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Sample records for composite microsphere scaffolds

  1. Multiscale patterning of a biomimetic scaffold integrated with composite microspheres.

    PubMed

    Minardi, Silvia; Sandri, Monica; Martinez, Jonathan O; Yazdi, Iman K; Liu, Xeuwu; Ferrari, Mauro; Weiner, Bradley K; Tampieri, Anna; Tasciotti, Ennio

    2014-10-15

    The ideal scaffold for regenerative medicine should concurrently mimic the structure of the original tissue from the nano- up to the macroscale and recapitulate the biochemical composition of the extracellular matrix (ECM) in space and time. In this study, a multiscale approach is followed to selectively integrate different types of nanostructured composite microspheres loaded with reporter proteins, in a multi-compartment collagen scaffold. Through the preservation of the structural cues of the functionalized collagen scaffold at the nano- and microscale, its macroscopic features (pore size, porosity, and swelling) are not altered. Additionally, the spatial confinement of the microspheres allows the release of the reporter proteins in each of the layers of the scaffold. Finally, the staged and zero-order release kinetics enables the temporal biochemical patterning of the scaffold. The versatile manufacturing of each component of the scaffold results in the ability to customize it to better mimic the architecture and composition of the tissues and biological systems.

  2. Collagen/silk fibroin composite scaffold incorporated with PLGA microsphere for cartilage repair.

    PubMed

    Wang, Jianhua; Yang, Qiu; Cheng, Niangmei; Tao, Xiaojun; Zhang, Zhihua; Sun, Xiaomin; Zhang, Qiqing

    2016-04-01

    For cartilage repair, ideal scaffolds should mimic natural extracellular matrix (ECM) exhibiting excellent characteristics, such as biocompatibility, suitable porosity, and good cell affinity. This study aimed to prepare a collagen/silk fibroin composite scaffold incorporated with poly-lactic-co-glycolic acid (PLGA) microsphere that can be applied in repairing cartilage. To obtain optimum conditions for manufacturing a composite scaffold, a scaffold composed of different collagen-to-silk fibroin ratios was evaluated by determining porosity, water absorption, loss rate in hot water, and cell proliferation. Results suggested that the optimal ratio of collagen and silk fibroin composite scaffold was 7:3. The microstructure and morphological characteristics of the obtained scaffold were also examined through scanning electron microscopy and Fourier transform infrared spectroscopy. The results of in vitro fluorescence staining of bone marrow stromal cells revealed that collagen/silk fibroin composite scaffold enhanced cell proliferation without eliciting side effects. The prepared composite scaffold incorporated with PLGA microsphere was implanted in fully thick articular cartilage defects in rabbits. Collagen/silk fibroin composite scaffold with PLGA microspheres could enhance articular cartilage regeneration and integration between the repaired cartilage and the surrounding cartilage. Therefore, this composite will be a promising material for cartilage repair and regeneration.

  3. Controlled drug release from a novel injectable biodegradable microsphere/scaffold composite based on poly(propylene fumarate).

    PubMed

    Kempen, Diederik H R; Lu, Lichun; Kim, Choll; Zhu, Xun; Dhert, Wouter J A; Currier, Bradford L; Yaszemski, Michael J

    2006-04-01

    The ideal biomaterial for the repair of bone defects is expected to have good mechanical properties, be fabricated easily into a desired shape, support cell attachment, allow controlled release of bioactive factors to induce bone formation, and biodegrade into nontoxic products to permit natural bone formation and remodeling. The synthetic polymer poly(propylene fumarate) (PPF) holds great promise as such a biomaterial. In previous work we developed poly(DL-lactic-co-glycolic acid) (PLGA) and PPF microspheres for the controlled delivery of bioactive molecules. This study presents an approach to incorporate these microspheres into an injectable, porous PPF scaffold. Model drug Texas red dextran (TRD) was encapsulated into biodegradable PLGA and PPF microspheres at 2 microg/mg microsphere. Five porous composite formulations were fabricated via a gas foaming technique by combining the injectable PPF paste with the PLGA or PPF microspheres at 100 or 250 mg microsphere per composite formulation, or a control aqueous TRD solution (200 microg per composite). All scaffolds had an interconnected pore network with an average porosity of 64.8 +/- 3.6%. The presence of microspheres in the composite scaffolds was confirmed by scanning electron microscopy and confocal microscopy. The composite scaffolds exhibited a sustained release of the model drug for at least 28 days and had minimal burst release during the initial phase of release, as compared to drug release from microspheres alone. The compressive moduli of the scaffolds were between 2.4 and 26.2 MPa after fabrication, and between 14.9 and 62.8 MPa after 28 days in PBS. The scaffolds containing PPF microspheres exhibited a significantly higher initial compressive modulus than those containing PLGA microspheres. Increasing the amount of microspheres in the composites was found to significantly decrease the initial compressive modulus. The novel injectable PPF-based microsphere/scaffold composites developed in this study

  4. Preparation and characterization of PHBV microsphere/45S5 bioactive glass composite scaffolds with vancomycin releasing function.

    PubMed

    Li, Wei; Ding, Yaping; Rai, Ranjana; Roether, Judith A; Schubert, Dirk W; Boccaccini, Aldo R

    2014-08-01

    PHBV microsphere/45S5 bioactive glass (BG) composite scaffolds with drug release function were developed for bone tissue engineering. BG-based glass-ceramic scaffolds with high porosity (94%) and interconnected pore structure prepared by foam replication method were coated with PHBV microspheres (nominal diameter=3.5 μm) produced by water-in-oil-in-water double emulsion solvent evaporation method. A homogeneous microsphere coating throughout the porous structure of scaffolds was obtained by a simple dip coating method, using the slurry of PHBV microspheres in hexane. Compressive strength tests showed that the microsphere coating slightly improved the mechanical properties of the scaffolds. It was confirmed that the microsphere coating did not inhibit the bioactivity of the scaffolds in SBF. Hydroxyapatite crystals homogeneously grew not only on the struts of the scaffolds but also on the surface of microspheres within 7 days of immersion in SBF. Vancomycin was successfully encapsulated into the PHBV microspheres. The encapsulated vancomycin was released with a dual release profile involving a relatively low initial burst release (21%) and a sustained release (1 month), which is favorable compared to the high initial burst release (77%) and short release period (4 days) measured on uncoated scaffolds. The developed bioactive composite scaffold with drug delivery function has thus the potential to be used advantageously in bone tissue engineering.

  5. Polyphosphazene/Nano-Hydroxyapatite Composite Microsphere Scaffolds for Bone Tissue Engineering

    PubMed Central

    Nukavarapu, Syam P.; Kumbar, Sangamesh G.; Brown, Justin L.; Krogman, Nicholas R.; Weikel, Arlin L.; Hindenlang, Mark D.; Nair, Lakshmi S.; Allcock, Harry R; Laurencin, Cato T.

    2009-01-01

    The non-toxic, neutral degradation products of amino acid ester polyphosphazenes make them ideal candidates for in vivo orthopaedic applications. The quest for new osteocompatible materials for load bearing tissue engineering applications has led us to investigate mechanically competent amino acid ester substituted polyphosphazenes. In this study, we have synthesized three biodegradable polyphosphazenes substituted with side groups namely leucine, valine and phenylalanine ethyl esters. Of these polymers, the phenylalanine ethyl ester substituted polyphosphazene showed the highest glass transition temperature (41.6 °C) and hence was chosen as a candidate material for forming composite microspheres with 100 nm sized hydroxyapatite (nHAp). The fabricated composite microspheres were sintered into a three-dimensional (3-D) porous scaffold by adopting a dynamic solvent sintering approach. The composite microsphere scaffolds showed compressive moduli of 46–81 MPa with mean pore diameters in the range of 86–145 µm. The three-dimensional polyphosphazene-nHAp composite microsphere scaffolds showed good osteoblast cell adhesion, proliferation and alkaline phosphatase expression, and are potential suitors for bone tissue engineering applications. PMID:18517248

  6. Composite microsphere-functionalized scaffold for the controlled release of small molecules in tissue engineering

    PubMed Central

    Pandolfi, Laura; Minardi, Silvia; Taraballi, Francesca; Liu, Xeuwu; Ferrari, Mauro; Tasciotti, Ennio

    2016-01-01

    Current tissue engineering strategies focus on restoring damaged tissue architectures using biologically active scaffolds. The ideal scaffold would mimic the extracellular matrix of any tissue of interest, promoting cell proliferation and de novo extracellular matrix deposition. A plethora of techniques have been evaluated to engineer scaffolds for the controlled and targeted release of bioactive molecules to provide a functional structure for tissue growth and remodeling, as well as enhance recruitment and proliferation of autologous cells within the implant. Recently, novel approaches using small molecules, instead of growth factors, have been exploited to regulate tissue regeneration. The use of small synthetic molecules could be very advantageous because of their stability, tunability, and low cost. Herein, we propose a chitosan–gelatin scaffold functionalized with composite microspheres consisting of mesoporous silicon microparticles and poly(dl-lactic-co-glycolic acid) for the controlled release of sphingosine-1-phospate, a small molecule of interest. We characterized the platform with scanning electron microscopy, Fourier transform infrared spectroscopy, and confocal microscopy. Finally, the biocompatibility of this multiscale system was analyzed by culturing human mesenchymal stem cells onto the scaffold. The presented strategy establishes the basis of a versatile scaffold for the controlled release of small molecules and for culturing mesenchymal stem cells for regenerative medicine applications. PMID:26977286

  7. Biocompatibility and osteogenesis of calcium phosphate composite scaffolds containing simvastatin-loaded PLGA microspheres for bone tissue engineering.

    PubMed

    Zhang, Hao-Xuan; Xiao, Gui-Yong; Wang, Xia; Dong, Zhao-Gang; Ma, Zhi-Yong; Li, Lei; Li, Yu-Hua; Pan, Xin; Nie, Lin

    2015-10-01

    By utilizing a modified solid/oil/water (s/o/w) emulsion solvent evaporation technique, calcium phosphate composite scaffolds containing simvastatin-loaded PLGA microspheres (SIM-PLGA-CPC) were prepared in this study. We characterized the morphology, encapsulation efficiency and in vitro drug release of SIM-loaded PLGA microspheres as well as the macrostructure, pore size, porosity and mechanical strength of the scaffolds. Rabbit bone mesenchymal stem cells (BMSCs) were seeded onto SIM-PLGA-CPC scaffolds, and the proliferation, morphology, cell cycle and differentiation of BMSCs were investigated using the cell counting kit-8 (CCK-8) assay, scanning electron microscopy (SEM), flow cytometry, alkaline phosphatase (ALP) activity and alizarin red S staining, respectively. The results revealed that SIM-PLGA-CPC scaffolds were biocompatible and osteogenic in vitro. To determine the in vivo biocompatibility and osteogenesis of the scaffolds, both pure PLGA-CPC scaffolds and SIM-PLGA-CPC scaffolds were implanted in rabbit femoral condyles and microradiographically and histologically investigated. SIM-PLGA-CPC scaffolds exhibited good biocompatibility and could improve the efficiency of new bone formation. All these results suggested that the SIM-PLGA-CPC scaffolds fulfilled the basic requirements of bone tissue engineering scaffold and possessed application potentials in orthopedic surgery.

  8. PHBV microspheres--PLGA matrix composite scaffold for bone tissue engineering.

    PubMed

    Huang, Wei; Shi, Xuetao; Ren, Li; Du, Chang; Wang, Yingjun

    2010-05-01

    Polymer scaffolds, particularly in the form of microspheres, have been employed to support cells growth and deliver drugs or growth factors in tissue engineering. In this study, we have established a scaffold by embedding poly (beta-hydroxybutyrate-co-beta-hydroxyvalerate) (PHBV) microspheres into poly (L-lactic-co-glycolic acid) (PLGA) matrix, according to their different solubility in acetone, with the aim of repairing bone defects. PLGA/PHBV scaffolds had good pore parameters, for example, the porosity of PLGA/30% PHBV scaffold can reach to 81.273 +/- 2.192%. Besides, the pore size distribution of the model was evaluated and the results revealed that the pore size mainly distributed between 50 mum and 200 mum. With increasing the amount of PHBV microspheres, the compressive strength of the PLGA/PHBV scaffold enhanced. The morphology of the hybrid scaffold was rougher than that of pure PLGA scaffold, which had no significant effect on the cell behavior. The in vitro evaluation suggested that the model is suitable as a scaffold for engineering bone tissue, and has the potential for further applications in drug delivery system.

  9. Levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffold for the treatment of chronic osteomyelitis with bone defects.

    PubMed

    Wang, Qi; Chen, Cheng; Liu, Wen; He, Xiaoqiang; Zhou, Nian; Zhang, Dongli; Gu, Hongchen; Li, Jidong; Jiang, Jiaxing; Huang, Wei

    2017-02-02

    Chronic osteomyelitis is a prolonged persistent disease accompanied by bone destruction and sequestrum formation, it is very difficult to treat. Antibiotic loaded polymethyl methacrylate (PMMA) has been used in clinical. However, when PMMA was implanted in the body, the deficiencies is that it is non-biodegradable and a second operation is needed. Here, we synthesize a novel levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds, and evaluated the therapeutic effect in treating chronic osteomyelitis with bone defects in rabbit model compared with bulk PMMA. X-ray, Micro CT, gross pathology as well as immunohistochemical staining were performed at predesignated time points (1, 3, 6 and 12 weeks). Our results demonstrated that the efficiency of mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds loaded with 5 mg levofloxacin was much better at treating bone defects than the other groups. This novel synthetic scaffold may provide a solution for the treatment of chronic osteomyelitis.

  10. Levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffold for the treatment of chronic osteomyelitis with bone defects

    PubMed Central

    Wang, Qi; Chen, Cheng; Liu, Wen; He, Xiaoqiang; Zhou, Nian; Zhang, Dongli; Gu, Hongchen; Li, Jidong; Jiang, Jiaxing; Huang, Wei

    2017-01-01

    Chronic osteomyelitis is a prolonged persistent disease accompanied by bone destruction and sequestrum formation, it is very difficult to treat. Antibiotic loaded polymethyl methacrylate (PMMA) has been used in clinical. However, when PMMA was implanted in the body, the deficiencies is that it is non-biodegradable and a second operation is needed. Here, we synthesize a novel levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds, and evaluated the therapeutic effect in treating chronic osteomyelitis with bone defects in rabbit model compared with bulk PMMA. X-ray, Micro CT, gross pathology as well as immunohistochemical staining were performed at predesignated time points (1, 3, 6 and 12 weeks). Our results demonstrated that the efficiency of mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds loaded with 5 mg levofloxacin was much better at treating bone defects than the other groups. This novel synthetic scaffold may provide a solution for the treatment of chronic osteomyelitis. PMID:28150731

  11. Sol-gel processed mupirocin silica microspheres loaded collagen scaffold: a synergistic bio-composite for wound healing.

    PubMed

    Perumal, Sathiamurthi; Ramadass, Satiesh kumar; Madhan, Balaraman

    2014-02-14

    Development of a bio-composite using synergistic combination is a promising strategy to address various pathological manifestations of acute and chronic wounds. In the present work, we have combined three materials viz., mupirocin as an antimicrobial drug, sol-gel processed silica microsphere as drug carrier for sustained delivery of drug and collagen, an established wound healer as scaffold. The mupirocin-loaded silica microspheres (Mu-SM) and Mu-SM loaded collagen scaffold were characterized for surface morphology, entrapment efficiency and distribution homogeneity, in vitro drug release, water uptake capacity, cell proliferation and antibacterial activity. In vivo wound healing efficacy of the bio-composite was experimented using full thickness excision wound model in Wistar albino rats. The Mu-SM incorporated collagen scaffold showed good in vitro characteristics in terms of better water uptake, sustained drug availability and antimicrobial activity. The wound closure analysis revealed that the complete epithelialisation was observed at 14.2 ± 0.44 days for Mu-SM loaded collagen, whereas this was 17.4 ± 0.44 days and 20.6 ± 0.54 days for collagen and control groups, respectively. Consequently, the synergistic strategy of combining mupirocin-loaded silica microspheres and collagen as a Mu-SM loaded collagen dressing material would be an ideal biomaterial for the treatment of surface wounds, burns and foot ulcers.

  12. Pitch carbon microsphere composite

    NASA Technical Reports Server (NTRS)

    Price, H. L.; Nelson, J. B.

    1977-01-01

    Petroleum pitch carbon microspheres were prepared by flash heating emulsified pitch and carbonizing the resulting microspheres in an inert atmosphere. Microsphere composites were obtained from a mixture of microspheres and tetraester precursor pyrrone powder. Scanning electron micrographs of the composite showed that it was an aggregate of microspheres bonded together by the pyrrone at the sphere contact points, with voids in and among the microspheres. Physical, thermal, and sorption properties of the composite are described. Composite applications could include use as a honeycomb filler in elevated-temperature load-bearing sandwich boards or in patient-treatment tables for radiation treatment of tumors.

  13. In vitro and in vivo evaluation of calcium phosphate composite scaffolds containing BMP-VEGF loaded PLGA microspheres for the treatment of avascular necrosis of the femoral head.

    PubMed

    Zhang, Hao-Xuan; Zhang, Xiu-Ping; Xiao, Gui-Yong; Hou, Yong; Cheng, Lei; Si, Meng; Wang, Shuai-Shuai; Li, Yu-Hua; Nie, Lin

    2016-03-01

    Avascular necrosis of the femoral head (ANFH) is difficult to treat due to high pressure and hypoxia, and reduced levels of growth factors such as bone morphogenetic protein (BMP), and vascular endothelial growth factor (VEGF). We generated a novel calcium phosphate (CPC) composite scaffold, which contains BMP-VEGF-loaded poly-lactic-co-glycolic acid (PLGA) microspheres (BMP-VEGF-PLGA-CPC). The BMP-VEGF-loaded microspheres have an encapsulation efficiency of 89.15% for BMP, and 78.55% for VEGF. The BMP-VEGF-PLGA-CPC scaffold also demonstrated a porosity of 62% with interconnected porous structures, and pore sizes of 219 μm and compressive strength of 6.60 MPa. Additionally, bone marrow mesenchymal stem cells (BMSCs) were seeded on scaffolds in vitro. Further characterization showed that the BMP-VEGF-PLGA-CPC scaffolds were biocompatible and enhanced osteogenesis and angiogenesis in vitro. Using a rabbit model of ANFH, BMP-VEGF-PLGA-CPC scaffolds were implanted into the bone tunnels of core decompression in the femoral head for 6 and 12 weeks. Radiographic and histological analysis demonstrated that the BMP-VEGF-PLGA-CPC scaffolds exhibited good biocompatibility, and osteogenic and angiogenic activity in vivo. These results indicate that the BMP-VEGF-PLGA-CPC scaffold may improve the therapeutic effect of core decompression surgery and be used as a treatment for ANFH.

  14. Scaffolds for bone regeneration made of hydroxyapatite microspheres in a collagen matrix.

    PubMed

    Cholas, Rahmatullah; Kunjalukkal Padmanabhan, Sanosh; Gervaso, Francesca; Udayan, Gayatri; Monaco, Graziana; Sannino, Alessandro; Licciulli, Antonio

    2016-06-01

    Biomimetic scaffolds with a structural and chemical composition similar to native bone tissue may be promising for bone tissue regeneration. In the present work hydroxyapatite mesoporous microspheres (mHA) were incorporated into collagen scaffolds containing an ordered interconnected macroporosity. The mHA were obtained by spray drying of a nano hydroxyapatite slurry prepared by the precipitation technique. X-ray diffraction (XRD) analysis revealed that the microspheres were composed only of hydroxyapatite (HA) phase, and energy-dispersive x-ray spectroscopy (EDS) analysis revealed the Ca/P ratio to be 1.69 which is near the value for pure HA. The obtained microspheres had an average diameter of 6 μm, a specific surface area of 40 m(2)/g as measured by Brunauer-Emmett-Teller (BET) analysis, and Barrett-Joyner-Halenda (BJH) analysis showed a mesoporous structure with an average pore diameter of 16 nm. Collagen/HA-microsphere (Col/mHA) composite scaffolds were prepared by freeze-drying followed by dehydrothermal crosslinking. SEM observations of Col/mHA scaffolds revealed HA microspheres embedded within a porous collagen matrix with a pore size ranging from a few microns up to 200 μm, which was also confirmed by histological staining of sections of paraffin embedded scaffolds. The compressive modulus of the composite scaffold at low and high strain values was 1.7 and 2.8 times, respectively, that of pure collagen scaffolds. Cell proliferation measured by the MTT assay showed more than a 3-fold increase in cell number within the scaffolds after 15 days of culture for both pure collagen scaffolds and Col/mHA composite scaffolds. Attractive properties of this composite scaffold include the potential to load the microspheres for drug delivery and the controllability of the pore structure at various length scales.

  15. In vitro characterization of hepatocyte growth factor release from PHBV/PLGA microsphere scaffold.

    PubMed

    Zhu, Xin Hao; Wang, Chi-Hwa; Tong, Yen Wah

    2009-05-01

    Polymer scaffolds which can support cells to grow as well as deliver growth factors to the cells simultaneously have great potential for the successful regeneration of failed tissues. As popularly used vehicles to deliver anti-cancer drugs and growth factors, microspheres also show many advantages as substrates to guide the growth of cells. Therefore, we aimed to examine the feasibility of using microspheres as ideal scaffolds for liver tissue engineering. To determine the capabilities of previously used microsphere scaffold to deliver growth factors simultaneously, this work investigated a long-term (about three months) release of bovine serum albumin (BSA) from microsphere scaffolds fabricated by using two different polymers, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV, 8% PHV), poly(lactide-co-glycolide) acid (PLGA, 5050) and a blend of PLGA and PHBV. BSA served as a model for hepatocyte growth factor (HGF) since both proteins have similar molecular weights and hydrophilicity. Furthermore, HGF was encapsulated into the PLGA/PHBV composite microsphere with a core-shell structure, and sustained delivery of HGF with maintained bioactivity was achieved for at least 40 days. The moderate degradation rate (about 55% loss of the initial mass) and well-preserved structure after three months of incubation indicated that the PLGA/PHBV composite microspheres would therefore be more suitable than the pure PHBV or PLGA microspheres as a scaffold for engineering liver tissue.

  16. Effects of Nano-hydroxyapatite/Poly(DL-lactic-co-glycolic acid) Microsphere-Based Composite Scaffolds on Repair of Bone Defects: Evaluating the Role of Nano-hydroxyapatite Content.

    PubMed

    He, Shu; Lin, Kai-Feng; Sun, Zhen; Song, Yue; Zhao, Yi-Nan; Wang, Zheng; Bi, Long; Liu, Jian

    2016-07-01

    The aim of the current study was to prepare microsphere-based composite scaffolds made of nano-hydroxyapatite (nHA)/poly (DL-lactic-co-glycolic acid) (PLGA) at different ratios and evaluate the effects of nHA on the characteristics of scaffolds for tissue engineering application. First, microsphere-based composite scaffolds made of two ratios of nHA/PLGA (nHA/PLGA = 20/80 and nHA/PLGA = 50/50) were prepared. Then, the effects of nHA on the wettability, mechanical strength, and degradation of scaffolds were investigated. Second, the biocompatibility and osteoinductivity were evaluated and compared by co-culture of scaffolds with bone marrow stromal stem cells (BMSCs). The results showed that the adhesion, proliferation, and osteogenic differentiation of BMSCs with nHA/PLGA (50/50) were better than those with nHA/PLGA (20/80). Finally, we implanted the scaffolds into femur bone defects in a rabbit model, then the capacity of guiding bone regeneration as well as the in vivo degradation were observed by micro-CT and histological examinations. After 4 weeks' implantation, there was no significant difference on the repair of bone defects. However, after 8 and 12 weeks' implantation, the nHA/PLGA (20/80) exhibited better bone formation than nHA/PLGA (50/50). These results suggested that a proper concentration of nHA in the nHA/PLGA composite should be taken into account when the composite scaffolds were prepared, which plays an important role in the biocompatibility, degradation rate and osteoconductivity.

  17. Delivery of Bioactive Lipids from Composite Microgel-Microsphere Injectable Scaffolds Enhances Stem Cell Recruitment and Skeletal Repair

    PubMed Central

    Das, Anusuya; Barker, Daniel A.; Wang, Tiffany; Lau, Cheryl M.; Lin, Yong; Botchwey, Edward A.

    2014-01-01

    In this study, a microgel composed of chitosan and inorganic phosphates was used to deliver poly(lactic-co-glycolic acid) (PLAGA) microspheres loaded with sphingolipid growth factor FTY720 to critical size cranial defects in Sprague Dawley rats. We show that sustained release of FTY720 from injected microspheres used alone or in combination with recombinant human bone morphogenic protein-2 (rhBMP2) improves defect vascularization and bone formation in the presence and absence of rhBMP2 as evaluated by quantitative microCT and histological measurements. Moreover, sustained delivery of FTY720 from PLAGA and local targeting of sphingosine 1-phosphate (S1P) receptors reduces CD45+ inflammatory cell infiltration, promotes endogenous recruitment of CD29+CD90+ bone progenitor cells and enhances the efficacy of rhBMP2 from chitosan microgels. Companion in vitro studies suggest that selective activation of sphingosine receptor subtype-3 (S1P3) via FTY720 treatment induces smad-1 phosphorylation in bone-marrow stromal cells. Additionally, FTY720 enhances stromal cell-derived factor-1 (SDF-1) mediated chemotaxis of CD90+CD11B-CD45- bone progenitor cells in vitro after stimulation with rhBMP2. We believe that use of such small molecule delivery formulations to recruit endogenous bone progenitors may be an attractive alternative to exogenous cell-based therapy. PMID:25077607

  18. Solvent/Non-Solvent Sintering To Make Microsphere Scaffolds

    NASA Technical Reports Server (NTRS)

    Laurencin, Cato T.; Brown, Justin L.; Nair, Lakshmi

    2011-01-01

    A solvent/non-solvent sintering technique has been devised for joining polymeric microspheres to make porous matrices for use as drug-delivery devices or scaffolds that could be seeded with cells for growing tissues. Unlike traditional sintering at elevated temperature and pressure, this technique is practiced at room temperature and pressure and, therefore, does not cause thermal degradation of any drug, protein, or other biochemical with which the microspheres might be loaded to impart properties desired in a specific application. Also, properties of scaffolds made by this technique are more reproducible than are properties of comparable scaffolds made by traditional sintering. The technique involves the use of two miscible organic liquids: one that is and one that is not a solvent for the affected polymer. The polymeric microspheres are placed in a mold having the size and shape of the desired scaffold, then the solvent/non-solvent mixture is poured into the mold to fill the void volume between the microspheres, then the liquid mixture is allowed to evaporate. Some of the properties of the resulting scaffold can be tailored through choice of the proportions of the liquids and the diameter of the microspheres.

  19. In vitro bioactivity of bioresorbable porous polymeric scaffolds incorporating hydroxyapatite microspheres.

    PubMed

    Li, L H; Kommareddy, K P; Pilz, C; Zhou, C R; Fratzl, P; Manjubala, I

    2010-07-01

    Biomimetic composites consisting of polymer and mineral components, resembling bone in structure and composition, were produced using a rapid prototyping technique for bone tissue engineering applications. Solid freeform fabrication, known as rapid prototyping (RP) technology, allows scaffolds to be designed with pre-defined and controlled external and internal architecture. Using the indirect RP technique, a three-component scaffold with a woodpile structure, consisting of poly-L-lactic acid (PLLA), chitosan and hydroxyapatite (HA) microspheres, was produced that had a macroporosity of more than 50% together with micropores induced by lyophilization. X-ray diffraction analysis indicated that the preparation and construction of the composite scaffold did not affect the phase composition of the HA. The compressive strength and elastic modulus (E) for the PLLA composites are 0.42 and 1.46 MPa, respectively, which are much higher than those of chitosan/HA composites and resemble the properties of cellular structure. These scaffolds showed excellent biocompatibility and ability for three-dimensional tissue growth of MC3T3-E1 pre-osteoblastic cells. The pre-osteoblastic cells cultured on these scaffolds formed a network on the HA microspheres and proliferated not only in the macropore channels but also in the micropores, as seen from the histological analysis and electron microscopy. The proliferating cells formed an extracellular matrix network and also differentiated into mature osteoblasts, as indicated by alkaline phosphatase enzyme activity. The properties of these scaffolds indicate that they can be used for non-load-bearing applications.

  20. Growth Factor Gradients via Microsphere Delivery in Biopolymer Scaffolds for Osteochondral Tissue Engineering

    PubMed Central

    Wang, Xiaoqin; Wenk, Esther; Zhang, Xiaohui; Meinel, Lorenz; Vunjak-Novakovic, Gordana; Kaplan, David L.

    2009-01-01

    Temporally and spatially controlled delivery of growth factors in polymeric scaffolds is crucial for engineering composite tissue structures, such as osteochondral constructs. In the present study, microsphere-mediated growth factor delivery in polymer scaffolds and its impact on osteochondral differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs) was evaluated. Two growth factors, bone morphogenetic protein 2 (rhBMP-2) and insulin-like growth factor I (rhIGF-I), were incorporated as a single concentration gradient or reverse gradient combining two factors in the scaffolds. To assess the gradient making system and the delivery efficiency of polylactic-co-glycolic acid (PLGA) and silk fibroin microspheres, initially an alginate gel was fabricated into a cylinder shape with microspheres incorporated as gradients. Compared to PLGA microspheres, silk microspheres were more efficient in delivering rhBMP-2, probably due to sustained release of the growth factor, while less efficient in delivering rhIGF-I, likely due to loading efficiency. The growth factor gradients formed were shallow, inducing non-gradient trends in hMSC osteochondral differentiation. Aqueous-derived silk porous scaffolds were used to incorporate silk microspheres using the same gradient process. Both growth factors formed deep and linear concentration gradients in the scaffold, as shown by enzyme-linked immunosorbent assay (ELISA). After seeding with hMSCs and culturing for 5 weeks in a medium containing osteogenic and chondrogenic components, hMSCs exhibited osteogenic and chondrogenic differentiation along the concentration gradients of rhBMP-2 in the single gradient of rhBMP-2 and reverse gradient of rhBMP-2/rhIGF-I, but not the rhIGF-I gradient system, confirming that silk microspheres were more efficient in delivering rhBMP-2 than rhIGF-I for hMSCs osteochondrogenesis. This novel silk microsphere/scaffold system offers a new option for the delivery of multiple growth factors

  1. Microsphere-based scaffolds encapsulating chondroitin sulfate or decellularized cartilage

    PubMed Central

    Gupta, Vineet; Tenny, Kevin M; Barragan, Marilyn; Berkland, Cory J; Detamore, Michael S

    2016-01-01

    Extracellular matrix materials such as decellularized cartilage (DCC) and chondroitin sulfate (CS) may be attractive chondrogenic materials for cartilage regeneration. The goal of the current study was to investigate the effects of encapsulation of DCC and CS in homogeneous microsphere-based scaffolds, and to test the hypothesis that encapsulation of these extracellular matrix materials would induce chondrogenesis of rat bone marrow stromal cells. Four different types of homogeneous scaffolds were fabricated from microspheres of poly(D,L-lactic-co-glycolic acid): Blank (poly(D,L-lactic-co-glycolic acid) only; negative control), transforming growth factor-β3 encapsulated (positive control), DCC encapsulated, and CS encapsulated. These scaffolds were then seeded with rat bone marrow stromal cells and cultured for 6 weeks. The DCC and CS encapsulation altered the morphological features of the microspheres, resulting in higher porosities in these groups. Moreover, the mechanical properties of the scaffolds were impacted due to differences in the degree of sintering, with the CS group exhibiting the highest compressive modulus. Biochemical evidence suggested a mitogenic effect of DCC and CS encapsulation on rat bone marrow stromal cells with the matrix synthesis boosted primarily by the inherently present extracellular matrix components. An important finding was that the cell seeded CS and DCC groups at week 6 had up to an order of magnitude higher glycosaminoglycan contents than their acellular counterparts. Gene expression results indicated a suppressive effect of DCC and CS encapsulation on rat bone marrow stromal cell chondrogenesis with differences in gene expression patterns existing between the DCC and CS groups. Overall, DCC and CS were easily included in microsphere-based scaffolds; however, there is a requirement to further refine their concentrations to achieve the differentiation profiles we seek in vitro. PMID:27358376

  2. Therapeutic efficacy of antibiotic-loaded gelatin microsphere/silk fibroin scaffolds in infected full-thickness burns.

    PubMed

    Lan, Yong; Li, Weichang; Jiao, Yanpeng; Guo, Rui; Zhang, Yi; Xue, Wei; Zhang, Yuanming

    2014-07-01

    Despite advances in burn treatment, burn infection remains a major cause of morbidity and mortality. In this study, an antibacterial silk fibroin (SF) scaffold for burn treatment was designed; gelatin microspheres (GMs) were impregnated with the antibiotic gentamycin sulfate (GS), and the GS-impregnated GMs were then embedded in a SF matrix to fabricate GS/GM/SF scaffolds. The developed GS/GM/SF scaffolds could serve as a dermal regeneration template in full-thickness burns. The average pore size and porosity of the GS/GM/SF scaffolds were 40-80 μm and 85%, respectively. Furthermore, the drug release rate of the scaffolds was significantly slower than that of either GS/GM or GS/SF scaffolds. And the composite scaffold exhibited stronger antimicrobial activities against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Hence, we evaluated the wound-healing effects and antibacterial properties of the GS/GM/SF scaffolds in a rat full-thickness burn infection model. Over 21 days, the GS/GM/SF scaffolds not only significantly reduced burn infection by P. aeruginosa but also accelerated the regeneration of the dermis and exhibited higher epithelialization rates than did GS/SF and SF scaffolds. Thus, GS/GM/SF scaffolds are potentially effective for treatment of full-thickness infected burns, and GS/GM/SF scaffolds are a promising therapeutic tool for severely burned patients.

  3. Microsphere-Based Seamless Scaffolds Containing Macroscopic Gradients of Encapsulated Factors for Tissue Engineering

    PubMed Central

    Singh, Milind; Morris, Casey P.; Ellis, Ryan J.; Detamore, Michael S.

    2008-01-01

    Spatial and temporal control of bioactive signals in three-dimensional (3D) tissue engineering scaffolds is greatly desired. Coupled together, these attributes may mimic and maintain complex signal patterns, such as those observed during axonal regeneration or neovascularization. Seamless polymer constructs may provide a route to achieve spatial control of signal distribution. In this study, a novel microparticle-based scaffold fabrication technique is introduced as a method to create 3D scaffolds with spatial control over model dyes using uniform poly(D,L-lactide-co-glycolide) microspheres. Uniform microspheres were produced using the Precision Particle Fabrication technique. Scaffolds were assembled by flowing microsphere suspensions into a cylindrical glass mold, and then microspheres were physically attached to form a continuous scaffold using ethanol treatment. An ethanol soak of 1 h was found to be optimum for improved mechanical characteristics. Morphological and physical characterization of the scaffolds revealed that microsphere matrices were porous (41.1 ± 2.1%) and well connected, and their compressive stiffness ranged from 142 to 306 kPa. Culturing chondrocytes on the scaffolds revealed the compatibility of these substrates with cell attachment and viability. In addition, bilayered, multilayered, and gradient scaffolds were fabricated, exhibiting excellent spatial control and resolution. Such novel scaffolds can serve as sustained delivery devices of heterogeneous signals in a continuous and seamless manner, and may be particularly useful in future interfacial tissue engineering investigations. PMID:18795865

  4. Balancing mechanical strength with bioactivity in chitosan-calcium phosphate 3D microsphere scaffolds for bone tissue engineering: air- vs. freeze-drying processes.

    PubMed

    Nguyen, D T; McCanless, J D; Mecwan, M M; Noblett, A P; Haggard, W O; Smith, R A; Bumgardner, J D

    2013-01-01

    The objective of this study was to evaluate the potential benefit of 3D composite scaffolds composed of chitosan and calcium phosphate for bone tissue engineering. Additionally, incorporation of mechanically weak lyophilized microspheres within those air-dried (AD) was considered for enhanced bioactivity. AD microsphere, alone, and air- and freeze-dried microsphere (FDAD) 3D scaffolds were evaluated in vitro using a 28-day osteogenic culture model with the Saos-2 cell line. Mechanical testing, quantitative microscopy, and lysozyme-driven enzymatic degradation of the scaffolds were also studied. FDAD scaffold showed a higher concentration (p < 0.01) in cells per scaffold mass vs. AD constructs. Collagen was ∼31% greater (p < 0.01) on FDAD compared to AD scaffolds not evident in microscopy of microsphere surfaces. Alternatively, AD scaffolds demonstrated a superior threefold increase in compressive strength over FDAD (12 vs. 4 MPa) with minimal degradation. Inclusion of FD spheres within the FDAD scaffolds allowed increased cellular activity through improved seeding, proliferation, and extracellular matrix production (as collagen), although mechanical strength was sacrificed through introduction of the less stiff, porous FD spheres.

  5. Porcine gelatin microsphere/calcium phosphate cement composites: an in vitro degradation study.

    PubMed

    Habraken, Wouter J E M; Wolke, Joop G C; Mikos, Antonios G; Jansen, John A

    2009-11-01

    Scaffolds for bone tissue engineering preferably should be mechanically stable, osteoconductive, biodegradable and porous. To comply with these characteristics, calcium phosphate cements (CPCs) with porcine (type A) gelatin microspheres were formulated. In this experiment, in vitro degradation of 10 wt % gelatin type A microsphere CPCs (GELA CPCs) was followed for 12 weeks in proteolytic medium. Results showed a gradual decrease in mass, compression strength and E-modulus. Morphology investigation showed that degradation of the spheres started at the surface of the composite and gradually proceeded to the inner part. Overall, porcine gelatin microspheres can be used to generate in situ macroporosity into an injectable CPC.

  6. PHBV microspheres as neural tissue engineering scaffold support neuronal cell growth and axon-dendrite polarization.

    PubMed

    Chen, Wenhui; Tong, Yen Wah

    2012-02-01

    Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) microspheres, with properties such as slower degradation and more efficient drug delivery properties, have important benefits for neural tissue engineering. Our previous studies have shown PHBV microspheres to improve cell growth and differentiation. This study aimed to investigate if PHBV microspheres would support neurons to extend these benefits to neural tissue engineering. PHBV microspheres' suitability as neural tissue engineering scaffolds was investigated using PC12 cells, cortical neurons (CNs), and neural progenitor cells (NPCs) to cover a variety of neuronal types for different applications. Microspheres were fabricated using an emulsion-solvent-evaporation technique. DNA quantification, cell viability assays, and immunofluorescent staining were carried out. PC12 cultures on PHBV microspheres showed growth trends comparable to two-dimensional controls. This was further verified by staining for cell spreading. Also, CNs expressed components of the signaling pathway on PHBV microspheres, and had greater axon-dendrite segregation (4.1 times for axon stains and 2.3 times for dendrite stains) than on coverslips. NPCs were also found to differentiate into neurons on the microspheres. Overall, the results indicate that PHBV microspheres, as scaffolds for neural tissue engineering, supported a variety of neuronal cell types and promoted greater axon-dendrite segregation.

  7. Aerogel microspheres from natural cellulose nanofibrils and their application as cell culture scaffold.

    PubMed

    Cai, Hongli; Sharma, Sudhir; Liu, Wenying; Mu, Wei; Liu, Wei; Zhang, Xiaodan; Deng, Yulin

    2014-07-14

    We demonstrated that ultralight pure natural aerogel microspheres can be fabricated using cellulose nanofibrials (CNF) directly. Experimentally, the CNF aqueous gel droplets, produced by spraying and atomizing through a steel nozzle, were collected into liquid nitrogen for instant freezing followed by freeze-drying. The aerogel microspheres are highly porous with bulk density as low as 0.0018 g cm(-3). The pore size of the cellulose aeogel microspheres ranges from nano- to macrometers. The unique ultralight and high porous structure ensured high moisture (~90 g g(-1)) and water uptake capacity (~100 g g(-1)) of the aerogel microspheres. Covalent cross-linking between the native nanofibrils and cross-linkers made the aerogel microspheres very stable even in a harsh environment. The present study also confirmed this kind of aerogel microspheres from native cellulose fibers can be used as cell culture scaffold.

  8. Fabrication and evaluation of a sustained-release chitosan-based scaffold embedded with PLGA microspheres.

    PubMed

    Song, Kedong; Liu, Yingchao; Macedo, Hugo M; Jiang, Lili; Li, Chao; Mei, Guanyu; Liu, Tianqing

    2013-04-01

    Nutrient depletion within three-dimensional (3D) scaffolds is one of the major hurdles in the use of this technology to grow cells for applications in tissue engineering. In order to help in addressing it, we herein propose to use the controlled release of encapsulated nutrients within polymer microspheres into chitosan-based 3D scaffolds, wherein the microspheres are embedded. This method has allowed maintaining a stable concentration of nutrients within the scaffolds over the long term. The polymer microspheres were prepared using multiple emulsions (w/o/w), in which bovine serum albumin (BSA) and poly (lactic-co-glycolic) acid (PLGA) were regarded as the protein pattern and the exoperidium material, respectively. These were then mixed with a chitosan solution in order to form the scaffolds by cryo-desiccation. The release of BSA, entrapped within the embedded microspheres, was monitored with time using a BCA kit. The morphology and structure of the PLGA microspheres containing BSA before and after embedding within the scaffold were observed under a scanning electron microscope (SEM). These had a round shape with diameters in the range of 27-55 μm, whereas the chitosan-based scaffolds had a uniform porous structure with the microspheres uniformly dispersed within their 3D structure and without any morphological change. In addition, the porosity, water absorption and degradation rate at 37 °C in an aqueous environment of 1% chitosan-based scaffolds were (92.99±2.51) %, (89.66±0.66) % and (73.77±3.21) %, respectively. The studies of BSA release from the embedded microspheres have shown a sustained and cumulative tendency with little initial burst, with (20.24±0.83) % of the initial amount released after 168 h (an average rate of 0.12%/h). The protein concentration within the chitosan-based scaffolds after 168 h was found to be (11.44±1.81)×10(-2) mg/mL. This novel chitosan-based scaffold embedded with PLGA microspheres has proven to be a promising technique

  9. Injectable and porous PLGA microspheres that form highly porous scaffolds at body temperature.

    PubMed

    Qutachi, Omar; Vetsch, Jolanda R; Gill, Daniel; Cox, Helen; Scurr, David J; Hofmann, Sandra; Müller, Ralph; Quirk, Robin A; Shakesheff, Kevin M; Rahman, Cheryl V

    2014-12-01

    Injectable scaffolds are of interest in the field of regenerative medicine because of their minimally invasive mode of delivery. For tissue repair applications, it is essential that such scaffolds have the mechanical properties, porosity and pore diameter to support the formation of new tissue. In the current study, porous poly(dl-lactic acid-co-glycolic acid) (PLGA) microspheres were fabricated with an average size of 84±24μm for use as injectable cell carriers. Treatment with ethanolic sodium hydroxide for 2min was observed to increase surface porosity without causing the microsphere structure to disintegrate. This surface treatment also enabled the microspheres to fuse together at 37°C to form scaffold structures. The average compressive strength of the scaffolds after 24h at 37°C was 0.9±0.1MPa, and the average Young's modulus was 9.4±1.2MPa. Scaffold porosity levels were 81.6% on average, with a mean pore diameter of 54±38μm. This study demonstrates a method for fabricating porous PLGA microspheres that form solid porous scaffolds at body temperature, creating an injectable system capable of supporting NIH-3T3 cell attachment and proliferation in vitro.

  10. Cold Atmospheric Plasma Modified Electrospun Scaffolds with Embedded Microspheres for Improved Cartilage Regeneration

    PubMed Central

    Zhu, Wei; Castro, Nathan J.; Cheng, Xiaoqian; Keidar, Michael; Zhang, Lijie Grace

    2015-01-01

    Articular cartilage is prone to degeneration and possesses extremely poor self-healing capacity due to inherent low cell density and the absence of a vasculature network. Tissue engineered cartilage scaffolds show promise for cartilage repair. However, there still remains a lack of ideal biomimetic tissue scaffolds which effectively stimulate cartilage regeneration with appropriate functional properties. Therefore, the objective of this study is to develop a novel biomimetic and bioactive electrospun cartilage substitute by integrating cold atmospheric plasma (CAP) treatment with sustained growth factor delivery microspheres. Specifically, CAP was applied to a poly(ε-caprolactone) electrospun scaffold with homogeneously distributed bioactive factors (transforming growth factor-β1 and bovine serum albumin) loaded poly(lactic-co-glycolic) acid microspheres. We have shown that CAP treatment renders electrospun scaffolds more hydrophilic thus facilitating vitronectin adsorption. More importantly, our results demonstrate, for the first time, CAP and microspheres can synergistically enhance stem cell growth as well as improve chondrogenic differentiation of human marrow-derived mesenchymal stem cells (such as increased glycosaminoglycan, type II collagen, and total collagen production). Furthermore, CAP can substantially enhance 3D cell infiltration (over two-fold increase in infiltration depth after 1 day of culture) in the scaffolds. By integrating CAP, sustained bioactive factor loaded microspheres, and electrospinning, we have fabricated a promising bioactive scaffold for cartilage regeneration. PMID:26222527

  11. Effect of Autologous Bone Marrow Stromal Cell Seeding and Bone Morphogenetic Protein-2 Delivery on Ectopic Bone Formation in a Microsphere/Poly(Propylene Fumarate) Composite

    PubMed Central

    Kempen, Diederik H.R.; Kruyt, Moyo C.; Lu, Lichun; Wilson, Clayton E.; Florschutz, Anthony V.; Yaszemski, Michael J.; Dhert, Wouter J.A.

    2009-01-01

    A biodegradable microsphere/scaffold composite based on the synthetic polymer poly(propylene fumarate) (PPF) holds promise as a scaffold for cell growth and sustained delivery vehicle for growth factors for bone regeneration. The objective of the current work was to investigate the in vitro release and in vivo bone forming capacity of this microsphere/scaffold composite containing bone morphogenetic protein-2 (BMP-2) in combination with autologous bone marrow stromal cells (BMSCs) in a goat ectopic implantation model. Three composites consisting of 0, 0.08, or 8 μg BMP-2 per mg of poly(lactic-co-glycolic acid) microspheres, embedded in a porous PPF scaffold, were combined with either plasma (no cells) or culture-expanded BMSCs. PPF scaffolds impregnated with a BMP-2 solution and combined with BMSCs as well as empty PPF scaffolds were also tested. The eight different composites were implanted subcutaneously in the dorsal thoracolumbar area of goats. Incorporation of BMP-2–loaded microspheres in the PPF scaffold resulted in a more sustained in vitro release with a lower burst phase, as compared to BMP-2–impregnated scaffolds. Histological analysis after 9 weeks of implantation showed bone formation in the pores of 11/16 composites containing 8 μg/mg BMP-2–loaded microspheres with no significant difference between composites with or without BMSCs (6/8 and 5/8, respectively). Bone formation was also observed in 1/8 of the BMP-2–impregnated scaffolds. No bone formation was observed in the other conditions. Overall, this study shows the feasibility of bone induction by BMP-2 release from microspheres/scaffold composites. PMID:18925831

  12. Injectable alginate/hydroxyapatite gel scaffold combined with gelatin microspheres for drug delivery and bone tissue engineering.

    PubMed

    Yan, Jingxuan; Miao, Yuting; Tan, Huaping; Zhou, Tianle; Ling, Zhonghua; Chen, Yong; Xing, Xiaodong; Hu, Xiaohong

    2016-06-01

    Injectable and biodegradable alginate-based composite gel scaffolds doubly integrated with hydroxyapatite (HAp) and gelatin microspheres (GMs) were cross-linked via in situ release of calcium cations. As triggers of calcium cations, CaCO3 and glucono-D-lactone (GDL) were fixed as a mass ratio of 1:1 to control pH value ranging from 6.8 to 7.2 during gelation. Synchronously, tetracycline hydrochloride (TH) was encapsulated into GMs to enhance bioactivity of composite gel scaffolds. The effects of HAp and GMs on characteristics of gel scaffolds, including pH value, gelation time, mechanical properties, swelling ratio, degradation behavior and drug release, were investigated. The results showed that HAp and GMs successfully improved mechanical properties of gel scaffolds at strain from 0.1 to 0.5, which stabilized the gel network and decreased weight loss, as well as swelling ratio and gelation time. TH could be released from this composite gel scaffold into the local microenvironment in a controlled fashion by the organic/inorganic hybrid of hydrogel network. Our results demonstrate that the HAp and GMs doubly integrated alginate-based gel scaffolds, especially the one with 6% (w/v) HAp and 5% (w/v) GMs, have suitable physical performance and bioactive properties, thus provide a potential opportunity to be used for bone tissue engineering. The potential application of this gel scaffold in bone tissue engineering was confirmed by encapsulation behavior of osteoblasts. In combination with TH, the gel scaffold exhibited beneficial effects on osteoblast activity, which suggested a promising future for local treatment of pathologies involving bone loss.

  13. PLGA/alginate composite microspheres for hydrophilic protein delivery.

    PubMed

    Zhai, Peng; Chen, X B; Schreyer, David J

    2015-11-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate.

  14. Microsphere-Based Scaffolds Encapsulating Tricalcium Phosphate And Hydroxyapatite For Bone Regeneration

    PubMed Central

    Gupta, Vineet; Lyne, Dina V.; Barragan, Marilyn; Berkland, Cory J.; Detamore, Michael S.

    2016-01-01

    Bioceramic mixtures of tricalcium phosphate (TCP) and hydroxyapatite (HAp) are widely used for bone regeneration because of their excellent cytocompatibility, osteoconduction, and osteoinduction. Therefore, we hypothesized that incorporation of a mixture of TCP and HAp in microsphere-based scaffolds would enhance osteogenesis of rat bone marrow stromal cells (rBMSCs) compared to a positive control of scaffolds with encapsulated bone-morphogenic protein-2 (BMP-2). Poly(D,L-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds encapsulating TCP and HAp mixtures in two different ratios (7:3 and 1:1) were fabricated with the same net ceramic content (30 wt%) to evaluate how incorporation of these ceramic mixtures would affect the osteogenesis in rBMSCs. Encapsulation of TCP/HAp mixtures impacted microsphere morphologies and the compressive moduli of the scaffolds. Additionally, TCP/HAp mixtures enhanced the end-point secretion of extracellular matrix (ECM) components relevant to bone tissue compared to the “blank” (PLGA-only) microsphere-based scaffolds as evidenced by the biochemical, gene expression, histology, and immunohistochemical characterization. Moreover, the TCP/HAp mixture groups even surpassed the BMP-2 positive control group in some instances in terms of matrix synthesis and gene expression. Lastly, gene expression data suggested that the rBMSCs responded differently to different TCP/HAp ratios presented to them. Altogether, it can be concluded that TCP/HAp mixtures stimulated the differentiation of rBMSCs toward an osteoblastic phenotype, and therefore may be beneficial in gradient microsphere-based scaffolds for osteochondral regeneration. PMID:27272903

  15. Material characterization of microsphere-based scaffolds with encapsulated raw materials.

    PubMed

    Sridharan, BanuPriya; Mohan, Neethu; Berkland, Cory J; Detamore, Michael S

    2016-06-01

    "Raw materials," or materials capable of serving both as building blocks and as signals, which are often but not always natural materials, are taking center stage in biomaterials for contemporary regenerative medicine. In osteochondral tissue engineering, a field leveraging the underlying bone to facilitate cartilage regeneration, common raw materials include chondroitin sulfate (CS) for cartilage and β-tricalcium phosphate (TCP) for bone. Building on our previous work with gradient scaffolds based on microspheres, here we delved deeper into the characterization of individual components. In the current study, the release of CS and TCP from poly(D, L-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds was evaluated over a time period of 4 weeks. Raw material encapsulated groups were compared to 'blank' groups and evaluated for surface topology, molecular weight, and mechanical performance as a function of time. The CS group may have led to increased surface porosity, and the addition of CS improved the mechanical performance of the scaffold. The finding that CS was completely released into the surrounding media by 4 weeks has a significant impact on future in vivo studies, given rapid bioavailability. The addition of TCP seemed to contribute to the rough external appearance of the scaffold. The current study provides an introduction to degradation patterns of homogenous raw material encapsulated scaffolds, providing characterization data to advance the field of microsphere-based scaffolds in tissue engineering.

  16. Preparation and Characterization of 45S5 Bioactive Glass-based Scaffolds Loaded with PHBV Microspheres with Daidzein Release Function.

    PubMed

    Macías-Andrés, Víctor I; Li, Wei; Aguilar-Reyes, Ena A; Ding, Yaping; Roether, Judith A; Harhaus, Leila; León-Patiño, Carlos A; Boccaccini, A R

    2017-02-27

    PHBV microsphere loaded 45S5 bioactive glass (BG) based scaffolds with drug releasing capability have been developed. PHBV microspheres with a mean particle size 4 ± 2 μm loaded with daidzein were obtained by oil-in-water single emulsion solvent evaporation method and applied to the surface of BG scaffolds by dip coating technique. The morphology, in vitro bioactivity in simulated body fluid (SBF), mechanical properties and drug release kinetics of microsphere loaded scaffolds were studied. The microspheres were shown to be homogeneously dispersed on the scaffold surfaces. It was confirmed that hydroxyapatite crystals homogeneously grew not only on the surface of the scaffold but also on the surface of the microspheres within 3 days of immersion in SBF. The daidzein release from the microsphere loaded scaffolds lasted almost 1 month and was determined to be diffusion controlled. The microsphere loaded BG scaffolds with daidzein releasing capability obtained in this study are a candidate for bone tissue engineering. This article is protected by copyright. All rights reserved.

  17. Preparation and characterization of gelatin-hydroxyapatite composite microspheres for hard tissue repair.

    PubMed

    Chao, Shao Ching; Wang, Ming-Jia; Pai, Nai-Su; Yen, Shiow-Kang

    2015-12-01

    Gelatin-hydroxyapatite composite microspheres composed of 21% gelatin (G) and 79% hydroxyapatite (HA) with uniform morphology and controllable size were synthesized from a mixed solution of Ca(NO3)2, NH4H2PO4 and gelatin by a wet-chemical method. Material analyses such as X-ray diffraction (XRD), scanning/transmission electron microscopy examination (SEM/TEM) and inductively coupled plasma-mass spectroscopy (ICP-MS) were used to characterize G-HA microspheres by analyzing their crystalline phase, microstructure, morphology and composition. HA crystals precipitate along G fibers to form nano-rods with diameters of 6-10nm and tangle into porous microspheres after blending. The cell culture indicates that G-HA composite microspheres without any toxicity could enhance the proliferation and differentiation of osteoblast-like cells. In a rat calvarial defect model, G-HA bioactive scaffolds were compared with fibrin glue (F) and Osteoset® Bone Graft Substitute (OS) for their capacity of regenerating bone. Four weeks post-implantation, new bone, mineralization, and expanded blood vessel area were found in G-HA scaffolds, indicating greater osteoconductivity and bioactivity than F and OS.

  18. Incorporation of Chitosan Microspheres into Collagen-Chitosan Scaffolds for the Controlled Release of Nerve Growth Factor

    PubMed Central

    Xiao, Wei; Qi, Fengyu; Huang, Jinghui; Luo, Zhuojing

    2014-01-01

    Background Artifical nerve scaffold can be used as a promising alternative to autologous nerve grafts to enhance the repair of peripheral nerve defects. However, current nerve scaffolds lack efficient microstructure and neurotrophic support. Methods Microsphere–Scaffold composite was developed by incorporating chitosan microspheres loaded with nerve growth factor (NGF–CMSs) into collagen-chitosan scaffolds (CCH) with longitudinally oriented microchannels (NGF–CMSs/CCH). The morphological characterizations, in vitro release kinetics study, neurite outgrowth assay, and bioactivity assay were evaluated. After that, a 15-mm-long sciatic nerve gap in rats was bridged by the NGF–CMSs/CCH, CCH physically absorbed NGF (NGF/CCH), CCH or nerve autograft. 16 weeks after implantation, electrophysiology, fluoro-gold retrograde tracing, and nerve morphometry were performed. Results The NGF–CMSs were evenly distributed throughout the longitudinally oriented microchannels of the scaffold. The NGF–CMSs/CCH was capable of sustained release of bioactive NGF within 28 days as compared with others in vitro. In vivo animal study demonstrated that the outcomes of NGF–CMSs/CCH were better than those of NGF/CCH or CCH. Conclusion Our findings suggest that incorporation of NGF–CMSs into the CCH may be a promising tool in the repair of peripheral nerve defects. PMID:24983464

  19. Evaluation of zinc-doped mesoporous hydroxyapatite microspheres for the construction of a novel biomimetic scaffold optimized for bone augmentation

    PubMed Central

    Yu, Weilin; Sun, Tuan-Wei; Qi, Chao; Ding, Zhenyu; Zhao, Huakun; Zhao, Shichang; Shi, Zhongmin; Zhu, Ying-Jie; Chen, Daoyun; He, Yaohua

    2017-01-01

    Biomaterials with high osteogenic activity are desirable for sufficient healing of bone defects resulting from trauma, tumor, infection, and congenital abnormalities. Synthetic materials mimicking the structure and composition of human trabecular bone are of considerable potential in bone augmentation. In the present study, a zinc (Zn)-doped mesoporous hydroxyapatite microspheres (Zn-MHMs)/collagen scaffold (Zn-MHMs/Coll) was developed through a lyophilization fabrication process and designed to mimic the trabecular bone. The Zn-MHMs were synthesized through a microwave-hydrothermal method by using creatine phosphate as an organic phosphorus source. Zn-MHMs that consist of hydroxyapatite nanosheets showed relatively uniform spherical morphology, mesoporous hollow structure, high specific surface area, and homogeneous Zn distribution. They were additionally investigated as a drug nanocarrier, which was efficient in drug delivery and presented a pH-responsive drug release behavior. Furthermore, they were incorporated into the collagen matrix to construct a biomimetic scaffold optimized for bone tissue regeneration. The Zn-MHMs/Coll scaffolds showed an interconnected pore structure in the range of 100–300 μm and a sustained release of Zn ions. More importantly, the Zn-MHMs/Coll scaffolds could enhance the osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells. Finally, the bone defect repair results of critical-sized femoral condyle defect rat model demonstrated that the Zn-MHMs/Coll scaffolds could enhance bone regeneration compared with the Coll or MHMs/Coll scaffolds. The results suggest that the biomimetic Zn-MHMs/Coll scaffolds may be of enormous potential in bone repair and regeneration. PMID:28392688

  20. Subcritical CO2 Sintering of Microspheres of Different Polymeric Materials to Fabricate Scaffolds for Tissue Engineering

    PubMed Central

    Bhamidipati, Manjari; Sridharan, BanuPriya; Scurto, Aaron M; Detamore, Michael S.

    2013-01-01

    The aim of this study was to use CO2 at sub-critical pressures as a tool to sinter 3D, macroporous, microsphere-based scaffolds for bone and cartilage Tissue Engineering Porous scaffolds composed of ~200 µm microspheres of either poly(lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL) were prepared using dense phase CO2 sintering, which were seeded with rat bone marrow mesenchymal stromal cells (rBMSCs), and exposed to either osteogenic (PLGA, PCL) or chondrogenic (PLGA) conditions for 6 weeks. Under osteogenic conditions, the PLGA constructs produced over an order of magnitude more calcium than the PCL constructs, whereas the PCL constructs had far superior mechanical and structural integrity (125 times stiffer than PLGA constructs) at week 6, along with twice the cell content of the PLGA constructs. Chondrogenic cell performance was limited in PLGA constructs, perhaps as a result of the polymer degradation rate being too high. The current study represents the first long-term culture of CO2-sintered microsphere-based scaffolds, and has established important thermodynamic differences in sintering between the selected formulations of PLGA and PCL, with the former requiring adjustment of pressure only, and the latter requiring the adjustment of both pressure and temperature. Based on more straightforward sintering conditions and more favorable cell performance, PLGA may be the material of choice for microspheres in a CO2 sintering application, although a different PLGA formulation with the encapsulation of growth factors, extracellular matrix-derived nanoparticles, and/or buffers in the microspheres may be advantageous for achieving a more superior cell performance than observed here. PMID:24094202

  1. TiO2 Sub-microsphere Film as Scaffold Layer for Efficient Perovskite Solar Cells.

    PubMed

    Huang, Yang; Zhu, Jun; Ding, Yong; Chen, Shuanghong; Zhang, Changneng; Dai, Songyuan

    2016-03-01

    TiO2 sub-microspheres composed of anatase granular-like nanocrystallines with an average diameter ∼250 nm are synthesized using sol-gel method and employed as the scaffold layer for efficient mesocopic perovskite solar cells. Compared with mesoporous TiO2 films composed of ∼18 nm nanoparticles, the sub-microsphere films show superior light-trapping characteristics and significantly improve the light-harvesting capability of the solar cells. In addition, the charge-transport performance is also dramatically improved according to the transient photocurrent decay despite there being no significant difference in the perovskite layer surface morphology. As a result, an average power conversion efficiency of 15% with a highly uniform distribution is achieved for the solar cells with TiO2 sub-microsphere films, 12% higher than those with TiO2 nanoparticle films. The combination of light-harvesting capability and fast charge transfer make the TiO2 sub-microsphere film a good candidate as the scaffold layer for efficient perovskite solar cells.

  2. Polymeric microspheres

    DOEpatents

    Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

    2004-04-13

    The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

  3. Novel glycidyl methacrylated dextran (Dex-GMA)/gelatin hydrogel scaffolds containing microspheres loaded with bone morphogenetic proteins: formulation and characteristics.

    PubMed

    Chen, Fa-Ming; Zhao, Yi-Min; Sun, Hai-Hua; Jin, Tao; Wang, Qin-Tao; Zhou, Wei; Wu, Zhi-Fen; Jin, Yan

    2007-03-12

    Novel thermomechanical hydrogel scaffolds containing our previously prepared microspheres loaded with bone morphogenetic proteins (BMP) were successfully generated by radical crosslinking and low dose gamma-irradiation from combination of two kind of biomaterials: glycidyl methacrylated dextran (Dex-GMA) and gelatin. The structure of those resulting smart hybrid hydrogels was evaluated by mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) analyses, and as a function of the degree of Dex-GMA's substitution (DS), the proportion between Dex-GMA and gelatin, and the initial polyethyleneglycol (PEG) concentration used in the preparation of the hydrogels. The swelling and degradation properties and the temperature-sensitive drug release manner were determined by dynamic evaluation methods in vitro, and the gel content was also calculated. MIP analysis showed that by systematically altering the preparation parameters, the overall networks were clearly macroporous with pore sizes ranging from 5.6+/-4.2 to 37.7+/-13.7 microm. As expected, the pore size decreased as DS and initial PEG concentration increased, whereas the opposite was found for the gel content. Moreover, the porosity values ranged from 73.7+/-12.4% up to 89.6+/-6.3%. The SEM results also showed the inter-connective pores as well as microspheres encased into their porous structure of those hydrogels. The swelling and degradation properties of the resultant hydrogels varied according to the DS of Dex-GMA and initial PEG concentration, while the proportion between Dex-GMA and gelatin had no significant influence on those characterizations. By changing the composition ratio of the two precursors, the phase transition temperature (lower critical solution temperature, LSCT) of the hydrogel scaffolds could also be adjusted to be or near the body temperature, so BMP release from microsphere-hydrogel compounds could be accordingly controlled and the release period could be varied from 18 to

  4. Biodegradable polymer-silica xerogel composite microspheres for controlled release of gentamicin.

    PubMed

    Xue, J M; Tan, C H; Lukito, D

    2006-08-01

    Single and double layered composite microspheres were prepared by encapsulating gentamicin-loaded silica xerogels with biodegradable PLGA polymers (poly(DL-lactide-co-glycolide)). The in vitro drug release properties of both the composite microspheres were investigated. The single layered composite microspheres showed a high initial burst, followed by two sustained release stages lasting for approximately 6 weeks. The two sustained release stages of the single layered composite microspheres could be attributed to the swelling and bulk erosion of the polymer encapsulations, respectively. In comparison with the single layered composite microspheres, the double layered composite microspheres realized a much reduced initial burst together with three sustained release stages. The whole release period of the double layered composite microspheres could last more than 9 weeks. These distinct behaviors make the double layered composite microspheres promising as a new drug release material for localized drug delivery applications.

  5. Thermal expansion of an epoxy-glass microsphere composite

    NASA Technical Reports Server (NTRS)

    Price, H. L.; Burks, H. D.

    1977-01-01

    The thermal expansion of a composite of epoxy (diglycidyl ether of bisphenol A) and solid glass microspheres was investigated. The microspheres had surfaces which were either untreated or treated with a silicone release agent, an epoxy coupling agent, or a general purpose silane coupling agent. Both room temperature (about 300 K) and elevated temperature (about 475 K) cures were used for the epoxy. Two microsphere size ranges were used, about 50 microns, which is applicable in filled moldings, and about 125 microns, which is applicable as bond line spacers. The thermal expansion of the composites was measured from 300 to 350 K or from 300 to 500 K, depending on the epoxy cure temperature. Measurements were made on composites containing up to .6 volume fraction microspheres. Two predictive models, which required only the values of thermal expansion of the polymer and glass and their specific gravities, were tested against the experimental data. A finite element analysis was made of the thermal strain of a composite cell containing a single microsphere surrounded by a finite-thickness interface.

  6. Immobilization of salvianolic acid B-loaded chitosan microspheres distributed three-dimensionally and homogeneously on the porous surface of hydroxyapatite scaffolds.

    PubMed

    Li, Jinyu; Wang, Qin; Zhi, Wei; Wang, Jianxin; Feng, Bo; Qu, Shuxin; Mu, Yandong; Weng, Jie

    2016-10-07

    Porous hydroxyapatite (HA) scaffolds combined with a drug delivery system have attracted much attention for bone tissue engineering. In this study, an easy and highly efficient method was developed to immobilize salvianolic acid B (Sal B)-loaded chitosan (CS) microspheres three dimensionally and homogeneously on the surface of HA scaffolds pre-coated with alginate. Porous HA scaffolds were prepared via a template-leaching process and CS microspheres (used as drug carriers) were fabricated by an emulsion method. To improve adhesion between the microspheres and HA scaffolds, alginate was used to pre-coat the porous surface of the HA scaffolds. Various concentrations of alginate were used to optimize the adhesion of Sal B-loaded CS microspheres to the scaffold surface. During the adherence process, coated HA scaffolds were immersed in an aqueous solution containing Sal B-loaded CS microspheres, followed by standing or shaking at 37 °C for a certain time. The results showed that the microspheres were solidly and homogeneously distributed on the porous surface of the alginate pre-coated HA scaffolds via electrostatic interactions. Few microspheres detached from the porous surface, even after the HA scaffolds with microspheres were treated by shaking in distilled water for as long as 7 d. Compared with the static condition, the distribution of Sal B-loaded CS microspheres on the porous surface of pre-coated HA scaffolds in the shaken condition was more homogeneous and almost unaggregated. Additionally, the compressive strength of the scaffolds coated with alginate was obviously improved. The optimal alginate coating concentration was 1% (i.e. the microstructure of the porous surfaces of the HA scaffolds was almost unchanged). The release profile of Sal B over a 30 d immersion found an initial burst release followed by a sustained release. The result of cell culture in vitro was that 1% alginate-coated scaffolds with Sal B-loaded CS microspheres obviously promoted cell

  7. Stratified scaffold design for engineering composite tissues.

    PubMed

    Mosher, Christopher Z; Spalazzi, Jeffrey P; Lu, Helen H

    2015-08-01

    A significant challenge to orthopaedic soft tissue repair is the biological fixation of autologous or allogeneic grafts with bone, whereby the lack of functional integration between such grafts and host bone has limited the clinical success of anterior cruciate ligament (ACL) and other common soft tissue-based reconstructive grafts. The inability of current surgical reconstruction to restore the native fibrocartilaginous insertion between the ACL and the femur or tibia, which minimizes stress concentration and facilitates load transfer between the soft and hard tissues, compromises the long-term clinical functionality of these grafts. To enable integration, a stratified scaffold design that mimics the multiple tissue regions of the ACL interface (ligament-fibrocartilage-bone) represents a promising strategy for composite tissue formation. Moreover, distinct cellular organization and phase-specific matrix heterogeneity achieved through co- or tri-culture within the scaffold system can promote biomimetic multi-tissue regeneration. Here, we describe the methods for fabricating a tri-phasic scaffold intended for ligament-bone integration, as well as the tri-culture of fibroblasts, chondrocytes, and osteoblasts on the stratified scaffold for the formation of structurally contiguous and compositionally distinct regions of ligament, fibrocartilage and bone. The primary advantage of the tri-phasic scaffold is the recapitulation of the multi-tissue organization across the native interface through the layered design. Moreover, in addition to ease of fabrication, each scaffold phase is similar in polymer composition and therefore can be joined together by sintering, enabling the seamless integration of each region and avoiding delamination between scaffold layers.

  8. Chitosan microsphere scaffold tethered with RGD-conjugated poly(methacrylic acid) brushes as effective carriers for the endothelial cells.

    PubMed

    Yang, Zhenyi; Yuan, Shaojun; Liang, Bin; Liu, Yang; Choong, Cleo; Pehkonen, Simo O

    2014-09-01

    Endothelial cell-matrix interactions play a vital role in promoting vascularization of engineered tissues. The current study reports a facile and controllable method to develop a RGD peptide-functionalized chitosan microsphere scaffolds for rapid cell expansion of human umbilical vein endothelial cells (HUVECs). Functional poly(methacrylic acid) (PMAA) brushes are grafted from the chitosan microsphere surfaces via surface-initiated ATRP. Subsequent conjugation of RGD peptides on the pendent carboxyl groups of PMAA side chain is accomplished by carbodiimide chemistry to facilitate biocompatibility of the 3D CS scaffolding system. In vitro cell-loading assay of HUVECs exhibits a significant improvment of cell adhesion, spreading, and proliferation on the RGD peptide-immobilized CS microsphere surfaces.

  9. Coaxial electrohydrodynamic atomization process for production of polymeric composite microspheres

    PubMed Central

    Xu, Qingxing; Qin, Hao; Yin, Zhenyuan; Hua, Jinsong; Pack, Daniel W.; Wang, Chi-Hwa

    2013-01-01

    Polymeric composite microspheres consisting of a poly(D,L-lactic-co-glycolic acid) (PLGA) core surrounded by a poly(D,L-lactic acid) (PDLLA) shell layer were successfully fabricated by coaxial electrohydrodynamic atomization (CEHDA) process. Process conditions, including nozzle voltage and polymer solution flow rates, as well as solution parameters, such as polymer concentrations, were investigated to ensure the formation of composite microspheres with a doxorubicin-loaded PLGA core surrounded by a relatively drug-free PDLLA shell layer. Various microsphere formulations were fabricated and characterized in terms of their drug distribution, encapsulation efficiency and in vitro release. Numerical simulation of CEHDA process was performed based on a computational fluid dynamics (CFD) model in Fluent by employing the process conditions and fluid properties used in the experiments. The simulation results were compared with the experimental work to illustrate the capability of the CFD model to predict the production of consistent compound droplets, and hence, the expected core-shell structured microspheres. PMID:24347672

  10. Coaxial electrohydrodynamic atomization process for production of polymeric composite microspheres.

    PubMed

    Xu, Qingxing; Qin, Hao; Yin, Zhenyuan; Hua, Jinsong; Pack, Daniel W; Wang, Chi-Hwa

    2013-12-18

    Polymeric composite microspheres consisting of a poly(D,L-lactic-co-glycolic acid) (PLGA) core surrounded by a poly(D,L-lactic acid) (PDLLA) shell layer were successfully fabricated by coaxial electrohydrodynamic atomization (CEHDA) process. Process conditions, including nozzle voltage and polymer solution flow rates, as well as solution parameters, such as polymer concentrations, were investigated to ensure the formation of composite microspheres with a doxorubicin-loaded PLGA core surrounded by a relatively drug-free PDLLA shell layer. Various microsphere formulations were fabricated and characterized in terms of their drug distribution, encapsulation efficiency and in vitro release. Numerical simulation of CEHDA process was performed based on a computational fluid dynamics (CFD) model in Fluent by employing the process conditions and fluid properties used in the experiments. The simulation results were compared with the experimental work to illustrate the capability of the CFD model to predict the production of consistent compound droplets, and hence, the expected core-shell structured microspheres.

  11. Preparation, characterization and in vitro release of gentamicin from PHBV/wollastonite composite microspheres.

    PubMed

    Li, Haiyan; Chang, Jiang

    2005-10-20

    Composite microspheres have been prepared from bioactive wollastonite (W) and biodegradable poly (hydroxybutyrate-polyhydroxyvalerate) (PHBV) in the present study. Gentamicin was encapsulated into the microspheres by the absorption method and the in vitro release of the gentamicin from the microspheres was performed in distilled water, modified simulated body fluid (SBF) and phosphate buffered saline (PBS) at 37 degrees C for 22 days, respectively. The results showed that the release behavior of gentamicin from PHBV/W composite microspheres was similar to that from the pure PHBV microspheres when the experiment was performed in distilled water. However, in the PBS and SBF solutions, gentamicin released from the PHBV/W composite microspheres at a relatively lower rate as compared to that of the pure PHBV microspheres and 90% of the total amount of gentamicin released from the composite microspheres after soaking for 22 days, which was much longer than that for the release of the same amount gentamicin from the pure PHBV microspheres (8 days). Scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS) analysis on the microspheres after release in SBF and PBS revealed that a microporous apatite layer was formed on the composite microspheres surface, which resulted in a controlled release behavior of the gentamicin from the PHBV/W composite microspheres. All of these results provided the possibility that the PHBV/W composite microspheres could be applied as alternative drug controlled release systems, especially as bone fillings for bone repair due to their advantages of controlled releasing antibiotics and apatite-formation ability, through which the implanted microspheres could chemically bond to the surrounding tissue in vivo.

  12. Role of surfactant during microemulsion photopolymerization for the creation of three-dimensional (3D) liquid crystal elastomer microsphere spatial cell scaffolds

    NASA Astrophysics Data System (ADS)

    Hegmann, Elda; Bera, Tanmay; Malcuit, Christopher; Clements, Robert

    2016-06-01

    Three-dimensional (3D) cell scaffolds based on connected nematic liquid crystal elastomer microsphere architectures support the attachment and proliferation of C2C12 myoblasts, neuroblastomas (SHSY5Y) and human dermal fibroblasts (hDF). The microsphere spatial cell scaffolds were prepared by an oil-in-water microemulsion photopolymerization of reactive nematic mesogens in the presence of various surfactants, and the as-prepared scaffold constructs are composed of smooth surface microspheres with diameter ranging from 10 to 30 μm. We here investigate how the nature and type of surfactant used during the microemulsion photopolymerization impacts both the size and size distribution of the resulting microspheres as well as their surface morphology, i.e. the surface roughness.

  13. Mesoporous metal oxide microsphere electrode compositions and their methods of making

    DOEpatents

    Parans Paranthaman, Mariappan; Bi, Zhonghe; Bridges, Craig A; Brown, Gilbert M

    2014-12-16

    Compositions and methods of making are provided for treated mesoporous metal oxide microspheres electrodes. The compositions comprise (a) microspheres with an average diameter between 200 nanometers (nm) and 10 micrometers (.mu.m); (b) mesopores on the surface and interior of the microspheres, wherein the mesopores have an average diameter between 1 nm and 50 nm and the microspheres have a surface area between 50 m.sup.2/g and 500 m.sup.2/g, and wherein the composition has an electrical conductivity of at least 1.times.10.sup.-7 S/cm at 25.degree. C. and 60 MPa. The methods of making comprise forming a mesoporous metal oxide microsphere composition and treating the mesoporous metal oxide microspheres by at least one method selected from the group consisting of: (i) annealing in a reducing atmosphere, (ii) doping with an aliovalent element, and (iii) coating with a coating composition.

  14. Microspheres

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Vital information on a person's physical condition can be obtained by identifying and counting the population of T-cells and B-cells, lymphocytes of the same shape and size that help the immune system protect the body from the invasion of disease. The late Dr. Alan Rembaum developed a method for identifying the cells. The method involved tagging the T-cells and B-cells with microspheres of different fluorescent color. Microspheres, which have fluorescent dye embedded in them, are chemically treated so that they can link with antibodies. With the help of a complex antibody/antigen reaction, the microspheres bind themselves to specific 'targets,' in this case the T-cells or B-cells. Each group of cells can then be analyzed by a photoelectronic instrument at different wavelengths emitted by the fluorescent dyes. Same concept was applied to the separation of cancer cells from normal cells. Microspheres were also used to conduct many other research projects. Under a patent license Magsphere, Inc. is producing a wide spectrum of microspheres on a large scale and selling them worldwide for various applications.

  15. Mesoporous metal oxide microsphere electrode compositions and their methods of making

    SciTech Connect

    Paranthaman, Mariappan Parans; Liu, Hansan; Brown, Gilbert M.; Sun, Xiao-Guang; Bi, Zhonghe

    2016-12-06

    Compositions and methods of making are provided for mesoporous metal oxide microspheres electrodes. The mesoporous metal oxide microsphere compositions comprise (a) microspheres with an average diameter between 200 nanometers (nm) and 10 micrometers (.mu.m); (b) mesopores on the surface and interior of the microspheres, wherein the mesopores have an average diameter between 1 nm and 50 nm and the microspheres have a surface area between 50 m.sup.2/g and 500 m.sup.2/g. The methods of making comprise forming composite powders. The methods may also comprise refluxing the composite powders in a basic solution to form an etched powder, washing the etched powder with an acid to form a hydrated metal oxide, and heat-treating the hydrated metal oxide to form mesoporous metal oxide microspheres.

  16. Preparation of bioactive porous HA/PCL composite scaffolds

    NASA Astrophysics Data System (ADS)

    Zhao, J.; Guo, L. Y.; Yang, X. B.; Weng, J.

    2008-12-01

    Porous hydroxyapatite (HA) bioceramic scaffold has been widely attracted the attention to act as a three-dimensional (3D) template for cell adhesion, proliferation, differentiation and thus promoting bone and cartilage regeneration because of its osteoinduction. However, the porous bioceramic scaffold is fragile so that it is not suitable to be applied in clinic for bone repair or replacement. Therefore, it is significant to improve the mechanical property of porous HA bioceramics while the interconnected structure is maintained for tissue ingrowth in vivo. In the present research, a porous composite scaffold composed of HA scaffold and polycaprolactone (PCL) lining was fabricated by the method of polymer impregnating to produce HA scaffold coated with PCL lining. Subsequently, the composite scaffolds were deposited with biomimetic coating for improving the bioactivity. The HA/PCL composite scaffolds with improved mechanical property and bioactivity is expected to be a promising bone substitute in tissue engineering applications.

  17. Preparation of monodisperse PEG hydrogel composite microspheres via microfluidic chip with rounded channels

    NASA Astrophysics Data System (ADS)

    Yu, Bing; Cong, Hailin; Liu, Xuesong; Ren, Yumin; Wang, Jilei; Zhang, Lixin; Tang, Jianguo; Ma, Yurong; Akasaka, Takeshi

    2013-09-01

    An effective microfluidic method to fabricate monodisperse polyethylene glycol (PEG) hydrogel composite microspheres with tunable dimensions and properties is reported in this paper. A T-junction microfluidic chip equipped with rounded channels and online photopolymerization system is applied for the microsphere microfabrication. The shape and size of the microspheres are well controlled by the rounded channels and PEG prepolymer/silicon oil flow rate ratios. The obtained PEG/aspirin composite microspheres exhibit a sustained release of aspirin for a wide time range; the obtained PEG/Fe3O4 nanocomposite microspheres exhibit excellent magnetic properties; and the obtained binary PEG/dye composite microspheres show the ability to synchronously load two functional components in the same peanut-shaped or Janus hydrogel particles.

  18. Silicon dioxide hollow microspheres with porous composite structure: synthesis and characterization.

    PubMed

    Yan, Xiuli; Lei, Zhongli

    2011-10-15

    In this paper, a strategy for hollow porous silica microspheres with ideally flower structure is presented. SiO(2)/PAM hybrid composite microspheres with porous were synthesized by the reaction that the porous polyacrylamide (PAM) micro-gels immersed in tetraethoxysilane (TEOS) anhydrous alcohol solution and water in a moist atmosphere, with ammonium hydroxide as a catalyst. The SiO(2) hollow microspheres with porous were obtained after calcination of the composite microspheres at 550 °C for 4 h. The morphology, composition, and crystalline structure of the microspheres were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo-gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FI-IR), and X-ray diffraction (XRD), N(2) absorption analysis, respectively. The results indicated that the obtained hollow porous SiO(2) microspheres were a perfect flower structure.

  19. Synthetic, biological and composite scaffolds for abdominal wall reconstruction.

    PubMed

    Meintjes, Jennifer; Yan, Sheng; Zhou, Lin; Zheng, Shusen; Zheng, Minghao

    2011-03-01

    The reconstruction of abdominal wall defects remains a huge surgical challenge. Tension-free repair is proven to be superior to suture repair in abdominal wall reconstruction. Scaffolds are essential for tension-free repair. They are used to bridge a defect or reinforce the abdominal wall. A huge variety of scaffolds are now commercially available. Most of the synthetic scaffolds are composed of polypropylene. They provide strong tissue reinforcement, but cause a foreign body reaction, which can result in serious complications. Absorbable synthetic scaffolds, such as Dexon™ (polyglycolic acid) and Vicryl™ (polyglactin 910), are not suitable for abdominal wall reconstruction as they usually require subsequent surgeries to repair recurrent hernias. Composite scaffolds combine the strength of nonabsorbable synthetic scaffolds with the antiadhesive properties of the absorbable scaffold, but require long-term follow-up. Biological scaffolds, such as Permacol™, Surgisis(®) and Alloderm(®), are derived from acellular mammalian tissues. Non-cross-linked biological scaffolds show excellent biocompatibility and degrade slowly over time. However, remnant DNA has been found in several products and the degradation leads to recurrence. Randomized controlled trials with long-term follow-up studies are lacking for all of the available scaffolds, particularly those derived from animal tissue. This article provides an overview of the different types of scaffolds available, and presents the key clinical studies of the commercially available synthetic, composite and biological scaffolds for abdominal wall reconstruction.

  20. Fluorescent composite scaffolds made of nanodiamonds/polycaprolactone

    NASA Astrophysics Data System (ADS)

    Cao, Li; Hou, Yanwen; Lafdi, Khalid; Urmey, Kirk

    2015-11-01

    Polycaprolactone (PCL) has been widely studied for biological applications. Biodegradable PCL fibrous scaffold can work as an appropriate substrate for tissue regeneration. In this letter, fluorescent nanodiamonds (FNDs) were prepared after surface passivation with octadecylamine. The FNDs were then mixed with PCL polymer and subsequently electrospun into FNDs/PCL fibrous scaffolds. The obtained scaffolds not only exhibited photoluminescence, but also showed reinforced mechanical strength. Toxicity study indicated FNDs/PCL scaffolds were nontoxic. This biocompatible fluorescent composite fibrous scaffold can support in vitro cell growth and also has the potential to act as an optical probe for tissue engineering application in vitro and in vivo.

  1. Facile fabrication of poly(L-lactic acid) microsphere-incorporated calcium alginate/hydroxyapatite porous scaffolds based on Pickering emulsion templates.

    PubMed

    Hu, Yang; Ma, Shanshan; Yang, Zhuohong; Zhou, Wuyi; Du, Zhengshan; Huang, Jian; Yi, Huan; Wang, Chaoyang

    2016-04-01

    In this study, we develop a facile one-pot approach to the fabrication of poly(L-lactic acid) (PLLA) microsphere-incorporated calcium alginate (ALG-Ca)/hydroxyapatite (HAp) porous scaffolds based on HAp nanoparticle-stabilized oil-in-water Pickering emulsion templates, which contain alginate in the aqueous phase and PLLA in the oil phase. The emulsion aqueous phase is solidified by in situ gelation of alginate with Ca(2+) released from HAp by decreasing pH with slow hydrolysis of D-gluconic acid δ-lactone (GDL) to produce emulsion droplet-incorporated gels, followed by freeze-drying to form porous scaffolds containing microspheres. The pore structure of porous scaffolds can be adjusted by varying the HAp or GDL concentration. The compressive tests show that the increase of HAp or GDL concentration is beneficial to improve the compressive property of porous scaffolds, while the excessive HAp can lead to the decrease in compressive property. Moreover, the swelling behavior studies display that the swelling ratios of porous scaffolds reduce with increasing HAp or GDL concentration. Furthermore, hydrophobic drug ibuprofen (IBU) and hydrophilic drug bovine serum albumin (BSA) are loaded into the microspheres and scaffold matrix, respectively. In vitro drug release results indicate that BSA has a rapid release while IBU has a sustained release in the dual drug-loaded scaffolds. In vitro cell culture experiments verify that mouse bone mesenchymal stem cells can proliferate on the porous scaffolds well, indicating the good biocompatibility of porous scaffolds. All these results demonstrate that the PLLA microsphere-incorporated ALG-Ca/HAp porous scaffolds have a promising potential for tissue engineering and drug delivery applications.

  2. Biomimetic composite microspheres of collagen/chitosan/nano-hydroxyapatite: In-situ synthesis and characterization.

    PubMed

    Teng, Shu-Hua; Liang, Mian-Hui; Wang, Peng; Luo, Yong

    2016-01-01

    The collagen/chitosan/hydroxyapatite (COL/CS/HA) composite microspheres with a good spherical form and a high dispersity were successfully obtained using an in-situ synthesis method. The FT-IR and XRD results revealed that the inorganic phase in the microspheres was crystalline HA containing carbonate ions. The morphology of the composite microspheres was dependent on the HA content, and a more desirable morphology was achieved when 20 wt.% HA was contained. The composite microspheres exhibited a narrow particle distribution, most of which ranged from 5 to 10 μm. In addition, the needle-like HA nano-particles were uniformly distributed in the composite microspheres, and their crystallinity and crystal size decreased with the HA content.

  3. Poly(lactic-co-glycolic) acid/nanohydroxyapatite scaffold containing chitosan microspheres with adrenomedullin delivery for modulation activity of osteoblasts and vascular endothelial cells.

    PubMed

    Wang, Lin; Li, Chunyan; Chen, Yingxin; Dong, Shujun; Chen, Xuesi; Zhou, Yanmin

    2013-01-01

    Adrenomedullin (ADM) is a bioactive regulatory peptide that affects migration and proliferation of diverse cell types, including endothelial cells, smooth muscle cells, and osteoblast-like cells. This study investigated the effects of sustained release of ADM on the modulation activity of osteoblasts and vascular endothelial cells in vitro. Chitosan microspheres (CMs) were developed for ADM delivery. Poly(lactic-co-glycolic) acid and nano-hydroxyapatite were used to prepare scaffolds containing microspheres with ADM. The CMs showed rough surface morphology and high porosity, and they were well-distributed. The scaffolds exhibited relatively uniform pore sizes with interconnected pores. The addition of CMs improved the mechanical properties of the scaffolds without affecting their high porosity. In vitro degradation tests indicated that the addition of CMs increased the water absorption of the scaffolds and inhibited pH decline of phosphate-buffered saline medium. The expression levels of osteogenic-related and angiogenic-related genes were determined in MG63 cells and in human umbilical vein endothelial cells cultured on the scaffolds, respectively. The expression levels of osteogenic-related and angiogenic-related proteins were also detected by western blot analysis. Their expression levels in cells were improved on the ADM delivery scaffolds at a certain time point. The in vitro evaluation suggests that the microsphere-scaffold system is suitable as a model for bone tissue engineering.

  4. Poly(lactic-co-glycolic) Acid/Nanohydroxyapatite Scaffold Containing Chitosan Microspheres with Adrenomedullin Delivery for Modulation Activity of Osteoblasts and Vascular Endothelial Cells

    PubMed Central

    Li, Chunyan; Chen, Yingxin; Dong, Shujun; Chen, Xuesi; Zhou, Yanmin

    2013-01-01

    Adrenomedullin (ADM) is a bioactive regulatory peptide that affects migration and proliferation of diverse cell types, including endothelial cells, smooth muscle cells, and osteoblast-like cells. This study investigated the effects of sustained release of ADM on the modulation activity of osteoblasts and vascular endothelial cells in vitro. Chitosan microspheres (CMs) were developed for ADM delivery. Poly(lactic-co-glycolic) acid and nano-hydroxyapatite were used to prepare scaffolds containing microspheres with ADM. The CMs showed rough surface morphology and high porosity, and they were well-distributed. The scaffolds exhibited relatively uniform pore sizes with interconnected pores. The addition of CMs improved the mechanical properties of the scaffolds without affecting their high porosity. In vitro degradation tests indicated that the addition of CMs increased the water absorption of the scaffolds and inhibited pH decline of phosphate-buffered saline medium. The expression levels of osteogenic-related and angiogenic-related genes were determined in MG63 cells and in human umbilical vein endothelial cells cultured on the scaffolds, respectively. The expression levels of osteogenic-related and angiogenic-related proteins were also detected by western blot analysis. Their expression levels in cells were improved on the ADM delivery scaffolds at a certain time point. The in vitro evaluation suggests that the microsphere-scaffold system is suitable as a model for bone tissue engineering. PMID:23841075

  5. Liquid Crystal Elastomer Microspheres as Three-Dimensional Cell Scaffolds Supporting the Attachment and Proliferation of Myoblasts.

    PubMed

    Bera, Tanmay; Freeman, Ernest J; McDonough, Jennifer A; Clements, Robert J; Aladlaan, Asaad; Miller, Donald W; Malcuit, Christopher; Hegmann, Torsten; Hegmann, Elda

    2015-07-08

    We report that liquid crystal elastomers (LCEs), often portrayed as artificial muscles, serve as scaffolds for skeletal muscle cell. A simultaneous microemulsion photopolymerization and cross-linking results in nematic LCE microspheres 10-30 μm in diameter that when conjoined form a LCE construct that serves as the first proof-of-concept for responsive LCE muscle cell scaffolds. Confocal microscopy experiments clearly established that LCEs with a globular, porous morphology permit both attachment and proliferation of C2C12 myoblasts, while the nonporous elastomer morphology, prepared in the absence of a microemulsion, does not. In addition, cytotoxicity and proliferation assays confirm that the liquid crystal elastomer materials are biocompatible promoting cellular proliferation without any inherent cytotoxicity.

  6. Preparation and characterization of bioactive mesoporous wollastonite - Polycaprolactone composite scaffold.

    PubMed

    Wei, Jie; Chen, Fangping; Shin, Jung-Woog; Hong, Hua; Dai, Chenglong; Su, Jiancan; Liu, Changsheng

    2009-02-01

    A well-defined mesoporous structure of wollastonite with high specific surface area was synthesized using surfactant P123 (triblock copolymer) as template, and its composite scaffolds with poly(epsilon-caprolactone) (PCL) were fabricated by a simple method of solvent casting-particulate leaching. The measurements of the water contact angles suggest that the incorporation of either mesoporous wollastonite (m-WS) or conventional wollastonite (c-WS) into PCL could improve the hydrophilicity of the composites, and the former was more effective than the later. The bioactivity of the composite scaffold was evaluated by soaking the scaffolds in a simulated body fluid (SBF) and the results show that the m-WS/PCL composite (m-WPC) scaffolds can induce a dense and continuous layer of apatite after soaking for 1 week, as compared with the scattered and discrete apatite particles on the c-WS/PCL composite (c-WPC) scaffolds. The m-WPC had a significantly enhanced apatite-forming bioactivity compared with the c-WPC owing to the high specific surface area and pore volume of m-WS. In addition, attachment and proliferation of MG(63) cells on m-WPC scaffolds were significantly higher than that of c-WPC, revealing that m-WPC scaffolds had excellent biocompatibility. Such improved properties of m-WPC should be helpful for developing new biomaterials and may have potential use in hard tissue repair.

  7. Physicochemical and mechanical properties of freeze cast hydroxyapatite-gelatin scaffolds with dexamethasone loaded PLGA microspheres for hard tissue engineering applications.

    PubMed

    Ghorbani, Farnaz; Nojehdehian, Hanieh; Zamanian, Ali

    2016-12-01

    Hydroxyapatite (HA)-gelatin scaffolds incorporated with dexamethasone-loaded polylactic-co-glycolic acid (PLGA) microspheres were synthesized by freeze casting technique. Scanning electron microscopy (SEM) micrographs demonstrated a unidirectional microstructure and a decrease in the pore size as a function of temperature gradient. Higher amounts of HA resulted in a decrease in the pore size. According to the results, at lower cooling rates, the formation of a lamellar structure decreased the mechanical strength, but at the same time, enhanced the swelling ratio, biodegradation rate and drug release level. On the other hand, higher weight ratios of HA increased the compressive strength, and reduced the swelling ratio, biodegradation rate and drug release level. The results obtained by furrier transform infrared spectroscopy (FTIR) and bioactivity analysis illustrated that the interactions of the materials support the apatite formation in the simulated body fluid (SBF) solution. Based on the obtained results, the synthesized composite scaffolds have the necessary mechanical and physicochemical features to support the regeneration of defects and to maintain their stability during the neo-tissue formation.

  8. Chitosan-poly(lactide-co-glycolide) microsphere-based scaffolds for bone tissue engineering: in vitro degradation and in vivo bone regeneration studies.

    PubMed

    Jiang, Tao; Nukavarapu, Syam P; Deng, Meng; Jabbarzadeh, Ehsan; Kofron, Michelle D; Doty, Stephen B; Abdel-Fattah, Wafa I; Laurencin, Cato T

    2010-09-01

    Natural polymer chitosan and synthetic polymer poly(lactide-co-glycolide) (PLAGA) have been investigated for a variety of tissue engineering applications. We have previously reported the fabrication and in vitro evaluation of a novel chitosan/PLAGA sintered microsphere scaffold for load-bearing bone tissue engineering applications. In this study, the in vitro degradation characteristics of the chitosan/PLAGA scaffold and the in vivo bone formation capacity of the chitosan/PLAGA-based scaffolds in a rabbit ulnar critical-sized-defect model were investigated. The chitosan/PLAGA scaffold showed slower degradation than the PLAGA scaffold in vitro. Although chitosan/PLAGA scaffold showed a gradual decrease in compressive properties during the 12-week degradation period, the compressive strength and compressive modulus remained in the range of human trabecular bone. Chitosan/PLAGA-based scaffolds were able to guide bone formation in a rabbit ulnar critical-sized-defect model. Microcomputed tomography analysis demonstrated that successful bridging of the critical-sized defect on the sides both adjacent to and away from the radius occurred using chitosan/PLAGA-based scaffolds. Immobilization of heparin and recombinant human bone morphogenetic protein-2 on the chitosan/PLAGA scaffold surface promoted early bone formation as evidenced by complete bridging of the defect along the radius and significantly enhanced mechanical properties when compared to the chitosan/PLAGA scaffold. Furthermore, histological analysis suggested that chitosan/PLAGA-based scaffolds supported normal bone formation via intramembranous formation.

  9. Controlling protein release from scaffolds using polymer blends and composites.

    PubMed

    Ginty, Patrick J; Barry, John J A; White, Lisa J; Howdle, Steve M; Shakesheff, Kevin M

    2008-01-01

    We report the development of three protein loaded polymer blend and composite materials that modify the release kinetics of the protein from poly(dl-lactic acid) (P(dl)LA) scaffolds. P(dl)LA has been combined with either poly(ethylene glycol) (PEG), poly(caprolactone) (PCL) microparticles or calcium alginate fibres using supercritical CO(2) (scCO(2)) processing to form single and dual protein release scaffolds. P(dl)LA was blended with the hydrophilic polymer PEG using scCO(2) to increase the water uptake of the resultant scaffold and modify the release kinetics of an encapsulated protein. This was demonstrated by the more rapid release of the protein when compared to the release rate from P(dl)LA only scaffolds. For the P(dl)LA/alginate scaffolds, the protein loaded alginate fibres were processed into porous protein loaded P(dl)LA scaffolds using scCO(2) to produce dual release kinetics from the scaffolds. Protein release from the hydrophilic alginate fibres was more rapid in the initial stages, complementing the slower release from the slower degrading P(dl)LA scaffolds. In contrast, when protein loaded PCL particles were loaded into P(dl)LA scaffolds, the rate of protein release was retarded from the slow degrading PCL phase.

  10. Development of Microspheres Covered with Hydroxyapatite Nanocrystals as Cell Scaffold for Angiogenesis

    NASA Astrophysics Data System (ADS)

    Iwamoto, Takashi; Terada, Takahiro; Kogai, Yasumichi; Okada, Masahiro; Fujii, Syuji; Furuzono, Tsutomu

    2012-06-01

    We prepared poly(L-lactide-co-glycolide) cell scaffolds coated with hydroxyapatite (HAp) nanocrystals with 50-100 nm in diameter via the Pickering emulsion method. Our cell scaffolds were composed of biodegradable polymers and HAp nanocrystals as a core and shell, respectively. The scaffolds were spherical but displayed uneven shapes when altering a shear speed of homogenization during syntheses. The surface coverage of HAp nanocrystals was examined because the HAp-coating ratio for the scaffolds was an important factor as cell scaffolds in order to enhance cell adhesion. On the basis of scanning electron microscopy observations and thermogravimetric analyses, it was found that the cell scaffolds showed distorted morphologies, and the HAp-coating ratio decreased with increasing the shear speed in the synthesis because shear stress influenced shapes of the scaffolds.

  11. Fabrication and characterization of bioactive wollastonite/PHBV composite scaffolds.

    PubMed

    Li, Haiyan; Chang, Jiang

    2004-11-01

    Composite scaffolds of polyhydroxybutyrate-polyhydroxyvalerate (PHBV) with bioactive wollastonite were fabricated by a compression moulding, thermal processing, and salt particulate leaching method. Structure and mechanical properties of the scaffolds were determined. The bioactivity of the composites was evaluated by soaking in a simulated body fluid (SBF), and the formation of the hydroxyapatite (HAp) layer was determined by Scanning Electron Microscope (SEM) and Energy-Dispersive Spectrometer (EDS). The results showed that the wollastonite/PHBV composites were bioactive as it induced the formation of HAp on the surface of the composite scaffolds after soaking in SBF for 14 days. In addition, the measurements of the water contact angles suggested that incorporation of wollastonite into PHBV could improve the hydrophilicity of the composites and the enhancement was dependent on the wollastonite content. Furthermore, the pH and ion concentration changes of SBF solutions with composite scaffolds showed that the composites released Ca and Si ions, which could neutralize the acidic by-products of the PHBV and stabilize the pH of the SBF solutions between 7.2 and 7.8 within a 3-week soaking period. All of these results suggest that the incorporation of wollastonite was a useful approach to obtain composite scaffolds with improved properties.

  12. Fabrication of HA/PHBV composite scaffolds through the emulsion freezing/freeze-drying process and characterisation of the scaffolds.

    PubMed

    Sultana, Naznin; Wang, Min

    2008-07-01

    Biodegradable polymer-based scaffolds containing osteoconductive hydroxyapatite (HA) particles can be very useful for bone tissue engineering. In this investigation, HA nanoparticles were incorporated in poly(hydroxybutyrate-co-valerate) (PHBV) polymer to fabricate osteoconductive composite scaffolds. PHBV and HA/PHBV scaffolds were made using an emulsion freezing/freeze-drying technique. The scaffolds produced were subsequently characterized using several techniques. It was found that the scaffolds were highly porous and had interconnected porous structures. The pore size ranged from several microns to around 300 microm. The spherical HA nanoparticles which were produced in-house through a nanoemulsion process could be incorporated into composite scaffolds although some of these nanoparticles existed on the surface of pore walls when a relatively large amount of HA was used for composite scaffolds. The incorporation of HA nanoparticles also enhanced compressive mechanical properties of the scaffolds.

  13. A protein delivery system: biodegradable alginate-chitosan-poly(lactic-co-glycolic acid) composite microspheres.

    PubMed

    Zheng, Cai-Hong; Gao, Jian-Qing; Zhang, Ye-Ping; Liang, Wen-Quan

    2004-10-29

    In the present study we developed alginate-chitosan-poly(lactic-co-glycolic acid) (PLGA) composite microspheres to elevate protein entrapment efficiency and decrease its burst release. Bovine serum albumin (BSA), which used as the model protein, was entrapped into the alginate microcapsules by a modified emulsification method in an isopropyl alcohol-washed way. The rapid drug releases were sustained by chitosan coating. To obtain the desired release properties, the alginate-chitosan microcapsules were further incorporated in the PLGA to form the composite microspheres. The average diameter of the composite microcapsules was 31+/-9microm and the encapsulation efficiency was 81-87%, while that of conventional PLGA microspheres was just 61-65%. Furthermore, the burst releases at 1h of BSA entrapped in composite microspheres which containing PLGA (50:50) and PLGA (70:30) decreased to 24% and 8% in PBS, and further decreased to 5% and 2% in saline. On the contrary, the burst releases of conventional PLGA microspheres were 48% and 52% in PBS, respectively. Moreover, the release profiles could be manipulated by regulating the ratios of poly(lactic acid) to poly(glycolic acid) in the composite microspheres.

  14. [Preparation and clinical application of polyvinyl alcohol/drug-loaded chitosan microsphere composite wound dressing].

    PubMed

    Zhang, Xiuju; Lin, Zhidan; Chen, Wenbin; Song, Ying; Li, Zhizhong

    2011-04-01

    In order to prepare and apply the polyvinyl alcohol/drug-loaded chitosan microspheres composite wound dressing, we first prepared chitosan microspheres by emulsion cross-linking method, and then added chitosan microspheres into the reactants during the acetalization of polyvinyl alcohol and formaldehyde. We further studied the morphology, water absorption, swelling degree, mechanical properties and in vitro release of the sponge with different amount of chitosan microspheres. The results showed that polyvinyl alcohol/drug-loaded chitosan composite sponge has porous structure with connectionism. Increasing the amount of chitosan microspheres would make the apertures smaller, so that the water absorption and the swelling of sponge decreased, but the tensile strength and compressive strength increased. With the increase of the amount of chitosan microspheres, the drug absorption of cefradine and the release rate increase, and the release time become longer. With the results of toxicity grade of 0 to 1, this type of composite sponge is non-toxic and meets the requirement of biocompatibility. The observation of rabbit nasal cavity after surgical operation suggested that polyvinyl acetal sponge modified with the chitosan has antiphlogistic, hemostatic and non-adherent characteristic, and can promote the healing and recovering of the nasalmucosa. After using this composite material, best growing surroundings for patients' granulation tissue were provided. Exposed bone and tendon were covered well with granulation tissue.

  15. Introduction of gelatin microspheres into an injectable calcium phosphate cement.

    PubMed

    Habraken, W J E M; de Jonge, L T; Wolke, J G C; Yubao, L; Mikos, A G; Jansen, J A

    2008-12-01

    For tissue engineered bone constructs, calcium phosphate cement (CPC) has a high potential as scaffold material because of its biocompatibility and osteoconductivity. However, in vivo resorption and tissue ingrowth is slow. To address these issues, microspheres can be incorporated into the cement, which will create macroporosity after in situ degradation. The goal of this study was to investigate the handling properties and degradation characteristics of CPC containing gelatin microspheres. Setting time and injectability were determined and an in vitro degradation study was performed. Samples were assayed on mass, compression strength, E-modulus, and morphology. A supplementary degradation test with gelatin microspheres was performed to investigate the influence of physical conditions inside the cement on microsphere stability. The gelatin microsphere CPCs were easy to inject and showed initial setting times of less than 3 min. After 12-weeks in vitro degradation no increase in macroporosity was observed, which was supported by the small mass loss and stabilizing mechanical strength. Even a clear densification of the composite was observed. Explanations for the lack of macroporosity were recrystallization of the cement onto or inside the gelatin spheres and a delayed degradation of gelatin microspheres inside the scaffold. The supplementary degradation test showed that the pH is a factor in the delayed gelatin microsphere degradation. Also differences in degradation rate between types of gelatin were observed. Overall, the introduction of gelatin microspheres into CPC renders composites with good handling properties, though the degradation characteristics should be further investigated to generate a macroporous scaffold.

  16. Comparative Investigation on Thermal Insulation of Polyurethane Composites Filled with Silica Aerogel and Hollow Silica Microsphere.

    PubMed

    Liu, Chunyuan; Kim, Jin Seuk; Kwon, Younghwan

    2016-02-01

    This paper presents a comparative study on thermal conductivity of PU composites containing open-cell nano-porous silica aerogel and closed-cell hollow silica microsphere, respectively. The thermal conductivity of PU composites is measured at 30 degrees C with transient hot bridge method. The insertion of polymer in pores of silica aerogel creates mixed interfaces, increasing the thermal conductivity of resulting composites. The measured thermal conductivity of PU composites filled with hollow silica microspheres is estimated using theoretical models, and is in good agreement with Felske model. It appears that the thermal conductivity of composites decreases with increasing the volume fraction (phi) when hollow silica microsphere (eta = 0.916) is used.

  17. Stimuli-responsive transformation in carbon nanotube/expanding microsphere-polymer composites

    PubMed Central

    Loomis, James; Xu, Peng; Panchapakesan, Balaji

    2013-01-01

    Our work introduces a class of stimuli-responsive expanding polymer composites with ability to unidirectionally transform physical dimensions, elastic modulus, density, and electrical resistance. Carbon nanotubes and core-shell acrylic microspheres were dispersed in polydimethylsiloxane, resulting in composites that exhibit a binary set of material properties. Upon thermal or infrared stimuli, liquid cores encapsulated within the microspheres vaporize, expanding the surrounding shells and stretching the matrix. Microsphere expansion results in visible dimensional changes, regions of reduced polymeric chain mobility, nanotube tensioning, and overall elastic to plastic-like transformation of the composite. Here we show composite transformations including macroscopic volume expansion (>500%), density reduction (>80%), and elastic modulus increase (>675%). Additionally, conductive nanotubes allow for remote expansion monitoring and exhibit distinct loading-dependent electrical responses. With ability to pattern regions of tailorable expansion, strength, and electrical resistance into a single polymer skin, these composites present opportunities as structural and electrical building blocks in smart systems. PMID:23574648

  18. Coaxial additive manufacture of biomaterial composite scaffolds for tissue engineering.

    PubMed

    Cornock, R; Beirne, S; Thompson, B; Wallace, G G

    2014-06-01

    An inherent difficulty associated with the application of suitable bioscaffolds for tissue engineering is the incorporation of adequate mechanical characteristics into the materials which recapitulate that of the native tissue, whilst maintaining cell proliferation and nutrient transfer qualities. Biomaterial composites fabricated using rapid prototyping techniques can potentially improve the functionality and patient-specific processing of tissue engineering scaffolds. In this work, a technique for the coaxial melt extrusion printing of core-shell scaffold structures was designed, implemented and assessed with respect to the repeatability, cell efficacy and scaffold porosity obtainable. Encapsulated alginate hydrogel/thermoplastic polycaprolactone (Alg-PCL) cofibre scaffolds were fabricated. Selective laser melting was used to produce a high resolution stainless steel 316 L coaxial extrusion nozzle, exhibiting diameters of 300 μm/900 μm for the inner and outer nozzles respectively. We present coaxial melt extrusion printed scaffolds of Alg-PCL cofibres with ~0.4 volume fraction alginate, with total fibre diameter as low as 600 μm and core material offset as low as 10% of the total diameter. Furthermore the tuneability of scaffold porosity, pore size and interconnectivity, as well as the preliminary inclusion, compatibility and survival of an L-929 mouse fibroblast cell-line within the scaffolds were explored. This preliminary cell work highlighted the need for optimal material selection and further design reiteration in future research.

  19. Bioactive glass/polymer composite scaffolds mimicking bone tissue.

    PubMed

    Gentile, Piergiorgio; Mattioli-Belmonte, Monica; Chiono, Valeria; Ferretti, Concetta; Baino, Francesco; Tonda-Turo, Chiara; Vitale-Brovarone, Chiara; Pashkuleva, Iva; Reis, Rui L; Ciardelli, Gianluca

    2012-10-01

    The aim of this work was the preparation and characterization of scaffolds with mechanical and functional properties able to regenerate bone. Porous scaffolds made of chitosan/gelatin (POL) blends containing different amounts of a bioactive glass (CEL2), as inorganic material stimulating biomineralization, were fabricated by freeze-drying. Foams with different compositions (CEL2/POL 0/100; 40/60; 70/30 wt %/wt) were prepared. Samples were crosslinked using genipin (GP) to improve mechanical strength and thermal stability. The scaffolds were characterized in terms of their stability in water, chemical structure, morphology, bioactivity, and mechanical behavior. Moreover, MG63 osteoblast-like cells and periosteal-derived stem cells were used to assess their biocompatibility. CEL2/POL samples showed interconnected pores having an average diameter ranging from 179 ± 5 μm for CEL2/POL 0/100 to 136 ± 5 μm for CEL2/POL 70/30. GP-crosslinking and the increase of CEL2 amount stabilized the composites to water solution (shown by swelling tests). In addition, the SBF soaking experiment showed a good bioactivity of the scaffold with 30 and 70 wt % CEL2. The compressive modulus increased by increasing CEL2 amount up to 2.1 ± 0.1 MPa for CEL2/POL 70/30. Dynamical mechanical analysis has evidenced that composite scaffolds at low frequencies showed an increase of storage and loss modulus with increasing frequency; furthermore, a drop of E' and E″ at 1 Hz was observed, and for higher frequencies both moduli increased again. Cells displayed a good ability to interact with the different tested scaffolds which did not modify cell metabolic activity at the analyzed points. MTT test proved only a slight difference between the two cytotypes analyzed.

  20. Developing bioactive composite scaffolds for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Chen, Yun

    Poly(L-lactic acid) (PLLA) films were fabricated using the method of dissolving and evaporation. PLLA scaffold was prepared by solid-liquid phase separation of polymer solutions and subsequent sublimation of solvent. Bonelike apatite coating was formed on PLLA films, PLLA scaffolds and poly(glycolic acid) (PGA) scaffolds in 24 hours through an accelerated biomimetic process. The ion concentrations in the simulated body fluid (SBF) were nearly 5 times of those in human blood plasma. The apatite formed was characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The apatite formed in 5SBF was similar in morphology and composition to that formed in the classical biomimetic process employing SBF or 1.5SBF, and similar to that of natural bone. This indicated that the biomimetic apatite coating process could be accelerated by using concentrated simulated body fluid at 37°C. Besides saving time, the accelerated biomimetic process is particularly significant to biodegradable polymers. Some polymers which degrade too fast to be coated with apatite by a classical biomimetic process, for example PGA, could be coated with bone-like apatite in an accelerated biomimetic process. Collagen and apatite were co-precipitated as a composite coating on poly(L-lactic acid) (PLLA) in an accelerated biomimetic process. The incubation solution contained collagen (1g/L) and simulated body fluid (SBF) with 5 times inorganic ionic concentrations as human blood plasma. The coating formed on PLLA films and scaffolds after 24 hours incubation was characterized using EDX, XRD, FTIR, and SEM. It was shown that the coating contained carbonated bone-like apatite and collagen, the primary constituents of natural bone. SEM showed a complex composite coating of submicron bone-like apatite particulates combined with collagen fibrils. This work provided an efficient process to obtain

  1. Composite PLA scaffolds reinforced with PDO fibers for tissue engineering.

    PubMed

    Cont, Liana; Grant, David; Scotchford, Colin; Todea, Milica; Popa, Catalin

    2013-02-01

    Novel composite scaffolds were produced using long continuous bidirectional fibers embedded in an electrospun matrix, with the aim of using them in soft tissue engineering applications. The fibers are of polydioxanone and the matrix of polylactic acid. The novel manufacturing method consists of direct electrospinning performed on both sides of a collector that supports the already arranged fibers. The scaffolds were tested in vitro using 3T3 mouse fibroblasts as-obtained or functionalized with biotin or poly (dopamine). Functionalization did not significantly affect cells attachment, metabolic activity, or proliferation, but poly (dopamine) was proven to be effective in inducing hydrophilicity to the surface.

  2. Synthesis of biodegradable polymer-mesoporous silica composite microspheres for DNA prime-protein boost vaccination.

    PubMed

    Ho, Jenny; Huang, Yi; Danquah, Michael K; Wang, Huanting; Forde, Gareth M

    2010-03-18

    DNA vaccines or proteins are capable of inducing specific immunity; however, the translation to the clinic has generally been problematic, primarily due to the reduced magnitude of immune response and poor pharmacokinetics. Herein we demonstrate a composite microsphere formulation, composed of mesoporous silica spheres (MPS) and poly(D,L-lactide-co-glycolide) (PLGA), enables the controlled delivery of a prime-boost vaccine via the encapsulation of plasmid DNA (pDNA) and protein in different compartments. Method with modified dual-concentric-feeding needles attached to a 40 kHz ultrasonic atomizer was studied. These needles focus the flow of two different solutions, which passed through the ultrasonic atomizer. The process synthesis parameters, which are important to the scale-up of composite microspheres, were also studied. These parameters include polymer concentration, feed flowrate, and volumetric ratio of polymer and pDNA-PEI/MPS-BSA. This fabrication technique produced composite microspheres with mean D[4,3] ranging from 6 to 34 microm, depending upon the microsphere preparation. The resultant physical morphology of composite microspheres was largely influenced by the volumetric ratio of pDNA-PEI/MPS-BSA to polymer, and this was due to the precipitation of MPS at the surface of the microspheres. The encapsulation efficiencies were predominantly in the range of 93-98% for pDNA and 46-68% for MPS. In the in vitro studies, the pDNA and protein showed different release kinetics in a 40 day time frame. The dual-concentric-feeding in ultrasonic atomization was shown to have excellent reproducibility. It was concluded that this fabrication technique is an effective method to prepare formulations containing a heterologous prime-boost vaccine in a single delivery system.

  3. Novel Alginate-Chitosan Composite Microspheres for Implant Delivery of Vancomycin and In Vivo Evaluation.

    PubMed

    Mao, Yimin; Zhao, Ming; Ge, Yongbiao; Fan, Jiang

    2016-09-01

    In this study, vancomycin loaded alginate-chitosan composite microspheres were developed by emulsion cross-linking method. The in vitro and vivo characterizations were done to evaluate the feasibility of application. Our experimental results showed that the emulsification cross-linking technique appeared to be a feasible method for the preparation of alginate-chitosan composite microspheres. The microspheres were spherical in shape and the mean particle size and drug loading were 25.3 ± 5.4 μm and 18.5 ± 2.3% respectively. A sustained vancomycin release was realized i.e. the amount of cumulative release increased in a time frame of 24 h to reach an amount i.e. ~68%. The model that fit best for vancomycin released from the microspheres was the Higuchi kinetic model with a correlation coefficient r = 0.9996. In vivo results showed that the application of microspheres not only reduced the toxicity, but also maintained effective drug concentration. In addition, no severe signs of epithelial necrosis and sloughing of epithelial cells were detected in histological studies.

  4. Porous nano-hydroxyapatite/collagen scaffold containing drug-loaded ADM-PLGA microspheres for bone cancer treatment.

    PubMed

    Rong, Zi-Jie; Yang, Lian-Jun; Cai, Bao-Ta; Zhu, Li-Xin; Cao, Yan-Lin; Wu, Guo-Feng; Zhang, Zan-Jie

    2016-05-01

    To develop adriamycin (ADM)-encapsulated poly(lactic-co-glycolic acid) (PLGA) nanoparticles in a porous nano-hydroxyapatite/collagen scaffold (ADM-PLGA-NHAC). To provide novel strategies for future treatment of osteosarcoma, the properties of the scaffold, including its in vitro extended-release properties, the inhibition effects of ADM-PLGA-NHAC on the osteosarcoma MG63 cells, and its bone repair capacity, were investigated in vivo and in vitro. The PLGA copolymer was utilized as a drug carrier to deliver ADM-PLGA nanoparticles (ADM-PLGA-NP). Porous nano-hydroxyapatite and collagen were used to materials to produce the porous nano-hydroxyapatite/collagen scaffold (NHAC), into which the ADM-PLGA-NP was loaded. The performance of the drug-carrying scaffold was assessed using multiple techniques, including scanning electron microscopy and in vitro extended release. The antineoplastic activities of scaffold extracts on the human osteosarcoma MG63 cell line were evaluated in vitro using the cell counting kit-8 (CCK8) method and live-dead cell staining. The bone repair ability of the scaffold was assessed based on the establishment of a femoral condyle defect model in rabbits. ADM-PLGA-NHAC and NHAC were implanted into the rat muscle bag for immune response experiments. A tumor-bearing nude mice model was created, and the TUNEL and HE staining results were observed under optical microscopy to evaluate the antineoplastic activity and toxic side effects of the scaffold. The composite scaffold demonstrated extraordinary extended-release properties, and its extracts also exhibited significant inhibition of the growth of osteosarcoma MG63 cells. In the bone repair experiment, no significant difference was observed between ADM-PLGA-NHAC and NHAC by itself. In the immune response experiments, ADM-PLGA-NHAC exhibited remarkable biocompatibility. The in vivo antitumor experiment revealed that the implantation of ADM-PLGA-NHAC in the tumor resulted in a improved antineoplastic

  5. Polyacrylate microspheres composite for all-solid-state reference electrodes.

    PubMed

    Kisiel, Anna; Donten, Mikołaj; Mieczkowski, Józef; Rius-Ruiz, F Xavier; Maksymiuk, Krzysztof; Michalska, Agata

    2010-09-01

    A novel concept is proposed for the encapsulation of components within polyacrylate microspheres, prior to their incorporation into a membrane phase. Thus finer and better controlled dispersion of heterogeneous membrane components can be achieved. This concept was verified by using a poly(n-butyl acrylate) membrane-based reference electrode as an example. In this example the proper dispersion of solid constituents of the heterogeneous membrane and prevention of their leakage are both of primary importance. Potassium chloride-loaded poly(n-butyl acrylate) microspheres were prepared and then left in contact with silver nitrate to convert some of the KCl into AgCl. The material obtained was introduced into a poly(n-butyl acrylate) membrane. The reference electrode membranes obtained in this way were characterized with much more stable potential (both in different electrolytes and over time) compared with electrodes prepared by the direct introduction of KCl and AgCl to the membrane.

  6. The fabrication and characterization of biodegradable HA/PHBV nanoparticle-polymer composite scaffolds.

    PubMed

    Jack, Kevin S; Velayudhan, Shiny; Luckman, Paul; Trau, Matt; Grøndahl, Lisbeth; Cooper-White, Justin

    2009-09-01

    This study reports the fabrication and characterization of nano-sized hydroxyapatite (HA)/poly(hydroxyabutyrate-co-hydroxyvalerate) (PHBV) polymer composite scaffolds with high porosity and controlled pore architectures. These scaffolds were prepared using a modified thermally induced phase-separation technique. This investigation focuses on the effect of fabrication conditions on the overall pore architecture of the scaffolds and the dispersion of HA nanocrystals within the composite scaffolds. The morphologies, mechanical properties and in vitro bioactivity of the composite scaffolds were investigated. It was noted that the pore architectures could be manipulated by varying phase-separation parameters. The HA particles were dispersed in the pore walls of the scaffolds and were well bonded to the polymer. The introduction of HA greatly increased the stiffness and strength, and improved the in vitro bioactivity of the scaffolds. The results suggest these newly developed nano-HA/PHBV composite scaffolds may serve as an effective three-dimensional substrate in bone tissue engineering.

  7. Development of Composite Scaffolds for Load Bearing Segmental Bone Defects

    DTIC Science & Technology

    2013-07-01

    progressed from laboratory benchtop studies to preclinical testing in animals. This review is based on an exhaustive literature search of various...follow, a comprehensive review of in vivo models used to test composite scaffolds in SBDs is detailed to serve as a guide to design appropriate...related to fractures, sport and blast injuries. Diseases include bone cancer (osteosarcoma), tumor resection and reconstruction, osteoporosis

  8. Poly(3-hydroxybutyrate) multifunctional composite scaffolds for tissue engineering applications.

    PubMed

    Misra, Superb K; Ansari, Tahera I; Valappil, Sabeel P; Mohn, Dirk; Philip, Sheryl E; Stark, Wendelin J; Roy, Ipsita; Knowles, Jonathan C; Salih, Vehid; Boccaccini, Aldo R

    2010-04-01

    Poly(3-hydroxybutyrate) (P(3HB)) foams exhibiting highly interconnected porosity (85% porosity) were prepared using a unique combination of solvent casting and particulate leaching techniques by employing commercially available sugar cubes as porogen. Bioactive glass (BG) particles of 45S5 Bioglass grade were introduced in the scaffold microstructure, both in micrometer ((m-BG), <5 microm) and nanometer ((n-BG), 30 nm) sizes. The in vitro bioactivity of the P(3HB)/BG foams was confirmed within 10 days of immersion in simulated body fluid and the foams showed high level of protein adsorption. The foams interconnected porous microstructure proved to be suitable for MG-63 osteoblast cell attachment and proliferation. The foams implanted in rats as subcutaneous implants resulted in a non-toxic and foreign body response after one week of implantation. In addition to showing bioactivity and biocompatibility, the P(3HB)/BG composite foams also exhibited bactericidal properties, which was tested on the growth of Staphylococcus aureus. An attempt was made at developing multifunctional scaffolds by incorporating, in addition to BG, selected concentrations of Vitamin E or/and carbon nanotubes. P(3HB) scaffolds with multifunctionalities (viz. bactericidal, bioactive, electrically conductive, antioxidative behaviour) were thus produced, which paves the way for next generation of advanced scaffolds for bone tissue engineering.

  9. In vitro evaluation of alginate/halloysite nanotube composite scaffolds for tissue engineering.

    PubMed

    Liu, Mingxian; Dai, Libing; Shi, Huizhe; Xiong, Sheng; Zhou, Changren

    2015-04-01

    In this study, a series of alginate/halloysite nanotube (HNTs) composite scaffolds were prepared by solution-mixing and freeze-drying method. HNTs are incorporated into alginate to improve both the mechanical and cell-attachment properties of the scaffolds. The interfacial interactions between alginate and HNTs were confirmed by the atomic force microscope (AFM), transmission electron microscope (TEM) and FTIR spectroscopy. The mechanical, morphological, and physico-chemical properties of the composite scaffolds were investigated. The composite scaffolds exhibit significant enhancement in compressive strength and compressive modulus compared with pure alginate scaffold both in dry and wet states. A well-interconnected porous structure with size in the range of 100-200μm and over 96% porosity is found in the composite scaffolds. X-ray diffraction (XRD) result shows that HNTs are uniformly dispersed and partly oriented in the composite scaffolds. The incorporation of HNTs leads to increase in the scaffold density and decrease in the water swelling ratio of alginate. HNTs improve the stability of alginate scaffolds against enzymatic degradation in PBS solution. Thermogravimetrica analysis (TGA) shows that HNTs can improve the thermal stability of the alginate. The mouse fibroblast cells display better attachment to the alginate/HNT composite than those to the pure alginate, suggesting the good cytocompatibility of the composite scaffolds. Alginate/HNT composite scaffolds exhibit great potential for applications in tissue engineering.

  10. Biomimetic and bioactive nanofibrous scaffolds from electrospun composite nanofibers

    PubMed Central

    Zhang, YZ; Su, B; Venugopal, J; Ramakrishna, S; Lim, CT

    2007-01-01

    Electrospinning is an enabling technology that can architecturally (in terms of geometry, morphology or topography) and biochemically fabricate engineered cellular scaffolds that mimic the native extracellular matrix (ECM). This is especially important and forms one of the essential paradigms in the area of tissue engineering. While biomimesis of the physical dimensions of native ECM’s major constituents (eg, collagen) is no longer a fabrication-related challenge in tissue engineering research, conveying bioactivity to electrospun nanofibrous structures will determine the efficiency of utilizing electrospun nanofibers for regenerating biologically functional tissues. This can certainly be achieved through developing composite nanofibers. This article gives a brief overview on the current development and application status of employing electrospun composite nanofibers for constructing biomimetic and bioactive tissue scaffolds. Considering that composites consist of at least two material components and phases, this review details three different configurations of nanofibrous composite structures by using hybridizing basic binary material systems as example. These are components blended composite nanofiber, core-shell structured composite nanofiber, and nanofibrous mingled structure. PMID:18203429

  11. Angiogenic Effects of Collagen/Mesoporous Nanoparticle Composite Scaffold Delivering VEGF165

    PubMed Central

    Kim, Tae-Hyun; Kang, Min Sil

    2016-01-01

    Vascularization is a key issue for the success of tissue engineering to repair damaged tissue. In this study, we report a composite scaffold delivering angiogenic factor for this purpose. Vascular endothelial growth factor (VEGF) was loaded on mesoporous silica nanoparticle (MSN), which was then incorporated within a type I collagen sponge, to produce collagen/MSN/VEGF (CMV) scaffold. The CMV composite scaffold could release VEGF sustainably over the test period of 28 days. The release of VEGF improved the cell proliferation. Moreover, the in vivo angiogenesis of the scaffold, as studied by the chick chorioallantoic membrane (CAM) model, showed that the VEGF-releasing scaffold induced significantly increased number of blood vessel complexes when compared with VEGF-free scaffold. The composite scaffold showed good biocompatibility, as examined in rat subcutaneous tissue. These results demonstrate that the CMV scaffold with VEGF-releasing capacity can be potentially used to stimulate angiogenesis and tissue repair. PMID:27689093

  12. Biodegradable composite scaffolds: a strategy to modulate stem cell behaviour.

    PubMed

    Armentano, Ilaria; Fortunati, Elena; Mattioli, Samantha; Rescignano, Nicolatta; Kenny, José M

    2013-04-01

    The application of new biomaterial technologies offers the potential to direct the stem cell fate, targeting the delivery of cells and reducing immune rejection, thereby supporting the development of regenerative medicine. Cells respond to their surrounding structure and with nanostructures exhibit unique proliferative and differentiation properties. This review presents the relevance, the promising perspectives and challenges of current biodegradable composite scaffolds in terms of material properties, processing technology and surface modification, focusing on significant recent patents in these fields. It has been reported how biodegradable porous composite scaffolds can be engineered with initial properties that reproduce the anisotropy, viscoelasticity, tension-compression non-linearity of different tissues by introducing specific nanostructures. Moreover the modulation of electrical, morphological, surface and topographic scaffold properties enables specific stem cell response. Recent advances in nanotechnology have allowed to engineer novel biomaterials with these complexity levels. Understanding the specific biological response triggered by various aspects of the fibrous environment is important in guiding the design and engineering of novel substrates that mimic the native cell matrix interactions in vivo.

  13. Anisotropic photoelectric film assembled from mesoporous silica (MS)@CuO@FeS2 composite microspheres for improving photoelectric conversion.

    PubMed

    Zong, Jie; Zhu, Yihua; Shen, Jianhua; Yang, Xiaoling; Li, Chunzhong

    2013-07-15

    We report a novel strategy for the fabrication of mesoporous silica (MS)@CuO@FeS2 composite microsphere-based anisotropic films that combine the advantages of the CuO and FeS2 materials to improve photoelectric conversion. This was achieved by aligning MS@CuO@FeS2 composite microspheres in a cross-linked gel under a homogeneous magnetic field. The MS@CuO@FeS2 composite microspheres, which were synthesized by a simple layer-by-layer (LbL) self-assembly technique together with a solvothermal method, can absorb a wide range of light and exhibit ferromagnetic properties. In addition, the resulting MS@CuO@FeS2 composite microsphere-based anisotropic film shows photoelectric anisotropy. Such systems are promising for improving the performance of solar cells.

  14. Electroactive biomimetic collagen-silver nanowire composite scaffolds

    NASA Astrophysics Data System (ADS)

    Wickham, Abeni; Vagin, Mikhail; Khalaf, Hazem; Bertazzo, Sergio; Hodder, Peter; Dånmark, Staffan; Bengtsson, Torbjörn; Altimiras, Jordi; Aili, Daniel

    2016-07-01

    Electroactive biomaterials are widely explored as bioelectrodes and as scaffolds for neural and cardiac regeneration. Most electrodes and conductive scaffolds for tissue regeneration are based on synthetic materials that have limited biocompatibility and often display large discrepancies in mechanical properties with the surrounding tissue causing problems during tissue integration and regeneration. This work shows the development of a biomimetic nanocomposite material prepared from self-assembled collagen fibrils and silver nanowires (AgNW). Despite consisting of mostly type I collagen fibrils, the homogeneously embedded AgNWs provide these materials with a charge storage capacity of about 2.3 mC cm-2 and a charge injection capacity of 0.3 mC cm-2, which is on par with bioelectrodes used in the clinic. The mechanical properties of the materials are similar to soft tissues with a dynamic elastic modulus within the lower kPa range. The nanocomposites also support proliferation of embryonic cardiomyocytes while inhibiting the growth of both Gram-negative Escherichia coli and Gram-positive Staphylococcus epidermidis. The developed collagen/AgNW composites thus represent a highly attractive bioelectrode and scaffold material for a wide range of biomedical applications.Electroactive biomaterials are widely explored as bioelectrodes and as scaffolds for neural and cardiac regeneration. Most electrodes and conductive scaffolds for tissue regeneration are based on synthetic materials that have limited biocompatibility and often display large discrepancies in mechanical properties with the surrounding tissue causing problems during tissue integration and regeneration. This work shows the development of a biomimetic nanocomposite material prepared from self-assembled collagen fibrils and silver nanowires (AgNW). Despite consisting of mostly type I collagen fibrils, the homogeneously embedded AgNWs provide these materials with a charge storage capacity of about 2.3 mC cm-2

  15. Biocompatibility and osteogenesis of biomimetic nano-hydroxyapatite/polyamide composite scaffolds for bone tissue engineering.

    PubMed

    Wang, Huanan; Li, Yubao; Zuo, Yi; Li, Jihua; Ma, Sansi; Cheng, Lin

    2007-08-01

    In this study, we prepared nano-hydroxyapatite/polyamide (n-HA/PA) composite scaffolds utilizing thermally induced phase inversion processing technique. The macrostructure and morphology as well as mechanical strength of the scaffolds were characterized. Mesenchymal stem cells (MSCs) derived from bone marrow of neonatal rabbits were cultured, expanded and seeded on n-HA/PA scaffolds. The MSC/scaffold constructs were cultured for up to 7 days and the adhesion, proliferation and differentiation of MSCs into osteoblastic phenotype were determined using MTT assay, alkaline phosphatase (ALP) activity and collagen type I (COL I) immunohistochemical staining and scanning electronic microscopy (SEM). The results confirm that n-HA/PA scaffolds are biocompatible and have no negative effects on the MSCs in vitro. To investigate the in vivo biocompatibility and osteogenesis of the composite scaffolds, both pure n-HA/PA scaffolds and MSC/scaffold constructs were implanted in rabbit mandibles and studied histologically and microradiographically. The results show that n-HA/PA composite scaffolds exhibit good biocompatibility and extensive osteoconductivity with host bone. Moreover, the introduction of MSCs to the scaffolds dramatically enhanced the efficiency of new bone formation, especially at the initial stage after implantation. In long term (more than 12 weeks implantation), however, the pure scaffolds show as good biocompatibility and osteogenesis as the hybrid ones. All these results indicate that the scaffolds fulfill the basic requirements of bone tissue engineering scaffold, and have the potential to be applied in orthopedic, reconstructive and maxillofacial surgery.

  16. Improving mechanical and biological properties of macroporous HA scaffolds through composite coatings.

    PubMed

    Zhao, J; Lu, X; Duan, K; Guo, L Y; Zhou, S B; Weng, J

    2009-11-01

    Interconnected porous hydroxyapatite (HA) scaffolds are widely used for bone repair and replacement, owing to their ability to support the adhesion, transfer, proliferation and differentiation of cells. In the present study, the polymer impregnation approach was adopted to produce porous HA scaffolds with three-dimensional (3D) porous structures. These scaffolds have an advantage of highly interconnected porosity (approximately 85%) but a drawback of poor mechanical strength. Therefore, the as-prepared HA scaffolds were lined with composite polymer coatings in order to improve the mechanical properties and retain its good bioactivity and biocompatibility at the same time. The composite coatings were based on poly(D,L-lactide) (PDLLA) polymer solutions, and contained single component or combination of HA, calcium sulfate (CS) and chondroitin sulfate (ChS) powders. The effects of composite coatings on scaffold porosity, microstructure, mechanical property, in vitro mineralizing behavior, and cell attachment of the resultant scaffolds were investigated. The results showed that the scaffolds with composite coatings resulted in significant improvement in both mechanical and biological properties while retaining the 3D interconnected porous structure. The in vitro mineralizing behaviors were mainly related to the compositions of CS and ChS powders in the composite coatings. Excellent cell attachments were observed on the pure HA scaffold as well as the three types of composite scaffolds. These composite scaffolds with improved mechanical properties and bioactivities are promising bone substitutes in tissue engineering fields.

  17. Hydroxyapatite reinforced inherent RGD containing silk fibroin composite scaffolds: Promising platform for bone tissue engineering.

    PubMed

    Behera, Sibaram; Naskar, Deboki; Sapru, Sunaina; Bhattacharjee, Promita; Dey, Tuli; Ghosh, Ananta K; Mandal, Mahitosh; Kundu, Subhas C

    2017-03-08

    Replacement and repair of ectopic bone defects and traumatized bone tissues are done using porous scaffolds and composites. The prerequisites for such scaffolds include high mechanical strength, osseoconductivity and cytocompatibility. The present work is designed to address such requirements by fabricating a reinforced cytocompatible scaffold. Biocompatible silk protein fibroin collected from tropical non-mulberry tasar silkworm (Antheraea mylitta) is used to fabricate fibroin-hydroxyapatite (HAp) nanocomposite particles using chemical precipitation method. In situ reinforcement of fibroin-HAp nanocomposite and external deposition of HAp particles on fibroin scaffold is carried out for comparative evaluations of bio-physical and biochemical characteristics. HAp deposited fibroin scaffolds provide greater mechanical strength and cytocompatibility, when compared with fibroin-HAp nanoparticles reinforced fibroin scaffolds. Minimal immune responses of both types of composite scaffolds are observed using osteoblast-macrophage co-culture model. Nanocomposite reinforced fibroin scaffold can be tailored further to accommodate different requirements depending on bone type or bone regeneration period.

  18. The effect of porosity on drug release kinetics from vancomycin microsphere/calcium phosphate cement composites.

    PubMed

    Schnieders, Julia; Gbureck, Uwe; Vorndran, Elke; Schossig, Michael; Kissel, Thomas

    2011-11-01

    The influence of porosity on release profiles of antibiotics from calcium phosphate composites was investigated to optimize the duration of treatment. We hypothesized, that by the encapsulation of vancomycin-HCl into biodegradable microspheres prior admixing to calcium phosphate bone cement, the influence of porosity of the cement matrix on vancomycin release could be reduced. Encapsulation of vancomycin into a biodegradable poly(lactic co-glycolic acid) copolymer (PLGA) was performed by spray drying; drug-loaded microparticles were added to calcium phosphate cement (CPC) at different powder to liquid ratios (P/L), resulting in different porosities of the cement composites. The effect of differences in P/L ratio on drug release kinetics was compared for both the direct addition of vancomycin-HCl to the cement liquid and for cement composites modified with vancomycin-HCl-loaded microspheres. Scanning electron microscopy (SEM) was used to visualize surface and cross section morphology of the different composites. Brunauer, Emmett, and Teller-plots (BET) was used to determine the specific surface area and pore size distribution of these matrices. It could be clearly shown, that variations in P/L ratio influenced both the porosity of cement and vancomycin release profiles. Antibiotic activity during release study was successfully measured using an agar diffusion assay. However, vancomycin-HCl encapsulation into PLGA polymer microspheres decreased porosity influence of cement on drug release while maintaining antibiotic activity of the embedded substance.

  19. Hierarchical ZnO-Ag-C composite porous microspheres with superior electrochemical properties as anode materials for lithium ion batteries.

    PubMed

    Xie, Qingshui; Ma, Yating; Zeng, Deqian; Zhang, Xiaoqiang; Wang, Laisen; Yue, Guanghui; Peng, Dong-Liang

    2014-11-26

    Hierarchical ZnO-Ag-C composite porous microspheres are successfully synthesized by calcination of the preproduced zinc-silver citrate porous microspheres in argon. The carbon derives from the in situ carbonization of carboxylic acid groups in zinc-silver citrate during annealing treatment. The average particle size of ZnO-Ag-C composite porous microspheres is approximate 1.5 μm. When adopted as the electrode materials in lithium ion batteries, the obtained composite porous microspheres display high specific capacity, excellent cyclability, and good rate capability. A discharge capacity as high as 729 mA h g(-1) can be retained after 200 cycles at 100 mA g(-1). The excellent electrochemical properties of ZnO-Ag-C are ascribed to its unique hierarchical porous configuration as well as the modification of silver and carbon.

  20. Evaluation of PHBV/calcium silicate composite scaffolds for cartilage tissue engineering

    NASA Astrophysics Data System (ADS)

    Wu, Jun; Sun, Junying; Liu, Jinbo

    2014-10-01

    In our previous studies, composite scaffolds containing poly (hydroxybutyrate-co-hydroxyvalerate) (PHBV) and calcium silicate (CS) have been prepared and well characterized as cell scaffolds. Here, we evaluated these composite scaffolds for cartilage tissue engineering through in vitro experiments of cell-scaffold interactions and in vivo observation of cartilage formation. Rabbit articular chondrocytes were seeded into PHBV and PHBV/CS scaffolds. A short-term in vitro culture followed by a long-term in vivo transplantation was performed to evaluate the difference of cartilage regeneration in PHBV and PHBV/CS scaffolds. Results showed that, as compared to pure PHBV scaffolds, the addition of CS into PHBV improved the cell adhesion on the scaffolds and further promoted the cell penetration into scaffolds. In vivo results indicated that the PHBV/CS composite scaffolds enhanced the formation of cartilage-like tissue as thicker and stronger cartilage matrix was found in PHBV/CS group as compared to those in PHBV group. These results demonstrated that the PHBV/CS scaffolds may be more suitable for applications in cartilage tissue engineering that pure PHBV scaffolds.

  1. Porous silicon oxide-PLGA composite microspheres for sustained ocular delivery of daunorubicin.

    PubMed

    Nan, Kaihui; Ma, Feiyan; Hou, Huiyuan; Freeman, William R; Sailor, Michael J; Cheng, Lingyun

    2014-08-01

    A water-soluble anthracycline antibiotic drug (daunorubicin, DNR) was loaded into oxidized porous silicon (pSiO2) microparticles and then encapsulated with a layer of polymer (poly lactide-co-glycolide, PLGA) to investigate their synergistic effects in control of DNR release. Similarly fabricated PLGA-DNR microspheres without pSiO2, and pSiO2 microparticles without PLGA were used as control particles. The composite microparticles synthesized by a solid-in-oil-in-water emulsion method have mean diameters of 52.33±16.37μm for PLGA-pSiO2_21/40-DNR and the mean diameter of 49.31±8.87μm for PLGA-pSiO2_6/20-DNR. The mean size, 26.00±8μm, of PLGA-DNR was significantly smaller, compared with the other two (P<0.0001). Optical microscopy revealed that PLGA-pSiO2-DNR microspheres contained multiple pSiO2 particles. In vitro release experiments determined that control PLGA-DNR microspheres completely released DNR within 38days and control pSiO2-DNR microparticles (with no PLGA coating) released DNR within 14days, while the PLGA-pSiO2-DNR microspheres released DNR for 74days. Temporal release profiles of DNR from PLGA-pSiO2 composite particles indicated that both PLGA and pSiO2 contribute to the sustained release of the payload. The PLGA-pSiO2 composite displayed a more constant rate of DNR release than the pSiO2 control formulation, and displayed a significantly slower release of DNR than either the PLGA or pSiO2 formulations. We conclude that this system may be useful in managing unwanted ocular proliferation when formulated with antiproliferation compounds such as DNR.

  2. Preparation, physicochemical properties and biocompatibility of PBLG/PLGA/bioglass composite scaffolds.

    PubMed

    Cui, Ning; Qian, Junmin; Wang, Jinlei; Ji, Chuanlei; Xu, Weijun; Wang, Hongjie

    2017-02-01

    In this study, novel poly(γ-benzyl l-glutamate)/poly(lactic-co-glycolic acid)/bioglass (PBLG/PLGA/BG) composite scaffolds with different weight ratios were fabricated using a negative NaCl-templating method. The morphology, compression modulus and degradation kinetics of the scaffolds were characterized. The results showed that the PBLG/PLGA/BG composite scaffolds with a weight ratio of 5:5:1, namely PBLG5PLGA5BG composite scaffolds, displayed a pore size range of 50-500μm, high compressive modulus (566.6±8.8kPa), suitable glass transition temperature (46.8±0.2°C) and low degradation rate (>8weeks). The in vitro biocompatibility of the scaffolds was evaluated with MC3T3-E1 cells by live-dead staining, MTT and ALP activity assays. The obtained results indicated that the PBLG5PLGA5BG composite scaffolds were more conducive to the adhesion, proliferation and osteoblastic differentiation of MC3T3-E1 cells than PBLG and PBLG/PLGA composite scaffolds. The in vivo biocompatibility of the scaffolds was evaluated in both SD rat subcutaneous model and rabbit tibia defect model. The results of H&E, Masson's trichrome and CD34 staining assays demonstrated that the PBLG5PLGA5BG composite scaffolds allowed the ingrowth of tissue and microvessels more effectively than PBLG/PLGA composite scaffolds. The results of digital radiography confirmed that the PBLG5PLGA5BG composite scaffolds significantly improved in vivo osteogenesis. Collectively, the PBLG5PLGA5BG composite scaffolds could be a promising candidate for tissue engineering applications.

  3. Porous Hydroxyapatite Scaffold with Three-Dimensional Localized Drug Delivery System Using Biodegradable Microspheres

    DTIC Science & Technology

    2011-03-21

    such as hydroxyapa- tite [(Ca10(PO4)6(OH)2), HAp] is known for its excellent biocompat- ibility due to its similarity in composition to the apatite ...were radio- frequency (RF) plasma glow-discharged (PDC-32 G, Harrick Plasma, USA) in oxygen -filled chamber at a pressure of 200 mTorr Pa and at 40 mA...The plasma power density and the treatment time were fixed at 30 W and 30 s, respectively. The second step involved dispersing the oxygen plasma

  4. Migration of Co-cultured Endothelial Cells and Osteoblasts in Composite Hydroxyapatite/Polylactic Acid Scaffolds

    DTIC Science & Technology

    2011-07-16

    Migration of Co-cultured Endothelial Cells and Osteoblasts in Composite Hydroxyapatite/ Polylactic Acid Scaffolds AMITA R. SHAH,1,2,3 SARITA R. SHAH,2...bone. A scaffold design consisting of a hydroxy apatite (HA) ring surrounding a polylactic acid (PLA) core simulates the structure of bone and provides...and osteoblasts in composite hydroxyapatite/ polylactic acid scaffolds. 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR

  5. Fabrication, characterization, and in vitro degradation of composite scaffolds based on PHBV and bioactive glass.

    PubMed

    Li, Haiyan; Du, Ruilin; Chang, Jiang

    2005-10-01

    Composite scaffolds of polyhydroxybutyrate-polyhydroxyvalerate (PHBV) with sol-gel-derived bioactive glass (BG, 58S) are fabricated by compression molding, thermal processing, and salt particulate leaching method. Structure and mechanical properties of the scaffolds are determined. The bioactivity of the composites is evaluated by soaking the scaffolds in a simulated body fluid (SBF), and the formation of the apatite layer on the scaffolds is determined by scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). The results show that the PHBV/BG composites are bioactive as they induce the formation of apatite on the composite scaffolds after soaking in SBF for 3 days. In addition, the measurements of the water contact angles suggest that incorporation of BG into PHBV can improve the hydrophilicity of the composites and the enhancement is dependent on the BG content. Furthermore, the degradation assessment of the scaffolds is performed in phosphate-buffered saline (PBS) solution at 37 C. Weight loss and water absorption of the scaffolds, pH of the incubation media, and molecular weight measurements of the PHBV in the scaffolds are used to monitor the degradation of the scaffolds during a nine-week incubation in PBS. It has been found that the incorporation of bioactive glass into the PHBV delayed the degradation of PHBV in the composite scaffolds for the period investigated. The present results show not only a useful method to prepare composite scaffolds with improved properties but also a way of adjusting the in vitro degradation behavior of composite scaffolds by tailoring the content of bioactive glass.

  6. Novel hydroxyapatite/carboxymethylchitosan composite scaffolds prepared through an innovative "autocatalytic" electroless coprecipitation route.

    PubMed

    Oliveira, J M; Costa, S A; Leonor, I B; Malafaya, P B; Mano, J F; Reis, R L

    2009-02-01

    A developmental composite scaffold for bone tissue engineering applications composed of hydroxyapatite (HA) and carboxymethylchitosan (CMC) was obtained using a coprecipitation method, which is based on the "autocatalytic" electroless deposition route. The results revealed that the pores of the scaffold were regular, interconnected, and possess a size in the range of 20-500 microm. Furthermore, the Fourier transform infra-red spectrum of the composite scaffolds exhibited all the characteristic peaks of apatite, and the appearance of typical bands from CMC, thus showing that coprecipitation of both organic and inorganic phases was effective. The X-ray diffraction pattern of composite scaffolds demonstrated that calcium-phosphates consisted of crystalline HA. From microcomputed tomography analysis, it was possible to determine that composite scaffolds possess a 58.9% +/- 6% of porosity. The 2D morphometric analysis demonstrated that on average the scaffolds consisted of 24% HA and 76% CMC. The mechanical properties were assessed using compressive tests, both in dry and wet states. Additionally, in vitro tests were carried out to evaluate the water-uptake capability, weight loss, and bioactive behavior of the composite scaffolds. The novel hydroxyapatite/carboxymethylchitosan composite scaffolds showed promise whenever degradability and bioactivity are simultaneously desired, as in the case of bone tissue-engineering scaffolding applications.

  7. Ultrasonic preparation of hierarchical graphene-oxide/TiO2 composite microspheres for efficient photocatalytic hydrogen production.

    PubMed

    Gao, Peng; Sun, Darren Delai

    2013-11-01

    Hierarchical graphene oxide (GO)-TiO2 composite microspheres with different GO/TiO2 mass ratios were successfully prepared by mixing GO and TiO2 microspheres under ultrasonic conditions. Ultrasonication helped the GO and TiO2 microsphere to uniformly mix on the microscale. The results showed that the GO-TiO2 composites that were prepared by ultrasonic mixing exhibited significantly higher hydrogen-evolution rates than those that were synthesized by simple mechanical grinding, owing to synergetic effects, including enhanced light absorption and scattering, as well as improved interfacial charge transfer because of the excellent contact between the GO sheets and TiO2 microspheres. In addition, GO-TiO2-3 (3 wt.% GO) showed the highest hydrogen-generation rate (305.6 μmol h(-)), which was about 13 and 3.3-times higher than those of TiO2 microsphere and GO-P25 (with 3 wt.% GO), respectively. Finally, a tentative mechanism for hydrogen production is proposed and supported by photoluminescence and transient photocurrent measurements. This work highlights the potential applications of GO-TiO2 composite microspheres in the field of clean-energy production.

  8. Ultrafast hydrothermal synthesis of high quality magnetic core phenol-formaldehyde shell composite microspheres using the microwave method.

    PubMed

    You, Li-Jun; Xu, Shuai; Ma, Wan-Fu; Li, Dian; Zhang, Yu-Ting; Guo, Jia; Hu, Jack J; Wang, Chang-Chun

    2012-07-17

    An ultrafast, facile, and efficient microwave hydrothermal approach was designed to fabricate magnetic Fe(3)O(4)/phenol-formaldehyde (PF) core-shell microspheres for the first time. The structure of the Fe(3)O(4)/PF core-shell microspheres could be well controlled by the in situ polycondensation of phenol and formaldehyde with magnetic Fe(3)O(4) clusters as the seeds in an aqueous solution without any surfactants. The effect of synthetic parameters, such as the feeding amounts of phenol, the dosages of formaldehyde, the reaction temperatures, and the microwave heating time, on the morphologies and sizes of the Fe(3)O(4)/PF microspheres were investigated in details. The phenol-formaldehyde shell is found to be evenly coated on Fe(3)O(4) clusters within 10 min of the irradiation. The as-prepared microspheres were highly uniform in morphology, and the method was found to allow the shell thickness to be finely controlled in the range of 10-200 nm. The properties of the composite microspheres were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetic analysis (TGA), Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The as-prepared Fe(3)O(4)/PF microspheres were monodisperse and highly dispersible in water, ethanol, N,N-dimethyformamide, and acetone, a beneficial quality for the further functionalization and applications of the Fe(3)O(4)/PF microspheres.

  9. Compositional dependence of hematopoietic stem cells expansion on bioceramic composite scaffolds for bone tissue engineering.

    PubMed

    Mishra, Sarika; Rajyalakshmi, A; Balasubramanian, K

    2012-09-01

    Bioceramics are although well known for their osteoinductive and osseointegrative properties in bone tissue regeneration, yet, they are inappropriate for load bearing applications due to inadequate mechanical strength. In this article, the authors report the expansion of hematopoietic stem cells (HSCs) on as-synthesized composite scaffolds from hydroxyapatite and β-tricalcium phosphate for bone tissue engineering, in an adequate load-bearing application. The physical, structural, and mechanical properties of the composite scaffolds have been examined and correlated with the in vitro adhesion pattern of HSCs. The results indicated that the response of HSCs varies with change in the stoichiometry of composite scaffolds. The H2T2 scaffolds have exhibited the highest expansion of CD34+ cells and long-term culture initiating cells when compared with other stoichiometries. The results suggest that H2T2 composite can be a potential strategic bone-graft substitute in contrast with monolithic bioceramics, serving a dual role of bioresorbability and enhanced load-bearing capacity.

  10. A biomimetic three-dimensional woven composite scaffold for functional tissue engineering of cartilage

    NASA Astrophysics Data System (ADS)

    Moutos, Franklin T.; Freed, Lisa E.; Guilak, Farshid

    2007-02-01

    Tissue engineering seeks to repair or regenerate tissues through combinations of implanted cells, biomaterial scaffolds and biologically active molecules. The rapid restoration of tissue biomechanical function remains an important challenge, emphasizing the need to replicate structural and mechanical properties using novel scaffold designs. Here we present a microscale 3D weaving technique to generate anisotropic 3D woven structures as the basis for novel composite scaffolds that are consolidated with a chondrocyte-hydrogel mixture into cartilage tissue constructs. Composite scaffolds show mechanical properties of the same order of magnitude as values for native articular cartilage, as measured by compressive, tensile and shear testing. Moreover, our findings showed that porous composite scaffolds could be engineered with initial properties that reproduce the anisotropy, viscoelasticity and tension-compression nonlinearity of native articular cartilage. Such scaffolds uniquely combine the potential for load-bearing immediately after implantation in vivo with biological support for cell-based tissue regeneration without requiring cultivation in vitro.

  11. Short- and long-term peripheral nerve regeneration using a poly-lactic-co-glycolic-acid scaffold containing nerve growth factor and glial cell line-derived neurotrophic factor releasing microspheres.

    PubMed

    de Boer, Ralph; Borntraeger, Andreas; Knight, Andrew M; Hébert-Blouin, Marie-Noëlle; Spinner, Robert J; Malessy, Martijn J A; Yaszemski, Michael J; Windebank, Anthony J

    2012-08-01

    Addition of neural growth factors to bioengineered scaffolds may improve peripheral nerve regeneration. The aim of this study is to evaluate the short- and long term effect of microsphere delivered nerve growth factor (NGF) and glial cell derived neurotrophic factor (GDNF) in the 10 mm rat sciatic nerve gap. Eighty-four rats were assigned to seven groups (n = 6) at two endpoints (6 and 16 weeks): saline, saline NGF, saline NGF-microspheres, saline GDNF, saline GDNF-microspheres, saline blank microspheres, and autologous nerve graft. Total fascicular area and total number of myelinated fibers at mid-tube increased in all conduit groups between 6 and 16 weeks. Autologous, saline NGF-microsphere and saline GDNF-microsphere groups reached maximal histomorphometric values by 6 weeks (p < 0.05). Compound muscle action potentials returned after 6 weeks for the autologous graft and continued to increase to a level of 3.6 ± 1.9 mV at endpoint. No significant differences were found between study groups as measured by ankle angle. These experiments show an initial beneficial effect of incorporation of NGF- or GDNF-microspheres in a PLGA 85/15 nerve conduit, since histomorphometric values reached their maximum by 6 weeks compared to control groups. These results do not yet extrapolate into improved electrophysiological or functional improvement.

  12. Clinoptilolite/PCL-PEG-PCL composite scaffolds for bone tissue engineering applications.

    PubMed

    Pazarçeviren, Engin; Erdemli, Özge; Keskin, Dilek; Tezcaner, Ayşen

    2017-03-01

    The aim of this study was to prepare and characterize highly porous clinoptilolite/poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) composite scaffolds. Scaffolds with different clinoptilolite contents (10% and 20%) were fabricated with reproducible solvent-free powder compression/particulate leaching technique. The scaffolds had interconnective porosity in the range of 55-76%. Clinoptilolite/poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) scaffolds showed negligible degradation within eight weeks and displayed less water uptake and higher bioactivity than poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) scaffolds. The presence of clinoptilolite improved the mechanical properties. Highest compressive strength (5.6 MPa) and modulus (114.84 MPa) were reached with scaffold group containing 20% clinoptilolite. In vitro protein adsorption capacity of the scaffolds was also higher for clinoptilolite/poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) scaffolds. These scaffolds had 0.95 mg protein/g scaffold adsorption capacity and also higher osteoinductivity in terms of enhanced ALP, OSP activities and intracellular calcium deposition. Stoichiometric apatite deposition (Ca/P=1.686) was observed during cellular proliferation analysis with human fetal osteoblasts cells. Thus, it can be suggested that clinoptilolite/poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) composite scaffolds could be promising carriers for enhancement of bone regeneration in bone tissue engineering applications.

  13. Fabrication of biodegradable polyurethane microspheres by a facile and green process.

    PubMed

    Lin, Cheng-Yen; Hsu, Shan-hui

    2015-05-01

    Two different compositions of water-based biodegradable polyurethane (PU) in the form of homogeneous nanoparticles (NPs) were synthesized using biodegradable polyesters as the soft segment. The first PU (PU01) was based on poly(ε-caprolactone) (PCL) diol and the second PU (PU02) was based on 40% PCL diol and 60% polyethylene butylene adipate diol. The PU NP dispersions with different solid contents were sprayed into liquid nitrogen and resuspended in water to generate elastic microspheres (50-60 µm) with different nanoporosities. In vitro degradation analysis revealed that microspheres of PU02 (i.e., PU02 MS) degraded faster than those of PU01 (PU01 MS). Methylene blue was encapsulated during microsphere formation and the release was investigated. Microspheres made from a lower content (10%) of PU02 dispersion (i.e., PU02 MS_10) showed a greater burst release of methylene blue in 6 h, whereas those made from a higher content (30%) of PU01 dispersion (i.e., PU01 MS_30) revealed a prolonged release with a significantly lower burst release. Biocompatibility evaluation using L929 fibroblasts demonstrated that cells were attached and proliferated on microspheres after 24 h. On the other hand, microspheres may further self-assemble into films and scaffolds. Surface modification of microspheres by chitosan may modify the self-assembly behavior of microspheres. Microspheres could be stacked to form scaffolds with different macroporosities. Fibroblasts were successfully seeded and grown in the microsphere-stacked scaffolds. We concluded that the biodegradable and elastic microspheres may be facilely produced from a green and sustainable process with potential applications in drug release and three-dimensional cell culture.

  14. Formation of superhydrophobic microspheres of poly(vinylidene fluoride- hexafluoropropylene)/graphene composite via gelation.

    PubMed

    Zhang, Li; Zha, Dao-an; Du, Tingting; Mei, Shilin; Shi, Zujin; Jin, Zhaoxia

    2011-07-19

    We report on the spontaneous formation of superhydrophobic poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)/graphene composite microspheres with uniform size via gelation. When the suspension of PVDF-HFP/graphene (0.25 wt. % with respect to PVDF-HFP) in DMF adsorbs water vapor, it changes to a hybrid gel. A dried porous gel is obtained after solvent exchange and freeze drying. Morphology characterization shows that this hybrid gel is composed of PVDF-HFP/graphene microspheres with a diameter of 8-10 μm. In contrast, PVDF-HFP solution gives rise to a cellular microstructure following the same experimental procedures. We further elucidate the formation mechanism on the basis of the characterization by freeze fracture transmission electron microscopy, X-ray diffraction, and differential scanning calorimetry characterizations. Furthermore, contact angle measurements of water on PVDF-HFP/graphene indicates that the hydrophobic nature of PVDF-HFP combined with the micro/nanoscale hierarchical texture creates a superhydrophobic surface. Such superhydrophobic microspheres may have potential applications as water-repellent catalyst-supporting materials.

  15. 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.

  16. Pillaring effects in macroporous carrageenan-silica composite microspheres.

    PubMed

    Boissière, M; Tourrette, A; Devoisselle, J M; Di Renzo, F; Quignard, F

    2006-02-01

    The impregnation of a carrageenan gel by a silica sol is an efficient method to form a composite material which can be conveniently activated by CO2 supercritical drying. The textural properties of the solids have been characterized by nitrogen adsorption-desorption at 77 K and their composition by thermogravimetric analysis and EDX microprobe. Morphology was examined by SEM. The silica-carrageenan composites present an open macroporous structure. Silica particles retained inside the gel behaved as pillars between the polysaccharide fibrils and form a stick-and-ball network. The stiffening of the carrageenan gel by silica prevented its shrinkage upon drying. The nature of the alkali cations affected the retention of silica particles inside the gel. In the absence of silica, carrageenan fibrils rearrange under supercritical drying and form an aerogel with cavities in the mesopore range.

  17. A facile in-situ hydrothermal synthesis of SrTiO3/TiO2 microsphere composite

    NASA Astrophysics Data System (ADS)

    Wang, Hongxing; Zhao, Wei; Zhang, Yubo; Zhang, Shimeng; Wang, Zihao; Zhao, Dan

    2016-06-01

    TiO2 was successfully used as sacrificed template to synthesise SrTiO3/TiO2 microsphere composite via an in-situ hydrothermal process. The diameter of SrTiO3/TiO2 microsphere was about 700 nm with the same size of the template, and all of the microspheres were in good dispersity. The optimized reaction parameters for the phase and morphology of the as-synthesized samples were investigated. The results showed the SrTiO3/TiO2 microsphere can be synthesized at 170 °C when the concentration of sodium hydroxide was 0.1 M. Lower hydrothermal temperature hampered the formation of the SrTiO3/TiO2 composite, the higher alkali concentration, however, will destroy the morphology of products. The formation mechanism of SrTiO3/TiO2 microsphere composite was proposed and the photocatalytic properties of the samples were characterized using methylene blue solution as the pollutant under the UV light irradiation. The results indicated the proper OH- concentration will provide a channel for Sr2+ to react with Ti4+ located in the template and form the SrTiO3/TiO2 composite, and those with micro-scaled spherical morphology exhibited good photocatalytic activities.

  18. Synthesis and Electrochemical Properties of Molybdenum Disulfide/Carbon Microsphere Composite

    NASA Astrophysics Data System (ADS)

    Jiang, Qiang; Chen, Xiao; Li, Lin; Feng, Chuanqi; Guo, Zaiping

    2017-02-01

    The molybdenum disulfide/carbon (MoS2/C) microsphere composite is synthesized by a facial hydrothermal method using carbon spheres as a template. The structure and morphology of the expected compounds are characterized by x-ray diffraction, x-ray photoelectron spectroscopy and scanning electron microscopy techniques. The electrochemical properties of the composite are investigated by a battery testing system. The as-prepared MoS2/C composite has an initial discharge capacity of 943 mAh g-1 and retained a reversible capacity at 705 mAh g-1 after 165 cycles with nearly 100% coulombic efficiency, exhibiting better electrochemical performances than those of pure MoS2. The MoS2/C composite is a promising anode material for lithium-ion battery applications.

  19. Facile preparation of well-dispersed CeO2-ZnO composite hollow microspheres with enhanced catalytic activity for CO oxidation.

    PubMed

    Xie, Qingshui; Zhao, Yue; Guo, Huizhang; Lu, Aolin; Zhang, Xiangxin; Wang, Laisen; Chen, Ming-Shu; Peng, Dong-Liang

    2014-01-08

    In this article, well-dispersed CeO2-ZnO composite hollow microspheres have been fabricated through a simple chemical reaction followed by annealing treatment. Amorphous zinc-cerium citrate hollow microspheres were first synthesized by dispersing zinc citrate hollow microspheres into cerium nitrate solution and then aging at room temperature for 1 h. By calcining the as-produced zinc-cerium citrate hollow microspheres at 500 °C for 2 h, CeO2-ZnO composite hollow microspheres with homogeneous composition distribution could be harvested for the first time. The resulting CeO2-ZnO composite hollow microspheres exhibit enhanced activity for CO oxidation compared with CeO2 and ZnO, which is due to well-dispersed small CeO2 particles on the surface of ZnO hollow microspheres and strong interaction between CeO2 and ZnO. Moreover, when Au nanoparticles are deposited on the surface of the CeO2-ZnO composite hollow microspheres, the full CO conversion temperature of the as-produced 1.0 wt % Au-CeO2-ZnO composites reduces from 300 to 60 °C in comparison with CeO2-ZnO composites. The significantly improved catalytic activity may be ascribed to the strong synergistic interplay between Au nanoparticles and CeO2-ZnO composites.

  20. Development of composite scaffolds for load-bearing segmental bone defects.

    PubMed

    Pilia, Marcello; Guda, Teja; Appleford, Mark

    2013-01-01

    The need for a suitable tissue-engineered scaffold that can be used to heal load-bearing segmental bone defects (SBDs) is both immediate and increasing. During the past 30 years, various ceramic and polymer scaffolds have been investigated for this application. More recently, while composite scaffolds built using a combination of ceramics and polymeric materials are being investigated in a greater number, very few products have progressed from laboratory benchtop studies to preclinical testing in animals. This review is based on an exhaustive literature search of various composite scaffolds designed to serve as bone regenerative therapies. We analyzed the benefits and drawbacks of different composite scaffold manufacturing techniques, the properties of commonly used ceramics and polymers, and the properties of currently investigated synthetic composite grafts. To follow, a comprehensive review of in vivo models used to test composite scaffolds in SBDs is detailed to serve as a guide to design appropriate translational studies and to identify the challenges that need to be overcome in scaffold design for successful translation. This includes selecting the animal type, determining the anatomical location within the animals, choosing the correct study duration, and finally, an overview of scaffold performance assessment.

  1. Effect of polymer microsphere incorporation on impact performance of STF cotton fabric composite

    NASA Astrophysics Data System (ADS)

    Suhaimi, M. S.; Mohamed, R.; Faiza, M. A.

    2010-05-01

    Liquid body armor system is recently being used compared to conventional body armor due to its lightweight, highly flexibility and reduced layered fabric. Shear thickening fluid (STF) system comprising of Polymer Microsphere (PMS) and solvent media are exploited in this study. Polymer Microsphere (eg: PMS) in solvent media varies with viscosity upon different PMS composition with and without surfactant. Fabrication of STF fabric system using Cotton laminate were performed using hand lay up with fixed areal density of 40% PMS content. Impact performance was evaluated using knife pendulum impact tester. Impact strength was found to increase with incorporation of STF system. STF addition significantly improves stab resistance of fabric. There were improvements of impact energy absorption for cotton fabric at different volume of STF used with 3 layers. For the three layer systems, impact performance showed improvement of 27.62% using 4ml of STF compared to use of 8ml of STF (12.44% impact improvement). For Cotton STF fabric composite, the effectiveness of the penetration was raised upon higher fabric layers. Overall, the STF-Cotton fabric composite are totally failure during testing, because of the cotton fabric is a fabric, which has very low strength. The addition of STF onto the cotton fabric system will not make the fabric becomes highly impact resistance.

  2. Novel polystyrene microspheres functionalized by imidazolium and the electrocatalytic activity towards H2O2 of its Prussian blue composite

    NASA Astrophysics Data System (ADS)

    Mao, Hui; Song, Jinling; Zhang, Qian; Liu, Daliang; Gong, Naiqi; Li, Ying; Wu, Qiong; Verpoort, Francis; Song, Xi-Ming

    2013-05-01

    Copolymerization of styrene (St) and 1-vinyl-3-ethylimidazolium bromide (VEIB), novel poly(St-co-VEIB) microspheres were generated. Owing to the presence of imidazolium groups, such microspheres having an average diameter of 125 nm, behave electropositively when dispersed in aqueous solution. Furthermore, due to the presence of imidazolium groups, having a capacity of ion-exchange and weak reducibility on the surface of the PS microspheres, [Fe(CN)6]3- was absorbed on the surface of poly(St-co-VEIB) microspheres, and simultaneously, Fe3+ was reduced to Fe2+. Thus, in situ growth of Prussian blue (PB) nanoparticles could occur on the surface of poly(St-co-VEIB) microspheres without the addition of any other reducing agent. This methodology, utilizing the ion-exchange and weak reducibility properties of the imidazolium groups on the surface of micro-/nanostructures is a novel general method for assembling hierarchical nanostructured materials. Finally, the electrochemical property of the strawberry-like PS/PB composite microspheres was also investigated by applying a glassy carbon electrode. A good repeatability of the cyclic voltammetry responses, having a good linearity and sensitivity, for the electrocatalytic reduction of H2O2 was obtained.

  3. Controlled Release of Chitosan and Sericin from the Microspheres-Embedded Wound Dressing for the Prolonged Anti-microbial and Wound Healing Efficacy.

    PubMed

    Aramwit, Pornanong; Yamdech, Rungnapha; Ampawong, Sumate

    2016-05-01

    One approach in wound dressing development is to incorporate active molecules or drugs in the dressing. In order to reduce the frequency of dressing changes as well as to prolong wound healing efficacy, wound dressings that can sustain the release of the active molecules should be developed. In our previous work, we developed chitosan/sericin (CH/SS) microspheres that released sericin in a controlled rate. However, the difficulty of applying the microspheres that easily diffuse and quickly degrade onto the wound was its limitations. In this study, we aimed to develop wound dressing materials which are easier to apply and to provide extended release of sericin. Different amounts of CH/SS microspheres were embedded into various compositions of polyvinyl alcohol/gelatin (PVA/G) scaffolds and fabricated using freeze-drying and glutaraldehyde crosslinking techniques. The obtained CH/SS microspheres-embedded scaffolds with appropriate design and formulation were introduced as a wound dressing material. Sericin was released from the microspheres and the scaffolds in a sustained manner. Furthermore, an optimized formation of the microspheres-embedded scaffolds (2PVA2G+2CHSS) was shown to possess an effective antimicrobial activity against both gram-positive and gram-negative bacteria. These microspheres-embedded scaffolds were not toxic to L929 mouse fibroblast cells, and they did not irritate the tissue when applied to the wound. Finally, probably by the sustained release of sericin, these microspheres-embedded scaffolds could promote wound healing as well as or slightly better than a clinically used wound dressing (Allevyn®) in a mouse model. The antimicrobial CH/SS microspheres-embedded PVA/G scaffolds with sustained release of sericin would appear to be a promising candidate for wound dressing application.

  4. Porous silicon oxide-PLGA composite microspheres for sustained ocular delivery of daunorubicin

    PubMed Central

    Nan, Kaihui; Ma, Feiyan; Hou, Huiyuan; Freeman, William R.; Sailor, Michael J.; Cheng, Lingyun

    2014-01-01

    A water-soluble anthracycline antibiotic drug (daunorubicin, DNR) was loaded into oxidized porous silicon (pSiO2) microparticles and then encapsulated with a layer of polymer (poly lactide-co-glycolide, PLGA) to investigate their synergistic effects in control of DNR release. Similarly fabricated PLGA-DNR microspheres without pSiO2, and pSiO2 microparticles without PLGA were used as control particles. The composite microparticles synthesized by a solid-in-oil-in-water (S/O/W) emulsion method have mean diameters of 52.33±16.37 μm for PLGA-pSiO2_21/40-DNR and the mean diameter of 49.31±8.87 μm for PLGA-pSiO2_6/20-DNR. The mean size, 26.00±8 μm, of PLGA-DNR was significantly smaller, compared with the other two (p<0.0001). Optical microscopy revealed that PLGA-pSiO2-DNR microsphere contained multiple pSiO2 particles. In vitro release experiments determined that control PLGA-DNR microspheres completely released DNR within 38 days and control pSiO2-DNR microparticles (with no PLGA coating) released DNR within 14 days, while the PLGA-pSiO2-DNR microspheres released DNR for 74 days. Temporal release profiles of DNR from PLGA-pSiO2 composite particles indicated that both PLGA and pSiO2 contribute to the sustained release of the payload. The PLGA-pSiO2 composite displayed a more constant rate of DNR release than the pSiO2 control formulation, and it displayed a significantly slower release of DNR than either the PLGA or pSiO2 formulations. We conclude that this system may be useful in managing unwanted ocular proliferation when formulated with anti-proliferation compounds such as DNR. PMID:24793657

  5. Bioactive nanoparticle-gelatin composite scaffold with mechanical performance comparable to cancellous bones.

    PubMed

    Wang, Chen; Shen, Hong; Tian, Ye; Xie, Yue; Li, Ailing; Ji, Lijun; Niu, Zhongwei; Wu, Decheng; Qiu, Dong

    2014-08-13

    Mechanical properties are among the most concerned issues for artificial bone grafting materials. The scaffolds used for bone grafts are either too brittle (glass) or too weak (polymer), and therefore composite scaffolds are naturally expected as the solution. However, despite the intensive studies on composite bone grafting materials, there still lacks a material that could be matched to the natural cancellous bones. In this study, nanosized bioactive particles (BP) with controllable size and good colloidal stability were used to composite with gelatin, forming macroporous scaffolds. It was found that the mechanical properties of obtained composite scaffolds, in terms of elastic modulus, compressive strength, and strain at failure, could match to that of natural cancellous bones. This is ascribed to the good distribution of particle in matrix and strong interaction between particle and gelatin. Furthermore, the incorporation of BPs endues the composite scaffolds with bioactivity, forming HA upon reacting with simulated body fluid (SBF) within days, thus stimulating preosteoblasts attachment, growth, and proliferation in these scaffolds. Together with their good mechanical properties, these composite scaffolds are promising artificial bone grating materials.

  6. Novel synthesis strategies for natural polymer and composite biomaterials as potential scaffolds for tissue engineering.

    PubMed

    Ko, Hsu-Feng; Sfeir, Charles; Kumta, Prashant N

    2010-04-28

    Recent developments in tissue engineering approaches frequently revolve around the use of three-dimensional scaffolds to function as the template for cellular activities to repair, rebuild and regenerate damaged or lost tissues. While there are several biomaterials to select as three-dimensional scaffolds, it is generally agreed that a biomaterial to be used in tissue engineering needs to possess certain material characteristics such as biocompatibility, suitable surface chemistry, interconnected porosity, desired mechanical properties and biodegradability. The use of naturally derived polymers as three-dimensional scaffolds has been gaining widespread attention owing to their favourable attributes of biocompatibility, low cost and ease of processing. This paper discusses the synthesis of various polysaccharide-based, naturally derived polymers, and the potential of using these biomaterials to serve as tissue engineering three-dimensional scaffolds is also evaluated. In this study, naturally derived polymers, specifically cellulose, chitosan, alginate and agarose, and their composites, are examined. Single-component scaffolds of plain cellulose, plain chitosan and plain alginate as well as composite scaffolds of cellulose-alginate, cellulose-agarose, cellulose-chitosan, chitosan-alginate and chitosan-agarose are synthesized, and their suitability as tissue engineering scaffolds is assessed. It is shown that naturally derived polymers in the form of hydrogels can be synthesized, and the lyophilization technique is used to synthesize various composites comprising these natural polymers. The composite scaffolds appear to be sponge-like after lyophilization. Scanning electron microscopy is used to demonstrate the formation of an interconnected porous network within the polymeric scaffold following lyophilization. It is also established that HeLa cells attach and proliferate well on scaffolds of cellulose, chitosan or alginate. The synthesis protocols reported in this

  7. Sol-gel assisted fabrication of collagen hydrolysate composite scaffold: a novel therapeutic alternative to the traditional collagen scaffold.

    PubMed

    Ramadass, Satiesh Kumar; Perumal, Sathiamurthi; Gopinath, Arun; Nisal, Anuya; Subramanian, Saravanan; Madhan, Balaraman

    2014-09-10

    Collagen is one of the most widely used biomaterial for various biomedical applications. In this Research Article, we present a novel approach of using collagen hydrolysate, smaller fragments of collagen, as an alternative to traditionally used collagen scaffold. Collagen hydrolysate composite scaffold (CHCS) was fabricated with sol-gel transition procedure using tetraethoxysilane as the silica precursor. CHCS exhibits porous morphology with pore sizes varying between 380 and 780 μm. Incorporation of silica conferred CHCS with controlled biodegradation and better water uptake capacity. Notably, 3T3 fibroblast proliferation was seen to be significantly better under CHCS treatment when compared to treatment with collagen scaffold. Additionally, CHCS showed excellent antimicrobial activity against the wound pathogens Staphylococcus aureus, Bacillus subtilis, and Escherichia coli due to the inherited antimicrobial activity of collagen hydrolysate. In vivo wound healing experiments with full thickness excision wounds in rat model demonstrated that wounds treated with CHCS showed accelerated healing when compared to wounds treated with collagen scaffold. These findings indicate that the CHCS scaffold from collagen fragments would be an effective and affordable alternative to the traditionally used collagen structural biomaterials.

  8. Macroporous Fe3O4/carbon composite microspheres with a short Li+ diffusion pathway for the fast charge/discharge of lithium ion batteries.

    PubMed

    Choi, Seung Ho; Ko, You Na; Jung, Kyeong Youl; Kang, Yun Chan

    2014-08-25

    Macroporous Fe3O4/carbon composite and core-shell Fe3O4@carbon composite microspheres have been prepared by means of one-pot spray pyrolysis. The addition of polystyrene (PS) nanobeads to a spray solution containing an iron salt and poly(vinylpyrrolidone) (PVP) led to macroporous Fe3O4/carbon composite microspheres, the carbon and iron components of which are uniformly distributed over the entire composite microsphere. The pore-size distribution curve for the macroporous Fe3O4/carbon composite shows distinct peaks at around 10 and 80 nm. An electrode prepared from the macroporous Fe3O4/carbon composite microspheres showed better cycling and rate performances than an electrode formed from core-shell Fe3O4@carbon composite microspheres. The initial discharge and charge capacities of the macroporous Fe3O4/carbon composite microsphere electrode were determined to be 1258 and 908 mA h g(-1) at 2 A g(-1), respectively, and the corresponding initial coulombic efficiency was 72 %. The composite microsphere electrode cycled 500 times at 5 A g(-1) showed a high discharge capacity of 733 mA h g(-1).

  9. Electrospun aligned nanofibrous scaffold of carbon nanotubes-polyurethane composite for endothelial cells.

    PubMed

    Han, Zhaozhao; Kong, Hua; Meng, Jie; Wang, Chaoying; Xie, Sishen; Xu, Haiyan

    2009-02-01

    Nanofibrous scaffold of carbon nanotubes/polyurethane composite (MWNT/PU) with aligned topography was fabricated by electrospinning for endothelium cells growth. The diameter of the generated fiber was around 300 nm-500 nm. Experimental results indicated that the nanofibrous scaffold of MWNT/PU exhibited promotional influence on the cell proliferation. It was also observed that the scaffold possessed an advantage of supporting ECs migrating and aggregating along the axis of the aligned nanofibers, which is one of the important functions in the process of endothelium regeneration. It was also demonstrated that the endothelial cells growing on the scaffold expressed non-thrombogenic phenotype with low tissue factor released. These results indicated the favorable interactions between ECs and the nanofibrous scaffold of MWNT/PU, implying that the aligned nanofibrous scaffold has a promising potential for vascular engineering.

  10. In vivo release of plasmid DNA from composites of oligo(poly(ethylene glycol)fumarate) and cationized gelatin microspheres.

    PubMed

    Kasper, F Kurtis; Kushibiki, Toshihiro; Kimura, Yu; Mikos, Antonios G; Tabata, Yasuhiko

    2005-10-20

    Composites of cationized gelatin microspheres (CGMS), crosslinked with either 3 mM or 6 mM glutaraldehyde solution, and a novel hydrogel material, oligo(poly(ethylene glycol)fumarate) (OPF) were fabricated and investigated toward prolonging the release of plasmid DNA in vivo relative to the constituent materials. The composites and constituent materials were investigated in a subcutaneous murine model to assess the release of 125I-labeled plasmid DNA and 125I-labeled cationized gelatin in vivo. The time profiles of the radioactivity remaining were employed to compare the profiles of DNA release and cationized gelatin degradation. Both composite formulations (incorporating either 3 mM or 6 mM CGMS) prolonged the bioavailability of plasmid DNA relative to both injected plasmid DNA solution and the respective non-embedded cationized gelatin microspheres. Injected plasmid DNA solution persisted in the subject for only 7-10 days, whereas the persistence of DNA from composites of OPF and either 3 mM or 6 mM CGMS extended to at least day 42. The 3 mM and 6 mM CGMS each increased the persistence of DNA slightly, relative to injection of DNA solution, to between 28 and 35 days. Interestingly, the release profile of plasmid DNA from composites was not significantly different from the release of DNA from OPF alone. The release of plasmid DNA from the composites was in accord with the degradation of the microspheres within the OPF. These results show that composites of OPF and cationized gelatin microspheres are able to prolong the availability of plasmid DNA in vivo relative to cationized gelatin microspheres alone and provide a promising candidate material for the sustained, controlled release of plasmid DNA.

  11. Antibacterial properties of poly (octanediol citrate)/gallium-containing bioglass composite scaffolds.

    PubMed

    Zeimaran, Ehsan; Pourshahrestani, Sara; Djordjevic, Ivan; Pingguan-Murphy, Belinda; Kadri, Nahrizul Adib; Wren, Anthony W; Towler, Mark R

    2016-01-01

    Bioactive glasses may function as antimicrobial delivery systems through the incorporation and subsequent release of therapeutic ions. The aim of this study was to evaluate the antimicrobial properties of a series of composite scaffolds composed of poly(octanediol citrate) with increased loads of a bioactive glass that releases zinc (Zn(2+)) and gallium (Ga(3+)) ions in a controlled manner. The antibacterial activity of these scaffolds was investigated against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The ability of the scaffolds to release ions and the subsequent ingress of these ions into hard tissue was evaluated using a bovine bone model. Scaffolds containing bioactive glass exhibited antibacterial activity and this increased in vitro with higher bioactive glass loads; viable cells decreased to about 20 % for the composite scaffold containing 30 % bioactive glass. The Ga(3+) release rate increased as a function of time and Zn(2+) was shown to incorporate into the surrounding bone.

  12. Controlling Acute Inflammation with Fast Releasing Dexamethasone-PLGA Microsphere/PVA Hydrogel Composites for Implantable Devices

    PubMed Central

    Bhardwaj, Upkar; Sura, Radhakrishna; Papadimitrakopoulos, Fotios; Burgess, Diane J.

    2007-01-01

    Background Continuous release of dexamethasone from PLGA microsphere/PVA hydrogel composites has been shown to suppress the inflammatory tissue reaction in response to subcutaneously implanted foreign material for a period of one month. The scope of the present work is to investigate whether suppressing the initial acute inflammatory phase with fast releasing dexamethasone-PLGA microsphere/PVA composites (that release the drug over a period of one week) would prevent the development of a foreign body reaction in response to implantation in the subcutaneous tissue using a rat model. Methods Dexamethasone loaded PLGA microspheres were prepared using the solvent evaporation method. In vitro release from microspheres was analyzed using USP apparatus 4 in phosphate buffered saline (PBS) at 37°C. Composites were fabricated in 18G needles by freeze-thaw cycling the PVA/microsphere dispersion. The composites were implanted in the subcutaneous tissue of anesthetized rats. The pharmacodynamic effect was evaluated by histological examination of the tissue surrounding the composites at pre-determined time points. Results In vitro release studies showed that most of the drug entrapped in the microspheres was released within one week. At days 3 and 8, these fast releasing dexamethasone containing composites suppressed the acute phase of inflammation but did not prevent the development of an inflammatory reaction after dexamethasone was completely released from the composites. By day 30, chronic inflammation and fibrosis were observed in the tissue surrounding the drug-containing composites. On days 3 and 8, the number of inflammatory cells in the vicinity of the dexamethasone containing composites was similar to that in normal tissue. However, the number of inflammatory cells was higher in drug-containing composites as compared to drug-free composites by day 30. This was due to the inflammation being in a more advanced stage in drug-free composites where a granulomatous

  13. Chitin and carbon nanotube composites as biocompatible scaffolds for neuron growth

    NASA Astrophysics Data System (ADS)

    Singh, Nandita; Chen, Jinhu; Koziol, Krzysztof K.; Hallam, Keith R.; Janas, Dawid; Patil, Avinash J.; Strachan, Ally; G. Hanley, Jonathan; Rahatekar, Sameer S.

    2016-04-01

    The design of biocompatible implants for neuron repair/regeneration ideally requires high cell adhesion as well as good electrical conductivity. Here, we have shown that plasma-treated chitin carbon nanotube composite scaffolds show very good neuron adhesion as well as support of synaptic function of neurons. The addition of carbon nanotubes to a chitin biopolymer improved the electrical conductivity and the assisted oxygen plasma treatment introduced more oxygen species onto the chitin nanotube scaffold surface. Neuron viability experiments showed excellent neuron attachment onto plasma-treated chitin nanotube composite scaffolds. The support of synaptic function was evident on chitin/nanotube composites, as confirmed by PSD-95 staining. The biocompatible and electrically-conducting chitin nanotube composite scaffold prepared in this study can be used for in vitro tissue engineering of neurons and, potentially, as an implantable electrode for stimulation and repair of neurons.

  14. Chitin and carbon nanotube composites as biocompatible scaffolds for neuron growth.

    PubMed

    Singh, Nandita; Chen, Jinhu; Koziol, Krzysztof K; Hallam, Keith R; Janas, Dawid; Patil, Avinash J; Strachan, Ally; G Hanley, Jonathan; Rahatekar, Sameer S

    2016-04-21

    The design of biocompatible implants for neuron repair/regeneration ideally requires high cell adhesion as well as good electrical conductivity. Here, we have shown that plasma-treated chitin carbon nanotube composite scaffolds show very good neuron adhesion as well as support of synaptic function of neurons. The addition of carbon nanotubes to a chitin biopolymer improved the electrical conductivity and the assisted oxygen plasma treatment introduced more oxygen species onto the chitin nanotube scaffold surface. Neuron viability experiments showed excellent neuron attachment onto plasma-treated chitin nanotube composite scaffolds. The support of synaptic function was evident on chitin/nanotube composites, as confirmed by PSD-95 staining. The biocompatible and electrically-conducting chitin nanotube composite scaffold prepared in this study can be used for in vitro tissue engineering of neurons and, potentially, as an implantable electrode for stimulation and repair of neurons.

  15. Controlled delivery of platelet-derived growth factor-BB from injectable microsphere/hydrogel composites.

    PubMed

    Wu, Hua; Liu, Jiaoyan; Wu, Jingjing; Wan, Ying; Chen, Yun

    2016-12-01

    Platelet-derived growth factor-BB (PGDF-BB) loaded gelatin microspheres with an average size of about 2μm was incorporated into chitosan/silk fibroin/glycerophosphate (GP) solutions to prepare composites. The formulated composite solutions were able to form into hydrogels in a temperature range between 32 and 37°C at a pH of ca.7. They had good fluidity at 25°C and showed shear-thinning features at both 25 and 37°C, revealing that they are injectable at room temperature. Elastic modulus of some composites at 37°C was about 10-fold higher than that of chitosan/GP gel, confirming that these composites behave like mechanically strong gels. Optimal composites showed abilities to administrate PDGF-BB release in an approximately linear manner up to 5 weeks. The PDGF-BB release could be regulated by the PDGF-BB load and the silk fibroin content in the composites in an individual or cooperative way. In vivo degradation of composites demonstrated that some of them had markedly enhanced degradation endurance as compared to the chitosan/GP gel. PDGF-BB-stimulated DNA synthesis in Balb/c 3T3 fibroblasts and PDGF-BB-induced cell migration suggested that the bioactivity of released PDGF-BB was well retained.

  16. Electrospun PHBV/collagen composite nanofibrous scaffolds for tissue engineering.

    PubMed

    Meng, Wan; Kim, Se-Yong; Yuan, Jiang; Kim, Jung Chul; Kwon, Oh Hyeong; Kawazoe, Naoki; Chen, Guoping; Ito, Yoshihiro; Kang, Inn-Kyu

    2007-01-01

    Electrospinning has recently emerged as a leading technique for the formation of nanofibrous structures made of synthetic and natural extracellular matrix components. In this study, nanofibrous scaffolds were obtained by electrospinning a combination of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and type-I collagen in 1,1,1,3,3,3-hexafluoro-2-isopropanol (HIFP). The resulting fibers ranged from 300 to 600 nm in diameter. Their surfaces were characterized by attenuated total reflection Fourier transform infrared spectroscopy, electron spectroscopy for chemical analysis and atomic force microscopy. The PHBV and collagen components of the PHBV/collagen nanofibrous scaffold were biodegraded by PHB depolymerase and a type-I collagenase aqueous solution, respectively. The cell culture experiments indicated that the PHBV/collagen nanofibrous scaffold accelerated the adhesion and growth of NIH3T3 cells more effectively than the PHBV nanofibrous scaffold, thus making the former a good scaffold for tissue engineering.

  17. Fabrication and characterization of bioactive β-Ca2SiO4/PHBV composite scaffolds.

    PubMed

    Wang, Nana; Zhou, Zheng; Xia, Leilei; Dai, Yao; Liu, Hairong

    2013-05-01

    A key challenge in tissue engineering is the construction of a scaffold with adequate properties which would mimic extracellular matrix (ECM) to induce the cells' efficient adhesion, proliferation and proper differentiation. Novel β-Ca2SiO4/PHBV composite scaffolds were fabricated by integrating β-Ca2SiO4 nanoparticles with PHBV backbone via a modified solvent casting-particulates leaching method, which generates interconnected porous structure and the high porosity, about 87%, of these scaffolds. Compared with PHBV scaffolds, β-Ca2SiO4/PHBV composite scaffolds facilitate the adhesion of human osteoblast-like MG-63 cells due to their increased hydrophilicity. The β-Ca2SiO4/PHBV composite scaffolds containing 2.5 or 5% β-Ca2SiO4 nanoparticles significantly enhance the proliferation of MG-63 cells by stimulating the transcription of the transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-7 (BMP-7) genes. These scaffolds also induce early differentiation via promoting the transcription of alkaline phosphatase (ALP). The results suggest the potential application of β-Ca2SiO4/PHBV composites in bone tissue engineering.

  18. Design of a multiphase osteochondral scaffold. I. Control of chemical composition.

    PubMed

    Lynn, Andrew K; Best, Serena M; Cameron, Ruth E; Harley, Brendan A; Yannas, Ioannis V; Gibson, Lorna J; Bonfield, William

    2010-03-01

    This is the first in a series of articles that describe the design and development of a family of osteochondral scaffolds based on collagen-glycosaminoglycan (collagen-GAG) and calcium phosphate technologies, engineered for the regenerative repair of defects in articular cartilage. The osteochondral scaffolds consist of two layers: a mineralized type I collagen-GAG scaffold designed to regenerate the underlying subchondral bone and a nonmineralized type II collagen-GAG scaffold designed to regenerate cartilage. The subsequent articles in this series describe the fabrication and properties of a mineralized scaffold as well as a two-layer (one mineralized, the other not) osteochondral scaffold for regeneration of the underlying bone and cartilage, respectively. This article describes a technology through which the chemical composition-particularly the calcium phosphate mass fraction-of triple coprecipitated nanocomposites of collagen, glycosaminoglycan, and calcium phosphate can be accurately and reproducibly varied without the need for titrants or other additives. Here, we describe how the mineral:organic ratio can be altered over a range that includes that for articular cartilage (0 wt % mineral) and for bone (75 wt % mineral). This technology achieves the objective of mimicking the composition of two main tissue types found in articular joints, with particular emphasis on the osseous compartment of an osteochondral scaffold. Exclusion of titrants avoids the formation of potentially harmful contaminant phases during freeze-drying steps crucial for scaffold fabrication, ensuring that the potential for binding growth factors and drugs is maintained.

  19. Biological evaluation of porous aliphatic polyurethane/hydroxyapatite composite scaffolds for bone tissue engineering.

    PubMed

    Yang, Wanxun; Both, Sanne K; Zuo, Yi; Birgani, Zeinab Tahmasebi; Habibovic, Pamela; Li, Yubao; Jansen, John A; Yang, Fang

    2015-07-01

    Biomaterial scaffolds meant to function as supporting structures to osteogenic cells play a pivotal role in bone tissue engineering. Recently, we synthesized an aliphatic polyurethane (PU) scaffold via a foaming method using non-toxic components. Through this procedure a uniform interconnected porous structure was created. Furthermore, hydroxyapatite (HA) particles were introduced into this process to increase the bioactivity of the PU matrix. To evaluate the biological performances of these PU-based scaffolds, their influence on in vitro cellular behavior and in vivo bone forming capacity of the engineered cell-scaffold constructs was investigated in this study. A simulated body fluid test demonstrated that the incorporation of 40 wt % HA particles significantly promoted the biomineralization ability of the PU scaffolds. Enhanced in vitro proliferation and osteogenic differentiation of the seeded mesenchymal stem cells were also observed on the PU/HA composite. Next, the cell-scaffold constructs were implanted subcutaneously in a nude mice model. After 8 weeks, a considerable amount of vascularized bone tissue with initial marrow stroma development was generated in both PU and PU/HA40 scaffold. In conclusion, the PU/HA composite is a potential scaffold for bone regeneration applications.

  20. Clay nanotube-biopolymer composite scaffolds for tissue engineering

    NASA Astrophysics Data System (ADS)

    Naumenko, Ekaterina A.; Guryanov, Ivan D.; Yendluri, Raghuvara; Lvov, Yuri M.; Fakhrullin, Rawil F.

    2016-03-01

    Porous biopolymer hydrogels doped at 3-6 wt% with 50 nm diameter/0.8 μm long natural clay nanotubes were produced without any cross-linkers using the freeze-drying method. The enhancement of mechanical strength (doubled pick load), higher water uptake and thermal properties in chitosan-gelatine-agarose hydrogels doped with halloysite was demonstrated. SEM and AFM imaging has shown the even distribution of nanotubes within the scaffolds. We used enhanced dark-field microscopy to visualise the distribution of halloysite nanotubes in the implantation area. In vitro cell adhesion and proliferation on the nanocomposites occur without changes in viability and cytoskeleton formation. In vivo biocompatibility and biodegradability evaluation in rats has confirmed that the scaffolds promote the formation of novel blood vessels around the implantation sites. The scaffolds show excellent resorption within six weeks after implantation in rats. Neo-vascularization observed in newly formed connective tissue placed near the scaffold allows for the complete restoration of blood flow. These phenomena indicate that the halloysite-doped scaffolds are biocompatible as demonstrated both in vitro and in vivo. The chitosan-gelatine-agarose doped clay nanotube nanocomposite scaffolds fabricated in this work are promising candidates for tissue engineering applications.Porous biopolymer hydrogels doped at 3-6 wt% with 50 nm diameter/0.8 μm long natural clay nanotubes were produced without any cross-linkers using the freeze-drying method. The enhancement of mechanical strength (doubled pick load), higher water uptake and thermal properties in chitosan-gelatine-agarose hydrogels doped with halloysite was demonstrated. SEM and AFM imaging has shown the even distribution of nanotubes within the scaffolds. We used enhanced dark-field microscopy to visualise the distribution of halloysite nanotubes in the implantation area. In vitro cell adhesion and proliferation on the nanocomposites occur

  1. Nano-composite scaffolds for bone tissue engineering containing silver nanoparticles: preparation, characterization and biological properties.

    PubMed

    Marsich, Eleonora; Bellomo, Francesca; Turco, Gianluca; Travan, Andrea; Donati, Ivan; Paoletti, Sergio

    2013-07-01

    In this study nano-composite scaffolds to be used as bone grafts have been endowed with antibacterial properties owing to the presence of silver nanoparticles. The alginate/hydroxyapatite composite scaffolds were prepared by internal gelation followed by a freeze-drying procedure to obtain a porous structure. The nanoparticles were prepared in presence of a lactose modified-chitosan and this colloidal solution was adsorbed on the scaffolds by exploiting electrostatic interactions. The adsorption and release of the silver from the composite scaffold was measured by ICP-AES and spectrofluorimetry measurements. Micro-computed tomography analysis of the scaffolds showed a homogeneous porous structure with average pore sizes of 341.5 μm and porosity of 80 %. In vitro biological tests (MTS and killing kinetics assays) demonstrated that silver does not affect the ability of the scaffolds to promote osteoblasts proliferation and that at the same time it exerts a strong bactericidal effect against both Gram+ and Gram- bacterial strains. Overall, the combined results indicate that these biocompatible antimicrobial scaffolds possess ideal characteristics for tissue engineering applications.

  2. Synthesis of electromagnetic functionalized Fe3O4 microspheres/polyaniline composites by two-step oxidative polymerization.

    PubMed

    Cui, Chenkui; Du, Yunchen; Li, Tianhao; Zheng, Xiaoying; Wang, Xiaohong; Han, Xijiang; Xu, Ping

    2012-08-09

    Composites consisting of Fe(3)O(4) microspheres (FMS) and polyaniline (PANI), FMS/PANI, have been successfully prepared through a two-step oxidative polymerization of aniline monomers in the presence of Fe(3)O(4) microspheres. In our two-step polymerization technique, Fe(3+) and ammonium persulfate (APS) are used as the oxidants in each step. It is discovered that the two-step oxidative process plays a dominant role in the morphology of these composites: aniline oligomers oxidized by Fe(3+) are mainly produced in the first stage, and "egg-like" PANI aggregates are obtained in the second stage. It can be found that embedding Fe(3)O(4) microspheres in the polymer matrixes will not only modulate the complex permittivity but also produce magnetic resonance and loss in the composites. Therefore, the characteristic impedance and reflection loss of these composites are greatly improved. Especially, the composite with equal amount of FMS and PANI, FMS/PANI(50), displays very strong reflection loss over a wide frequency range that can be manipulated by the absorber thickness. More importantly, the composites prepared from the two-step chemical oxidative polymerization using hierarchical magnetic materials have better microwave absorption and environmental stability as compared with those composites from Fe(3)O(4) nanoparticles, one-step oxidative polymerization, and physical mixture. We believe the two-step oxidative polymerization technique can be a novel route for the design and preparation of lightweight and highly effective microwave absorbers in the future.

  3. Fabrication of poly(N-ethylaniline)/lignosulfonate composites and their carbon microspheres.

    PubMed

    He, Zhi-Wei; Lü, Qiu-Feng; Lin, Qilang

    2012-12-01

    Novel poly(N-ethylaniline)/lignosulfonate (PNA-LS) composites were prepared via an in situ polymerization of N-ethylaniline (NA) with lignosulfonate (LS) as a dispersant. Nitrogen-containing carbon materials were obtained by direct pyrolysis of the PNA-LS composites at the pyrolytic temperatures ranging from 300°C to 1200°C. The as-prepared PNA-LS composites and their carbon materials were investigated by TGA, SEM, TEM, FTIR and UV-vis spectra, XRD and elemental analysis. The results showed that the morphology, structure and properties of the PNA-LS composites were depended on the LS:NA mass ratio. PNA-LS microspheres with an average diameter of 1300 nm could be fabricated when the LS:NA mass ratio was 2.5:97.5, while regular hexagon sheets of PNA-LS composite were obtained with the LS:NA mass ratio above 5:95. Furthermore, nitrogen-containing carbon nanospheres with an average diameter of 820 nm were achieved at the carbonization temperature of 800°C.

  4. Preparation of SnO2-coated Ni microsphere composites with controlled microwave absorption properties

    NASA Astrophysics Data System (ADS)

    Zhao, Biao; Shao, Gang; Fan, Bingbing; Guo, Wenhui; Chen, Yongqiang; Zhang, Rui

    2015-03-01

    In this work, the core-shell structured Ni/SnO2 composites have been successfully synthesized by a hydrothermal deposition method (HDM). The crystal structure, morphology and electromagnetic (EM) properties of Ni/SnO2 composites were investigated. The effects of SnO32- and urea contents on the morphologies of final Ni/SnO2 samples were also considered. The microwave absorption properties of Ni microspheres are remarkably enhanced after coating whit SnO2 nanaoshells. Moreover, the microwave absorption properties of core-shell structured Ni/SnO2 composites can be tailored by tuning SnO2 contents. The results show that the Ni/SnO2 composites prepared at 0.017 M SnO32- exhibit outstanding microwave absorption properties with a minimum reflection loss of -42.8 dB at 9.8 GHz with the corresponding thickness of 3.0 mm. The reflection loss below -10 dB can be obtained in a wide range of 5.8-18.0 GHz by adjusting the absorber thicknesses from 1.5 mm to 4.5 mm. The excellent microwave absorption properties are attributed to high magnetic loss, dielectric loss, multi-resonance and interfacial polarization of the core-shelled Ni/SnO2 composites.

  5. In vitro degradation of porous PLLA/pearl powder composite scaffolds.

    PubMed

    Liu, Y S; Huang, Q L; Kienzle, A; Müller, W E G; Feng, Q L

    2014-05-01

    The in vitro degradation behavior of poly-L-lactide (PLLA), PLLA/aragonite pearl powder and PLLA/vaterite pearl powder scaffolds was investigated. The scaffolds were soaked in phosphate buffer solution (PBS) up to 200 days. Scanning electron microscopy (SEM), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC) were used to observe any degradation of the scaffolds. Degradation behaviors such as changes in pH, porosity, bulk density, water absorption, weight loss and mechanical properties were discussed. The results show that a gradual increase of the pH in composite scaffolds can decrease the rate of hydrolysis of PLLA. PLLA/vaterite and PLLA/aragonite scaffolds have a similar degradation behavior but a slower rate of degradation than PLLA.

  6. Phase transitions of macromolecular microsphere composite hydrogels based on the stochastic Cahn–Hilliard equation

    SciTech Connect

    Li, Xiao Ji, Guanghua Zhang, Hui

    2015-02-15

    We use the stochastic Cahn–Hilliard equation to simulate the phase transitions of the macromolecular microsphere composite (MMC) hydrogels under a random disturbance. Based on the Flory–Huggins lattice model and the Boltzmann entropy theorem, we develop a reticular free energy suit for the network structure of MMC hydrogels. Taking the random factor into account, with the time-dependent Ginzburg-Landau (TDGL) mesoscopic simulation method, we set up a stochastic Cahn–Hilliard equation, designated herein as the MMC-TDGL equation. The stochastic term in the equation is constructed appropriately to satisfy the fluctuation-dissipation theorem and is discretized on a spatial grid for the simulation. A semi-implicit difference scheme is adopted to numerically solve the MMC-TDGL equation. Some numerical experiments are performed with different parameters. The results are consistent with the physical phenomenon, which verifies the good simulation of the stochastic term.

  7. Living nano-micro fibrous woven fabric/hydrogel composite scaffolds for heart valve engineering.

    PubMed

    Wu, Shaohua; Duan, Bin; Qin, Xiaohong; Butcher, Jonathan T

    2017-03-15

    Regeneration and repair of injured or diseased heart valves remains a clinical challenge. Tissue engineering provides a promising treatment approach to facilitate living heart valve repair and regeneration. Three-dimensional (3D) biomimetic scaffolds that possess heterogeneous and anisotropic features that approximate those of native heart valve tissue are beneficial to the successful in vitro development of tissue engineered heart valves (TEHV). Here we report the development and characterization of a novel composite scaffold consisting of nano- and micro-scale fibrous woven fabrics and 3D hydrogels by using textile techniques combined with bioactive hydrogel formation. Embedded nano-micro fibrous scaffolds within hydrogel enhanced mechanical strength and physical structural anisotropy of the composite scaffold (similar to native aortic valve leaflets) and also reduced its compaction. We determined that the composite scaffolds supported the growth of human aortic valve interstitial cells (HAVIC), balanced the remodeling of heart valve ECM against shrinkage, and maintained better physiological fibroblastic phenotype in both normal and diseased HAVIC over single materials. These fabricated composite scaffolds enable the engineering of a living heart valve graft with improved anisotropic structure and tissue biomechanics important for maintaining valve cell phenotypes.

  8. Bi-layered calcium phosphate cement-based composite scaffold mimicking natural bone structure

    PubMed Central

    He, Fupo; Ye, Jiandong

    2013-01-01

    In this study, a core/shell bi-layered calcium phosphate cement (CPC)-based composite scaffold with adjustable compressive strength, which mimicked the structure of natural cortical/cancellous bone, was fabricated. The dense tubular CPC shell was prepared by isostatic pressing CPC powder with a specially designed mould. A porous CPC core with unidirectional lamellar pore structure was fabricated inside the cavity of dense tubular CPC shell by unidirectional freeze casting, followed by infiltration of poly(lactic-co-glycolic acid) and immobilization of collagen. The compressive strength of bi-layered CPC-based composite scaffold can be controlled by varying thickness ratio of dense layer to porous layer. Compared to the scaffold without dense shell, the pore interconnection of bi-layered scaffold was not obviously compromised because of its high unidirectional interconnectivity but poor three dimensional interconnectivity. The in vitro results showed that the rat bone marrow stromal cells attached and proliferated well on the bi-layered CPC-based composite scaffold. This novel bi-layered CPC-based composite scaffold is promising for bone repair. PMID:27877603

  9. Gel-limited synthesis of dumbbell-like Fe3O4-Ag composite microspheres and their SERS applications

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoli; Niu, Chunyu; Wang, Yongqiang; Zhou, Shaomin; Liu, Jin

    2014-10-01

    A novel gel-limited strategy was developed to synthesize dumbbell-like Fe3O4-Ag composite microspheres through a simple one-pot solvothermal method. In such a reaction system, a special precursor solution containing oleic, water, ethanol and silver ions was used and transformed into a bulk gel under heating at the very beginning of the reaction, thus all the subsequent reactions proceeded in the interior of the gel. The gel-limited reactions had two advantages, on the one hand, the magnetic Fe3O4 microspheres were fixed in the gel which avoided them aggregating together, whereas on the other hand, the silver ions stored in the gel could be gradually released and tended to diffuse towards the nearest Fe3O4 microsphere, which favored the generation of a dumbbell-like Fe3O4-Ag structure. From the time-dependent experiments under optimal conditions, the typical growth process of dumbbell-like structures clearly demonstrated that a silver seed first appeared on the surface of a single Fe3O4 microsphere, which then grew bigger slowly and finally formed a dumbbell-like Fe3O4-Ag structure. Moreover, the formation of the gel was found to be strongly affected by the ratio of water and ethanol in the precursor solution, which further influenced the morphologies of the Fe3O4-Ag microspheres. Furthermore, the effect of lattice match between Fe3O4 and Ag on the final products was also proven from the control experiments by using a template with a different surface crystalline structure. When used as SERS substrates, the final dumbbell-like Fe3O4-Ag microspheres show fast magnetic separation and the selective detection of thiram for the surface capped oleic chain during the growth process.A novel gel-limited strategy was developed to synthesize dumbbell-like Fe3O4-Ag composite microspheres through a simple one-pot solvothermal method. In such a reaction system, a special precursor solution containing oleic, water, ethanol and silver ions was used and transformed into a bulk gel

  10. Tailoring chitosan/collagen scaffolds for tissue engineering: Effect of composition and different crosslinking agents on scaffold properties.

    PubMed

    Martínez, A; Blanco, M D; Davidenko, N; Cameron, R E

    2015-11-05

    Chitosan/collagen (Chit/Col) blends have demonstrated great potential for use in tissue engineering (TE) applications. However, there exists a lack of detailed study on the influence of important design parameters (i.e, component ratio or crosslinking methods) on the essential properties of the scaffolds (morphology, mechanical stiffness, swelling, degradation and cytotoxicity). This work entailed a systematic study of these essential properties of three Chit/Col compositions, covering a wide range of component ratios and using different crosslinking methods. Our results showed the possibility of tailoring these properties by changing component ratios, since different interactions occurred between Chit/Col: samples with Chit-enriched compositions showed a hydrogen-bonding type complex (HC), whereas a self-crosslinking phenomenon was induced in Col-enriched scaffolds. Additionally, material and biological properties of the resultant matrices were further adjusted and tuned by changing crosslinking conditions. In such way, we obtained a wide range of scaffolds whose properties were tailored to meet specific needs of TE applications.

  11. Degradability, cytocompatibility, and osteogenesis of porous scaffolds of nanobredigite and PCL–PEG–PCL composite

    PubMed Central

    Hou, Jun; Fan, Donghui; Zhao, Lingming; Yu, Baoqin; Su, Jiacan; Wei, Jie; Shin, Jung-Woog

    2016-01-01

    Biocomposite scaffolds were fabricated by incorporation of nanobredigite (n-BD) into the polymer of poly(ε-caprolactone)–poly(ethyleneglycol)–poly(ε-caprolactone) (PCL–PEG–PCL). The results revealed that the addition of n-BD into PCL–PEG–PCL significantly improved water absorption, compressive strength, and degradability of the scaffolds of n-BD/PCL–PEG–PCL composite (n-BPC) compared with PCL–PEG–PCL scaffolds alone. In addition, the proliferation and alkaline phosphatase activity of MG63 cells cultured on n-BPC scaffolds were obviously higher than that cultured on PCL–PEG–PCL scaffolds. Moreover, the results of the histological evaluation from the animal model revealed that the n-BPC scaffolds significantly improved new bone formation compared with the PCL–PEG–PCL scaffolds, indicating good osteogenesis. The n-BPC scaffolds with good biocompatibility could stimulate cell proliferation, differentiation, and bone tissue regeneration and would be an excellent candidate for bone defect repair. PMID:27555774

  12. Study of the electrospun PLA/silk fibroin-gelatin composite nanofibrous scaffold for tissue engineering.

    PubMed

    Gui-Bo, Yin; You-Zhu, Zhang; Shu-Dong, Wang; De-Bing, Shi; Zhi-Hui, Dong; Wei-Guo, Fu

    2010-04-01

    In this article, a nanofibrous composite scaffold of poly L-lactic acid(PLA)/silk fibroin(SF)-gelatin was fabricated by multilayer electrospinning. To investigate the feasibility of PLA/SF-gelatin use as scaffolds, the porosity and mechanical properties were examined; in particular, the biocompatibilities were evaluated in vivo and in vitro by the means of cell adhesion and cytotoxicity testing, short-term subcutaneous implantation testing, and acute hemolysis testing according to the requirements of ISO 10993. The results showed the scaffold achieved the desirable levels of pliability (elastic up to 7.3% strain) and the appropriate breaking strength (2.22 MPa). The porosity of the SF-gelatin layer was 87% and the pore diameter was 142 nm. After 12 days of cultivation, SEM observation demonstrated the scaffold was nontoxic, biocompatible, and capable of supporting 3T3 mouse fibroblasts attachment, spreading, and growth. The hemolysis test proved the scaffolds with hemolytic rates from 3.1 to 4.5%. The subcutaneous implantation test indicated minor inflammatory reactions surrounding the scaffolds and biodegradation were initially observed in about 3 months. The desired porous structure, strong and pliable properties, combined with the ability of PLA/SF-gelatin scaffold to support cell growth in vitro, especially excellent biocompatibility in vivo, suggested potential application for tissue engineering scaffolds.

  13. MAPs/bFGF-PLGA microsphere composite-coated titanium surfaces promote increased adhesion and proliferation of fibroblasts.

    PubMed

    Wang, Zhongshan; Wu, Guofeng; Bai, Shizhu; Feng, Zhihong; Dong, Yan; Zhou, Jian; Qin, Haiyan; Zhao, Yimin

    2014-06-01

    Infection and epithelial downgrowth are two major problems with maxillofacial transcutaneous implants, and both are mainly due to lack of stable closure of soft tissues at transcutaneous sites. Fibroblasts have been shown to play a key role in the formation of biological seals. In this work, titanium (Ti) model surfaces were coated with mussel adhesive proteins (MAPs) utilizing its unique adhesion ability on diverse inorganic and organic surfaces in wet environments. Prepared basic fibroblast growth factor (bFGF)-poly(lactic-co-glycolic acid) (PLGA) microspheres can be easily synthesized and combined onto MAPs-coated Ti surfaces, due to the negative surface charges of microspheres in aqueous solution, which is in contrast to the positive charges of MAPs. Titanium model surfaces were divided into three groups. Group A: MAPs/bFGF-PLGA microspheres composite-coated Ti surfaces. Group B: MAPs-coated Ti surfaces. Group C: uncoated Ti surfaces. The effects of coated Ti surfaces on adhesion of fibroblasts, cytoskeletal organization, proliferation, and extracellular matrix (ECM)-related gene expressions were examined. The results revealed increased adhesion (P < 0.05), enhanced actin cytoskeletal organization, and up-regulated ECM-related gene expressions in groups A and B compared with group C. Increased proliferation of fibroblasts during five days of incubation was observed in group A compared with groups B and C (P < 0.05). Collectively, the results from this in vitro study demonstrated that MAPs/bFGF-PLGA microspheres composite-coated Ti surfaces had the ability to increase fibroblast functionality. In addition, MAPs/bFGF-PLGA microsphere composite-coated Ti surfaces should be studied further as a method of promoting formation of stable biological seals around transcutaneous sites.

  14. Controlled Release of Vanadium from a Composite Scaffold Stimulates Mesenchymal Stem Cell Osteochondrogenesis.

    PubMed

    Schussler, S D; Uske, K; Marwah, P; Kemp, F W; Bogden, J D; Lin, S S; Livingston Arinzeh, Treena

    2017-03-22

    Large bone defects often require the use of autograft, allograft, or synthetic bone graft augmentation; however, these treatments can result in delayed osseous integration. A tissue engineering strategy would be the use of a scaffold that could promote the normal fracture healing process of endochondral ossification, where an intermediate cartilage phase is later transformed to bone. This study investigated vanadyl acetylacetonate (VAC), an insulin mimetic, combined with a fibrous composite scaffold, consisting of polycaprolactone with nanoparticles of hydroxyapatite and beta-tricalcium phosphate, as a potential bone tissue engineering scaffold. The differentiation of human mesenchymal stem cells (MSCs) was evaluated on 0.05 and 0.025 wt% VAC containing composite scaffolds (VAC composites) in vitro using three different induction media: osteogenic (OS), chondrogenic (CCM), and chondrogenic/osteogenic (C/O) media, which mimics endochondral ossification. The controlled release of VAC was achieved over 28 days for the VAC composites, where approximately 30% of the VAC was released over this period. MSCs cultured on the VAC composites in C/O media had increased alkaline phosphatase activity, osteocalcin production, and collagen synthesis over the composite scaffold without VAC. In addition, gene expressions for chondrogenesis (Sox9) and hypertrophic markers (VEGF, MMP-13, and collagen X) were the highest on VAC composites. Almost a 1000-fold increase in VEGF gene expression and VEGF formation, as indicated by immunostaining, was achieved for cells cultured on VAC composites in C/O media, suggesting VAC will promote angiogenesis in vivo. These results demonstrate the potential of VAC composite scaffolds in supporting endochondral ossification as a bone tissue engineering strategy.

  15. Biomimetic composite scaffolds containing bioceramics and collagen/gelatin for bone tissue engineering - A mini review.

    PubMed

    Kuttappan, Shruthy; Mathew, Dennis; Nair, Manitha B

    2016-12-01

    Bone is a natural composite material consisting of an organic phase (collagen) and a mineral phase (calcium phosphate, especially hydroxyapatite). The strength of bone is attributed to the apatite, while the collagen fibrils are responsible for the toughness and visco-elasticity. The challenge in bone tissue engineering is to develop such biomimetic composite scaffolds, having a balance between biological and biomechanical properties. This review summarizes the current state of the field by outlining composite scaffolds made of gelatin/collagen in combination with bioactive ceramics for bone tissue engineering application.

  16. Preparation and characterization of aloe vera blended collagen-chitosan composite scaffold for tissue engineering applications.

    PubMed

    Jithendra, Panneerselvam; Rajam, Abraham Merlin; Kalaivani, Thambiran; Mandal, Asit Baran; Rose, Chellan

    2013-08-14

    Collagen-Chitosan (COL-CS) scaffolds supplemented with different concentrations (0.1-0.5%) of aloe vera (AV) were prepared and tested in vitro for their possible application in tissue engineering. After studying the microstructure and mechanical properties of all the composite preparations, a 0.2% AV blended COL-CS scaffold was chosen for further studies. Scaffolds were examined by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA) to understand the intermolecular interactions and their influence on the thermal property of the complex composite. Swelling property in phosphate buffered saline (pH 7.4) and in vitro biodegradability by collagenase digestion method were monitored to assess the stability of the scaffold in a physiological medium in a hydrated condition, and to assay its resistance against enzymatic forces. The scanning electron microscope (SEM) image of the scaffold samples showed porous architecture with gradual change in their morphology and reduced tensile properties with increasing aloe vera concentration. The FTIR spectrum revealed the overlap of the AV absorption peak with the absorption peak of COL-CS. The inclusion of AV to COL-CS increased the thermal stability as well as hydrophilicity of the scaffolds. Cell culture studies on the scaffold showed enhanced growth and proliferation of fibroblasts (3T3L1) without exhibiting any toxicity. Also, normal cell morphology and proliferation were observed by fluorescence microscopy and SEM. The rate of cell growth in the presence/absence of aloe vera in the scaffolds was in the order: COL-CS-AV > COL-CS > TCP (tissue culture polystyrene plate). These results suggested that the aloe vera gel-blended COL-CS scaffolds could be a promising candidate for tissue engineering applications.

  17. Fabrication and in vitro biocompatibility of biomorphic PLGA/nHA composite scaffolds for bone tissue engineering.

    PubMed

    Qian, Junmin; Xu, Weijun; Yong, Xueqing; Jin, Xinxia; Zhang, Wei

    2014-03-01

    In this study, biomorphic poly(dl-lactic-co-glycolic acid)/nano-hydroxyapatite (PLGA/nHA) composite scaffolds were successfully prepared using cane as a template. The porous morphology, phase, compression characteristics and in vitro biocompatibility of the PLGA/nHA composite scaffolds and biomorphic PLGA scaffolds as control were investigated. The results showed that the biomorphic scaffolds preserved the original honeycomb-like architecture of cane and exhibited a bimodal porous structure. The average channel diameter and micropore size of the PLGA/nHA composite scaffolds were 164 ± 52 μm and 13 ± 8 μm, respectively, with a porosity of 89.3 ± 1.4%. The incorporation of nHA into PLGA decreased the degree of crystallinity of PLGA, and significantly improved the compressive modulus of biomorphic scaffolds. The in vitro biocompatibility evaluation with MC3T3-E1 cells demonstrated that the biomorphic PLGA/nHA composite scaffolds could better support cell attachment, proliferation and differentiation than the biomorphic PLGA scaffolds. The localization depth of MC3T3-E1 cells within the channels of the biomorphic PLGA/nHA composite scaffolds could reach approximately 400 μm. The results suggested that the biomorphic PLGA/nHA composite scaffolds were promising candidates for bone tissue engineering.

  18. Culture & differentiation of mesenchymal stem cell into osteoblast on degradable biomedical composite scaffold: In vitro study

    PubMed Central

    Jain, Krishan G.; Mohanty, Sujata; Ray, Alok R.; Malhotra, Rajesh; Airan, Balram

    2015-01-01

    Background & objectives: There is a significant bone tissue loss in patients from diseases and traumatic injury. The current autograft transplantation gold standard treatment has drawbacks, namely donor site morbidity and limited supply. The field of tissue engineering has emerged with a goal to provide alternative sources for transplantations to bridge this gap between the need and lack of bone graft. The aim of this study was to prepare biocomposite scaffolds based on chitosan (CHT), polycaprolactone (PCL) and hydroxyapatite (HAP) by freeze drying method and to assess the role of scaffolds in spatial organization, proliferation, and osteogenic differentiation of human mesenchymal stem cells (hMSCs) in vitro, in order to achieve bone graft substitutes with improved physical-chemical and biological properties. Methods: Pure chitosan (100CHT) and composites (40CHT/HAP, 30CHT/HAP/PCL and 25CHT/HAP/PCL scaffolds containing 40, 30, 25 parts per hundred resin (phr) filler, respectively) in acetic acid were freeze dried and the porous foams were studied for physicochemical and in vitro biological properties. Results: Scanning electron microscope (SEM) images of the scaffolds showed porous microstructure (20-300 μm) with uniform pore distribution in all compositions. Materials were tested under compressive load in wet condition (using phosphate buffered saline at pH 7.4). The in vitro studies showed that all the scaffold compositions supported mesenchymal stem cell attachment, proliferation and differentiation as visible from SEM images, [3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay, alkaline phosphatase (ALP) assay and quantitative reverse transcription (qRT)-PCR. Interpretation & conclusions: Scaffold composition 25CHT/HAP/PCL showed better biomechanical and osteoinductive properties as evident by mechanical test and alkaline phosphatase activity and osteoblast specific gene expression studies. This study suggests that this novel

  19. Synthesis of nanofibrous gelatin/silica bioglass composite microspheres using emulsion coupled with thermally induced phase separation.

    PubMed

    Noh, Da-Young; An, Young-Hyeon; Jo, In-Hwan; Koh, Young-Hag; Kim, Hyoun-Ee

    2016-05-01

    This study proposes an innovative way of synthesizing porous gelatin/silica bioglass composite microspheres with a nanofibrous structure using emulsion coupled with thermally induced phase separation (TIPS). In particular, a mixture of the solvent (water) and non-solvent (ethanol) was used to induce a unique phase separation of gelatin/silica mixtures (i.e. gelatin/silica hybrid-rich and liquid-rich phases) at -70 °C for the creation of a nanofibrous structure. All the composite microspheres synthesized with silica contents of 10 wt.%, 15 wt.%, and 20 wt.% had well-defined spherical shapes between 124 and 136 μm in size. In addition, they were comprised of nanofibrous gelatin/silica composite walls (several tens of nanometers in thickness), where the sol-gel derived silica bioglass phase was uniformly distributed throughout the gelatin matrix. The in vitro apatite-forming ability and biocompatibility of the nanofibrous gelatin/silica bioglass composite microspheres was significantly enhanced with an increase in silica content, demonstrating their great potential for the promotion of bone tissue regeneration.

  20. cmRNA/lipoplex encapsulation in PLGA microspheres enables transfection via calcium phosphate cement (CPC)/PLGA composites.

    PubMed

    Utzinger, Maximilian; Jarzebinska, Anita; Haag, Nicolas; Schweizer, Martin; Winter, Gerhard; Dohmen, Christian; Rudolph, Carsten; Plank, Christian

    2017-03-10

    In this study lipoplexes containing chemically modified messenger RNA (cmRNA) were incorporated into poly (lactic-co-glycolic acid) (PLGA) microspheres via water-in-oil-in-water (W/O/W) double emulsion solvent evaporation technique. The nanoparticle encapsulation by microparticle formation was optimized to achieve lipoplex release and maximum transfection efficiency in surrounding cells. It was possible to adjust characteristic features in surface topology and size of the PLGA-microspheres by varying the extent of lipoplex loading into the polymer matrix. The partial release of lipids and mRNA out of the microparticle system, their accumulation in cells and the production of encoded protein were visualized via fluorescence microscopy. These bioactive microspheres, containing cmRNA bearing lipoplexes, were developed for the incorporation of a therapeutic component into injectable calcium phosphate cements (CPC). Due to the incorporation of PLGA/lipoplex microspheres as a degradable entity, the porosity of the cement phase could additionally be adjusted. This approach of complex nanoparticle incorporation into polymer/cement composites represents a promising example for combining transcript therapy with biomechanical engineering.

  1. A polycaprolactone/cuttlefish bone-derived hydroxyapatite composite porous scaffold for bone tissue engineering.

    PubMed

    Kim, Beom-Su; Yang, Sun-Sik; Lee, Jun

    2014-07-01

    Cuttlefish bone (CB) is an attractive natural biomaterial source to obtain hydroxyapatite (HAp). In this study, a porous polycaprolactone (PCL) scaffold incorporating CB-derived HAp (CB-HAp) powder was fabricated using the solvent casting and particulate leaching method. The presence of CB-HAp in PCL/CB-HAp scaffold was confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) and porosity analysis showed that the average pore dimension of the fabricated scaffold was approximately 200-300 μm, with ∼85% porosity, and that the compressive modulus increased after addition of CB-HAp powders. In vitro tests such as cell proliferation assay, cytotoxicity analysis, cell attachment observations, and alkaline phosphatase activity assays showed that the PCL/CB-HAp scaffold could improve the proliferation, viability, adherence, and osteoblast differentiation rate of MG-63 cells. When surgically implanted into rabbit calvarial bone defects, consistent with the in vitro results, PCL/CB-HAp scaffold implantation resulted in significantly higher new bone formation than did implantation of PCL alone. These findings suggest that addition of CB-HAp powder to the PCL scaffold can improve cellular response and that the PCL/CB-HAp composite scaffold has great potential for use in bone tissue engineering.

  2. Development of Composite Poly(Lactide-co-Glycolide)- Nanodiamond Scaffolds for Bone Cell Growth.

    PubMed

    Brady, Mariea A; Renzing, Andrea; Douglas, Timothy E L; Liu, Qin; Wille, Sebastian; Parizek, Martin; Bacakova, Lucie; Kromka, Alexander; Jarosova, Marketa; Godier, Greetje; Warnkel, Patrick H

    2015-02-01

    There are relatively few nanotechnologies that can produce nanocomposite scaffolds for cell growth. Electrospinning has emerged as the foremost method of producing nanofibrous biomimetic scaffolds for tissue engineering applications. In this study diamond nanoparticles were integrated into a polymer solution to develop a nanocomposite scaffold containing poly(lactide-co-glycolide) (PLGA) loaded with diamond nanoparticles. To investigate the effect of adding diamond nanoparticles to PLGA scaffolds, primary human mesenchymal stem cells (hMSCs) were seeded on the scaffolds. The cytocompatibility results showed that addition of diamond nanoparticles did not impinge upon cell proliferation, nor was there a cytotoxic cellular response after 9 days in culture. Scanning electron microscopy, transmission electron microscopy, atomic force microscopy and confocal microscopy enabled qualitative characterization of the fibres and revealed cell morphology and number. Furthermore, surface roughness was measured to evaluate diamond nanoparticle modifications, and no significant difference was found between the diamond nanocomposite and pure polymer scaffolds. On the other hand, bright spots on phase images performed by atomic force microscopy suggested a higher hardness at certain points on fibers of the PLGA-nanodiamond composites, which was supported by nanoindentation measurements. This study shows that PLGA nanofibers can be reinforced with nanodiamond without adversely affecting cell behaviour, and thus it sets the foundation for future application of these scaffolds in bone tissue engineering.

  3. A composite fibrin-based scaffold for controlled delivery of bioactive pro-angiogenetic growth factors.

    PubMed

    Briganti, Enrica; Spiller, Dario; Mirtelli, Chiara; Kull, Silvia; Counoupas, Claudio; Losi, Paola; Senesi, Sonia; Di Stefano, Rossella; Soldani, Giorgio

    2010-02-25

    The aim of this study was to fabricate and characterize in vitro a novel composite scaffold that, combining good mechanical properties with a controlled and sustained release of bioactive pro-angiogenetic growth factors, should be useful for angiogenesis induction in organs/tissues in which is also necessary to give resistance and mechanical strength. Composite scaffolds, constituted by a synthetic biocompatible material, a poly(ether)urethane-polydimethylsiloxane blend, and a biological polymer, the fibrin, were manufactured by spray, phase-inversion technique. During the manufacturing process heparin and heparin-binding growth factors, such as VEGF(165) and bFGF, were incorporated into the fibrin layer. Microscopical examinations showed a homogeneous fibrin layer firmly adherent on top of the synthetic material. Tensile tests highlighted the high elasticity of the composite scaffold and its capability to maintain integrity up to high deformation. VEGF(165) and bFGF release were controlled by fibrinogen concentration, whereas it was not affected by heparin concentration, as revealed by ELISA assay. The biological activity of the released growth factors was maintained as demonstrated by HUVEC proliferation. Finally, scaffolds induced a low monocyte mRNA expression of inflammatory markers (IL-8, L-SEL, LFA-1 and iNOS). In conclusion, the new composite scaffolds, once implanted, providing a co-localization and temporal distribution of bioactive VEGF and bFGF in addition to good mechanical properties, may be useful to stimulate new vessels formation in ischemic tissues.

  4. Fabrication of PLGA/MWNTs composite electrospun fibrous scaffolds for improved myogenic differentiation of C2C12 cells.

    PubMed

    Xu, Jiazhu; Xie, Ya; Zhang, Hongbo; Ye, Zhaoyang; Zhang, Wenjun

    2014-11-01

    Electrically conducting scaffolds have attracted tremendous attention in skeletal muscle tissue engineering. In this paper, poly(lactic-co-glycolic acid) (PLGA)/multi-wall carbon nanotubes (MWNTs) composite fibrous scaffolds were fabricated using the electrospinning technique. The physical properties of the composite fibers were characterized and proliferation and differentiation of C2C12 cells on these scaffolds were examined. It was found that the addition of MWNTs modulated the physical properties of PLGA fibers including morphology, fiber diameter, degradation, tensile strength and electrical conductivity, depending on the amount of MWNTs. These fibrous scaffolds were cytocompatible and supported the proliferation of C2C12 cells. Importantly, C2C12 cells showed more mature myotube formation on PLGA/MWNTs composite fibrous scaffolds compared to PLGA scaffolds. These results indicate that PLGA/MWNTs composite electrospun fibers have great potential in skeletal muscle tissue engineering.

  5. Fire hazard reduction of hollow glass microspheres in thermoplastic polyurethane composites.

    PubMed

    Jiao, Chuanmei; Wang, Hongzhi; Li, Shaoxiang; Chen, Xilei

    2017-02-24

    Nowadays, reducing the fire hazard of thermoplastic polyurethane (TPU) is an important research direction in the fields of fire safety materials. In this article, hollow glass microsphere (HGM) was used to reduce the fire hazard of TPU in combustion process. The fire characteristics including smoke and heat production of TPU composites were evaluated using smoke density test (SDT) and cone calorimeter test (CCT). And the thermal decomposition and flammable properties were further studied using thermogravimetric analysis/infrared spectrometry (TG-IR) and limiting oxygen index (LOI), etc. The SDT results showed that the luminous flux (LF) of TPU4 containing 2.00wt% HGM was up to 24% at the end of test without flame, which is much higher than that of TPU0 (5%). And, the CCT results indicated that 2.00wt% HGM could make the total smoke release (TSR) decrease from 1019m(2)/m(2) (TPU0) to 757m(2)/m(2) (TPU4), reduced by 26%. The TG-IR results confirmed that HGM could improve the thermal stability of composites and reduce the production of some toxic gases. The above results illustrated HGM had a good prospect in reducing the fire hazard for TPU.

  6. Electrophoretic deposition of antibiotic loaded PHBV microsphere-alginate composite coating with controlled delivery potential.

    PubMed

    Chen, Qiang; Li, Wei; Goudouri, Ourania-Menti; Ding, Yaping; Cabanas-Polo, Sandra; Boccaccini, Aldo R

    2015-06-01

    Electrophoretic deposition (EPD) technique has been developed for the fabrication of antibiotic-loaded PHBV microsphere (MS)-alginate antibacterial coatings. The composite coatings deposited from suspensions with different MS concentrations were produced in order to demonstrate the versatility of the proposed method for achieving functional coatings with tailored drug loading and release profiles. Linearly increased deposit mass with increasing MS concentrations was obtained, and MS were found to be homogeneously stabilized in the alginate matrix. Chemical composition, surface roughness and wettability of the deposited coatings were measured by Fourier transform infrared (FTIR) spectroscopy, laser profilometer and water contact angle instruments, respectively. The co-deposition mechanism was described by two separate processes according to the results of relevant measurements: (i) the deposition of alginate-adsorbed MS and (ii) the non-adsorbed alginate. Qualitative antibacterial tests indicated that MS containing coatings exhibit excellent inhibition effects against E. coli (gram-negative bacteria) after 1h of incubation. The proposed coating system combined with the simplicity of the EPD technique can be considered a promising surface modification approach for the controlled in situ delivery of drug or other biomolecules.

  7. Composite Scaffold of Poly(Vinyl Alcohol) and Interfacial Polyelectrolyte Complexation Fibers for Controlled Biomolecule Delivery

    PubMed Central

    Cutiongco, Marie Francene A.; Choo, Royden K. T.; Shen, Nathaniel J. X.; Chua, Bryan M. X.; Sju, Ervi; Choo, Amanda W. L.; Le Visage, Catherine; Yim, Evelyn K. F.

    2015-01-01

    Controlled delivery of hydrophilic proteins is an important therapeutic strategy. However, widely used methods for protein delivery suffer from low incorporation efficiency and loss of bioactivity. The versatile interfacial polyelectrolyte complexation (IPC) fibers have the capacity for precise spatiotemporal release and protection of protein, growth factor, and cell bioactivity. Yet its weak mechanical properties limit its application and translation into a viable clinical solution. To overcome this limitation, IPC fibers can be incorporated into polymeric scaffolds such as the biocompatible poly(vinyl alcohol) hydrogel (PVA). Therefore, we explored the use of a composite scaffold of PVA and IPC fibers for controlled biomolecule release. We first observed that the permeability of biomolecules through PVA films were dependent on molecular weight. Next, IPC fibers were incorporated in between layers of PVA to produce PVA–IPC composite scaffolds with different IPC fiber orientation. The composite scaffold demonstrated excellent mechanical properties and efficient biomolecule incorporation. The rate of biomolecule release from PVA–IPC composite grafts exhibited dependence on molecular weight, with lysozyme showing near-linear release for 1 month. Angiogenic factors were also incorporated into the PVA–IPC grafts, as a potential biomedical application of the composite graft. While vascular endothelial growth factor only showed a maximum cumulative release of 3%, the smaller PEGylated-QK peptide showed maximum release of 33%. Notably, the released angiogenic biomolecules induced endothelial cell activity thus indicating retention of bioactivity. We also observed lack of significant macrophage response against PVA–IPC grafts in a rabbit model. Showing permeability, mechanical strength, precise temporal growth factor release, and bioinertness, PVA–IPC fibers composite scaffolds are excellent scaffolds for controlled biomolecule delivery in soft tissue

  8. Collagen-coated polylactide microcarriers/chitosan hydrogel composite: injectable scaffold for cartilage regeneration.

    PubMed

    Hong, Yi; Gong, Yihong; Gao, Changyou; Shen, Jiacong

    2008-06-01

    A novel structure of injectable scaffold is designed and fabricated by combining collagen-coated polylactide (PLA) microcarriers and crosslinkable chitosan hydrogel. The collagen-coated PLA microcarriers were firstly mixed with the hydrogel precursor, a thickening agent of konjac glucomannan (KGM), and redox initiators of ammonium persulfate and tetramethylethylenediamine (TMEDA). The mixture was then injected into a mold and incubated at 37 degrees C to obtain the composite scaffold. The hydrogel can deliver the collagen-coated PLA microcarriers to the desired site and, after gelation, will prevent them from uncontrolled movement. On the other hand, the collagen-coated PLA microcarriers can substantially enhance the mechanical properties of the composite system. It was found that the microcarriers suspended stably in 0.6% KGM/1% chitosan derivative (CML) solution at 37 degrees C at least for 15 min. The dynamic elastic modulus (G') of the composite scaffold increased along with the increase of the microcarrier content. G' of the composite scaffold with 10% microcarriers was measured as 0.87-2.15 MPa at a frequency range of 0.1-100 rad/s, which was 120-90 times higher than that of its hydrogel system alone (12.1-24.4 kPa). In vitro culture of chondrocytes/composite scaffold showed that the cell metabolic activity increased rapidly before day 9, then leveled off. Cells in the hydrogel could attach and grow on the surface of the collagen-coated PLA microcarriers to form confluent cell layers after days 9-12. These features make the composite scaffold to be injectable and applicable in either tissue engineering, or regenerative medicine, and in particular, in orthopaedics.

  9. Composite scaffold of poly(vinyl alcohol) and interfacial polyelectrolyte complexation fibers for controlled biomolecule delivery.

    PubMed

    Cutiongco, Marie Francene A; Choo, Royden K T; Shen, Nathaniel J X; Chua, Bryan M X; Sju, Ervi; Choo, Amanda W L; Le Visage, Catherine; Yim, Evelyn K F

    2015-01-01

    Controlled delivery of hydrophilic proteins is an important therapeutic strategy. However, widely used methods for protein delivery suffer from low incorporation efficiency and loss of bioactivity. The versatile interfacial polyelectrolyte complexation (IPC) fibers have the capacity for precise spatiotemporal release and protection of protein, growth factor, and cell bioactivity. Yet its weak mechanical properties limit its application and translation into a viable clinical solution. To overcome this limitation, IPC fibers can be incorporated into polymeric scaffolds such as the biocompatible poly(vinyl alcohol) hydrogel (PVA). Therefore, we explored the use of a composite scaffold of PVA and IPC fibers for controlled biomolecule release. We first observed that the permeability of biomolecules through PVA films were dependent on molecular weight. Next, IPC fibers were incorporated in between layers of PVA to produce PVA-IPC composite scaffolds with different IPC fiber orientation. The composite scaffold demonstrated excellent mechanical properties and efficient biomolecule incorporation. The rate of biomolecule release from PVA-IPC composite grafts exhibited dependence on molecular weight, with lysozyme showing near-linear release for 1 month. Angiogenic factors were also incorporated into the PVA-IPC grafts, as a potential biomedical application of the composite graft. While vascular endothelial growth factor only showed a maximum cumulative release of 3%, the smaller PEGylated-QK peptide showed maximum release of 33%. Notably, the released angiogenic biomolecules induced endothelial cell activity thus indicating retention of bioactivity. We also observed lack of significant macrophage response against PVA-IPC grafts in a rabbit model. Showing permeability, mechanical strength, precise temporal growth factor release, and bioinertness, PVA-IPC fibers composite scaffolds are excellent scaffolds for controlled biomolecule delivery in soft tissue engineering.

  10. Three-dimensional electrospun polycaprolactone (PCL)/alginate hybrid composite scaffolds.

    PubMed

    Kim, Min Seong; Kim, GeunHyung

    2014-12-19

    Micro/nanofibrous scaffolds have been used widely in biomedical applications because the micro/nano-scale fibres resemble natural extracellular matrix and the high surface-to-volume ratio encourages cellular activities (attachment and proliferation). However, poor mechanical properties, low controllability of various shapes and difficulties in obtaining controllable pore structure have been obstacles to their use in hard-tissue regeneration. To overcome these shortcomings, we suggest a new composite system, which uses a combination method of wet electrospinning, rapid prototyping and a physical punching process. Using the process, we obtained polycaprolactone (PCL)/alginate composite scaffolds, consisting of electrospun PCL/alginate fibres and micro-sized PCL struts, with mean pore sizes of 821 ± 55 μm. To show the feasibility of the scaffolds for hard-tissue regeneration, the scaffolds were assessed not only for physical properties, including hydrophilicity, water absorption, and tensile and compressive strength, but also in vitro cellular responses (cell viability and proliferation) and osteogenic differentiation (alkaline phosphatase (ALP) activity, and mineralisation) by culturing with pre-osteoblasts (MC3T3-E1 cells). With the reinforcing micro-sized PCL struts, the elastic modulus of the PCL/alginate scaffold was significantly improved versus a pure PCL scaffold. Additionally, due to the alginate component in the fibrous scaffold, they showed significantly enhanced hydrophilic behaviour, water absorption (∼8-fold) and significant biological activities (∼1.6-fold for cell viability at 7 days, ∼2.3-fold for ALP activity at 14 days and ∼6.4-fold for calcium mineralisation at 14 days) compared with those of a pure PCL fibrous scaffold.

  11. Porous magnesium/PLGA composite scaffolds for enhanced bone regeneration following tooth extraction.

    PubMed

    Brown, Andrew; Zaky, Samer; Ray, Herbert; Sfeir, Charles

    2015-01-01

    Sixty percent of implant-supported dental prostheses require bone grafting to enhance bone quantity and quality prior to implant placement. We have developed a metallic magnesium particle/PLGA composite scaffold to overcome the limitations of currently used dental bone grafting materials. This is the first report of porous metallic magnesium/PLGA scaffolds synthesized using a solvent casting, salt leaching method. We found that incorporation of varying amounts of magnesium into the PLGA scaffolds increased the compressive strength and modulus, as well as provided a porous structure suitable for cell infiltration, as measured by mercury intrusion porosimetry. Additionally, combining basic-degrading magnesium with acidic-degrading PLGA led to an overall pH buffering effect and long-term release of magnesium over the course of a 10-week degradation assay, as measured with inductively coupled plasma-atomic emission spectroscopy. Using an indirect proliferation assay adapted from ISO 10993:5, it was found that extracts of medium from degrading magnesium/PLGA scaffolds increased bone marrow stromal cell proliferation in vitro, a phenomenon observed by other groups investigating magnesium's impact on cells. Finally, magnesium/PLGA scaffold biocompatibility was assessed in a canine socket preservation model. Micro-computed tomography and histological analysis showed the magnesium/PLGA scaffolds to be safer and more effective at preserving bone height than empty controls. Three-dimensional magnesium/PLGA composite scaffolds show promise for dental socket preservation and also, potentially, orthopedic bone regeneration. These scaffolds could decrease inflammation observed with clinically used PLGA devices, as well as enhance osteogenesis, as observed with previously studied magnesium devices.

  12. Hierarchically biomimetic bone scaffold materials: nano-HA/collagen/PLA composite.

    PubMed

    Liao, S S; Cui, F Z; Zhang, W; Feng, Q L

    2004-05-15

    A bone scaffold material (nano-HA/ collagen/PLA composite) was developed by biomimetic synthesis. It shows some features of natural bone both in main composition and hierarchical microstructure. Nano-hydroxyapatite and collagen assembled into mineralized fibril. The three-dimensional porous scaffold materials mimic the microstructure of cancellous bone. Cell culture and animal model tests showed that the composite material is bioactive. The osteoblasts were separated from the neonatal rat calvaria. Osteoblasts adhered, spread, and proliferated throughout the pores of the scaffold material within a week. A 15-mm segmental defect model in the radius of the rabbit was used to evaluate the bone-remodeling ability of the composite. Combined with 0.5 mg rhBMP-2, the material block was implanted into the defect. The segmental defect was integrated 12 weeks after surgery, and the implanted composite was partially substituted by new bone tissue. This scaffold composite has promise for the clinical repair of large bony defects according to the principles of bone tissue engineering.

  13. Characterization of the mechanical behaviors and bioactivity of tetrapod ZnO whiskers reinforced bioactive glass/gelatin composite scaffolds.

    PubMed

    Guo, Weihuang; Zhao, Fujian; Wang, Yudong; Tang, Jieyin; Chen, Xiaofeng

    2017-01-23

    The purpose of this study is to construct bone tissue engineering scaffold with high porosity, good mechanical properties, and biological activities. Bioactive glass/gelatin composite scaffolds with different amounts of tetrapod zinc oxide whiskers were produced. The morphology, mechanical properties and in vitro bioactivity of the composite scaffolds were investigated. Results showed that, the composite scaffolds had open pores with a high degree of interconnectivity, and the porosity was higher than 80%. With the amount of ZnO whiskers increased, the mechanical properties of scaffolds increased. However, the reinforcing effect began to decrease when the addition is higher than 2wt%, which was resulted by the aggregation of the ZnO whiskers. In vitro test showed that, the composite scaffolds processed good biodegradability, and in vitro apatite-forming ability. The release of zinc ions retarded the growth of the HCA, so the HCA deposited on the scaffolds with ZnO was amorphous and worm-like. Furthermore, the composite scaffolds had good biocompatibility assessed by in vitro cell tests using rMSCs. All results are promising for the application of the composite scaffolds in bone repair.

  14. Optimization of Polymer-ECM Composite Scaffolds for Tissue Engineering: Effect of Cells and Culture Conditions on Polymeric Nanofiber Mats.

    PubMed

    Goyal, Ritu; Guvendiren, Murat; Freeman, Onyi; Mao, Yong; Kohn, Joachim

    2017-01-11

    The design of composite tissue scaffolds containing an extracellular matrix (ECM) and synthetic polymer fibers is a new approach to create bioactive scaffolds that can enhance cell function. Currently, studies investigating the effects of ECM-deposition and decellularization on polymer degradation are still lacking, as are data on optimizing the stability of the ECM-containing composite scaffolds during prolonged cell culture. In this study, we develop fibrous scaffolds using three polymer compositions, representing slow (E0000), medium (E0500), and fast (E1000) degrading materials, to investigate the stability, degradation, and mechanics of the scaffolds during ECM deposition and decellularization, and during the complete cellularization-decell-recell cycle. We report data on percent molecular weight (% Mw) retention of polymeric fiber mats, changes in scaffold stiffness, ECM deposition, and the presence of fibronectin after decellularization. We concluded that the fast degrading E1000 (Mw retention ≤ 50% after 28 days) was not sufficiently stable to allow scaffold handling after 28 days in culture, while the slow degradation of E0000 (Mw retention ≥ 80% in 28 days) did not allow deposited ECM to replace the polymer support. The scaffolds made from medium degrading E0500 (Mw retention about 60% at 28 days) allowed the gradual replacement of the polymer network with cell-derived ECM while maintaining the polymer network support. Thus, polymers with an intermediate rate of degradation, maintaining good scaffold handling properties after 28 days in culture, seem best suited for creating ECM-polymer composite scaffolds.

  15. Optimization of Polymer-ECM Composite Scaffolds for Tissue Engineering: Effect of Cells and Culture Conditions on Polymeric Nanofiber Mats

    PubMed Central

    Goyal, Ritu; Guvendiren, Murat; Freeman, Onyi; Mao, Yong; Kohn, Joachim

    2017-01-01

    The design of composite tissue scaffolds containing an extracellular matrix (ECM) and synthetic polymer fibers is a new approach to create bioactive scaffolds that can enhance cell function. Currently, studies investigating the effects of ECM-deposition and decellularization on polymer degradation are still lacking, as are data on optimizing the stability of the ECM-containing composite scaffolds during prolonged cell culture. In this study, we develop fibrous scaffolds using three polymer compositions, representing slow (E0000), medium (E0500), and fast (E1000) degrading materials, to investigate the stability, degradation, and mechanics of the scaffolds during ECM deposition and decellularization, and during the complete cellularization-decell-recell cycle. We report data on percent molecular weight (% Mw) retention of polymeric fiber mats, changes in scaffold stiffness, ECM deposition, and the presence of fibronectin after decellularization. We concluded that the fast degrading E1000 (Mw retention ≤ 50% after 28 days) was not sufficiently stable to allow scaffold handling after 28 days in culture, while the slow degradation of E0000 (Mw retention ≥ 80% in 28 days) did not allow deposited ECM to replace the polymer support. The scaffolds made from medium degrading E0500 (Mw retention about 60% at 28 days) allowed the gradual replacement of the polymer network with cell-derived ECM while maintaining the polymer network support. Thus, polymers with an intermediate rate of degradation, maintaining good scaffold handling properties after 28 days in culture, seem best suited for creating ECM-polymer composite scaffolds. PMID:28085047

  16. Preparation and adsorption properties of magnetic CoFe2O4-chitosan composite microspheres

    NASA Astrophysics Data System (ADS)

    Lian, Qi; Zheng, Xue-Fang; Hu, Tie-Feng

    2015-11-01

    Magnetic chitosan microspheres made from novel polymer materials show outstanding applied characteristics. Magnetic chitosan microspheres are rather cheap, non-toxic, tasteless, alkali resistant, corrosion resistant, easily degradable, easily recyclable, and so on. It can be widely used in many fields. In this paper, magnetic CoFe2O4/chitosan core-shell microspheres are prepared by means of emulsification cross-linking technique using CoFe2O4 as core and glutaric dialdehyde as crosslinking agent. The results demonstrated that the different calcining temperature of magnetic (CoFe2O4) particles, CoFe2O4/chitosan ratio and stirring time of the suspension medium are the most effective parameters that control the size, size distribution, morphology and magnetism of the described microspheres. Finally, the size, morphology and chemical structure of the prepared materials are studied by different methods. The results show that the optimal calcination temperature of magnetic particles is 700°C, the optimal ratio of CoFe2O4/chitosan is 1: 1, ultrasonic dispersion time is 30 min. The prepared chitosan magnetic microspheres have small size and are well dispersed when the stirring time is 3 h. The prepared magnetic chitosan microspheres are well shaped spheres with a diameter from 1 to 50 μm, in which CoFe2O4 particles are dispersed uniformly. The magnetic chitosan microspheres show excellent magnetic response and have good adsorption characteristics.

  17. Raspberrylike SiO2@reduced graphene oxide@AgNP composite microspheres with high aqueous dispersity and excellent catalytic activity.

    PubMed

    Xiao, Wei; Zhang, Yanhua; Liu, Bitao

    2015-03-25

    The hybridizations of functional microspheres with graphene or graphene oxide (GO) sheets often suffer from severe agglomeration behaviors, leading to poor water dispersity of the resultant composite materials. Here, we first demonstrate that the sonication-assisted self-assembly of tiny GO sheets (whose lateral size less than 200 nm) on microspheric substrates like cationic polyelectrolyte-modified SiO2 microspheres could effectively overcome such a common drawback. On the basis of this facile strategy, we further developed reduced graphene oxide/silver nanoparticle composite film wrapped SiO2 microspheres, which not only possessed unique raspberrylike structure and high aqueous dispersity but also exhibited exceptional catalytic activity toward the reduction of 4-nitrophenol.

  18. Partially degradable film/fabric composites: textile scaffolds for liver cell culture.

    PubMed

    Karamuk, E; Mayer, J; Wintermantel, E; Akaike, T

    1999-09-01

    In this study, a composite scaffold combining textile superstructures and biomimetic glycopolymers is introduced, which may allow engineering of organotypic liver tissue in vitro. Woven poly(ethylene therephtalat) (PET) fabrics were coated on one side with a thin biodegradable polymer film (poly[D-L-lactic-co-glycolic acid] PLGA), in order to obtain a polar structure. The composite structure ensured the stability of the membrane during in vitro degradation, independently of mesh size. Matrix porosity increased when a polymer blend matrix was used. For hepatocyte culturing studies, the scaffolds were additionally coated with an artificial glycopolymer (poly[N-p-vinylbenzyl-D-lactoamide], PVLA) in order to improve cell attachment. It was observed that formation of aggregates depends on the scaffold geometry as well as on the pretreatment and medium conditions. After 4 days in culture, the pores of the fabric were filled with aggregates illustrating the possibility of immobilizing hepatocyte aggregates in well-defined spatial configurations on textile structures.

  19. In vitro and animal study of novel nano-hydroxyapatite/poly(epsilon-caprolactone) composite scaffolds fabricated by layer manufacturing process.

    PubMed

    Heo, Su-Jin; Kim, Seung-Eon; Wei, Jie; Kim, Dong Hwa; Hyun, Young-Taek; Yun, Hui-Suk; Kim, Hyung Keun; Yoon, Taek Rim; Kim, Su-Hyang; Park, Su-A; Shin, Ji Won; Shin, Jung-Woog

    2009-05-01

    The purpose of this study was to propose a computer-controllable scaffold structure made by a layer manufacturing process (LMP) with addition of nano- or micro-sized particles and to investigate the effects of particle size in vitro. In addition, the superiority of this LMP method over the conventional scaffolds made by salt leaching and gas forming process was investigated through animal study. Using the LMP, we have created a new nano-sized hydroxyapatite/poly(epsilon-caprolactone) composite (n-HPC) scaffold and a micro-sized hydroxyapatite/poly(epsilon-caprolactone) composite (m-HPC) scaffold for bone tissue engineering applications. The scaffold macropores were well interconnected, with a porosity of 73% and a pore size of 500 microm. The compressive modulus of the n-HPC and m-HPC scaffolds was 6.76 and 3.18 MPa, respectively. We compared the cellular responses to the two kinds of scaffolds. Both n-HPC and m-HPC exhibited good in vitro biocompatibility. Attachment and proliferation of mesenchymal stem cells were better on the n-HPC than on the m-HPC scaffold. Moreover, significantly higher alkaline phosphatase activity and calcium content were observed on the n-HPC than on the m-HPC scaffold. In an animal study, the LMP scaffolds enhanced bone formation, owing to their well-interconnected pores. Radiological and histological examinations confirmed that the new bony tissue had grown easily into the entire n-HPC scaffold fabricated by LMP. We suggest that the well-interconnected pores in the LMP scaffolds might encourage cell attachment, proliferation, and migration to stimulate cell functions, thus enhancing bone formation in the LMP scaffolds. This study shows that bioactive and biocompatible n-HPC composite scaffolds prepared using an LMP have potential applications in bone tissue engineering.

  20. Relevance of fiber integrated gelatin-nanohydroxyapatite composite scaffold for bone tissue regeneration

    NASA Astrophysics Data System (ADS)

    Halima Shamaz, Bibi; Anitha, A.; Vijayamohan, Manju; Kuttappan, Shruthy; Nair, Shantikumar; Nair, Manitha B.

    2015-10-01

    Porous nanohydroxyapatite (nanoHA) is a promising bone substitute, but it is brittle, which limits its utility for load bearing applications. To address this issue, herein, biodegradable electrospun microfibrous sheets of poly(L-lactic acid)-(PLLA)-polyvinyl alcohol (PVA) were incorporated into a gelatin-nanoHA matrix which was investigated for its mechanical properties, the physical integration of the fibers with the matrix, cell infiltration, osteogenic differentiation and bone regeneration. The inclusion of sacrificial fibers like PVA along with PLLA and leaching resulted in improved cellular infiltration towards the center of the scaffold. Furthermore, the treatment of PLLA fibers with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide enhanced their hydrophilicity, ensuring firm anchorage between the fibers and the gelatin-HA matrix. The incorporation of PLLA microfibers within the gelatin-nanoHA matrix reduced the brittleness of the scaffolds, the effect being proportional to the number of layers of fibrous sheets in the matrix. The proliferation and osteogenic differentiation of human adipose-derived mesenchymal stem cells was augmented on the fibrous scaffolds in comparison to those scaffolds devoid of fibers. Finally, the scaffold could promote cell infiltration, together with bone regeneration, upon implantation in a rabbit femoral cortical defect within 4 weeks. The bone regeneration potential was significantly higher when compared to commercially available HA (Surgiwear™). Thus, this biomimetic, porous, 3D composite scaffold could be offered as a promising candidate for bone regeneration in orthopedics.

  1. A composite chitosan-gelatin bi-layered, biomimetic macroporous scaffold for blood vessel tissue engineering.

    PubMed

    Badhe, Ravindra V; Bijukumar, Divya; Chejara, Dharmesh R; Mabrouk, Mostafa; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Kondiah, Pierre P D; Pillay, Viness

    2017-02-10

    A composite chitosan-gelatin macroporous hydrogel-based scaffold with bi-layered tubular architecture was engineered by solvent casting-co-particulate leaching. The scaffold constituted an inner macroporous layer concealed by a non-porous outer layer mimicking the 3D matrix of blood vessels with cellular adhesion and proliferation. The scaffold was evaluated for its morphological, physicochemical, physicomechanical and biodurability properties employing SEM, FTIR, DSC, XRD, porositometry, rheology and texture analysis. The fluid uptake and biodegradation in the presence of lysozymes was also investigated. Cellular attachment and proliferation was analysed using human dermal fibroblasts (HDF-a) seeded onto the scaffold and evaluated by MTT assay, SEM, and confocal microscopy. Results demonstrated that the scaffold had a desirable tensile strength=95.81±11kPa, elongation at break 112.5±13%, porosity 82% and pores between 100 and 230μm, 50% in vitro biodegradation at day 16 and proliferated fibroblasts over 20 days. These results demonstrate that scaffold may be an excellent tubular archetype for blood vessel tissue engineering.

  2. Degradation and biocompatibility of porous nano-hydroxyapatite/polyurethane composite scaffold for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Dong, Zhihong; Li, Yubao; Zou, Qin

    2009-04-01

    Porous scaffold containing 30 wt% nano-hydroxyapatite (n-HA) and 70 wt% polyurethane (PU) from castor oil was prepared by a foaming method and investigated by X-ray diffraction (XRD), Fourier transform infrared absorption (FTIR), scanning electron microscopy (SEM) techniques. The results show that n-HA particles disperse homogeneously in the PU matrix. The porous scaffold has not only macropores of 100-800 μm in size but also a lot of micropores on the walls of macropores. The porosity and compressive strength of scaffold are 80% and 271 kPa, respectively. After soaking in simulated body fluid (SBF), hydrolysis and deposition partly occur on the scaffold. The biological evaluation in vitro and in vivo shows that the n-HA/PU scaffold is non-cytotoxic and degradable. The porous structure provides a good microenvironment for cell adherence, growth and proliferation. The n-HA/PU composite scaffold can be satisfied with the basic requirement for tissue engineering, and has the potential to be applied in repair and substitute of human menisci of the knee-joint and articular cartilage.

  3. Novel synthesis strategy for composite hydrogel of collagen/hydroxyapatite-microsphere originating from conversion of CaCO3 templates.

    PubMed

    Wei, Qingrong; Lu, Jian; Wang, Qiaoying; Fan, Hongsong; Zhang, Xingdong

    2015-03-20

    Inspired by coralline-derived hydroxyapatite, we designed a methodological route to synthesize carbonated-hydroxyapatite microspheres from the conversion of CaCO3 spherulite templates within a collagen matrix under mild conditions and thus constructed the composite hydrogel of collagen/hydroxyapatite-microspheres. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) were employed to confirm the successful generation of the carbonated hydroxyapatite phase originating from CaCO3, and the ratios of calcium to phosphate were tracked over time. Variations in the weight portion of the components in the hybrid gels before and after the phase transformation of the CaCO3 templates were identified via thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) shows these composite hydrogels have a unique multiscale microstructure consisting of a collagen nanofibril network and hydroxyapatite microspheres. The relationship between the hydroxyapatite nanocrystals and the collagen fibrils was revealed by transmission electron microscopy (TEM) in detail, and the selected area electron diffraction (SAED) pattern further confirmed the results of the XRD analyses which show the typical low crystallinity of the generated hydroxyapatite. This smart synthesis strategy achieved the simultaneous construction of microscale hydroxyapatite particles and collagen fibrillar hydrogel, and appears to provide a novel route to explore an advanced functional hydrogel materials with promising potentials for applications in bone tissue engineering and reconstruction medicine.

  4. Novel synthesis strategy for composite hydrogel of collagen/hydroxyapatite-microsphere originating from conversion of CaCO3 templates

    NASA Astrophysics Data System (ADS)

    Wei, Qingrong; Lu, Jian; Wang, Qiaoying; Fan, Hongsong; Zhang, Xingdong

    2015-03-01

    Inspired by coralline-derived hydroxyapatite, we designed a methodological route to synthesize carbonated-hydroxyapatite microspheres from the conversion of CaCO3 spherulite templates within a collagen matrix under mild conditions and thus constructed the composite hydrogel of collagen/hydroxyapatite-microspheres. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) were employed to confirm the successful generation of the carbonated hydroxyapatite phase originating from CaCO3, and the ratios of calcium to phosphate were tracked over time. Variations in the weight portion of the components in the hybrid gels before and after the phase transformation of the CaCO3 templates were identified via thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) shows these composite hydrogels have a unique multiscale microstructure consisting of a collagen nanofibril network and hydroxyapatite microspheres. The relationship between the hydroxyapatite nanocrystals and the collagen fibrils was revealed by transmission electron microscopy (TEM) in detail, and the selected area electron diffraction (SAED) pattern further confirmed the results of the XRD analyses which show the typical low crystallinity of the generated hydroxyapatite. This smart synthesis strategy achieved the simultaneous construction of microscale hydroxyapatite particles and collagen fibrillar hydrogel, and appears to provide a novel route to explore an advanced functional hydrogel materials with promising potentials for applications in bone tissue engineering and reconstruction medicine.

  5. Tailoring the morphology of raspberry-like carbon black/polystyrene composite microspheres for fabricating superhydrophobic surface

    SciTech Connect

    Bao, Yubin; Li, Qiuying; Xue, Pengfei; Huang, Jianfeng; Wang, Jibin; Guo, Weihong; Wu, Chifei

    2011-05-15

    In our previous report, raspberry-like carbon black/polystyrene (CB/PS) composite microsphere was prepared through heterocoagulation process. Based on the previous study, in the present work, the morphology of raspberry-like CB/PS particle is tailored through adjusting the polarity and the concentration ratio of CB/PS colloidal suspension with the purpose to prepare particulate film for the fabrication of superhydrophobic surface. Scanning electron microscope (SEM) confirms the morphology of raspberry-like particle and the coverage of CB. Rough surfaces fabricated by raspberry-like particles with proper morphology are observed by SEM and clear evidence of superhydrophobic surface is shown. The structure of raspberry-like particle is analyzed by atom force microscope. The proposed relationship between the hydrophobicity and the structure of CB aggregates on the surface of PS microsphere is discussed in details.

  6. Poly(ε-caprolactone)/gelatin composite electrospun scaffolds with porous crater-like structures for tissue engineering

    PubMed Central

    Hwang, Patrick T.J.; Murdock, Kyle; Alexander, Grant C.; Salaam, Amanee D.; Ng, Joshua I.; Lim, Dong-Jin; Dean, Derrick; Jun, Ho-Wook

    2016-01-01

    Electrospinning has been widely used to fabricate scaffolds imitating the structure of natural extracellular matrix (ECM). However, conventional electrospinning produces tightly compacted nanofiber layers with only small superficial pores and a lack of bioactivity, which limit the usefulness of electrospinning in biomedical applications. Thus, a porous poly(ε-caprolactone) (PCL)/gelatin composite electrospun scaffold with crater-like structures was developed. Porous crater-like structures were created on the scaffold by a gas foaming/salt leaching process; this unique fiber structure had more large pore areas and higher porosity than the conventional electrospun fiber network. Various ratios of PCL/gelatin (concentration ratios: 100/0, 75/25, and 50/50) composite electrospun scaffolds with and without crater-like structures were characterized by their microstructures, surface chemistry, degradation, mechanical properties, and ability to facilitate cell growth and infiltration. The combination of PCL and gelatin endowed the scaffold with both structural stability of PCL and bioactivity of gelatin. All ratios of scaffolds with crater-like structures showed fairly similar surface chemistry, degradation rates, and mechanical properties to equivalent scaffolds without crater-like structures; however, craterized scaffolds displayed higher human mesenchymal stem cell (hMSC) proliferation and infiltration throughout the scaffolds after 7-day culture. Therefore, these results demonstrated that PCL/gelatin composite electrospun scaffolds with crater-like structures can provide a structurally and biochemically improved three-dimensional ECM-mimicking microenvironment. PMID:26567028

  7. Poly(ɛ-caprolactone)/gelatin composite electrospun scaffolds with porous crater-like structures for tissue engineering.

    PubMed

    Hwang, Patrick T J; Murdock, Kyle; Alexander, Grant C; Salaam, Amanee D; Ng, Joshua I; Lim, Dong-Jin; Dean, Derrick; Jun, Ho-Wook

    2016-04-01

    Electrospinning has been widely used to fabricate scaffolds imitating the structure of natural extracellular matrix (ECM). However, conventional electrospinning produces tightly compacted nanofiber layers with only small superficial pores and a lack of bioactivity, which limit the usefulness of electrospinning in biomedical applications. Thus, a porous poly(ε-caprolactone) (PCL)/gelatin composite electrospun scaffold with crater-like structures was developed. Porous crater-like structures were created on the scaffold by a gas foaming/salt leaching process; this unique fiber structure had more large pore areas and higher porosity than the conventional electrospun fiber network. Various ratios of PCL/gelatin (concentration ratios: 100/0, 75/25, and 50/50) composite electrospun scaffolds with and without crater-like structures were characterized by their microstructures, surface chemistry, degradation, mechanical properties, and ability to facilitate cell growth and infiltration. The combination of PCL and gelatin endowed the scaffold with both structural stability of PCL and bioactivity of gelatin. All ratios of scaffolds with crater-like structures showed fairly similar surface chemistry, degradation rates, and mechanical properties to equivalent scaffolds without crater-like structures; however, craterized scaffolds displayed higher human mesenchymal stem cell (hMSC) proliferation and infiltration throughout the scaffolds after 7-day culture. Therefore, these results demonstrated that PCL/gelatin composite electrospun scaffolds with crater-like structures can provide a structurally and biochemically improved three-dimensional ECM-mimicking microenvironment.

  8. Fabrication and characterization of layered chitosan/silk fibroin/nano-hydroxyapatite scaffolds with designed composition and mechanical properties.

    PubMed

    Zhou, Ting; Wu, Jingjing; Liu, Jiaoyan; Luo, Ying; Wan, Ying

    2015-07-30

    Chitosan/nano-hydroxyapatite (HA) composites were first prepared and then used together with chitosan and silk fibroin (SF) to produce a type of four-layer porous scaffold that is potentially applicable for articular cartilage repair. The bottom layer of the scaffold was built with the chitosan/HA composite and the other three layers of the scaffold were fabricated using chitosan/SF composites in which the content of the chitosan and SF was altered in a mutually reversed trend. The so-produced chitosan/SF/HA scaffolds were further crosslinked using tripolyphosphate to achieve enhanced mechanical properties. Interconnected porous microstructures throughout the scaffolds were constructed using a temperature gradient processing technique, and the resultant scaffolds were endowed with graded pore-sizes and porosities as well as porous interface zones between contiguous layers without visual clefts. The compressive modulus and stress at 10% strain of the scaffolds in wet state showed a gradient-changed trend which partially mimics the compressive mechanical properties of an articular cartilage matrix. Cell culture on some chitosan/SF/HA scaffolds for a period of time of up to 14 d showed that the scaffolds were able to well support the growth and infiltration of cells, suggesting that the presently developed chitosan/SF/HA scaffolds have promising potential for articular cartilage repair.

  9. Adsorption of Cd(II), Cu(II) and Ni(II) ions by cross-linking chitosan/rectorite nano-hybrid composite microspheres.

    PubMed

    Zeng, Lixuan; Chen, Yufei; Zhang, Qiuyun; Guo, Xingmei; Peng, Yanni; Xiao, Huijuan; Chen, Xiaocheng; Luo, Jiwen

    2015-10-05

    Chitosan/rectorie (CTS/REC) nano-hybrid composite microsphere was prepared by changing the proportion of CTS/REC with 2:1, 3:1 and 4:1. Compared with the pure cross-linking chitosan microsphere, the nano-hybrid composite microsphere was proved to have better sorption capacity of Cd(II), Cu(II) and Ni(II), especially 2:1(CTS/REC-1). The adsorption behavior of the microsphere of Cd(II), Cu(II) and Ni(II) was investigated in single and binary metal systems. In single system, the equilibrium studies showed that the adsorption of Cd(II), Cu(II) and Ni(II) followed the Langmuir model and the pseudo-second-order kinetic model. The negative values of (ΔG) suggested that the adsorption process was spontaneous. In binary system, the combined action of the metals was found to be antagonistic and the metal sorption followed the order of Cu(II)>Cd(II)>Ni(II). The regeneration studies indicated that EDTA desorbed Cd(II), Cu(II) and Ni(II) from cross-linking microspheres better than HCl. The FT-IR and XPS spectra showed that coordination bonds were formed between Cd(II), Cu(II) and Ni(II) and the nitrogen atoms of cross-linking CTS/REC nano-hybrid composite microspheres.

  10. Engineered osteochondral grafts using biphasic composite solid free-form fabricated scaffolds.

    PubMed

    Schek, Rachel M; Taboas, Juan M; Segvich, Sharon J; Hollister, Scott J; Krebsbach, Paul H

    2004-01-01

    Tissue engineering has provided an alternative to traditional strategies to repair cartilage damaged by injury or degenerative disease. A successful strategy to engineer osteochondral tissue will mimic the natural contour of the articulating surface, achieve native mechanical properties and functional load-bearing ability, and lead to integration with host cartilage and underlying subchondral bone. Image-based design (IBD) and solid free-form (SFF) fabrication can be used to generate scaffolds that are load bearing and match articular geometry. The objective of this study was to utilize materials and biological factors in an integrated approach to regenerate a multitissue interface. Biphasic composite scaffolds manufactured by IBD and SFF fabrication were used to simultaneously generate bone and cartilage in discrete regions and provide for the development of a stable interface between cartilage and subchondral bone. Poly-L-lactic acid/hydroxyapatite composite scaffolds were differentially seeded with fibroblasts transduced with an adenovirus expressing bone morphogenetic protein 7 (BMP-7) in the ceramic phase and fully differentiated chondrocytes in the polymeric phase. After subcutaneous implantation into mice, the biphasic scaffolds promoted the simultaneous growth of bone, cartilage, and a mineralized interface tissue. Within the ceramic phase, the pockets of tissue generated included blood vessels, marrow stroma, and adipose tissue. This combination of IBD and SFF-fabricated biphasic scaffolds with gene and cell therapy is a promising approach to regenerate osteochondral defects.

  11. Neocartilage formation from mesenchymal stem cells grown in type II collagen-hyaluronan composite scaffolds.

    PubMed

    Yeh, Hsi-Yi; Lin, Ting-Yu; Lin, Chen-Huan; Yen, B Linju; Tsai, Ching-Lin; Hsu, Shan-Hui

    2013-01-01

    Three-dimensional (3D) collagen type II-hyaluronan (HA) composite scaffolds (CII-HA) which mimics the extracellular environment of natural cartilage were fabricated in this study. Rheological measurements demonstrated that the incorporation of HA increased the compression modulus of the scaffolds. An initial in vitro evaluation showed that scaffolds seeded with porcine chondrocytes formed cartilaginous-like tissue after 8 weeks, and HA functioned to promote the growth of chondrocytes into scaffolds. Placenta-derived multipotent cells (PDMC) and gingival fibroblasts (GF) were seeded on tissue culture polystyrene (TCPS), CII-HA films, and small intestinal submucosa (SIS) sheets for comparing their chondrogenesis differentiation potentials with those of adipose-derived adult stem cells (ADAS) and bone marrow-derived mesenchymal stem cells (BMSC). Among different cells, PDMC showed the greatest chondrogenic differentiation potential on both CII-HA films and SIS sheets upon TGF-β3 induction, followed by GF. This was evidenced by the up-regulation of chondrogenic genes (Sox9, aggrecan, and collagen type II), which was not observed for cells grown on TCPS. This finding suggested the essential role of substrate materials in the chondrogenic differentiation of PDMC and GF. Neocartilage formation was more obvious in both PDMC and GF cells plated on CII-HA composite scaffolds vs. 8-layer SIS at 28 days in vitro. Finally, implantation of PDMC/CII-HA constructs into NOD-SCID mice confirmed the formation of tissue-engineered cartilage in vivo.

  12. A biodegradable porous composite scaffold of PGA/beta-TCP for bone tissue engineering.

    PubMed

    Cao, Hong; Kuboyama, Noboru

    2010-02-01

    Polyglycolic acid (PGA) and beta-tricalcium phosphate (beta-TCP) each have many applications as tissue repair materials. In this study, three-dimensional (3D) porous composite scaffolds of PGA/beta-TCP (in 1:1 and 1:3 weight ratios) were fabricated using the solvent casting and particulate leaching method. PGA/beta-TCP scaffolds with high porosity, interconnected 3D pores and rough surfaces were obtained and were observed using scanning electron microscopy (SEM) and micro-computed tomography (micro-CT). The PGA/beta-TCP scaffolds were investigated during the repair of critical bone defects (3 mm diameter, 2 mm depth) in rat femoral medial-epicondyles, compared with hydroxylapatite (HAP) and no implant as controls. Quantitative imageology analysis (volume and density of new bone) and qualitative histological evaluations (hematoxylin and eosin staining; tartrate-resistant acid phosphatase-hematoxylin counterstaining) were characterized using in vivo micro-CT images and histological sections at 0, 14, 30 and 90 days after surgery. Significant differences of all variables were tested by multivariate analysis (p<0.05). The results showed that the bone reformation by using the PGA/beta-TCP scaffolds began within 14 days of surgery, and were healing well at 30 days after surgery. By 90 days after surgery, the bone replacement was almost completed and presented a healthy bone appearance. The new bone mineral densities (mg/cm(3)) with HAP, PGA/beta-TCP (1:1) and PGA/beta-TCP (1:3) at 90 days after surgery were: 390.4+/-18.1, 563.8+/-26.9 and 606.3+/-26.9, respectively. The new bone mineral density with the PGA/beta-TCP scaffold was higher than with HAP (p<0.001), and with the PGA/beta-TCP (1:3) scaffold was higher than with the PGA/beta-TCP (1:1) scaffold at each time examined (p<0.05). The biodegradation percents (%) of HAP, PGA/beta-TCP (1:1) and PGA/beta-TCP (1:3) at 90 days after surgery were: 35.1+/-5.5, 99.0+/-1.0 and 96.2+/-3.3, respectively. The biodegradation

  13. 3D Printed Polycaprolactone Carbon Nanotube Composite Scaffolds for Cardiac Tissue Engineering.

    PubMed

    Ho, Chee Meng Benjamin; Mishra, Abhinay; Lin, Pearlyn Teo Pei; Ng, Sum Huan; Yeong, Wai Yee; Kim, Young-Jin; Yoon, Yong-Jin

    2017-04-01

    Fabrication of tissue engineering scaffolds with the use of novel 3D printing has gained lot of attention, however systematic investigation of biomaterials for 3D printing have not been widely explored. In this report, well-defined structures of polycaprolactone (PCL) and PCL- carbon nanotube (PCL-CNT) composite scaffolds have been designed and fabricated using a 3D printer. Conditions for 3D printing has been optimized while the effects of varying CNT percentages with PCL matrix on the thermal, mechanical and biological properties of the printed scaffolds are studied. Raman spectroscopy is used to characterise the functionalized CNTs and its interactions with PCL matrix. Mechanical properties of the composites are characterised using nanoindentation. Maximum peak load, elastic modulus and hardness increases with increasing CNT content. Differential scanning calorimetry (DSC) studies reveal the thermal and crystalline behaviour of PCL and its CNT composites. Biodegradation studies are performed in Pseudomonas Lipase enzymatic media, showing its specificity and effect on degradation rate. Cell imaging and viability studies of H9c2 cells from rat origin on the scaffolds are performed using fluorescence imaging and MTT assay, respectively. PCL and its CNT composites are able to show cell proliferation and have the potential to be used in cardiac tissue engineering.

  14. [Research on the mechanical properties of bone scaffold reinforced by magnesium alloy/bioceramics composite with stereolithography double channels].

    PubMed

    Li, Changhai; Lian, Qin; Zhuang, Pei; Wang, Junzhong; Li, Dichen

    2015-02-01

    Focusing on the poor mechanical strength of porous bioceramics bone scaffold, and taking into account of the good mechanical properties of biodegradable magnesium alloy, we proposed a novel method to fabricate magnesium alloy/bioceramics composite bone scaffold with stereolithography double channels. Firstly, a scaffold structure without mutually connected double channels was designed. Then, an optimized bioceramics scaffold was fabricated according to stereolithography and gel-casing. Molten AZ31 magnesium alloy was perfused into the secondary channel of scaffold by low-pressure casting, and magnesium alloy/bioceramics composite bone scaffold was obtained when magnesium alloy was solidified. The compression test showed that the strength of bioceramics scaffold with only one channel and without magnesium alloy was (9.76 ± 0.64) MPa, while the strength of magnesium alloy/bioceramics composite scaffold with double channels was (17.25 ± 0.88) MPa. It can be concluded that the magnesium alloy/bioceramics composite is obviously able to improve the scaffold strength.

  15. Rapid prototyping amphiphilic polymer/hydroxyapatite composite scaffolds with hydration-induced self-fixation behavior.

    PubMed

    Kutikov, Artem B; Gurijala, Anvesh; Song, Jie

    2015-03-01

    Two major factors hampering the broad use of rapid prototyped biomaterials for tissue engineering applications are the requirement for custom-designed or expensive research-grade three-dimensional (3D) printers and the limited selection of suitable thermoplastic biomaterials exhibiting physical characteristics desired for facile surgical handling and biological properties encouraging tissue integration. Properly designed thermoplastic biodegradable amphiphilic polymers can exhibit hydration-dependent hydrophilicity changes and stiffening behavior, which may be exploited to facilitate the surgical delivery/self-fixation of the scaffold within a physiological tissue environment. Compared to conventional hydrophobic polyesters, they also present significant advantages in blending with hydrophilic osteoconductive minerals with improved interfacial adhesion for bone tissue engineering applications. Here, we demonstrated the excellent blending of biodegradable, amphiphilic poly(D,L-lactic acid)-poly(ethylene glycol)-poly(D,L-lactic acid) (PLA-PEG-PLA) (PELA) triblock co-polymer with hydroxyapatite (HA) and the fabrication of high-quality rapid prototyped 3D macroporous composite scaffolds using an unmodified consumer-grade 3D printer. The rapid prototyped HA-PELA composite scaffolds and the PELA control (without HA) swelled (66% and 44% volume increases, respectively) and stiffened (1.38-fold and 4-fold increases in compressive modulus, respectively) in water. To test the hypothesis that the hydration-induced physical changes can translate into self-fixation properties of the scaffolds within a confined defect, a straightforward in vitro pull-out test was designed to quantify the peak force required to dislodge these scaffolds from a simulated cylindrical defect at dry versus wet states. Consistent with our hypothesis, the peak fixation force measured for the PELA and HA-PELA scaffolds increased 6-fold and 15-fold upon hydration, respectively. Furthermore, we showed that

  16. Rapid Prototyping Amphiphilic Polymer/Hydroxyapatite Composite Scaffolds with Hydration-Induced Self-Fixation Behavior

    PubMed Central

    Kutikov, Artem B.; Gurijala, Anvesh

    2015-01-01

    Two major factors hampering the broad use of rapid prototyped biomaterials for tissue engineering applications are the requirement for custom-designed or expensive research-grade three-dimensional (3D) printers and the limited selection of suitable thermoplastic biomaterials exhibiting physical characteristics desired for facile surgical handling and biological properties encouraging tissue integration. Properly designed thermoplastic biodegradable amphiphilic polymers can exhibit hydration-dependent hydrophilicity changes and stiffening behavior, which may be exploited to facilitate the surgical delivery/self-fixation of the scaffold within a physiological tissue environment. Compared to conventional hydrophobic polyesters, they also present significant advantages in blending with hydrophilic osteoconductive minerals with improved interfacial adhesion for bone tissue engineering applications. Here, we demonstrated the excellent blending of biodegradable, amphiphilic poly(D,L-lactic acid)-poly(ethylene glycol)-poly(D,L-lactic acid) (PLA-PEG-PLA) (PELA) triblock co-polymer with hydroxyapatite (HA) and the fabrication of high-quality rapid prototyped 3D macroporous composite scaffolds using an unmodified consumer-grade 3D printer. The rapid prototyped HA-PELA composite scaffolds and the PELA control (without HA) swelled (66% and 44% volume increases, respectively) and stiffened (1.38-fold and 4-fold increases in compressive modulus, respectively) in water. To test the hypothesis that the hydration-induced physical changes can translate into self-fixation properties of the scaffolds within a confined defect, a straightforward in vitro pull-out test was designed to quantify the peak force required to dislodge these scaffolds from a simulated cylindrical defect at dry versus wet states. Consistent with our hypothesis, the peak fixation force measured for the PELA and HA-PELA scaffolds increased 6-fold and 15-fold upon hydration, respectively. Furthermore, we showed that

  17. Biodegradable composite scaffolds of bioactive glass/chitosan/carboxymethyl cellulose for hemostatic and bone regeneration.

    PubMed

    Chen, Chen; Li, Hong; Pan, Jianfeng; Yan, Zuoqin; Yao, Zhenjun; Fan, Wenshuai; Guo, Changan

    2015-02-01

    Hemostasis in orthopedic osteotomy or bone cutting requires different methods and materials. The bleeding of bone marrow can be mostly stopped by bone wax. However, the wax cannot be absorbed, which leads to artificial prosthesis loosening, foreign matter reaction, and infection. Here, a bioactive glass/chitosan/carboxymethyl cellulose (BG/CS/CMC) composite scaffold was designed to replace traditional wax. WST-1 assay indicated the BG/CS/CMC composite resulted in excellent biocompatibility with no cytotoxicity. In vivo osteogenesis assessment revealed that the BG/CS/CMC composite played a dominant role in bone regeneration and hemostasis. The BG/CS/CMC composite had the same hemostasis effect as bone wax; in addition its biodegradation also led to the functional reconstruction of bone defects. Thus, BG/CS/CMC scaffolds can serve as a potential material for bone repair and hemostasis in critical-sized bone defects.

  18. Preparation and Properties of Bamboo Fiber/Nano-hydroxyapatite/Poly(lactic-co-glycolic) Composite Scaffold for Bone Tissue Engineering.

    PubMed

    Jiang, Liuyun; Li, Ye; Xiong, Chengdong; Su, Shengpei; Ding, Haojie

    2017-02-08

    In this study, bamboo fiber was first designed to incorporate into nano-hydroxyapatite/poly(lactic-co-glycolic) to obtain a new composite scaffold of bamboo fiber/nano-hydroxyapatite/poly(lactic-co- glycolic) (BF/n-HA/PLGA) by freeze-drying method. The effect of their components and some factors consisting of different freeze temperatures, concentrations, and pore-forming agents on the porous morphology, porosity, and compressive properties of the scaffold were investigated by scanning electron microscope, modified liquid displacement method, and electromechanical universal testing machine. The results indicated that the 5% BF/30% n-HA/PLGA composite scaffold, prepared with 5% (w/v) high concentration and frozen at -20 °C without pore-forming agent, had the best ideal porous structure and porosity as well as compressive properties, which far exceed those of n-HA/PLGA composite scaffold. In addition, the in vitro simulated body fluids soaking and cell culture experiment showed the addition of BF into the scaffold accelerated the BF/n-HA/PLGA composite scaffolds degradation and exhibited good cytocompatibility, including attachment and proliferation. All the results of the study show that BF has improved the properties of n-HA/PLGA composite scaffolds and BF/n-HA/PLGA might have a great potential for bone tissue engineering scaffold.

  19. Effect of nanofiber content on bone regeneration of silk fibroin/poly(ε-caprolactone) nano/microfibrous composite scaffolds.

    PubMed

    Kim, Beom Su; Park, Ko Eun; Kim, Min Hee; You, Hyung Keun; Lee, Jun; Park, Won Ho

    2015-01-01

    The broad application of electrospun nanofibrous scaffolds in tissue engineering is limited by their small pore size, which has a negative influence on cell migration. This disadvantage could be significantly improved through the combination of nano- and microfibrous structure. To accomplish this, different nano/microfibrous scaffolds were produced by hybrid electrospinning, combining solution electrospinning with melt electrospinning, while varying the content of the nanofiber. The morphology of the silk fibroin (SF)/poly(ε-caprolactone) (PCL) nano/microfibrous composite scaffolds was investigated with field-emission scanning electron microscopy, while the mechanical and pore properties were assessed by measurement of tensile strength and mercury porosimetry. To assay cell proliferation, cell viability, and infiltration ability, human mesenchymal stem cells were seeded on the SF/PCL nano/microfibrous composite scaffolds. From in vivo tests, it was found that the bone-regenerating ability of SF/PCL nano/microfibrous composite scaffolds was closely associated with the nanofiber content in the composite scaffolds. In conclusion, this approach of controlling the nanofiber content in SF/PCL nano/microfibrous composite scaffolds could be useful in the design of novel scaffolds for tissue engineering.

  20. Amino-functionalized core-shell magnetic mesoporous composite microspheres for Pb(II) and Cd(II) removal.

    PubMed

    Tang, Yulin; Liang, Song; Wang, Juntao; Yu, Shuili; Wang, Yilong

    2013-04-01

    Amino-functionalized Fe3O4@mesoporous SiO2 core-shell composite microspheres NH2-MS in created in multiple synthesis steps have been investigated for Pb(II) and Cd(II) adsorption. The microspheres were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), N2 adsorption-desorption, zeta potential measurements and vibrating sample magnetometer. Batch adsorption tests indicated that NH2-MS exhibited higher adsorption affinity toward Pb(II) and Cd(II) than MS did. The Langmuir model could fit the adsorption isotherm very well with maximum adsorption capacity of 128.21 and 51.81 mg/g for Pb(II) and Cd(II), respectively, implying that adsorption processes involved monolayer adsorption. Pb(II) and Cd(II) adsorption could be well described by the pseudo second-order kinetics model, and was found to be strongly dependent on pH and humic acid. The Pb(II)- and Cd(II)-loaded microspheres were effectively desorbed using 0.01 mol/L HCl or EDTA solution. NH2-MS have promise for use as adsorbents in the removal of Pb(II) and Cd(II) in wastewater treatment processes.

  1. Variation of mechanical behavior of β-TCP/collagen two phase composite scaffold with mesenchymal stem cell in vitro.

    PubMed

    Arahira, Takaaki; Todo, Mitsugu

    2016-08-01

    The primary aim of this study is to characterize the variational behavior of the compressive mechanical property of bioceramic-based scaffolds using stem cells during the cell culture period. β-Tricalcium phosphate (TCP)/collagen two phase composites and β-TCP scaffolds were fabricated using the polyurethane template technique and a subsequent freeze-drying method. Rat bone-marrow mesenchymal stem cells (rMSCs) were then cultured in these scaffolds for up to 28 days. Compression tests of the scaffolds with rMSCs were periodically conducted. Biological properties, such as the cell number, alkaline phosphatase (ALP) activity, and gene expressions of osteogenesis, were evaluated. The microstructural change due to cell growth and the formation of extracellular matrices was examined using a field-emission scanning electron microscope. The compressive property was then correlated with the biological properties and microstructures to understand the mechanism of the variational behavior of the macroscopic mechanical property. The porous collagen structure in the β-TCP scaffold effectively improved the structural stability of the composite scaffold, whereas the β-TCP scaffold exhibited structural instability with the collapse of the porous structure when immersed in a culture medium. The β-TCP/collagen composite scaffold exhibited higher ALP activity and more active generation of osteoblastic markers than the β-TCP scaffold.

  2. Biomimetic composite scaffolds based on mineralization of hydroxyapatite on electrospun poly(ɛ-caprolactone)/nanocellulose fibers.

    PubMed

    Si, Junhui; Cui, Zhixiang; Wang, Qianting; Liu, Qiong; Liu, Chuntai

    2016-06-05

    A biomimetic nanocomposite scaffold with HA formation on the electrospun poly(ɛ-caprolactone) (PCL)/nanocellulose (NC) fibrous matrix was developed in this study. The electrospun PCL/NC fiber mat was built and then biomineralized by treatment in simulated body fluid (SBF). Using such a rapid and effective procedure, a continuous biomimetic crystalline HA layer could be successfully formed without the need of any additional chemical modification of the substrate surface. The results showed that the introduction of NC into composite fibers is an effective approach to induce the deposition of HA nucleus as well as to improve their distribution and growth of a crystalline HA layer on the fibrous scaffolds. The water contact angle (WCA) of the PCL/NC/HA scaffolds decreases with increasing NC content and mineralization time, resulting in the enhancement of their hydrophilicity. These results indicated that HA-mineralized on PCL/NC fiber can be prepared directly by simply using SBF immersion.

  3. Facile growth and composition-dependent photocatalytic activity of flowerlike BiOCl1-xBrx hierarchical microspheres

    NASA Astrophysics Data System (ADS)

    Qin, Qin; Guo, Yingna; Zhou, Dandan; Yang, Yuxin; Guo, Yihang

    2016-12-01

    A group of nanosheet-assembled three-dimensional BiOCl1-xBrx hierarchical microspheres (x = 0, 0.3, 0.4, 0.5, 0.7, 0.8 and 1.0) with layered tetragonal crystal phase were prepared by 2-methoxyethanol-assisted solvothermal route and using ionic liquids as both halogen sources and structure-directing agent. By the combination of the results including XRD, XPS and UV-vis/DR spectra, lattice substitution of halogen atoms each other and then formation of BiOCl1-xBrx solid solution was evidenced. Additionally, the BiOCl1-xBrx microspheres exhibited interesting composition-dependent band gaps. The simulated sunlight and visible-light photocatalytic properties including degradation, mineralization and reusability of the BiOCl1-xBrx microspheres were evaluated by selecting p-nitrophenol (PNP) and tetrabromobisphenol-A (TBBPA) as the target pollutant compounds, finding that the balance between the suitable band gap and adequate potential of the valence band in BiOCl1-xBrx crystals dominated their photocatalytic activity. Additionally, the BiOCl1-xBrx microspheres with advantages such as enhanced photon utilization efficiency, larger BET surface area and favorable (110) exposed reactive surface gave the positive influence on their photocatalytic activity. Based on the results of photoelectrochemistry experiment and indirect chemical probe testing, direct •O2- and hVB+ photooxidation for the decomposition of PNP or TBBPA was revealed.

  4. Synthesis of Ca P nanoparticles and fabrication of Ca P/PHBV nanocomposite microspheres for bone tissue engineering applications

    NASA Astrophysics Data System (ADS)

    Duan, B.; Wang, M.; Zhou, W. Y.; Cheung, W. L.

    2008-11-01

    As the first step in producing totally bioresorbable osteoconductive composite scaffolds for bone tissue engineering using the selective laser sintering technology, bioresorbable nanoparticles of calcium phosphate (Ca-P) similar in composition to β-tricalcium phosphate were synthesized and Ca-P nanoparticle filled poly(hydroxybutyrate- co-hydroxyvalerate) (PHBV) microspheres were fabricated. The pH of the chemical reaction for Ca-P particle synthesis was found to have significant effects on the morphology and chemical composition of Ca-P precipitated. Ca-P particles produced at the pH of 10.0-11.0 were amorphous, had a Ca:P molar ratio of about 1.5, were spherical in shape and had sizes in the range of 10-30 nm. The Ca-P particles were used to form Ca-P nanocomposite microspheres through a solid-in-oil-in-water (S/O/W) emulsion solvent evaporation process. Ca-P nanoparticles were mostly encapsulated inside the microspheres and some Ca-P nanoparticles were superficially embedded on the microspheres. The Ca-P/PHBV microspheres had an average diameter of about 48 μm which is suitable for selective laser sintering for constructing osteoconductive composite scaffolds.

  5. Biomineralized hydroxyapatite nanoclay composite scaffolds with polycaprolactone for stem cell-based bone tissue engineering.

    PubMed

    Ambre, Avinash H; Katti, Dinesh R; Katti, Kalpana S

    2015-06-01

    Nanoclay modified with unnatural amino acid was used to design a nanoclay-hydroxyapatite (HAP) hybrid by mineralizing HAP in the nanoclay galleries mimicking biomineralization. This hybrid (in situ HAPclay) was used to fabricate polycaprolactone (PCL)/in situ HAPclay films and scaffolds for bone regeneration. Cell culture assays and imaging were used to study interactions between human mesenchymal stem cells (hMSCs) and PCL/in situ HAPclay composites (films and scaffolds). SEM imaging indicated MSC attachment, formation of mineralized extracellular (ECM) on PCL/in situ HAPclay films, and infiltration of MSCs to the interior of PCL/in situ HAPclay scaffolds. Mineralized ECM was formed by MSCs without use of osteogenic supplements. AFM imaging performed on this in vitro generated mineralized ECM on PCL/in situ HAPclay films revealed presence of components (collagen and mineral) of hierarchical organization reminiscent of natural bone. Cellular events observed during two-stage seeding experiments on PCL/in situ HAPclay films indicated similarities with events occurring during in vivo bone formation. PCL/in situ HAPclay films showed significantly increased (100-595% increase in elastic moduli) nanomechanical properties and PCL/in situ HAPclay scaffolds showed increased degradation. This work puts forth PCL/in situ HAPclay composites as viable biomaterials for bone tissue engineering.

  6. Activated carbon fibers/poly(lactic-co-glycolic) acid composite scaffolds: preparation and characterizations.

    PubMed

    Shi, Yanni; Han, Hao; Quan, Haiyu; Zang, Yongju; Wang, Ning; Ren, Guizhi; Xing, Melcolm; Wu, Qilin

    2014-10-01

    The present work is a first trial to introduce activated carbon fibers (ACF) with high adsorption capacity into poly(lactic-co-glycolic) acid (PLGA), resulting in a novel kind of scaffolds for tissue engineering applications. ACF, prepared via high-temperature processing of carbon fibers, are considered to possess bioactivity and biocompatibility. The ACF/PLGA composite scaffolds are prepared by solvent casting/particulate leaching method. Increments in both pore quantity and quality over the surface of ACF as well as a robust combination between ACF and PLGA matrix are observed via scanning electron microscopy (SEM). The high adsorption capacity of ACF is confirmed by methylene blue solution absorbency test. The surfaces of ACF are affiliated with many hydrophilic groups and characterized by Fourier transform infrared spectroscopy. Furthermore, the SEM images show that cells possess a favorable spreading morphology on the ACF/PLGA scaffolds. Besides, vivo experiments are also carried out to evaluate the histocompatibility of the composite scaffolds. The results show that ACF have the potential to become one of the most promising materials in biological fields.

  7. A Hydrogel-Mineral Composite Scaffold for Osteochondral Interface Tissue Engineering

    PubMed Central

    Khanarian, Nora T.; Jiang, Jie; Wan, Leo Q.; Mow, Van C.

    2012-01-01

    Osteoarthritis is the leading cause of physical disability among Americans, and tissue engineered cartilage grafts have emerged as a promising treatment option for this debilitating condition. Currently, the formation of a stable interface between the cartilage graft and subchondral bone remains a significant challenge. This study evaluates the potential of a hybrid scaffold of hydroxyapatite (HA) and alginate hydrogel for the regeneration of the osteochondral interface. Specifically, the effects of HA on the response of chondrocytes were determined, focusing on changes in matrix production and mineralization, as well as scaffold mechanical properties over time. Additionally, the optimal chondrocyte population for interface tissue engineering was evaluated. It was observed that the HA phase of the composite scaffold promoted the formation of a proteoglycan- and type II collagen–rich matrix when seeded with deep zone chondrocytes. More importantly, the elevated biosynthesis translated into significant increases in both compressive and shear moduli relative to the mineral-free control. Presence of HA also promoted chondrocyte hypertrophy and type X collagen deposition. These results demonstrate that the hydrogel–calcium phosphate composite supported the formation of a calcified cartilage-like matrix and is a promising scaffold design for osteochondral interface tissue engineering. PMID:21919797

  8. Evaluation of bone matrix gelatin/fibrin glue and chitosan/gelatin composite scaffolds for cartilage tissue engineering.

    PubMed

    Wang, Z H; Zhang, J; Zhang, Q; Gao, Y; Yan, J; Zhao, X Y; Yang, Y Y; Kong, D M; Zhao, J; Shi, Y X; Li, X L

    2016-07-15

    This study was designed to evaluate bone matrix gelatin (BMG)/fibrin glue and chitosan/gelatin composite scaffolds for cartilage tissue engineering. Chondrocytes were isolated from costal cartilage of Sprague-Dawley rats and seeded on BMG/fibrin glue or chitosan/gelatin composite scaffolds. After different in vitro culture durations, the scaffolds were subjected to hematoxylin and eosin, Masson's trichrome, and toluidine blue staining, anti-collagen II and anti-aggrecan immunohistochemistry, and scanning electronic microscopy (SEM) analysis. After 2 weeks of culture, chondrocytes were distributed evenly on the surfaces of both scaffolds. Cell numbers and the presence of extracellular matrix components were markedly increased after 8 weeks of culture, and to a greater extent on the chitosan/gelatin scaffold. The BMG/fibrin glue scaffold showed signs of degradation after 8 weeks. Immunofluorescence analysis confirmed higher levels of collagen II and aggrecan using the chitosan/gelatin scaffold. SEM revealed that the majority of cells on the surface of the BMG/fibrin glue scaffold demonstrated a round morphology, while those in the chitosan/gelatin group had a spindle-like shape, with pseudopodia. Chitosan/gelatin scaffolds appear to be superior to BMG/ fibrin glue constructs in supporting chondrocyte attachment, proliferation, and biosynthesis of cartilaginous matrix components.

  9. 3D scaffold alters cellular response to graphene in a polymer composite for orthopedic applications.

    PubMed

    Kumar, Sachin; Azam, Dilkash; Raj, Shammy; Kolanthai, Elayaraja; Vasu, K S; Sood, A K; Chatterjee, Kaushik

    2016-05-01

    Graphene-based polymer nanocomposites are being studied for biomedical applications. Polymer nanocomposites can be processed differently to generate planar two-dimensional (2D) substrates and porous three-dimensional (3D) scaffolds. The objective of this work was to investigate potential differences in biological response to graphene in polymer composites in the form of 2D substrates and 3D scaffolds. Polycaprolactone (PCL) nanocomposites were prepared by incorporating 1% of graphene oxide (GO) and reduced graphene oxide (RGO). GO increased modulus and strength of PCL by 44 and 22% respectively, whereas RGO increased modulus and strength by 22 and 16%, respectively. RGO increased the water contact angle of PCL from 81° to 87° whereas GO decreased it to 77°. In 2D, osteoblast proliferated 15% more on GO composites than on PCL whereas RGO composite showed 17% decrease in cell proliferation, which may be attributed to differences in water wettability. In 3D, initial cell proliferation was markedly retarded in both GO (36% lower) and RGO (55% lower) composites owing to increased roughness due to the presence of the protruding nanoparticles. Cells organized into aggregates in 3D in contrast to spread and randomly distributed cells on 2D discs due to the macro-porous architecture of the scaffolds. Increased cell-cell contact and altered cellular morphology led to significantly higher mineralization in 3D. This study demonstrates that the cellular response to nanoparticles in composites can change markedly by varying the processing route and has implications for designing orthopedic implants such as resorbable fracture fixation devices and tissue scaffolds using such nanocomposites.

  10. Three-dimensionally plotted MBG/PHBHHx composite scaffold for antitubercular drug delivery and tissue regeneration.

    PubMed

    Li, Kun; Zhu, Min; Xu, Peng; Xi, Yanhai; Cheng, Zisheng; Zhu, Yufang; Ye, Xiaojian

    2015-02-01

    A suitable drug-loaded scaffold that can postoperatively release an antituberculosis drug efficiently in a lesion area and help repair a bone defect is very important in the clinical treatment of bone tuberculosis (TB). In this study, a composite drug-loaded cylindrical scaffold was prepared by using three-dimensional printing technology in combination with the mesoporous confinement range, surface chemical groups, and gradual degradation of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). This achieves the slow release of a drug for as long as possible. We implanted the drug-loaded compound scaffold into New Zealand rabbits' femur defect model to study the in vivo drug release performance and osteogenic ability. The in vivo release of isoniazid and rifampicin from the prepared composites could be effectively sustained for 12 weeks in local tissues, whereas these drugs were sustained for just 2 weeks in a control group. The blood drug concentrations were very low and most concentrations were below 5 μg/ml. Therefore, the systemic toxic adverse effect is very low. In addition, the composite exhibits good osteogenic potential in a rabbit bone defect model. The results of this study indicate that this composite has great potential for treating osteoarticular TB.

  11. Biodegradable nanofibers-reinforced microfibrous composite scaffolds for bone tissue engineering.

    PubMed

    Martins, Albino; Pinho, Elisabete D; Correlo, Vítor M; Faria, Susana; Marques, Alexandra P; Reis, Rui L; Neves, Nuno M

    2010-12-01

    Native bone extracellular matrix (ECM) is a complex hierarchical fibrous composite structure, resulting from the assembling of collagen fibrils at several length scales, ranging from the macro to the nanoscale. The combination of nanofibers within microfibers after conventional reinforcement methodologies seems to be a feasible solution to the rational design of highly functional synthetic ECM substitutes. The present work aims at the development of bone ECM inspired structures, conjugating electrospun chitosan (Cht) nanofibers within biodegradable polymeric microfibers [poly(butylene succinate)-PBS and PBS/Cht], assembled in a fiber mesh structure. The nanofibers-reinforced composite fiber mesh scaffolds were seeded with human bone marrow mesenchymal stem cells (hBMSCs) and cultured under osteogenic differentiation conditions. These nanofibers-reinforced composite scaffolds sustained ECM deposition and mineralization, mainly in the PBS/Cht-based fiber meshes, as depicted by the increased amount of calcium phosphates produced by the osteogenic differentiated hBMSCs. The osteogenic genotype of the cultured hBMSCs was confirmed by the expression of osteoblastic genes, namely Alkaline Phosphatase, Osteopontin, Bone Sialoprotein and Osteocalcin, and the transcription factors Runx2 and Osterix, all involved in different stages of the osteogenesis. These data represent the first report on the biological functionality of nanofibers-reinforced composite scaffolds, envisaging the applicability of the developed structures for bone tissue engineering.

  12. Biocompatibility Properties of Polyamide 6/ PCL Blends Composite Textile Scaffold using EA.hy926 Human Endothelial Cells.

    PubMed

    Abdal-Hay, Abdalla; Abdelrazek Khalil, Khalil; Al-Jassir, Fawzi F; Gamal-Eldeen, Amira

    2017-02-27

    Enhancing the cytocompatibility profiles including cell attachment, growth and viability of designed synthetic scaffolds have a pivotal role in tissue engineering applications. Polymer blending is one of the most effective methods for providing new desirable biomaterials for tissue scaffolds. This article reports a novel polyamide 6/ poly(Ɛ-caprolactone) (PA6/PCL) blends solution by varying the concentrations ratios of PA6 and PCL which was fabricated to create composite fibrous tissue scaffolds. Highly porous blends fibrous scaffold has been fabricated and their suitability as cell-support for EA.hy926 human endothelial cells has been studied. Our results demonstrated that the unique nanoscale morphological properties and tune porosity of the blends scaffold were controlled. We found that these properties are mainly depending on the PA6/PCL blending viscosity value, and the viscosity of the blending solution has an intense effect on the properties of the blends scaffold. The influence of the scaffolds extraction fluids and the scaffold direct contact of both of the metabolic viability and the DNA integrity of EA.hy926 endothelial cells as well as the cell/ scaffold interaction analysis by Scanning Electron Microscope, after different co-culturing intervals, demonstrated that PA6/PCL blend scaffolds showed different behavior. Blend scaffolds of PA6/PCL of 90:10 ratio proved to be excellent endothelial cell carrier, which provided a good cell morphology, DNA integrity and viability, induced DNA synthesis/replication, and enhanced cell proliferation, attachment, and invasion. These results indicate that blends of PA6/PCL composite fibers is a promising 3D substitute for the next generation of synthetic tissue scaffold that could soon find clinical applications.

  13. Hypoxia-mimicking bioactive glass/collagen glycosaminoglycan composite scaffolds to enhance angiogenesis and bone repair.

    PubMed

    Quinlan, Elaine; Partap, Sonia; Azevedo, Maria M; Jell, Gavin; Stevens, Molly M; O'Brien, Fergal J

    2015-06-01

    One of the biggest challenges in regenerative medicine is promoting sufficient vascularisation of tissue-engineered constructs. One approach to overcome this challenge is to target the cellular hypoxia inducible factor (HIF-1α) pathway, which responds to low oxygen concentration (hypoxia) and results in the activation of numerous pro-angiogenic genes including vascular endothelial growth factor (VEGF). Cobalt ions are known to mimic hypoxia by artificially stabilising the HIF-1α transcription factor. Here, resorbable bioactive glass particles (38 μm and 100 μm) with cobalt ions incorporated into the glass network were used to create bioactive glass/collagen-glycosaminoglycan scaffolds optimised for bone tissue engineering. Inclusion of the bioactive glass improved the compressive modulus of the resulting composite scaffolds while maintaining high degrees of porosity (>97%). Moreover, in vitro analysis demonstrated that the incorporation of cobalt bioactive glass with a mean particle size of 100 μm significantly enhanced the production and expression of VEGF in endothelial cells, and cobalt bioactive glass/collagen-glycosaminoglycan scaffold conditioned media also promoted enhanced tubule formation. Furthermore, our results prove the ability of these scaffolds to support osteoblast cell proliferation and osteogenesis in all bioactive glass/collagen-glycosaminoglycan scaffolds irrespective of the particle size. In summary, we have developed a hypoxia-mimicking tissue-engineered scaffold with pro-angiogenic and pro-osteogenic capabilities that may encourage bone tissue regeneration and overcome the problem of inadequate vascularisation of grafts commonly seen in the field of tissue engineering.

  14. Porous CaP/silk composite scaffolds to repair femur defects in an osteoporotic model.

    PubMed

    Cheng, Ning; Dai, Jing; Cheng, Xiangrong; Li, Shu'e; Miron, Richard J; Wu, Tao; Chen, Wenli; Zhang, Yufeng; Shi, Bin

    2013-08-01

    The most common complication for patients with postmenopausal osteoporosis is bone-related defects and fractures. While routine medication has a high probability of undesirable side effects, new approaches have aimed to develop regeneration procedures that stimulate new bone formation while reversing bone loss. Recently, we have synthesized a new hybrid CaP/silk scaffold with a CaP-phase distribution and pore architecture better suited to facilitate cell differentiation and bone formation. The aim of the present study was to compare the involved remodeling process and therapeutic effect of porous CaP/silk composite scaffolds upon local implantation into osteoporotic defects. Wistar rats were used to induce postmenopausal osteoporotic model by bilateral ovariectomy. The pure silk and hybrid CaP/silk scaffolds were implanted into critical sized defects created in distal femoral epiphysis. After 14 and 28 days, the in vivo osteogenetic efficiency was evaluated by μCT analysis, hematoxylin and eosin staining, Safranin O staining, tartrate-resistant acid phosphatase staining, and immunohistochemical assessment. Animals with or without critical-sized defects were used as drill or blank controls, respectively. The osteoporotic defect model was well established with significantly decreased μCT parameters of BV/TV, Tb.N and increased Tb.Sp, porosity, combined with changes in histological observations. During the healing process, the critical-sized drill control defects failed to regenerate appreciable bone tissue, while more significantly increased bone formation and mineralization with dynamic scaffold degradation and decreased osteoclastic bone resorption could be detected within defects with hybrid CaP/silk scaffolds compared to pure silk scaffolds.

  15. Needle-like ion-doped hydroxyapatite crystals influence osteogenic properties of PCL composite scaffolds.

    PubMed

    Guarino, V; Veronesi, F; Marrese, M; Giavaresi, G; Ronca, A; Sandri, M; Tampieri, A; Fini, M; Ambrosio, Luigi

    2016-02-29

    Surface topography and chemistry both play a crucial role on influencing cell response in 3D porous scaffolds in terms of osteogenesis. Inorganic materials with peculiar morphology and chemical functionalities may be proficiently used to improve scaffold properties-in the bulk and along pore surface-promoting in vitro and in vivo osseous tissue in-growth. The present study is aimed at investigating how bone regenerative properties of composite scaffolds made of poly(Ɛ-caprolactone) (PCL) can be augmented by the peculiar properties of Mg(2+) ion doped hydroxyapatite (dHA) crystals, mainly emphasizing the role of crystal shape on cell activities mediated by microstructural properties. At the first stage, the study of mechanical response by crossing experimental compression tests and theoretical simulation via empirical models, allow recognizing a significant contribution of dHA shape factor on scaffold elastic moduli variation as a function of the relative volume fraction. Secondly, the peculiar needle-like shape of dHA crystals also influences microscopic (i.e. crystallinity, adhesion forces) and macroscopic (i.e. roughness) properties with relevant effects on biological response of the composite scaffold: differential scanning calorimetry (DSC) analyses clearly indicate a reduction of crystallization heat-from 66.75 to 43.05 J g(-1)-while atomic force microscopy (AFM) ones show a significant increase of roughness-from (78.15  ±  32.71) to (136.13  ±  63.21) nm-and of pull-off forces-from 33.7% to 48.7%. Accordingly, experimental studies with MG-63 osteoblast-like cells show a more efficient in vitro secretion of alkaline phosphatase (ALP) and collagen I and a more copious in vivo formation of new bone trabeculae, thus suggesting a relevant role of dHA to support the main mechanisms involved in bone regeneration.

  16. Culturing primary human osteoblasts on electrospun poly(lactic-co-glycolic acid) and poly(lactic-co-glycolic acid)/nanohydroxyapatite scaffolds for bone tissue engineering.

    PubMed

    Li, Mengmeng; Liu, Wenwen; Sun, Jiashu; Xianyu, Yunlei; Wang, Jidong; Zhang, Wei; Zheng, Wenfu; Huang, Deyong; Di, Shiyu; Long, Yun-Ze; Jiang, Xingyu

    2013-07-10

    In this work, we fabricated polymeric fibrous scaffolds for bone tissue engineering using primary human osteoblasts (HOB) as the model cell. By employing one simple approach, electrospinning, we produced poly(lactic-co-glycolic acid) (PLGA) scaffolds with different topographies including microspheres, beaded fibers, and uniform fibers, as well as the PLGA/nanohydroxyapatite (nano-HA) composite scaffold. The bone-bonding ability of electrospun scaffolds was investigated by using simulated body fluid (SBF) solution, and the nano-HA in PLGA/nano-HA composite scaffold can significantly enhance the formation of the bonelike apatites. Furthermore, we carried out in vitro experiments to test the performance of electrospun scaffolds by utilizing both mouse preosteoblast cell line (MC 3T3 E1) and HOB. Results including cell viability, alkaline phosphatase (ALP) activity, and osteocalcin concentration demonstrated that the PLGA/nano-HA fibers can promote the proliferation of HOB efficiently, indicating that it is a promising scaffold for human bone repair.

  17. Simultaneous removal of acid green 25 and mercury ions from aqueous solutions using glutamine modified chitosan magnetic composite microspheres.

    PubMed

    Tao, Xue; Li, Kun; Yan, Han; Yang, Hu; Li, Aimin

    2016-02-01

    In this current work, the magnetic composite microsphere containing glutamine modified chitosan and silica coated Fe3O4 nanoparticles (CS-Gln-MCM) has been successfully prepared and extensively characterized, which is a kind of biodegradable materials. CS-Gln-MCM shows enhanced removal efficiency for both acid green 25 (AG25), an amphoteric dye, and mercury ions (Hg(2+)) from water in the respective while measured pH range compared with chitosan magnetic composite microsphere (CS-MCM) without modification. It is due to the fact that the grafted amino acid provides a variety of additional adsorption active sites and diverse adsorption mechanisms are involved. In AG25 and Hg(2+) aqueous mixture, the modified adsorbents bear preferential adsorption for AG25 over Hg(2+) in strong acidic solutions ascribed to multiple interactions between AG25 and CS-Gln-MCM, such as hydrogen bonding and electrostatic interactions. While, in weak acidic conditions, an efficient simultaneous removal is observed for different adsorption effects involved in aforementioned two pollutants. Besides, CS-Gln-MCM illuminates not only short equilibrium time for adsorption of each pollutant less than 20.0 min but also rapid magnetic separation from water and efficient regeneration after saturated adsorption. Therefore, CS-Gln-MCM bears great application potentials in water treatment.

  18. 3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration.

    PubMed

    Inzana, Jason A; Olvera, Diana; Fuller, Seth M; Kelly, James P; Graeve, Olivia A; Schwarz, Edward M; Kates, Stephen L; Awad, Hani A

    2014-04-01

    Low temperature 3D printing of calcium phosphate scaffolds holds great promise for fabricating synthetic bone graft substitutes with enhanced performance over traditional techniques. Many design parameters, such as the binder solution properties, have yet to be optimized to ensure maximal biocompatibility and osteoconductivity with sufficient mechanical properties. This study tailored the phosphoric acid-based binder solution concentration to 8.75 wt% to maximize cytocompatibility and mechanical strength, with a supplementation of Tween 80 to improve printing. To further enhance the formulation, collagen was dissolved into the binder solution to fabricate collagen-calcium phosphate composites. Reducing the viscosity and surface tension through a physiologic heat treatment and Tween 80, respectively, enabled reliable thermal inkjet printing of the collagen solutions. Supplementing the binder solution with 1-2 wt% collagen significantly improved maximum flexural strength and cell viability. To assess the bone healing performance, we implanted 3D printed scaffolds into a critically sized murine femoral defect for 9 weeks. The implants were confirmed to be osteoconductive, with new bone growth incorporating the degrading scaffold materials. In conclusion, this study demonstrates optimization of material parameters for 3D printed calcium phosphate scaffolds and enhancement of material properties by volumetric collagen incorporation via inkjet printing.

  19. 3D Printing of Composite Calcium Phosphate and Collagen Scaffolds for Bone Regeneration

    PubMed Central

    Inzana, Jason A.; Olvera, Diana; Fuller, Seth M.; Kelly, James P.; Graeve, Olivia A.; Schwarz, Edward M.; Kates, Stephen L.; Awad, Hani A.

    2014-01-01

    Low temperature 3D printing of calcium phosphate scaffolds holds great promise for fabricating synthetic bone graft substitutes with enhanced performance over traditional techniques. Many design parameters, such as the binder solution properties, have yet to be optimized to ensure maximal biocompatibility and osteoconductivity with sufficient mechanical properties. This study tailored the phosphoric acid-based binder solution concentration to 8.75 wt% to maximize cytocompatibility and mechanical strength, with a supplementation of Tween 80 to improve printing. To further enhance the formulation, collagen was dissolved into the binder solution to fabricate collagen-calcium phosphate composites. Reducing the viscosity and surface tension through a physiologic heat treatment and Tween 80, respectively, enabled reliable thermal inkjet printing of the collagen solutions. Supplementing the binder solution with 1–2 wt% collagen significantly improved maximum flexural strength and cell viability. To assess the bone healing performance, we implanted 3D printed scaffolds into a critically sized murine femoral defect for 9 weeks. The implants were confirmed to be osteoconductive, with new bone growth incorporating the degrading scaffold materials. In conclusion, this study demonstrates optimization of material parameters for 3D printed calcium phosphate scaffolds and enhancement of material properties by volumetric collagen incorporation via inkjet printing. PMID:24529628

  20. Quercetin impregnated chitosan-fibrin composite scaffolds as potential wound dressing materials - Fabrication, characterization and in vivo analysis.

    PubMed

    Vedakumari, Weslen S; Ayaz, Nazeeha; Karthick, Arun S; Senthil, Rethinam; Sastry, Thotapalli P

    2017-01-15

    The present study efforts at fabricating chitosan-fibrin composite (CF) scaffolds impregnated with quercetin for wound dressing application and aims at investigating their physicochemical properties. CF scaffolds were prepared by mixing acidic solution of chitosan with an alkaline solution of fibrin, to which quercetin (Q) was added, homogenized and lyophilized obtain Q-CF scaffold. FTIR spectra were used to determine the interactions between the functional groups of quercetin and CF scaffolds. TGA analysis revealed the decomposition of saccharide rings and amino acids of chitosan and fibrin at the temperature range of 255-400°C. Q-CF scaffold exhibited maximum tensile strength of 1.45MPa, an ideal mechanical strength for a wound dressing material. Q-CF scaffolds exhibited good bactericidal activity against Escherichia coli and Staphylococcus aureus. Biocompatibility of Q-CF scaffold was assessed using MTT assay, which elucidated its non-toxic property and excellent suitability for tissue engineering applications. In vivo wound healing experiments performed using albino rats revealed that topical application of Q-CF scaffold on open excision type of wounds can significantly accelerate the process of wound healing. These results suggest that Q-CF scaffold could serve as a promising wound dressing material.

  1. [Strategies to choose scaffold materials for tissue engineering].

    PubMed

    Gao, Qingdong; Zhu, Xulong; Xiang, Junxi; Lü, Yi; Li, Jianhui

    2016-02-01

    Current therapies of organ failure or a wide range of tissue defect are often not ideal. Transplantation is the only effective way for long time survival. But it is hard to meet huge patients demands because of donor shortage, immune rejection and other problems. Tissue engineering could be a potential option. Choosing a suitable scaffold material is an essential part of it. According to different sources, tissue engineering scaffold materials could be divided into three types which are natural and its modified materials, artificial and composite ones. The purpose of tissue engineering scaffold is to repair the tissues or organs damage, so could reach the ideal recovery in its function and structure aspect. Therefore, tissue engineering scaffold should even be as close as much to the original tissue or organs in function and structure. We call it "organic scaffold" and this strategy might be the drastic perfect substitute for the tissues or organs in concern. Optimized organization with each kind scaffold materials could make up for biomimetic structure and function of the tissue or organs. Scaffold material surface modification, optimized preparation procedure and cytosine sustained-release microsphere addition should be considered together. This strategy is expected to open new perspectives for tissue engineering. Multidisciplinary approach including material science, molecular biology, and engineering might find the most ideal tissue engineering scaffold. Using the strategy of drawing on each other strength and optimized organization with each kind scaffold material to prepare a multifunctional biomimetic tissue engineering scaffold might be a good method for choosing tissue engineering scaffold materials. Our research group had differentiated bone marrow mesenchymal stem cells into bile canaliculi like cells. We prepared poly(L-lactic acid)/poly(ε-caprolactone) biliary stent. The scaffold's internal played a part in the long-term release of cytokines which

  2. Comparison between PCL/hydroxyapatite (HA) and PCL/halloysite nanotube (HNT) composite scaffolds prepared by co-extrusion and gas foaming.

    PubMed

    Jing, Xin; Mi, Hao-Yang; Turng, Lih-Sheng

    2017-03-01

    In this work, three-dimensional poly(caprolactone) (PCL) tissue engineering scaffolds were prepared by co-extrusion and gas foaming. Biocompatible hydroxyapatite (HA) and halloysite nanotubes (HNT) were added to the polymer matrix to enhance the mechanical properties and bioactivity of the composite scaffolds. The effects of HA and HNT on the rheological behavior, microstructure, and mechanical properties of the composite scaffolds were systematically compared. It was found that the HNT improved viscosity more significantly than HA, and reduced the pore size of scaffolds, while the mechanical performance of PCL/HNT scaffolds was higher than PCL/HA scaffolds with the same filler content. Human mesenchymal stem cells (hMSCs) were used as the cell model to compare the biological properties of two composite scaffolds. The results demonstrated that cells could survive on all scaffolds, and showed a more flourishing living state on the composite scaffolds. The cell differentiation for 5% HA and 1% HNT scaffolds were significantly higher than other scaffolds, while the differentiation of 5% HNT scaffolds was lower than that of 1% HNT scaffolds mainly because of the reduced pore size and pore interconnectivity. Therefore, this study suggested that, with proper filler content and control of microstructure through processing, HNT could be a suitable substitute for HA for bone tissue engineering to reduce the cost and improve mechanical performance.

  3. IMPACT OF COMPOSITION AND HEAT TREATMENT ON PORE SIZE IN POROUS WALLED HOLLOW GLASS MICROSPHERES

    SciTech Connect

    Raszewski, F; Erich Hansen, E; Ray Schumacher, R; David Peeler, D

    2007-12-04

    The Savannah River National Laboratory (SRNL) developed a new geometric form: hollow glass microspheres (HGMs), with unique porous walls. The new geometric form combines the existing technology of HGMs with basic glass science knowledge in the realm of glass-in-glass phase separation. Conceptually, the development of a HGM with porous walls (referred to as a PWHGM) provides a unique system in which various media or filling agents can be incorporated into the PWHGM (via transport through the porous walls) and ultimately has the capacity to serve as a functional delivery system in various industrial applications. Applications of these types of systems could range from hydrogen storage, molecular sieves, drug and bioactive delivery systems, to environmental, chemical and biological indicators, relevant to Energy, Environmental Processing and Homeland Security fields. As a specific example, previous studies at SRNL have introduced materials capable of hydrogen storage (as well as other materials) into the interior of the PWHGMs. The goal of this project was to determine if the microstructure (i.e., pore size and pore size distribution) of a PWHGM could be altered or tailored by varying composition and/or heat treatment (time and/or temperature) conditions. The ability to tailor the microstructure through composition or heat treatments could provide the opportunity to design the PWHGM system to accommodate different additives or fill agents. To meet this objective, HGMs of various alkali borosilicate compositions were fabricated using a flame forming apparatus installed at the Aiken County Technical Laboratory (ACTL). HGMs were treated under various heat treatment conditions to induce and/or enhance glass in glass phase separation. Heat treatment temperatures ranged from 580 C to 620 C, while heat treatment times were either 8 or 24 hours. Of the two primary variables assessed in this study, heat treatment temperature was determined to be most effective in changing the

  4. [Research progress on application of carbon nanotubes in bone tissue engineering scaffold].

    PubMed

    Yao, Mengzhu; Sheng, Xiaoxia; Lin, Jun; Gao, Jianqing

    2016-03-01

    Carbon nanotubes possess excellent mechanical and electrical properties and demonstrate broad application prospects in medical fields. Carbon nanotubes are composed of inorganic materials, natural biodegradable polymer or synthetic biodegradable polymer. The composite bone tissue engineering scaffolds are constructed by particle-hole method, lyophilization, microsphere aggregation method, electrostatic spinning or three-dimensional printing. Composite scaffolds overcome the shortcomings of single material and have good biocompatibility, osteoconduction and osteoinduction. With the study of surface chemistry, toxicology, and biocompatibility, a degradable "human-friendly" carbon nanotubes composite bone tissue scaffold will be available; and under the drive of new fabrication techniques, the clinical application of carbon nanotubes composite bone tissue engineering scaffolds will be better developed.

  5. Covalent and injectable chitosan-chondroitin sulfate hydrogels embedded with chitosan microspheres for drug delivery and tissue engineering.

    PubMed

    Fan, Ming; Ma, Ye; Tan, Huaping; Jia, Yang; Zou, Siyue; Guo, Shuxuan; Zhao, Meng; Huang, Hao; Ling, Zhonghua; Chen, Yong; Hu, Xiaohong

    2017-02-01

    Injectable hydrogels and microspheres derived from natural polysaccharides have been extensively investigated as drug delivery systems and cell scaffolds. In this study, we report a preparation of covalent hydrogels basing polysaccharides via the Schiff' base reaction. Water soluble carboxymethyl chitosan (CMC) and oxidized chondroitin sulfate (OCS) were prepared for cross-linking of hydrogels. The mechanism of cross-linking is attributed to the Schiff' base reaction between amino and aldehyde groups of polysaccharides. Furthermore, bovine serum albumin (BSA) loaded chitosan-based microspheres (CMs) with a diameter of 3.8-61.6μm were fabricated by an emulsion cross-linking method, followed by embedding into CMC-OCS hydrogels to produce a composite CMs/gel scaffold. In the current work, gelation rate, morphology, mechanical properties, swelling ratio, in vitro degradation and BSA release of the CMs/gel scaffolds were examined. The results show that mechanical and bioactive properties of gel scaffolds can be significantly improved by embedding CMs. The solid CMs can serve as a filler to toughen the soft CMC-OCS hydrogels. Compressive modulus of composite gel scaffolds containing 20mg/ml of microspheres was 13KPa, which was higher than the control hydrogel without CMs. Cumulative release of BSA during 2weeks from CMs embedded hydrogel was 30%, which was significantly lower than those of CMs and hydrogels. Moreover, the composite CMs/gel scaffolds exhibited lower swelling ratio and slower degradation rate than the control hydrogel without CMs. The potential of the composite hydrogel as an injectable scaffold was demonstrated by encapsulation of bovine articular chondrocytes in vitro. These results demonstrate the potential of CMs embedded CMC-OCS hydrogels as an injectable drug and cell delivery system in cartilage tissue engineering.

  6. Nanofiber-microsphere (nano-micro) matrices for bone regenerative engineering: a convergence approach toward matrix design.

    PubMed

    Nelson, Clarke; Khan, Yusuf; Laurencin, Cato T

    2014-11-01

    Bone is an essential organ for health and quality of life. Due to current shortfalls in therapy for bone tissue engineering, scientists have sought the application of synthetic materials as bone graft substitutes. As a composite organic/inorganic material with significant extra cellular matrix (ECM), one way to improve bone graft substitutes may be to engineer a synthetic matrix that is influenced by the physical appearance of natural ECM networks. In this work, the authors evaluate composite, hybrid scaffolds for bone tissue engineering based on composite ceramic/polymer microsphere scaffolds with synthetic ECM-mimetic networks in their pore spaces. Using thermally induced phase separation, nanoscale fibers were deposited in the pore spaces of structurally sound microsphere-based scaffold with a density proportionate to the initial polymer concentration. Porosimetry and mechanical testing indicated no significant changes in overall pore characteristics or mechanical integrity as a result of the fiber deposition process. These scaffolds displayed adequate mechanical integrity on the scale of human trabecular bone and supported the adhesion and proliferation of cultured mouse calvarial osteoblasts. Drawing from natural cues, these scaffolds may represent a new avenue forward for advanced bone tissue engineering scaffolds.

  7. The evaluation of physical properties and in vitro cell behavior of PHB/PCL/sol-gel derived silica hybrid scaffolds and PHB/PCL/fumed silica composite scaffolds.

    PubMed

    Ding, Yaping; Yao, Qingqing; Li, Wei; Schubert, Dirk W; Boccaccini, Aldo R; Roether, Judith A

    2015-12-01

    PHB/PCL/sol-gel derived silica hybrid scaffolds (P5S1S) and PHB/PCL/fumed silica composite scaffolds (P5S1N) with a 5:1 organic/inorganic ratio were fabricated through a combination of electrospinning and sol-gel methods and dispersion electrospinning, respectively. In contrast to the silica nanoparticle aggregates appearing on the fiber surface of P5S1N, smooth and uniform fibers were obtained for P5S1S. The fiber diameter distribution, tensile strength, thermal gravimetric analysis (TGA), and cellular behavior of both types of scaffolds were characterized and studied. The tensile strength results and TGA indicated that the interfacial interaction between the organic and the inorganic phase was enhanced in P5S1S over the nanocomposite scaffolds, and cells exhibited significantly higher alkaline phosphate activity (ALP) for P5S1S, which makes P5S1S hybrid scaffolds candidate materials for bone tissue engineering applications.

  8. Hydroxyapatite reinforced collagen scaffolds with improved architecture and mechanical properties.

    PubMed

    Kane, Robert J; Weiss-Bilka, Holly E; Meagher, Matthew J; Liu, Yongxing; Gargac, Joshua A; Niebur, Glen L; Wagner, Diane R; Roeder, Ryan K

    2015-04-01

    Hydroxyapatite (HA) reinforced collagen scaffolds have shown promise for synthetic bone graft substitutes and tissue engineering scaffolds. Freeze-dried HA-collagen scaffolds are readily fabricated and have exhibited osteogenicity in vivo, but are limited by an inherent scaffold architecture that results in a relatively small pore size and weak mechanical properties. In order to overcome these limitations, HA-collagen scaffolds were prepared by compression molding HA reinforcements and paraffin microspheres within a suspension of concentrated collagen fibrils (∼ 180 mg/mL), cross-linking the collagen matrix, and leaching the paraffin porogen. HA-collagen scaffolds exhibited an architecture with high porosity (85-90%), interconnected pores ∼ 300-400 μm in size, and struts ∼ 3-100 μm in thickness containing 0-80 vol% HA whisker or powder reinforcements. HA reinforcement enabled a compressive modulus of up to ∼ 1 MPa, which was an order of magnitude greater than unreinforced collagen scaffolds. The compressive modulus was also at least one order of magnitude greater than comparable freeze-dried HA-collagen scaffolds and two orders of magnitude greater than absorbable collagen sponges used clinically. Moreover, scaffolds reinforced with up to 60 vol% HA exhibited fully recoverable elastic deformation upon loading to 50% compressive strain for at least 100,000 cycles. Thus, the scaffold mechanical properties were well-suited for surgical handling, fixation, and bearing osteogenic loads during bone regeneration. The scaffold architecture, permeability, and composition were shown to be conducive to the infiltration and differentiation of adipose-derive stromal cells in vitro. Acellular scaffolds were demonstrated to induce angiogenesis and osteogenesis after subcutaneous ectopic implantation by recruiting endogenous cell populations, suggesting that the scaffolds were osteoinductive.

  9. Demagnetization Treatment of Remanent Composite Microspheres Studied by Alternating Current Susceptibility Measurements

    PubMed Central

    van Berkum, Susanne; Erné, Ben H.

    2013-01-01

    The magnetic remanence of silica microspheres with a low concentration of embedded cobalt ferrite nanoparticles is studied after demagnetization and remagnetization treatments. When the microspheres are dispersed in a liquid, alternating current (AC) magnetic susceptibility spectra reveal a constant characteristic frequency, corresponding to the rotational diffusion of the microparticles; this depends only on particle size and liquid viscosity, making the particles suitable as a rheological probe and indicating that interactions between the microspheres are weak. On the macroscopic scale, a sample with the dry microparticles is magnetically remanent after treatment in a saturating field, and after a demagnetization treatment, the remanence goes down to zero. The AC susceptibility of a liquid dispersion, however, characterizes the remanence on the scale of the individual microparticles, which does not become zero after demagnetization. The reason is that an individual microparticle contains only a relatively small number of magnetic units, so that even if they can be reoriented magnetically at random, the average vector sum of the nanoparticle dipoles is not negligible on the scale of the microparticle. In contrast, on the macroscopic scale, the demagnetization procedure randomizes the orientations of a macroscopic number of magnetic units, resulting in a remanent magnetization that is negligible compared to the saturation magnetization of the entire sample. PMID:24009021

  10. Fabrication and Cell Responsive Behavior of Macroporous PLLA/Gelatin Composite Scaffold with Hierarchical Micro-Nano Pore Structure

    PubMed Central

    Song, Kedong; Ji, Lili; Zhang, Jingying; Wang, Hai; Jiao, Zeren; Mayasari, Lim; Fu, Xiaoyan; Liu, Tianqing

    2015-01-01

    Scaffolds providing a 3D environment which can effectively promote the adhesion, proliferation and differentiation of cells are crucial to tissue regeneration. In this study, the polyllactic acid (PLLA) scaffold with hierarchical pore structural was fabricated via two-step thermally induced phase separation (TIPS). To mimic both physical architecture and chemical composite of natural bone extracellular matrix (ECM), gelatin fibers were introduced into the pores of PLLA scaffolds and formed 3D network structure via TIPS. Human adipose tissue-derived stem cells (ADSCs) were harvested and seeded into PLLA/gel hybrid scaffolds and cultured in vitro for biocompatibility assay. The surface morphology, porosity and compressive modulus of scaffolds were characterized by scanning electron microscopy (SEM), density analysis and compression test respectively. The results showed that hybrid scaffolds had high porosity (91.62%), a good compressive modulus (2.79 ± 0.20 MPa), nanometer fibers (diameter around 186.39~354.30 nm) and different grades of pore size from 7.41 ± 2.64 nm to 387.94 ± 102.48 nm. The scaffolds with mild hydrolysis by NaOH were modified by 1-ethyl-3-(3-dimethyl ami-nopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS). Gelatin was performed onto PLLA scaffold via TIPS aiming at enhancement cell-material interaction. In comparison with PLLA scaffold, the PLLA/gel scaffold had better biological performance and the mechanical properties because the gelatin fibers homogeneously distributed in each pore of PLLA scaffold and formed 3D network structure.

  11. 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.

  12. Effects of proliferation and differentiation of mesenchymal stem cells on compressive mechanical behavior of collagen/β-TCP composite scaffold.

    PubMed

    Arahira, Takaaki; Todo, Mitsugu

    2014-11-01

    The primary aim of this study is to characterize the effects of cell culture on the compressive mechanical behavior of the collagen/β-tricalcium phosphate (TCP) composite scaffold. The composite and pure collagen scaffolds were fabricated by the solid-liquid phase separation technique and the subsequent freeze-drying method. Rat bone marrow mesenchymal stem cells (rMSCs) were then cultured in these scaffolds up to 28 days. Compression test of the scaffolds with rMSCs were conducted periodically. Biological properties such as cell number, alkaline phosphatase (ALP) activity, and gene expressions of osteogenetic bone markers were evaluated during cell culture. The microstructural changes in the scaffolds during cell culture were also examined using a scanning electron microscope. The compressive elastic modulus was then correlated with those of the biological properties and microstructures to understand the mechanism of variational behavior of the macroscopic elastic property. The composite scaffold exhibited higher ALP activity and more active generation of osteoblastic markers than the collagen scaffold, indicating that β-TCP can activate the differentiation of rMSCs into osteoblasts and extracellular matrix (ECM) formation such as type I collagen and the following mineralization. The variational behavior of the compressive modulus of the composite scaffold was affected by both the material degradation and the proliferation of cells and the ECM formation. In the first stage, the modulus of the composite scaffold tended to increase due to cell proliferation and the following formation of network structure. In the second stage, the modulus tended to decrease because the material degradation such as ductile deformation of collagen and decomposition of β-TCP were more effective on the property than the ECM formation. In the third stage, active calcification by formation and growth of mineralized nodules resulted in the recovery of modulus. It is concluded that the

  13. In vitro bone formation by mesenchymal stem cells with 3D collagen/β-TCP composite scaffold.

    PubMed

    Todo, Mitsugu; Arahira, Takaaki

    2013-01-01

    Recent years, various kinds of natural polymers and bioceramics has been used to develop porous scaffolds for bone tissue engineering. Among of them, collagen guarantees good biological conditions, and β-tricalcium phosphate (β-TCP) possesses good oseteoconductivity, cellular adhesion, accelerated differentiation and mechanical property. In this study, rat bone marrow mesenchymal stem cells (rMSC) were cultured in β-TCP/collagen composite scaffolds up to 28 days in order to assess the time-dependent behavior of the extracellular matrix formation and the mechanical performance of the scaffold-cell system. The cell number and ALP activity were evaluated using a spectrophotometric plate reader. Gene expression of osteogenesis was analyzed using the real-time PCR reactions. Compression tests were also conducted periodically by using a conventional testing machine to evaluate the elastic modulus. The increasing behaviors of cell number and ALP activity in the composite scaffold were much better than in the collagen scaffold. The gene expression of osteocalcin and collagen type-I in collagen/β-TCP scaffold was higher than that of the collagen scaffold. The compressive modulus also increased up to 28 days. These results clearly showed that the distribution of micro β-TCP particles is very effective to increase the elastic modulus and promote cell growth.

  14. Synthesis and drug-loading properties of folic acid-modified superparamagnetic Fe3O4 hollow microsphere core/mesoporous SiO2 shell composite particles

    NASA Astrophysics Data System (ADS)

    Yang, Yong; Guo, Xue; Wei, Kaiwei; Wang, Lijuan; Yang, Dandan; Lai, Lifang; Cheng, Meiling; Liu, Qi

    2014-01-01

    A drug delivery system, which not only has superparamagnetic property, higher surface area but also has targeting function, has been developed. The core/shell structural magnetic magnetite mesoporous silica microspheres with amine groups (Fe3O4-SiO2-NH2) were first fabricated by a one-pot direct co-condensation method, then folic acid-modified magnetic mesoporous silica composite microspheres (Fe3O4-SiO2-NHFA) were obtained by the bonding of the Fe3O4-SiO2-NH2 with folic acid as targeted molecule. The resultant composite microspheres were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, low temperature nitrogen adsorption-desorption, and vibrating sample magnetometer. A well-known inflammational drug ibuprofen was used as a model drug to assess the loading and releasing behavior of the composite microspheres. Fe3O4-SiO2-NHFA system exhibits magnetic properties typical for superparamagnetic material with a higher saturation magnetization value of about 41.2 emu/g and has better capacity of drug storage (32.0 %) and sustained drug-release property. So this system has potential applications in biomedical field.

  15. Structural modification and characterization of bacterial cellulose-alginate composite scaffolds for tissue engineering.

    PubMed

    Kirdponpattara, Suchata; Khamkeaw, Arnon; Sanchavanakit, Neeracha; Pavasant, Prasit; Phisalaphong, Muenduen

    2015-11-05

    A novel bacterial cellulose-alginate composite scaffold (N-BCA) was fabricated by freeze drying and subsequent crosslinking with Ca(2+). The N-BCA then underwent a second freeze drying step to remove water without altering the physical structure. A stable structure of N-BCA with open and highly interconnected pores in the range of 90-160 μm was constructed. The N-BCA was stable in both water and PBS. The swelling ability of N-BCA in water was approximately 50 times its weight, which was about 6.5 times that of the freeze dried bacterial cellulose pellicles. N-BCA demonstrated no cytotoxicity against L929 mouse fibroblast cells. For long-term culture, N-BCA supported attachment, spreading, and proliferation of human gingival fibroblast (GF) on the surface. However, under static conditions, the cell migration and growth inside the scaffold were limited. Because of its biocompatibility and open macroporous structure, N-BCA could potentially be used as a scaffold for tissue engineering.

  16. Dexamethasone-loaded poly(D, L-lactic acid) microspheres/poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) micelles composite for skin augmentation.

    PubMed

    Fan, Min; Liao, Jinfeng; Guo, Gang; Ding, Qiuxia; Yang, Yi; Luo, Feng; Qian, Zhiyong

    2014-04-01

    Soft tissue augmentation using various injectable fillers has gained popularity as more patients seek esthetic improvement through minimally invasive procedures requiring little or no recovery time. The currently available injectable skin fillers can be divided into three categories. With careful assessment, stimulatory fillers are the most ideal fillers. In this study, dexamethasone-loaded poly(D, L-lactic acid) (PLA) microspheres of approximately 90 micro m suspended in poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) micelles were prepared as stimulatory filler for skin augmentation. The biodegradable PECE copolymer can form nano-sized micelles in water, which instantly turns into a non-flowing gel at body temperature due to micellar aggregation. The PECE micelles (making up 90% of composite) served as vehicle for subcutaneous injection were metabolized within 44 days. At the same time, the dexamethasone-loaded PLA microspheres (10% of composite) merely served as stimulus for connective tissue formation. Dexamethasone-loaded PLA microspheres/PECE micelles composite presented great hemocompatibility in vitro. It was demonstrated in the in vive study that the composite was biodegradable, biocompatible, nontoxic and nonmigratory. Histopathological studies indicated that the composite could stimulate collagen regeneration. Furthermore, granuloma, the main complication of the stimulatory fillers, did not appear when the composite was injected into the back of SD rats, because of the dexamethasone controlled release from the composite. All results suggested that dexamethasone-loaded PLA microspheres/PECE micelles composite may be an efficient and promising biomaterial for skin augmentation.

  17. Halloysite nanotube supported Ag nanoparticles heteroarchitectures as catalysts for polymerization of alkylsilanes to superhydrophobic silanol/siloxane composite microspheres.

    PubMed

    Li, Cuiping; Li, Xueyuan; Duan, Xuelan; Li, Guangjie; Wang, Jiaqiang

    2014-12-15

    Halloysite nanotube supported Ag nanoparticles heteroarchitectures have been prepared through a very simple electroless plating method. Robust Ag nanocrystals can be reproducibly fabricated by soaking halloysite nanotubes in ethanolic solutions of AgNO3 and butylamine. By simply adjusting the molar ratio of AgNO3 and butylamine, Ag nanoparticles with tunable size and quantity on halloysite nanotube are achieved. It reveals that the Ag nanoparticles are well-dispersed on the surface of halloysite nanotubes. The halloysite nanotube supported Ag nanoparticles heteroarchitectures can serve as active catalysts for the polymerization of an alkylsilane C18H37SiH3 with water to form silanol/siloxane composite microspheres and exhibit interesting superhydrophobicity ascribed to the micro/nanobinary structure.

  18. 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

  19. Composite pullulan-dextran polysaccharide scaffold with interfacial polyelectrolyte complexation fibers: a platform with enhanced cell interaction and spatial distribution.

    PubMed

    Cutiongco, Marie Francene Arnobit; Tan, Ming Hao; Ng, Martin Yoke Kuang; Le Visage, Catherine; Yim, Evelyn King Fai

    2014-10-01

    Hydrogels are highly preferred in soft tissue engineering because they recapitulate the hydrated extracellular matrix. Naturally derived polysaccharides, like pullulan and dextran, are attractive materials with which to form hydrophilic polymeric networks due to their non-immunogenic and non-antigenic properties. However, their inherent hydrophilicity prevents adherent cell growth. In this study, we modified pullulan-dextran scaffolds with interfacial polyelectrolyte complexation (IPC) fibers to improve their ability to support adherent cell growth. We showed that the pullulan-dextran-IPC fiber composite scaffold laden with extracellular matrix protein has improved cell adhesion and proliferation compared to the plain polysaccharide scaffold. We also demonstrated the zero-order release kinetics of the biologics bovine serum albumin and vascular endothelial growth factor (VEGF) incorporated in the composite scaffold. Lastly, we showed that the VEGF released from the composite scaffold retained its capacity to stimulate endothelial cell growth. The incorporation of IPC fibers in the pullulan-dextran hydrogel scaffold improved its functionality and biological activity, thus enhancing its potential in tissue engineering applications.

  20. 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.

  1. Synthesis of Microspherical LiFePO4-Carbon Composites for Lithium-Ion Batteries

    PubMed Central

    Yu, Linghui; Cai, Dandan; Wang, Haihui; Titirici, Maria-Magdalena

    2013-01-01

    This paper reports an “all in one” procedure to produce mesoporous, micro-spherical LiFePO4 composed of agglomerated crystalline nanoparticles. Each nanoparticle is individually coated with a thin glucose-derived carbon layer. The main advantage of the as-synthesized materials is their good performance at high charge-discharge rates. The nanoparticles and the mesoporosity guarantee a short bulk diffusion distance for both lithium ions and electrons, as well as additional active sites for the charge transfer reactions. At the same time, the thin interconnected carbon coating provides a conductive framework capable of delivering electrons to the nanostructured LiFePO4.

  2. Composite ECM-alginate microfibers produced by microfluidics as scaffolds with biomineralization potential.

    PubMed

    Angelozzi, Marco; Miotto, Martina; Penolazzi, Letizia; Mazzitelli, Stefania; Keane, Timothy; Badylak, Stephen F; Piva, Roberta; Nastruzzi, Claudio

    2015-11-01

    A novel approach to produce artificial bone composites (microfibers) with distinctive features mimicking natural tissue was investigated. Currently proposed inorganic materials (e.g. apatite matrixes) lack self-assembly and thereby limit interactions between cells and the material. The present work investigates the feasibility of creating "bio-inspired materials" specifically designed to overcome certain limitations inherent to current biomaterials. We examined the dimensions, morphology, and constitutive features of a composite hydrogel which combined an alginate based microfiber with a gelatin solution or a particulate form of urinary bladder matrix (UBM). The effectiveness of the composite microfibers to induce and modulate osteoblastic differentiation in three-dimensional (3D) scaffolds without altering the viability and morphological characteristics of the cells was investigated. The present study describes a novel alginate microfiber production method with the use of microfluidics. The microfluidic procedure allowed for precise tuning of microfibers which resulted in enhanced viability and function of embedded cells.

  3. Preparation and characterization of nano-sized hydroxyapatite/alginate/chitosan composite scaffolds for bone tissue engineering.

    PubMed

    Kim, Hye-Lee; Jung, Gil-Yong; Yoon, Jun-Ho; Han, Jung-Suk; Park, Yoon-Jeong; Kim, Do-Gyoon; Zhang, Miqin; Kim, Dae-Joon

    2015-09-01

    The aim of this study was to develop chitosan composite scaffolds with high strength and controlled pore structures by homogenously dispersed nano-sized hydroxyapatite (nano-HAp) powders. In the fabrication of composite scaffolds, nano-HAp powders distributed in an alginate (AG) solution with a pH higher than 10 were mixed with a chitosan (CS) solution and then freeze dried. While the HAp content increased up to 70 wt.%, the compressive strength and the elastic modulus of the composite scaffolds significantly increased from 0.27 MPa and 4.42 MPa to 0.68 MPa and 13.35 MPa, respectively. Higher content of the HAp also helped develop more differentiation and mineralization of the MC3T3-E1 cells on the composite scaffolds. The uniform pore structure and the excellent mechanical properties of the HAp/CS composite scaffolds likely resulted from the use of the AG solution at pH 10 as a dispersant for the nano-HAp powders.

  4. The preparation of composite microsphere with hollow core/porous shell structure by self-assembling of latex particles at emulsion droplet interface.

    PubMed

    He, Xiao Dong; Ge, Xue Wu; Wang, Mo Zhen; Zhang, Zhi Cheng

    2006-07-15

    A submicrometer-scaled polystyrene/melamine-formaldehyde hollow microsphere composite was prepared by self-assembling of sulfonated polystyrene (SPS) latex particles at the interface of emulsion droplets and then being fixed in place using a hard melamine-formaldehyde (MF) composite layer. For control-released purposes, the influential factors that control the size and uniformity of the packed-droplets and the permeability of the composite shell, including the initial particle location, the hydrophilicity and the size of colloidal templates, the oil phase solvent and reserving time of emulsions after the addition of MF prepolymer, were further studied. Relatively uniform sized particle packed-droplets with an average diameter of 10 microm were obtained. The assembled SPS particles kept ordering and minimal conglutination after the preparation of composite microspheres, which allows of controlling the permeability from the interstices between the particles. Porous-mesh-structured MF composite layer was formed to further control the permeability. The morphology of emulsions and composite microspheres were characterized by optical microscopy, scanning and transmission electron microscopy.

  5. High-Performance Aluminum-Ion Battery with CuS@C Microsphere Composite Cathode.

    PubMed

    Wang, Shuai; Jiao, Shuqiang; Wang, Junxiang; Chen, Hao-Sen; Tian, Donghua; Lei, Haiping; Fang, Dai-Ning

    2017-01-24

    On the basis of low-cost, rich resources, and safety performance, aluminum-ion batteries have been regarded as a promising candidate for next-generation energy storage batteries in large-scale energy applications. A rechargeable aluminum-ion battery has been fabricated based on a 3D hierarchical copper sulfide (CuS) microsphere composed of nanoflakes as cathode material and room-temperature ionic liquid containing AlCl3 and 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) as electrolyte. The aluminum-ion battery with a microsphere electrode exhibits a high average discharge voltage of ∼1.0 V vs Al/AlCl4(-), reversible specific capacity of about 90 mA h g(-1) at 20 mA g(-1), and good cyclability of nearly 100% Coulombic efficiency after 100 cycles. Such remarkable electrochemical performance is attributed to the well-defined nanostructure of the cathode material facilitating the electron and ion transfer, especially for chloroaluminate ions with large size, which is desirable for aluminum-ion battery applications.

  6. Cytocompatibility of a conductive nanofibrous carbon nanotube/poly (L-Lactic acid) composite scaffold intended for nerve tissue engineering

    PubMed Central

    Kabiri, Mahboubeh; Oraee-Yazdani, Saeed; Dodel, Masumeh; Hanaee-Ahvaz, Hana; Soudi, Sara; Seyedjafari, Ehsan; Salehi, Mohammad; Soleimani, Masoud

    2015-01-01

    The purpose of this study was to fabricate a conductive aligned nanofibrous substrate and evaluate its suitability and cytocompatibility with neural cells for nerve tissue engineering purposes. In order to reach these goals, we first used electrospinning to fabricate single-walled carbon-nanotube (SWCNT) incorporated poly(L-lactic acid) (PLLA) nanofibrous scaffolds and then assessed its cytocompatibility with olfactory ensheathing glial cells (OEC). The plasma treated scaffolds were characterized using scanning electron microscopy and water contact angle. OECs were isolated from olfactory bulb of GFP Sprague-Dawley rats and characterized using OEC specific markers via immunocytochemistry and flow cytometery. The cytocompatibility of the conductive aligned nano-featured scaffold was assessed using microscopy and MTT assay. We indicate that doping of PLLA polymer with SWCNT can augment the aligned nanosized substrate with conductivity, making it favorable for nerve tissue engineering. Our results demonstrated that SWCNT/PLLA composite scaffold promote the adhesion, growth, survival and proliferation of OEC. Regarding the ideal physical, topographical and electrical properties of the scaffold and the neurotrophic and migratory features of the OECs, we suggest this scaffold and the cell/scaffold construct as a promising platform for cell delivery to neural defects in nerve tissue engineering approaches. PMID:26600751

  7. Preparation of thermoresponsive Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) magnetic composite microspheres with controlled shell thickness and its releasing property for phenolphthalein.

    PubMed

    Zhang, Baoliang; Zhang, Hepeng; Fan, Xinlong; Li, Xiangjie; Yin, Dezhong; Zhang, Qiuyu

    2013-05-15

    In this work, Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) (Fe3O4/P(AA-MMA-NIPAm)) thermoresponsive magnetic composite microspheres have been prepared by controlled radical polymerization in the presence of 1,1-diphenylethene (DPE). The shell thickness of thermosensitive polymer (PNIPAm), which was on the surface of the microspheres, can be controlled by using DPE method. The morphology and thermosensitive properties of the composite microspheres, polymerization mechanism of the shell were characterized by TEM, FTIR, VSM, Laser Particle Sizer, TGA, NMR, and GPC. The microspheres with narrow particle size distribution show high saturation magnetization and superparamagnetism. The thermosensitive properties of the composite microspheres can be adjusted indirectly via controlling the addition amount of monomer (NIPAm) in the second step during controlled radical polymerization. Phenolphthalein was chosen as a model drug to investigate drug release behavior of the thermoresponsive magnetic composite microspheres with different shell thickness. Controlled drug release testing reveals that the release behavior depends on the thickness of polymer on the surface of the microspheres.

  8. Evaluation of the novel three-dimensional porous poly (L-lactic acid)/nano-hydroxyapatite composite scaffold.

    PubMed

    Huang, Jianghong; Xiong, Jianyi; Liu, Jianquan; Zhu, Weimin; Chen, Jielin; Duan, Li; Zhang, Jufeng; Wang, Daping

    2015-01-01

    To determine the optimal ratio of nano-hydroxyapatite (n-HA) to polylactic acid (PLLA) in the novel three-dimensional porous PLLA/n-HA composite scaffolds, low-temperature rapid prototyping technology was employed to fabricate the composite materials with different n-HA contents. Mechanical properties and degradation behaviors of the composites were examined, and the scaffold microstructure and n-HA dispersion were observed by scanning electron microscope (SEM). Mechanical tests demonstrated that the tensile strength of the composite material gradually decreased with an increase in n-HA content. When the n-HA content reached 20 wt%, the bending strength of the composite material peaked at 138.5 MPa. SEM images demonstrated that the optimal content of n-HA was 20 wt% as the largest interconnected pore size that can be seen, with a porosity as high as 80%. In vitro degradation experiments demonstrated that the pH value of the material containing solution gradually decreased in a time-dependent manner, with a simultaneous weakening of the mechanical properties. In vitro study using rat osteoblast cells showed that the composite scaffolds were biocompatible; the 20 wt% n-HA scaffold offered particular improvement to rat osteoblast cell adhesion and proliferation compared to other compositions. It was therefore concluded that 20 wt% n-HA is the optimal nano-hydroxyapatite (n-HA) to polylactic acid (PLLA) ratio, with promise for bone tissue engineering.

  9. Composite scaffolds for osteochondral repair obtained by combination of additive manufacturing, leaching processes and hMSC-CM functionalization.

    PubMed

    Díaz Lantada, Andrés; Alarcón Iniesta, Hernán; García-Ruíz, Josefa Predestinación

    2016-02-01

    Articular repair is a relevant and challenging area for the emerging fields of tissue engineering and biofabrication. The need of significant gradients of properties, for the promotion of osteochondral repair, has led to the development of several families of composite biomaterials and scaffolds, using different effective approaches, although a perfect solution has not yet been found. In this study we present the design, modeling, rapid manufacturing and in vitro testing of a composite scaffold aimed at osteochondral repair. The presented composite scaffold stands out for having a functional gradient of density and stiffness in the bony phase, obtained in titanium by means of computer-aided design combined with additive manufacture using selective laser sintering. The chondral phase is obtained by sugar leaching, using a PDMS matrix and sugar as porogen, and is joined to the bony phase during the polymerization of PDMS, therefore avoiding the use of supporting adhesives or additional intermediate layers. The mechanical performance of the construct is biomimetic and the stiffness values of the bony and chondral phases can be tuned to the desired applications, by means of controlled modifications of different parameters. A human mesenchymal stem cell (h-MSC) conditioned medium (CM) is used for improving scaffold response. Cell culture results provide relevant information regarding the viability of the composite scaffolds used.

  10. Osteogenic activity of nanonized pearl powder/poly (lactide-co-glycolide) composite scaffolds for bone tissue engineering.

    PubMed

    Yang, Yueh-Lung; Chang, Ching-Hsien; Huang, Ching-Cheng; Kao, Wenny Mei-Wen; Liu, Wei-Chung; Liu, Hsia-Wei

    2014-01-01

    Numerous materials have been proposed for bone tissue engineering. In this study, a newly designed hybrid composite scaffold composed of poly (D,L-lactide-co-glycolide) and a naturally bioceramic hybrid material, nanonized pearl powder, were prepared and the biological activities and physical properties of the scaffold for bone tissue engineering were evaluated. It is a composite consisting calcium carbonate crystal in an aragonite structure, embedded in an organic matrix. Peral contains one or more signal molecules capable of stimulating bone formation. The nanonized pearl powder is considered as a promising osteoinductive biomaterial. This biomaterial is biocompatible and shows osteogenic activity. In this study, the designed biohybrid of nanonized pearl powder/poly (lactide-co-glycolide) (NPP/PLGA) biocomposite scaffolds would employ biodegradable material as MC3T3-E1 cells seeded scaffolds. Therefore, the biocomposite scaffolds would be used to culture with MC3T3-E1 cells under spinner bioreactor in vitro. Furthermore, it also detailed how these tissues were characterized, qualitatively and quantitatively, with scanning electron microscopy and biochemical testing. The identity and the mode of action of these molecules on the osteoblast differentiation were analyzed. This study indicates that the efficiency of nanonized pearl powders in bone cell differentiation are certainly different from that of proteins. Further sudy will look forward to manufacturing the promising new generation bone substitute, three dimensional biocomposite scaffolds to replace the implant and autogeneous bone graft, which combines basic research and clinical application.

  11. Biocompatibility, degradability, bioactivity and osteogenesis of mesoporous/macroporous scaffolds of mesoporous diopside/poly(l-lactide) composite

    PubMed Central

    Liu, Zhulin; Ji, Jiajin; Tang, Songchao; Qian, Jun; Yan, Yonggang; Yu, Baoqing; Su, Jiacan; Wei, Jie

    2015-01-01

    Bioactive mesoporous diopside (m-DP) and poly(l-lactide) (PLLA) composite scaffolds with mesoporous/macroporous structure were prepared by the solution-casting and particulate-leaching method. The results demonstrated that the degradability and bioactivity of the mesoporous/macroporous scaffolds were significantly improved by incorporating m-DP into PLLA, and that the improvement was m-DP content-dependent. In addition, the scaffolds containing m-DP showed the ability to neutralize acidic degradation products and prevent the pH from dropping in the solution during the soaking period. Moreover, the scaffolds containing m-DP enhanced attachment, proliferation and alkaline phosphatase activity of MC3T3-E1 cells, which were also m-DP content-dependent. Furthermore, the histological and immunohistochemical analysis results showed that the scaffolds with m-DP significantly promoted new bone formation and improved the materials degraded in vivo, indicating good biocompatibility. The results suggested that the mesoporous/macroporous scaffolds of the m-DP/PLLA composite with osteogenesis had a potential for bone regeneration. PMID:26378120

  12. Preparation and Characterization of New Nano-Composite Scaffolds Loaded With Vascular Stents

    PubMed Central

    Xu, Hongzhen; Su, Jiansheng; Sun, Jun; Ren, Tianbin

    2012-01-01

    In this study, vascular stents were fabricated from poly (lactide-ɛ-caprolactone)/collagen/nano-hydroxyapatite (PLCL/Col/nHA) by electrospinning, and the surface morphology and breaking strength were observed or measured through scanning electron microscopy and tensile tests. The anti-clotting properties of stents were evaluated for anticoagulation surfaces modified by the electrostatic layer-by-layer self-assembly technique. In addition, nano-composite scaffolds of poly (lactic-co-glycolic acid)/polycaprolactone/nano-hydroxyapatite (PLGA/PCL/nHA) loaded with the vascular stents were prepared by thermoforming-particle leaching and their basic performance and osteogenesis were tested in vitro and in vivo. The results show that the PLCL/Col/nHA stents and PLGA/PCL/nHA nano-composite scaffolds had good surface structures, mechanical properties, biocompatibility and could guide bone regeneration. These may provide a new way to build vascularized-tissue engineered bone to repair large bone defects in bone tissue engineering. PMID:22489156

  13. Preparation and characterization of new nano-composite scaffolds loaded with vascular stents.

    PubMed

    Xu, Hongzhen; Su, Jiansheng; Sun, Jun; Ren, Tianbin

    2012-01-01

    In this study, vascular stents were fabricated from poly (lactide-ɛ-caprolactone)/collagen/nano-hydroxyapatite (PLCL/Col/nHA) by electrospinning, and the surface morphology and breaking strength were observed or measured through scanning electron microscopy and tensile tests. The anti-clotting properties of stents were evaluated for anticoagulation surfaces modified by the electrostatic layer-by-layer self-assembly technique. In addition, nano-composite scaffolds of poly (lactic-co-glycolic acid)/polycaprolactone/nano-hydroxyapatite (PLGA/PCL/nHA) loaded with the vascular stents were prepared by thermoforming-particle leaching and their basic performance and osteogenesis were tested in vitro and in vivo. The results show that the PLCL/Col/nHA stents and PLGA/PCL/nHA nano-composite scaffolds had good surface structures, mechanical properties, biocompatibility and could guide bone regeneration. These may provide a new way to build vascularized-tissue engineered bone to repair large bone defects in bone tissue engineering.

  14. Synthesis of magnetic and lightweight hollow microspheres/polyaniline/Fe 3 O 4 composite in one-step method

    NASA Astrophysics Data System (ADS)

    Sun, Li; Li, Qin; Wang, Wei; Pang, Jianfeng; Zhai, Jianping

    2011-09-01

    After hollow microspheres (HM) were surface modified, a layer of electromagnetic polyaniline/Fe3O4 composite (PAN/Fe3O4) was successfully grafted onto the surface of the self-assembled monolayer coated HM, resulting in HM/PAN/Fe3O4 composites. In this approach, γ-aminopropyltriethoxy silane was adopted to form a well-coating monolayer with amino groups for the graft polymerization of aniline, which played an important role in fabricating the core-shell structure. FeCl3 was used as the oxidant not only for aniline to form PAN, but also for FeCl2 to prepare the magnets. The structure, morphologies, and magnetic properties of the as-prepared samples were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometer. The results indicated that the HM/PAN/Fe3O4 composites possess low density (ρ < 1.0 g/cm3), controllable morphology, and good magnetic properties at room temperature (saturation magnetization Ms = 8.32 emu g-1 and coercive force Hc ≈ 0).

  15. Bioactive glass-based composites for the production of dense sintered bodies and porous scaffolds.

    PubMed

    Bellucci, D; Sola, A; Cannillo, V

    2013-05-01

    Recently several attempts have been made to combine calcium phosphates, such as β-tricalcium phosphate (β-TCP) and, most of all, hydroxyapatite (HA), with bioactive glasses of different composition, in order to develop composites with improved biological and mechanical performance. Unfortunately, the production of such systems usually implies a high-temperature treatment (up to 1300 °C), which may result in several drawbacks, including crystallization of the original glass, decomposition of the calcium phosphate phase and/or reactions between the constituent phases, with non-trivial consequences in terms of microstructure, bioactivity and mechanical properties of the final samples. In the present contribution, novel binary composites have been obtained by sintering a bioactive glass, characterized by a low tendency to crystallize, with the addition of HA or β-TCP as the second phase. In particular, the composites have been treated at a relatively low temperature (818 °C and 830 °C, depending on the sample), thus preserving the amorphous structure of the glass and minimizing the interaction between the constituent phases. The effects of the glass composition, calcium phosphate nature and processing conditions on the composite microstructure, mechanical properties and in vitro bioactivity have been systematically discussed. To conclude, a feasibility study to obtain scaffolds for bone tissue regeneration has been proposed.

  16. An Inorganic Microsphere Composite for the Selective Removal of Cesium 137 from Acidic Nuclear Waste Solutions - Parts 1 and 2

    SciTech Connect

    T. J. Tranter; T. A. Vereschchagina; V. Utgikar

    2009-03-01

    A new inorganic ion exchange composite for removing radioactive cesium from acidic waste streams has been developed. The new material consists of ammonium molybdophosphate, (NH4)3P(Mo3O10)4•3H2O (AMP), synthesized within hollow aluminosilicate microspheres (AMP-C), which are produced as a by-product from coal combustion. The selective cesium exchange capacity of this inorganic composite was evaluated in bench-scale column tests using simulated sodium bearing waste solution as a surrogate for the acidic tank waste currently stored at the Idaho National Laboratory (INL). Total cesium loading on the columns at saturation agreed very well with equilibrium values predicted from isotherm experiments performed previously. A numerical algorithm for solving the governing partial differential equations (PDE) for cesium uptake was developed using the intraparticle mass transfer coefficient obtained from previous batch kinetic experiments. Solutions to the governing equations were generated to obtain the cesium concentration at the column effluent as a function of throughput volume using the same conditions as those used for the actual column experiments. The numerical solutions of the PDE fit the column break through data quite well for all the experimental conditions in the study. The model should therefore provide a reliable prediction of column performance at larger scales. A new inorganic ion exchange composite consisting of ammonium molybdophosphate, (NH4)3P(Mo3O10)4•3H2O (AMP), synthesized within hollow aluminosilicate microspheres (AMP-C) has been developed. Two different batches of the sorbent were produced resulting in 20% and 25% AMP loading for two and three loading cycles, respectively. The selective cesium exchange capacity of this inorganic composite was evaluated using simulated sodium bearing waste solution as a surrogate for the acidic tank waste currently stored at the Idaho National Laboratory (INL). Equilibrium isotherms obtained from these experiments

  17. Proteins combination on PHBV microsphere scaffold to regulate Hep3B cells activity and functionality: a model of liver tissue engineering system.

    PubMed

    Zhu, Xin Hao; Gan, Seng Keat; Wang, Chi-Hwa; Tong, Yen Wah

    2007-12-01

    The synergistic effects of extracellular matrix (ECM) protein combinations on Hep3B cell proliferation and functions are studied herein. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) microspheres were covalently conjugated with three types of proteins, collagen (type I), laminin, and fibronectin, using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide cross linkers. Successful conjugations of protein molecules were verified by the presence of nitrogen peaks in X-ray photoelectron spectroscopy. The densities of grafted proteins were quantified using Micro-BCA kit. A human hepatoma cell line, Hep3B, was then cultured in vitro on the ECM proteins-modified microspheres for 2 weeks. Cell proliferation was estimated using MTT method, and two hepatic functions, albumin secretion and P-450 activity, were evaluated using ELISA and EROD assays, respectively. The results indicated that combination of the three ECM proteins on microsphere surfaces has a significant effect on the proliferation of Hep3B cells, thus better mimicking the in vivo environment for liver tissue engineering.

  18. Novel polyvinyl alcohol-bioglass 45S5 based composite nanofibrous membranes as bone scaffolds.

    PubMed

    Shankhwar, Nisha; Kumar, Manishekhar; Mandal, Biman B; Srinivasan, A

    2016-12-01

    Composite nanofibrous membranes based on sol-gel derived 45SiO2 24.5CaO 24.5 Na2O 6 P2O5 (bioglass, BG) and 43SiO2 24.5CaO 24.5 Na2O 6 P2O5 2Fe2O3 (magnetic bioglass, MBG) blended with polyvinyl alcohol (PVA) have been electrospun. These low cost membranes were mostly amorphous in structure with minor crystalline (sodium calcium phosphate) precipitates. All membranes were biodegradable. Among these, the composites exhibited higher tensile strength, better proliferation of human osteosarcoma MG63 cells and higher alkaline phosphatase enzyme activity than the bare PVA membrane, indicating their potential in bone tissue engineering. The magnetic PVA-MBG scaffold was also found to be a promising candidate for magnetic hyperthermia application.

  19. PHBV/PLLA-based composite scaffolds fabricated using an emulsion freezing/freeze-drying technique for bone tissue engineering: surface modification and in vitro biological evaluation.

    PubMed

    Sultana, Naznin; Wang, Min

    2012-03-01

    Tissue engineering combines living cells with biodegradable materials and/or bioactive components. Composite scaffolds containing biodegradable polymers and nanosized osteoconductive bioceramic with suitable properties are promising for bone tissue regeneration. In this paper, based on blending two biodegradable and biocompatible polymers, namely poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and poly(L-lactic acid) (PLLA) with incorporated nano hydroxyapatite (HA), three-dimensional composite scaffolds with controlled microstructures and an interconnected porous structure, together with high porosity, were fabricated using an emulsion freezing/freeze-drying technique. The influence of various parameters involved in the emulsion freezing/freeze-drying technique was studied for the fabrication of good-quality polymer scaffolds based on PHBV polymers. The morphology, mechanical properties and crystallinity of PHBV/PLLA and HA in PHBV/PLLA composite scaffolds and PHBV polymer scaffolds were studied. The scaffolds were coated with collagen in order to improve wettability. During in vitro biological evaluation study, it was observed that SaOS-2 cells had high attachment on collagen-coated scaffolds. Significant improvement in cell proliferation and alkaline phosphatase activity for HA-incorporated composite scaffolds was observed due to the incorporation of HA. After 3 and 7 days of culture on all scaffolds, SaOS-2 cells also had normal morphology and growth. These results indicated that PHBV/PLLA-based scaffolds fabricated via an emulsion freezing/freeze-drying technique were favorable sites for osteoblastic cells and are promising for the applications of bone tissue engineering.

  20. Polymer-ceramic spiral structured scaffolds for bone tissue engineering: effect of hydroxyapatite composition on human fetal osteoblasts.

    PubMed

    Zhang, Xiaojun; Chang, Wei; Lee, Paul; Wang, Yuhao; Yang, Min; Li, Jun; Kumbar, Sangamesh G; Yu, Xiaojun

    2014-01-01

    For successful bone tissue engineering, a scaffold needs to be osteoconductive, porous, and biodegradable, thus able to support attachment and proliferation of bone cells and guide bone formation. Recently, hydroxyapatites (HA), a major inorganic component of natural bone, and biodegrade polymers have drawn much attention as bone scaffolds. The present study was designed to investigate whether the bone regenerative properties of nano-HA/polycaprolactone (PCL) spiral scaffolds are augmented in an HA dose dependent manner, thereby establishing a suitable composition as a bone formation material. Nano-HA/PCL spiral scaffolds were prepared with different weight ratios of HA and PCL, while porosity was introduced by a modified salt leaching technique. Human fetal osteoblasts (hFOBs) were cultured on the nano-HA/PCL spiral scaffolds up to 14 days. Cellular responses in terms of cell adhesion, viability, proliferation, differentiation, and the expression of bone-related genes were investigated. These scaffolds supported hFOBs adhesion, viability and proliferation. Cell proliferation trend was quite similar on polymer-ceramic and neat polymer spiral scaffolds on days 1, 7, and 14. However, the significantly increased amount of alkaline phosphatase (ALP) activity and mineralized matrix synthesis was evident on the nano-HA/PCL spiral scaffolds. The HA composition in the scaffolds showed a significant effect on ALP and mineralization. Bone phenotypic markers such as bone sialoprotein (BSP), osteonectin (ON), osteocalcin (OC), and type I collagen (Col-1) were semi-quantitatively estimated by reverse transcriptase polymerase chain reaction analysis. All of these results suggested the osteoconductive characteristics of HA/PCL nanocomposite and cell maturation were HA dose dependent. For instance, HA∶PCL = 1∶4 group showed significantly higher ALP mineralization and elevated levels of BSP, ON, OC and Col-I expression as compared other lower or higher ceramic ratios

  1. Doped zinc oxide microspheres

    DOEpatents

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  2. Doped zinc oxide microspheres

    DOEpatents

    Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

    1993-12-14

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

  3. Porous calcium phosphate-poly (lactic-co-glycolic) acid composite bone cement: A viable tunable drug delivery system.

    PubMed

    Roy, Abhijit; Jhunjhunwala, Siddharth; Bayer, Emily; Fedorchak, Morgan; Little, Steve R; Kumta, Prashant N

    2016-02-01

    Calcium phosphate based cements (CPCs) are frequently used as bone void fillers for non-load bearing segmental bone defects due to their clinically relevant handling characteristics and ability to promote natural bone growth. Macroporous CPC scaffolds with interconnected pores are preferred for their ability to degrade faster and enable accelerated bone regeneration. Herein, a composite CPC scaffold is developed using newly developed resorbable calcium phosphate cement (ReCaPP) formulation containing degradable microspheres of bio-compatible poly (lactic-co-glycolic acid) (PLGA) serving as porogen. The present study is aimed at characterizing the effect of in-vitro degradation of PLGA microspheres on the physical, chemical and structural characteristics of the composite cements. The porosity measurements results reveal the formation of highly interconnected macroporous scaffolds after degradation of PLGA microspheres. The in-vitro characterizations also suggest that the degradation by products of PLGA reduces the pH of the local environment thereby increasing the dissolution rate of the cement. In addition, the in-vitro vancomycin release from the composite CPC scaffold suggests that the drug association with the composite scaffolds can be tuned to achieve control release kinetics. Further, the study demonstrates control release lasting for longer than 10weeks from the composite cements in which vancomycin is encapsulated in PLGA microspheres.

  4. Fabrication of poly (L-lactic acid)/gelatin composite tubular scaffolds for vascular tissue engineering.

    PubMed

    Shalumon, K T; Deepthi, S; Anupama, M S; Nair, S V; Jayakumar, R; Chennazhi, K P

    2015-01-01

    The in vitro fabrication of fully functional 3D vascular tissue construct represents one of the most fundamental challenges in vascular tissue engineering. Polymer blending is an effective method for developing, desirable bio-composites for tissue engineering. This study employs the blending of desired characteristics of a synthetic polymer, poly (L-lactic acid) (PLLA) and a biopolymer, gelatin for enhancing cell adhesion sites. Aligned and random PLLA/gelatin nanofibers were fabricated using electrospinning technique. Morphological and chemical characterization of the nanofibrous scaffolds was carried out and the size of fibers ranged from 100 to 500 nm. The SEM, fluorescent staining and viability assays revealed an increase in viability and proliferation of Human Umbilical Vein Endothelial Cells (HUVECs) and Smooth Muscle Cells (SMCs) proportional to gelatin content. The aligned fiber morphology helps cells to orient and elongate along their long axis. Thus the results were suggestive of the fact that topographically aligned nanofibrous scaffolds control cellular organization and possibly provide a good support for achieving the vital organization and physical properties of blood vessel.

  5. PGA-incorporated collagen: Toward a biodegradable composite scaffold for bone-tissue engineering.

    PubMed

    Toosi, Shirin; Naderi-Meshkin, Hojjat; Kalalinia, Fatemeh; Peivandi, Mohammad Taghi; HosseinKhani, Hossein; Bahrami, Ahmad Reza; Heirani-Tabasi, Asieh; Mirahmadi, Mahdi; Behravan, Javad

    2016-08-01

    Nowadays composite scaffolds based on synthetic and natural biomaterials have got attention to increase healing of non-union bone fractures. To this end, different aspects of collagen sponge incorporated with poly(glycolic acid) (PGA) fiber were investigated in this study. Collagen solution (6.33 mg/mL) with PGA fibers (collagen/fiber ratio [w/w]: 4.22, 2.11, 1.06, 0.52) was freeze-dried, followed by dehydrothermal cross-linking to obtain collagen sponge incorporating PGA fibers. Properties of scaffold for cell viability, proliferation, and differentiation of mesenchymal stem cells (MSCs) were evaluated. Scanning electron microscopy showed that collagen sponge exhibited an interconnected pore structure with an average pore size of 190 μm, irrespective of PGA fiber incorporation. The collagen-PGA sponge was superior to the original collagen sponge in terms of the initial attachment, proliferation rate, and osteogenic differentiation of the bone marrow-MSCs (BM-MSC). The shrinkage of sponges during cell culture was significantly suppressed by fiber incorporation. Incorporation of PGA fiber is a simple and promising way to reinforce collagen sponge without impairing biocompatibility. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2020-2028, 2016.

  6. A keratin scaffold regulates epidermal barrier formation, mitochondrial lipid composition, and activity

    PubMed Central

    Kumar, Vinod; Bouameur, Jamal-Eddine; Bär, Janina; Rice, Robert H.; Hornig-Do, Hue-Tran; Roop, Dennis R.; Schwarz, Nicole; Brodesser, Susanne; Thiering, Sören; Leube, Rudolf E.; Wiesner, Rudolf J.; Vijayaraj, Preethi; Brazel, Christina B.; Heller, Sandra; Binder, Hans; Löffler-Wirth, Henry; Seibel, Peter

    2015-01-01

    Keratin intermediate filaments (KIFs) protect the epidermis against mechanical force, support strong adhesion, help barrier formation, and regulate growth. The mechanisms by which type I and II keratins contribute to these functions remain incompletely understood. Here, we report that mice lacking all type I or type II keratins display severe barrier defects and fragile skin, leading to perinatal mortality with full penetrance. Comparative proteomics of cornified envelopes (CEs) from prenatal KtyI−/− and KtyII−/−K8 mice demonstrates that absence of KIF causes dysregulation of many CE constituents, including downregulation of desmoglein 1. Despite persistence of loricrin expression and upregulation of many Nrf2 targets, including CE components Sprr2d and Sprr2h, extensive barrier defects persist, identifying keratins as essential CE scaffolds. Furthermore, we show that KIFs control mitochondrial lipid composition and activity in a cell-intrinsic manner. Therefore, our study explains the complexity of keratinopathies accompanied by barrier disorders by linking keratin scaffolds to mitochondria, adhesion, and CE formation. PMID:26644517

  7. Characterization of hydroxyapatite whisker reinforced composites and scaffolds for mechanical and biological function in orthopaedic and spinal implants

    NASA Astrophysics Data System (ADS)

    Conrad, Timothy L.

    The overall objective of this study was to investigate the mechanical and biological properties of HA whisker reinforced polyaryletherketone (PAEK) composites and scaffolds which are key to clinical translation for orthopedic and spinal implants. The fatigue behavior of polyetherketoneketone (PEKK) reinforced with 0, 20, and 40 vol% hydroxyapatite (HA) was investigated in four-point bending fatigue. The fatigue life decreased with increasing HA reinforcement. However, PEKK reinforced with 40 vol% HA whiskers exhibited a fatigue life greater than 2.106 cycles at 40 MPa. Moreover, HA whisker reinforcement resulted in decreased creep deformation and minimal modulus degradation. The effects of the mold temperature and polyetheretherketone (PEEK) powder were investigated on the mechanical properties and crystallinity of HA whisker reinforced PEEK scaffolds prepared using compression molding and porogen leaching. The mechanical properties of the scaffolds increased while the PEEK crystallinity decreased, with increasing mold temperature and suggested an optimal mold temperature of 370--375°C for PEEK scaffolds comprising of 75% porosity and 20 vol% HA whisker reinforcement, regardless of the PEEK powder size. The effects of the porogen morphology on the architecture, mechanical properties, and permeability of HA whisker reinforced PEEK scaffolds were investigated in 75--90% porous scaffolds. HA whisker reinforced PEEK scaffolds prepared with an ellipsoidal porogen exhibited a greater permeability than scaffolds prepared with a cubic porogen. The compressive modulus, yield strength, and yield strain were not affected by the porogen morphology. The effects of HA reinforcement morphology and content was investigated on the behavior of primary osteoblasts on dense HA reinforced PEEK substrates in vitro. At day 7, the number of osteoblasts attached to PEEK substrate surfaces increased with increasing HA content and for HA whiskers compared to equiaxed HA powder reinforcement

  8. Silica-titania composite aerogel photocatalysts by chemical liquid deposition of titania onto nanoporous silica scaffolds.

    PubMed

    Zu, Guoqing; Shen, Jun; Wang, Wenqin; Zou, Liping; Lian, Ya; Zhang, Zhihua

    2015-03-11

    Silica-titania composite aerogels were synthesized by chemical liquid deposition of titania onto nanoporous silica scaffolds. This novel deposition process was based on chemisorption of partially hydrolyzed titanium alkoxides from solution onto silica nanoparticle surfaces and subsequent hydrolysis and condensation to afford titania nanoparticles on the silica surface. The titania is homogeneously distributed in the silica-titania composite aerogels, and the titania content can be effectively controlled by regulating the deposition cycles. The resultant composite aerogel with 15 deposition cycles possessed a high specific surface area (SSA) of 425 m(2)/g, a small particle size of 5-14 nm, and a large pore volume and pore size of 2.41 cm(3)/g and 18.1 nm, respectively, after heat treatment at 600 °C and showed high photocatalytic activity in the photodegradation of methylene blue under UV-light irradiation. Its photocatalytic activity highly depends on the deposition cycles and heat treatment. The combination of small particle size, high SSA, and enhanced crystallinity after heat treatment at 600 °C contributes to the excellent photocatalytic property of the silica-titania composite aerogel. The higher SSAs compared to those of the reported titania aerogels (<200 m(2)/g at 600 °C) at high temperatures combined with the simple method makes the silica-titania aerogels promising candidates as photocatalysts.

  9. 3D Printing of Aniline Tetramer-Grafted-Polyethylenimine and Pluronic F127 Composites for Electroactive Scaffolds.

    PubMed

    Dong, Shi-Lei; Han, Lu; Du, Cai-Xia; Wang, Xiao-Yu; Li, Lu-Hai; Wei, Yen

    2017-02-01

    Electroactive hydrogel scaffolds are fabricated by the 3D-printing technique using composites of 30% Pluronic F127 and aniline tetramer-grafted-polyethylenimine (AT-PEI) copolymers with various contents from 2.5% to 10%. The synthesized AT-PEI copolymers can self-assemble into nanoparticles with the diameter of ≈50 nm and display excellent electroactivity due to AT conjugation. The copolymers are then homogeneously distributed into 30% Pluronic F127 solution by virtue of the thermosensitivity of F127, denoted as F/AT-PEI composites. Macroscopic photographs of latticed scaffolds elucidate their excellent printability of F/AT-PEI hydrogels for the 3D-printing technique. The conductivities of the printed F/AT-PEI scaffolds are all higher than 2.0 × 10(-3) S cm(-1) , which are significantly improved compared with that of F127 scaffold with only 0.94 × 10(-3) S cm(-1) . Thus, the F/AT-PEI scaffolds can be considered as candidates for application in electrical stimulation of tissue regeneration such as repair of muscle and cardiac nerve tissue.

  10. Enhancement of nanofibrous scaffold of multiwalled carbon nanotubes/polyurethane composite to the fibroblasts growth and biosynthesis.

    PubMed

    Meng, Jie; Kong, Hua; Han, Zhaozhao; Wang, Chaoying; Zhu, Guangjin; Xie, Sishen; Xu, Haiyan

    2009-01-01

    In this work, the effect of nanofibrous structure and multiwalled carbon nanotubes (MWNTs) incorporation in the polyurethane (PU) on the fibroblasts growth behavior was studied. The nanofibrous scaffold of multiwalled carbon nanotubes and polyurethane composite (MWNT/PU) with an average fiber diameter of 300-500 nm was fabricated by electrospinning technique. The nanofibrous scaffold of PU, smooth film of PU, and MWNT/PU were also prepared as controls. Cell viability assay, laser confocal microscopy, and scanning electron microscopy were applied to evaluate cell adhesion, proliferation, and cytoskeletal development on the scaffolds, respectively. Cell-released protein was analyzed by Bradford protein assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), mass spectrometry, and transwell assay, respectively. Experimental results demonstrated that the scaffold with nanofibrous structure and MWNTs incorporation exhibited highest enhancement not only to the cell adhesion and proliferation but also to the cell migration and aggregation. Besides, cells cultured on the nanofibrous scaffold of MWNT/PU released the largest amount of proteins including collagen in comparison with those on the other substrates. Hence, the nanofibrous architecture and MWNTs incorporation provided favorite interactions to the cells, which implied the application potentials of the nanofibrous composite for tissue repair and regeneration.

  11. Investigation of silk fibroin nanoparticle-decorated poly(l-lactic acid) composite scaffolds for osteoblast growth and differentiation

    PubMed Central

    Chen, Biao-Qi; Kankala, Ranjith Kumar; Chen, Ai-Zheng; Yang, Ding-Zhu; Cheng, Xiao-Xia; Jiang, Ni-Na; Zhu, Kai; Wang, Shi-Bin

    2017-01-01

    Attempts to reflect the physiology of organs is quite an intricacy during the tissue engineering process. An ideal scaffold and its surface topography can address and manipulate the cell behavior during the regeneration of targeted tissue, affecting the cell growth and differentiation significantly. Herein, silk fibroin (SF) nanoparticles were incorporated into poly(l-lactic acid) (PLLA) to prepare composite scaffolds via phase-inversion technique using supercritical carbon dioxide (SC-CO2). The SF nanoparticle core increased the surface roughness and hydrophilicity of the PLLA scaffolds, leading to a high affinity for albumin attachment. The in vitro cytotoxicity test of SF/PLLA scaffolds in L929 mouse fibroblast cells indicated good biocompatibility. Then, the in vitro interplay between mouse preosteoblast cell (MC3T3-E1) and various topological structures and biochemical cues were evaluated. The cell adhesion, proliferation, osteogenic differentiation and their relationship with the structures as well as SF content were explored. The SF/PLLA weight ratio (2:8) significantly affected the MC3T3-E1 cells by improving the expression of key players in the regulation of bone formation, ie, alkaline phosphatase (ALP), osteocalcin (OC) and collagen 1 (COL-1). These results suggest not only the importance of surface topography and biochemical cues but also the potential of applying SF/PLLA composite scaffolds as biomaterials in bone tissue engineering. PMID:28331312

  12. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1986-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  13. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1987-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  14. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1983-01-01

    Microspheres of acrolein homopolymers and co-polymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  15. Induction and quantification of collagen fiber alignment in a three-dimensional hydroxyapatite-collagen composite scaffold.

    PubMed

    Banglmaier, Richard F; Sander, Edward A; VandeVord, Pamela J

    2015-04-01

    Hydroxyapatite-collagen composite scaffolds are designed to serve as a regenerative load bearing replacement that mimics bone. However, the material properties of these scaffolds are at least an order of magnitude less than that of bone and subject to fail under physiological loading conditions. These scaffolds compositionally resemble bone but they do not possess important structural attributes such as an ordered arrangement of collagen fibers, which is a correlate to the mechanical properties in bone. Furthermore, it is unclear how much ordering of structure is satisfactory to mimic bone. Therefore, quantitative methods are needed to characterize collagen fiber alignment in these scaffolds for better correlation between the scaffold structure and the mechanical properties. A combination of extrusion and compaction was used to induce collagen fiber alignment in composite scaffolds. Collagen fiber alignment, due to extrusion and compaction, was quantified from polarized light microscopy images with a Fourier transform image processing algorithm. The Fourier transform method was capable of resolving the degree of collagen alignment from polarized light images. Anisotropy indices of the image planes ranged from 0.08 to 0.45. Increases in the degree of fiber alignment induced solely by extrusion (0.08-0.25) or compaction (0.25-0.44) were not as great as those by the combination of extrusion and compaction (0.35-0.45). Additional measures of randomness and fiber direction corroborate these anisotropy findings. This increased degree of collagen fiber alignment was induced in a preferred direction that is consistent with the extrusion direction and parallel with the compacted plane.

  16. microsphere assemblies

    NASA Astrophysics Data System (ADS)

    Peña-Flores, Jesús I.; Palomec-Garfias, Abraham F.; Márquez-Beltrán, César; Sánchez-Mora, Enrique; Gómez-Barojas, Estela; Pérez-Rodríguez, Felipe

    2014-09-01

    The effect of Fe ion concentration on the morphological, structural, and optical properties of TiO2 films supported on silica (SiO2) opals has been studied. TiO2:Fe2O3 films were prepared by the sol-gel method in combination with a vertical dip coating procedure; precursor solutions of Ti and Fe were deposited on a monolayer of SiO2 opals previously deposited on a glass substrate by the same procedure. After the dip coating process has been carried out, the samples were thermally treated to obtain the TiO2:Fe2O3/SiO2 composites at the Fe ion concentrations of 1, 3, and 5 wt%. Scanning electron microscopy (SEM) micrographs show the formation of colloidal silica microspheres of about 50 nm diameter autoensembled in a hexagonal close-packed fashion. Although the X-ray diffractograms show no significant effect of Fe ion concentration on the crystal structure of TiO2, the μ-Raman and reflectance spectra do show that the intensity of a phonon vibration mode and the energy bandgap of TiO2 decrease as the Fe+3 ion concentration increases.

  17. A facile and cheap coating method to prepare SiO2/melamine-formaldehyde and SiO2/urea-formaldehyde composite microspheres

    NASA Astrophysics Data System (ADS)

    Mou, Shaoyan; Lu, Yao; Jiang, Yong

    2016-10-01

    A facile and cheap coating route has been explored to prepare SiO2/melamine formaldehyde hybrid particles. In this process, SiO2 microspheres act as seeds, and a polycondensation reaction occurs on the surface of melamine-formaldehyde pre-polymers. Formaldehyde is essential in this coating process because it acts as a novel and cheap surface modification agent instead of a traditional silane coupling agent. Ultrasonic method is used in the synthesis to avoid aggregation of nano- and micro-particles. Most of the traditional methods preparing composite microspheres were implemented under difficult conditions and at high costs. The improved coating method is much more able to provide a convenient path for researchers and engineers to more easily and economically perform experiments and engage in manufacturing. To verify this convenient method, SiO2/urea-formaldehyde composite microspheres were also prepared. SEM images show that the surfaces of all the products are smooth and well-shaped.

  18. Future Prospects for Scaffolding Methods and Biomaterials in Skin Tissue Engineering: A Review

    PubMed Central

    Chaudhari, Atul A.; Vig, Komal; Baganizi, Dieudonné Radé; Sahu, Rajnish; Dixit, Saurabh; Dennis, Vida; Singh, Shree Ram; Pillai, Shreekumar R.

    2016-01-01

    Over centuries, the field of regenerative skin tissue engineering has had several advancements to facilitate faster wound healing and thereby restoration of skin. Skin tissue regeneration is mainly based on the use of suitable scaffold matrices. There are several scaffold types, such as porous, fibrous, microsphere, hydrogel, composite and acellular, etc., with discrete advantages and disadvantages. These scaffolds are either made up of highly biocompatible natural biomaterials, such as collagen, chitosan, etc., or synthetic materials, such as polycaprolactone (PCL), and poly-ethylene-glycol (PEG), etc. Composite scaffolds, which are a combination of natural or synthetic biomaterials, are highly biocompatible with improved tensile strength for effective skin tissue regeneration. Appropriate knowledge of the properties, advantages and disadvantages of various biomaterials and scaffolds will accelerate the production of suitable scaffolds for skin tissue regeneration applications. At the same time, emphasis on some of the leading challenges in the field of skin tissue engineering, such as cell interaction with scaffolds, faster cellular proliferation/differentiation, and vascularization of engineered tissues, is inevitable. In this review, we discuss various types of scaffolding approaches and biomaterials used in the field of skin tissue engineering and more importantly their future prospects in skin tissue regeneration efforts. PMID:27898014

  19. The Osteogenesis of Bone Marrow Stem Cells on mPEG-PCL-mPEG/Hydroxyapatite Composite Scaffold via Solid Freeform Fabrication

    PubMed Central

    Liao, Han-Tsung; Jiang, Cho-Pei

    2014-01-01

    The study described a novel bone tissue scaffold fabricated by computer-aided, air pressure-aided deposition system to control the macro- and microstructure precisely. The porcine bone marrow stem cells (PBMSCs) seeded on either mPEG-PCL-mPEG (PCL) or mPEG-PCL-mPEG/hydroxyapatite (PCL/HA) composite scaffold were cultured under osteogenic medium to test the ability of osteogenesis in vitro. The experimental outcomes indicated that both scaffolds possessed adequate pore size, porosity, and hydrophilicity for the attachment and proliferation of PBMSCs and the PBMSCs expressed upregulated genes of osteogensis and angiogenesis in similar manner on both scaffolds. The major differences between these two types of the scaffolds were the addition of HA leading to higher hardness of PCL/HA scaffold, cell proliferation, and VEGF gene expression in PCL/HA scaffold. However, the in vivo bone forming efficacy between PBMSCs seeded PCL and PCL/HA scaffold was different from the in vitro results. The outcome indicated that the PCL/HA scaffold which had bone-mimetic environment due to the addition of HA resulted in better bone regeneration and mechanical strength than those of PCL scaffold. Therefore, providing a bone-mimetic scaffold is another crucial factor for bone tissue engineering in addition to the biocompatibility, 3D architecture with high porosity, and interpored connection. PMID:24868523

  20. The osteogenesis of bone marrow stem cells on mPEG-PCL-mPEG/hydroxyapatite composite scaffold via solid freeform fabrication.

    PubMed

    Liao, Han-Tsung; Chen, Yo-Yu; Lai, Yu-Ting; Hsieh, Ming-Fa; Jiang, Cho-Pei

    2014-01-01

    The study described a novel bone tissue scaffold fabricated by computer-aided, air pressure-aided deposition system to control the macro- and microstructure precisely. The porcine bone marrow stem cells (PBMSCs) seeded on either mPEG-PCL-mPEG (PCL) or mPEG-PCL-mPEG/hydroxyapatite (PCL/HA) composite scaffold were cultured under osteogenic medium to test the ability of osteogenesis in vitro. The experimental outcomes indicated that both scaffolds possessed adequate pore size, porosity, and hydrophilicity for the attachment and proliferation of PBMSCs and the PBMSCs expressed upregulated genes of osteogensis and angiogenesis in similar manner on both scaffolds. The major differences between these two types of the scaffolds were the addition of HA leading to higher hardness of PCL/HA scaffold, cell proliferation, and VEGF gene expression in PCL/HA scaffold. However, the in vivo bone forming efficacy between PBMSCs seeded PCL and PCL/HA scaffold was different from the in vitro results. The outcome indicated that the PCL/HA scaffold which had bone-mimetic environment due to the addition of HA resulted in better bone regeneration and mechanical strength than those of PCL scaffold. Therefore, providing a bone-mimetic scaffold is another crucial factor for bone tissue engineering in addition to the biocompatibility, 3D architecture with high porosity, and interpored connection.

  1. Amorphous calcium phosphate nanospheres/polylactide composite coated tantalum scaffold: facile preparation, fast biomineralization and subchondral bone defect repair application.

    PubMed

    Zhou, Rong; Xu, Wei; Chen, Feng; Qi, Chao; Lu, Bing-Qiang; Zhang, Hao; Wu, Jin; Qian, Qi-Rong; Zhu, Ying-Jie

    2014-11-01

    Calcium phosphate (CaP) materials are widely used in various biomedical areas such as drug/gene delivery and bone repair/tissue engineering. In this study, amorphous CaP nanospheres synthesized by a simple co-precipitation method are used to prepare the CaP-polylactide (CaP-PLA) composite. Then, the as-prepared CaP-PLA composite is used to coat tantalum (Ta) plates and porous scaffolds. Compared with bare Ta plate, CaP-PLA coated Ta plates show a high performance of surface biomineralization in simulated body fluid (SBF). In addition, the hydrophilicity of the CaP-PLA coated Ta plates is significantly improved. CaP-PLA coated Ta plates with bovine serum albumin (BSA) are prepared and used for the investigation of BSA release in vitro. The experimental results indicate a sustained BSA release property and simultaneous biomineralization of the as-prepared BSA-containing CaP-PLA coated Ta plates. Furthermore, CaP-PLA coated Ta scaffolds are favorable for the human osteoblast-like MG63 cells adhesion and spreading. The vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-containing CaP-PLA coated porous Ta scaffolds are used for the study of rabbit subchondral bone defect repair, covering with autogeneic periosteums. The as-prepared CaP-PLA composite coated Ta scaffolds are useful to guide the bone regeneration in vivo.

  2. Electrospinning and evaluation of PHBV-based tissue engineering scaffolds with different fibre diameters, surface topography and compositions.

    PubMed

    Tong, Ho-Wang; Wang, Min; Lu, William W

    2012-01-01

    While electrospinning is an effective technology for producing poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) micrometre-scale fibrous scaffolds for tissue regeneration, electrospinning of PHBV fibrous scaffolds composed of sub-micrometre fibres, surface-porous fibres or nanocomposite fibres is rarely explored. In this study, the average PHBV fibre diameter was successfully reduced to the sub-micrometre scale by dissolving a conductivity-enhancing salt in the polymer solution for electrospinning. Surface-porous fibres were made using a mixture of solvents, and carbonated hydroxyapatite (CHA) nanoparticles were incorporated into the fibres with the aid of an ultrasonic power source. Water contact angle measurements demonstrated that both fibre diameter reduction and CHA incorporation enhanced the wettability of the fibrous scaffolds. Tensile properties of the scaffolds were not undermined by the reduction of fibre diameter and the presence of surface pores. In vitro biological evaluation using a human osteoblast-like cell line (SaOS-2) demonstrated that all types of fibrous scaffolds supported cell attachment, spreading and proliferation. Analysis of cell morphology revealed similar projected cell areas on all types of scaffolds. However, cells on sub-micrometre fibres possessed a lower cell aspect ratio than cells on microfibres. The reduction of fibre diameter to the sub-micrometre scale enhanced cell proliferation after 14 days cell culture, while the incorporation of CHA nanoparticles in microfibres significantly enhanced the alkaline phosphatase activity of SaOS-2 cells. The control of fibre diameter, surface topography and composition is important in developing electrospun PHBV-based scaffolds for specific tissue-engineering applications.

  3. Effect of the preparation methods on architecture, crystallinity, hydrolytic degradation, bioactivity, and biocompatibility of PCL/bioglass composite scaffolds.

    PubMed

    Dziadek, Michal; Pawlik, Justyna; Menaszek, Elzbieta; Stodolak-Zych, Ewa; Cholewa-Kowalska, Katarzyna

    2015-11-01

    In this study, two different composition gel derived silica-rich (S2) or calcium-rich (A2) bioactive glasses (SBG) from a basic CaO-P2 O5 -SiO2 system were incorporated into poly(ε-caprolactone) (PCL) matrix to obtain novel bioactive composite scaffolds for bone tissue engineering applications. The composites were fabricated in the form of highly porous 3D scaffolds using following preparation methods: solvent casting particulate leaching (SCPL), solid-liquid phase separation, phase inversion (PI). Scaffolds containing 21% vol. of each bioactive glass were characterized for architecture, crystallinity, hydrolytic degradation, surface bioactivity, and cellular response. Results indicated that the use of different preparation methods leads to obtain highly porous (60-90%) materials with differentiated morphology: pore shape, size, and distributions. Thermal analysis (DSC) showed that the preparation method of materials and addition of bioactive glass particles into polymer matrix induced the changes of PCL crystallinity. Composites obtained by SCPL and PI method containing A2 SBG rapidly formed a hydroxyapatite calcium phosphate surface layer after incubation in SBF. Bioactive glasses used as filler in composite scaffolds could neutralize the released acidic by-products of the polymer degradation. Preliminary in vitro biological studies of the composites in contact with osteoblastic cells showed good biocompatibility of the obtained materials. Addition of bioactive glass into the PCL matrix promotes mineralization estimated on the basis of the ALP activity. These results suggest that through a process of selection appropriate methods of preparation and bioglass composition it is possible to design and obtain porous materials with suitable properties for regeneration of bone tissue.

  4. Combination of thermal extrusion printing and ultrafast laser fabrication for the manufacturing of 3D composite scaffolds

    NASA Astrophysics Data System (ADS)

    Balčiūnas, Evaldas; Lukoševičius, Laurynas; Mackevičiūtė, Dovilė; Rekštytė, Sima; Rutkūnas, Vygandas; Paipulas, Domas; Stankevičiūtė, Karolina; Baltriukienė, Daiva; Bukelskienė, Virginija; Piskarskas, Algis P.; Malinauskas, Mangirdas

    2014-03-01

    We present a novel approach to manufacturing 3D microstructured composite scaffolds for tissue engineering applications. A thermal extrusion 3D printer - a simple, low-cost tabletop device enabling rapid materialization of CAD models in plastics - was used to produce cm-scale microporous scaffolds out of polylactic acid (PLA). The fabricated objects were subsequently immersed in a photosensitive monomer solution and direct laser writing technique (DLW) was used to refine its inner structure by fabricating a fine mesh inside the previously produced scaffold. In addition, a composite material structure out of four different materials fabricated via DLW is presented. This technique, empowered by ultrafast lasers allows 3D structuring with high spatial resolution in a great variety of photosensitive materials. A composite scaffold made of distinct materials and periodicities is acquired after the development process used to wash out non-linked monomers. Another way to modify the 3D printed PLA surfaces was also demonstrated - ablation with femtosecond laser beam. Structure geometry on macro- to micro- scales could be finely tuned by combining these fabrication techniques. Such artificial 3D substrates could be used for cell growth or as biocompatible-biodegradable implants. To our best knowledge, this is the first experimental demonstration showing the creation of composite 3D scaffolds using convenient 3D printing combined with DLW. This combination of distinct material processing techniques enables rapid fabrication of diverse functional micro-featured and integrated devices. Hopefully, the proposed approach will find numerous applications in the field of tissue engineering, as well as in microelectromechanical systems, microfluidics, microoptics and others.

  5. Stabilization of porous chitosan improves the performance of its association with platelet-rich plasma as a composite scaffold.

    PubMed

    Shimojo, A A M; Perez, A G M; Galdames, S E M; Brissac, I C S; Santana, M H A

    2016-03-01

    This study offers innovative perspectives for optimizing of scaffolds based on correlation structure-function aimed the regenerative medicine. Thus, we evaluated in vitro performance of stabilized porous chitosan (SPCHTs) associated with activated platelet-rich plasma (aP-PRP) as a composite scaffold for the proliferation and osteogenic differentiation of human adipose-derived mesenchymal stem cells (h-AdMSCs). The porous structure of chitosan (PCHT) was prepared similarly to solid sponges by controlled freezing (-20 °C) and lyophilization of a 3% (w/v) chitosan solution. Stabilization was performed by treating the PCHT with sodium hydroxide (TNaOH), an ethanol series (TEtOH) or by crosslinking with tripolyphosphate (CTPP). The aP-PRP was obtained from the controlled centrifugation of whole blood and activated with autologous serum and calcium. Imaging of the structures showed fibrin networks inside and on the surface of SPCHTs as a consequence of electrostatic interactions. SPCHTs were non-cytotoxic, and the porosity, pore size and Young's modulus were approximately 96%, 145 μm and 1.5 MPa for TNaOH and TEtOH and 94%, 110 μm and 1.8 MPa for CTPP, respectively. Stabilization maintained the integrity of the SPCHTs for at least 10 days of cultivation. SPCHTs showed controlled release of the growth factors TGF-β1 and PDGF-AB. Although generating different patterns, all of the stabilization treatments improved the proliferation of seeded h-AdMSCs on the composite scaffold compared to aP-PRP alone, and differentiation of the composite scaffold treated with TEtOH was significantly higher than for non-stabilized PCHT. We conclude that the composite scaffolds improved the in vitro performance of PRP and have potential in regenerative medicine.

  6. Ingrowth of human mesenchymal stem cells into porous silk particle reinforced silk composite scaffolds: An in vitro study.

    PubMed

    Rockwood, Danielle N; Gil, Eun Seok; Park, Sang-Hyug; Kluge, Jonathan A; Grayson, Warren; Bhumiratana, Sarindr; Rajkhowa, Rangam; Wang, Xungai; Kim, Sung Jun; Vunjak-Novakovic, Gordana; Kaplan, David L

    2011-01-01

    Silk fibroin protein is biodegradable and biocompatible, exhibiting excellent mechanical properties for various biomedical applications. However, porous three-dimensional (3-D) silk fibroin scaffolds, or silk sponges, usually fall short in matching the initial mechanical requirements for bone tissue engineering. In the present study, silk sponge matrices were reinforced with silk microparticles to generate protein-protein composite scaffolds with desirable mechanical properties for in vitro osteogenic tissue formation. It was found that increasing the silk microparticle loading led to a substantial increase in the scaffold compressive modulus from 0.3 MPa (non-reinforced) to 1.9 MPa for 1:2 (matrix:particle) reinforcement loading by dry mass. Biochemical, gene expression, and histological assays were employed to study the possible effects of increasing composite scaffold stiffness, due to microparticle reinforcement, on in vitro osteogenic differentiation of human mesenchymal stem cells (hMSCs). Increasing silk microparticle loading increased the osteogenic capability of hMSCs in the presence of bone morphogenic protein-2 (BMP-2) and other osteogenic factors in static culture for up to 6 weeks. The calcium adsorption increased dramatically with increasing loading, as observed from biochemical assays, histological staining, and microcomputer tomography (μCT) analysis. Specifically, calcium content in the scaffolds increased by 0.57, 0.71, and 1.27 mg (per μg of DNA) from 3 to 6 weeks for matrix to particle dry mass loading ratios of 1:0, 1:1, and 1:2, respectively. In addition, μCT imaging revealed that at 6 weeks, bone volume fraction increased from 0.78% for non-reinforced to 7.1% and 6.7% for 1:1 and 1:2 loading, respectively. Our results support the hypothesis that scaffold stiffness may strongly influence the 3-D in vitro differentiation capabilities of hMSCs, providing a means to improve osteogenic outcomes.

  7. Development of Composite Porous Scaffolds Based on Collagen and Biodegradable Poly(ester urethane)urea

    PubMed Central

    Guan, Jianjun; Stankus, John J.; Wagner, William R.

    2010-01-01

    Our objective in this work was to develop a flexible, biodegradable scaffold for cell transplantation that would incorporate a synthetic component for strength and flexibility and type I collagen for enzymatic lability and cytocompatibility. A biodegradable poly(ester urethane)urea was synthesized from poly(caprolactone), 1,4-diisocyanatobutane, and putrescine. Using a thermally induced phase separation process, porous scaffolds were created from a mixture containing this polyurethane and 0%, 10%, 20%, or 30% type I collagen. The resulting scaffolds were found to have open, interconnected pores (from 7 to >100 um) and porosities from 58% to 86% depending on the polyurethane/collagen ratio. The scaffolds were also flexible with breaking strains of 82–443% and tensile strengths of 0.97–4.11 MPa depending on preparation conditions. Scaffold degradation was significantly increased when collagenase was introduced into an incubating buffer in a manner that was dependent on the mass fraction of collagen present in the scaffold. Mass losses could be varied from 15% to 59% over 8 weeks. When culturing umbilical artery smooth muscle cells on these scaffolds higher cell numbers were observed over a 4-week culture period in scaffolds containing collagen. In summary, a strong and flexible scaffold system has been developed that can degrade by both hydrolysis and collagenase degradation pathways, as well as support cell growth. This scaffold possesses properties that would make it attractive for future use in soft tissue applications where such mechanical and biological features would be advantageous. PMID:16826792

  8. Design and characterization of core-shell mPEG-PLGA composite microparticles for development of cell-scaffold constructs.

    PubMed

    Wen, Yanhong; Gallego, Monica Ramos; Nielsen, Lene Feldskov; Jorgensen, Lene; Møller, Eva Horn; Nielsen, Hanne Mørck

    2013-09-01

    Appropriate scaffolds capable of providing suitable biological and structural guidance are of great importance to generate cell-scaffold constructs for cell-based tissue engineering. The aim of the present study was to develop composite microparticles with a structure to provide functionality as a combined drug delivery/scaffold system. Composite microparticles were produced by incorporating either alginate/dermatan sulfate (Alg/DS) or alginate/chitosan/dermatan sulfate (Alg/CS/DS) particles in mPEG-PLGA microparticles using coaxial ultrasonic atomization. The encapsulation and distribution of Alg/DS or Alg/CS/DS particles in the mPEG-PLGA microparticles were significantly dependent on the operating conditions, including the flow rate ratio (Qout/Qin) and the viscosity of the polymer solutions (Vout, Vin) between the outer and the inner feeding channels. The core-shell composite microparticles containing the Alg/DS particles or the Alg/CS/DS particles displayed 40% and 65% DS release in 10 days, respectively, as compared to the DS directly loaded microparticles showing 90% DS release during the same time interval. The release profiles of DS correlate with the cell proliferation of fibroblasts, i.e. more sustainable cell growth was induced by the DS released from the core-shell composite microparticles comprising Alg/CS/DS particles. After seeding fibroblasts onto the composite microparticles, excellent cell adhesion was observed, and a successful assembly of the cell-scaffold constructs was induced within 7 days. Therefore, the present study demonstrates a novel strategy for fabrication of core-shell composite microparticles comprising additional particulate drug carriers in the core, which provides controlled delivery of DS and favorable cell biocompatibility; an approach to potentially achieve cell-based tissue regeneration.

  9. Structure-property-processing correlations in freeze-cast composite scaffolds.

    PubMed

    Hunger, Philipp M; Donius, Amalie E; Wegst, Ulrike G K

    2013-05-01

    Surprisingly few reports have been published, to date, on the structure-property-processing correlations observed in freeze-cast materials directionally solidified from polymer solutions, or ceramic or metal slurries. The studies that exist focus on properties of sintered ceramics, that is materials whose structure was altered by further processing. In this contribution, we report first results on correlations observed in alumina-chitosan-gelatin composites, which were chosen as a model system to test and compare the effect of particle size and processing parameters on their mechanical properties at a specific composition. Our study reveals that highly porous (>90%) hybrid materials can be manufactured by freeze casting, through the self-assembly of a polymer and a ceramic phase that occurs during directional solidification, without the need of additional processing steps such as sintering or infiltration. It further illustrates that the properties of freeze-cast hybrid materials can independently be tailored at two levels of their structural hierarchy, allowing for the simultaneous optimization of both mechanical and structural requirements. An increase in freezing rate resulted in decreases in lamellar spacing, cell wall thickness, pore aspect ratio and cross-sectional area, as well as increases in both Young's modulus and compressive yield strength. The mechanical properties of the composite scaffolds increased with an increasing particle size. The results show that both structure and mechanical properties of the freeze-cast composites can be custom-designed and that they are thus ideally suited for a large variety of applications that require high porosity at low or medium load-bearing capacity.

  10. Ceramic composites as matrices and scaffolds for drug delivery in tissue engineering.

    PubMed

    Habraken, W J E M; Wolke, J G C; Jansen, J A

    2007-05-30

    Ceramic composites and scaffolds are popular implant materials in the field of dentistry, orthopedics and plastic surgery. For bone tissue engineering especially CaP-ceramics or cements and bioactive glass are suitable implant materials due to their osteoconductive properties. In this review the applicability of these ceramics but also of ceramic/polymer composites for bone tissue engineering is discussed, and in particular their use as drug delivery systems. Overall, the high density and slow biodegradability of ceramics is not beneficial for tissue engineering purposes. To address these issues, macroporosity can be introduced often in combination with osteoinductive growth factors and cells. Ceramics are good carriers for drugs, in which release patterns are strongly dependent on the chemical consistency of the ceramic, type of drug and drug loading. Biodegradable polymers like polylactic acid, gelatin or chitosan are used as matrices for ceramic particles or as adjuvant to calcium phosphate cements. The use of these polymers can introduce a tailored biodegradation/drug release to the ceramic material.

  11. Electrochemical properties of tungsten sulfide–carbon composite microspheres prepared by spray pyrolysis

    PubMed Central

    Choi, Seung Ho; Boo, Sung Jin; Lee, Jong-Heun; Kang, Yun Chan

    2014-01-01

    Tungsten sulfide (WS2)–carbon composite powders with superior electrochemical properties are prepared by a two-step process. WO3-carbon composite powders were first prepared by conventional spray pyrolysis, and they were then sulfidated to form WS2-carbon powders. Bare WS2 powders are also prepared by sulfidation of bare WO3 powders obtained by spray pyrolysis. Stacked graphitic layers could not be found in the bare WS2 and WS2–carbon composite powders. The amorphous bare WS2 and WS2–carbon composite powders have Brunauer–Emmett–Teller (BET) surface areas of 2.8 and 4 m2 g−1, respectively. The initial discharge and charge capacities of the WS2–carbon composite powders at a current density of 100 mA g−1 are 1055 and 714 mA h g−1, respectively, and the corresponding initial Coulombic efficiency is 68%. On the other hand, the initial discharge and charge capacities of the bare WS2 powders are 514 and 346 mA h g−1, respectively. The discharge capacities of the WS2–carbon composite powders for the 2nd and 50th cycles are 716 and 555 mA h g−1, respectively, and the corresponding capacity retention measured after first cycle is 78%. PMID:25169439

  12. Filling Porous Microspheres With Magnetic Material

    NASA Technical Reports Server (NTRS)

    Chang, Manchium; Colvin, Michael S.

    1990-01-01

    New process produces magnetic microspheres with controllable sizes, compositions, and properties for use in medical diagnostic tests, biological research, and chemical processes. Paramagnetic microspheres also made with process. Porous plastic microspheres prepared by polymerization of monomer in diluent by cross-linking agent. When diluent removed, it leaves tiny pores throughout polymerized spheres. Size and distribution of pores determined by amount and type of diluent and cross-linking agent.

  13. Formation of methotrexate-PLLA-PEG-PLLA composite microspheres by microencapsulation through a process of suspension-enhanced dispersion by supercritical CO2

    PubMed Central

    Chen, Ai-Zheng; Wang, Guang-Ya; Wang, Shi-Bin; Li, Li; Liu, Yuan-Gang; Zhao, Chen

    2012-01-01

    Background The aim of this study was to improve the drug loading, encapsulation efficiency, and sustained-release properties of supercritical CO2-based drug-loaded polymer carriers via a process of suspension-enhanced dispersion by supercritical CO2 (SpEDS), which is an advanced version of solution-enhanced dispersion by supercritical CO2 (SEDS). Methods Methotrexate nanoparticles were successfully microencapsulated into poly (L-lactide)-poly(ethylene glycol)-poly(L-lactide) (PLLA-PEG-PLLA) by SpEDS. Methotrexate nanoparticles were first prepared by SEDS, then suspended in PLLA-PEG-PLLA solution, and finally microencapsulated into PLLA-PEG-PLLA via SpEDS, where an “injector” was utilized in the suspension delivery system. Results After microencapsulation, the composite methotrexate (MTX)-PLLA-PEG-PLLA microspheres obtained had a mean particle size of 545 nm, drug loading of 13.7%, and an encapsulation efficiency of 39.2%. After an initial burst release, with around 65% of the total methotrexate being released in the first 3 hours, the MTX-PLLA-PEG-PLLA microspheres released methotrexate in a sustained manner, with 85% of the total methotrexate dose released within 23 hours and nearly 100% within 144 hours. Conclusion Compared with a parallel study of the coprecipitation process, microencapsulation using SpEDS offered greater potential to manufacture drug-loaded polymer microspheres for a drug delivery system. PMID:22787397

  14. Evaluation of the effects of nano-TiO2 on bioactivity and mechanical properties of nano bioglass-P3HB composite scaffold for bone tissue engineering.

    PubMed

    Bakhtiyari, Sanaz Soleymani Eil; Karbasi, Saeed; Monshi, Ahmad; Montazeri, Mahbobeh

    2016-01-01

    To emulate bone structure, porous composite scaffold with suitable mechanical properties should be designed. In this research the effects of nano-titania (nTiO2) on the bioactivity and mechanical properties of nano-bioglass-poly-3-hydroxybutyrate (nBG/P3HB)-composite scaffold were evaluated. First, nBG powder was prepared by melting method of pure raw materials at a temperature of 1400 °C and then the porous ceramic scaffold of nBG/nTiO2 with 30 wt% of nBG containing different weight ratios of nTiO2 (3, 6, and 9 wt% of nTiO2 with grain size of 35-37 nm) was prepared by using polyurethane sponge replication method. Then the scaffolds were coated with P3HB in order to increase the scaffold's mechanical properties. Mechanical strength and modulus of scaffolds were improved by adding nTiO2 to nBG scaffold and adding P3HB to nBG/nTiO2 composite scaffold. The results of the compressive strength and porosity tests showed that the best scaffold is 30 wt% of nBG with 6 wt% of nTiO2 composite scaffold immersed for 30 s in P3HB with 79.5-80 % of porosity in 200-600 μm, with a compressive strength of 0.15 MPa and a compressive modulus of 30 MPa, which is a good candidate for bone tissue engineering. To evaluate the bioactivity of the scaffold, the simulated body fluid (SBF) solution was used. The best scaffold with 30 wt% of nBG, 6 wt% of P3HB and 6 wt% of nTiO2 was immersed in SBF for 4 weeks at an incubation temperature of 37 °C. The bioactivity of the scaffolds was characterized by AAS, SEM, EDXA and XRD. The results of bioactivity showed that bone-like apatite layer formed well at scaffold surface and adding nTiO2 to nBG/P3HB composite scaffold helped increase the bioactivity rate.

  15. Multifunctional polypyrrole/strontium hexaferrite composite microspheres: preparation, characterization, and properties.

    PubMed

    Jiang, Jing; Ai, Lunhong; Li, Liangchao

    2009-02-05

    Polypyrrole (PPY)/SrFe12O19 composites with tunable electrical and magnetic properties were synthesized by in situ polymerization of pyrrole in the presence of SrFe12O19 particles. The structure of PPY/SrFe12O19 composites was characterized by means of Fourier transform infrared spectroscopy and X-ray diffraction. Transmission electron microscope and scanning electron microscope images illustrated that the spherical composites consisted of SrFe12O19 hexagonal plates sheathed by PPY. In the electromagnetic measurments, it was found that the ac conductivity of SrFe12O19 particles increased while the saturation magnetization, remanent magnetization, and coercivity decreased after PPY coating; moreover, the desired electrical and magnetic properties of PPY/SrFe12O19 composites can be modulated simply by controlling the contents of SrFe12O19 particles. A possible mechanism was also proposed to interpret the formation of the PPY/SrFe12O19 composites.

  16. Scaffold-based Drug Delivery for Cartilage Tissue Regeneration.

    PubMed

    Shalumon, K T; Chen, Jyh-Ping

    2015-01-01

    Regenerative engineering is an advanced field comprising the collective benefit of biodegradable polymers with cells and tissue inducing factors. Current method of replacing the defective organ is through transplantation, but is limited due to immune rejection and availability. As a solution, new polymeric biomaterial-based three-dimensional (3D) scaffolds in combination with cells and inducing factors were aroused to fulfil the existing demands. These scaffolds apply material science, biomedical technology and translational medicine to develop functional tissue engineering constructs. Presence of small molecules and growth factors guides the cell phenotypes to specific organ development. The 3D scaffold thus could also be favorably used as carriers for various types of drugs and genes, with the release profile fine-tuned by modulation of the scaffold's morphology, porosity, and composition. An increasing trend was observed in recent years toward the combination of scaffolds and growth factors to fabricate a bioactive system, which not only provide a biomimetic biodegradable physical support for tissue growth but also explores biological signals to modulate tissue regeneration. In this review, along with general aspects of tissue engineering, we also discuss the importance of various scaffold architectures like nanofibers, hydrogels, beads, meshes, microspheres etc. in combination with specific drugs, growth factors and small molecules for cartilage regeneration. Growth factors may be incorporated into scaffolds by direct blending, physical adsorption, drop casting, surface grafting, covalent bonding, chemical immobilization, coaxial electrospinning, microparticle incorporation etc. This offers new possibilities for the development of biomimetic scaffolds that are endowed with a hierarchical architecture and sophisticated release kinetics of the growth factors. This review portrait the fundamentals of tissue engineering with emphasis on the role of inducing factors

  17. Composites containing albumin protein or cyanoacrylate adhesives and biodegradable scaffolds: I. Acute wound closure study in a rat model

    NASA Astrophysics Data System (ADS)

    Hoffman, Grant T.; Soller, Eric C.; Heintzelman, Douglas L.; Duffy, Mark T.; Bloom, Jeffrey N.; Gilmour, Travis M.; Gonnerman, Krista N.; McNally-Heintzelman, Karen M.

    2004-07-01

    Composite adhesives composed of biodegradable scaffolds impregnated with a biological or synthetic adhesive were investigated for use in wound closure as an alternative to using either one of the adhesives alone. Two different scaffold materials were investigated: (i) a synthetic biodegradable material fabricated from poly(L-lactic-co-glycolic acid); and (ii) a biological material, small intestinal sub mucosa, manufactured by Cook BioTech. The biological adhesive was composed of 50%(w/v) bovine serum albumin solder and 0.5mg/ml indocyanine green dye mixed in deionized water, and activated with an 808-nm diode laser. The synthetic adhesive was Ethicon's Dermabond, a 2-octyl-cyanoacrylate. The tensile strength of skin incisions repaired ex vivo in a rat model, by adhesive alone or in combination with a scaffold, as well as the time-to-failure, were measured and compared. The tensile strength of repairs formed using the scaffold-enhanced biological adhesives were on average, 80% stronger than their non-enhanced counterparts, with an accompanying increase in the time-to-failure of the repairs. These results support the theory that a scaffold material with an irregular surface that bridges the wound provides a stronger, more durable and consistent adhesion, due to the distribution of the tensile stress forces over the many micro-adhesions provided by the irregular surface, rather than the one large continuous adhesive contact. This theory is also supported by several previous ex vivo experiments demonstrating enhanced tensile strength of irregular versus smooth scaffold surfaces in identical tissue repairs performed on bovine thoracic aorta, liver, spleen, small intestine and lung tissue.

  18. PLGA/TCP composite scaffold incorporating bioactive phytomolecule icaritin for enhancement of bone defect repair in rabbits.

    PubMed

    Chen, S-H; Lei, M; Xie, X-H; Zheng, L-Z; Yao, D; Wang, X-L; Li, W; Zhao, Z; Kong, A; Xiao, D-M; Wang, D-P; Pan, X-H; Wang, Y-X; Qin, L

    2013-05-01

    Bone defect repair is challenging in orthopaedic clinics. For treatment of large bone defects, bone grafting remains the method of choice for the majority of surgeons, as it fills spaces and provides support to enhance biological bone repair. As therapeutic agents are desirable for enhancing bone healing, this study was designed to develop such a bioactive composite scaffold (PLGA/TCP/ICT) made of polylactide-co-glycolide (PLGA) and tricalcium phosphate (TCP) as a basic carrier, incorporating a phytomolecule icaritin (ICT), i.e., a novel osteogenic exogenous growth factor. PLGA/TCP/ICT scaffolds were fabricated as PLGA/TCP (control group) and PLGA/TCP in tandem with low/mid/high-dose ICT (LICT/MICT/HICT groups, respectively). To evaluate the in vivo osteogenic and angiogenic potentials of these bioactive scaffolds with slow release of osteogenic ICT, the authors established a 12 mm ulnar bone defect model in rabbits. X-ray and high-resolution peripheral quantitative computed tomography results at weeks 2, 4 and 8 post-surgery showed more newly formed bone within bone defects implanted with PLGA/TCP/ICT scaffolds, especially PLGA/TCP/MICT scaffold. Histological results at weeks 4 and 8 also demonstrated more newly mineralized bone in PLGA/TCP/ICT groups, especially in the PLGA/TCP/MICT group, with correspondingly more new vessel ingrowth. These findings may form a good foundation for potential clinical validation of this innovative bioactive scaffold incorporated with the proper amount of osteopromotive phytomolecule ICT as a ready product for clinical applications.

  19. In vitro study of nano-HA/PLLA composite scaffold for rabbit BMSC differentiation under TGF-β1 induction.

    PubMed

    Zhu, Weimin; Chen, Kang; Lu, Wei; Sun, Qifeng; Peng, Liangquan; Fen, Wenzhe; Li, Hao; Ou, Yangkan; Liu, Haifeng; Wang, Daping; Zeng, Yanjun

    2014-03-01

    The aim of this study is to investigate the effects of differentiation of rabbit bone marrow mesenchymal stem cells (rBMSCs) into chondrocytes induced by transforming growth factor-beta1 (TCP-β1) composite poly-1actide-co-glycolic acid/nano-hydroxyapatite (PLLA/nano-HA) to the construction of biomimetic artificial cartilage in vitro. In the low-temperature extrusion preparation of PLLA/nano-HA composite porous scaffolds, rBMSCs were isolated and cultured to third generation in vitro, induced by TGF-β1-contained special inducing system into chondrocytes, 14 d later, identified by toluidine blue and type II collagen immunohistochemistry staining, and then the differential chondrocytes composite into the PLLA/nano-HA composite porous scaffolds, using scanning electron microscopy (SEM) to observe the growth conditions and cell attachment on the composite in the 7th,14th, and 21st day and to gather cells on composite in the 7th, 14th, and 21st day of cell. RT-PCR is used to detect the expression of aggrecan (Col2A1 in mRNA) and Western blot for detection of the expression of type II collagen of the attached cells. rBMSCs can differentiate into chondrocytes when induced, and the differentiation of chondrocytes secreting GAG by toluidine blue staining and type II collagen immunohistochemistry staining was positive; SEM confirm the cells distribution evenly, stretching well in composite. RT-PCR of aggrecan, Col2A1 in mRNA, and Western-blot of type II collagen expression in the differentiation of chondrocytes have different levels. Using TGF-β1 containing special inducing system induced rBMSCs into chondrocytes, then into compounds of PLLA/nano-HA composite porous scaffolds, and cell carrier complex proliferated well and secreted the chondrocyte-specific extracellular matrix stably, successfully constructing artificial bionic in vitro.

  20. Enhancing cell migration in shape-memory alginate-collagen composite scaffolds: In vitro and ex vivo assessment for intervertebral disc repair.

    PubMed

    Guillaume, Olivier; Naqvi, Syeda Masooma; Lennon, Kerri; Buckley, Conor Timothy

    2015-04-01

    Lower lumbar disc disorders pose a significant problem in an aging society with substantial socioeconomic consequences. Both inner tissue (nucleus pulposus) and outer tissue (annulus fibrosus) of the intervertebral disc are affected by such debilitating disorders and can lead to disc herniation and lower back pain. In this study, we developed an alginate-collagen composite porous scaffold with shape-memory properties to fill defects occurring in annulus fibrosus tissue of degenerated intervertebral discs, which has the potential to be administered using minimal invasive surgery. In the first part of this work, we assessed how collagen incorporation on preformed alginate scaffolds influences the physical properties of the final composite scaffold. We also evaluated the ability of annulus fibrosus cells to attach, migrate, and proliferate on the composite alginate-collagen scaffolds compared to control scaffolds (alginate only). In vitro experiments, performed in intervertebral disc-like microenvironmental conditions (low glucose and low oxygen concentrations), revealed that for alginate only scaffolds, annulus fibrosus cells agglomerated in clusters with limited infiltration and migration capacity. In comparison, for alginate-collagen scaffolds, annulus fibrosus cells readily attached and colonized constructs, while preserving their typical fibroblastic-like cell morphology with spreading behavior and intense cytoskeleton expression. In a second part of this study, we investigated the effects of alginate-collagen scaffold when seeded with bone marrow derived mesenchymal stem cells. In vitro, we observed that alginate-collagen porous scaffolds supported cell proliferation and extracellular matrix deposition (collagen type I), with secretion amplified by the local release of transforming growth factor-β3. In addition, when cultured in ex vivo organ defect model, alginate-collagen scaffolds maintained viability of transplanted mesenchymal stem cells for up to 5

  1. Preparation, characterization and antimicrobial activity of a bio-composite scaffold containing chitosan/nano-hydroxyapatite/nano-silver for bone tissue engineering.

    PubMed

    Saravanan, Sekaran; Nethala, Sricharan; Pattnaik, Soumitri; Tripathi, Anjali; Moorthi, Ambigapathi; Selvamurugan, Nagarajan

    2011-08-01

    In this study, a bio-composite scaffold containing chitosan/nano-hydroxyapatite/nano-silver particles (CS/nHAp/nAg) was developed by freeze drying technique, followed by introduction of silver ions in controlled amount through reduction phenomenon by functional groups of chitosan. The scaffolds were characterized using SEM, FT-IR, XRD, swelling, and biodegradation studies. The testing of the prepared scaffolds with Gram-positive and Gram-negative bacterial strains showed antibacterial activity. The scaffold materials were also found to be non-toxic to rat osteoprogenitor cells and human osteosarcoma cell line. Thus, these results suggested that CS/nHAp/nAg bio-composite scaffolds have the potential in controlling implant associated bacterial infection during reconstructive surgery of bone.

  2. Laminated electrospun nHA/PHB-composite scaffolds mimicking bone extracellular matrix for bone tissue engineering.

    PubMed

    Chen, Zhuoyue; Song, Yue; Zhang, Jing; Liu, Wei; Cui, Jihong; Li, Hongmin; Chen, Fulin

    2017-03-01

    Electrospinning is an effective means to generate nano- to micro-scale polymer fibers resembling native extracellular matrix for tissue engineering. However, a major problem of electrospun materials is that limited pore size and porosity may prevent adequate cellular infiltration and tissue ingrowth. In this study, we first prepared thin layers of hydroxyapatite nanoparticle (nHA)/poly-hydroxybutyrate (PHB) via electrospinning. We then laminated the nHA/PHB thin layers to obtain a scaffold for cell seeding and bone tissue engineering. The results demonstrated that the laminated scaffold possessed optimized cell-loading capacity. Bone marrow mesenchymal stem cells (MSCs) exhibited better adherence, proliferation and osteogenic phenotypes on nHA/PHB scaffolds than on PHB scaffolds. Thereafter, we seeded MSCs onto nHA/PHB scaffolds to fabricate bone grafts. Histological observation showed osteoid tissue formation throughout the scaffold, with most of the scaffold absorbed in the specimens 2months after implantation, and blood vessels ingrowth into the graft could be observed in the graft. We concluded that electrospun and laminated nanoscaled biocomposite scaffolds hold great therapeutic potential for bone regeneration.

  3. Micro-spherical cochleate composites: method development for monodispersed cochleate system.

    PubMed

    Nagarsekar, Kalpa; Ashtikar, Mukul; Steiniger, Frank; Thamm, Jana; Schacher, Felix H; Fahr, Alfred

    2017-03-01

    Cochleates have been of increasing interest in pharmaceutical research due to their extraordinary stability. However the existing techniques used in the production of cochleates still need significant improvements to achieve sufficiently monodispersed formulations. In this study, we report a simple method for the production of spherical composite microparticles (3-5 μm in diameter) made up of nanocochleates from phosphatidylserine and calcium (as binding agent). Formulations obtained from the proposed method were evaluated using electron microscopy and small angle X-ray scattering and were compared with conventional cochleate preparation techniques. In this new method, an ethanolic lipid solution and aqueous solution of a binding agent is subjected to rapid and uniform mixing with a microfluidic device. The presence of high concentration of organic solvent promotes the formation of composite microparticles made of nanocochleates. This simple methodology eliminates elaborate preparation methods, while providing a monodisperse cochleate system with analogous quality.

  4. Enhanced bone tissue regeneration by antibacterial and osteoinductive silica-HACC-zein composite scaffolds loaded with rhBMP-2.

    PubMed

    Zhou, Panyu; Xia, Yan; Cheng, Xiaosong; Wang, Panfeng; Xie, Yang; Xu, Shuogui

    2014-12-01

    Next-generation orthopedic implants with both osteoinductivity and antibacterial ability are greatly needed. In the present study, biodegradable rhBMP-2 loaded zein-based scaffolds with a macroporous structure were synthesized, and SBA-15 nanoparticles and hydroxypropyltrimethyl ammonium chloride chitosan (HACC) were incorporated into the scaffolds to produce an anti-infective composite scaffold for delivery of osteogenic factors that facilitate the functional repair of bone defects. The silica/HACC/zein scaffolds developed here showed bioactivity, biocompatibility, and effective antibacterial activity. Confocal laser scanning microscopy (CLSM) was used to quantitatively measure the bactericidal efficacy with respect to bacterial adhesion. Results showed that the sample zein-HACC-S20 exhibited long-lasting antibacterial activity against Escherichia coli and Staphylococcus aureus up to 5 d. At a low dosage of rhBMP-2 (ca. 80 μg), the scaffolds released rhBMP-2 protein efficiently at a relatively slow rate, even after 27 d. An ALP activity and ECM mineralization assay showed that the zein-HACC-S20 scaffolds exhibited significant early osteogenic differentiation by generating enhanced ALP product on day 14 and ECM mineralization on day 21. In a mouse model of thigh muscle pouches, zein-S20 and zein-HACC-S20 groups resulted in obvious bone formation and gave more extensive mineralization to the implants than silica free groups, indicating effective bone induction in vivo. In a rabbit model of critical-sized radius bone defects (20 mm in length and 5 mm in diameter), the bone defects were almost fully repaired and bone marrow cavity recanalization was detectable by 3D micro-CT technique and histological analysis after 12 weeks. In this way, the zein-HACC-S20 scaffolds were proven to significantly promote the bone repair. They also demonstrated considerable promise for tissue engineering. Silica/HACC/zein scaffolds with both antibacterial activity and the ability to

  5. Characterization of fabricated three dimensional scaffolds of bioceramic-polymer composite via microstereolithography technique

    NASA Astrophysics Data System (ADS)

    Talib, Marina; Covington, James A.; Bolarinwa, Aminat

    2014-02-01

    Microstereolithography is a method used for rapid prototyping of polymeric and ceramic components. This technique converts a computer-aided design (CAD) to a three dimensional (3D) model, and enables layer per layer fabrication curing a liquid resin with UV-light or laser source. The aim of this project was to formulate photocurable polymer reinforced with synthesized calcium pyrophosphate (CPP), and to fabricate a 3D scaffolds with optimum mechanical properties for specific tissue engineering applications. The photocurable ceramic suspension was prepared with acrylate polyester, multifunctional acrylate monomer with the addition of 50-70wt% of CPP, photoinitiators and photoinhibitors. The 3D structure of disc (5 mm height × 4 mm diameter) was successfully fabricated using Envisiontec Perfactory3® . They were then sintered at high temperature for polymer removal, to obtain a ceramic of the desired porosity. The density increased to more than 35% and the dimensional shrinkage after sintering were 33%. The discs were then subjected compressive measurement, biodegradation and bioactivity test. Morphology and CPP content of the sintered polymer was investigated with SEM and XRD, respectively. The addition of CPP coupled with high temperature sintering, had a significant effect on the compressive strength exhibited by the bioceramic. The values are in the range of cancellous bone (2-4 MPa). In biodegradation and bioactivity test, the synthesized CPP induced the formation of apatite layer and its nucleation onto the composite surface.

  6. Design of composite scaffolds and three-dimensional shape analysis for tissue-engineered ear

    PubMed Central

    Cervantes, Thomas M.; Bassett, Erik K.; Tseng, Alan; Kimura, Anya; Roscioli, Nick; Randolph, Mark A.; Vacanti, Joseph P.; Hadlock, Theresa A.; Gupta, Rajiv; Pomerantseva, Irina; Sundback, Cathryn A.

    2013-01-01

    Engineered cartilage is a promising option for auricular reconstruction. We have previously demonstrated that a titanium wire framework within a composite collagen ear-shaped scaffold helped to maintain the gross dimensions of the engineered ear after implantation, resisting the deformation forces encountered during neocartilage maturation and wound healing. The ear geometry was redesigned to achieve a more accurate aesthetic result when implanted subcutaneously in a nude rat model. A non-invasive method was developed to assess size and shape changes of the engineered ear in three dimensions. Computer models of the titanium framework were obtained from CT scans before and after implantation. Several parameters were measured including the overall length, width and depth, the minimum intrahelical distance and overall curvature values for each beam section within the framework. Local curvature values were measured to gain understanding of the bending forces experienced by the framework structure in situ. Length and width changed by less than 2%, whereas the depth decreased by approximately 8% and the minimum intrahelical distance changed by approximately 12%. Overall curvature changes identified regions most susceptible to deformation. Eighty-nine per cent of local curvature measurements experienced a bending moment less than 50 µN-m owing to deformation forces during implantation. These quantitative shape analysis results have identified opportunities to improve shape fidelity of engineered ear constructs. PMID:23904585

  7. Design of composite scaffolds and three-dimensional shape analysis for tissue-engineered ear.

    PubMed

    Cervantes, Thomas M; Bassett, Erik K; Tseng, Alan; Kimura, Anya; Roscioli, Nick; Randolph, Mark A; Vacanti, Joseph P; Hadlock, Theresa A; Gupta, Rajiv; Pomerantseva, Irina; Sundback, Cathryn A

    2013-10-06

    Engineered cartilage is a promising option for auricular reconstruction. We have previously demonstrated that a titanium wire framework within a composite collagen ear-shaped scaffold helped to maintain the gross dimensions of the engineered ear after implantation, resisting the deformation forces encountered during neocartilage maturation and wound healing. The ear geometry was redesigned to achieve a more accurate aesthetic result when implanted subcutaneously in a nude rat model. A non-invasive method was developed to assess size and shape changes of the engineered ear in three dimensions. Computer models of the titanium framework were obtained from CT scans before and after implantation. Several parameters were measured including the overall length, width and depth, the minimum intrahelical distance and overall curvature values for each beam section within the framework. Local curvature values were measured to gain understanding of the bending forces experienced by the framework structure in situ. Length and width changed by less than 2%, whereas the depth decreased by approximately 8% and the minimum intrahelical distance changed by approximately 12%. Overall curvature changes identified regions most susceptible to deformation. Eighty-nine per cent of local curvature measurements experienced a bending moment less than 50 µN-m owing to deformation forces during implantation. These quantitative shape analysis results have identified opportunities to improve shape fidelity of engineered ear constructs.

  8. Microsphere Composites of Nano-Al and Nanothermite: An Approach to Better Utilization of Nanomaterials

    DTIC Science & Technology

    2014-01-01

    34 Journal of Materials Chemistry, Vol. 21, No. 26, 2011, pp. 9400-9405. 6Jian, G. Q., Liu L., and Zachariah, R. M., "Facile Aerosol Route to Hollow CuO...1341–1346. 7Ali, A. N., Son, S. F., Hiskey, M. A., and Naud, D. L., "Novel high nitrogen propellant use in solid fuel micropropulsion," Journal of...Composites (Al/MoO3, Al/WO3, Al/CuO, and B12O3),” Journal of Propulsion and Power, Vol. 23, No. 4, July.-Aug. 2007, pp. 707-714. 11Ilyushin, M. A

  9. Improving bone repair of femoral and radial defects in rabbit by incorporating PRP into PLGA/CPC composite scaffold with unidirectional pore structure.

    PubMed

    He, Fupo; Chen, Yan; Li, Jiyan; Lin, Bomiao; Ouyang, Yi; Yu, Bo; Xia, Yuanyou; Yu, Bo; Ye, Jiandong

    2015-04-01

    In this study, a platelet-rich plasma poly(lactic-co-glycolic acid) (PRP-PLGA)/calcium phosphate cement (CPC) composite scaffold was prepared by incorporating PRP into PLGA/CPC scaffold with unidirectional pore structure, which was fabricated by the unidirectional freeze casting of CPC slurry and the following infiltration of PLGA. The results from in vitro cell experiments and in vivo implantation in femoral defects manifested that incorporation of PRP into PLGA/CPC scaffold improved in vitro cell response (cell attachment, proliferation, and differentiation), and markedly boosted bone formation, angiogenesis and material degradation. The incorporation of PRP into scaffold showed more outstanding improvement in osteogenesis as the scaffolds were used to repair the segmental radial defects, especially at the early stage. The new bone tissues grew along the unidirectional lamellar pores of scaffold. At 12 weeks postimplantation, the segmental radial defects treated with PRP-PLGA/CPC scaffold had almost recuperated, whereas treated with the scaffold without PRP was far from healed. Taken together, the PRP-PLGA/CPC scaffold with unidirectional pore structure is a promising candidate to repair bone defects at various sites.

  10. PDLA/PLLA and PDLA/PCL nanofibers with a chitosan-based hydrogel in composite scaffolds for tissue engineered cartilage.

    PubMed

    Wright, L D; McKeon-Fischer, K D; Cui, Z; Nair, L S; Freeman, J W

    2014-12-01

    Osteoarthritis (OA) is the most prevalent musculoskeletal disease in humans, causing pain, loss of joint motility and function, and severely reducing the standard of living of patients. Cartilage tissue engineering attempts to repair the damaged tissue of individuals suffering from OA by providing mechanical support to the joint as new tissue regenerates. The aim of this study was to create composite three dimensional scaffolds comprised of electrospun poly(D,L-lactide)/poly(L-lactide) (PDLA/PLLA) or poly(D,L-lactide)/polycaprolactone (PDLA/PCL) with salt leached pores and an embedded chitosan hydrogel to determine the potential of these scaffolds for cartilage tissue engineering. PDLA/PLLA-hydrogel scaffolds displayed the largest compressive moduli followed by PDLA/PCL-hydrogel scaffolds. Dynamic mechanical tests showed that the PDLA/PLLA scaffolds had no appreciable recovery while PDLA/PCL scaffolds did exhibit some recovery. Primary canine chondrocytes produced both collagen type II and proteoglycans (primary components of extracellular matrix in cartilage) while being cultured on scaffolds composed of electrospun PDLA/PCL. As a result, a composite electrospun embedded hydrogel scaffold shows promise for treating individuals suffering from OA.

  11. A Biomimetic Silk Fibroin/Sodium Alginate Composite Scaffold for Soft Tissue Engineering

    PubMed Central

    Wang, Yiyu; Wang, Xinyu; Shi, Jian; Zhu, Rong; Zhang, Junhua; Zhang, Zongrui; Ma, Daiwei; Hou, Yuanjing; Lin, Fei; Yang, Jing; Mizuno, Mamoru

    2016-01-01

    A cytocompatible porous scaffold mimicking the properties of extracellular matrices (ECMs) has great potential in promoting cellular attachment and proliferation for tissue regeneration. A biomimetic scaffold was prepared using silk fibroin (SF)/sodium alginate (SA) in which regular and uniform pore morphology can be formed through a facile freeze-dried method. The scanning electron microscopy (SEM) studies showed the presence of interconnected pores, mostly spread over the entire scaffold with pore diameter around 54~532 μm and porosity 66~94%. With significantly better water stability and high swelling ratios, the blend scaffolds crosslinked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) provided sufficient time for the formation of neo-tissue and ECMs during tissue regeneration. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) results confirmed random coil structure and silk I conformation were maintained in the blend scaffolds. What’s more, FI-TR spectra demonstrated crosslinking reactions occurred actually among EDC, SF and SA macromolecules, which kept integrity of the scaffolds under physiological environment. The suitable pore structure and improved equilibrium swelling capacity of this scaffold could imitate biochemical cues of natural skin ECMs for guiding spatial organization and proliferation of cells in vitro, indicating its potential candidate material for soft tissue engineering. PMID:27996001

  12. Development of core-shell coaxially electrospun composite PCL/chitosan scaffolds.

    PubMed

    Surucu, Seda; Turkoglu Sasmazel, Hilal

    2016-11-01

    This study was related to combining of synthetic Poly (ε-caprolactone) (PCL) and natural chitosan polymers to develop three dimensional (3D) PCL/chitosan core-shell scaffolds for tissue engineering applications. The scaffolds were fabricated with coaxial electrospinning technique and the characterizations of the samples were done by thickness and contact angle (CA) measurements, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray Photoelectron Spectroscopy (XPS) analyses, mechanical and PBS absorption and shrinkage tests. The average inter-fiber diameter values were calculated for PCL (0.717±0.001μm), chitosan (0.660±0.007μm) and PCL/chitosan core-shell scaffolds (0.412±0.003μm), also the average inter-fiber pore size values exhibited decreases of 66.91% and 61.90% for the PCL and chitosan scaffolds respectively, compared to PCL/chitosan core-shell ones. XPS analysis of the PCL/chitosan core-shell structures exhibited the characteristic peaks of PCL and chitosan polymers. The cell culture studies (MTT assay, Confocal Laser Scanning Microscope (CLSM) and SEM analyses) carried out with L929 ATCC CCL-1 mouse fibroblast cell line proved that the biocompatibility performance of the scaffolds. The obtained results showed that the created micro/nano fibrous structure of the PCL/chitosan core-shell scaffolds in this study increased the cell viability and proliferation on/within scaffolds.

  13. Comparison of three-dimensional printing and vacuum freeze-dried techniques for fabricating composite scaffolds.

    PubMed

    Sun, Kai; Li, Ruixin; Jiang, Wenxue; Sun, Yufu; Li, Hui

    2016-09-02

    In this study, the performances of different preparation methods of the scaffolds were analyzed for chondrocyte tissue engineering. Silk fibroin/collagen (SF/C) was fabricated using a vacuum freeze-dried technique and by 3D printing. The porosity, water absorption expansion rates, mechanical properties, and pore sizes of the resulting materials were evaluated. The proliferation and metabolism of the cells was detected at different time points using an MTT assay. Cell morphologies and distributions were observed by histological analysis and scanning electron microscopy (SEM). The porosity, water absorption expansion rate, and Young's modulus of the material obtained via 3D printing were significantly higher than those obtained by the freeze-dried method, while the pore size did not differ significantly between the two methods. MTT assay results showed that the metabolism of cells seeded on the 3D printed scaffolds was more viable than the metabolism on the freeze-dried material. H&E staining of the scaffolds revealed that the number of cells in the 3D printed scaffold was higher in comparison to a similar measurement on the freeze-dried material. Consequently, stem cells grew well inside the 3D printed scaffolds, as measured by SEM, while the internal structure of the freeze-dried scaffold was disordered. Compared with the freeze-dried technique, the 3D printed scaffold exhibited better overall performance and was more suitable for cartilage tissue engineering.

  14. Tissue response and biodegradation of composite scaffolds prepared from Thai silk fibroin, gelatin and hydroxyapatite.

    PubMed

    Tungtasana, Hathairat; Shuangshoti, Somruetai; Shuangshoti, Shanop; Kanokpanont, Sorada; Kaplan, David L; Bunaprasert, Tanom; Damrongsakkul, Siriporn

    2010-12-01

    This work aimed to investigate tissue responses and biodegradation, both in vitro and in vivo, of four types of Bombyx mori Thai silk fibroin based-scaffolds. Thai silk fibroin (SF), conjugated gelatin/Thai silk fibroin (CGSF), hydroxyapatite/Thai silk fibroin (SF4), and hydroxyapatite/conjugated gelatin/Thai silk fibroin (CGSF4) scaffolds were fabricated using salt-porogen leaching, dehydrothermal/chemical crosslinking and an alternate soaking technique for mineralization. In vitro biodegradation in collagenase showed that CGSF scaffolds had the slowest biodegradability, due to the double crosslinking by dehydrothermal and chemical treatments. The hydroxyapatite deposited from alternate soaking separated from the surface of the protein scaffolds when immersed in collagenase. From in vivo biodegradation studies, all scaffolds could still be observed after 12 weeks of implantation in subcutaneous tissue of Wistar rats and also following ISO10993-6: Biological evaluation of medical devices. At 2 and 4 weeks of implantation the four types of Thai silk fibroin based-scaffolds were classified as "non-irritant" to "slight-irritant", compared to Gelfoam(®) (control samples). These natural Thai silk fibroin-based scaffolds may provide suitable biomaterials for clinical applications.

  15. In vitro mineralization of MC3T3-E1 osteoblast-like cells on collagen/nano-hydroxyapatite scaffolds coated carbon/carbon composites.

    PubMed

    Cao, Sheng; Li, Hejun; Li, Kezhi; Lu, Jinhua; Zhang, Leilei

    2016-02-01

    Collagen/nano-hydroxyapatite (collagen/nHA) scaffolds were successfully prepared on carbon/carbon composites as bioactive films using the layer-by-layer coating method. Surface characterizations of collagen/nHA scaffolds were detected by scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Compressive strengths of the scaffolds were evaluated by a universal test machine. In vitro biological performances were determined using scaffolds seeded with MC3T3-E1 osteoblasts-like cells and cultured in mineralization medium for up to 21 days. In addition, cellular morphologies and several related gene expressions of MC3T3-E1 cells in the scaffolds were also evaluated. Chemical and morphological analysis showed that the scaffolds had uniform pore sizes and unified phase composition. Mechanical testing indicated that the collagen/nHA scaffolds had the highest compressive strength in 50% of strain condition when the proportion of collagen and nano-hydroxyapatite was 1:3. Cellular morphology observations and cytology tests indicated that MC3T3-E1 cells were adhered on these scaffolds and proliferated. SEM photographs and gene expressions showed that mineralized MC3T3-E1 cells and newly formed extra cellular matrix (ECM) filled up the pores of the scaffolds after the 3-week mineralization inducement. Nano-sized apatite particles were secreted from MC3T3-E1 cells and combined with the reconstructed ECM. Collectively, collagen/nHA scaffolds provided C/C composites with a biomimetic surface for cell adhesion, proliferation and mineralized extra cellular matrices formation.

  16. Fluorescent microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, A.

    1978-01-01

    Latex particles with attached antibodies have potential biochemical and environmental applications. Human red blood cells and lymphocytes have been labeled with fluorescent microspheres by either direct or indirect immunological technique. Immunolatex spheres can also be used for detecting and localizing specific cell surface receptors. Hormones and toxins may also be bondable.

  17. Cross-linked polyvinyl pyridine coated glass particle catalyst support and aqueous composition or polyvinyl pyridine adducted microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

    1981-01-01

    Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agent provides higher surface area beads. Addition of monomers such as hydroxyethylmethacrylate acrylamide or methacrylamide increases hydrophilic properties and surface area of the beads. High surface area catalytic supports are formed in the presence of controlled pore glass substrate.

  18. Exploring the dark side of MTT viability assay of cells cultured onto electrospun PLGA-based composite nanofibrous scaffolding materials.

    PubMed

    Qi, Ruiling; Shen, Mingwu; Cao, Xueyan; Guo, Rui; Tian, Xuejiao; Yu, Jianyong; Shi, Xiangyang

    2011-07-21

    One major method used to evaluate the biocompatibility of porous tissue engineering scaffolding materials is MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The MTT cell viability assay is based on the absorbance of the dissolved MTT formazan crystals formed in living cells, which is proportional to the number of viable cells. Due to the strong dye sorption capability of porous scaffolding materials, we propose that the cell viability determined from the MTT assay is likely to give a false negative result. In this study, we aim to explore the effect of the adsorption of MTT formazan on the accuracy of the viability assay of cells cultured onto porous electrospun poly(lactic-co-glycolic acid) (PLGA) nanofibers, HNTs (halloysite nanotubes)/PLGA, and CNTs (multiwalled carbon nanotubes)/PLGA composite nanofibrous mats. The morphology of electrospun nanofibers and L929 mouse fibroblasts cultured onto the nanofibrous scaffolds were observed using scanning electron microscopy. The viability of cells proliferated for 3 days was evaluated through the MTT assay. In the meantime, the adsorption of MTT formazan onto the same electrospun nanofibers was evaluated and the standard concentration-absorbance curve was obtained in order to quantify the contribution of the adsorbed MTT formazan during the MTT cell viability assay. We show that the PLGA, and the HNTs- or CNTs-doped PLGA nanofibers display appreciable MTT formazan dye sorption, corresponding to 35.6-50.2% deviation from the real cell viability assay data. The better dye sorption capability of the nanofibers leads to further deviation from the real cell viability. Our study gives a general insight into accurate MTT cytotoxicity assessment of various porous tissue engineering scaffolding materials, and may be applicable to other colorimetric assays for analyzing the biological properties of porous scaffolding materials.

  19. Design and characterization of a conductive nanostructured polypyrrole-polycaprolactone coated magnesium/PLGA composite for tissue engineering scaffolds.

    PubMed

    Liu, Haixia; Wang, Ran; Chu, Henry K; Sun, Dong

    2015-09-01

    A novel biodegradable and conductive composite consisting of magnesium (Mg), polypyrrole-block-ploycaprolactone (PPy-PCL), and poly(lactic-co-glycolic acid) (PLGA) is synthesized in a core-shell-skeleton manner for tissue engineering applications. Mg particles in the composite are first coated with a conductive nanostructured PPy-PCL layer for corrosion resistance via the UV-induced photopolymerization method. PLGA matrix is then added to tailor the biodegradability of the resultant composite. Composites with different composition ratios are examined through experiments, and their material properties are characterized. The in vitro experiments on culture of 293FT-GFP cells show that the composites are suitable for cell growth and culture. Biodegradability of the composite is also evaluated. By adding PLGA matrix to the composite, the degrading time of the composite can last for more than eight weeks, hence providing a longer period for tissue formation as compared to Mg composites or alloys. The findings of this research will offer a new opportunity to utilize a conductive, nanostructured-coated Mg/PLGA composite as the scaffold material for implants and tissue regeneration.

  20. Maximizing the encapsulation efficiency and the bioavailability of controlled-release cetirizine microspheres using Draper–Lin small composite design

    PubMed Central

    El-Say, Khalid Mohamed

    2016-01-01

    This study was aimed at developing a controlled-release cetirizine hydrochloride (CTZ)-loaded polymethacrylate microsphere by optimization technique using software-based response surface methodology. The emulsion solvent evaporation method was utilized in the preparation of microspheres. Four process variables were selected, namely, Eudragit RLPO loading percentage in total polymer, the emulsifier hydrophilic lipophilic balance (HLB), the antitacking percentage, and the dispersed phase volume. The desired responses were particle size, angle of repose, production yield, encapsulation efficiency, loading capacity, initial drug release, and the time for 85% of drug release from the microspheres. Optimization was carried out by fitting the experimental data to the software program (Statgraphics Centurion XV). Moreover, 18 batches were subjected to various characterization tests required for the production of dosage form. The pharmacokinetic parameters were evaluated after the oral administration of 10 mg CTZ in both optimized formulation and commercial product on healthy human volunteers using a double-blind, randomized, cross-over design. The optimized formulation showed satisfactory yield (84.43%) and drug encapsulation efficiency (87.1%). Microspheres were of spherical shape, smooth surface, and good flowability with an average size of 142.3 μm. The developed optimized batch of microspheres ensured 28.87% initial release after 2 hours, and the release of CTZ extended for >12 hours. In addition, the relative bioavailability of the optimized formulation was 165.5% with respect to the marketed CTZ tablets indicating a significant enhancement of CTZ bioavailability. Thus, there is an expectation to decrease the administered dose and the frequency of administration, and subsequently minimize the adverse effects that are faced by the patient during the treatment. PMID:26966353

  1. Maximizing the encapsulation efficiency and the bioavailability of controlled-release cetirizine microspheres using Draper-Lin small composite design.

    PubMed

    El-Say, Khalid Mohamed

    2016-01-01

    This study was aimed at developing a controlled-release cetirizine hydrochloride (CTZ)-loaded polymethacrylate microsphere by optimization technique using software-based response surface methodology. The emulsion solvent evaporation method was utilized in the preparation of microspheres. Four process variables were selected, namely, Eudragit RLPO loading percentage in total polymer, the emulsifier hydrophilic lipophilic balance (HLB), the antitacking percentage, and the dispersed phase volume. The desired responses were particle size, angle of repose, production yield, encapsulation efficiency, loading capacity, initial drug release, and the time for 85% of drug release from the microspheres. Optimization was carried out by fitting the experimental data to the software program (Statgraphics Centurion XV). Moreover, 18 batches were subjected to various characterization tests required for the production of dosage form. The pharmacokinetic parameters were evaluated after the oral administration of 10 mg CTZ in both optimized formulation and commercial product on healthy human volunteers using a double-blind, randomized, cross-over design. The optimized formulation showed satisfactory yield (84.43%) and drug encapsulation efficiency (87.1%). Microspheres were of spherical shape, smooth surface, and good flowability with an average size of 142.3 μm. The developed optimized batch of microspheres ensured 28.87% initial release after 2 hours, and the release of CTZ extended for >12 hours. In addition, the relative bioavailability of the optimized formulation was 165.5% with respect to the marketed CTZ tablets indicating a significant enhancement of CTZ bioavailability. Thus, there is an expectation to decrease the administered dose and the frequency of administration, and subsequently minimize the adverse effects that are faced by the patient during the treatment.

  2. 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.

  3. Electrophoretic Deposition of Dexamethasone-Loaded Mesoporous Silica Nanoparticles onto Poly(L-Lactic Acid)/Poly(ε-Caprolactone) Composite Scaffold for Bone Tissue Engineering.

    PubMed

    Qiu, Kexin; Chen, Bo; Nie, Wei; Zhou, Xiaojun; Feng, Wei; Wang, Weizhong; Chen, Liang; Mo, Xiumei; Wei, Youzhen; He, Chuanglong

    2016-02-17

    The incorporation of microcarriers as drug delivery vehicles into polymeric scaffold for bone regeneration has aroused increasing interest. In this study, the aminated mesoporous silica nanoparticles (MSNs-NH2) were prepared and used as microcarriers for dexamethasone (DEX) loading. Poly(l-lactic acid)/poly(ε-caprolactone) (PLLA/PCL) nanofibrous scaffold was fabricated via thermally induced phase separation (TIPS) and served as template, onto which the drug-loaded MSNs-NH2 nanoparticles were deposited by electrophoretic deposition (EPD). The physicochemical and release properties of the prepared scaffolds (DEX@MSNs-NH2/PLLA/PCL) were examined, and their osteogenic activities were also evaluated through in vitro and in vivo studies. The release of DEX from the scaffolds revealed an initial rapid release followed by a slower and sustained one. The in vitro results indicated that the DEX@MSNs-NH2/PLLA/PCL scaffold exhibited good biocompatibility to rat bone marrow-derived mesenchymal stem cells (BMSCs). Also, BMSCs cultured on the DEX@MSNs-NH2/PLLA/PCL scaffold exhibited a higher degree of osteogenic differentiation than those cultured on PLLA/PCL and MSNs-NH2/PLLA/PCL scaffolds, in terms of alkaline phosphatase (ALP) activity, mineralized matrix formation, and osteocalcin (OCN) expression. Furthermore, the in vivo results in a calvarial defect model of Sprague-Dawley (SD) rats demonstrated that the DEX@MSNs-NH2/PLLA/PCL scaffold could significantly promote calvarial defect healing compared with the PLLA/PCL scaffold. Thus, the EPD technique provides a convenient way to incorporate osteogenic agents-containing microcarriers to polymer scaffold, and thus, prepared composite scaffold could be a potential candidate for bone tissue engineering application due to its capacity for delivery of osteogenic agents.

  4. Aligned poly(L-lactic-co-e-caprolactone) electrospun microfibers and knitted structure: a novel composite scaffold for ligament tissue engineering.

    PubMed

    Vaquette, Cédryck; Kahn, Cyril; Frochot, Céline; Nouvel, Cécile; Six, Jean-Luc; De Isla, Natalia; Luo, Li-Hua; Cooper-White, Justin; Rahouadj, Rachid; Wang, Xiong

    2010-09-15

    We developed a novel technique involving knitting and electrospinning to fabricate a composite scaffold for ligament tissue engineering. Knitted structures were coated with poly(L-lactic-co-e-caprolactone) (PLCL) and then placed onto a rotating cylinder and a PLCL solution was electrospun onto the structure. Highly aligned 2-microm-diameter microfibers covered the space between the stitches and adhered to the knitted scaffolds. The stress-strain tensile curves exhibited an initial toe region similar to the tensile behavior of ligaments. Composite scaffolds had an elastic modulus (150 +/- 14 MPa) similar to the modulus of human ligaments. Biological evaluation showed that cells proliferated on the composite scaffolds and they spontaneously orientated along the direction of microfiber alignment. The microfiber architecture also induced a high level of extracellular matrix secretion, which was characterized by immunostaining. We found that cells produced collagen type I and type III, two main components found in ligaments. After 14 days of culture, collagen type III started to form a fibrous network. We fabricated a composite scaffold having the mechanical properties of the knitted structure and the morphological properties of the aligned microfibers. It is difficult to seed a highly macroporous structure with cells, however the technique we developed enabled an easy cell seeding due to presence of the microfiber layer. Therefore, these scaffolds presented attractive properties for a future use in bioreactors for ligament tissue engineering.

  5. Mechanical properties and in vitro evaluation of bioactivity and degradation of dexamethasone-releasing poly-D-L-lactide/nano-hydroxyapatite composite scaffolds.

    PubMed

    Chen, Ling; Tang, Chak Yin; Tsui, Chi Pong; Chen, Da Zhu

    2013-06-01

    The purpose of this study was to fabricate drug-release nano-composite scaffolds and perform in vitro evaluation of their mechanical properties, bioactivity, biodegradability and drug release behaviors. Porous drug-release poly-d-l-lactide (PDLLA) composite scaffolds filled with different amounts of nano-hydroxyapatite (nano-HAp) were prepared by a technique combining polymer coagulation, cold compression moulding, salt leaching and drug coating. Apatite detected on the scaffolds after exposure to a simulated body fluid showed improvement in bioactivity and the apatite formation ability through the addition of the nano-HAp content in the composites. Nano-HAp incorporation and apatite formation made a positive impact on the mechanical properties of the scaffolds; however, plasticization and degradation of PDLLA had a negative impact. The pH-compensation effect of the composite scaffolds can reduce the risk of chronic inflammation complications. The fabrication method in this study can produce scaffolds with controllable structure, appropriate mechanical properties and degradation rates for cancellous bone repair applications.

  6. Acoustic droplet–hydrogel composites for spatial and temporal control of growth factor delivery and scaffold stiffness

    PubMed Central

    Fabiilli, Mario L.; Wilson, Christopher G.; Padilla, Frédéric; Martín-Saavedra, Francisco M.; Fowlkes, J. Brian; Franceschi, Renny T.

    2013-01-01

    Wound healing is regulated by temporally and spatially restricted patterns of growth factor signaling, but there are few delivery vehicles capable of the “on-demand” release necessary for recapitulating these patterns. Recently we described a perfluorocarbon double emulsion that selectively releases a protein payload upon exposure to ultrasound through a process known as acoustic droplet vaporization (ADV). In this study, we describe a delivery system composed of fibrin hydrogels doped with growth factor-loaded double emulsion for applications in tissue regeneration. Release of immunoreactive basic fibroblast growth factor (bFGF) from the composites increased up to 5-fold following ADV and delayed release was achieved by delaying exposure to ultrasound. Releasates of ultrasound-treated materials significantly increased the proliferation of endothelial cells compared to sham controls, indicating that the released bFGF was bioactive. ADV also triggered changes in the ultrastructure and mechanical properties of the fibrin as bubble formation and consolidation of the fibrin in ultrasound-treated composites were accompanied by up to a 22-fold increase in shear stiffness. ADV did not reduce the viability of cells suspended in composite scaffolds. These results demonstrate that an acoustic droplet–hydrogel composite could have broad utility in promoting wound healing through on-demand control of growth factor release and/or scaffold architecture. PMID:23535233

  7. Gold and Hydroxyapatite Nano-Composite Scaffolds for Anterior Cruciate Ligament Reconstruction: In Vitro Characterization.

    PubMed

    Smith, S E; White, R A; Grant, D A; Grant, S A

    2016-01-01

    Current anterior cruciate ligament (ACL) graft replacement materials often fail due to the lack of biological integration. While many newly developed extracellular matrix based scaffolds show good biocompatibility they often do not entice cellular remodeling and the rebuilding of a functional ligament. We have proposed the conjugation of gold nanoparticles (AuNP) and hydroxyapatite nanoparticles (nano-HAp) to acellular tissue to enhance cell attachment and proliferation while maintaining an improved degradation resistance and open microstructure. We are the first to investigate the double conjugation of AuNP and nano-HAp onto decellularized tissue to improve the tissue remodeling response. Decellularized porcine diaphragm was crosslinked with two types of nano-HAp and amine-functionalized AuNP with 1-ethyl-3-(3-dimethlaminopropyl) carbodiimide (EDC) crosslinker. Scaffolds were characterized using electron microscopy, differential scanning calorimetry, and fibroblast assays. Results demonstrated that scaffolds with nano-HAp have increased thermal stability at low levels of crosslinking. The open microstructure of the scaffold was not compromised allowing for cell migration while still providing increased degradation resistance. The addition of < 200 nm nano-HAp decreased cell viability compared to scaffolds without nanoparticles, but the addition of AuNP to scaffolds showed enhanced cell viability in the presence of < 200 nm nano-HAp. The addition of < 40 nm nano-HAp showed an increase in cell viability compared to scaffolds crosslinked without nanoparticles. It is concluded that attaching AuNP and < 40nm nano-HAp to extracellular matrices may improve overall properties.

  8. Silk fibroin/sodium alginate composite nano-fibrous scaffold prepared through thermally induced phase-separation (TIPS) method for biomedical applications.

    PubMed

    Zhang, Haiping; Liu, Xiaotian; Yang, Mingying; Zhu, Liangjun

    2015-10-01

    To mimic the natural fibrous structure of the tissue extracellular matrix, a nano-fibrous silk fibroin (SF)/sodium alginate (SA) composite scaffold was fabricated by a thermally-induced phase-separation method. The effects of SF/SA ratio on the structure and the porosity of the composite scaffolds were examined. Scanning electron microscopy and porosity results showed that the 5SF/1SA and 3SF/1SA scaffolds possessed an excellent nano-fibrous structure and a porosity of more than 90%. Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry results indicated the physical interaction between SF and SA molecules and their good compatibility in the 5SF/1SA and 3SF/1SA scaffolds, whereas they showed less compatibility in the 1SF/1SA scaffold. Cell culture results showed that MG-63 cells can attach and grow well on the surface of the SF/SA scaffolds. The nano-fibrous SF/SA scaffold can be potentially used in tissue engineering.

  9. Co-electrospun gelatin-poly(L-lactic acid) scaffolds: modulation of mechanical properties and chondrocyte response as a function of composition.

    PubMed

    Torricelli, Paola; Gioffrè, Michela; Fiorani, Andrea; Panzavolta, Silvia; Gualandi, Chiara; Fini, Milena; Focarete, Maria Letizia; Bigi, Adriana

    2014-03-01

    Bio-synthetic scaffolds of interspersed poly(l-lactic acid) (PLLA) and gelatin (GEL) fibers are fabricated by co-electrospinning. Tailored PLLA/GEL compositions are obtained and GEL crosslinking with genipin provides for the maintenance of good fiber morphology. Scaffold tensile mechanical properties are intermediate between those of pure PLLA and GEL and vary as a function of PLLA content. Primary human chondrocytes grown on the scaffolds exhibit good proliferation and increased values of the differentiation parameters, especially for intermediate PLLA/GEL compositions. Mineralization tests enable the deposition of a uniform layer of poorly crystalline apatite onto the scaffolds, suggesting potential applications involving cartilage as well as cartilage-bone interface tissue engineering.

  10. Compression molding of aerogel microspheres

    DOEpatents

    Pekala, Richard W.; Hrubesh, Lawrence W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50-800 kg/m.sup.3 (0.05-0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization.

  11. Compression molding of aerogel microspheres

    DOEpatents

    Pekala, R.W.; Hrubesh, L.W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner is disclosed. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50--800 kg/m{sup 3} (0.05--0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization. 4 figs.

  12. Sustained Local Release of NGF from a Chitosan-Sericin Composite Scaffold for Treating Chronic Nerve Compression.

    PubMed

    Zhang, Lei; Yang, Wen; Tao, Kaixiong; Song, Yu; Xie, Hongjian; Wang, Jian; Li, Xiaolin; Shuai, Xiaoming; Gao, Jinbo; Chang, Panpan; Wang, Guobin; Wang, Zheng; Wang, Lin

    2017-02-01

    Chronic nerve compression (CNC), a common form of peripheral nerve injury, always leads to chronic peripheral nerve pain and dysfunction. Current available treatments for CNC are ineffective as they usually aim to alleviate symptoms at the acute phase with limited capability toward restoring injured nerve function. New approaches for effective recovery of CNC injury are highly desired. Here we report for the first time a tissue-engineered approach for the repair of CNC. A genipin cross-linked chitosan-sericin 3D scaffold for delivering nerve growth factor (NGF) was designed and fabricated. This scaffold combines the advantages of both chitosan and sericin, such as high porosity, adjustable mechanical properties and swelling ratios, the ability of supporting Schwann cells growth, and improving nerve regeneration. The degradation products of the composite scaffold upregulate the mRNA levels of the genes important for facilitating nerve function recovery, including glial-derived neurotrophic factor (GDNF), early growth response 2 (EGR2), and neural cell adhesion molecule (NCAM) in Schwann cells, while down-regulating two inflammatory genes' mRNA levels in macrophages, tumor necrosis factor alpha (TNF-α), and interleukin-1 beta (IL-1β). Importantly, our tissue-engineered strategy achieves significant nerve functional recovery in a preclinical CNC animal model by decreasing neuralgia, improving nerve conduction velocity (NCV), accelerating microstructure restoration, and attenuating gastrocnemius muscles dystrophy. Together, this work suggests a promising clinical alternative for treating chronic peripheral nerve compression injury.

  13. Effects of composite formulation on the mechanical properties of biodegradable poly(propylene fumarate)/bone fiber scaffolds

    PubMed Central

    Zhu, Xun; Liu, Nathan; Yaszemski, Michael J.; Lu, Lichun

    2010-01-01

    The objective of our study was to determine the effects of composite formulation on the compressive modulus and ultimate strength of a biodegradable, in situ polymerizable poly(propylene fumarate) (PPF) and bone fiber scaffold. The following parameters were investigated: the incorporation of bone fibers (either mineralized or demineralized), PPF molecular weight, N-vinyl pyrrolidinone (NVP) crosslinker amount, benzoyl peroxide (BP) initiator amount, and sodium chloride porogen amount. Eight formulations were chosen based on a resolution III two level fractional factorial design. The compressive modulus and ultimate strength of these formulations were measured on a materials testing machine. Absolute values for compressive modulus varied from 21.3 to 271 MPa and 2.8 to 358 MPa for dry and wet samples, respectively. The ultimate strength of the crosslinked composites varied from 2.1 to 20.3 MPa for dry samples and from 0.4 to 16.6 MPa for wet samples. Main effects of each parameter on the measured property were calculated. The incorporation of mineralized bone fibers and an increase in PPF molecular weight resulted in higher compressive modulus and ultimate strength. Both mechanical properties also increased as the amount of benzoyl peroxide increased or the NVP amount decreased in the formulation. Sodium chloride had a dominating effect on the increase of mechanical properties in dry samples but showed little effects in wet samples. Demineralization of bone fibers led to a decrease in the compressive modulus and ultimate strength. Our results suggest that bone fibers are appropriate as structural enforcement components in PPF scaffolds. The desired orthopaedic PPF scaffold might be obtained by changing a variety of composite formulation parameters. PMID:22034584

  14. Effects of composite formulation on the mechanical properties of biodegradable poly(propylene fumarate)/bone fiber scaffolds.

    PubMed

    Zhu, Xun; Liu, Nathan; Yaszemski, Michael J; Lu, Lichun

    2010-01-01

    The objective of our study was to determine the effects of composite formulation on the compressive modulus and ultimate strength of a biodegradable, in situ polymerizable poly(propylene fumarate) (PPF) and bone fiber scaffold. The following parameters were investigated: the incorporation of bone fibers (either mineralized or demineralized), PPF molecular weight, N-vinyl pyrrolidinone (NVP) crosslinker amount, benzoyl peroxide (BP) initiator amount, and sodium chloride porogen amount. Eight formulations were chosen based on a resolution III two level fractional factorial design. The compressive modulus and ultimate strength of these formulations were measured on a materials testing machine. Absolute values for compressive modulus varied from 21.3 to 271 MPa and 2.8 to 358 MPa for dry and wet samples, respectively. The ultimate strength of the crosslinked composites varied from 2.1 to 20.3 MPa for dry samples and from 0.4 to 16.6 MPa for wet samples. Main effects of each parameter on the measured property were calculated. The incorporation of mineralized bone fibers and an increase in PPF molecular weight resulted in higher compressive modulus and ultimate strength. Both mechanical properties also increased as the amount of benzoyl peroxide increased or the NVP amount decreased in the formulation. Sodium chloride had a dominating effect on the increase of mechanical properties in dry samples but showed little effects in wet samples. Demineralization of bone fibers led to a decrease in the compressive modulus and ultimate strength. Our results suggest that bone fibers are appropriate as structural enforcement components in PPF scaffolds. The desired orthopaedic PPF scaffold might be obtained by changing a variety of composite formulation parameters.

  15. Microwave absorption properties of lightweight absorber based on Fe50Ni50-coated poly(acrylonitrile) microspheres and reduced graphene oxide composites

    NASA Astrophysics Data System (ADS)

    Zhang, Bin; Wang, Jun; Wang, Junpeng; Huo, Siqi; Zhang, Bin; Tang, Yushan

    2016-09-01

    In this paper, we proposed a facile method to obtain the lightweight composites consisting of surface modified Fe50Ni50-coated poly(acrylonitrile) microspheres (PANS@SMF), reduced graphene oxide (RGO) and epoxy resin. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM) and vector network analyzer (VNA). Impedance matching condition and electromagnetic wave attenuation characteristic were used for the reflection loss (RL) performance of the composites. Compared with pure PANS@SMF and RGO composites, the -10 dB absorption bandwidth and the minimum RL of the hybrid composites were enhanced. The bandwidth less than -10 dB was almost 4.5 GHz in the range of 10 GHz to 14.5 GHz, with a matching thickness of 2.5 mm. The density of the hybrid composites was in the range of 0.25-0.34 g/cm3. Therefore, the hybrid composite can be considered as a potential lightweight microwave absorber.

  16. Composite lithium metal anode by melt infusion of lithium into a 3D conducting scaffold with lithiophilic coating

    PubMed Central

    Liang, Zheng; Lin, Dingchang; Zhao, Jie; Lu, Zhenda; Liu, Yayuan; Liu, Chong; Lu, Yingying; Wang, Haotian; Yan, Kai; Tao, Xinyong; Cui, Yi

    2016-01-01

    Lithium metal-based battery is considered one of the best energy storage systems due to its high theoretical capacity and lowest anode potential of all. However, dendritic growth and virtually relative infinity volume change during long-term cycling often lead to severe safety hazards and catastrophic failure. Here, a stable lithium–scaffold composite electrode is developed by lithium melt infusion into a 3D porous carbon matrix with “lithiophilic” coating. Lithium is uniformly entrapped on the matrix surface and in the 3D structure. The resulting composite electrode possesses a high conductive surface area and excellent structural stability upon galvanostatic cycling. We showed stable cycling of this composite electrode with small Li plating/stripping overpotential (<90 mV) at a high current density of 3 mA/cm2 over 80 cycles. PMID:26929378

  17. Bone regeneration and infiltration of an anisotropic composite scaffold: an experimental study of rabbit cranial defect repair.

    PubMed

    Li, Jidong; You, Fu; Li, Yubao; Zuo, Yi; Li, Limei; Jiang, Jiaxing; Qu, Yili; Lu, Minpeng; Man, Yi; Zou, Qin

    2016-01-01

    Tissue formation on scaffold outer edges after implantation may restrict cell infiltration and mass transfer to/from the scaffold center due to insufficient interconnectivity, leading to incidence of a necrotic core. Herein, a nano-hydroxyapatite/polyamide66 (n-HA/PA66) anisotropic scaffold with axially aligned channels was prepared with the aim to enhance pore interconnectivity. Bone tissue regeneration and infiltration inside of scaffold were assessed by rabbit cranial defect repair experiments. The amount of newly formed bone inside of anisotropic scaffold was much higher than isotropic scaffold, e.g., after 12 weeks, the new bone volume in the inner pores was greater in the anisotropic scaffolds (>50%) than the isotropic scaffolds (<30%). The results suggested that anisotropic scaffolds could accelerate the inducement of bone ingrowth into the inner pores in the non-load-bearing bone defects compared to isotropic scaffolds. Thus, anisotropic scaffolds hold promise for the application in bone tissue engineering.

  18. ERK Signals: Scaffolding Scaffolds?

    PubMed Central

    Casar, Berta; Crespo, Piero

    2016-01-01

    ERK1/2 MAP Kinases become activated in response to multiple intra- and extra-cellular stimuli through a signaling module composed of sequential tiers of cytoplasmic kinases. Scaffold proteins regulate ERK signals by connecting the different components of the module into a multi-enzymatic complex by which signal amplitude and duration are fine-tuned, and also provide signal fidelity by isolating this complex from external interferences. In addition, scaffold proteins play a central role as spatial regulators of ERKs signals. In this respect, depending on the subcellular localization from which the activating signals emanate, defined scaffolds specify which substrates are amenable to be phosphorylated. Recent evidence has unveiled direct interactions among different scaffold protein species. These scaffold-scaffold macro-complexes could constitute an additional level of regulation for ERK signals and may serve as nodes for the integration of incoming signals and the subsequent diversification of the outgoing signals with respect to substrate engagement. PMID:27303664

  19. Microfibrous β-TCP/collagen scaffolds mimic woven bone in structure and composition.

    PubMed

    Zhang, Shen; Zhang, Xin; Cai, Qing; Wang, Bo; Deng, Xuliang; Yang, Xiaoping

    2010-12-01

    Woven bone, as the initial form of bone tissue, is always found in developing and repairing bone. It is thought of as a temporary scaffold for the deposition of osteogenic cells and the laying down of lamellar bone. Thus, we hypothesize that a matrix which resembles the architecture and components of woven bone can provide an osteoblastic microenvironment for bone cell growth and new bone formation. In this study, woven-bone-like beta-tricalcium phosphate (β-TCP)/collagen scaffolds were fabricated by sol-gel electrospinning and impregnating methods. Optimization studies on sol-gel synthesis and electrospinning process were conducted respectively to prepare pure β-TCP fibers with dimensions close to mineralized collagen fibrils in woven bone. The collagen-coating layer prepared by impregnation had an adhesive role that held the β-TCP fibers together, and resulted in rapid degradation and matrix mineralization in in vitro tests. MG63 osteoblast-like cells seeded on the resultant scaffolds showed three-dimensional (3D) morphologies, and merged into multicellular layers after 7 days culture. Cytotoxicity test further revealed that extracts from the resultant scaffolds could promote the proliferation of MG63 cells. Therefore, the woven-bone-like matrix that we constructed favored the attachment and proliferation of MG63 cells in three dimensions. It has great potential ability to shorten the time of formation of new bone.

  20. Microradiographic microsphere manipulator

    DOEpatents

    Singleton, R.M.

    A method and apparatus is disclosed for radiographic characterization of small hollow spherical members (microspheres), constructed of either optically transparent or opaque materials. The apparatus involves a microsphere manipulator which holds a batch of microspheres between two parallel thin plastic films for contact microradiographic characterization or projection microradiography thereof. One plastic film is translated relative to and parallel to the other to roll the microspheres through any desired angle to allow different views of the microspheres.

  1. Microradiographic microsphere manipulator

    DOEpatents

    Singleton, Russell M.

    1980-01-01

    A method and apparatus for radiographic characterization of small hollow spherical members (microspheres), constructed of either optically transparent or opaque materials. The apparatus involves a microsphere manipulator which holds a batch of microspheres between two parallel thin plastic films for contact microradiographic characterization or projection microradiography thereof. One plastic film is translated to relative to and parallel to the other to roll the microspheres through any desired angle to allow different views of the microspheres.

  2. Novel calcified gum Arabic porous nano-composite scaffold for bone tissue regeneration.

    PubMed

    Hadavi, M; Hasannia, S; Faghihi, Sh; Mashayekhi, F; Zadeh, H H; Mostofi, S B

    2017-03-14

    The aim of this study was to investigate the biomechanical and biological properties of a nanocomposite scaffold containing both mineral and polysaccharide constituents. Hydroxyapatite nanoparticles (n-HA) was synthesized from dead abra ovata shells using wet chemical methods and was used in different ratios in concert with gum Arabic, a branched plant polysaccharide. N-HA/gum nanocomposite was fabricated with freeze-drying process and characterized by FTIR and SEM for chemical structure and morphology. Porosity was estimated using liquid substitution method. The scaffold mechanical properties were evaluated by compressive test measurement. Osteogenic differentiation was assessed using alkaline phosphatase production and biomineralization was evaluated using Alizarin red assay. Results demonstrated that the hydroxyapatite/gum Arabic nanocomposite had favorable biocompatibility and a similar structure to natural bone matrix. Porous nanocomposite possessed macropore networks with a porosity 87-93% and mean pore size ranging between 164 and 230 μm. The gum/HA with a ratio of 50% w/w HA had the highest compressive modulus of ∼75.3 MPa Pa (MPa) and the ultimate compressive stress of ∼16.6 MPa. C2C12 cells cultured on a scaffold with higher percentage (40 and 50 w/w) of HA demonstrated increased ALP levels and calcium deposition. The data from the present study demonstrated significant changes to the biomechanical properties and osteoconductivity of the nanocomposite scaffold by modulating its mineral content. Nanocomposite scaffolds containing gum and n-HA of 40-50% exhibited highest mechanical properties, as well as supported increased biomineralization.

  3. Hybrid microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Richard C. K. (Inventor)

    1985-01-01

    Substrates, particularly inert synthetic organic resin beads (10) or sheet (12) such as polystyrene are coated with a covalently bound layer (24) of polyacrolein by irradiation a solution (14) of acrolein or other aldehyde with high intensity radiation. Individual microspheres (22) are formed which attach to the surface to form the aldehyde containing layer (24). The aldehyde groups can be converted to other functional groups by reaction with materials such as hydroxylamine. Adducts of proteins such as antibodies or enzymes can be formed by direct reaction with the surface aldehyde groups.

  4. Improvement of cell response of the poly(lactic-co-glycolic acid)/calcium phosphate cement composite scaffold with unidirectional pore structure by the surface immobilization of collagen via plasma treatment.

    PubMed

    He, Fupo; Li, Jiyan; Ye, Jiandong

    2013-03-01

    In this study, calcium phosphate cement (CPC)-based scaffold with unidirectional lamellar pore structure was fabricated by unidirectional freeze casting. Poly(lactic-co-glycolic acid) (PLGA) was infiltrated into the CPC scaffold to improve its strength and toughness, which compromised the bioactivity and osteoconductivity of CPC. Collagen (Col) was immobilized on the pore surface of the PLGA/CPC scaffold to enhance the bioactivity of the scaffold using plasma treatment under the ammonia (NH(3)) atmosphere. The immobilization of collagen was characterized by infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Compared to the PLGA/CPC composite scaffold, the Col/PLGA/CPC composite scaffold had higher contact angle, porosity and water absorption, while the compressive strength of both scaffolds was comparable. Rat bone marrow mesenchymal stem cells (rMSCs) seeded on the Col/PLGA/CPC scaffold showed markedly improved cell seeding, attachment, proliferation and differentiation than those on the PLGA/CPC scaffold. These results suggest that the surface immobilization of collagen by plasma treatment can improve the bioactivity of the PLGA/CPC scaffold and the Col/PLGA/CPC composite scaffold is a promising candidate for bone tissue engineering.

  5. Collagen-gelatin-genipin-hydroxyapatite composite scaffolds colonized by human primary osteoblasts are suitable for bone tissue engineering applications: in vitro evidences.

    PubMed

    Vozzi, G; Corallo, C; Carta, S; Fortina, M; Gattazzo, F; Galletti, M; Giordano, N

    2014-05-01

    The application of porous hydroxyapatite (HAp)-collagen as a bone tissue engineering scaffold represents a new trend of mimicking the specific bone extracellular matrix (ECM). The use of HAp in reconstructive surgery has shown that it is slowly invaded by host tissue. Therefore, implant compatibility may be augmented by seeding cells before implantation. Human primary osteoblasts were seeded onto innovative collagen-gelatin-genipin (GP)-HAp scaffolds containing respectively 10%, 20%, and 30% HAp. Cellular adhesion, proliferation, alkaline phosphatase (ALP) activity, osteopontin (OPN), and osteocalcin (OC) expressions were evaluated after 3, 7, 15, and 21 days. The three types of scaffolds showed increased cellular proliferation over time in culture (maximum at 21 days) but the highest was recorded in 10% HAp scaffolds. ALP activity was the highest in 10% HAp scaffolds in all the times of evaluation. OC and OPN resulted in higher concentration in 10% HAp scaffolds compared to 20% and 30% HAp (maximum at 21 days). Finally, scanning electron microscopy analysis showed progressive scaffolds adhesion and colonization from the surface to the inside from day 3 to day 21. In vitro attachment, proliferation, and colonization of human primary osteoblasts on collagen-GP-HAp scaffolds with different percentages of HAp (10%, 20%, and 30%) all increased over time in culture, but comparing different percentages of HAp, they seem to increase with decreasing of HAp component. Therefore, the mechanical properties (such as the stiffness due to the HAp%) coupled with a good biomimetic component (collagen) are the parameters to set up in composite scaffolds design for bone tissue engineering.

  6. In vitro study of 3D PLGA/n-HAp/β-TCP composite scaffolds with etched oxygen plasma surface modification in bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Roh, Hee-Sang; Jung, Sang-Chul; Kook, Min-Suk; Kim, Byung-Hoon

    2016-12-01

    Three-dimensional (3D) scaffolds have many advantageous properties for bone tissue engineering application, due to its controllable properties such as pore size, structural shape and interconnectivity. In this study, effects on oxygen plasma surface modification and adding of nano-hydroxyapatite (n-HAp) and β-tricalcium phosphate (β-TCP) on the 3D PLGA/n-HAp/β-TCP scaffolds for improving preosteoblast cell (MC3T3-E1) adhesion, proliferation and differentiation were investigated. The 3D PLGA/n-HAp/β-TCP scaffolds were fabricated by 3D Bio-Extruder equipment. The 3D scaffolds were prepared with 0°/90° architecture and pore size of approximately 300 μm. In addition 3D scaffolds surface were etched by oxygen plasma to enhance the hydrophilic property and surface roughness. After oxygen plasma treatment, the surface chemistry and morphology were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. And also hydrophilic property was measured by contact angle. The MC3T3-E1 cell proliferation and differentiation were investigated by MTT assay and ALP activity. In present work, the 3D PLGA/HAp/beta-TCP composite scaffold with suitable structure for the growth of osteoblast cells was successfully fabricated by 3D rapid prototyping technique. The surface hydrophilicity and roughness of 3D scaffold increased by oxygen plasma treatment had a positive effect on cell adhesion, proliferation, and differentiation. Furthermore, the differentiation of MC3T3-E1 cell was significantly enhanced by adding of n-HAp and β-TCP on 3D PLGA scaffold. As a result, combination of bioceramics and oxygen plasma treatment showed a synergistic effect on biocompatibility of 3D scaffolds. This result confirms that this technique was useful tool for improving the biocompatibility in bone tissue engineering application.

  7. Investigation of emulsified, acid and acid-alkali catalyzed mesoporous bioactive glass microspheres for bone regeneration and drug delivery.

    PubMed

    Miao, Guohou; Chen, Xiaofeng; Dong, Hua; Fang, Liming; Mao, Cong; Li, Yuli; Li, Zhengmao; Hu, Qing

    2013-10-01

    Acid-catalyzed mesoporous bioactive glass microspheres (MBGMs-A) and acid-alkali co-catalyzed mesoporous bioactive glass microspheres (MBGMs-B) were successfully synthesized via combination of sol-gel and water-in-oil (W/O) micro-emulsion methods. The structural, morphological and textural properties of mesoporous bioactive glass microspheres (MBGMs) were characterized by various techniques. Results show that both MBGMs-A and MBGMs-B exhibit regularly spherical shape but with different internal porous structures, i.e., a dense microstructure for MBGMs-A and internally porous structure for MBGMs-B. (29)Si NMR data reveal that MGBMs have low polymerization degree of silica network. The in vitro bioactivity tests indicate that the apatite formation rate of MBGMs-B was faster than that of MBGMs-A after soaking in simulated body fluid (SBF) solution. Furthermore, the two kinds of MBGMs have similar storage capacity of alendronate (AL), and the release behaviors of AL could be controlled due to their unique porous structure. In conclusion, the microspheres are shown to be promising candidates as bone-related drug carriers and filling materials of composite scaffold for bone repair.

  8. Fabrication of Poly-l-lactic Acid/Dicalcium Phosphate Dihydrate Composite Scaffolds with High Mechanical Strength-Implications for Bone Tissue Engineering.

    PubMed

    Tanataweethum, Nida; Liu, Wai Ching; Goebel, W Scott; Li, Ding; Chu, Tien Min

    2015-11-04

    Scaffolds were fabricated from poly-l-lactic acid (PLLA)/dicalcium phosphate dihydrate (DCPD) composite by indirect casting. Sodium citrate and PLLA were used to improve the mechanical properties of the DCPD scaffolds. The resulting PLLA/DCPD composite scaffold had increased diametral tensile strength and fracture energy when compared to DCPD only scaffolds (1.05 vs. 2.70 MPa and 2.53 vs. 12.67 N-mm, respectively). Sodium citrate alone accelerated the degradation rate by 1.5 times independent of PLLA. Cytocompatibility of all samples were evaluated using proliferation and differentiation parameters of dog-bone marrow stromal cells (dog-BMSCs). The results showed that viable dog-BMSCs attached well on both DCPD and PLLA/DCPD composite surfaces. In both DCPD and PLLA/DCPD conditioned medium, dog-BMSCs proliferated well and expressed alkaline phosphatase (ALP) activity indicating cell differentiation. These findings indicate that incorporating both sodium citrate and PLLA could effectively improve mechanical strength and biocompatibility without increasing the degradation time of calcium phosphate cement scaffolds for bone tissue engineering purposes.

  9. Fabrication of Poly-l-lactic Acid/Dicalcium Phosphate Dihydrate Composite Scaffolds with High Mechanical Strength—Implications for Bone Tissue Engineering

    PubMed Central

    Tanataweethum, Nida; Liu, Wai Ching; Scott Goebel, W.; Li, Ding; Chu, Tien Min

    2015-01-01

    Scaffolds were fabricated from poly-l-lactic acid (PLLA)/dicalcium phosphate dihydrate (DCPD) composite by indirect casting. Sodium citrate and PLLA were used to improve the mechanical properties of the DCPD scaffolds. The resulting PLLA/DCPD composite scaffold had increased diametral tensile strength and fracture energy when compared to DCPD only scaffolds (1.05 vs. 2.70 MPa and 2.53 vs. 12.67 N-mm, respectively). Sodium citrate alone accelerated the degradation rate by 1.5 times independent of PLLA. Cytocompatibility of all samples were evaluated using proliferation and differentiation parameters of dog-bone marrow stromal cells (dog-BMSCs). The results showed that viable dog-BMSCs attached well on both DCPD and PLLA/DCPD composite surfaces. In both DCPD and PLLA/DCPD conditioned medium, dog-BMSCs proliferated well and expressed alkaline phosphatase (ALP) activity indicating cell differentiation. These findings indicate that incorporating both sodium citrate and PLLA could effectively improve mechanical strength and biocompatibility without increasing the degradation time of calcium phosphate cement scaffolds for bone tissue engineering purposes. PMID:26556380

  10. In vitro adipogenic differentiation of preadipocytes varies with differentiation stimulus, culture dimensionality, and scaffold composition.

    PubMed

    Stacey, D Heath; Hanson, Summer E; Lahvis, Garet; Gutowski, Karol A; Masters, Kristyn S

    2009-11-01

    Despite the rapidly growing body of work on stem cell-based adipose tissue engineering, there remains much to be learned about the role of the scaffold and culture environments in directing the adipogenic differentiation of cells. The present study examined how various culture environments and differentiation stimuli (traditional differentiation medium [DM] and coculture with mature adipocytes) impacted the adipogenic differentiation of human preadipocytes, with studies progressing from two-dimensions (2D) to three-dimensions (3D) in vitro. Assays for adipogenic markers (leptin, adiponectin, and glycerol) and Oil Red O staining were used to assess differentiation. After 16 days of 2D culture, adipogenesis was substantially greater when preadipocytes were cocultured with adipocytes rather than treated with DM. In a 3D in vitro environment, the production of adipogenic markers was significantly elevated relative to 2D conditions, and the coculture condition continued to stimulate greater adipogenesis. Alterations in 3D scaffold physical properties had only a minimal effect on the function of mature adipocytes, but significantly impacted the ability of preadipocytes to undergo adipogenic differentiation in vitro. These alterations in scaffold environment and in medium conditions, particularly the application of adipocyte/preadipocyte coculture methods in lieu of traditional DM, may provide further means for optimizing adipogenic outcomes in vitro and in vivo.

  11. Porous-wall hollow glass microspheres as carriers for biomolecules

    DOEpatents

    Li, Shuyi; Dynan, William S; Wicks, George; Serkiz, Steven

    2013-09-17

    The present invention includes compositions of porous-wall hollow glass microspheres and one or more biomolecules, wherein the one or more biomolecules are positioned within a void location within the hollow glass microsphere, and the use of such compositions for the diagnostic and/or therapeutic delivery of biomolecules.

  12. Manipulation of chemical composition and architecture of non-biodegradable poly(ethylene terephthalate)/chitosan fibrous scaffolds and their effects on L929 cell behavior.

    PubMed

    Veleirinho, Beatriz; Berti, Fernanda V; Dias, Paulo F; Maraschin, Marcelo; Ribeiro-do-Valle, Rosa M; Lopes-da-Silva, José A

    2013-01-01

    Microporous, non-woven fibrous scaffolds made of poly(ethylene terephthalate) and chitosan were produced by electrospinning. Fiber morphology, diameter, pore size, and wettability were manipulated by varying the chemical composition of the electrospinning solution, i.e. chitosan concentration and molecular weight, and by post-electrospinning treatment with glutaraldehyde. In vitro studies were conducted using a fibroblast cell line toward a comprehensive understanding of how scaffolds characteristics can modulate the cell behavior, i.e. viability, adhesion, proliferation, extracellular matrix secretion, and three-dimensional colonization. Substantial differences were found as a result of scaffold morphological changes. Higher levels of adhesion, spreading, and superficial proliferation were achieved for scaffolds with smaller fiber and pore diameters while cell penetration and internal colonization were enhanced for scaffolds with larger pores. Additionally, the available area for cell adhesion, which is related to fiber and pore size, was a crucial factor for the viability of L929 cells. This paper provides significant insights for the development and optimization of electrospun scaffolds toward an improved biological performance.

  13. S-propranolol imprinted polymer nanoparticle-on-microsphere composite porous cellulose membrane for the enantioselectively controlled delivery of racemic propranolol.

    PubMed

    Jantarat, Chutima; Tangthong, Naruedom; Songkro, Sarunyoo; Martin, Gary P; Suedee, Roongnapa

    2008-02-12

    Molecularly imprinted polymer (MIP) nanoparticle-on-microspheres (NOM) selective for S-propranolol were successfully prepared using suspension polymerization involving agitation of the reaction mixture at high speed. The integration of the MIP-NOM into a self-assembled porous cellulose membrane allowed a controlled distribution and availability of the molecule recognition sites within a porous structure. The nature of the membrane-included microparticles determined the degree of porosity whilst the adherent nanoparticles provided an increased surface area enabling the composite membrane to be employed efficiently for the trans-membrane transport of the imprinted molecule. The MIP-NOM within the membrane were easily accessible for binding of the imprinted molecule and appeared to maintain high selectivity, indicating that the composite membranes may potentially provide valuable affinity matrices. In this study, the application for MIP-NOM composite cellulose membranes were investigated for their potential to act as transdermal drug delivery systems for the S-enantiomers from racemic propranolol, its ester prodrugs (cyclopropanoyl- and valeryl-propranolol) or other beta-blockers (pindolol and oxprenolol). The enantioselective release of the fluorescently active 1-pyrene-butyryl ester prodrug of S-propranolol from MIP-NOM composite membranes and its diffusion and transit across excised rat skin was monitored by confocal laser scanning microscopy. The mechanism underlying the release of S-propranolol from the MIP-NOM composite membrane was found to involve specific adsorption and mobility of this enantiomer at the binding site in the MIP-NOM as the latter undergo a transition from the dry to wet state. The proposed MIP-NOM composite membrane controlled release system may be applicable for fabrication of novel membranes with self-controllable permeability responding to the presence of target solutes.

  14. Preparation of uniform magnetic recoverable catalyst microspheres with hierarchically mesoporous structure by using porous polymer microsphere template

    PubMed Central

    2014-01-01

    Merging nanoparticles with different functions into a single microsphere can exhibit profound impact on various applications. However, retaining the unique properties of each component after integration has proven to be a significant challenge. Our previous research demonstrated a facile method to incorporate magnetic nanoparticles into porous silica microspheres. Here, we report the fabrication of porous silica microspheres embedded with magnetic and gold nanoparticles as magnetic recoverable catalysts. The as-prepared multifunctional composite microspheres exhibit excellent magnetic and catalytic properties and a well-defined structure such as uniform size, high surface area, and large pore volume. As a result, the very little composite microspheres show high performance in catalytic reduction of 4-nitrophenol, special convenient magnetic separability, long life, and good reusability. The unique nanostructure makes the microspheres a novel stable and highly efficient catalyst system for various catalytic industry processes. PMID:24708885

  15. Towards functional 3D-stacked electrospun composite scaffolds of PHBV, silk fibroin and nanohydroxyapatite: Mechanical properties and surface osteogenic differentiation.

    PubMed

    Paşcu, Elena I; Cahill, Paul A; Stokes, Joseph; McGuinness, Garrett B

    2016-04-01

    Bone tissue engineering scaffolds have two challenging functional tasks to fulfil: to encourage cell proliferation, differentiation and matrix synthesis and to provide suitable mechanical stability upon implantation. Composites of biopolymers and bioceramics combine the advantages of both types of materials, resulting in better processability and enhanced mechanical and biological properties through matrix reinforcement. In the present study, novel thick bone composite scaffolds were successfully fabricated using electrospun flat sheets of polyhydroxybutyrate-polyhydroxyvalerate/nanohydroxyapatite/silk fibroin essence (2% nanohydroxyapatite - 2% silk fibroin essence and 5% nanohydroxyapatite - 5% silk fibroin essence, respectively). Their potential asin vitrobone regeneration scaffolds was evaluated using mouse calvarian osteoblast cells (MC3T3-E1), in terms of morphology (scanning electron microscope), cell attachment, cell proliferation, Col type I, osteopontin and bone alkaline phosphatase activity (Quantitative Real Time Polymerase Chain Reaction [qRT-PCR], enzyme-linked immunosorbent assay, immunocytochemistry). Electrospun polyhydroxybutyrate-polyhydroxyvalerate scaffolds were used as reference constructs. The results showed that the compressive and tensile mechanical properties of the scaffolds are dependent on the change in their composition, and the treatment these underwent. Furthermore, methanol-treated and autoclaved (MA) P2 (2% nanohydroxyapatite, 2% silk fibroin essence) samples appeared to exhibit more promising tensile properties. Additionally, the compressive tests results confirmed that the methanol pre-treatment and the autoclaving step lead to an increase in the P2 secant modulus when compared to the non-methanol-treated ones, P2 and P5 (5% nanohydroxyapatite, 5% silk fibroin essence), respectively.Both formulations of polyhydroxybutyrate-polyhydroxyvalerate/nanohydroxyapatite/silk fibroin essence composite promoted greater cell adhesion and

  16. Fabrication of an rhBMP-2 loaded porous β-TCP microsphere-hyaluronic acid-based powder gel composite and evaluation of implant osseointegration.

    PubMed

    Lee, Jae Hyup; Kim, Jungju; Baek, Hae-Ri; Lee, Kyung Mee; Seo, Jun-Hyuk; Lee, Hyun-Kyung; Lee, A-Young; Zheng, Guang Bin; Chang, Bong-Soon; Lee, Choon-Ki

    2014-09-01

    Methods to improve osseointegration that include implantation of rhBMP-2 with various kinds of carriers are currently of considerable interest. The present study was conducted to evaluate if the rhBMP-2 loaded β-TCP microsphere-hyaluronic acid-based powder-like hydrogel composite (powder gel) can act as an effective rhBMP-2 carrier for implantation in host bone with a bone defect or poor bone quality. The release pattern for rhBMP-2 was then evaluated against an rhBMP-2-loaded collagen sponge as a control group. Dental implants were also inserted into the tibias of three groups of rabbits: an rhBMP-2 (200 µg) loaded powder gel composite implanted group, an implant only group, and a powder gel implanted group. Micro-CT and histology of the implanted areas were carried out four weeks later. The rhBMP-2 powder gel released less rhBMP-2 than the collagen sponge, but it continued a slow release for more than 7 days. The rhBMP-2 powder gel composite improved osseointegration of the dental implant by increasing the amount of new bone formation in the implant pitch and it improved the bone quality and bone quantity of new bone. The histology results indicated that the rhBMP-2 powder gel composite improved the osseointegration in the cortical bone as well as the marrow space along the fixture. The bone-to-implant contact ratio of the rhBMP-2 (200 µg) loaded powder gel composite implanted group was significantly higher than those of the implant only group and the powder gel implanted group. The powder gel appeared to be a good carrier and could release rhBMP-2 slowly to promote the formation of new bone following implantation in a bone defect, thereby improving implant osseointegration.

  17. An Inorganic Microsphere Composite for the Selective Removal of 137 Cesium from Acidic Nuclear Waste Solutions 2: Bench-Scale Column Experiments, Modeling, and Preliminary Process Design

    SciTech Connect

    Troy J. Tranter; T. A. Vereschagina; V. Utgikar

    2009-03-01

    A new inorganic ion exchange composite for removing radioactive cesium from acidic waste streams has been developed. The new material consists of ammonium molybdophosphate, (NH4)3P(Mo3O10)4?3H2O (AMP), synthesized within hollow aluminosilicate microspheres (AMP-C), which are produced as a by-product from coal combustion. The selective cesium exchange capacity of this inorganic composite was evaluated in bench-scale column tests using simulated sodium bearing waste solution as a surrogate for the acidic tank waste currently stored at the Idaho National Laboratory (INL). Total cesium loading on the columns at saturation agreed very well with equilibrium values predicted from isotherm experiments performed previously. A numerical algorithm for solving the governing partial differential equations (PDE) for cesium uptake was developed using the intraparticle mass transfer coefficient obtained from previous batch kinetic experiments. Solutions to the governing equations were generated to obtain the cesium concentration at the column effluent as a function of throughput volume using the same conditions as those used for the actual column experiments. The numerical solutions of the PDE fit the column break through data quite well for all the experimental conditions in the study. The model should therefore provide a reliable prediction of column performance at larger scales.

  18. Composite scaffolds of dicalcium phosphate anhydrate /multi-(amino acid) copolymer: in vitro degradability and osteoblast biocompatibility.

    PubMed

    Yao, Qianqian; Ye, Jun; Xu, Qian; Mo, Anchun; Gong, Ping

    2015-01-01

    This study aims to evaluate in vitro degradability and osteoblast biocompatibility of dicalcium phosphate anhydrate/multi-(amino acid) (DCPA/MAA) composites prepared by in situ polymerization method. The results revealed that the composites could be slowly degraded in PBS solution, with weight loss of 9.5 ± 0.2 wt.% compared with 12.2 ± 0.2 wt.% of MAA copolymer after eight weeks, and the changes of pH value were in the range of 7.18-7.4 and stabilized at 7.24. In addition, the compressive strength of the composite decreased from 98 to 62 MPa while that of MAA copolymer from 117 to 86 MPa. Furthermore, with non-toxicity demonstrated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assay, the addition of DCPA to the MAA copolymer evidenced an enhancement of osteoblast differentiation and attachment compared with pure MAA materials regarding to alkaline phosphatase activity as well as initial cell adhesion. The results indicated that the DCPA/MAA scaffolds with good osteoblast biocompatibility, degradability, and sufficient strength had promising potential application in bone tissue engineering.

  19. Tetronic(®)-based composite hydrogel scaffolds seeded with rat bladder smooth muscle cells for urinary bladder tissue engineering applications.

    PubMed

    Sivaraman, Srikanth; Ostendorff, Rachel; Fleishman, Benjamin; Nagatomi, Jiro

    2015-01-01

    Natural hydrogels such as collagen offer desirable properties for tissue engineering, including cell adhesion sites, but their low mechanical strength is not suitable for bladder tissue regeneration. In contrast, synthetic hydrogels such as poly (ethylene glycol) allow tuning of mechanical properties, but do not elicit protein adsorption or cell adhesion. For this reason, we explored the use of composite hydrogel blends composed of Tetronic (BASF) 1107-acrylate (T1107A) in combination with extracellular matrix moieties collagen and hyaluronic acid seeded with bladder smooth muscle cells (BSMC). This composite hydrogel supported BSMC growth and distribution throughout the construct. When compared to the control (acellular) hydrogels, mechanical properties (peak stress, peak strain, and elastic modulus) of the cellular hydrogels were significantly greater. When compared to the 7-day time point after BSMC seeding, results of mechanical testing at the 14-day time point indicated a significant increase in both ultimate tensile stress (4.1-11.6 kPa) and elastic modulus (11.8-42.7 kPa) in cellular hydrogels. The time-dependent improvement in stiffness and strength of the cellular constructs can be attributed to the continuous collagen deposition and reconstruction by BSMC seeded in the matrix. The composite hydrogel provided a biocompatible scaffold for BSMC to thrive and strengthen the matrix; further, this trend could lead to strengthening the construct to match the mechanical properties of the bladder.

  20. Development of Risperidone PLGA Microspheres

    PubMed Central

    D'Souza, Susan; Faraj, Jabar A.; Giovagnoli, Stefano; DeLuca, Patrick P.

    2014-01-01

    The aim of this study was to design and evaluate biodegradable PLGA microspheres for sustained delivery of Risperidone, with an eventual goal of avoiding combination therapy for the treatment of schizophrenia. Two PLGA copolymers (50 : 50 and 75 : 25) were used to prepare four microsphere formulations of Risperidone. The microspheres were characterized by several in vitro techniques. In vivo studies in male Sprague-Dawley rats at 20 and 40 mg/kg doses revealed that all formulations exhibited an initial burst followed by sustained release of the active moiety. Additionally, formulations prepared with 50 : 50 PLGA had a shorter duration of action and lower cumulative AUC levels than the 75 : 25 PLGA microspheres. A simulation of multiple dosing at weekly or 15-day regimen revealed pulsatile behavior for all formulations with steady state being achieved by the second dose. Overall, the clinical use of Formulations A, B, C, or D will eliminate the need for combination oral therapy and reduce time to achieve steady state, with a smaller washout period upon cessation of therapy. Results of this study prove the suitability of using PLGA copolymers of varying composition and molecular weight to develop sustained release formulations that can tailor in vivo behavior and enhance pharmacological effectiveness of the drug. PMID:24616812

  1. Biocompatibility and Structural Features of Biodegradable Polymer Scaffolds.

    PubMed

    Nasonova, M V; Glushkova, T V; Borisov, V V; Velikanova, E A; Burago, A Yu; Kudryavtseva, Yu A

    2015-11-01

    We performed a comparative analysis of physicochemical properties and biocompatibility of scaffolds of different composition on the basis of biodegradable polymers fabricated by casting and electrospinning methods. For production of polyhydroxyalkanoate-based scaffolds by electrospinning method, the optimal concentration of the polymer was 8-10%. Fiber diameter and properties of the scaffold produced by electrospinning method depended on polymer composition. Addition of polycaprolactone increased elasticity of the scaffolds. Bio- and hemocompatibility of the scaffolds largely depended on the composition formulation and method of scaffold fabrication. Polylactide introduced into the composition of polyhydroxybutyrate-oxyvalerate scaffolds accelerated degradation and increased adhesive properties of the scaffolds.

  2. Incorporation of sol-gel bioactive glass into PLGA improves mechanical properties and bioactivity of composite scaffolds and results in their osteoinductive properties.

    PubMed

    Filipowska, J; Pawlik, J; Cholewa-Kowalska, K; Tylko, G; Pamula, E; Niedzwiedzki, L; Szuta, M; Laczka, M; Osyczka, A M

    2014-10-20

    In this study, 3D porous bioactive composite scaffolds were produced and evaluated for their physico-chemical and biological properties. Polymer poly-L-lactide-co-glycolide (PLGA) matrix scaffolds were modified with sol-gel-derived bioactive glasses (SBGs) of CaO-SiO2-P2O5 systems. We hypothesized that SBG incorporation into PLGA matrix would improve the chemical and biological activity of composite materials as well as their mechanical properties. We applied two bioactive glasses, designated as S2 or A2, differing in the content of SiO2 and CaO (i.e. 80 mol% SiO2, 16 mol% CaO for S2 and 40 mol% SiO2, 52 mol% CaO for A2). The composites were characterized for their porosity, bioactivity, microstructure and mechanical properties. The osteoinductive properties of these composites were evaluated in human bone marrow stromal cell (hBMSC) cultures grown in either standard growth medium or treated with recombinant human bone morphogenetic protein-2 (rhBMP-2) or dexamethasone (Dex). After incubation in simulated body fluid, calcium phosphate precipitates formed inside the pores of both A2-PLGA and S2-PLGA scaffolds. The compressive strength of the latter was increased slightly compared to PLGA. Both composites promoted superior hBMSC attachment to the material surface and stimulated the expression of several osteogenic markers in hBMSC compared to cells grown on unmodified PLGA. There were also marked differences in the response of hBMSC to composite scaffolds, depending on chemical compositions of the scaffolds and culture treatments. Compared to silica-rich S2-PLGA, hBMSC grown on calcium-rich A2-PLGA were overall less responsive to rhBMP-2 or Dex and the osteoinductive properties of these A2-PLGA scaffolds seemed partially dependent on their ability to induce BMP signaling in untreated hBMSC. Thus, beyond the ability of currently studied composites to enhance hBMSC osteogenesis, it may become possible to modulate the osteogenic response of hBMSC, depending on the

  3. Three dimensional printed macroporous polylactic acid/hydroxyapatite composite scaffolds for promoting bone formation in a critical-size rat calvarial defect model.

    PubMed

    Zhang, Haifeng; Mao, Xiyuan; Du, Zijing; Jiang, Wenbo; Han, Xiuguo; Zhao, Danyang; Han, Dong; Li, Qingfeng

    2016-01-01

    We have explored the applicability of printed scaffold by comparing osteogenic ability and biodegradation property of three resorbable biomaterials. A polylactic acid/hydroxyapatite (PLA/HA) composite with a pore size of 500 μm and 60% porosity was fabricated by three-dimensional printing. Three-dimensional printed PLA/HA, β-tricalcium phosphate (β-TCP) and partially demineralized bone matrix (DBM) seeded with bone marrow stromal cells (BMSCs) were evaluated by cell adhesion, proliferation, alkaline phosphatase activity and osteogenic gene expression of osteopontin (OPN) and collagen type I (COL-1). Moreover, the biocompatibility, bone repairing capacity and degradation in three different bone substitute materials were estimated using a critical-size rat calvarial defect model in vivo. The defects were evaluated by micro-computed tomography and histological analysis at four and eight weeks after surgery, respectively. The results showed that each of the studied scaffolds had its own specific merits and drawbacks. Three-dimensional printed PLA/HA scaffolds possessed good biocompatibility and stimulated BMSC cell proliferation and differentiation to osteogenic cells. The outcomes in vivo revealed that 3D printed PLA/HA scaffolds had good osteogenic capability and biodegradation activity with no difference in inflammation reaction. Therefore, 3D printed PLA/HA scaffolds have potential applications in bone tissue engineering and may be used as graft substitutes in reconstructive surgery.

  4. Three dimensional printed macroporous polylactic acid/hydroxyapatite composite scaffolds for promoting bone formation in a critical-size rat calvarial defect model

    PubMed Central

    Zhang, Haifeng; Mao, Xiyuan; Du, Zijing; Jiang, Wenbo; Han, Xiuguo; Zhao, Danyang; Han, Dong; Li, Qingfeng

    2016-01-01

    Abstract We have explored the applicability of printed scaffold by comparing osteogenic ability and biodegradation property of three resorbable biomaterials. A polylactic acid/hydroxyapatite (PLA/HA) composite with a pore size of 500 μm and 60% porosity was fabricated by three-dimensional printing. Three-dimensional printed PLA/HA, β-tricalcium phosphate (β-TCP) and partially demineralized bone matrix (DBM) seeded with bone marrow stromal cells (BMSCs) were evaluated by cell adhesion, proliferation, alkaline phosphatase activity and osteogenic gene expression of osteopontin (OPN) and collagen type I (COL-1). Moreover, the biocompatibility, bone repairing capacity and degradation in three different bone substitute materials were estimated using a critical-size rat calvarial defect model in vivo. The defects were evaluated by micro-computed tomography and histological analysis at four and eight weeks after surgery, respectively. The results showed that each of the studied scaffolds had its own specific merits and drawbacks. Three-dimensional printed PLA/HA scaffolds possessed good biocompatibility and stimulated BMSC cell proliferation and differentiation to osteogenic cells. The outcomes in vivo revealed that 3D printed PLA/HA scaffolds had good osteogenic capability and biodegradation activity with no difference in inflammation reaction. Therefore, 3D printed PLA/HA scaffolds have potential applications in bone tissue engineering and may be used as graft substitutes in reconstructive surgery. PMID:27877865

  5. Effect of ionic activity products on the structure and composition of mineral self assembled on three-dimensional poly(lactide-co-glycolide) scaffolds

    PubMed Central

    Shin, Kyungsup; Jayasuriya, Ambalangodage C.; Kohn, David H.

    2009-01-01

    A biomimetic approach involving the self-assembly of mineral within the pores of three-dimensional porous polymer scaffolds is a promising strategy to integrate advantages of inorganic and organic phases into a single material for hard tissue engineering. Such a material enhances the ability of progenitor cells to differentiate down an osteoblast lineage in vitro and in vivo, compared with polymer scaffolds. The mechanisms regulating mineral formation in this one-step process, however, are poorly understood, especially the effects of ionic activity products (IP) of the mineralizing solution and incubation time. The aims of this study were to define the structure and composition of mineral formed within the pores of biodegradable polymer scaffolds as a function of IP and time. Three-dimensional poly(lactide-co-glycolide) scaffolds were fabricated by solvent casting/particulate leaching and incubated for 4–16 days in six variants of simulated body fluid whose IPs were varied by adjusting ionic concentrations. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy demonstrated the formation of carbonated apatite with sub-micrometer sized crystals that grew into spherical globules extending out of the scaffold pore surfaces. As IP increased, more mineral grew on the scaffold pore surfaces, but the apatite became less crystalline and the Ca/P molar ratio decreased from 1.63 ± 0.005 to 1.51 ± 0.002. Since morphology, composition, and structure of mineral are factors that affect cell function, this study demonstrates that the IP of the mineralizing solution is an important modulator of material properties, potentially leading to enhanced control of cell function. PMID:17584901

  6. Micromechanical finite-element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone-hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering.

    PubMed

    Eshraghi, Shaun; Das, Suman

    2012-08-01

    Bioresorbable scaffolds with mechanical properties suitable for bone tissue engineering were fabricated from polycaprolactone (PCL) and hydroxyapatite (HA) by selective laser sintering (SLS) and modeled by finite-element analysis (FEA). Both solid gage parts and scaffolds having 1-D, 2-D and 3-D orthogonal, periodic porous architectures were made with 0, 10, 20 and 30 vol.% HA. PCL:HA scaffolds manufactured by SLS had nearly full density (99%) in the designed solid regions and had excellent geometric and dimensional control. Through optimization of the SLS process, the compressive moduli for our solid gage parts and scaffolds are the highest reported in the literature for additive manufacturing. The compressive moduli of solid gage parts were 299.3, 311.2, 415.5 and 498.3 MPa for PCL:HA loading at 100:0, 90:10, 80:20 and 70:30, respectively. The compressive effective stiffness tended to increase as the loading of HA was increased and the designed porosity was lowered. In the case of the most 3-D porous scaffold, the compressive modulus more than doubled from 14.9 to 36.2 MPa when changing the material from 100:0 to 70:30 PCL:HA. A micromechanical FEA model was developed to investigate the reinforcement effect of HA loading on the compressive modulus of the bulk material. Using a first-principles based approach, the random distribution of HA particles in a solidified PCL matrix was modeled for any HA loading to predict the bulk mechanical properties of the composites. The bulk mechanical properties were also used for FEA of the scaffold geometries. The results of the FEA were found to be in good agreement with experimental mechanical testing. The development of patient- and site-specific composite tissue-engineering constructs with tailored properties can be seen as a direct extension of this work on computational design, a priori modeling of mechanical properties and direct digital manufacturing.

  7. Composite poly(l-lactic-acid)/silk fibroin scaffold prepared by electrospinning promotes chondrogenesis for cartilage tissue engineering.

    PubMed

    Li, Zhengqiang; Liu, Peng; Yang, Ting; Sun, Ying; You, Qi; Li, Jiale; Wang, Zilin; Han, Bing

    2016-05-01

    Nanofibrous materials produced by electrospinning have attracted considerable attention from researchers in regenerative medicine. A combination of nanofibrous scaffold and chondrocytes is considered promising for repair of cartilage defect or damage. In the present study, we fabricated a poly(l-lactic-acid) (PLLA)/silk fibroin (SF) nanofibrous scaffold by electrospinning and evaluated its chondrogenic potential. The PLLA/SF nanofibers were characterized for diameter, surface wettability, swelling ratio, and tensile strength. Throughin vitroexperiments, PLLA/SF scaffold-chondrocyte interactions were investigated relative to the unmodified PLLA scaffold with regard to cellular adhesion, spreading, and proliferation by scanning electron microscopy and confocal laser scanning microscopy, and through analyses of DNA, sulfated glycosaminoglycan, and collagen. In addition, hematoxylin-eosin and Alcian blue-nuclear fast red staining were used to observe growth of chondrocytes, and secretion and distribution of cartilage-specific extracellular matrices in the scaffolds. Expressions of cartilage-related genes (collagen II, aggrecan, sox9, collagen I, and collagen X) were detected by real-time quantitative PCR. The PLLA/SF scaffold had better hydrophilicity, and could support chondrocytes adhesion and spreading more effectively than the unmodified PLLA scaffold. Chondrocytes secreted more cartilage-specific extracellular matrices and maintained their phenotype on the PLLA/SF scaffold. So it is concluded that the PLLA/SF scaffold is more conducive toin vitroformation of cartilage-like new tissues than the unmodified PLLA scaffold, and may be a promising material in cartilage tissue engineering.

  8. A novel chitosan-tussah silk fibroin/nano-hydroxyapatite composite bone scaffold platform with tunable mechanical strength in a wide range.

    PubMed

    Ran, Jiabing; Hu, Jingxiao; Sun, Guanglin; Chen, Si; Jiang, Pei; Shen, Xinyu; Tong, Hua

    2016-12-01

    Currently, great efforts have been made to enhance the mechanical strength of bone tissue engineering (BTE) scaffolds, which are composed of biopolymeric matrices and inorganic nano-fillers. But the tunability of mechanical strength in a wide range for BTE scaffolds has seldom been investigated in spite of the great importance of this performance. In this work, a chitosan-tussah silk fibroin/hydroxyapatite (CS-TSF/HAp) hydrogel was synthesized by using a novel in situ precipitation method. Through in situ inducing the conformation transition of TSF in the CS-TSF/HAp hydrogel, which could be monitored by XRD, FT-IR, TGA, and DTA, the elastic modulus and fracture strength of the final CS-TSF/HAp composite could be tailored in a wide range without changing its composition, morphology, roughness, and crystal structures. The elastic modulus of the CS-TSF/HAp composite ranged from ∼250 to ∼400MPa while its fracture strength ranged from ∼45 to ∼100MPa. In order to clarify the rationale behind this process, a speculative explanation was provided. In vitro cell culture indicated that MC3T3-E1 cells cultured on the CS-TSF/HAp composite had positive adhesion, proliferation, and differentiation potential. We believed that the CS-TSF/HAp composite could be used as an ideal scaffold platform for cell culture and implantation of bone reconstruction.

  9. Microspheres and nanoparticles from ultrasound

    NASA Astrophysics Data System (ADS)

    Suh, Won Hyuk

    Improved preparations of various examples of monodispersed, porous, hollow, and core-shell metal and semiconductor nanoparticles or nanowires have been developed. Now titania microspheres and nanoparticles and silica microspheres can be synthesized using an inexpensive high frequency (1.7 MHz) ultrasonic generator (household humidifier; ultrasonic spray pyrolysis; USP). Morphology and pore size of titania microspheres were controlled by the silica to Ti(IV) ratio and silica particle size. Fine tuning the precursor ratio affords sub-50 nm titania nanoparticles as well. In terms of silica microspheres, morphology was controlled by the silica to organic monomer ratio. In liquids irradiated with high intensity ultrasound (20 kHz; HIUS), acoustic cavitation produces high energy chemistry through intense local heating inside the gas phase of collapsing bubbles in the liquid. HIUS and USP confine the chemical reactions to isolated sub-micron reaction zones, but sonochemistry does so in a heated gas phase within a liquid, while USP uses a hot liquid droplet carried by a gas flow. Thus, USP can be viewed as a method of phase-separated synthesis using submicron-sized droplets as isolated chemical reactors for nanomaterial synthesis. While USP has been used to create both titania and silica spheres separately, there are no prior reports of titania-silica composites. Such nanocomposites of metal oxides have been produced, and by further manipulation, various porous structures with fascinating morphologies were generated. Briefly, a precursor solution was nebulized using a commercially available household ultrasonic humidifier (1.7 MHz ultrasound generator), and the resulting mist was carried in a gas stream of air through a quartz glass tube in a hot furnace. After exiting the hot zone, these microspheres are porous or hollow and in certain cases magnetically responsive. In the case of titania microspheres, they are rapidly taken up into the cytoplasm of mammalian cells and

  10. Preparation of chitosan/poly(acrylic acid) magnetic composite microspheres and applications in the removal of copper(II) ions from aqueous solutions.

    PubMed

    Yan, Han; Yang, Lingyun; Yang, Zhen; Yang, Hu; Li, Aimin; Cheng, Rongshi

    2012-08-30

    In this current work, the magnetic composite microspheres (MCM), consisting of Fe(3)O(4) nanoparticles and poly(acrylic acid) (PAA) blended chitosan (CS), were prepared successfully by a simple method, co-precipitation of the compounds in alkaline solution. SEM, FTIR and TG techniques have been applied to investigate the structures of the MCM materials. The vibrating-sample magnetometer (VSM) measurement illustrated a paramagnetic property as well as a fast magnetic response, which indicated the significant separability of the MCM in the aqueous suspensions. Then, the MCM materials were employed as absorbents for removal of copper(II) (Cu(II)) ions from aqueous solutions. The fundamental adsorption behaviors of MCM were studied also. Experimental results revealed that the CS/PAA-MCM had greater adsorption capacity than CS-MCM, and PAA played an important role for the adsorption of Cu(II) ions. Moreover, the adsorption isotherms were all well described by the Langmuir model, while the adsorption kinetics followed the pseudo-second order equation. Furthermore, the adsorbent could be easily regenerated at lower pH and reused almost without any loss of adsorption capacity. On the contrary, the Cu(II) ions loaded CS-MCM and CS/PAA-MCM were stable enough at pH higher than 4.0, and both exhibited efficient phosphate removal with maximal uptakes around 63.0 and 108.0 mg Pg(-1), respectively.

  11. Multifunctional Chitosan-45S5 Bioactive Glass-Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Microsphere Composite Membranes for Guided Tissue/Bone Regeneration.

    PubMed

    Li, Wei; Ding, Yaping; Yu, Shanshan; Yao, Qingqing; Boccaccini, Aldo R

    2015-09-23

    Novel multifunctional chitosan-45S5 bioactive glass-poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) microsphere (CS-BG-MS) composite membranes were developed with applicability in guided tissue/bone regeneration (GTR/GBR). The incorporation of 45S5 BG and PHBV MS into CS membranes not only provided the membranes with favorable surface roughness, hydrophilicity, and flexibility but also slowed down their degradation rate. Moreover, the CS membranes became bioactive after the incorporation of 45S5 BG and capable of releasing drugs of different physicochemical properties in a controlled and sustained manner with the addition of PHBV MS. Cell culture tests showed that osteoblast-like MG-63 human osteosarcoma cells had significantly higher adhesion, cell proliferation, and alkaline phosphatase (ALP) activity on CS-BG and CS-BG-MS membranes than on neat CS membranes. Therefore, the developed bioactive CS-BG-MS membranes with potential multidrug (e.g., antibacterial and antiosteoporosis drugs) delivery capability are promising candidate membranes for GTR/GBR applications.

  12. In situ growth of copper nanocrystals from carbonaceous microspheres with electrochemical glucose sensing properties

    SciTech Connect

    Zhou, Xiaoliang; Yan, Zhengguang Han, Xiaodong

    2014-02-01

    Graphical abstract: In situ growth of copper nanoparticles from hydrothermal copper-containing carbonaceous microspheres was induced by annealing or electron beam irradiation. Obtained micro-nano carbon/copper composite microspheres show electrochemical glucose sensing properties. - Highlights: • We synthesized carbonaceous microspheres containing non-nanoparicle copper species through a hydrothermal route. • By annealing or electron beam irradiation, copper nanoparticles would form from the carbonaceous microspheres in situ. • By controlling the annealing temperature, particle size of copper could be controlled in the range of 50–500 nm. • The annealed carbon/copper hierarchical composite microspheres were used to fabricate an electrochemical glucose sensor. - Abstract: In situ growth of copper nanocrystals from carbon/copper microspheres was observed in a well-controlled annealing or an electron beam irradiation process. Carbonaceous microspheres containing copper species with a smooth appearance were yielded by a hydrothermal synthesis using copper nitrate and ascorbic acid as reactants. When annealing the carbonaceous microspheres under inert atmosphere, copper nanoparticles were formed on carbon microspheres and the copper particle sizes can be increased to a range of 50–500 nm by altering the heating temperature. Similarly, in situ formation of copper nanocrystals from these carbonaceous microspheres was observed on the hydrothermal product carbonaceous microspheres with electron beam irradiation in a vacuum transmission electron microscopy chamber. The carbon/copper composite microspheres obtained through annealing were used to modify a glassy carbon electrode and tested as an electrochemical glucose sensor.

  13. The influence of stereolithographic scaffold architecture and composition on osteogenic signal expression with rat bone marrow stromal cells

    PubMed Central

    Kim, Kyobum; Dean, David; Wallace, Jonathan; Breithaupt, Rob; Mikos, Antonios G.; Fisher, John P.

    2011-01-01

    Scaffold design parameters, especially physical construction factors such as mechanical stiffness of substrate materials, pore size of 3D porous scaffolds, and channel geometry, are known to influence the osteogenic signal expression and subsequent differentiation of a transplanted cell population. In this study of photocrosslinked poly(propylene fumarate) (PPF) and diethyl fumarate (DEF) scaffolds, the effect of DEF incorporation ratio and pore size on the osteogenic signal expression of rat bone marrow stromal cells (BMSCs) was investigated. Results demonstrated that DEF concentrations and pore sizes that led to increased scaffold mechanical stiffness also upregulated osteogenic signal expression, including bone morphogenic protein-2 (BMP-2), fibroblast growth factors-2 (FGF-2), transforming growth factor-β1 (TGF-β1), vascular endothelial growth factor (VEGF), and Runx2 transcriptional factor. Similar scaffold fabrication parameters supported rapid BMSC osteoblastic differentiation, as demonstrated by increased alkaline phosphatase (ALP) and osteocalcin expression. When scaffolds with random architecture, fabricated by porogen leaching, were compared to those with controlled architecture, fabricated by stereolithography (SLA), results showed that SLA scaffolds with the highly permeable and porous channels also have significantly higher expression of FGF-2, TGF-β1, and VEGF. Subsequent ALP expression and osteopontin secretion were also significantly increased in SLA scaffolds. Based upon these results, we conclude that scaffold properties provided by additive manufacturing techniques such as SLA fabrication, particularly increased mechanical stiffness and high permeability, may stimulate dramatic BMSC responses that promote rapid bone tissue regeneration. PMID:21396709

  14. Effects of wollastonite on proliferation and differentiation of human bone marrow-derived stromal cells in PHBV/wollastonite composite scaffolds.

    PubMed

    Li, Haiyan; Zhai, Wanying; Chang, Jiang

    2009-09-01

    In this study, the effects of wollastonite on proliferation and differentiation of human bone marrow-derived stromal cells (hBMSCs) have been investigated based on a polyhydroxybutyrate-co-hydroxyvalerate (PHBV)/ wollastonite (W) composite scaffolds system. Cell morphology, proliferation, and differentiation were measured. The results showed that the incorporation of wollastonite benefited hBMSCs adhesion, proliferation, and differentiation rate. In addition, an increase of proliferation and differentiation rate was observed when the wollastonite content in the PHBV/W composite scaffolds increased from 10 to 20 wt%. Based on our previous studies on PHBV/W composite discs, the differentiation measurements in this paper further proved that the wollastonite itself can stimulate the hBMSCs to differentiate toward osteoblasts without any osteogenic medium, and the ionic products (Ca and Si) released from wollastonite might contribute to this advantage. It is also suggested that the osteogenic differentiation of the hBMSCs can be affected by adjusting the wollastonite content in the composite scaffolds.

  15. Hydrophilic porous magnetic poly(GMA-MBAA-NVP) composite microspheres containing oxirane groups: An efficient carrier for immobilizing penicillin G acylase

    NASA Astrophysics Data System (ADS)

    Xue, Ping; Su, Weiguang; Gu, Yaohua; Liu, Haifeng; Wang, Julan

    2015-03-01

    Magnetic hydrophilic polymeric microspheres containing oxirane groups were prepared by inverse suspension polymerization of glycidyl methacrylate (GMA), N, N‧-methylene bisacrylamide (MBAA) and N-vinyl pyrrolidone (NVP) in the existence of formamide, which were denoted as magnetic poly(GMA-MBAA-NVP) microspheres. The magnetic poly(GMA-MBAA-NVP) microspheres were characterized by scanning electron microscopy (SEM), FT-IR spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and so on. The results showed that poly(GMA-MBAA-NVP) microspheres possessed well spherical shape, narrow size distribution, abundant porous structure, reactive oxirane groups and superparamagnetic properties. Formamide used in the present work served as a modifier, a dispersant and a porogen to form final porous polymer microspheres. The penicillin G acylase (PGA) was covalently immobilized onto the magnetic microspheres through the reaction between the amino groups of enzyme and the oxirane groups on the microspheres for producing 6-aminopenicillanic acid (6-APA). The effects of GMA/NVP ratio and crosslink density on the activity of immobilized PGA were investigated. The highest apparent activity, enzyme loading and coupling yield of immobilized PGA were 821 IU/g, 65.3 mg/g and 42.3% respectively when the mass ratio of GMA/NVP was 1:1 and crosslink density was 60%. Compared with the free PGA, immobilized PGA showed a wider range of pH value and reaction temperature. The relative activity and reaction rate of immobilized PGA remained almost constant after 20 recycles. The magnetic poly(GMA-MBAA-NVP) microspheres would be very promising carriers for immobilizing enzymes in industrial application.

  16. Adhesion and growth of human bone marrow mesenchymal stem cells on precise-geometry 3D organic-inorganic composite scaffolds for bone repair.

    PubMed

    Chatzinikolaidou, Maria; Rekstyte, Sima; Danilevicius, Paulius; Pontikoglou, Charalampos; Papadaki, Helen; Farsari, Maria; Vamvakaki, Maria

    2015-03-01

    Engineering biomaterial scaffolds that promote attachment and growth of mesenchymal stem cells in three dimensions is a crucial parameter for successful bone tissue engineering. Towards this direction, a lot of research effort has focused recently into the development of three-dimensional porous scaffolds, aiming to elicit positive cellular behavior. However, the fabrication of three-dimensional tissue scaffolds with a precise geometry and complex micro- and nano-features, supporting cell in-growth remains a challenge. In this study we report on a positive cellular response of human bone marrow-derived (BM) mesenchymal stem cells (MSCs) onto hybrid material scaffolds consisting of methacryloxypropyl trimethoxysilane, zirconium propoxide, and 2-(dimethylamino)ethyl methacrylate (DMAEMA). First, we use Direct fs Laser Writing, a 3D scaffolding technology to fabricate the complex structures. Subsequently, we investigate the morphology, viability and proliferation of BM-MSCs onto the hybrid scaffolds and examine the cellular response from different donors. Finally, we explore the effect of the materials' chemical composition on cell proliferation, employing three different material surfaces: (i) a hybrid consisting of methacryloxypropyl trimethoxysilane, zirconium propoxide and 50mol% DMAEMA, (ii) a hybrid material comprising methacryloxypropyl trimethoxysilane and zirconium propoxide, and (iii) a purely organic polyDMAEMA. Our results show a strong adhesion of BM-MSCs onto the hybrid material containing 50% DMAEMA from the first 2h after seeding, and up to several days, and a proliferation increase after 14 and 21days, similar to the polystyrene control, independent of cell donor. These findings support the potential use of our proposed cell-material combination in bone tissue engineering.

  17. Feasibility of ceramic-polymer composite cryogels as scaffolds for bone tissue engineering.

    PubMed

    Rodriguez-Lorenzo, Luis M; Saldaña, Laura; Benito-Garzón, Lorena; García-Carrodeguas, Raul; de Aza, Salvador; Vilaboa, Nuria; Román, Julio San

    2012-06-01

    The purpose of the current study was to investigate whether the cryopolymerization technique is capable of producing suitable scaffolds for bone tissue engineering. Cryopolymers made of 2-hydroxyethyl methacrylate and acrylic acid with (W1 and W20) and without (W0) wollastonite particles were prepared. The elastic modulus of the specimens rose one order of magnitude from W1 to W20. Total porosity reached 56% for W0, 72% for W1 and 36% for W20, with pore sizes of up to 2 mm, large interconnection sizes of up to 1 mm and small interconnection sizes of 50-80 µm on dry specimens. Cryogels swell up to 224 ± 17% for W0, 315 ± 18% for W1 and 231 ± 27% for W20 specimens, while maintaining the integrity of the bodies. Pore sizes > 5 mm can be observed for swollen specimens. The biocompatibility of the samples was tested using human mesenchymal stem cells isolated from bone marrow and adipose tissues. Both types of cells attached and grew on the three tested substrates, colonized their inner regions and organized an extracellular cell matrix. Fibronectin and osteopontin levels decreased in the media from cells cultured on W20 samples, likely due to increased binding on the ECM deposited by cells. The osteoprotegerin-to-receptor activator of nuclear factor-κB ligand secretion ratios increased with increasing wollastonite content. Altogether, these results indicate that an appropriate balance of surface properties and structure that favours stromal cell colonization in the porous cryogels can be achieved by modulating the amount of wollastonite.

  18. Facile Synthesis and Highly Electrocatalytic and Photocatalytic Performances of Nido-Like Ag/ZnO Composite Microspheres

    NASA Astrophysics Data System (ADS)

    Pan, Lu; Shen, Liying; Li, Li; Li, Chen

    2015-09-01

    Nido-like Ag/ZnO composites with different Ag contents were obtained by calcining each precursor prepared via a facile and easily controlled hydrothermal method. The resulting samples were characterized by x-ray diffraction and field emission scanning electron microscopy. The experiments demonstrated that Ag/ZnO composites were assembled by numerous flakes with a mean thickness of 150 nm. The electrocatalytic and photocatalytic performances of Ag/ZnO composites were investigated. The results indicated that the addition of Ag nanoparticles could effectively enhance the electrocatalytic and photocatalytic activity of the products. The sample with 4% Ag exhibited the highest electrocatalytic and photocatalytic activity.

  19. Physico-chemical and in vitro cellular properties of different calcium phosphate-bioactive glass composite chitosan-collagen (CaP@ChiCol) for bone scaffolds.

    PubMed

    Mooyen, Sukanya; Charoenphandhu, Narattaphol; Teerapornpuntakit, Jarinthorn; Thongbunchoo, Jirawan; Suntornsaratoon, Panan; Krishnamra, Nateetip; Tang, I-Ming; Pon-On, Weeraphat

    2016-05-17

    In the present study, scaffolds for bone tissue engineering applications were made by immersing the inorganic phases of three different calcium phosphate (CaPs) (hydroxyapatite (HA), tricalcium phosphate (TCP), and biphasic calcium phosphate (BCP)) mixing bioactive glass (15Ca:80Si:5P) (BG) with polycaprolactone (PCL) as a binder in an organic phase of chitosan/collagen (ChiCol) matrix (CaPBG@ChiCol). Porous scaffolds were obtained by freeze drying the combinations. The mechanical properties and in vitro growth of rat osteoblast-like UMR-106 cells were investigated. The investigation indicated that the compressive strength was controlled by the types of CaP. The highest compressive modulus of the composites was 479.77 MPa (23.84 MPa for compressive strength) which is for the BCPBG@ChiCol composite. Compressive modulus of 459.01 and 435.95 MPa with compressive strength of 22.73 and 17.89 MPa were observed for the HABG@ChiCol and TCPBG@ChiCol composites, respectively. In vitro cell availability and proliferation tests confirmed the osteoblast attachment and growth on the CaPBG@ChiCol surface. Comparing the scaffolds, cells grown on the BCPBG based composite showed the higher cell density. To test its bioactivity, BCPBG@ChiCol was chosen for MTT and ALP assays on UMR-106 cells. The results indicated that the UMR-106 cells were viable and had higher ALP activity as the culturing times were increased. Therefore, ChiCol-fabricated BCPBG scaffold shows promise for bone regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  20. Glass microsphere lubrication

    NASA Technical Reports Server (NTRS)

    Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

    1991-01-01

    The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the

  1. Platelet-rich plasma gel composited with nondegradable porous polyurethane scaffolds as a potential auricular cartilage alternative.

    PubMed

    Wang, Zhongshan; Qin, Haiyan; Feng, Zhihong; Zhao, Yimin

    2016-02-01

    Total auricular reconstruction is still a challenge, and autologous cartilage transplant is the main therapy so far. Tissue engineering provides a promising method for auricular cartilage reconstruction. However, although degradable framework demonstrated excellent initial cosmetic details, it is difficult to maintain the auricular contour over time and the metabolites tended to be harmful to human body. In this study, biocompatible and safe nondegradable elastic polyurethane was used to make porous scaffold in specific details by rapid prototyping technology. Platelet-rich plasma contains fibrin and abundant autologous growth factors, which was used as cell carriers for in vitro expanded cells. When crosslinking polyurethane framework, platelet-rich plasma and cells together, we successfully made polyurethane/platelet-rich plasma/cell composites, and implanted them into dorsal subcutaneous space of nude mice. The results showed that this method resulted in more even cell distribution and higher cell density, promoted chondrocyte proliferation, induced higher level expressions of aggrecan and type II collagen gene, increased content of newly developed glycosaminoglycans, and produced high-quality cartilaginous tissue. This kind of cartilage tissue engineering approach may be a potential promising alternative for external ear reconstruction.

  2. Multi-porous electroactive poly(L-lactic acid)/polypyrrole composite micro/nano fibrous scaffolds promote neurite outgrowth in PC12 cells.

    PubMed

    Yu, Qiaozhen; Xu, Shuiling; Zhang, Kuihua; Shan, Yongming

    2013-01-05

    In this study, poly(L-lactic acid)/ammonium persulfate doped-polypyrrole composite fibrous scaffolds with moderate conductivity were produced by combining electrospinning with in situ polymerization. PC12 cells were cultured on these fibrous scaffolds and their growth following electrical stimulation (0-20.0 μA stimulus intensity, for 1-4 days) was observed using inverted light microscopy, and scanning electron microscopy coupled with the MTT cell viability test. The results demonstrated that the poly(L-lactic acid)/ammonium persulfate doped-polypyrrole fibrous scaffold was a dual multi-porous micro/nano fibrous scaffold. An electrical stimulation with a current intensity 5.0-10.0 μA for about 2 days enhanced neuronal growth and neurite outgrowth, while a high current intensity (over 15.0 μA) suppressed them. These results indicate that electrical stimulation with a moderate current intensity for an optimum time frame can promote neuronal growth and neurite outgrowth in an intensity- and time-dependent manner.

  3. Glass microspheres for medical applications

    NASA Astrophysics Data System (ADS)

    Conzone, Samuel David

    Radioactive dysprosium lithium borate glass microspheres have been developed as biodegradable radiation delivery vehicles for the radiation synovectomy treatment of rheumatoid arthritis. Once injected into a diseased joint, the microspheres deliver a potent dose of radiation to the diseased tissue, while a non-uniform chemical reaction converts the glass into an amorphous, porous, hydrated dysprosium phosphate reaction product. The non-radioactive, lithium-borate component is dissolved from the glass (up to 94% weight loss), while the radioactive 165Dy reacts with phosphate anions in the body fluids, and becomes "chemically" trapped in a solid, dysprosium phosphate reaction product that has the same size as the un-reacted glass microsphere. Ethylene diamine tetraacetate (EDTA) chelation therapy can be used to dissolve the dysprosium phosphate reaction product after the radiation delivery has subsided. The dysprosium phosphate reaction product, which formed in vivo in the joint of a Sprague-Dawley rat, was dissolved by EDTA chelation therapy in <1 week, without causing any detectable joint damage. The combination of dysprosium lithium borate glass microspheres and EDTA chelation therapy provides an unique "tool" for the medical community, which can deliver a large dose (>100 Gy) of localized beta radiation to a treatment site within the body, followed by complete biodegradability. The non-uniform reaction process is a desirable characteristic for a biodegradable radiation delivery vehicle, but it is also a novel material synthesis technique that can convert a glass to a highly porous materials with widely varying chemical composition by simple, low-temperature, glass/solution reaction. The reaction product formed by nonuniform reaction occupies the same volume as the un-reacted glass, and after drying for 1 h at 300°C, has a specific surface area of ≈200 m2/g, a pore size of ≈30 nm, and a nominal crushing strength of ≈10 MPa. Finally, rhenium glass

  4. Mechanical properties, biological activity and protein controlled release by poly(vinyl alcohol)-bioglass/chitosan-collagen composite scaffolds: a bone tissue engineering applications.

    PubMed

    Pon-On, Weeraphat; Charoenphandhu, Narattaphol; Teerapornpuntakit, Jarinthorn; Thongbunchoo, Jirawan; Krishnamra, Nateetip; Tang, I-Ming

    2014-05-01

    In the present study, composite scaffolds made with different weight ratios (0.5:1, 1:1 and 2:1) of bioactive glass (15Ca:80Si:5P) (BG)/polyvinyl alcohol (PVA) (PVABG) and chitosan (Chi)/collagen (Col) (ChiCol) were prepared by three mechanical freeze-thaw followed by freeze-drying to obtain the porous scaffolds. The mechanical properties and the in vitro biocompatibility of the composite scaffolds to simulated body fluid (SBF) and to rat osteoblast-like UMR-106 cells were investigated. The results from the studies indicated that the porosity and compressive strength were controlled by the weight ratio of PVABG:ChiCol. The highest compressive modulus of the composites made was 214.64 MPa which was for the 1:1 weight ratio PVABG:ChiCol. Mineralization study in SBF showed the formation of apatite crystals on the PVABG:ChiCol surface after 7 days of incubation. In vitro cell availability and proliferation tests confirmed the osteoblast attachment and growth on the PVABG:ChiCol surface. MTT and ALP tests on the 1:1 weight ratio PVABG:ChiCol composite indicated that the UMR-106 cells were viable. Alkaline phosphatase activity was found to increase with increasing culturing time. In addition, we showed the potential of PVABG:ChiCol drug delivery through PBS solution studies. 81.14% of BSA loading had been achieved and controlled release for over four weeks was observed. Our results indicated that the PVABG:ChiCol composites, especially the 1:1 weight ratio composite exhibited significantly improved mechanical, mineral deposition, biological properties and controlled release. This made them potential candidates for bone tissue engineering applications.

  5. Development of a new carbon nanotube-alginate-hydroxyapatite tricomponent composite scaffold for application in bone tissue engineering.

    PubMed

    Rajesh, Rajendiran; Ravichandran, Y Dominic

    2015-01-01

    In recent times, tricomponent scaffolds prepared from naturally occurring polysaccharides, hydroxyapatite, and reinforcing materials have been gaining increased attention in the field of bone tissue engineering. In the current work, a tricomponent scaffold with an oxidized multiwalled carbon nanotube (fMWCNT)-alginate-hydroxyapatite with the required porosity was prepared for the first time by a freeze-drying method and characterized using analytical techniques. The hydroxyapatite for the scaffold was isolated from chicken bones by thermal calcination at 800°C. The Fourier transform infrared spectra and X-ray diffraction data confirmed ionic interactions and formation of the fMWCNT-alginate-hydroxyapatite scaffold. Interconnected porosity with a pore size of 130-170 µm was evident from field emission scanning electron microscopy. The total porosity calculated using the liquid displacement method was found to be 93.85%. In vitro biocompatibility and cell proliferation on the scaffold was checked using an MG-63 cell line by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and cell attachment by Hoechst stain assay. In vitro studies showed better cell proliferation, cell differentiation, and cell attachment on the prepared scaffold. These results indicate that this scaffold could be a promising candidate for bone tissue engineering.

  6. Injectable polyurethane composite scaffolds delay wound contraction and support cellular infiltration and remodeling in rat excisional wounds.

    PubMed

    Adolph, Elizabeth J; Hafeman, Andrea E; Davidson, Jeffrey M; Nanney, Lillian B; Guelcher, Scott A

    2012-02-01

    Injectable scaffolds present compelling opportunities for wound repair and regeneration because of their ability to fill irregularly shaped defects and deliver biologics such as growth factors. In this study, we investigated the properties of injectable polyurethane (PUR) biocomposite scaffolds and their application in cutaneous wound repair using a rat excisional model. The scaffolds have a minimal reaction exotherm and clinically relevant working and setting times. Moreover, the biocomposites have mechanical and thermal properties consistent with rubbery elastomers. In the rat excisional wound model, injection of settable biocomposite scaffolds stented the wounds at early time points, resulting in a regenerative rather than a scarring phenotype at later time points. Measurements of wound length and thickness revealed that the treated wounds were less contracted at day 7 compared to blank wounds. Analysis of cell proliferation and apoptosis showed that the scaffolds were biocompatible and supported tissue ingrowth. Myofibroblast formation and collagen fiber organization provided evidence that the scaffolds have a positive effect on extracellular matrix remodeling by disrupting the formation of an aligned matrix under elevated tension. In summary, we have developed an injectable biodegradable PUR biocomposite scaffold that enhances cutaneous wound healing in a rat model.

  7. Development of a new carbon nanotube–alginate–hydroxyapatite tricomponent composite scaffold for application in bone tissue engineering

    PubMed Central

    Rajesh, Rajendiran; Dominic Ravichandran, Y

    2015-01-01

    In recent times, tricomponent scaffolds prepared from naturally occurring polysaccharides, hydroxyapatite, and reinforcing materials have been gaining increased attention in the field of bone tissue engineering. In the current work, a tricomponent scaffold with an oxidized multiwalled carbon nanotube (fMWCNT)–alginate–hydroxyapatite with the required porosity was prepared for the first time by a freeze-drying method and characterized using analytical techniques. The hydroxyapatite for the scaffold was isolated from chicken bones by thermal calcination at 800°C. The Fourier transform infrared spectra and X-ray diffraction data confirmed ionic interactions and formation of the fMWCNT–alginate–hydroxyapatite scaffold. Interconnected porosity with a pore size of 130–170 µm was evident from field emission scanning electron microscopy. The total porosity calculated using the liquid displacement method was found to be 93.85%. In vitro biocompatibility and cell proliferation on the scaffold was checked using an MG-63 cell line by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and cell attachment by Hoechst stain assay. In vitro studies showed better cell proliferation, cell differentiation, and cell attachment on the prepared scaffold. These results indicate that this scaffold could be a promising candidate for bone tissue engineering. PMID:26491303

  8. In vivo degradation of a poly(propylene fumarate)/beta-tricalcium phosphate injectable composite scaffold.

    PubMed

    Peter, S J; Miller, S T; Zhu, G; Yasko, A W; Mikos, A G

    1998-07-01

    This study was designed to investigate the in vivo biodegration and biocompatibility of a poly(propylene fumarate) (PPF)-based orthopedic biomaterial. The effects of varying the PPF to N-vinyl pyrrolidinone ratio and PPF to beta-tricalcium phosphate content were studied. The composite mechanical properties and local tissue interactions were analyzed over 12 weeks. An initial increase in both compressive modulus and strength was seen for composite formulations that incorporated beta-tricalcium phosphate. The samples incorporating a higher PPF to N-vinyl pyrrolidinone ratio reached a maximal compressive strength of 7.7 MPa and a maximal compressive modulus of 191.4 MPa at 3 weeks. The lower PPF to N-vinyl pyrrolidinone ratio samples gained a maximum compressive strength of 7.5 MPa initially and a compressive modulus of 134.0 MPa at 1 week. At 6 weeks, all samples for formulations incorporating beta-tricalcium phosphate crumbled upon removal and were not mechanically tested. Samples that did not incorporate beta-tricalcium phosphate were very weak and insufficient for bone replacement at the 4-day time point and beyond. Tissue interactions resulted in a mild inflammatory response at the initial time points and mature fibrous encapsulation by 12 weeks.

  9. Polymer assisted hydroxyapatite microspheres suitable for biomedical application.

    PubMed

    Sinha, A; Mishra, T; Ravishankar, N

    2008-05-01

    Hollow Microspheres of hydroxyapatite-polymer composite can be used as carriers in drug delivery and fillers in tissue engineering. Based on the concept of soft chemistry, a battery of technique is available in the literature to synthesize hollow microspheres, however, an economically viable synthesis route, having good control over the microarchitect and easy to be scaled up, is yet to be developed. Polymer matrix mediated synthesis of inorganic nanoparticles is known to synthesize nanoparticles with controlled morphology and dimensions. It is termed as biomimetic synthesis. Integrating the biomimetic synthesis of nano-particles and spray drying techniques, a novel process of producing hydroxyapatite-polymer composite hollow microspheres is briefly discussed here.

  10. Making Polymeric Microspheres

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu; Hyson, Michael T.; Chung, Sang-Kun; Colvin, Michael S.; Chang, Manchium

    1989-01-01

    Combination of advanced techniques yields uniform particles for biomedical applications. Process combines ink-jet and irradiation/freeze-polymerization techniques to make polymeric microspheres of uniform size in diameters from 100 to 400 micrometer. Microspheres used in chromatography, cell sorting, cell labeling, and manufacture of pharmaceutical materials.

  11. Production of hollow aerogel microspheres

    SciTech Connect

    Upadhye, R.S.; Henning, S.A.

    1990-12-31

    A method is described for making hollow aerogel microspheres of 800--1200{mu} diameter and 100--300{mu} wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  12. Production of hollow aerogel microspheres

    DOEpatents

    Upadhye, Ravindra S.; Henning, Sten A.

    1993-01-01

    A method is described for making hollow aerogel microspheres of 800-1200 .mu. diameter and 100-300 .mu. wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  13. Microspheres in Plasma Display Panels

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Filling small bubbles of molten glass with gases is just as difficult as it sounds, but the technical staff at NASA is not known to shy away from a difficult task. When Microsphere Systems, Inc. (MSI), of Ypsilanti, Michigan, and Imaging Systems Technology, Inc. (IST), of Toledo, Ohio, were trying to push the limits of plasma displays but were having difficulty with the designs, NASA s Glenn Garrett Morgan Commercialization Initiative (GMCI) assembled key personnel at Glenn Research Center and Ohio State University for a brainstorming session to come up with a solution for the companies. They needed a system that could produce hollow, glass micro-sized spheres (microspheres) that could be filled with a variety of gasses. But the extremely high temperature required to force the micro-sized glass bubbles to form at the tip of a metal nozzle resulted in severe discoloration of the microspheres. After countless experiments on various glass-metal combinations, they had turned to the GMCI for help. NASA experts in advanced metals, ceramics, and glass concluded that a new design approach was necessary. The team determined that what was needed was a phosphate glass composition that would remain transparent, and they went to work on a solution. Six weeks later, using the design tips from the NASA team, Tim Henderson, president of MSI, had designed a new system in which all surfaces in contact with the molten glass would be ceramic instead of metal. Meanwhile, IST was able to complete a Phase I Small Business Innovation Research (SBIR) grant supported by the National Science Foundation (NSF) and supply a potential customer with samples of the microspheres for evaluation as filler materials for high-performance insulations.

  14. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolysis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  15. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolyis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  16. A reproducible accelerated in vitro release testing method for PLGA microspheres.

    PubMed

    Shen, Jie; Lee, Kyulim; Choi, Stephanie; Qu, Wen; Wang, Yan; Burgess, Diane J

    2016-02-10

    The objective of the present study was to develop a discriminatory and reproducible accelerated in vitro release method for long-acting PLGA microspheres with inner structure/porosity differences. Risperidone was chosen as a model drug. Qualitatively and quantitatively equivalent PLGA microspheres with different inner structure/porosity were obtained using different manufacturing processes. Physicochemical properties as well as degradation profiles of the prepared microspheres were investigated. Furthermore, in vitro release testing of the prepared risperidone microspheres was performed using the most common in vitro release methods (i.e., sample-and-separate and flow through) for this type of product. The obtained compositionally equivalent risperidone microspheres had similar drug loading but different inner structure/porosity. When microsphere particle size appeared similar, porous risperidone microspheres showed faster microsphere degradation and drug release compared with less porous microspheres. Both in vitro release methods investigated were able to differentiate risperidone microsphere formulations with differences in porosity under real-time (37 °C) and accelerated (45 °C) testing conditions. Notably, only the accelerated USP apparatus 4 method showed good reproducibility for highly porous risperidone microspheres. These results indicated that the accelerated USP apparatus 4 method is an appropriate fast quality control tool for long-acting PLGA microspheres (even with porous structures).

  17. Micromechanical finite element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone:hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering

    PubMed Central

    Eshraghi, Shaun; Das, Suman

    2012-01-01

    Bioresorbable scaffolds with mechanical properties suitable for bone tissue engineering were fabricated from polycaprolactone (PCL) and hydroxyapatite (HA) by selective laser sintering (SLS) and modeled by finite element analysis (FEA). Both solid gage parts and scaffolds having 1-D, 2-D and 3-D orthogonal, periodic porous architectures were made with 0, 10, 20 and 30% HA by volume. PCL:HA scaffolds manufactured by SLS had nearly full density (99%) in the designed solid regions and had excellent geometric and dimensional control. Through optimization of the SLS process, the compressive moduli for our solid gage parts and scaffolds are the highest reported in the literature for additive manufacturing. The compressive moduli of solid gage parts were 299.3, 311.2, 415.5 and 498.3 MPa for PCL:HA loading at 100:0, 90:10, 80:20 and 70:30 respectively. The compressive effective stiffness tended to increase as the loading of HA was increased and the designed porosity was lowered. In the case of the most 3-D porous scaffold, the compressive modulus more than doubled from 14.9 MPa to 36.2 MPa when changing the material from 100:0 to 70:30 PCL:HA. A micromechanical finite element analysis (FEA) model was developed to investigate the reinforcement effect of HA loading on the compressive modulus of the bulk material. Using a first-principles based approach, the random distribution of HA particles in a solidified PCL matrix was modeled for any loading of HA to predict the bulk mechanical properties of the composites. The bulk mechanical properties were also used for FEA of the scaffold geometries. Results of the FEA were found to be in good agreement with experimental mechanical testing. The development of patient and site-specific composite tissue engineering constructs with tailored properties can be seen as a direct extension of this work on computational design, a priori modeling of mechanical properties and direct digital manufacturing. PMID:22522129

  18. Liquid-liquid two phase systems for the production of porous hydrogels and hydrogel microspheres for biomedical applications: A tutorial review

    PubMed Central

    Elbert, Donald L.

    2010-01-01

    Macroporous hydrogels may have direct applications in regenerative medicine as scaffolds to support tissue formation. Hydrogel microspheres may be used as drug delivery vehicles or as building blocks to assemble modular scaffolds. A variety of techniques exist to produce macroporous hydrogels and hydrogel microspheres. A subset of these relies on liquid-liquid two phase systems. Within this subset, vastly different types of polymerization processes are found. In this review, the history, terminology and classification of liquid-liquid two phase polymerization and crosslinking are described. Instructive examples of hydrogel microsphere and macroporous scaffold formation by precipitation/dispersion, emulsion and suspension polymerizations are used to illustrate the nature of these processes. The role of the kinetics of phase separation in determining the morphology of scaffolds and microspheres is also delineated. Brief descriptions of miniemulsion, microemulsion polymerization and ionotropic gelation are also included. PMID:20659596

  19. Surface wrinkling on polydimethylsiloxane microspheres via wet surface chemical oxidation.

    PubMed

    Yin, Jian; Han, Xue; Cao, Yanping; Lu, Conghua

    2014-07-16

    Here we introduce a simple low-cost yet robust method to realize spontaneously wrinkled morphologies on spherical surfaces. It is based on surface chemical oxidation of aqueous-phase-synthesized polydimethylsiloxane (PDMS) microspheres in the mixed H2SO4/HNO3/H2O solution. Consequently, curvature and overstress-sensitive wrinkles including dimples and labyrinth patterns are successfully induced on the resulting oxidized PDMS microspheres. A power-law dependence of the wrinkling wavelength on the microsphere radius exists. The effects of experimental parameters on these tunable spherical wrinkles have been systematically investigated, when the microspheres are pre-deposited on a substrate. These parameters include the radius and modulus of microspheres, the mixed acid solution composition, the oxidation duration, and the water washing post-treatment. Meanwhile, the complicated chemical oxidation process has also been well studied by in-situ optical observation via the microsphere system, which represents an intractable issue in a planar system. Furthermore, we realize surface wrinkled topographies on the whole microspheres at a large scale, when microspheres are directly dispersed in the mixed acid solution for surface oxidation. These results indicate that the introduced wet surface chemical oxidation has the great potential to apply to other complicated curved surfaces for large-scale generation of well-defined wrinkling patterns, which endow the solids with desired physical properties.

  20. Surface Wrinkling on Polydimethylsiloxane Microspheres via Wet Surface Chemical Oxidation

    PubMed Central

    Yin, Jian; Han, Xue; Cao, Yanping; Lu, Conghua

    2014-01-01

    Here we introduce a simple low-cost yet robust method to realize spontaneously wrinkled morphologies on spherical surfaces. It is based on surface chemical oxidation of aqueous-phase-synthesized polydimethylsiloxane (PDMS) microspheres in the mixed H2SO4/HNO3/H2O solution. Consequently, curvature and overstress-sensitive wrinkles including dimples and labyrinth patterns are successfully induced on the resulting oxidized PDMS microspheres. A power-law dependence of the wrinkling wavelength on the microsphere radius exists. The effects of experimental parameters on these tunable spherical wrinkles have been systematically investigated, when the microspheres are pre-deposited on a substrate. These parameters include the radius and modulus of microspheres, the mixed acid solution composition, the oxidation duration, and the water washing post-treatment. Meanwhile, the complicated chemical oxidation process has also been well studied by in-situ optical observation via the microsphere system, which represents an intractable issue in a planar system. Furthermore, we realize surface wrinkled topographies on the whole microspheres at a large scale, when microspheres are directly dispersed in the mixed acid solution for surface oxidation. These results indicate that the introduced wet surface chemical oxidation has the great potential to apply to other complicated curved surfaces for large-scale generation of well-defined wrinkling patterns, which endow the solids with desired physical properties. PMID:25028198

  1. Comparison of Osteogenesis between Adipose-Derived Mesenchymal Stem Cells and Their Sheets on Poly-ε-Caprolactone/β-Tricalcium Phosphate Composite Scaffolds in Canine Bone Defects

    PubMed Central

    Kim, Yongsun; Lee, Seung Hoon; Kang, Byung-jae; Kim, Wan Hee; Yun, Hui-suk

    2016-01-01

    Multipotent mesenchymal stem cells (MSCs) and MSC sheets have effective potentials of bone regeneration. Composite polymer/ceramic scaffolds such as poly-ε-caprolactone (PCL)/β-tricalcium phosphate (β-TCP) are widely used to repair large bone defects. The present study investigated the in vitro osteogenic potential of canine adipose-derived MSCs (Ad-MSCs) and Ad-MSC sheets. Composite PCL/β-TCP scaffolds seeded with Ad-MSCs or wrapped with osteogenic Ad-MSC sheets (OCS) were also fabricated and their osteogenic potential was assessed following transplantation into critical-sized bone defects in dogs. The alkaline phosphatase (ALP) activity of osteogenic Ad-MSCs (O-MSCs) and OCS was significantly higher than that of undifferentiated Ad-MSCs (U-MSCs). The ALP, runt-related transcription factor 2, osteopontin, and bone morphogenetic protein 7 mRNA levels were upregulated in O-MSCs and OCS as compared to U-MSCs. In a segmental bone defect, the amount of newly formed bone was greater in PCL/β-TCP/OCS and PCL/β-TCP/O-MSCs/OCS than in the other groups. The OCS exhibit strong osteogenic capacity, and OCS combined with a PCL/β-TCP composite scaffold stimulated new bone formation in a critical-sized bone defect. These results suggest that the PCL/β-TCP/OCS composite has potential clinical applications in bone regeneration and can be used as an alternative treatment modality in bone tissue engineering. PMID:27610141

  2. Hierarchically Macro-Mesoporous Pt/γ-Al2O3 Composite Microspheres for Efficient Formaldehyde Oxidation at Room Temperature

    PubMed Central

    Nie, Longhui; Meng, Aiyun; Yu, Jiaguo; Jaroniec, Mietek

    2013-01-01

    Room temperature catalytic oxidation by noble metals is considered to be the most promising strategy for the removal of HCHO, which is one of the major indoor air pollutants. Hierarchically macro-mesoporous structured Pt/γ-Al2O3 hollow spheres with open and accessible pores were synthesized and used for catalytic oxidative decomposition of HCHO at room temperature. The prepared composite hollow spheres showed higher catalytic activity than the conventional nanoparticle supports, which is mainly due to their hierarchical macro-mesoporous structure facilitating diffusion of reactants and products, and the high dispersion of accessible catalytic Pt nanoparticles. This work may contribute to the development of hierarchically structured materials and high-performance catalysts for indoor air purification and related catalytic processes. PMID:24225532

  3. Design, fabrication and perivascular implantation of bioactive scaffolds engineered with human adventitial progenitor cells for stimulation of arteriogenesis in peripheral ischemia.

    PubMed

    Carrabba, M; De Maria, C; Oikawa, A; Reni, C; Rodriguez-Arabaolaza, I; Spencer, H; Slater, S; Avolio, E; Dang, Z; Spinetti, G; Madeddu, P; Vozzi, G

    2016-03-24

    Cell therapy represents a promising option for revascularization of ischemic tissues. However, injection of dispersed cells is not optimal to ensure precise homing into the recipient's vasculature. Implantation of cell-engineered scaffolds around the occluded artery may obviate these limitations. Here, we employed the synthetic polymer polycaprolactone for fabrication of 3D woodpile- or channel-shaped scaffolds by a computer-assisted writing system (pressure assisted micro-syringe square), followed by deposition of gelatin (GL) nanofibers by electro-spinning. Scaffolds were then cross-linked with natural (genipin, GP) or synthetic (3-glycidyloxy-propyl-trimethoxy-silane, GPTMS) agents to improve mechanical properties and durability in vivo. The composite scaffolds were next fixed by crown inserts in each well of a multi-well plate and seeded with adventitial progenitor cells (APCs, 3 cell lines in duplicate), which were isolated/expanded from human saphenous vein surgical leftovers. Cell density, alignment, proliferation and viability were assessed 1 week later. Data from in vitro assays showed channel-shaped/GPTMS-crosslinked scaffolds confer APCs with best alignment and survival/growth characteristics. Based on these results, channel-shaped/GPTMS-crosslinked scaffolds with or without APCs were implanted around the femoral artery of mice with unilateral limb ischemia. Perivascular implantation of scaffolds accelerated limb blood flow recovery, as assessed by laser Doppler or fluorescent microspheres, and increased arterial collaterals around the femoral artery and in limb muscles compared with non-implanted controls. Blood flow recovery and perivascular arteriogenesis were additionally incremented by APC-engineered scaffolds. In conclusion, perivascular application of human APC-engineered scaffolds may represent a novel option for targeted delivery of therapeutic cells in patients with critical limb ischemia.

  4. POROUS WALL, HOLLOW GLASS MICROSPHERES

    SciTech Connect

    Sexton, W.

    2012-06-30

    Hollow Glass Microspheres (HGM) is not a new technology. All one has to do is go to the internet and Google{trademark} HGM. Anyone can buy HGM and they have a wide variety of uses. HGM are usually between 1 to 100 microns in diameter, although their size can range from 100 nanometers to 5 millimeters in diameter. HGM are used as lightweight filler in composite materials such as syntactic foam and lightweight concrete. In 1968 a patent was issued to W. Beck of the 3M{trademark} Company for 'Glass Bubbles Prepared by Reheating Solid Glass Particles'. In 1983 P. Howell was issued a patent for 'Glass Bubbles of Increased Collapse Strength' and in 1988 H. Marshall was issued a patent for 'Glass Microbubbles'. Now Google{trademark}, Porous Wall, Hollow Glass Microspheres (PW-HGMs), the key words here are Porous Wall. Almost every article has its beginning with the research done at the Savannah River National Laboratory (SRNL). The Savannah River Site (SRS) where SRNL is located has a long and successful history of working with hydrogen and its isotopes for national security, energy, waste management and environmental remediation applications. This includes more than 30 years of experience developing, processing, and implementing special ceramics, including glasses for a variety of Department of Energy (DOE) missions. In the case of glasses, SRS and SRNL have been involved in both the science and engineering of vitreous or glass based systems. As a part of this glass experience and expertise, SRNL has developed a number of niches in the glass arena, one of which is the development of porous glass systems for a variety of applications. These porous glass systems include sol gel glasses, which include both xerogels and aerogels, as well as phase separated glass compositions, that can be subsequently treated to produce another unique type of porosity within the glass forms. The porous glasses can increase the surface area compared to 'normal glasses of a 1 to 2 order of

  5. Microsphere Insulation Panels

    NASA Technical Reports Server (NTRS)

    Mohling, R.; Allen, M.; Baumgartner, R.

    2006-01-01

    Microsphere insulation panels (MIPs) have been developed as lightweight, longlasting replacements for the foam and vacuum-jacketed systems heretofore used for thermally insulating cryogenic vessels and transfer ducts. The microsphere core material of a typical MIP consists of hollow glass bubbles, which have a combination of advantageous mechanical, chemical, and thermal-insulation properties heretofore available only separately in different materials. In particular, a core filling of glass microspheres has high crush strength and low density, is noncombustible, and performs well in soft vacuum.

  6. The Effects of rhBMP-2 Released from Biodegradable Polyurethane/Microsphere Composite Scaffolds on New Bone Formation in Rat Femora

    DTIC Science & Technology

    2009-09-17

    was purchased from Alfa Aesar (Ward Hill, MA). Dichloromethane ( DCM ) and glucose were from Acros Organics (Morris Plains, NJ). Hexamethylene diiso...and PEG (4600 Da), at a ratio of 9:1, were dissolved in DCM at polymer concentrations of 10% and 5% for large and small size particles, respec- tively...A glucose solution of BSA–FITC (fluoroisothiocyanate-labeled bovine serum albumin) or rhBMP-2 was added to the polymer DCM solution, followed by soni

  7. Organic aerogel microspheres

    DOEpatents

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1999-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  8. Organic aerogel microspheres

    DOEpatents

    Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

    1999-06-01

    Organic aerogel microspheres are disclosed which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonstick gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  9. Compartmentalization in proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Brooke, S.; Fox, S. W.

    1977-01-01

    Proteinoid microspheres with stable internal compartments and internal structure are made from acidic proteinoid and basic proteinoid with calcium. The populations of microspheres are characterized by a wide diversity of structure. A model of primitive intracellular communication is suggested by the observed movement of internal particles between compartments of a multicompartmentalized unit. Differential response to pH change and to temperature change has been demonstrated within one population and suggests one mode of adaptive selection among primordial cell populations.

  10. Preparation of chitosan/nano hydroxyapatite organic-inorganic hybrid microspheres for bone repair.

    PubMed

    Chen, Jingdi; Pan, Panpan; Zhang, Yujue; Zhong, Shengnan; Zhang, Qiqing

    2015-10-01

    In this work, we encapsulated icariin (ICA) into chitosan (CS)/nano hydroxyapatite (nHAP) composite microspheres to form organic-inorganic hybrid microspheres for drug delivery carrier. The composition and morphology of composite microspheres were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry- thermogravimetric analysis (DSC-TGA). Moreover, we further studied the performance of swelling properties, degradation properties and drug release behavior of the microspheres. ICA, the extract of traditional Chinese medicine-epimedium, was combined to study drug release properties of the microspheres. ICA loaded microspheres take on a sustained release behavior, which can be not only ascribed to electrostatic interaction between reactive negative hydroxyl (OH) of ICA and positive amine groups (NH₂) of CS, but also depended on the homogeneous dispersion of HAP nanoparticles inside CS organic matrix. In addition, the adhesion and morphology of osteoblasts were detected by inverted fluorescence microscopy. The biocompatibility of CS/nHAP/ICA microspheres was evaluated by the MTT cytotoxicity assay, Hoechst 33258 and PI fluorescence staining. These studies demonstrate that composite microspheres provide a suitable microenvironment for osteoblast attachment and proliferation. It can be speculated that the ICA loaded CS-based organic-inorganic hybrid microspheres might have potential applications in drug delivery systems.

  11. R & D of an Innovative Composite Scaffold Incorporated with Phytoestrogenic Icaritin for Treatment of Steroid-associated Osteonecrosis Lesion in Rabbits

    NASA Astrophysics Data System (ADS)

    Xie, Xinhui

    Epimedium -derived flavonoids (EF), is found to be able to facilitate matrix calcification, stimulate osteogenesis and inhibit adipogenesis of BMSCs. The present thesis work hypothesizes that the PLGA/TCP incorporating Icaritin to form a porous composite scaffold is osteopromotive and is able to enhance the repair of necrotic bone defect with steroid-associated ON after core decompression. The findings implied that the porous composite PLGA/TCP/Icaritin scaffold would be an appropriate osteopromotive scaffold implant or bone graft substitute biomaterial for potential application in skeletal tissue engineering. It was the first study to incorporate or homogenize the Chinese herbal molecule into the porous composite biomaterials for medical testing. Though the osteopromotive effect in ON model was observed in vivo, the molecular mechanism of osteogenesis remains for future investigations. (Abstract shortened by UMI.)

  12. Evaluation of the Thermosensitive Release Properties of Microspheres Containing an Agrochemical Compound.

    PubMed

    Terada, Takatoshi; Ohtsubo, Toshiro; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

    2017-01-01

    The purpose of this study was to develop a deeper understanding of the key physicochemical parameters involved in the release profiles of microsphere-encapsulated agrochemicals at different temperatures. Microspheres consisting of different polyurethanes (PUs) were prepared using our previously reported solventless microencapsulation technique. Notably, these microspheres exhibited considerable differences in their thermodynamic characteristics, including their glass transition temperature (Tg), extrapolated onset temperature (To) and extrapolated end temperature (Te). At test temperatures below the To of the PU, only 5-10% of the agrochemical was rapidly released from the microspheres within 1 d, and none was released thereafter. However, at test temperatures above the To of the PU, the rate of agrochemical release gradually increased with increasing temperatures, and the rate of release from the microspheres was dependent on the composition of the PU. Taken together, these results show that the release profiles of the microspheres were dependent on their thermodynamic characteristics and changes in their PU composition.

  13. Synergistic Ternary Composite (Carbon/Fe3 O4 @Graphene) with Hollow Microspherical and Robust Structure for Li-Ion Storage.

    PubMed

    Li, Xingxing; Zheng, Xueying; Shao, Jie; Gao, Tian; Shi, Qiang; Qu, Qunting

    2016-01-04

    The electrode materials with hollow structure and/or graphene coating are expected to exhibit outstanding electrochemical performances in energy-storage systems. 2D graphene-wrapped hollow C/Fe3 O4 microspheres are rationally designed and fabricated by a novel facile and scalable strategy. The core@double-shell structure SPS@FeOOH@GO (SPS: sulfonated polystyrene, GO: graphene oxide) microspheres are first prepared through a simple one-pot approach and then transformed into C/Fe3 O4 @G (G: graphene) after calcination at 500 °C in Ar. During calcination, the Kirkendall effect resulting from the diffusion/reaction of SPS-derived carbon and FeOOH leads to the formation of hollow structure carbon with Fe3 O4 nanoparticles embedded in it. In the rationally constructed architecture of C/Fe3 O4 @G, the strongly coupled C/Fe3 O4 hollow microspheres are further anchored onto 2D graphene networks, achieving a strong synergetic effect between carbon, Fe3 O4 , and graphene. As an anode material of Li-ion batteries (LIBs), C/Fe3 O4 @G manifests a high reversible capacity, excellent rate behavior, and outstanding long-term cycling performance (1208 mAh g(-1) after 200 cycles at 100 mA g(-1) ).

  14. Three-dimensional, bioactive, biodegradable, polymer-bioactive glass composite scaffolds with improved mechanical properties support collagen synthesis and mineralization of human osteoblast-like cells in vitro.

    PubMed

    Lu, Helen H; El-Amin, Saadiq F; Scott, Kimberli D; Laurencin, Cato T

    2003-03-01

    In the past decade, tissue engineering-based bone grafting has emerged as a viable alternative to biological and synthetic grafts. The biomaterial component is a critical determinant of the ultimate success of the tissue-engineered graft. Because no single existing material possesses all the necessary properties required in an ideal bone graft, our approach has been to develop a three dimensional (3-D), porous composite of polylactide-co-glycolide (PLAGA) and 45S5 bioactive glass (BG) that is biodegradable, bioactive, and suitable as a scaffold for bone tissue engineering (PLAGA-BG composite). The objectives of this study were to examine the mechanical properties of a PLAGA-BG matrix, to evaluate the response of human osteoblast-like cells to the PLAGA-BG composite, and to evaluate the ability of the composite to form a surface calcium phosphate layer in vitro. Structural and mechanical properties of PLAGA-BG were measured, and the formation of a surface calcium phosphate layer was evaluated by surface analysis methods. The growth and differentiation of human osteoblast-like cells on PLAGA-BG were also examined. A hypothesis was that the combination of PLAGA with BG would result in a biocompatible and bioactive composite, capable of supporting osteoblast adhesion, growth and differentiation, with mechanical properties superior to PLAGA alone. The addition of bioactive glass granules to the PLAGA matrix resulted in a structure with higher compressive modulus than PLAGA alone. Moreover, the PLAGA-BA composite was found to be a bioactive material, as it formed surface calcium phosphate deposits in a simulated body fluid (SBF), and in the presence of cells and serum proteins. The composite supported osteoblast-like morphology, stained positively for alkaline phosphatase, and supported higher levels of Type I collagen synthesis than tissue culture polystyrene controls. We have successfully developed a degradable, porous, polymer bioactive glass composite possessing

  15. Method for sizing hollow microspheres

    DOEpatents

    Farnum, E.H.; Fries, R.J.

    1975-10-29

    Hollow Microspheres may be effectively sized by placing them beneath a screen stack completely immersed in an ultrasonic bath containing a liquid having a density at which the microspheres float and ultrasonically agitating the bath.

  16. Enhanced osteogenesis and angiogenesis by mesoporous hydroxyapatite microspheres-derived simvastatin sustained release system for superior bone regeneration

    PubMed Central

    Yu, Wei-Lin; Sun, Tuan-Wei; Qi, Chao; Zhao, Hua-Kun; Ding, Zhen-Yu; Zhang, Zhi-Wang; Sun, Ben-Ben; Shen, Ji; Chen, Feng; Zhu, Ying-Jie; Chen, Dao-Yun; He, Yao-Hua

    2017-01-01

    Biomaterials with both excellent osteogenic and angiogenic activities are desirable to repair massive bone defects. In this study, simvastatin with both osteogenic and angiogenic activities was incorporated into the mesoporous hydroxyapatite microspheres (MHMs) synthesized through a microwave-assisted hydrothermal method using fructose 1,6-bisphosphate trisodium salt (FBP) as an organic phosphorous source. The effects of the simvastatin-loaded MHMs (S-MHMs) on the osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and angiogenesis in EA.hy926 cells were investigated. The results showed that the S-MHMs not only enhanced the expression of osteogenic markers in rBMSCs but also promoted the migration and tube formation of EA.hy926 cells. Furthermore, the S-MHMs were incorporated into collagen matrix to construct a novel S-MHMs/collagen composite scaffold. With the aid of MHMs, the water-insoluble simvastatin was homogenously incorporated into the hydrophilic collagen matrix and presented a sustained release profile. In vivo experiments showed that the S-MHMs/collagen scaffolds enhanced the bone regeneration and neovascularization simultaneously. These results demonstrated that the water-insoluble simvastatin could be incorporated into the MHMs and maintained its biological activities, more importantly, the S-MHMs/collagen scaffolds fabricated in this study are of immense potential in bone defect repair by enhancing osteogenesis and angiogenesis simultaneously. PMID:28287178

  17. Design and application of chitosan/biphasic calcium phosphate porous scaffolds for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Sendemir-Urkmez, Aylin

    For the restoration of maxillofacial bone tissue, design of novel tissue engineering scaffolds capable of inducing bone remodeling through the delivery of mesenchymal stem cells (MSCs) and an angiogenic growth factor, directly at the site of the defect was investigated in order to replace autogenous cancellous bone grafts with synthetic materials. Porous, three dimensional scaffolds were fabricated by a freeze drying method. In culture media, biphasic calcium phosphate particles within chitosan produced a surface reprecipitate of a composition similar to natural apatite that led to a uniform distribution of cells and mineralized ECM through chemotaxis. Further, the reprecipitation regulated the differentiation pathway and phenotype commitment of stem cells by altering the initial cell attachment morphology and actin cytoskeleton organization. In order to induce neovascularization after implantation, constructs were designed to be loaded with gelatin microspheres that delivered basic fibroblast growth factor (bFGF), a potent angiogenic factor. In vitro proliferation tests performed on fibroblastic cells showed no detectible loss of bFGF activity when delivered through enzymatic degradation of gelatin. Laser scanning confocal microscopy was used to demonstrate that gelatin microspheres can be injected evenly into cell-scaffold constructs owing to the spongy characteristics of the scaffold. To examine the binding interactions of bFGF with surface bound gelatin, a label free biosensor system, Biomolecular INteraction Detection sensor (BIND) was used. Results confirm that the principal interaction that takes place between bFGF and gelatin is electrostatic. Cell loaded tissue engineered constructs were produced in vitro at clinically relevant sizes and implanted with and without bFGF into a porcine mandibular defect model. Tissue engineered constructs facilitated the healing of mandibular defects only if combined with delivery of bFGF via gelatin microspheres. b

  18. Optimized fabrication of Ca-P/PHBV nanocomposite scaffolds via selective laser sintering for bone tissue engineering.

    PubMed

    Duan, Bin; Cheung, Wai Lam; Wang, Min

    2011-03-01

    Biomaterials for scaffolds and scaffold fabrication techniques are two key elements in scaffold-based tissue engineering. Nanocomposites that consist of biodegradable polymers and osteoconductive bioceramic nanoparticles and advanced scaffold manufacturing techniques, such as rapid prototyping (RP) technologies, have attracted much attention for developing new bone tissue engineering strategies. In the current study, poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) microspheres and calcium phosphate (Ca-P)/PHBV nanocomposite microspheres were fabricated using the oil-in-water (O/W) and solid-in-oil-in-water (S/O/W) emulsion solvent evaporation methods. The microspheres with suitable sizes were then used as raw materials for scaffold fabrication via selective laser sintering (SLS), which is a mature RP technique. A three-factor three-level complete factorial design was applied to investigate the effects of the three factors (laser power, scan spacing, and layer thickness) in SLS and to optimize SLS parameters for producing good-quality PHBV polymer scaffolds and Ca-P/PHBV nanocomposite scaffolds. The plots of the main effects of these three factors and the three-dimensional response surface were constructed and discussed. Based on the regression equation, optimized PHBV scaffolds and Ca-P/PHBV scaffolds were fabricated using the optimized values of SLS parameters. Characterization of optimized PHBV scaffolds and Ca-P/PHBV scaffolds verified the optimization process. It has also been demonstrated that SLS has the capability of constructing good-quality, sophisticated porous structures of complex shape, which some tissue engineering applications may require.

  19. Chitosan microspheres with an extracellular matrix-mimicking nanofibrous structure as cell-carrier building blocks for bottom-up cartilage tissue engineering.

    PubMed

    Zhou, Yong; Gao, Huai-Ling; Shen, Li-Li; Pan, Zhao; Mao, Li-Bo; Wu, Tao; He, Jia-Cai; Zou, Duo-Hong; Zhang, Zhi-Yuan; Yu, Shu-Hong

    2016-01-07

    Scaffolds for tissue engineering (TE) which closely mimic the physicochemical properties of the natural extracellular matrix (ECM) have been proven to advantageously favor cell attachment, proliferation, migration and new tissue formation. Recently, as a valuable alternative, a bottom-up TE approach utilizing cell-loaded micrometer-scale modular components as building blocks to reconstruct a new tissue in vitro or in vivo has been proved to demonstrate a number of desirable advantages compared with the traditional bulk scaffold based top-down TE approach. Nevertheless, micro-components with an ECM-mimicking nanofibrous structure are still very scarce and highly desirable. Chitosan (CS), an accessible natural polymer, has demonstrated appealing intrinsic properties and promising application potential for TE, especially the cartilage tissue regeneration. According to this background, we report here the fabrication of chitosan microspheres with an ECM-mimicking nanofibrous structure for the first time based on a physical gelation process. By combining this physical fabrication procedure with microfluidic technology, uniform CS microspheres (CMS) with controlled nanofibrous microstructure and tunable sizes can be facilely obtained. Especially, no potentially toxic or denaturizing chemical crosslinking agent was introduced into the products. Notably, in vitro chondrocyte culture tests revealed that enhanced cell attachment and proliferation were realized, and a macroscopic 3D geometrically shaped cartilage-like composite can be easily constructed with the nanofibrous CMS (NCMS) and chondrocytes, which demonstrate significant application potential of NCMS as the bottom-up cell-carrier components for cartilage tissue engineering.

  20. Patient-Derived Human Induced Pluripotent Stem Cells From Gingival Fibroblasts Composited With Defined Nanohydroxyapatite/Chitosan/Gelatin Porous Scaffolds as Potential Bone Graft Substitutes

    PubMed Central

    Ji, Jun; Tong, Xin; Huang, Xiaofeng; Zhang, Junfeng

    2016-01-01

    pluripotent stem cells (hiPSCs) were established from clinically easily derived human gingival fibroblasts (hGFs) and defined nanohydroxyapatite/chitosan/gelatin (HCG) scaffolds. hiPSCs derived from hGFs had better osteogenesis capability than that of hGFs. More interestingly, osteogenic differentiation of hiPSCs from hGFs was elevated significantly when composited with HCG-311 scaffolds in vitro and in vivo. The present study has uncovered the important role of different nHA ratios in HCG scaffolds in osteogenesis induction of hiPSCs derived from hGFs. This technique could serve as a potential innovative approach for bone tissue engineering, especially large bone regeneration clinically. PMID:26586776

  1. A protein/antibiotic releasing poly(lactic-co-glycolic acid)/lecithin scaffold for bone repair applications.

    PubMed

    Shi, Xuetao; Wang, Yingjun; Ren, Li; Huang, Wei; Wang, Dong-An

    2009-05-21

    Novel poly(lactic-co-glycolic acid) (PLGA)-hybridizing-lecithin scaffolds loaded with drug or protein were prepared with water/oil/water techniques and sintering microspheres technique. In such fabricated composite scaffolds (abbreviated "PLGA/Lec-SMS"), the introduction of lecithin component has been proven capable of largely enhancing Gentamicin (GS) and protein (Bovine Serum Albumin) encapsulation efficiency. The in vitro GS and BSA releasing profiles of PLGA/Lec-SMS system were plotted basing over 60 days' and 18 days' data collection, respectively. It indicates a sustained releasing tendency despite a burst at the very beginning. The antibacterial properties of GS-laden scaffolds were determined in vitro, and the antibacterial activity of scaffolds was enhanced by incorporating lecithin into PLGA bulks. Additionally, mesenchymal stem cells (MSCs) were seeded onto PLGA-SMS and PLGA/Lec-SMS in vitro. The outcome confirmed PLGA/Lec(5%)-SMS functions to improve MSC proliferation and also to enhance general ALP production and calcium secretion which is the vital markers for osteogenesis. In conclusion, this newly designed antibiotic releasing PLGA/Lec-SMS is promising for bone-repairing therapeutics.

  2. Preparation of a new composite combining strengthened β-tricalcium phosphate with platelet-rich plasma as a potential scaffold for the repair of bone defects

    PubMed Central

    WANG, CHENGGONG; ZHONG, DA; ZHOU, XING; YIN, KE; LIAO, QIANDE; KONG, LINGYU; LIU, ANSONG

    2014-01-01

    β-tricalcium phosphate (β-TCP) and platelet-rich plasma (PRP) are commonly used in bone tissue engineering. In the present study, a new composite combining strengthened β-TCP and PRP was prepared and its morphological and mechanical properties were investigated by scanning electron microscopy (SEM) and material testing. The biocompatibility was evaluated by measuring the adhesion rate and cytotoxicity of bone marrow stromal cells (BMSCs). The strengthened β-TCP/PRP composite had an appearance like the fungus Boletus kermesinus with the PRP gel distributed on the surface of the micropores. The maximum load and load intensity were 945.6±86.4 N and 13.1±0.5 MPa, which were significantly higher than those of β-TCP (110.1±14.3 N and 1.6±0.2 MPa; P<0.05). The BMSC adhesion rate on the strengthened β-TCP/PRP composite was >96% after 24 h, with a cell cytotoxicity value of zero. SEM micrographs revealed that following seeding of BMSCs onto the composite in high-glucose Dulbecco’s modified Eagle’s medium culture for two weeks, the cells grew well and exhibited fusiform, spherical and polygonal morphologies, as well as pseudopodial connections. The strengthened β-TCP/PRP composite has the potential to be used as a scaffold in bone tissue engineering due to its effective biocompatibility and mechanical properties. PMID:25187800

  3. Synthesis and catalytic performance of SiO2@Ni and hollow Ni microspheres

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Liu, Yanhua; Shi, Xueting; Yu, Zhengyang; Feng, Libang

    2016-11-01

    Nickel (Ni) catalyst has been widely used in catalytic reducing reactions such as catalytic hydrogenation of organic compounds and catalytic reduction of organic dyes. However, the catalytic efficiency of pure Ni is low. In order to improve the catalytic performance, Ni nanoparticle-loaded microspheres can be developed. In this study, we have prepared Ni nanoparticle-loaded microspheres (SiO2@Ni) and hollow Ni microspheres using two-step method. SiO2@Ni microspheres with raspberry-like morphology and core-shell structure are synthesized successfully using SiO2 microsphere as a template and Ni2+ ions are adsorbed onto SiO2 surfaces via electrostatic interaction and then reduced and deposited on surfaces of SiO2 microspheres. Next, the SiO2 cores are removed by NaOH etching and the hollow Ni microspheres are prepared. The NaOH etching time does no have much influence on the crystal structure, shape, and surface morphology of SiO2@Ni; however, it can change the phase composition evidently. The hollow Ni microspheres are obtained when the NaOH etching time reaches 10 h and above. The as-synthesized SiO2@Ni microspheres exhibit much higher catalytic performance than the hollow Ni microspheres and pure Ni nanoparticles in the catalytic reduction of methylene blue. Meanwhile, the SiO2@Ni catalyst has high stability and hence it can be recycled for reuse.

  4. Hybrid use of combined and sequential delivery of growth factors and ultrasound stimulation in porous multilayer composite scaffolds to promote both vascularization and bone formation in bone tissue engineering.

    PubMed

    Yan, Haoran; Liu, Xia; Zhu, Minghua; Luo, Guilin; Sun, Tao; Peng, Qiang; Zeng, Yi; Chen, Taijun; Wang, Yingying; Liu, Keliang; Feng, Bo; Weng, Jie; Wang, Jianxin

    2016-01-01

    In this study, a multilayer coating technology would be adopted to prepare a porous composite scaffold and the growth factor release and ultrasound techniques were introduced into bone tissue engineering to finally solve the problems of vascularization and bone formation in the scaffold whilst the designed multilayer composite with gradient degradation characteristics in the space was used to match the new bone growth process better. The results of animal experiments showed that the use of low intensity pulsed ultrasound (LIPUS) combined with growth factors demonstrated excellent capabilities and advantages in both vascularization and new bone formation in bone tissue engineering. The degradation of the used scaffold materials could match new bone formation very well. The results also showed that only RGD-promoted cell adhesion was insufficient to satisfy the needs of new bone formation while growth factors and LIPUS stimulation were the key factors in new bone formation.

  5. Fast and reversible lithium-induced electrochemical alloying in tin-based composite oxide hierarchical microspheres assembled by nanoplate building blocks

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Wen, Zhenhai; Li, Jinghong

    To benefit from the large capacity gain advantages offered by lithium-induced electrochemical alloying and to overcome poor kinetics, a novel concept to tackle such issues by using porous hierarchical microspheres with an interconnected network of nanoplate building blocks, has been introduced and demonstrated with Sn 1.0P 1.17O 4.72 glass as an example. Such desired three-dimensional microarchitectures with exciting nanosize effects can be exploited to fabricate next generation of lithium-ion batteries where outstanding rate capability and sustained reversible capacity are achieved.

  6. Co-cultivation of keratinocyte-human mesenchymal stem cell (hMSC) on sericin loaded electrospun nanofibrous composite scaffold (cationic gelatin/hyaluronan/chondroitin sulfate) stimulates epithelial differentiation in hMSCs: In vitro study.

    PubMed

    Bhowmick, Sirsendu; Scharnweber, Dieter; Koul, Veena

    2016-05-01

    Fortifying the scaffold with bioactive molecules and glycosaminoglycans (GAGs), is an efficient way to design new generation tissue engineered biomaterials. In this study, we evaluated the synergistic effect of electrospun nanofibrous composite scaffold (cationic gelatin/hyaluronan/chondroitin sulfate) loaded with sericin and, contact co-culture of human mesenchymal stem cells (hMSCs)-keratinocytes on hMSCs' differentiation towards epithelial lineage. Cationic gelatin is prepared with one step novel synthesis process by grafting quaternary ammonium salts to the backbone of gelatin. Release kinetics studies showed that Fickian diffusion is the major release mechanism for both GAGs and sericin/gelatin. In vitro biocompatibility of the electrospun scaffold was evaluated in terms of LDH and DNA quantification assay on human foreskin fibroblast, human keratinocyte and hMSC. Significant proliferation (∼ 4-6 fold) was detected after culturing all three cell on the electrospun scaffold containing sericin. After 5 days of contact co-culture, results revealed that electrospun scaffold containing sericin promote epithelial differentiation of hMSC in terms of several protein markers (keratin 14, ΔNp63α and Pan-cytokeratin) and gene expression of some dermal proteins (keratin 14, ΔNp63α). Findings of this study will foster the progress of current skin tissue engineering scaffolds by understanding the skin regeneration and wound healing process.

  7. Method for preparing hollow metal oxide microsphere

    DOEpatents

    Schmitt, C.R.

    1974-02-12

    Hollow refractory metal oxide microspheres are prepared by impregnating resinous microspheres with a metallic compound, drying the impregnated microspheres, heating the microspheres slowly to carbonize the resin, and igniting the microspheres to remove the carbon and to produce the metal oxide. Zirconium oxide is given as an example. (Official Gazette)

  8. Raspberry-like PS/CdTe/Silica Microspheres for Fluorescent Superhydrophobic Materials.

    PubMed

    Chang, Jinghui; Zang, Linlin; Wang, Cheng; Sun, Liguo; Chang, Qing

    2016-12-01

    Superhydrophobic particulate films were fabricated via deposition of raspberry-like fluorescent PS/CdTe/silica microspheres on clean glass substrates and surface modification. Particularly, the fluorescent microspheres were prepared by a kind of modified strategy, namely introducing poly (acrylic acid)-functionalized polystyrene microspheres and thiol-stabilized CdTe quantum dots into a hydrolysis reaction of tetraethoxysilane simultaneously. And through adjusting the reaction parameters, the polystyrene spheres with two particle sizes and three colors of CdTe quantum dots aqueous solution were obtained. Consequently, raspberry-like microspheres consist of polystyrene cores and the composite shells of CdTe quantum dots and silica. These microspheres possess a fluorescent characteristic and form a hierarchical dual roughness which was conductive to superhydrophobicity, and the hydrophobic tests also showed the contact angles of water droplets on the surface of the raspberry-like microspheres which were over 160° at room temperature.

  9. Raspberry-like PS/CdTe/Silica Microspheres for Fluorescent Superhydrophobic Materials

    NASA Astrophysics Data System (ADS)

    Chang, Jinghui; Zang, Linlin; Wang, Cheng; Sun, Liguo; Chang, Qing

    2016-02-01

    Superhydrophobic particulate films were fabricated via deposition of raspberry-like fluorescent PS/CdTe/silica microspheres on clean glass substrates and surface modification. Particularly, the fluorescent microspheres were prepared by a kind of modified strategy, namely introducing poly (acrylic acid)-functionalized polystyrene microspheres and thiol-stabilized CdTe quantum dots into a hydrolysis reaction of tetraethoxysilane simultaneously. And through adjusting the reaction parameters, the polystyrene spheres with two particle sizes and three colors of CdTe quantum dots aqueous solution were obtained. Consequently, raspberry-like microspheres consist of polystyrene cores and the composite shells of CdTe quantum dots and silica. These microspheres possess a fluorescent characteristic and form a hierarchical dual roughness which was conductive to superhydrophobicity, and the hydrophobic tests also showed the contact angles of water droplets on the surface of the raspberry-like microspheres which were over 160° at room temperature.

  10. Safety evaluation of a bioglass-polylactic acid composite scaffold seeded with progenitor cells in a rat skull critical-size bone defect.

    PubMed

    Eldesoqi, Karam; Henrich, Dirk; El-Kady, Abeer M; Arbid, Mahmoud S; Abd El-Hady, Bothaina M; Marzi, Ingo; Seebach, Caroline

    2014-01-01

    Treating large bone defects represents a major challenge in traumatic and orthopedic surgery. Bone tissue engineering provides a promising therapeutic option to improve the local bone healing response. In the present study tissue biocompatibility, systemic toxicity and tumorigenicity of a newly developed composite material consisting of polylactic acid (PLA) and 20% or 40% bioglass (BG20 and BG40), respectively, were analyzed. These materials were seeded with mesenchymal stem cells (MSC) and endothelial progenitor cells (EPC) and tested in a rat calvarial critical size defect model for 3 months and compared to a scaffold consisting only of PLA. Serum was analyzed for organ damage markers such as GOT and creatinine. Leukocyte count, temperature and free radical indicators were measured to determine the degree of systemic inflammation. Possible tumor occurrence was assessed macroscopically and histologically in slides of liver, kidney and spleen. Furthermore, the concentrations of serum malondialdehyde (MDA) and sodium oxide dismutase (SOD) were assessed as indicators of tumor progression. Qualitative tissue response towards the implants and new bone mass formation was histologically investigated. BG20 and BG40, with or without progenitor cells, did not cause organ damage, long-term systemic inflammatory reactions or tumor formation. BG20 and BG40 supported bone formation, which was further enhanced in the presence of EPCs and MSCs. This investigation reflects good biocompatibility of the biomaterials BG20 and BG40 and provides evidence that additionally seeding EPCs and MSCs onto the scaffold does not induce tumor formation.

  11. Polyester scaffolds with bimodal pore size distribution for tissue engineering.

    PubMed

    Sosnowski, Stanislaw; Woźniak, Piotr; Lewandowska-Szumieł, Małgorzata

    2006-06-16

    This paper presents a method for the preparation of porous poly(L-lactide)/poly[(L-lactide)-co-glycolide] scaffolds for tissue engineering. Scaffolds were prepared by a mold pressing-salt leaching technique from structured microparticles. The total porosity was in the range 70-85%. The pore size distribution was bimodal. Large pores, susceptible for osteoblasts growth and proliferation had the dimensions 50-400 microm. Small pores, dedicated to the diffusion of nutrients or/and metabolites of bone forming cells, as well as the products of hydrolysis of polyesters from the walls of the scaffold, had sizes in the range 2 nm-5 microm. The scaffolds had good mechanical strength (compressive modulus equal to 41 MPa and a strength of 1.64 MPa for 74% porosity). Scaffolds were tested in vitro with human osteoblast-like cells (MG-63). It was found that the viability of cells seeded within the scaffolds obtained using the mold pressing-salt leaching technique from structured microparticles was better when compared to cells cultured in scaffolds obtained by traditional methods. After 34 d of culture, cells within the tested scaffolds were organized in a tissue-like structure. Photos of section of macro- and mesoporous PLLA/PLGA scaffold containing 50 wt.-% of PLGA microspheres after 34 d of culture. Dark spots mark MG-63 cells, white areas belong to the scaffold. The specimen was stained with haematoxylin/eosin. Bar = 100 microm.

  12. Fabrication of the novel core-shell MCM-41@mTiO2 composite microspheres with large specific surface area for enhanced photocatalytic degradation of dinitro butyl phenol (DNBP)

    NASA Astrophysics Data System (ADS)

    Wei, Xiao-Na; Wang, Hui-Long; Li, Zhen-Duo; Huang, Zhi-Qiang; Qi, Hui-Ping; Jiang, Wen-Feng

    2016-05-01

    The mesoporous MCM-41@mTiO2 core-shell composite microspheres were synthesized successfully by combining sol-gel and simple hydrothermal treatment. The morphology and microstructure characteristics of the synthesized materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption measurements, X-ray powder diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis/DRS) and Fourier transform infrared spectroscopy (FT-IR). The results indicate that the composite material possesses obvious core/shell structure, a pure mesoporous and well-crystallized TiO2 layer (mTiO2), high specific surface area (316.8 m2/g), large pore volume (0.42 cm3/g) and two different pore sizes (2.6 nm and 11.0 nm). The photocatalytic activity of the novel MCM-41@mTiO2 composite was evaluated by degrading 2-sec-butyl-4,6-dinitrophenol (DNBP) in aqueous suspension under UV and visible light irradiation. The results were compared with commercial anatase TiO2 and Degussa P25 and the enhanced degradation were obtained with the synthesized MCM-41@mTiO2 composite under the same conditions, which meant that this material can serve as an efficient photocatalyst for the degradation of hazardous organic pollutants in wastewaters.

  13. Green synthesis of mesoporous ZnFe2O4/C composite microspheres as superior anode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Yao, Lingmin; Hou, Xianhua; Hu, Shejun; Wang, Jie; Li, Min; Su, Chao; Tade, Moses O.; Shao, Zongping; Liu, Xiang

    2014-07-01

    The commercialized LIBs employing graphite as anodes currently suffer a series of problems from the safety, theoretical capacity (372 mAh g-1) and rate capability. Herein, self-assembly mesoporous Zn ferrite (ZnFe2O4) microsphere embedded into carbon network has been synthesized by a facile method in the presence of citric acid. The Zn ferrites as an anode material with novel structure demonstrate superior electrochemical performance, with enhanced specific reversible capacity (∼1100 mAh g-1 at the specific current of 0.05 A g-1 after 100 cycles), excellent rate capability (more than 500 mAh g-1 even at the specific current of 1.1 A g-1) and good cycleability with little fading (∼97.6% after 100 cycles). The excellent cycling performance is associated with the loose Zn ferrite microsphere with numerous mesopores embedded into the carbon network, which can accommodate the severe mechanism strains and provides good electrical contact and conductivity. The superior electrochemical performance may facilitate ZnFe2O4 to be a promising alternative anode in lithium ion battery.

  14. Scaffolded biology.

    PubMed

    Minelli, Alessandro

    2016-09-01

    Descriptions and interpretations of the natural world are dominated by dichotomies such as organism vs. environment, nature vs. nurture, genetic vs. epigenetic, but in the last couple of decades strong dissatisfaction with those partitions has been repeatedly voiced and a number of alternative perspectives have been suggested, from perspectives such as Dawkins' extended phenotype, Turner's extended organism, Oyama's Developmental Systems Theory and Odling-Smee's niche construction theory. Last in time is the description of biological phenomena in terms of hybrids between an organism (scaffolded system) and a living or non-living scaffold, forming unit systems to study processes such as reproduction and development. As scaffold, eventually, we can define any resource used by the biological system, especially in development and reproduction, without incorporating it as happens in the case of resources fueling metabolism. Addressing biological systems as functionally scaffolded systems may help pointing to functional relationships that can impart temporal marking to the developmental process and thus explain its irreversibility; revisiting the boundary between development and metabolism and also regeneration phenomena, by suggesting a conceptual framework within which to investigate phenomena of regular hypermorphic regeneration such as characteristic of deer antlers; fixing a periodization of development in terms of the times at which a scaffolding relationship begins or is terminated; and promoting plant galls to legitimate study objects of developmental biology.

  15. In Vitro Studies on the Degradability, Bioactivity, and Cell Differentiation of PRP/AZ31B Mg Alloys Composite Scaffold

    PubMed Central

    Zou, Jian; Xu, Hongwei; Li, Xiaolin

    2017-01-01

    In recent years, more and more methods have been developed to improve the bioactivity of the biodegradable materials in bone tissue regeneration. In present study, we used rat mesenchymal stem cells (rMSCs) to evaluate the outcomes of Mg alloys (AZ31B, Magnesium, and Aluminum) and Platelet-rich plasma (PRP)/Mg alloys on rMSCs biocompatibility and osteogenic differentiation. Water absorption experiments indicated that both bare AZ31B and PRP/AZ31B were capable of absorbing large amounts of water. But the water absorption ratio for PRP/AZ31B was significantly higher than that for bare AZ31B. The degradability experiments implied that both samples degraded at same speed. rMSCs on the surface of AZ31B distributed more and better than those on the AZ31B scaffold. In ALP activity experiment, the activity of rMSCs on the PRP/AZ31B was markedly higher than that on the AZ31B scaffolds on the 7th day and 14th day. qRT-PCR also showed that OPN and OCN were expressed in both samples. OPN and OCN expression in PRP/AZ31B sample were higher than those in bare AZ31B samples. In summary, the in vitro study implied that AZ31B combined with PRP could remarkably improve cell seeding, attachment, proliferation, and differentiation. PMID:28337451

  16. Microsphere insulation systems

    NASA Technical Reports Server (NTRS)

    Allen, Mark S. (Inventor); Willen, Gary S. (Inventor); Mohling, Robert A. (Inventor)

    2005-01-01

    A new insulation system is provided that contains microspheres. This insulation system can be used to provide insulated panels and clamshells, and to insulate annular spaces around objects used to transfer, store, or transport cryogens and other temperature-sensitive materials. This insulation system provides better performance with reduced maintenance than current insulation systems.

  17. Polyvinyl pyridine microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

    1979-01-01

    Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agen