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Sample records for porous polymeric scaffolds

  1. Three-dimensional porous biodegradable polymeric scaffolds fabricated with biodegradable hydrogel porogens.

    PubMed

    Kim, Jinku; Yaszemski, Michael J; Lu, Lichun

    2009-12-01

    We have developed a new fabrication technique to create three-dimensional (3D) porous poly(epsilon-caprolactone fumarate) (PCLF) scaffolds using hydrogel microparticle porogens, as an alternative to overcome certain limitations of traditional scaffold fabrication techniques such as a salt leaching method. Both natural hydrogel, gelatin, and synthetic hydrogel, poly(ethylene glycol) sebacic acid diacrylate, were used as porogens to fabricate 3D porous PCLF scaffolds. Hydrogel microparticles were prepared by a single emulsion technique with the particle size in the range of 100-500 microm after equilibrium in water. The pore size distribution, porosity, pore interconnectivity, and spatial pore heterogeneity of the 3D PCLF scaffolds were assessed using micro-computed tomography and imaging analysis. Scaffolds fabricated with the hydrogel porogens had higher porosity and pore interconnectivity as well as more homogeneous spatial pore distribution, compared to the scaffolds made from the salt leaching process. Compressive moduli of the scaffolds were also measured and showed that lower porosity yielded greater modulus of the scaffolds. Overall, the new fabrication technology using hydrogel porogens may be beneficial for certain tissue engineering applications. PMID:19216632

  2. Porous scaffold design for tissue engineering

    NASA Astrophysics Data System (ADS)

    Hollister, Scott J.

    2005-07-01

    A paradigm shift is taking place in medicine from using synthetic implants and tissue grafts to a tissue engineering approach that uses degradable porous material scaffolds integrated with biological cells or molecules to regenerate tissues. This new paradigm requires scaffolds that balance temporary mechanical function with mass transport to aid biological delivery and tissue regeneration. Little is known quantitatively about this balance as early scaffolds were not fabricated with precise porous architecture. Recent advances in both computational topology design (CTD) and solid free-form fabrication (SFF) have made it possible to create scaffolds with controlled architecture. This paper reviews the integration of CTD with SFF to build designer tissue-engineering scaffolds. It also details the mechanical properties and tissue regeneration achieved using designer scaffolds. Finally, future directions are suggested for using designer scaffolds with in vivo experimentation to optimize tissue-engineering treatments, and coupling designer scaffolds with cell printing to create designer material/biofactor hybrids.

  3. A tough, precision-porous hydrogel scaffold: ophthalmologic applications.

    PubMed

    Teng, Wenqi; Long, Thomas J; Zhang, Qianru; Yao, Ke; Shen, Tueng T; Ratner, Buddy D

    2014-10-01

    Appropriate mechanical properties and highly interconnected porosity are important properties for tissue engineering scaffolds. However, most existing hydrogel scaffolds suffer from poor mechanical properties limiting their application. Furthermore, it is relatively infrequent that precision control is achieved over pore size and structure of the scaffold because there are relatively few current technologies that allow such control and there is not a general appreciation that such control is important. To address these shortcomings, by combining double network polymerization and sphere-templating fabrication techniques, we developed a tough, intelligent scaffold based on poly(acrylic acid) and poly(N-isopropyl acrylamide) with a controllable, uniform, and interconnected porous structure. A mechanical assessment showed the toughness of the hydrogel and scaffold to be up to ?1.4 10(7) Jm(-3) and ?1.5 10(6) Jm(-3) respectively, as compared with 10(4)-10(5) Jm(-3) for most synthetic hydrogels. The thermosensitivity and pH-sensitivity were explored in a swelling study. In vitro testing demonstrated the scaffold matrices supported NIH-3T3 cell adhesion, proliferation and infiltration. An in vivo rabbit study showed the scaffolds promote strong cellular integration by allowing cells to migrate into the porous structure from the surrounding tissues. These data suggest that the poly(acrylic acid)/poly(N-isopropyl acrylamide)-based scaffold could be an attractive candidate for tissue engineering. PMID:25085856

  4. Producing ORMOSIL scaffolds by femtosecond laser polymerization

    NASA Astrophysics Data System (ADS)

    Matei, A.; Zamfirescu, M.; Radu, C.; Buruiana, E. C.; Buruiana, T.; Mustaciosu, C.; Petcu, I.; Radu, M.; Dinescu, M.

    2012-07-01

    Structures with different geometries and sizes were built via direct femtosecond laser writing, starting from new organic/inorganic hybrid monomers based on hybrid methacrylate containing triethoxysilane, in addition to urethane and urea groups. Multifunctional oligomer of urethane dimethacrylate type was chosen as comonomer in polymerization experiments because dimethacrylates give rise to the formation of a polymer network, having a number of favorable properties including biocompatibility and surface nanostructuring. Free standing polymeric structures were designed and created in order to be tested in fibroblast cells culture. Investigations of the cellular adhesion, proliferation, and viability of L929 mouse fibroblasts on free-standing laser processed scaffolds were performed for different scaffold designs.

  5. Novel Polymeric Scaffolds Using Protein Microbubbles as Porogen and Growth Factor Carriers

    PubMed Central

    Nair, Ashwin; Thevenot, Paul; Dey, Jagannath; Shen, Jinhui; Sun, Man-Wu; Yang, Jian

    2010-01-01

    Polymeric tissue engineering scaffolds prepared by conventional techniques like salt leaching and phase separation are greatly limited by their poor biomolecule-delivery abilities. Conventional methods of incorporation of various growth factors, proteins, and/or peptides on or in scaffold materials via different crosslinking and conjugation techniques are often tedious and may affect scaffold's physical, chemical, and mechanical properties. To overcome such deficiencies, a novel two-step porous scaffold fabrication procedure has been created in which bovine serum albumin microbubbles (henceforth MB) were used as porogen and growth factor carriers. Polymer solution mixed with MB was phase separated and then lyophilized to create porous scaffold. MB scaffold triggered substantially lesser inflammatory responses than salt-leached and conventional phase-separated scaffolds in vivo. Most importantly, the same technique was used to produce insulin-like growth factor-1 (IGF-1)–eluting porous scaffolds, simply by incorporating IGF-1–loaded MB (MB-IGF-1) with polymer solution before phase separation. In vitro such MB-IGF-1 scaffolds were able to promote cell growth to a much greater extent than scaffold soaked in IGF-1, confirming the bioactivity of the released IGF-1. Further, such MB-IGF-1 scaffolds elicited IGF-1–specific collagen production in the surrounding tissue in vivo. This novel growth factor–eluting scaffold fabrication procedure can be used to deliver a range of single or combination of bioactive biomolecules to substantially promote cell growth and function in degradable scaffold. PMID:19327002

  6. Hydrophilized 3D porous scaffold for effective plasmid DNA delivery.

    PubMed

    Oh, Se Heang; Kim, Tae Ho; Jang, Sung Hwan; Im, Gun Il; Lee, Jin Ho

    2011-06-15

    In this study, hydrophilic PLGA/Pluronic F127 scaffolds loaded with a pDNA/PEI-PEG complex were prepared to estimate their potential use as a polymeric matrix for pDNA delivery. The scaffold was fabricated by a novel precipitation/particulate leaching method. The prepared pDNA/PEI-PEG complex-loaded PLGA/Pluronic F127 scaffold exhibited a highly porous (porosity, 93-95%) and open pore structure, as well as hydrophilicity, which can provide the good environment for cell adhesion and growth. The pDNA/PEI-PEG complexes were efficiently loaded into the PLGA/Pluronic F127 scaffold and continuously released from the scaffolds up to ~90% of the initial loading amount over a period of 8 wk, which may lead to continuous gene transfection into human bone marrow mesenchymal stem cells (hBMMSCs). From the in vitro cell culture in the scaffolds for transfection, it was observed that the pDNA/PEI-PEG complex-loaded hydrophilic PLGA/Pluronic F127 scaffold has a higher transfection efficiency of the pDNA/PEI-PEG complexes into hBMMSCs than the hydrophobic PLGA ones. The cell viability associated with the pDNA/PEI-PEG complexes released from the PLGA/Pluronic F127 scaffold was not significantly different from that of the PLGA/Pluronic F127 scaffold without pDNA, indicating its low cytotoxicity, probably due to the sustained release of the pDNA/PEI-PEG complex from the scaffolds. From these results, we could suggest that the pDNA/PEI-PEG complex-loaded hydrophilic PLGA/Pluronic F127 scaffold can be an effective gene delivery system for 3D tissue formation. PMID:21484988

  7. Solid-state cryomilling for porogen mixing and porous scaffold fabrication - biomed 2011.

    PubMed

    Allaf, Rula M; Rivero, Iris V

    2011-01-01

    Several widely used techniques for the fabrication of three dimensional (3D) scaffolds utilize the particulate leaching method to achieve a porous structure. This method involves the selective leaching of a mineral or an organic compound to generate pores. However, scaffolds prepared by this technique tend to exhibit limited interconnectivity. Therefore, to enhance the interconnectivity of the scaffolds fabricated by particulate leaching, a polymeric porogen can be added during processing. Typically porogens are mixed into a polymer solution, powder, or melt. The mixture is subsequently cast, molded, or extruded, and then leaching the porogens results in porous scaffolds. Still, even though scaffold interconnectivity is improved through the addition of polymer porogens, particulate leaching does not yield scaffolds with uniform properties. This research introduces a new solventless approach, cryomilling, to blend porogens and attain interconnected porous scaffolds with uniform morphologies. To validate the efficacy of the suggested approach a comparison of the effect of various solid-state mixing approaches on scaffold morphology and mechanical properties will be made. In this study, salt particles and poly(ethylene oxide) (PEO) were mixed (manually or through cryomilling) with poly(e-caprolactone) (PCL) for the preparation of porous 3D PCL scaffolds, the mixtures were then compression molded, and subsequently, water was used to leach the porogens. Morphological and compressive properties of the resulting scaffolds will be discussed. This simple, novel, economical, organic solvent-free approach for the fabrication of 3D interconnected porous scaffolds holds promise for tissue engineering applications. PMID:21525630

  8. A review: fabrication of porous polyurethane scaffolds.

    PubMed

    Janik, H; Marzec, M

    2015-03-01

    The aim of tissue engineering is the fabrication of three-dimensional scaffolds that can be used for the reconstruction and regeneration of damaged or deformed tissues and organs. A wide variety of techniques have been developed to create either fibrous or porous scaffolds from polymers, metals, composite materials and ceramics. However, the most promising materials are biodegradable polymers due to their comprehensive mechanical properties, ability to control the rate of degradation and similarities to natural tissue structures. Polyurethanes (PUs) are attractive candidates for scaffold fabrication, since they are biocompatible, and have excellent mechanical properties and mechanical flexibility. PU can be applied to various methods of porous scaffold fabrication, among which are solvent casting/particulate leaching, thermally induced phase separation, gas foaming, emulsion freeze-drying and melt moulding. Scaffold properties obtained by these techniques, including pore size, interconnectivity and total porosity, all depend on the thermal processing parameters, and the porogen agent and solvents used. In this review, various polyurethane systems for scaffolds are discussed, as well as methods of fabrication, including the latest developments, and their advantages and disadvantages. PMID:25579961

  9. Nano/macro porous bioactive glass scaffold

    NASA Astrophysics Data System (ADS)

    Wang, Shaojie

    Bioactive glass (BG) and ceramics have been widely studied and developed as implants to replace hard tissues of the musculo-skeletal system, such as bones and teeth. Recently, instead of using bulk materials, which usually do not degrade rapidly enough and may remain in the human body for a long time, the idea of bioscaffold for tissue regeneration has generated much interest. An ideal bioscaffold is a porous material that would not only provide a three-dimensional structure for the regeneration of natural tissue, but also degrade gradually and, eventually be replaced by the natural tissue completely. Among various material choices the nano-macro dual porous BG appears as the most promising candidate for bioscaffold applications. Here macropores facilitate tissue growth while nanopores control degradation and enhance cell response. The surface area, which controls the degradation of scaffold can also be tuned by changing the nanopore size. However, fabrication of such 3D structure with desirable nano and macro pores has remained challenging. In this dissertation, sol-gel process combined with spinodal decomposition or polymer sponge replication method has been developed to fabricate the nano-macro porous BG scaffolds. Macropores up to 100microm are created by freezing polymer induced spinodal structure through sol-gel transition, while larger macropores (>200um) of predetermined size are obtained by the polymer sponge replication technique. The size of nanopores, which are inherent to the sol-gel method of glass fabrication, has been tailored using several approaches: Before gel point, small nanopores are generated using acid catalyst that leads to weakly-branched polymer-like network. On the other hand, larger nanopores are created with the base-catalyzed gel with highly-branched cluster-like structure. After the gel point, the nanostructure can be further modified by manipulating the sintering temperature and/or the ammonia concentration used in the solvent exchange process. Although both techniques lower the surface area of BG scaffolds, the temperature-dependent sintering process closes nanopores through densification, while the concentration-dependent solvent exchange process enlarges nanopores through Ostwald-ripening type coarsening. Therefore, nanopore size and surface area of BG scaffold are independently controlled using these methods. In vitro cell and in vivo animal tissue responses have been investigated to evaluate the performance of the nano-macro porous BG scaffold. The cells are found to migrate and penetrate deep into the 3D nano-macro porous structure, while exhibiting excellent adhesion to the bioscaffold surface. Importantly, the new tissue with both blood vessels and collagen fibers is formed deep inside the implanted scaffolds without obvious inflammatory reaction. Furthermore, our observations show biological benefits of the nanopores in the BG scaffold. In comparison to BG scaffold without nanopores, cells migrate and penetrate into nano-macro dual-porous BG scaffold faster and deeper mainly because of the increase of surface area. To study the effect of nanopore topography, we fabricated BG scaffolds with the same surface area but different nanopore sizes. It is found that the initial cell attachment is significantly enhanced on the BG scaffold with the same surface area but smaller nanopores size, indicating that the nanopore topography strongly influences the performance of BG scaffold. In conclusion, the present results demonstrate most clearly the usefulness of our nano-macro dual-porous BG as a novel and superior 3D bioscaffold for regenerative medicine and hard tissue engineering.

  10. Porous ceramic scaffolds with complex architectures

    SciTech Connect

    Saiz, Eduardo; Munch, Etienne; Franco, Jaime; Deville, Sylvain; Hunger, Phillip; Saiz, Eduardo; Tomsia, Antoni P.

    2008-03-15

    This work compares two novel techniques for the fabrication of ceramic scaffolds for bone tissue engineering with complex porosity: robocasting and freeze casting. Both techniques are based on the preparation of concentrated ceramic suspensions with suitable properties for the process. In robocasting, the computer-guided deposition of the suspensions is used to build porous materials with designed three dimensional (3-D) geometries and microstructures. Freeze casting uses ice crystals as a template to form porous lamellar ceramic materials. Preliminary results on the compressive strengths of the materials are also reported.

  11. Exploiting novel sterilization techniques for porous polyurethane scaffolds.

    PubMed

    Bertoldi, Serena; Far, Silvia; Haugen, Hvard Jostein; Tanzi, Maria Cristina

    2015-05-01

    Porous polyurethane (PU) structures raise increasing interest as scaffolds in tissue engineering applications. Understanding the effects of sterilization on their properties is mandatory to assess their potential use in the clinical practice. The aim of this work is the evaluation of the effects of two innovative sterilization techniques (i.e. plasma, Sterrad() system, and ozone) on the morphological, chemico-physical and mechanical properties of a PU foam synthesized by gas foaming, using water as expanding agent. In addition, possible toxic effects of the sterilization were evaluated by in vitro cytotoxicity tests. Plasma sterilization did not affect the morphological and mechanical properties of the PU foam, but caused at some extent degradative phenomena, as detected by infrared spectroscopy. Ozone sterilization had a major effect on foam morphology, causing the formation of new small pores, and stronger degradation and oxidation on the structure of the material. These modifications affected the mechanical properties of the sterilized PU foam too. Even though, no cytotoxic effects were observed after both plasma and ozone sterilization, as confirmed by the good values of cell viability assessed by Alamar Blue assay. The results here obtained can help in understanding the effects of sterilization procedures on porous polymeric scaffolds, and how the scaffold morphology, in particular porosity, can influence the effects of sterilization, and viceversa. PMID:25893387

  12. Mechanical Improvements to Reinforced Porous Silk Scaffolds

    PubMed Central

    Gil, Eun Seok; Kluge, Jonathan A.; Rockwood, Danielle N.; Rajkhowa, Rangam; Wang, Lijing; Wang, Xungai; Kaplan, David L

    2012-01-01

    Load bearing porous biodegradable scaffolds are required to engineer functional tissues such as bone. Mechanical improvements to porogen leached scaffolds prepared from silk proteins were systematically studied through the addition of silk particles in combination with silk solution concentration, exploiting interfacial compatibility between the two components. Solvent solutions of silk up to 32 w/v% were successfully prepared in hexafluoroisopropanaol (HFIP) for the study. The mechanical properties of the reinforced silk scaffolds correlated to the material density and matched by a power law relationship, independent of the ratio of silk particles to matrix. These results were similar to the relationships previously shown for cancellous bone. The mechanism behind the increased mechanical properties was a densification effect, and not the effect of including stiffer silk particles into the softer silk continuous matrix. A continuous interface between the silk matrix and the silk particles, as well as homogeneous distribution of the silk particles within the matrix were observed. Furthermore, we note that the roughness of the pore walls was controllable by varying the ratio of particles matrix, providing a route to control topography. The rate of proteolytic hydrolysis of the scaffolds decreased with increase in mass of silk used in the matrix and with increasing silk particle content. PMID:21793193

  13. Rapid Engineering of Three-Dimensional, Multicellular Tissues With Polymeric Scaffolds

    NASA Technical Reports Server (NTRS)

    Gonda, Steve R.; Jordan, Jacqueline; Fraga, Denise N.

    2007-01-01

    A process has been developed for the rapid tissue engineering of multicellular-tissue-equivalent assemblies by the controlled enzymatic degradation of polymeric beads in a low-fluid-shear bioreactor. In this process, the porous polymeric beads serve as temporary scaffolds to support the assemblies of cells in a tissuelike 3D configuration during the critical initial growth phases of attachment of anchorage-dependent cells, aggregation of the cells, and formation of a 3D extracellular matrix. Once the cells are assembled into a 3D array and enmeshed in a structural supportive 3D extracellular matrix (ECM), the polymeric scaffolds can be degraded in the low-fluid-shear environment of the NASA-designed bioreactor. The natural 3D tissuelike assembly, devoid of any artificial support structure, is maintained in the low-shear bioreactor environment by the newly formed natural cellular/ECM. The elimination of the artificial scaffold allows normal tissue structure and function.

  14. Hierarchical porous polymer scaffolds from block copolymers.

    PubMed

    Sai, Hiroaki; Tan, Kwan Wee; Hur, Kahyun; Asenath-Smith, Emily; Hovden, Robert; Jiang, Yi; Riccio, Mark; Muller, David A; Elser, Veit; Estroff, Lara A; Gruner, Sol M; Wiesner, Ulrich

    2013-08-01

    Hierarchical porous polymer materials are of increasing importance because of their potential application in catalysis, separation technology, or bioengineering. Examples for their synthesis exist, but there is a need for a facile yet versatile conceptual approach to such hierarchical scaffolds and quantitative characterization of their nonperiodic pore systems. Here, we introduce a synthesis method combining well-established concepts of macroscale spinodal decomposition and nanoscale block copolymer self-assembly with porosity formation on both length scales via rinsing with protic solvents. We used scanning electron microscopy, small-angle x-ray scattering, transmission electron tomography, and nanoscale x-ray computed tomography for quantitative pore-structure characterization. The method was demonstrated for AB- and ABC-type block copolymers, and resulting materials were used as scaffolds for calcite crystal growth. PMID:23908232

  15. Evaluation of phytochemical-incorporated porous polymeric sponges for bone tissue engineering: a novel perspective.

    PubMed

    Raghavan, Ravi N; Somanathan, N; Sastry, Thottapalli P

    2013-08-01

    Porous polymeric scaffolds are extensively studied for delivery of bone growth factors. Since phytochemicals are known to produce changes in cell signalling and other metabolic pathways, osteogenic phytochemicals, that is, extracts of Cissus quadrangularis and Butea monosperma, are incorporated into sulphonated poly(aryl ether ketone) sponges. The results have shown that the scaffolds with phytochemicals enhanced the proliferation and alkaline phosphatase activity of the cells compared to cells treated on scaffolds without phytochemicals. Hence, these phytochemicals can be evaluated to augment, if not substitute the use of bone morphogenetic proteins in scaffolds. PMID:23736994

  16. Thermoforming techniques for manufacturing porous scaffolds for application in 3D cell cultivation.

    PubMed

    Borowiec, Justyna; Hampl, Jrg; Gebinoga, Michael; Elsarnagawy, Tarek; Elnakady, Yasser A; Fouad, Hassan; Almajhadi, Fahd; Fernekorn, Uta; Weise, Frank; Singh, Sukhdeep; Elsarnagawy, Dief; Schober, Andreas

    2015-04-01

    Within the scientific community, there is an increasing demand to apply advanced cell cultivation substrates with increased physiological functionalities for studying spatially defined cellular interactions. Porous polymeric scaffolds are utilized for mimicking an organ-like structure or engineering complex tissues and have become a key element for three-dimensional (3D) cell cultivation in the meantime. As a consequence, efficient 3D scaffold fabrication methods play an important role in modern biotechnology. Here, we present a novel thermoforming procedure for manufacturing porous 3D scaffolds from permeable materials. We address the issue of precise thermoforming of porous polymer foils by using multilayer polymer thermoforming technology. This technology offers a new method for structuring porous polymer foils that are otherwise available for non-porous polymers only. We successfully manufactured 3D scaffolds from solvent casted and phase separated polylactic acid (PLA) foils and investigated their biocompatibility and basic cellular performance. The HepG2 cell culture in PLA scaffold has shown enhanced albumin secretion rate in comparison to a previously reported polycarbonate based scaffold with similar geometry. PMID:25686978

  17. Beneficial effect of hydrophilized porous polymer scaffolds in tissue-engineered cartilage formation.

    PubMed

    Ju, Young Min; Park, Kwideok; Son, Jun Sik; Kim, Jae-Jin; Rhie, Jong-Won; Han, Dong Keun

    2008-04-01

    Three dimensional (3D) porous poly(L-lactic acid) (PLLA) scaffolds were fabricated using a modified gas foaming method whose effervescent porogens were a mixture of sodium bicarbonate and citric acid. To improve chondrocyte adhesion, the scaffolds were then hydrophilized through oxygen plasma treatment and in situ graft polymerization of acrylic acid (AA). When the physical properties of AA-grafted scaffolds were examined, the porosity and pore size were 87 approximately 93% and 100 approximately 300 microm, respectively. The pore sizes were highly dependent on the varying ratios (w/w) between porogen and polymer solution. Influenced by their pore sizes, the compressive moduli of scaffolds significantly decreased with increasing pore size. The altered surface characteristics were clearly reflected in the reduced water contact angles that meant a significant hydrophilization with the modified polymer surface. Electron spectroscopy for chemical analysis (ESCA) and time-of-flight secondary ion mass spectrometer (ToF-SIMS) also confirmed the altered surface chemistry. When chondrocytes were seeded onto the AA-grafted PLLA scaffolds, cell adhesion and proliferation were substantially improved as compared to the unmodified scaffolds. The benefit of the modified scaffolds was clear in the gene expressions of collagen type II that was significantly upregulated after 4-week culture. Safranin-O staining also identified greater glycosaminoglycan (GAG) deposition in the modified scaffold. The AA-grafted porous polymer scaffolds were effective for cell adhesion and differentiation, making them a suitable platform for tissue-engineered cartilage. PMID:17973245

  18. Repair of mandibular defects using MSCs-seeded biodegradable polyester porous scaffolds.

    PubMed

    Ren, Jie; Ren, Tianbin; Zhao, Peng; Huang, Yanxia; Pan, Kefeng

    2007-01-01

    PLLA, PLA-PEG and PLGA porous scaffolds with pore size ranging from 100 to 250 microm and porosity over 85% were fabricated by a solution-casting/salt-leaching method. The porous structure and porosity of the scaffold were mainly dependent on volume fraction and size of the porogens of NaCl particles. The effects of the polymeric materials on the cell culture behavior and bone formation in vitro in their scaffolds were studied. In vitro cell culture in the scaffolds of the three polymers demonstrated that mesenchymal stem cells (MSCs) had a good adhesion and spread. The composite matrixes cultured for several days possessed preliminary functions of tissue-engineering bone, with signs of the calcium knur formation and the expression of osteocalcin and collagen I in mRNA, especially that of PLA-PEG and PLGA. These cell-loaded porous scaffolds showed effective repair of mandibular defect of rabbits in vivo. Contrastive experiments demonstrated that the MSCs/PLGA scaffold owned better ability facilitating for the MSCs proliferation, differentiation and defect repair. These composite scaffolds can be a potential effective tool for treating mandibular and other bone defects. PMID:17550655

  19. Flow-Induced Stress Distribution in Porous Scaffolds

    NASA Astrophysics Data System (ADS)

    Papavassiliou, Dimitrios; Voronov, Roman; Vangordon, Samuel; Sikavitsas, Vassilios

    2010-11-01

    Flow-induced stresses help the differentiation and proliferation of mesenchymal cells cultured in porous scaffolds within perfusion bioreactors. The distribution of stresses in a scaffold is thus important for understanding the tissue growth process in such reactors. Computational results for flow through Poly-L-Lactic Acid porous scaffolds that have been produced with salt-leaching techniques, and for scaffolds that have been constructed with nonwoven fibers, indicate that the probability density function (pdf) of the wall stress, when normalized with the mean and the standard deviation of the pdf, appears to follow a single type of pdf. The scaffolds were imaged with micro-CT and the simulations were run with lattice Boltzmann methods. The parameters of the distribution can be obtained using Darcy's law and the Blake-Kozeny-Carman equation. Experimental results available in the literature appear to corroborate the computational findings, leading to the conclusion that stresses in high-porosity porous materials follow a single distribution.

  20. Porous Biodegradable Metals for Hard Tissue Scaffolds: A Review

    PubMed Central

    Yusop, A. H.; Bakir, A. A.; Shaharom, N. A.; Abdul Kadir, M. R.; Hermawan, H.

    2012-01-01

    Scaffolds have been utilized in tissue regeneration to facilitate the formation and maturation of new tissues or organs where a balance between temporary mechanical support and mass transport (degradation and cell growth) is ideally achieved. Polymers have been widely chosen as tissue scaffolding material having a good combination of biodegradability, biocompatibility, and porous structure. Metals that can degrade in physiological environment, namely, biodegradable metals, are proposed as potential materials for hard tissue scaffolding where biodegradable polymers are often considered as having poor mechanical properties. Biodegradable metal scaffolds have showed interesting mechanical property that was close to that of human bone with tailored degradation behaviour. The current promising fabrication technique for making scaffolds, such as computation-aided solid free-form method, can be easily applied to metals. With further optimization in topologically ordered porosity design exploiting material property and fabrication technique, porous biodegradable metals could be the potential materials for making hard tissue scaffolds. PMID:22919393

  1. Development of polycaprolactone porous scaffolds by combining solvent casting, particulate leaching, and polymer leaching techniques for bone tissue engineering.

    PubMed

    Thadavirul, Napaphat; Pavasant, Prasit; Supaphol, Pitt

    2014-10-01

    Sodium chloride and polyethylene glycol (PEG) were used as water-soluble porogens for the formation of porous polycaprolactone (PCL) scaffolds. The main purpose was to prepare and evaluate in vitro efficacy of highly interconnected, three-dimensional, porous polymeric scaffolds, as obtained from the combined particulate and polymer leaching techniques. Microscopic analysis confirmed the high interconnectivity of the pores and relatively uniform pore size of 378-435 μm. The PCL scaffolds were further characterized for their density and pore characteristics, water absorption and flow behaviors, and mechanical properties and the potential for their use as bone scaffolding materials was evaluated in vitro using mouse calvaria-derived preosteoblastic cells (MC3T3-E1). Evidently, the use of PEG as the secondary porogen not only improved the interconnectivity of the pore structures but also resulted in the PCL scaffolds that exhibited much better support for the proliferation and differentiation of the cultured bone cells. PMID:24132871

  2. Novel Biodegradable Porous Scaffold Applied to Skin Regeneration

    PubMed Central

    Wang, Hui-Min; Chou, Yi-Ting; Wen, Zhi-Hong; Wang, Zhao-Ren; Chen, Chun-Hong; Ho, Mei-Ling

    2013-01-01

    Skin wound healing is an important lifesaving issue for massive lesions. A novel porous scaffold with collagen, hyaluronic acid and gelatin was developed for skin wound repair. The swelling ratio of this developed scaffold was assayed by water absorption capacity and showed a value of over 20 g water/g dried scaffold. The scaffold was then degraded in time- and dose-dependent manners by three enzymes: lysozyme, hyaluronidase and collagenase I. The average pore diameter of the scaffold was 132.58.4 m measured from SEM images. With human skin cells growing for 7 days, the SEM images showed surface fractures on the scaffold due to enzymatic digestion, indicating the biodegradable properties of this scaffold. To simulate skin distribution, the human epidermal keratinocytes, melanocytes and dermal fibroblasts were seeded on the porous scaffold and the cross-section immunofluorescent staining demonstrated normal human skin layer distributions. The collagen amount was also quantified after skin cells seeding and presented an amount 50% higher than those seeded on culture wells. The in vivo histological results showed that the scaffold ameliorated wound healing, including decreasing neutrophil infiltrates and thickening newly generated skin compared to the group without treatments. PMID:23762223

  3. Porous three-dimensional carbon nanotube scaffolds for tissue engineering.

    PubMed

    Lalwani, Gaurav; Gopalan, Anu; D'Agati, Michael; Sankaran, Jeyantt Srinivas; Judex, Stefan; Qin, Yi-Xian; Sitharaman, Balaji

    2015-10-01

    Assembly of carbon nanomaterials into three-dimensional (3D) architectures is necessary to harness their unique physiochemical properties for tissue engineering and regenerative medicine applications. Herein, we report the fabrication and comprehensive cytocompatibility assessment of 3D chemically crosslinked macrosized (5-8 mm height and 4-6 mm diameter) porous carbon nanotube (CNT) scaffolds. Scaffolds prepared via radical initiated thermal crosslinking of single- or multiwalled CNTs (SWCNTs and MWCNTs) possess high porosity (>80%), and nano-, micro-, and macroscale interconnected pores. MC3T3 preosteoblast cells on MWCNT and SWCNT scaffolds showed good cell viability comparable to poly(lactic-co-glycolic) acid (PLGA) scaffolds after 5 days. Confocal live cell and immunofluorescence imaging showed that MC3T3 cells were metabolically active and could attach, proliferate, and infiltrate MWCNT and SWCNT scaffolds. SEM imaging corroborated cell attachment and spreading and suggested that cell morphology is governed by scaffold surface roughness. MC3T3 cells were elongated on scaffolds with high surface roughness (MWCNTs) and rounded on scaffolds with low surface roughness (SWCNTs). The surface roughness of scaffolds may be exploited to control cellular morphology and, in turn, govern cell fate. These results indicate that crosslinked MWCNTs and SWCNTs scaffolds are cytocompatible, and open avenues toward development of multifunctional all-carbon scaffolds for tissue engineering applications. PMID:25788440

  4. Image-based metrology of porous tissue engineering scaffolds

    NASA Astrophysics Data System (ADS)

    Rajagopalan, Srinivasan; Robb, Richard A.

    2006-03-01

    Tissue engineering is an interdisciplinary effort aimed at the repair and regeneration of biological tissues through the application and control of cells, porous scaffolds and growth factors. The regeneration of specific tissues guided by tissue analogous substrates is dependent on diverse scaffold architectural indices that can be derived quantitatively from the microCT and microMR images of the scaffolds. However, the randomness of pore-solid distributions in conventional stochastic scaffolds presents unique computational challenges. As a result, image-based characterization of scaffolds has been predominantly qualitative. In this paper, we discuss quantitative image-based techniques that can be used to compute the metrological indices of porous tissue engineering scaffolds. While bulk averaged quantities such as porosity and surface are derived directly from the optimal pore-solid delineations, the spatially distributed geometric indices are derived from the medial axis representations of the pore network. The computational framework proposed (to the best of our knowledge for the first time in tissue engineering) in this paper might have profound implications towards unraveling the symbiotic structure-function relationship of porous tissue engineering scaffolds.

  5. Silk fibroin porous scaffolds for nucleus pulposus tissue engineering.

    PubMed

    Zeng, Chao; Yang, Qiang; Zhu, Meifeng; Du, Lilong; Zhang, Jiamin; Ma, Xinlong; Xu, Baoshan; Wang, Lianyong

    2014-04-01

    Intervertebral discs (IVDs) are structurally complex tissue that hold the vertebrae together and provide mobility to spine. The nucleus pulposus (NP) degeneration often results in degenerative IVD disease that is one of the most common causes of back and neck pain. Tissue engineered nucleus pulposus offers an alternative approach to regain the function of the degenerative IVD. The aim of this study is to determine the feasibility of porous silk fibroin (SF) scaffolds fabricated by paraffin-sphere-leaching methods with freeze-drying in the application of nucleus pulposus regeneration. The prepared scaffold possessed high porosity of 92.385.12% and pore size of 165.008.25?m as well as high pore interconnectivity and appropriate mechanical properties. Rabbit NP cells were seeded and cultured on the SF scaffolds. Scanning electron microscopy, histology, biochemical assays and mechanical tests revealed that the porous scaffolds could provide an appropriate microstructure and environment to support adhesion, proliferation and infiltration of NP cells in vitro as well as the generation of extracellular matrix. The NP cell-scaffold construction could be preliminarily formed after subcutaneously implanted in a nude mice model. In conclusion, The SF porous scaffold offers a potential candidate for tissue engineered NP tissue. PMID:24582244

  6. Solvent/Non-Solvent Sintering: A Novel Route to Create Porous Microsphere Scaffolds For Tissue Regeneration

    PubMed Central

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

    2009-01-01

    Solvent/non-solvent sintering creates porous polymeric microsphere scaffolds suitable for tissue engineering purposes with control over the resulting porosity, average pore diameter and mechanical properties. Five different biodegradable biocompatible polyphosphazenes exhibiting glass transition temperatures from ?8C to 41oC and poly(lactide-co-glycolide), (PLAGA) a degradable polymer used in a number of biomedical settings, were examined to study the versatility of the process and benchmark the process to heat sintering. Parameters such as: solvent/non-solvent sintering solution composition and submersion time effect the sintering process. PLAGA microsphere scaffolds fabricated with solvent/non-solvent sintering exhibited an interconnected porosity and pore size of 31.9% and 179.1m respectively which was analogous to that of conventional heat sintered PLAGA microsphere scaffolds. Biodegradable polyphosphazene microsphere scaffolds exhibited a maximum interconnected porosity of 37.6% and a maximum compressive modulus of 94.3MPa. Solvent/non-solvent sintering is an effective strategy for sintering polymeric microspheres, with a broad spectrum of glass transition temperatures, under ambient conditions making it an excellent fabrication route for developing tissue engineering scaffolds and drug delivery vehicles. PMID:18161819

  7. Design of a bioresorbable polymeric scaffold for osteoblast culture

    NASA Astrophysics Data System (ADS)

    Ditaranto, Vincent M., Jr.

    Bioresorbable polymeric scaffolds were designed for the purpose of growing rat osteosarcoma cells (ROS 17/2.8) using the compression molding method. The material used in the construction of the scaffolds was a mixture of polycaprolactone (PCL), Hydroxyapatite (HA), Glycerin (GL) and salt (NaCl) for porosity. The concentration of the several materials utilized, was determined by volume. Past research at the University of Massachusetts Lowell (UML) has successfully utilized the compression molding method for the construction of scaffolds, but was unable to accomplish the goal of long term cell survival and complete cellular proliferation throughout a three dimensional scaffold. This research investigated various concentrations of the materials and molding temperatures used for the manufacture of scaffolds in order to improve the scaffold design and address those issues. The design of the scaffold using the compression molding process is detailed in the Method and Materials section of this thesis. The porogen (salt) used for porosity was suspected as a possible source of contamination causing cell apoptosis in past studies. This research addressed the issues for cell survival and proliferation throughout a three dimensional scaffold. The leaching of the salt was one major design modification. This research successfully used ultrasonic leaching in addition to the passive method. Prior to cell culture, the scaffolds were irradiated to 2.75 Mrad, with cobalt-60 gamma radionuclide. The tissue culture consisted of two trials: (1) cell culture in scaffolds cleaned with passive leaching; (2) cell culture with scaffolds cleaned with ultrasonic leaching. Cell survival and proliferation was accomplished only with the addition of ultrasonic leaching of the scaffolds. Analysis of the scaffolds included Scanning Electron Microscopy (SEM), Nikon light microscopy and x-ray mapping of the calcium, sodium and chloride ion distribution. The cells were analyzed by Environmental Scanning Electron Microscopy (ESEM) and Nikon light microscopy. The high magnification of ESEM up to 60,000 x revealed an unexpected discovery. The osteoblasts appeared to be remodeling the PCL scaffold shown in the last two figures of this research.

  8. Silk porous scaffolds with nanofibrous microstructures and tunable properties.

    PubMed

    Lu, Guozhong; Liu, Shanshan; Lin, Shasha; Kaplan, David L; Lu, Qiang

    2014-08-01

    Scaffold biomaterials derived from silk fibroin have been widely used in tissue engineering. However, mimicking the nanofibrous structures of the extracellular matrix (ECM) for achieving better biocompatibility remains a challenge. Here, we design a mild self-assembly approach to prepare nanofibrous scaffolds from silk fibroin solution. Silk nanofibers were self-assembled by slowly concentrating process in aqueous solution without any cross-linker or toxic solvent and then were further fabricated into porous scaffolds with pore size of about 200-250?m through lyophilization, mimicking nano and micro structures of ECM. Gradient water/methanol annealing treatments were used to control the secondary structures, mechanical properties, and degradation behaviors of the scaffolds, which would be critical for different tissue regeneration applications. With salt-leached silk scaffold as control, the ECM-mimetic scaffolds with different secondary structures were used to culture the amniotic fluid-derived stem cells in vitro to confirm their biocompatibility. All the ECM-mimetic scaffolds with different secondary structures represented better cell growth and proliferation compared to the salt-leached scaffold, confirming the critical influence of ECM-mimetic structure on biocompatibility. Although further studies such as cell differentiation behaviours are still necessary for clarifying the influence of microstructures and secondary conformational compositions, our study provides promising scaffold candidate that is suitable for different tissue regenerations. PMID:24892562

  9. Synthesis of polymer/inorganic nanocomposite films using highly porous inorganic scaffolds

    NASA Astrophysics Data System (ADS)

    Zhang, Huanjun; Popp, Matthias; Hartwig, Andreas; Mdler, Lutz

    2012-03-01

    Polymeric/inorganic nanocomposite films have been fabricated through a combination of flame-spray-pyrolysis (FSP) made inorganic scaffold and surface initiated polymerization of cyanoacrylate. The highly porous structure of pristine SnO2 films allows the uptake of cyanoacrylate and the polymerization is surface initiated by the water adsorbed onto the SnO2 surface. Scanning electron microscopy study reveals a nonlinear increase in the composite particle size and the film thickness with polymerization time. The structural change is rather homogeneous throughout the whole layer. The composite is formed mainly by an increase of the particle size and not by just filling the existing pores. High-resolution transmission electron microscopy imaging shows SnO2 nanoparticles embedded in the polymeric matrix, constituting the nanocomposite material. Thermogravimetric analysis indicates that the porosity of the nanocomposite films decreases from 98% to 75%, resulting in a significant enhancement of the hardness of the films. DC conductivity measurements conducted in situ on the nanocomposite layer suggest a gradual increase in the layer resistance, pointing to a loss of connectivity between the SnO2 primary particles as the polymerization proceeds.Polymeric/inorganic nanocomposite films have been fabricated through a combination of flame-spray-pyrolysis (FSP) made inorganic scaffold and surface initiated polymerization of cyanoacrylate. The highly porous structure of pristine SnO2 films allows the uptake of cyanoacrylate and the polymerization is surface initiated by the water adsorbed onto the SnO2 surface. Scanning electron microscopy study reveals a nonlinear increase in the composite particle size and the film thickness with polymerization time. The structural change is rather homogeneous throughout the whole layer. The composite is formed mainly by an increase of the particle size and not by just filling the existing pores. High-resolution transmission electron microscopy imaging shows SnO2 nanoparticles embedded in the polymeric matrix, constituting the nanocomposite material. Thermogravimetric analysis indicates that the porosity of the nanocomposite films decreases from 98% to 75%, resulting in a significant enhancement of the hardness of the films. DC conductivity measurements conducted in situ on the nanocomposite layer suggest a gradual increase in the layer resistance, pointing to a loss of connectivity between the SnO2 primary particles as the polymerization proceeds. Electronic supplementary information (ESI) available: SEM images and powder XRD patterns. See DOI: 10.1039/c2nr12029a

  10. Living Bacterial Sacrificial Porogens to Engineer Decellularized Porous Scaffolds

    PubMed Central

    Xu, Feng; Sridharan, BanuPriya; Durmus, Naside Gozde; Wang, ShuQi; Yavuz, Ahmet Sinan; Gurkan, Umut Atakan; Demirci, Utkan

    2011-01-01

    Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative medicine and drug discovery as viable tissue mimics. However, the existing hydrogel fabrication techniques suffer from limited control over pore interconnectivity, density and size, which leads to inefficient nutrient and oxygen transport to cells embedded in the scaffolds. Here, we demonstrated an innovative approach to develop a new platform for tissue engineered constructs using live bacteria as sacrificial porogens. E.coli were patterned and cultured in an interconnected three-dimensional (3D) hydrogel network. The growing bacteria created interconnected micropores and microchannels. Then, the scafold was decellularized, and bacteria were eliminated from the scaffold through lysing and washing steps. This 3D porous network method combined with bioprinting has the potential to be broadly applicable and compatible with tissue specific applications allowing seeding of stem cells and other cell types. PMID:21552485

  11. Living bacterial sacrificial porogens to engineer decellularized porous scaffolds.

    PubMed

    Xu, Feng; Sridharan, BanuPriya; Durmus, Naside Gozde; Wang, ShuQi; Yavuz, Ahmet Sinan; Gurkan, Umut Atakan; Demirci, Utkan

    2011-01-01

    Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative medicine and drug discovery as viable tissue mimics. However, the existing hydrogel fabrication techniques suffer from limited control over pore interconnectivity, density and size, which leads to inefficient nutrient and oxygen transport to cells embedded in the scaffolds. Here, we demonstrated an innovative approach to develop a new platform for tissue engineered constructs using live bacteria as sacrificial porogens. E.coli were patterned and cultured in an interconnected three-dimensional (3D) hydrogel network. The growing bacteria created interconnected micropores and microchannels. Then, the scafold was decellularized, and bacteria were eliminated from the scaffold through lysing and washing steps. This 3D porous network method combined with bioprinting has the potential to be broadly applicable and compatible with tissue specific applications allowing seeding of stem cells and other cell types. PMID:21552485

  12. Tissue engineering scaffold material of porous nanohydroxyapatite/polyamide 66

    PubMed Central

    Xu, Qian; Lu, Hongyan; Zhang, Jingchao; Lu, Guoyu; Deng, Zhennan; Mo, Anchun

    2010-01-01

    The aim of the study was to investigate a porous nanohydroxyapatite/polyamide 66 (n-HA/PA66) scaffold material that was implanted into muscle and tibiae of 16 New Zealand white rabbits to evaluate the biocompatibility and osteogenesis and osteoinductivity of the materials in vivo. The samples were harvested at 2, 4, 12 and 26 weeks respectively, and subjected to histological analysis. At 2 weeks, the experiment showed that osteogenesis was detected in porous n-HA/PA66 composite and the density of new bone formation was similar to the surrounding host bone at 12 weeks. The study indicated that three-dimensional pore structures could facilitate cell adhesion, differentiation and proliferation, and help with fibrovascular and nerve colonization. In conclusion, porous n-HA/PA66 scaffold material could be a good candidate as a bone substitute material used in clinics due to its excellent histocompatibility, osteoconductivity and osteoinductivity. PMID:20517477

  13. Laser 3D printing with sub-microscale resolution of porous elastomeric scaffolds for supporting human bone stem cells.

    PubMed

    Petrochenko, Peter E; Torgersen, Jan; Gruber, Peter; Hicks, Lucas A; Zheng, Jiwen; Kumar, Girish; Narayan, Roger J; Goering, Peter L; Liska, Robert; Stampfl, Jrgen; Ovsianikov, Aleksandr

    2015-04-01

    A reproducible method is needed to fabricate 3D scaffold constructs that results in periodic and uniform structures with precise control at sub-micrometer and micrometer length scales. In this study, fabrication of scaffolds by two-photon polymerization (2PP) of a biodegradable urethane and acrylate-based photoelastomer is demonstrated. This material supports 2PP processing with sub-micrometer spatial resolution. The high photoreactivity of the biophotoelastomer permits 2PP processing at a scanning speed of 1000 mm s(-1), facilitating rapid fabrication of relatively large structures (>5 mm(3)). These structures are custom printed for in vitro assay screening in 96-well plates and are sufficiently flexible to enable facile handling and transplantation. These results indicate that stable scaffolds with porosities of greater than 60% can be produced using 2PP. Human bone marrow stromal cells grown on 3D scaffolds exhibit increased growth and proliferation compared to smooth 2D scaffold controls. 3D scaffolds adsorb larger amounts of protein than smooth 2D scaffolds due to their larger surface area; the scaffolds also allow cells to attach in multiple planes and to completely infiltrate the porous scaffolds. The flexible photoelastomer material is biocompatible in vitro and is associated with facile handling, making it a viable candidate for further study of complex 3D-printed scaffolds. PMID:25522214

  14. Slowly degradable porous silk microfabricated scaffolds for vascularized tissue formation.

    PubMed

    Wray, Lindsay S; Tsioris, Konstantinos; Gi, Eun Seok; Omenetto, Fiorenzo G; Kaplan, David L

    2013-07-19

    There is critical clinical demand for tissue-engineered (TE), three-dimensional (3D) constructs for tissue repair and organ replacements. Current efforts toward this goal are prone to necrosis at the core of larger constructs because of limited oxygen and nutrient diffusion. Therefore, critically sized 3D TE constructs demand an immediate vascular system for sustained tissue function upon implantation. To address this challenge the goal of this project was to develop a strategy to incorporate microchannels into a porous silk TE scaffold that could be fabricated reproducibly using microfabrication and soft lithography. Silk is a suitable biopolymer material for this application because it is mechanically robust, biocompatible, slowly degrades in vivo, and has been used in a variety of TE constructs. We report the fabrication of a silk-based TE scaffold that contains an embedded network of porous microchannels. Enclosed porous microchannels support endothelial lumen formation, a critical step toward development of the vascular niche, while the porous scaffold surrounding the microchannels supports tissue formation, demonstrated using human mesenchymal stem cells. This approach for fabricating vascularized TE constructs is advantageous compared to previous systems, which lack porosity and biodegradability or degrade too rapidly to sustain tissue structure and function. The broader impact of this research will enable the systemic study and development of complex, critically-sized engineered tissues, from regenerative medicine to in vitro tissue models of disease states. PMID:24058328

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

    PubMed Central

    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.

    2014-01-01

    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 ± 24 μm for use as injectable cell carriers. Treatment with ethanolic sodium hydroxide for 2 min 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 24 h at 37 °C was 0.9 ± 0.1 MPa, and the average Young’s modulus was 9.4 ± 1.2 MPa. Scaffold porosity levels were 81.6% on average, with a mean pore diameter of 54 ± 38 μm. 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. PMID:25152354

  16. Neuronal cell growth on polymeric scaffolds studied by CARS microscopy

    NASA Astrophysics Data System (ADS)

    Enejder, Annika; Fink, Helen; Kuhn, Hans-Georg

    2012-03-01

    For studies of neuronal cell integration and neurite outgrowth in polymeric scaffold materials as a future alternative for the treatment of damages in the neuronal system, we have developed a protocol employing CARS microscopy for imaging of neuronal networks. The benefits of CARS microscopy come here to their best use; (i) the overall three-dimensional (3D) arrangement of multiple cells and their neurites can be visualized without the need for chemical preparations or physical sectioning, potentially affecting the architecture of the soft, fragile scaffolds and (ii) details on the interaction between single cells and scaffold fibrils can be investigated by close-up images at sub-micron resolution. The establishment of biologically more relevant 3D neuronal networks in a soft hydrogel composed of native Extra Cellular Matrix (ECM) components was compared with conventional two-dimensional networks grown on a stiff substrate. Images of cells in the hydrogel scaffold reveal significantly different networking characteristics compared to the 2D networks, raising the question whether the functionality of neurons grown as layers in conventional cultivation dishes represents that of neurons in the central and peripheral nervous systems.

  17. Fabrication and characterization of porous PHBV scaffolds for tissue engineering

    NASA Astrophysics Data System (ADS)

    Ruiz, I.; Hermida, . B.; Baldessari, A.

    2011-12-01

    Porous scaffolds of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) were elaborated by three different techniques: salt leaching (SL), emulsion solvent evaporation (ESE) and temperature induced phase separation (TIPS). For SL partially fused sieved grains of sodium chloride (106-355 ?m) were used as porogen. Emulsions, prepared from a solution of PHBV in chloroform allow getting flexible films; the content of surfactant may be used to control the pore size. The pore size of the TIPS scaffolds decreased on increasing the cooling rate and the morphology of the interconnected structure could be controlled by changing the temperature gradient. Finally, chemical changes associated to the enhancement of hydrophilic behaviour of the scaffolds after alkaline and enzymatic hydrolysis as well as after sterilization by ? irradiation are presented.

  18. Highly porous 3D nanofiber scaffold using an electrospinning technique.

    PubMed

    Kim, Geunhyung; Kim, WanDoo

    2007-04-01

    A successful 3D tissue-engineering scaffold must have a highly porous structure and good mechanical stability. High porosity and optimally designed pore size provide structural space for cell accommodation and migration and enable the exchange of nutrients between the scaffold and environment. Poly(epsilon-carprolactone) fibers were electrospun using an auxiliary electrode and chemical blowing agent (BA), and characterized according to porosity, pore size, and their mechanical properties. We also investigated the effect of the BA on the electrospinning processability. The growth characteristic of human dermal fibroblasts cells cultured in the webs showed the good adhesion with the blown web relative to a normal electrospun mat. The blown nanofiber web had good tensile properties and high porosity compared to a typical electrospun nanofiber scaffold. PMID:16924612

  19. Three-dimensional printing of porous ceramic scaffolds for bone tissue engineering.

    PubMed

    Seitz, Hermann; Rieder, Wolfgang; Irsen, Stephan; Leukers, Barbara; Tille, Carsten

    2005-08-01

    This article reports a new process chain for custom-made three-dimensional (3D) porous ceramic scaffolds for bone replacement with fully interconnected channel network for the repair of osseous defects from trauma or disease. Rapid prototyping and especially 3D printing is well suited to generate complex-shaped porous ceramic matrices directly from powder materials. Anatomical information obtained from a patient can be used to design the implant for a target defect. In the 3D printing technique, a box filled with ceramic powder is printed with a polymer-based binder solution layer by layer. Powder is bonded in wetted regions. Unglued powder can be removed and a ceramic green body remains. We use a modified hydroxyapatite (HA) powder for the fabrication of 3D printed scaffolds due to the safety of HA as biocompatible implantable material and efficacy for bone regeneration. The printed ceramic green bodies are consolidated at a temperature of 1250 degrees C in a high temperature furnace in ambient air. The polymeric binder is pyrolysed during sintering. The resulting scaffolds can be used in tissue engineering of bone implants using patient-derived cells that are seeded onto the scaffolds. This article describes the process chain, beginning from data preparation to 3D printing tests and finally sintering of the scaffold. Prototypes were successfully manufactured and characterized. It was demonstrated that it is possible to manufacture parts with inner channels with a dimension down to 450 microm and wall structures with a thickness down to 330 microm. The mechanical strength of dense test parts is up to 22 MPa. PMID:15981173

  20. Graded Porous ?-Tricalcium Phosphate Scaffolds Enhance Bone Regeneration in Mandible Augmentation

    PubMed Central

    Yang, Jingwen; Kang, Yunqing; Browne, Christopher; Jiang, Ting; Yang, Yunzhi

    2015-01-01

    Abstract Bone augmentation requires scaffold to promote forming of natural bone structure. Currently, most of the reported bone scaffolds are porous solids with uniform pores. The aim of the currentstudy is to evaluate the effect of a graded porous ?-tricalcium phosphate scaffolds on alveolar bone augmentation. Three groups of scaffolds were fabricated by a template-casting method: (1) graded porous scaffolds with large pores in the center and small pores at theperiphery, (2) scaffolds with large uniform pores, and (3) scaffolds with small uniform pores. Bone augmentation on rabbit mandible wasinvestigated by microcomputed tomography, sequential fluorescentlabeling, and histologic examination 3 months after implantation.The result presents that all the scaffold groups maintain their augmented bone height after 3-month observation, whereas the autograftinggroup presents an obvious bone resorption. Microcomputed tomography reveals that the graded porous group has significantly greater volume of new bone (P < 0.05) and similar bone density compared with the uniform pores groups. Bone substance distributes unevenly in all the 3 experimental groups. Greater bone volume can be observed in the area closer to the bone bed. The sequential fluorescentlabeling observation reveals robust bone regeneration in the first month and faster bone growth in the graded porous scaffold group than that in the large porous scaffold group. Histologic examinationsconfirm bone structure in the aspect of distribution, activity, and maturity. We conclude that graded porous designed biodegradable?-tricalcium phosphate scaffolds are beneficial to promote bone augmentation in the aspect of bone volume. PMID:25675019

  1. Ovalbumin-Based Porous Scaffolds for Bone Tissue Regeneration

    PubMed Central

    Farrar, Gabrielle; Barone, Justin; Morgan, Abby

    2010-01-01

    Cell differentiation on glutaraldehyde cross-linked ovalbumin scaffolds was the main focus of this research. Salt leaching and freeze drying were used to create a three-dimensional porous structure. Average pore size was 147.84 ± 40.36 μm and 111.79 ± 30.71 μm for surface and cross sectional area, respectively. Wet compressive strength and elastic modulus were 6.8 ± 3.6 kPa. Average glass transition temperature was 320.1 ± 1.4°C. Scaffolds were sterilized with ethylene oxide prior to seeding MC3T3-E1 cells. Cells were stained with DAPI and Texas red to determine morphology and proliferation. Average cell numbers increased between 4-hour- and 96-hour-cultured scaffolds. Alkaline phosphatase and osteocalcin levels were measured at 3, 7, 14, and 21 days. Differentiation studies showed an increase in osteocalcin at 21 days and alkaline phosphatase levels at 14 days, both indicating differentiation occurred. This work demonstrated the use of ovalbumin scaffolds for a bone tissue engineering application. PMID:21350641

  2. Porous polymeric materials for hydrogen storage

    DOEpatents

    Yu, Luping; Liu, Di-Jia; Yuan, Shengwen; Yang, Junbing

    2013-04-02

    A porous polymer, poly-9,9'-spirobifluorene and its derivatives for storage of H.sub.2 are prepared through a chemical synthesis method. The porous polymers have high specific surface area and narrow pore size distribution. Hydrogen uptake measurements conducted for these polymers determined a higher hydrogen storage capacity at the ambient temperature over that of the benchmark materials. The method of preparing such polymers, includes oxidatively activating solids by CO.sub.2/steam oxidation and supercritical water treatment.

  3. Effect of porous YSZ scaffold microstructure on the long-term performance of infiltrated Ni-YSZ anodes

    NASA Astrophysics Data System (ADS)

    Buyukaksoy, Aligul; Kammampata, Sanoop P.; Birss, Viola I.

    2015-08-01

    Ni infiltration into porous YSZ scaffolds is a promising route for the construction of high performing and redox-stable Ni-YSZ anodes for application in solid oxide fuel cells (SOFCs). However, the long-term instability of this type of anode is a critical problem. Here, it is shown that an interconnected Ni film, rather than discrete Ni particles, can be formed inside a porous, pre-sintered YSZ scaffold by using a polymeric Ni-based precursor as the infiltration medium. To understand the effect of the YSZ microstructure on the long-term stability and the electrochemical performance of the resulting composites, two types of Ni-YSZ anodes were investigated. Anodes prepared by polymeric Ni infiltration into a YSZ scaffold with large grains (0.5 ?m) and pores (0.5 ?m and 5 ?m) showed extensive agglomeration in the Ni phase, resulting in poor stability and poor activity. In contrast, Ni infiltration into YSZ scaffolds with finer particle and pore sizes (?200 nm each) produced anodes with a very small polarization resistance of ca. 0.1 ? cm2 per electrode at 800 C. An increase of only ?5% was seen in the resistance after ca. 110 h at this temperature, achieved by preventing Ni agglomeration.

  4. Diffusion model to describe osteogenesis within a porous titanium scaffold.

    PubMed

    Schmitt, M; Allena, R; Schouman, T; Frasca, S; Collombet, J M; Holy, X; Rouch, P

    2016-01-01

    In this study, we develop a two-dimensional finite element model, which is derived from an animal experiment and allows simulating osteogenesis within a porous titanium scaffold implanted in ewe's hemi-mandible during 12 weeks. The cell activity is described through diffusion equations and regulated by the stress state of the structure. We compare our model to (i) histological observations and (ii) experimental data obtained from a mechanical test done on sacrificed animal. We show that our mechano-biological approach provides consistent numerical results and constitutes a useful tool to predict osteogenesis pattern. PMID:25573031

  5. Porous polymeric materials for hydrogen storage

    DOEpatents

    Yu, Luping (Hoffman Estates, IL); Liu, Di-Jia (Naperville, IL); Yuan, Shengwen (Chicago, IL); Yang, Junbing (Westmont, IL)

    2011-12-13

    Porous polymers, tribenzohexazatriphenylene, poly-9,9'-spirobifluorene, poly-tetraphenyl methane and their derivatives for storage of H.sub.2 prepared through a chemical synthesis method. The porous polymers have high specific surface area and narrow pore size distribution. Hydrogen uptake measurements conducted for these polymers determined a higher hydrogen storage capacity at the ambient temperature over that of the benchmark materials. The method of preparing such polymers, includes oxidatively activating solids by CO.sub.2/steam oxidation and supercritical water treatment.

  6. Fabrication and properties of porous scaffold of magnesium phosphate/polycaprolactone biocomposite for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Wu, Fan; Liu, Changsheng; O'Neill, Brian; Wei, Jie; Ngothai, Yung

    2012-07-01

    In this study, porous scaffolds made of magnesium phosphate (MP)/polycaprolactone (PCL) biocomposite were developed for bone tissue engineering applications. The composite scaffolds were fabricated by the particulate leaching method using sodium chloride particles as porogen. The obtained scaffold with porosity around 73% presents a porous structure with interconnected open pores. Hydrophilicity of the scaffolds was enhanced by the incorporation of MP component as demonstrated by the water contact angle measurement. The results of the in vitro degradation study show that the MP/PCL composite scaffolds degraded faster than PCL scaffolds in phosphate buffered saline (PBS). In addition, the degradation rate of the scaffolds could be tuned by adjusting the content of MP component in the composite. The results indicate that the MP/PCL composite scaffold has a potential application in bone tissue engineering.

  7. Polycaprolactone coated porous tricalcium phosphate scaffolds for controlled release of protein for tissue engineering

    PubMed Central

    Xue, Weichang; Bandyopadhyay, Amit; Bose, Susmita

    2010-01-01

    Polycaprolactone (PCL) was coated on porous tricalcium phosphate (TCP) scaffolds to achieve controlled protein delivery. Porous TCP scaffolds were fabricated using reticulated polyurethane foam as sacrificial scaffold with a porosity of 70–90 vol %. PCL was coated on sintered porous TCP scaffolds by dipping-drying process. The compressive strength of TCP scaffolds increased significantly after PCL coating. The highest strength of 2.41 MPa at a porosity of 70% was obtained for the TCP scaffold coated with 5% PCL solution. Model protein bovine serum albumin (BSA) was encapsulated efficiently within the PCL coating. The amount of BSA encapsulation was controlled by varying proteins’ composition in the PCL coating. The FTIR analysis confirmed that BSA retained its structural conformation and did not show significant denaturization during PCL coating. The release kinetics in phosphate buffer solution indicated that the protein release was controlled and sustained, and primarily dependant on protein concentration encapsulated in the PCL coating. PMID:19572301

  8. Designing and modeling doubly porous polymeric materials

    NASA Astrophysics Data System (ADS)

    Ly, H.-B.; Le Droumaguet, B.; Monchiet, V.; Grande, D.

    2015-07-01

    Doubly porous organic materials based on poly(2-hydroxyethyl methacrylate) are synthetized through the use of two distinct types of porogen templates, namely a macroporogen and a nanoporogen. Two complementary strategies are implemented by using either sodium chloride particles or fused poly(methyl methacrylate) beads as macroporogens, in conjunction with ethanol as a porogenic solvent. The porogen removal respectively allows for the generation of either non-interconnected or interconnected macropores with an average diameter of about 100-200 ?m and nanopores with sizes lying within the 100 nm order of magnitude, as evidenced by mercury intrusion porosimetry and scanning electron microscopy. Nitrogen sorption measurements evidence the formation of materials with rather high specific surface areas, i.e. higher than 140 m2.g-1. This paper also addresses the development of numerical tools for computing the permeability of such doubly porous materials. Due to the coexistence of well separated scales between nanopores and macropores, a consecutive double homogenization approach is proposed. A nanoscopic scale and a mesoscopic scale are introduced, and the flow is evaluated by means of the Finite Element Method to determine the macroscopic permeability. At the nanoscopic scale, the flow is described by the Stokes equations with an adherence condition at the solid surface. At the mesoscopic scale, the flow obeys the Stokes equations in the macropores and the Darcy equation in the permeable polymer in order to account for the presence of the nanopores.

  9. In vitro degradation and mechanical properties of PLA-PCL copolymer unit cell scaffolds generated by two-photon polymerization.

    PubMed

    Felfel, R M; Poocza, Leander; Gimeno-Fabra, Miquel; Milde, Tobias; Hildebrand, Gerhard; Ahmed, Ifty; Scotchford, Colin; Sottile, Virginie; Grant, David M; Liefeith, Klaus

    2016-01-01

    The manufacture of 3D scaffolds with specific controlled porous architecture, defined microstructure and an adjustable degradation profile was achieved using two-photon polymerization (TPP) with a size of 2  ×  4  ×  2 mm(3). Scaffolds made from poly(D,L-lactide-co-ɛ-caprolactone) copolymer with varying lactic acid (LA) and ɛ -caprolactone (CL) ratios (LC16:4, 18:2 and 9:1) were generated via ring-opening-polymerization and photoactivation. The reactivity was quantified using photo-DSC, yielding a double bond conversion ranging from 70% to 90%. The pore sizes for all LC scaffolds were see 300 μm and throat sizes varied from 152 to 177 μm. In vitro degradation was conducted at different temperatures; 37, 50 and 65 °C. Change in compressive properties immersed at 37 °C over time was also measured. Variations in thermal, degradation and mechanical properties of the LC scaffolds were related to the LA/CL ratio. Scaffold LC16:4 showed significantly lower glass transition temperature (T g) (4.8 °C) in comparison with the LC 18:2 and 9:1 (see 32 °C). Rates of mass loss for the LC16:4 scaffolds at all temperatures were significantly lower than that for LC18:2 and 9:1. The degradation activation energies for scaffold materials ranged from 82.7 to 94.9 kJ mol(-1). A prediction for degradation time was applied through a correlation between long-term degradation studies at 37 °C and short-term studies at elevated temperatures (50 and 65 °C) using the half-life of mass loss (Time (M1/2)) parameter. However, the initial compressive moduli for LC18:2 and 9:1 scaffolds were 7 to 14 times higher than LC16:4 (see 0.27) which was suggested to be due to its higher CL content (20%). All scaffolds showed a gradual loss in their compressive strength and modulus over time as a result of progressive mass loss over time. The manufacturing process utilized and the scaffolds produced have potential for use in tissue engineering and regenerative medicine applications. PMID:26836023

  10. Rapid prototyped porous nickel–titanium scaffolds as bone substitutes

    PubMed Central

    Hoffmann, Waldemar; Bormann, Therese; Rossi, Antonella; Müller, Bert; Schumacher, Ralf; Martin, Ivan; Wendt, David

    2014-01-01

    While calcium phosphate–based ceramics are currently the most widely used materials in bone repair, they generally lack tensile strength for initial load bearing. Bulk titanium is the gold standard of metallic implant materials, but does not match the mechanical properties of the surrounding bone, potentially leading to problems of fixation and bone resorption. As an alternative, nickel–titanium alloys possess a unique combination of mechanical properties including a relatively low elastic modulus, pseudoelasticity, and high damping capacity, matching the properties of bone better than any other metallic material. With the ultimate goal of fabricating porous implants for spinal, orthopedic and dental applications, nickel–titanium substrates were fabricated by means of selective laser melting. The response of human mesenchymal stromal cells to the nickel–titanium substrates was compared to mesenchymal stromal cells cultured on clinically used titanium. Selective laser melted titanium as well as surface-treated nickel–titanium and titanium served as controls. Mesenchymal stromal cells had similar proliferation rates when cultured on selective laser melted nickel–titanium, clinically used titanium, or controls. Osteogenic differentiation was similar for mesenchymal stromal cells cultured on the selected materials, as indicated by similar gene expression levels of bone sialoprotein and osteocalcin. Mesenchymal stromal cells seeded and cultured on porous three-dimensional selective laser melted nickel–titanium scaffolds homogeneously colonized the scaffold, and following osteogenic induction, filled the scaffold’s pore volume with extracellular matrix. The combination of bone-related mechanical properties of selective laser melted nickel–titanium with its cytocompatibility and support of osteogenic differentiation of mesenchymal stromal cells highlights its potential as a superior bone substitute as compared to clinically used titanium. PMID:25383165

  11. Delivery of growth factors using a smart porous nanocomposite scaffold to repair a mandibular bone defect.

    PubMed

    Liu, Xian; Zhao, Kun; Gong, Tao; Song, Jian; Bao, Chongyun; Luo, En; Weng, Jie; Zhou, Shaobing

    2014-03-10

    Implantation of a porous scaffold with a large volume into the body in a convenient and safe manner is still a challenging task in the repair of bone defects. In this study, we present a porous smart nanocomposite scaffold with a combination of shape memory function and controlled delivery of growth factors. The shape memory function enables the scaffold with a large volume to be deformed into its temporal architecture with a small volume using hot-compression and can subsequently recover its original shape upon exposure to body temperature after it is implanted in the body. The scaffold consists of chemically cross-linked poly(ε-caprolactone) (c-PCL) and hydroxyapatite nanoparticles. The highly interconnected pores of the scaffold were obtained using the sugar leaching method. The shape memory porous scaffold loaded with bone morphogenetic protein-2 (BMP-2) was also fabricated by coating the calcium alginate layer and BMP-2 on the surface of the pore wall. Under both in vitro and in vivo environmental conditions, the porous scaffold displays good shape memory recovery from the compressed shape with deformed pores of 33 μm in diameter to recover its porous shape with original pores of 160 μm in diameter. In vitro cytotoxicity based on the MTT test revealed that the scaffold exhibited good cytocompatibility. The in vivo micro-CT and histomorphometry results demonstrated that the porous scaffold could promote new bone generation in the rabbit mandibular bone defect. Thus, our results indicated that this shape memory porous scaffold demonstrated great potential for application in bone regenerative medicine. PMID:24467335

  12. Gelatin-layered and multi-sized porous ?-tricalcium phosphate for tissue engineering scaffold

    PubMed Central

    2012-01-01

    The multi-sized porous ?-tricalcium phosphate scaffolds were fabricated by freeze drying followed by slurry coating using a multi-sized porous sponge as a template. Then, gelatin was dip coated on the multi-sized porous ?-tricalcium phosphate scaffolds under vacuum. The mechanical and biological properties of the fabricated scaffolds were evaluated and compared to the uniformly sized porous scaffolds and scaffolds that were not coated by gelatin. The compressive strength was tested by a universal testing machine, and the cell viability and differentiation behavior were measured using a cell counting kit and alkaline phosphatase activity using the MC3T3-E1 cells. In comparison, the gelatin-coated multi-sized porous ?-tricalcium phosphate scaffold showed enhanced compressive strength. After 14 days, the multi-sized pores were shown to affect cell differentiation, and gelatin coatings were shown to affect the cell viability and differentiation. The results of this study demonstrated that the multi-sized porous ?-tricalcium phosphate scaffold coated by gelatin enhanced the mechanical and biological strengths. PMID:22252276

  13. Nanoscale Control of Silks for Nanofibrous Scaffold Formation with Improved Porous Structure

    PubMed Central

    Lin, Shasha; Lu, Guozhong; Liu, Shanshan; Bai, Shumeng; Liu, Xi; Lu, Qiang; Zuo, Baoqi; Kaplan, David L.; Zhu, Hesun

    2014-01-01

    Silk-based porous scaffolds have been used extensively in tissue engineering because of their excellent biocompatibility, tunable biodegradability and robust mechanical properties. Although many silk-based scaffolds have been prepared through freeze-drying, a challenge remains to effectively control porous structures during this process. In the present study silk fibroin with different nanostructures were self-assembled in aqueous solution by repeated drying-dissolving process and then used to improve porous structure formation in lyophilization process. Viscosity, secondary structures and water interactions were also studied to exclude their influence on the formation and control of porous structures. Following nanofiber formation in aqueous solution, silk scaffolds with improved porous structure were directly formed after lyophilization and then stabilized with water or methanol annealing treatments. Compared to silk scaffolds derived from fresh solution, the nanofibrous scaffolds showed significantly better cell compatibility in vitro. Therefore, this nanoscale control of silk offers feasible way to regulate the matrix features including porous structure and nanostructure, which are important in regulating cell and tissue outcomes in tissue engineering and regeneration, and then achieve silk-based scaffolds with improved properties. PMID:24949200

  14. Fabrication of uniformly cell-laden porous scaffolds using a gas-in-liquid templating technique.

    PubMed

    Takei, Takayuki; Aokawa, Ryuta; Shigemitsu, Takamasa; Kawakami, Koei; Yoshida, Masahiro

    2015-11-01

    Design of porous scaffolds in tissue engineering field was challenging. Uniform immobilization of cells in the scaffolds with high porosity was essential for homogeneous tissue formation. The present study was aimed at fabricating uniformly cell-laden porous scaffolds with porosity >74% using the gas-in-liquid foam templating technique. To this end, we used gelatin, microbial transglutaminase and argon gas as a scaffold material, cross-linker of the protein and porogen of scaffold, respectively. We confirmed that a porosity of >74% could be achieved by increasing the gas volume delivered to a gelatin solution. Pore size in the scaffold could be controlled by stirring speed, stirring time and the pore size of the filter through which the gas passed. The foaming technique enabled us to uniformly immobilize a human hepatoblastoma cell line in scaffold. Engraftment efficiency of the cell line entrapped within the scaffold in nude mice was higher than that of cells in free-form. These results showed that the uniformly cell-laden porous scaffolds were promising for tissue engineering. PMID:25912452

  15. Three-dimensional plotter technology for fabricating polymeric scaffolds with micro-grooved surfaces.

    PubMed

    Son, JoonGon; Kim, GeunHyung

    2009-01-01

    Various mechanical techniques have been used to fabricate biomedical scaffolds, including rapid prototyping (RP) devices that operate from CAD files of the target feature information. The three-dimensional (3-D) bio-plotter is one RP system that can produce design-based scaffolds with good mechanical properties for mimicking cartilage and bones. However, the scaffolds fabricated by RP have very smooth surfaces, which tend to discourage initial cell attachment. Initial cell attachment, migration, differentiation and proliferation are strongly dependent on the chemical and physical characteristics of the scaffold surface. In this study, we propose a new 3-D plotting method supplemented with a piezoelectric system for fabricating surface-modified scaffolds. The effects of the physically-modified surface on the mechanical and hydrophilic properties were investigated, and the results of cell culturing of chondrocytes indicate that this technique is a feasible new method for fabricating high-quality 3-D polymeric scaffolds. PMID:19874679

  16. Processing and characterization of chitosan/PVA and methylcellulose porous scaffolds for tissue engineering.

    PubMed

    Kanimozhi, K; Khaleel Basha, S; Sugantha Kumari, V

    2016-04-01

    Biomimetic porous scaffold chitosan/poly(vinyl alcohol) CS/PVA containing various amounts of methylcellulose (MC) (25%, 50% and 75%) incorporated in CS/PVA blend was successfully produced by a freeze drying method in the present study. The composite porous scaffold membranes were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), swelling degree, porosity, degradation of films in Hank's solution and the mechanical properties. Besides these characterizations, the antibacterial activity of the prepared scaffolds was tested, toward the bacterial species Staphylococcus aureus (S.aureus) and Escherichia coli (E.coli). FTIR, XRD and DSC demonstrated that there was strong intermolecular hydrogen bonding between the molecules of CS/PVA and MC. The crystalline microstructure of the scaffold membranes was not well developed. SEM images showed that the morphology and diameter of the scaffolds were mainly affected by the weight ratio of MC. By increasing the MC content in the hybrid scaffolds, their swelling capacity and porosity increased. The mechanical properties of these scaffolds in dry and swollen state were greatly improved with high swelling ratio. The elasticity of films was also significantly improved by the incorporation of MC, and the scaffolds could also bear a relative high tensile strength. These findings suggested that the developed scaffold possess the prerequisites and can be used as a scaffold for tissue engineering. PMID:26838875

  17. Preparation and Evaluation of Gelatin-Chitosan-Nanobioglass 3D Porous Scaffold for Bone Tissue Engineering

    PubMed Central

    Maji, Kanchan; Dasgupta, Sudip; Pramanik, Krishna; Bissoyi, Akalabya

    2016-01-01

    The aim of the present study was to prepare and characterize bioglass-natural biopolymer based composite scaffold and evaluate its bone regeneration ability. Bioactive glass nanoparticles (58S) in the size range of 20–30 nm were synthesized using sol-gel method. Porous scaffolds with varying bioglass composition from 10 to 30 wt% in chitosan, gelatin matrix were fabricated using the method of freeze drying of its slurry at 40 wt% solids loading. Samples were cross-linked with glutaraldehyde to obtain interconnected porous 3D microstructure with improved mechanical strength. The prepared scaffolds exhibited >80% porosity with a mean pore size range between 100 and 300 microns. Scaffold containing 30 wt% bioglass (GCB 30) showed a maximum compressive strength of 2.2 ± 0.1 MPa. Swelling and degradation studies showed that the scaffold had excellent properties of hydrophilicity and biodegradability. GCB 30 scaffold was shown to be noncytotoxic and supported mesenchymal stem cell attachment, proliferation, and differentiation as indicated by MTT assay and RUNX-2 expression. Higher cellular activity was observed in GCB 30 scaffold as compared to GCB 0 scaffold suggesting the fact that 58S bioglass nanoparticles addition into the scaffold promoted better cell adhesion, proliferation, and differentiation. Thus, the study showed that the developed composite scaffolds are potential candidates for regenerating damaged bone tissue. PMID:26884764

  18. The interaction between bone marrow stromal cells and RGD modified three dimensional porous polycaprolactone scaffolds

    PubMed Central

    Zhang, Huina; Lin, Chia-Ying; Hollister, Scott J

    2015-01-01

    We previously established a simple method to immobilize the Arg-Gly-Asp (RGD) peptide on polycaprolactone (PCL) two-dimensional film surfaces that significantly improved bone marrow stromal cell (BMSC) adhesion to these films. The current work extends this modification strategy to three-dimensional (3D) PCL scaffolds to investigate BMSCs attachment, cellular distribution and cellularity, signal transduction and survival on the modified PCL scaffold compared to those on the untreated ones. The results demonstrated that treatment of 3D PCL scaffold surfaces with 1,6-hexanediamine introduced the amino functional groups onto the porous PCL scaffold homogenously as detected by a ninhydrin staining method. Followed by the cross-linking reaction, RGDC peptide was successfully immobilized on the surface of PCL scaffold. Although the static seeding method used in this study caused heterogeneous cell distribution, the RGD modified PCL scaffold still demonstrated the improved BMSC attachment and cellular distribution in the scaffold. More importantly, the integrin-mediated signal transduction FAK-PI3K-Akt pathway was significantly up-regulated by RGD modification and a subsequent increase in cell survival and growth was found in the modified scaffold. The present study introduces an easy method to immobilize RGD peptide on the 3D porous PCL scaffold and provides further evidence that modification of 3D PCL scaffolds with RGD peptides elicits specific cellular responses and improves the final cell-biomaterial interaction. PMID:19487019

  19. Preparation and Evaluation of Gelatin-Chitosan-Nanobioglass 3D Porous Scaffold for Bone Tissue Engineering.

    PubMed

    Maji, Kanchan; Dasgupta, Sudip; Pramanik, Krishna; Bissoyi, Akalabya

    2016-01-01

    The aim of the present study was to prepare and characterize bioglass-natural biopolymer based composite scaffold and evaluate its bone regeneration ability. Bioactive glass nanoparticles (58S) in the size range of 20-30 nm were synthesized using sol-gel method. Porous scaffolds with varying bioglass composition from 10 to 30 wt% in chitosan, gelatin matrix were fabricated using the method of freeze drying of its slurry at 40 wt% solids loading. Samples were cross-linked with glutaraldehyde to obtain interconnected porous 3D microstructure with improved mechanical strength. The prepared scaffolds exhibited >80% porosity with a mean pore size range between 100 and 300 microns. Scaffold containing 30 wt% bioglass (GCB 30) showed a maximum compressive strength of 2.2 ± 0.1 MPa. Swelling and degradation studies showed that the scaffold had excellent properties of hydrophilicity and biodegradability. GCB 30 scaffold was shown to be noncytotoxic and supported mesenchymal stem cell attachment, proliferation, and differentiation as indicated by MTT assay and RUNX-2 expression. Higher cellular activity was observed in GCB 30 scaffold as compared to GCB 0 scaffold suggesting the fact that 58S bioglass nanoparticles addition into the scaffold promoted better cell adhesion, proliferation, and differentiation. Thus, the study showed that the developed composite scaffolds are potential candidates for regenerating damaged bone tissue. PMID:26884764

  20. Peracetic acid: a practical agent for sterilizing heat-labile polymeric tissue-engineering scaffolds.

    PubMed

    Yoganarasimha, Suyog; Trahan, William R; Best, Al M; Bowlin, Gary L; Kitten, Todd O; Moon, Peter C; Madurantakam, Parthasarathy A

    2014-09-01

    Advanced biomaterials and sophisticated processing technologies aim at fabricating tissue-engineering scaffolds that can predictably interact within a biological environment at the cellular level. Sterilization of such scaffolds is at the core of patient safety and is an important regulatory issue that needs to be addressed before clinical translation. In addition, it is crucial that meticulously engineered micro- and nano- structures are preserved after sterilization. Conventional sterilization methods involving heat, steam, and radiation are not compatible with engineered polymeric systems because of scaffold degradation and loss of architecture. Using electrospun scaffolds made from polycaprolactone, a low melting polymer, and employing spores of Bacillus atrophaeus as biological indicators, we compared ethylene oxide, autoclaving and 80% ethanol to a known chemical sterilant, peracetic acid (PAA), for their ability to sterilize as well as their effects on scaffold properties. PAA diluted in 20% ethanol to 1000 ppm or above sterilized electrospun scaffolds in 15 min at room temperature while maintaining nano-architecture and mechanical properties. Scaffolds treated with PAA at 5000 ppm were rendered hydrophilic, with contact angles reduced to 0°. Therefore, PAA can provide economical, rapid, and effective sterilization of heat-sensitive polymeric electrospun scaffolds that are used in tissue engineering. PMID:24341350

  1. Peracetic Acid: A Practical Agent for Sterilizing Heat-Labile Polymeric Tissue-Engineering Scaffolds

    PubMed Central

    Yoganarasimha, Suyog; Trahan, William R.; Best, Al M.; Bowlin, Gary L.; Kitten, Todd O.; Moon, Peter C.

    2014-01-01

    Advanced biomaterials and sophisticated processing technologies aim at fabricating tissue-engineering scaffolds that can predictably interact within a biological environment at the cellular level. Sterilization of such scaffolds is at the core of patient safety and is an important regulatory issue that needs to be addressed before clinical translation. In addition, it is crucial that meticulously engineered micro- and nano- structures are preserved after sterilization. Conventional sterilization methods involving heat, steam, and radiation are not compatible with engineered polymeric systems because of scaffold degradation and loss of architecture. Using electrospun scaffolds made from polycaprolactone, a low melting polymer, and employing spores of Bacillus atrophaeus as biological indicators, we compared ethylene oxide, autoclaving and 80% ethanol to a known chemical sterilant, peracetic acid (PAA), for their ability to sterilize as well as their effects on scaffold properties. PAA diluted in 20% ethanol to 1000?ppm or above sterilized electrospun scaffolds in 15?min at room temperature while maintaining nano-architecture and mechanical properties. Scaffolds treated with PAA at 5000?ppm were rendered hydrophilic, with contact angles reduced to 0. Therefore, PAA can provide economical, rapid, and effective sterilization of heat-sensitive polymeric electrospun scaffolds that are used in tissue engineering. PMID:24341350

  2. PHBV/PAM Scaffolds with Local Oriented Structure through UV Polymerization for Tissue Engineering

    PubMed Central

    Wang, Yingjun

    2014-01-01

    Locally oriented tissue engineering scaffolds can provoke cellular orientation and direct cell spread and migration, offering an exciting potential way for the regeneration of the complex tissue. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) scaffolds with locally oriented hydrophilic polyacrylamide (PAM) inside the macropores of the scaffolds were achieved through UV graft polymerization. The interpenetrating PAM chains enabled good interconnectivity of PHBV/PAM scaffolds that presented a lower porosity and minor diameter of pores than PHBV scaffolds. The pores with diameter below 100 μm increased to 82.15% of PHBV/PAM scaffolds compared with 31.5% of PHBV scaffolds. PHBV/PAM scaffold showed a much higher compressive elastic modulus than PHBV scaffold due to PAM stuffing. At 5 days of culturing, sheep chondrocytes spread along the similar direction in the macropores of PHBV/PAM scaffolds. The locally oriented PAM chains might guide the attachment and spreading of chondrocytes and direct the formation of microfilaments via contact guidance. PMID:24579074

  3. Development of porous Ti6Al4V/chitosan sponge composite scaffold for orthopedic applications.

    PubMed

    Guo, Miao; Li, Xiang

    2016-01-01

    A novel composite scaffold consisting of porous Ti6Al4V part filled with chitosan sponge was fabricated using a combination of electron beam melting and freeze-drying. The mechanical properties of porous Ti6Al4V part were examined via compressive test. The ultimate compressive strength was 85.35 8.68 MPa and the compressive modulus was 2.26 0.42 GPa. The microstructure of composite scaffold was characterized using scanning electron microscopy. The chitosan sponge filled in Ti6Al4V part exhibited highly porous and well-interconnected micro-pore architecture. The osteoblastic cells were seeded on scaffolds to test their seeding efficiency and biocompatibility. Significantly higher cell seeding efficiency was found on composite scaffold. The biological response of osteoblasts on composite scaffolds was superior in terms of improved cell attachment, higher proliferation, and well-spread morphology in relation to porous Ti6Al4V part. These results suggest that the Ti6Al4V/chitosan composite scaffold is potentially useful as a biomedical scaffold for orthopedic applications. PMID:26478418

  4. Construction of biocompatible porous tissue scaffold from the decellularized umbilical artery.

    PubMed

    Xin, Yi; Wu, Guanghui; Wu, Man; Zhang, Xiaoxia; Velot, Emilie; Decot, Vronique; Cui, Wei; Huang, Yimin; Stoltz, Jean-Francois; Du, Jie; Li, Na

    2015-01-01

    The scaffolds prepared from the tissue decellularization conserve the porous 3-D structure and provide an optimal matrix for the tissue regeneration. Since decade, the enzymatic digestion, chemical reagent treatment and mechanical actions such as eversion and abrasion have been used to remove the cells from the intact matrix. In this study, we optimized an enzymatic method to decellularize the umbilical artery to construct a 3-D porous scaffold which is suitable for the culture of mesenchymal stem cells (MSCs). The scaffold maintained the interconnected porous structure. It remained the similar high water content 95.3 1% compared to 94.9 0.6% in the intact umbilical artery (p>0.05). The decellularization process decreased the stress from 0.24 0.05 mPa to 0.15 0.06 mPa (p<0.05). However the decellularization did not change the strain of the artery (45 15% vs. 53 10%, p>0.05). When the scaffold was transplanted to the subcutaneous tissue in the wild type mice, there were less T cells appeared in the surrounding tissue which meant the decreased the immunogenicity by decellularization. This scaffold also supported the adhesion and proliferation of the MSCs. In this study, we constructed a biological compatible porous scaffold from the decellularized umbilical artery which may provide a suitable scaffold for cell-matrix interaction studies and for tissue engineering. PMID:25538057

  5. Functionalization of microstructured open-porous bioceramic scaffolds with human fetal bone cells.

    PubMed

    Krauss Juillerat, Franziska; Borcard, Franoise; Staedler, Davide; Scaletta, Corinne; Applegate, Lee Ann; Comas, Horacio; Gauckler, Ludwig J; Gerber-Lemaire, Sandrine; Juillerat-Jeanneret, Lucienne; Gonzenbach, Urs T

    2012-11-21

    Bone substitute materials allowing trans-scaffold migration and in-scaffold survival of human bone-derived cells are mandatory for development of cell-engineered permanent implants to repair bone defects. In this study, we evaluated the influence on human bone-derived cells of the material composition and microstructure of foam scaffolds of calcium aluminate. The scaffolds were prepared using a direct foaming method allowing wide-range tailoring of the microstructure for pore size and pore openings. Human fetal osteoblasts (osteo-progenitors) attached to the scaffolds, migrated across the entire bioceramic depending on the scaffold pore size, colonized, and survived in the porous material for at least 6 weeks. The long-term biocompatibility of the scaffold material for human bone-derived cells was evidenced by in-scaffold determination of cell metabolic activity using a modified MTT assay, a repeated WST-1 assay, and scanning electron microscopy. Finally, we demonstrated that the osteo-progenitors can be covalently bound to the scaffolds using biocompatible click chemistry, thus enhancing the rapid adhesion of the cells to the scaffolds. Therefore, the different microstructures of the foams influenced the migratory potential of the cells, but not cell viability. Scaffolds allow covalent biocompatible chemical binding of the cells to the materials, either localized or widespread integration of the scaffolds for cell-engineered implants. PMID:23116053

  6. Development of a porous PLGA-based scaffold for mastoid air cell regeneration

    PubMed Central

    Gould, Toby W. A.; Birchall, John P.; Mallick, Ali S.; Alliston, Tamara; Lustig, Lawrence R.; Shakesheff, Kevin M.

    2015-01-01

    Objective To develop a porous, biodegradable scaffold for mastoid air cell regeneration. Study Design In vitro development of a temperature-sensitive poly(DL-lactic acid-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) scaffold tailored for this application. Methods Human mastoid bone microstructure and porosity was investigated using micro-computed tomography. PLGA/PEG-alginate scaffolds were developed and scaffold porosity was assessed. Human bone marrow mesenchymal stem cells (hBM-MSCs) were cultured on the scaffolds in vitro. Scaffolds were loaded with ciprofloxacin and release of ciprofloxacin over time in vitro was assessed. Results Porosity of human mastoid bone was measured at 83% with an average pore size of 1.3mm. PLGA/PEG-alginate scaffold porosity ranged from 43–78% depending on the alginate bead content. hBM-MSCs proliferate on the scaffolds in vitro, and release of ciprofloxacin from the scaffolds was demonstrated over 7–10 weeks. Conclusion The PLGA/PEG-alginate scaffolds developed in this study demonstrate similar structural features to human mastoid bone, support cell growth and display sustained antibiotic release. These scaffolds may be of potential clinical use in mastoid air cell regeneration. Further in vivo studies to assess the suitability of PLGA/PEG-alginate scaffolds for this application are required. PMID:23670365

  7. Porous chitosan scaffold cross-linked by chemical and natural procedure applied to investigate cell regeneration

    NASA Astrophysics Data System (ADS)

    Yao, Chih-Kai; Liao, Jiunn-Der; Chung, Chia-Wei; Sung, Wei-I.; Chang, Nai-Jen

    2012-12-01

    Porous chitosan scaffold is used for tissue engineering and drug delivery, but is limited as a scaffold material due to its mechanical weakness, which restrains cell adhesion on the surface. In this study, a chemical reagent (citrate) and a natural reagent (genipin) are used as cross-linkers for the formation of chitosan-based films. Nanoindentation technique with a continuous stiffness measurement system is particularly applied on the porous scaffold surface to examine the characteristic modulus and nanohardness of a porous scaffold surface. The characteristic modulus of a genipin-cross-linked chitosan surface is ?2.325 GPa, which is significantly higher than that of an uncross-linked one (?1.292 GPa). The cell-scaffold surface interaction is assessed. The cell morphology and results of an MTS assay of 3T3-fibroblast cells of a genipin-cross-linked chitosan surface indicate that the enhancement of mechanical properties induced cell adhesion and proliferation on the modified porous scaffold surface. The pore size and mechanical properties of porous chitosan film can be tuned for specific applications such as tissue regeneration.

  8. Gelatin porous scaffolds fabricated using a modified gas foaming technique: characterisation and cytotoxicity assessment.

    PubMed

    Poursamar, S Ali; Hatami, Javad; Lehner, Alexander N; da Silva, Cludia L; Ferreira, Frederico Castelo; Antunes, A P M

    2015-03-01

    The current study presents an effective and simple strategy to obtain stable porous scaffolds from gelatin via a gas foaming method. The technique exploits the intrinsic foaming ability of gelatin in the presence of CO2 to obtain a porous structure stabilised with glutaraldehyde. The produced scaffolds were characterised using physical and mechanical characterisation methods. The results showed that gas foaming may allow the tailoring of the 3-dimensional structure of the scaffolds with an interconnected porous structure. To assess the effectiveness of the preparation method in mitigating the potential cytotoxicity risk of using glutaraldehyde as a crosslinker, direct and in-direct cytotoxicity assays were performed at different concentrations of glutaraldehyde. The results indicate the potential of the gas foaming method, in the preparation of viable tissue engineering scaffolds. PMID:25579897

  9. A novel bioactive porous CaSiO3 scaffold for bone tissue engineering.

    PubMed

    Ni, Siyu; Chang, Jiang; Chou, Lee

    2006-01-01

    The aim of this study was to fabricate bioactive porous CaSiO3 scaffolds and examine their effects on proliferation and differentiation of osteoblast-like cells. In this study, porous CaSiO3 scaffolds were obtained by sintering a ceramic slip-coated polymer foam at 1350 degrees C. X-ray diffraction (XRD) of the scaffolds indicated that the products were essentially pure alpha-CaSiO3. The obtained scaffolds had a well-interconnected porous structure with pore sizes ranging from several micrometers to more than 100 microm and porosities of 88.5 +/- 2.8%. The in vitro bioactivity of the scaffolds was investigated by soaking them in simulated body fluid (SBF) for 7 days and then characterizing them by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analysis. The results indicated that hydroxyapatite (HAp) was formed on the surface of the scaffolds. In addition, the scaffolds were incubated in Ringer's solution at 37 degrees C to study the in vitro degradation by measurement of weight loss after incubation, which showed that the CaSiO3 scaffolds were degradable. The cellular responses to the scaffolds were assessed in terms of cell proliferation and differentiation. Osteoblast-like cells were seeded into the CaSiO3 scaffolds. SEM observations showed that there was significant cell adhesion, as the cells spread and grew in the scaffolds. In addition, the proliferation rate and alkaline phosphatase (ALP) activity of the cells in the scaffolds were improved as compared to the controls. These studies demonstrate initial in vitro cell compatibility and their potential application to bone tissue engineering. PMID:16265636

  10. A novel bioactive porous CaSiO3 scaffold for bone tissue engineering.

    TOXLINE Toxicology Bibliographic Information

    Ni S; Chang J; Chou L

    2006-01-01

    The aim of this study was to fabricate bioactive porous CaSiO3 scaffolds and examine their effects on proliferation and differentiation of osteoblast-like cells. In this study, porous CaSiO3 scaffolds were obtained by sintering a ceramic slip-coated polymer foam at 1350 degrees C. X-ray diffraction (XRD) of the scaffolds indicated that the products were essentially pure alpha-CaSiO3. The obtained scaffolds had a well-interconnected porous structure with pore sizes ranging from several micrometers to more than 100 microm and porosities of 88.5 +/- 2.8%. The in vitro bioactivity of the scaffolds was investigated by soaking them in simulated body fluid (SBF) for 7 days and then characterizing them by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analysis. The results indicated that hydroxyapatite (HAp) was formed on the surface of the scaffolds. In addition, the scaffolds were incubated in Ringer's solution at 37 degrees C to study the in vitro degradation by measurement of weight loss after incubation, which showed that the CaSiO3 scaffolds were degradable. The cellular responses to the scaffolds were assessed in terms of cell proliferation and differentiation. Osteoblast-like cells were seeded into the CaSiO3 scaffolds. SEM observations showed that there was significant cell adhesion, as the cells spread and grew in the scaffolds. In addition, the proliferation rate and alkaline phosphatase (ALP) activity of the cells in the scaffolds were improved as compared to the controls. These studies demonstrate initial in vitro cell compatibility and their potential application to bone tissue engineering.

  11. Interactions of coronary artery smooth muscle cells with 3D porous polyurethane scaffolds.

    PubMed

    Grenier, Stéphanie; Sandig, Martin; Holdsworth, David W; Mequanint, Kibret

    2009-05-01

    One strategy in vascular tissue engineering is the design of hybrid vascular substitutes where vascular cells infiltrate biostable porous scaffolds that provides favorable environment for guided cell repopulation and acts as a mechanically supporting layer after the tissue regeneration process. The aim of the present work was to study the interaction of human coronary artery smooth muscle cells (HCASMC) with 3D porous polyurethane scaffolds. We therefore fabricated porous and highly interconnected 3D polyurethane scaffolds that can promote HCASMC attachment, proliferation, and migration. SEM and microCT studies of the fabricated scaffolds showed that the current scaffolds had highly open and interconnected pore structures, with an average porosity of 84%. HCASMC interaction on polyurethane films revealed that cells adhere and express specific marker proteins (vinculin and h-caldesmon). This expression was further enhanced by coating the polyurethane with Matrigel. On uncoated 3D scaffolds, dense spherical aggregates of cells were often encountered with little adhesion of individual cells alongside the struts of the scaffold, independent of the porogens used. In contrast, when cultured on Matrigel-coated scaffolds, cell numbers quickly increased after 14 days and spread along the entire scaffold. At the upper scaffold surface, elongated cells were seen adhering to one another and also to the scaffold surface. These cells were elongated, aligned in parallel and contained abundant F-actin bundles suggesting a differentiated contractile phenotype. Deep into the scaffold, cells were encountered that formed actin-rich lamellipodial extensions spreading along the strut and lacked stress fibers, suggesting active cell migration along the substrate. PMID:18431771

  12. [Study on hydroxyapatite porous scaffold bonded by phosphates and its biocompatibility].

    PubMed

    Dong, Yinsheng; Zhang, Qingguo; Liu, Bin; Guo, Zongke; Lin, Pinghua; Pu, Yuepu

    2005-10-01

    The porous scaffolds for bone tissue engineering were prepared by foam impregnation. The magnesium and aluminum acid phosphates were used as bonder and the hydroxyapatite ((Ca10 (PO4)6(OH)2, HA) powder as raw materials. Scanning electron microscopy (SEM) examination indicated that the 3D interconnected porous structure of the organic foam was replicated well by the scaffolds calcined at high temperature and the structural requirement of tissue engineering was satisfied. XRD analysis showed that the scaffold was composed of HA and Ca7Mg2P6O24 while calcined at 1150 degrees C for shorter time and of (Ca, Mg)3(PO4)2 when the time prolonged to 2 h. There was no peak of CaO found in the scaffolds by XRD. According to the culture in vitro, the scaffold possesses good biocompatibility and certain degree of degradability. PMID:16294736

  13. Nanostructured porous polymeric photonic bandgap structures for sensing

    NASA Astrophysics Data System (ADS)

    Kim, Sung Jin; Chodavarapu, Vamsy P.; Bukowski, Rachel; Titus, A. H.; Cartwright, Alexander N.; Swihart, Mark T.; Bright, Frank; Bunning, Timothy J.

    2007-02-01

    A methodology for enabling biochemical sensing applications using porous polymer photonic bandgap structures is presented. Specifically, we demonstrate an approach to encapsulation of chemical and biological recognition elements within the pores of these structures. This sensing platform is built on our recently demonstrated nanofabrication technique using holographic interferometry of a photo-activated mixture that includes a volatile solvent as well as monomers, photoinitiators, and co-initiators. Evaporation of the solvent after polymerization yields nanoporous polymeric 1D photonic bandgap structures that can be directly integrated into optical sensor systems that we have previously developed. More importantly, these composite structures are simple to fabricate, chromatically tunable, highly versatile, and can be employed as a general template for the encapsulation of biochemical recognition elements. As a specific example of a prototype device, we demonstrate an oxygen (O II) sensor by encapsulating the fluorophore (tris(4,7-diphenyl-1,10-phenathroline)ruthenium(II) within these nanostructured materials. Finally, we report initial results of extending this technique to the development of a hydrophilic porous polymer photonic bandgap structure for sensing in aqueous environments. The ability to control the hydrophilic/hydrophobic nature of these materials has direct impact on chemical and biological sensing.

  14. Biomechanical and biocompatibility characteristics of electrospun polymeric tracheal scaffolds.

    PubMed

    Ajalloueian, Fatemeh; Lim, Mei Ling; Lemon, Greg; Haag, Johannes C; Gustafsson, Ylva; Sjqvist, Sebastian; Beltrn-Rodrguez, Antonio; Del Gaudio, Costantino; Baiguera, Silvia; Bianco, Alessandra; Jungebluth, Philipp; Macchiarini, Paolo

    2014-07-01

    The development of tracheal scaffolds fabricated based on electrospinning technique by applying different ratios of polyethylene terephthalate (PET) and polyurethane (PU) is introduced here. Prior to clinical implantation, evaluations of biomechanical and morphological properties, as well as biocompatibility and cell adhesion verifications are required and extensively performed on each scaffold type. However, the need for bioreactors and large cell numbers may delay the verification process during the early assessment phase. Hence, we investigated the feasibility of performing biocompatibility verification using static instead of dynamic culture. We performed bioreactor seeding on 3-dimensional (3-D) tracheal scaffolds (PET/PU and PET) and correlated the quantitative and qualitative results with 2-dimensional (2-D) sheets seeded under static conditions. We found that an 8-fold reduction for 2-D static seeding density can essentially provide validation on the qualitative and quantitative evaluations for 3-D scaffolds. In vitro studies revealed that there was notably better cell attachment on PET sheets/scaffolds than with the polyblend. However, the in vivo outcomes of cell seeded PET/PU and PET scaffolds in an orthotopic transplantation model in rodents were similar. They showed that both the scaffold types satisfied biocompatibility requirements and integrated well with the adjacent tissue without any observation of necrosis within 30 days of implantation. PMID:24703872

  15. Poly(lactide-co-glycolide) porous scaffolds for tissue engineering and regenerative medicine

    PubMed Central

    Pan, Zhen; Ding, Jiandong

    2012-01-01

    Porous scaffolds fabricated from biocompatible and biodegradable polymers play vital roles in tissue engineering and regenerative medicine. Among various scaffold matrix materials, poly(lactide-co-glycolide) (PLGA) is a very popular and an important biodegradable polyester owing to its tunable degradation rates, good mechanical properties and processibility, etc. This review highlights the progress on PLGA scaffolds. In the latest decade, some facile fabrication approaches at room temperature were put forward; more appropriate pore structures were designed and achieved; the mechanical properties were investigated both for dry and wet scaffolds; a long time biodegradation of the PLGA scaffold was observed and a three-stage model was established; even the effects of pore size and porosity on in vitro biodegradation were revealed; the PLGA scaffolds have also been implanted into animals, and some tissues have been regenerated in vivo after loading cells including stem cells. PMID:23741612

  16. Fabrication of porous polyvinyl alcohol scaffold for bone tissue engineering via selective laser sintering.

    PubMed

    Shuai, Cijun; Mao, Zhongzheng; Lu, Haibo; Nie, Yi; Hu, Huanlong; Peng, Shuping

    2013-03-01

    A tetragonal polyvinyl alcohol (PVA) scaffold with 3D orthogonal periodic porous architecture was fabricated via selective laser sintering (SLS) technology. The scaffold was fabricated under the laser power of 8W, scan speed of 600mm min(-1), laser spot diameter of 0.8mm and layer thickness of 0.15mm. The microstructure analysis showed that the degree of crystallization decreased while the PVA powder melts gradually and fuses together completely with laser power increasing. Thermal decomposition would occur if the laser power was further higher (16W or higher in the case). The porous architecture was controllable and totally interconnected. The porosity of the fabricated scaffolds was measured to be 67.9 2.7% which satisfies the requirement of micro-pores of the bone scaffolds. Its bioactivity and biocompatibility were also evaluated in vitro as tissue engineering (TE) scaffolds. In vitro adhesion assay showed that the amount of pores increased while the scaffold remains stable and intact after immersion in simulated body fluid for seven days. Moreover, the number of MG-63 cells and the bridge between cells increased with increasing time in cell culture. The present work demonstrates that PVA scaffolds with well-defined porous architectures via SLS technology were designed and fabricated for bone TE. PMID:23385303

  17. A Novel Porous Scaffold Fabrication Technique for Epithelial and Endothelial Tissue Engineering

    PubMed Central

    McHugh, Kevin J.; Tao, Sarah L.; Saint-Geniez, Magali

    2014-01-01

    Porous scaffolds have the ability to minimize transport barriers for both two- (2D) and three-dimensional tissue engineering. However, current porous scaffolds may be non-ideal for 2D tissues such as epithelium due to inherent fabrication-based characteristics. While 2D tissues require porosity to support molecular transport, pores must be small enough to prevent cell migration into the scaffold in order to avoid non-epithelial tissue architecture and compromised function. Though electrospun meshes are the most popular porous scaffolds used today, their heterogeneous pore size and intense topography may be poorly-suited for epithelium. Porous scaffolds produced using other methods have similar unavoidable limitations, frequently involving insufficient pore resolution and control, which make them incompatible with 2D tissues. In addition, many of these techniques require an entirely new round of process development in order to change material or pore size. Herein we describe “pore casting,” a fabrication method that produces flat scaffolds with deterministic pore shape, size, and location that can be easily altered to accommodate new materials or pore dimensions. As proof-of-concept, pore-cast poly(ε-caprolactone) (PCL) scaffolds were fabricated and compared to electrospun PCL in vitro using canine kidney epithelium, human colon epithelium, and human umbilical vein endothelium. All cell types demonstrated improved morphology and function on pore-cast scaffolds, likely due to reduced topography and universally small pore size. These results suggest that pore casting is an attractive option for creating 2D tissue engineering scaffolds, especially when the application may benefit from well-controlled pore size or architecture. PMID:23625319

  18. Large Scale Laser Two-Photon Polymerization Structuring for Fabrication of Artificial Polymeric Scaffolds for Regenerative Medicine

    SciTech Connect

    Malinauskas, M.; Purlys, V.; Zukauskas, A.; Rutkauskas, M.; Danilevicius, P.; Paipulas, D.; Bickauskaite, G.; Gadonas, R.; Piskarskas, A.; Bukelskis, L.; Baltriukiene, D.; Bukelskiene, V.; Sirmenis, R.; Gaidukeviciute, A.; Sirvydis, V.

    2010-11-10

    We present a femtosecond Laser Two-Photon Polymerization (LTPP) system of large scale three-dimensional structuring for applications in tissue engineering. The direct laser writing system enables fabrication of artificial polymeric scaffolds over a large area (up to cm in lateral size) with sub-micrometer resolution which could find practical applications in biomedicine and surgery. Yb:KGW femtosecond laser oscillator (Pharos, Light Conversion. Co. Ltd.) is used as an irradiation source (75 fs, 515 nm (frequency doubled), 80 MHz). The sample is mounted on wide range linear motor driven stages having 10 nm sample positioning resolution (XY--ALS130-100, Z--ALS130-50, Aerotech, Inc.). These stages guarantee an overall travelling range of 100 mm into X and Y directions and 50 mm in Z direction and support the linear scanning speed up to 300 mm/s. By moving the sample three-dimensionally the position of laser focus in the photopolymer is changed and one is able to write complex 3D (three-dimensional) structures. An illumination system and CMOS camera enables online process monitoring. Control of all equipment is automated via custom made computer software ''3D-Poli'' specially designed for LTPP applications. Structures can be imported from computer aided design STereoLihography (stl) files or programmed directly. It can be used for rapid LTPP structuring in various photopolymers (SZ2080, AKRE19, PEG-DA-258) which are known to be suitable for bio-applications. Microstructured scaffolds can be produced on different substrates like glass, plastic and metal. In this paper, we present microfabricated polymeric scaffolds over a large area and growing of adult rabbit myogenic stem cells on them. Obtained results show the polymeric scaffolds to be applicable for cell growth practice. It exhibit potential to use it for artificial pericardium in the experimental model in the future.

  19. Large Scale Laser Two-Photon Polymerization Structuring for Fabrication of Artificial Polymeric Scaffolds for Regenerative Medicine

    NASA Astrophysics Data System (ADS)

    Malinauskas, M.; Purlys, V.; Žukauskas, A.; Rutkauskas, M.; Danilevičius, P.; Paipulas, D.; Bičkauskaitė, G.; Bukelskis, L.; Baltriukienė, D.; Širmenis, R.; Gaidukevičiutė, A.; Bukelskienė, V.; Gadonas, R.; Sirvydis, V.; Piskarskas, A.

    2010-11-01

    We present a femtosecond Laser Two-Photon Polymerization (LTPP) system of large scale three-dimensional structuring for applications in tissue engineering. The direct laser writing system enables fabrication of artificial polymeric scaffolds over a large area (up to cm in lateral size) with sub-micrometer resolution which could find practical applications in biomedicine and surgery. Yb:KGW femtosecond laser oscillator (Pharos, Light Conversion. Co. Ltd.) is used as an irradiation source (75 fs, 515 nm (frequency doubled), 80 MHz). The sample is mounted on wide range linear motor driven stages having 10 nm sample positioning resolution (XY—ALS130-100, Z—ALS130-50, Aerotech, Inc.). These stages guarantee an overall travelling range of 100 mm into X and Y directions and 50 mm in Z direction and support the linear scanning speed up to 300 mm/s. By moving the sample three-dimensionally the position of laser focus in the photopolymer is changed and one is able to write complex 3D (three-dimensional) structures. An illumination system and CMOS camera enables online process monitoring. Control of all equipment is automated via custom made computer software "3D-Poli" specially designed for LTPP applications. Structures can be imported from computer aided design STereoLihography (stl) files or programmed directly. It can be used for rapid LTPP structuring in various photopolymers (SZ2080, AKRE19, PEG-DA-258) which are known to be suitable for bio-applications. Microstructured scaffolds can be produced on different substrates like glass, plastic and metal. In this paper, we present microfabricated polymeric scaffolds over a large area and growing of adult rabbit myogenic stem cells on them. Obtained results show the polymeric scaffolds to be applicable for cell growth practice. It exhibit potential to use it for artificial pericardium in the experimental model in the future.

  20. An experimental fatigue study of a porous scaffold for the regeneration of articular cartilage.

    PubMed

    Vikingsson, L; Gmez-Tejedor, J A; Gallego Ferrer, G; Gmez Ribelles, J L

    2015-05-01

    The aim of this experimental study is to predict the long-term mechanical behavior of a porous scaffold implanted in a cartilage defect for tissue engineering purpose. Fatigue studies were performed by up to 100,000 unconfined compression cycles in a polycaprolactone (PCL) scaffold with highly interconnected pores architecture. The scaffold compliance, stress-strain response and hysteresis energy have been measured after different number of fatigue cycles, while the morphology has been observed by scanning electron microscopy at the same fatigue times. To simulate the growing tissue in the scaffold/tissue construct, the scaffold was filled with an aqueous solution of polyvinyl alcohol (PVA) and subjected to repeating cycles of freezing and thawing that increase the hydrogel stiffness. Fatigue studies show that the mechanical loading provokes failure of the dry scaffold at a smaller number of deformation cycles than when it is immersed in water, and also that 100,000 compressive dynamic cycles do not affect the scaffold/gel construct. This shows the stability of the scaffold implanted in a chondral defect and gives a realistic simulation of the mechanical performance from implantation of the empty scaffold to regeneration of the new tissue inside the scaffold's pores. PMID:25814177

  1. Physical modification of the interior surfaces of PLGA porous scaffolds using sugar fibers as template.

    PubMed

    Qu, Zehua; Ding, Jiandong

    2013-01-01

    A three-dimensional (3D) poly(D,L-lactic-co-glycolic acid) porous scaffold with microgrooves and microholes on the pore walls was fabricated by using salt particulates as main porogens and sugar fibers as modifiers. Besides macropores templated from salt particulates, microgrooves and microholes were generated after leaching sugar fibers. The resultant porous scaffolds were of high porosity over 90% and still kept good mechanical properties. The microgrooves were globally randomly distributed, but locally anisotropic, resulting in contact guidance of cells, and an appropriate fraction of fibers in fabrication of 3D scaffolds led to a significantly enhanced cell viability; the microholes increased the loading amount of a model protein bovine serum albumin. Two key ideal parameters of this technical strategy, the full coverage amount of sugar fibers on the salt particulates, m(c), and the ratio of the surface areas of modified and unmodified scaffolds S(in)=S(in,o) were defined and derived. PMID:23565686

  2. Investigation of osteoblast cells behavior in polymeric 3D micropatterned scaffolds using digital holographic microscopy.

    PubMed

    Mihailescu, M; Popescu, R C; Matei, A; Acasandrei, A; Paun, I A; Dinescu, M

    2014-08-01

    The effect of micropatterned polymeric scaffolds on the features of the cultured cells at different time intervals after seeding was investigated by digital holographic microscopy. Both parallel and perpendicular walls, with different heights, were fabricated using two-photon lithography on photopolymers. The walls were subsequently coated with polypyrrole-based thin films using the matrix assisted pulsed laser evaporation technique. Osteoblast-like cells, MG-63 line, were cultured on these polymeric 3D micropatterned scaffolds. To analyze these scaffolds with/without cultured cells, an inverted digital holographic microscope, which provides 3D images, was used. Information about the samples' refractive indices and heights was obtained from the phase shift introduced in the optical path. Characteristics of cell adhesion, alignment, orientation, and morphology as a function of the wall heights and time from seeding were highlighted. PMID:25090313

  3. Incorporation of polymeric microparticles into collagen-hydroxyapatite scaffolds for the delivery of a pro-osteogenic peptide for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    López-Noriega, Adolfo; Quinlan, Elaine; Celikkin, Nehar; O'Brien, Fergal J.

    2015-01-01

    Collagen-hydroxyapatite scaffolds are outstanding materials for bone tissue engineering as they are biocompatible, bioresorbable, osteoconductive, and osteoinductive. The objective of the present work was to assess the potential of increasing their regenerative capacity by functionalising the scaffolds for therapeutic delivery. This was achieved by the utilization of polymeric drug carriers. With this purpose, alginate, chitosan, gelatine, and poly(lactic-co-glycolic acid) (PLGA) microparticles eluting PTHrP 107-111, an osteogenic pentapeptide, were fabricated and tested by incorporating them into the scaffolds. Among them, PLGA microparticles show the most promising characteristics for use as drug delivery devices. Following the incorporation of the microparticles, the scaffolds maintained their interconnected porous structure and the mechanical properties of the materials were not adversely affected. In addition, the microparticles released all their PTHrP 107-111 cargo. Most importantly, the delivered peptide proved to be bioactive and promoted enhanced osteogenesis as assessed by alkaline phosphatase production and osteocalcin and osteopontin gene expression when pre-osteoblastic cells were seeded on the scaffolds. While the focus was on bone repair, the release system described in this study can be used for the delivery of therapeutics for healing and regeneration of a variety of tissue types depending on the type of collagen scaffold chosen.

  4. Label-free magnetic resonance imaging to locate live cells in three-dimensional porous scaffolds

    PubMed Central

    Abarrategi, A.; Fernandez-Valle, M. E.; Desmet, T.; Castejn, D.; Civantos, A.; Moreno-Vicente, C.; Ramos, V.; Sanz-Casado, J. V.; Martnez-Vzquez, F. J.; Dubruel, P.; Miranda, P.; Lpez-Lacomba, J. L.

    2012-01-01

    Porous scaffolds are widely tested materials used for various purposes in tissue engineering. A critical feature of a porous scaffold is its ability to allow cell migration and growth on its inner surface. Up to now, there has not been a method to locate live cells deep inside a material, or in an entire structure, using real-time imaging and a non-destructive technique. Herein, we seek to demonstrate the feasibility of the magnetic resonance imaging (MRI) technique as a method to detect and locate in vitro non-labelled live cells in an entire porous material. Our results show that the use of optimized MRI parameters (4.7 T; repetition time = 3000 ms; echo time = 20 ms; resolution 39 39 m) makes it possible to obtain images of the scaffold structure and to locate live non-labelled cells in the entire material, with a signal intensity higher than that obtained in the culture medium. In the current study, cells are visualized and located in different kinds of porous scaffolds. Moreover, further development of this MRI method might be useful in several three-dimensional biomaterial tests such as cell distribution studies, routine qualitative testing methods and in situ monitoring of cells inside scaffolds. PMID:22442095

  5. Mechanical properties and shape memory effect of 3D-printed PLA-based porous scaffolds.

    PubMed

    Senatov, F S; Niaza, K V; Zadorozhnyy, M Yu; Maksimkin, A V; Kaloshkin, S D; Estrin, Y Z

    2016-04-01

    In the present work polylactide (PLA)/15wt% hydroxyapatite (HA) porous scaffolds with pre-modeled structure were obtained by 3D-printing by fused filament fabrication. Composite filament was obtained by extrusion. Mechanical properties, structural characteristics and shape memory effect (SME) were studied. Direct heating was used for activation of SME. The average pore size and porosity of the scaffolds were 700μm and 30vol%, respectively. Dispersed particles of HA acted as nucleation centers during the ordering of PLA molecular chains and formed an additional rigid fixed phase that reduced molecular mobility, which led to a shift of the onset of recovery stress growth from 53 to 57°C. A more rapid development of stresses was observed for PLA/HA composites with the maximum recovery stress of 3.0MPa at 70°C. Ceramic particles inhibited the growth of cracks during compression-heating-compression cycles when porous PLA/HA 3D-scaffolds recovered their initial shape. Shape recovery at the last cycle was about 96%. SME during heating may have resulted in "self-healing" of scaffold by narrowing the cracks. PLA/HA 3D-scaffolds were found to withstand up to three compression-heating-compression cycles without delamination. It was shown that PLA/15%HA porous scaffolds obtained by 3D-printing with shape recovery of 98% may be used as self-fitting implant for small bone defect replacement owing to SME. PMID:26710259

  6. Effective method for multi-scale gradient porous scaffold design and fabrication.

    PubMed

    Yang, Nan; Zhou, Kuntao

    2014-10-01

    Function-based modeling is a highly flexible porous scaffold design approach for use in tissue engineering. It was recently proposed as a valid tool for constructing cellular structures by providing a compact representation of complex structures. However, current approaches have some limitations with regard to combining multiple function-based substructures. In this short communication, we propose an effective method for combination operations of multiple substructures based on given substructures and boundaries. With this proposed method, a functional gradient porous scaffold (FGPS) with multi-scale substructures could be easily constructed and directly fabricated by using additive manufacturing techniques. PMID:25175242

  7. Porous polymer scaffold for on-site delivery of stem cells - Protects from oxidative stress and potentiates wound tissue repair.

    PubMed

    Geesala, Ramasatyaveni; Bar, Nimai; Dhoke, Neha R; Basak, Pratyay; Das, Amitava

    2016-01-01

    Wound healing by cell transplantation techniques often suffer setbacks due to oxidative stress encountered at injury sites. A porous polyethyleneglycol-polyurethane (PEG-PU) scaffold that facilitates cell delivery and boosts tissue repair was developed through semi-interpenetrating polymer network approach. The key physico-chemical properties assessed confirms these polymeric matrices are highly thermostable, barostable, degrade at an acidic pH (5.8), biodegradable, cytocompatible and possess excellent porosity. Mechanism of cellular penetration into porous polymer networks was evident by a ?6 - fold increase in gene expression of MMP-13 and MMP-2 via activation of Akt and Erk. H2O2-induced apoptosis of mouse bone marrow stem cells (BMSCs) was abrogated in presence of polymer networks indicating a protective effect from oxidative stress. Transplantation of BMSC+PEG-PU at murine excisional splint wound site depicted significant increase in fibroblast proliferation, collagen deposition, anti-oxidant enzyme activities of catalase, SOD and GPx. Furthermore it significantly decreased expression of pro-inflammatory cytokines (IL-1?, TNF-?, IL-8, etc) with a concomitant increase in anti-inflammatory cytokines (IL-10, IL-13) at an early healing period of day 7. Finally, immunostaining revealed an enhanced engraftment and vascularity indicating an accelerated wound tissue closure. This pre-clinical study demonstrates the proof-of-concept and further necessitates their clinical evaluation as potential cell delivery vehicle scaffolds. PMID:26576045

  8. Hydrolytic degradation of porous scaffolds for tissue engineering from terpolymer of L-lactide, ɛ-caprolactone and glycolide

    NASA Astrophysics Data System (ADS)

    Pamuła, Elżbieta; Dobrzyński, Piotr; Bero, Maciej; Paluszkiewicz, Czesława

    2005-06-01

    Segmental terpolymer of L-lactide, ɛ-caprolactone and glycolide have been synthesized by ring-opening polymerization with the use of zirconium acetylacetonate as a biocompatible initiator. Porous scaffolds aimed at tissue engineering have been prepared from resulting terpolymer by solvent casting/particulate leaching technique. Sieved sodium citrate particles of 500-700 μm size have been used as porogens. The obtained scaffolds have been submitted to degradation in phosphate buffered saline (PBS) at 37 °C for 26 weeks and characterized as a function of incubation time by: Fourier transform infrared spectroscopy in the attenuated total reflection mode (FTIR-ATR), nuclear magnetic resonance ( 1H NMR), gel permeation chromatography (GPC) and scanning electron microscopy (SEM). The scaffolds start to degrade immediately after contact with PBS, as demonstrated by decrease in molecular weights ( Mn and Mw). In the first stage (6 weeks in PBS) when the scaffolds are still dimensionally stable, the degradation is generally due to cleavage of ester bonds between glycolidyl (GG) and caproyl (Cap) groups present in chain sequences such as -GGCapCap-, -GGGCap-, as shown by 1H NMR. The analysis of FTIR spectra of the initial scaffolds and after 6 week immersion in PBS reveals a shift of the band attributed to C dbnd6 O vibrations and considerable changes in the shape of the bands attributed to C-O and C-O-C vibrations. These changes are due to chain-scission of polyester bonds in hydrolysis reaction. Subsequently, when the concentration of sequences containing glycol, glycolidyl and caproyl groups decreases, the influence of cleavage of polyester bonds between longer lactyl microblocks on the degradation increases gradually. As a result, two separate polymer fractions are formed.

  9. Tailoring properties of porous Poly (vinylidene fluoride) scaffold through nano-sized 58s bioactive glass.

    PubMed

    Shuai, Cijun; Huang, Wei; Feng, Pei; Gao, Chengde; Shuai, Xiong; Xiao, Tao; Deng, Youwen; Peng, Shuping; Wu, Ping

    2016-01-01

    The biological properties of porous poly (vinylidene fluoride) (PVDF) scaffolds fabricated by selective laser sintering were tailored through nano-sized 58s bioactive glass. The results showed that 58s bioactive glass distributed evenly in the PVDF matrix. There were some exposed particles on the surface which provided attachment sites for biological response. It was confirmed that the scaffolds had highly bioactivity by the formation of bone-like apatite in simulated body fluid. And the bone-like apatite became dense with the increase in 58s bioactive glass and culture time. Moreover, the scaffolds were suitable for cell adhesion and proliferation compared with the PVDF scaffolds without 58s bioactive glass. The research showed that the PVDF/58s bioactive glass scaffolds had latent application in bone tissue engineering. PMID:26592544

  10. Correlation between porous texture and cell seeding efficiency of gas foaming and microfluidic foaming scaffolds.

    PubMed

    Costantini, Marco; Colosi, Cristina; Mozetic, Pamela; Jaroszewicz, Jakub; Tosato, Alessia; Rainer, Alberto; Trombetta, Marcella; Święszkowski, Wojciech; Dentini, Mariella; Barbetta, Andrea

    2016-05-01

    In the design of scaffolds for tissue engineering applications, morphological parameters such as pore size, shape, and interconnectivity, as well as transport properties, should always be tailored in view of their clinical application. In this work, we demonstrate that a regular and ordered porous texture is fundamental to achieve an even cell distribution within the scaffold under perfusion seeding. To prove our hypothesis, two sets of alginate scaffolds were fabricated using two different technological approaches of the same method: gas-in-liquid foam templating. In the first one, foam was obtained by insufflating argon in a solution of alginate and a surfactant under stirring. In the second one, foam was generated inside a flow-focusing microfluidic device under highly controlled and reproducible conditions. As a result, in the former case the derived scaffold (GF) was characterized by polydispersed pores and interconnects, while in the latter (μFL), the porous structure was highly regular both with respect to the spatial arrangement of pores and interconnects and their monodispersity. Cell seeding within perfusion bioreactors of the two scaffolds revealed that cell population inside μFL scaffolds was quantitatively higher than in GF. Furthermore, seeding efficiency data for μFL samples were characterized by a lower standard deviation, indicating higher reproducibility among replicates. Finally, these results were validated by simulation of local flow velocity (CFD) inside the scaffolds proving that μFL was around one order of magnitude more permeable than GF. PMID:26952471

  11. Adipogenic differentiation of stem cells in three-dimensional porous bacterial nanocellulose scaffolds.

    PubMed

    Krontiras, Panagiotis; Gatenholm, Paul; Hgg, Daniel A

    2015-01-01

    There is an increased interest in developing adipose tissue for in vitro and in vivo applications. Current two-dimensional (2D) cell-culture systems of adipocytes are limited, and new methods to culture adipocytes in three-dimensional (3D) are warranted as a more life-like model to study metabolic diseases such as obesity and diabetes. In this study, we have evaluated different porous bacterial nanocellulose scaffolds for 3D adipose tissue. In an initial pilot study, we compared adipogenic differentiation of mice mesenchymal stem cells from a cell line on 2D and 3D scaffolds of bacterial nanocellulose. The 3D scaffolds were engineered by crosslinking homogenized cellulose fibrils using alginate and freeze drying the mixture to obtain a porous structure. Quenching the scaffolds in liquid nitrogen resulted in smaller pores compared to slower freezing using isopropanol. We found that on 2D surfaces, the cells were scarcely distributed and showed limited formation of lipid droplets, whereas cells grown in macroporous 3D scaffolds contained more cells growing in clusters, containing large lipid droplets. All four types of scaffolds contained a lot of adipocytes, but scaffolds with smaller pores contained larger cell clusters than scaffolds with bigger pores, with viable adipocytes present even 4 weeks after differentiation. Scaffolds with lower alginate fractions retained their pore integrity better. We conclude that 3D culturing of adipocytes in bacterial nanocellulose macroporous scaffolds is a promising method for fabrication of adipose tissue as an in vitro model for adipose biology and metabolic disease. PMID:24819827

  12. Characteristics and osteogenic effect of zirconia porous scaffold coated with ?-TCP/HA

    PubMed Central

    Song, Young-Gyun

    2014-01-01

    PURPOSE The purpose of this study was to evaluate the properties of a porous zirconia scaffold coated with bioactive materials and compare the in vitro cellular behavior of MC3T3-E1 preosteoblastic cells to titanium and zirconia disks and porous zirconia scaffolds. MATERIALS AND METHODS Titanium and zirconia disks were prepared. A porous zirconia scaffold was fabricated with an open cell polyurethane disk foam template. The porous zirconia scaffolds were coated with ?-TCP, HA and a compound of ?-TCP and HA (BCP). The characteristics of the specimens were evaluated using scanning electron microscopy (SEM), energy dispersive x-ray spectrometer (EDX), and x-ray diffractometry (XRD). The dissolution tests were analyzed by an inductively coupled plasma spectrometer (ICP). The osteogenic effect of MC3T3-E1 cells was assessed via cell counting and reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS The EDX profiles showed the substrate of zirconia, which was surrounded by the Ca-P layer. In the dissolution test, dissolved Ca2+ ions were observed in the following decreasing order; ?-TCP > BCP > HA (P<.05). In the cellular experiments, the cell proliferation on titanium disks appeared significantly lower in comparison to the other groups after 5 days (P<.05). The zirconia scaffolds had greater values than the zirconia disks (P<.05). The mRNA level of osteocalcin was highest on the non-coated zirconia scaffolds after 7 days. CONCLUSION Zirconia had greater osteoblast cell activity than titanium. The interconnecting pores of the zirconia scaffolds showed enhanced proliferation and cell differentiation. The activity of osteoblast was more affected by microstructure than by coating materials. PMID:25177472

  13. Fabrication of highly porous tissue-engineering scaffolds using selective spherical porogens.

    PubMed

    Johnson, Taylor; Bahrampourian, Rahimeh; Patel, Alpesh; Mequanint, Kibret

    2010-01-01

    Tissue engineering holds great promise as an alternative strategy to current treatment modalities of diseased or otherwise failed tissues. Most strategies of tissue engineering rely on three-dimensional porous scaffolds to mimic the natural extracellular matrix (ECM) as templates onto which cells attach, multiply, migrate and function. When cells are harvested from a donor and seeded, scaffolds facilitate the organization of these cells into a three-dimensional architecture, control cell behavior and subsequently direct the formation of organ-specific tissue. In view of its role, scaffold fabrication methods target the creation of highly porous and interconnected pore structures. Among the different scaffolds fabrication methods explored, solvent casting followed by precipitation or particulate leaching is one of the most straightforward methods. In this paper, we conducted a comparative study of two methods to prepare spherical porogens using poly(vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) as dispersing agents and we used these porogens to fabricate cylindrical porous scaffolds using a combination of pressure differential and solvent casting/particulate leaching method. Porogen particle size analyses showed that at 0.6% dispersing agent concentration, PVP produced smaller particles with narrower distribution (100-300 mum) than poly(vinyl alcohol) (100-500 mum) presumably due to the fast adsorption kinetics of the former. Scaffolds fabricated from PVP-stabilized porogens had higher open porosities and high pore interconnectivity than those based on porogens prepared using PVA stabilizer. Preliminary cell culture work also showed that scaffolds fabricated using PVP-stabilized porogens support attachment and spreading of human coronary artery smooth muscle cells (HCASMC) better than the PVA counterparts. This is the first time that such direct comparative studies on the porogen preparation methods and its effect on the scaffold porosity and cell attachment property is reported. PMID:20592448

  14. A transient cell-shielding method for viable MSC delivery within hydrophobic scaffolds polymerized in situ.

    PubMed

    Guo, Ruijing; Ward, Catherine L; Davidson, Jeffrey M; Duvall, Craig L; Wenke, Joseph C; Guelcher, Scott A

    2015-06-01

    Cell-based therapies have emerged as promising approaches for regenerative medicine. Hydrophobic poly(ester urethane)s offer the advantages of robust mechanical properties, cell attachment without the use of peptides, and controlled degradation by oxidative and hydrolytic mechanisms. However, the application of injectable hydrophobic polymers to cell delivery is limited by the challenges of protecting cells from reaction products and creating a macroporous architecture post-cure. We designed injectable carriers for cell delivery derived from reactive, hydrophobic polyisocyanate and polyester triol precursors. To overcome cell death caused by reaction products from in situ polymerization, we encapsulated bone marrow-derived stem cells (BMSCs) in fastdegrading, oxidized alginate beads prior to mixing with the hydrophobic precursors. Cells survived the polymerization at >70% viability, and rapid dissolution of oxidized alginate beads after the scaffold cured created interconnected macropores that facilitated cellular adhesion to the scaffold in vitro. Applying this injectable system to deliver BMSCs to rat excisional skin wounds showed that the scaffolds supported survival of transplanted cells and infiltration of host cells, which improved new tissue formation compared to both implanted, pre-formed scaffolds seeded with cells and acellular controls. Our design is the first to enable injectable delivery of settable, hydrophobic scaffolds where cell encapsulation provides a mechanism for both temporary cytoprotection during polymerization and rapid formation of macropores post-polymerization. This simple approach provides potential advantages for cell delivery relative to hydrogel technologies, which have weaker mechanical properties and require incorporation of peptides to achieve cell adhesion and degradability. PMID:25907036

  15. Biomimetic apatite-coated porous PVA scaffolds promote the growth of breast cancer cells.

    PubMed

    Ye, Mao; Mohanty, Pravansu; Ghosh, Gargi

    2014-11-01

    Recapitulating the native environment of bone tissue is essential to develop in vitro models of breast cancer bone metastasis. The bone is a composite material consisting of organic matrix and inorganic mineral phase, primarily hydroxyapatite. In this study, we report the mineralization of porous poly vinyl alcohol (PVA) scaffolds upon incubation in modified Hanks' Balanced Salt Solution (HBSS) for 14 days. Scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction analysis revealed that the deposited minerals have composition similar to hydroxyapatite. The study demonstrated that the rate of nucleation and growth of minerals was faster on surfaces of less porous scaffolds. However, upon prolonged incubation, formation of mineral layer was observed on the surface of all the scaffolds. In addition, the study also demonstrated that 3D mineralization only occurred for scaffolds with highly interconnected porous networks. The mineralization of the scaffolds promoted the adsorption of serum proteins and consequently, the adhesion and proliferation of breast cancer cells. PMID:25280710

  16. Interfacing polymeric scaffolds with primary pancreatic ductal adenocarcinoma cells to develop 3D cancer models.

    PubMed

    Ricci, Claudio; Mota, Carlos; Moscato, Stefania; D'Alessandro, Delfo; Ugel, Stefano; Sartoris, Silvia; Bronte, Vincenzo; Boggi, Ugo; Campani, Daniela; Funel, Niccola; Moroni, Lorenzo; Danti, Serena

    2014-01-01

    We analyzed the interactions between human primary cells from pancreatic ductal adenocarcinoma (PDAC) and polymeric scaffolds to develop 3D cancer models useful for mimicking the biology of this tumor. Three scaffold types based on two biocompatible polymeric formulations, such as poly(vinyl alcohol)/gelatin (PVA/G) mixture and poly(ethylene oxide terephthalate)/poly(butylene terephthalate) (PEOT/PBT) copolymer, were obtained via different techniques, namely, emulsion and freeze-drying, compression molding followed by salt leaching, and electrospinning. In this way, primary PDAC cells interfaced with different pore topographies, such as sponge-like pores of different shape and size or nanofiber interspaces. The aim of this study was to investigate the influence played by the scaffold architecture over cancerous cell growth and function. In all scaffolds, primary PDAC cells showed good viability and synthesized tumor-specific metalloproteinases (MMPs) such as MMP-2, and MMP-9. However, only sponge-like pores, obtained via emulsion-based and salt leaching-based techniques allowed for an organized cellular aggregation very similar to the native PDAC morphological structure. Differently, these cell clusters were not observed on PEOT/PBT electrospun scaffolds. MMP-2 and MMP-9, as active enzymes, resulted to be increased in PVA/G and PEOT/PBT sponges, respectively. These findings suggested that spongy scaffolds supported the generation of pancreatic tumor models with enhanced aggressiveness. In conclusion, primary PDAC cells showed diverse behaviors while interacting with different scaffold types that can be potentially exploited to create stage-specific pancreatic cancer models likely to provide new knowledge on the modulation and drug susceptibility of MMPs. PMID:25482337

  17. Interfacing polymeric scaffolds with primary pancreatic ductal adenocarcinoma cells to develop 3D cancer models

    PubMed Central

    Ricci, Claudio; Mota, Carlos; Moscato, Stefania; D’Alessandro, Delfo; Ugel, Stefano; Sartoris, Silvia; Bronte, Vincenzo; Boggi, Ugo; Campani, Daniela; Funel, Niccola; Moroni, Lorenzo; Danti, Serena

    2014-01-01

    We analyzed the interactions between human primary cells from pancreatic ductal adenocarcinoma (PDAC) and polymeric scaffolds to develop 3D cancer models useful for mimicking the biology of this tumor. Three scaffold types based on two biocompatible polymeric formulations, such as poly(vinyl alcohol)/gelatin (PVA/G) mixture and poly(ethylene oxide terephthalate)/poly(butylene terephthalate) (PEOT/PBT) copolymer, were obtained via different techniques, namely, emulsion and freeze-drying, compression molding followed by salt leaching, and electrospinning. In this way, primary PDAC cells interfaced with different pore topographies, such as sponge-like pores of different shape and size or nanofiber interspaces. The aim of this study was to investigate the influence played by the scaffold architecture over cancerous cell growth and function. In all scaffolds, primary PDAC cells showed good viability and synthesized tumor-specific metalloproteinases (MMPs) such as MMP-2, and MMP-9. However, only sponge-like pores, obtained via emulsion-based and salt leaching-based techniques allowed for an organized cellular aggregation very similar to the native PDAC morphological structure. Differently, these cell clusters were not observed on PEOT/PBT electrospun scaffolds. MMP-2 and MMP-9, as active enzymes, resulted to be increased in PVA/G and PEOT/PBT sponges, respectively. These findings suggested that spongy scaffolds supported the generation of pancreatic tumor models with enhanced aggressiveness. In conclusion, primary PDAC cells showed diverse behaviors while interacting with different scaffold types that can be potentially exploited to create stage-specific pancreatic cancer models likely to provide new knowledge on the modulation and drug susceptibility of MMPs. PMID:25482337

  18. A Porous Tissue Engineering Scaffold Selectively Degraded by Cell-Generated Reactive Oxygen Species

    PubMed Central

    Martin, John R.; Gupta, Mukesh K.; Page, Jonathan M.; Yu, Fang; Davidson, Jeffrey M.; Guelcher, Scott A.

    2014-01-01

    Biodegradable tissue engineering scaffolds are commonly fabricated from poly(lactide-co-glycolide) (PLGA) or similar polyesters that degrade by hydrolysis. PLGA hydrolysis generates acidic breakdown products that trigger an accelerated, autocatalytic degradation mechanism that can create mismatched rates of biomaterial breakdown and tissue formation. Reactive oxygen species (ROS) are key mediators of cell function in both health and disease, especially at sites of inflammation and tissue healing, and induction of inflammation and ROS are natural components of the in vivo response to biomaterial implantation. Thus, polymeric biomaterials that are selectively degraded by cell-generated ROS may have potential for creating tissue engineering scaffolds with better matched rates of tissue in-growth and cell-mediated scaffold biodegradation. To explore this approach, a series of poly(thioketal) (PTK) urethane (PTK-UR) biomaterial scaffolds were synthesized that degrade specifically by an ROS-dependent mechanism. PTK-UR scaffolds had significantly higher compressive moduli than analogous poly(ester urethane) (PEUR) scaffolds formed from hydrolytically-degradable ester-based diols (p < 0.05). Unlike PEUR scaffolds, the PTK-UR scaffolds were stable under aqueous conditions out to 25 weeks but were selectively degraded by ROS, indicating that their biodegradation would be exclusively cell-mediated. The in vitro oxidative degradation rates of the PTK-URs followed first-order degradation kinetics, were significantly dependent on PTK composition (p < 0.05), and correlated to ROS concentration. In subcutaneous rat wounds, PTK-UR scaffolds supported cellular infiltration and granulation tissue formation, followed first-order degradation kinetics over 7 weeks, and produced significantly greater stenting of subcutaneous wounds compared to PEUR scaffolds. These combined results indicate that ROS-degradable PTK-UR tissue engineering scaffolds have significant advantages over analogous polyester-based biomaterials and provide a robust, cell-degradable substrate for guiding new tissue formation. PMID:24491510

  19. Bilayer porous scaffold based on poly-(?-caprolactone) nanofibrous membrane and gelatin sponge for favoring cell proliferation

    NASA Astrophysics Data System (ADS)

    Zhou, Zhihua; Zhou, Yang; Chen, Yiwang; Nie, Huarong; Wang, Yang; Li, Fan; Zheng, Yan

    2011-12-01

    Electrospun poly-(?-caprolactone) (PCL) nanofibers has been widely used in the medical prosthesis. However, poor hydrophilicity and the lack of natural recognition sites for covalent cell-recognition signal molecules to promote cell attachment have limited its utility as tissue scaffolds. In this study, Bilayer porous scaffolds based on PCL electrospun membranes and gelatin (GE) sponges were fabricated through soft hydrolysis of PCL electrospun followed by grafting gelatin onto the fiber surface, through crosslinking and freeze drying treatment of additional gelatin coat and grafted gelatin surface. GE sponges were stably anchored on PCL membrane surface with the aid of grafted GE molecules. The morphologies of bilayer porous scaffolds were observed through SEM. The contact angle of the scaffolds was 0, the mechanical properties of scaffolds were measured by tensile test, Young's moduli of PCL scaffolds before and after hydrolysis are 66-77.3 MPa and 62.3-75.4 MPa, respectively. Thus, the bilayer porous scaffolds showed excellent hydrophilic surface and desirable mechanical strength due to the soft hydrolysis and GE coat. The cell culture results showed that the adipose derived mesenchymal stem cells did more favor to adhere and grow on the bilayer porous scaffolds than on PCL electrospun membranes. The better cell affinity of the final bilayer scaffolds not only attributed to the surface chemistry but also the introduction of bilayer porous structure.

  20. Distribution and Viability of Fetal and Adult Human Bone Marrow Stromal Cells in a Biaxial Rotating Vessel Bioreactor after Seeding on Polymeric 3D Additive Manufactured Scaffolds

    PubMed Central

    Leferink, Anne M.; Chng, Yhee-Cheng; van Blitterswijk, Clemens A.; Moroni, Lorenzo

    2015-01-01

    One of the conventional approaches in tissue engineering is the use of scaffolds in combination with cells to obtain mechanically stable tissue constructs in vitro prior to implantation. Additive manufacturing by fused deposition modeling is a widely used technique to produce porous scaffolds with defined pore network, geometry, and therewith defined mechanical properties. Bone marrow-derived mesenchymal stromal cells (MSCs) are promising candidates for tissue engineering-based cell therapies due to their multipotent character. One of the hurdles to overcome when combining additive manufactured scaffolds with MSCs is the resulting heterogeneous cell distribution and limited cell proliferation capacity. In this study, we show that the use of a biaxial rotating bioreactor, after static culture of human fetal MSCs (hfMSCs) seeded on synthetic polymeric scaffolds, improved the homogeneity of cell and extracellular matrix distribution and increased the total cell number. Furthermore, we show that the relative mRNA expression levels of indicators for stemness and differentiation are not significantly changed upon this bioreactor culture, whereas static culture shows variations of several indicators for stemness and differentiation. The biaxial rotating bioreactor presented here offers a homogeneous distribution of hfMSCs, enabling studies on MSCs fate in additive manufactured scaffolds without inducing undesired differentiation. PMID:26557644

  1. Fabrication of porous titanium scaffold with controlled porous structure and net-shape using magnesium as spacer.

    PubMed

    Kim, Sung Won; Jung, Hyun-Do; Kang, Min-Ho; Kim, Hyoun-Ee; Koh, Young-Hag; Estrin, Yuri

    2013-07-01

    This paper reports a new approach to fabricating biocompatible porous titanium with controlled pore structure and net-shape. The method is based on using sacrificial Mg particles as space holders to produce compacts that are mechanically stable and machinable. Using magnesium granules and Ti powder, Ti/Mg compacts with transverse rupture strength (~85 MPa) sufficient for machining were fabricated by warm compaction, and a complex-shape Ti scaffold was eventually produced by removal of Mg granules from the net-shape compact. The pores with the average size of 132-262 ?m were well distributed and interconnected. Due to anisotropy and alignment of the pores the compressive strength varied with the direction of compression. In the case of pores aligned with the direction of compression, the compressive strength values (59-280 MPa) high enough for applications in load bearing implants were achieved. To verify the possibility of controlled net-shape, conventional machining process was performed on Ti/Mg compact. Compact with screw shape and porous Ti scaffold with hemispherical cup shape were fabricated by the results. Finally, it was demonstrated by cell tests using MC3T3-E1 cell line that the porous Ti scaffolds fabricated by this technique are biocompatible. PMID:23623100

  2. Functionalized ormosil scaffolds processed by direct laser polymerization for application in tissue engineering

    NASA Astrophysics Data System (ADS)

    Matei, A.; Schou, J.; Canulescu, S.; Zamfirescu, M.; Albu, C.; Mitu, B.; Buruiana, E. C.; Buruiana, T.; Mustaciosu, C.; Petcu, I.; Dinescu, M.

    2013-08-01

    Synthesized N,N'-(methacryloyloxyethyl triehtoxy silyl propyl carbamoyl-oxyhexyl)-urea hybrid methacrylate was polymerized by direct laser polymerization using femtosecond laser pulses with the aim of using it for subsequent applications in tissue engineering. The as-obtained scaffolds were modified either by low pressure argon plasma treatment or by covering the structures with two different proteins (lysozyme, fibrinogen). For improved adhesion, the proteins were deposited by matrix assisted pulsed laser evaporation technique. The functionalized structures were tested in mouse fibroblasts culture and the cells morphology, proliferation, and attachment were analyzed.

  3. Nanoscale modification of porous gelatin scaffolds with chondroitin sulfate for corneal stromal tissue engineering

    PubMed Central

    Lai, Jui-Yang; Li, Ya-Ting; Cho, Ching-Hsien; Yu, Ting-Chun

    2012-01-01

    Recent studies reflect the importance of using naturally occurring biopolymers as three-dimensional corneal keratocyte scaffolds and suggest that the porous structure of gelatin materials may play an important role in controlling nutrient uptake. In the current study, the authors further consider the application of carbodiimide cross-linked porous gelatin as an alternative to collagen for corneal stromal tissue engineering. The authors developed corneal keratocyte scaffolds by nanoscale modification of porous gelatin materials with chondroitin sulfate (CS) using carbodiimide chemistry. Scanning electron microscopy/energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy showed that the amount of covalently incorporated polysaccharide was significantly increased when the CS concentration was increased from 0% to 1.25% (w/v). In addition, as demonstrated by dimethylmethylene blue assays, the CS content in these samples was in the range of 0.0780.149 nmol per 10 mg scaffold. When compared with their counterparts without CS treatment, various CS-modified porous gelatin membranes exhibited higher levels of water content, light transmittance, and amount of permeated nutrients but possessed lower Youngs modulus and resistance against protease digestion. The hydrophilic and mechanical properties of scaffolds modified with 0.25% CS were comparable with those of native corneas. The samples from this group were biocompatible with the rabbit corneal keratocytes and showed enhanced proliferative and biosynthetic capacity of cultured cells. In summary, the authors found that the nanoscale-level modification has influence on the characteristics and cell-material interactions of CS-containing gelatin hydrogels. Porous membranes with a CS content of 0.112 0.003 nmol per 10 mg scaffold may hold potential for use in corneal stromal tissue engineering. PMID:22403490

  4. Heterogeneous minimal surface porous scaffold design using the distance field and radial basis functions.

    PubMed

    Yoo, Dongjin

    2012-06-01

    This paper presented an effective method for the 3D heterogeneous porous scaffold design of human tissue using triply periodic minimal surface (TPMS) internal pore architectures. First, an implicit solid representing the smooth 3D scalar field for the porosity distribution was reconstructed by interpolating the geometric positions of control points and porosity values defined at those points using an implicit interpolation algorithm based on the thin-plate radial basis function. After generating the implicit solid representing the smooth 3D scalar field for the porosity distribution, a functionally graded tissue scaffold with accurately controlled porosity distribution was designed using the TPMS-based unit cell libraries. Numerical results showed that the proposed scaffold design method has the potential benefits for accurately controlling the spatial porosity distribution within an arbitrarily shaped scaffold while keeping the advantage of the TPMS-based unit cell libraries. PMID:22487098

  5. Correlation between properties and microstructure of laser sintered porous β-tricalcium phosphate bone scaffolds

    NASA Astrophysics Data System (ADS)

    Shuai, Cijun; Feng, Pei; Zhang, Liyang; Gao, Chengde; Hu, Huanlong; Peng, Shuping; Min, Anjie

    2013-10-01

    A porous β-tricalcium phosphate (β-TCP) bioceramic scaffold was successfully prepared with our homemade selective laser sintering system. Microstructure observation by a scanning electron microscope showed that the grains grew from 0.21 to 1.32 μm with the decrease of laser scanning speed from 250 to 50 mm min-1. The mechanical properties increased mainly due to the improved apparent density when the laser scanning speed decreased to 150 mm min-1. When the scanning speed was further decreased, the grain size became larger and the mechanical properties severely decreased. The highest Vickers hardness and fracture toughness of the scaffold were 3.59 GPa and 1.16 MPa m1/2, respectively, when laser power was 11 W, spot size was 1 mm in diameter, layer thickness was 0.1-0.2 mm and laser scanning speed was 150 mm min-1. The biocompatibility of these scaffolds was assessed in vitro with MG63 osteoblast-like cells and human bone marrow mesenchymal stem cells. The results showed that all the prepared scaffolds are suitable for cell attachment and differentiation. Moreover, the smaller the grain size, the better the cell biocompatibility. The porous scaffold with a grain size of 0.71 μm was immersed in a simulated body fluid for different days to assess the bioactivity. The surface of the scaffold was covered by a bone-like apatite layer, which indicated that the β-TCP scaffold possesses good bioactivity. These discoveries demonstrated the evolution rule between grain microstructure and the properties that give a useful reference for the fabrication of β-TCP bone scaffolds.

  6. Surface modification of biodegradable porous Mg bone scaffold using polycaprolactone/bioactive glass composite.

    PubMed

    Yazdimamaghani, Mostafa; Razavi, Mehdi; Vashaee, Daryoosh; Tayebi, Lobat

    2015-04-01

    A reduction in the degradation rate of magnesium (Mg) and its alloys is in high demand to enable these materials to be used in orthopedic applications. For this purpose, in this paper, a biocompatible polymeric layer reinforced with a bioactive ceramic made of polycaprolactone (PCL) and bioactive glass (BG) was applied on the surface of Mg scaffolds using dip-coating technique under low vacuum. The results indicated that the PCL-BG coated Mg scaffolds exhibited noticeably enhanced bioactivity compared to the uncoated scaffold. Moreover, the mechanical integrity of the Mg scaffolds was improved using the PCL-BG coating on the surface. The stable barrier property of the coatings effectively delayed the degradation activity of Mg scaffold substrates. Moreover, the coatings induced the formation of apatite layer on their surface after immersion in the SBF, which can enhance the biological bone in-growth and block the microcracks and pore channels in the coatings, thus prolonging their protective effect. Furthermore, it was shown that a three times increase in the concentration of PCL-BG noticeably improved the characteristics of scaffolds including their degradation resistance and mechanical stability. Since bioactivity, degradation resistance and mechanical integrity of a bone substitute are the key factors for repairing and healing fractured bones, we suggest that PCL-BG is a suitable coating material for surface modification of Mg scaffolds. PMID:25686970

  7. Microwave-assisted synthesis of porous chitosan-modified montmorillonite-hydroxyapatite composite scaffolds.

    PubMed

    Kar, Sumanta; Kaur, Tejinder; Thirugnanam, A

    2016-01-01

    In this study, a porous chitosan-organically modified montmorillonite-hydroxyapatite (CS-OM-HA) composite scaffold was developed by combining microwave irradiation and gas foaming method. Hydroxyapatite (HA) particles of size ?65nm were synthesized and characterized by X-ray diffraction (XRD) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The prepared composite scaffolds were characterized using ATR-FTIR, XRD, mercury intrusion porosimeter (MIP) and scanning electron microscopy (SEM) studies. The synergistic effect of HA and OM on the mechanical and in vitro biological properties (swelling, degradation, protein adsorption and bioactivity) of the composite scaffolds were evaluated. Swelling, degradation, mechanical property, bioactivity and protein adsorption studies of CS-OM-HA composite scaffolds have shown desirable results in comparison with the pure CS and CS-OM composite scaffolds. CS-OM-HA composite scaffolds were also found to be non-cytotoxic to MG 63 osteoblast cell lines. From the study, it can be concluded that the novel CS-OM-HA composite scaffold with improved mechanical and in vitro biological properties has wide potential in non-load bearing bone tissue engineering applications. PMID:26505953

  8. Attachment, Proliferation, and Chondroinduction of Mesenchymal Stem Cells on Porous Chitosan-Calcium Phosphate Scaffolds

    PubMed Central

    Elder, Steven; Gottipati, Anuhya; Zelenka, Hilary; Bumgardner, Joel

    2013-01-01

    Symptomatic osteochondral lesions occur frequently, but relatively few treatment options are currently available. The purpose of this study was to conduct a preliminary investigation into a new tissue engineering approach to osteochondral regeneration. The concept is a biphasic construct consisting of a porous, osteoconductive chitosan-calcium phosphate scaffold supporting a layer of neocartilage formed by marrow-derived mesenchymal stem cells. Two experiments were conducted to assess the feasibility of this approach. The first experiment characterized the attachment efficiency and proliferation of primary human marrow-derived mesenchymal stem cells seeded relatively sparely onto the scaffolds surface. The second experiment compared two different methods of creating a biphasic construct using a much higher density of primary porcine marrow stromal cells. About 40% of the sparsely seeded human cells attached and proliferated rapidly. Constructs formed by one of the two experimental techniques exhibited a layer of cartilaginous tissue which only partially covered the scaffolds surface due to inadequate adhesion between the cells and the scaffold. This study demonstrates some potential for the approach to yield an implantable biphasic construct, but further development is required to improve cell-scaffold adhesion. PMID:23986794

  9. Biodegradable CSMA/PECA/Graphene Porous Hybrid Scaffold for Cartilage Tissue Engineering

    PubMed Central

    Liao, JinFeng; Qu, Ying; Chu, BingYang; Zhang, XiaoNing; Qian, ZhiYong

    2015-01-01

    Owing to the limited repair capacity of articular cartilage, it is essential to develop tissue-engineered cartilage for patients suffering from joint disease and trauma. Herein, we prepared a novel hybrid scaffold composed of methacrylated chondroitin sulfate (CSMA), poly(ethylene glycol) methyl ether-ε-caprolactone-acryloyl chloride (MPEG-PCL-AC, PECA was used as abbreviation for MPEG-PCL-AC) and graphene oxide (GO) and evaluated its potential application in cartilage tissue engineering. To mimic the natural extracellular matrix (ECM) of cartilage, the scaffold had an adequate pore size, porosity, swelling ability, compression modulus and conductivity. Cartilage cells contacted with the scaffold remained viable and showed growth potential. Furthermore, CSMA/PECA/GO scaffold was biocompatible and had a favorable degradation rate. In the cartilage tissue repair of rabbit, Micro-CT and histology observation showed the group of CSMA/PECA/GO scaffold with cellular supplementation had better chondrocyte morphology, integration, continuous subchondral bone, and much thicker newly formed cartilage compared with scaffold group and control group. Our results show that the CSMA/PECA/GO hybrid porous scaffold can be applied in articular cartilage tissue engineering and may have great potential to in other types of tissue engineering applications. PMID:25961959

  10. Mechanical characterization of injection-molded macro porous bioceramic bone scaffolds.

    PubMed

    Vivanco, Juan; Aiyangar, Ameet; Araneda, Aldo; Ploeg, Heidi-Lynn

    2012-05-01

    Bioactive ceramic materials like tricalcium phosphate (TCP) have been emerging as viable material alternatives to the current therapies of bone scaffolding to target fracture healing and osteoporosis. Both material and architectural characteristics play a critical role in the osteoconductive capacity and strength of bone scaffolds. Thus, the objective of this research was to investigate the sintering temperature effect of a cost-effective manufacturing process on the architecture and mechanical properties of a controlled macro porous bioceramic bone scaffold. In this study the physical and mechanical properties of ?-TCP bioceramic scaffolds were investigated as a function of the sintering temperature in the range of 950-1150 C. Physical properties investigated included bulk dimensions, pore size, and strut thickness; and, compressive mechanical properties were evaluated in air at room temperature and in saline solution at body temperature. Statistically significant increases in apparent elastic modulus were measured for scaffolds sintered at higher temperatures. Structural stiffness for all the specimens was significantly reduced when tested at body temperature in saline solution. These findings support the development of clinically successful bioceramic scaffolds that may stimulate bone regeneration and scaffold integration while providing structural integrity. PMID:22498292

  11. Porous scaffold design using the distance field and triply periodic minimal surfacemodels.

    PubMed

    Yoo, Dong J

    2011-11-01

    An effective method for the 3D porous scaffold design of human tissue is presented based on a hybrid method of distance field and triply periodic minimal surface (TPMS). By the creative application of traditional distance field algorithm into the Boolean operations of the anatomical model and TPMS-based unit cell library, an almost defects free porous scaffolds having the complicated micro-structure and high quality external surface faithful to a specific anatomic model can be easily obtained without the difficult and time-consuming trimming and re-meshing processes. After generating the distance fields for the given tissue model and required internal micro-structure, a series of simple modifications in distance fields enable us to obtain a complex porous scaffold. Experimental results show that the proposed scaffold design method has the potential to combine the perfectly interconnected pore networks based on the TPMS unit cell libraries and the given external geometry in a consistent framework irrespective of the complexity of the models. PMID:21798592

  12. PLLA-collagen and PLLA-gelatin hybrid scaffolds with funnel-like porous structure for skin tissue engineering

    NASA Astrophysics Data System (ADS)

    Lu, Hongxu; Oh, Hwan Hee; Kawazoe, Naoki; Yamagishi, Kozo; Chen, Guoping

    2012-12-01

    In skin tissue engineering, a three-dimensional porous scaffold is necessary to support cell adhesion and proliferation and to guide cells moving into the repair area in the wound healing process. Structurally, the porous scaffold should have an open and interconnected porous architecture to facilitate homogenous cell distribution. Moreover, the scaffolds should be mechanically strong to protect deformation during the formation of new skin. In this study, the hybrid scaffolds were prepared by forming funnel-like collagen or gelatin sponge on a woven poly(l-lactic acid) (PLLA) mesh. The hybrid scaffolds combined the advantages of both collagen or gelatin (good cell-interactions) and PLLA mesh (high mechanical strength). The hybrid scaffolds were used to culture dermal fibroblasts for dermal tissue engineering. The funnel-like porous structure promoted homogeneous cell distribution and extracellular matrix production. The PLLA mesh reinforced the scaffold to avoid deformation. Subcutaneous implantation showed that the PLLA-collagen and PLLA-gelatin scaffolds promoted the regeneration of dermal tissue and epidermis and reduced contraction during the formation of new tissue. These results indicate that funnel-like hybrid scaffolds can be used for skin tissue regeneration.

  13. Porous Hydroxyapatite Bioceramic Scaffolds for Drug Delivery and Bone Regeneration

    NASA Astrophysics Data System (ADS)

    Loca, Dagnija; Locs, Janis; Salma, Kristine; Gulbis, Juris; Salma, Ilze; Berzina-Cimdina, Liga

    2011-10-01

    The conventional methods of supplying a patient with pharmacologic active substances suffer from being very poorly selective, so that damage can occurs to the healthy tissues and organs, different from the intended target. In addition, high drug doses can be required to achieve the desired effect. An alternative approach is based on the use of implantable delivery tools, able to release the active substance in a controlled way. In the current research local drug delivery devices containing 8mg of gentamicin sulphate were prepared using custom developed vacuum impregnation technique. In vitro dissolution tests showed that gentamicin release was sustained for 12h. In order to decrease gentamicin release rate, biopolymer coatings were applied and coating structure investigated. The results showed that gentamicin release can be sustained for more than 70h for poly(epsilon-caprolactone) coated calcium phosphate scaffolds. From poly lactic acid and polyvinyl alcohol coated scaffolds gentamicin was released within 20h and 50h, respectively.

  14. Simple method to generate and fabricate stochastic porous scaffolds.

    PubMed

    Yang, Nan; Gao, Lilan; Zhou, Kuntao

    2015-11-01

    Considerable effort has been made to generate regular porous structures (RPSs) using function-based methods, although little effort has been made for constructing stochastic porous structures (SPSs) using the same methods. In this short communication, we propose a straightforward method for SPS construction that is simple in terms of methodology and the operations used. Using our method, we can obtain a SPS with functionally graded, heterogeneous and interconnected pores, target pore size and porosity distributions, which are useful for applications in tissue engineering. The resulting SPS models can be directly fabricated using additive manufacturing (AM) techniques. PMID:26249613

  15. Label-free Raman monitoring of extracellular matrix formation in three-dimensional polymeric scaffolds

    PubMed Central

    Kunstar, Aliz; Leferink, Anne M.; Okagbare, Paul I.; Morris, Michael D.; Roessler, Blake J.; Otto, Cees; Karperien, Marcel; van Blitterswijk, Clemens A.; Moroni, Lorenzo; van Apeldoorn, Aart A.

    2013-01-01

    Monitoring extracellular matrix (ECM) components is one of the key methods used to determine tissue quality in three-dimensional scaffolds for regenerative medicine and clinical purposes. Raman spectroscopy can be used for non-invasive sensing of cellular and ECM biochemistry. We have investigated the use of conventional (confocal and semiconfocal) Raman microspectroscopy and fibre-optic Raman spectroscopy for in vitro monitoring of ECM formation in three-dimensional poly(ethylene oxide terephthalate)poly(butylene terephthalate) (PEOT/PBT) scaffolds. Chondrocyte-seeded PEOT/PBT scaffolds were analysed for ECM formation by Raman microspectroscopy, biochemical analysis, histology and scanning electron microscopy. ECM deposition in these scaffolds was successfully detected by biochemical and histological analysis and by label-free non-destructive Raman microspectroscopy. In the spectra collected by the conventional Raman set-ups, the Raman bands at 937 and at 1062 cm?1 which, respectively, correspond to collagen and sulfated glycosaminoglycans could be used as Raman markers for ECM formation in scaffolds. Collagen synthesis was found to be different in single chondrocyte-seeded scaffolds when compared with microaggregate-seeded samples. Normalized band-area ratios for collagen content of single cell-seeded samples gradually decreased during a 21-day culture period, whereas collagen content of the microaggregate-seeded samples significantly increased during this period. Moreover, a fibre-optic Raman set-up allowed for the collection of Raman spectra from multiple pores inside scaffolds in parallel. These fibre-optic measurements could give a representative average of the ECM Raman signal present in tissue-engineered constructs. Results in this study provide proof-of-principle that Raman microspectroscopy is a promising non-invasive tool to monitor ECM production and remodelling in three-dimensional porous cartilage tissue-engineered constructs. PMID:23825118

  16. Label-free Raman monitoring of extracellular matrix formation in three-dimensional polymeric scaffolds.

    PubMed

    Kunstar, Aliz; Leferink, Anne M; Okagbare, Paul I; Morris, Michael D; Roessler, Blake J; Otto, Cees; Karperien, Marcel; van Blitterswijk, Clemens A; Moroni, Lorenzo; van Apeldoorn, Aart A

    2013-09-01

    Monitoring extracellular matrix (ECM) components is one of the key methods used to determine tissue quality in three-dimensional scaffolds for regenerative medicine and clinical purposes. Raman spectroscopy can be used for non-invasive sensing of cellular and ECM biochemistry. We have investigated the use of conventional (confocal and semiconfocal) Raman microspectroscopy and fibre-optic Raman spectroscopy for in vitro monitoring of ECM formation in three-dimensional poly(ethylene oxide terephthalate)-poly(butylene terephthalate) (PEOT/PBT) scaffolds. Chondrocyte-seeded PEOT/PBT scaffolds were analysed for ECM formation by Raman microspectroscopy, biochemical analysis, histology and scanning electron microscopy. ECM deposition in these scaffolds was successfully detected by biochemical and histological analysis and by label-free non-destructive Raman microspectroscopy. In the spectra collected by the conventional Raman set-ups, the Raman bands at 937 and at 1062 cm(-1) which, respectively, correspond to collagen and sulfated glycosaminoglycans could be used as Raman markers for ECM formation in scaffolds. Collagen synthesis was found to be different in single chondrocyte-seeded scaffolds when compared with microaggregate-seeded samples. Normalized band-area ratios for collagen content of single cell-seeded samples gradually decreased during a 21-day culture period, whereas collagen content of the microaggregate-seeded samples significantly increased during this period. Moreover, a fibre-optic Raman set-up allowed for the collection of Raman spectra from multiple pores inside scaffolds in parallel. These fibre-optic measurements could give a representative average of the ECM Raman signal present in tissue-engineered constructs. Results in this study provide proof-of-principle that Raman microspectroscopy is a promising non-invasive tool to monitor ECM production and remodelling in three-dimensional porous cartilage tissue-engineered constructs. PMID:23825118

  17. An animal experimental study of porous magnesium scaffold degradation and osteogenesis

    PubMed Central

    Liu, Y.J.; Yang, Z.Y.; Tan, L.L.; Li, H.; Zhang, Y.Z.

    2014-01-01

    Our objective was to observe the biodegradable and osteogenic properties of magnesium scaffolding under in vivo conditions. Twelve 6-month-old male New Zealand white rabbits were randomly divided into two groups. The chosen operation site was the femoral condyle on the right side. The experimental group was implanted with porous magnesium scaffolds, while the control group was implanted with hydroxyapatite scaffolds. X-ray and blood tests, which included serum magnesium, alanine aminotransferase (ALT), creatinine (CREA), and blood urea nitrogen (BUN) were performed serially at 1, 2, and 3 weeks, and 1, 2, and 3 months. All rabbits were killed 3 months postoperatively, and the heart, kidney, spleen, and liver were analyzed with hematoxylin and eosin (HE) staining. The bone samples were subjected to microcomputed tomography scanning (micro-CT) and hard tissue biopsy. SPSS 13.0 (USA) was used for data analysis, and values of P<0.05 were considered to be significant. Bubbles appeared in the X-ray of the experimental group after 2 weeks, whereas there was no gas in the control group. There were no statistical differences for the serum magnesium concentrations, ALT, BUN, and CREA between the two groups (P>0.05). All HE-stained slices were normal, which suggested good biocompatibility of the scaffold. Micro-CT showed that magnesium scaffolds degraded mainly from the outside to inside, and new bone was ingrown following the degradation of magnesium scaffolds. The hydroxyapatite scaffold was not degraded and had fewer osteoblasts scattered on its surface. There was a significant difference in the new bone formation and scaffold bioabsorption between the two groups (9.291.27 vs 1.400.49 and 7.800.50 vs 0.000.00 mm3, respectively; P<0.05). The magnesium scaffold performed well in degradation and osteogenesis, and is a promising material for orthopedics. PMID:25098717

  18. An animal experimental study of porous magnesium scaffold degradation and osteogenesis.

    PubMed

    Liu, Y J; Yang, Z Y; Tan, L L; Li, H; Zhang, Y Z

    2014-08-01

    Our objective was to observe the biodegradable and osteogenic properties of magnesium scaffolding under in vivo conditions. Twelve 6-month-old male New Zealand white rabbits were randomly divided into two groups. The chosen operation site was the femoral condyle on the right side. The experimental group was implanted with porous magnesium scaffolds, while the control group was implanted with hydroxyapatite scaffolds. X-ray and blood tests, which included serum magnesium, alanine aminotransferase (ALT), creatinine (CREA), and blood urea nitrogen (BUN) were performed serially at 1, 2, and 3 weeks, and 1, 2, and 3 months. All rabbits were killed 3 months postoperatively, and the heart, kidney, spleen, and liver were analyzed with hematoxylin and eosin (HE) staining. The bone samples were subjected to microcomputed tomography scanning (micro-CT) and hard tissue biopsy. SPSS 13.0 (USA) was used for data analysis, and values of P<0.05 were considered to be significant. Bubbles appeared in the X-ray of the experimental group after 2 weeks, whereas there was no gas in the control group. There were no statistical differences for the serum magnesium concentrations, ALT, BUN, and CREA between the two groups (P>0.05). All HE-stained slices were normal, which suggested good biocompatibility of the scaffold. Micro-CT showed that magnesium scaffolds degraded mainly from the outside to inside, and new bone was ingrown following the degradation of magnesium scaffolds. The hydroxyapatite scaffold was not degraded and had fewer osteoblasts scattered on its surface. There was a significant difference in the new bone formation and scaffold bioabsorption between the two groups (9.29 1.27 vs 1.40 0.49 and 7.80 0.50 vs 0.00 0.00 mm3, respectively; P<0.05). The magnesium scaffold performed well in degradation and osteogenesis, and is a promising material for orthopedics. PMID:25098717

  19. Effects of surfactants on the microstructure of porous ceramic scaffolds fabricated by foaming for bone tissue engineering

    SciTech Connect

    Wang Xi; Ruan Jianming; Chen Qiyuan

    2009-06-03

    A porous scaffold comprising a {beta}-tricalcium phosphate matrix and bioactive glass powders was fabricated by foaming method and the effects of surfactants as foaming agent on microstructure of scaffolds were investigated. Foaming capacity and foam stability of different surfactants in water firstly were carried out to evaluate their foam properties. The porous structure and pore size distribution of the scaffolds were systematically characterized by scanning electron microscopy (SEM) and an optical microscopy connected to an image analyzer. The results showed that the foam stability of surfactant has more remarkable influence on their microstructure such as pore shape, size and interconnectivity than the foaming ability of one. Porous scaffolds fabricated using nonionic surfactant Tween 80 with large foam stability exhibited higher open and total porosities, and fully interconnected porous structure with a pore size of 750-850 {mu}m.

  20. Nanoscalar modifications to polymeric tissue engineering scaffolds: Effect on cellular behavior

    NASA Astrophysics Data System (ADS)

    Powell, Heather M.

    Polymeric scaffolds provide a surface that can facilitate cell growth and tissue morphogenesis. Of particular interest is the role of nanoscalar features on cell behavior. Nanoscale topographies can be generated on two-dimensional polymeric substrates via reactive ion etching. The magnitude and morphology of the resultant surfaces can be tailored by varying the gas media, etching time and power used. Nanofibrillar surfaces were produced on polyethylene terephthalate films via oxygen-plasma etching. These nanofibrils were dimensionally similar to collagen fibers. Cells cultured on nanofibrillar surfaces were shown to have a disrupted cytoskeleton, lower levels of cell-substrate signaling, reduced strength of adhesion and an inhibition of lipid droplet coalescence. The results suggest that cells can detect nanoscalar surface topographies and alter their function in response to these environmental stimuli. While nanofibrillar surfaces can be considered pseudo-three dimensional, they cannot produce 3-D cell structures. Thus truly three dimensional scaffolds must be fabricated to determine the role of nanoscalar fibers on cell organization and function. Electrospinning was employed to generate 3-D meshes of polycaprolactone, a common biodegradable polymer. These nonwoven meshes were comprised of 500 nm fibers with an average pore size of 5 mum. In addition to forming mats of nonwoven fibers, electrospinning technology can also produce tubular scaffolds. These tubular scaffolds were seeded with human vascular smooth muscle cells and cultured for two days. After 2 days in culture, cells assumed a helical orientation around the lumen of the tube, an architecture which closely mimics natural blood vessels. Thus electrospun scaffolds facilitate the growth and organization of cell populations in a manner which imitates the natural tissue.

  1. Direct deposited porous scaffolds of calcium phosphate cement with alginate for drug delivery and bone tissue engineering.

    PubMed

    Lee, Gil-Su; Park, Jeong-Hui; Shin, Ueon Sang; Kim, Hae-Won

    2011-08-01

    This study reports the preparation of novel porous scaffolds of calcium phosphate cement (CPC) combined with alginate, and their potential usefulness as a three-dimensional (3-D) matrix for drug delivery and tissue engineering of bone. An ?-tricalcium phosphate-based powder was mixed with sodium alginate solution and then directly injected into a fibrous structure in a Ca-containing bath. A rapid hardening reaction of the alginate with Ca(2+) helps to shape the composite into a fibrous form with diameters of hundreds of micrometers, and subsequent pressing in a mold allows the formation of 3-D porous scaffolds with different porosity levels. After transformation of the CPC into a calcium-deficient hydroxyapatite phase in simulated biological fluid the scaffold was shown to retain its mechanical stability. During the process biological proteins, such as bovine serum albumin and lysozyme, used as model proteins, were observed to be effectively loaded onto and released from the scaffolds for up to more than a month, proving the efficacy of the scaffolds as a drug delivering matrix. Mesenchymal stem cells (MSCs) were isolated from rat bone marrow and then cultured on the CPC-alginate porous scaffolds to investigate the ability to support proliferation of cells and their subsequent differentiation along the osteogenic lineage. It was shown that MSCs increasingly actively populated and also permeated into the porous network with time of culture. In particular, cells cultured within a scaffold with a relatively high porosity level showed favorable proliferation and osteogenic differentiation. An in vivo pilot study of the CPC-alginate porous scaffolds after implantation into the rat calvarium for 6 weeks revealed the formation of new bone tissue within the scaffold, closing the defect almost completely. Based on these results, the newly developed CPC-alginate porous scaffolds could be potentially useful as a 3-D matrix for drug delivery and tissue engineering of bone. PMID:21539944

  2. MC3T3-E1 osteoblast attachment and proliferation on porous hydroxyapatite scaffolds fabricated with nanophase powder

    PubMed Central

    Smith, Ian O; McCabe, Laura R; Baumann, Melissa J

    2006-01-01

    Porous bone tissue engineering scaffolds were fabricated using both nano hydroxyapatite (nano HA) powder (20 nm average particle size) and micro HA powder (10 ?m average particle size), resulting in sintered scaffolds of 59 vol% porosity and 8.61.9 ?m average grain size and 72 vol% porosity and 58855 nm average grain size, respectively. Scanning electron microscopy was used to measure both the grain size and pore size. MC3T3-E1 osteoblast (OB) attachment and proliferation on both nano HA and micro HA porous scaffolds were quantified. As expected, OB cell number was greater on nano HA scaffolds compared with similarly processed micro HA scaffolds 5 days after seeding, while OB attachment did not appear greater on the nano HA scaffolds (p<0.05). PMID:17722535

  3. Porous, resorbable, fiber-reinforced scaffolds tailored for articular cartilage repair.

    PubMed

    Slivka, M A; Leatherbury, N C; Kieswetter, K; Niederauer, G G

    2001-12-01

    Porous 75:25 poly(D,L-lactide-co-glycolide) scaffolds reinforced with polyglycolide fibers were prepared with mechanical properties tailored for use in articular cartilage repair. Compression testing was performed to investigate the influence of physiological testing conditions, manufacturing method, anisotropic properties due to predominant fiber orientation, amounts of fiber reinforcement (0 to 20 wt, %), and viscoelasticity via a range of strain rates. Using the same testing modality, the mechanical properties of the scaffolds were compared with pig and goat articular cartilage. Results showed that mechanical properties of the scaffolds under physiological conditions (aqueous, 37 degrees C) were much lower than when tested under ambient conditions. The manufacturing method and anisotropy of the scaffolds significantly influenced the mechanical properties. The compressive modulus and yield strength proportionally increased with increasing fiber reinforcement up to 20%. From 0.01 to 10 mm/mm/min strain rate, the compressive modulus increased in a logarithmic fashion, and the yield strength increased in a semi-log fashion. The compressive modulus of the non-reinforced scaffolds was most similar to the pig and goat articular cartilage when compared using similar testing conditions and modality, but the improvement in yield strength using the stiffer scaffolds with fiber reinforcement could provide needed structural support for in vivo loads. PMID:11749733

  4. Bioactivity and bone healing properties of biomimetic porous composite scaffold: in vitro and in vivo studies.

    PubMed

    Veronesi, Francesca; Giavaresi, Gianluca; Guarino, Vincenzo; Raucci, Maria Grazia; Sandri, Monica; Tampieri, Anna; Ambrosio, Luigi; Fini, Milena

    2015-09-01

    Tissue engineering (TE) represents a valid alternative to traditional surgical therapies for the management of bone defects that do not regenerate spontaneously. Scaffolds, one of the most important component of TE strategy, should be biocompatible, bioactive, osteoconductive, and osteoinductive. The aim of this study was to evaluate the biological properties and bone regeneration ability of a porous poly(?-caprolactone) (PCL) scaffold, incorporating MgCO3 -doped hydroxyapatite particles, uncoated (PCL_MgCHA) or coated by apatite-like crystals via biomimetic treatment (PCL_MgCHAB). It was observed that both scaffolds are not cytotoxic and, even if cell viability was similar on both scaffolds, PCL_MgCHAB showed higher alkaline phosphatase and collagen I (COLL I) production at day 7. PCL_MgCHA induced more tumor necrosis factor-? release than PCL_MgCHAB, while osteocalcin was produced less by both scaffolds up to 7 days and no significant differences were observed for transforming growth factor-? synthesis. The percentage of new bone trabeculae growth in wide defects carried out in rabbit femoral distal epiphyses was significantly higher in PCL_MgCHAB in comparison with PCL_MgCHA at 4 weeks and even more at 12 weeks after implantation. This study highlighted the role of a biomimetic composite scaffold in bone regeneration and lays the foundations for its future employment in the clinical practice. PMID:25689266

  5. Tantalum coating on porous Ti6Al4V scaffold using chemical vapor deposition and preliminary biological evaluation.

    PubMed

    Li, Xiang; Wang, Lin; Yu, Xiaoming; Feng, Yafei; Wang, Chengtao; Yang, Ke; Su, Daniel

    2013-07-01

    Porous tantalum (Ta), produced via chemical vapor deposition (CVD) of commercially pure Ta onto a vitreous carbon, is currently available for use in orthopedic applications. However, the relatively high manufacturing cost and the incapability to produce customized implant using medical image data have limited its application to gain widespread acceptance. In this study, Ta film was deposited on porous Ti6Al4V scaffolds using CVD technique. Digital microscopy and scanning electron microscopy indicated that the Ta coating evenly covered the entire scaffold structure. X-ray diffraction analysis showed that the coating consisted of ? and ? phases of Ta. Goat mesenchymal stem cells were seeded and cultured on the Ti6Al4V scaffolds with and without coating. The tetrazolium-based colorimetric assay exhibited better cell adhesion and proliferation on Ta-coated scaffolds compared with uncoated scaffolds. The porous scaffolds were subsequently implanted in goats for 12weeks. Histological analysis revealed similar bone formation around the periphery of the coated and uncoated implants, but bone ingrowth is better within the Ta-coated scaffolds. To demonstrate the ability of producing custom implant for clinical applications via this technology, we designed and fabricated a porous Ti6Al4V scaffold with segmental mandibular shape derived from patient computerized tomography data. PMID:23623123

  6. Metallizing porous scaffolds as an alternative fabrication method for solid oxide fuel cell anodes

    NASA Astrophysics Data System (ADS)

    Ruiz-Trejo, Enrique; Atkinson, Alan; Brandon, Nigel P.

    2015-04-01

    A combination of electroless and electrolytic techniques is used to incorporate nickel into a porous Ce0.9Gd0.1O1.90 scaffold. First a porous backbone was screen printed into a YSZ electrolyte using an ink that contains sacrificial pore formers. Once sintered, the scaffold was coated with silver using Tollens' reaction followed by electrodeposition of nickel in a Watts bath. At high temperatures the silver forms droplets enabling direct contact between the gadolinia-doped ceria and nickel. Using impedance spectroscopy analysis in a symmetrical cell a total area specific resistance of 1 ?cm2 at 700 C in 97% H2 with 3% H2O was found, indicating the potential of this fabrication method for scaling up.

  7. Healing of critical-size segmental defects in rat femora using strong porous bioactive glass scaffolds.

    PubMed

    Bi, Lianxiang; Zobell, Brett; Liu, Xin; Rahaman, Mohamed N; Bonewald, Lynda F

    2014-09-01

    The repair of structural bone defects such as segmental defects in the long bones of the limbs is a challenging clinical problem. In this study, the capacity of silicate (13-93) and borate (13-93B3) bioactive glass scaffolds (porosity=47-50%) to heal critical-size segmental defects in rat femurs was evaluated and compared with autografts. Defects were implanted with 13-93 and 13-93B3 scaffolds with a grid-like microstructure (compressive strength=86 MPa and 40 MPa, respectively), 13-93B3 scaffolds with an oriented microstructure (compressive strength=32 MPa) and autografts using intramedullary fixation. Twelve weeks post-implantation, the defects were harvested and evaluated using histomorphometric analysis. The percentage of new bone in the defects implanted with the three groups of glass scaffolds (25-28%) and the total von Kossa-positive area (32-38%) were not significantly different from the autografts (new bone=38%; von Kossa-positive area=40%) (p>0.05). New blood vessel area in the defects implanted with the glass scaffolds (4-8%) and the autografts (5%) showed no significant difference among the four groups. New cartilage formed in the 13-93 grid-like scaffolds (18%) was significantly higher than in 13-93B3 grid-like scaffolds (8%) and in the autografts (8%) (p=0.02). The results indicate that these strong porous bioactive glass scaffolds are promising synthetic implants for structural bone repair. PMID:25063184

  8. High resolution x-ray imaging of dynamic solute transport in cyclically deformed porous tissue scaffolds

    NASA Astrophysics Data System (ADS)

    Op Den Buijs, Jorn; Lee, Kee-Won; Jorgensen, Steven M.; Wang, Shanfeng; Yaszemski, Michael J.; Ritman, Erik L.

    2008-03-01

    The objective was to develop a method for high-resolution imaging of dynamic solute transport in cyclically deforming porous scaffolds for tissue engineering applications. A flexible cubic scaffold with single cylindrical channel was fabricated from a biodegradable polymer blend using a combined 3D printing and injection molding technique. The scaffold was attached to the bottom of a fluid reservoir mounted underneath a compression apparatus placed inside the X-ray scanner. The scaffold was positioned with the channel axis perpendicular to the X-ray beam. The container was filled with glycerin, and a solution of the contrast agent sodium iodide (NaI) in glycerin was injected into the scaffold channel. Intervals of compression cycles (14.5 +/- 2.1 % compression at 1.0 Hz) were applied to the top face of the scaffold. After each interval the compression was temporarily paused to obtain a two-dimensional image at 20 ?m pixel resolution. A series of images was also obtained without application of the compression cycles to quantify the effect of passive diffusional removal of NaI from the channel. The average NaI concentration in the channel decreased by 82% after 300 cycles (5 min.) of compression, by 40% after 60 min. of passive removal. Spatial profiles of the NaI concentration along the channel axis indicated that compression-induced transport preferentially removed the contrast agent at the pore openings. We conclude that convective transport induced by cyclic mechanical deformation of artificial tissue scaffolds could significantly contribute to the rate and depth of nutrient transport inside the scaffold, as compared to slow diffusive transport alone.

  9. Direct Ink Writing of Highly Porous and Strong Glass Scaffolds for Load-bearing Bone Defects Repair and Regeneration

    PubMed Central

    Fu, Qiang; Saiz, Eduardo; Tomsia, Antoni P.

    2011-01-01

    The quest for synthetic materials to repair load-bearing bone lost because of trauma, cancer, or congenital bone defects requires development of porous and high-performance scaffolds with exceptional mechanical strength. However, the low mechanical strength of porous bioactive ceramic and glass scaffolds, compared with that of human cortical bone, has limited their use for these applications. In the present work, bioactive 6P53B glass scaffolds with superior mechanical strength were fabricated using a direct ink writing technique. The rheological properties of Pluronic F-127 (referred to hereafter simply as F-127) hydrogel-based inkswere optimized for the printing of features as fine as 30 ?m and of the three-dimensional scaffolds. The mechanical strength and in vitro degradation of the scaffolds were assessed in a simulated body fluid (SBF). The sintered glass scaffolds show a compressive strength (136 22 MPa) comparable to that of human cortical bone (100-150 MPa), while the porosity (60%) is in the range of that of trabecular bone (50-90%).The strength is ~100 times that of polymer scaffolds and 45 times that of ceramic and glass scaffolds with comparable porosities. Despite the strength decrease resulting from weight loss during immersion in an SBF, the value (77 MPa) is still far above that of trabecular bone after three weeks. The ability to create both porous and strong structures opens a new avenue for fabricating scaffolds for load-bearing bone defect repair and regeneration. PMID:21745606

  10. Development and Characterization of Novel Porous 3D Alginate-Cockle Shell Powder Nanobiocomposite Bone Scaffold

    PubMed Central

    Bharatham, B. Hemabarathy; Abu Bakar, Md. Zuki; Perimal, Enoch Kumar; Yusof, Loqman Mohamed; Hamid, Muhajir

    2014-01-01

    A novel porous three-dimensional bone scaffold was developed using a natural polymer (alginate/Alg) in combination with a naturally obtained biomineral (nano cockle shell powder/nCP) through lyophilization techniques. The scaffold was developed in varying composition mixture of Alg-nCP and characterized using various evaluation techniques as well as preliminary in vitro studies on MG63 human osteoblast cells. Morphological observations using SEM revealed variations in structures with the use of different Alg-nCP composition ratios. All the developed scaffolds showed a porous structure with pore sizes ideal for facilitating new bone growth; however, not all combination mixtures showed subsequent favorable characteristics to be used for biological applications. Scaffolds produced using the combination mixture of 40% Alg and 60% nCP produced significantly promising results in terms of mechanical strength, degradation rate, and increased cell proliferation rates making it potentially the optimum composition mixture of Alg-nCP with future application prospects. PMID:25110655

  11. Development and characterization of novel porous 3D alginate-cockle shell powder nanobiocomposite bone scaffold.

    PubMed

    Bharatham, B Hemabarathy; Abu Bakar, Md Zuki; Perimal, Enoch Kumar; Yusof, Loqman Mohamed; Hamid, Muhajir

    2014-01-01

    A novel porous three-dimensional bone scaffold was developed using a natural polymer (alginate/Alg) in combination with a naturally obtained biomineral (nano cockle shell powder/nCP) through lyophilization techniques. The scaffold was developed in varying composition mixture of Alg-nCP and characterized using various evaluation techniques as well as preliminary in vitro studies on MG63 human osteoblast cells. Morphological observations using SEM revealed variations in structures with the use of different Alg-nCP composition ratios. All the developed scaffolds showed a porous structure with pore sizes ideal for facilitating new bone growth; however, not all combination mixtures showed subsequent favorable characteristics to be used for biological applications. Scaffolds produced using the combination mixture of 40% Alg and 60% nCP produced significantly promising results in terms of mechanical strength, degradation rate, and increased cell proliferation rates making it potentially the optimum composition mixture of Alg-nCP with future application prospects. PMID:25110655

  12. Prolongation of the degradation period and improvement of the angiogenesis of zein porous scaffolds in vivo.

    PubMed

    Wang, Hua-Jie; Huang, Jing-Chun; Hou, Li; Miyazawa, Teruo; Wang, Jin-Ye

    2016-05-01

    Zein porous scaffolds modified with fatty acids have shown great improvement in mechanical properties and good cell compatibility in vitro, indicating the potential application as a bone tissue engineering substitute. The present study was conducted to systematically investigate whether the addition of fatty acids affects the short-term (up to 12 weeks) and long-term (up to 1 year) behaviors of scaffolds in vivo, mainly focusing on changes in the degradation period and inflammatory responses. Throughout the implantation period, no abnormal signs occurred and zein porous scaffolds modified with oleic acid showed good tolerance in rabbits, characterized by the growth of relatively more blood vessels in the scaffolds and only a slight degree of fibrosis histology. Moreover, the degradation period was prolonged from 8 months to 1 year as compared to the control. These results affirmed further that zein could be used as a new kind of natural biomaterial suitable for bone tissue engineering. PMID:26979976

  13. A facile method to determine pore size distribution in porous scaffold by using image processing.

    PubMed

    Lo Re, G; Lopresti, F; Petrucci, G; Scaffaro, R

    2015-09-01

    Image processing permits scientists to investigate morphological properties of three-dimensional structures starting from their bi-dimensional gray-scale representation. In many cases porous structure with complex architecture has to be designed in order to attempt specific properties such in the case of scaffold for tissue engineering. Traditional morphological characterization, like scanning electron microscopy, should be coupled with quantitative information such as pore size distribution (PSD) in order to get a deeper understanding of the influence of the porous structure on tissue regeneration processes and on other related applications, it is remarkable to study a quantitative analysis of porosity and of pores dimension. In this work it was developed as a software able to accomplish the segmentation of images containing pores of any geometry in a semi-automatic way with the aim to measure the PSD. Case study constituted by PLA porous scaffolds with different pore size was adopted. Results indicate that image processing methods well fit the pore size features of PLA scaffolds, overcoming the limits of the more invasive porosimetry techniques. PMID:26026425

  14. Enhanced Osteogenesis in Cocultures with Human Mesenchymal Stem Cells and Endothelial Cells on Polymeric Microfiber Scaffolds

    PubMed Central

    Gershovich, Julia G.; Dahlin, Rebecca L.; Kasper, F. Kurtis

    2013-01-01

    In this work, human mesenchymal stem cells (hMSCs) and their osteogenically precultured derivatives were directly cocultured with human umbilical vein endothelial cells (HUVECs) on electrospun three-dimensional poly(ɛ-caprolactone) microfiber scaffolds to evaluate the coculture's effect on the generation of osteogenic constructs. Specifically, cells were cultured on scaffolds for up to 3 weeks, and the cellularity, alkaline phosphatase (ALP) activity, and bone-like matrix formation were assessed. Constructs with cocultures and monocultures had almost identical cellularity after the first week, however, lower cellularity was observed in cocultures compared to monocultures during the subsequent 2 weeks of culture. Scaffolds with cocultures showed a significantly higher ALP activity, glycosaminoglycan and collagen production, as well as greater calcium deposition over the course of study compared to monocultures of hMSCs. Furthermore, the osteogenic outcome was equally robust in cocultures containing osteogenically precultured and non-precultured hMSCs. The results demonstrate that the combination of MSC and HUVEC populations within a porous scaffold material under osteogenic culture conditions is an effective strategy to promote osteogenesis. PMID:23799306

  15. Microcellular open porous monoliths for cell growth by thiol-ene polymerization of low-toxicity monomers in high internal phase emulsions.

    PubMed

    Suec, Maja; Liska, Robert; Russmller, Gnter; Kotek, Ji?i; Krajnc, Peter

    2015-02-01

    Open porous microcellular polymers with high degrees of porosity are prepared from divinyl adipate and pentaerythritol tetrakis(3-mercaptopropionate) by thiol-ene polymerization within high internal phase emulsions. The influence of monomer ratio, droplet phase volume, and emulsion stirring rate on the morphology and mechanical properties of the products is studied. The newly produced material is successfully applied as a scaffold for osteoblastic MC3T3-E1 cells in vitro, showing increased rates of cell growth compared to material prepared by standard methods. PMID:25294695

  16. In vitro cell proliferation evaluation of porous nano-zirconia scaffolds with different porosity for bone tissue engineering.

    PubMed

    Zhu, Yinglan; Zhu, Ruiqiao; Ma, Juan; Weng, Zhiqiang; Wang, Yang; Shi, Xiaolei; Li, Yicai; Yan, Xiaodong; Dong, Zhen; Xu, Jinke; Tang, Chengzhong; Jin, Lei

    2015-09-01

    The selection of scaffold materials and the optimization of scaffold morphological and mechanical properties are critical for successful bone tissue engineering. We fabricated porous scaffolds of nano-sized zirconia using a replication technique. The study aimed to explore the relationship between porosity, pore size, mechanical strength, cell adhesion, and cell proliferation in the zirconia scaffolds. Macro- and micro-structures and compressive strength were comparatively tested. Beagle bone marrow stromal cells were seeded onto the scaffolds to evaluate cell seeding efficiency and cell proliferation profile over 14 d of incubation. The zirconia scaffolds presented a complex porous structure with good interconnectivity of pores. By increasing the sinter cycles, the porosity and pore size of the scaffolds decreased, with mean values ranging from 92.7-68.0% and 830-577 ?m, respectively, accompanied by increased compressive strengths of 0.6-4.4?MPa. Cell seeding efficiency and cell proliferation over the first 7 d of incubation increased when the porosity decreased, with cell viability highest in the scaffold with a porosity of 75.2%. After 7 d of incubation, the cell proliferation increased when the porosity increased, highest in the scaffolds with a porosity of 92.7%. These results showed that the zirconia scaffold with a porosity of 75.2% possesses favorable mechanical and biological properties for future applications in bone tissue engineering. PMID:26391576

  17. Performance of PRP Associated with Porous Chitosan as a Composite Scaffold for Regenerative Medicine

    PubMed Central

    Shimojo, Andréa Arruda Martins; Perez, Amanda Gomes Marcelino; Galdames, Sofia Elisa Moraga; Brissac, Isabela Cambraia de Souza; Santana, Maria Helena Andrade

    2015-01-01

    This study aimed to evaluate the in vitro performance of activated platelet-rich plasma associated with porous sponges of chitosan as a composite scaffold for proliferation and osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells. The sponges were prepared by controlled freezing (−20, −80, or −196°C) and lyophilization of chitosan solutions (1, 2, or 3% w/v). The platelet-rich plasma was obtained from controlled centrifugation of whole blood and activated with calcium and autologous serum. The composite scaffolds were prepared by embedding the sponges with the activated platelet-rich plasma. The results showed the performance of the scaffolds was superior to that of activated platelet-rich plasma alone, in terms of delaying the release of growth factors and increased proliferation of the stem cells. The best preparation conditions of chitosan composite scaffolds that coordinated the physicochemical and mechanical properties and cell proliferation were 3% (w/v) chitosan and a −20°C freezing temperature, while −196°C favored osteogenic differentiation. Although the composite scaffolds are promising for regenerative medicine, the structures require stabilization to prevent the collapse observed after five days. PMID:25821851

  18. New paradigms in internal architecture design and freeform fabrication of tissue engineering porous scaffolds.

    PubMed

    Yoo, Dongjin

    2012-07-01

    Advanced additive manufacture (AM) techniques are now being developed to fabricate scaffolds with controlled internal pore architectures in the field of tissue engineering. In general, these techniques use a hybrid method which combines computer-aided design (CAD) with computer-aided manufacturing (CAM) tools to design and fabricate complicated three-dimensional (3D) scaffold models. The mathematical descriptions of micro-architectures along with the macro-structures of the 3D scaffold models are limited by current CAD technologies as well as by the difficulty of transferring the designed digital models to standard formats for fabrication. To overcome these difficulties, we have developed an efficient internal pore architecture design system based on triply periodic minimal surface (TPMS) unit cell libraries and associated computational methods to assemble TPMS unit cells into an entire scaffold model. In addition, we have developed a process planning technique based on TPMS internal architecture pattern of unit cells to generate tool paths for freeform fabrication of tissue engineering porous scaffolds. PMID:22721938

  19. Fabrication of Porous Hydroxyapatite Scaffolds as Artificial Bone Preform and its Biocompatibility Evaluation

    PubMed Central

    2014-01-01

    In this study, a novel porous hydroxyapatite scaffold was designed and fabricated to imitate natural bone through a multipass extrusion process. The conceptual design manifested unidirectional microchannels at the exterior part of the scaffold to facilitate rapid biomineralization and a central canal that houses the bone marrow. External and internal fissures were minimized during microwave sintering at 1,100°C. No deformation was noted, and a mechanically stable scaffold was fabricated. Detailed microstructure of the fabricated artificial bone was examined by scanning electron microscope and X-ray diffractometer, and material properties like compressive strength were evaluated. The initial biocompatibility was examined by the cell proliferation of MG-63 osteoblast-like cells using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Preliminary in vivo investigation in a rabbit model after 4 weeks and 8 weeks of implantation showed full osteointegration of the scaffold with the native tissue, and formation of bone tissue within the pore network, as examined by microcomputed tomography analyses and histological staining. Osteon-like bone microarchitecture was observed along the unidirectional channel with microblood vessels. These confirm a biomimetic regeneration model in the implanted bone scaffold, which can be used as an artificial alternative for damaged bone. PMID:24399056

  20. Osteogenic effect of controlled released rhBMP-2 in 3D printed porous hydroxyapatite scaffold.

    PubMed

    Wang, Hai; Wu, Gui; Zhang, Jing; Zhou, Kui; Yin, Bo; Su, Xinlin; Qiu, Guixing; Yang, Guang; Zhang, Xianglin; Zhou, Gang; Wu, Zhihong

    2016-05-01

    Recently, 3D printing as effective technology has been highlighted in the biomedical field. Previously, a porous hydroxyapatite (HA) scaffold with the biocompatibility and osteoconductivity has been developed by this method. However, its osteoinductivity is limited. The main purpose of this study was to improve it by the introduction of recombinant human bone morphogenetic protein-2 (rhBMP-2). This scaffold was developed by coating rhBMP-2-delivery microspheres with collagen. These synthesized scaffolds were characterized by Scanning Electron Microscopy (SEM), a delivery test in vitro, cell culture, and the experiments in vivo by a Micro-computed tomography (μCT) scan and histological evaluation of VanGieson staining. SEM results indicated the surface of scaffolds were more fit for the adhesion of hMSCs to coat collagen/rhBMP-2 microspheres. Biphasic release of rhBMP-2 could continue for more than 21 days, and keep its osteoinductivity to induce osteogenic differentiation of hMSCs in vitro. In addition, the experiments in vivo showed that the scaffold had a good bone regeneration capacity. These findings demonstrate that the HA/Collagen/Chitosan Microspheres system can simultaneously achieve localized long-term controlled release of rhBMP-2 and bone regeneration, which provides a promising route for improving the treatment of bone defects. PMID:26896655

  1. Conductive porous scaffolds as potential neural interface materials.

    SciTech Connect

    Hedberg-Dirk, Elizabeth L.; Cicotte, Kirsten N.; Buerger, Stephen P.; Reece, Gregory; Dirk, Shawn M.; Lin, Patrick P.

    2011-11-01

    Our overall intent is to develop improved prosthetic devices with the use of nerve interfaces through which transected nerves may grow, such that small groups of nerve fibers come into close contact with electrode sites, each of which is connected to electronics external to the interface. These interfaces must be physically structured to allow nerve fibers to grow through them, either by being porous or by including specific channels for the axons. They must be mechanically compatible with nerves such that they promote growth and do not harm the nervous system, and biocompatible to promote nerve fiber growth and to allow close integration with biological tissue. They must exhibit selective and structured conductivity to allow the connection of electrode sites with external circuitry, and electrical properties must be tuned to enable the transmission of neural signals. Finally, the interfaces must be capable of being physically connected to external circuitry, e.g. through attached wires. We have utilized electrospinning as a tool to create conductive, porous networks of non-woven biocompatible fibers in order to meet the materials requirements for the neural interface. The biocompatible fibers were based on the known biocompatible material poly(dimethyl siloxane) (PDMS) as well as a newer biomaterial developed in our laboratories, poly(butylene fumarate) (PBF). Both of the polymers cannot be electrospun using conventional electrospinning techniques due to their low glass transition temperatures, so in situ crosslinking methodologies were developed to facilitate micro- and nano-fiber formation during electrospinning. The conductivity of the electrospun fiber mats was controlled by controlling the loading with multi-walled carbon nanotubes (MWNTs). Fabrication, electrical and materials characterization will be discussed along with initial in vivo experimental results.

  2. Facile fabrication of hierarchical porous resins via high internal phase emulsion and polymeric porogen

    NASA Astrophysics Data System (ADS)

    Ma, Libin; Luo, Xiaogang; Cai, Ning; Xue, Yanan; Zhu, San; Fu, Zhen; Yu, Faquan

    2014-06-01

    To achieve the dual features of fast oil absorption rate and high oil absorbency for the practical application in emergency treatment of spilled chemical pollutants, hierarchical porous resins were synthesized. The polymerization of high internal phase emulsion was applied to fabricate the porous structure for the purpose of high oil absorbency. Polymeric porogens were proposed to adjust the second-order or interconnected pore structure for fast oil absorption rate. SEM revealed the hierarchical porous structure. Molecular weight and dose of polymeric porogen were investigated for the effect on the formation of porous structure and absorption features. Optimized resins have 31.5 g/g or 17.1 g/g absorbency for chloroform and toluene, respectively, and only 5 min is needed to reach their saturation absorption. Besides, the porous resins demonstrated high oil retention under pressure. The absorption/desorption cycling results revealed the high repeatability of recovered resins. All these tests predicted the potential applications of porous resins of this kind particularly in the emergency treatment of oil and chemical pollution.

  3. Mechanical properties of highly porous PDLLA/Bioglass composite foams as scaffolds for bone tissue engineering.

    PubMed

    Blaker, J J; Maquet, V; Jrme, R; Boccaccini, A R; Nazhat, S N

    2005-11-01

    This study developed highly porous degradable composites as potential scaffolds for bone tissue engineering. These scaffolds consisted of poly-D,L-lactic acid filled with 2 and 15 vol.% of 45S5 Bioglass particles and were produced via thermally induced solid-liquid phase separation and subsequent solvent sublimation. The scaffolds had a bimodal and anisotropic pore structure, with tubular macro-pores of approximately 100 microm in diameter, and with interconnected micro-pores of approximately 10-50 microm in diameter. Quasi-static and thermal dynamic mechanical analysis carried out in compression along with thermogravimetric analysis was used to investigate the effect of Bioglass on the properties of the foams. Quasi-static compression testing demonstrated mechanical anisotropy concomitant with the direction of the macro-pores. An analytical modelling approach was applied, which demonstrated that the presence of Bioglass did not significantly alter the porous architecture of these foams and reflected the mechanical anisotropy which was congruent with the scanning electron microscopy investigation. This study found that the Ishai-Cohen and Gibson-Ashby models can be combined to predict the compressive modulus of the composite foams. The modulus and density of these complex foams are related by a power-law function with an exponent between 2 and 3. PMID:16701845

  4. Direct fabrication of high-resolution three-dimensional polymeric scaffolds using electrohydrodynamic hot jet plotting

    NASA Astrophysics Data System (ADS)

    Wei, Chuang; Dong, Jingyan

    2013-02-01

    This paper presents the direct three-dimensional (3D) fabrication of polymer scaffolds with sub-10 m structures using electrohydrodynamic jet (EHD-jet) plotting of melted thermoplastic polymers. Traditional extrusion-based fabrication approaches of 3D periodic porous structures are very limited in their resolution, due to the excessive pressure requirement for extruding highly viscous thermoplastic polymers. EHD-jet printing has become a high-resolution alternative to other forms of nozzle deposition-based fabrication approaches by generating micro-scale liquid droplets or a fine jet through the application of a large electrical voltage between the nozzle and the substrate. In this study, we successfully apply EHD-jet plotting technology with melted biodegradable polymer (polycaprolactone, or PCL) for the fabrication of 2D patterns and 3D periodic porous scaffold structures in potential tissue engineering applications. Process conditions (e.g. electrical voltage, pressure, plotting speed) have been thoroughly investigated to achieve reliable jet printing of fine filaments. We have demonstrated for the first time that the EHD-jet plotting process is capable of the fabrication of 3D periodic structures with sub-10 m resolution, which has great potential in advanced biomedical applications, such as cell alignment and guidance.

  5. Compensation of spherical aberration influences for two-photon polymerization patterning of large 3D scaffolds

    NASA Astrophysics Data System (ADS)

    Stichel, T.; Hecht, B.; Houbertz, R.; Sextl, G.

    2015-10-01

    Two-photon polymerization using femtosecond laser pulses at a wavelength of 515 nm is used for three-dimensional patterning of photosensitive, biocompatible inorganic-organic hybrid polymers (ORMOCERs). In order to fabricate millimeter-sized biomedical scaffold structures with interconnected pores, medium numerical aperture air objectives with long working distances are applied which allow voxel lengths of several micrometers and thus the solidification of large scaffolds in an adequate time. It is demonstrated that during processing the refraction of the focused laser beam at the air/material interface leads to strong spherical aberration which decreases the peak intensity of the focal point spread function along with shifting and severely extending the focal region in the direction of the beam propagation. These effects clearly decrease the structure integrity, homogeneity and the structure details and therefore are minimized by applying a positioning and laser power adaptation throughout the fabrication process. The results will be discussed with respect to the resulting structural homogeneity and its application as biomedical scaffold.

  6. Polymeric electrospun scaffolds: neuregulin encapsulation and biocompatibility studies in a model of myocardial ischemia.

    PubMed

    Simn-Yarza, Teresa; Rossi, Angela; Heffels, Karl-Heinz; Prsper, Felipe; Groll, Jrgen; Blanco-Prieto, Maria J

    2015-05-01

    Cardiovascular disease represents one of the major health challenges in modern times and is the number one cause of death globally. Thus, numerous studies are under way to identify effective cell- and/or growth factor (GF)-based therapies for repairing damaged cardiac tissue. In this regard, improving the engraftment or survival of regenerative cells and prolonging GF exposure have become fundamental goals in advancing these therapeutic approaches. Biomaterials have emerged as innovative scaffolds for the delivery of both cells and proteins in tissue engineering applications. In the present study, electrospinning was used to generate smooth homogenous polymeric fibers, which consisted of a poly(lactic-co-glycolic acid) (PLGA)/NCO-sP(EO-stat-PO) polymer blend encapsulating the cardioactive GF, Neuregulin-1 (Nrg). We evaluated the biocompatibility and degradation of this Nrg-containing biomaterial in a rat model of myocardial ischemia. Histological analysis revealed the presence of an initial acute inflammatory response after implantation, which was followed by a chronic inflammatory phase, characterized by the presence of giant cells. Notably, the scaffold remained in the heart after 3 months. Furthermore, an increase in the M2:M1 macrophage ratio following implantation suggested the induction of constructive tissue remodeling. Taken together, the combination of Nrg-encapsulating scaffolds with cells capable of inducing cardiac regeneration could represent an ambitious and promising therapeutic strategy for repairing diseased or damaged myocardial tissue. PMID:25707939

  7. Porous Shape Memory Polymers

    PubMed Central

    Hearon, Keith; Singhal, Pooja; Horn, John; Small, Ward; Olsovsky, Cory; Maitland, Kristen C.; Wilson, Thomas S.; Maitland, Duncan J.

    2013-01-01

    Porous shape memory polymers (SMPs) include foams, scaffolds, meshes, and other polymeric substrates that possess porous three-dimensional macrostructures. Porous SMPs exhibit active structural and volumetric transformations and have driven investigations in fields ranging from biomedical engineering to aerospace engineering to the clothing industry. The present review article examines recent developments in porous SMPs, with focus given to structural and chemical classification, methods of characterization, and applications. We conclude that the current body of literature presents porous SMPs as highly interesting smart materials with potential for industrial use. PMID:23646038

  8. 3D Printing Bioceramic Porous Scaffolds with Good Mechanical Property and Cell Affinity

    PubMed Central

    Chang, Chih-Hao; Lin, Chih-Yang; Liu, Fwu-Hsing; Chen, Mark Hung-Chih; Lin, Chun-Pin; Ho, Hong-Nerng; Liao, Yunn-Shiuan

    2015-01-01

    Artificial bone grafting is widely used in current orthopedic surgery for bone defect problems. Unfortunately, surgeons remain unsatisfied with the current commercially available products. One of the major complaints is that these products cannot provide sufficient mechanical strength to support the human skeletal structure. In this study, we aimed to develop a bone scaffold with better mechanical property and good cell affinity by 3D printing (3DP) techniques. A self-developed 3D printer with laser-aided gelling (LAG) process was used to fabricate bioceramic scaffolds with inter-porous structures. To improve the mechanical property of the bioceramic parts after heating, CaCO3 was added to the silica ceramic slurry. CaCO3 was blended into a homogenous SiO2-sol dispersion at weight ratios varying from 0/100 to 5/95 to 9/91 (w/w). Bi-component CaCO3/SiO2-sol was prepared as a biocomposite for the 3DP scaffold. The well-mixed biocomposite was used to fabricate the bioceramic green part using the LAG method. The varied scaffolds were sintered at different temperatures ranging from 900 to 1500°C, and the mechanical property was subsequently analyzed. The scaffolds showed good property with the composite ratio of 5:95 CaCO3:SiO2 at a sintering temperature of 1300°C. The compressive strength was 47 MPa, and the porosity was 34%. The topography of the sintered 3DP bioceramic scaffold was examined by SEM, EDS and XRD. The silica bioceramic presented no cytotoxicity and good MG-63 osteoblast-like cell affinity, demonstrating good biocompatibility. Therefore, the new silica biocomposite is viable for fabricating 3DP bone bioceramics with improved mechanical property and good cell affinity. PMID:26618362

  9. 3D Printing Bioceramic Porous Scaffolds with Good Mechanical Property and Cell Affinity.

    PubMed

    Chang, Chih-Hao; Lin, Chih-Yang; Liu, Fwu-Hsing; Chen, Mark Hung-Chih; Lin, Chun-Pin; Ho, Hong-Nerng; Liao, Yunn-Shiuan

    2015-01-01

    Artificial bone grafting is widely used in current orthopedic surgery for bone defect problems. Unfortunately, surgeons remain unsatisfied with the current commercially available products. One of the major complaints is that these products cannot provide sufficient mechanical strength to support the human skeletal structure. In this study, we aimed to develop a bone scaffold with better mechanical property and good cell affinity by 3D printing (3DP) techniques. A self-developed 3D printer with laser-aided gelling (LAG) process was used to fabricate bioceramic scaffolds with inter-porous structures. To improve the mechanical property of the bioceramic parts after heating, CaCO3 was added to the silica ceramic slurry. CaCO3 was blended into a homogenous SiO2-sol dispersion at weight ratios varying from 0/100 to 5/95 to 9/91 (w/w). Bi-component CaCO3/SiO2-sol was prepared as a biocomposite for the 3DP scaffold. The well-mixed biocomposite was used to fabricate the bioceramic green part using the LAG method. The varied scaffolds were sintered at different temperatures ranging from 900 to 1500C, and the mechanical property was subsequently analyzed. The scaffolds showed good property with the composite ratio of 5:95 CaCO3:SiO2 at a sintering temperature of 1300C. The compressive strength was 47 MPa, and the porosity was 34%. The topography of the sintered 3DP bioceramic scaffold was examined by SEM, EDS and XRD. The silica bioceramic presented no cytotoxicity and good MG-63 osteoblast-like cell affinity, demonstrating good biocompatibility. Therefore, the new silica biocomposite is viable for fabricating 3DP bone bioceramics with improved mechanical property and good cell affinity. PMID:26618362

  10. Hydrothermal fabrication of hydroxyapatite/chitosan/carbon porous scaffolds for bone tissue engineering.

    PubMed

    Long, Teng; Liu, Yu-Tai; Tang, Sha; Sun, Jin-Liang; Guo, Ya-Ping; Zhu, Zhen-An

    2014-11-01

    Porous carbon fiber felts (PCFFs) have great applications in orthopedic surgery because of the strong mechanical strength, low density, high stability, and porous structure, but they are biologically inert. To improve their biological properties, we developed, for the first time, the hydroxyapatite (HA)/chitosan/carbon porous scaffolds (HCCPs). HA/chitosan nanohybrid coatings have been fabricated on PCFFs according to the following stages: (i) deposition of chitosan/calcium phosphate precursors on PCFFs; and (ii) hydrothermal transformation of the calcium phosphate precursors in chitosan matrix into HA nanocrystals. The scanning electron microscopy images indicate that PCFFs are uniformly covered with elongated HA nanoplates and chitosan, and the macropores in PCFFs still remain. Interestingly, the calcium-deficient HA crystals exist as plate-like shapes with thickness of 10-18 nm, width of 30-40 nm, and length of 80-120 nm, which are similar to the biological apatite. The HA in HCCPs is similar to the mineral of natural bone in chemical composition, crystallinity, and morphology. As compared with PCFFs, HCCPs exhibit higher in vitro bioactivity and biocompatibility because of the presence of the HA/chitosan nanohybrid coatings. HCCPs not only promote the formation of bone-like apatite in simulated body fluid, but also improve the adhesion, spreading, and proliferation of human bone marrow stromal cells. Hence, HCCPs have great potentials as scaffold materials for bone tissue engineering and implantation. PMID:24687547

  11. Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review.

    PubMed

    Wang, Xiaojian; Xu, Shanqing; Zhou, Shiwei; Xu, Wei; Leary, Martin; Choong, Peter; Qian, M; Brandt, Milan; Xie, Yi Min

    2016-03-01

    One of the critical issues in orthopaedic regenerative medicine is the design of bone scaffolds and implants that replicate the biomechanical properties of the host bones. Porous metals have found themselves to be suitable candidates for repairing or replacing the damaged bones since their stiffness and porosity can be adjusted on demands. Another advantage of porous metals lies in their open space for the in-growth of bone tissue, hence accelerating the osseointegration process. The fabrication of porous metals has been extensively explored over decades, however only limited controls over the internal architecture can be achieved by the conventional processes. Recent advances in additive manufacturing have provided unprecedented opportunities for producing complex structures to meet the increasing demands for implants with customized mechanical performance. At the same time, topology optimization techniques have been developed to enable the internal architecture of porous metals to be designed to achieve specified mechanical properties at will. Thus implants designed via the topology optimization approach and produced by additive manufacturing are of great interest. This paper reviews the state-of-the-art of topological design and manufacturing processes of various types of porous metals, in particular for titanium alloys, biodegradable metals and shape memory alloys. This review also identifies the limitations of current techniques and addresses the directions for future investigations. PMID:26773669

  12. Porous polycaprolactone/nanohydroxyapatite tissue engineering scaffolds fabricated by combining NaCl and PEG as co-porogens: structure, property, and chondrocyte-scaffold interaction in vitro.

    PubMed

    Liu, Li; Wang, Yuanyuan; Guo, Shengrong; Wang, Zhenyu; Wang, Wei

    2012-05-01

    In this study, porous polycaprolactone/nanohydroxyapatite (PCL/nHA) composite scaffolds were fabricated using a modified melt-molding/leaching technique, by the combination of salt particulate (NaCl) and water-soluble polymer (PEG) as co-porogens. The porogens were kept at a constant proportion of 70% in the blends but varied in the NaCl/PEG ratio and the PEG variety to generate PCL/nHA scaffolds with various pore architectures. The resultant composite scaffolds were investigated on their morphologies, physicochemical properties, mechanical properties, and in vitro degradation. The cell-scaffold interactions were evaluated in vitro using chondrocyte. Generally, the PCL/nHA scaffolds exhibited multimodal pore morphologies consisting of macropores and interconnected micropores, created by the extraction of NaCl particulate and continuous PEG phase. The evolution of porogens led to much effect on the overall pore architecture of the scaffolds; subsequently, their physiochemical and mechanical properties and degradation behaviors, as well as the cell binding and proliferation. The PCL/nHA scaffold prepared from NaCl/PEG 4000 (20/50) presented more macropores (>50 μm) with interconnectivity and showed higher strength and improved bioactivity than the others. All of these results suggest promising potentials of PCL/nHA scaffolds developed in this study desired for cartilage tissue engineering. PMID:22447487

  13. Surface functionalization of 3D glass-ceramic porous scaffolds for enhanced mineralization in vitro

    NASA Astrophysics Data System (ADS)

    Ferraris, Sara; Vitale-Brovarone, Chiara; Bretcanu, Oana; Cassinelli, Clara; Vern, Enrica

    2013-04-01

    Bone reconstruction after tissue loosening due to traumatic, pathological or surgical causes is in increasing demand. 3D scaffolds are a widely studied solution for supporting new bone growth. Bioactive glass-ceramic porous materials can offer a three-dimensional structure that is able to chemically bond to bone. The ability to surface modify these devices by grafting biologically active molecules represents a challenge, with the aim of stimulating physiological bone regeneration with both inorganic and organic signals. In this research work glass ceramic scaffolds with very high mechanical properties and moderate bioactivity have been functionalized with the enzyme alkaline phosphatase (ALP). The material surface was activated in order to expose hydroxyl groups. The activated surface was further grafted with ALP both via silanization and also via direct grafting to the surface active hydroxyl groups. Enzymatic activity of grafted samples were measured by means of UV-vis spectroscopy before and after ultrasonic washing in TRIS-HCl buffer solution. In vitro inorganic bioactivity was investigated by soaking the scaffolds after the different steps of functionalization in a simulated body fluid (SBF). SEM observations allowed the monitoring of the scaffold morphology and surface chemical composition after soaking in SBF. The presence of ALP enhanced the in vitro inorganic bioactivity of the tested material.

  14. 3D printing of porous hydroxyapatite scaffolds intended for use in bone tissue engineering applications.

    PubMed

    Cox, Sophie C; Thornby, John A; Gibbons, Gregory J; Williams, Mark A; Mallick, Kajal K

    2015-02-01

    A systematic characterisation of bone tissue scaffolds fabricated via 3D printing from hydroxyapatite (HA) and poly(vinyl)alcohol (PVOH) composite powders is presented. Flowability of HA:PVOH precursor materials was observed to affect mechanical stability, microstructure and porosity of 3D printed scaffolds. Anisotropic behaviour of constructs and part failure at the boundaries of interlayer bonds was highlighted by compressive strength testing. A trade-off between the ability to facilitate removal of PVOH thermal degradation products during sintering and the compressive strength of green parts was revealed. The ultimate compressive strength of 55% porous green scaffolds printed along the Y-axis and dried in a vacuum oven for 6h was 0.88 0.02 MPa. Critically, the pores of 3D printed constructs could be user designed, ensuring bulk interconnectivity, and the imperfect packing of powder particles created an inherent surface roughness and non-designed porosity within the scaffold. These features are considered promising since they are known to facilitate osteoconduction and osteointegration in-vivo. Characterisation techniques utilised in this study include two funnel flow tests, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), compressive strength testing and computed tomography (CT). PMID:25492194

  15. Direct writing of porous tissue scaffolds based on Vaseline-doped hydroxyapatite inks

    NASA Astrophysics Data System (ADS)

    Li, Ya-Yun; Li, Long-Tu; Li, Bo

    2015-05-01

    A novel type of 40 vol.% hydroxyapatite (HAp), Ca10(PO4)6(OH)2, suspension doped with Vaseline was developed, and porous three-dimensional (3D) scaffolds were fabricated by using a direct ink writing (DIW) method. The preparation of the HAp inks and the principles of the DIW technique were investigated. The microporosity of the scaffold wall increased after introducing the Vaseline, whereas macroporosity can be produced by varying the DIW technique. The micromorphology test results show that the samples sintered at 1150C for 2 h formed ceramics with a set amount of pores, which benefit cell growth by providing more locations for cells to attach and proliferate. Under a microscope, the proliferations of human liver carcinoma cell line (HepG2) cells can be observed on the 3D HAp scaffolds. The DIW method has the advantages of a rapid process, ease of design and high precision control, potentially inspiring the design and application of biomaterials and scaffolds.

  16. Characterization of Silk Fibroin/Chitosan 3D Porous Scaffold and In Vitro Cytology

    PubMed Central

    Zeng, Shuguang; Liu, Lei; Shi, Yong; Qiu, Junqi; Fang, Wei; Rong, Mingdeng; Guo, Zehong; Gao, Wenfeng

    2015-01-01

    Bone tissue engineering is a powerful tool to treat bone defects caused by trauma, infection, tumors and other factors. Both silk fibroin (SF) and chitosan (CS) are non-toxic and have good biocompatibility, but are poor biological scaffolds when used alone. In this study, the microscopic structure and related properties of SF/CS composite scaffolds with different component ratios were examined. The scaffold material most suitable for osteoblast growth was determined, and these results offer an experimental basis for the future reconstruction of bone defects. First, via freeze-drying and chemical crosslinking methods, SF/CS composites with different component ratios were prepared and their structure was characterized. Changes in the internal structure of the SF and CS mixture were observed, confirming that the mutual modification between the two components was complete and stable. The internal structure of the composite material was porous and three-dimensional with a porosity above 90%. We next studied the pore size, swelling ratio, water absorption ratio, degradation and in vitro cell proliferation. For the 40% SF-60% CS group, the pore size of the scaffold was suitable for the growth of osteoblasts, and the rate of degradation was steady. This favors the early adhesion, growth and proliferation of MG-63 cells. In addition to good biocompatibility and satisfactory cell affinity, this material promotes the secretion of extracellular matrix materials by osteoblasts. Thus, 40% SF-60% CS is a good material for bone tissue engineering. PMID:26083846

  17. Biomechanical stability of novel mechanically adapted open-porous titanium scaffolds in metatarsal bone defects of sheep.

    PubMed

    Wieding, Jan; Lindner, Tobias; Bergschmidt, Philipp; Bader, Rainer

    2015-04-01

    Open-porous titanium scaffolds for large segmental bone defects offer advantages like early weight-bearing and limited risk of implant failure. The objective of this experimental study was to determine the biomechanical behavior of novel open-porous titanium scaffolds with mechanical-adapted properties invivo. Two types of the custom-made, open-porous scaffolds made of Ti6Al4V (Young's modulus: 6-8GPa and different pore sizes) were implanted into a 20mm segmental defect in the mid-diaphysis of the metatarsus of sheep, and were stabilized with an osteosynthesis plate. After 12 and 24 weeks postoperatively, torsional testing was performed on the implanted bone and compared to the contralateral non-treated side. Maximum torque, maximum angle, torsional stiffness, fracture energy, shear modulus and shear stress were investigated. Furthermore, bone mineral density (BMD) of the newly formed bone was determined. Mechanical loading capabilities for both scaffolds were similar and about 50% after 12 weeks (e.g., max. torque of approximately 20Nm). A further increase after 24 weeks was found for most of the investigated parameters. Results for torsional stiffness and shear modulus as well as bone formation depended on the type of scaffold.Increased BMD after 24 weeks was found for one scaffold type but remained constant for the other one. The present data showed the capability of mechanically adapted open-porous titanium scaffolds to function as bone scaffolds for large segmental defects and the influence of the scaffold's stiffness. A further increase in the biomechanical stability can be assumed for longer observation periods of greater than six months. PMID:25678114

  18. Vascularization of hollow channel-modified porous silk scaffolds with endothelial cells for tissue regeneration.

    PubMed

    Zhang, Wenjie; Wray, Lindsay S; Rnjak-Kovacina, Jelena; Xu, Ling; Zou, Duohong; Wang, Shaoyi; Zhang, Maolin; Dong, Jiachen; Li, Guanglong; Kaplan, David L; Jiang, Xinquan

    2015-07-01

    Despite the promise for stem cell-based tissue engineering for regenerative therapy, slow and insufficient vascularization of large tissue constructs negatively impacts the survival and function of these transplanted cells. A combination of channeled porous silk scaffolds and prevascularization with endothelial cells was investigated to test the ability of this tissue engineering strategy to support rapid and extensive vascularization process. We report that hollow channels promote invitro prevascularization by facilitating endothelial cell growth, VEGF secretion, and capillary-like tube formation. When implanted invivo, the pre-established vascular networks in the hollow channel scaffolds anastomose with host vessels and exhibit accelerated vascular infiltration throughout the whole tissue construct, which provides timely and sufficient nutrients to ensure the survival of the transplanted stem cells. This tissue engineering strategy can promote the effective application of stem cell-based regeneration to improve future clinical applications. PMID:25934280

  19. In vitro and in vivo evaluations of 3D porous TCP-coated and non-coated alumina scaffolds.

    PubMed

    Kim, Young-Hee; Anirban, Jyoti M; Song, Ho-Yeon; Seo, Hyung-Seok; Lee, Byong-Taek

    2011-02-01

    Both tricalcium phosphate (TCP) and alumina have been extensively studied and shown to have high biocompatibility. Tricalcium phosphate has improved biodegradability and a higher solubility than hydroxyapatite. In contrast, alumina (Al(2)O(3)) is almost completely inert at physiological conditions and has been used as a biomaterial due to its wear resistance, high surface finish, and excellent hardness. Thus, the combination of these two implants would result in greater biocompatibility and phenotype maintenance. A polyurethane (PU) foam replica method was employed in this study to coat TCP on an alumina scaffold. The TCP-coated alumina scaffold was then sintered to generate a porous surface morphology. The pore sizes obtained using this approach ranged between 100-600 m, which is ideal for cellular proliferation. The cytotoxicity, cellular proliferation, differentiation, and ECM deposition on the coated scaffold resulted in longer-term viability of osteogenic markers compared to the non-coated scaffold. Moreover, the osteogenic properties of porous TCP-coated Al(2)O(3) scaffolds were reported in this study using rabbit models. The TCP/Al(2)O( 3) scaffold and control Al(2)O(3) scaffolds were implanted in the rabbit femur. The bone tissue response was analyzed with micro-computed tomography (micro CT) at 12 and 24 weeks after implantation. The porous scaffolds exhibited favorable hard and soft tissue responses at both time points. At 24 weeks, a three-fold increase in bone tissue ingrowth was observed in defects containing TCP-coated Al(2)O(3) scaffolds compared to control Al(2)O(3) scaffolds. PMID:20207781

  20. Ice-template-induced silk fibroin-chitosan scaffolds with predefined microfluidic channels and fully porous structures.

    PubMed

    Mao, Mao; He, Jiankang; Liu, Yaxiong; Li, Xiao; Li, Dichen

    2012-07-01

    Scaffold-based tissue engineering has made great progress in fabricating relatively simple tissues. One of the major challenges in creating thick complex organs is to achieve sufficient nutrient supply as well as uniform cell distribution in a three-dimensional (3D) scaffold. Here we employed microstructured ice templates to fabricate silk fibroin-chitosan (SF-CS) scaffolds with predefined microfluidic channels, open-pore surface and oriented porous structures. The effects of these structural organizations in ice-template-induced (ITI) scaffolds on nutrient delivery, cell seeding as well as cell growth were well investigated in comparison with that of polydimethylsiloxane-template-induced scaffolds. The ITI scaffolds exhibited better structural properties in promoting mass transport, facilitating uniform cell distribution and growth. The ITI scaffolds uniformly seeded with living cells could be further rolled up to form a thick tissue-engineered construct with predefined microfluidic channels. We envision that our ITI scaffolds can be potentially used to engineer thick prevascularized organs when the oriented porous structures are uniformly seeded with primary cells and the predefined microfluidic channels are incorporated with endothelial cells. PMID:22269914

  1. Chondrogenic regeneration using bone marrow clots and a porous polycaprolactone-hydroxyapatite scaffold by three-dimensional printing.

    PubMed

    Yao, Qingqiang; Wei, Bo; Liu, Nancy; Li, Chenshuang; Guo, Yang; Shamie, Arya Nick; Chen, James; Tang, Cheng; Jin, Chengzhe; Xu, Yan; Bian, Xiuwu; Zhang, Xinli; Wang, Liming

    2015-04-01

    Scaffolds play an important role in directing three-dimensional (3D) cartilage regeneration. Our recent study reported the potential advantages of bone marrow clots (MC) in promoting extracellular matrix (ECM) scaffold chondrogenic regeneration. The aim of this study is to build a new scaffold for MC, with improved characteristics in mechanics, shaping, and biodegradability, compared to our previous study. To address this issue, this study prepared a 3D porous polycaprolactone (PCL)-hydroxyapatite (HA) scaffold combined with MC (Group A), while the control group (Group B) utilized a bone marrow stem cell seeded PCL-HA scaffold. The results of in vitro cultures and in vivo implantation demonstrated that although an initial obstruction of nutrient exchange caused by large amounts of fibrin and erythrocytes led to a decrease in the ratio of live cells in Group A, these scaffolds also showed significant improvements in cell adhesion, proliferation, and chondrogenic differentiation with porous recanalization in the later culture, compared to Group B. After 4 weeks of in vivo implantation, Group A scaffolds have a superior performance in DNA content, Sox9 and RunX2 expression, cartilage lacuna-like cell and ECM accumulation, when compared to Group B. Furthermore, Group A scaffold size and mechanics were stable during in vitro and in vivo experiments, unlike the scaffolds in our previous study. Our results suggest that the combination with MC proved to be a highly efficient, reliable, and simple new method that improves the biological performance of 3D PCL-HA scaffold. The MC-PCL-HA scaffold is a candidate for future cartilage regeneration studies. PMID:25530453

  2. Fabrication of three-dimensional porous scaffold based on collagen fiber and bioglass for bone tissue engineering.

    PubMed

    Long, Teng; Yang, Jun; Shi, Shan-Shan; Guo, Ya-Ping; Ke, Qin-Fei; Zhu, Zhen-An

    2015-10-01

    An ideal scaffold for bone tissue engineering should have interconnected porous structure, good biocompatibility, and mechanical properties well-matched with natural bones. Collagen is the key component in the extracellular matrix (ECM) of natural bones, and plays an important role in bone regeneration. The biological activity of collagen has promoted it to be an advantageous biomaterial for bone tissue engineering; however, the mechanical properties of these scaffolds are insufficient and the porous structures are not stable in the wet state. An effective strategy to solve this problem is to fabricate a hybrid scaffold of biologically derived and synthetic material, which have the necessary bioactivity and mechanical stability needed for bone synthesis. In this work, a three-dimensional macroporous bone scaffold based on collagen (CO) fiber and bioglass (BG) is fabricated by a slurry-dipping technique, and its relevant mechanical and biological properties are evaluated. The CO/BG scaffold is interconnected with a porosity of 81 ± 4.6% and pore size of 40-200 μm. Compared with CO scaffold, water absorption value of CO/BG scaffold decreases greatly from 889% to 52%, which significantly alleviates the swelling behavior of collagen and improves the stability of scaffold structure. The CO/BG scaffold has a compression strength of 5.8 ± 1.6 MPa and an elastic modulus of 0.35 ± 0.01 Gpa, which are well-matched with the mechanical properties of trabecular bones. In vitro cell assays demonstrate that the CO/BG scaffold has good biocompatibility to facilitate the spreading and proliferation of human bone marrow stromal cells. Hence, the CO/BG scaffold is promising for bone tissue engineering application. PMID:25430707

  3. Strategies for the chemical analysis of highly porous bone scaffolds using secondary ion mass spectrometry.

    PubMed

    Wang, Daming; Poologasundarampillai, Gowsihan; van den Bergh, Wouter; Chater, Richard J; Kasuga, Toshihiro; Jones, Julian R; McPhail, David S

    2014-02-01

    Understanding the distribution of critical elements (e.g. silicon and calcium) within silica-based bone scaffolds synthesized by different methods is central to the optimization of these materials. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used to determine this information due to its very high surface sensitivity and its ability to map all the elements and compounds in the periodic table with high spatial resolution. The SIMS image data can also be combined with depth profiles to construct three-dimensional chemical maps. However, the scaffolds have interconnected pore networks, which are very challenging structures for the SIMS technique. To overcome this problem two experimental methodologies have been developed. The first method involved the use of the focused ion beam technique to obtain clear images of the regions of interest and subsequently mark them by introducing fiducial marks; the samples were then analysed using the ToF-SIMS technique to yield the chemical analyses of the regions of interest. The second method involved impregnating the pores using a suitable reagent so that a flat surface could be achieved, and this was followed by secondary ion mapping and 3D chemical imaging with ToF-SIMS. The samples used in this work were sol-gel 70S30C foam and electrospun fibres and calcium-containing silica/gelatin hybrid scaffolds. The results demonstrate the feasibility of both these experimental methodologies and indicate that these methods can provide an opportunity to compare various artificial bone scaffolds, which will be of help in improving scaffold synthesis and processing routes. The techniques are also transferable to many other types of porous material. PMID:24457328

  4. Stress-strain analysis of porous scaffolds made from titanium alloys synthesized via SLS method

    NASA Astrophysics Data System (ADS)

    Shishkovsky, I.

    2009-09-01

    A layer-by-layer selective laser sintering (SLS) technology seems to be greatly promising for solving the plastic surgery problems, particularly those pertaining to the facial reconstruction. Made from titanium-based alloys (titanium or nitinol, i.e. NiTi-intermetallic phase), the porous scaffolds for cranioplasty are an efficient tool for rectifying the face defects and for the dental orthopedic surgery. The progress in the oral surgery and teeth implantation is caused by the problem of an osteointegration on the one hand, and by achievements of the implant synthesis techniques, on the other hand. An important problem thereby is a profound study of the stress-strain behavior of porous implants under the masticatory load or pressure. In the present study the ways for the optimization of the porous implant structural and strength properties as the function of the laser synthesis parameters are described. The finite element approach (ANSYS) was used here for a complex dowel description and numerical simulations. In order to evaluate the processes in the porous implant under the external loading, a CAD 3D model was built for different internal and external configurations of the implant and/or initial shape of powdered particles. The stress-strain dependences were calculated that displayed the irregularity of the stress distribution by the implant volume in the bone tissue. Most of the values are concentrated in places of object contact.

  5. Improved dimensional stability with bioactive glass fibre skeleton in poly(lactide-co-glycolide) porous scaffolds for tissue engineering.

    PubMed

    Haaparanta, Anne-Marie; Uppstu, Peter; Hannula, Markus; Ell, Ville; Rosling, Ari; Kellomki, Minna

    2015-11-01

    Bone tissue engineering requires highly porous three-dimensional (3D) scaffolds with preferable osteoconductive properties, controlled degradation, and good dimensional stability. In this study, highly porous 3D poly(d,l-lactide-co-glycolide) (PLGA) - bioactive glass (BG) composites (PLGA/BG) were manufactured by combining highly porous 3D fibrous BG mesh skeleton with porous PLGA in a freeze-drying process. The 3D structure of the scaffolds was investigated as well as in vitro hydrolytic degradation for 10weeks. The effect of BG on the dimensional stability, scaffold composition, pore structure, and degradation behaviour of the scaffolds was evaluated. The composites showed superior pore structure as the BG fibres inhibited shrinkage of the scaffolds. The BG was also shown to buffer the acidic degradation products of PLGA. These results demonstrate the potential of these PLGA/BG composites for bone tissue engineering, but the ability of this kind of PLGA/BG composites to promote bone regeneration will be studied in forthcoming in vivo studies. PMID:26249615

  6. Influences of environmental factors on bacterial extracellular polymeric substances production in porous media

    NASA Astrophysics Data System (ADS)

    Xia, Lu; Zheng, Xilai; Shao, Haibing; Xin, Jia; Peng, Tao

    2014-11-01

    Bioclogging of natural porous media occurs frequently under a wide range of conditions. It may influence the performance of permeable reactive barrier and constructed wetland. It is also one of the factors that determine the effect of artificial groundwater recharge and in situ bioremediation process. In this study, a series of percolation column experiments were conducted to simulate bioclogging process in porous media. The predominant bacteria in porous media which induced clogging were identified to be Methylobacterium, Janthinobacterium, Yersinia, Staphylococcus and Acidovorax, most of which had been shown to effectively produce viscous extracellular polymeric substances (EPS). The column in which EPS production was maximized also coincided with the largest reduction in saturated hydraulic conductivity of porous media. In addition, carbon concentration was the most significant factor to affect polysaccharide, protein and EPS secretion, followed by phosphorus concentration and temperature. The coupled effect of carbon and phosphorus concentration was also very important to stimulate polysaccharide and EPS production.

  7. A comparison study of different physical treatments on cartilage matrix derived porous scaffolds for tissue engineering applications

    NASA Astrophysics Data System (ADS)

    Moradi, Ali; Pramanik, Sumit; Ataollahi, Forough; Khalil, Alizan Abdul; Kamarul, Tunku; Pingguan-Murphy, Belinda

    2014-12-01

    Native cartilage matrix derived (CMD) scaffolds from various animal and human sources have drawn attention in cartilage tissue engineering due to the demonstrable presence of bioactive components. Different chemical and physical treatments have been employed to enhance the micro-architecture of CMD scaffolds. In this study we have assessed the typical effects of physical cross-linking methods, namely ultraviolet (UV) light, dehydrothermal (DHT) treatment, and combinations of them on bovine articular CMD porous scaffolds with three different matrix concentrations (5%, 15% and 30%) to assess the relative strengths of each treatment. Our findings suggest that UV and UV-DHT treatments on 15% CMD scaffolds can yield architecturally optimal scaffolds for cartilage tissue engineering.

  8. Influence of Parathyroid Hormone-Loaded PLGA Nanoparticles in Porous Scaffolds for Bone Regeneration

    PubMed Central

    Gentile, Piergiorgio; Nandagiri, Vijay Kumar; Pabari, Ritesh; Daly, Jacqueline; Tonda-Turo, Chiara; Ciardelli, Gianluca; Ramtoola, Zebunnissa

    2015-01-01

    Biodegradable poly(lactide-co-glycolide) (PLGA) nanoparticles, containing human parathyroid hormone (PTH (1–34)), prepared by a modified double emulsion-solvent diffusion-evaporation method, were incorporated in porous freeze-dried chitosan-gelatin (CH-G) scaffolds. The PTH-loaded nanoparticles (NPTH) were characterised in terms of morphology, size, protein loading, release kinetics and in vitro assessment of biological activity of released PTH and cytocompatibility studies against clonal human osteoblast (hFOB) cells. Structural integrity of incorporated and released PTH from nanoparticles was found to be intact by using Tris-tricine SDS-PAGE. In vitro PTH release kinetics from PLGA nanoparticles were characterised by a burst release followed by a slow release phase for 3–4 weeks. The released PTH was biologically active as evidenced by the stimulated release of cyclic AMP from hFOB cells as well as increased mineralisation studies. Both in vitro and cell studies demonstrated that the PTH bioactivity was maintained during the fabrication of PLGA nanoparticles and upon release. Finally, a content of 33.3% w/w NPTHs was incorporated in CH-G scaffolds, showing an intermittent release during the first 10 days and, followed by a controlled release over 28 days of observation time. The increased expression of Alkaline Phosphatase levels on hFOB cells further confirmed the activity of intermittently released PTH from scaffolds. PMID:26343649

  9. Liposome combined porous beta-TCP scaffold: preparation, characterization, and anti-biofilm activity.

    PubMed

    Zhu, Chong-Tao; Xu, Yong-Qing; Shi, Jian; Li, Jun; Ding, Jing

    2010-08-01

    The objective of this study was to design a novel artificial bone scaffold for therapy and prevention of refractory bacterial infection. Porous beta-tricalcium phosphate (beta-TCP) scaffold was combined with liposomal gentamicin (GS) to form a novel complex drug carrier. The liposome combined beta-TCP scaffold (LCS) was characterized for its liposome binding rate, drug loading, and micromorphology. The anti-biofilm activity of LCS was evaluated by Staphylococcus aureus biofilm in vitro. The drug release from LCS was recognized as an initial high dose of liposomal GS released from the matrix and a further sustained release of free GS from the liposome, respectively, and it is an ideal release pattern for treatment and prevention of post-operative osteomyelitis. The release kinetics was influenced by variation of particle size of liposome. LCS displayed a potential anti-biofilm activity even in the lowest GS concentration (2.5 microg/mL), and the regrowth time was extended from 5.0 h to 9.5 h. At a higher dosage range, the highest anti-biofilm activity was achieved by LCS with liposomal particle size of 800 nm. In conclusion, the development of LCS showed a new pathway for controlled delivery of liposomal antibiotics for treatment of osteomyelitis caused by persistent bacterial infection. PMID:20429845

  10. Influence of Parathyroid Hormone-Loaded PLGA Nanoparticles in Porous Scaffolds for Bone Regeneration.

    PubMed

    Gentile, Piergiorgio; Nandagiri, Vijay Kumar; Pabari, Ritesh; Daly, Jacqueline; Tonda-Turo, Chiara; Ciardelli, Gianluca; Ramtoola, Zebunnissa

    2015-01-01

    Biodegradable poly(lactide-co-glycolide) (PLGA) nanoparticles, containing human parathyroid hormone (PTH (1-34)), prepared by a modified double emulsion-solvent diffusion-evaporation method, were incorporated in porous freeze-dried chitosan-gelatin (CH-G) scaffolds. The PTH-loaded nanoparticles (NPTH) were characterised in terms of morphology, size, protein loading, release kinetics and in vitro assessment of biological activity of released PTH and cytocompatibility studies against clonal human osteoblast (hFOB) cells. Structural integrity of incorporated and released PTH from nanoparticles was found to be intact by using Tris-tricine SDS-PAGE. In vitro PTH release kinetics from PLGA nanoparticles were characterised by a burst release followed by a slow release phase for 3-4 weeks. The released PTH was biologically active as evidenced by the stimulated release of cyclic AMP from hFOB cells as well as increased mineralisation studies. in vitro and cell studies demonstrated that the PTH bioactivity was maintained during the fabrication of PLGA nanoparticles and upon release. Finally, a content of 33.3% w/w NPTHs was incorporated in CH-G scaffolds, showing an intermittent release during the first 10 days and, followed by a controlled release over 28 days of observation time. The increased expression of Alkaline Phosphatase levels on hFOB cells further confirmed the activity of intermittently released PTH from scaffolds. PMID:26343649

  11. 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

  12. 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. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1017-1029, 2016. PMID:26567028

  13. Biosensors based on porous cellulose nanocrystal-poly(vinyl alcohol) scaffolds.

    PubMed

    Schyrr, Bastien; Pasche, Stphanie; Voirin, Guy; Weder, Christoph; Simon, Yoan C; Foster, E Johan

    2014-08-13

    Cellulose nanocrystals (CNCs), which offer a high aspect ratio, large specific surface area, and large number of reactive surface groups, are well suited for the facile immobilization of high density biological probes. We here report functional high surface area scaffolds based on cellulose nanocrystals (CNCs) and poly(vinyl alcohol) (PVA) and demonstrate that this platform is useful for fluorescence-based sensing schemes. Porous CNC/PVA nanocomposite films with a thickness of 25-70 nm were deposited on glass substrates by dip-coating with an aqueous mixture of the CNCs and PVA, and the porous nanostructure was fixated by heat treatment. In a subsequent step, a portion of the scaffold's hydroxyl surface groups was reacted with 2-(acryloxy)ethyl (3-isocyanato-4-methylphenyl)carbamate to permit the immobilization of thiolated fluorescein-substituted lysine, which was used as a first sensing motif, via nucleophile-based thiol-ene Michael addition. The resulting sensor films exhibit a nearly instantaneous and pronounced change of their fluorescence emission intensity in response to changes in pH. The approach was further extended to the detection of protease activity by immobilizing a Frster-type resonance energy transfer chromophore pair via a labile peptide sequence to the scaffold. This sensing scheme is based on the degradation of the protein linker in the presence of appropriate enzymes, which separate the chromophores and causes a turn-on of the originally quenched fluorescence. Using a standard benchtop spectrometer to monitor the increase in fluorescence intensity, trypsin was detected at a concentration of 250 ?g/mL, i.e., in a concentration that is typical for abnormal proteolytic activity in wound fluids. PMID:24955644

  14. Preparation, in vitro degradability, cytotoxicity, and in vivo biocompatibility of porous hydroxyapatite whisker-reinforced poly(L-lactide) biocomposite scaffolds.

    PubMed

    Xie, Lu; Yu, Haiyang; Yang, Weizhong; Zhu, Zhuoli; Yue, Li

    2016-04-01

    Biodegradable and bioactive scaffolds with interconnected macroporous structures, suitable biodegradability, adequate mechanical property, and excellent biocompatibility have drawn increasing attention in bone tissue engineering. Hence, in this work, porous hydroxyapatite whisker-reinforced poly(L-lactide) (HA-w/PLLA) composite scaffolds with different ratios of HA and PLLA were successfully developed through compression molding and particle leaching. The microstructure, in vitro mineralization, cytocompatibility, hemocompatibility, and in vivo biocompatibility of the porous HA-w/PLLA were investigated for the first time. The SEM results revealed that these HA-w/PLLA scaffolds possessed interconnected pore structures. Compared with porous HA powder-reinforced PLLA (HA-p/PLLA) scaffolds, HA-w/PLLA scaffolds exhibited better mechanical property and in vitro bioactivity, as more formation of bone-like apatite layers were induced on these scaffolds after mineralization in SBF. Importantly, in vitro cytotoxicity displayed that porous HA-w/PLLA scaffold with HA/PLLA ratio of 1:1 (HA-w1/PLLA1) produced no deleterious effect on human mesenchymal stem cells (hMSCs), and cells performed elevated cell proliferation, indicating a good cytocompatibility. Simultaneously, well-behaved hemocompatibility and favorable in vivo biocompatibility determined from acute toxicity test and histological evaluation were also found in the porous HA-w1/PLLA1 scaffold. These findings may provide new prospects for utilizing the porous HA whisker-based biodegradable scaffolds in bone repair, replacement, and augmentation applications. PMID:26873015

  15. Modulation of anabolic and catabolic responses via a porous polymer scaffold manufactured using thermally induced phase separation.

    PubMed

    Yu, Nicole Y C; Schindeler, Aaron; Peacock, Lauren; Mikulec, Kathy; Fitzpatrick, Jane; Ruys, Andrew J; Cooper-White, Justin J; Little, David G

    2013-01-01

    We describe two studies encompassing the iterative refinement of a polymer-based rhBMP-2 delivery system for bone tissue engineering. Firstly, we compared the bone-forming capacity of porous poly(D,L-lactic-co-glycolic acid) (PLGA) scaffolds produced by thermally induced phase separation (TIPS) with non-porous solvent cast poly(D,L-lactic acid) (PDLLA) used previously. Secondly, we examined the potential synergy between rhBMP-2 and local bisphosphonate in the PLGA scaffold system. In vivo ectopic bone formation studies were performed in C57BL6/J mice. Polymer scaffolds containing 0, 5, 10 or 20 g rhBMP-2 were inserted into the dorsal musculature. At all rhBMP-2 doses, porous PLGA produced significantly higher bone volume (BV, mm3) than the solid PDLLA scaffolds. Next, porous PLGA scaffolds containing 10 g rhBMP-2 0.2, or 2 g zoledronic acid (ZA) were inserted into the hind-limb musculature. Co-delivery of local 10 g rhBMP-2/2 g ZA significantly augmented bone formation compared with rhBMP-2 alone (400 % BV increase, p < 0.01). Hydroxyapatite microparticle (HAp) addition (2 % w/w) to the 10 g rhBMP-2/0.2 g ZA group increased BV (200 %, p < 0.01). We propose that this was due to controlled ZA release of HAp-bound ZA. Consistent with this, elution analyses showed that HAp addition did not alter the rhBMP-2 elution, but delayed ZA release. Moreover, 2 % w/w HAp addition reduced the scaffold's compressive properties, but did not alter ease of surgical handling. In summary, our data show that refinement of the polymer selection and scaffold fabrication can enhance rhBMP-2 induced bone formation in our bone tissue engineering implant, and this can be further optimised by the local co-delivery of ZA/HAp. PMID:23444237

  16. In vitro and in vivo evaluation of porous TiNi-based alloy as a scaffold for cell tissue engineering.

    PubMed

    Kokorev, Oleg V; Hodorenko, Valentina N; Chekalkin, Timofey L; Kim, Ji-Soon; Kang, Seung-Baik; Dambaev, Georgiy Ts; Gunther, Victor E

    2016-03-01

    This study aims to look into the applicability of a porous TiNi-based shape memory alloy (SMA) scaffold as an incubator for bone marrow mesenchymal cells, hepatocytes, and pancreatic islet cells. The porous TiNi-based SMA used was fabricated using a self-propagating high-temperature synthesis (SHS) technique, in which scaffold blocks measuring 4 × 4 × 10 mm were prepared. In vitro tests were done using mesenchymal stem cells (MSC) isolated from mature bone marrow of CBA/j inbred mice, and cultured in 3 different culture media - Control medium, Osteogenic medium, and Chondrogenic medium. Hepatocytes and islet cells were isolated from the livers and pancreatic glands of Wistar rats respectively, seeded on porous TiNi-based SMA scaffolds, and cultured. The scaffolds were then implanted into the abdominal cavity of Wistar rats and later harvested, at days 7, 14, 21, and 28, post-implantation. SEM imaging was performed with pre-implanted scaffolds at day 0 and harvested scaffolds at days 7, 14, 21, and 28, post-implantation. Based on weight increase percentages, the in vitro study revealed that the osteogenic group showed a 2-fold increase, and the chondrogenic group showed a 1.33-fold increase, compared to the control group. The in vivo study, on the other hand, showed that from day 7 post-implantation, the cellular in-growth gradually invaded the inner porous structure from the periphery towards the center, and at day-28 post-implantation, all pores were closed and completely filled with cells and the extracellular matrix. The results show that porous TiNi-based SMA is a unique biocompatible incubator for cell cultures and can be successfully used for tissue bioengineering and artificial organs. PMID:25613028

  17. Response of murine bone marrow-derived mesenchymal stromal cells to dry-etched porous silicon scaffolds.

    PubMed

    Hajj-Hassan, Mohamad; Khayyat-Kholghi, Maedeh; Wang, Huifen; Chodavarapu, Vamsy; Henderson, Janet E

    2011-11-01

    Porous silicon shows great promise as a bio-interface material due to its large surface to volume ratio, its stability in aqueous solutions and to the ability to precisely regulate its pore characteristics. In the current study, porous silicon scaffolds were fabricated from single crystalline silicon wafers by a novel xenon difluoride dry etching technique. This simplified dry etch fabrication process allows selective formation of porous silicon using a standard photoresist as mask material and eliminates the post-formation drying step typically required for the wet etching techniques, thereby reducing the risk of damaging the newly formed porous silicon. The porous silicon scaffolds supported the growth of primary cultures of bone marrow derived mesenchymal stromal cells (MSC) plated at high density for up to 21 days in culture with no significant loss of viability, assessed using Alamar Blue. Scanning electron micrographs confirmed a dense lawn of cells at 9 days of culture and the presence of MSC within the pores of the porous silicon scaffolds. PMID:21858915

  18. Graded porous polyurethane foam: a potential scaffold for oro-maxillary bone regeneration.

    PubMed

    Giannitelli, S M; Basoli, F; Mozetic, P; Piva, P; Bartuli, F N; Luciani, F; Arcuri, C; Trombetta, M; Rainer, A; Licoccia, S

    2015-06-01

    Bone tissue engineering applications demand for biomaterials offering a substrate for cell adhesion, migration, and proliferation, while inferring suitable mechanical properties to the construct. In the present study, polyurethane (PU) foams were synthesized to develop a graded porous material-characterized by a dense shell and a porous core-for the treatment of oro-maxillary bone defects. Foam was synthesized via a one-pot reaction starting from a polyisocyanate and a biocompatible polyester diol, using water as a foaming agent. Different foaming conditions were examined, with the aim of creating a dense/porous functional graded material that would perform at the same time as an osteoconductive scaffold for bone defect regeneration and as a membrane-barrier to gingival tissue ingrowth. The obtained PU was characterized in terms of morphological and mechanical properties. Biocompatibility assessment was performed in combination with bone-marrow-derived human mesenchymal stromal cells (hBMSCs). Our findings confirm that the material is potentially suitable for guided bone regeneration applications. PMID:25842142

  19. Bone regeneration in strong porous bioactive glass (13–93) scaffolds with an oriented microstructure implanted in rat calvarial defects

    PubMed Central

    Liu, Xin; Rahaman, Mohamed N.; Fu, Qiang

    2012-01-01

    There is a need for synthetic bone graft substitutes to repair large bone defects resulting from trauma, malignancy, and congenital diseases. Bioactive glass has attractive properties as a scaffold material but factors that influence its ability to regenerate bone in vivo are not well understood. In the present work, the ability of strong porous scaffolds of 13–93 bioactive glass with an oriented microstructure to regenerate bone was evaluated in vivo using a rat calvarial defect model. Scaffolds with an oriented microstructure of columnar pores (porosity = 50%; pore diameter = 50–150 µm) showed mostly osteoconductive bone regeneration, and new bone formation, normalized to the available pore area (volume) of the scaffolds, increased from 37% at 12 weeks to 55% at 24 weeks. Scaffolds of the same glass with a trabecular microstructure (porosity = 80%; pore width = 100–500 µm), used as the positive control, showed bone regeneration in the pores of 25% and 46% at 12 and 24 weeks, respectively. The brittle mechanical response of the as-fabricated scaffolds changed markedly to an elasto-plastic response in vivo at both implantation times. These results indicate that both groups of 13–93 bioactive glass scaffolds could potentially be used to repair large bone defects, but scaffolds with the oriented microstructure could also be considered for the repair of loaded bone. PMID:22922251

  20. Porous diopside (CaMgSi(2)O(6)) scaffold: A promising bioactive material for bone tissue engineering.

    PubMed

    Wu, Chengtie; Ramaswamy, Yogambha; Zreiqat, Hala

    2010-06-01

    Diopside (CaMgSi(2)O(6)) powders and dense ceramics have been shown to be bioactive biomaterials for bone repair. The aim of this study is to prepare bioactive diopside scaffolds and examine their physicochemical and biological properties. X-ray diffraction, scanning electron microscopy (SEM), micro-computerized tomography and energy-dispersive spectrometry were used to analyse the composition, microstructure, pore size and interconnectivity of the diopside scaffolds. The mechanical strength and stability as well as the degradation of the scaffolds were investigated by testing the compressive strength, modulus and silicon ions released, respectively. Results showed that highly porous diopside scaffolds with varying porosity and high interconnectivity of 97% were successfully prepared with improved compressive strength and mechanical stability, compared to the bioglass and CaSiO(3) scaffolds. The bioactivity of the diopside scaffolds was assessed using apatite-forming ability in simulated body fluids (SBF) and by their support for human osteoblastic-like cell (HOB) attachment, proliferation and differentiation using SEM, and MTS and alkaline phosphatase activity assays, respectively. Results showed that diopside scaffolds possessed apatite-forming ability in SBF and supported HOB attachment proliferation and differentiation. Bioactive diopside scaffolds were prepared with excellent pore/structure art, and improved mechanical strength and mechanical stability, suggesting their possible applications for bone tissue engineering regeneration. PMID:20018260

  1. The effect of collagen-chitosan porous scaffold thickness on dermal regeneration in a one-stage grafting procedure.

    TOXLINE Toxicology Bibliographic Information

    Haifei S; Xingang W; Shoucheng W; Zhengwei M; Chuangang Y; Chunmao H

    2014-01-01

    Dermal substitutes are used as dermal regeneration templates to reduce scar formation and improve wound healing. Unlike autografts, dermal substitutes lack normal vascular networks. The increased distance required for diffusion of oxygen and nutrients to the autograft following interpositioning of the substitute dramatically affects graft survival. To evaluate the effect of collagen-chitosan scaffold thickness on dermal regeneration, single-layer collagen-chitosan porous scaffolds of 0.5-, 1- and 2-mm thicknesses were fabricated and used to treat full-thickness wounds in a one-stage grafting procedure in a rat model. Skin-graft viability, wound contraction, histological changes, and wound tensile strength were evaluated. The results indicated that the distance for the diffusion of oxygen and nutrients to the autograft in the 2-mm-thick scaffold provided less support for graft take, which resulted in graft necrosis, extensive inflammatory reaction, marked foreign-body reaction (FBR), rapid scaffold degradation, and abnormal collagen deposition and remodeling. In contrast, the thinner scaffolds, especially of that 0.5-mm thickness, promoted earlier angiogenesis, ensuring skin-graft viability with a mild FBR, and ordered fibroblast infiltration and better collagen remodeling. It can be concluded that collagen-chitosan porous scaffolds with a thickness of <1mm are more suitable for dermal regeneration and can be used as dermal templates for treatment of dermal defects using a one-stage grafting procedure.

  2. The effect of collagen-chitosan porous scaffold thickness on dermal regeneration in a one-stage grafting procedure.

    PubMed

    Haifei, Shi; Xingang, Wang; Shoucheng, Wu; Zhengwei, Mao; Chuangang, You; Chunmao, Han

    2014-01-01

    Dermal substitutes are used as dermal regeneration templates to reduce scar formation and improve wound healing. Unlike autografts, dermal substitutes lack normal vascular networks. The increased distance required for diffusion of oxygen and nutrients to the autograft following interpositioning of the substitute dramatically affects graft survival. To evaluate the effect of collagen-chitosan scaffold thickness on dermal regeneration, single-layer collagen-chitosan porous scaffolds of 0.5-, 1- and 2-mm thicknesses were fabricated and used to treat full-thickness wounds in a one-stage grafting procedure in a rat model. Skin-graft viability, wound contraction, histological changes, and wound tensile strength were evaluated. The results indicated that the distance for the diffusion of oxygen and nutrients to the autograft in the 2-mm-thick scaffold provided less support for graft take, which resulted in graft necrosis, extensive inflammatory reaction, marked foreign-body reaction (FBR), rapid scaffold degradation, and abnormal collagen deposition and remodeling. In contrast, the thinner scaffolds, especially of that 0.5-mm thickness, promoted earlier angiogenesis, ensuring skin-graft viability with a mild FBR, and ordered fibroblast infiltration and better collagen remodeling. It can be concluded that collagen-chitosan porous scaffolds with a thickness of <1mm are more suitable for dermal regeneration and can be used as dermal templates for treatment of dermal defects using a one-stage grafting procedure. PMID:24076783

  3. 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. PMID:26774574

  4. Collagen-poly(dialdehyde) guar gum based porous 3D scaffolds immobilized with growth factor for tissue engineering applications.

    PubMed

    Ragothaman, Murali; Palanisamy, Thanikaivelan; Kalirajan, Cheirmadurai

    2014-12-19

    Here we report the preparation of collagen-poly(dialdehyde) guar gum based hybrid functionalized scaffolds covalently immobilized with platelet derived growth factor - BB for tissue engineering applications. Poly(dialdehyde) guar gum was synthesized from selective oxidation of guar gum using sodium periodate. The synthesized poly(dialdehyde) guar gum not only promotes crosslinking of collagen but also immobilizes the platelet derived growth factor through imine bonds. The covalent crosslinking formed in collagen improves thermal, swelling and biodegradation properties of the hybrid scaffolds. The prepared hybrid scaffolds show 3D interconnected honeycomb porous structure when viewed under a microscope. The release of immobilized platelet derived growth factor was seen up to 13th day of incubation thereby proving its sustained delivery. The developed hybrid scaffold leads to a quantum increase in NIH 3T3 fibroblast cell density and proliferation thereby demonstrating its potential for tissue engineering applications. PMID:25263907

  5. Towards a methodology for the effective surface modification of porous polymer scaffolds.

    PubMed

    Safinia, Laleh; Datan, Nathalie; Hhse, Marek; Mantalaris, Athanassios; Bismarck, Alexander

    2005-12-01

    A novel low-pressure radio-frequency plasma treatment protocol was developed to achieve the effective through-thickness surface modification of large porous poly (D,L-lactide) (PDLLA) polymer scaffolds using air or water: ammonia plasma treatments. Polymer films were modified as controls. Scanning electron micrographs and maximum bubble point measurements demonstrated that the PDLLA foams have the high porosity, void fraction and interconnected pores required for use as tissue engineering scaffolds. The polymer surface of the virgin polymer does contain acidic functional groups but is hydrophobic. Following exposure to air or water: ammonia plasma, an increased number of polar functional groups and improved wetting behaviour, i.e. hydrophilicity, of wet surfaces was detected. The number of polar surface functional groups increased (hence the decrease in water contact angles) with increasing exposure time to plasma. The change in surface composition and wettablility of wet polymer constructs was characterised by zeta potential and contact angle measurements. The hydrophobic recovery of the treated PDLLA polymer surfaces was also studied. Storage of the treated polymer constructs in ambient air caused an appreciable hydrophobic recovery, whereas in water only partial hydrophobic recovery occurred. However, in both cases the initial surface characteristics decay as function of time. PMID:16009420

  6. Porous biocompatible three-dimensional scaffolds of cellulose microfiber/gelatin composites for cell culture.

    PubMed

    Xing, Qi; Zhao, Feng; Chen, Si; McNamara, James; Decoster, Mark A; Lvov, Yuri M

    2010-06-01

    Physiological tissues, including brain and other organs, have three-dimensional (3-D) aspects that need to be supported to model them in vitro. Here we report the use of cellulose microfibers combined with cross-linked gelatin to make biocompatible porous microscaffolds for the sustained growth of brain cell and human mesenchymal stem cells (hMSCs) in 3-D structure. Live imaging using confocal microscopy indicated that 3-D microscaffolds composed of gelatin or cellulose fiber/gelatin both supported brain cell adhesion and growth for 16days in vitro. Cellulose microfiber/gelatin composites containing up to 75% cellulose fibers can withstand a higher mechanical load than gelatin alone, and composites also provided linear pathways along which brain cells could grow compared to more clumped cell growth in gelatin alone. Therefore, the bulk cellulose microfiber provides a novel skeleton in this new scaffold material. Cellulose fiber/gelatin scaffold supported hMSCs growth and extracellular matrix formation. hMSCs osteogenic and adipogenic assays indicated that hMSCs cultured in cellulose fiber/gelatin composite preserved the multilineage differentiation potential. As natural, biocompatible components, the combination of gelatin and cellulose microfibers, fabricated into 3-D matrices, may therefore provide optimal porosity and tensile strength for long-term maintenance and observation of cells. PMID:20035906

  7. Controllable synthesis and characterization of porous polyvinyl alcohol/hydroxyapatite nanocomposite scaffolds via an in situ colloidal technique.

    PubMed

    Poursamar, S Ali; Azami, Mahmoud; Mozafari, Masoud

    2011-06-01

    During the last decades, there have been several attempts to combine bioactive materials with biocompatible and biodegradable polymers to create nanocomposite scaffolds with excellent biocompatibility, bioactivity, biodegradability and mechanical properties. In this research, the nanocomposite scaffolds with compositions based on PVA and HAp nanoparticles were successfully prepared using colloidal HAp nanoparticles combined with freeze-drying technique for tissue engineering applications. In addition, the effect of the pH value of the reactive solution and different percentages of PVA and HAp on the synthesis of PVA/HAp nanocomposites were investigated. The SEM observations revealed that the prepared scaffolds were porous with three dimensional microstructures, and in vitro experiments with osteoblast cells indicated an appropriate penetration of the cells into the scaffold's pores, and also the continuous increase in cell aggregation on the scaffolds with increase in the incubation time demonstrated the ability of the scaffolds to support cell growth. According to the obtained results, the nanocomposite scaffolds could be considered as highly bioactive and potential bone tissue engineering implants. PMID:21310596

  8. Optimization and evaluation of silk fibroin-chitosan freeze-dried porous scaffolds for cartilage tissue engineering application.

    PubMed

    Vishwanath, Varshini; Pramanik, Krishna; Biswas, Amit

    2016-05-01

    Silk fibroin/chitosan blend has been reported to be an attractive biomaterial that provides a 3D porous structure with controllable pore size and mechanical property suitable for tissue engineering applications. However, there is no systematic study for optimizing the ratio of silk fibroin (SF) and chitosan (CS) which seems to influence the scaffold property to a great extent. The present research, therefore, investigates the effect of blend ratio of SF and CS on scaffold property and establishes the optimum value of blend ratio. Among the various blends, the scaffolds with blend ratio of SF/CS (80:20) were found to be superior. The scaffold possesses pore size in the range 71-210 μm and porosity of 82.2 ± 1.3%. The compressive strength of the scaffold was measured as 190 ± 0.2 kPa. The cell supportive property of the scaffold in terms of cell attachment, cell viability, and proliferation was confirmed by cell culture study using mesenchymal stem cells derived from umbilical cord blood. Furthermore, the assessment of glycosaminoglycan secretion on the scaffolds indicates its potentiality toward cartilage tissue regeneration. PMID:26830046

  9. Tissue engineering of bovine articular cartilage within porous poly(ether ester) copolymer scaffolds with different structures.

    PubMed

    Mahmood, Tahir A; Shastri, V Prasad; van Blitterswijk, Clemens A; Langer, Robert; Riesle, Jens

    2005-01-01

    The potential of porous poly(ether ester) scaffolds made from poly(ethylene glycol) terephthalate: poly(butylene terephthalate) (PEGT:PBT) block copolymers produced by various methods to enable cartilaginous tissue formation in vitro was studied. Scaffolds were fabricated by two different processes: paraffin templating (PT) and compression molding (CM). To determine whether PEGT:PBT scaffolds are able to support chondrogenesis, primary bovine chondrocytes were seeded within cylindrical scaffolds under dynamic seeding conditions. On day 3, constructs were transferred to six-well plates and evaluated for glycosaminoglycan (GAG) distribution (3, 10, and 24 days), type II collagen distribution, cellularity, and total collagen and GAG content (10 and 24 days). It was observed that better cell distribution during infiltration within PT scaffolds allowed greater chondrogenesis, and at later time points, than in CM scaffolds. The amount of GAG remained constant for all groups from 10 to 24 days, whereas collagen content increased significantly. These data suggest that PEGT:PBT scaffolds are suitable for cartilage tissue engineering, with the PT process enabling greater chondrogenesis than CM. PMID:16144460

  10. Nanogel tectonic porous gel loading biologics, nanocarriers, and cells for advanced scaffold.

    PubMed

    Hashimoto, Yoshihide; Mukai, Sada-atsu; Sawada, Shin-ichi; Sasaki, Yoshihiro; Akiyoshi, Kazunari

    2015-01-01

    We developed a new self-assembled amphiphilic nanogel-crosslinked porous (NanoCliP) gel that can trap proteins, liposomes, and cells. The NanoCliP gel was prepared by Michael addition of a self-assembled nanogel of acryloyl group-modified cholesterol-bearing pullulan to pentaerythritol tetra (mercaptoethyl) polyoxyethylene, followed by freezing-induced phase separation. Dynamic rheological analysis revealed that the storage modulus (G') of the NanoCliP gel was approximately 10 times greater than that of a nonporous nanogel-crosslinked gel. Two-photon excitation deep imaging revealed that the NanoCliP gel comprises interconnected pores of several hundred micrometers in diameter. The NanoCliP gel trapped proteins and liposomes via hydrophobic interactions because its amphiphilic nanogels exhibit chaperone-like activity. Mouse embryonic fibroblasts penetrated the interconnected pores and adhered to the porous surface of fibronectin-complexed NanoCliP gel. In vivo, the NanoCliP gel enhanced cell infiltration, tissue ingrowth, and neovascularization without requiring exogenous growth factors, suggesting that the NanoCliP gel is a promising scaffold for tissue engineering. PMID:25453324

  11. Nanostructured Porous Silicon: The Winding Road from Photonics to Cell Scaffolds – A Review

    PubMed Central

    Hernández-Montelongo, Jacobo; Muñoz-Noval, Alvaro; García-Ruíz, Josefa Predestinación; Torres-Costa, Vicente; Martín-Palma, Raul J.; Manso-Silván, Miguel

    2015-01-01

    For over 20 years, nanostructured porous silicon (nanoPS) has found a vast number of applications in the broad fields of photonics and optoelectronics, triggered by the discovery of its photoluminescent behavior in 1990. Besides, its biocompatibility, biodegradability, and bioresorbability make porous silicon (PSi) an appealing biomaterial. These properties are largely a consequence of its particular susceptibility to oxidation, leading to the formation of silicon oxide, which is readily dissolved by body fluids. This paper reviews the evolution of the applications of PSi and nanoPS from photonics through biophotonics, to their use as cell scaffolds, whether as an implantable substitute biomaterial, mainly for bony and ophthalmological tissues, or as an in vitro cell conditioning support, especially for pluripotent cells. For any of these applications, PSi/nanoPS can be used directly after synthesis from Si wafers, upon appropriate surface modification processes, or as a composite biomaterial. Unedited studies of fluorescently active PSi structures for cell culture are brought to evidence the margin for new developments. PMID:26029688

  12. Freeze casting of porous hydroxyapatite scaffolds. II. Sintering, microstructure, and mechanical behavior.

    PubMed

    Fu, Qiang; Rahaman, Mohamed N; Dogan, Fatih; Bal, B Sonny

    2008-08-01

    In Part I, the influence of processing parameters on the general microstructure of freeze-cast hydroxyapatite (HA) constructs was explored. This work is an extension of Part I to investigate the effect of sintering conditions on the microstructure and mechanical behavior of freeze-cast HA. For constructs prepared from aqueous suspensions (5-20 vol % HA), sintering for 3 h at temperatures from 1250 degrees C to 1375 degrees C produced a decrease in porosity of <5% but an increase in strength of nearly 50%. Constructs with a porosity of 52% had compressive strengths of 12 +/- 1 MPa and 5 +/- 1 MPa in the directions parallel and perpendicular to the freezing direction, respectively. The mechanical response showed high strain tolerance (5-10% at the maximum stress), high strain to failure (>20%), and high strain rate sensitivity. Manipulation of the freeze-cast microstructure, achieved by additions of glycerol and 1,4-dioxane to the aqueous suspensions, produced changes in the magnitude of the mechanical response, but little change in the general nature of the response. The favorable mechanical behavior of the porous constructs, coupled with the ability to modify their microstructure, indicates the potential of the present freeze-casting route for the production of porous scaffolds for bone tissue engineering. PMID:18338786

  13. Dynamic freeze casting for the production of porous titanium (Ti) scaffolds.

    PubMed

    Jung, Hyun-Do; Yook, Se-Won; Jang, Tae-Sik; Li, Yuanlong; Kim, Hyoun-Ee; Koh, Young-Hag

    2013-01-01

    This paper proposes dynamic freeze casting as a new manufacturing technique for producing porous Ti scaffolds with a uniform porous structure and good ductility. In this method, Ti/camphene slurries with various initial Ti contents (15, 20, and 25 vol.%) were frozen at 44 °C for 12 h in rotation, which allowed for the extensive growth of camphene crystals and the uniform construction of walls made of Ti particles. All the fabricated samples showed spherical-like pores surrounded by dense Ti walls that were uniformly formed after sintering at 1300 °C for 2 h in a vacuum. The porosity decreased from 71 to 52 vol.% with an increase in Ti content from 15 to 25 vol.%, whereas the pore size decreased from 362 to 95 μm. On the other hand, the compressive strength and stiffness increased considerably from 57±4 to 183±6 MPa and from 1.3±0.5 to 5.0±0.8 GPa, respectively, due to the decrease in the porosity of the samples. PMID:25428042

  14. Data on bone marrow stem cells delivery using porous polymer scaffold

    PubMed Central

    Geesala, Ramasatyaveni; Bar, Nimai; Dhoke, Neha R.; Basak, Pratyay; Das, Amitava

    2015-01-01

    Low bioavailability and/or survival at the injury site of transplanted stem cells necessitate its delivery using a biocompatible, biodegradable cell delivery vehicle. In this dataset, we report the application of a porous biocompatible, biodegradable polymer network that successfully delivers bone marrow stem cells (BMSCs) at the wound site of a murine excisional splint wound model. In this data article, we are providing the additional data of the reference article “Porous polymer scaffold for on-site delivery of stem cells – protects from oxidative stress and potentiates wound tissue repair” (Ramasatyaveni et al., 2016) [1]. This data consists of the characterization of bone marrow stem cells (BMSCs) showing the pluripotency and stem cell-specific surface markers. Image analysis of the cellular penetration into PEG–PU polymer network and the mechanism via enzymatic activation of MMP-2 and MMP-13 are reported. In addition, we provide a comparison of various routes of transplantation-mediated BMSCs engraftment in the murine model using bone marrow transplantation chimeras. Furthermore, we included in this dataset the engraftment of BMSCs expressing Sca-1+Lin−CD133+CD90.2+ in post-surgery day 10. PMID:26862563

  15. Data on bone marrow stem cells delivery using porous polymer scaffold.

    PubMed

    Geesala, Ramasatyaveni; Bar, Nimai; Dhoke, Neha R; Basak, Pratyay; Das, Amitava

    2016-03-01

    Low bioavailability and/or survival at the injury site of transplanted stem cells necessitate its delivery using a biocompatible, biodegradable cell delivery vehicle. In this dataset, we report the application of a porous biocompatible, biodegradable polymer network that successfully delivers bone marrow stem cells (BMSCs) at the wound site of a murine excisional splint wound model. In this data article, we are providing the additional data of the reference article "Porous polymer scaffold for on-site delivery of stem cells - protects from oxidative stress and potentiates wound tissue repair" (Ramasatyaveni et al., 2016) [1]. This data consists of the characterization of bone marrow stem cells (BMSCs) showing the pluripotency and stem cell-specific surface markers. Image analysis of the cellular penetration into PEG-PU polymer network and the mechanism via enzymatic activation of MMP-2 and MMP-13 are reported. In addition, we provide a comparison of various routes of transplantation-mediated BMSCs engraftment in the murine model using bone marrow transplantation chimeras. Furthermore, we included in this dataset the engraftment of BMSCs expressing Sca-1(+)Lin(-)CD133(+)CD90.2(+) in post-surgery day 10. PMID:26862563

  16. Preparation and Reinforcement of Dual‐Porous Biocompatible Cellulose Scaffolds for Tissue Engineering

    PubMed Central

    Pircher, Nicole; Fischhuber, David; Carbajal, Leticia; Strauß, Christine; Nedelec, Jean‐Marie; Kasper, Cornelia; Rosenau, Thomas

    2015-01-01

    1 Biocompatible cellulose‐based aerogels composed of nanoporous struts, which embed interconnected voids of controlled micron‐size, have been prepared employing temporary templates of fused porogens, reinforcement by interpenetrating PMMA networks and supercritical carbon dioxide drying. Different combinations of cellulose solvent (Ca(SCN)2/H2O/LiCl or [EMIm][OAc]/DMSO) and anti‐solvent (EtOH), porogen type (paraffin wax or PMMA spheres) and porogen size (various fractions in the range of 100–500 μm) as well as intensity of PMMA reinforcement have been investigated to tailor the materials for cell scaffolding applications. All aerogels exhibited an open and dual porosity (micronporosity >100 μm and nanoporosity extending to the low micrometer range). Mechanical properties of the dual‐porous aerogels under compressive stress were considerably improved by introduction of interpenetrating PMMA networks. The effect of the reinforcing polymer on attachment, spreading, and proliferation of NIH 3T3 fibroblast cells, cultivated on selected dual‐porous aerogels to pre‐evaluate their biocompatibility was similarly positive. PMID:26941565

  17. Effect of ZrO2 addition on the mechanical properties of porous TiO2 bone scaffolds.

    PubMed

    Tiainen, Hanna; Eder, Georg; Nilsen, Ola; Haugen, Hvard J

    2012-08-01

    This study aimed at the investigation of the effect of zirconium dioxide (ZrO2) addition on the mechanical properties of titanium dioxide (TiO2) bone scaffolds. The highly biocompatible TiO2 has been identified as a promising material for bone scaffolds, whereas the more bioinert ZrO2 is known for its excellent mechanical properties. Ultra-porous TiO2 scaffolds (>89% porosity) were produced using polymer sponge replication with 0-40 wt.% of the TiO2 raw material substituted with ZrO2. Microstructure, chemical composition, and pore architectural features of the prepared ceramic foams were characterised and related to their mechanical strength. Addition of 1 wt.% of ZrO2 led to 16% increase in the mean compressive strength without significant changes in the pore architectural parameters of TiO2 scaffolds. Further ZrO2 additions resulted in reduction of compressive strength in comparison to containing no ZrO2. The appearance of zirconium titanate (ZrTiO4) phase was found to hinder the densification of the ceramic material during sintering resulting in poor intergranular connections and thus significantly reducing the compressive strength of the highly porous ceramic foam scaffolds. PMID:24364936

  18. Monotonic and cyclic loading behavior of porous scaffolds made from poly(para-phenylene) for orthopedic applications.

    PubMed

    Hoyt, Anthony J; Yakacki, Christopher M; Fertig, Ray S; Dana Carpenter, R; Frick, Carl P

    2015-01-01

    Porous poly(para-phenylene) (PPP) scaffolds have tremendous potential as an orthopedic biomaterial; however, the underlying mechanisms controlling the monotonic and cyclic behavior are poorly understood. The purpose of this study was to develop a method to integrate micro-computed tomography (?CT), finite-element analysis (FEA), and experimental results to uncover the relationships between the porous structure and mechanical behavior. The ?CT images were taken from porous PPP scaffolds with a porosity of 75vol% and pore size distribution between 420 and 500m. Representative sections of the image were segmented and converted into finite-element meshes. It was shown through FEA that localized stresses within the microstructure were approximately 100 times higher than the applied global stress during the linear loading regime. Experimental analysis revealed the S-N fatigue curves for fully dense and porous PPP samples were parallel on log-log plots, with the endurance limit for porous samples in tension being approximately 100 times lower than their solid PPP counterparts (0.3-35MPa) due to the extreme stress concentrations caused by the porous microarchitecture. The endurance limit for porous samples in compression was much higher than in tension (1.60MPa). Through optical, laser-scanning, and scanning-electron microscopy it was found that porous tensile samples failed under Mode I fracture in both monotonic and cyclic loading. By comparison, porous compressive samples failed via strut buckling/pore collapse monotonically and by shearing fracture during cyclic loading. Monotonic loading showed that deformation behavior was strongly correlated with pore volume fraction, matching foam theory well; however, fatigue behavior was much more sensitive to local stresses believed to cause crack nucleation. PMID:25460410

  19. Biomineral coating increases bone formation by ex vivo BMP-7 gene therapy in rapid prototyped poly(L-lactic acid) (PLLA) and poly(?-caprolactone) (PCL) porous scaffolds.

    PubMed

    Saito, Eiji; Suarez-Gonzalez, Darilis; Murphy, William L; Hollister, Scott J

    2015-03-11

    Porousbiodegradable polymer scaffolds are widely utilized for bone tissue engineering, but are not osteoconductive like calcium phosphate scaffolds. We combine indirect solid freeform fabrication (SFF), ex vivo gene therapy, with biomineral coating to compare the effect of biomineral coating on bone regeneration for Poly (L-lactic acid) (PLLA) and Poly (?-caprolactone) (PCL) scaffolds with the same porous architecture. Scanning electron microscope (SEM) and micro-computed tomography (?-CT) demonstrate PLLA and PCL scaffolds have the same porous architecture and are completely coated. All scaffolds are seeded with human gingival fibroblasts (HGF) transduced with adenovirus encoded with either bone morphogenetic protein 7 (BMP-7) or green fluorescent protein (GFP), and implanted into mice subcutaneously for 3 and 10 weeks. Only scaffolds with BMP-7 transduced HGFs show mineralized tissue formation. At 3 weeks some blood vessel-like structures are observed in coated PLLA and PCL scaffolds, but there is no significant difference in bone ingrowth between the coated and uncoated scaffolds for either PLLA or PCL. At 10 weeks, however, coated scaffolds (both PLLA and PCL) have significantly more bone ingrowth than uncoated scaffolds, which have more fibrous tissue. Coated PLLA scaffolds have improved mechanical properties compared with uncoated PLLA scaffolds due to increased bone ingrowth. PMID:25515846

  20. Protein growth factors loaded highly porous chitosan scaffold: a comparison of bone healing properties.

    PubMed

    Nandi, Samit K; Kundu, Biswanath; Basu, Debabrata

    2013-04-01

    Present study aimed to investigate and compare effectiveness of porous chitosan alone and in combination with insulin like growth factor-1 (IGF-1) and bone morphogenetic protein-2 (BMP-2) in bone healing. Highly porous (852%) with wide distribution of macroporous (70-900 ?m) chitosan scaffolds were fabricated as bone substitutes by employing a simple liquid hardening method using 2% (w/v) chitosan suspension. IGF-1 and BMP-2 were infiltrated using vacuum infiltration with freeze drying method. Adsorption efficiency was found to be 872 and 902% for BMP-2 and IGF-1 respectively. After thorough material characterization (pore details, FTIR and SEM), samples were used for subsequent in vivo animal trial. Eighteen rabbit models were used to evaluate and compare control (chitosan) (group A), chitosan with IGF-1 (group B) and chitosan with BMP-2 (group C) in the repair of critical size bone defect in tibia. Radiologically, there was evidence of radiodensity in defect area from 60th day (initiated on 30th day) in groups B and C as compared to group A and attaining nearly bony density in most of the part at day 90. Histological results depicted well developed osteoblastic proliferation around haversian canal along with proliferating fibroblast, vascularization and reticular network which was more pronounced in group B followed by groups C and A. Fluorochrome labeling and SEM studies in all groups showed similar outcome. Hence, porous chitosan alone and in combination with growth factors (GFs) can be successfully used for bone defect healing with slight advantage of IGF-1 in chitosan samples. PMID:23827571

  1. Fabrication of Porous Ultra-Short Single-Walled Carbon Nanotube Nanocomposite Scaffolds for Bone Tissue Engineering

    PubMed Central

    Shi, Xinfeng; Sitharaman, Balaji; Pham, Quynh P.; Liang, Feng; Wu, Katherine; Billups, W. Edward; Wilson, Lon J.; Mikos, Antonios G.

    2011-01-01

    We investigated the fabrication of highly porous scaffolds made of three different materials [poly(propylene fumarate (PPF) polymer, an ultra-short single-walled carbon nanotube (US-tube) nanocomposite, and a dodecylated US-tube (F-US-tube) nanocomposite] in order to evaluate the effects of material composition and porosity on scaffold pore structure, mechanical properties, and marrow stromal cell culture. All scaffolds were produced by a thermal-crosslinking particulate-leaching technique at specific porogen contents of 75, 80, 85, and 90 vol%. Scanning electron microcopy, microcomputed tomography, and mercury intrusion porosimetry were used to analyze the pore structures of scaffolds. The porogen content was found to dictate the porosity of scaffolds. There was no significant difference in porosity, pore size, and interconnectivity among the different materials for the same porogen fraction. Nearly 100% of the pore volume was interconnected through 20 ?m or larger connections for all scaffolds. While interconnectivity through larger connections improved with higher porosity, compressive mechanical properties of scaffolds declined at the same time. However, the compressive modulus, offset yield strength, and compressive strength of F-US-tube nanocomposites were higher than or similar to the corresponding properties for the PPF polymer and US-tube nanocomposites for all the porosities examined. As for in vitro osteoconductivity, marrow stromal cells demonstrated equally good cell attachment and proliferation on all scaffolds made of different materials at each porosity. These results indicate that functionalized ultra-short single-walled carbon nanotube nanocomposite scaffolds with tunable porosity and mechanical properties hold great promise for bone tissue engineering applications. PMID:17576009

  2. Numerical optimization of open-porous bone scaffold structures to match the elastic properties of human cortical bone.

    PubMed

    Wieding, Jan; Wolf, Andreas; Bader, Rainer

    2014-09-01

    Treatment of large segmental bone defects, especially in load bearing areas, is a complex procedure in orthopedic surgery. The usage of additive manufacturing processes enables the creation of customized bone implants with arbitrary open-porous structure satisfying both the mechanical and the biological requirements for a sufficient bone ingrowth. Aim of the present numerical study was to optimize the geometrical parameters of open-porous titanium scaffolds to match the elastic properties of human cortical bone with respect to an adequate pore size. Three different scaffold designs (cubic, diagonal and pyramidal) were numerically investigated by using an optimization approach. Beam elements were used to create the lattice structures of the scaffolds. The design parameters strut diameter and pore size ranged from 0.2 to 1.5mm and from 0 to 3.0mm, respectively. In a first optimization step, the geometrical parameters were varied under uniaxial compression to obtain a structural modulus of 15GPa (Young?s modulus of cortical bone) and a pore size of 800m was aimed to enable cell ingrowth. Furthermore, the mechanical behavior of the optimized structures under bending and torsion was investigated. Results for bending modulus were between 9.0 and 14.5GPa. In contrast, shear modulus was lowest for cubic and pyramidal design of approximately 1GPa. Here, the diagonal design revealed a modulus of nearly 20GPa. In a second step, large-sized bone scaffolds were created and placed in a biomechanical loading situation within a 30mm segmental femoral defect, stabilized with an osteosynthesis plate and loaded with physiological muscle forces. Strut diameter for the 17 sections of each scaffold was optimized independently in order to match the biomechanical stability of intact bone. For each design, highest strut diameter was found at the dorsal/medial site of the defect and smallest strut diameter in the center. In conclusion, we demonstrated the possibility of providing optimized open-porous scaffolds for bone regeneration by considering both mechanical and biological aspects. Furthermore, the results revealed the need of the investigation and comparison of different load scenarios (compression, bending and torsion) as well as complex biomechanical loading for a profound characterization of different scaffold designs. The usage of a numerical optimization process was proven to be a feasible tool to reduce the amount of the required titanium material without influencing the biomechanical performance of the scaffold negatively. By using fully parameterized models, the optimization approach is adaptable to other scaffold designs and bone defect situations. PMID:24942627

  3. Constitution and in vivo test of micro-porous tubular scaffold for esophageal tissue engineering.

    PubMed

    Hou, Lei; Jin, Jiachang; Lv, Jingjing; Chen, Ling; Zhu, Yabin; Liu, Xingyu

    2015-11-01

    Current clinical techniques in treating long-gap esophageal defects often lead to complications and high morbidity. Aiming at long-gap synthetic esophageal substitute, we had synthesized a biodegradable copolymer, poly(L-lactide-co-caprolactone) (PLLC), with low glass transition temperature. In this work, we developed a tubular PLLC porous scaffold using a self-designed tubular mold and thermal induced phase separation (TIPS) method. In order to enhance the interaction between tissue and scaffold, fibrin, a natural fibrous protein derived from blood fibrinogen, was coated on the scaffold circumferential surface. The fibrin density was measured to be 1.23 ± 0.04 mg/cm(2). Primary epithelial cell culture demonstrated the improved in vitro biocompatibility. In animal study with partial scaffold implantation, in situ mucosa regeneration was observed along the degradation of the scaffold. These indicate that fibrin incorporated PLLC scaffold can greatly improve epithelial regeneration in esophagus repair, therefore serve as a good candidate for long-term evaluation of post-implantation at excision site. PMID:26208515

  4. Comparison of different fabrication techniques used for processing 3-dimensional, porous, biodegradable scaffolds from modified starch for bone tissue engineering.

    PubMed

    Kunjachan, V; Subramanian, A; Hanna, M; Guan, J J

    2004-01-01

    3 dimensional, porous, biodegradable scaffolds were fabricated using modified starch of varying degree of substitution (DS) by extrusion processing. Freeze drying/lyophilization was also employed to fabricate scaffolds from modified starch. The research efforts have been focused on the comparison of the above-mentioned techniques by comparing the properties of the fabricated scaffolds in the paradigm of bone tissue engineering. The physicomechanical properties like porosity, compressive strength and modulus, pore size and microstructure were tested and analyzed by liquid replacement, mechanical testing and scanning electron microscopy respectively. The biodegradability of scaffolds was evaluated by soaking the samples in aqueous medium and Hank's balanced salt solution at 37-degree invitro. The cytotoxicity studies on these scaffolds were also conducted. The scaffolds have a 3D structure consisting of interconnected pores with good porosity, pore size, adequate compressive strength and modulus and exhibit good biodegradability as well as biocompatibility. After further optimization in the processing conditions and parameters they could be made useful for bone tissue engineering. PMID:15133947

  5. Biomimetic hybrid porous scaffolds immobilized with platelet derived growth factor-BB promote cellularization and vascularization in tissue engineering.

    PubMed

    Murali, Ragothaman; Ponrasu, Thangavel; Cheirmadurai, Kalirajan; Thanikaivelan, Palanisamy

    2016-02-01

    Development of hybrid scaffolds with synergistic combination of growth factor is a promising approach to promote early in vivo wound repair and tissue regeneration. Here, we show the rapid wound healing in Wistar albino rats using biomimetic collagen-poly(dialdehyde) guar gum based hybrid porous scaffolds covalently immobilized with platelet derived growth factor-BB. The immobilized platelet derived growth factor in the hybrid scaffolds not only enhance the total protein, collagen, hexosamine, and uronic acid contents in the granulation tissue but also provide stronger tissues. The wound closure analysis reveal that the complete epithelialization period is 15.4??0.9 days for collagen-poly(dialdehyde) guar gum-platelet derived growth factor hybrid scaffolds, whereas it is significantly higher for control, collagen, collagen- poly(dialdehyde) guar gum and povidine-iodine treated groups. Further, the histological evaluation shows that the immobilized platelet derived growth factor in the hybrid scaffolds induced a more robust cellular and vascular response in the implanted site. Hence, we demonstrate that the collagen-poly(dialdehyde) guar gum hybrid scaffolds loaded with platelet derived growth factor stimulates chemotactic effects in the implanted site to promote rapid tissue regeneration and wound repair without the assistance of antibacterial agents. 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 388-396, 2016. PMID:26414915

  6. Influence of the laser assisted fabricated 3D porous scaffolds from bioceramoplasts of micron and nano sizes on culture of MMSC

    NASA Astrophysics Data System (ADS)

    Shishkovsky, I.; Volchkov, S.

    2013-11-01

    The objective of the investigation was to test the biocompatibility of 3D porous biopolymer matrices (tissue-cellular scaffolds), made of biocompatible and bioresorbable polymers (polycarbonate, polyetheretherketone /PEEK/, polycaprolactone), including the materials with biocompatible oxide ceramics additive (TiO2, Al2O3, ZrO2 and hydroxyapatite) of micron and nano sizes, for tissue-engineering purposes. The porous samples were prepared via a layer-by-layer SLS method. The surface microstructures and their roughness were analyzed by the optical microscopy equipped with the cell analysis software. The cellular morphology, proliferative activity and adhesion of the polymeric and ceramopolymeric matrices were the subjects for comparison. The study showed that all the tested materials posessed biocompatible properties. The experimentally estimated cell duplication speed per day turned out to be maximal for polycarbonate (0.279 duplications per day) and for PEEK + Al2O3 = 3:1 group (0.30 dupl/day) against 0.387 dupl/day for the reference sample and 0.270 dupl/day for the group of cells placed close to the pure titanium samples.

  7. An ultra-sensitive microfluidic immunoassay using living radical polymerization and porous polymer monoliths.

    SciTech Connect

    Abhyankar, Vinay V.; Singh, Anup K.; Hatch, Anson V.

    2010-07-01

    We present a platform that combines patterned photopolymerized polymer monoliths with living radical polymerization (LRP) to develop a low cost microfluidic based immunoassay capable of sensitive (low to sub pM) and rapid (<30 minute) detection of protein in 100 {micro}L sample. The introduction of LRP functionality to the porous monolith allows one step grafting of functionalized affinity probes from the monolith surface while the composition of the hydrophilic graft chain reduces non-specific interactions and helps to significantly improve the limit of detection.

  8. Tough and Flexible CNT-Polymeric Hybrid Scaffolds for Engineering Cardiac Constructs

    PubMed Central

    Kharaziha, Mahshid; Ryon Shin, Su; Nikkhah, Mehdi; Nur Topkaya, Seda; Masoumi, Nafiseh; Annabi, Nasim; Dokmeci, Mehmet. R.

    2014-01-01

    In the past few years, a considerable amount of effort has been devoted toward the development of biomimetic scaffolds for cardiac tissue engineering. However, most of the previous scaffolds have been electrically insulating or lacked the structural and mechanical robustness to engineer cardiac tissue constructs with suitable electrophysiological functions. Here, we developed tough and flexible hybrid scaffolds with enhanced electrical properties composed of carbon nanotubes (CNTs) embedded aligned poly(glycerol sebacate):gelatin (PG) electrospun nanofibers. Incorporation of varying concentrations of CNTs from 0 to 1.5% within the PG nanofibrous scaffolds (CNT-PG scaffolds) notably enhanced fiber alignment and improved the electrical conductivity and toughness of the scaffolds while maintaining the viability, retention, alignment, and contractile activities of cardiomyocytes (CMs) seeded on the scaffolds. The resulting CNT-PG scaffolds resulted in stronger spontaneous and synchronous beating behavior (3.5-fold lower excitation threshold and 2.8-fold higher maximum capture rate) compared to those cultured on PG scaffold. Overall, our findings demonstrated that aligned CNT-PG scaffold exhibited superior mechanical properties with enhanced CM beating properties. It is envisioned that the proposed hybrid scaffolds can be useful for generating cardiac tissue constructs with improved organization and maturation. PMID:24927679

  9. Tough and flexible CNT-polymeric hybrid scaffolds for engineering cardiac constructs.

    PubMed

    Kharaziha, Mahshid; Shin, Su Ryon; Nikkhah, Mehdi; Topkaya, Seda Nur; Masoumi, Nafiseh; Annabi, Nasim; Dokmeci, Mehmet R; Khademhosseini, Ali

    2014-08-01

    In the past few years, a considerable amount of effort has been devoted toward the development of biomimetic scaffolds for cardiac tissue engineering. However, most of the previous scaffolds have been electrically insulating or lacked the structural and mechanical robustness to engineer cardiac tissue constructs with suitable electrophysiological functions. Here, we developed tough and flexible hybrid scaffolds with enhanced electrical properties composed of carbon nanotubes (CNTs) embedded aligned poly(glycerol sebacate):gelatin (PG) electrospun nanofibers. Incorporation of varying concentrations of CNTs from 0 to 1.5% within the PG nanofibrous scaffolds (CNT-PG scaffolds) notably enhanced fiber alignment and improved the electrical conductivity and toughness of the scaffolds while maintaining the viability, retention, alignment, and contractile activities of cardiomyocytes (CMs) seeded on the scaffolds. The resulting CNT-PG scaffolds resulted in stronger spontaneous and synchronous beating behavior (3.5-fold lower excitation threshold and 2.8-fold higher maximum capture rate) compared to those cultured on PG scaffold. Overall, our findings demonstrated that aligned CNT-PG scaffold exhibited superior mechanical properties with enhanced CM beating properties. It is envisioned that the proposed hybrid scaffolds can be useful for generating cardiac tissue constructs with improved organization and maturation. PMID:24927679

  10. Nano SiO2 and MgO Improve the Properties of Porous ?-TCP Scaffolds via Advanced Manufacturing Technology

    PubMed Central

    Gao, Chengde; Wei, Pingpin; Feng, Pei; Xiao, Tao; Shuai, Cijun; Peng, Shuping

    2015-01-01

    Nano SiO2 and MgO particles were incorporated into ?-tricalcium phosphate (?-TCP) scaffolds to improve the mechanical and biological properties. The porous cylindrical ?-TCP scaffolds doped with 0.5 wt % SiO2, 1.0 wt % MgO, 0.5 wt % SiO2 + 1.0 wt % MgO were fabricated via selective laser sintering respectively and undoped ?-TCP scaffold was also prepared as control. The phase composition and mechanical strength of the scaffolds were evaluated. X-ray diffraction analysis indicated that the phase transformation from ?-TCP to ?-TCP was inhibited after the addition of MgO. The compressive strength of scaffold was improved from 3.12 0.36 MPa (?-TCP) to 5.74 0.62 MPa (?-TCP/SiO2), 9.02 0.55 MPa (?-TCP/MgO) and 10.43 0.28 MPa (?-TCP/SiO2/MgO), respectively. The weight loss and apatite-forming ability of the scaffolds were evaluated by soaking them in simulated body fluid. The results demonstrated that both SiO2 and MgO dopings slowed down the degradation rate and improved the bioactivity of ?-TCP scaffolds. In vitro cell culture studies indicated that SiO2 and MgO dopings facilitated cell attachment and proliferation. Combined addition of SiO2 and MgO were found optimal in enhancing both the mechanical and biological properties of ?-TCP scaffold. PMID:25815597

  11. Nano SiO2 and MgO improve the properties of porous ?-TCP scaffolds via advanced manufacturing technology.

    PubMed

    Gao, Chengde; Wei, Pingpin; Feng, Pei; Xiao, Tao; Shuai, Cijun; Peng, Shuping

    2015-01-01

    Nano SiO2 and MgO particles were incorporated into ?-tricalcium phosphate (?-TCP) scaffolds to improve the mechanical and biological properties. The porous cylindrical ?-TCP scaffolds doped with 0.5 wt % SiO2, 1.0 wt % MgO, 0.5 wt % SiO2 + 1.0 wt % MgO were fabricated via selective laser sintering respectively and undoped ?-TCP scaffold was also prepared as control. The phase composition and mechanical strength of the scaffolds were evaluated. X-ray diffraction analysis indicated that the phase transformation from ?-TCP to ?-TCP was inhibited after the addition of MgO. The compressive strength of scaffold was improved from 3.12 0.36 MPa (?-TCP) to 5.74 0.62 MPa (?-TCP/SiO2), 9.02 0.55 MPa (?-TCP/MgO) and 10.43 0.28 MPa (?-TCP/SiO2/MgO), respectively. The weight loss and apatite-forming ability of the scaffolds were evaluated by soaking them in simulated body fluid. The results demonstrated that both SiO2 and MgO dopings slowed down the degradation rate and improved the bioactivity of ?-TCP scaffolds. In vitro cell culture studies indicated that SiO2 and MgO dopings facilitated cell attachment and proliferation. Combined addition of SiO2 and MgO were found optimal in enhancing both the mechanical and biological properties of ?-TCP scaffold. PMID:25815597

  12. Comprehensive Genetic Analysis of Early Host Body Reactions to the Bioactive and Bio-Inert Porous Scaffolds

    PubMed Central

    Ehashi, Tomo; Takemura, Taro; Hanagata, Nobutaka; Minowa, Takashi; Kobayashi, Hisatoshi; Ishihara, Kazuhiko; Yamaoka, Tetsuji

    2014-01-01

    To design scaffolds for tissue regeneration, details of the host body reaction to the scaffolds must be studied. Host body reactions have been investigated mainly by immunohistological observations for a long time. Despite of recent dramatic development in genetic analysis technologies, genetically comprehensive changes in host body reactions are hardly studied. There is no information about host body reactions that can predict successful tissue regeneration in the future. In the present study, porous polyethylene scaffolds were coated with bioactive collagen or bio-inert poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB) and were implanted subcutaneously and compared the host body reaction to those substrates by normalizing the result using control non-coat polyethylene scaffold. The comprehensive analyses of early host body reactions to the scaffolds were carried out using a DNA microarray assay. Within numerous genes which were expressed differently among these scaffolds, particular genes related to inflammation, wound healing, and angiogenesis were focused upon. Interleukin (IL)-1β and IL-10 are important cytokines in tissue responses to biomaterials because IL-1β promotes both inflammation and wound healing and IL-10 suppresses both of them. IL-1β was up-regulated in the collagen-coated scaffold. Collagen-specifically up-regulated genes contained both M1- and M2-macrophage-related genes. Marked vessel formation in the collagen-coated scaffold was occurred in accordance with the up-regulation of many angiogenesis-inducible factors. The DNA microarray assay provided global information regarding the host body reaction. Interestingly, several up-regulated genes were detected even on the very bio-inert PMB-coated surfaces and those genes include inflammation-suppressive and wound healing-suppressive IL-10, suggesting that not only active tissue response but also the inert response may relates to these genetic regulations. PMID:24454803

  13. 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 effect and fewer adverse side effects than direct intraperitoneal injection of ADM. The ADM-PLGA-NHAC developed in this study exhibited excellent extended-release drug properties, bone repairing and antineoplastic efficacy, which make it a promising osteoconductivity material with the capability to inhibit osteosarcoma. PMID:26975746

  14. Osteogenic Differentiation of Human Mesenchymal Stem Cells in 3-D Zr-Si Organic-Inorganic Scaffolds Produced by Two-Photon Polymerization Technique

    PubMed Central

    Koroleva, Anastasia; Deiwick, Andrea; Nguyen, Alexander; Schlie-Wolter, Sabrina; Narayan, Roger; Timashev, Peter; Popov, Vladimir; Bagratashvili, Viktor; Chichkov, Boris

    2015-01-01

    Two-photon polymerization (2PP) is applied for the fabrication of 3-D Zr-Si scaffolds for bone tissue engineering. Zr-Si scaffolds with 150, 200, and 250 μm pore sizes are seeded with human bone marrow stem cells (hBMSCs) and human adipose tissue derived stem cells (hASCs) and cultured in osteoinductive and control media for three weeks. Osteogenic differentiation of hASCs and hBMSCs and formation of bone matrix is comparatively analyzed via alkaline phosphatase activity (ALP), calcium quantification, osteocalcin staining and scanning electron microscopy (SEM). It is observed that the 150 μm pore size Zr-Si scaffolds support the strongest matrix mineralization, as confirmed by calcium deposition. Analysis of ALP activity, osteocalcin staining and SEM observations of matrix mineralization reveal that mesenchymal stem cells cultured on 3-D scaffolds without osteogenic stimulation spontaneously differentiate towards osteogenic lineage. Nanoindentation measurements show that aging of the 2PP-produced Zr-Si scaffolds in aqueous or alcohol media results in an increase in the scaffold Young’s modulus and hardness. Moreover, accelerated formation of bone matrix by hASCs is noted, when cultured on the scaffolds with lower Young’s moduli and hardness values (non aged scaffolds) compared to the cells cultured on scaffolds with higher Young’s modulus and hardness values (aged scaffolds). Presented results support the potential application of Zr-Si scaffolds for autologous bone tissue engineering. PMID:25706270

  15. Label-Free Optical Detection of Peptide Synthesis on a Porous Silicon Scaffold/Sensor

    PubMed Central

    Furbert, Patrick; Lu, Caiyan; Winograd, Nicholas; DeLouise, Lisa

    2008-01-01

    Mesoporous porous silicon (PSi) microcavity sensors are used to conduct conventional solid-phase peptide synthesis. The sensor optical response provides a convenient means to monitor the synthesis reaction in a nondestructive manner. Measurements indicate that peptide synthesis occurs only when the PSi sensor/scaffold is amine-terminated using, for example, the amino silane or deprotected acid-labile Rink linker. Equivalent coupling efficiencies of the first amino acid to both amine terminations are observed. Kinetic studies indicate that coupling reactions are 90% complete in 1 h. Quantitative analysis of the optical response following the synthesis of homo-oligopeptides (4-mers) suggests that coupling efficiencies and/or optical thickness changes depend on the peptide length. The synthesis of the cell adhesive oligopeptide (RGD) was monitored by the optical sensor response and validated by the cell culture of primary dermal fibroblasts. Secondary ion mass spectrometry (SIMS) analysis successfully detected peptide on the silicon wafer adjacent to the PSi. Our findings suggest the potential to exploit the high surface area, efficient coupling, and intrinsic optical detection properties of PSi for label-free high-throughput screening. PMID:18247639

  16. Image-Based Three-Dimensional Analysis to Characterize the Texture of Porous Scaffolds

    PubMed Central

    Pennella, Francesco; Gallo, Diego; Ciardelli, Gianluca; Bignardi, Cristina; Audenino, Alberto; Morbiducci, Umberto

    2014-01-01

    The aim of the present study is to characterize the microstructure of composite scaffolds for bone tissue regeneration containing different ratios of chitosan/gelatin blend and bioactive glasses. Starting from realistic 3D models of the scaffolds reconstructed from micro-CT images, the level of heterogeneity of scaffold architecture is evaluated performing a lacunarity analysis. The results demonstrate that the presence of the bioactive glass component affects not only macroscopic features such as porosity, but mainly scaffold microarchitecture giving rise to structural heterogeneity, which could have an impact on the local cell-scaffold interaction and scaffold performances. The adopted approach allows to investigate the scale-dependent pore distribution within the scaffold and the related structural heterogeneity features, providing a comprehensive characterization of the scaffold texture. PMID:24995272

  17. Image-based three-dimensional analysis to characterize the texture of porous scaffolds.

    PubMed

    Massai, Diana; Pennella, Francesco; Gentile, Piergiorgio; Gallo, Diego; Ciardelli, Gianluca; Bignardi, Cristina; Audenino, Alberto; Morbiducci, Umberto

    2014-01-01

    The aim of the present study is to characterize the microstructure of composite scaffolds for bone tissue regeneration containing different ratios of chitosan/gelatin blend and bioactive glasses. Starting from realistic 3D models of the scaffolds reconstructed from micro-CT images, the level of heterogeneity of scaffold architecture is evaluated performing a lacunarity analysis. The results demonstrate that the presence of the bioactive glass component affects not only macroscopic features such as porosity, but mainly scaffold microarchitecture giving rise to structural heterogeneity, which could have an impact on the local cell-scaffold interaction and scaffold performances. The adopted approach allows to investigate the scale-dependent pore distribution within the scaffold and the related structural heterogeneity features, providing a comprehensive characterization of the scaffold texture. PMID:24995272

  18. Preparation of porous 45S5 Bioglass-derived glass-ceramic scaffolds by using rice husk as a porogen additive.

    PubMed

    Wu, Shih-Ching; Hsu, Hsueh-Chuan; Hsiao, Sheng-Hung; Ho, Wen-Fu

    2009-06-01

    Bioactive glass is currently regarded as the most biocompatible material in the bone regeneration field because of its bioactivity, osteoconductivity and even osteoinductivity. In the present work porous glass-ceramic scaffolds, which were prepared from the 45S5 Bioglass by foaming with rice husks and sintering at 1050 degrees C for 1 h, have been developed. The produced scaffolds were characterized for their morphology, properties and bioactivity. Micrographs taken using a scanning electron microscope (SEM) were used for analysis of macropores, mesopores and micropores, respectively. The bioactivity of the porous glass-ceramic scaffolds was investigated using simulated body fluid (SBF) and characterized by SEM, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). A great potential scaffold that provides sufficient mechanical support temporarily while maintaining bioactivity, and that can biodegrade at later stages is achievable with the developed 45S5 Bioglass-derived scaffolds. PMID:19160020

  19. Conceptual design of large surface area porous polymeric hybrid media based on polyhedral oligomeric silsesquioxane precursors: preparation, tailoring of porous properties, and internal surface functionalization.

    PubMed

    Alves, Filipa; Scholder, Pascal; Nischang, Ivo

    2013-04-10

    We report on the preparation of hybrid, organic-inorganic porous materials derived from polyhedral oligomeric vinylsilsesquioxanes (vinylPOSS) via a single-step molding process. The monolithic, large surface area materials are studied with a particular focus on morphology and porous properties. Radical vinyl polymerization of the nanometer-sized POSS building blocks is therefore utilized via a thermally initiated route and in porogenic diluents such as tetrahydrofuran and polyethylene glycols of varying composition. Careful choice of these porogenic solvents and proper choice of initiator concentration lead to highly porous monolithic building entities which show a rigid, 3D-adhered, porous structure, macroscopically adapting the shape of a given mold. The described materials reflect Brunauer-Emmett-Teller (BET) surface areas of 700 m2/g or more and maximum tunable mesopore volumes of up to 2 cm3/g. Experimental investigations demonstrate the option to tailor nanoporosity and macroporosity in the single-step free-radical polymerization process. While studies on the influence of the used porogenic solvents reveal tuneability of pore sizes due to the unique pore formation process, tailored existence of residual vinyl groups allows facile postpolymerization modification of the highly porous, large surface area hybrid materials exploited via thiol-ene "click" chemistry. Our developed, simply realizable preparation process explores a new route to derive porous organic-inorganic hybrid adsorbents for a wide variety of applications such as extraction, separation science, and catalysis. PMID:23489022

  20. Conceptual Design of Large Surface Area Porous Polymeric Hybrid Media Based on Polyhedral Oligomeric Silsesquioxane Precursors: Preparation, Tailoring of Porous Properties, and Internal Surface Functionalization

    PubMed Central

    2013-01-01

    We report on the preparation of hybrid, organic–inorganic porous materials derived from polyhedral oligomeric vinylsilsesquioxanes (vinylPOSS) via a single-step molding process. The monolithic, large surface area materials are studied with a particular focus on morphology and porous properties. Radical vinyl polymerization of the nanometer-sized POSS building blocks is therefore utilized via a thermally initiated route and in porogenic diluents such as tetrahydrofuran and polyethylene glycols of varying composition. Careful choice of these porogenic solvents and proper choice of initiator concentration lead to highly porous monolithic building entities which show a rigid, 3D-adhered, porous structure, macroscopically adapting the shape of a given mold. The described materials reflect Brunauer–Emmett–Teller (BET) surface areas of 700 m2/g or more and maximum tunable mesopore volumes of up to 2 cm3/g. Experimental investigations demonstrate the option to tailor nanoporosity and macroporosity in the single-step free-radical polymerization process. While studies on the influence of the used porogenic solvents reveal tuneability of pore sizes due to the unique pore formation process, tailored existence of residual vinyl groups allows facile postpolymerization modification of the highly porous, large surface area hybrid materials exploited via thiol–ene “click” chemistry. Our developed, simply realizable preparation process explores a new route to derive porous organic–inorganic hybrid adsorbents for a wide variety of applications such as extraction, separation science, and catalysis. PMID:23489022

  1. Improvement of Distribution and Osteogenic Differentiation of Human Mesenchymal Stem Cells by Hyaluronic Acid and ?-Tricalcium Phosphate-Coated Polymeric Scaffold In Vitro

    PubMed Central

    Chen, Muwan; Le, Dang Q.S.; Kjems, Jrgen; Bnger, Cody; Lysdahl, Helle

    2015-01-01

    Abstract Bone tissue engineering requires a well-designed scaffold that can be biodegradable, biocompatible, and support the stem cells to osteogenic differentiation. Porous polycaprolactone (PCL) scaffold prepared by fused deposition modeling is an attractive biomaterial that has been used in clinic. However, PCL scaffolds lack biological function and osteoinductivity. In this study, we functionalized the PCL scaffolds by embedding them with a matrix of hyaluronic acid/?-tricalcium phosphate (HA/TCP). Human mesenchymal stem cells (MSCs) were cultured on scaffolds with and without coating to investigate proliferation and osteogenic differentiation. The DNA amount was significantly higher in the HA/TCP-coated scaffold on day 21. At the gene expression level, HA/TCP coating significantly increased the expression of ALP and COLI on day 4. These data correlated with the ALP activity peaking on day 7 in the HA/TCP-coated scaffold. Scanning electron microscope and histological analysis revealed that the cell matrix and calcium deposition were distributed more uniformly in the coated scaffolds compared to scaffolds without coating. In conclusion, the HA/TCP coating improved cellular proliferation, osteogenic differentiation, and uniform distribution of the cellular matrix in vitro. The HA/TCP-PCL scaffold holds great promise to accommodate human bone marrow-derived MSCs for bone reconstruction purposes, which warrants future in vivo studies. PMID:26487981

  2. Preparation and characterization of highly porous, biodegradable polyurethane scaffolds for soft tissue applications

    PubMed Central

    Guan, Jianjun; Fujimoto, Kazuro L.; Sacks, Michael S.; Wagner, William R.

    2010-01-01

    In the engineering of soft tissues, scaffolds with high elastance and strength coupled with controllable biodegradable properties are necessary. To fulfill such design criteria we have previously synthesized two kinds of biodegradable polyurethaneureas, namely poly(ester urethane)urea (PEUU) and poly(ether ester urethane)urea (PEEUU) from polycaprolactone, polycaprolactone-b-polyethylene glycol-b-polycaprolactone, 1,4-diisocyanatobutane and putrescine. PEUU and PEEUU were further fabricated into scaffolds by thermally induced phase separation using dimethyl sulfoxide (DMSO) as a solvent. The effect of polymer solution concentration, quenching temperature and polymer type on pore morphology and porosity was investigated. Scaffolds were obtained with open and interconnected pores having sizes ranging from several ?m to more than 150 ?m and porosities of 8097%. By changing the polymer solution concentration or quenching temperature, scaffolds with random or oriented tubular pores could be obtained. The PEUU scaffolds were flexible with breaking strains of 214% and higher, and tensile strengths of approximately 1.0 MPa, whereas the PEEUU scaffolds generally had lower strengths and breaking strains. Scaffold degradation in aqueous buffer was related to the porosity and polymer hydrophilicity. Smooth muscle cells were filtration seeded in the scaffolds and it was shown that both scaffolds supported cell adhesion and growth, with smooth muscle cells growing more extensively in the PEEUU scaffold. These biodegradable and flexible scaffolds demonstrate potential for future application as cell scaffolds in cardiovascular tissue engineering or other soft tissue applications. PMID:15626443

  3. 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%, 145μm and 1.5MPa for TNaOH and TEtOH and 94%, 110μm and 1.8MPa for CTPP, respectively. Stabilization maintained the integrity of the SPCHTs for at least 10days 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. PMID:26706561

  4. Polymeric vs hydroxyapatite-based scaffolds on dental pulp stem cell proliferation and differentiation

    PubMed Central

    Khojasteh, Arash; Motamedian, Saeed Reza; Rad, Maryam Rezai; Shahriari, Mehrnoosh Hasan; Nadjmi, Nasser

    2015-01-01

    AIM: To evaluate adhesion, proliferation and differentiation of human dental pulp stem cells (hDPSCs) on four commercially available scaffold biomaterials. METHODS: hDPSCs were isolated from human dental pulp tissues of extracted wisdom teeth and established in stem cell growth medium. hDPSCs at passage 3-5 were seeded on four commercially available scaffold biomaterials, SureOss (Allograft), Cerabone (Xenograft), PLLA (Synthetic), and OSTEON II Collagen (Composite), for 7 and 14 d in osteogenic medium. Cell adhesion and morphology to the scaffolds were evaluated by scanning electron microscopy (SEM). Cell proliferation and differentiation into osteogenic lineage were evaluated using DNA counting and alkaline phosphatase (ALP) activity assay, respectively. RESULTS: All scaffold biomaterials except SureOss (Allograft) supported hDPSC adhesion, proliferation and differentiation. hDPSCs seeded on PLLA (Synthetic) scaffold showed the highest cell proliferation and attachment as indicated with both SEM and DNA counting assay. Evaluating the osteogenic differentiation capability of hDPSCs on different scaffold biomaterials with ALP activity assay showed high level of ALP activity on cells cultured on PLLA (Synthetic) and OSTEON II Collagen (Composite) scaffolds. SEM micrographs also showed that in the presence of Cerabone (Xenograft) and OSTEON II Collagen (Composite) scaffolds, the hDPSCs demonstrated the fibroblastic phenotype with several cytoplasmic extension, while the cells on PLLA scaffold showed the osteoblastic-like morphology, round-like shape. CONCLUSION: PLLA scaffold supports adhesion, proliferation and osteogenic differentiation of hDPSCs. Hence, it may be useful in combination with hDPSCs for cell-based reconstructive therapy. PMID:26640621

  5. Effect of cryomilling times on the resultant properties of porous biodegradable poly(e-caprolactone)/poly(glycolic acid) scaffolds for articular cartilage tissue engineering.

    PubMed

    Jonnalagadda, John B; Rivero, Iris V

    2014-12-01

    The aim of this research is to develop a parametric investigation of the fabrication of poly(e-caprolactone) (PCL)/poly(glycolic acid) (PGA) scaffolds to decipher the influence of cryomilling time on the scaffolds' resultant physical, morphological and mechanical characteristics. Scaffolds were fabricated via solid-state cryomilling to prepare a homogeneous blend along with conventional compression molding and porogen leaching yielding interconnected porous scaffolds. PCL/PGA scaffolds fabricated through this technique demonstrated high porosity at all cryomilling times. Morphological analysis revealed a co-continuous interconnected pore network. While mean pore size decreased, water uptake and compressive properties increased with increasing cryomilling times. Porous scaffolds cryomilled for 12min exhibited a mean pore size within the optimal range for tissue engineering and chondrocyte ingrowth. And the compressive modulus of scaffolds cryomilled for 12, 30 and 60min matched the compressive modulus of human articular cartilage. In addition, scaffolds exhibited water uptake, a key requirement in tissue engineering. A 60 day in vitro degradation study revealed mass loss starting from day 10 and increasing through day 60, while notable reduction in compressive properties was observed. The results indicated that cryomilling times affected the resultant properties of PCL/PGA scaffolds and will be interesting candidates for articular cartilage tissue engineering. PMID:25194523

  6. Comparative study of silk fibroin porous scaffolds derived from salt/water and sucrose/hexafluoroisopropanol in cartilage formation.

    PubMed

    Makaya, Kumiko; Terada, Shinichi; Ohgo, Kosuke; Asakura, Tetsuo

    2009-07-01

    The purpose of this study is to create a new silk fibroin scaffold with sufficient three-dimensional morphology and porous structure for cartilage formation. We have applied sucrose particles sized around 300 to 500 microm as porogens compared to equal-sized salt particles. After the porogen was leached out with water, scaffolds were prepared with fibroin derived from sucrose/hexafluoroisopropanol (Su/H) or salt/water (Sa/W) based composites. A compression test indicated that the Sa/W fibroin was much harder than the Su/H fibroin, but a protease enzyme digested the Sa/W fibroin more quickly than Su/H fibroin. Rabbit ear chondrocytes were seeded onto the scaffolds for 4-8 week in vitro culture and histological analyses were performed. The distribution of cartilage formation in Safranin O staining was more homogenous in Su/H fibroin than that of Sa/W fibroin. The overall amount of cartilage was significantly better in the Su/H fibroin than that in the Sa/W fibroin. However, the inner structure of pore wall in the Sa/W fibroin was rough and microporous with cartilage matrix deposition, while that in the Su/H fibroin was thin and homogenous. Since mature cartilage gradually regenerates to fill the porous space, slowly degradable Su/H fibroin should be a better candidate for cartilage formation. PMID:19577196

  7. Ingrowth of Human Mesenchymal Stem Cells into Porous Silk Particle Reinforced Silk Composite Scaffolds: An In Vitro Study

    PubMed Central

    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

    2010-01-01

    Silk fibroin protein is biodegradable and biocompatible, exhibiting excellent mechanical properties for various biomedical applications. However, porous 3D 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 (nonreinforced) 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 six weeks. The calcium adsorption increased dramatically with increasing loading, as observed from biochemical assays, histological staining, and microCT (?CT) analysis. Specifically, calcium content in the scaffolds increased by 0.57, 0.71, and 1.27 mg (per ?g 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, ?CT imaging revealed that at 6 weeks, bone volume fraction increased from 0.78% for nonreinforced 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 3D in vitro differentiation capabilities of hMSCs, providing a means to improve osteogenic outcomes. PMID:20656075

  8. 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 (?CT) analysis. Specifically, calcium content in the scaffolds increased by 0.57, 0.71, and 1.27 mg (per ?g 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, ?CT 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. PMID:20656075

  9. Novel biodegradable poly(propylene fumarate)-co-poly(l-lactic acid) porous scaffolds fabricated by phase separation for tissue engineering applications

    PubMed Central

    Liu, Xifeng; Miller, A. Lee; Waletzki, Brian E.; Yaszemski, Michael J.

    2015-01-01

    Scaffolds with intrinsically interconnected porous structures are highly desirable in tissue engineering and regenerative medicine. In this study, three-dimensional polymer scaffolds with highly interconnected porous structures were fabricated by thermally induced phase separation of novel synthesized biodegradable poly(propylene fumarate)-co-poly(l-lactic acid) in a dioxane/water binary system. Defined porous scaffolds were achieved by optimizing conditions to attain interconnected porous structures. The effect of phase separation parameters on scaffold morphology were investigated, including polymer concentration (1, 3, 5, 7, and 9%), quench time (1, 4, and 8 min), dioxane/water ratio (83/17, 85/15, and 87/13 wt/wt), and freeze temperature (−20, −80, and −196 °C). Interesting pore morphologies were created by adjusting these processing parameters, e.g., flower-shaped (5%; 85/15; 1 min; −80 °C), spherulite-like (5%; 85/15; 8 min; −80 °C), and bead-like (5%; 87/13; 1 min; −80 °C) morphology. Modulation of phase separation conditions also resulted in remarkable differences in scaffold porosities (81% to 91%) and thermal properties. Furthermore, scaffolds with varied mechanic strengths, degradation rates, and protein adsorption capabilities could be fabricated using the phase separation method. In summary, this work provides an effective route to generate multi-dimensional porous scaffolds that can be applied to a variety of hydrophobic polymers and copolymers. The generated scaffolds could potentially be useful for various tissue engineering applications including bone tissue engineering. PMID:26989483

  10. Preparation of three-layered porous PLA/PEG scaffold: relationship between morphology, mechanical behavior and cell permeability.

    PubMed

    Scaffaro, R; Lopresti, F; Botta, L; Rigogliuso, S; Ghersi, G

    2016-02-01

    Interface tissue engineering (ITE) is used to repair or regenerate interface living tissue such as for instance bone and cartilage. This kind of tissues present natural different properties from a biological and mechanical point of view. With the aim to imitating the natural gradient occurring in the bone-cartilage tissue, several technologies and methods have been proposed over recent years in order to develop polymeric functionally graded scaffolds (FGS). In this study three-layered scaffolds with a pore size gradient were developed by melt mixing polylactic acid (PLA) and two water-soluble porogen agents: sodium chloride (NaCl) and polyethylene glycol (PEG). Pore dimensions were controlled by NaCl granulometry while PEG solvation created a micropores network within the devices. Scaffolds were characterized from a morphological and mechanical point of view in order to find a correlation between the preparation method, the pore architecture and compressive mechanical behavior. Biological tests were also performed in order to study the effect of pore size gradient on the permeation of different cell lines in co-culture. To imitate the physiological work condition, compressive tests were also performed in phosphate buffered saline (PBS) solution at 37C. The presented preparation method permitted to prepare three-layered scaffolds with high control of porosity and pore size distribution. Furthermore mechanical behaviors were found to be strongly affected by pore architecture of tested devices as well as the permeation of osteoblast and fibroblast in-vitro. PMID:26410761

  11. The generation of biomolecular patterns in highly porous collagen-GAG scaffolds using direct photolithography.

    PubMed

    Martin, Teresa A; Caliari, Steven R; Williford, Paul D; Harley, Brendan A; Bailey, Ryan C

    2011-06-01

    The extracellular matrix (ECM) is a complex organization of structural proteins found within tissues and organs. Heterogeneous tissues with spatially and temporally modulated properties play an important role in organism physiology. Here we present a benzophenone (BP) based direct, photolithographic approach to spatially pattern solution phase biomolecules within collagen-GAG (CG) scaffolds and demonstrate creation of a wide range of patterns composed of multiple biomolecular species in a manner independent from scaffold fabrication steps. We demonstrate the ability to immobilize biomolecules at surface densities of up to 1000 ligands per square micron on the scaffold strut surface and to depths limited by the penetration depth of the excitation source into the scaffold structure. Importantly, while BP photopatterning does further crosslink the CG scaffold, evidenced by increased mechanical properties and collagen crystallinity, it does not affect scaffold microstructural or compositional properties or negatively influence cell adhesion, viability, or proliferation. We show that covalently photoimmobilized fibronectin within a CG scaffold significantly increases the speed of MC3T3-E1 cell attachment relative to the bare CG scaffold or non-specifically adsorbed fibronectin, suggesting that this approach can be used to improve scaffold bioactivity. Our findings, on the whole, establish the use of direct, BP photolithography as a methodology for covalently incorporating activity-improving biochemical cues within 3D collagen biomaterial scaffolds with spatial control over biomolecular deposition. PMID:21397322

  12. Microfabrication of complex porous tissue engineering scaffolds using 3D projection stereolithography

    PubMed Central

    Gauvin, Robert; Chen, Ying-Chieh; Lee, Jin Woo; Soman, Pranav; Zorlutuna, Pinar; Nichol, Jason W.; Bae, Hojae; Chen, Shaochen; Khademhosseini, Ali

    2013-01-01

    The success of tissue engineering will rely on the ability to generate complex, cell seeded three-dimensional (3D) structures. Therefore, methods that can be used to precisely engineer the architecture and topography of scaffolding materials will represent a critical aspect of functional tissue engineering. Previous approaches for 3D scaffold fabrication based on top-down and process driven methods are often not adequate to produce complex structures due to the lack of control on scaffold architecture, porosity, and cellular interactions. The proposed projection stereolithography (PSL) platform can be used to design intricate 3D tissue scaffolds that can be engineered to mimic the microarchitecture of tissues, based on computer aided design (CAD). The PSL system was developed, programmed and optimized to fabricate 3D scaffolds using gelatin methacrylate (GelMA). Variation of the structure and prepolymer concentration enabled tailoring the mechanical properties of the scaffolds. A dynamic cell seeding method was utilized to improve the coverage of the scaffold throughout its thickness. The results demonstrated that the interconnectivity of pores allowed for uniform human umbilical vein endothelial cells (HUVECs) distribution and proliferation in the scaffolds, leading to high cell density and confluency at the end of the culture period. Moreover, immunohistochemistry results showed that cells seeded on the scaffold maintained their endothelial phenotype, demonstrating the biological functionality of the microfabricated GelMA scaffolds. PMID:22365811

  13. The generation of biomolecular patterns in highly porous collagen-GAG scaffolds using direct photolithography

    PubMed Central

    Martin, Teresa A.; Caliari, Steven R.; Williford, Paul D.; Harley, Brendan A.; Bailey, Ryan C.

    2014-01-01

    The extracellular matrix (ECM) is a complex organization of structural proteins found within tissues and organs. Heterogeneous tissues with spatially and temporally modulated properties play an important role in organism physiology. Here we present a benzophenone (BP) based direct, photolithographic approach to spatially pattern solution phase biomolecules within collagen-GAG (CG) scaffolds and demonstrate creation of a wide range of patterns composed of multiple biomolecular species in a manner independent from scaffold fabrication steps. We demonstrate the ability to immobilize biomolecules at surface densities of up to 1000 ligands per square micron on the scaffold strut surface and to depths limited by the penetration depth of the excitation source into the scaffold structure. Importantly, while BP photopatterning does further crosslink the CG scaffold, evidenced by increased mechanical properties and collagen crystallinity, it does not affect scaffold microstructural or compositional properties or negatively influence cell adhesion, viability, or proliferation. We show that covalently photoimmobilized fibronectin within a CG scaffold significantly increases the speed of MC3T3-E1 cell attachment relative to the bare CG scaffold or non-specifically adsorbed fibronectin, suggesting that this approach can be used to improve scaffold bioactivity. Our findings, on the whole, establish the use of direct, BP photolithography as a methodology for covalently incorporating activity-improving biochemical cues within 3D collagen biomaterial scaffolds with spatial control over biomolecular deposition. PMID:21397322

  14. Microfabrication of complex porous tissue engineering scaffolds using 3D projection stereolithography.

    PubMed

    Gauvin, Robert; Chen, Ying-Chieh; Lee, Jin Woo; Soman, Pranav; Zorlutuna, Pinar; Nichol, Jason W; Bae, Hojae; Chen, Shaochen; Khademhosseini, Ali

    2012-05-01

    The success of tissue engineering will rely on the ability to generate complex, cell seeded three-dimensional (3D) structures. Therefore, methods that can be used to precisely engineer the architecture and topography of scaffolding materials will represent a critical aspect of functional tissue engineering. Previous approaches for 3D scaffold fabrication based on top-down and process driven methods are often not adequate to produce complex structures due to the lack of control on scaffold architecture, porosity, and cellular interactions. The proposed projection stereolithography (PSL) platform can be used to design intricate 3D tissue scaffolds that can be engineered to mimic the microarchitecture of tissues, based on computer aided design (CAD). The PSL system was developed, programmed and optimized to fabricate 3D scaffolds using gelatin methacrylate (GelMA). Variation of the structure and prepolymer concentration enabled tailoring the mechanical properties of the scaffolds. A dynamic cell seeding method was utilized to improve the coverage of the scaffold throughout its thickness. The results demonstrated that the interconnectivity of pores allowed for uniform human umbilical vein endothelial cells (HUVECs) distribution and proliferation in the scaffolds, leading to high cell density and confluency at the end of the culture period. Moreover, immunohistochemistry results showed that cells seeded on the scaffold maintained their endothelial phenotype, demonstrating the biological functionality of the microfabricated GelMA scaffolds. PMID:22365811

  15. In vitro and in vivo evaluation of biodegradable, open-porous scaffolds made of sintered magnesium W4 short fibres.

    PubMed

    Bobe, K; Willbold, E; Morgenthal, I; Andersen, O; Studnitzky, T; Nellesen, J; Tillmann, W; Vogt, C; Vano, K; Witte, F

    2013-11-01

    A cytocompatible and biocompatible, degradable, open-porous, mechanically adaptable metal scaffold made of magnesium alloy W4 melt-extracted short fibres was fabricated by liquid phase sintering. Cylindrical samples (35 mm) of sintered W4 short fibres were evaluated under in vitro (L929, HOB, eudiometer, weight loss) and in vivo conditions (rabbits: 6 and 12 weeks). The in vitro corrosion environment (e.g., temperature, flow, composition of corrosion solution, exposure time) significantly influenced the corrosion rates of W4 scaffolds compared with corrosion in vivo. Corrosion rates under cell culture conditions for 72 h varied from 1.05 to 3.43 mm y(-1) depending on the media composition. Corrosion rates measured in eudiometric systems for 24 h were ~24-27 times higher (3.88-4.43 mm y(-1)) than corrosion in vivo after 6 weeks (0.16 mm y(-1)). Moreover, it was found that the cell culture media composition significantly influences the ionic composition of the extract by selectively dissolving ions from W4 samples or their corrosion products. A pilot in vivo study for 6 and 12 weeks demonstrated active bone remodelling, no foreign body reaction and no clinical observation of gas formation during W4 scaffold implantation. Long-term in vivo studies need to be conducted to prove complete degradation of the W4 scaffold and total replacement by the host tissue. PMID:23542554

  16. Improving osteointegration and osteogenesis of three-dimensional porous Ti6Al4V scaffolds by polydopamine-assisted biomimetic hydroxyapatite coating.

    PubMed

    Li, Yong; Yang, Wei; Li, Xiaokang; Zhang, Xing; Wang, Cairu; Meng, Xiangfei; Pei, Yifeng; Fan, Xiangli; Lan, Pingheng; Wang, Chunhui; Li, Xiaojie; Guo, Zheng

    2015-03-18

    Titanium alloys with various porous structures can be fabricated by advanced additive manufacturing techniques, which are attractive for use as scaffolds for bone defect repair. However, modification of the scaffold surfaces, particularly inner surfaces, is critical to improve the osteointegration of these scaffolds. In this study, a biomimetic approach was employed to construct polydopamine-assisted hydroxyapatite coating (HA/pDA) onto porous Ti6Al4V scaffolds fabricated by the electron beam melting method. The surface modification was characterized with the field emission scanning electron microscopy, energy dispersive spectroscopy, water contact angle measurement, and confocal laser scanning microscopy. Attachment and proliferation of MC3T3-E1 cells on the scaffold surface were significantly enhanced by the HA/pDA coating compared to the unmodified surfaces. Additionally, MC3T3-E1 cells grown on the HA/pDA-coated Ti6Al4V scaffolds displayed significantly higher expression of runt-related transcription factor-2, alkaline phosphatase, osteocalcin, osteopontin, and collagen type-1 compared with bare Ti6Al4V scaffolds after culture for 14 days. Moreover, microcomputed tomography analysis and Van-Gieson staining of histological sections showed that HA/pDA coating on surfaces of porous Ti6Al4V scaffolds enhanced osteointegration and significantly promoted bone regeneration after implantation in rabbit femoral condylar defects for 4 and 12 weeks. Therefore, this study provides an alternative to biofunctionalized porous Ti6Al4V scaffolds with improved osteointegration and osteogenesis functions for orthopedic applications. PMID:25711714

  17. A simple method for the synthesis of porous polymeric vesicles and their application as MR contrast agents

    PubMed Central

    Yan, Lesan; Higbee, Elizabeth; Tsourkas, Andrew

    2015-01-01

    Because of their low membrane permeability the use of polymeric vesicles in certain drug delivery and molecular imaging applications and as bioreactors is less than ideal. Here, we report a simple method to prepare porous polymeric vesicles that possess high membrane permeability. Specifically, porous vesicles were produced from the aqueous assembly of the diblock copolymer PEG-PBD, and the triblock copolymer PEG-PPO-PEG. It was found that PEG-PPO-PEG-doped polymersomes exhibited improved membrane permeability to molecules less than 5 kDa. Further, these porous vesicles retained molecules ≥10 kDa within their aqueous interiors with no significant leakage. To demonstrate its application, highly efficient magnetic resonance contrast agents were produced from porous polymersomes by encapsulating macromolecules labeled with gadolinium. Due to a fast water exchange rate with surrounding bulk water, these paramagnetic porous polymersomes exhibited higher r1 relaxivity compared with Gd-encapsulated vesicles with no pores. Due to their simplicity, the porous polymersomes prepared with this method are expected to have additional useful applications. PMID:26693022

  18. Synthesis of porous zirconia spheres for HPLC by polymerization-induced colloid aggregation (PICA)

    SciTech Connect

    Sun, L.; Annen, M.J.; Lorenzano-Porras, F.; Carr, P.W.; McCormick, A.V. )

    1994-03-15

    Porous, spherical zirconia particles with a narrow particle size distribution, which are useful as chromatographic packing materials for high performance liquid chromatography (HPLC), were synthesized by polymerization-induced colloid aggregation (PICA) first described by Iler and McQueston (US Patent 4,010,242, 1977.) and the effects of a number of crucial processing variables were examined. In this method, an aqueous zirconia sol consisting of 700 [angstrom] (mean diameter) particles is mixed with urea and formaldehyde polymer adsorbs onto the ZrO[sub 2] colloids, entraining the colloids in the precipitation of the polymer gel and thus alloying the colloids to aggregate. Features of the aggregation process are elucidated from responses of the process to variations in temperature, reaction mixture composition, and solvent polarity. Results suggest that the aggregation process resembles those reported for the bridging flocculation of colloids by adsorbed polymers. Porous zirconia particles obtained after polymer combustion and sintering of the aggregates are 3.5 [mu]m in diameter with a surface area of 13 m[sup 2]/g, a porosity of 29% and pores ranging from <50 to 350 [angstrom] in diameter. The particles are strong enough to withstand the packing of a HPLC column.

  19. Novel Modeling Approach to Generate a Polymeric Nanofiber Scaffold for Salivary Gland Cells

    PubMed Central

    Jean-Gilles, Riffard; Soscia, David; Sequeira, Sharon; Melfi, Michael; Gadre, Anand; Castracane, James; Larsen, Melinda

    2011-01-01

    Background Electrospun nanofibers have been utilized in many biomedical applications as biomimetics of extracellular matrix proteins that promote self-organization of cells into 3D tissue constructs. As progress towards an artificial salivary gland tissue construct, we prepared nanofiber scaffolds using PLGA, a biodegradable and biocompatible material. Method of Approach We used electrospinning to prepare nanofiber scaffolds using PLGA with both DMF and HFIP as solvents. Using a design of experiment (DOE) approach, system and process parameters were optimized concurrently and their effects on the diameter of the resulting fibers were computed into a single model. A transfer function was used to reproducibly produce nanofibers of a defined diameter, which was confirmed by SEM. The mouse salivary gland epithelial cell line, SIMS, was seeded on the nanofiber scaffolds, and morphology, cell proliferation, and viability were assayed. Results Varying two or more parameters simultaneously yielded trends diverging from the linear response predicted by previous studies. Comparison of two solvents revealed that the diameter of PLGA nanofibers generated using HFIP is less sensitive to changes in the system and process parameters than are fibers generated using DMF. Inclusion of NaCl reduced morphological inconsistencies and minimized process variability. The resulting nanofiber scaffolds supported attachment, survival and cell proliferation of a mouse salivary gland epithelial cell line. In comparison with glass and flat PLGA films, the nanofibers promoted self-organization of the salivary gland cells into 3D cell clusters, or aggregates. Conclusions These data indicate that nanofiber scaffolds promote salivary gland cell organization, and suggest that a nanofiber scaffold could provide a platform for engineering of an artificial salivary gland tissue construct. This study additionally provides a method for efficient production of nanofiber scaffolds for general application in tissue engineering. PMID:22229076

  20. Novel Modeling Approach to Generate a Polymeric Nanofiber Scaffold for Salivary Gland Cells.

    PubMed

    Jean-Gilles, Riffard; Soscia, David; Sequeira, Sharon; Melfi, Michael; Gadre, Anand; Castracane, James; Larsen, Melinda

    2010-08-01

    BACKGROUND: Electrospun nanofibers have been utilized in many biomedical applications as biomimetics of extracellular matrix proteins that promote self-organization of cells into 3D tissue constructs. As progress towards an artificial salivary gland tissue construct, we prepared nanofiber scaffolds using PLGA, a biodegradable and biocompatible material. METHOD OF APPROACH: We used electrospinning to prepare nanofiber scaffolds using PLGA with both DMF and HFIP as solvents. Using a design of experiment (DOE) approach, system and process parameters were optimized concurrently and their effects on the diameter of the resulting fibers were computed into a single model. A transfer function was used to reproducibly produce nanofibers of a defined diameter, which was confirmed by SEM. The mouse salivary gland epithelial cell line, SIMS, was seeded on the nanofiber scaffolds, and morphology, cell proliferation, and viability were assayed. RESULTS: Varying two or more parameters simultaneously yielded trends diverging from the linear response predicted by previous studies. Comparison of two solvents revealed that the diameter of PLGA nanofibers generated using HFIP is less sensitive to changes in the system and process parameters than are fibers generated using DMF. Inclusion of NaCl reduced morphological inconsistencies and minimized process variability. The resulting nanofiber scaffolds supported attachment, survival and cell proliferation of a mouse salivary gland epithelial cell line. In comparison with glass and flat PLGA films, the nanofibers promoted self-organization of the salivary gland cells into 3D cell clusters, or aggregates. CONCLUSIONS: These data indicate that nanofiber scaffolds promote salivary gland cell organization, and suggest that a nanofiber scaffold could provide a platform for engineering of an artificial salivary gland tissue construct. This study additionally provides a method for efficient production of nanofiber scaffolds for general application in tissue engineering. PMID:22229076

  1. Novel real function based method to construct heterogeneous porous scaffolds and additive manufacturing for use in medical engineering.

    PubMed

    Yang, Nan; Tian, Yanling; Zhang, Dawei

    2015-11-01

    Heterogeneous porous scaffolds have important applications in biomedical engineering, as they can mimic the structures of natural tissues to achieve the corresponding properties. Here, we introduce a new and easy to implement real function based method for constructing complex, heterogeneous porous structures, including hybrid structures, stochastic structures, functionally gradient structures, and multi-scale structures, or their combinations (e.g., hybrid multi-scale structures). Based on micro-CT data, a femur-mimetic structure with gradient morphology was constructed using our method and fabricated using stereolithography. Results showed that our method could generate gradient porosity or gradient specific surfaces and be sufficiently flexible for use with micro-CT data and additive manufacturing (AM) techniques. PMID:26320819

  2. Development of highly porous scaffolds based on bioactive silicates for dental tissue engineering

    SciTech Connect

    Goudouri, O.M.; Theodosoglou, E.; Kontonasaki, E.; Will, J.; Chrissafis, K.; Koidis, P.; Paraskevopoulos, K.M.; Boccaccini, A.R.

    2014-01-01

    Graphical abstract: - Highlights: • Synthesis of an Mg-based glass-ceramic via the sol–gel technique. • The heat treatment of the glass-ceramic promoted the crystallization of akermanite. • Akermanite scaffolds coated with gelatin were successfully fabricated. • An HCAp layer was developed on the surface of all scaffolds after 9 days in SBF. - Abstract: Various scaffolding materials, ceramics and especially Mg-based ceramic materials, including akermanite (Ca{sub 2}MgSi{sub 2}O{sub 7}) and diopside (CaMgSi{sub 2}O{sub 6}), have attracted interest for dental tissue regeneration because of their improved mechanical properties and controllable biodegradation. The aim of the present work was the synthesis of an Mg-based glass-ceramic, which would be used for the construction of workable akermanite scaffolds. The characterization of the synthesized material was performed by Fourier Transform Infrared Spectroscopy (FTIR) X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). Finally, the apatite forming ability of the scaffolds was assessed by immersion in simulated body fluid. The scaffolds were fabricated by the foam replica technique and were subsequently coated with gelatin to provide a functional surface for increased cell attachment. Finally, SEM microphotographs and FTIR spectra of the scaffolds after immersion in SBF solution indicated the inorganic bioactive character of the scaffolds suitable for the intended applications in dental tissue engineering.

  3. Preparation of tissue engineering porous scaffold with poly(lactic acid) and polyethylene glycol solution blend by solvent-casting/particulate-leaching

    NASA Astrophysics Data System (ADS)

    Huang, Ran; Zhu, Xiaomin; Zhao, Tingting; Wan, Ajun

    2014-12-01

    Polyethylene glycol/poly(lactic acid) solution blend is employed as the raw materials to prepare porous scaffold of potential usage in tissue engineering. The solution blend can be naturally introduced in the classical solvent casting/particular leaching technique in porous matrix preparation. The PEG presence is to modify the degradation behavior of scaffolds to fit particular requirements in tissue engineering. The porous matrix of PEG/PLA with various weight ratios are made with pores size 250 ? m. The SEM characterizations have been done to investigate the porous morphology of products, the results indicate that though with the clear semi-miscibility feature of PEG/PLA blends, the macro-structure is not significantly affected by the PEG content percentage. The degradation results show an enhanced weight loss rate with the presence of PEG as expected.

  4. A novel porous bioceramics scaffold by accumulating hydroxyapatite spherulites for large bone tissue engineering in vivo. II. Construct large volume of bone grafts.

    PubMed

    Zhi, Wei; Zhang, Cong; Duan, Ke; Li, Xiaohong; Qu, Shuxin; Wang, Jianxin; Zhu, Zhuoli; Huang, Peng; Xia, Tian; Liao, Ga; Weng, Jie

    2014-08-01

    In vivo engineering of bone autografts using bioceramic scaffolds with appropriate porous structures is a potential approach to prepare autologous bone grafts for the repair of critical-sized bone defects. This study investigated the evolutionary process of osteogenesis, angiogenesis, and compressive strength of bioceramic scaffolds implanted in two non-osseous sites of dogs: the abdominal cavity and the dorsal muscle. Hydroxyapatite (HA) sphere-accumulated scaffolds with controlled porous structures were prepared and placed in the two sites for up to 6 months. Analyses of retrieved scaffolds found that osteogenesis and angiogenesis were faster in scaffolds implanted in dorsal muscles compared with those placed in abdominal cavities. The abdominal cavity, however, can accommodate larger bone grafts with designed shape. Analyses of scaffolds implanted in abdominal cavities [an environment of a low mesenchymal stem cell (MSC) density] further demonstrated that angiogenesis play critical roles during osteogenesis in the scaffolds, presumably by supplying progenitor cells and/or MSCs as seed cells. This study also examined the relationship between the volume of bone grafts and the physiological environment of in vivo bioreactor. These results provide basic information for the selection of appropriate implanting sites and culture time required to engineer autologous bone grafts for the clinical bone defect repair. Based on these positive results, a pilot study has applied the grafts constructed in canine abdominal cavity to repair segmental bone defect in load-bearing sites (limbs). PMID:23946164

  5. An innovative method to obtain porous PLLA scaffolds with highly spherical and interconnected pores.

    PubMed

    Vaquette, Cédryck; Frochot, Céline; Rahouadj, Rachid; Wang, Xiong

    2008-07-01

    Scaffolding is an essential issue in tissue engineering and scaffolds should answer certain essential criteria: biocompatibility, high porosity, and important pore interconnectivity to facilitate cell migration and fluid diffusion. In this work, a modified solvent casting-particulate leaching out method is presented to produce scaffolds with spherical and interconnected pores. Sugar particles (200-300 microm and 300-500 microm) were poured through a horizontal Meker burner flame and collected below the flame. While crossing the high temperature zone, the particles melted and adopted a spherical shape. Spherical particles were compressed in plastic mold. Then, poly-L-lactic acid solution was cast in the sugar assembly. After solvent evaporation, the sugar was removed by immersing the structure into distilled water for 3 days. The obtained scaffolds presented highly spherical interconnected pores, with interconnection pathways from 10 to 100 mum. Pore interconnection was obtained without any additional step. Compression tests were carried out to evaluate the scaffold mechanical performances. Moreover, rabbit bone marrow mesenchymal stem cells were found to adhere and to proliferate in vitro in the scaffold over 21 days. This technique produced scaffold with highly spherical and interconnected pores without the use of additional organic solvents to leach out the porogen. PMID:18098188

  6. Accurate Fabrication of Hydroxyapatite Bone Models with Porous Scaffold Structures by Using Stereolithography

    NASA Astrophysics Data System (ADS)

    Maeda, Chiaki; Tasaki, Satoko; Kirihara, Soshu

    2011-05-01

    Computer graphic models of bioscaffolds with four-coordinate lattice structures of solid rods in artificial bones were designed by using a computer aided design. The scaffold models composed of acryl resin with hydroxyapatite particles at 45vol. % were fabricated by using stereolithography of a computer aided manufacturing. After dewaxing and sintering heat treatment processes, the ceramics scaffold models with four-coordinate lattices and fine hydroxyapatite microstructures were obtained successfully. By using a computer aided analysis, it was found that bio-fluids could flow extensively inside the sintered scaffolds. This result shows that the lattice structures will realize appropriate bio-fluid circulations and promote regenerations of new bones.

  7. Fabrication of three-dimensional porous scaffolds with controlled filament orientation and large pore size via an improved E-jetting technique.

    PubMed

    Li, Jin Lan; Cai, Yan Li; Guo, Yi Lin; Fuh, Jerry Ying Hsi; Sun, Jie; Hong, Geok Soon; Lam, Ruey Na; Wong, Yoke San; Wang, Wilson; Tay, Bee Yen; Thian, Eng San

    2014-05-01

    Biodegradable polymeric scaffolds have been widely used in tissue engineering as a platform for cell proliferation and subsequent tissue regeneration. Conventional microextrusion methods for three-dimensional (3D) scaffold fabrication were limited by their low resolution. Electrospinning, a form of electrohydrodynamic (EHD) printing, is an attractive method due to its capability of fabricating high-resolution scaffolds at the nanometer/micrometer scale level. However, the scaffold was composed of randomly orientated filaments which could not guide the cells in a specific direction. Furthermore, the pores of the electrospun scaffold were small, thus preventing cell infiltration. In this study, an alternative EHD jet printing (E-jetting) technique has been developed and employed to fabricate 3D polycaprolactone (PCL) scaffolds with desired filament orientation and pore size. The effect of PCL solution concentration was evaluated. Results showed that solidified filaments were achieved at concentration >70% (w/v). Uniform filaments of diameter 20 μm were produced via the E-jetting technique, and X-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopic analyses revealed that there was no physicochemical changes toward PCL. Scaffold with a pore size of 450 μm and porosity level of 92%, was achieved. A preliminary in vitro study illustrated that live chondrocytes were attaching on the outer and inner surfaces of collagen-coated E-jetted PCL scaffolds. E-jetted scaffolds increased chondrocytes extracellular matrix secretion, and newly formed matrices from chondrocytes contributed significantly to the mechanical strength of the scaffolds. All these results suggested that E-jetting is an alternative scaffold fabrication technique, which has the capability to construct 3D scaffolds with aligned filaments and large pore sizes for tissue engineering applications. PMID:24155124

  8. Fabrication of porous polymeric matrix drug delivery devices using the selective laser sintering technique.

    PubMed

    Leong, K F; Phua, K K; Chua, C K; Du, Z H; Teo, K O

    2001-01-01

    New techniques in solid freeform fabrication (SFF) have prompted research into methods of manufacturing and controlling porosity. The strategy of this research is to integrate computer aided design (CAD) and the SFF technique of selective laser sintering (SLS) to fabricate porous polymeric matrix drug delivery devices (DDDs). This study focuses on the control of the porosity of a matrix by manipulating the SLS process parameters of laser beam power and scan speed. Methylene blue dye is used as a drug model to infiltrate the matrices via a degassing method; visual inspection of dye penetration into the matrices is carried out. Most notably, the laser power matrices show a two-stage penetration process. The matrices are sectioned along the XZ planes and viewed under scanning electron microscope (SEM). The morphologies of the samples reveal a general increase in channel widths as laser power decreases and scan speed increases. The fractional release profiles of the matrices are determined by allowing the dye to diffuse out in vitro within a controlled environment. The results show that laser power and scan speed matrices deliver the dye for 8-9 days and have an evenly distributed profile. Mercury porosimetry is used to analyse the porosity of the matrices. Laser power matrices show a linear relationship between porosity and variation in parameter values. However, the same relationship for scan speed matrices turns out to be rather inconsistent. Relationships between the SLS parameters and the experimental results are developed using the fractional release rate equation for the infinite slab porous matrix DDD as a basis for correlation. PMID:11382078

  9. Use of Clotted Human Plasma and Aprotinin in Skin Tissue Engineering: A Novel Approach to Engineering Composite Skin on a Porous Scaffold.

    PubMed

    Paul, Michelle; Kaur, Pritinder; Herson, Marisa; Cheshire, Perdita; Cleland, Heather; Akbarzadeh, Shiva

    2015-10-01

    Tissue-engineered composite skin is a promising therapy for the treatment of chronic and acute wounds, including burns. Providing the wound bed with a dermal scaffold populated by autologous dermal and epidermal cellular components can further entice host cell infiltration and vascularization to achieve permanent wound closure in a single stage. However, the high porosity and the lack of a supportive basement membrane in most commercially available dermal scaffolds hinders organized keratinocyte proliferation and stratification in vitro and may delay re-epithelization in vivo. The objective of this study was to develop a method to enable the in vitro production of a human skin equivalent (HSE) that included a porous scaffold and dermal and epidermal cells expanded ex vivo, with the potential to be used for definitive treatment of skin defects in a single procedure. A collagen-glycosaminoglycan dermal scaffold (Integra()) was populated with adult fibroblasts. A near-normal skin architecture was achieved by the addition of coagulated human plasma to the fibroblast-populated scaffold before seeding cultured keratinocytes. This resulted in reducing scaffold pore size and improving contact surfaces. Skin architecture and basement membrane formation was further improved by the addition of aprotinin (a serine protease inhibitor) to the culture media to inhibit premature clot digestion. Histological assessment of the novel HSE revealed expression of keratin 14 and keratin 10 similar to native skin, with a multilayered neoepidermis morphologically comparable to human skin. Furthermore, deposition of collagen IV and laminin-511 were detected by immunofluorescence, indicating the formation of a continuous basement membrane at the dermal-epidermal junction. The proposed method was efficient in producing an in vitro near native HSE using the chosen off-the-shelf porous scaffold (Integra). The same principles and promising outcomes should be applicable to other biodegradable porous scaffolds, combined with autologous cells, for use in wound treatment. PMID:25996837

  10. Porous hydroxyapatite/gelatine scaffolds with ice-designed channel-like porosity for biomedical applications.

    PubMed

    Landi, Elena; Valentini, Federica; Tampieri, Anna

    2008-11-01

    A cryogenic process, including freeze-casting and drying has been performed to obtain hydroxyapatite (HA) scaffolds (approx. diameter 10 mm, height 20 mm) with completely lamellar morphology due to preferentially aligned channel-like pores. Changing the process parameters that influence the cold transmission efficiency from the bottom to the top of the poured HA slurry, lamellar ice crystals with different thickness grew throughout the samples. After sintering, scaffolds with porosity features nearly resembling the ice ones were obtained. The interconnection of pores and the ability of the scaffolds to be rapidly penetrated by synthetic body fluid has been proven. Biohybrid HA/gel composites were prepared, infiltrating HA lamellar scaffolds (45-55 vol.% of porosity) with a 10wt.% solution of gelatine. Colouring genipine was used to cross-link gelatine and clearly show the distribution of the protein in the composite. The compressive mechanical properties of lamellar scaffolds improved with the addition of gelatine: the strength increased up to 5-6 times, while the elastic modulus and strain approximately doubled. The effectiveness of the cross-linkage has been preliminarily verified following scaffold degradation in synthetic body fluid. PMID:18579459

  11. Porous surface structure of biocompatible implants and tissue scaffolds base of titanium and nitinol synthesized SLS/M methods

    NASA Astrophysics Data System (ADS)

    Shishkovsky, I.; Sherbakov, V.; Petriv, A.; Kuznetsov, M.; Morozov, Yu.; Volova, L.; Barikov, I.; Fakeev, S.

    2007-06-01

    The objectives of these researches were to investigate the technical fundamentals of synthesizing high-strength biocompatible medical implants and tissue scaffolds made from nitinol or titanium using of Selective Laser Sintering/Melting (SLS/M). In particular, we had been identify the processing parameters and procedures necessary to successfully laser synthesize multi-material and functionally graded implants: the physical and mechanical properties, microstructure, and corrosion behavior of the resulting structures; the shape memory effect in porous layered nitinol structures made using laser synthesis. The comparative morphological and histological results of Selective Laser Sintering of porous titanium and nitinol implants are presented. Studies are conducted also on primary cultures of dermal fibroblasts and mesenchymal stromal human cells of the 4-18 passages. The principle possibility of long cultivating a bone marrow on the porous carrier-incubator from NiTi and titanium in vitro was determined. Sufficient understanding of laser synthesized titanium and nitinol structures to determine their suitability for future use as implants, resulting in superior tissue to implant fixation and minimally invasive surgical procedures, was developed.

  12. A combinatorial variation in surface chemistry and pore size of three-dimensional porous poly(?-caprolactone) scaffolds modulates the behaviors of mesenchymal stem cells.

    PubMed

    Zhao, Yingdi; Tan, Ke; Zhou, Yan; Ye, Zhaoyang; Tan, Wen-Song

    2016-02-01

    Biomaterial properties play significant roles in controlling cellular behaviors. The objective of the present study was to investigate how pore size and surface chemistry of three-dimensional (3D) porous scaffolds regulate the fate of mesenchymal stem cells (MSCs) in vitro in combination. First, on poly(?-caprolactone) (PCL) films, the hydrolytic treatment was found to stimulate the adhesion, spreading and proliferation of human MSCs (hMSCs) in comparison with pristine films, while the aminolysis showed mixed effects. Then, 3D porous PCL scaffolds with varying pore sizes (100-200?m, 200-300?m and 300-450?m) were fabricated and subjected to either hydrolysis or aminolysis. It was found that a pore size of 200-300?m with hydrolysis in 3D scaffolds was the most favorable condition for growth of hMSCs. Importantly, while a pore size of 200-300?m with hydrolysis for 1h supported the best osteogenic differentiation of hMSCs, the chondrogenic differentiation was greatest in scaffolds with a pore size of 300-450?m and treated with aminolysis for 1h. Taken together, these results suggest that surface chemistry and pore size of 3D porous scaffolds may potentially have a synergistic impact on the behaviors of MSCs. PMID:26652364

  13. The promotion of angiogenesis induced by three-dimensional porous beta-tricalcium phosphate scaffold with different interconnection sizes via activation of PI3K/Akt pathways

    PubMed Central

    Xiao, Xin; Wang, Wei; Liu, Dong; Zhang, Haoqiang; Gao, Peng; Geng, Lei; Yuan, Yulin; Lu, Jianxi; Wang, Zhen

    2015-01-01

    The porous architectural characteristics of biomaterials play an important role in scaffold revascularization. However, no consensus exists regarding optimal interconnection sizes for vascularization and its scaffold bioperformance with different interconnection sizes. Therefore, a series of disk-type beta-tricalcium phosphates with the same pore sizes and variable interconnections were produced to evaluate how the interconnection size influenced biomaterial vascularization in vitro and in vivo. We incubated human umbilical vein endothelial cells on scaffolds with interconnections of various sizes. Results showed that scaffolds with a 150 μm interconnection size ameliorated endothelial cell function evidenced by promoting cell adhesion and migration, increasing cell proliferation and enhancing expression of platelet-endothelial cell adhesion molecules and vascular endothelial growth factor. In vivo study was performed on rabbit implanted with scaffolds into the bone defect on femoral condyles. Implantation with scaffolds with 150 μm interconnection size significantly improved neovascularization as shown by micro-CT as compared to scaffolds with 100 and 120 μm interconnection sizes. Moreover, the aforementioned positive effects were abolished by blocking PI3K/Akt/eNOS pathway with LY-294002. Our study explicitly demonstrates that the scaffold with 150 μm interconnection size improves neovascularization via the PI3K/Akt pathway and provides a target for biomaterial inner structure modification to attain improved clinical performance in implant vascularization. PMID:25797242

  14. The promotion of angiogenesis induced by three-dimensional porous beta-tricalcium phosphate scaffold with different interconnection sizes via activation of PI3K/Akt pathways

    NASA Astrophysics Data System (ADS)

    Xiao, Xin; Wang, Wei; Liu, Dong; Zhang, Haoqiang; Gao, Peng; Geng, Lei; Yuan, Yulin; Lu, Jianxi; Wang, Zhen

    2015-03-01

    The porous architectural characteristics of biomaterials play an important role in scaffold revascularization. However, no consensus exists regarding optimal interconnection sizes for vascularization and its scaffold bioperformance with different interconnection sizes. Therefore, a series of disk-type beta-tricalcium phosphates with the same pore sizes and variable interconnections were produced to evaluate how the interconnection size influenced biomaterial vascularization in vitro and in vivo. We incubated human umbilical vein endothelial cells on scaffolds with interconnections of various sizes. Results showed that scaffolds with a 150 μm interconnection size ameliorated endothelial cell function evidenced by promoting cell adhesion and migration, increasing cell proliferation and enhancing expression of platelet-endothelial cell adhesion molecules and vascular endothelial growth factor. In vivo study was performed on rabbit implanted with scaffolds into the bone defect on femoral condyles. Implantation with scaffolds with 150 μm interconnection size significantly improved neovascularization as shown by micro-CT as compared to scaffolds with 100 and 120 μm interconnection sizes. Moreover, the aforementioned positive effects were abolished by blocking PI3K/Akt/eNOS pathway with LY-294002. Our study explicitly demonstrates that the scaffold with 150 μm interconnection size improves neovascularization via the PI3K/Akt pathway and provides a target for biomaterial inner structure modification to attain improved clinical performance in implant vascularization.

  15. Bacterial inhibition potential of 3D rapid-prototyped magnesium-based porous composite scaffolds--an in vitro efficacy study.

    PubMed

    Ma, Rui; Lai, Yu-xiao; Li, Long; Tan, Hong-lue; Wang, Jia-li; Li, Ye; Tang, Ting-ting; Qin, Ling

    2015-01-01

    Bone infections are common in trauma-induced open fractures with bone defects. Therefore, developing anti-infection scaffolds for repairing bone defects is desirable. This study develoepd novel Mg-based porous composite scaffolds with a basal matrix composed of poly(lactic-co-glycolicacid) (PLGA) and tricalcium phosphate (TCP). A unique low-temperature rapid prototyping technology was used to fabricate the scaffolds, including PLGA/TCP (PT), PLGA/TCP/5%Mg (PT5M), PLGA/TCP/10%Mg (PT10M), and PLGA/TCP/15%Mg (PT15M). The bacterial adhesion and biofilm formation of Staphylococcus aureus were evaluated. The results indicated that the Mg-based scaffolds significantly inhibited bacterial adhesion and biofilm formation compared to PT, and the PT10M and PT15M exhibited significantly stronger anti-biofilm ability than PT5M. In vitro degratation tests revealed that the degradation of the Mg-based scaffolds caused an increase of pH, Mg(2+) concentration and osmolality, and the increased pH may be one of the major contributing factors to the antibacterial function of the Mg-based scaffolds. Additionally, the PT15M exhibited an inhibitory effect on cell adhesion and proliferation of MC3T3-E1 cells. In conclusion, the PLGA/TCP/Mg scaffolds could inhibit bacterial adhesion and biofilm formation, and the PT10M scaffold was considered to be an effective composition with considerable antibacterial ability and good cytocompatibility. PMID:26346217

  16. The promotion of angiogenesis induced by three-dimensional porous beta-tricalcium phosphate scaffold with different interconnection sizes via activation of PI3K/Akt pathways.

    PubMed

    Xiao, Xin; Wang, Wei; Liu, Dong; Zhang, Haoqiang; Gao, Peng; Geng, Lei; Yuan, Yulin; Lu, Jianxi; Wang, Zhen

    2015-01-01

    The porous architectural characteristics of biomaterials play an important role in scaffold revascularization. However, no consensus exists regarding optimal interconnection sizes for vascularization and its scaffold bioperformance with different interconnection sizes. Therefore, a series of disk-type beta-tricalcium phosphates with the same pore sizes and variable interconnections were produced to evaluate how the interconnection size influenced biomaterial vascularization in vitro and in vivo. We incubated human umbilical vein endothelial cells on scaffolds with interconnections of various sizes. Results showed that scaffolds with a 150 μm interconnection size ameliorated endothelial cell function evidenced by promoting cell adhesion and migration, increasing cell proliferation and enhancing expression of platelet-endothelial cell adhesion molecules and vascular endothelial growth factor. In vivo study was performed on rabbit implanted with scaffolds into the bone defect on femoral condyles. Implantation with scaffolds with 150 μm interconnection size significantly improved neovascularization as shown by micro-CT as compared to scaffolds with 100 and 120 μm interconnection sizes. Moreover, the aforementioned positive effects were abolished by blocking PI3K/Akt/eNOS pathway with LY-294002. Our study explicitly demonstrates that the scaffold with 150 μm interconnection size improves neovascularization via the PI3K/Akt pathway and provides a target for biomaterial inner structure modification to attain improved clinical performance in implant vascularization. PMID:25797242

  17. Biofilms and extracellular polymeric substances mediate the transport of graphene oxide nanoparticles in saturated porous media.

    PubMed

    Jian-Zhou, He; Cheng-Cheng, Li; Deng-Jun, Wang; Zhou, Dong-Mei

    2015-12-30

    Understanding the fate and transport of graphene oxide nanoparticles (GONPs) in the subsurface environments is of crucial importance since they may pose potential risks to the environment and human health. However, little is known about the significance of biofilm on mobility of GONPs in the subsurface. Here we investigated the transport of GONPs in saturated sand coated with Bacillus subtilis (Gram-positive) and Pseudomonas putida (Gram-negative) biofilms, and their secreted extracellular polymeric substances (EPS) under environmentally relevant ionic strengths (1-50mM NaCl) at pH 7.2. Our results showed that irrespective of bacteria type, greater retention of GONPs occurred in biofilm-coated sand compared to clean sand, likely attributed to the increased surface roughness and physical straining. However, EPS showed negligible influence on GONPs transport, which was inconsistent with the findings in the presence of biofilms, while they exhibited comparable ?-potentials. The different retention phenotype of GONPs in the presence of EPS was induced by hydration effect and steric repulsion. A two-site kinetic retention model well-described the transport of GONPs in porous media covered with different surface coatings, which proves the applicability of mathematical model in predicting nanoparticles' mobility in the subsurface environments, when considering the potential effects of biofilm and EPS. PMID:26223021

  18. ?-Cyclodextrin associated polymeric systems: Rheology, flow behavior in porous media and enhanced heavy oil recovery performance.

    PubMed

    Wei, Bing

    2015-12-10

    This proof of concept research evaluates an approach to improve the enhanced heavy oil recovery performance of conventional polymers. Three associated polymeric systems, based on hydrolyzed polyacrylamide, xanthan gum, and a novel hydrophobic copolymer, were proposed in this work. The results of the theoretically rheology study indicate that these systems offer superior viscoelasticity and pronounced shear-thinning behavior due to the "interlocking effect". As a result of the surfactant collaboration, the dynamic interfacial tension between oil and polymer solution can be reduced by two orders of magnitude. Sandpack flooding tests demonstrated the capacity of the developed systems in mobility control during propagating in porous media, and the adsorption behavior was represented by the thickness of the adsorbed layer. The relationship between microscopic efficiency and capillary number indicated that the associated systems can significantly reduce the residual oil saturation due to the synergistic effect of the mobility reduction and surface activity, and the overall recovery efficiency was raised by 2-20% OOIP compared to the baseline polymers. PMID:26428140

  19. Bone Tissue Engineering with Premineralized Silk Scaffolds

    PubMed Central

    Kim, Hyeon Joo; Kim, Ung-Jin; Kim, Hyun Suk; Li, Chunmei; Wada, Masahisa; Leisk, Gary G.; Kaplan, David L.

    2009-01-01

    Silks fibroin biomaterials are being explored as novel protein-based systems for cell and tissue culture. In the present study, biomimetic growth of calcium phosphate on porous silk fibroin polymeric scaffolds was explored to generate organic/inorganic composites as scaffolds for bone tissue engineering. Aqueous-derived silk fibroin scaffolds were prepared with the addition of polyaspartic acid during processing, followed by the controlled deposition of calcium phosphate by exposure to CaCl2 and Na2HPO4. These mineralized protein-composite scaffolds were subsequently seeded with human bone marrow stem cells (hMSC) and cultured in vitro for 6 weeks under osteogenic conditions with or without BMP-2. The extent of osteoconductivity was assessed by cell numbers, alkaline phosphatase and calcium deposition, along with immunohistochemistry for bone related outcomes. The results suggest increased osteoconductive outcomes with an increase in initial content of apatite and BMP-2 in the silk fibroin porous scaffolds. The premineralization of these highly porous silk fibroin protein scaffolds provided enhanced outcomes for the bone tissue engineering. PMID:18387349

  20. Fabrication of long-acting drug release property of hierarchical porous bioglasses/polylactic acid fibre scaffolds for bone tissue engineering.

    PubMed

    Wang, Dan; Lin, Huiming; Jiang, Jingjie; Jin, Qumei; Li, Lei; Dong, Yan; Qu, Fengyu

    2015-04-01

    Hierarchical porous fibre scaffolds with mesoporous bioglasses (MBGs) and polylactic acid (PLA) were successfully fabricated by the electrospinning method. These compound scaffolds possess macropores with sizes of about 100 nm because of the solvent evaporation from the fibre and the mesoporous structure ( ∼4.0 nm) originated from MBGs. The biomineralisation ability was investigated in simulated body fluid. The fibre structure is beneficial for inducing the growth of hydroxyapatite. In addition, compared with pure MBGs, the materials (MP-1 and MP-2) exhibit a long-acting drug release process up to 140 h and the drug release process corresponds with the Fickian diffusion mechanism. With the special fibre morphology and the hierarchical porous structure, the MBGs/PLA fibre scaffolds are expected to have potential application for bone tissue repair and regeneration. PMID:25829170

  1. Uncultured Marrow Mononuclear Cells Delivered Within Fibrin Glue Hydrogels to Porous Scaffolds Enhance Bone Regeneration Within Critical-Sized Rat Cranial Defects

    PubMed Central

    Kretlow, James D.; Spicer, Patrick P.; Jansen, John A.; Vacanti, Charles A.; Kasper, F. Kurtis

    2010-01-01

    For bone tissue engineering, the benefits of incorporating mesenchymal stem cells (MSCs) into porous scaffolds are well established. There is, however, little consensus on the effects of or need for MSC handling ex vivo. Culture and expansion of MSCs adds length and cost, and likely increases risk associated with treatment. We evaluated the effect of using uncultured bone marrow mononuclear cells (bmMNCs) encapsulated within fibrin glue hydrogels and seeded into porous scaffolds to regenerate bone over 12 weeks in an 8-mm-diameter, critical-sized rat cranial defect. A full factorial experimental design was used to evaluate bone formation within model poly(L-lactic acid) and corraline hydroxyapatite scaffolds with or without platelet-rich plasma (PRP) and bmMNCs. Mechanical push-out testing, microcomputed tomographical analyses, and histology were performed. PRP showed no benefit for bone formation. Cell-laden poly(L-lactic acid) scaffolds without PRP required significantly greater force to displace from surrounding tissues than control (cell-free) scaffolds, but no differences were observed during push-out testing of coral scaffolds. For bone volume formation as analyzed by microcomputed tomography, significant positive overall effects were observed with bmMNC incorporation. These data suggest that bmMNCs may provide therapeutic advantages in bone tissue engineering applications without the need for culture, expansion, and purification. PMID:20715884

  2. Chitosan-collagen porous scaffold and bone marrow mesenchymal stem cell transplantation for ischemic stroke

    PubMed Central

    Yan, Feng; Yue, Wei; Zhang, Yue-lin; Mao, Guo-chao; Gao, Ke; Zuo, Zhen-xing; Zhang, Ya-jing; Lu, Hui

    2015-01-01

    In this study, we successfully constructed a composite of bone marrow mesenchymal stem cells and a chitosan-collagen scaffold in vitro, transplanted either the composite or bone marrow mesenchymal stem cells alone into the ischemic area in animal models, and compared their effects. At 14 days after co-transplantation of bone marrow mesenchymal stem cells and the hitosan-collagen scaffold, neurological function recovered noticeably. Vascular endothelial growth factor expression and nestin-labeled neural precursor cells were detected in the ischemic area, surrounding tissue, hippocampal dentate gyrus and subventricular zone. Simultaneously, a high level of expression of glial fibrillary acidic protein and a low level of expression of neuron-specific enolase were visible in BrdU-labeled bone marrow mesenchymal stem cells. These findings suggest that transplantation of a composite of bone marrow mesenchymal stem cells and a chitosan-collagen scaffold has a neuroprotective effect following ischemic stroke. PMID:26604902

  3. Effect of porosities of bilayered porous scaffolds on spontaneous osteochondral repair in cartilage tissue engineering

    PubMed Central

    Dong, Jian; Ding, Jiandong

    2015-01-01

    Poly(lactide-co-glycolide)-bilayered scaffolds with the same porosity or different ones on the two layers were fabricated, and the porosity effect on in vivo repairing of the osteochondral defect was examined in a comparative way for the first time. The constructs of scaffolds and bone marrow-derived mesenchymal stem cells were implanted into pre-created osteochondral defects in the femoral condyle of New Zealand white rabbits. After 12 weeks, all experimental groups exhibited good cartilage repairing according to macroscopic appearance, cross-section view, haematoxylin and eosin staining, toluidine blue staining, immunohistochemical staining and real-time polymerase chain reaction of characteristic genes. The group of 92% porosity in the cartilage layer and 77% porosity in the bone layer resulted in the best efficacy, which was understood by more biomechanical mimicking of the natural cartilage and subchondral bone. This study illustrates unambiguously that cartilage tissue engineering allows for a wide range of scaffold porosity, yet some porosity group is optimal. It is also revealed that the biomechanical matching with the natural composite tissue should be taken into consideration in the design of practical biomaterials, which is especially important for porosities of a multi-compartment scaffold concerning connected tissues. PMID:26813511

  4. Modeling porous scaffold microstructure by a reaction-diffusion system and its degradation by hydrolysis.

    PubMed

    Garzn-Alvarado, Diego A; Velasco, Marco A; Narvez-Tovar, Carlos A

    2012-02-01

    One of the most important areas of Tissue Engineering is the research about bone regeneration and the replacement of its function. To meet this requirement, scaffolds have been developed to allow the cell migration, the growth of bone tissue, the transport of growth factors and nutrients and the renovation of the mechanical properties of bone. Scaffolds are made of different biomaterials and manufactured using various techniques that, in some cases, do not allow full control over the size and orientation of the pores that characterize the scaffold microstructure. From this perspective, we propose a novel hypothesis that a reaction-diffusion system can be used to design the geometrical specifications of the bone matrix. The validation of this hypothesis is performed by simulations of the reaction-diffusion system in a representative tridimensional unit cell, coupled with a model of scaffold degradation by hydrolysis. The results show the possibility that a Reaction-Diffusion system can control features such as the percentage of porosity, trabecular size, orientation, and interconnectivity of pores. PMID:22136697

  5. Three-dimensional porous scaffolds at the crossroads of tissue engineering and cell-based gene therapy.

    PubMed

    Coutu, Daniel L; Yousefi, Azizeh-Mitra; Galipeau, Jacques

    2009-10-15

    In the last 20 years, more than 1,500 gene therapy clinical trials have been approved worldwide targeting a variety of indications, from inherited monogenic diseases to acquired conditions such as cancer, cardiovascular and infectious diseases. However, concerns about the safety and efficacy of gene therapy pharmaceuticals justify the development of alternative strategies to ensure the clinical translation of this still promising field. In particular, ex vivo gene therapy strategies using autologous adult stem cells coupled to three-dimensional (3D) porous scaffolds show great promises in preclinical studies. Developments in the fields of biomaterial sciences and tissue engineering have already helped understanding how we can harness to regenerative potential of many cell types to create artificial tissues and organs and vastly improve the engraftment of ex vivo manipulated adult stem cells. In this article, we will review the current state of the art in tissue engineering by exploring the various types of clinically available biomaterials and the methods used to process them into complex 3D scaffolds. We will then review how these technologies are applied in cell-based gene therapy and identify novel avenues of research that may benefit patients in the near future. PMID:19681040

  6. Comparative Study of Bone Repair Using Porous Hydroxyapatite/ ?-Tricalcium Phosphate and Xenograft Scaffold in Rabbits with Tibia Defect

    PubMed Central

    Bagher, Zohreh; Rajaei, Farzad; Shokrgozar, Mohammadali

    2012-01-01

    Background: Bone tissue engineering requires materials that are biocompatible, mechanically suited for bone function, integrated with the host skeleton, and support osteoinduction of the implanted cells for new bone formation. The aim of this study was to compare the osteogenic potential of xenograft with hydroxyapatite/?- tricalcium phosphate (HA/?-TCP) scaffold. Methods: New Zealand rabbits (n = 9) were divided into 3 groups. Osteoblast cells were originally isolated from rabbit iliac crest and cultured in DMEM/F12. After creating a critical-sized defect (2 3 cm) in rabbit tibia bone, the defect was filled with an implant of HA/TCP with osteoblasts and xenograft in the hole of left (as control) and right tibia, respectively. The new bone formation and the development of bone union within the defect were evaluated by x-ray images and eosine and hematoxylin staining at 4, 8, and 12 weeks post-operation. Results: The bone partially formed in both groups was filled with osteoblast cultured on porous implants at 4 weeks. Over time, progressive bone regeneration was observed inside the pores. Moreover, a progressive vascular ingrowth and progressive integration with the host bone were obvious in xenograft when compared to HA/?-TCP. A good integration between the xenograft implants and the bone was observed radiographically and confirmed by histological section. Conclusion: The result showed that the bone defect can be repaired using both synthetic and xenograft implants. However, the xenograft showed a better osteointegration as compared to HA/?-TCP scaffold. PMID:22562028

  7. Localised controlled release of simvastatin from porous chitosan-gelatin scaffolds engrafted with simvastatin loaded PLGA-microparticles for bone tissue engineering application.

    PubMed

    Gentile, Piergiorgio; Nandagiri, Vijay Kumar; Daly, Jacqueline; Chiono, Valeria; Mattu, Clara; Tonda-Turo, Chiara; Ciardelli, Gianluca; Ramtoola, Zebunnissa

    2016-02-01

    Localised controlled release of simvastatin from porous freeze-dried chitosan-gelatin (CH-G) scaffolds was investigated by incorporating simvastatin loaded poly-(dl-lactide-co-glycolide) acid (PLGA) microparticles (MSIMs) into the scaffolds. MSIMs at 10% w/w simvastatin loading were prepared using a single emulsion-solvent evaporation method. The MSIM optimal amount to be incorporated into the scaffolds was selected by analysing the effect of embedding increasing amounts of blank PLGA microparticles (BL-MPs) on the scaffold physical properties and on the in vitro cell viability using a clonal human osteoblastic cell line (hFOB). Increasing the BL-MP content from 0% to 33.3% w/w showed a significant decrease in swelling degree (from 124556% to 57035%). Scaffold pore size and distribution changed significantly as a function of BL-MP loading. Compressive modulus of scaffolds increased with increasing BL-MP amount up to 16.6% w/w (23.01.0kPa). No significant difference in cell viability was observed with increasing BL-MP loading. Based on these results, a content of 16.6% w/w MSIM particles was incorporated successfully in CH-G scaffolds, showing a controlled localised release of simvastatin able to influence the hFOB cell proliferation and the osteoblastic differentiation after 11days. PMID:26652371

  8. Bioresorbable polymeric scaffolds for coronary revascularization: Lessons learnt from ABSORB III, ABSORB China, and ABSORB Japan

    PubMed Central

    Gogas, Bill D.; King, Spencer B.; Samady, Habib

    2015-01-01

    Bioresorbable polymers and biocorrodible metals are the latest developments in biodegradable materials used in interventional cardiology for the mechanical treatment of coronary atherosclerosis. Poly-L-lactic acid is the most frequently used bioresorbable polymer and initial evidence of feasibility, efficacy and clinical safety following deployment of polymer-based platforms was gained after completion of the first-in-man longitudinal ABSORB registries, Cohorts A and B and ABSORB Extend. In these studies, the biologic interaction of the first-generation Absorb Bioresorbable Vascular Scaffold (BVS) (Abbott Vascular, SC, Calif., US) with the underlying vascular tissue was evaluated in vivo with multiple imaging modalities such as intravascular ultrasound (IVUS), virtual histology-IVUS, IVUS-palpography, optical coherence tomography as well as ex vivo with coronary computed tomography. Efficacy measures following this in vivo multi-imaging assessment as well as clinical safety were comparable with current generation drug-eluting stents (DES) (Abbott Vascular, SC, Calif., US) in non-complex lesions over a 3-year follow-up. Furthermore, novel properties of functional and anatomic restoration of the vessel wall during the late phases of resorption and vascular healing were observed transforming the field of mechanical treatment of atherosclerosis from delivering only acute revascularization to additionally enable late repair and subsequent restoration of a more physiologic underlying vascular tissue. Despite the sufficient evidence and the subsequent Conformité Européenne mark approval of the first fully biodegradable scaffold (Absorb BVS) in 2012 for revascularizing non-complex lesions, the paucity of randomized comparisons of fully bioresorbable scaffolds (BRS) with metallic DES in a “real-world” clinical setting raised controversies among the interventional community for the merit of these technologies. Only recently, results from international large-scale randomized trials from the United States (U.S.), China and Japan were revealed. Herein we provide a comprehensive overview of the ABSORB III, ABSORB China and ABSORB Japan studies demonstrating the consistent non-inferiority in clinical safety and efficacy measures of the Absorb BVS vs. current generation DES. PMID:26925407

  9. Bioresorbable polymeric scaffolds for coronary revascularization: Lessons learnt from ABSORB III, ABSORB China, and ABSORB Japan.

    PubMed

    Gogas, Bill D; King, Spencer B; Samady, Habib

    2015-01-01

    Bioresorbable polymers and biocorrodible metals are the latest developments in biodegradable materials used in interventional cardiology for the mechanical treatment of coronary atherosclerosis. Poly-L-lactic acid is the most frequently used bioresorbable polymer and initial evidence of feasibility, efficacy and clinical safety following deployment of polymer-based platforms was gained after completion of the first-in-man longitudinal ABSORB registries, Cohorts A and B and ABSORB Extend. In these studies, the biologic interaction of the first-generation Absorb Bioresorbable Vascular Scaffold (BVS) (Abbott Vascular, SC, Calif., US) with the underlying vascular tissue was evaluated in vivo with multiple imaging modalities such as intravascular ultrasound (IVUS), virtual histology-IVUS, IVUS-palpography, optical coherence tomography as well as ex vivo with coronary computed tomography. Efficacy measures following this in vivo multi-imaging assessment as well as clinical safety were comparable with current generation drug-eluting stents (DES) (Abbott Vascular, SC, Calif., US) in non-complex lesions over a 3-year follow-up. Furthermore, novel properties of functional and anatomic restoration of the vessel wall during the late phases of resorption and vascular healing were observed transforming the field of mechanical treatment of atherosclerosis from delivering only acute revascularization to additionally enable late repair and subsequent restoration of a more physiologic underlying vascular tissue. Despite the sufficient evidence and the subsequent Conformité Européenne mark approval of the first fully biodegradable scaffold (Absorb BVS) in 2012 for revascularizing non-complex lesions, the paucity of randomized comparisons of fully bioresorbable scaffolds (BRS) with metallic DES in a "real-world" clinical setting raised controversies among the interventional community for the merit of these technologies. Only recently, results from international large-scale randomized trials from the United States (U.S.), China and Japan were revealed. Herein we provide a comprehensive overview of the ABSORB III, ABSORB China and ABSORB Japan studies demonstrating the consistent non-inferiority in clinical safety and efficacy measures of the Absorb BVS vs. current generation DES. PMID:26925407

  10. Tantalum coating of porous carbon scaffold supplemented with autologous bone marrow stromal stem cells for bone regeneration in vitro and in vivo.

    PubMed

    Wei, Xiaowei; Zhao, Dewei; Wang, Benjie; Wang, Wei; Kang, Kai; Xie, Hui; Liu, Baoyi; Zhang, Xiuzhi; Zhang, Jinsong; Yang, Zhenming

    2016-03-01

    Porous tantalum metal with low elastic modulus is similar to cancellous bone. Reticulated vitreous carbon (RVC) can provide three-dimensional pore structure and serves as the ideal scaffold of tantalum coating. In this study, the biocompatibility of domestic porous tantalum was first successfully tested with bone marrow stromal stem cells (BMSCs) in vitro and for bone tissue repair in vivo. We evaluated cytotoxicity of RVC scaffold and tantalum coating using BMSCs. The morphology, adhesion, and proliferation of BMSCs were observed via laser scanning confocal microscope and scanning electron microscopy. In addition, porous tantalum rods with or without autologous BMSCs were implanted on hind legs in dogs, respectively. The osteogenic potential was observed by hard tissue slice examination. At three weeks and six weeks following implantation, new osteoblasts and new bone were observed at the tantalum-host bone interface and pores. At 12 weeks postporous tantalum with autologous BMSCs implantation, regenerated trabecular equivalent to mature bone was found in the pore of tantalum rods. Our results suggested that domestic porous tantalum had excellent biocompatibility and could promote new bone formation in vivo. Meanwhile, the osteogenesis of porous tantalum associated with autologous BMSCs was more excellent than only tantalum implantation. Future clinical studies are warranted to verify the clinical efficacy of combined implantation of this domestic porous tantalum associated with autologous BMSCs implantation and compare their efficacy with conventional autologous bone grafting carrying blood vessel in patients needing bone repairing. PMID:26843518

  11. Three-dimensional culture of mouse bone marrow cells on stroma formed within a porous scaffold: influence of scaffold shape and cryopreservation of the stromal layer on expansion of haematopoietic progenitor cells.

    PubMed

    Miyoshi, Hirotoshi; Ohshima, Norio; Sato, Chiaki

    2013-01-01

    This study's primary goal was to develop an effective ex vivo expansion method for haematopoietic cells. 3D culture of mouse bone marrow cells was performed in porous scaffolds using a sheet or cube shape. Bone marrow cells were cultured on bone marrow-derived stromal layers formed within the scaffolds and the effect of scaffold shape on the expansion of haematopoietic cells was examined. In some experiments, stromal layers within cubic scaffolds were frozen and then used to culture bone marrow cells after thawing. Results show that after comparison, total cell density and expansion of haematopoietic cells were greater in cultures using the cubic scaffold, suggesting that it was superior to the sheet-like scaffold for expanding haematopoietic cells. When cryopreserved stroma was used, it effectively supported the expansion of haematopoietic cells, and a greater expansion of haematopoietic cells [(erythroid and haematopoietic progenitor cells (HPCs)] was achieved than in cultures with stromal cells that had not been cryopreserved. Expansion of cells using cryopreserved stroma had several other advantages such as a shorter culture period than the conventional method, a stable supply of stromal cells, and ease of handling and scaling up. As a result, this is an attractive method for ex vivo expansion of haematopoietic stem cells (HSCs) and HPCs for clinical use. PMID:22081538

  12. Use of fluorescence spectroscopy to study polymeric materials with porous structure based on imprinting by self-assembled fibrillar networks.

    PubMed

    Burguete, M Isabel; Galindo, Francisco; Gavara, Raquel; Izquierdo, M Angeles; Lima, Joo C; Luis, Santiago V; Parola, A Jorge; Pina, Fernando

    2008-09-01

    Different polymeric materials have been prepared from the organogels formed by a polymerizable methacrylic mixture (methyl methacrylate/ethylene glycol dimethacrylate, 1:1, w/w) and the macrocyclic pseudopeptide 1. The use of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide as a very efficient radical initiator allows polymeric materials in which the structure of the fibrils formed by self-assembly of the organogelator 1 is truly preserved to be obtained. Removal of the pseudopeptidic molecule provides materials with a porous structure reflecting that of the original self-assembled fibrils. The use of fluorescent probes such as rhodamine B and pyrene greatly facilitate the study of the porous structures formed and, accordingly, that of the morphology of the original fibrils. Those studies reveal the presence of a permanent porosity and the organization of the substructures as a porous network. This confirms the existence of a nucleation and growth mechanism for the generation of the fibrils, giving rise to the formation of spherulitic structures. Those spherulites are additionally linked by connections of variable size. A series of diffusion experiments allowed establishment of a direct dependence of the inner porosity of the materials on the amount of self-organizing template used for their preparation. PMID:18683958

  13. Interpenetrating polymer network hydrogel scaffolds for artificial cornea periphery.

    PubMed

    Parke-Houben, Rachel; Fox, Courtney H; Zheng, Luo Luo; Waters, Dale J; Cochran, Jennifer R; Ta, Christopher N; Frank, Curtis W

    2015-02-01

    Three-dimensional scaffolds based on inverted colloidal crystals (ICCs) were fabricated from sequentially polymerized interpenetrating polymer network (IPN) hydrogels of poly(ethyleneglycol) and poly(acrylic acid). This high-strength, high-water-content IPN hydrogel may be suitable for use in an artificial cornea application. Development of a highly porous, biointegrable region at the periphery of the artificial cornea device is critical to long-term retention of the implant. The ICC fabrication technique produced scaffolds with well-controlled, tunable pore and channel dimensions. When surface functionalized with extracellular matrix proteins, corneal fibroblasts were successfully cultured on IPN hydrogel scaffolds, demonstrating the feasibility of these gels as materials for the artificial cornea porous periphery. Porous hydrogels with and without cells were visualized non-invasively in the hydrated state using variable-pressure scanning electron microscopy. PMID:25665845

  14. Highly porous drug-eluting structures: from wound dressings to stents and scaffolds for tissue regeneration.

    PubMed

    Elsner, Jonathan J; Kraitzer, Amir; Grinberg, Orly; Zilberman, Meital

    2012-01-01

    For many biomedical applications, there is need for porous implant materials. The current article focuses on a method for preparation of drug-eluting porous structures for various biomedical applications, based on freeze drying of inverted emulsions. This fabrication process enables the incorporation of any drug, to obtain an "active implant" that releases drugs to the surrounding tissue in a controlled desired manner. Examples for porous implants based on this technique are antibiotic-eluting mesh/matrix structures used for wound healing applications, antiproliferative drug-eluting composite fibers for stent applications and local cancer treatment, and protein-eluting films for tissue regeneration applications. In the current review we focus on these systems. We show that the release profiles of both types of drugs, water-soluble and water-insoluble, are affected by the emulsion's formulation parameters. The former's release profile is affected mainly through the emulsion stability and the resulting porous microstructure, whereas the latter's release mechanism occurs via water uptake and degradation of the host polymer. Hence, appropriate selection of the formulation parameters enables to obtain desired controllable release profile of any bioactive agent, water-soluble or water-insoluble, and also fit its physical properties to the application. PMID:23507890

  15. MgF2-coated porous magnesium/alumina scaffolds with improved strength, corrosion resistance, and biological performance for biomedical applications.

    PubMed

    Kang, Min-Ho; Jang, Tae-Sik; Kim, Sung Won; Park, Hui-Sun; Song, Juha; Kim, Hyoun-Ee; Jung, Kyung-Hwan; Jung, Hyun-Do

    2016-05-01

    Porous magnesium (Mg) has recently emerged as a promising biodegradable alternative to biometal for bone ingrowth; however, its low mechanical properties and high corrosion rate in biological environments remain problematic. In this study, porous magnesium was implemented in a scaffold that closely mimics the mechanical properties of human bones with a controlled degradation rate and shows good biocompatibility to match the regeneration rate of bone tissue at the affected site. The alumina-reinforced Mg scaffold was produced by spark plasma sintering and coated with magnesium fluoride (MgF2) using a hydrofluoric acid solution to regulate the corrosion rate under physiological conditions. Sodium chloride granules (NaCl), acting as space holders, were leached out to achieve porous samples (60%) presenting an average pore size of 240μm with complete pore interconnectivity. When the alumina content increased from 0 to 5vol%, compressive strength and stiffness rose considerably from 9.5 to 13.8MPa and from 0.24 to 0.40GPa, respectively. Moreover, the biological response evaluated by in vitro cell test and blood test of the MgF2-coated porous Mg composite was enhanced with better corrosion resistance compared with that of uncoated counterparts. Consequently, MgF2-coated porous Mg/alumina composites may be applied in load-bearing biodegradable implants. PMID:26952467

  16. Porous SiO2 nanofiber grafted novel bioactive glass-ceramic coating: A structural scaffold for uniform apatite precipitation and oriented cell proliferation on inert implant.

    PubMed

    Das, Indranee; De, Goutam; Hupa, Leena; Vallittu, Pekka K

    2016-05-01

    A composite bioactive glass-ceramic coating grafted with porous silica nanofibers was fabricated on inert glass to provide a structural scaffold favoring uniform apatite precipitation and oriented cell proliferation. The coating surfaces were investigated thoroughly before and after immersion in simulated body fluid. In addition, the proliferation behavior of fibroblast cells on the surface was observed for several culture times. The nanofibrous exterior of this composite bioactive coating facilitated homogeneous growth of flake-like carbonated hydroxyapatite layer within a short period of immersion. Moreover, the embedded porous silica nanofibers enhanced hydrophilicity which is required for proper cell adhesion on the surface. The cells proliferated well following a particular orientation on the entire coating by the assistance of nanofibrous scaffold-like structural matrix. This newly engineered composite coating was effective in creating a biological structural matrix favorable for homogeneous precipitation of calcium phosphate, and organized cell growth on the inert glass surface. PMID:26952416

  17. Peptide-directed self-assembly of functionalized polymeric nanoparticles part I: design and self-assembly of peptide-copolymer conjugates into nanoparticle fibers and 3D scaffolds.

    PubMed

    Ding, Xiaochu; Janjanam, Jagadeesh; Tiwari, Ashutosh; Thompson, Martin; Heiden, Patricia A

    2014-06-01

    A robust self-assembly of nanoparticles into fibers and 3D scaffolds is designed and fabricated by functionalizing a RAFT-polymerized amphiphilic triblock copolymer with designer ionic complementary peptides so that the assembled core-shell polymeric nanoparticles are directed by peptide assembly into continuous "nanoparticle fibers," ultimately leading to 3D fiber scaffolds. The assembled nanostructure is confirmed by FESEM and optical microscopy. The assembly is not hindered when a protein (insulin) is incorporated within the nanoparticles as an active ingredient. MTS cytotoxicity tests on SW-620 cell lines show that the peptides, copolymers, and peptide-copolymer conjugates are biocompatible. The methodology of self-assembled nanoparticle fibers and 3D scaffolds is intended to combine the advantages of a flexible hydrogel scaffold with the versatility of controlled release nanoparticles to offer unprecedented ability to incorporate desired drug(s) within a self-assembled scaffold system with individual control over the release of each drug. PMID:24610743

  18. Challenges for Nerve Repair Using Chitosan-Siloxane Hybrid Porous Scaffolds

    PubMed Central

    Shirosaki, Yuki; Hayakawa, Satoshi; Osaka, Akiyoshi; Lopes, Maria A.; Santos, Jos D.; Geuna, Stefano; Mauricio, Ana C.

    2014-01-01

    The treatment of peripheral nerve injuries remains one of the greatest challenges of neurosurgery, as functional recover is rarely satisfactory in these patients. Recently, biodegradable nerve guides have shown great potential for enhancing nerve regeneration. A major advantage of these nerve guides is that no foreign material remains after the device has fulfilled its task, which spares a second surgical intervention. Recently, we studied peripheral nerve regeneration using chitosan-?-glycidoxypropyltrimethoxysilane (chitosan-GPTMS) porous hybrid membranes. In our studies, these porous membranes significantly improved nerve fiber regeneration and functional recovery in rat models of axonotmetic and neurotmetic sciatic nerve injuries. In particular, the number of regenerated myelinated nerve fibers and myelin thickness were significantly higher in rat treated with chitosan porous hybrid membranes, whether or not they were used in combination with mesenchymal stem cells isolated from the Wharton's jelly of the umbilical cord. In this review, we describe our findings on the use of chitosan-GPTMS hybrids for nerve regeneration. PMID:25054129

  19. Freeze casting of porous hydroxyapatite scaffolds. I. Processing and general microstructure.

    PubMed

    Fu, Qiang; Rahaman, Mohamed N; Dogan, Fatih; Bal, B Sonny

    2008-07-01

    Freeze casting of aqueous suspensions on a cold substrate was investigated as a method for preparing hydroxyapatite (HA) scaffolds with unidirectional porosity. In the present paper, we report on the ability to manipulate the microstructure of freeze-cast constructs by controlling the processing parameters. Constructs prepared from aqueous suspensions (5-20 volume percent particles) on a steel substrate at -20 degrees C had a lamellar-type microstructure, consisting of plate-like HA and unidirectional pores oriented in the direction of freezing. Sintering for 3 h at 1350 degrees C produced constructs with dense HA lamellas, porosity of approximately 50%, and inter-lamellar pore widths of 5-30 microm. The thickness of the HA lamellas decreased but the width of the pores increased with decreasing particle concentration. Decreasing the substrate temperature from -20 degrees C to -196 degrees C produced a finer lamellar microstructure. The use of water-glycerol mixtures (20 wt % glycerol) as the solvent in the suspension resulted in the production of finer pores (1-10 microm) and a larger number of dendritic growth connecting the HA lamellas. On the other hand, the use of water-dioxane mixtures (60 wt % dioxane) produced a cellular-type microstructure with larger pores (90-110 microm). The ability to produce a uniaxial microstructure and its manipulation by controlling the processing parameters indicate the potential of the present freeze casting route for the production of scaffolds for bone tissue engineering applications. PMID:18098195

  20. Biohybrid Fibro-Porous Vascular Scaffolds: Effect of Crosslinking on Properties

    PubMed Central

    Nozik, Danna; Patel, Harsh; Singh, Raj K.; Vohra, Yogesh K.

    2015-01-01

    Tubular grafts were fabricated from blends of polycaprolactone (PCL) and poly(glycolide -co-caprolactone) (PGC) polymers and coated with an extracellular matrix containing collagens, laminin, and proteoglycans, but not growth factors (HuBiogel). Multifunctional scaffolds from polymer blends and membrane proteins provide the necessary biomechanics and biological functions for tissue regeneration. Two crosslinking agents, a natural crosslinker namely genipin (Gp) and a carbodiimide reagent namely 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), were used for further stabilizing the protein matrix and the effect of crosslinking was evaluated for structural, morphological, mechanical properties using SEM, DSC and DMA. SEM images and fiber diameter distribution showed fiber-size between 0.2 m to 1 m with the majority of fiber diameters being under 500 nm, indicating upper range of protein fiber-sizes (for example, collagen fibers in extracellular matrix are in 50 to 500 nm diameter range). HB coating did not affect the mechanical properties, but increased its hydrophilicity of the graft. Overall data showed that PCL/PGC blends with 3:1 mass ratio exhibited mechanical properties comparable to those of human native arteries (tensile strength of 12 MPa and Youngs modulus of <10 MPa). Additionally, the effect of crosslinking on coating stability was investigated to assure the retention of proteins on scaffold for effective cell-matrix interactions. PMID:26082566

  1. Production and in vitro characterization of 3D porous scaffolds made of magnesium carbonate apatite (MCA)/anionic collagen using a biomimetic approach.

    PubMed

    Sader, Marcia S; Martins, Virginia C A; Gomez, Santiago; LeGeros, Racquel Z; Soares, Gloria A

    2013-10-01

    3D porous scaffolds are relevant biomaterials to bone engineering as they can be used as templates to tissue reconstruction. The aim of the present study was to produce and characterize in vitro 3D magnesium-carbonate apatite/collagen (MCA/col) scaffolds. They were prepared by using biomimetic approach, followed by cross-linking with 0.25% glutaraldehyde solution (GA) and liofilization. Results obtained with Fourier-transform infrared spectroscopy (FT-IR) confirmed the type-B carbonate substitution, while by X-ray diffraction (XRD), a crystallite size of ~10nm was obtained. Optical and electron microscopy showed that the cylindrical samples exhibited an open-porous morphology, with apatite nanocrystals precipitated on collagen fibrils. The cross-linked 3D scaffolds showed integrity when immersed in culture medium up to 14 days. Also, the immersion of such samples into an acid buffer solution, to mimic the osteoclastic resorption environment, promotes the release of important ions for bone repair, such as calcium, phosphorus and magnesium. Bone cells (SaOs2) adhered, and proliferated on the 3D composite scaffolds, showing that synthesis and the cross-linking processes did not induce cytotoxicity. PMID:23910332

  2. Osteogenesis and chondrogenesis of biomimetic integrated porous PVA/gel/V-n-HA/pa6 scaffolds and BMSCs construct in repair of articular osteochondral defect.

    PubMed

    Li, Xiang; Li, Yubao; Zuo, Yi; Qu, Dan; Liu, Yiming; Chen, Tao; Jiang, Nan; Li, Hui; Li, Jihua

    2015-10-01

    A novel bi-layered osteochondral scaffold, including of PVA/Gel/V layer for the cartilage and n-HA/PA6 layer for the subchondral bone, has been proposed to evaluate the potential of the engineered of osteochondral grafts in repairing articular osteochondral defects in rabbits. The two different layers of the scaffolds were seeded with allogenic bone marrow-derived stem cells (BMSCs), which were chondrogenically and osteogenically induced respectively. The critical-size osteochondral defects were created in the knees of adult rabbits. The defects were treated with cell-bi-layered constructs (Group A), bi-layered constructs (Group B) and untreated group C as control group. The adhesion, proliferation and differentiation of BMSCs were demonstrated by immunohistochemical staining and scanning electron microscopy (SEM) in vitro. Cell survival was tracked via fluorescent labeling in vivo. Overall, the porous PVA/Gel/V-n-HA/PA6 scaffold was compatible and had no negative effects on the BMSCs in vitro culture. The cell-bi-layered scaffolds showed superior repair results as compared to the control group using gross examination and histological assessment. With BMSCs implantation, the two different layers of the composite biomimetic scaffolds provided a suitable environment for cells to form respective tissue. Simultaneously, the RT-PCR results confirmed the expression of specific extracellular matrix (ECM) markers for cartilaginous or osteoid tissue. This investigation showed that the porous PVA/Gel/V-n-HA/PA6 scaffold is a potential matrix for treatment of osteochondral defects, and the method of using chondrogenically and osteogenically differentiated BMSCs as seed cells on each layer might be a promising strategy in repair of articular osteochondral defect due to enhanced chondrogenesis and osteogenesis. PMID:25772000

  3. A new method for the preparation of polymeric porous layer open tubular columns for GC application

    NASA Technical Reports Server (NTRS)

    Shen, T. C.; Wang, M. L.

    1995-01-01

    A new method to prepare polymeric PLOT columns by using in situ polymerization technology is described. The method involves a straightforward in situ polymerization of the monomer. The polymer produced is directly coated on the metal tubing. This eliminates many of the steps needed in conventional polymeric PLOT column preparation. Our method is easy to operate and produces very reproducible columns, as shown previously (T. C. Shen. J. Chromatogr. Sci. 30, 239, 1992). The effects of solvents, tubing pretreatments, initiators and reaction temperatures in the preparation of PLOT columns are studied. Several columns have been developed to separate (1) highly polar compounds, such as water and ammonia or water and HCN, and (2) hydrocarbons and inert gases. A recent improvement has allowed us to produce bonded polymeric PLOT columns. These were studied, and the results are included also.

  4. Study of the effect of external heating and internal temperature build-up during polymerization on the morphology of porous polymethacrylate adsorbent

    NASA Astrophysics Data System (ADS)

    Wei, Chan Yi; Ongkudon, Clarence M.; Kansil, Tamar

    2015-07-01

    Modern day synthesis protocols of methacrylate monolithic polymer adsorbent are based on existing polymerization blueprint without a thorough understanding of the dynamics of pore structure and formation. This has resulted in unproductiveness of polymer adsorbent consequently affecting purity and recovery of final product, productivity, retention time and cost effectiveness of the whole process. The problems magnified in monolith scaling-up where internal heat buildup resulting from external heating and high exothermic polymerization reaction was reflected in cracking of the adsorbent. We believe that through careful and precise control of the polymerization kinetics and parameters, it is possible to prepare macroporous methacrylate monolithic adsorbents with controlled pore structures despite being carried out in an unstirred mould. This research involved the study of the effect of scaling-up on pore morphology of monolith, in other words, porous polymethacrylate adsorbents that were prepared via bulk free radical polymerization process by imaging the porous morphology of polymethacrylate with scanning electron microscope.

  5. Computer-Aided Process Planning for the Layered Fabrication of Porous Scaffold Matrices

    NASA Astrophysics Data System (ADS)

    Starly, Binil

    Rapid Prototyping (RP) technology promises to have a tremendous impact on the design and fabrication of porous tissue replacement structures for applications in tissue engineering and regenerative medicine. The layer-by-layer fabrication technology enables the design of patient-specific medical implants and complex structures for diseased tissue replacement strategies. Combined with advancements in imaging modalities and bio-modeling software, physicians can engage themselves in advanced solutions for craniofacial and mandibular reconstruction. For example, prior to the advancement of RP technologies, solid titanium parts used as implants for mandibular reconstruction were fashioned out of molding or CNC-based machining processes (Fig. 3.1). Titanium implants built using this process are often heavy, leading to increased patient discomfort. In addition, the Young's modulus of titanium is almost five times that of healthy cortical bone resulting in stress shielding effects [1,2]. With the advent of CAD/CAM-based tools, the virtual reconstruction of the implants has resulted in significant design improvements. The new generation of implants can be porous, enabling the in-growth of healthy bone tissue for additional implant fixation and stabilization. Newer implants would conform to the external shape of the defect site that is intended to be filled in. More importantly, the effective elastic modulus of the implant can be designed to match that of surrounding tissue. Ideally, the weight of the implant can be designed to equal the weight of the tissue that is being replaced resulting in increased patient comfort. Currently, such porous structures for reconstruction can only be fabricated using RP-based metal fabrication technologies such as Electron Beam Melting (EBM), Selective Laser Sintering (SLS), and 3D Printing processes.

  6. Relationship between micro-porosity, water permeability and mechanical behavior in scaffolds for cartilage engineering.

    PubMed

    Vikingsson, L; Claessens, B; Gmez-Tejedor, J A; Gallego Ferrer, G; Gmez Ribelles, J L

    2015-08-01

    In tissue engineering the design and optimization of biodegradable polymeric scaffolds with a 3D-structure is an important field. The porous scaffold provide the cells with an adequate biomechanical environment that allows mechanotransduction signals for cell differentiation and the scaffolds also protect the cells from initial compressive loading. The scaffold have interconnected macro-pores that host the cells and newly formed tissue, while the pore walls should be micro-porous to transport nutrients and waste products. Polycaprolactone (PCL) scaffolds with a double micro- and macro-pore architecture have been proposed for cartilage regeneration. This work explores the influence of the micro-porosity of the pore walls on water permeability and scaffold compliance. A Poly(Vinyl Alcohol) with tailored mechanical properties has been used to simulate the growing cartilage tissue inside the scaffold pores. Unconfined and confined compression tests were performed to characterize both the water permeability and the mechanical response of scaffolds with varying size of micro-porosity while volume fraction of the macro-pores remains constant. The stress relaxation tests show that the stress response of the scaffold/hydrogel construct is a synergic effect determined by the performance of the both components. This is interesting since it suggests that the in vivo outcome of the scaffold is not only dependent upon the material architecture but also the growing tissue inside the scaffold?s pores. On the other hand, confined compression results show that compliance of the scaffold is mainly controlled by the micro-porosity of the scaffold and less by hydrogel density in the scaffold pores. These conclusions bring together valuable information for customizing the optimal scaffold and to predict the in vivo mechanical behavior. PMID:25913609

  7. Transfer of apatite coating from porogens to scaffolds: uniform apatite coating within porous poly(DL-lactic-co-glycolic acid) scaffold in vitro.

    PubMed

    Li, Jiashen; Beaussart, Audrey; Chen, Yun; Mak, Arthur F T

    2007-01-01

    Strategies to bone tissue engineering have focused on the use of synthetic or natural degradable materials as scaffolds for cell transplantation to guide bone regeneration. Biocompatibility, biodegradability, biomechanical integrity, and osteoconductivity are important requirements for the scaffold materials. This study explored a new approach of apatite coating to enhance the osteoconductivity of a synthetic degradable poly(DL-lactic-co-glycolic acid) (PLGA) scaffold. The new approach was developed to ensure a relatively uniform apatite coating on the interior pore surfaces deep inside a scaffold, even for a relatively thick scaffold with small pores. Apatite was first coated on the surface of paraffin spheres of the desirable sizes. The paraffin spheres were then molded to form a foam. PLGA/pyridine solution was cast into the interspaces among the paraffin spheres. After the paraffin spheres were dissolved and removed by cyclohexane, PLGA scaffold with controlled pore size, good interconnectivity and high porosity was obtained with apatite left on the pore surface uniformly throughout the whole scaffold. The scaffold and apatite coating were characterized using thermogravimetry analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffractometry. PMID:17072848

  8. Nucleation of biomimetic apatite in synthetic body fluids: dense and porous scaffold development.

    PubMed

    Landi, Elena; Tampieri, Anna; Celotti, Giancarlo; Langenati, Ratih; Sandri, Monica; Sprio, Simone

    2005-06-01

    The effectiveness of synthetic body fluids (SBF) as biomimetic sources to synthesize carbonated hydroxyapatite (CHA) powder similar to the biological inorganic phase, in terms of composition and microstructure, was investigated. CHA apatite powders were prepared following two widely experimented routes: (1) calcium nitrate tetrahydrate and diammonium hydrogen phosphate and (2) calcium hydroxide and ortophosphoric acid, but using SBF as synthesis medium instead of pure water. The characteristics of the as-prepared powders were compared, also with the features of apatite powders synthesized via pure water-based classical methods. The powder thermal resistance and behaviour during densification were studied together with the mechanical properties of the dense samples. The sponge impregnation process was used to prepare porous samples having morphological and mechanical characteristics suitable for bone substitution. Using this novel synthesis was it possible to prepare nanosized (approximately equal to 20 nm), pure, carbonate apatite powder containing Mg, Na, K ions, with morphological and compositional features mimicking natural apatite and with improved thermal properties. After sintering at 1250 degrees C the carbonate-free apatite porous samples showed a surprising, high compressive strength together with a biomimetic morphology. PMID:15603779

  9. Porous poly(alpha-hydroxyacid)/Bioglass composite scaffolds for bone tissue engineering. I: Preparation and in vitro characterisation.

    PubMed

    Maquet, V; Boccaccini, A R; Pravata, L; Notingher, I; Jrme, R

    2004-08-01

    Highly porous composites scaffolds of poly-D,L-lactide (PDLLA) and poly(lactide-co-glycolide) (PLGA) containing different amounts (10, 25 and 50 wt%) of bioactive glass (45S5 Bioglass)were prepared by thermally induced solid-liquid phase separation (TIPS) and subsequent solvent sublimation. The addition of increasing amounts of Bioglass into the polymer foams decreased the pore volume. Conversely, the mechanical properties of the polymer materials were improved. The composites were incubated in phosphate buffer saline at 37 degrees C to study the in vitro degradation of the polymer by measurement of water absorption, weight loss as well as changes in the average molecular weight of the polymer and in the pH of the incubation medium as a function of the incubation time. The addition of Bioglass to polymer foams increased the water absorption and weight loss compared to neat polymer foams. However, the polymer molecular weight, determined by size exclusion chromatography, was found to decrease more rapidly and to a larger extent in absence of Bioglass. The presence of the bioactive filler was therefore found to delay the degradation rate of the polymer as compared to the neat polymer foams. Formation of hydroxyapatite on the surface of composites, as an indication of their bioactivity, was recorded by EDXA, X-ray diffractometry and confirmed by Raman spectroscopy. PMID:15046908

  10. 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 invitro 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. PMID:26359295

  11. Osteogenic differentiation of umbilical cord and adipose derived stem cells onto highly porous 45S5 Bioglass®-based scaffolds.

    PubMed

    Detsch, Rainer; Alles, Sonja; Hum, Jasmin; Westenberger, Peter; Sieker, Frank; Heusinger, Dominik; Kasper, Cornelia; Boccaccini, Aldo R

    2015-03-01

    In the context of bone tissue engineering (BTE), combinations of bioactive scaffolds with living cells are investigated to optimally yield functional bone tissue for implantation purposes. Bioactive glasses are a class of highly bioactive, inorganic materials with broad application potential in BTE strategies. The aim of this study was to evaluate bioactive glass (45S5 Bioglass(®)) samples of composition: 45 SiO2, 24.5 CaO, 24.5 Na2O, and 6 P2O5 (in wt%) as scaffold materials for mesenchymal stem cells (MSC). Pore architecture of the scaffolds as well as cell behavior in the three-dimensional environment was evaluated by several methods. Investigations concerned the osteogenic cell attachment, growth and differentiation of adipose tissue derived MSC (adMSC) compared with MSC from human full term umbilical cord tissues (ucMSC) on porous Bioglass(®)-based scaffolds over a cultivation period of 5 weeks. Differences in lineage-specific osteogenic differentiation of adMSC and ucMSC on Bioglass(®) samples were demonstrated. The investigation led to positive results in terms of cell attachment, proliferation, and differentiation of MSC onto Bioglass(®)-based scaffolds confirming the relevance of these matrices for BTE applications. PMID:24853477

  12. Multiple approaches to predicting oxygen and glucose consumptions by HepG2 cells on porous scaffolds in an axial-flow bioreactor.

    PubMed

    Podichetty, Jagdeep T; Bhaskar, Prasana R; Singarapu, Kumar; Madihally, Sundararajan V

    2015-02-01

    In this study, the distribution of oxygen and glucose was evaluated along with consumption by hepatocytes using three different approaches. The methods include (i) Computational Fluid Dynamics (CFD) simulation, (ii) residence time distribution (RTD) analysis using a step-input coupled with segregation model or dispersion model, and (iii) experimentally determined consumption by HepG2 cells in an open-loop. Chitosan-gelatin (CG) scaffolds prepared by freeze-drying and polycaprolactone (PCL) scaffolds prepared by salt leaching technique were utilized for RTD analyses. The scaffold characteristics were used in CFD simulations i.e. Brinkman's equation for flow through porous medium, structural mechanics for fluid induced scaffold deformation, and advection-diffusion equation coupled with Michaelis-Menten rate equations for nutrient consumption. With the assumption that each hepatocyte behaves like a micro-batch reactor within the scaffold, segregation model was combined with RTD to determine exit concentration. A flow rate of 1 mL/min was used in the bioreactor seeded with 0.6 × 10(6) HepG2 cells/cm(3) on CG scaffolds and oxygen consumption was measured using two flow-through electrodes located at the inlet and outlet. Glucose in the spent growth medium was also analyzed. RTD results showed distribution of nutrients to depend on the surface characteristics of scaffolds. Comparisons of outlet oxygen concentrations between the simulation results, and experimental results showed good agreement with the dispersion model. Outlet oxygen concentrations from segregation model predictions were lower. Doubling the cell density showed a need for increasing the flow rate in CFD simulations. This integrated approach provide a useful strategy in designing bioreactors and monitoring tissue regeneration. PMID:25116006

  13. Towards biomimetic scaffolds: anhydrous scaffold fabrication from biodegradable amine-reactive diblock copolymers.

    PubMed

    Hacker, Michael; Tessmar, Jörg; Neubauer, Markus; Blaimer, Andrea; Blunk, Torsten; Göpferich, Achim; Schulz, Michaela B

    2003-11-01

    The development of biomimetic materials and their processing into three-dimensional cell carrying scaffolds is one promising tissue engineering strategy to improve cell adhesion, growth and differentiation on polymeric constructs developing mature and viable tissue. This study was concerned with the fabrication of scaffolds made from amine-reactive diblock copolymers, N-succinimidyl tartrate monoamine poly(ethylene glycol)-block-poly(D,L-lactic acid), which are able to suppress unspecific protein adsorption and to covalently bind proteins or peptides. An appropriate technique for their processing had to be both anhydrous, to avoid hydrolysis of the active ester, and suitable for the generation of interconnected porous structures. Attempts to fabricate scaffolds utilizing hard paraffin microparticles as hexane-extractable porogens failed. Consequently, a technique was developed involving lipid microparticles, which served as biocompatible porogens on which the scaffold forming polymer was precipitated in the porogen extraction media (n-hexane). Porogen melting during the extraction and polymer precipitation step led to an interconnected network of pores. Suitable lipid mixtures and their melting points, extraction conditions (temperature and time) and a low-toxic polymer solvent system were determined for their use in processing diblock copolymers of different molecular weights (22 and 42 kDa) into highly porous off-the-shelf cell carriers ready for easy surface modification towards biomimetic scaffolds. Insulin was employed to demonstrate the principal of instant protein coupling to a prefabricated scaffold. PMID:12922156

  14. Biomimetic alginate/polyacrylamide porous scaffold supports human mesenchymal stem cell proliferation and chondrogenesis.

    PubMed

    Guo, Peng; Yuan, Yasheng; Chi, Fanglu

    2014-09-01

    We describe the development of alginate/polyacrylamide (ALG/PAAm) porous hydrogels based on interpenetrating polymer network structure for human mesenchymal stem cell proliferation and chondrogenesis. Three ALG/PAAm hydrogels at molar ratios of 10/90, 20/80, and 30/70 were prepared and characterized with enhanced elastic and rubbery mechanical properties, which are similar to native human cartilage tissues. Their elasticity and swelling properties were also studied under different physiological pH conditions. Finally, in vitro tests demonstrated that human mesenchymal stem cells could proliferate on the as-synthesized hydrogels with improved alkaline phosphatase activities. These results suggest that ALG/PAAm hydrogels may be a promising biomaterial for cartilage tissue engineering. PMID:25063162

  15. A mathematical model and computational framework for three-dimensional chondrocyte cell growth in a porous tissue scaffold placed inside a bi-directional flow perfusion bioreactor.

    PubMed

    Shakhawath Hossain, Md; Bergstrom, D J; Chen, X B

    2015-12-01

    The in vitro chondrocyte cell culture for cartilage tissue regeneration in a perfusion bioreactor is a complex process. Mathematical modeling and computational simulation can provide important insights into the culture process, which would be helpful for selecting culture conditions to improve the quality of the developed tissue constructs. However, simulation of the cell culture process is a challenging task due to the complicated interaction between the cells and local fluid flow and nutrient transport inside the complex porous scaffolds. In this study, a mathematical model and computational framework has been developed to simulate the three-dimensional (3D) cell growth in a porous scaffold placed inside a bi-directional flow perfusion bioreactor. The model was developed by taking into account the two-way coupling between the cell growth and local flow field and associated glucose concentration, and then used to perform a resolved-scale simulation based on the lattice Boltzmann method (LBM). The simulation predicts the local shear stress, glucose concentration, and 3D cell growth inside the porous scaffold for a period of 30 days of cell culture. The predicted cell growth rate was in good overall agreement with the experimental results available in the literature. This study demonstrates that the bi-directional flow perfusion culture system can enhance the homogeneity of the cell growth inside the scaffold. The model and computational framework developed is capable of providing significant insight into the culture process, thus providing a powerful tool for the design and optimization of the cell culture process. Biotechnol. Bioeng. 2015;112: 2601-2610. 2015 Wiley Periodicals, Inc. PMID:26061385

  16. HA/nylon 6,6 porous scaffolds fabricated by salt-leaching/solvent casting technique: effect of nano-sized filler content on scaffold properties

    PubMed Central

    Mehrabanian, Mehran; Nasr-Esfahani, Mojtaba

    2011-01-01

    Nanohydroxyapatite (n-HA)/nylon 6,6 composite scaffolds were produced by means of the salt-leaching/solvent casting technique. NaCl with a distinct range size was used with the aim of optimizing the pore network. Composite powders with different n-HA contents (40%, 60%) for scaffold fabrication were synthesized and tested. The composite scaffolds thus obtained were characterized for their microstructure, mechanical stability and strength, and bioactivity. The microstructure of the composite scaffolds possessed a well-developed interconnected porosity with approximate optimal pore size ranging from 200 to 500 ?m, ideal for bone regeneration and vascularization. The mechanical properties of the composite scaffolds were evaluated by compressive strength and modulus tests, and the results confirmed their similarity to cortical bone. To characterize bioactivity, the composite scaffolds were immersed in simulated body fluid for different lengths of time and results monitored by scanning electron microscopy and energy dispersive X-ray microanalysis to determine formation of an apatite layer on the scaffold surface. PMID:21904455

  17. Fabrication of porous carbon/TiO₂ composites through polymerization-induced phase separation and use as an anode for Na-ion batteries.

    PubMed

    Lee, Jeongwoo; Chen, Yu-Ming; Zhu, Yu; Vogt, Bryan D

    2014-12-10

    Polymerization-induced phase separation of nanoparticle-filled solution is demonstrated as a simple approach to control the structure of porous composites. These composites are subsequently demonstrated as the active component for sodium ion battery anode. To synthesize the composites, we dissolved/dispersed titanium oxide (anatase) nanoparticles (for sodium insertion) and poly(hydroxybutyl methacrylate) (PHBMA, porogen) in furfuryl alcohol (carbon precursor) containing a photoacid generator (PAG). UV exposure converts the PAG to a strong acid that catalyzes the furfuryl alcohol polymerization. This polymerization simultaneously decreases the miscibility of the PHBMA and reduces the mobility in the mixture to kinetically trap the phase separation. Carbonization of this polymer composite yields a porous nanocomposite. This nanocomposite exhibits nearly 3-fold greater gravimetric capacity in Na-ion batteries than the same titanium oxide nanoparticles that have been coated with carbon. This improved performance is attributed to the morphology as the carbon content in the composite is five times that of the coated nanoparticles. The porous composite materials exhibit stable cyclic performance. Moreover, the battery performance using materials from this polymerization-induced phase separation method is reproducible (capacity within 10% batch-to-batch). This simple fabrication methodology may be extendable to other systems and provides a facile route to generate reproducible hierarchical porous morphology that can be beneficial in energy storage applications. PMID:25397899

  18. Porous graphitic carbon nitride synthesized via direct polymerization of urea for efficient sunlight-driven photocatalytic hydrogen production

    NASA Astrophysics Data System (ADS)

    Zhang, Yuewei; Liu, Jinghai; Wu, Guan; Chen, Wei

    2012-08-01

    Energy captured directly from sunlight provides an attractive approach towards fulfilling the need for green energy resources on the terawatt scale with minimal environmental impact. Collecting and storing solar energy into fuel through photocatalyzed water splitting to generate hydrogen in a cost-effective way is desirable. To achieve this goal, low cost and environmentally benign urea was used to synthesize the metal-free photocatalyst graphitic carbon nitride (g-C3N4). A porous structure is achieved via one-step polymerization of the single precursor. The porous structure with increased BET surface area and pore volume shows a much higher hydrogen production rate under simulated sunlight irradiation than thiourea-derived and dicyanamide-derived g-C3N4. The presence of an oxygen atom is presumed to play a key role in adjusting the textural properties. Further improvement of the photocatalytic function can be expected with after-treatment due to its rich chemistry in functionalization.Energy captured directly from sunlight provides an attractive approach towards fulfilling the need for green energy resources on the terawatt scale with minimal environmental impact. Collecting and storing solar energy into fuel through photocatalyzed water splitting to generate hydrogen in a cost-effective way is desirable. To achieve this goal, low cost and environmentally benign urea was used to synthesize the metal-free photocatalyst graphitic carbon nitride (g-C3N4). A porous structure is achieved via one-step polymerization of the single precursor. The porous structure with increased BET surface area and pore volume shows a much higher hydrogen production rate under simulated sunlight irradiation than thiourea-derived and dicyanamide-derived g-C3N4. The presence of an oxygen atom is presumed to play a key role in adjusting the textural properties. Further improvement of the photocatalytic function can be expected with after-treatment due to its rich chemistry in functionalization. Electronic supplementary information (ESI) available: Methods for preparing and characterizing UCN, TCN and DCN samples. Methods for examining the photocatalytic hydrogen production. FTIR, XPS, and digital photos of three products are shown in Fig. S1-6. See DOI: 10.1039/c2nr30948c

  19. Scaffold development using selective laser sintering of polyetheretherketone-hydroxyapatite biocomposite blends.

    PubMed

    Tan, K H; Chua, C K; Leong, K F; Cheah, C M; Cheang, P; Abu Bakar, M S; Cha, S W

    2003-08-01

    In tissue engineering (TE), temporary three-dimensional scaffolds are essential to guide cell proliferation and to maintain native phenotypes in regenerating biologic tissues or organs. To create the scaffolds, rapid prototyping (RP) techniques are emerging as fabrication techniques of choice as they are capable of overcoming many of the limitations encountered with conventional manual-based fabrication processes. In this research, RP fabrication of solvent free porous polymeric and composite scaffolds was investigated. Biomaterials such as polyetheretherketone (PEEK) and hydroxyapatite (HA) were experimentally processed on a commercial selective laser sintering (SLS) RP system. The SLS technique is highly advantageous as it provides good user control over the microstructures of created scaffolds by adjusting the SLS process parameters. Different weight percentage (wt%) compositions of physically mixed PEEK/HA powder blends were sintered to assess their suitability for SLS processing. Microstructural assessments of the scaffolds were conducted using electron microscopy. The results ascertained the potential of SLS-fabricated TE scaffolds. PMID:12895584

  20. Vapor deposition polymerization of aniline on 3D hierarchical porous carbon with enhanced cycling stability as supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Zhao, Yufeng; Zhang, Zhi; Ren, Yuqin; Ran, Wei; Chen, Xinqi; Wu, Jinsong; Gao, Faming

    2015-07-01

    In this work, a polyaniline coated hierarchical porous carbon (HPC) composite (PANI@HPC) is developed using a vapor deposition polymerization technique. The as synthesized composite is applied as the supercapacitor electrode material, and presents a high specific capacitance of 531 F g-1 at current density of 0.5 A g-1 and superior cycling stability of 96.1% (after 10,000 charge-discharge cycles at current density of 10 A g-1). This can be attributed to the maximized synergistic effect of PANI and HPC. Furthermore, an aqueous symmetric supercapacitor device based on PANI@HPC is fabricated, demonstrating a high specific energy of 17.3 Wh kg-1.

  1. In vivo vascularization of anisotropic channeled porous polylactide-based capsules for islet transplantation: the effects of scaffold architecture and implantation site.

    PubMed

    Kasoju, N; Kubies, D; Fbryov, E; K?, J; Kumorek, M M; Sticov, E; Ryp?ek, F

    2015-01-01

    The replacement of pancreatic islets for the possible treatment of type 1 diabetes is limited by the extremely high oxygen demand of the islets. To this end, here we hypothesize to create a novel extra-hepatic highly-vascularized bioartificial cavity using a porous scaffold as a template and using the host body as a living bioreactor for subsequent islet transplantation. Polylactide-based capsular-shaped anisotropic channeled porous scaffolds were prepared by following the unidirectional thermally-induced phase separation technique, and were implanted under the skin and in the greater omentum of Brown Norway rats. Polyamide mesh-based isotropic regular porous capsules were used as the controls. After 4weeks, the implants were excised and analyzed by histology. The hematoxylin and eosin, as well as Masson's trichrome staining, revealed a) low or no infiltration of giant inflammatory cells in the implant, b) minor but insignificant fibrosis around the implant, c) guided infiltration of host cells in the test capsule in contrast to random cell infiltration in the control capsule, and d) relatively superior cell infiltration in the capsules implanted in the greater omentum than in the capsules implanted under the skin. Furthermore, the anti-CD31 immunohistochemistry staining revealed numerous vessels at the implant site, but mostly on the external surface of the capsules. Taken together, the current study, the first of its kind, is a significant step-forward towards engineering a bioartificial microenvironment for the transplantation of islets. PMID:26447597

  2. Effect of different hydroxyapatite incorporation methods on the structural and biological properties of porous collagen scaffolds for bone repair.

    PubMed

    Ryan, Alan J; Gleeson, John P; Matsiko, Amos; Thompson, Emmet M; O'Brien, Fergal J

    2015-12-01

    Scaffolds which aim to provide an optimised environment to regenerate bone tissue require a balance between mechanical properties and architecture known to be conducive to enable tissue regeneration, such as a high porosity and a suitable pore size. Using freeze-dried collagen-based scaffolds as an analogue of native ECM, we sought to improve the mechanical properties by incorporating hydroxyapatite (HA) in different ways while maintaining a pore architecture sufficient to allow cell infiltration, vascularisation and effective bone regeneration. Specifically we sought to elucidate the effect of different hydroxyapatite incorporation methods on the mechanical, morphological, and cellular response of the resultant collagen-HA scaffolds. The results demonstrated that incorporating either micron-sized (CHA scaffolds) or nano-sized HA particles (CnHA scaffolds) prior to freeze-drying resulted in moderate increases in stiffness (2.2-fold and 6.2-fold, respectively, vs. collagen-glycosaminoglycan scaffolds, P < 0.05, a scaffold known to support osteogenesis), while enabling good cell attachment, and moderate mesenchymal stem cell (MSC)-mediated calcium production after 28 days' culture (2.1-fold, P < 0.05, and 1.3-fold, respectively, vs. CG scaffolds). However, coating of collagen scaffolds with a hydroxyapatite precipitate after freeze-drying (CpHA scaffolds) has been shown to be a highly effective method to increase the compressive modulus (26-fold vs. CG controls, P < 0.001) of scaffolds while maintaining a high porosity (~ 98%). The coating of the ligand-dense collagen structure results in a lower cell attachment level (P < 0.05), although it supported greater cell-mediated calcium production (P < 0.0001) compared with other scaffold variants after 28 days' culture. The comparatively good mechanical properties of these high porosity scaffolds is obtained partially through highly crosslinking the scaffolds with both a physical (DHT) and chemical (EDAC) crosslinking treatment. Control of scaffold microstructure was examined via alterations in freezing temperature. It was found that the addition of HA prior to freeze-drying generally reduced the pore size and so the CpHA scaffold fabrication method offered increased control over the resulting scaffolds microstructure. These findings will help guide future design considerations for composite biomaterials and demonstrate that the method of HA incorporation can have profound effects on the resulting scaffold structural and biological response. PMID:25409684

  3. Extraction of naphthenic acid from kerosene using porous and nonporous polymeric membranes

    SciTech Connect

    Netke, S.A.; Pangarkar, V.G.

    1996-01-01

    A systematic study of membrane-assisted extraction of naphthenic acids from hydrocarbon fractions by aqueous caustic soda using both porous and nonporous membranes is reported. The effects of hydrodynamic factors, concentration of naphthenic acids and caustic soda, and temperature on the transmembrane flux are discerned. The film model is used to determine the intrinsic mass transfer characteristics of the membranes.

  4. Free-form-fabricated commercially pure Ti and Ti6Al4V porous scaffolds support the growth of human embryonic stem cell-derived mesodermal progenitors.

    PubMed

    de Peppo, G M; Palmquist, A; Borchardt, P; Lenners, M; Hyllner, J; Snis, A; Lausmaa, J; Thomsen, P; Karlsson, C

    2012-01-01

    Commercially-pure titanium (cp-Ti) and the titanium-aluminum-vanadium alloy (Ti6Al4V) are widely used as reconstructive implants for skeletal engineering applications, due to their good mechanical properties, biocompatibility and ability to integrate with the surrounding bone. Electron beam melting technology (EBM) allows the fabrication of customized implants with tailored mechanical properties and high potential in the clinical practice. In order to augment the interaction with the biological tissue, stem cells have recently been combined with metallic scaffolds for skeletal engineering applications. We previously demonstrated that human embryonic stem cell-derived mesodermal progenitors (hES-MPs) hold a great potential to provide a homogeneous and unlimited supply of cells for bone engineering applications. This study demonstrates the effect of EBM-fabricated cp-Ti and Ti6Al4V porous scaffolds on hES-MPs behavior, in terms of cell attachment, growth and osteogenic differentiation. Displaying different chemical composition but similar surface properties, EBM-fabricated cp-Ti and Ti6Al4V scaffolds supported cell attachment and growth, and did not seem to alter the expression of genes involved in osteogenic differentiation and affect the alkaline phosphatase activity. In conclusion, interfacing hES-MPs to EBM-fabricated scaffolds may represent an interesting strategy for design of third-generation biomaterials, with the potential to promote implant integration in clinical conditions characterized by poor bone quality. PMID:22262956

  5. A multistep procedure to prepare pre-vascularized cardiac tissue constructs using adult stem sells, dynamic cell cultures, and porous scaffolds

    PubMed Central

    Pagliari, Stefania; Tirella, Annalisa; Ahluwalia, Arti; Duim, Sjoerd; Goumans, Marie-Josè; Aoyagi, Takao; Forte, Giancarlo

    2014-01-01

    The vascularization of tissue engineered products represents a key issue in regenerative medicine which needs to be addressed before the translation of these protocols to the bedside can be foreseen. Here we propose a multistep procedure to prepare pre-vascularized three-dimensional (3D) cardiac bio-substitutes using dynamic cell cultures and highly porous biocompatible gelatin scaffolds. The strategy adopted exploits the peculiar differentiation potential of two distinct subsets of adult stem cells to obtain human vascularized 3D cardiac tissues. In the first step of the procedure, human mesenchymal stem cells (hMSCs) are seeded onto gelatin scaffolds to provide interconnected vessel-like structures, while human cardiomyocyte progenitor cells (hCMPCs) are stimulated in vitro to obtain their commitment toward the cardiac phenotype. The use of a modular bioreactor allows the perfusion of the whole scaffold, providing superior performance in terms of cardiac tissue maturation and cell survival. Both the cell culture on natural-derived polymers and the continuous medium perfusion of the scaffold led to the formation of a densely packaged proto-tissue composed of vascular-like and cardiac-like cells, which might complete maturation process and interconnect with native tissue upon in vivo implantation. In conclusion, the data obtained through the approach here proposed highlight the importance to provide stem cells with complementary signals in vitro able to resemble the complexity of cardiac microenvironment. PMID:24917827

  6. Grafting of molecularly imprinted polymer to porous polyethylene filtration membranes by plasma polymerization.

    PubMed

    Cowieson, D; Piletska, E; Moczko, E; Piletsky, S

    2013-08-01

    An application of plasma-induced grafting of polyethylene membranes with a thin layer of molecularly imprinted polymer (MIP) was presented. High-density polyethylene (HDPE) membranes, "Vyon," were used as a substrate for plasma grafting modification. The herbicide atrazine, one of the most popular targets of the molecular imprinting, was chosen as a template. The parameters of the plasma treatment were optimized in order to achieve a good balance between polymerization and ablation processes. Modified HDPE membranes were characterized, and the presence of the grafted polymeric layer was confirmed based on the observed weight gain, pore size measurements, and infrared spectrometry. Since there was no significant change in the porosity of the modified membranes, it was assumed that only a thin layer of the polymer was introduced on the surface. The experiments on the re-binding of the template atrazine to the membranes modified with MIP and blank polymers were performed. HDPE membranes which were grafted with polymer using continuous plasma polymerization demonstrated the best result which was expressed in an imprinted factor equal to 3, suggesting that molecular imprinting was successfully achieved. PMID:23748644

  7. In vitro chondrocyte behavior on porous biodegradable poly(e-caprolactone)/polyglycolic acid scaffolds for articular chondrocyte adhesion and proliferation.

    PubMed

    Jonnalagadda, John B; Rivero, Iris V; Dertien, Janet S

    2015-01-01

    In this study, poly(e-caprolactone)/polyglycolic acid (PCL/PGA) scaffolds for repairing articular cartilage were fabricated via solid-state cryomilling along with compression molding and porogen leaching. Four distinct scaffolds were fabricated using this approach by four independent cryomilling times. These scaffolds were assessed for their suitability to promote articular cartilage regeneration with in vitro chondrocyte cell culture studies. The scaffolds were characterized for pore size, porosity, swelling ratio, compressive, and thermal properties. Cryomilling time proved to significantly affect the physical, mechanical, and morphological properties of the scaffolds. In vitro bovine chondrocyte culture was performed dynamically for 1, 7, 14, 28, and 35 days. Chondrocyte viability and adhesion were tested using MTT assay and scanning electron microscopy micrographs. Glycosaminoglycan (GAG) and DNA assays were performed to investigate the extracellular matrix (ECM) formation and cell proliferation, respectively. PCL/PGA scaffolds demonstrated high porosity for all scaffold types. Morphological analysis and poly(ethylene oxide) continuity demonstrated the existence of a co-continuous network of interconnected pores with pore sizes appropriate for tissue engineering and chondrocyte ingrowth. While mean pore size decreased, water uptake and compressive properties increased with increasing cryomilling times. Compressive modulus of 12, 30, and 60 min scaffolds matched the compressive modulus of human articular cartilage. Viable cells increased besides increase in cell proliferation and ECM formation with progress in culture period. Chondrocytes exhibited spherical morphology on all scaffold types. The pore size of the scaffold affected chondrocyte adhesion, proliferation, and GAG secretion. The results indicated that the 12 min scaffolds delivered promising results for applications in articular cartilage repair. PMID:25671317

  8. Vertical ridge augmentation of the atrophic posterior mandible with custom-made, computer-aided design/computer-aided manufacturing porous hydroxyapatite scaffolds.

    PubMed

    Figliuzzi, Michele; Mangano, Francesco Guido; Fortunato, Leonzio; De Fazio, Rossella; Macchi, Aldo; Iezzi, Giovanna; Piattelli, Adriano; Mangano, Carlo

    2013-05-01

    The present study describes a new protocol for the manufacturing of custom-made hydroxyapatite scaffolds using computer-aided design/computer-aided manufacturing (CAD/CAM), to augment posterior mandibular bone and minimize surgery when severe atrophy is present. Computed tomographic images of an atrophic posterior mandible were acquired and modified into a 3-dimensional (3D) reconstruction model. This model was transferred as a stereolithographic file to a CAD program, where virtual 3D reconstructions of the alveolar ridge were performed, drawing 2 anatomically shaped, custom-made scaffolds. Computer-aided-manufacturing software generated a set of tool-paths for manufacture on a computer-numerical-control milling machine into the exact shape of the 3D projects. Clinically sized, anatomically shaped scaffolds were generated from commercially available porous hydroxyapatite blocks. The custom-made scaffolds well matched the shape of the bone defects and could be easily implanted during surgery. This matching of the shape helped to reduce the time for the operation and contributed to the good healing of the defects. At the 6-month recall, a newly formed and well-integrated bone was observed, completely filling the mandibular posterior defects, and implants were placed, with good primary stability. At the 1-year follow-up examination, the implant-supported restorations showed a good functional and esthetic integration. Although this is an interim report, this study demonstrates that anatomically shaped custom-made scaffolds can be fabricated by combining computed tomographic scans and CAD/CAM techniques. Further studies are needed to confirm these results. PMID:23714896

  9. Osteogenic differentiation of dura mater stem cells cultured in vitro on three-dimensional porous scaffolds of poly(?-caprolactone) fabricated via co-extrusion and gas foaming

    PubMed Central

    Aronin, C.E. Petrie; Cooper, J.A.; Sefcik, L.S.; Tholpady, S.S.; Ogle, R.C.; Botchwey, E.A.

    2008-01-01

    A novel scaffold fabrication method utilizing both polymer blend extrusion and gas foaming techniques to control pore size distribution is presented. Seventy five per cent of all pores produced using polymer blend extrusion alone were less than 50 ?m. Introducing a gas technique provided better control of pore size distribution, expanding the range from 0-50 to 0-350 ?m. Varying sintering time, annealing temperature and foaming pressure also helped reduced the percentage of pore sizes below 50 ?m. Scaffolds chosen for in vitro cellular studies had a pore size distribution of 0-300 ?m, average pore size 66 17 ?m, 0.54 0.02% porosity and 98% interconnectivity, measured by micro computed tomography (microCT) analysis. The ability of the scaffolds to support osteogenic differentiation and cranial defect repair was evaluated by static and dynamic (0.035 0.006 m s-1 terminal velocity) cultivation with dura mater stem cells (DSCs). In vitro studies showed minimal increases in proliferation over 28 days in culture in osteogenic media. Alkaline phosphatase expression remained constant throughout the study. Moderate increases in matrix deposition, as assessed by histochemical staining and microCT analysis, occurred at later time points, days 21 and 28. Although constructs cultured dynamically showed greater mineralization than static conditions, these trends were not significant. It remains unclear whether bioreactor culture of DSCs is advantageous for bone tissue engineering applications. However, these studies show that polycaprolactone (PCL) scaffolds alone, without the addition of other co-polymers or ceramics, support long-term attachment and mineralization of DSCs throughout the entire porous scaffold. PMID:18434267

  10. Metal filled porous carbon

    SciTech Connect

    Gross, Adam F.; Vajo, John J.; Cumberland, Robert W.; Liu, Ping; Salguero, Tina T.

    2011-03-22

    A porous carbon scaffold with a surface and pores, the porous carbon scaffold containing a primary metal and a secondary metal, where the primary metal is a metal that does not wet the surface of the pores of the carbon scaffold but wets the surface of the secondary metal, and the secondary metal is interspersed between the surface of the pores of the carbon scaffold and the primary metal.

  11. Enhanced angiogenesis and osteogenesis in critical bone defects by the controlled release of BMP-2 and VEGF: implantation of electron beam melting-fabricated porous Ti6Al4V scaffolds incorporating growth factor-doped fibrin glue.

    PubMed

    Lv, Jia; Xiu, Peng; Tan, Jie; Jia, Zhaojun; Cai, Hong; Liu, Zhongjun

    2015-06-01

    Electron beam melting (EBM)-fabricated porous titanium implants possessing low elastic moduli and tailored structures are promising biomaterials for orthopedic applications. However, the bio-inert nature of porous titanium makes reinforcement with growth factors (GFs) a promising method to enhance implant in vivo performance. Bone-morphogenic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) are key factors of angiogenesis and osteogenesis. Therefore, the present study is aimed at evaluating EBM-fabricated porous titanium implants incorporating GF-doped fibrin glue (FG) as composite scaffolds providing GFs for improvement of angiogenesis and osteogenesis in rabbit femoral condyle defects. BMP-2 and VEGF were added into the constituent compounds of FG, and then this GF-doped FG was subsequently injected into the porous scaffolds. In five groups of implants, angiogenesis and osteogenesis were evaluated at 4?weeks post-implantation using Microfil perfusion and histological analysis: eTi (empty scaffolds), cTi (containing undoped FG), BMP/cTi (containing 50??g rhBMP-2), VEGF/cTi (containing 0.5??g VEGF) and Dual/cTi (containing 50??g rhBMP-2 and 0.5??g VEGF). The results demonstrate that these composite implants are biocompatible and provide the desired gradual release of the bioactive growth factors. Incorporation of GF delivery, whether a single factor or dual factors, significantly enhanced both angiogenesis and osteogenesis inside the porous scaffolds. However, the synergistic effect of the dual factors combination was observable on angiogenesis but absent on osteogenesis. In conclusion, fibrin glue is a biocompatible material that could be employed as a delivery vehicle in EBM-fabricated porous titanium for controlled release of BMP-2 and VEGF. Application of this method for loading a porous titanium scaffold to incorporate growth factors is a convenient and promising strategy for improving osteogenesis of critical-sized bone defects. PMID:26107105

  12. Design and Fabrication of 3D printed Scaffolds with a Mechanical Strength Comparable to Cortical Bone to Repair Large Bone Defects

    NASA Astrophysics Data System (ADS)

    Roohani-Esfahani, Seyed-Iman; Newman, Peter; Zreiqat, Hala

    2016-01-01

    A challenge in regenerating large bone defects under load is to create scaffolds with large and interconnected pores while providing a compressive strength comparable to cortical bone (100–150 MPa). Here we design a novel hexagonal architecture for a glass-ceramic scaffold to fabricate an anisotropic, highly porous three dimensional scaffolds with a compressive strength of 110 MPa. Scaffolds with hexagonal design demonstrated a high fatigue resistance (1,000,000 cycles at 1–10 MPa compressive cyclic load), failure reliability and flexural strength (30 MPa) compared with those for conventional architecture. The obtained strength is 150 times greater than values reported for polymeric and composite scaffolds and 5 times greater than reported values for ceramic and glass scaffolds at similar porosity. These scaffolds open avenues for treatment of load bearing bone defects in orthopaedic, dental and maxillofacial applications.

  13. Design and Fabrication of 3D printed Scaffolds with a Mechanical Strength Comparable to Cortical Bone to Repair Large Bone Defects

    PubMed Central

    Roohani-Esfahani, Seyed-Iman; Newman, Peter; Zreiqat, Hala

    2016-01-01

    A challenge in regenerating large bone defects under load is to create scaffolds with large and interconnected pores while providing a compressive strength comparable to cortical bone (100–150 MPa). Here we design a novel hexagonal architecture for a glass-ceramic scaffold to fabricate an anisotropic, highly porous three dimensional scaffolds with a compressive strength of 110 MPa. Scaffolds with hexagonal design demonstrated a high fatigue resistance (1,000,000 cycles at 1–10 MPa compressive cyclic load), failure reliability and flexural strength (30 MPa) compared with those for conventional architecture. The obtained strength is 150 times greater than values reported for polymeric and composite scaffolds and 5 times greater than reported values for ceramic and glass scaffolds at similar porosity. These scaffolds open avenues for treatment of load bearing bone defects in orthopaedic, dental and maxillofacial applications. PMID:26782020

  14. Design and Fabrication of 3D printed Scaffolds with a Mechanical Strength Comparable to Cortical Bone to Repair Large Bone Defects.

    PubMed

    Roohani-Esfahani, Seyed-Iman; Newman, Peter; Zreiqat, Hala

    2016-01-01

    A challenge in regenerating large bone defects under load is to create scaffolds with large and interconnected pores while providing a compressive strength comparable to cortical bone (100-150?MPa). Here we design a novel hexagonal architecture for a glass-ceramic scaffold to fabricate an anisotropic, highly porous three dimensional scaffolds with a compressive strength of 110?MPa. Scaffolds with hexagonal design demonstrated a high fatigue resistance (1,000,000 cycles at 1-10?MPa compressive cyclic load), failure reliability and flexural strength (30?MPa) compared with those for conventional architecture. The obtained strength is 150 times greater than values reported for polymeric and composite scaffolds and 5 times greater than reported values for ceramic and glass scaffolds at similar porosity. These scaffolds open avenues for treatment of load bearing bone defects in orthopaedic, dental and maxillofacial applications. PMID:26782020

  15. A hypothesis-driven parametric study of effects of polymeric scaffold properties on tissue engineered neovessel formation.

    PubMed

    Miller, Kristin S; Khosravi, Ramak; Breuer, Christopher K; Humphrey, Jay D

    2015-01-01

    Continued advances in the tissue engineering of vascular grafts have enabled a paradigm shift from the desire to design for adequate suture retention, burst pressure and thrombo-resistance to the goal of achieving grafts having near native properties, including growth potential. Achieving this far more ambitious outcome will require the identification of optimal, not just adequate, scaffold structure and material properties. Given the myriad possible combinations of scaffold parameters, there is a need for a new strategy for reducing the experimental search space. Toward this end, we present a new modeling framework for in vivo neovessel development that allows one to begin to assess in silico the potential consequences of different combinations of scaffold structure and material properties. To restrict the number of parameters considered, we also utilize a non-dimensionalization to identify key properties of interest. Using illustrative constitutive relations for both the evolving fibrous scaffold and the neotissue that develops in response to inflammatory and mechanobiological cues, we show that this combined non-dimensionalization computational approach predicts salient aspects of neotissue development that depend directly on two key scaffold parameters, porosity and fiber diameter. We suggest, therefore, that hypothesis-driven computational models should continue to be pursued given their potential to identify preferred combinations of scaffold parameters that have the promise of improving neovessel outcome. In this way, we can begin to move beyond a purely empirical trial-and-error search for optimal combinations of parameters and instead focus our experimental resources on those combinations that are predicted to have the most promise. PMID:25288519

  16. A Hypothesis-Driven Parametric Study of Effects of Polymeric Scaffold Properties on Tissue Engineered Neovessel Formation

    PubMed Central

    Miller, Kristin S.; Khosravi, Ramak; Breuer, Christopher K.; Humphrey, Jay D.

    2014-01-01

    Continued advances in the tissue engineering of vascular grafts have enabled a paradigm shift from the desire to design for adequate suture retention, burst pressure, and thrombo-resistance to the goal of achieving grafts having near native properties, including growth potential. Achieving this far more ambitious outcome will require the identification of optimal, not just adequate, scaffold structure and material properties. Given the myriad possible combinations of scaffold parameters, there is a need for a new strategy for reducing the experimental search space. Toward this end, we present a new modeling framework for in vivo neovessel development that allows one to begin to assess in silico the potential consequences of different combinations of scaffold structure and material properties. To restrict the number of parameters considered, we also utilize a non-dimensionalization to identify key properties of interest. Using illustrative constitutive relations for both the evolving fibrous scaffold and the neotissue that develops in response to inflammatory and mechanobiological cues, we show that this combined nondimensionalization computational approach predicts salient aspects of neotissue development that depend directly on two key scaffold parameters, porosity and fiber diameter. We suggest, therefore, that hypothesis-driven computational models should continue to be pursued given their potential to identify preferred combinations of scaffold parameters that have the promise of improving neovessel outcome. In this way, we can begin to move beyond a purely empirical trial-and-error search for optimal combinations of parameters and instead focus our experimental resources on those combinations that are predicted to have the most promise. PMID:25288519

  17. MicroRNA-26a-modified adipose-derived stem cells incorporated with a porous hydroxyapatite scaffold improve the repair of bone defects

    PubMed Central

    WANG, ZHENLIN; ZHANG, DAWEI; HU, ZHIQIANG; CHENG, JIWEI; ZHUO, CHUANMENG; FANG, XIANCONG; XING, YONGMING

    2015-01-01

    Tissue-engineered bone substitutes are frequently used to repair bone defects. Adipose-derived stem cells (ASCs) are a promising source of cells for repairing bone tissue, however, insufficient osteogenic potency remains the main obstacle for their application. The present study aimed to enhance the osteogenic potency of ASCs by transfection of microRNA (miR)-26a, a novel osteogenic and angiogenic promoting miRNA. An inverted fluorescence microscope was used to observe transfection efficiency, while a scanning electron microscope was used to detect morphological alterations. Cell proliferation was monitored continuously for 7 days using a Cell Counting kit-8 assay. Osteogenic differentiation was determined by reverse transcription quantitative polymerase chain reaction, alkaline phosphatase (ALP) staining, collagen secretion and extracellular matrix (ECM) mineralization. ASCs were incorporated with a porous hydroxyapatite (HA) scaffold to create a novel tissue-engineered bone substitute and inserted into the critical tibia defect of rats. New bone formation was evaluated by hematoxylin and eosin and Masson's trichrome staining. The results demonstrated that miR-26a was successfully delivered into the cytoplasm, while the morphology and proliferation of ASCs were not significantly altered. Osteogenic-associated genes were markedly upregulated and ALP production, collagen secretion and ECM mineralization were all increased following transfection of miR-26a. Histological evaluation demonstrated that the modified cells accompanied with a porous HA scaffold markedly promoted new bone formation within the defective area. In conclusion, miR-26a transfection significantly improved the osteogenic potency of ASCs suggesting that modified ASCs incorporated with a HA scaffold may be used as a potential bone substitute. PMID:25997460

  18. In situ polymerization into porous ceramics: a novel route to tough biomimetic materials.

    PubMed

    Pezzotti, G; Asmus, S M F; Ferroni, L P; Miki, S

    2002-08-01

    A hydroxyapatite-based biomimetic composite, which is henceforth referred to as a synthetic bony material with high toughness characteristics, was prepared. It was obtained from a hydroxyapatite (HAp) skeleton with a relative porosity fraction of approximately 32 vol %, prepared by cold-isostatic-press compaction, followed by a sintering process, leading to a hydroxyapatite structure containing percolated submicrometer porosity channels. The percolated pores were infiltrated with a liquid mixture of epsilon-caprolactam monomer and an initiator, before homogeneous in situ polymerization to 6-nylon within the fully percolated pore structure was induced thermally. The final composite consisted of a dense interpenetrated hydroxyapatite/6-nylon network in a fraction approximately 68/30 vol %. The work of fracture value of the hybrid composite was found to be comparable with those found in two natural materials (bovine femur and nacre), which were also investigated under the same testing conditions. PMID:15348565

  19. Evaluation of a combined drug-delivery system for proteins assembled with polymeric nanoparticles and porous microspheres; characterization and protein integrity studies.

    PubMed

    Alcalá-Alcalá, Sergio; Benítez-Cardoza, Claudia G; Lima-Muñoz, Enrique J; Piñón-Segundo, Elizabeth; Quintanar-Guerrero, David

    2015-07-15

    This work presents an evaluation of the adsorption/infiltration process in relation to the loading of a model protein, α-amylase, into an assembled biodegradable polymeric system, free of organic solvents and made up of poly(D,L-lactide-co-glycolide) acid (PLGA). Systems were assembled in a friendly aqueous medium by adsorbing and infiltrating polymeric nanoparticles into porous microspheres. These assembled systems are able to load therapeutic amounts of the drug through adsorption of the protein onto the large surface area characteristic of polymeric nanoparticles. The subsequent infiltration of nanoparticles adsorbed with the protein into porous microspheres enabled the controlled release of the protein as a function of the amount of infiltrated nanoparticles, since the surface area available on the porous structure is saturated at different levels, thus modifying the protein release rate. Findings were confirmed by both the BET technique (N2 isotherms) and in vitro release studies. During the adsorption process, the pH of the medium plays an important role by creating an environment that favors adsorption between the surfaces of the micro- and nano-structures and the protein. Finally, assays of α-amylase activity using 2-chloro-4-nitrophenyl-α-D-maltotrioside (CNP-G3) as the substrate and the circular dichroism technique confirmed that when this new approach was used no conformational changes were observed in the protein after release. PMID:25936624

  20. A one-step method to fabricate PLLA scaffolds with deposition of bioactive hydroxyapatite and collagen using ice-based microporogens.

    PubMed

    Li, Jiashen; Chen, Yun; Mak, Arthur F T; Tuan, Rocky S; Li, Lin; Li, Yi

    2010-06-01

    Porous poly(l-lactic acid) (PLLA) scaffolds with bioactive coatings were prepared by a novel one-step method. In this process, ice-based microporogens containing bioactive molecules, such as hydroxyapatite (HA) and collagen, served as both porogens to form the porous structure and vehicles to transfer the bioactive molecules to the inside of PLLA scaffolds in a single step. Based on scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy analysis, the bioactive components were found to be transferred successfully from the porogens to PLLA scaffolds evenly. Osteoblast cells were used to evaluate the cellular behaviors of the composite scaffolds. After culturing for 8days, MTT assay and alkaline phosphatase activity results suggested that HA/collagen could improve the interactions between osteoblast cells and the polymeric scaffold. PMID:20004261

  1. A one-step method to fabricate PLLA scaffolds with deposition of bioactive hydroxyapatite and collagen using ice-based microporogens

    PubMed Central

    Li, Jiashen; Chen, Yun; Mak, Arthur F.T.; Tuan, Rocky S.; Li, Lin; Li, Yi

    2010-01-01

    Porous poly(L-lactic acid) (PLLA) scaffolds with bioactive coatings were prepared by a novel one-step method. In this process, ice-based microporogens containing bioactive molecules, such as hydroxyapatite (HA) and collagen, served as both porogens to form the porous structure and vehicles to transfer the bioactive molecules to the inside of PLLA scaffolds in a single step. Based on scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis, the bioactive components were found to be transferred successfully from the porogens to PLLA scaffolds evenly. Osteoblast cells were used to evaluate the cellular behaviors of the composite scaffolds. After 8 days culturing, MTT assay and alkaline phosphatase (ALP) activity results suggested that HA/collagen could improve the interactions between osteoblast cells and the polymeric scaffold. PMID:20004261

  2. Injectable PolyMIPE Scaffolds for Soft Tissue Regeneration

    PubMed Central

    Moglia, Robert S.; Robinson, Jennifer L.; Muschenborn, Andrea D.; Touchet, Tyler J.; Maitland, Duncan J.; Cosgriff-Hernandez, Elizabeth

    2013-01-01

    Injury caused by trauma, burns, surgery, or disease often results in soft tissue loss leading to impaired function and permanent disfiguration. Tissue engineering aims to overcome the lack of viable donor tissue by fabricating synthetic scaffolds with the requisite properties and bioactive cues to regenerate these tissues. Biomaterial scaffolds designed to match soft tissue modulus and strength should also retain the elastomeric and fatigue-resistant properties of the tissue. Of particular design importance is the interconnected porous structure of the scaffold needed to support tissue growth by facilitating mass transport. Adequate mass transport is especially true for newly implanted scaffolds that lack vasculature to provide nutrient flux. Common scaffold fabrication strategies often utilize toxic solvents and high temperatures or pressures to achieve the desired porosity. In this study, a polymerized medium internal phase emulsion (polyMIPE) is used to generate an injectable graft that cures to a porous foam at body temperature without toxic solvents. These poly(ester urethane urea) scaffolds possess elastomeric properties with tunable compressive moduli (20200 kPa) and strengths (460 kPa) as well as high recovery after the first conditioning cycle (9799%). The resultant pore architecture was highly interconnected with large voids (0.52 mm) from carbon dioxide generation surrounded by water-templated pores (50300 ?m). The ability to modulate both scaffold pore architecture and mechanical properties by altering emulsion chemistry was demonstrated. Permeability and form factor were experimentally measured to determine the effects of polyMIPE composition on pore interconnectivity. Finally, initial human mesenchymal stem cell (hMSC) cytocompatibility testing supported the use of these candidate scaffolds in regenerative applications. Overall, these injectable polyMIPE foams show strong promise as a biomaterial scaffold for soft tissue repair. PMID:24563552

  3. Smart Porous Silicon Nanoparticles with Polymeric Coatings for Sequential Combination Therapy.

    PubMed

    Xu, Wujun; Thapa, Rinez; Liu, Dongfei; Nissinen, Tuomo; Granroth, Sari; Närvänen, Ale; Suvanto, Mika; Santos, Hélder A; Lehto, Vesa-Pekka

    2015-11-01

    In spite of the advances in drug delivery, the preparation of smart nanocomposites capable of precisely controlled release of multiple drugs for sequential combination therapy is still challenging. Here, a novel drug delivery nanocomposite was prepared by coating porous silicon (PSi) nanoparticles with poly(beta-amino ester) (PAE) and Pluronic F-127, respectively. Two anticancer drugs, doxorubicin (DOX) and paclitaxel (PTX), were separately loaded into the core of PSi and the shell of F127. The nanocomposite displayed enhanced colloidal stability and good cytocompatibility. Moreover, a spatiotemporal drug release was achieved for sequential combination therapy by precisely controlling the release kinetics of the two tested drugs. The release of PTX and DOX occurred in a time-staggered manner; PTX was released much faster and earlier than DOX at pH 7.0. The grafted PAE on the external surface of PSi acted as a pH-responsive nanovalve for the site-specific release of DOX. In vitro cytotoxicity tests demonstrated that the DOX and PTX coloaded nanoparticles exhibited a better synergistic effect than the free drugs in inducing cellular apoptosis. Therefore, the present study demonstrates a promising strategy to enhance the efficiency of combination cancer therapies by precisely controlling the release kinetics of different drugs. PMID:26390039

  4. Porous and strong bioactive glass (13–93) scaffolds prepared by unidirectional freezing of camphene-based suspensions

    PubMed Central

    Liu, Xin; Rahaman, Mohamed N.; Fu, Qiang; Tomsia, Antoni P.

    2011-01-01

    Scaffolds of 13–93 bioactive glass (6Na2O, 12K2O, 5MgO, 20CaO, 4P2O5, 53SiO2; wt %) with an oriented pore architecture were formed by unidirectional freezing of camphene-based suspensions, followed by thermal annealing of the frozen constructs to grow the camphene crystals. After sublimation of the camphene, the constructs were sintered (1 h at 700 °C) to produce a dense glass phase with oriented macropores. The objective of this work was to study how constant freezing rates (1–7 °C/min) during the freezing step influenced the pore orientation and mechanical response of the scaffolds. When compared to scaffolds prepared by freezing the suspensions on a substrate kept at a constant temperature of 3 °C (time-dependent freezing rate), higher freezing rates resulted in better pore orientation, a more homogeneous microstructure, and a marked improvement in the mechanical response of the scaffolds in compression. Scaffolds fabricated using a constant freezing rate of 7 °C/min (porosity = 50 ± 4%; average pore diameter = 100 μm), had a compressive strength of 47 ± 5 MPa and an elastic modulus of 11 ± 3 GPa (in the orientation direction). In comparison, scaffolds prepared by freezing on the constant-temperature substrate had strength and modulus values of 35 ± 11 MPa and 8 ± 3 GPa, respectively. These oriented bioactive glass scaffolds prepared by the constant freezing rate route could potentially be used for the repair of defects in load-bearing bones, such as segmental defects in the long bones. PMID:21855661

  5. Extracellular matrix-enriched polymeric scaffolds as a substrate for hepatocyte cultures: in vitro and in vivo studies.

    PubMed

    Zavan, B; Brun, P; Vindigni, V; Amadori, A; Habeler, W; Pontisso, P; Montemurro, D; Abatangelo, G; Cortivo, R

    2005-12-01

    Tissue engineering is a promising approach to developing hepatic tissue suitable for the functional replacement of a failing liver. The aim of the present study was to investigate whether an extracellular cell matrix obtained from fibroblasts-cultured within scaffolds of hyaluronic acid (HYAFF) could influence the proliferation rate and survival of rat hepatocytes both during long-term culture and after in vivo transplantation. Cultures were evaluated by histological and morphological analysis, a proliferation assay and metabolic activity (albumin secretion). Hepatocytes cultured in extracellular matrix-enriched scaffolds exhibited a round cellular morphology and re-established cell-cell contacts, growing into aggregates of several cells along and/or among fibers in the fabric. Hepatocytes were able to secrete albumin up to 14 days in culture. In vivo results demonstrated the biocompatibility of HYAFF-11 implanted in nude mice, in which hepatocytes maintained small well-organised aggregates until the 35th day. In conclusion, the presence of a fibroblast-secreted extracellular matrix improved the biological properties of the hyaluronan scaffold, favoring the survival and morphological integrity of hepatocytes in vitro and in vivo. PMID:15993941

  6. Biotin-avidin mediates the binding of adipose-derived stem cells to a porous β-tricalcium phosphate scaffold: Mandibular regeneration

    PubMed Central

    FENG, ZIHAO; LIU, JIAQI; SHEN, CONGCONG; LU, NANHANG; ZHANG, YONG; YANG, YANWEN; QI, FAZHI

    2016-01-01

    The present study aimed to investigate the properties of a promising bone scaffold for bone repair, which consisted of a novel composite of adipose-derived stem cells (ADSCs) attached to a porous β-tricalcium phosphate (β-TCP) scaffold with platelet-rich plasma (PRP). The β-TCP powder was synthesized and its composition was determined using X-ray diffraction and Fourier transform infrared spectroscopy. The surface morphology and microstructure of the fabricated porous β-TCP scaffold samples were analyzed using light and scanning electron microscopy, and their porosity and compressive strength were also evaluated. In addition, the viability of rabbit ADSCs incubated with various concentrations of the β-TCP extraction fluid was analyzed. The rate of attachment and the morphology of biotinylated ADSCs (Bio-ADSCs) on avidin-coated β-TCP (Avi-β-TCP), and untreated ADSCs on β-TCP, were compared. Furthermore, in vivo bone-forming abilities were determined following the implantation of group 1 (Bio-ADSCs/Avi-β-TCP) and group 2 (Bio-ADSCs/Avi-β-TCP/PRP) constructs using computed tomography, and histological osteocalcin (OCN) and alkaline phosphatase (ALP) expression analyses in a rabbit model of mandibulofacial defects. The β-TCP scaffold exhibited a high porosity (71.26±0.28%), suitable pore size, and good mechanical strength (7.93±0.06 MPa). Following incubation with β-TCP for 72 h, 100% of viable ADSCs remained. The avidin-biotin binding system significantly increased the initial attachment rate of Bio-ADSCs to Avi-β-TCP in the first hour (P<0.01). Following the addition of PRP, group 2 exhibited a bony-union and mandibular body shape, newly formed bone and increased expression levels of OCN and ALP in the mandibulofacial defect area, as compared with group 1 (P<0.05). The results of the present study suggested that the novel Bio-ADSCs/Avi-β-TCP/PRP composite may have potential application in bone repair and bone tissue engineering. PMID:26997987

  7. Preparation of a porous conductive scaffold from aniline pentamer-modified polyurethane/PCL blend for cardiac tissue engineering.

    PubMed

    Baheiraei, Nafiseh; Yeganeh, Hamid; Ai, Jafar; Gharibi, Reza; Ebrahimi-Barough, Somayeh; Azami, Mahmoud; Vahdat, Sadaf; Baharvand, Hossein

    2015-10-01

    A novel biodegradable electroactive polyurethane containing aniline pentamer (AP) was blended with polycaprolactone (PCL). The prepared blend (PB) and PCL were further fabricated in to scaffolds using a mixture of poly(ethylene glycol) and salt particles in a double porogen particulate leaching and compression molding methodology. Scaffolds held open and interconnected pores having pore size ranging from several ?m to 150 m. PB scaffolds had compression modulus and strength of 4.1 and 1.3 MPa, respectively. The conductivity of the scaffold was measured as 10(-5) 0.09 S .cm(-1) and preserved for at least 100 h post fabrication. Scaffolds supported neonatal cardiomyocytes adhesion and growth with PB showing more extensive effect on the expression of the cardiac genes involved in muscle contraction and relaxation (troponin-T) and cytoskeleton alignment (actinin-4). Our results highlight the potential of incorporation of AP as an electroactive moiety for induction of cardiomyocyte proliferation and repair of damaged heart tissue. PMID:25765879

  8. Bone Regeneration of Hydroxyapatite/Alumina Bilayered Scaffold with 3?mm Passage-Like Medullary Canal in Canine Tibia Model

    PubMed Central

    Kim, Jong Min; Son, Jun Sik; Kim, Gonhyung; Choi, Seok Hwa

    2015-01-01

    The aim of this study was to evaluate the bone regeneration of hydroxyapatite (HA)/alumina bilayered scaffold with a 3?mm passage-like medullary canal in a beagle tibia model. A porous HA/alumina scaffold was fabricated using a polymeric template-coating technique. HA/alumina scaffold dimensions were 10?mm in outer diameter, 20?mm in length, and with either a 3?mm passage or no passage. A 20?mm segmental defect was induced using an oscillating saw through the diaphysis of the beagle tibia. The defects of six beagles were filled with HA/alumina bilayered scaffolds with a 3?mm passage or without. The segmental defect was fixated using one bone plate and six screws. Bone regeneration within the HA/alumina scaffolds was observed at eight weeks after implantation. The evaluation of bone regeneration within the scaffolds after implantation in a beagle tibia was performed using radiography, computerized tomography (CT), micro-CT, and fluorescence microscopy. New bone successfully formed in the tibia defects treated with 3?mm passage HA/alumina scaffolds compared to without-passage HA/alumina scaffolds. It was concluded that the HA/alumina bilayered scaffold with 3?mm passage-like medullary canal was instrumental in inducing host-scaffold engraftment of the defect as well as distributing the newly formed bone throughout the scaffold at 8 weeks after implantation. PMID:25688353

  9. Bone regeneration of hydroxyapatite/alumina bilayered scaffold with 3?mm passage-like medullary canal in canine tibia model.

    PubMed

    Kim, Jong Min; Son, Jun Sik; Kang, Seong Soo; Kim, Gonhyung; Choi, Seok Hwa

    2015-01-01

    The aim of this study was to evaluate the bone regeneration of hydroxyapatite (HA)/alumina bilayered scaffold with a 3?mm passage-like medullary canal in a beagle tibia model. A porous HA/alumina scaffold was fabricated using a polymeric template-coating technique. HA/alumina scaffold dimensions were 10?mm in outer diameter, 20?mm in length, and with either a 3?mm passage or no passage. A 20?mm segmental defect was induced using an oscillating saw through the diaphysis of the beagle tibia. The defects of six beagles were filled with HA/alumina bilayered scaffolds with a 3?mm passage or without. The segmental defect was fixated using one bone plate and six screws. Bone regeneration within the HA/alumina scaffolds was observed at eight weeks after implantation. The evaluation of bone regeneration within the scaffolds after implantation in a beagle tibia was performed using radiography, computerized tomography (CT), micro-CT, and fluorescence microscopy. New bone successfully formed in the tibia defects treated with 3?mm passage HA/alumina scaffolds compared to without-passage HA/alumina scaffolds. It was concluded that the HA/alumina bilayered scaffold with 3?mm passage-like medullary canal was instrumental in inducing host-scaffold engraftment of the defect as well as distributing the newly formed bone throughout the scaffold at 8 weeks after implantation. PMID:25688353

  10. Synergetic effect based gel-emulsions and their utilization for the template preparation of porous polymeric monoliths.

    PubMed

    Miao, Qing; Chen, Xiangli; Liu, Lingling; Peng, Junxia; Fang, Yu

    2014-11-18

    A polymerizable cholesteryl derivative (COA) was synthesized and used as a stabilizer for creating gel-emulsions with water in polymerizable monomers, of which they are styrene (ST), tert-butyl methacrylate (t-BMA), ethylene glycol dimethyl acrylate (EGDMA), and methyl methacrylate (MMA), etc. Interestingly, in addition to COA, the presence of a small amount of Span-80 is a necessity for the formation of the monomers containing gel-emulsions. Unlike conventional ones, the volume fraction of the dispersed phase in the gel-emulsions as created could be much lower than 74%, a critical value for routine gel-emulsions. Stabilization of these gel-emulsions as created has been attributed to the synergetic effect between COA, a typical low-molecular-mass gelator (LMMG), and Span-80, a surfactant, of which the former gels the continuous phase and the latter minimizes the interfacial energy of the continuous phase and the dispersed phase. SEM observation confirmed the network structures of COA in the gel-emulsions. Rheological tests demonstrated that the storage modulus, G', and the yield stress of the gel-emulsions decrease along with increasing the volume fraction of the dispersed phase, water, provided it is not greater than 74%-a result inconsistent with the theory explaining formation of routine gel-emulsions and in support of the conclusion that the systems under study follow a different mechanism. Furthermore, unlike LMMG-based stabilizers reported earlier, the gelator, COA, created in the present study has been functioning not only as a stabilizer but also a monomer. To illustrate the conceptual advantages, the gel-emulsions of water in ST/DVB/AIBN were polymerized. As expected, the densities and internal structures of the monoliths as prepared are highly adjustable, functionalization of the materials with cholesterol has been realized, and at the same time the problem of stabilizer leaking has been avoided. A preliminary test for gas adsorption demonstrated that the monoliths as prepared are good adsorbents for some volatile organic compounds (VOCs), in particular benzene, toluene, ethylbenzene, and xylene-the famous and toxic BTEX. It is believed that the findings reported in the present work provide not only a new strategy for creating novel gel-emulsions but also a new route for functionalizing porous polymeric monoliths. PMID:25338107

  11. Research of osteoblastic induced rat bone marrow mesenchymal stem cells cultured on β-TCP/PLLA porous scaffold

    PubMed Central

    Yang, Yi; Wu, Jiang; Jin, Gele; Li, Liang; Li, Zhongwei; Li, Cao

    2015-01-01

    Background: Ceramic and polymer composite scaffolds are widely used in tissue engineering for bone tissue regeneration. Composite of β-tricalcium phosphate (β-TCP) and poly L-lactic acid (PLLA), due to its biocompatibility and biodegradability, is widely used in bioengineering. However, optimal ratio, porosity and pore size of this kind of scaffolds were not very clear yet. Materials and methods: We cultured osteoblastic induced rMSCs on β-TCP/PLLA scaffolds to investigate the optimum construction, which owned better properties for supporting cells growth, proliferation and differentiation. A total of 24 mice were divided into three groups: rMSCs + β-TCP/PLLA, osteoblastic rMSCs + β-TCP/PLLA and β-TCP/PLLA without cells. 8 rude mice were implanted with rMSCs + β-TCP/PLLA in the left thighs and β-TCP/PLLA without cells in the right thighs. 8 rude mice were implanted with osteoblastic rMSCs + β-TCP/PLLA in the left thighs and the same treatments in the right thighs as the above. After 8 and 12 weeks, the mice were sacrificed and implants with the surrounding tissues were harvested together. Paraffin sections were got and HE stain and Masson-Goldner stain were employed to observe the ectopic bone formation. Results: The scaffolds of β-TCP/PLLA = 2:1 significantly increased osteocalcin production of the cells. In addition, scaffolds with NaCl = 70 wt%, pore size 200~450 μm showed better compatibility to these seeding cells. A significantly larger area of bone formation in the osteoblastic rMSCs and β-TCP/PLLA composite than that in rMSCs/scaffold and in the scaffold without cells in vivo. Conclusion: compounds of osteoblastic induced rMSCs and the scaffold with β-TCP/PLLA = 2:1, NaCl = 70 wt%, pore size = 200-450 μm had good properties as a kind of bone substitute. PMID:26064209

  12. DBD atmospheric plasma-modified, electrospun, layer-by-layer polymeric scaffolds for L929 fibroblast cell cultivation.

    PubMed

    Surucu, Seda; Turkoglu Sasmazel, Hilal

    2016-02-01

    This paper reported a study related to atmospheric pressure dielectric barrier discharge (DBD) Ar+O2 and Ar+N2 plasma modifications to alter surface properties of 3D PCL/Chitosan/PCL layer-by-layer hybrid scaffolds and to improve mouse fibroblast (L929 ATCC CCL-1) cell attachment, proliferation, and growth. The scaffolds were fabricated using electrospinning technique and each layer was electrospun sequentially on top of the other. The surface modifications were performed with an atmospheric pressure DBD plasma under different gas flow rates (50, 60, 70, 80, 90, and 100sccm) and for different modification times (0.5-7min), and then the chemical and topographical characterizations of the modified samples were done by contact angle (CA) measurements, scanning electron microscopy (SEM), atomic force microscopy, and X-ray photoelectron spectroscopy. The samples modified with Ar+O2 plasma for 1min under 70cm(3)/min O2 flow rate (71.0773.578) showed a 18.83% decrease compare to unmodified samples' CA value (84.4633.864). Comparing with unmodified samples, the average fiber diameter values for plasma-modified samples by Ar+O2 (1min 70sccm) and Ar+N2 (40s 70sccm) increased 40.756 and 54.295%, respectively. Additionally, the average inter-fiber pore size values exhibited decrease of 37.699 and 48.463% for the same Ar+O2 and Ar+N2 plasma-modified samples, respectively, compare to unmodified samples. Biocompatibility performance was determined with MTT assay, fluorescence, Giemsa, and confocal imaging as well as SEM. The results showed that Ar+O2-based plasma modification increased the hydrophilicity and oxygen functionality of the surface, thus affecting the cell viability and proliferation on/within scaffolds. PMID:26494511

  13. Fabrication of TiO2 nanotubes on porous titanium scaffold and biocompatibility evaluation in vitro and in vivo.

    PubMed

    Fan, Xingping; Feng, Bo; Liu, Zhiyuan; Tan, Jing; Zhi, Wei; Lu, Xiong; Wang, Jianxin; Weng, Jie

    2012-12-01

    Porous titanium was modified by anodic oxidation and heat treatment method. Scanning electron microscopy and X-ray diffraction examinations revealed that the modified surface of porous titanium was covered by anatase nanotubes. In vitro, the bioactivity of specimens before and after modification was evaluated by immersing into the double-concentration simulated body fluid for 7 days. The porous titanium specimens were implanted into the femurs of dogs for 3 months. The osteointegration of the implants was investigated by push-out test and histological examination. The results showed that the porous titanium with anatase nanotubes has the superior ability of apatite formation and a higher push-out force when compared with the other implants. The histological analysis indicated that the implant with anatase nanotubes had excellent ability to facilitate the osteointegration in vivo. PMID:22791689

  14. Modification of the bulk properties of the porous poly(lactide-co-glycolide) scaffold by irradiation with a cyclotron ion beam with high energy for its application in tissue engineering.

    PubMed

    Woo, Jung Hoon; Kim, Do Yeon; Jo, Seong Yeun; Kang, Hyunki; Noh, Insup

    2009-08-01

    Understanding the bulk properties of a prefabricated scaffold for handling and degradation during cell culture may be advantageous to its application in tissue engineering. Modification of the bulk properties of the porous poly(lactide-co-glycolide) (PLGA) scaffold was performed by irradiation with a high energy cyclotron proton ion beam. The porous PLGA scaffolds were fabricated in advance by the gas-foaming method by employing ammonium bicarbonate particles as porogens. Irradiation with ion beams was performed with 40 MeV for 3, 6 and 9 min on the scaffolds at a distance of 30 cm from the beam exit to the scaffold surface. The bulk area of the ion beam-treated PLGA scaffold apparently demonstrated no color changes when observed with a digital camera. The chemical structures of the untreated samples seemed to be kept well when analyzed by both Fourier transformed infrared but a subtle change was observed in its x-ray photoelectron spectroscopy. The results of in vitro tissue culture with smooth muscle cells for up to 4 weeks also demonstrated no significant difference in terms of its handling stability during cell culture and cellular behavior between the untreated PLGA scaffolds and the ion beam-treated ones. However, significant changes were observed in its molecular weight as measured by gel permeation chromatography, indicating a significant reduction of its molecular weights. These results of in vitro tests and GPC measurements indicated that while bulk modification of the scaffold was processed, its handling was stable during in vitro cell culture for up to 4 weeks. PMID:19584424

  15. Influence of 3D porous galactose containing PVA/gelatin hydrogel scaffolds on three-dimensional spheroidal morphology of hepatocytes.

    PubMed

    Vasanthan, Kirthanashri S; Subramaniam, Anuradha; Krishnan, Uma Maheswari; Sethuraman, Swaminathan

    2015-01-01

    Three-dimensional liver scaffolds are temporary framework that mimics native ECM architecture and positively influence hepatocyte lodging, proliferation with retention of metabolic activities. The aim of the current study is to develop galactose containing physical cross-linked polyvinyl alcohol/gelatin (P/G 8:2 and 9:1) hydrogel scaffolds via freeze/thaw technique. The 8:2 and 9:1 P/G hydrogels exhibited comparable pore size and porosity (P > 0.05). The tensile strength of the fabricated 8:2 and 9:1 P/G hydrogel scaffolds were found to be in accordance with native human liver. Pore interconnectivity of both the P/G hydrogel scaffolds was confirmed by scanning electron micrographs and liquid displacement method. Further galactose containing hydrogel promoted cell-cell and cell-hydrogel interaction, aiding cellular aggregation leading to spheroids formation compared to void P/G hydrogel by 7 days. Hence, galactose containing P/G hydrogel could be more promising substrate as it showed significantly higher cell proliferation and albumin secretion for 21 days when compared to non-galactose P/G hydrogels (P < 0.05). PMID:25578699

  16. Improved cell infiltration of highly porous nanofibrous scaffolds formed by combined fiber-fiber charge repulsions and ultra-sonication

    PubMed Central

    Jeong, Sung Isn; Burns, Nancy A.; Bonino, Christopher A.; Kwon, Il Keun; Khan, Saad A.; Alsberg, Eben

    2014-01-01

    A significant problem affecting electrospun nanofibrous tissue scaffolds is poor infiltration of cells into their three-dimensional (3D) structure. Environmental and physical manipulation, however, can enhance cellular infiltration into electrospun scaffolds. In this work, RGD-modified alginate mats with increased thickness and porosity were achieved by pairing high humidity electrospinning with post-processing ultra-sonication. RGD-modified alginate, polyethylene oxide (PEO), and an FDA-approved, nonionic surfactant blends were electrospun in 20 and 50% relative humidity conditions. Mats electrospun in high humidity conditions resulted in significantly increased mat thickness and decreased fiber diameters. The mats alginate content was then isolated via ionic crosslinking and PEO/surfactant extraction. Finally, the alginate-only mat was post-processed by ultra-sonication to further enhance its cross-sectional thickness. Cell morphology, proliferation, and infiltration into the scaffolds were evaluated by seeding fibroblasts onto the alginate mat. Cell spreading, growth and infiltration improved with increased humidity and ultra-sonication. This approach shows great promise for the design of cell-permeable nanofibrous scaffolds for tissue-engineering applications. PMID:25530854

  17. 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.

  18. Polycaprolactone Scaffolds Fabricated via Bioextrusion for Tissue Engineering Applications

    PubMed Central

    Domingos, Marco; Dinucci, Dinuccio; Cometa, Stefania; Alderighi, Michele; Brtolo, Paulo Jorge; Chiellini, Federica

    2009-01-01

    The most promising approach in Tissue Engineering involves the seeding of porous, biocompatible/biodegradable scaffolds, with donor cells to promote tissue regeneration. Additive biomanufacturing processes are increasingly recognized as ideal techniques to produce 3D structures with optimal pore size and spatial distribution, providing an adequate mechanical support for tissue regeneration while shaping in-growing tissues. This paper presents a novel extrusion-based system to produce 3D scaffolds with controlled internal/external geometry for TE applications.The BioExtruder is a low-cost system that uses a proper fabrication code based on the ISO programming language enabling the fabrication of multimaterial scaffolds. Poly(?-caprolactone) was the material chosen to produce porous scaffolds, made by layers of directionally aligned microfilaments. Chemical, morphological, and in vitro biological evaluation performed on the polymeric constructs revealed a high potential of the BioExtruder to produce 3D scaffolds with regular and reproducible macropore architecture, without inducing relevant chemical and biocompatibility alterations of the material. PMID:20126577

  19. Pore size and LbL chitosan coating influence mesenchymal stem cell in vitro fibrosis and biomineralization in 3D porous poly(epsilon-caprolactone) scaffolds.

    PubMed

    Mehr, Nima Ghavidel; Li, Xian; Chen, Gaoping; Favis, Basil D; Hoemann, Caroline D

    2015-07-01

    Poly(epsilon-caprolactone) (PCL) is a hydrophobic bioplastic under development for bone tissue engineering applications. Limited information is available on the role of internal geometry and cell-surface attachment on osseous integration potential. We tested the hypothesis that human bone marrow mesenchymal stem cells (MSCs) deposit more mineral inside porous 3D PCL scaffolds with fully interconnected 84 or 141 m pores, when the surfaces are coated with chitosan via Layer-by-Layer (LbL)-deposited polyelectrolytes. Freshly trypsinized MSCs were seeded on PCL 3D cylinders using a novel static cold seeding method in 2% serum to optimally populate all depths of the scaffold discs, followed by 10 days of culture in proliferation medium and 21 additional days in osteogenic medium. MSCs were observed by SEM and histology to spread faster and to proliferate more on chitosan-coated pore surfaces. Most pores, with or without chitosan, became filled by collagen networks sparsely populated with fibroblast-like cells. After 21 days of culture in osteogenic medium, sporadic matrix mineralization was detected histologically and by micro-CT in highly cellular surface layers that enveloped all scaffolds and in cell aggregates in 141 m pores near the edges. LbL-chitosan promoted punctate mineral deposition on the surfaces of 84 m pores (p?

  20. Fast and continuous preparation of high polymerization degree cellulose nanofibrils and their three-dimensional macroporous scaffold fabrication

    NASA Astrophysics Data System (ADS)

    Song, Jiankang; Tang, Aimin; Liu, Tingting; Wang, Jufang

    2013-02-01

    C6-carboxy-cellulose with a carboxylate content of 0.8 mmol g-1 was obtained by oxidation of once-dried cellulose, using the 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)/NaClO/NaClO2 system at pH 6.8 and 60 C for 16 h. This method, with the addition of reagents in the order TEMPO, NaClO and NaClO2, was 38 h faster than a previously published method. Individualized cellulose nanofibrils with a width of 3-5 nm and a length of several hundred nanometers were prepared by homogenizing the C6-carboxy-cellulose-water suspension. Macroporous cellulose nanofibril/poly(vinyl alcohol) scaffolds with interconnected large pores of 20-100 ?m diameter and small pores of 2-10 ?m diameter were fabricated. The cellulose nanofilaments formed nanofibrous structures on the surface of the PVA wall, which was similar to that of the collagen skeleton of the extracellular matrix. NIH/3T3 cells were cultured in the scaffolds for 4 weeks, SEM observation showed that the cells were anchored and clustered on the cellulose nanofilaments, forming spherical colonies. The extracellular matrix (ECM) was filled with mineralized particles.

  1. Fast and continuous preparation of high polymerization degree cellulose nanofibrils and their three-dimensional macroporous scaffold fabrication.

    PubMed

    Song, Jiankang; Tang, Aimin; Liu, Tingting; Wang, Jufang

    2013-03-21

    C6-carboxy-cellulose with a carboxylate content of 0.8 mmol g(-1) was obtained by oxidation of once-dried cellulose, using the 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)/NaClO/NaClO2 system at pH 6.8 and 60 C for 16 h. This method, with the addition of reagents in the order TEMPO, NaClO and NaClO2, was 38 h faster than a previously published method. Individualized cellulose nanofibrils with a width of 3-5 nm and a length of several hundred nanometers were prepared by homogenizing the C6-carboxy-cellulose-water suspension. Macroporous cellulose nanofibril/poly(vinyl alcohol) scaffolds with interconnected large pores of 20-100 ?m diameter and small pores of 2-10 ?m diameter were fabricated. The cellulose nanofilaments formed nanofibrous structures on the surface of the PVA wall, which was similar to that of the collagen skeleton of the extracellular matrix. NIH/3T3 cells were cultured in the scaffolds for 4 weeks, SEM observation showed that the cells were anchored and clustered on the cellulose nanofilaments, forming spherical colonies. The extracellular matrix (ECM) was filled with mineralized particles. PMID:23412536

  2. Tailoring of processing parameters for sintering microsphere-based scaffolds with dense-phase carbon dioxide

    PubMed Central

    Jeon, Ju Hyeong; Bhamidipati, Manjari; Sridharan, BanuPriya; Scurto, Aaron M.; Berkland, Cory J.; Detamore, Michael S.

    2015-01-01

    Microsphere-based polymeric tissue-engineered scaffolds offer the advantage of shape-specific constructs with excellent spatiotemporal control and interconnected porous structures. The use of these highly versatile scaffolds requires a method to sinter the discrete microspheres together into a cohesive network, typically with the use of heat or organic solvents. We previously introduced subcritical CO2 as a sintering method for microsphere-based scaffolds; here we further explored the effect of processing parameters. Gaseous or subcritical CO2 was used for making the scaffolds, and various pressures, ratios of lactic acid to glycolic acid in poly(lactic acid-co-glycolic acid), and amounts of NaCl particles were explored. By changing these parameters, scaffolds with different mechanical properties and morphologies were prepared. The preferred range of applied subcritical CO2 was 15–25 bar. Scaffolds prepared at 25 bar with lower lactic acid ratios and without NaCl particles had a higher stiffness, while the constructs made at 15 bar, lower glycolic acid content, and with salt granules had lower elastic moduli. Human umbilical cord mesenchymal stromal cells (hUCMSCs) seeded on the scaffolds demonstrated that cells penetrate the scaffolds and remain viable. Overall, the study demonstrated the dependence of the optimal CO2 sintering parameters on the polymer and conditions, and identified desirable CO2 processing parameters to employ in the sintering of microsphere-based scaffolds as a more benign alternative to heat-sintering or solvent-based sintering methods. PMID:23115065

  3. Microwave sintering and in vitro study of defect-free stable porous multilayered HAp-ZrO2 artificial bone scaffold

    NASA Astrophysics Data System (ADS)

    Jang, Dong-Woo; Nguyen, Thi-Hiep; Sarkar, Swapan Kumar; Lee, Byong-Taek

    2012-06-01

    Continuously porous hydroxyapatite (HAp)/t-ZrO2 composites containing concentric laminated frames and microchanneled bodies were fabricated by an extrusion process. To investigate the mechanical properties of HAp/t-ZrO2 composites, the porous composites were sintered at different temperatures using a microwave furnace. The microstructure was designed to imitate that of natural bone, particularly small bone, with both cortical and spongy bone sections. Each microchannel was separated by alternating lamina of HAp, HAp-(t-ZrO2) and t-ZrO2. HAp and ZrO2 phases existed on the surface of the microchannel and the core zone to increase the biocompatibility and mechanical properties of the HAp-ZrO2 artificial bone. The sintering behavior was evaluated and the optimum sintering temperature was found to be 1400 C, which produced a stable scaffold. The material characteristics, such as the microstructure, crystal structure and compressive strength, were evaluated in detail for different sintering temperatures. A detailed in vitro study was carried out using MTT assay, western blot analysis, gene expression by polymerase chain reaction and laser confocal image analysis of cell proliferation. The results confirmed that HAp-ZrO2 performs as an artificial bone, showing excellent cell growth, attachment and proliferation behavior using osteoblast-like MG63 cells.

  4. Biomimetic nanoclay scaffolds for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Ambre, Avinash Harishchandra

    Tissue engineering offers a significant potential alternative to conventional methods for rectifying tissue defects by evoking natural regeneration process via interactions between cells and 3D porous scaffolds. Imparting adequate mechanical properties to biodegradable scaffolds for bone tissue engineering is an important challenge and extends from molecular to macroscale. This work focuses on the use of sodium montmorillonite (Na-MMT) to design polymer composite scaffolds having enhanced mechanical properties along with multiple interdependent properties. Materials design beginning at the molecular level was used in which Na-MMT clay was modified with three different unnatural amino acids and further characterized using Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD). Based on improved bicompatibility with human osteoblasts (bone cells) and intermediate increase in d-spacing of MMT clay (shown by XRD), 5-aminovaleric acid modified clay was further used to prepare biopolymer (chitosan-polygalacturonic acid complex) scaffolds. Osteoblast proliferation in biopolymer scaffolds containing 5-aminovaleric acid modified clay was similar to biopolymer scaffolds containing hydroxyapatite (HAP). A novel process based on biomineralization in bone was designed to prepare 5-aminovaleric acid modified clay capable of imparting multiple properties to the scaffolds. Bone-like apatite was mineralized in modified clay and a novel nanoclay-HAP hybrid (in situ HAPclay) was obtained. FTIR spectroscopy indicated a molecular level organic-inorganic association between the intercalated 5-aminovaleric acid and mineralized HAP. Osteoblasts formed clusters on biopolymer composite films prepared with different weight percent compositions of in situ HAPclay. Human MSCs formed mineralized nodules on composite films and mineralized extracellular matrix (ECM) in composite scaffolds without the use of osteogenic supplements. Polycaprolactone (PCL), a synthetic polymer, was used for preparing composites (films and scaffolds) containing in situ HAPclay. Composite films showed significantly improved nanomechanical properties. Human MSCs formed mineralized ECM on films in absence of osteogenic supplements and were able to infiltrate the scaffolds. Atomic force microscopy imaging of mineralized ECM formed on composite films showed similarities in dimensions, arrangement of collagen and apatite with their natural bone counterparts. This work indicates the potential of in situ HAPclay to impart polymeric scaffolds with osteoinductive, osteoconductive abilities and improve their mechanical properties besides emphasizing nanoclays as cell-instructive materials.

  5. Protein-releasing polymeric scaffolds induce fibrochondrocytic differentiation of endogenous cells for knee meniscus regeneration in sheep.

    PubMed

    Lee, Chang H; Rodeo, Scott A; Fortier, Lisa Ann; Lu, Chuanyong; Erisken, Cevat; Mao, Jeremy J

    2014-12-10

    Regeneration of complex tissues, such as kidney, liver, and cartilage, continues to be a scientific and translational challenge. Survival of ex vivo cultured, transplanted cells in tissue grafts is among one of the key barriers. Meniscus is a complex tissue consisting of collagen fibers and proteoglycans with gradient phenotypes of fibrocartilage and functions to provide congruence of the knee joint, without which the patient is likely to develop arthritis. Endogenous stem/progenitor cells regenerated the knee meniscus upon spatially released human connective tissue growth factor (CTGF) and transforming growth factor-?3 (TGF?3) from a three-dimensional (3D)-printed biomaterial, enabling functional knee recovery. Sequentially applied CTGF and TGF?3 were necessary and sufficient to propel mesenchymal stem/progenitor cells, as a heterogeneous population or as single-cell progenies, into fibrochondrocytes that concurrently synthesized procollagens I and II?. When released from microchannels of 3D-printed, human meniscus scaffolds, CTGF and TGF?3 induced endogenous stem/progenitor cells to differentiate and synthesize zone-specific type I and II collagens. We then replaced sheep meniscus with anatomically correct, 3D-printed scaffolds that incorporated spatially delivered CTGF and TGF?3. Endogenous cells regenerated the meniscus with zone-specific matrix phenotypes: primarily type I collagen in the outer zone, and type II collagen in the inner zone, reminiscent of the native meniscus. Spatiotemporally delivered CTGF and TGF?3 also restored inhomogeneous mechanical properties in the regenerated sheep meniscus. Survival and directed differentiation of endogenous cells in a tissue defect may have implications in the regeneration of complex (heterogeneous) tissues and organs. PMID:25504882

  6. Protein-releasing polymeric scaffolds induce fibrochondrocytic differentiation of endogenous cells for knee meniscus regeneration in sheep

    PubMed Central

    Lee, Chang H.; Rodeo, Scott A.; Fortier, Lisa Ann; Lu, Chuanyong; Erisken, Cevat

    2015-01-01

    Regeneration of complex tissues, such as kidney, liver, and cartilage, continues to be a scientific and translational challenge. Survival of ex vivo cultured, transplanted cells in tissue grafts is among one of the key barriers. Meniscus is a complex tissue consisting of collagen fibers and proteoglycans with gradient phenotypes of fibrocartilage and functions to provide congruence of the knee joint, without which the patient is likely to develop arthritis. Endogenous stem/progenitor cells regenerated the knee meniscus upon spatially released human connective tissue growth factor (CTGF) and transforming growth factor–β3 (TGFβ3) from a three-dimensional (3D)–printed biomaterial, enabling functional knee recovery. Sequentially applied CTGF and TGFβ3 were necessary and sufficient to propel mesenchymal stem/progenitor cells, as a heterogeneous population or as single-cell progenies, into fibrochondrocytes that concurrently synthesized procollagens I and IIα. When released from microchannels of 3D–printed, human meniscus scaffolds, CTGF and TGFβ3 induced endogenous stem/progenitor cells to differentiate and synthesize zone-specific type I and II collagens. We then replaced sheep meniscus with anatomically correct, 3D–printed scaffolds that incorporated spatially delivered CTGF and TGFβ3. Endogenous cells regenerated the meniscus with zone-specific matrix phenotypes: primarily type I collagen in the outer zone, and type II collagen in the inner zone, reminiscent of the native meniscus. Spatiotemporally delivered CTGF and TGFβ3 also restored inhomogeneous mechanical properties in the regenerated sheep meniscus. Survival and directed differentiation of endogenous cells in a tissue defect may have implications in the regeneration of complex (heterogeneous) tissues and organs. PMID:25504882

  7. Functionalized ultra-porous titania nanofiber membranes as nuclear waste separation and sequestration scaffolds for nuclear fuels recycle.

    SciTech Connect

    Liu, Haiqing; Bell, Nelson Simmons; Cipiti, Benjamin B.; Lewis, Tom Goslee,; Sava, Dorina Florentina; Nenoff, Tina Maria

    2012-09-01

    Advanced nuclear fuel cycle concept is interested in reducing separations to a simplified, one-step process if possible. This will benefit from the development of a one-step universal getter and sequestration material so as a simplified, universal waste form was proposed in this project. We have developed a technique combining a modified sol-gel chemistry and electrospinning for producing ultra-porous ceramic nanofiber membranes with controllable diameters and porous structures as the separation/sequestration materials. These ceramic nanofiber materials have been determined to have high porosity, permeability, loading capacity, and stability in extreme conditions. These porous fiber membranes were functionalized with silver nanoparticles and nanocrystal metal organic frameworks (MOFs) to introduce specific sites to capture gas species that are released during spent nuclear fuel reprocessing. Encapsulation into a durable waste form of ceramic composition was also demonstrated.

  8. Porous Yttria-Stabilized Zirconia Microstructures for SOFC Anode Fabrication

    NASA Astrophysics Data System (ADS)

    Palakkathodi Kammampata, Sanoop

    Solid oxide fuel cells (SOFCs) are electrochemical devices that convert fuels, such as hydrogen and natural gas, to electricity at high efficiencies, e.g., up to 90 %. SOFCs are emerging as a key technology for energy production that also minimize greenhouse gas emissions compared to conventional thermal power generation. SOFCs, which are normally based on nickel-yttria stabilized zirconia (YSZ) anodes, undergo degradation with time due to their high operating temperatures and their susceptibility to damage due to anode oxidation (redox cycling) and poisoning. Ni infiltration into porous YSZ scaffolds is considered to be a promising approach for overcoming some of these problems and enhancing their redox tolerance. However, long-term instability of the morphology of these types of anodes is an important problem. The focus of this thesis was therefore to develop methods to form porous YSZ scaffolds and attempt to construct stable Ni-YSZ anodes with reasonable electrochemical performance by infiltration. In this work, the issue of long-term instability was considered to originate from both the porous YSZ scaffold microstructure and the Ni infiltration precursor employed. To study this more closely, two different porous YSZ scaffold microstructures were developed by using tape casting, followed by Ni infiltration using a polymeric precursor, known to form a continuous Ni phase, rather than electrically separated Ni particles. Ni infiltration into porous YSZ scaffolds with large grains (0.5 microm) and large pores (two types of pores: 0.5 microm and 5 microm) resulted in extensive Ni particle growth that resulted in poor stability and poor electrochemical performance (0.5 ? cm2 per electrode at 800C). Ni infiltration into a scaffold having finer grains and pores (200 nm each) resulted in anodes with a much lower polarization resistance of 0.11 ? cm2 per electrode at 800C, increasing by 5 % after 108 hours at this temperature.

  9. Ectopic osteochondral formation of biomimetic porous PVA-n-HA/PA6 bilayered scaffold and BMSCs construct in rabbit.

    PubMed

    Qu, Dan; Li, Jihua; Li, Yubao; Khadka, Ashish; Zuo, Yi; Wang, Hang; Liu, Yiming; Cheng, Lin

    2011-01-01

    In this work, the novel poly vinyl alcohol/gelatin-nano-hydroxyapatite/polyamide6 (PVA-n-HA/PA6) bilayered scaffold with biomimetic properties for articular cartilage and subchondral bone is developed. Furthermore, when these osteochondral scaffolds were seeded with induced bone mesenchymal stem cells (BMSCs) and implanted at ectopic sites, showed the potential for an engineered cartilage tissue and the corresponding subchondral bone. BMSCs were expanded in vitro and induced to chondrogenic or osteogenic potential by culturing in suitable media for 14 days. Subsequently, these induced cells were seeded into PVA-n-HA/PA6 separately, and the constructs were implanted into the rabbit muscle pouch for upto 12 weeks. Ectopic neocartilage formation in the PVA layer and reconstitution of the subchondral bone which remained confined within the n-HA/PA6 layer with the alteration of the cellular phenotype were identified with Masson's trichrome stain. Simultaneously, the RT-PCR results confirmed the expression of specific extracellular matrix (ECM) markers for cartilaginous tissue, such as collagen type II (Col-II), or alternatively, markers for osteoid tissue, such as collagen type I (Col-I) at the corresponding layers. During ectopic implantation, the underlying subchondral bone layer was completely integrated with the cartilage layer. The result from the ectopic osteochondral scaffolds implantation suggests that PVA-n-HA/PA6 with induced BMSCs is a possible substitute with potential in cartilage repair strategies. PMID:20967773

  10. Tailoring the morphology of high molecular weight PLLA scaffolds through bioglass addition.

    PubMed

    Barroca, N; Daniel-da-Silva, A L; Vilarinho, P M; Fernandes, M H V

    2010-09-01

    Thermally induced phase separation (TIPS) has proven to be a suitable method for the preparation of porous structures for tissue engineering applications, and particular attention has been paid to increasing the pore size without the use of possible toxic surfactants. Within this context, an alternative method to control the porosity of polymeric scaffolds via the combination with a bioglass is proposed in this work. The addition of a bioactive glass from the 3CaO x P2O5-MgO-SiO2 system enables the porous structure of high molecular weight poly(l-lactic) acid (PLLA) scaffolds prepared by TIPS to be tailored. Bioglass acts as a nucleating catalyst agent of the PLLA matrix, promoting its crystallization, and the glass solubility controls the pore size. A significant increase in the pore size is observed as the bioglass content increases and scaffolds with large pore size (approximately 150 microm) can be prepared. In addition, the bioactive character of the scaffolds is proved by in vitro tests in synthetic plasma. The importance of this approach resides on the combination of the ability to tailor the porosity of polymeric scaffolds via the tunable solubility of bioglasses, without the use of toxic surfactants, leading to a composite structure with suitable properties for bone tissue engineering applications. PMID:20350622

  11. 3D polylactide-based scaffolds for studying human hepatocarcinoma processes in vitro

    NASA Astrophysics Data System (ADS)

    Scaffaro, Roberto; Lo Re, Giada; Rigogliuso, Salvatrice; Ghersi, Giulio

    2012-08-01

    We evaluated the combination of leaching techniques and melt blending of polymers and particles for the preparation of highly interconnected three-dimensional polymeric porous scaffolds for in vitro studies of human hepatocarcinoma processes. More specifically, sodium chloride and poly(ethylene glycol) (PEG) were used as water-soluble porogens to form porous and solvent-free poly(L,D-lactide) (PLA)-based scaffolds. Several characterization techniques, including porosimetry, image analysis and thermogravimetry, were combined to improve the reliability of measurements and mapping of the size, distribution and microarchitecture of pores. We also investigated the effect of processing, in PLA-based blends, on the simultaneous bulk/surface modifications and pore architectures in the scaffolds, and assessed the effects on human hepatocarcinoma viability and cell adhesion. The influence of PEG molecular weight on the scaffold morphology and cell viability and adhesion were also investigated. Morphological studies indicated that it was possible to obtain scaffolds with well-interconnected pores of assorted sizes. The analysis confirmed that SK-Hep1 cells adhered well to the polymeric support and emitted surface protrusions necessary to grow and differentiate three-dimensional systems. PEGs with higher molecular weight showed the best results in terms of cell adhesion and viability.

  12. Laser printing of cells into 3D scaffolds.

    PubMed

    Ovsianikov, A; Gruene, M; Pflaum, M; Koch, L; Maiorana, F; Wilhelmi, M; Haverich, A; Chichkov, B

    2010-03-01

    One of the most promising approaches in tissue engineering is the application of 3D scaffolds, which provide cell support and guidance in the initial tissue formation stage. The porosity of the scaffold and internal pore organization influence cell migration and play a major role in its biodegradation dynamics, nutrient diffusion and mechanical stability. In order to control cell migration and cellular interactions within the scaffold, novel technologies capable of producing 3D structures in accordance with predefined design are required. The two-photon polymerization (2PP) technique, used in this report for the fabrication of scaffolds, allows the realization of arbitrary 3D structures with submicron spatial resolution. Highly porous 3D scaffolds, produced by 2PP of acrylated poly(ethylene glycol), are seeded with cells by means of laser-induced forward transfer (LIFT). In this laser printing approach, a propulsive force, resulting from laser-induced shock wave, is used to propel individual cells or cell groups from a donor substrate towards the receiver substrate. We demonstrate that with this technique printing of multiple cell types into 3D scaffolds is possible. Combination of LIFT and 2PP provides a route for the realization of 3D multicellular tissue constructs and artificial ECM engineered on the microscale. PMID:20811119

  13. Fabrication of mullite-bonded porous SiC ceramics from multilayer-coated SiC particles through sol-gel and in-situ polymerization techniques

    NASA Astrophysics Data System (ADS)

    Ebrahimpour, Omid

    In this work, mullite-bonded porous silicon carbide (SiC) ceramics were prepared via a reaction bonding technique with the assistance of a sol-gel technique or in-situ polymerization as well as a combination of these techniques. In a typical procedure, SiC particles were first coated by alumina using calcined powder and alumina sol via a sol-gel technique followed by drying and passing through a screen. Subsequently, they were coated with the desired amount of polyethylene via an in-situ polymerization technique in a slurry phase reactor using a Ziegler-Natta catalyst. Afterward, the coated powders were dried again and passed through a screen before being pressed into a rectangular mold to make a green body. During the heating process, the polyethylene was burnt out to form pores at a temperature of about 500°C. Increasing the temperature above 800°C led to the partial oxidation of SiC particles to silica. At higher temperatures (above 1400°C) derived silica reacted with alumina to form mullite, which bonds SiC particles together. The porous SiC specimens were characterized with various techniques. The first part of the project was devoted to investigating the oxidation of SiC particles using a Thermogravimetric analysis (TGA) apparatus. The effects of particle size (micro and nano) and oxidation temperature (910°C--1010°C) as well as the initial mass of SiC particles in TGA on the oxidation behaviour of SiC powders were evaluated. To illustrate the oxidation rate of SiC in the packed bed state, a new kinetic model, which takes into account all of the diffusion steps (bulk, inter and intra particle diffusion) and surface oxidation rate, was proposed. Furthermore, the oxidation of SiC particles was analyzed by the X-ray Diffraction (XRD) technique. The effect of different alumina sources (calcined Al2O 3, alumina sol or a combination of the two) on the mechanical, physical, and crystalline structure of mullite-bonded porous SiC ceramics was studied in the second part of the project. Alumina sol was synthesized by the hydrolysis of Aluminum isopropoxide using the Yoldas method. Alumina sol was homogenous and had a needle-like shape with a thickness of 2--3 nm. Crystalline changes during the heating process of alumina sol were studied using XRD. In addition, Fourier transform infrared (FTIR) spectroscopy was performed to identify the functional groups on the alumina sol surface as a function of temperature. In the third part of the project, the feasibility of the in-situ polymerization technique was investigated to fabricate porous SiC ceramics. In this part, the mixture of SiC and calcined alumina powders were coated by polyethylene via in-situ polymerizing referred to as the polymerization compounding process in a slurry phase. The polymerization was conducted under very moderate operational conditions using the Ziegler-Natta catalyst system. Differential scanning calorimetry (DSC) and TGA analysis and morphological studies (SEM and TEM) revealed the presence of a high density of polyethylene on the surface of SiC and alumina powders. The amount of polymer was controlled by the polymerization reaction time. Most parts of particles were coated by a thin layer of polyethylene and polymer. The porous SiC ceramics, which were fabricated by these treated particles showed higher mechanical and physical properties compared to the samples made without any treatment. The relative intensity of mullite was higher compared to the samples prepared by the traditional process. The effects of the sintering temperature, forming pressure and polymer content were also studied on the physical and mechanical properties of the final product. In the last phase of this research work, the focus of the investigation was to take advantage of both the sol-gel processing and in-situ polymerization method to develop a new process to manufacture mullite-bonded porous SiC ceramic with enhanced mechanical and physical properties. Therefore, first the SiC particles and alumina nano powders were mixed in alumina sol to adjust the alumina weight to 35 wt%. Then, the desired amount of catalyst, which depends on the total surface area of the particles, was grafted onto the surface of the powders under an inert atmosphere. Consequently, the polymerization started from the surface of the substrate. The treated powders were characterized by SEM, XPS and TGA. In addition, the amount of pore-former was determined by TGA analysis. Porous SiC ceramics, which were fabricated by the novel process, consist of mullite, SiC, cristobalite and a small amount of alumina and TiO 2 as a result of reaction of TiCl4 with air. Furthermore, the effect of the sintering temperatures (1500°C, 1550°C and 1600°C) on the crystalline structure of the porous samples was investigated. Furthermore, it was proposed that converting TiCl4 to TiO2 acted as the sintering additive to form mullite at a lower sintering temperature. (Abstract shortened by UMI.).

  14. Differential osteogenic potential of human adipose-derived stem cells co-cultured with human osteoblasts on polymeric microfiber scaffolds.

    PubMed

    Rozila, Ismail; Azari, Pedram; Munirah, Sha'ban; Wan Safwani, Wan Kamarul Zaman; Gan, Seng Neon; Nur Azurah, Abdul Ghani; Jahendran, Jeevanan; Pingguan-Murphy, Belinda; Chua, Kien Hui

    2016-02-01

    The osteogenic potential of human adipose-derived stem cells (HADSCs) co-cultured with human osteoblasts (HOBs) using selected HADSCs/HOBs ratios of 1:1, 2:1, and 1:2, respectively, is evaluated. The HADSCs/HOBs were seeded on electrospun three-dimensional poly[(R)-3-hydroxybutyric acid] (PHB) blended with bovine-derived hydroxyapatite (BHA). Monocultures of HADSCs and HOBs were used as control groups. The effects of PHB-BHA scaffold on cell proliferation and cell morphology were assessed by AlamarBlue assay and field emission scanning electron microscopy. Cell differentiation, cell mineralization, and osteogenic-related gene expression of co-culture HADSCs/HOBs were examined by alkaline phosphatase (ALP) assay, alizarin Red S assay, and quantitative real time PCR, respectively. The results showed that co-culture of HADSCs/HOBs, 1:1 grown into PHB-BHA promoted better cell adhesion, displayed a significant higher cell proliferation, higher production of ALP, extracellular mineralization and osteogenic-related gene expression of run-related transcription factor, bone sialoprotein, osteopontin, and osteocalcin compared to other co-culture groups. This result also suggests that the use of electrospun PHB-BHA in a co-culture HADSCs/HOBs system may serve as promising approach to facilitate osteogenic differentiation activity of HADSCs through direct cell-to-cell contact with HOBs. 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 377-387, 2016. PMID:26414782

  15. The role of hydroxyapatite as solid signal on performance of PCL porous scaffolds for bone tissue regeneration.

    PubMed

    Guarino, Vincenzo; Causa, Filippo; Netti, Paolo A; Ciapetti, Gabriela; Pagani, Stefania; Martini, Desiree; Baldini, Nicola; Ambrosio, Luigi

    2008-08-01

    Highly porous composites made up of biodegradable poly-epsilon-caprolactone (PCL) and stoichiometric hydroxyapatite (HA) particles have been developed as substrate for bone-tissue regeneration. The processing technique consists of phase inversion and particulate (salt crystals) leaching. Three different HA contents (13, 20 and 26 vol %) in PCL-based composite were considered in this study. Pore microstructure with fully interconnected network and pore sizes ranging around a few hundred of mum (macroporosity) was obtained as a result of salt particles removal by leaching process. Several microns (microporosity) porosity was also created through phase inversion of polymer solution. Total porosity up to 95% was achieved. Human marrow stromal cells (MSC) were seeded onto porous PCL-based composites for 1-5 weeks and cultured in osteogenic medium. MSC were able to adhere and grow on PCL-based substrates with a plateau at 3-4 weeks. However, the small effect of bioactive signals on the biological response evaluated in MSC cell culture suggests a prior role of topography on the biological response. Importantly, the presence of HA as a bioactive solid signal determines an increase of mechanical properties. On the overall, the results indicated that porous PCL-based composites are potential candidate for bone substitution with beneficial influence on structural characteristics by solid signal addition. PMID:18335435

  16. 3D porous calcium-alginate scaffolds cell culture system improved human osteoblast cell clusters for cell therapy.

    PubMed

    Chen, Ching-Yun; Ke, Cherng-Jyh; Yen, Ko-Chung; Hsieh, Hui-Chen; Sun, Jui-Sheng; Lin, Feng-Huei

    2015-01-01

    Age-related orthopedic disorders and bone defects have become a critical public health issue, and cell-based therapy is potentially a novel solution for issues surrounding bone tissue engineering and regenerative medicine. Long-term cultures of primary bone cells exhibit phenotypic and functional degeneration; therefore, culturing cells or tissues suitable for clinical use remain a challenge. A platform consisting of human osteoblasts (hOBs), calcium-alginate (Ca-Alginate) scaffolds, and a self-made bioreactor system was established for autologous transplantation of human osteoblast cell clusters. The Ca-Alginate scaffold facilitated the growth and differentiation of human bone cell clusters, and the functionally-closed process bioreactor system supplied the soluble nutrients and osteogenic signals required to maintain the cell viability. This system preserved the proliferative ability of cells and cell viability and up-regulated bone-related gene expression and biological apatite crystals formation. The bone-like tissue generated could be extracted by removal of calcium ions via ethylenediaminetetraacetic acid (EDTA) chelation, and exhibited a size suitable for injection. The described strategy could be used in therapeutic application and opens new avenues for surgical interventions to correct skeletal defects. PMID:25825603

  17. Unexpected and successful "one-step" formation of porous polymeric particles only by mixing organic solvent and water under "low-energy-input" conditions.

    PubMed

    Takami, Taku; Murakami, Yoshihiko

    2014-04-01

    We found that porous particles were unexpectedly obtained in a "one-step" manner only by mixing an organic solvent and water under "low-energy-input" (i.e., low-homogenization-rate) conditions. This phenomenon was attributable to the unexpected formation of the spontaneously formed water-in-oil (w/o) emulsions in the droplets of o/w emulsions. The unexpected formation resulted in the successful formation of water-in-oil-in-water (w/o/w) emulsions instead of o/w emulsions, although the mixed solution containing both an organic solvent and water were simply emulsified in the presence of block copolymers. The present study clarifies the effects of the various preparation conditions on the morphology of unexpected w/o/w emulsions and resulting particles. The porous particles are expected to be suitable drug carriers for pulmonary delivery. The results obtained in the present study show that a newly developed one-step emulsification can be a powerful and facile technique for preparing porous polymeric particles. PMID:24601639

  18. Highly porous Zinc Stannate (Zn2SnO4) nanofibers scaffold photoelectrodes for efficient methyl ammonium halide perovskite solar cells.

    PubMed

    Mali, Sawanta S; Shim, Chang Su; Hong, Chang Kook

    2015-01-01

    Development of ternary metal oxide (TMO) based electron transporting layer (ETL) for perovskite solar cell open a new approaches toward efficient a unique strategy for solid state dye-sensitized solar cells (ssDSSCs). In the present investigation, highly porous zinc tin oxide (Zn2SnO4) scaffold nanofibers has been synthesized by electrospinning technique and successfully used for methyl ammonium lead halide (CH3NH3PbI3) perovskite sensitized solid state solar cells. The fabricated optimized perovskite solar cell devices exhibited 7.38% power conversion efficiency (PCE) with open circuit voltage (VOC) 0.986 V, current density (JSC)?= 12.68 mAcm(-2) and fill factor (FF) 0.59 under AM 1.5 G sunlight (100 mWcm(-2)) which is higher than Zn2SnO4 nanoparticle (? = 2.52%) based perovskite solar cells. This improvement is achieved due to high porosity of Zn2SnO4 nanofibers and high crystallinity of the nanofibers synthesized at 700?C. These results are remarkably higher than reported perovskite solar cells based on such type of ternary metal oxide ETLs. PMID:26094863

  19. Highly porous Zinc Stannate (Zn2SnO4) nanofibers scaffold photoelectrodes for efficient methyl ammonium halide perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Mali, Sawanta S.; Su Shim, Chang; Kook Hong, Chang

    2015-06-01

    Development of ternary metal oxide (TMO) based electron transporting layer (ETL) for perovskite solar cell open a new approaches toward efficient a unique strategy for solid state dye-sensitized solar cells (ssDSSCs). In the present investigation, highly porous zinc tin oxide (Zn2SnO4) scaffold nanofibers has been synthesized by electrospinning technique and successfully used for methyl ammonium lead halide (CH3NH3PbI3) perovskite sensitized solid state solar cells. The fabricated optimized perovskite solar cell devices exhibited 7.38% power conversion efficiency (PCE) with open circuit voltage (VOC) 0.986 V, current density (JSC) = 12.68 mAcm-2 and fill factor (FF) 0.59 under AM 1.5 G sunlight (100 mWcm-2) which is higher than Zn2SnO4 nanoparticle (η = 2.52%) based perovskite solar cells. This improvement is achieved due to high porosity of Zn2SnO4 nanofibers and high crystallinity of the nanofibers synthesized at 700 °C. These results are remarkably higher than reported perovskite solar cells based on such type of ternary metal oxide ETLs.

  20. Highly porous Zinc Stannate (Zn2SnO4) nanofibers scaffold photoelectrodes for efficient methyl ammonium halide perovskite solar cells

    PubMed Central

    Mali, Sawanta S.; Su Shim, Chang; Kook Hong, Chang

    2015-01-01

    Development of ternary metal oxide (TMO) based electron transporting layer (ETL) for perovskite solar cell open a new approaches toward efficient a unique strategy for solid state dye-sensitized solar cells (ssDSSCs). In the present investigation, highly porous zinc tin oxide (Zn2SnO4) scaffold nanofibers has been synthesized by electrospinning technique and successfully used for methyl ammonium lead halide (CH3NH3PbI3) perovskite sensitized solid state solar cells. The fabricated optimized perovskite solar cell devices exhibited 7.38% power conversion efficiency (PCE) with open circuit voltage (VOC) 0.986 V, current density (JSC) = 12.68 mAcm-2 and fill factor (FF) 0.59 under AM 1.5 G sunlight (100 mWcm−2) which is higher than Zn2SnO4 nanoparticle (η = 2.52%) based perovskite solar cells. This improvement is achieved due to high porosity of Zn2SnO4 nanofibers and high crystallinity of the nanofibers synthesized at 700 °C. These results are remarkably higher than reported perovskite solar cells based on such type of ternary metal oxide ETLs. PMID:26094863

  1. Novel bioactive polyester scaffolds prepared from unsaturated resins based on isosorbide and succinic acid.

    PubMed

    Smiga-Matuszowicz, Monika; Janicki, Bartosz; Jaszcz, Katarzyna; ?ukaszczyk, Jan; Kaczmarek, Marcin; Lesiak, Marta; Siero?, Aleksander L; Simka, Wojciech; Mierzwi?ski, Maciej; Kusz, Damian

    2014-12-01

    In this study new biodegradable materials obtained by crosslinking poly(3-allyloxy-1,2-propylene succinate) (PSAGE) with oligo(isosorbide maleate) (OMIS) and small amount of methyl methacrylate were investigated. The porous scaffolds were obtained in the presence of a foaming system consisted of calcium carbonate/carboxylic acid mixture, creating in situ porous structure during crosslinking of liquid formulations. The maximum crosslinking temperature and setting time, the cured porous materials morphology as well as the effect of their porosity on mechanical properties and hydrolytic degradation process were evaluated. It was found that the kind of carboxylic acid used in the foaming system influenced compressive strength and compressive modulus of porous scaffolds. The MTS cytotoxicity assay was carried out for OMIS using hFOB1.19 cell line. OMIS resin was found to be non-toxic in wide range of concentrations. On the ground of scanning electron microscopy (SEM) observations and energy X-ray dispersive analysis (EDX) it was found that hydroxyapatite (HA) formation at the scaffolds surfaces within short period of soaking in phosphate buffer solution occurs. After 3h immersion a compact layer of HA was observed at the surface of the samples. The obtained results suggest potential applicability of resulted new porous crosslinked polymeric materials as temporary bone void fillers. PMID:25491802

  2. Application of an in-situ thermo-polymerized porous polymer: creation of an on-column frit for a packed capillary HPLC column.

    PubMed

    Ma, Jiping; Ding, Mingyu; Xu, Yan; Chen, Lingxin

    2007-03-01

    A 3-mm length of a porous monolithic polymer was prepared in a 0.32-mm inner-diameter fused-silica capillary by an in-situ thermo-polymerization method and used as an on-column frit for a packed capillary HPLC column. The on-column frit can resist high pressure up to 400 bar. A 5-microm packing material was packed in the capillary with the on-column frit by a slurry method. At pressure driving mode, separation of samples was performed using the capillary HPLC column. The in-situ frit preparation method has the advantages of easy preparation, easy control of the location of the frit and a mild preparing reaction condition. PMID:17372384

  3. Bone regeneration in a rabbit critical-sized calvarial model using tyrosine-derived polycarbonate scaffolds.

    PubMed

    Kim, Jinku; Magno, Maria Hanshella R; Waters, Heather; Doll, Bruce A; McBride, Sean; Alvarez, Pedro; Darr, Aniq; Vasanji, Amit; Kohn, Joachim; Hollinger, Jeffrey O

    2012-06-01

    Porous three-dimensional tyrosine-derived polycarbonate (TyrPC) scaffolds with a bimodal pore distribution were fabricated to mimic bone architecture using a combination of salt-leaching and phase separation techniques. TyrPC scaffolds degraded in register with bone regeneration during the 6-week study period and compressive moduli of the scaffolds were maintained >0.5 MPa at 6 weeks of incubation in PBS at 37 °C. The TyrPC scaffolds either unsupplemented or supplemented with recombinant human bone morphogenetic protein-2 (rhBMP-2) were implanted in a rabbit calvarial critical-sized defect (CSD) model and the TyrPC scaffolds treated with rhBMP-2 or TyrPC coated with calcium phosphate scaffold alone promoted bone regeneration in a rabbit calvarial CSD at 6 weeks postimplantation. A synthetic TyrPC polymeric scaffold either without a biological supplement or with a minimal dose of rhBMP-2 induced bone regeneration comparable to a commercially available bone graft substitute in a nonrodent CSD animal model. PMID:22220747

  4. Monolithic porous polymer for on-chip solid-phase extraction and preconcentration prepared by photoinitiated in situ polymerization within a microfluidic device.

    PubMed

    Yu, C; Davey, M H; Svec, F; Frchet, J M

    2001-11-01

    Monolithic porous polymers have been prepared by photoinitiated polymerization within the channels of a microfluidic device and used for on-chip solid-phase extraction and preconcentration. The preparation of the monolithic material with hydrophobic and ionizable surface chemistries is easily achieved by copolymerization of butyl methacrylate with ethylene dimethacrylate, or 2-hydroxyethyl methacrylate and [2-(methacryloyloxy)ethyl]trimethylammonium chloride with ethylene dimethacrylate, respectively. The porous properties, and consequently the flow resistance, of the monolithic device are controlled by the use of a mixture of hexane and methanol as a porogenic mixture. This mixture was designed to meet the specific requirements for pore formation within macroporous monoliths useful in the microfluidic formats. The low flow resistance enables high flow rates of up to 10 microL/min, which corresponds to a linear flow velocity of 50 mm/s and far exceeds the flow velocities typical of the common analytical microchips. The function of the monolithic concentration device was first demonstrated using very dilute solutions of Coumarin 519. The performance in a more realistic application was then demonstrated with the enrichment of a hydrophobic tetrapeptide and also of green fluorescent protein for which an increase in concentration by a factor as high as 10(3) was achieved. PMID:11721904

  5. Fabrication and characterization of three-dimensional poly(ether- ether- ketone)/-hydroxyapatite biocomposite scaffolds using laser sintering.

    PubMed

    Tan, K H; Chua, C K; Leong, K F; Naing, M W; Cheah, C M

    2005-05-01

    The ability to have precise control over porosity, scaffold shape, and internal pore architecture is critical in tissue engineering. For anchorage-dependent cells, the presence of three-dimensional scaffolds with interconnected pore networks is crucial to aid in the proliferation and reorganization of cells. This research explored the potential of rapid prototyping techniques such as selective laser sintering to fabricate solvent-free porous composite polymeric scaffolds comprising of different blends of poly(ether-ether-ketone) (PEEK) and hydroxyapatite (HA). The architecture of the scaffolds was created with a scaffold library of cellular units and a corresponding algorithm to generate the structure. Test specimens were produced and characterized by varying the weight percentage, starting with 10 wt% HA to 40 wt% HA, of physically mixed PEEK-HA powder blends. Characterization analyses including porosity, microstructure, composition of the scaffolds, bioactivity, and in vitro cell viability of the scaffolds were conducted. The results obtained showed a promising approach in fabricating scaffolds which can produce controlled microarchitecture and higher consistency. PMID:15934394

  6. A biodegradable polymeric system for peptide–protein delivery assembled with porous microspheres and nanoparticles, using an adsorption/infiltration process

    PubMed Central

    Alcalá-Alcalá, Sergio; Urbán-Morlán, Zaida; Aguilar-Rosas, Irene; Quintanar-Guerrero, David

    2013-01-01

    A biodegradable polymeric system is proposed for formulating peptides and proteins. The systems were assembled through the adsorption of biodegradable polymeric nanoparticles onto porous, biodegradable microspheres by an adsorption/infiltration process with the use of an immersion method. The peptide drug is not involved in the manufacturing of the nanoparticles or in obtaining the microspheres; thus, contact with the organic solvent, interfaces, and shear forces required for the process are prevented during drug loading. Leuprolide acetate was used as the model peptide, and poly(d,l-lactide-co-glycolide) (PLGA) was used as the biodegradable polymer. Leuprolide was adsorbed onto different amounts of PLGA nanoparticles (25 mg/mL, 50 mg/mL, 75 mg/mL, and 100 mg/mL) in a first stage; then, these were infiltrated into porous PLGA microspheres (100 mg) by dipping the structures into a microsphere suspension. In this way, the leuprolide was adsorbed onto both surfaces (ie, nanoparticles and microspheres). Scanning electron microscopy studies revealed the formation of a nanoparticle film on the porous microsphere surface that becomes more continuous as the amount of infiltrated nanoparticles increases. The adsorption efficiency and release rate are dependent on the amount of adsorbed nanoparticles. As expected, a greater adsorption efficiency (~95%) and a slower release rate were seen (~20% of released leuprolide in 12 hours) when a larger amount of nanoparticles was adsorbed (100 mg/mL of nanoparticles). Leuprolide acetate begins to be released immediately when there are no infiltrated nanoparticles, and 90% of the peptide is released in the first 12 hours. In contrast, the systems assembled in this study released less than 44% of the loaded drug during the same period of time. The observed release profiles denoted a Fickian diffusion that fit Higuchi’s model (t1/2). The manufacturing process presented here may be useful as a potential alternative for formulating injectable depots for sensitive hydrophilic drugs such as peptides and proteins, among others. PMID:23788833

  7. Evaluation of polyelectrolyte complex-based scaffolds for mesenchymal stem cell therapy in cardiac ischemia treatment.

    PubMed

    Ceccaldi, Caroline; Bushkalova, Raya; Alfarano, Chiara; Lairez, Olivier; Calise, Denis; Bourin, Philippe; Frugier, Celine; Rouzaud-Laborde, Charlotte; Cussac, Daniel; Parini, Angelo; Sallerin, Brigitte; Fullana, Sophie Girod

    2014-02-01

    Three-dimensional (3D) scaffolds hold great potential for stem cell-based therapies. Indeed, recent results have shown that biomimetic scaffolds may enhance cell survival and promote an increase in the concentration of therapeutic cells at the injury site. The aim of this work was to engineer an original polymeric scaffold based on the respective beneficial effects of alginate and chitosan. Formulations were made from various alginate/chitosan ratios to form opposite-charge polyelectrolyte complexes (PECs). After freeze-drying, the resultant matrices presented a highly interconnected porous microstructure and mechanical properties suitable for cell culture. In vitro evaluation demonstrated their compatibility with mesenchymal stell cell (MSC) proliferation and their ability to maintain paracrine activity. Finally, the in vivo performance of seeded 3D PEC scaffolds with a polymeric ratio of 40/60 was evaluated after an acute myocardial infarction provoked in a rat model. Evaluation of cardiac function showed a significant increase in the ejection fraction, improved neovascularization, attenuated fibrosis as well as less left ventricular dilatation as compared to an animal control group. These results provide evidence that 3D PEC scaffolds prepared from alginate and chitosan offer an efficient environment for 3D culturing of MSCs and represent an innovative solution for tissue engineering. PMID:24211733

  8. Translating textiles to tissue engineering: Creation and evaluation of microporous, biocompatible, degradable scaffolds using industry relevant manufacturing approaches and human adipose derived stem cells.

    PubMed

    Haslauer, Carla M; Avery, Matthew R; Pourdeyhimi, Behnam; Loboa, Elizabeth G

    2015-07-01

    Polymeric scaffolds have emerged as a means of generating three-dimensional tissues, such as for the treatment of bone injuries and nonunions. In this study, a fibrous scaffold was designed using the biocompatible, degradable polymer poly-lactic acid in combination with a water dispersible sacrificial polymer, EastONE. Fibers were generated via industry relevant, facile scale-up melt-spinning techniques with an islands-in-the-sea geometry. Following removal of EastONE, a highly porous fiber remained possessing 12 longitudinal channels and pores throughout all internal and external fiber walls. Weight loss and surface area characterization confirmed the generation of highly porous fibers as observed via focused ion beam/scanning electron microscopy. Porous fibers were then knit into a three-dimensional scaffold and seeded with human adipose-derived stem cells (hASC). Confocal microscopy images confirmed hASC attachment to the fiber walls and proliferation throughout the knit structure. Quantification of cell-mediated calcium accretion following culture in osteogenic differentiation medium confirmed hASC differentiation throughout the porous constructs. These results suggest incorporation of a sacrificial polymer within islands-in-the-sea fibers generates a highly porous scaffold capable of supporting stem cell viability and differentiation with the potential to generate large three-dimensional constructs for bone regeneration and/or other tissue engineering applications. PMID:25229198

  9. Effect of calcium phosphate coating and rhBMP-2 on bone regeneration in rabbit calvaria using poly(propylene fumarate) scaffolds.

    PubMed

    Dadsetan, Mahrokh; Guda, Teja; Runge, M Brett; Mijares, Dindo; LeGeros, Racquel Z; LeGeros, John P; Silliman, David T; Lu, Lichun; Wenke, Joseph C; Brown Baer, Pamela R; Yaszemski, Michael J

    2015-05-01

    Various calcium phosphate based coatings have been evaluated for better bony integration of metallic implants and are currently being investigated to improve the surface bioactivity of polymeric scaffolds. The aim of this study was to evaluate the role of calcium phosphate coating and simultaneous delivery of recombinant human bone morphogenetic protein-2 (rhBMP-2) on the in vivo bone regeneration capacity of biodegradable, porous poly(propylene fumarate) (PPF) scaffolds. PPF scaffolds were coated with three different calcium phosphate formulations: magnesium-substituted ?-tricalcium phosphate (?-TCMP), carbonated hydroxyapatite (synthetic bone mineral, SBM) and biphasic calcium phosphate (BCP). In vivo bone regeneration was evaluated by implantation of scaffolds in a critical-sized rabbit calvarial defect loaded with different doses of rhBMP-2. Our data demonstrated that scaffolds with each of the calcium phosphate coatings were capable of sustaining rhBMP-2 release and retained an open porous structure. After 6weeks of implantation, micro-computed tomography revealed that the rhBMP-2 dose had a significant effect on bone formation within the scaffolds and that the SBM-coated scaffolds regenerated significantly greater bone than BCP-coated scaffolds. Mechanical testing of the defects also indicated restoration of strength in the SBM and ?-TCMP with rhBMP-2 delivery. Histology results demonstrated bone growth immediately adjacent to the scaffold surface, indicating good osteointegration and osteoconductivity for coated scaffolds. The results obtained in this study suggest that the coated scaffold platform demonstrated a synergistic effect between calcium phosphate coatings and rhBMP-2 delivery and may provide a promising platform for the functional restoration of large bone defects. PMID:25575855

  10. An Open Source Image Processing Method to Quantitatively Assess Tissue Growth after Non-Invasive Magnetic Resonance Imaging in Human Bone Marrow Stromal Cell Seeded 3D Polymeric Scaffolds

    PubMed Central

    Leferink, Anne M.; Fratila, Raluca M.; Koenrades, Maaike A.; van Blitterswijk, Clemens A.; Velders, Aldrik; Moroni, Lorenzo

    2014-01-01

    Monitoring extracellular matrix (ECM) components is one of the key methods used to determine tissue quality in three-dimensional (3D) scaffolds for regenerative medicine and clinical purposes. This is even more important when multipotent human bone marrow stromal cells (hMSCs) are used, as it could offer a method to understand in real time the dynamics of stromal cell differentiation and eventually steer it into the desired lineage. Magnetic Resonance Imaging (MRI) is a promising tool to overcome the challenge of a limited transparency in opaque 3D scaffolds. Technical limitations of MRI involve non-uniform background intensity leading to fluctuating background signals and therewith complicating quantifications on the retrieved images. We present a post-imaging processing sequence that is able to correct for this non-uniform background intensity. To test the processing sequence we investigated the use of MRI for in vitro monitoring of tissue growth in three-dimensional poly(ethylene oxide terephthalate)poly(butylene terephthalate) (PEOT/PBT) scaffolds. Results showed that MRI, without the need to use contrast agents, is a promising non-invasive tool to quantitatively monitor ECM production and cell distribution during in vitro culture in 3D porous tissue engineered constructs. PMID:25502022

  11. An open source image processing method to quantitatively assess tissue growth after non-invasive magnetic resonance imaging in human bone marrow stromal cell seeded 3D polymeric scaffolds.

    PubMed

    Leferink, Anne M; Fratila, Raluca M; Koenrades, Maaike A; van Blitterswijk, Clemens A; Velders, Aldrik; Moroni, Lorenzo

    2014-01-01

    Monitoring extracellular matrix (ECM) components is one of the key methods used to determine tissue quality in three-dimensional (3D) scaffolds for regenerative medicine and clinical purposes. This is even more important when multipotent human bone marrow stromal cells (hMSCs) are used, as it could offer a method to understand in real time the dynamics of stromal cell differentiation and eventually steer it into the desired lineage. Magnetic Resonance Imaging (MRI) is a promising tool to overcome the challenge of a limited transparency in opaque 3D scaffolds. Technical limitations of MRI involve non-uniform background intensity leading to fluctuating background signals and therewith complicating quantifications on the retrieved images. We present a post-imaging processing sequence that is able to correct for this non-uniform background intensity. To test the processing sequence we investigated the use of MRI for in vitro monitoring of tissue growth in three-dimensional poly(ethylene oxide terephthalate)-poly(butylene terephthalate) (PEOT/PBT) scaffolds. Results showed that MRI, without the need to use contrast agents, is a promising non-invasive tool to quantitatively monitor ECM production and cell distribution during in vitro culture in 3D porous tissue engineered constructs. PMID:25502022

  12. Osteogenesis and angiogenesis induced by porous ?-CaSiO(3)/PDLGA composite scaffold via activation of AMPK/ERK1/2 and PI3K/Akt pathways.

    PubMed

    Wang, Chen; Lin, Kaili; Chang, Jiang; Sun, Jiao

    2013-01-01

    As a potential bioactive material, ?-calcium silicate (?-CS) has attracted particular attention in the field of bone regeneration. In this study, porous ?-CS/Poly-D,L-Lactide-Glycolide (PDLGA) composite scaffolds were developed with the goals of controlling the degradation rate and improving the mechanical and biological properties. The compressive strength and toughness were significantly enhanced by PDLGA modification of porous ?-CS ceramic scaffolds. The effects of the ionic extract from ?-CS/PDLGA composite scaffolds on osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (rBMSCs), proliferation of human umbilical vein endothelial cells (HUVECs) and the related mechanisms were investigated. It was shown that bioactive ions from ?-CS/PDLGA scaffolds could enhance cell viability, alkaline phosphatase (ALP) activity, calcium mineral deposition, and mRNA expression levels of osteoblast-related genes of rBMSCs without addition of extra osteogenic reagents. The activation in AMP-activated protein kinase (AMPK), extracellular signal-related kinases (ERK) 1/2 and RUNX-2 were observed in rBMSCs cultured in the extract of ?-CS/PDLGA, and these effects could be blocked by AMPK inhibitor Compound C. The extracts of ?-CS/PDLGA composites stimulated HUVECs proliferation that was associated with phosphorylation of protein kinase B (Akt) and endothelial nitric oxide synthase (eNOS) as well as an increase in nitric oxide (NO) production and secretion of vascular endothelial growth factor (VEGF). The inductions were abolished by the addition of phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. The composite scaffolds were implanted in critical sized rabbit femur defects (6 10 mm) for 4, 12 and 20 weeks with ?-tricalcium phosphate (?-TCP) as controls. Sequential histological evaluations and radiographs revealed that ?-CS/PDLGA dramatically stimulated new bone formation and angiogenesis. The biodegradation rate of the ?-CS/PDLGA scaffolds was lower than that of ?-TCP at each time point examined, and matched the new bone formation rates. These data suggest that ?-CS/PDLGA could promote bone regeneration in vivo, which might be ascribed to the enhanced osteogenic differentiation of mesenchymal stem cells (MSCs) and increased angiogenic activity of endothelial cells (ECs). PMID:23069715

  13. Enhanced survival and function of islet-like clusters differentiated from adipose stem cells on a three-dimensional natural polymeric scaffold: an in vitro study.

    PubMed

    Aloysious, Neena; Nair, Prabha D

    2014-05-01

    Autologous adipose stem cells owing to its pluripotent nature offer a valuable source for pancreatic beta cell replacement in the treatment of diabetes mellitus. However, maintaining longevity and functionality of stem cell-derived islet-like cells for long-term in vitro culture is challenging. Signaling interaction between islets and surrounding extracellular matrix (ECM) is an important factor for islet survival and function. Tissue engineering strategy to use scaffolds as substitute for ECM is a key to the problem. In the present study, we fabricated a three-dimensional (3D) biodegradable scaffold comprised of natural polymers dextran and gelatin (DEXGEL) for differentiation of adipose stem cells to islet-like clusters (ILCs). Adipose stem cells derived from subcutaneous fat of New Zealand white rabbits were differentiated to ILCs on DEXGEL scaffold and two-dimensional (2D) culture plates via three stage protocol using cocktail of growth factors. The ILCs differentiated on DEXGEL scaffold exhibited characteristic islet morphology, and expressed islet-specific hormones (insulin, glucagon, and somatostatin). The insulin secretion in response to glucose challenge and viability of ILCs on DEXGEL scaffold were significantly higher in comparison to ILCs on 2D culture. Our results demonstrated for the first time that DEXGEL scaffold simulated an extracellular environment for effective differentiation of rabbit adipose stem cells to ILCs. PMID:24359126

  14. Surface modification of strontium-doped porous bioactive ceramic scaffolds via poly(DOPA) coating and immobilizing silk fibroin for excellent angiogenic and osteogenic properties.

    PubMed

    Wang, Xu; Gu, Zhipeng; Jiang, Bo; Li, Li; Yu, Xixun

    2016-04-22

    For bioceramic scaffolds employed in clinical applications, excellent bioactivity and tenacity were of great importance. Modifying inorganic SCPP scaffolds with biological macromolecules could obviously improve its bioactivity and eliminate its palpable brittleness. However, it was hard to execute directly due to extremely bad interfacial compatibility between them. In this research, dopamine (DOPA) was introduced onto strontium-doped calcium polyphosphate (SCPP) scaffolds, subsequently the preliminary material was successfully further modified by silk fibroin (SF). SCPP/D/SF possessed suitable biomechanical properties, ability to stimulate angiogenic factor secretion and excellent biocompatibility. Biomechanical examination demonstrated that SCPP/D/SF scaffolds yielded better compressive strength because of improved interfacial compatibility. MTT assay and CLSM observation showed that SCPP/D/SF scaffolds had good cytocompatibility and presented better inducing-cell-migration potential than pure SCPP scaffolds. Meanwhile, its ability to stimulate angiogenic factor secretion was measured through the ELISA assay and immunohistological analysis in vitro and in vivo respectively. The results revealed, superior to SCPP, SCPP/D/SF could effectively promote VEGF and bFGF expression, possibly leading to enhancing angiogenesis and osteogenesis. In a word, SCPP/D/SF could serve as a potential bone tissue engineering scaffold for comparable biomechanical properties and excellent bioactivity. It provided a novel idea for modification of inorganic materials to prepare promising bone tissue engineering scaffolds with the ability to accelerate bone regeneration and vascularization. PMID:26870855

  15. High-precision flexible fabrication of tissue engineering scaffolds using distinct polymers

    SciTech Connect

    Wei, Chuang; Cai, Lei; Sonawane, Bhushan; Wang, Shanfeng; Dong, Jingyan

    2012-01-01

    Three-dimensional porous structures using biodegradable materials with excellent biocompatibility are critically important for tissue engineering applications. We present a multi-nozzle-based versatile deposition approach to flexibly construct porous tissue engineering scaffolds using distinct polymeric biomaterials such as thermoplastic and photo-crosslinkable polymers. We first describe the development of the deposition system and fabrication of scaffolds from two types of biodegradable polymers using this system. The thermoplastic sample is semi-crystalline poly({var_epsilon}-caprolactone) (PCL) that can be processed at a temperature higher than its melting point and solidifies at room temperature. The photo-crosslinkable one is polypropylene fumarate (PPF) that has to be dissolved in a reactive solvent as a resin for being cured into solid structures. Besides the direct fabrication of thermoplastic PCL scaffolds, we specifically develop a layer molding approach for the fabrication of crosslinkable polymers, which traditionally can only be fabricated by stereolithography. In this approach, a thermoplastic supporting material (paraffin wax) is first deposited to make a mold for each specific layer, and then PPF is deposited on demand to fill the mold and cured by the UV light. The supporting material can be removed to produce a porous scaffold of crosslinked PPF. Both PCL and crosslinked PPF scaffolds fabricated using the developed system have been characterized in terms of compressive mechanical properties, morphology, pore size and porosity. Mouse MC3T3-E1 pre-osteoblastic cell studies on the fabricated scaffolds have been performed to demonstrate their capability of supporting cell proliferation and ingrowth, aiming for bone tissue engineering applications.

  16. High-precision flexible fabrication of tissue engineering scaffolds using distinct polymers.

    PubMed

    Wei, Chuang; Cai, Lei; Sonawane, Bhushan; Wang, Shanfeng; Dong, Jingyan

    2012-05-25

    Three-dimensional porous structures using biodegradable materials with excellent biocompatibility are critically important for tissue engineering applications. We present a multi-nozzle-based versatile deposition approach to flexibly construct porous tissue engineering scaffolds using distinct polymeric biomaterials such as thermoplastic and photo-crosslinkable polymers. We first describe the development of the deposition system and fabrication of scaffolds from two types of biodegradable polymers using this system. The thermoplastic sample is semi-crystalline poly(?-caprolactone) (PCL) that can be processed at a temperature higher than its melting point and solidifies at room temperature. The photo-crosslinkable one is polypropylene fumarate (PPF) that has to be dissolved in a reactive solvent as a resin for being cured into solid structures. Besides the direct fabrication of thermoplastic PCL scaffolds, we specifically develop a layer molding approach for the fabrication of crosslinkable polymers, which traditionally can only be fabricated by stereolithography. In this approach, a thermoplastic supporting material (paraffin wax) is first deposited to make a mold for each specific layer, and then PPF is deposited on demand to fill the mold and cured by the UV light. The supporting material can be removed to produce a porous scaffold of crosslinked PPF. Both PCL and crosslinked PPF scaffolds fabricated using the developed system have been characterized in terms of compressive mechanical properties, morphology, pore size and porosity. Mouse MC3T3-E1 pre-osteoblastic cell studies on the fabricated scaffolds have been performed to demonstrate their capability of supporting cell proliferation and ingrowth, aiming for bone tissue engineering applications. PMID:22635324

  17. Dynamic compression combined with SOX-9 overexpression in rabbit adipose-derived mesenchymal stem cells cultured in a three-dimensional gradual porous PLGA composite scaffold upregulates HIF-1? expression.

    PubMed

    Chen, Xu; Li, Jianjun; Wang, Enbo; Zhao, Qun; Kong, Zhan; Yuan, Xiangnan

    2015-12-01

    There is considerable interest in how the fate of adipose-derived stem cells is determined. Physical stimuli play a crucial role in skeletogenesis and in cartilage repair and regeneration. In the present study, we investigated the comparative and interactive effects of dynamic compression and SRY-related high-mobility group box gene-9 (SOX-9) on chondrogenesis of rabbit adipose-derived stem cells in three-dimensional gradual porous PLGA (polylactic-co-glycolic acid) composite scaffolds. Articular cartilage is stratified into zones delineated by characteristic changes in cellular, matrix, and nutritive components. As a consequence, biochemical and biomechanical properties vary greatly between the different zones, giving the tissue its unique structure and, thus, the ability to cope with extreme loading. The effects on development of the cartilage were examined using a combination of computational modeling to predict alterations in biophysical stimuli, detailed morphometric analysis of 3D digital representations. In addition, early chondrogenic differentiation was assessed via real-time PCR of mRNA expression levels for bone- and cartilage-specific gene markers. Our findings define the important role of dynamic compression combined with SOX-9 overexpression during in vitro generation of tissue-engineering cartilage and suggest that a 3D gradual porous PLGA composite scaffold may benefit articular cartilage tissue engineering in cartilage regeneration for better force distribution. 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 3886-3895, 2015. PMID:26123537

  18. Fabrication of a multi-layer three-dimensional scaffold with controlled porous micro-architecture for application in small intestine tissue engineering

    PubMed Central

    Knight, Toyin; Basu, Joydeep; Rivera, Elias A.; Spencer, Thomas; Jain, Deepak; Payne, Richard

    2013-01-01

    Various methods can be employed to fabricate scaffolds with characteristics that promote cell-to-material interaction. This report examines the use of a novel technique combining compression molding with particulate leaching to create a unique multi-layered scaffold with differential porosities and pore sizes that provides a high level of control to influence cell behavior. These cell behavioral responses were primarily characterized by bridging and penetration of two cell types (epithelial and smooth muscle cells) on the scaffold in vitro. Larger pore sizes corresponded to an increase in pore penetration, and a decrease in pore bridging. In addition, smaller cells (epithelial) penetrated further into the scaffold than larger cells (smooth muscle cells). In vivo evaluation of a multi-layered scaffold was well tolerated for 75 d in a rodent model. This data shows the ability of the components of multi-layered scaffolds to influence cell behavior, and demonstrates the potential for these scaffolds to promote desired tissue outcomes in vivo. PMID:23563499

  19. 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. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 195-208, 2016. PMID:26282063

  20. Three-dimensional cellular distribution in polymeric scaffolds for bone regeneration: a microCT analysis compared to SEM, CLSM and DNA content.

    PubMed

    Parrilli, A; Pagani, S; Maltarello, M C; Santi, S; Salerno, A; Netti, P A; Giardino, R; Rimondini, L; Fini, M

    2014-07-01

    In orthopaedic surgery the tissues damaged by injury or disease could be replaced using constructs based on biocompatible materials, cells and growth factors. Scaffold design, porosity and early colonization are key components for the implant success. From biological point of view, attention may be also given to the number, type and size of seeded cells, as well as the seeding technique and cell morphological and volumetric alterations. This paper describes the use of the microCT approach (to date used principally for mineralized matrix quantification) to observe construct colonization in terms of cell localization, and make a direct comparison of the microtomographic sections with scanning electron microscopy images and confocal laser scanning microscope analysis. Briefly, polycaprolactone scaffolds were seeded at different cell densities with MG63 osteoblastic-like cells. Two different endpoints, 1 and 2 weeks, were selected for the three-dimensional colonization and proliferation analysis of the cells. By observing all images obtained, in addition to a more extensive distribution of cells on scaffolds surfaces than in the deeper layers, cell volume increased at 2 weeks compared to 1 week after seeding. Combining the cell number quantification by deoxyribonucleic acid analysis and the single cell volume changes by confocal laser scanning microscope, we validated the microCT segmentation method by finding no statistical differences in the evaluation of the cell volume fraction of the scaffold. Furthermore, the morphological results of this study suggest that an effective scaffold colonization requires a precise balance between different factors, such as number, type and size of seeded cells in addition to scaffold porosity. PMID:24802370

  1. Use of Micro-Computed Tomography to Nondestructively Characterize Biomineral Coatings on Solid Freeform Fabricated Poly (L-Lactic Acid) and Poly (ɛ-Caprolactone) Scaffolds In Vitro and In Vivo

    PubMed Central

    Saito, Eiji; Suarez-Gonzalez, Darilis; Rao, Rameshwar R.; Stegemann, Jan P.; Murphy, William L.

    2013-01-01

    Biomineral coatings have been extensively used to enhance the osteoconductivity of polymeric scaffolds. Numerous porous scaffolds have previously been coated with a bone-like apatite mineral through incubation in simulated body fluid (SBF). However, characterization of the mineral layer formed on scaffolds, including the amount of mineral within the scaffolds, often requires destructive methods. We have developed a method using micro-computed tomography (μ-CT) scanning to nondestructively quantify the amount of mineral in vitro and in vivo on biodegradable scaffolds made of poly (L-lactic acid) (PLLA) and poly (ɛ-caprolactone) (PCL). PLLA and PCL scaffolds were fabricated using an indirect solid freeform fabrication (SFF) technique to achieve orthogonally interconnected pore architectures. Biomineral coatings were formed on the fabricated PLLA and PCL scaffolds after incubation in modified SBF (mSBF). Scanning electron microscopy and X-ray diffraction confirmed the formation of an apatite-like mineral. The scaffolds were implanted into mouse ectopic sites for 3 and 10 weeks. The presence of a biomineral coating within the porous scaffolds was confirmed through plastic embedding and μ-CT techniques. Tissue mineral content (TMC) and volume of mineral on the scaffold surfaces detected by μ-CT had a strong correlation with the amount of calcium measured by the orthocresolphthalein complex-one (OCPC) method before and after implantation. There was a strong correlation between OCPC pre- and postimplantation and μ-CT measured TMC (R2=0.96 preimplant; R2=0.90 postimplant) and mineral volume (R2=0.96 preimplant; R2=0.89 postimplant). The μ-CT technique showed increases in mineral following implantation, suggesting that μ-CT can be used to nondestructively determine the amount of calcium on coated scaffolds. PMID:23134479

  2. Degradable glycine-based photo-polymerizable polyphosphazenes for use as scaffolds for tissue regeneration.

    PubMed

    Rothemund, Sandra; Aigner, Tamara B; Iturmendi, Aitziber; Rigau, Maria; Husár, Branislav; Hildner, Florian; Oberbauer, Eleni; Prambauer, Martina; Olawale, Gbenga; Forstner, Reinhard; Liska, Robert; Schröder, Klaus R; Brüggemann, Oliver; Teasdale, Ian

    2015-03-01

    Photo-polymerizable scaffolds are designed and prepared via short chain poly(organo)phosphazene building blocks bearing glycine allylester moieties. The polyphosphazene was combined with a trifunctional thiol and divinylester in various ratios, followed by thiol-ene photo-polymerization to obtain porous matrices. Degradation studies under aqueous conditions showed increasing rates in correlation with the polyphosphazene content. Preliminary cell studies show the non-cytotoxic nature of the polymers and their degradation products, as well as the cell adhesion and proliferation of adipose-derived stem cells. PMID:25355036

  3. Nano/microfibrous polymeric constructs loaded with bioactive agents and designed for tissue engineering applications: a review.

    PubMed

    Puppi, Dario; Zhang, Xuanmiao; Yang, Likai; Chiellini, Federica; Sun, Xun; Chiellini, Emo

    2014-10-01

    Nano/microfibrous polymeric constructs present various inherent advantages, such as highly porous architecture and high surface to volume ratio, making them attractive for tissue engineering purposes. Electrospinning is the most preferred technique for the fabrication of polymeric nanofibrous assemblies that can mimic the physical functions of native extracellular matrix greatly favoring cells attachment and thus influencing their morphology and activities. Different approaches have been developed to apply polymeric microfiber fabrication techniques (e.g. wet-spinning) for the obtainment of scaffolds with a three-dimensional network of micropores suitable for effective cells migration. Progress in additive manufacturing technology has led to the development of complex scaffold's shapes and microfibrous structures with a high degree of automation, good accuracy and reproducibility. Various loading methods, such as direct blending, coaxial electrospinning and microparticles incorporation, are enabling to develop customized strategies for the biofunctionalization of nano/microfibrous scaffolds with a tailored kinetics of release of different bioactive agents, ranging from small molecules, such as antibiotics, to protein drugs, such as growth factors, and even cells. Recent activities on the combination of different processing techniques and loading methods for the obtainment of biofunctionalized polymeric constructs with a complex multiscale structure open new possibilities for the development of biomimetic scaffolds endowed with a hierarchical architecture and a sophisticated release kinetics of different bioactive agents. This review is aimed at summarizing current advances in technologies and methods for manufacturing nano/microfibrous polymeric constructs suitable as tissue engineering scaffolds, and for their combination with different bioactive agents to promote tissue regeneration and therapeutic effects. PMID:24678016

  4. A Bi-Layered Elastomeric Scaffold for Tissue Engineering of Small-Diameter Vascular Grafts

    PubMed Central

    Soletti, Lorenzo; Hong, Yi; Guan, Jianjun; Stankus, John J.; El-Kurdi, Mohammed S.; Wagner, William R.; Vorp, David A.

    2011-01-01

    A major barrier in the development of a clinically-useful small-diameter tissue engineered vascular graft (TEVG) is the scaffold component. Scaffold requirements include matching the mechanical and structural properties with those of native vessels and optimizing the microenvironment to foster cell integration, adhesion, and growth. We have developed a small-diameter, bi-layered, biodegradable, elastomeric scaffold based on a synthetic, biodegradable elastomer. The scaffold incorporates a highly porous inner layer, allowing cell integration and growth, and an external, fibrous reinforcing layer deposited by electrospinning. Scaffold morphology and mechanical properties were assessed, quantified, and compared to those of native vessels. Scaffolds were then seeded with adult stem cells via a rotational vacuum seeding device to obtain a TEVG, cultured in dynamic conditions for 7 days, and evaluated for cellularity. The scaffold showed a firm integration of the two polymeric layers with no delaminations. Mechanical properties were physiologically-consistent showing anisotropy, elastic modulus (1.40.4 MPa), and ultimate tensile stress (8.31.7 MPa) comparable with native vessels. Compliance and suture retention force were 4.60.510?4 mmHg?1 and 3.40.3 N, respectively. Seeding resulted in a rapid, uniform, bulk integration of cells, with a seeding efficiency of 921%. The scaffolds maintained a high level of cellular density throughout dynamic culture. This approach, combining artery-like mechanical properties and a rapid and efficient cellularization, might contribute to the future clinical translation of TEVGs. PMID:19540370

  5. Polymeric nanoporous materials fabricated with supercritical CO2 and CO2-expanded liquids.

    PubMed

    Zhang, Aijuan; Zhang, Qingkun; Bai, Hua; Li, Lei; Li, Jun

    2014-01-01

    Both academia and industries have put great efforts into developing non-destructive technologies for the fabrication of polymeric nanoporous materials. Such non-destructive technologies developed with supercritical CO2 (scCO2) and CO2-expanded liquids (CXLs) have been attracting more and more attention because they have been demonstrated to be green and effective media for porous polymer preparation and processing. In this tutorial review, we present several such new technologies with scCO2 and CXLs, which have the capacity to prepare polymeric nanoporous materials with unique morphologies. The fabricated nanoporous polymers have significantly improved the performance of polymeric monoliths and films, and have found wide applications as templates, antireflection coatings, low-k materials, tissue engineering scaffolds and filtration membranes. This tutorial review also introduces the associated characterization methods, including the imaging, scattering and physisorption techniques. PMID:25032751

  6. Monodisperse porous poly(vinyl acetate-co-divinylbenzene) particles by single-stage seeded polymerization: a packing material for reversed phase HPLC.

    PubMed

    Caglayan, Berna; Unsal, Ender; Camli, S Tolga; Tuncel, Murvet; Tuncel, Ali

    2006-05-01

    A single-stage swelling and polymerization method was proposed for the synthesis of monodisperse porous poly(vinyl acetate-co-divinylbenzene) [poly(VAc-co-DVB)] particles with different VAc/DVB feed ratios. The particles obtained with the VAc/DVB feed ratio of 50:50 v/v had a narrow pore size distribution exhibiting a sharp peak at 30 nm. Based on this distribution the mean pore size and the specific volume were determined as 12 nm and 1.39 mL/g, respectively. The specific surface area of poly(VAc-co-DVB) particles was found to be 470 m2/g. These properties make poly(VAc-co-DVB) particles a promising support for potential HPLC applications. Poly(vinyl alcohol-co-divinylbenzene) [poly(VA-co-DVB)] particles were then obtained by the basic hydrolysis of poly(VAc-co-DVB) particles. The hydroxyl groups on poly(VA-co-DVB) particles have a suitably reactive functionality for surface grafting or derivatization protocols aiming at synthesizing various HPLC packings. The examination of poly(VA-co-DVB) particles by confocal laser scanning microscopy showed the homogeneous distribution of hydroxyl functionality in the particle interior. As a starting point, the chromatographic performance of plain material, poly(VAc-co-DVB) particles produced with VAc/DVB feed ratio of 50:50 (v/v) was tested by a commonly utilized chromatographic mode, reversed phase chromatography. Poly(VAc-co-DVB) particles were successfully used as packing material in the RP separation of alkylbenzenes with resolutions higher than 1.5. Theoretical plate numbers up to 17 500 plates/m were achieved. No significant change both in the chromatographic resolution and column efficiency was observed with increasing flow rate. The chromatography showed that poly(VAc-co-DVB) particles were a suitable starting material for the synthesis of chromatographic packings for different modes of HPLC. PMID:16833225

  7. Growth factors delivery from hybrid PCL-starch scaffolds processed using supercritical fluid technology.

    PubMed

    Diaz-Gomez, Luis; Concheiro, Angel; Alvarez-Lorenzo, Carmen; García-González, Carlos A

    2016-05-20

    Synthetic polymeric scaffolds to be used as surrogates of autologous bone grafts should not only have suitable physicochemical and mechanical properties, but also contain bioactive agents such as growth factors (GFs) to facilitate the tissue growth. For this purpose, cost-effective and autologous GFs sources are preferred to avoid some post-surgery complications after implantation, like immunogenicity or disease transmission, and the scaffolds should be processed using methods able to preserve GFs activity. In this work, poly(ɛ-caprolactone) (PCL) scaffolds incorporating GFs were processed using a green foaming process based on supercritical fluid technology. Preparation rich in growth factors (PRGF), a natural and highly available cocktail of GFs obtained from platelet rich plasma (PRP), was used as GF source. PCL:starch:PRGF (85:10:5 weight ratio) porous solid scaffolds were obtained by a supercritical CO2-assisted foaming process at 100bar and 37°C with no need of post-processing steps. Bioactivity of GFs after processing and scaffold cytocompatibility were confirmed using mesenchymal stem cells. The performance of starch as GF control release component was shown to be dependent on starch pre-gelification conditions. PMID:26917401

  8. Tissue engineering bone-ligament complexes using fiber-guiding scaffolds

    PubMed Central

    Park, Chan Ho; Rios, Hector F.; Jin, Qiming; Sugai, James V.; Padial-Molina, Miguel; Taut, Andrei D.; Flanagan, Colleen L.; Hollister, Scott J.; Giannobile, William V.

    2011-01-01

    Regeneration of bone-ligament complexes destroyed due to disease or injury is a clinical challenge due to complex topologies and tissue integration required for functional restoration. Attempts to reconstruct soft-hard tissue interfaces have met with limited clinical success. In this investigation, we manufactured biomimetic fiber-guiding scaffolds using solid free-form fabrication methods that custom fit complex anatomical defects to guide functionally-oriented ligamentous fibers in vivo. Compared to traditional, amorphous or random-porous polymeric scaffolds, the use of perpendicularly oriented microchannels provides better guidance for cellular processes anchoring ligaments between two distinct mineralized structures. These structures withstood biomechanical loading to restore large osseous defects. Cell transplantation using hybrid scaffolding constructs with guidance channels resulted in predictable oriented fiber architecture, greater control of tissue infiltration, and better organization of ligament interface than random scaffold architectures. These findings demonstrate that fiber-guiding scaffolds drive neogenesis of triphasic bone-ligament integration for a variety of clinical scenarios. PMID:21993234

  9. Development and molecular characterization of polymeric micro-nanofibrous scaffold of a defined 3-D niche for in vitro chemosensitivity analysis against acute myeloid leukemia cells

    PubMed Central

    Nair, Maya S; Mony, Ullas; Menon, Deepthy; Koyakutty, Manzoor; Sidharthan, Neeraj; Pavithran, Keechilat; Nair, Shantikumar V; Menon, Krishnakumar N

    2015-01-01

    Standard in vitro drug testing employs 2-D tissue culture plate systems to test anti-leukemic drugs against cell adhesion-mediated drug-resistant leukemic cells that harbor in 3-D bone marrow microenvironments. This drawback necessitates the fabrication of 3-D scaffolds that have cell adhesion-mediated drug-resistant properties similar to in vivo niches. We therefore aimed at exploiting the known property of polyurethane (PU)/poly-l-lactic acid (PLLA) in forming a micro-nanofibrous structure to fabricate unique, not presented before, as far as we are aware, 3-D micro-nanofibrous scaffold composites using a thermally induced phase separation technique. Among the different combinations of PU/PLLA composites generated, the unique PU/PLLA 60:40 composite displayed micro-nanofibrous morphology similar to decellularized bone marrow with increased protein and fibronectin adsorption. Culturing of acute myeloid leukemia (AML) KG1a cells in FN-coated PU/PLLA 60:40 shows increased cell adhesion and cell adhesion-mediated drug resistance to the drugs cytarabine and daunorubicin without changing the original CD34+/CD38?/CD33? phenotype for 168 hours compared to fibronectin tissue culture plate systems. Molecularly, as seen in vivo, increased chemoresistance is associated with the upregulation of anti-apoptotic Bcl2 and the cell cycle regulatory protein p27Kip1 leading to cell growth arrest. Abrogation of Bcl2 activity by the Bcl2-specific inhibitor ABT 737 led to cell death in the presence of both cytarabine and daunorubicin, demonstrating that the cell adhesion-mediated drug resistance induced by Bcl2 and p27Kip1 in the scaffold was similar to that seen in vivo. These results thus show the utility of a platform technology, wherein drug testing can be performed before administering to patients without the necessity for stromal cells. PMID:26028971

  10. Preparation and characterization of nano-hydroxyapatite/polymer composite scaffolds.

    PubMed

    Xiao, Xiufeng; Liu, Rongfang; Huang, Qiongyu

    2008-11-01

    Polycaprolactone/chitosan (PCL/CS) porous composite scaffolds were prepared by solution phase separation method, and the scaffolds were further enhanced by filling with nano-hydroxyapatite/polyvinyl alcohol (n-HA/PVA) composite slurry to prepare n-HA-PVA/PCL-CS composite porous scaffolds through slurry centrifugal filling technique. The morphology, microstructure, component, porosity and mechanical property of the scaffolds were characterized using scanning electron microscope, X-ray diffraction, Fourier transform infrared spectroscope, elemental analyzer and material test machine. The results show that PCL/CS scaffolds have mutual transfixion porous structure just like honeycombs. The porosity of the scaffolds can achieve 60-80%. As the content of CS increases, the porosity increases while the compressive strength decreases. After filled with HA/PVA composite slurry, the porosity of n-HA/PCL-CS composite scaffolds decreases, but still greater than 60%, while the compression modulus can increase to 25.7 MPa. PMID:18574674

  11. Elastin-Coated Biodegradable Photopolymer Scaffolds for Tissue Engineering Applications

    PubMed Central

    Barenghi, Rossella; Beke, Szabolcs; Gavazzo, Paola; Farkas, Balzs; Scaglione, Silvia

    2014-01-01

    One of the main open issues in modern vascular surgery is the nonbiodegradability of implants used for stent interventions, which can lead to small caliber-related thrombosis and neointimal hyperplasia. Some new, resorbable polymeric materials have been proposed to substitute traditional stainless-steel stents, but so far they were affected by poor mechanical properties and low biocompatibility. In this respect, a new material, polypropylene fumarate (PPF), may be considered as a promising candidate to implement the development of next generation stents, due to its complete biodegradability, and excellent mechanical properties and the ease to be precisely patterned. Besides all these benefits, PPF has not been tested yet for vascular prosthesis, mainly because it proved to be almost inert, while the ability to elicit a specific biological function would be of paramount importance in such critical surgery applications. Here, we propose a biomimetic functionalization process, aimed at obtaining specific bioactivation and thus improved cell-polymer interaction. Porous PPF-based scaffolds produced by deep-UV photocuring were coated by elastin and the functionalized scaffolds were extensively characterized, revealing a stable bound between the protein and the polymer surface. Both 3T3 and HUVEC cell lines were used for in vitro tests displaying an enhancement of cells adhesion and proliferation on the functionalized scaffolds. PMID:25405204

  12. Novel Scaffolds Fabricated Using Oleuropein for Bone Tissue Engineering

    PubMed Central

    Fan, Hui; Hui, Junfeng; Duan, Zhiguang; Fan, Daidi; Mi, Yu; Deng, Jianjun; Li, Hui

    2014-01-01

    We investigated the feasibility of oleuropein as a cross-linking agent for fabricating three-dimensional (3D) porous composite scaffolds for bone tissue engineering. Human-like collagen (HLC) and nanohydroxyapatite (n-HAp) were used to fabricate the composite scaffold by way of cross-linking. The mechanical tests revealed superior properties for the cross-linked scaffolds compared to the uncross-linked scaffolds. The as-obtained composite scaffold had a 3D porous structure with pores ranging from 120 to 300??m and a porosity of 73.6 2.3%. The cross-linked scaffolds were seeded with MC3T3-E1 Subclone 14 mouse osteoblasts. Fluorescence staining, the Cell Counting Kit-8 (CCK-8) assay, and scanning electron microscopy (SEM) indicated that the scaffolds enhanced cell adhesion and proliferation. Our results indicate the potential of these scaffolds for bone tissue engineering. PMID:24959582

  13. Porous polymer networks and ion-exchange media and metal-polymer composites made therefrom

    SciTech Connect

    Kanatzidis, Mercouri G; Katsoulidis, Alexandros

    2015-03-10

    Porous polymeric networks and composite materials comprising metal nanoparticles distributed in the polymeric networks are provided. Also provided are methods for using the polymeric networks and the composite materials in liquid- and vapor-phase waste remediation applications. The porous polymeric networks, are highly porous, three-dimensional structures characterized by high surface areas. The polymeric networks comprise polymers polymerized from aldehydes and phenolic molecules.

  14. Porous bodies of hydroxyapatite produced by a combination of the gel-casting and polymer sponge methods

    PubMed Central

    González Ocampo, Jazmín I.; Escobar Sierra, Diana M.; Ossa Orozco, Claudia P.

    2015-01-01

    A combination of gel-casting and polymeric foam infiltration methods is used in this study to prepare porous bodies of hydroxyapatite (HA), to provide a better control over the microstructures of samples. These scaffolds were prepared by impregnating a body of porous polyurethane foam with slurry containing HA powder, and using a percentage of solids between 40% and 50% w/v, and three different types of monomers to provide a better performance. X-Ray Diffraction (XRD), and Fourier Transformed Infrared (FTIR) and Scanning Electron Microscopy (SEM) were employed to evaluate both the powder hydroxyapatite and the scaffolds obtained. In addition, porosity and interconnectivity measurements were taken in accordance with the international norm. Bioactivity was checked using immersion tests in Simulated Body Fluids (SBF). After the sintering process of the porous bodies, the XRD results showed peaks characteristic of a pure and crystalline HA (JCPDS 9-432) as a single phase. SEM images indicate open and interconnected pores inside the material, with pore sizes between 50 and 600 μm. Also, SEM images demonstrate the relatively good bioactivity of the HA scaffolds after immersion in SBF. All results for the porous HA bodies suggest that these materials have great potential for use in tissue engineering. PMID:26966570

  15. Porous bodies of hydroxyapatite produced by a combination of the gel-casting and polymer sponge methods.

    PubMed

    González Ocampo, Jazmín I; Escobar Sierra, Diana M; Ossa Orozco, Claudia P

    2016-03-01

    A combination of gel-casting and polymeric foam infiltration methods is used in this study to prepare porous bodies of hydroxyapatite (HA), to provide a better control over the microstructures of samples. These scaffolds were prepared by impregnating a body of porous polyurethane foam with slurry containing HA powder, and using a percentage of solids between 40% and 50% w/v, and three different types of monomers to provide a better performance. X-Ray Diffraction (XRD), and Fourier Transformed Infrared (FTIR) and Scanning Electron Microscopy (SEM) were employed to evaluate both the powder hydroxyapatite and the scaffolds obtained. In addition, porosity and interconnectivity measurements were taken in accordance with the international norm. Bioactivity was checked using immersion tests in Simulated Body Fluids (SBF). After the sintering process of the porous bodies, the XRD results showed peaks characteristic of a pure and crystalline HA (JCPDS 9-432) as a single phase. SEM images indicate open and interconnected pores inside the material, with pore sizes between 50 and 600 μm. Also, SEM images demonstrate the relatively good bioactivity of the HA scaffolds after immersion in SBF. All results for the porous HA bodies suggest that these materials have great potential for use in tissue engineering. PMID:26966570

  16. Acrylic-acid-functionalized PolyHIPE scaffolds for use in 3D cell culture.

    PubMed

    Hayward, Adam S; Sano, Naoko; Przyborski, Stefan A; Cameron, Neil R

    2013-12-01

    This study describes the development of a functional porous polymer for use as a scaffold to support 3D hepatocyte culture. A high internal phase emulsion (HIPE) is prepared containing the monomers styrene (STY), divinylbenzene (DVB), and 2-ethylhexyl acrylate (EHA) in the external oil phase and the monomer acrylic acid (Aa) in the internal aqueous phase. Upon thermal polymerization with azobisisobutyronitrile (AIBN), the resulting porous polymer (polyHIPE) is found to have an open-cell morphology and a porosity of 89%, both suitable characteristics for 3D cell scaffold applications. X-ray photo-electron spectroscopy reveals that the polyHIPE surface contained 7.5% carboxylic acid functionality, providing a useful substrate for subsequent surface modifications and bio-conjugations. Initial bio-compatibility assessments with human hepatocytes show that the acid functionality does not have any detrimental effect on cell adhesion. It is therefore believed that this material can be a useful precursor scaffold towards 3D substrates that offer tailored surface functionality for enhanced cell adhesion. PMID:24243821

  17. Recent advances in bone tissue engineering scaffolds

    PubMed Central

    Bose, Susmita; Roy, Mangal; Bandyopadhyay, Amit

    2012-01-01

    Bone disorders are of significant concern due to increase in the median age of our population. Traditionally, bone grafts have been used to restore damaged bone. Synthetic biomaterials are now being used as bone graft substitutes. These biomaterials were initially selected for structural restoration based on their biomechanical properties. Later scaffolds were engineered to be bioactive or bioresorbable to enhance tissue growth. Now scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous, biodegradable materials that harbor different growth factors, drugs, genes or stem cells. In this review, we highlight recent advances in bone scaffolds and discuss aspects that still need to be improved. PMID:22939815

  18. One-step fabrication and high photocatalytic activity of porous graphitic carbon nitride/graphene oxide hybrid by direct polymerization of cyanamide without templates

    NASA Astrophysics Data System (ADS)

    Yu, Qingbo; Guo, Shuai; Li, Xianhua; Zhang, Mingxu

    2014-10-01

    Graphene oxide modified porous g-C3N4 (porous g-C3N4/GO) had been synthesized by means of one-step calcination of cyanamide for efficient photocatalysis under visible light irradiation (? > 400 nm). We expect that the photocatalytic activity of this hybrid photocatalyst could be enhanced by the efficient visible light absorption due to the porous structure and efficient photo generated charge separation at the heterojunction formed between porous g-C3N4 and GO. Scanning electron microscopy (SEM) images demonstrated that the as prepared photocatalyst is composed of GO and porous g-C3N4. The UV-vis diffuse reflectance spectrum shows that optical absorption of porous g-C3N4/GO is more intensive than for pristine g-C3N4. The enhanced generation of photocurrent under visible light irradiation (? > 400 nm) is observed for the porous g-C3N4/GO. The results of photocatalytic experiments reveal that the pseudofirst-order kinetic constant of photocatalytic degradation of methylene blue (MB) using the porous g-C3N4/GO is 6 times higher than that of pristine g-C3N4.

  19. Method for making a bio-compatible scaffold

    DOEpatents

    Cesarano, III, Joseph (Albuquerque, NM); Stuecker, John N. (Albuquerque, NM); Dellinger, Jennifer G. (Champaigne, IL); Jamison, Russell D. (Urbana, IL)

    2006-01-31

    A method for forming a three-dimensional, biocompatible, porous scaffold structure using a solid freeform fabrication technique (referred to herein as robocasting) that can be used as a medical implant into a living organism, such as a human or other mammal. Imaging technology and analysis is first used to determine the three-dimensional design required for the medical implant, such as a bone implant or graft, fashioned as a three-dimensional, biocompatible scaffold structure. The robocasting technique is used to either directly produce the three-dimensional, porous scaffold structure or to produce an over-sized three-dimensional, porous scaffold lattice which can be machined to produce the designed three-dimensional, porous scaffold structure for implantation.

  20. Enhancing Osteoconduction of PLLA-Based Nanocomposite Scaffolds for Bone Regeneration Using Different Biomimetic Signals to MSCs

    PubMed Central

    Ciapetti, Gabriela; Granchi, Donatella; Devescovi, Valentina; Baglio, Serena R.; Leonardi, Elisa; Martini, Desire; Jurado, Maria Jesus; Olalde, Beatriz; Armentano, Ilaria; Kenny, Jos M.; Walboomers, Frank X.; Alava, Jos Inaki; Baldini, Nicola

    2012-01-01

    In bone engineering, the adhesion, proliferation and differentiation of mesenchymal stromal cells rely on signaling from chemico-physical structure of the substrate, therefore prompting the design of mimetic extracellular matrix-like scaffolds. In this study, three-dimensional porous poly-L-lactic acid (PLLA)-based scaffolds have been mixed with different components, including single walled carbon nanotubes (CNT), micro-hydroxyapatite particles (HA), and BMP2, and treated with plasma (PT), to obtain four different nanocomposites: PLLA + CNT, PLLA + CNTHA, PLLA + CNT + HA + BMP2 and PLLA + CNT + HA + PT. Adult bone marrow mesenchymal stromal cells (MSCs) were derived from the femur of orthopaedic patients, seeded on the scaffolds and cultured under osteogenic induction up to differentiation and mineralization. The release of specific metabolites and temporal gene expression profiles of marrow-derived osteoprogenitors were analyzed at definite time points, relevant to in vitro culture as well as in vivo differentiation. As a result, the role of the different biomimetic components added to the PLLA matrix was deciphered, with BMP2-added scaffolds showing the highest biomimetic activity on cells differentiating to mature osteoblasts. The modification of a polymeric scaffold with reinforcing components which also work as biomimetic cues for cells can effectively direct osteoprogenitor cells differentiation, so as to shorten the time required for mineralization. PMID:22408463

  1. One-step in situ synthesis and characterization of sponge-like porous calcium phosphate scaffolds using a sol-gel and gel casting hybrid process.

    PubMed

    Wang, Jianxin; Zhao, Huichuan; Zhou, Shaobing; Lu, Xiong; Feng, Bo; Duan, Caihong; Weng, Jie

    2009-08-01

    In this article, a novel strategy to prepare porous calcium phosphate ceramics using a sol-gel and gel-casting hybrid process is presented. The ceramic foams obtained using this method exhibited sponge-like structure with uniform big pores and small pores distributed on the big pore walls. The sizes of big and small pores were within 500-800 and 50-300 microm, respectively. These kinds of porous calcium phosphate ceramics have shown better property in withstanding machining and better microstructures characterized by a very high degree of interconnection and optimal pore size for osteo-conduction compared with those conventionally fabricated. The signification or importance of this study is reflected by one-step in situ synthesis and the use of a sol-gel and gel casting hybrid process. Organic monomers, foaming agents, and surfactants are not required during this novel porous ceramic fabrication. The precursors themselves act as monomers, foaming agents, and surfactants. These advantages will offer a cheap and simple pathway for industrial manufacture. PMID:18523946

  2. Significance of soluble growth factors in the chondrogenic response of human umbilical cord matrix stem cells in a porous three dimensional scaffold.

    PubMed

    Nirmal, Remya S; Nair, Prabha D

    2013-01-01

    Stem cell based tissue engineering has emerged as a promising strategy for articular cartilage regeneration. Foetal derived mesenchymal stem cells (MSCs) with their ease of availability, pluripotency and high expansion potential have been demonstrated to be an attractive cell source over adult MSCs. However, there is a need for optimisation of chondrogenic signals to direct the differentiation of these multipotent MSCs to chondrogenic lineage. In this study we have demonstrated the in vitro chondrogenesis of human umbilical cord matrix MSCs in three dimensional PVA-PCL (polyvinyl alcohol-polycaprolactone) scaffolds in the presence of the individual growth factors TGF?1, TGF?3, IGF, BMP2 and their combination with BMP2. Gene expression, histology and immunohistology were evaluated after 28d culture. The induced cells showed the feature of chondrocytes in their morphology and expression of typical chondrogenic extracellular matrix molecules. Moreover, the real-time PCR assay has shown the expression of gene markers of chondrogenesis, SOX9, collagen type II and aggrecan. The expression of collagen type I and collagen type X was also evaluated. This study has demonstrated the successful chondrogenic induction of human umbilical cord MSCs in 3D scaffolds. Interestingly, the growth factor combination of TGF-?3 and BMP-2 was found to be more effective for chondrogenesis as shown by the real-time PCR studies. The findings of this study suggest the importance of using growth factor combinations for successful chondrogenic differentiation of umbilical cord MSCs. PMID:24213879

  3. Osteoinductive silk fibroin/titanium dioxide/hydroxyapatite hybrid scaffold for bone tissue engineering.

    PubMed

    Kim, Jung-Ho; Kim, Dong-Kyu; Lee, Ok Joo; Ju, Hyung Woo; Lee, Jung Min; Moon, Bo Mi; Park, Hyun Jung; Kim, Dong Wook; Lee, Jun Ho; Park, Chan Hum

    2016-01-01

    The present study demonstrated the fabrication that incorporation of titanium isopropoxide (TiO2) and hydroxyapatite (HA) nanoparticles into the silk fibroin (SF) scaffolds. In this process, we prepared TiO2 nanoparticles using sol-gel synthesis and the porous structure was developed by salt-leaching process. Homogeneous distribution of TiO2 and HA nanoparticles were confirmed by images of VP-FE-SEM and those equipped with energy dispersive X-ray spectrometer. Structural characteristics of the porous SF/TiO2/HA hybrid scaffold were also determined using FTIR analysis and X-ray diffractometer. In this study, the porous SF/TiO2/HA hybrid scaffold showed similar porosity, enhanced mechanical property, but decreased water binding abilities, compared with the porous SF scaffold. For evaluation of the osteogenic differentiation of rat bone marrow mesenchymal stem cells, alkaline phosphatase activity and osteogenic gene expression were employed. Our results revealed that the porous SF/TiO2/HA hybrid scaffold had improved osteoinductivity compared with the porous SF scaffold. These results suggest that the osteogenic property as well as mechanical property of the porous SF/TiO2/HA hybrid scaffold could be better than the porous SF scaffold. Therefore, the porous SF/TiO2/HA hybrid scaffold may be a good promising biomaterial for bone tissue engineering application. PMID:26257379

  4. Accelerated tissue integration into porous materials by immobilizing basic fibroblast growth factor using a biologically safe three-step reaction.

    PubMed

    Kakinoki, Sachiro; Sakai, Yusuke; Fujisato, Toshia; Yamaoka, Tetsuji

    2015-12-01

    Soft tissue integration into a porous structure is important to prevent bacterial infection of percutaneous devices and improve tissue regeneration using porous scaffolds. Here, basic fibroblast growth factor (bFGF) was immobilized on porous polymer materials using a mild and biologically safe three-step reaction: (1) modification with a novel surface-modification peptide (penta-lysine-mussel adhesive sequence, which reacts with various matrices), (2) electrostatic binding of heparin with introduced penta-lysine, and (3) biologically specific binding of bFGF to heparin. Porous polyethylene specimens (PPSs) (D = 6.0 mm, H?=?2.0 mm) with a good size for tissue integration were selected as a base material, immobilized with bFGF, and subcutaneously implanted into mice. Half of the unmodified PPSs extruded out of the body on day 112 postimplantation; however, the three-step reaction completely prevented sample rejection. Tissue integration was greatly accelerated by immobilizing bFGF. Direct physical coating of bFGF on PPS resulted in greater immobilization but lesser tissue integration than that after the three-step bFGF immobilization, indicating that heparin binds and enhances bFGF efficacy. This three-step bFGF immobilization reaction will be applicable to various polymeric, metallic, and ceramic materials and is a simple strategy to integrate tissue on porous medical devices or scaffolds for tissue regeneration. PMID:26034014

  5. Memory effects of nematic liquid crystals in porous network: the role of geometry

    NASA Astrophysics Data System (ADS)

    Serra, Francesca; Eaton, Shane; Buscaglia, Marco; Cerbino, Roberto; Cerullo, Giulio; Osellame, Roberto; Bellini, Tommaso

    2014-03-01

    We exploit here the bistability of nematic liquid crystals (NLC) induced by their confinement into bicontinuous porous networks. In such a confined liquid crystal, the application of a strong external field induces the reconfiguring of topological defects, which then become locked as they entangle with the porous material. In this sense, the system has a memory of the applied field and it retains its orientation also when the field is removed. Computer simulations already showed that this effect depends on the geometry and the topology of the porous material. Incorporating liquid crystals in laser-microfabricated structures, made with two-photon polymerization, allows us to experimentally test this concept. We compare networks with different geometry and measure the memory of liquid crystals: we show that, as computer simulations predict, the cubic geometry yields the biggest memory effect. Both experiments and simulations also show that defects and anisotropies in the porous structure are important parameters that can substantially affect the memory. The small size of the scaffold (50-100 microns) and the large memory of the liquid crystals in cubic scaffold make this system promising for applications. Cariplo Grants 2008-2413 and 2010-0635, JSPS fellowship.

  6. Resorbable glass-ceramic phosphate-based scaffolds for bone tissue engineering: synthesis, properties, and in vitro effects on human marrow stromal cells.

    PubMed

    Vitale-Brovarone, Chiara; Ciapetti, Gabriela; Leonardi, Elisa; Baldini, Nicola; Bretcanu, Oana; Vern, Enrica; Baino, Francesco

    2011-11-01

    Highly porous bioresorbable glass-ceramic scaffolds were prepared via sponge replication method by using an open-cell polyurethane foam as a template and phosphate-based glass powders. The glass, belonging to the P2O5-SiO2-CaO-MgO-Na2O-K2O system, was synthesized by a melting-quenching route, ground, and sieved to obtain powders with a grain size of less than 30??m. A slurry containing glass powders, polyvinyl alcohol, and water was prepared to coat the polymeric template. The removal of the polymer and the sintering of the glass powders were performed by a thermal treatment, in order to obtain an inorganic replica of the template structure. The structure and properties of the scaffold were investigated from structural, morphological, and mechanical viewpoints by means of X-ray diffraction, scanning electron microscopy, density measurements, image analysis, and compressive tests. The scaffolds exhibited a trabecular architecture that closely mimics the structure of a natural spongy bone. The solubility of the porous structures was assessed by soaking the samples in acellular simulated body fluid (SBF) and Tris-HCl for different time frames and then by assessing the scaffold weight loss. As far as the test in SBF is concerned, the nucleation of hydroxyapatite on the scaffold trabeculae demonstrates the bioactivity of the material. Biological tests were carried out using human bone marrow stromal cells to test the osteoconductivity of the material. The cells adhered to the scaffold struts and were metabolically active; it was found that cell differentiation over proliferation occurred. Therefore, the produced scaffolds, being biocompatible, bioactive, resorbable, and structurally similar to a spongy bone, can be proposed as interesting candidates for bone grafting. PMID:20566654

  7. Effect of material, process parameters, and simulated body fluids on mechanical properties of 13-93 bioactive glass porous constructs made by selective laser sintering.

    PubMed

    Kolan, Krishna C R; Leu, Ming C; Hilmas, Gregory E; Velez, Mariano

    2012-09-01

    The effect of particle size distribution, binder content, processing parameters, and sintering schedule on the microstructure and mechanical properties of porous constructs was investigated. The porous constructs were produced by indirect selective laser sintering (SLS) of 13-93 bioactive glass using stearic acid as a polymeric binder. The binder content and d(50) particle size in the feedstock powders were simultaneously reduced from 22 to 12 wt% and from 20 to 11 ?m, respectively, to identify the minimum binder content required for the SLS fabrication. An average particle size of ?16 ?m with a binder content of 15 wt% significantly reduced post-processing time and improved mechanical properties. Increasing the laser power and scan speed at the energy density of 1 cal/cm maintained the feature sharpness of the parts during the fabrication of green parts and could almost double the mechanical properties of the sintered parts. Changes in the heating rates, ranging from 0.1 to 2 C/min, during the post-processing of the fabricated "green" scaffolds showed that the heating rate significantly affects the densification and mechanical properties of the sintered scaffolds. The compressive strength of the scaffolds manufactured with the optimized parameters varied from 41 MPa, for a scaffold with a porosity of ?50%, to 157 MPa, for a dense part. The bioactive scaffolds soaked in simulated body fluids for durations up to 6 weeks were used to evaluate the change in mechanical properties in vitro. PMID:22842272

  8. Scaffolding and Metacognition

    ERIC Educational Resources Information Center

    Holton, Derek; Clarke, David

    2006-01-01

    This paper proposes an expanded conception of scaffolding with four key elements: (1) scaffolding agency--expert, reciprocal, and self-scaffolding; (2) scaffolding domain--conceptual and heuristic scaffolding; (3) the identification of self-scaffolding with metacognition; and (4) the identification of six zones of scaffolding activity; each zone

  9. Scaffolding and Metacognition

    ERIC Educational Resources Information Center

    Holton, Derek; Clarke, David

    2006-01-01

    This paper proposes an expanded conception of scaffolding with four key elements: (1) scaffolding agency--expert, reciprocal, and self-scaffolding; (2) scaffolding domain--conceptual and heuristic scaffolding; (3) the identification of self-scaffolding with metacognition; and (4) the identification of six zones of scaffolding activity; each zone…

  10. Microspheres leaching for scaffold porosity control.

    PubMed

    Draghi, L; Resta, S; Pirozzolo, M G; Tanzi, M C

    2005-12-01

    Scaffold morphology plays a key role in the development of tissue engineering constructs. The control of pore size, shape and interconnection is needed to achieve adequate nutrient transport and cell ingrowth. Several techniques are available for scaffold manufacturing, but none allows easy control of morphology and is, at the same time, applicable to a wide variety of materials. To investigate the possibility of processing a wide range polymers by solvent casting/particulate leaching with accurate control of scaffold morphology, three different porogens (gelatin microspheres, paraffin microspheres and sodium chloride crystals) were used to fabricate scaffolds from commonly employed biodegradable polymers. The outcome of processing was evaluated in terms of scaffold morphology and structure/properties relationships. Highly porous scaffolds were obtained with all porogens and well defined spherical pores resulted from microspheres leaching. Furthermore, scaffolds with spherical pores showed better mechanical performance and lower flow resistance. Cytocompatibility tests performed showed no evidence of processing residuals released from the scaffolds. Solvent casting/microspheres leaching, particularly gelatin microspheres leaching, can be used to process a large number of polymers and enables to tailor scaffold pore size, shape and interconnection, thus providing a powerful tool for material selection and optimization of scaffold morphology. PMID:16362206

  11. Platelet-Rich Plasma Favors Proliferation of Canine Adipose-Derived Mesenchymal Stem Cells in Methacrylate-Endcapped Caprolactone Porous Scaffold Niches

    PubMed Central

    Rodríguez-Jiménez, Francisco Javier; Valdes-Sánchez, Teresa; Carrillo, José M.; Rubio, Mónica; Monleon-Prades, Manuel; García-Cruz, Dunia Mercedes; García, Montserrat; Cugat, Ramón; Moreno-Manzano, Victoria

    2012-01-01

    Osteoarticular pathologies very often require an implementation therapy to favor regeneration processes of bone, cartilage and/or tendons. Clinical approaches performed on osteoarticular complications in dogs constitute an ideal model for human clinical translational applications. The adipose-derived mesenchymal stem cells (ASCs) have already been used to accelerate and facilitate the regenerative process. ASCs can be maintained in vitro and they can be differentiated to osteocytes or chondrocytes offering a good tool for cell replacement therapies in human and veterinary medicine. Although ACSs can be easily obtained from adipose tissue, the amplification process is usually performed by a time consuming process of successive passages. In this work, we use canine ASCs obtained by using a Bioreactor device under GMP cell culture conditions that produces a minimum of 30 million cells within 2 weeks. This method provides a rapid and aseptic method for production of sufficient stem cells with potential further use in clinical applications. We show that plasma rich in growth factors (PRGF) treatment positively contributes to viability and proliferation of canine ASCs into caprolactone 2-(methacryloyloxy) ethyl ester (CLMA) scaffolds. This biomaterial does not need additional modifications for cASCs attachment and proliferation. Here we propose a framework based on a combination of approaches that may contribute to increase the therapeutical capability of stem cells by the use of PRGF and compatible biomaterials for bone and connective tissue regeneration. PMID:24955632

  12. Effect of hydroxyapatite-containing microspheres embedded into three-dimensional magnesium phosphate scaffolds on the controlled release of lysozyme and in vitro biodegradation

    PubMed Central

    Lee, Jongman; Yun, Hui-suk

    2014-01-01

    The functionality of porous three-dimensional (3D) magnesium phosphate (MgP) scaffold was investigated for the development of a novel protein delivery system and biomimetic bone tissue engineering scaffold. This enhancement can be achieved by incorporation of hydroxyapatite (HA)-containing polymeric microspheres (MSs) into a bulk MgP matrix, and a paste-extruding deposition (PED) system. In this work, the amount of MS and HA was precisely controlled when manufacturing MS-embedded MgP (MS/MgP) composite scaffolds. The main influence was researched in terms of in vitro lysozyme-release, in vitro biodegradation, mechanical properties, and in vitro calcification. The controlled release of lysozyme was indicated, while showing graded release patterns according to HA content. The composite scaffolds degraded gradually with MS content and degradation time. Due to the effect of HA inclusion, the higher HA-containing MS/MgP scaffolds could, not only delay the biodegradation process but also, compensate for the possible loss of mechanical properties. In this regard, it is reasonable to confirm the inverse relationship between biodegradation and corresponding compressive properties. In order to encourage bioactivity and osteoconductivity, the MS/MgP composite scaffolds were subjected to simulated body fluid treatment. Calcium deposition was, in turn, improved with increasing MS and HA content over time. This quantitative result was also proved using morphological and elemental analysis. In summary, a significant transformation of a monolithic MgP scaffold was directed toward a multifunctional bone tissue engineering scaffold equipped with controlled protein delivery, biodegradability, and bioactivity. PMID:25214782

  13. Fabrication of porous microtent structures toward an in vitro endothelium model

    NASA Astrophysics Data System (ADS)

    Kim, Bongsu; Zhang, Xu; Borteh, Hassan; Li, Zhenqing; Guan, Jianjun; Zhao, Yi

    2012-08-01

    This paper reports the fabrication of compliant and permeable thin films with controlled curvature preferable to serve as engineering scaffolds for the production of in vivo like vascular endothelial constructs. A simple fabrication process was developed to fabricate three-dimensional ‘tent’ like microstructures by combining electrospinning and microfabrication. In particular, the ‘microtents’ were created by electrospinning mechanically flexible poly(etherurethane)urea(PEUU) polymer on a microstructured collecting substrate. The shape of the ‘microtents’ can be tuned by adjusting the geometries of microstructures on the collecting substrate and the operational parameters of electrospinning. Mechanical characterization showed the nonlinear mechanical behavior of porous polymeric thin films is similar to those of soft tissues, indicating that these thin films may serve as scaffolds for mimicking local mechanical environment of vascular tissues. Human endothelial cells were successfully cultured on the concave side of the porous thin film, constituting an endothelium model in vitro. This work addresses the need for engineered tissue scaffolds that can mimic both morphological and mechanical environments of natural vascular endothelium. The coupled effects of mechanical, structural and biochemical factors on vascular endothelium can thus be investigated.

  14. Silk scaffolds for musculoskeletal tissue engineering.

    PubMed

    Yao, Danyu; Liu, Haifeng; Fan, Yubo

    2016-02-01

    The musculoskeletal system, which includes bone, cartilage, tendon/ligament, and skeletal muscle, is becoming the targets for tissue engineering because of the high need for their repair and regeneration. Numerous factors would affect the use of musculoskeletal tissue engineering for tissue regeneration ranging from cells used for scaffold seeding to the manufacture and structures of materials. The essential function of the scaffolds is to convey growth factors as well as cells to the target site to aid the regeneration of the injury. Among the variety of biomaterials used in scaffold engineering, silk fibroin is recognized as an ideal material for its impressive cytocompatibility, slow biodegradability, and excellent mechanical properties. The current review describes the advances made in the fabrication of silk fibroin scaffolds with different forms such as films, particles, electrospun fibers, hydrogels, three-dimensional porous scaffolds, and their applications in the regeneration of musculoskeletal tissues. PMID:26445979

  15. Nanofibrous Scaffolds for Dental and Craniofacial Applications

    PubMed Central

    Gupte, M.J.; Ma, P.X.

    2012-01-01

    Tissue-engineering solutions often harness biomimetic materials to support cells for functional tissue regeneration. Three-dimensional scaffolds can create a multi-scale environment capable of facilitating cell adhesion, proliferation, and differentiation. One such multi-scale scaffold incorporates nanofibrous features to mimic the extracellular matrix along with a porous network for the regeneration of a variety of tissues. This review will discuss nanofibrous scaffold synthesis/fabrication, biological effects of nanofibers, their tissue- engineering applications in bone, cartilage, enamel, dentin, and periodontium, patient-specific scaffolds, and incorporated growth factor delivery systems. Nanofibrous scaffolds cannot only further the field of craniofacial regeneration but also advance technology for tissue-engineered replacements in many physiological systems. PMID:21828356

  16. Mechanical properties and dual drug delivery application of poly(lactic-co-glycolic acid) scaffolds fabricated with a poly(β-amino ester) porogen.

    PubMed

    Clark, Amanda; Milbrandt, Todd A; Hilt, J Zach; Puleo, David A

    2014-05-01

    Polymeric scaffolds that are biocompatible and biodegradable are widely used for tissue engineering applications. Scaffolds can be further enhanced by enabling the release of one or more drugs to stimulate regeneration or for the treatment of a specific disease or condition. In this study, poly(lactic-co-glycolic acid) (PLGA) microspheres were mixed with poly(β-amino ester) (PBAE) particles to create novel hybrid scaffolds capable of dual release of drug and growth factor. Fast-degrading PBAE particles loaded with the drug ketoprofen acted as porogens that provided a rapid 12h release. The PLGA microspheres were loaded with a growth factor, bone morphogenetic protein 2, and fused together around the porogens to create a slow-degrading matrix that provided sustained release lasting 70days. Drug release was further tailored by varying the amount of porogen added to the scaffold. Bioactivity measurements demonstrated that the scaffold fabrication technique did not damage the drug or protein. The compressive modulus was affected by the amount of porogen added, extending from 50 to 111MPa for loadings from 60 to 40% PBAE, and after 5days of degradation, it decreased to 0.6 to 1.1kPa when the porogen was gone. PLGA containing a quick-degrading porogen can be used to release two drugs while developing a porous microarchitecture for cell ingrowth with in a matrix capable of maintaining a compressive modulus applicable for soft tissue implants. PMID:24424269

  17. Fabrication of Mechanically Tunable and Bioactive Metal Scaffolds for Biomedical Applications.

    PubMed

    Jung, Hyun-Do; Lee, Hyun; Kim, Hyoun-Ee; Koh, Young-Hag; Song, Juha

    2015-01-01

    Biometal systems have been widely used for biomedical applications, in particular, as load-bearing materials. However, major challenges are high stiffness and low bioactivity of metals. In this study, we have developed a new method towards fabricating a new type of bioactive and mechanically reliable porous metal scaffolds-densified porous Ti scaffolds. The method consists of two fabrication processes, 1) the fabrication of porous Ti scaffolds by dynamic freeze casting, and 2) coating and densification of the porous scaffolds. The dynamic freeze casting method to fabricate porous Ti scaffolds allowed the densification of porous scaffolds by minimizing the chemical contamination and structural defects. The densification process is distinctive for three reasons. First, the densification process is simple, because it requires a control of only one parameter (degree of densification). Second, it is effective, as it achieves mechanical enhancement and sustainable release of biomolecules from porous scaffolds. Third, it has broad applications, as it is also applicable to the fabrication of functionally graded porous scaffolds by spatially varied strain during densification. PMID:26709604

  18. ECM Inspired Coating of Embroidered 3D Scaffolds Enhances Calvaria Bone Regeneration

    PubMed Central

    Rentsch, C.; Rentsch, B.; Heinemann, S.; Bernhardt, R.; Bischoff, B.; Förster, Y.; Scharnweber, D.; Rammelt, S.

    2014-01-01

    Resorbable polymeric implants and surface coatings are an emerging technology to treat bone defects and increase bone formation. This approach is of special interest in anatomical regions like the calvaria since adults lose the capacity to heal large calvarial defects. The present study assesses the potential of extracellular matrix inspired, embroidered polycaprolactone-co-lactide (PCL) scaffolds for the treatment of 13 mm full thickness calvarial bone defects in rabbits. Moreover the influence of a collagen/chondroitin sulfate (coll I/cs) coating of PCL scaffolds was evaluated. Defect areas filled with autologous bone and empty defects served as reference. The healing process was monitored over 6 months by combining a novel ultrasonographic method, radiographic imaging, biomechanical testing, and histology. The PCL coll I/cs treated group reached 68% new bone volume compared to the autologous group (100%) and the biomechanical stability of the defect area was similar to that of the gold standard. Histological investigations revealed a significantly more homogenous bone distribution over the whole defect area in the PCL coll I/cs group compared to the noncoated group. The bioactive, coll I/cs coated, highly porous, 3-dimensional PCL scaffold acted as a guide rail for new skull bone formation along and into the implant. PMID:25013767

  19. Optimization of tyrosine-derived polycarbonate terpolymers for bone regeneration scaffolds

    NASA Astrophysics Data System (ADS)

    Resurreccion-Magno, Maria Hanshella C.

    Tyrosine-derived polycarbonates (TyrPC) are a versatile class of polymers highly suitable for bone tissue engineering. Among the tyrosine-derived polycarbonates, poly(DTE carbonate) has an FDA masterfile that documents its biocompatibility and non-toxicity and has shown potential utility in orthopedics due to its osteoconductive properties and strength. DTE stands for desaminotyrosyl-tyrosine ethyl ester and is the most commonly used tyrosine-derived monomer. However, in vitro degradation studies showed that poly(DTE carbonate) did not completely resorb even after four years of incubation in phosphate buffered saline. Thus for bone regeneration, which only requires a temporary implant until the bone heals, poly(DTE carbonate) would not be the best choice. The goal of the present research was to optimize a scaffold composition for bone regeneration that is based on desaminotyrosyl-tyrosine alkyl ester (DTR), desaminotyrosyl-tyrosine (DT) and poly(ethylene glycol) (PEG). Five areas of research were presented: (1) synthesis and characterization of a focused library of TyrPC terpolymers; (2) evaluation of the effects of how small changes on the composition affected the mechanism and kinetics of polymer degradation and erosion; (3) fabrication of bioactive three-dimensional porous scaffold constructs for bone regeneration; (4) assessment of osteogenic properties in vitro using pre-osteoblasts; and (5) evaluation of bone regeneration potential, with or without recombinant human bone morphogenetic protein-2 (rhBMP-2), in vivo using a critical sized defect (CSD) rabbit calvaria (cranium) model. Small changes in the composition, such as changing the R group of DTR from ethyl to methyl, varying the mole percentages of DT and PEG, and using a different PEG block length, affected the overall properties of these polymers. Porous scaffolds were prepared by a combination of solvent casting, porogen leaching and phase separation techniques. Calcium phosphate was coated on the surface post-fabrication. The scaffolds displayed (i) a bimodal pore architecture with micropores (< 20 mum) and macropores (200 -- 400 mum), (ii) a highly interconnected and open pore structure, and (iii) a highly organized microstructure. These scaffolds supported robust cell attachment and promoted osteogenic differentiation of pre-osteoblasts. This is the first report that a synthetic polymeric scaffold either without a biological supplement or with a minimal dose of rhBMP-2 induced comparable bone regeneration to a commercially available bone substitute in a non-rodent CSD animal model.

  20. Tissue differentiation in an in vivo bioreactor: in silico investigations of scaffold stiffness.

    PubMed

    Khayyeri, Hanifeh; Checa, Sara; Tgil, Magnus; O'Brien, Fergal J; Prendergast, Patrick J

    2010-08-01

    Scaffold design remains a main challenge in tissue engineering due to the large number of requirements that need to be met in order to create functional tissues in vivo. Computer simulations of tissue differentiation within scaffolds could serve as a powerful tool in elucidating the design requirements for scaffolds in tissue engineering. In this study, a lattice-based model of a 3D porous scaffold construct derived from micro CT and a mechano-biological simulation of a bone chamber experiment were combined to investigate the effect of scaffold stiffness on tissue differentiation inside the chamber. The results indicate that higher scaffold stiffness, holding pore structure constant, enhances bone formation. This study demonstrates that a lattice approach is very suitable for modelling scaffolds in mechano-biological simulations, since it can accurately represent the micro-porous geometries of scaffolds in a 3D environment and reduce computational costs at the same time. PMID:20037774

  1. Peripheral nerve morphogenesis induced by scaffold micropatterning

    PubMed Central

    Memon, Danish; Boneschi, Filippo Martinelli; Madaghiele, Marta; Brambilla, Paola; Del Carro, Ubaldo; Taveggia, Carla; Riva, Nilo; Trimarco, Amelia; Lopez, Ignazio D.; Comi, Giancarlo; Pluchino, Stefano; Martino, Gianvito; Sannino, Alessandro; Quattrini, Angelo

    2014-01-01

    Several bioengineering approaches have been proposed for peripheral nervous system repair, with limited results and still open questions about the underlying molecular mechanisms. We assessed the biological processes that occur after the implantation of collagen scaffold with a peculiar porous microstructure of the wall in a rat sciatic nerve transection model compared to commercial collagen conduits and nerve crush injury using functional, histological and genome wide analyses. We demonstrated that within 60 days, our conduit had been completely substituted by a normal nerve. Gene expression analysis documented a precise sequential regulation of known genes involved in angiogenesis, Schwann cells/axons interactions and myelination, together with a selective modulation of key biological pathways for nerve morphogenesis induced by porous matrices. These data suggest that the scaffolds microstructure profoundly influences cell behaviors and creates an instructive micro-environment to enhance nerve morphogenesis that can be exploited to improve recovery and understand the molecular differences between repair and regeneration. PMID:24559639

  2. Towards application of one- and two-dimensional nanomaterials for reinforcement of polymeric nanocomposite bone grafts

    NASA Astrophysics Data System (ADS)

    Farrshid, Behzad

    One- and two-dimensional (1-D and 2-D) nanomaterials possess extraordinary physiochemical properties such as large surface area, excellent mechanical properties, high surface energy and good dispersivity in organic and biological solvents, therefore, they have been extensively used as reinforcing agents to improve the mechanical properties of polymeric scaffolds for bone tissue engineering applications. Carbon nanomaterials such as carbon nanotubes and graphene have been used as reinforcing agents for biodegradable polymeric scaffolds and composites, however, their short- and long-term in vitro cytotoxicity and in vivo biocompatibility is an area of extensive debate. In this study, we have systematically investigated the effects of addition of low concentrations (0.01-0.2 wt. %) of 1-D and 2-D carbon nanomaterials (graphene oxide nanoplatelets, graphene oxide nanoribbons and carbon nanotubes) and inorganic nanomaterials (boron nitride nanotubes, boron nitride nanoplatelers, tungsten disulfide nanotubes and molybdenum disulfide nanoplatelets) on the mechanical properties, cytocompatibility, and bioactivity of poly(propylene fumarate) (PPF) nanocomposites towards their potential applications as porous and nonporous implants for bone tissue engineering. Addition of nanomaterials in the PPF matrix improved the compressive and flexural mechanical properties of non-porous crosslinked PPF nanocomposites and porous PPF scaffolds. Our results suggest that in addition to high surface roughness and surface area of the nanomaterials, the presence of functional groups on the surface of nanomaterials leads to an increased nanomaterial-polymer interaction and a uniform dispersion of nanomaterials in polymer matrix which may be the key factors responsible for an improved mechanical reinforcement. The in vitro studies showed an excellent cytocompatibility for both carbon and inorganic nanomaterial reinforced PPF nanocomposites and scaffolds. Protein adsorption studies and in vitro osteogenic differentiation studies also showed that addition of these 1-D and 2-D carbon and inorganic nanomaterials leads to an improved protein adsorption that promotes osteogenic differentiation and calcium mineralization in vitro. and good cytocompatibility of PPF nanocomposites. The long term implication of this research focuses on the development of mechanically strong, biocompatible, biodegradable and bioactive nanocomposites that can potentially replace commercial bone grafts that often lack the required mechanical properties for load bearing bone tissue engineering applications.

  3. Bone Tissue Engineering by Using Calcium Phosphate Glass Scaffolds and the Avidin-Biotin Binding System.

    PubMed

    Kim, Min-Chul; Hong, Min-Ho; Lee, Byung-Hyun; Choi, Heon-Jin; Ko, Yeong-Mu; Lee, Yong-Keun

    2015-12-01

    Highly porous and interconnected scaffolds were fabricated using calcium phosphate glass (CPG) for bone tissue engineering. An avidin-biotin binding system was used to improve osteoblast-like cell adhesion to the scaffold. The scaffolds had open macro- and micro-scale pores, and continuous struts without cracks or defects. Scaffolds prepared using a mixture (amorphous and crystalline CPG) were stronger than amorphous group and crystalline group. Cell adhesion assays showed that more cells adhered, with increasing cell seeding efficiency to the avidin-adsorbed scaffolds, and that cell attachment to the highly porous scaffolds significantly differed between avidin-adsorbed scaffolds and other scaffolds. Proliferation was also significantly higher for avidin-adsorbed scaffolds. Osteoblastic differentiation of MG-63 cells was observed at 3 days, and MG-63 cells in direct contact with avidin-adsorbed scaffolds were positive for type I collagen, osteopontin, and alkaline phosphatase gene expression. Osteocalcin expression was observed in the avidin-adsorbed scaffolds at 7 days, indicating that cell differentiation in avidin-adsorbed scaffolds occurred faster than the other scaffolds. Thus, these CPG scaffolds have excellent biological properties suitable for use in bone tissue engineering. PMID:26040755

  4. Development of porous PLGA/PEI1.8k biodegradable microspheres for the delivery of mesenchymal stem cells (MSCs).

    PubMed

    Lee, Young Sook; Lim, Kwang Suk; Oh, Jung-Eun; Yoon, A-Rum; Joo, Wan Seok; Kim, Hyun Soo; Yun, Chae-Ok; Kim, Sung Wan

    2015-05-10

    Multipotent mesenchymal stem cells (MSCs) promise a therapeutic alternative for many debilitating and incurable diseases. However, one of the major limitations for the therapeutic application of human MSC (hMSC) is the lengthy ex vivo expansion time for preparing a sufficient amount of cells due to the low engraftment rate after transplantation. To solve this conundrum, a porous biodegradable polymeric microsphere was investigated as a potential scaffold for the delivery of MSCs. The modified water/oil/water (W1/O/W2) double emulsion solvent evaporation method was used for the construction of porous microspheres. PEI1.8k was blended with poly(lactic-co-glycolic acid) (PLGA) to enhance electrostatic cellular attachment to the microspheres. The porous PLGA/PEI1.8k (PPP) particles demonstrated an average particle size of 290μm and an average pore size of 14.3μm, providing a micro-carrier for the MSC delivery. PPP particles allowed for better attachment of rMSCs than non-porous PLGA/PEI1.8k (NPP) particles and non-porous (NP) and porous PLGA (PP) microspheres. rMSC successfully grew on the PPP particles for 2weeks in vitro. Next, PPP particles loaded with 3 different amounts of hMSC showed increased in vivo engraftment rates and maintained the stemness characteristics of hMSC compared with hMSCs-alone group in rats 2weeks after intramyocardial administration. These customized PPP particles for MSC delivery are a biodegradable and injectable scaffold that can be used for clinical applications. PMID:25575866

  5. 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.

  6. In Vitro and In Vivo Characterization of Pentaerythritol Triacrylate-co-Trimethylolpropane Nanocomposite Scaffolds as Potential Bone Augments and Grafts

    PubMed Central

    Chen, Cong; Garber, Leah; Smoak, Mollie; Fargason, Carmel; Scherr, Thomas; Blackburn, Caleb; Bacchus, Sasha; Lopez, Mandi J.; Pojman, John A.; Del Piero, Fabio

    2015-01-01

    A thiol-acrylate-based copolymer synthesized via an amine-catalyzed Michael addition was studied in vitro and in vivo to assess its potential as an in situ polymerizing graft or augment in bone defect repair. The blends of hydroxyapatite (HA) with pentaerythritol triacrylate-co-trimethylolpropane (PETA), cast as solids or gas foamed as porous scaffolds, were evaluated in an effort to create a biodegradable osteogenic material for use as a bone-void-filling augment. Osteogenesis experiments were conducted with human adipose-derived mesenchymal stromal cells (hASCs) to determine the ability of the material to serve as an osteoinductive substrate. Poly(ɛ-caprolactone) (PCL) composites PCL:HA (80:20) (wt/wt%) served as the control scaffold, while the experimental scaffolds included PETA:HA (100:0), (85:15), (80:20), and (75:25) composites (wt/wt%). The results indicate that PETA:HA (80:20) foam composites had higher mechanical strength than the corresponding porous PCL:HA (80:20) scaffolds made by thermo-precipitation method, and in the case of foamed composites, increasing HA content directly correlated with increased yield strength. For cytotoxicity and osteogenesis experiments, hASCs cultured for 21 days on PETA:HA scaffolds in stromal medium displayed the greatest number of live cells compared with PCL:HA composites. Moreover, hASCs cultured on foamed PETA:HA (80:20) scaffolds resulted in the greatest mineralization, increased alkaline phosphatase (ALP) expression, and the highest osteocalcin (OCN) expression after 21 days. Overall, the PETA:HA (80:20) and PETA:HA (85:15) scaffolds, with 66.38% and 72.02% porosity, respectively, had higher mechanical strength and cytocompatibility compared with the PCL:HA control. The results of the 6-week in vivo biocompatibility study using a posterior lumbar spinal fusion model demonstrate that PETA:HA can be foamed in vivo without serious adverse effects at the surgical site. Additionally, it was demonstrated that cells migrate into the interconnected pore volume and are found within centers of ossification. PMID:25134965

  7. In vitro and in vivo characterization of pentaerythritol triacrylate-co-trimethylolpropane nanocomposite scaffolds as potential bone augments and grafts.

    PubMed

    Chen, Cong; Garber, Leah; Smoak, Mollie; Fargason, Carmel; Scherr, Thomas; Blackburn, Caleb; Bacchus, Sasha; Lopez, Mandi J; Pojman, John A; Del Piero, Fabio; Hayes, Daniel J

    2015-01-01

    A thiol-acrylate-based copolymer synthesized via an amine-catalyzed Michael addition was studied in vitro and in vivo to assess its potential as an in situ polymerizing graft or augment in bone defect repair. The blends of hydroxyapatite (HA) with pentaerythritol triacrylate-co-trimethylolpropane (PETA), cast as solids or gas foamed as porous scaffolds, were evaluated in an effort to create a biodegradable osteogenic material for use as a bone-void-filling augment. Osteogenesis experiments were conducted with human adipose-derived mesenchymal stromal cells (hASCs) to determine the ability of the material to serve as an osteoinductive substrate. Poly(?-caprolactone) (PCL) composites PCL:HA (80:20) (wt/wt%) served as the control scaffold, while the experimental scaffolds included PETA:HA (100:0), (85:15), (80:20), and (75:25) composites (wt/wt%). The results indicate that PETA:HA (80:20) foam composites had higher mechanical strength than the corresponding porous PCL:HA (80:20) scaffolds made by thermo-precipitation method, and in the case of foamed composites, increasing HA content directly correlated with increased yield strength. For cytotoxicity and osteogenesis experiments, hASCs cultured for 21 days on PETA:HA scaffolds in stromal medium displayed the greatest number of live cells compared with PCL:HA composites. Moreover, hASCs cultured on foamed PETA:HA (80:20) scaffolds resulted in the greatest mineralization, increased alkaline phosphatase (ALP) expression, and the highest osteocalcin (OCN) expression after 21 days. Overall, the PETA:HA (80:20) and PETA:HA (85:15) scaffolds, with 66.38% and 72.02% porosity, respectively, had higher mechanical strength and cytocompatibility compared with the PCL:HA control. The results of the 6-week in vivo biocompatibility study using a posterior lumbar spinal fusion model demonstrate that PETA:HA can be foamed in vivo without serious adverse effects at the surgical site. Additionally, it was demonstrated that cells migrate into the interconnected pore volume and are found within centers of ossification. PMID:25134965

  8. Composite Scaffolds of Interfacial Polyelectrolyte Fibers for Temporally Controlled Release of Biomolecules.

    PubMed

    Cutiongco, Marie Francene A; Teo, Benjamin Kim Kiat; Yim, Evelyn King Fai

    2015-01-01

    Various scaffolds used in tissue engineering require a controlled biochemical environment to mimic the physiological cell niche. Interfacial polyelectrolyte complexation (IPC) fibers can be used for controlled delivery of various biological agents such as small molecule drugs, cells, proteins and growth factors. The simplicity of the methodology in making IPC fibers gives flexibility in its application for controlled biomolecule delivery. Here, we describe a method of incorporating IPC fibers into two different polymeric scaffolds, hydrophilic polysaccharide and hydrophobic polycaprolactone, to create a multi-component composite scaffold. We showed that IPC fibers can be easily embedded into these polymeric structures, enhancing the capability for sustained release and improved preservation of biomolecules. We also created a composite polymeric scaffold with topographical cues and sustained biochemical release that can have synergistic effects on cell behavior. Composite polymeric scaffolds with IPC fibers represent a novel and simple method of recreating the cellular niche. PMID:26325384

  9. Micro-computed tomography (micro-CT) as a potential tool to assess the effect of dynamic coating routes on the formation of biomimetic apatite layers on 3D-plotted biodegradable polymeric scaffolds.

    PubMed

    Oliveira, A L; Malafaya, P B; Costa, S A; Sousa, R A; Reis, R L

    2007-02-01

    This work studies the influence of dynamic biomimetic coating procedures on the growth of bone-like apatite layers at the surface of starch/polycaprolactone (SPCL) scaffolds produced by a 3D-plotting technology. These systems are newly proposed for bone Tissue Engineering applications. After generating stable apatite layers through a sodium silicate-based biomimetic methodology the scaffolds were immersed in Simulated Body Fluid solutions (SBF) under static, agitation and circulating flow perfusion conditions, for different time periods. Besides the typical characterization techniques, Micro-Computed Tomography analysis (micro-CT) was used to assess scaffold porosity and as a new tool for mapping apatite content. 2D histomorphometric analysis was performed and 3D virtual models were created using specific softwares for CT reconstruction. By the proposed biomimetic routes apatite layers were produced covering the interior of the scaffolds, without compromising their overall morphology and interconnectivity. Dynamic conditions allowed for the production of thicker apatite layers as consequence of higher mineralizing rates, when comparing with static conditions. micro-CT analysis clearly demonstrated that flow perfusion was the most effective condition in order to obtain well-defined apatite layers in the inner parts of the scaffolds. Together with SEM, this technique was a useful complementary tool for assessing the apatite content in a non-destructive way. PMID:17323152

  10. Variation of flow-induced stresses within scaffolds used in bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Papavassiliou, Dimitrios; Pham, Ngoc; Voronov, Roman; Sikavitsas, Vassilios

    2011-11-01

    Bone tissue engineering is often based on seeding adult stem cells on porous scaffolds and subsequently placing these scaffolds in flow perfusion bioreactors to stimulate cell differentiation and cell growth. In the present study, the distribution of stresses in structured porous scaffolds under flow is investigated by calculating the probability density function of flow-induced stresses in different scaffold geometries with simulations. The physical reason for the development of particular stress distributions is further explored, and it is found that the direction of flow relative to the internal architecture of the porous scaffold is important for stress distributions. When the flow direction is random relative to the configuration of the geometric elements making up the scaffold, it is found that a common distribution, such as the one suggested by Voronov et al. (Appl. Phys. Let., 2010, 97:024101), can be used to describe the stress distribution. NSF CBET-070081.

  11. Fabrication of polylactide nanocomposite scaffolds for bone tissue engineering applications

    NASA Astrophysics Data System (ADS)

    Mkhabela, Vuyiswa J.; Ray, Suprakas Sinha

    2015-05-01

    Highly porous three-dimensional polylactide (PLA) scaffolds were obtained from PLA incorporated with different amounts of chitosan-modified montmorillonite (CS-MMT), through solvent casting and particulate leaching method. The processed scaffolds were tested in vitro for their possible application in bone tissue engineering. Scaffolds were characterized by Focused Ion Beam Scanning Electron Microscopy (FIB SEM), Fourier Transform Infra-Red (FTIR), and X-Ray Diffraction (XRD) to study their structure and intermolecular interactions. Bioresorbability tests in simulated body fluid (pH 7.4) were conducted to assess the response of the scaffolds in a simulated physiological condition. The FIB SEM images of the scaffolds showed a porous architecture with gradual change in morphology with increasing CS-MMT concentration. FTIR analysis revealed the presence of both PLA and CS-MMT particles on the surface of the scaffolds. XRD showed that the crystalline unit cell type was the same for all the scaffolds, and crystallinity decreased with an increase in CS-MMT concentration. The scaffolds were found to be bioresorbable, with rapid bioresorbability on the scaffolds with a high CS-MMT concentration.

  12. Fabrication of polylactide nanocomposite scaffolds for bone tissue engineering applications

    SciTech Connect

    Mkhabela, Vuyiswa J.; Ray, Suprakas Sinha

    2015-05-22

    Highly porous three-dimensional polylactide (PLA) scaffolds were obtained from PLA incorporated with different amounts of chitosan-modified montmorillonite (CS-MMT), through solvent casting and particulate leaching method. The processed scaffolds were tested in vitro for their possible application in bone tissue engineering. Scaffolds were characterized by Focused Ion Beam Scanning Electron Microscopy (FIB SEM), Fourier Transform Infra-Red (FTIR), and X-Ray Diffraction (XRD) to study their structure and intermolecular interactions. Bioresorbability tests in simulated body fluid (pH 7.4) were conducted to assess the response of the scaffolds in a simulated physiological condition. The FIB SEM images of the scaffolds showed a porous architecture with gradual change in morphology with increasing CS-MMT concentration. FTIR analysis revealed the presence of both PLA and CS-MMT particles on the surface of the scaffolds. XRD showed that the crystalline unit cell type was the same for all the scaffolds, and crystallinity decreased with an increase in CS-MMT concentration. The scaffolds were found to be bioresorbable, with rapid bioresorbability on the scaffolds with a high CS-MMT concentration.

  13. Controlled release of an extract of Calendula officinalis flowers from a system based on the incorporation of gelatin-collagen microparticles into collagen I scaffolds: design and in vitro performance.

    PubMed

    Jimnez, Ronald A; Milln, Diana; Suesca, Edward; Sosnik, Alejandro; Fontanilla, Marta R

    2015-06-01

    Aiming to develop biological skin dresses with improved performance in the treatment of skin wounds, acellular collagen I scaffolds were modified with polymeric microparticles and the subsequent loading of a hydroglycolic extract of Calendula officinalis flowers. Microparticles made of gelatin-collagen were produced by a water-in-oil emulsion/cross-linking method. Thereafter, these microparticles were mixed with collagen suspensions at three increasing concentrations and the resulting mixtures lyophilized to make microparticle-loaded porous collagen scaffolds. Resistance to enzymatic degradation, ability to associate with the C. officinalis extract, and the extract release profile of the three gelatin-collagen microparticle-scaffold prototypes were assessed in vitro and compared to collagen scaffolds without microparticles used as control. Data indicated that the incorporation of gelatin-collagen microparticles increased the resistance of the scaffolds to in vitro enzymatic degradation, as well as their association with the C. officinalis flower extract. In addition, a sharp decrease in cytotoxicity, as well as more prolonged release of the extract, was attained. Overall results support the potential of these systems to develop innovative dermal substitutes with improved features. Furthermore, the gelatin-collagen mixture represents a low-cost and scalable alternative with high clinical transferability, especially appealing in developing countries. PMID:25787728

  14. Novel hybrid scaffolds for the cultivation of osteoblast cells.

    PubMed

    Sasmazel, Hilal Turkoglu

    2011-11-01

    In this study, natural biodegradable polysaccharide, chitosan, and synthetic biodegradable polymer, poly(?-caprolactone) (PCL) were used to prepare 3D, hybrid polymeric tissue scaffolds (PCL/chitosan blend and PCL/chitosan/PCL layer by layer scaffolds) by using the electrospinning technique. The hybrid scaffolds were developed through HA addition to accelerate osteoblast cell growth. Characteristic examinations of the scaffolds were performed by micrometer, SEM, contact angle measurement system, ATR-FTIR, tensile machine and swelling experiments. The thickness of all electrospun scaffolds was determined in the range of 0.0100.001-0.0120.002 mm. In order to optimize electrospinning processes, suitable bead-free and uniform scaffolds were selected by using SEM images. Blending of PCL with chitosan resulted in better hydrophilicity for the PCL/chitosan scaffolds. The characteristic peaks of PCL and chitosan in the blend and layer by layer nanofibers were observed. The PCL/chitosan/PCL layer by layer structure had higher elastic modulus and tensile strength values than both individual PCL and chitosan structures. The layer by layer scaffolds exhibited the PBS absorption values of 184.2; 197.2% which were higher than those of PCL scaffolds but lower than those of PCL/chitosan blend scaffolds. SaOs-2 osteosarcoma cell culture studies showed that the highest ALP activities belonged to novel PCL/chitosan/PCL layer by layer scaffolds meaning better cell differentiation on the surfaces. PMID:21839769

  15. Porous polymer media

    DOEpatents

    Shepodd, Timothy J.

    2002-01-01

    Highly crosslinked monolithic porous polymer materials for chromatographic applications. By using solvent compositions that provide not only for polymerization of acrylate monomers in such a fashion that a porous polymer network is formed prior to phase separation but also for exchanging the polymerization solvent for a running buffer using electroosmotic flow, the need for high pressure purging is eliminated. The polymer materials have been shown to be an effective capillary electrochromatographic separations medium at lower field strengths than conventional polymer media. Further, because of their highly crosslinked nature these polymer materials are structurally stable in a wide range of organic and aqueous solvents and over a pH range of 2-12.

  16. Chitosan-based scaffolds for bone tissue engineering

    PubMed Central

    Levengood, Sheeny Lan; Zhang, Miqin

    2014-01-01

    Bone defects requiring grafts to promote healing are frequently occurring and costly problems in health care. Chitosan, a biodegradable, naturally occurring polymer, has drawn considerable attention in recent years as scaffolding material in tissue engineering and regenerative medicine. Chitosan is especially attractive as a bone scaffold material because it supports the attachment and proliferation of osteoblast cells as well as formation of mineralized bone matrix. In this review, we discuss the fundamentals of bone tissue engineering and the unique properties of chitosan as a scaffolding material to treat bone defects for hard tissue regeneration. We present the common methods for fabrication and characterization of chitosan scaffolds, and discuss the influence of material preparation and addition of polymeric or ceramic components or biomolecules on chitosan scaffold properties such as mechanical strength, structural integrity, and functional bone regeneration. Finally, we highlight recent advances in development of chitosan-based scaffolds with enhanced bone regeneration capability. PMID:24999429

  17. Indirect additive manufacturing as an elegant tool for the production of self-supporting low density gelatin scaffolds.

    PubMed

    Van Hoorick, Jasper; Declercq, Heidi; De Muynck, Amelie; Houben, Annemie; Van Hoorebeke, Luc; Cornelissen, Ria; Van Erps, Jrgen; Thienpont, Hugo; Dubruel, Peter; Van Vlierberghe, Sandra

    2015-10-01

    The present work describes for the first time the production of self-supporting low gelatin density (<10w/v%) porous scaffolds using methacrylamide-modified gelatin as an extracellular matrix mimicking component. As porous scaffolds starting from low gelatin concentrations cannot be realized with the conventional additive manufacturing techniquesin the abscence of additives, we applied an indirect fused deposition modelling approach. To realize this, we have printed a sacrificial polyester scaffold which supported the hydrogel material during UV crosslinking, thereby preventing hydrogel structure collapse. After complete curing, the polyester scaffold was selectively dissolved leaving behind a porous, interconnective low density gelatin scaffold. Scaffold structural analysis indicated the success of the selected indirect additive manufacturing approach. Physico-chemical testing revealed scaffold properties (mechanical, degradation, swelling) to depend on the applied gelatin concentration and methacrylamide content. Preliminary biocompatibility studies revealed the cell-interactive and biocompatible properties of the materials developed. PMID:26411443

  18. Hierarchical Structure and Mechanical Improvement of an n-HA/GCO-PU Composite Scaffold for Bone Regeneration.

    PubMed

    Li, Limei; Zuo, Yi; Zou, Qin; Yang, Boyuan; Lin, Lili; Li, Jidong; Li, Yubao

    2015-10-14

    To improve the mechanical properties of bone tissue and achieve the desired bone tissue regeneration for orthopedic surgery, newly designed hydroxyapatite/polyurethane (HA/PU) porous scaffolds were developed via in situ polymerization. The results showed that the molecular modification of PU soft segments by glyceride of castor oil (GCO) can increase the scaffold compressive strength by 48% and the elastic modulus by 96%. When nano-HA (n-HA) particles were incorporated into the GCO-PU matrix, the compressive strength and elastic modulus further increased by 49 and 74%, from 2.91 to 4.34 MPa and from 95 to 165.36 MPa, respectively. The n-HA particles with fine dispersity not only improved the interface bonding with the GCO-PU matrix but also provided effective bioactivity for bonding with bone tissue. The hierarchical structure and mechanical quality of the n-HA/GCO-PU composite scaffold were determined to be appropriate for the growth of cells and the regeneration of bony tissues, demonstrating promising prospects for bone repair and regeneration. PMID:26406396

  19. Electrospun poly(d/l-lactide-co-l-lactide) hybrid matrix: a novel scaffold material for soft tissue engineering

    PubMed Central

    Kluger, Petra J.; Wyrwa, Ralf; Weisser, Jrgen; Maierle, Julia; Votteler, Miriam; Rode, Claudia; Schnabelrauch, Matthias; Walles, Heike

    2010-01-01

    Electrospinning is a long-known polymer processing technique that has received more interest and attention in recent years due to its versatility and potential use in the field of biomedical research. The fabrication of three-dimensional (3D) electrospun matrices for drug delivery and tissue engineering is of particular interest. In the present study, we identified optimal conditions to generate novel electrospun polymeric scaffolds composed of poly-d/l-lactide and poly-l-lactide in the ratio 50:50. Scanning electron microscopic analyses revealed that the generated poly(d/l-lactide-co-l-lactide) electrospun hybrid microfibers possessed a unique porous high surface area mimicking native extracellular matrix (ECM). To assess cytocompatibility, we isolated dermal fibroblasts from human skin biopsies. After 5days of in vitro culture, the fibroblasts adhered, migrated and proliferated on the newly created 3D scaffolds. Our data demonstrate the applicability of electrospun poly(d/l-lactide-co-l-lactide) scaffolds to serve as substrates for regenerative medicine applications with special focus on skin tissue engineering. PMID:20640490

  20. Mechanical reliability of porous low-k dielectrics for advanced interconnect: Study of the instability mechanisms in porous low-k dielectrics and their mediation through inert plasma induced re-polymerization of the backbone structure

    NASA Astrophysics Data System (ADS)

    Sa, Yoonki

    Continuous scaling down of critical dimensions in interconnect structures requires the use of ultralow dielectric constant (k) films as interlayer dielectrics to reduce resistance-capacitance delays. Porous carbon-doped silicon oxide (p-SiCOH) dielectrics have been the leading approach to produce these ultralow-k materials. However, embedding of porosity into dielectric layer necessarily decreases the mechanical reliability and increases its susceptibility to adsorption of potentially deleterious chemical species during device fabrication process. Among those, exposure of porous-SiCOH low-k (PLK) dielectrics to oxidizing plasma environment causes the increase in dielectric constant and their vulnerability to mechanical instability of PLKs due to the loss of methyl species and increase in moisture uptake. These changes in PLK properties and physical stability have been persisting challenges for next-generation interconnects because they are the sources of failure in interconnect integration as well as functional and physical failures appearing later in IC device manufacturing. It is therefore essential to study the fundamentals of the interactions on p-SiCOH matrix induced by plasma exposure and find an effective and easy-to-implement way to reverse such changes by repairing damage in PLK structure. From these perspectives, the present dissertation proposes 1) a fundamental understanding of structural transformation occurring during oxidative plasma exposure in PLK matrix structure and 2) its restoration by using silylating treatment, soft x-ray and inert Ar-plasma radiation, respectively. Equally important, 3) as an alternative way of increasing the thermo-mechanical reliability, PLK dielectric film with an intrinsically robust structure by controlling pore morphology is fabricated and investigated. Based on the investigations, stability of PLK films studied by time-dependent ball indentation tester under the elevated temperature, variation in film thickness and dielectric constant, shows striking difference with small change in the chemical bond structure. Comparison of peak extracted by using FTIR (Fourier transform infrared spectroscopy) reveals that viscoplastic deformation and dielectric constant change correctly reflect the evolution in morphological structure of Si-O-Si peak. It is also found that hydrophilic nature of PLK matrix induced by silanol group is more involved with viscoplastic deformation rate and cage-like crosslinking in Si-O-Si peak is responsible for dielectric constant change. However, the level of instability driven by plasma exposure in PLK matrix is found to recover and desired mechanical and electrical properties are obtained by modifying the chemical bond configuration. Silylation process by HMDS (hexamethyldisilazane) works on recovery of hydrophobicity because it replenishes -C while removing -OH bonds. Contact angle is restored by controlling process temperature, however, the silylating agent cannot penetrate deep into PLK matrix without an adequate medium such as supercritical CO2, making it difficult to implement. As a way of overcoming the limitation of UV cure, soft x-ray cure with Al Kalpha target is applied to induce gentle reconfiguration of chemical bond. It is possible to break bond links selectively by controlling x-ray energy level and also reduce thermal curing temperature due to the increased penetration depth. As a result of soft x-ray cure, film thickness loss almost not occurred. However, influence of x-ray radiation on the moisture removal is limited. Basically, oxidative plasma damage appears in two extensive areas. The first is the loss of -C from PLK matrix, and the second is the increase in hydrophilic nature involved with the formation of Si-OH terminal bonds and H2O. Both alternations cause the dielectric constant to degrade because of increased density and/or loss of free volume, but the second causes PLK to lose thermal and mechanical stability because Si-OH and H2O act as catalysts for reactions that break the cross-linked backbone. Clearly, both changes in PLK chemistry and bond structure must be addressed in order for any repair method to be favorable. For this reason, Ar plasma treatment with low energy ions is employed to repair the plasma induced damage by creating the desired changes in the film matrix without a significant loss of other properties. Our approach of using inert plasma as a way for damage recovery is motivated by the realization that there is no possibility of chemical reaction with any organic species, driving the energy transfer only from the plasma species towards the respective film matrix. As results, after applying Ar plasma beam treatment followed by annealing on damaged PLK films, the resistance against thermal instability and viscoplastic deformation is found to be improved. Ball indentation depth of the films with Ar plasma process is drastically reduced at the identical condition. More noticeable is the fact that such alternation is converted towards a dehydration reaction under hydrostatic thermal pressure, which causes dielectric constant to decrease and films shrinkage to restore during reconstruction of polymer chains. It is suggested that the immediate event of an Ar plasma beam radiation is to deposit energy from the plasma species (ions, electrons) and this energy input produces the excited state species because Ar cannot chemically react with the film matrix. As a consequence, the radical sites are generated at the less stable area such as colony boundary or pore surface with the decay of the excited species, leading to the production of free radicals by an energy transfer to the bonds which are to be broken. Then, the activated sites experience chemical bond rearrangement by chain-scission, branching, or cross-linking. In our case, crosslink with C is involved with silylmethylene (Si-(CH 2)x-Si) groups and it is turned out that some of these groups are converted to methyl groups terminally bonded to siloxane backbone structure under 300˜400°C by reaction with -OH, and simultaneously creating a new Si-O-Si crosslink. As an alternative way of increasing the thermo-mechanical reliability, PLK dielectric film with an intrinsically robust structure by controlling pore morphology is fabricated. Since pore surface is susceptible to be damaged by BEOL integration damage, pore morphology in terms of size, distribution, and connectivity should be controlled in order to increase the robustness of PLK dielectrics. Generally, pores in PLK matrix are created by depositing organic fragment (called 'porogen') into the film and removed later by thermal and electron beam cure to form porous PLK layer (; Subtractive deposition). However, during the curing Si-O-Si backbone crosslink is broken and pores are easily interconnected, leading to vulnerable structure to the extrinsic damage. Constitutive deposition approach is feasible for the introduction of smaller nano-pores with little or no interconnectivity by steric hindrance. Due to the closed pore system, thermally-induced stress and plasma-induced damage is restricted merely to the surface of the dielectric film. This is attributed to the stable siloxane (Si-O-Si) backbone and the terminally bonded methyl group attached to silicon (Si-CH3), inducing steric hindrance that lowers the density of the films. The low dielectric constant and mechanical stability are closely involved with the formation of the Si-O-Si cage-like structure and an appropriate combination of stable Si-O-Si, Si-CH3 groups. Based on the FTIR and XPS spectra, it is concluded that the formation of the Si-O-Si cage-like structure was enhanced by structural method. It is believed that all these changes are beneficial for improving PLK stability as will be detailed in this dissertation. Especially, the originality and particular advantage of this study regarding plasma-induced damage repair will be highlighted.

  1. Porosity and Cell Preseeding Influence Electrospun Scaffold Maturation and Meniscus Integration In Vitro

    PubMed Central

    Ionescu, Lara C.

    2013-01-01

    Electrospinning generates fibrous scaffolds ideal for engineering soft orthopedic tissues. By modifying the electrospinning process, scaffolds with different structural organization and content can be generated. For example, fibers can be aligned in a single direction, or the porosity of the scaffold can be modified through the use of multi-jet electrospinning and the removal of sacrificial fibers. In this work, we investigated the role of fiber alignment and scaffold porosity on construct maturation and integration within in vitro meniscus defects. Further, we explored the effect of preseeding expanded meniscus fibrochondrocytes (MFCs) onto the scaffold at a high density before in vitro repair. Our results demonstrate that highly porous electropun scaffolds integrate better with a native tissue and mature to a greater extent than low-porosity scaffolds, while scaffold alignment does not influence integration or maturation. The addition o