites.

    PubMed

    Orellana, Bryan R; Thomas, Mark V; Dziubla, Thomas D; Shah, Nihar M; Hilt, J Zach; Puleo, David A

    2013-10-01

    The capacity to quickly regenerate or augment bone lost as a result of resorption is crucial to ensure suitable application of prosthetics for restoring masticatory function. Calcium sulfate hemihydrate (CS)-based bone graft substitute composites containing poly(β-amino ester) (PBAE) biodegradable hydrogel particles were developed to act as a 'tenting' barrier to soft tissue infiltration, potentially providing adequate space to enable vertical bone regeneration. CS has long been recognized as an osteoconductive biomaterial with an excellent reputation as a biocompatible substance. Composite samples were fabricated with varying amounts (1 or 10 wt%) and sizes (53-150 or 150-250 μm) of gel particles embedded in CS. The swelling and degradation rates of PBAE gels alone were rapid, resulting in complete degradation in less than 24h, an important characteristic to aid in controlled release of drug. MicroCT images revealed a homogeneous distribution of gel particles within the CS matrix. All CS samples degraded via surface erosion, with the amount of gel particles (i.e., 10 wt% gel particles) having only a small, but significant, effect on the dissolution rate (4% vs. 5% per day). Compression testing determined that the amount, but not the size, of gel particles had a significant effect on the overall strength of the composites. As much as a 75% drop in strength was seen with a 10 wt% loading of particles. A pilot study using PBAE particles loaded with the multipotential drug curcumin demonstrated sustained release of drug from CS composites. By adjusting the amount and/or size of the biodegradable gel particles embedded in CS, mechanical strength and degradation rates of the composites, as well as the drug release kinetics, can be tuned to fabricate, multi-functional 'space-making' bone grafting substitutes.

  3. Bioerodible Calcium Sulfate/Poly(β-amino ester) Hydrogel Composites

    PubMed Central

    Orellana, Bryan R.; Thomas, Mark V.; Dziubla, Thomas D.; Shah, Nihar M.; Hilt, James Z.; Puleo, David A.

    2013-01-01

    The capacity to quickly regenerate or augment bone lost as a result of resorption is crucial to ensure suitable application of prosthetics for restoring masticatory function. Calcium sulfate hemihydrate (CS)-based bone graft substitute composites containing poly(β-amino ester) (PBAE) biodegradable hydrogel particles were developed to act as a ‘tenting’ barrier to soft tissue infiltration, potentially providing adequate space to enable vertical bone regeneration. CS has long been recognized as an osteoconductive biomaterial with an excellent reputation as a biocompatible substance. Composite samples were fabricated with varying amounts (1 or 10 wt%) and sizes (53–150 or 150–250 µm) of gel particles embedded in CS. The swelling and degradation rates of PBAE gels alone were rapid, resulting in complete degradation in less than 24 hours, an important characteristic to aid in controlled release of drug. MicroCT images revealed a homogeneous distribution of gel particles within the CS matrix. All CS samples degraded via surface erosion, with the amount of gel particles (i.e., 10 wt% gel particles) having only a small, but significant, effect on the dissolution rate (4% vs. 5% per day). Compression testing determined that the amount, but not the size, of gel particles had a significant effect on the overall strength of the composites. As much as a 75% drop in strength was seen with a 10 wt% loading of particles. A pilot study using PBAE particles loaded with the multipotential drug curcumin demonstrated sustained release of drug from CS composites. By adjusting the amount and/or size of the biodegradable gel particles embedded in CS, mechanical strength and degradation rates of the composites, as well as the drug release kinetics, can be tuned to provide sufficient, multi-functional ‘space-making’ bone grafting substitutes. PMID:23811276

  4. Incorporation of fluorescent enzyme substrates in agarose gel for in situ zymography.

    PubMed

    Yi, C F; Gosiewska, A; Burtis, D; Geesin, J

    2001-04-01

    The currently available methods for the detection of proteases in tissue sections are characterized by limited substrate specificity and low sensitivity and are also cumbersome. We have developed a novel in situ zymography method that uses a synthetic substrate conjugated to a fluorescent tag for detection of proteases in tissue sections. In the presence of active enzyme, the fluorescent tag is cleaved off from the substrate peptide chain resulting in an approximately 100-fold increase in the fluorescent signal. In order to minimize the diffusion of the fluorescent tag, the substrate is incorporated into 1% agarose prior to overlaying onto the tissue section. This method retains the morphological details of the tissue section, is highly sensitive and specific for the designated peptide sequence, and provides information regarding the functional status of the enzyme. Thus, this method could be used for detection and monitoring of enzymatic activity in tissue sections for a variety of applications.

  5. Fractionation of SWNT/nucleic acid complexes by agarose gel electrophoresis.

    PubMed

    Vetcher, Alexandre A; Srinivasan, Srimeenakshi; Vetcher, Ivan A; Abramov, Semen M; Kozlov, Mikhail; Baughman, Ray H; Levene, Stephen D

    2006-08-28

    We show that aqueous dispersions of single-walled carbon nanotubes (SWNTs), prepared with the aid of nucleic acids (NAs) such as RNA or DNA, can be separated into fractions using agarose gel electrophoresis. In a DC electric field, SWNT/NA complexes migrate in the gel in the direction of positive potential to form well-defined bands. Raman spectroscopy as a function of band position shows that nanotubes having different spectroscopic properties possess different electrophoretic mobilities. The migration patterns for SWNT/RNA and SWNT/DNA complexes differ. Parallel elution of the SWNT/NA complexes from the gel during electrophoresis and subsequent characterization by AFM reveals differences in nanotube diameter, length and curvature. The results suggest that fractionation of nanotubes can be achieved by this procedure. We discuss factors affecting the mobility of the nanotube complexes and propose analytical applications of this technique.

  6. A New Organic Dye-Based Staining for The Detection of Plant DNA in Agarose Gels.

    PubMed

    Sönmezoğlu, Özlem Ateş; Özkay, Kerime

    2015-01-01

    Ethidium bromide (EtBr) is used to stain DNA in agarose gel electrophoresis, but this dye is mutagenic and carcinogenic. We investigated N-719, which is a visible, reliable and organic Ruthenium-based dye, and five fluorescent alternatives for staining plant DNA. For prestaining and poststaining, N-719, GelRed, and SYBR Safe stained both DNA and PCR product bands as clearly as EtBr. SYBR Green I, methylene blue, and crystal violet were effective for poststaining only. The organic dye N-719 stained DNA bands as sensitively and as clearly as EtBr. Consequently, organic dyes can be used as alternatives to EtBr in plant biotechnology studies.

  7. Analysis of Replicating Mitochondrial DNA by In Organello Labeling and Two-Dimensional Agarose Gel Electrophoresis.

    PubMed

    Holt, Ian J; Kazak, Lawrence; Reyes, Aurelio; Wood, Stuart R

    2016-01-01

    Our understanding of the mechanisms of DNA replication in a broad range of organisms and viruses has benefited from the application of two-dimensional agarose gel electrophoresis (2D-AGE). The method resolves DNA molecules on the basis of size and shape and is technically straightforward. 2D-AGE sparked controversy in the field of mitochondria when it revealed replicating molecules with lengthy tracts of RNA, a phenomenon never before reported in nature. More recently, radioisotope labeling of the DNA in the mitochondria has been coupled with 2D-AGE. In its first application, this procedure helped to delineate the "bootlace mechanism of mitochondrial DNA replication," in which processed mitochondrial transcripts are hybridized to the lagging strand template at the replication fork as the leading DNA strand is synthesized. This chapter provides details of the method, how it has been applied to date and concludes with some potential future applications of the technique.

  8. Towards a more reliable comet assay: optimising agarose concentration, unwinding time and electrophoresis conditions.

    PubMed

    Azqueta, Amaya; Gutzkow, Kristine B; Brunborg, Gunnar; Collins, Andrew R

    2011-09-18

    The comet assay is now the method of choice for measuring most kinds of DNA damage in cells. However, due to the lack of a standardised protocol inter-laboratory comparisons are of limited value. The aim of this paper is to demonstrate how small changes in comet-assay variables may significantly affect the results. We examined the effect of varying agarose concentrations, alkaline unwinding time, electrophoresis time, voltage and current, by use of two cell types, viz. human peripheral blood lymphocytes and the lymphoblastoid cell line TK-6. All these variables have marked effects on assay performance and, therefore, on the determination of DNA damage. Here we identify factors of particular importance.

  9. Assaying cooperativity of protein-DNA interactions using agarose gel electrophoresis.

    PubMed

    Williams, Tanya L; Levy, Daniel L

    2013-01-01

    DNA-binding proteins play essential roles in many cellular processes. Understanding on a molecular level how these proteins interact with their cognate sequences can provide important functional insights. Here, we describe a band shift assay in agarose gel to assess the mode of protein binding to a DNA molecule containing multiple protein-binding sites. The basis for the assay is that protein-DNA complexes display retarded gel electrophoresis mobility, due to their increased molecular weight relative to free DNA. The degree of retardation is higher with increasing numbers of bound protein molecules, thereby allowing resolution of complexes with differing protein-DNA stoichiometries. The DNA is radiolabeled to allow for visualization of both unbound DNA and all the different DNA-protein complexes. We present a quantitative analysis to determine whether protein binding to multiple sites within the same DNA molecule is independent or cooperative.

  10. Analyzing modifiers of protein aggregation in C. elegans by native agarose gel electrophoresis.

    PubMed

    Holmberg, Mats; Nollen, Ellen A A

    2013-01-01

    The accumulation of specific aggregation-prone proteins during aging is thought to be involved in several diseases, most notably Alzheimer's and Parkinson's disease as well as polyglutamine expansion disorders such as Huntington's disease. Caenorhabditis elegans disease models with transgenic expression of fluorescently tagged aggregation-prone proteins have been used to screen for genetic modifiers of aggregation. To establish the role of modifying factors in the generation of aggregation intermediates, a method has been developed using native agarose gel electrophoresis (NAGE) that enables parallel screening of aggregation patterns of fluorescently labeled aggregation-prone proteins. Together with microscopy-based genetic screens this method can be used to identify modifiers of protein aggregation and characterize their molecular function. Although described here for analyzing aggregates in C. elegans, NAGE can be adjusted for use in other model organisms as well as for cultured cells.

  11. Bioactive Agarose Carbon-Nanotube Composites are Capable of Manipulating Brain–Implant Interface

    PubMed Central

    Lewitus, Dan Y.; Smith, Karen L.; Landers, John; Neimark, Alexander V.; Kohn, Joachim

    2014-01-01

    Composite electrodes made of the polysaccharide agarose and carbon nanotube fibers (A-CNE) have shown potential to be applied as tissue-compatible, micro-electronic devices. In the present work, A-CNEs were functionalized using neuro-relevant proteins (laminin and alpha-melanocyte stimulating hormone) and implanted in brain tissue for 1 week (acute response) and 4 weeks (chronic response). Qualitative and quantitative analysis of neuronal and immunological responses revealed significant changes in immunological response to implanted materials depending on the type of biomolecule used. The potential to manipulate tissue response through the use of an anti-inflammatory protein, alpha-melanocyte stimulating hormone, was shown in the reduction of astroglia presence near the implant site during the glial scar formation. These results suggest that A-CNEs, which are soft, flexible, and easily made bioactive, have the ability to modify brain tissue response through surface modification as a function of the biomolecule used. PMID:25382868

  12. New in situ crosslinking chemistries for hydrogelation

    NASA Astrophysics Data System (ADS)

    Roberts, Meredith Colleen

    Over the last half century, hydrogels have found immense value as biomaterials in a vast number of biomedical and pharmaceutical applications. One subset of hydrogels receiving increased attention is in situ forming gels. Gelling by either bioresponsive self-assembly or mixing of binary crosslinking systems, these technologies are useful in minimally invasive applications as well as drug delivery systems in which the sol-to-gel transition aids the formulation's performance. Thus far, the field of in situ crosslinking hydrogels has received limited attention in the development of new crosslinking chemistries. Moreover, not only does the chemical nature of the crosslinking moieties allow these systems to perform in situ, but they contribute dramatically to the mechanical properties of the hydrogel networks. For example, reversible crosslinks with finite lifetimes generate dynamic viscoelastic gels with time-dependent properties, whereas irreversible crosslinks form highly elastic networks. The aim of this dissertation is to explore two new covalent chemistries for their ability to crosslink hydrogels in situ under physiological conditions. First, reversible phenylboronate-salicylhydroxamate crosslinking was implemented in a binary, multivalent polymeric system. These gels formed rapidly and generated hydrogel networks with frequency-dependent dynamic rheological properties. Analysis of the composition-structure-property relationships of these hydrogels---specifically considering the effects of pH, degree of polymer functionality, charge of the polymer backbone and polymer concentration on dynamic theological properties---was performed. These gels demonstrate diverse mechanical properties, due to adjustments in the binding equilibrium of the pH-sensitive crosslinks, and thus have the potential to perform in a range of dynamic or bioresponsive applications. Second, irreversible catalyst-free "click" chemistry was employed in the hydrogelation of multivalent azide

  13. Rapid self-integrating, injectable hydrogel for tissue complex regeneration

    PubMed Central

    Hou, Sen; Wang, Xuefei; Park, Sean; Jin, Xiaobing

    2015-01-01

    A novel rapid self-integrating, injectable, and bio-erodible hydrogel is developed for tissue complex regeneration. The figure shows the self-integration of the hydrogel pieces to form various structures. In the figure, some hydrogel disks were dyed pink with rodamine and the others were left with the original light yellow color to visualize the interfaces (scale bar=5mm). This hydrogel is demonstrated to engineer cartilage-bone complex. PMID:25946414

  14. Comparison of potassium and sodium binding in vivo and in agarose samples using TQTPPI pulse sequence

    NASA Astrophysics Data System (ADS)

    Schepkin, Victor D.; Neubauer, Andreas; Nagel, Armin M.; Budinger, Thomas F.

    2017-04-01

    Potassium and sodium specific binding in vivo were explored at 21.1 T by triple quantum (TQ) magnetic resonance (MR) signals without filtration to achieve high sensitivities and precise quantifications. The pulse sequence used time proportional phase increments (TPPI). During simultaneous phase-time increments, it provided total single quantum (SQ) and TQ MR signals in the second dimension at single and triple quantum frequencies, respectively. The detection of both TQ and SQ signals was performed at identical experimental conditions and the resulting TQ signal equals 60 ± 3% of the SQ signal when all ions experience sufficient time for binding. In a rat head in vivo the TQ percentage relative to SQ for potassium is 41.5 ± 3% and for sodium is 16.1 ± 1%. These percentages were compared to the matching values in an agarose tissue model with MR relaxation times similar to those of mammalian brain tissue. The sodium TQ signal in agarose samples decreased in the presence of potassium, suggesting a competitive binding of potassium relative to sodium ions for the same binding sites. The TQTPPI signals correspond to almost two times more effective binding of potassium than sodium. In vivo, up to ∼69% of total potassium and ∼27% of total sodium can be regarded as bound or experiencing an association time in the range of several milliseconds. Experimental data analyses show that more than half of the in vivo total sodium TQ signal could be from extracellular space, which is an important factor for quantification of intracellular MR signals.

  15. Comparative assessment of intrinsic mechanical stimuli on knee cartilage and compressed agarose constructs.

    PubMed

    Completo, A; Bandeiras, C; Fonseca, F

    2017-03-17

    A well-established cue for improving the properties of tissue-engineered cartilage is mechanical stimulation. However, the explicit ranges of mechanical stimuli that correspond to favorable metabolic outcomes are elusive. Usually, these outcomes have only been associated with the applied strain and frequency, an oversimplification that can hide the fundamental relationship between the intrinsic mechanical stimuli and the metabolic outcomes. This highlights two important key issues: the firstly is related to the evaluation of the intrinsic mechanical stimuli of native cartilage; the second, assuming that the intrinsic mechanical stimuli will be important, deals with the ability to replicate them on the tissue-engineered constructs. This study quantifies and compares the volume of cartilage and agarose subjected to a given magnitude range of each intrinsic mechanical stimulus, through a numerical simulation of a patient-specific knee model coupled with experimental data of contact during the stance phase of gait, and agarose constructs under direct-dynamic compression. The results suggest that direct compression loading needs to be parameterized with time-dependence during the initial culture period in order to better reproduce each one of the intrinsic mechanical stimuli developed in the patient-specific cartilage. A loading regime which combines time periods of low compressive strain (5%) and frequency (0.5Hz), in order to approach the maximal principal strain and fluid velocity stimulus of the patient-specific cartilage, with time periods of high compressive strain (20%) and frequency (3Hz), in order to approach the pore pressure values, may be advantageous relatively to a single loading regime throughout the full culture period.

  16. Analysis of mucosal mucins separated by SDS-urea agarose polyacrylamide composite gel electrophoresis.

    PubMed

    Issa, Samah M A; Schulz, Benjamin L; Packer, Nicolle H; Karlsson, Niclas G

    2011-12-01

    Efficient separation of mucins (200 kDa-2 MDa) was demonstrated using gradient SDS agarose/polyacrylamide composite gel electrophoresis (SDS-AgPAGE). Inclusion of urea (SDS-UAgPAGE) in the gels casting were shown to have no effect on the migration of mucins in the gel and allowed casting of gel at room temperature. This simplified the procedure for multiple casting of agarose polyacrylamide gradients and increased reproducibility of these gels. Hence, the implementation of urea makes the technique applicable for high throughput isolation and screening of mucin oligosaccharides by LC-MS after releasing the oligosaccharides from isolated, blotted mucin subpopulations. It was also shown that the urea addition had no effect on other supporting applications such as western and lectin blotting. In addition, identification of the mucin protein after tryptic digestion and LC-MS was possible and no protein carbamylation due to the presence of urea in the gel was detected. LC-MS software developed for metabolomic analysis was used for O-linked oligosaccharide detection and differential display of various mucin samples. Using this method, heterogeneous glycosylation of mucins and mucin-type molecules isolated by SDS-AgPAGE and SDS-UAgPAGE was shown to consist of more than 80 different components in a single band, and in the extreme cases, up to 300-500 components (MUC5B/AC from saliva and sputum and). Metabolomic software was also used to show that the migration of mucin isoforms within the gel is due to heterogeneous size distribution of the oligosaccharides, with the slower migrating bands enriched in high-molecular-weight oligosaccharides.

  17. Cultivation of agarose-based microfluidic hydrogel promotes the development of large, full-thickness, tissue-engineered articular cartilage constructs.

    PubMed

    Goldman, Stephen M; Barabino, Gilda A

    2017-02-01

    The fabrication of tissue-engineered constructs of clinically relevant sizes continues to be plagued by poor nutrient transport to the interior of the construct. Consequences of poor mass transfer to the construct core include large gradients in cell viability and matrix deposition, as well as inadequate mechanical functionality. Prior literature has shown that embedded microfluidic channels offer the potential to control the spatial and temporal presentation of hydrodynamic and chemical cues within the developing tissue construct toward improved mass transfer. The current state of the art in microfluidic constructs, however, has fallen short of achieving sufficient thickness and robustness of constructs for further development towards translation. Towards this goal, we designed a microfluidic tissue construct and established bioprocessing conditions to meet nutrient transport requirements of a large, full-thickness, articular cartilage construct over a 2 week culture period. Our microfluidic constructs of 2.5 and 5 mm thicknesses showed enhanced cell proliferation relative to statically cultured constructs. These constructs, which are both thick and robust to culture periods of sufficient length to support extracellular matrix development, represent an important improvement over previously reported constructs which were thinner and lacking in extracellular matrix (most likely attributable to too-short culture periods). Copyright © 2014 John Wiley & Sons, Ltd.

  18. Stable Li-ion battery anodes by in-situ polymerization of conducting hydrogel to conformally coat silicon nanoparticles.

    PubMed

    Wu, Hui; Yu, Guihua; Pan, Lijia; Liu, Nian; McDowell, Matthew T; Bao, Zhenan; Cui, Yi

    2013-01-01

    Silicon has a high-specific capacity as an anode material for Li-ion batteries, and much research has been focused on overcoming the poor cycling stability issue associated with its large volume changes during charging and discharging processes, mostly through nanostructured material design. Here we report incorporation of a conducting polymer hydrogel into Si-based anodes: the hydrogel is polymerized in-situ, resulting in a well-connected three-dimensional network structure consisting of Si nanoparticles conformally coated by the conducting polymer. Such a hierarchical hydrogel framework combines multiple advantageous features, including a continuous electrically conductive polyaniline network, binding with the Si surface through either the crosslinker hydrogen bonding with phytic acid or electrostatic interaction with the positively charged polymer, and porous space for volume expansion of Si particles. With this anode, we demonstrate a cycle life of 5,000 cycles with over 90% capacity retention at current density of 6.0 A g(-1).

  19. Molecular dynamic simulations of the water absorbency of hydrogels.

    PubMed

    Ou, Xiang; Han, Qiang; Dai, Hui-Hui; Wang, Jiong

    2015-09-01

    A polymer gel can imbibe solvent molecules through surface tension effect. When the solvent happens to be water, the gel can swell to a large extent and forms an aggregate called hydrogel. The large deformation caused by such swelling makes it difficult to study the behaviors of hydrogels. Currently, few molecular dynamic simulation works have been reported on the water absorbing mechanism of hydrogels. In this paper, we first use molecular dynamic simulation to study the water absorbing mechanism of hydrogels and propose a hydrogel-water interface model to study the water absorbency of the hydrogel surface. Also, the saturated water content and volume expansion rate of the hydrogel are investigated by building a hydrogel model with different cross-linking degree and by comparing the water absorption curves under different temperatures. The sample hydrogel model used consists of Polyethylene glycol diglycidyl ether (PEGDGE) as epoxy and the Jeffamine, poly-oxy-alkylene-amines, as curing agent. The conclusions obtained are useful for further investigation on PEGDGE/Jeffamine hydrogel. Moreover, the simulation methods, including hydrogel-water interface modeling, we first propose are also suitable to study the water absorbing mechanism of other hydrogels.

  20. 4D Printing with Mechanically Robust, Thermally Actuating Hydrogels.

    PubMed

    Bakarich, Shannon E; Gorkin, Robert; in het Panhuis, Marc; Spinks, Geoffrey M

    2015-06-01

    A smart valve is created by 4D printing of hydrogels that are both mechanically robust and thermally actuating. The printed hydrogels are made up of an interpenetrating network of alginate and poly(N-isopropylacrylamide). 4D structures are created by printing the "dynamic" hydrogel ink alongside other static materials.

  1. Hydrogels for ocular drug delivery and tissue engineering

    PubMed Central

    Fathi, Marzieh; Barar, Jaleh; Aghanejad, Ayuob; Omidi, Yadollah

    2015-01-01

    Hydrogels, as crosslinked polymeric three dimensional networks, possess unique structure and behavior in response to the internal and/or external stimuli. As a result, they offer great prospective applications in drug delivery, cell therapy and human tissue engineering. Here, we highlight the potential of hydrogels in prolonged intraocular drug delivery and ocular surface therapy using stem cells incorporated hydrogels. PMID:26929918

  2. Multifunctional inverse opal particles for drug delivery and monitoring

    NASA Astrophysics Data System (ADS)

    Zhang, Bin; Cheng, Yao; Wang, Huan; Ye, Baofen; Shang, Luoran; Zhao, Yuanjin; Gu, Zhongze

    2015-06-01

    Particle-based delivery systems have a demonstrated value for drug discovery and development. Here, we report a new type of particle-based delivery system that has controllable release and is self-monitoring. The particles were composed of poly(N-isopropylacrylamide) (pNIPAM) hydrogel with an inverse opal structure. The presence of macropores in the particles provides channels for active drug loading and release from the materials.Particle-based delivery systems have a demonstrated value for drug discovery and development. Here, we report a new type of particle-based delivery system that has controllable release and is self-monitoring. The particles were composed of poly(N-isopropylacrylamide) (pNIPAM) hydrogel with an inverse opal structure. The presence of macropores in the particles provides channels for active drug loading and release from the materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02324f

  3. Ag@AgI, core@shell structure in agarose matrix as hybrid: synthesis, characterization, and antimicrobial activity.

    PubMed

    Ghosh, Somnath; Saraswathi, A; Indi, S S; Hoti, S L; Vasan, H N

    2012-06-05

    A novel in situ core@shell structure consisting of nanoparticles of Ag (Ag Nps) and AgI in agarose matrix (Ag@AgI/agarose) has been synthesized as a hybrid, in order to have an efficient antibacterial agent for repetitive usage with no toxicity. The synthesized core@shell structure is very well characterized by XRD, UV-visible, photoluminescence, and TEM. A detailed antibacterial studies including repetitive cycles are carried out on Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria in saline water, both in dark and on exposure to visible light. The hybrid could be recycled for the antibacterial activity and is nontoxic toward human cervical cancer cells (HeLa cells). The water insoluble Ag@AgI in agarose matrix forms a good coating on quartz, having good mechanical strength. EPR and TEM studies are carried out on the Ag@AgI/agarose and the bacteria, respectively, to elucidate a possible mechanism for killing of the bacteria.

  4. Influence of pinning effects on the electrochemical formation of silver patterns in agarose-containing sols and gels.

    PubMed

    Pasquale, M A; Saracco, G P; Marchiano, S L; Arvia, A J

    2005-11-03

    The formation of silver patterns via electrolysis from aqueous silver sulfate + x% w/v agarose sol and gel media, with and without supporting electrolyte, in a quasi-two-dimensional (2D) cylindrical cell at room temperature, is utilized as a reference system to investigate the complexity of pinning effects. From pattern morphology and electrochemical data, both delocalized and localized pinning in the bulk dominate the drift of the growth front, depending on the concentration of agarose in the heterogeneous media. Delocalized pinning results from mobile, small agarose aggregates at the growth front and from their accumulation by the front drift. For gels, localized pinning comes from their own percolated structure. A depinning/pinning transition is observed in going from sols to gels. The relative contribution of diffusion and advection in mass-transport-controlled silver electrodeposition depends on the plating bath composition. On the other hand, silver ion attachment to the cathode appears to be interfered with by some screening caused by weakly adsorbed, mobile agarose aggregates at the metal surface without slowing down the rate of the electron-transfer step at the cathode. Their relative contribution of a delocalized, localized pinning and screening effect to a great extent determines the morphology and transition in the growth mode of silver patterns in both media. The analysis of charge and current transients and the corresponding silver pattern morphologies for open and dense radial patterns is made. Results are qualitatively simulated with a novel, rather simple cellular automaton algorithm.

  5. Immobilization of Lipases on Heterofunctional Octyl-Glyoxyl Agarose Supports: Improved Stability and Prevention of the Enzyme Desorption.

    PubMed

    Rueda, N; Dos Santos, J C S; Torres, R; Ortiz, C; Barbosa, O; Fernandez-Lafuente, R

    2016-01-01

    Lipases are among the most widely used enzymes in industry. Here, a novel method is described to rationally design the support matrix to retain the enzyme on the support matrix without leaching and also activate the enzyme for full activity retention. Lipases are interesting biocatalysts because they show the so-called interfacial activation, a mechanism of action that has been used to immobilize lipases on hydrophobic supports such as octyl-agarose. Thus, adsorption of lipases on hydrophobic surfaces is very useful for one step purification, immobilization, hyperactivation, and stabilization of most lipases. However, lipase molecules may be released from the support under certain conditions (high temperature, organic solvents), as there are no covalent links between the enzyme and the support matrix. A heterofunctional support has been proposed in this study to overcome this problem, such as the heterofunctional glyoxyl-octyl agarose beads. It couples the numerous advantages of the octyl-agarose support to covalent immobilization and creates the possibility of using the biocatalyst under any experimental conditions without risk of enzyme desorption and leaching. This modified support may be easily prepared from the commercially available octyl-agarose. Preparation of this useful support and enzyme immobilization on it via covalent linking is described here. The conditions are described to increase the possibility of achieving at least one covalent attachment between each enzyme molecule and the support matrix.

  6. Epithelial and stromal developmental patterns in a novel substitute of the human skin generated with fibrin-agarose biomaterials.

    PubMed

    Carriel, Víctor; Garzón, Ingrid; Jiménez, Jose-María; Oliveira, Ana-Celeste-Ximenes; Arias-Santiago, Salvador; Campos, Antonio; Sánchez-Quevedo, Maria-Carmen; Alaminos, Miguel

    2012-01-01

    Development of human skin substitutes by tissue engineering may offer new therapeutic alternatives to the use of autologous tissue grafts. For that reason, it is necessary to investigate and develop new biocompatible biomaterials that support the generation of a proper human skin construct. In this study, we generated a novel model of bioengineered human skin substitute using human cells obtained from skin biopsies and fibrin-agarose biomaterials and we evaluated this model both at the ex vivo and the in vivo levels. Once the dermal fibroblasts and the epithelial keratinocytes were isolated and expanded in culture, we used fibrin-agarose scaffolds for the development of a full-thickness human skin construct, which was evaluated after 1, 2, 3 and 4 weeks of development ex vivo. The skin substitutes were then grafted onto immune-deficient nude mice and analyzed at days 10, 20, 30 and 40 postimplantation using transmission electron microscopy, histochemistry and immunofluorescence. The results demonstrated that the fibrin-agarose artificial skin had adequate biocompatibility and proper biomechanical properties. A proper development of both the bioengineered dermis and epidermis was found after 30 days in vivo, although the tissues kept ex vivo and those implanted in the animal model for 10 or 20 days showed lower levels of differentiation. In summary, our model of fibrin-agarose skin equivalent was able to reproduce the structure and histological architecture of the native human skin, especially after long-term in vivo implantation, suggesting that these tissues could reproduce the native skin.

  7. Photothermal Microneedle Etching: Improved Three-Dimensional Microfabrication Method for Agarose Gel for Topographical Control of Cultured Cell Communities

    NASA Astrophysics Data System (ADS)

    Moriguchi, Hiroyuki; Yasuda, Kenji

    2006-08-01

    We have developed a new three-dimensional (3D) microfabrication method for agarose gel, photothermal microneedle etching (PTMNE), by means of an improved photothermal spot heating using a focused 1064 nm laser beam for melting a portion of the agarose layer at the tip of the microneedle, where a photoabsorbent chromium layer is coated to be heated. The advantage of this method is that it allows the 3D control of the melting topography within the thick agarose layer with a 2 μm resolution, whereas conventional photothermal etching can enable only two-dimensional (2D) control on the surface of the chip. By this method, we can form the spheroid clusters of particular cells from isolated single cells without any physical contact with other cells in other chambers, which is important for measuring the community effect of the cell group from isolated single cells. When we set single cancer cells in microchambers of 100 μm in diameter, formed in a 50-μm-thick agarose layer, we observed that they grew, divided, and formed spheroid clusters of cells in each microchamber. The result indicates the potential of this method to be a fundamental technique in the research of multicellular spherical clusters of cells for checking the community effect of cells in 3D structures, such as the permeabilities of chemicals and substrates into the cluster, which is complementary to conventional 2D dish cultivation and can contribute to the cell-based screening of drugs.

  8. Electrode films of porous agarose: The effects of physical structure on electron transport processes. [Impregnated with Nafion; immobilized electroactive species

    SciTech Connect

    Moran, K.D.

    1988-02-01

    Potential use of chemically modified electrodes in electrocatalysis has stimulated interest in creation and characterization of electrode films for reagent immobilization. We have created two highly porous electrocatalyst support matrices, with high rates of electron transport. Both are based on immobilization of reagents in agarose gel. In one case, Nafion was impregnated into agarose gel films. Diffusion of methyl viologen in Nafionagarose matrices are higher than in Nafion. In Nafion, the diffusion coefficient decreases with increasing methyl viologen concentration, while in Nafionagarose, the opposite dependence is observed. The faster rate of electron transport in Nafionagarose films is related to the heterogeneous structure and the coupling of the diffusion pathways. In the second application of agarose gels as an electrode coating material, agarose hydroxyl groups were activated in 1,1'carbonyldiimidazole and subsequently reacted with amine derivatives of electroactive mediators. Electron transport between the electroactive sites in the gel is very rapid (on the order of 10/sup -7/ cm/sup 2/s. Interpreting the data in light of the Dahms-Ruff description of electron transport shows that the rate of electron transport through both ferrocene and viologen derivatized gels is limited by the rate of electron self-exchange of the species. 22 figs., 15 tabs

  9. Comparison between agarose gel electrophoresis and capillary electrophoresis for variable numbers of tandem repeat typing of Mycobacterium tuberculosis.

    PubMed

    Yokoyama, Eiji; Kishida, Kazunori; Uchimura, Masako; Ichinohe, Sadato

    2006-06-01

    Variable numbers of tandem repeat (VNTR) typing of Mycobacterium tuberculosis was performed on 54 strains including 23 strains derived from 9 outbreaks. PCR amplicon sizes of 12 mycobacterial interspersed repetitive unit tandem repeat loci were measured using both agarose gel electrophoresis and capillary electrophoresis. Similarities using agarose gel electrophoresis of Euclidian distances among the 23 strains derived from the 9 outbreaks were significantly lower than that using capillary electrophoresis (Wilcoxon signed ranks test, P < 0.01). By clustering analysis using unweighted pair group method using arithmetic averages, all of the 23 strains derived from the 9 outbreaks were each clustered with more than 90% similarities based on the distance using capillary electrophoresis. In contrast, differential clusters with more than 90% similarity were observed with only 7 strains derived from 3 outbreaks when analyzed by agarose gel electrophoresis. These results indicated that measurement of PCR amplicon size of tandem repeat loci should be carried out using capillary electrophoresis and that agarose gel electrophoresis is not suitable for clustering analysis of M. tuberculosis VNTR typing.

  10. Electrophoresis of /sup 35/S-labeled proteoglycans of polyacrylamide-agarose composite gels and their visualization by fluorography

    SciTech Connect

    Carney, S.L.; Bayliss, M.T.; Collier, J.M.; Muir, H.

    1986-01-01

    Techniques for the electrophoresis of /sup 35/S-labeled proteoglycans on polyacrylamide-agarose gel slabs and subsequent fixation, impregnation, and fluorography of such electrophoretograms have been developed. The procedure permits the examination of newly synthesized proteoglycan subspecies using a rapid technique, previously unavailable for these labeled molecules.

  11. Rapid drug susceptibility test of Mycobacterium tuberculosis using microscopic time-lapse imaging in an agarose matrix.

    PubMed

    Choi, Jungil; Yoo, Jungheon; Kim, Ki-Jung; Kim, Eun-Geun; Park, Kyung Ock; Kim, Hyejin; Kim, Haeun; Jung, Hyunju; Kim, Taeyoung; Choi, Myungjin; Kim, Hee Chan; Ryoo, Sungweon; Jung, Yong-Gyun; Kwon, Sunghoon

    2016-03-01

    Tuberculosis (TB) is a major global health problem, and multi-drug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) are spreading throughout the world. However, conventional drug susceptibility test (DST) methods, which rely on the detection of the colony formation on a solid medium, require 1-2 months to the result. A rapid and accurate DST is necessary to identify patients with drug-resistant TB and treat them with appropriate drugs. Here, we used microscopic imaging of Mycobacterium tuberculosis (MTB) immobilized in an agarose matrix for a rapid DST. The agarose matrix, which was molded in a microfluidic chip, was inoculated with MTB, and TB drugs in liquid culture medium diffused throughout the agarose to reach the MTB immobilized in the agarose matrix. After the responses of MTB to drugs were tracked with an automated microscopic system, an image-processing program automatically determined the susceptibility and resistance of MTB to specific doses of TB drugs. The automatic DST system was able to assess the drug susceptibility of various drug-resistant clinical TB strains within 9 days with an accuracy comparable to that of conventional method. Our rapid DST method based on microscopic time-lapse imaging greatly reduces the time required for a DST and can be used to rapidly and accurately treat TB patients.

  12. No evidence of viral transmission following long-term implantation of agarose encapsulated porcine islets in diabetic dogs.

    PubMed

    Gazda, Lawrence S; Vinerean, Horatiu V; Laramore, Melissa A; Hall, Richard D; Carraway, Joseph W; Smith, Barry H

    2014-01-01

    We have previously described the use of a double coated agarose-agarose porcine islet macrobead for the treatment of type I diabetes mellitus. In the current study, the long-term viral safety of macrobead implantation into pancreatectomized diabetic dogs treated with pravastatin (n = 3) was assessed while 2 dogs served as nonimplanted controls. A more gradual return to preimplant insulin requirements occurred after a 2nd implant procedure (days 148, 189, and >652) when compared to a first macrobead implantation (days 9, 21, and 21) in all macrobead implanted animals. In all three implanted dogs, porcine C-peptide was detected in the blood for at least 10 days following the first implant and for at least 26 days following the second implant. C-peptide was also present in the peritoneal fluid of all three implanted dogs at 6 months after 2nd implant and in 2 of 3 dogs at necropsy. Prescreening results of islet macrobeads and culture media prior to transplantation were negative for 13 viruses. No evidence of PERV or other viral transmission was found throughout the study. This study demonstrates that the long-term (2.4 years) implantation of agarose-agarose encapsulated porcine islets is a safe procedure in a large animal model of type I diabetes mellitus.

  13. Inverse opals of molecularly imprinted hydrogels for the detection of bisphenol A and pH sensing.

    PubMed

    Griffete, Nébéwia; Frederich, Hugo; Maître, Agnès; Ravaine, Serge; Chehimi, Mohamed M; Mangeney, Claire

    2012-01-10

    Inverse opal films of molecularly imprinted polymers (MIP) were elaborated using the colloidal crystal template method. The colloidal crystals of silica particles were built by the Langmuir-Blodgett technique, allowing a perfect control of the film thickness. Polymerization in the interspaces of the colloidal crystal in the presence of bisphenol A (BPA) and removal of the used template provides 3D-ordered macroporous methacrylic acid-based hydrogel films in which nanocavities derived from bisphenol A are distributed within the thin walls of the inverse opal hydrogel. The equilibrium swelling properties of the nonimprinted (NIPs) and molecularly imprinted polymers (MIPs) were studied as a function of pH and bisphenol A concentration, while the molecular structures of the bulk hydrogels were analyzed using a cross-linked network structure theory. This study showed an increase in nanopore (mesh) size in the MIPs after BPA extraction as compared to NIPs, in agreement with the presence of nanocavities left by the molecular imprints of the template molecule. The resulting inverse opals were found to display large responses to external stimuli (pH or BPA) with Bragg diffraction peak shifts depending upon the hydrogel film thickness. The film thickness was therefore shown to be a critical parameter for improving the sensing capacities of inverse opal hydrogel films deposited on a substrate.

  14. Exploiting Bisphosphonate-Bioactive-Glass Interactions for the Development of Self-Healing and Bioactive Composite Hydrogels.

    PubMed

    Diba, Mani; An, Jie; Schmidt, Stephan; Hembury, Mathew; Ossipov, Dmitri; Boccaccini, Aldo R; Leeuwenburgh, Sander C G

    2016-12-01

    Hydrogels are widely recognized as promising candidates for various biomedical applications, such as tissue engineering. Recently, extensive research efforts have been devoted to the improvement of the biological and mechanical performance of hydrogel systems by incorporation of functional groups and/or inorganic particles in their composition. Bisphosphonates are a class of drugs, commonly used for treatment of osteoporosis, which exhibit a strong binding affinity for hydroxyapatite. In this study, the binding affinity of a bisphosphonate-functionalized polymer, hyaluronan, toward a bioactive glass (i.e., 45S5 Bioglass) is evaluated using force-distance measurements with atomic force microscopy. The strong interaction between bisphosphonate and bioactive glass is then exploited to develop organic-inorganic composite hydrogels and the viscoelastic and self-healing ability of these materials are investigated. Finally, the stability and mineralization behavior of these hydrogels are evaluated in simulated body fluid. Following this approach, injectable, bioactive and self-healing organic-inorganic composite hydrogels are produced, which mineralize abundantly and rapidly in simulated body fluid. These properties render these composite gels suitable for applications in bone-tissue engineering.

  15. Design of Thermally Responsive Polymeric Hydrogels for Brackish Water Desalination: Effect of Architecture on Swelling, Deswelling, and Salt Rejection.

    PubMed

    Ali, Wael; Gebert, Beate; Hennecke, Tobias; Graf, Karlheinz; Ulbricht, Mathias; Gutmann, Jochen S

    2015-07-29

    In this work, we explore the ability of utilizing hydrogels synthesized from a temperature-sensitive polymer and a polyelectrolyte to desalinate salt water by means of reversible thermally induced absorption and desorption. Thus, the influence of the macromolecular architecture on the swelling/deswelling behavior for such hydrogels was investigated by tailor-made network structures. To this end, a series of chemically cross-linked polymeric hydrogels were synthesized via free radical-initiated copolymerization of sodium acrylate (SA) with the thermoresponsive comonomer N-isopropylacrylamide (NIPAAm) by realizing different structural types. In particular, two different polyNIPAAm macromonomers, either with one acrylate function at the chain end or with additional acrylate functions as side groups were synthesized by controlled polymerization and subsequent polymer-analogous reaction and then used as building blocks. The rheological behaviors of hydrogels and their estimated mesh sizes are discussed. The performance of the hydrogels in terms of swelling and deswelling in both deionized water (DI) and brackish water (2 g/L NaCl) was measured as a function of cross-linking degree and particle size. The salt content could be reduced by 23% in one cycle by using the best performing material.

  16. An extra peptide within the catalytic module of a β-agarase affects the agarose degradation pattern.

    PubMed

    Han, Wen-Jun; Gu, Jing-Yan; Liu, Hui-Hui; Li, Fu-Chuan; Wu, Zhi-Hong; Li, Yue-Zhong

    2013-03-29

    Agarase hydrolyzes agarose into a series of oligosaccharides with repeating disaccharide units. The glycoside hydrolase (GH) module of agarase is known to be responsible for its catalytic activity. However, variations in the composition of the GH module and its effects on enzymatic functions have been minimally elucidated. The agaG4 gene, cloned from the genome of the agarolytic Flammeovirga strain MY04, encodes a 503-amino acid protein, AgaG4. Compared with elucidated agarases, AgaG4 contains an extra peptide (Asn(246)-Gly(302)) within its GH module. Heterologously expressed AgaG4 (recombinant AgaG4; rAgaG4) was determined to be an endo-type β-agarase. The protein degraded agarose into neoagarotetraose and neoagarohexaose at a final molar ratio of 1.5:1. Neoagarooctaose was the smallest substrate for rAgaG4, whereas neoagarotetraose was the minimal degradation product. Removing the extra fragment from the GH module led to the inability of the mutant (rAgaG4-T57) to degrade neoagarooctaose, and the final degradation products of agarose by the truncated protein were neoagarotetraose, neoagarohexaose, and neoagarooctaose at a final molar ratio of 2.7:2.8:1. The optimal temperature for agarose degradation also decreased to 40 °C for this mutant. Bioinformatic analysis suggested that tyrosine 276 within the extra fragment was a candidate active site residue for the enzymatic activity. Site-swapping experiments of Tyr(276) to 19 various other amino acids demonstrated that the characteristics of this residue were crucial for the AgaG4 degradation of agarose and the cleavage pattern of substrate.

  17. Poly(n-vinylpyrrolidone) hydrogels: 2.Hydrogel composites as wound dressing for tropical environment

    NASA Astrophysics Data System (ADS)

    Himly, N.; Darwis, D.; Hardiningsih, L.

    1993-10-01

    POLY(N-VINYLPYRROLIDONE) HYDROGELS: 2. HYDROGEL COMPOSITES AS WOUND DRESSING FOR TROPICAL ENVIRONMENT. The effects of irradiation on hydration and other properties of poly(vinylpyrrolidone) (PVP) hydrogel composites have been investigated. The aqueous solution of vinylpyrrolidone (VP) 10 wt % was mixed with several additives such as agar and polyethylen glycol (PEG). The solution was then irradiated with gamma rays from Cobalt-60 source at room temperature. Several parameters such as elongation at break (EB), tensile strength (TS), degree of swelling (DS), water vapor transmission rate (WVTR), equilibrium water content (EWC), microbial growth and penetration test, and water activity (Aw) were analysed at room temperature of 29 ±2°C humidity of 80 ± 10%. Results show that elongation at break of hydrogel membranes with initial composition of VP with agar, VP with agar and PEG were 240 % and 250 % kGy, the equilibrium water content of membranes were 96 to 90%, whereas degree of swelling were 55 to 10. The WVTR of hydrogel membranes with initial composition of VP with agar and PEG was 70 g m -2h -1, while the water activity was 0.9. Such hydrogel membranes exhibits the following properties: They are elastic, transparent, flexible, impermeable for bacteria. They absopt a high capacity of water, attached to healthy skin but not to the wound and they are easy to remove. These properties of the hydrogel membranes allow for applying as a wound dressings in tropical environment.

  18. The synthesis of hydrogels with controlled distribution of polymer brushes in hydrogel network

    NASA Astrophysics Data System (ADS)

    Sun, YuWei; Zhou, Chao; Zhang, AoKai; Xu, LiQun; Yao, Fang; Cen, Lian; Fu, Guo-Dong

    2014-11-01

    Poly(ethylene glycol) (PEG) hydrogels with 3-dimensionally controlled well-defined poly(N-isopropylacrylamide) (poly(NIPAAm)) brushes were prepared by combined copper(I)-catalyzed azide-alkyne cycloaddition ("Click Chemistry") and atom transfer radical polymerization (ATRP). The resulting hydrogels were presented as representatives with their detailed synthesis routes and characterization. HPEG-S-poly(NIPAAm) is a hydrogel with poly(NIPAAm) brushes mainly grafted on surface, whereas HPEG-G-poly(NIPAAm) has a gradiently decreased poly(NIPAAm) brushes in their chain length from surface to inside. On the other hand, poly(NIPAAm) brushes in HPEG-U-poly(NIPAAm) are uniformly dispersed throughout the whole hydrogel network. Successful preparation of HPEG-S-poly(NIPAAm), HPEG-G-poly(NIPAAm) and HPEG-U-poly(NIPAAm) were ascertained by X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. Optical properties and thermal behaviors of these hydrogels were evaluated by UV-visible transmittance spectra and differential scanning calorimetry (DSC). Hence, the flexibility and controllability of the synthetic strategy in varying the distribution of polymer brushes and hydrogel properties was demonstrated. Hydrogels with tunable and well-defined 3-dimensional poly(NIPAAm) polymer brushes could be tailor-designed to find potential applications in smart devices or skin dressing, such as for diabetics as they have special optical and thermal behaviors.

  19. Development of a temperature-sensitive composite hydrogel for drug delivery applications.

    PubMed

    Ramanan, Ram Mohan Kripa; Chellamuthu, Prithiviraj; Tang, Liping; Nguyen, Kytai T

    2006-01-01

    To develop materials with improved controllability and specificity, we have investigated composite hydrogels with temperature-sensitive properties using photo cross-linking. Specifically, our novel composite materials are composed of nanoparticles made of poly(N-isopropylacrylamide) (PNIPAAm), temperature-sensitive hydrogels, and a photo cross-linker, poly(ethylene glycol) diacrylate (PEGDA). PNIPAAm particles were synthesized by emulsion polymerization and by varying concentration of four main factors: monomers (N-isopropylacrylamide), cross-linkers (N,N'-methylenebisacrylamide), surfactants (sodium dodecyl sulfate, SDS), and initiators (potassium persulfate). We found that the surfactant, SDS, was the most important factor affecting the particle size using the factorial design analysis. Additionally, both nano- and micro-PNIPAAm particles had excellent loading efficiency (>80% of the incubated bovine serum albumin (BSA)), and their release kinetics expressed an initial burst effect followed by a sustained release over time. Furthermore, BSA-loaded PNIPAAm nanoparticles were used to form three-dimensional gel networks by means of a photocuring process using a photo cross-linker, PEGDA, and a photoinitiator, Irgacure-2959 (I-2959). Results from scanning electron microscopy and in vitro BSA release studies from these hydrogels demonstrated that PNIPAAm nanoparticles were embedded inside the PEG polymeric matrix and the composite material was able to release BSA in response to changes in temperature. These PNIPAAm nanoparticle hydrogel networks may have advantages in applications of controlled drug delivery systems because of their temperature sensitivity and their ability of in situ photopolymerization to localize at the specific region in the body.

  20. Hydrophilic Organic Electrodes on Flexible Hydrogels.

    PubMed

    Moser, Thierry; Celma, Coralie; Lebert, Audrey; Charrault, Eric; Brooke, Robert; Murphy, Peter J; Browne, Gareth; Young, Richard; Higgs, Timothy; Evans, Drew

    2016-01-13

    Prompted by the rapidly developing field of wearable electronics, research into biocompatible substrates and coatings is intensifying. Acrylate-based hydrogel polymers have gained widespread use as biocompatible articles in applications such as contact and intraocular lenses. Surface treatments and/or coatings present one strategy to further enhance the performance of these hydrogels or even realize novel functionality. In this study, the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is deposited from the vapor phase onto hydrated hydrogel substrates and blended with biocompatibilizing coconstituents incorporating polyethylene glycol (PEG) and polydimethyl siloxane (PDMS) moieties. Plasma pretreatment of the dehydrated hydrogel substrate modifies its surface topography and chemical composition to facilitate the attachment of conductive PEDOT-based surface layers. Manipulating the vapor phase polymerization process and constituent composition, the PEDOT-based coating is engineered to be both hydrophilic (i.e. to promote biocompatibility) and highly conductive. The fabrication of this conductively coated hydrogel has implications for the future of wearable electronic devices.

  1. Robust fluidic connections to freestanding microfluidic hydrogels

    PubMed Central

    Baer, Bradly B.; Larsen, Taylor S. H.

    2015-01-01

    Biomimetic scaffolds approaching physiological scale, whose size and large cellular load far exceed the limits of diffusion, require incorporation of a fluidic means to achieve adequate nutrient/metabolite exchange. This need has driven the extension of microfluidic technologies into the area of biomaterials. While construction of perfusable scaffolds is essentially a problem of microfluidic device fabrication, functional implementation of free-standing, thick-tissue constructs depends upon successful integration of external pumping mechanisms through optimized connective assemblies. However, a critical analysis to identify optimal materials/assembly components for hydrogel substrates has received little focus to date. This investigation addresses this issue directly by evaluating the efficacy of a range of adhesive and mechanical fluidic connection methods to gelatin hydrogel constructs based upon both mechanical property analysis and cell compatibility. Results identify a novel bioadhesive, comprised of two enzymatically modified gelatin compounds, for connecting tubing to hydrogel constructs that is both structurally robust and non-cytotoxic. Furthermore, outcomes from this study provide clear evidence that fluidic interconnect success varies with substrate composition (specifically hydrogel versus polydimethylsiloxane), highlighting not only the importance of selecting the appropriately tailored components for fluidic hydrogel systems but also that of encouraging ongoing, targeted exploration of this issue. The optimization of such interconnect systems will ultimately promote exciting scientific and therapeutic developments provided by microfluidic, cell-laden scaffolds. PMID:26045731

  2. Novel self-assembled tacrolimus nanoparticles cross-linking thermosensitive hydrogels for local rheumatoid arthritis therapy.

    PubMed

    Wu, Huimin; Wang, Kaiyuan; Wang, Hanning; Chen, Fang; Huang, Wencong; Chen, Yuqi; Chen, Jiali; Tao, Jin; Wen, Xiaoguang; Xiong, Subin

    2017-01-01

    The aim was to explore the potential application of novel self-assembled nanoparticles cross-linking thermosensitive hydrogels composed of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (Soluplus) and tacr