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Sample records for aligned fiber scaffolds

  1. Aligned and Electrospun Piezoelectric Polymer Fiber Assembly and Scaffold

    NASA Technical Reports Server (NTRS)

    Scott-Carnell, Lisa A. (Inventor); Siochi, Emilie J. (Inventor); Holloway, Nancy M. (Inventor); Leong, Kam W. (Inventor); Kulangara, Karina (Inventor)

    2015-01-01

    A scaffold assembly and related methods of manufacturing and/or using the scaffold for stem cell culture and tissue engineering applications are disclosed which at least partially mimic a native biological environment by providing biochemical, topographical, mechanical and electrical cues by using an electroactive material. The assembly includes at least one layer of substantially aligned, electrospun polymer fiber having an operative connection for individual voltage application. A method of cell tissue engineering and/or stem cell differentiation uses the assembly seeded with a sample of cells suspended in cell culture media, incubates and applies voltage to one or more layers, and thus produces cells and/or a tissue construct. In another aspect, the invention provides a method of manufacturing the assembly including the steps of providing a first pre-electroded substrate surface; electrospinning a first substantially aligned polymer fiber layer onto the first surface; providing a second pre-electroded substrate surface; electrospinning a second substantially aligned polymer fiber layer onto the second surface; and, retaining together the layered surfaces with a clamp and/or an adhesive compound.

  2. Image-based quantification of fiber alignment within electrospun tissue engineering scaffolds is related to mechanical anisotropy.

    PubMed

    Fee, Timothy; Downs, Crawford; Eberhardt, Alan; Zhou, Yong; Berry, Joel

    2016-07-01

    It is well documented that electrospun tissue engineering scaffolds can be fabricated with variable degrees of fiber alignment to produce scaffolds with anisotropic mechanical properties. Several attempts have been made to quantify the degree of fiber alignment within an electrospun scaffold using image-based methods. However, these methods are limited by the inability to produce a quantitative measure of alignment that can be used to make comparisons across publications. Therefore, we have developed a new approach to quantifying the alignment present within a scaffold from scanning electron microscopic (SEM) images. The alignment is determined by using the Sobel approximation of the image gradient to determine the distribution of gradient angles with an image. This data was fit to a Von Mises distribution to find the dispersion parameter κ, which was used as a quantitative measure of fiber alignment. We fabricated four groups of electrospun polycaprolactone (PCL) + Gelatin scaffolds with alignments ranging from κ = 1.9 (aligned) to κ = 0.25 (random) and tested our alignment quantification method on these scaffolds. It was found that our alignment quantification method could distinguish between scaffolds of different alignments more accurately than two other published methods. Additionally, the alignment parameter κ was found to be a good predictor the mechanical anisotropy of our electrospun scaffolds. The ability to quantify fiber alignment within and make direct comparisons of scaffold fiber alignment across publications can reduce ambiguity between published results where cells are cultured on "highly aligned" fibrous scaffolds. This could have important implications for characterizing mechanics and cellular behavior on aligned tissue engineering scaffolds. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1680-1686, 2016.

  3. Alignment of collagen fiber in knitted silk scaffold for functional massive rotator cuff repair.

    PubMed

    Zheng, Zefeng; Ran, Jisheng; Chen, Weishan; Hu, Yejun; Zhu, Ting; Chen, Xiao; Yin, Zi; Heng, Boon Chin; Feng, Gang; Le, Huihui; Tang, Chenqi; Huang, Jiayun; Chen, Yangwu; Zhou, Yiting; Dominique, Pioletti; Shen, Weiliang; Ouyang, Hong-Wei

    2017-03-15

    Rotator cuff tear is one of the most common types of shoulder injuries, often resulting in pain and physical debilitation. Allogeneic tendon-derived decellularized matrices do not have appropriate pore size and porosity to facilitate cell infiltration, while commercially-available synthetic scaffolds are often inadequate at inducing tenogenic differentiation. The aim of this study is to develop an advanced 3D aligned collagen/silk scaffold (ACS) and investigate its efficacy in a rabbit massive rotator cuff tear model. ACS has similar 3D alignment of collagen fibers as natural tendon with superior mechanical characteristics. Based on ectopic transplantation studies, the optimal collagen concentration (10mg/ml), pore diameter (108.43±7.25μm) and porosity (97.94±0.08%) required for sustaining a stable macro-structure conducive for cellular infiltration was determined. Within in vitro culture, tendon stem/progenitor cells (TSPCs) displayed spindle-shaped morphology, and were well-aligned on ACS as early as 24h. TSPCs formed intercellular contacts and deposited extracellular matrix after 7days. With the in vivo rotator cuff repair model, the regenerative tendon of the ACS group displayed more conspicuous native microstructures with larger diameter collagen fibrils (48.72±3.75 vs. 44.26±5.03nm) that had better alignment and mechanical properties (139.85±49.36vs. 99.09±33.98N) at 12weeks post-implantation. In conclusion, these findings demonstrate the positive efficacy of the macroporous 3D aligned scaffold in facilitating rotator cuff tendon regeneration, and its practical applications for rotator cuff tendon tissue engineering.

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

    PubMed

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

    2015-04-01

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

  5. The preparation and characterization of highly aligned poly(epsilon-caprolactone)/poly ethylene oxide/chitosan ultrafine fiber for the application to tissue scaffold.

    PubMed

    Nien, Yu-Hsun; Wang, Jia-Yi; Tsai, Yan-Sheng

    2013-07-01

    The purpose of this study was to fabricate poly(epsilon-caprolactone) (PCL)/poly ethylene oxid (PEO)/chitosan (CS) ultrafine fiber in both aligned and random structures using electrospinning technique and their process parameters were optimized. The aligned and random PCL/PEO/chitosan ultrafine fibers were also used as scaffold for tissue engineering and their cell affinity was investigated. In the first part, we inspected the effect of environment conditions, solution properties, process parameters on PCL/PEO/chitosan ultrafine fiber. In the second part, the apparatus of electrospinning to manufacture highly aligned PCL/PEO/chitosan ultrafine fiber was developed. The effects of process parameters such as flow rate, design of collector and rotation speed of collecting drum on the morphology of ultrafine fiber were discussed. In addition, the cross link of PCL/PEO/chitosan ultrafine fiber by cross-linking agent was examined, too. The physical properties, chemical properties, and cell affinities of the aligned PCL/PEO/chitosan ultrafine fiber with or without cross link were measured. The chemical analysis and tensile strength of the ultrafine fiber were characterized using Fourier Transfer Infared Spectrophotometer and Universal Tensile Machine, respectively. The results show that the aligned PCL/PEO/chitosan ultrafine fibrous mat had the capacity to induce cellular alignment and enhance cellular elongation.

  6. Thermally Drawn Fibers as Nerve Guidance Scaffolds

    PubMed Central

    Koppes, Ryan A.; Park, Seongjun; Hood, Tiffany; Jia, Xiaoting; Poorheravi, Negin Abdolrahim; Achyuta, Anilkumar Harapanahalli; Fink, Yoel; Anikeeva, Polina

    2016-01-01

    Synthetic neural scaffolds hold promise to eventually replace nerve autografts for tissue repair following peripheral nerve injury. Despite substantial evidence for the influence of scaffold geometry and dimensions on the rate of axonal growth, systematic evaluation of these parameters remains a challenge due to limitations in materials processing. We have employed fiber drawing to engineer a wide spectrum of polymer-based neural scaffolds with varied geometries and core sizes. Using isolated whole dorsal root ganglia as an in vitro model system we have identified key features enhancing nerve growth within these fiber scaffolds. Our approach enabled straightforward integration of microscopic topography at the scale of nerve fascicles within the scaffold cores, which led to accelerated Schwann cell migration, as well as neurite growth and alignment. Our findings indicate that fiber drawing provides a scalable and versatile strategy for producing nerve guidance channels capable of controlling direction and accelerating the rate of axonal growth. PMID:26717246

  7. Thermally drawn fibers as nerve guidance scaffolds.

    PubMed

    Koppes, Ryan A; Park, Seongjun; Hood, Tiffany; Jia, Xiaoting; Abdolrahim Poorheravi, Negin; Achyuta, Anilkumar Harapanahalli; Fink, Yoel; Anikeeva, Polina

    2016-03-01

    Synthetic neural scaffolds hold promise to eventually replace nerve autografts for tissue repair following peripheral nerve injury. Despite substantial evidence for the influence of scaffold geometry and dimensions on the rate of axonal growth, systematic evaluation of these parameters remains a challenge due to limitations in materials processing. We have employed fiber drawing to engineer a wide spectrum of polymer-based neural scaffolds with varied geometries and core sizes. Using isolated whole dorsal root ganglia as an in vitro model system we have identified key features enhancing nerve growth within these fiber scaffolds. Our approach enabled straightforward integration of microscopic topography at the scale of nerve fascicles within the scaffold cores, which led to accelerated Schwann cell migration, as well as neurite growth and alignment. Our findings indicate that fiber drawing provides a scalable and versatile strategy for producing nerve guidance channels capable of controlling direction and accelerating the rate of axonal growth.

  8. Nanofiber alignment of a small diameter elastic electrospun scaffold

    NASA Astrophysics Data System (ADS)

    Patel, Jignesh

    Cardiovascular disease is the leading cause of death in western countries with coronary heart disease making up 50% of these deaths. As a treatment option, tissue engineered grafts have great potential. Elastic scaffolds that mimic arterial extracellular matrix (ECM) may hold the key to creating viable vascular grafts. Electrospinning is a widely used scaffold fabrication technique to engineer tubular scaffolds. In this study, we investigated how the collector rotation speed altered the nanofiber alignment which may improve mechanical characteristics making the scaffold more suitable for arterial grafts. The scaffold was fabricated from a blend of PCL/Elastin. 2D Fast Fourier Transform (FFT) image processing tool and MatLab were used to quantitatively analyze nanofiber orientation at different collector speeds (13500 to 15500 rpm). Both Image J and MatLab showed graphical peaks indicating predominant fiber orientation angles. A collector speed of 15000 rpm was found to produce the best nanofiber alignment with narrow peaks at 90 and 270 degrees, and a relative amplitude of 200. This indicates a narrow distribution of circumferentially aligned nanofibers. Collector speeds below and above 15000 rpm caused a decrease in fiber alignment with a broader orientation distribution. Uniformity of fiber diameter was also measured. Of 600 measures from the 15000 rpm scaffolds, the fiber diameter range from 500 nm to 899 nm was most prevalent. This diameter range was slightly larger than native ECM which ranges from 50 nm to 500 nm. The second most prevalent diameter range had an average of 404 nm which is within the diameter range of collagen. This study concluded that with proper electrospinning technique and collector speed, it is possible to fabricate highly aligned small diameter elastic scaffolds. Image J 2D FFT results confirmed MatLab findings for the analyses of circumferentially aligned nanofibers. In addition, MatLab analyses simplified the FFT orientation data

  9. Fabrication of macromolecular gradients in aligned fiber scaffolds using a combination of in-line blending and air-gap electrospinning.

    PubMed

    Kishan, Alysha P; Robbins, Andrew B; Mohiuddin, Sahar F; Jiang, Mingliang; Moreno, Michael R; Cosgriff-Hernandez, Elizabeth M

    2016-12-22

    Although a variety of fabrication methods have been developed to generate electrospun meshes with gradient properties, no platform has yet to achieve fiber alignment in the direction of the gradient that mimics the native tendon-bone interface. In this study, we present a method combining in-line blending and air-gap electrospinning to address this limitation in the field. A custom collector with synced rotation permitted fiber collection with uniform mesh thickness and periodic copper wires were used to induce fiber alignment. Two poly(ester urethane ureas) with different hard segment contents (BPUR 50, BPUR 10) were used to generate compositional gradient meshes with and without fiber alignment. The compositional gradient across the length of the mesh was characterized using a fluorescent dye and the results indicated a continuous transition from the BPUR 50 to the BPUR 10. As expected, the fiber alignment of the gradient meshes induced a corresponding alignment of adherent cells in static culture. Tensile testing of the sectioned meshes confirmed a graded transition in mechanical properties and an increase in anisotropy with fiber alignment. Finite element modeling was utilized to illustrate the gradient mechanical properties across the full length of the mesh and lay the foundation for future computational development work. Overall, these results indicate that this electrospinning method permits the fabrication of macromolecular gradients in the direction of fiber alignment and demonstrate its potential for use in interfacial tissue engineering.

  10. Fiber alignment apparatus and method

    DOEpatents

    Kravitz, S.H.; Warren, M.E.; Snipes, M.B. Jr.; Armendariz, M.G.; Word, J.C. V

    1997-08-19

    A fiber alignment apparatus includes a micro-machined nickel spring that captures and locks arrays of single mode fibers into position. The design consists of a movable nickel leaf shaped spring and a fixed pocket where fibers are held. The fiber is slid between the spring and a fixed block, which tensions the spring. When the fiber reaches the pocket, it automatically falls into the pocket and is held by the pressure of the leaf spring. 8 figs.

  11. Fiber alignment apparatus and method

    DOEpatents

    Kravitz, Stanley H.; Warren, Mial Evans; Snipes, Jr., Morris Burton; Armendariz, Marcelino Guadalupe; Word, V., James Cole

    1997-01-01

    A fiber alignment apparatus includes a micro-machined nickel spring that captures and locks arrays of single mode fibers into position. The design consists of a movable nickel leaf shaped spring and a fixed pocket where fibers are held. The fiber is slid between the spring and a fixed block, which tensions the spring. When the fiber reaches the pocket, it automatically falls into the pocket and is held by the pressure of the leaf spring.

  12. Gradient fiber electrospinning of layered scaffolds using controlled transitions in fiber diameter.

    PubMed

    Grey, Casey P; Newton, Scott T; Bowlin, Gary L; Haas, Thomas W; Simpson, David G

    2013-07-01

    We characterize layered, delamination resistant, tissue engineering scaffolds produced by gradient electrospinning using computational fluid dynamics, measurements of fiber diameter with respect to dynamic changes in polymer concentration, SEM analysis, and materials testing. Gradient electrospinning delivers a continuously variable concentration of polymer to the electrospinning jet, resulting in scaffolds that exhibit controlled transitions in fiber diameter across the Z-axis. This makes it possible to produce scaffolds that exhibit very different fiber sizes and material properties on opposing surfaces while eliminating the boundary layers that lead to delamination failures. In materials testing bi-layered laminated electrospun scaffolds (layer 1 = <250 nm, layer 2 = 1000 nm diameter polycaprolactone fibers) exhibit ductile properties and undergo multiphasic failure. In contrast, scaffolds, produced by gradient electrospinning fabricated with fibers of this type on opposing surfaces fracture and fail as unified, and mechanically integrated, structures. Gradient electrospinning also eliminates the anisotropic strain properties observed in scaffolds composed of highly aligned fibers. In burst testing, scaffolds composed of aligned fibers produced using gradient electrospinning exhibit superior material properties with respect to scaffolds composed of random or aligned fibers produced from a single polymer concentration or as bi-layered, laminated structures.

  13. Coaxial electrospun aligned tussah silk fibroin nanostructured fiber scaffolds embedded with hydroxyapatite-tussah silk fibroin nanoparticles for bone tissue engineering.

    PubMed

    Shao, Weili; He, Jianxin; Sang, Feng; Ding, Bin; Chen, Li; Cui, Shizhong; Li, Kejing; Han, Qiming; Tan, Weilin

    2016-01-01

    The bone is a composite of inorganic and organic materials and possesses a complex hierarchical architecture consisting of mineralized fibrils formed by collagen molecules and coated with oriented hydroxyapatite. To regenerate bone tissue, it is necessary to provide a scaffold that mimics the architecture of the extracellular matrix in native bone. Here, we describe one such scaffold, a nanostructured composite with a core made of a composite of hydroxyapatite and tussah silk fibroin. The core is encased in a shell of tussah silk fibroin. The composite fibers were fabricated by coaxial electrospinning using green water solvent and were characterized using different techniques. In comparison to nanofibers of pure tussah silk, composite notably improved mechanical properties, with 90-fold and 2-fold higher initial modulus and breaking stress, respectively, obtained. Osteoblast-like MG-63 cells were cultivated on the composite to assess its suitability as a scaffold for bone tissue engineering. We found that the fiber scaffold supported cell adhesion and proliferation and functionally promoted alkaline phosphatase and mineral deposition relevant for biomineralization. In addition, the composite were more biocompatible than pure tussah silk fibroin or cover slip. Thus, the nanostructured composite has excellent biomimetic and mechanical properties and is a potential biocompatible scaffold for bone tissue engineering.

  14. Creation of highly aligned electrospun poly-L-lactic acid fibers for nerve regeneration applications

    NASA Astrophysics Data System (ADS)

    Wang, Han Bing; Mullins, Michael E.; Cregg, Jared M.; Hurtado, Andres; Oudega, Martin; Trombley, Matthew T.; Gilbert, Ryan J.

    2009-02-01

    Aligned, electrospun polymer fibers have shown considerable promise in directing regenerating axons in vitro and in vivo. However, in several studies, final electrospinning parameters are presented for producing aligned fiber scaffolds, and alignment where minimal fiber crossing occurs is not achieved. Highly aligned species are necessary for neural tissue engineering applications to ensure that axonal extension occurs through a regenerating environment efficiently. Axonal outgrowth on fibers that deviate from the natural axis of growth may delay axonal extension from one end of a scaffold to the other. Therefore, producing aligned fiber scaffolds with little fiber crossing is essential. In this study, the contributions of four electrospinning parameters (collection disk rotation speed, needle size, needle tip shape and syringe pump flow rate) were investigated thoroughly with the goal of finding parameters to obtain highly aligned electrospun fibers made from poly-L-lactic acid (PLLA). Using an 8 wt% PLLA solution in chloroform, a collection disk rotation speed of 1000 revolutions per minute (rpm), a 22 gauge, sharp-tip needle and a syringe pump rate of 2 ml h-1 produced highly aligned fiber (1.2-1.6 µm in diameter) scaffolds verified using a fast Fourier transform and a fiber alignment quantification technique. Additionally, the application of an insulating sheath around the needle tip improved the rate of fiber deposition (electrospinning efficiency). Optimized scaffolds were then evaluated in vitro using embryonic stage nine (E9) chick dorsal root ganglia (DRGs) and rat Schwann cells (SCs). To demonstrate the importance of creating highly aligned scaffolds to direct neurite outgrowth, scaffolds were created that contained crossing fibers. Neurites on these scaffolds were directed down the axis of the aligned fibers, but neurites also grew along the crossed fibers. At times, these crossed fibers even stopped further axonal extension. Highly aligned PLLA fibers

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

    PubMed

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

    2009-02-01

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

  16. Microcracks induce osteoblast alignment and maturation on hydroxyapatite scaffolds

    NASA Astrophysics Data System (ADS)

    Shu, Yutian

    Physiological bone tissue is a mineral/collagen composite with a hierarchical structure. The features in bone, such as mineral crystals, fibers, and pores can range from the nanometer to the centimeter in size. Currently available bone tissue scaffolds primarily address the chemical composition, pore size, and pore size distribution. While these design parameters are extensively investigated for mimicking bone function and inducing bone regeneration, little is known about microcracks, which is a prevalent feature found in fractured bone in vivo and associated with fracture healing and repair. Since the purpose of bone tissue engineering scaffold is to enhance bone regeneration, the coincidence of microcracks and bone densification should not be neglected but rather be considered as a potential parameter in bone tissue engineering scaffold design. The purpose of this study is to test the hypothesis that microcracks enhance bone healing. In vitro studies were designed to investigate the osteoblast (bone forming cells) response to microcracks in dense (94%) hydroxyapatite substrates. Microcracks were introduced using a well-established Vickers indentation technique. The results of our study showed that microcracks induced osteoblast alignment, enhanced osteoblast attachment and more rapid maturation. These findings may provide insight into fracture healing mechanism(s) as well as improve the design of bone tissue engineering orthopedic scaffolds for more rapid bone regeneration.

  17. Fabrication of a Highly Aligned Neural Scaffold via a Table Top Stereolithography 3D Printing and Electrospinning.

    PubMed

    Lee, Se-Jun; Nowicki, Margaret; Harris, Brent; Zhang, Lijie Grace

    2017-01-11

    Three-dimensional (3D) bioprinting is a rapidly emerging technique in the field of tissue engineering to fabricate extremely intricate and complex biomimetic scaffolds in the range of micrometers. Such customized 3D printed constructs can be used for the regeneration of complex tissues such as cartilage, vessels, and nerves. However, the 3D printing techniques often offer limited control over the resolution and compromised mechanical properties due to short selection of printable inks. To address these limitations, we combined stereolithography and electrospinning techniques to fabricate a novel 3D biomimetic neural scaffold with a tunable porous structure and embedded aligned fibers. By employing two different types of biofabrication methods, we successfully utilized both synthetic and natural materials with varying chemical composition as bioink to enhance biocompatibilities and mechanical properties of the scaffold. The resulting microfibers composed of polycaprolactone (PCL) polymer and PCL mixed with gelatin were embedded in 3D printed hydrogel scaffold. Our results showed that 3D printed scaffolds with electrospun fibers significantly improve neural stem cell adhesion when compared to those without the fibers. Furthermore, 3D scaffolds embedded with aligned fibers showed an enhancement in cell proliferation relative to bare control scaffolds. More importantly, confocal microscopy images illustrated that the scaffold with PCL/gelatin fibers greatly increased the average neurite length and directed neurite extension of primary cortical neurons along the fiber. The results of this study demonstrate the potential to create unique 3D neural tissue constructs by combining 3D bioprinting and electrospinning techniques.

  18. Electrospun PGS: PCL Microfibers Align Human Valvular Interstitial Cells and Provide Tunable Scaffold Anisotropy

    PubMed Central

    Masoumi, Nafiseh; Larson, Benjamin L.; Annabi, Nasim; Kharaziha, Mahshid; Zamanian, Behnam; Shapero, Kayle S.; Cubberley, Alexander T.; Camci-Unal, Gulden; Manning, Keefe. B.

    2014-01-01

    Tissue engineered heart valves (TEHV) could be useful in the repair of congenital or acquired valvular diseases due to their potential for growth and remodeling. The development of biomimetic scaffolds is a major challenge in heart valve tissue engineering. One of the most important structural characteristics of mature heart valve leaflets is their intrinsic anisotropy, which is derived from the microstructure of aligned collagen fibers in the extracellular matrix (ECM). In the present study, we used a directional electrospinning technique to fabricate fibrous poly-(glycerol sebacate):poly(caprolactone) (PGS:PCL) scaffolds containing aligned fibers, which resembled native heart valve leaflet ECM networks. In addition, the anisotropic mechanical characteristics of fabricated scaffolds were tuned by changing the ratio of PGS:PCL to mimic the native heart valve’s mechanical properties. Primary human valvular interstitial cells (VICs) attached and aligned along the anisotropic axes of all PGS:PCL scaffolds with various mechanical properties. The cells were also biochemically active in producing heart valve-associated collagen, vimentin, and smooth muscle actin as determined by gene expression. The fibrous PGS:PCL scaffolds seeded with human VICs mimicked the structure and mechanical properties of native valve leaflet tissues and would potentially be suitable for the replacement of heart valves in diverse patient populations. PMID:24453182

  19. Fabrication of Aligned Nanofiber Polymer Yarn Networks for Anisotropic Soft Tissue Scaffolds.

    PubMed

    Wu, Shaohua; Duan, Bin; Liu, Penghong; Zhang, Caidan; Qin, Xiaohong; Butcher, Jonathan T

    2016-07-06

    Nanofibrous scaffolds with defined architectures and anisotropic mechanical properties are attractive for many tissue engineering and regenerative medicine applications. Here, a novel electrospinning system is developed and implemented to fabricate continuous processable uniaxially aligned nanofiber yarns (UANY). UANY were processed into fibrous tissue scaffolds with defined anisotropic material properties using various textile-forming technologies, i.e., braiding, weaving, and knitting techniques. UANY braiding dramatically increased overall stiffness and strength compared to the same number of UANY unbraided. Human adipose derived stem cells (HADSC) cultured on UANY or woven and knitted 3D scaffolds aligned along local fiber direction and were >90% viable throughout 21 days. Importantly, UANY supported biochemical induction of HADSC differentiation toward smooth muscle and osteogenic lineages. Moreover, we integrated an anisotropic woven fiber mesh within a bioactive hydrogel to mimic the complex microstructure and mechanical behavior of valve tissues. Human aortic valve interstitial cells (HAVIC) and human aortic root smooth muscle cells (HASMC) were separately encapsulated within hydrogel/woven fabric composite scaffolds for generating scaffolds with anisotropic biomechanics and valve ECM like microenvironment for heart valve tissue engineering. UANY have great potential as building blocks for generating fiber-shaped tissues or tissue microstructures with complex architectures.

  20. Coiled fiber scaffolds embedded with gold nanoparticles improve the performance of engineered cardiac tissues

    NASA Astrophysics Data System (ADS)

    Fleischer, Sharon; Shevach, Michal; Feiner, Ron; Dvir, Tal

    2014-07-01

    Coiled perimysial fibers within the heart muscle provide it with the ability to contract and relax efficiently. Here, we report on a new nanocomposite scaffold for cardiac tissue engineering, integrating coiled electrospun fibers with gold nanoparticles. Cultivation of cardiac cells within the hybrid scaffolds promoted cell organization into elongated and aligned tissues generating a strong contraction force, high contraction rate and low excitation threshold.Coiled perimysial fibers within the heart muscle provide it with the ability to contract and relax efficiently. Here, we report on a new nanocomposite scaffold for cardiac tissue engineering, integrating coiled electrospun fibers with gold nanoparticles. Cultivation of cardiac cells within the hybrid scaffolds promoted cell organization into elongated and aligned tissues generating a strong contraction force, high contraction rate and low excitation threshold. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00300d

  1. Electrospinning of continuous aligned polymer fibers

    NASA Astrophysics Data System (ADS)

    Sundaray, Bibekananda; Subramanian, V.; Natarajan, T. S.; Xiang, Rong-Zheng; Chang, Chia-Cheng; Fann, Wun-Shain

    2004-02-01

    Electrospinning is a technique employed for preparing polymer fibers having diameters in the range of 10 μm-10 nm using high electrostatic field. In this letter, we report the formation of aligned polymer fibers, several centimeters in length, with separation between the fibers in the range of 5-100 μm. Achieving alignment is an important step toward the exploitation of these fibers in applications. We have employed about 4500 V and a separation distance of about 1-3 cm between the electrodes. Smaller distance between electrodes, we believe, provides better control on the formation of the fibers.

  2. A simple method for fabrication of electrospun fibers with controlled degree of alignment having potential for nerve regeneration applications.

    PubMed

    Vimal, Sunil Kumar; Ahamad, Nadim; Katti, Dhirendra S

    2016-06-01

    In peripheral nerve injuries where direct suturing of nerve endings is not feasible, nerve regeneration has been facilitated through the use of artificially aligned fibrous scaffolds that provide directional growth of neurons to bridge the gap. The degree of fiber alignment is crucial and can impact the directionality of cells in a fibrous scaffold. While there have been multiple approaches that have been used for controlling fiber alignment, however, they have been associated with a compromised control on other properties, such as diameter, morphology, curvature, and topology of fibers. Therefore, the present study demonstrates a modified electrospinning set-up, that enabled fabrication of electrospun fibers with controlled degree of alignment from non-aligned (NA), moderately aligned (MA, 75%) to highly aligned (HA, 95%) sub-micron fibers while keeping other physical properties unchanged. The results demonstrate that the aligned fibers (MA and HA) facilitated directional growth of human astrocytoma cells (U373), wherein the aspect ratio of cells was found to increase with an increase in degree of fibers alignment. In contrast to NA and MA fibers, the HA fibers showed improved contact guidance to U373 cells that was demonstrated by a significantly higher cell aspect ratio and nuclear aspect ratio. In conclusion, the present study demonstrated a modified electrospinning setup to fabricate differentially aligned fibrous scaffolds with the HA fibers showing potential for use in neural tissue engineering.

  3. Exploring the Potential of Starch/Polycaprolactone Aligned Magnetic Responsive Scaffolds for Tendon Regeneration.

    PubMed

    Gonçalves, Ana I; Rodrigues, Márcia T; Carvalho, Pedro P; Bañobre-López, Manuel; Paz, Elvira; Freitas, Paulo; Gomes, Manuela E

    2016-01-21

    The application of magnetic nanoparticles (MNPs) in tissue engineering (TE) approaches opens several new research possibilities in this field, enabling a new generation of multifunctional constructs for tissue regeneration. This study describes the development of sophisticated magnetic polymer scaffolds with aligned structural features aimed at applications in tendon tissue engineering (TTE). Tissue engineering magnetic scaffolds are prepared by incorporating iron oxide MNPs into a 3D structure of aligned SPCL (starch and polycaprolactone) fibers fabricated by rapid prototyping (RP) technology. The 3D architecture, composition, and magnetic properties are characterized. Furthermore, the effect of an externally applied magnetic field is investigated on the tenogenic differentiation of adipose stem cells (ASCs) cultured onto the developed magnetic scaffolds, demonstrating that ASCs undergo tenogenic differentiation synthesizing a Tenascin C and Collagen type I rich matrix under magneto-stimulation conditions. Finally, the developed magnetic scaffolds were implanted in an ectopic rat model, evidencing good biocompatibility and integration within the surrounding tissues. Together, these results suggest that the effect of the magnetic aligned scaffolds structure combined with magnetic stimulation has a significant potential to impact the field of tendon tissue engineering toward the development of more efficient regeneration therapies.

  4. Cell alignment induced by anisotropic electrospun fibrous scaffolds alone has limited effect on cardiomyocyte maturation

    PubMed Central

    Han, Jingjia; Wu, Qingling; Xia, Younan; Wagner, Mary B; Xu, Chunhui

    2016-01-01

    Enhancing the maturation of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) will facilitate their applications in disease modeling and drug discovery. Previous studies suggest that cell alignment could enhance hPSC-CM maturation; however, the robustness of this approach has not been well investigated. To this end, we examined if the anisotropic orientation of hPSC-CMs imposed by the underlying aligned fibers within a 3D microenvironment could improve the maturation of hPSC-CMs. Enriched hPSC-CMs were cultured for two weeks on Matrigel-coated anisotropic (aligned) and isotropic (random) polycaprolactone (PCL) fibrous scaffolds, as well as tissue culture polystyrenes (TCPs) as a control. As expected, hPSC-CMs grown on the two types of fibrous scaffolds exhibited anisotropic and isotropic orientations, respectively. Similar to cells on TCPs, hPSC-CMs cultured on these scaffolds expressed CM-associated proteins and were pharmacologically responsive to adrenergic receptor agonists, a muscarinic agonist, and a gap junction uncoupler in a dose-dependent manner. Although hPSC-CMs grown on anisotropic fibrous scaffolds displayed the highest expression of genes encoding a number of sarcomere proteins, calcium handling proteins and ion channels, their calcium transient kinetics were slower than cells grown on TCPs. These results suggest that electrospun anisotropic fibrous scaffolds, as a single method, have limited effect on improving the maturation of hPSC-CMs. PMID:27131761

  5. Fiber optics welder having movable aligning mirror

    DOEpatents

    Higgins, Robert W.; Robichaud, Roger E.

    1981-01-01

    A system for welding fiber optic waveguides together. The ends of the two fibers to be joined together are accurately, collinearly aligned in a vertical orientation and subjected to a controlled, diffuse arc to effect welding and thermal conditioning. A front-surfaced mirror mounted at a 45.degree. angle to the optical axis of a stereomicroscope mounted for viewing the junction of the ends provides two orthogonal views of the interface during the alignment operation.

  6. Patterned silk film scaffolds for aligned lamellar bone tissue engineering

    PubMed Central

    Tien, Lee W.; Gil, Eun Seok; Park, Sang-Hyug; Mandal, Biman B.; Kaplan, David L.

    2013-01-01

    Various porous biomaterial scaffolds have been utilized for bone tissue engineering; however, they are often limited in their ability to replicate the structural hierarchy and mechanics of native cortical bone. In this study, the alignment and osteogenic differentiation of human mesenchymal stem cells (MSCs) on patterned silk films (PF) was investigated as a bottom-up, biomimetic approach toward engineering cortical bone lamellae. Screening films cast with nine different micro and nano scale groove patterns showed that cellular alignment was mediated by an interplay between the width and depth of the patterns. MSCs were differentiated in osteogenic medium for four weeks on the PF that induced the highest degree of alignment, while flat films (FF) served as controls. Gene expression analysis and calcium quantification indicated that the PF supported osteogenic differentiation while also inducing robust lamellar alignment of cells and matrix deposition. A secondary alignment effect was noted on the PF where a new layer of aligned cells grew over the first layer, but rotated obliquely to the underlying pattern direction and first layer orientation. This layering and rotation of the aligned MSCs resembled the characteristic structural organization observed in native lamellar bone. The ability to control multilayered lamellar structural hierarchy from the interplay between a patterned 2D surface and cells suggests intriguing options for future biomaterial scaffolds designed to mimic native tissue structures. PMID:23070941

  7. Anisotropic fiber alignment in composite structures

    DOEpatents

    Graham, Alan L.; Mondy, Lisa A.; Guell, David C.

    1993-01-01

    High strength material composite structures are formed with oriented fibers to provide controlled anisotropic fibers. Fibers suspended in non-dilute concentrations (e.g., up to 20 volume percent for fibers having an aspect ratio of 20) in a selected medium are oriented by moving an axially spaced array of elements in the direction of desired fiber alignment. The array elements are generally perpendicular to the desired orientation. The suspension medium may also include sphere-like particles where the resulting material is a ceramic.

  8. Electrospun fibrous scaffolds promote breast cancer cell alignment and epithelial-mesenchymal transition.

    PubMed

    Saha, Sharmistha; Duan, Xinrui; Wu, Laying; Lo, Pang-Kuo; Chen, Hexin; Wang, Qian

    2012-01-31

    In this work we created electrospun fibrous scaffolds with random and aligned fiber orientations in order to mimic the three-dimensional structure of the natural extracellular matrix (ECM). The rigidity and topography of the ECM environment have been reported to alter cancer cell behavior. However, the complexity of the in vivo system makes it difficult to isolate and study such extracellular topographical cues that trigger cancer cells' response. Breast cancer cells were cultured on these fibrous scaffolds for 3-5 days. The cells showed elongated spindle-like morphology in the aligned fibers, whereas they maintained a mostly flat stellar shape in the random fibers. Gene expression profiling of these cells post seeding showed up-regulation of transforming growth factor β-1 (TGFβ-1) along with other mesenchymal biomarkers, suggesting that these cells undergo epithelial-mesenchymal transitions in response to the polymer scaffold. The results of this study indicate that the topographical cue may play a significant role in tumor progression.

  9. Scale-dependent fiber kinematics of elastomeric electrospun scaffolds for soft tissue engineering

    PubMed Central

    Stella, John A.; Wagner, William R.; Sacks, Michael S.

    2013-01-01

    Electrospun poly(ester urethane)urea (PEUU) scaffolds contain complex multiscale hierarchical structures that work simultaneously to produce unique macrolevel mechanical behaviors. In this study, we focused on quantifying key multiscale scaffold structural features to elucidate the mechanisms by which these scaffolds function to emulate native tissue tensile behavior. Fiber alignment was modulated via increasing rotational velocity of the collecting mandrel, and the resultant specimens were imaged using SEM under controlled biaxial strain. From the SEM images, fiber splay, tortuosity, and diameter were quantified in the unstrained and deformed configurations. Results indicated that not only fiber alignment increased with mandrel velocity but also, paradoxically, tortuosity increased concurrently with mandrel velocity and was highly correlated with fiber orientation. At microlevel scales (1–10 μm), local scaffold deformation behavior was observed to be highly heterogeneous, while increasing the scale resulted in an increasingly homogenous strain field. From our comprehensive measurements, we determined that the transition scale from heterogenous to homogeneous-like behavior to be ~1 mm. Moreover, while electrospun PEUU scaffolds exhibit complex deformations at the microscale, the larger scale structural features of the fibrous network allow them to behave as long-fiber composites that deform in an affine-like manner. This study underscores the importance of understanding the structure–function relationships in elastomeric fibrous scaffolds, and in particular allowed us to link microscale deformations with mechanisms that allow them to successfully simulate soft tissue mechanical behavior. PMID:19753623

  10. Bicomponent electrospinning to fabricate three-dimensional hydrogel-hybrid nanofibrous scaffolds with spatial fiber tortuosity.

    PubMed

    Jin, Gyuhyung; Lee, Slgirim; Kim, Seung-Hyun; Kim, Minhee; Jang, Jae-Hyung

    2014-12-01

    Electrospun fibrous mats have emerged as powerful tissue engineering scaffolds capable of providing highly effective and versatile physical guidance, mimicking the extracellular environment. However, electrospinning typically produces a sheet-like structure, which is a major limitation associated with current electrospinning technologies. To address this challenge, highly porous, volumetric hydrogel-hybrid fibrous scaffolds were fabricated by one Taylor cone-based side-by-side dual electrospinning of poly (ε-caprolactone) (PCL) and poly (vinyl pyrrolidone) (PVP), which possess distinct properties (i.e., hydrophobic and hydrogel properties, respectively). Immersion of the resulting scaffolds in water induced spatial tortuosity of the hydrogel PVP fibers while maintaining their aligned fibrous structures in parallel with the PCL fibers. The resulting conformational changes in the entire bicomponent fibers upon immersion in water led to volumetric expansion of the fibrous scaffolds. The spatial fiber tortuosity significantly increased the pore volumes of electrospun fibrous mats and dramatically promoted cellular infiltration into the scaffold interior both in vitro and in vivo. Harmonizing the flexible PCL fibers with the soft PVP-hydrogel layers produced highly ductile fibrous structures that could mechanically resist cellular contractile forces upon in vivo implantation. This facile dual electrospinning followed by the spatial fiber tortuosity for fabricating three-dimensional hydrogel-hybrid fibrous scaffolds will extend the use of electrospun fibers toward various tissue engineering applications.

  11. Biomimetic Scaffold with Aligned Microporosity Designed for Dentin Regeneration

    PubMed Central

    Panseri, Silvia; Montesi, Monica; Dozio, Samuele Maria; Savini, Elisa; Tampieri, Anna; Sandri, Monica

    2016-01-01

    Tooth loss is a common result of a variety of oral diseases due to physiological causes, trauma, genetic disorders, and aging and can lead to physical and mental suffering that markedly lowers the individual’s quality of life. Tooth is a complex organ that is composed of mineralized tissues and soft connective tissues. Dentin is the most voluminous tissue of the tooth and its formation (dentinogenesis) is a highly regulated process displaying several similarities with osteogenesis. In this study, gelatin, thermally denatured collagen, was used as a promising low-cost material to develop scaffolds for hard tissue engineering. We synthetized dentin-like scaffolds using gelatin biomineralized with magnesium-doped hydroxyapatite and blended it with alginate. With a controlled freeze-drying process and alginate cross-linking, it is possible to obtain scaffolds with microscopic aligned channels suitable for tissue engineering. 3D cell culture with mesenchymal stem cells showed the promising properties of the new scaffolds for tooth regeneration. In detail, the chemical–physical features of the scaffolds, mimicking those of natural tissue, facilitate the cell adhesion, and the porosity is suitable for long-term cell colonization and fine cell–material interactions. PMID:27376060

  12. Cellulose nanowhiskers and fiber alignment greatly improve mechanical properties of electrospun prolamin protein fibers.

    PubMed

    Wang, Yixiang; Chen, Lingyun

    2014-02-12

    Electrospun fibers from natural polymers must possess appropriate mechanical properties if they are to be functional in numerous applications. In this research, two convenient physical approaches were applied to reinforce the assembled hordein/zein electrospun nanofabrics: incorporation of surface-modified cellulose nanowhiskers (SCN) and fiber alignment. The mechanical properties and stability of the modified fibers were tested in relation to fiber morphology and structure as characterized by scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy. SCN modified by quaternary ammonium salt were well-dispersed in hordein/zein networks, leading to fibers with significantly improved mechanical properties and water resistance. With the addition of 3 wt % SCN, the tensile strength and Young's modulus of hordein/zein fibers increased from 4.36 ± 0.29 to 7.79 ± 0.36 MPa and from 195.80 ± 13.02 to 396.64 ± 18.33 MPa, respectively, and the elongation at break was retained because of the formation of a percolating network of SCN. The alignment of electrospun fibers strengthened the hordein/zein nanofabrics in both tangential and normal directions to 17.26 ± 1.41 and 14.02 ± 0.74 MPa, respectively, by not only altering the piling up pattern, but also by promoting phase separation and improved interactions. When applying both of the reinforcing methods, the tensile strength of hordein/zein fibers was further enhanced to 21.99 ± 1.19 MPa, stronger than that of cancellous bones (5-10 MPa). All the reinforced fibers exhibited a reduced burst effect in phosphate-buffered saline (PBS) while releasing the incorporated bioactive molecule in a controlled manner. These physically reinforced prolamin protein fibers possessed significantly improved mechanical properties and may have potential to be used as tissue engineering scaffold materials or natural delivery systems for biomedical applications.

  13. Fiber angle and aspect ratio influence the shear mechanics of oriented electrospun nanofibrous scaffolds.

    PubMed

    Driscoll, Tristan P; Nerurkar, Nandan L; Jacobs, Nathan T; Elliott, Dawn M; Mauck, Robert L

    2011-11-01

    Fibrocartilages, including the knee meniscus and the annulus fibrosus (AF) of the intervertebral disc, play critical mechanical roles in load transmission across joints and their function is dependent upon well-defined structural hierarchies, organization, and composition. All, however, are compromised in the pathologic transformations associated with tissue degeneration. Tissue engineering strategies that address these key features, for example, aligned nanofibrous scaffolds seeded with mesenchymal stem cells (MSCs), represent a promising approach for the regeneration of these fibrous structures. While such engineered constructs can replicate native tissue structure and uniaxial tensile properties, the multidirectional loading encountered by these tissues in vivo necessitates that they function adequately in other loading modalities as well, including shear. As previous findings have shown that native tissue tensile and shear properties are dependent on fiber angle and sample aspect ratio, respectively, the objective of the present study was to evaluate the effects of a changing fiber angle and sample aspect ratio on the shear properties of aligned electrospun poly(ε-caprolactone) (PCL) scaffolds, and to determine how extracellular matrix deposition by resident MSCs modulates the measured shear response. Results show that fiber orientation and sample aspect ratio significantly influence the response of scaffolds in shear, and that measured shear strains can be predicted by finite element models. Furthermore, acellular PCL scaffolds possessed a relatively high shear modulus, 2-4 fold greater than native tissue, independent of fiber angle and aspect ratio. It was further noted that under testing conditions that engendered significant fiber stretch, the aggregate resistance to shear was higher, indicating a role for fiber stretch in the overall shear response. Finally, with time in culture, the shear modulus of MSC laden constructs increased, suggesting that

  14. Effect of Sterilization Methods on Electrospun Poly(lactic acid) (PLA) Fiber Alignment for Biomedical Applications.

    PubMed

    Valente, T A M; Silva, D M; Gomes, P S; Fernandes, M H; Santos, J D; Sencadas, V

    2016-02-10

    Medically approved sterility methods should be a major concern when developing a polymeric scaffold, mainly when commercialization is envisaged. In the present work, poly(lactic acid) (PLA) fiber membranes were processed by electrospinning with random and aligned fiber alignment and sterilized under UV, ethylene oxide (EO), and γ-radiation, the most common ones for clinical applications. It was observed that UV light and γ-radiation do not influence fiber morphology or alignment, while electrospun samples treated with EO lead to fiber orientation loss and morphology changing from cylindrical fibers to ribbon-like structures, accompanied to an increase of polymer crystallinity up to 28%. UV light and γ-radiation sterilization methods showed to be less harmful to polymer morphology, without significant changes in polymer thermal and mechanical properties, but a slight increase of polymer wettability was detected, especially for the samples treated with UV radiation. In vitro results indicate that both UV and γ-radiation treatments of PLA membranes allow the adhesion and proliferation of MG 63 osteoblastic cells in a close interaction with the fiber meshes and with a growth pattern highly sensitive to the underlying random or aligned fiber orientation. These results are suggestive of the potential of both γ-radiation sterilized PLA membranes for clinical applications in regenerative medicine, especially those where customized membrane morphology and fiber alignment is an important issue.

  15. Understanding and overcoming shear alignment of fibers during extrusion.

    PubMed

    Martin, Joshua J; Riederer, Michael S; Krebs, Melissa D; Erb, Randall M

    2015-01-14

    Fiber alignment is the defining architectural characteristic of discontinuous fiber composites and is dictated by shear-dominated processing techniques including flow-injection molding, tape-casting, and mold-casting. However, recent colloidal assembly techniques have started to employ additional forces in fiber suspensions that have the potential to change the energy landscape of the shear-dominated alignment in conditions of flow. In this paper, we develop an energetics model to characterize the shear-alignment of rigid fibers under different flow conditions in the presence of magnetic colloidal alignment forces. We find that these colloidal forces can be sufficient to manipulate the energetic landscape and obtain tunable fiber alignment during flow within even small geometries, such as capillary flow. In most conditions, these colloidal forces work to freeze the fiber orientation during flow and prevent the structure disrupting phenomenon of Jeffrey's orbits that has been accepted to rule fiber suspensions under simple shear flow.

  16. Novel scaffold design with multi-grooved PLA fibers.

    PubMed

    Chung, Sangwon; Gamcsik, Mike P; King, Martin W

    2011-08-01

    A novel prototype nonwoven textile structure containing polylactide (PLA) multigrooved fibers has been proposed as a possible scaffold material for superior cell attachment and proliferation. Grooved cross-sectional fibers with larger surface area were obtained by a bi-component spinning system and the complete removal of the sacrificial component was confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray photon spectroscopy (XPS) analysis. These PLA nonwoven scaffolds containing the grooved fibers exhibited enhanced wettability, greater flexibility and tensile properties, and a larger surface area compared to a traditional PLA nonwoven fabric containing round fibers. To evaluate cellular attachment on the two types of PLA nonwoven scaffolds, NIH 3T3 fibroblasts were cultured for up to 12 days. It was evident that the initial cellular attachment was superior on the scaffold with grooved fibers, which was confirmed by MTT viability assay (p < 0.01) and SEM analysis. In the future, by modulating the size of the grooves on the fibers, such a scaffold material with a large surface area could serve as an alternative matrix for culturing different types of cells.

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

    PubMed

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

    2013-02-01

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

  18. Preparation of hybrid scaffold from fibrin and biodegradable polymer fiber.

    PubMed

    Hokugo, Akishige; Takamoto, Tomoaki; Tabata, Yasuhiko

    2006-01-01

    A biodegradable hybrid scaffold was prepared from fibrin and poly(glycolic acid) (PGA) fiber. Mixed fibrinogen and thrombin solution homogeneously dispersed in the presence of various amounts (0, 1.5, 3.0, and 6.0mg) of PGA fiber was freeze-dried to obtain fibrin sponges with or without PGA fiber incorporation. By scanning electron microscopy observation, the fibrin sponges had an interconnected pore structure, irrespective of the amount of PGA fiber incorporated. PGA fiber incorporation enabled the fibrin sponges to significantly enhance their compression strength. In vitro cell culture studies revealed that the number of L929 fibroblasts initially attached was significantly larger for any fibrin sponge with PGA fiber incorporation than for the fibrin sponge without PGA fiber. The shrinkage of sponges after cell seeding was suppressed by fiber incorporation. It is possible that the shrinkage suppression of sponges maintains their intraspace, resulting in the superior cell attachment of a sponge with PGA fiber incorporation. After subcutaneous implantation into the backs of mice, the residual volume of a fibrin sponge with PGA fiber incorporation was significant compared with that of a fibrin sponge without PGA fiber. Larger number of cells infiltrated deep inside the fibrin sponges with PGA fiber incorporation implanted subcutaneously. It is concluded that the fibrin sponge reinforced by fiber incorporation is a promising three-dimensional scaffold of cells for tissue engineering.

  19. Improving the mechanical properties of chitosan-based heart valve scaffolds using chitosan fibers.

    PubMed

    Albanna, Mohammad Z; Bou-Akl, Therese H; Walters, Henry L; Matthew, Howard W T

    2012-01-01

    Chitosan is being widely studied for tissue engineering applications due to its biocompatibility and biodegradability. However, its use in load-bearing applications is limited due to low mechanical properties. In this study, we investigated the effectiveness of a chitosan fiber reinforcement approach to enhancing the mechanical properties of chitosan scaffolds. Chitosan fibers were fabricated using a solution extrusion and neutralization method and incorporated into porous chitosan scaffolds. The effects of fiber/scaffold mass ratio, fiber mechanical properties and fiber length on scaffold mechanical properties were studied. The results showed that incorporating fibers improved scaffold strength and stiffness in proportion to the fiber/scaffold mass ratio. A fiber-reinforced, heart valve scaffold achieved leaflet tensile strength values of 220±17 kPa, comparable to the radial values of human pulmonary valve leaflets. Additionally, the effects of 2 mm fibers were found to be up to threefold greater than 10 mm fibers at identical mass ratios. Heparin crosslinking of fibers produced a reduction in fiber strength, and thus failed to produce additional improvements to fiber-reinforced scaffold properties. Despite this reduction in fiber strength, heparin-modified fibers still improved the mechanical properties of reinforced scaffolds, but to a lesser extent than unmodified fibers. The results demonstrate that chitosan fiber reinforcement can be used to achieve porous chitosan scaffold strength approaching that of tissue, and that fiber length and mechanical properties are important parameters in defining the degree of mechanical improvement.

  20. Aligning carbon fibers in micro-extruded composite ink

    NASA Astrophysics Data System (ADS)

    Mahajan, Chaitanya G.

    Direct write processes include a wide range of additive manufacturing techniques with the ability to fabricate structures directly onto planar and non-planar surfaces. Most additive manufacturing techniques use unreinforced polymers to produce parts. By adding carbon fiber as a reinforcing material, properties such as mechanical strength, electrical conductivity, and thermal conductivity can be enhanced. Carbon fibers can be long and continuous, or short and discontinuous. The strength of carbon fiber composite parts is greatly increased when the fibers are preferentially aligned. This research focuses on increasing the strength of additively manufactured parts reinforced using discontinuous carbon fibers that have been aligned during the micro extrusion process. A design of experiments (DOE) approach was used to identify significant process parameters affecting fiber alignment. Factors such as the length of carbon fibers, nozzle diameter, fiber loading fraction, air pressure, translational speed and standoff distance were considered. A two dimensional Fast Fourier Transform (2D FFT) was used to quantify the degree of fiber alignment in the extruded composite inks. ImageJ software supported by an oval profile plugin was used with micrographs of printed samples to obtain the carbon fiber alignment values. The optimal value for the factors was derived by identifying the significant main and interaction effects. Based on the results of the DOE, tensile test samples were printed with fibers aligned parallel and perpendicular to the tensile axis. A standard test method for tensile properties of plastic revealed that the extruded parts with fibers aligned along the tensile axis were better in tensile strength and modulus.

  1. Micropatterning of nanocomposite polymer scaffolds using sacrificial phosphate glass fibers for tendon tissue engineering applications.

    PubMed

    Alshomer, Feras; Chaves, Camilo; Serra, Tiziano; Ahmed, Ifty; Kalaskar, Deepak M

    2017-01-20

    This study presents a simple and reproducible method of micropatterning the novel nanocomposite polymer (POSS-PCU) using a sacrificial phosphate glass fiber template for tendon tissue engineering applications. The diameters of the patterned scaffolds produced were dependent on the diameter of the glass fibers (15 μm) used. Scaffolds were tested for their physical properties and reproducibility using various microscopy techniques. For the first time, we show that POSS-PCU supports growth of human tenocytes cells. Furthermore, we show that cellular alignment, their biological function and expression of various tendon related proteins such as scleraxis, collagen I and III, tenascin-C are significantly elevated on the micropatterned polymer surfaces compared to flat samples. This study demonstrated a simple, reproducible method of micropatterning POSS-PCU nanocomposite polymer for novel tendon repair applications, which when provided with physical cues could help mimic the microenvironment of tenocytes cells.

  2. An ice-templated, linearly aligned chitosan-alginate scaffold for neural tissue engineering.

    PubMed

    Francis, Nicola L; Hunger, Philipp M; Donius, Amalie E; Riblett, Benjamin W; Zavaliangos, Antonios; Wegst, Ulrike G K; Wheatley, Margaret A

    2013-12-01

    Several strategies have been investigated to enhance axonal regeneration after spinal cord injury, however, the resulting growth can be random and disorganized. Bioengineered scaffolds provide a physical substrate for guidance of regenerating axons towards their targets, and can be produced by freeze casting. This technique involves the controlled directional solidification of an aqueous solution or suspension, resulting in a linearly aligned porous structure caused by ice templating. In this study, freeze casting was used to fabricate porous chitosan-alginate (C/A) scaffolds with longitudinally oriented channels. Chick dorsal root ganglia explants adhered to and extended neurites through the scaffold in parallel alignment with the channel direction. Surface adsorption of a polycation and laminin promoted significantly longer neurite growth than the uncoated scaffold (poly-L-ornithine + Laminin = 793.2 ± 187.2 μm; poly-L-lysine + Laminin = 768.7 ± 241.2 μm; uncoated scaffold = 22.52 ± 50.14 μm) (P < 0.001). The elastic modulus of the hydrated scaffold was determined to be 5.08 ± 0.61 kPa, comparable to reported spinal cord values. The present data suggested that this C/A scaffold is a promising candidate for use as a nerve guidance scaffold, because of its ability to support neuronal attachment and the linearly aligned growth of DRG neurites.

  3. Controlled release of 6-aminonicotinamide from aligned, electrospun fibers alters astrocyte metabolism and dorsal root ganglia neurite outgrowth

    NASA Astrophysics Data System (ADS)

    Schaub, Nicholas J.; Gilbert, Ryan J.

    2011-08-01

    Following central nervous system (CNS) injury, activated astrocytes form a glial scar that inhibits the migration of axons ultimately leading to regeneration failure. Biomaterials developed for CNS repair can provide local delivery of therapeutics and/or guidance mechanisms to encourage cell migration into damaged regions of the brain or spinal cord. Electrospun fibers are a promising type of biomaterial for CNS injury since these fibers can direct cellular and axonal migration while slowly delivering therapy to the injury site. In this study, it was hypothesized that inclusion of an anti-metabolite, 6-aminonicotinamide (6AN), within poly-l-lactic acid electrospun fibers could attenuate astrocyte metabolic activity while still directing axonal outgrowth. Electrospinning parameters were varied to produce highly aligned electrospun fibers that contained 10% or 20% (w/w) 6AN. 6AN release from the fiber substrates occurred continuously over 2 weeks. Astrocytes placed onto drug-releasing fibers were less active than those cultured on scaffolds without 6AN. Dorsal root ganglia placed onto control and drug-releasing scaffolds were able to direct neurites along the aligned fibers. However, neurite outgrowth was stunted by fibers that contained 20% 6AN. These results show that 6AN release from aligned, electrospun fibers can decrease astrocyte activity while still directing axonal outgrowth.

  4. Electrospinning of aligned fibers with adjustable orientation using auxiliary electrodes

    NASA Astrophysics Data System (ADS)

    Arras, Matthias M. L.; Grasl, Christian; Bergmeister, Helga; Schima, Heinrich

    2012-06-01

    A conventional electrospinning setup was upgraded by two turnable plate-like auxiliary high-voltage electrodes that allowed aligned fiber deposition in adjustable directions. Fiber morphology was analyzed by scanning electron microscopy and attenuated total reflection Fourier transform infrared spectroscopy (FTIR-ATR). The auxiliary electric field constrained the jet bending instability and the fiber deposition became controllable. At target speeds of 0.9 m s-1 90% of the fibers had aligned within 2°, whereas the angular spread was 70° without the use of auxiliary electrodes. It was even possible to orient fibers perpendicular to the rotational direction of the target. The fiber diameter became smaller and its distribution narrower, while according to the FTIR-ATR measurement the molecular orientation of the polymer was unaltered. This study comprehensively documents the feasibility of directed fiber deposition and offers an easy upgrade to existing electrospinning setups.

  5. Fabrication of alumina porous scaffolds with aligned oriented pores for bone tissue engineering applications

    NASA Astrophysics Data System (ADS)

    Sarhadi, Fatemeh; Shafiee Afarani, Mahdi; Mohebbi-Kalhori, Davod; Shayesteh, Masoud

    2016-04-01

    In the present study, porous alumina scaffolds with specific orientation and anisotropic properties are fabricated for application in bone tissue repair. The scaffolds with double shape pores, tubular oriented and isotropic rounded pores, were prepared using alumina and silica as starting materials by the slip casting route. Milled polyurethane foam and silk fibers were applied as replica materials as well. The effect of fiber types and diameter and number of fibers on the microstructure and pore size was studied. Moreover, different characteristics such as porosity, density, orientation, flexural strength and compressive strength of the samples were investigated. Results showed that various fibers with different diameters and numbers led to forming the pores with different pore sizes, microstructure and consequently changes in the physical and mechanical properties. In addition, the simultaneous presence of fibers and particles led to more porous scaffolds. The oriented tiny micro-tube and rounded pores were observed in all porous ceramic scaffolds. Mechanical testing showed an anisotropy in the mechanical behaviors such that higher strengths were observed in the oriented pore direction than that of transverse. With increasing the number and diameter of silk fibers, the scaffolds with a high porosity up to 68 vol% and proper flexural strength were obtained.

  6. Fast Fiber-Laser Alignment: Beam Spot-Size Method

    NASA Astrophysics Data System (ADS)

    Zhang, Rong; Guo, Jingyan; Shi, Frank G.

    2005-03-01

    A novel fast and cost-effective method is introduced for the active alignment of a fiber to a laser diode: only four easy laser beam spot-size measurements are required for moving the fiber tip from the far field to the proximity of the optimal alignment position, thus dramatically reducing the total alignment time (at least five times faster than a conventional method),as experimentally confirmed. Moreover, in contrast to the existing methods,the new method is failure-proof. The principle of the proposed method can be applied generally to any type of packages and is illustrated by an example of a butterfly package.

  7. Smooth Muscle Cell Alignment and Phenotype Control by Melt Spun Polycaprolactone Fibers for Seeding of Tissue Engineered Blood Vessels

    PubMed Central

    Agrawal, Animesh; Lee, Bae Hoon; Irvine, Scott A.; An, Jia; Bhuthalingam, Ramya; Singh, Vaishali; Low, Kok Yao; Chua, Chee Kai; Venkatraman, Subbu S.

    2015-01-01

    A method has been developed to induce and retain a contractile phenotype for vascular smooth muscle cells, as the first step towards the development of a biomimetic blood vessel construct with minimal compliance mismatch. Melt spun PCL fibers were deposited on a mandrel to form aligned fibers of 10 μm in diameter. The fibers were bonded into aligned arrangement through dip coating in chitosan solution. This formed a surface of parallel grooves, 10 μm deep by 10 μm across, presenting a surface layer of chitosan to promote cell surface interactions. The aligned fiber surface was used to culture cells present in the vascular wall, in particular fibroblasts and smooth muscle cells. This topography induced “surface guidance” over the orientation of the cells, which adopted an elongated spindle-like morphology, whereas cells on the unpatterned control surface did not show such orientation, assuming more rhomboid shapes. The preservation of VSMC contractile phenotype on the aligned scaffold was demonstrated by the retention of α-SMA expression after several days of culture. The effect was assessed on a prototype vascular graft prosthesis fabricated from polylactide caprolactone; VSMCs aligned longitudinally along a fiberless tube, whereas, for the aligned fiber coated tubes, the VSMCs aligned in the required circumferential orientation. PMID:26413093

  8. Vortex-aligned fullerene nanowhiskers as a scaffold for orienting cell growth.

    PubMed

    Krishnan, Venkata; Kasuya, Yuki; Ji, Qingmin; Sathish, Marappan; Shrestha, Lok Kumar; Ishihara, Shinsuke; Minami, Kosuke; Morita, Hiromi; Yamazaki, Tomohiko; Hanagata, Nobutaka; Miyazawa, Kun'ichi; Acharya, Somobrata; Nakanishi, Waka; Hill, Jonathan P; Ariga, Katsuhiko

    2015-07-22

    A versatile method for the rapid fabrication of aligned fullerene C60 nanowhiskers (C60NWs) at the air-water interface is presented. This method is based on the vortex motion of a subphase (water), which directs floating C60NWs to align on the water surface according to the direction of rotational flow. Aligned C60NWs could be transferred onto many different flat substrates, and, in this case, aligned C60NWs on glass substrates were employed as a scaffold for cell culture. Bone forming human osteoblast MG63 cells adhered well to the C60NWs, and their growth was found to be oriented with the axis of the aligned C60NWs. Cells grown on aligned C60NWs were more highly oriented with the axis of alignment than when grown on randomly oriented nanowhiskers. A study of cell proliferation on the C60NWs revealed their low toxicity, indicating their potential for use in biomedical applications.

  9. Fibrous hydrogel scaffolds with cells embedded in the fibers as a potential tissue scaffold for skin repair.

    PubMed

    Lin, Hsin-Yi; Peng, Chih-Wei; Wu, Wei-Wen

    2014-01-01

    A novel approach was undertaken to create a potential skin wound dressing. L929 fibroblast cells and alginate solution were simultaneously dispensed into a calcium chloride solution using a three-dimensional plotting system to manufacture a fibrous alginate scaffold with interconnected pores. These cells were then embedded in the alginate hydrogel fibers of the scaffold. A conventional scaffold with cells directly seeded on the fiber surface was used as a control. The encapsulated fibroblasts made using the co-dispensing method distributed homogeneously within the scaffold and showed the delayed formation of large cell aggregates compared to the control. The cells embedded in the hydrogel fibers also deposited more type I collagen in the extracellular matrix and expressed higher levels of fgf11 and fn1 than the control, indicating increased cellular proliferation and attachment. The results indicate that the novel co-dispensing alginate scaffold may promote skin regeneration better than the conventional directly-seeded scaffold.

  10. Magnetic alignment of mesophase pitch-based carbon fibers

    NASA Astrophysics Data System (ADS)

    Matthews, M. J.; Dresselhaus, M. S.; Dresselhaus, G.; Endo, M.; Nishimura, Y.; Hiraoka, T.; Tamaki, N.

    1996-07-01

    Mesophase pitch-based carbon fibers (MPCFs) have recently been developed for use as high performance anode materials in Li ion secondary batteries, having a microscopic as well as macroscopic structure especially suitable for Li storage. Because of the highly anisotropic diamagnetic moment observed between 50 and 310 K in pristine milled MPCF segments, they can easily be oriented parallel to an applied magnetic field, as observed by scanning electron microscopy. A simple model is proposed to explain both the observed alignment of undoped fibers and the suppression of alignment in B-doped MPCFs for relatively small applied magnetic fields, because of their smaller diamagnetic moment.

  11. Aligning Arrays of Lenses and Single-Mode Optical Fibers

    NASA Technical Reports Server (NTRS)

    Liu, Duncan

    2004-01-01

    A procedure now under development is intended to enable the precise alignment of sheet arrays of microscopic lenses with the end faces of a coherent bundle of as many as 1,000 single-mode optical fibers packed closely in a regular array (see Figure 1). In the original application that prompted this development, the precise assembly of lenses and optical fibers serves as a single-mode spatial filter for a visible-light nulling interferometer. The precision of alignment must be sufficient to limit any remaining wavefront error to a root-mean-square value of less than 1/10 of a wavelength of light. This wavefront-error limit translates to requirements to (1) ensure uniformity of both the lens and fiber arrays, (2) ensure that the lateral distance from the central axis of each lens and the corresponding optical fiber is no more than a fraction of a micron, (3) angularly align the lens-sheet planes and the fiber-bundle end faces to within a few arc seconds, and (4) axially align the lenses and the fiber-bundle end faces to within tens of microns of the focal distance. Figure 2 depicts the apparatus used in the alignment procedure. The beam of light from a Zygo (or equivalent) interferometer is first compressed by a ratio of 20:1 so that upon its return to the interferometer, the beam will be magnified enough to enable measurement of wavefront quality. The apparatus includes relay lenses that enable imaging of the arrays of microscopic lenses in a charge-coupled-device (CCD) camera that is part of the interferometer. One of the arrays of microscopic lenses is mounted on a 6-axis stage, in proximity to the front face of the bundle of optical fibers. The bundle is mounted on a separate stage. A mirror is attached to the back face of the bundle of optical fibers for retroreflection of light. When a microscopic lens and a fiber are aligned with each other, the affected portion of the light is reflected back by the mirror, recollimated by the microscopic lens, transmitted

  12. Optimizing parameters on alignment of PCL/PGA nanofibrous scaffold: An artificial neural networks approach.

    PubMed

    Paskiabi, Farnoush Asghari; Mirzaei, Esmaeil; Amani, Amir; Shokrgozar, Mohammad Ali; Saber, Reza; Faridi-Majidi, Reza

    2015-11-01

    This paper proposes an artificial neural networks approach to finding the effects of electrospinning parameters on alignment of poly(ɛ-caprolactone)/poly(glycolic acid) blend nanofibers. Four electrospinning parameters, namely total polymer concentration, working distance, drum speed and applied voltage were considered as input and the standard deviation of the angles of nanofibers, introducing fibers alignments, as the output of the model. The results demonstrated that drum speed and applied voltage are two critical factors influencing nanofibers alignment, however their effect are entirely interdependent. Their effects also are not independent of other electrospinning parameters. In obtaining aligned electrospun nanofibers, the concentration and working distance can also be effective. In vitro cell culture study on random and aligned nanofibers showed directional growth of cells on aligned fibers.

  13. In Vitro Repair of Meniscal Radial Tear Using Aligned Electrospun Nanofibrous Scaffold

    PubMed Central

    Shimomura, Kazunori; Bean, Allison C.; Lin, Hang; Nakamura, Norimasa

    2015-01-01

    Radial tears of the meniscus represent one of the most common injuries of the knee, and result in loss of biomechanical meniscal function. However, there have been no established, effective treatments for radial meniscal tears. Nanofibrous materials produced by electrospinning have shown high promise in the engineering of soft musculoskeletal tissues. The goal of our study is to apply these technologies to develop a functional cell-seeded scaffold as a potential, new surgical method to enhance meniscal radial repair. Cylinder-shaped explants were excised from the inner avascular region of bovine meniscus and a radial tear was created in the center of the explant. The torn site was wrapped with either nanofibrous scaffold alone or scaffold seeded with meniscal fibrochondrocytes (MFC). A control group was prepared as explants without scaffolds or cells. The composite constructs in each group were cultured in vitro for 4 and 8 weeks, and these were then assessed histologically and mechanically. Histological analysis showed partial repair of the radial tear was observed with adherence between scaffold and native meniscal tissue in either the scaffold alone or cell-seeded scaffold group. Only the cell-seeded scaffold exhibited significant positive Picrosirius red staining and Safranin O staining. Mechanical testing of the repaired meniscus showed that the load-to-failure and stiffness values were significantly improved in the cell-seeded group. These results demonstrated the applicability of the MFC-seeded nanofibrous scaffold for meniscal radial tear repair based on both histological and mechanical analyses. In particular, the highly adhesive property of the cell-seeded scaffold to the meniscal tissue should be beneficial in helping to preserve the meniscal function by stabilizing meniscal fibers. PMID:25813386

  14. Aligning Optical Fibers by Means of Actuated MEMS Wedges

    NASA Technical Reports Server (NTRS)

    Morgan, Brian; Ghodssi, Reza

    2007-01-01

    Microelectromechanical systems (MEMS) of a proposed type would be designed and fabricated to effect lateral and vertical alignment of optical fibers with respect to optical, electro-optical, optoelectronic, and/or photonic devices on integrated circuit chips and similar monolithic device structures. A MEMS device of this type would consist of a pair of oppositely sloped alignment wedges attached to linear actuators that would translate the wedges in the plane of a substrate, causing an optical fiber in contact with the sloping wedge surfaces to undergo various displacements parallel and perpendicular to the plane. In making it possible to accurately align optical fibers individually during the packaging stages of fabrication of the affected devices, this MEMS device would also make it possible to relax tolerances in other stages of fabrication, thereby potentially reducing costs and increasing yields. In a typical system according to the proposal (see Figure 1), one or more pair(s) of alignment wedges would be positioned to create a V groove in which an optical fiber would rest. The fiber would be clamped at a suitable distance from the wedges to create a cantilever with a slight bend to push the free end of the fiber gently to the bottom of the V groove. The wedges would be translated in the substrate plane by amounts Dx1 and Dx2, respectively, which would be chosen to move the fiber parallel to the plane by a desired amount Dx and perpendicular to the plane by a desired amount Dy. The actuators used to translate the wedges could be variants of electrostatic or thermal actuators that are common in MEMS.

  15. Magnetically aligned H I fibers and the rolling hough transform

    SciTech Connect

    Clark, S. E.; Putman, M. E.; Peek, J. E. G.

    2014-07-01

    We present observations of a new group of structures in the diffuse Galactic interstellar medium (ISM): slender, linear H I features we dub 'fibers' that extend for many degrees at high Galactic latitude. To characterize and measure the extent and strength of these fibers, we present the Rolling Hough Transform, a new machine vision method for parameterizing the coherent linearity of structures in the image plane. With this powerful new tool we show that the fibers are oriented along the interstellar magnetic field as probed by starlight polarization. We find that these low column density (N{sub H} {sub I}≃5×10{sup 18} cm{sup –2}) fiber features are most likely a component of the local cavity wall, about 100 pc away. The H I data we use to demonstrate this alignment at high latitude are from the Galactic Arecibo L-Band Feed Array H I (GALFA-H I) Survey and the Parkes Galactic All Sky Survey. We find better alignment in the higher resolution GALFA-H I data, where the fibers are more visually evident. This trend continues in our investigation of magnetically aligned linear features in the Riegel-Crutcher H I cold cloud, detected in the Southern Galactic Plane Survey. We propose an application of the RHT for estimating the field strength in such a cloud, based on the Chandrasekhar-Fermi method. We conclude that data-driven, quantitative studies of ISM morphology can be very powerful predictors of underlying physical quantities.

  16. Monolayer formation of human osteoblastic cells on vertically aligned multiwalled carbon nanotube scaffolds.

    PubMed

    Lobo, Anderson O; Antunes, Erica F; Palma, Mariana Bs; Pacheco-Soares, Cristina; Trava-Airoldi, Vladimir J; Corat, Evaldo J

    2010-03-12

    Monolayer formation of SaOS-2 (human osteoblast-like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non-toxicity and the flat spreading with monolayer formation of the SaOs-2 on VACNT scaffolds surface indicate that they can be used for biomedical applications.

  17. Melt-spun shaped fibers with enhanced surface effects: fiber fabrication, characterization and application to woven scaffolds.

    PubMed

    Park, S J; Lee, B-K; Na, M H; Kim, D S

    2013-08-01

    Scaffolds with a high surface-area-to-volume ratio (SA:V) are advantageous with regard to the attachment and proliferation of cells in the field of tissue engineering. This paper reports on the development of novel melt-spun fibers with a high SA:V, which enhanced the surface effects of a fiber-based scaffold while maintaining its mechanical strength. The cross-section of the fibers was altered to a non-circular shape, producing a higher SA:V for a similar cross-sectional area. To obtain fibers with non-circular cross-sectional shape, or shaped fibers, three different types of metal spinnerets were fabricated for the melt-spinning process, each with circular, triangular or cruciform capillaries, using deep X-ray lithography followed by nickel electroforming. Using these spinnerets, circular and shaped fibers were manufactured with biodegradable polyester, polycaprolactone. The SA:V increase in the shaped fibers was experimentally investigated under different processing conditions. Tensile tests on the fibers and indentation tests on the woven fiber scaffolds were performed. The tested fibers and scaffolds exhibited similar mechanical characteristics, due to the similar cross-sectional area of the fibers. The degradation of the shaped fibers was notably faster than that of circular fibers, because of the enlarged surface area of the shaped fibers. The woven scaffolds composed of the shaped fibers significantly increased the proliferation of human osteosarcoma MG63 cells. This approach to increase the SA:V in shaped fibers could be useful for the fabrication of programmable, biodegradable fiber-based scaffolds in tissue engineering.

  18. Guidance of in vitro migration of human mesenchymal stem cells and in vivo guided bone regeneration using aligned electrospun fibers.

    PubMed

    Lee, Ji-hye; Lee, Young Jun; Cho, Hyeong-jin; Shin, Heungsoo

    2014-08-01

    Tissue regeneration is a complex process in which numerous chemical and physical signals are coordinated in a specific spatiotemporal pattern. In this study, we tested our hypothesis that cell migration and bone tissue formation can be guided and facilitated by microscale morphological cues presented from a scaffold. We prepared poly(l-lactic acid) (PLLA) electrospun fibers with random and aligned structures and investigated their effect on in vitro migration of human mesenchymal stem cells (hMSCs) and in vivo bone growth using a critical-sized defect model. Using a polydopamine coating on the fibers, we compared the synergistic effects of chemical signals. The adhesion morphology of hMSCs was consistent with the direction of fiber alignment, whereas the proliferation of hMSCs was not affected. The orientation of fibers profoundly affected cell migration, in which hMSCs cultured on aligned fibers migrated 10.46-fold faster along the parallel direction than along the perpendicular direction on polydopamine-coated PLLA nanofibers. We implanted each fiber type into a mouse calvarial defect model for 2 months. The micro-computed tomography (CT) imaging demonstrated that regenerated bone area was the highest when mice were implanted with aligned fibers with polydopamine coating, indicating a positive synergistic effect on bone regeneration. More importantly, scanning electron microscopy microphotographs revealed that the direction of regenerated bone tissue appeared to be consistent with the direction of the implanted fibers, and transmission electron microscopy images showed that the orientation of collagen fibrils appeared to be overlapped along the direction of nanofibers. Taken together, our results demonstrate that the aligned nanofibers can provide spatial guidance for in vitro cell migration as well as in vivo bone regeneration, which may be incorporated as major instructive cues for the stimulation of tissue regeneration.

  19. Aligned nanofibrillar collagen scaffolds – Guiding lymphangiogenesis for treatment of acquired lymphedema

    PubMed Central

    Zaitseva, Tatiana S.; Bazalova-Carter, Magdalena; Paukshto, Michael V.; Hou, Luqia; Strassberg, Zachary; Ferguson, James; Matsuura, Yuka; Dash, Rajesh; Yang, Phillip C.; Kretchetov, Shura; Vogt, Peter M.

    2016-01-01

    Secondary lymphedema is a common disorder associated with acquired functional impairment of the lymphatic system. The goal of this study was to evaluate the therapeutic efficacy of aligned nanofibrillar collagen scaffolds (BioBridge) positioned across the area of lymphatic obstruction in guiding lymphatic regeneration. In a porcine model of acquired lymphedema, animals were treated with BioBridge scaffolds, alone or in conjunction with autologous lymph node transfer as a source of endogenous lymphatic growth factor. They were compared with a surgical control group and a second control group in which the implanted BioBridge was supplemented with exogenous vascular endothelial growth factor-C (VEGF-C). Three months after implantation, immunofluorescence staining of lymphatic vessels demonstrated a significant increase in lymphatic collectors within close proximity to the scaffolds. To quantify the functional impact of scaffold implantation, bioimpedance was used as an early indicator of extracellular fluid accumulation. In comparison to the levels prior to implantation, the bioimpedance ratio was significantly improved only in the experimental BioBridge recipients with or without lymph node transfer, suggesting restoration of functional lymphatic drainage. These results further correlated with quantifiable lymphatic collectors, as visualized by contrast-enhanced computed tomography. They demonstrate the therapeutic potential of BioBridge scaffolds in secondary lymphedema. PMID:27348849

  20. Manufacture of a weakly denatured collagen fiber scaffold with excellent biocompatibility and space maintenance ability.

    PubMed

    Nakada, A; Shigeno, K; Sato, T; Kobayashi, T; Wakatsuki, M; Uji, M; Nakamura, T

    2013-08-01

    Although collagen scaffolds have been used for regenerative medicine, they have insufficient mechanical strength. We made a weakly denatured collagen fiber scaffold from a collagen fiber suspension (physiological pH 7.4) through a process of freeze drying and denaturation with heat under low pressure (1 × 10(-1) Pa). Heat treatment formed cross-links between the collagen fibers, providing the scaffold with sufficient mechanical strength to maintain the space for tissue regeneration in vivo. The scaffold was embedded under the back skin of a rat, and biocompatibility and space maintenance ability were examined after 2 weeks. These were evaluated by using the ratio of foreign body giant cells and thickness of the residual scaffold. A weakly denatured collagen fiber scaffold with moderate biocompatibility and space maintenance ability was made by freezing at -10 °C, followed by denaturation at 140 °C for 6 h. In addition, the direction of the collagen fibers in the scaffold was adjusted by cooling the suspension only from the bottom of the container. This process increased the ratio of cells that infiltrated into the scaffold. A weakly denatured collagen fiber scaffold thus made can be used for tissue regeneration or delivery of cells or proteins to a target site.

  1. An anisotropically and heterogeneously aligned patterned electrospun scaffold with tailored mechanical property and improved bioactivity for vascular tissue engineering.

    PubMed

    Xu, He; Li, Haiyan; Ke, Qinfei; Chang, Jiang

    2015-04-29

    The development of vascular scaffolds with controlled mechanical properties and stimulatory effects on biological activities of endothelial cells still remains a significant challenge to vascular tissue engineering. In this work, we reported an innovative approach to prepare a new type of vascular scaffolds with anisotropically and heterogeneously aligned patterns using electrospinning technique with unique wire spring templates, and further investigated the structural effects of the patterned electrospun scaffolds on mechanical properties and angiogenic differentiation of human umbilical vein endothelial cells (HUVECs). Results showed that anisotropically aligned patterned nanofibrous structure was obtained by depositing nanofibers on template in a structurally different manner, one part of nanofibers densely deposited on the embossments of wire spring and formed cylindrical-like structures in the transverse direction, while others loosely suspended and aligned along the longitudinal direction, forming a three-dimensional porous microstructure. We further found that such structures could efficiently control the mechanical properties of electrospun vascular scaffolds in both longitudinal and transverse directions by altering the interval distances between the embossments of patterned scaffolds. When HUVECs were cultured on scaffolds with different microstructures, the patterned scaffolds distinctively promoted adhesion of HUVECs at early stage and proliferation during the culture period. Most importantly, cells experienced a large shape change associated with cell cytoskeleton and nuclei remodeling, leading to a stimulatory effect on angiogenesis differentiation of HUVECs by the patterned microstructures of electrospun scaffolds, and the scaffolds with larger distances of intervals showed a higher stimulatory effect. These results suggest that electrospun scaffolds with the anisotropically and heterogeneously aligned patterns, which could efficiently control the

  2. Effects of fiber orientation and diameter on the behavior of human dermal fibroblasts on electrospun PMMA scaffolds.

    PubMed

    Liu, Ying; Ji, Yuan; Ghosh, Kaustabh; Clark, Richard A F; Huang, Lei; Rafailovich, Miriam H

    2009-09-15

    We used the electrospinning technique to produce fibrous scaffolds of poly(methyl methacrylate) (PMMA). Using a rotating drum, we aligned the fibers and formed multilayered structures where both the fiber spacing and pore size could be varied. We then plated adult human dermal fibroblasts and studied the effect of fiber diameter and orientation on the cell conformation, integrin receptor expression, proliferation, and migration. We found that a critical diameter minimum diameter existed, D0 = 0.97 microm for cell orientation to occur. For D < D0, no big difference in aspect ratio was observed relative to the control samples on PMMA thin film. Hence, we could fabricate substrate patterned with fibers of different diameters where different cell conformations coexisted on the same scaffold. On the other hand, staining for vinculin proteins in the cells indicated that on large diameter fibers and on flat surfaces, the integrin receptors followed the cell perimeter. On the very small diameter surfaces, the receptors were distributed uniformly along the cell. Cell dynamics studies indicated that the proliferation and migration were also affected by the fiber orientation.

  3. Strong, conductive, lightweight, neat graphene aerogel fibers with aligned pores.

    PubMed

    Xu, Zhen; Zhang, Yuan; Li, Peigang; Gao, Chao

    2012-08-28

    Liquid crystals of anisotropic colloids are of great significance in the preparation of their ordered macroscopic materials, for example, in the cases of carbon nanotubes and graphene. Here, we report a facile and scalable spinning process to prepare neat "core-shell" structured graphene aerogel fibers and three-dimensional cylinders with aligned pores from the flowing liquid crystalline graphene oxide (GO) gels. The uniform alignment of graphene sheets, inheriting the lamellar orders from GO liquid crystals, offers the porous fibers high specific tensile strength (188 kN m kg(-1)) and the porous cylinders high compression modulus (3.3 MPa). The porous graphene fibers have high specific surface area up to 884 m(2) g(-1) due to their interconnected pores and exhibit fine electrical conductivity (2.6 × 10(3) to 4.9 × 10(3) S m(-1)) in the wide temperature range of 5-300 K. The decreasing conductivity with decreasing temperature illustrates a typical semiconducting behavior, and the 3D interconnected network of 2D graphene sheets determines a dual 2D and 3D hopping conduction mechanism. The strong mechanical strength, high porosity, and fine electrical conductivity enable this novel material of ordered graphene aerogels to be greatly useful in versatile catalysts, supercapacitors, flexible batteries and cells, lightweight conductive fibers, and functional textiles.

  4. Design and fabrication of advanced fiber alignment structures for field-installable fiber connectors

    NASA Astrophysics Data System (ADS)

    Van Erps, Jürgen; Vervaeke, Michael; Sánchez Martínez, Alberto; Beri, Stefano; Debaes, Christof; Watté, Jan; Thienpont, Hugo

    2012-06-01

    Fiber-To-The-Home (FTTH) networks have been adopted as a potential replacement of traditional electrical connections for the 'last mile' transmission of information at bandwidths over 1Gb/s. However, the success and adoption of optical access networks critically depend on the quality and reliability of connections between optical fibers. In particular a further reduction of insertion loss of field-installable connectors must be achieved without a significant increase in component cost. This requires precise alignment of fibers that can differ in terms of ellipticity, eccentricity or diameter and seems hardly achievable using today's widespread ferrule-based alignment systems. Novel low-cost structures for bare fiber alignment with outstanding positioning accuracies are strongly desired as they would allow reducing loss beyond the level achievable with ferrule-bore systems. However, the realization of such alignment system is challenging as it should provide sufficient force to position the fiber with sub-micron accuracy required in positioning the fiber. In this contribution we propose, design and prototype a bare-fiber alignment system which makes use of deflectable/compressible micro-cantilevers. Such cantilevers behave as springs and provide self-centering functionality to the structure. Simulations of the mechanical properties of the cantilevers are carried out in order to get an analytical approximation and a mathematical model of the spring constant and stress in the structure. Elastic constants of the order of 104 to 105N/m are found out to be compatible with a proof stress of 70 MPa. Finally a first self-centering structure is prototyped in PMMA using our Deep Proton Writing technology. The spring constants of the fabricated cantilevers are in the range of 4 to 6 × 104N/m and the stress is in the range 10 to 20 MPa. These self-centering structures have the potential to become the basic building blocks for a new generation of field-installable connectors.

  5. Engineering of fiber-reinforced tissues with anisotropic biodegradable nanofibrous scaffolds.

    PubMed

    Nerurkar, Nandan L; Baker, Brendon M; Chen, Chiu-Yu; Elliott, Dawn M; Mauck, Robert L

    2006-01-01

    The repair of dense fiber-reinforced tissues poses a significant challenge for the tissue engineering community. The function of these structures is largely dependent on their architectural form, and as such, scaffold organization is an important design parameter in generating tissue analogues. To address this issue, we have recently utilized electrospinning to instill controllable fiber anisotropy in nanofibrous scaffolds. This abstract details the mechanical characterization of the bulk and local properties of these scaffolds, and points to their potential application in the repair and/or generation of fiber-reinforced tissues that recapitulate the native form.

  6. Freeform extrusion fabrication of titanium fiber reinforced 13-93 bioactive glass scaffolds.

    PubMed

    Thomas, Albin; Kolan, Krishna C R; Leu, Ming C; Hilmas, Gregory E

    2017-05-01

    Although implants made with bioactive glass have shown promising results for bone repair, their application in repairing load-bearing long bone is limited due to their poor mechanical properties in comparison to human bone. This work investigates the freeform extrusion fabrication of bioactive silicate 13-93 glass scaffolds reinforced with titanium (Ti) fibers. A composite paste prepared with 13-93 glass and Ti fibers (~16µm in diameter and lengths varying from ~200µm to ~2 mm) was extruded through a nozzle to fabricate scaffolds (0-90° filament orientation pattern) on a heated plate. The sintered scaffolds measured pore sizes ranging from 400 to 800µm and a porosity of ~50%. Scaffolds with 0.4vol% Ti fibers measured fracture toughness of ~0.8MPam(1/2) and a flexural strength of ~15MPa. 13-93 glass scaffolds without Ti fibers had a toughness of ~0.5MPam(1/2) and a strength of ~10MPa. The addition of Ti fibers increased the fracture toughness of the scaffolds by ~70% and flexural strength by ~40%. The scaffolds' biocompatibility and their degradation in mechanical properties in vitro were assessed by immersing the scaffolds in a simulated body fluid over a period of one to four weeks.

  7. In situ cross-linked electrospun fiber scaffold of collagen for fabricating cell-dense muscle tissue.

    PubMed

    Takeda, Naoya; Tamura, Kenichi; Mineguchi, Ryo; Ishikawa, Yumiko; Haraguchi, Yuji; Shimizu, Tatsuya; Hara, Yusuke

    2016-06-01

    Engineered muscle tissues used as transplant tissues in regenerative medicine should have a three-dimensional and cell-dense structure like native tissue. For fabricating a 3D cell-dense muscle tissue from myoblasts, we proposed the electrospun type I collagen microfiber scaffold of the string-shape like a harp. The microfibers were oriented in the same direction to allow the myoblasts to align, and were strung at low density with micrometer intervals to create space for the cells to occupy. To realize this shape of the scaffold, we employed in situ cross-linking during electrospinning process for the first time to collagen fibers. The collagen microfibers in situ cross-linked with glutaraldehyde stably existed in the aqueous media and completely retained the original shape to save the spaces between the fibers for over 14 days. On the contrary, the conventional cross-linking method by exposure to a glutaraldehyde aqueous solution vapor partially dissolved and damaged the fiber to lose a low-density shape of the scaffold. Myoblasts could penetrate into the interior of the in situ cross-linked string-shaped scaffold and form the cell-dense muscle tissues. Histochemical analysis showed the total area occupied by the cells in the cross section of the tissue was approximately 73 %. Furthermore, the resulting muscle tissue fabricated from primary myoblasts showed typical sarcomeric cross-striations and the entire tissue continuously pulsated by autonomous contraction. Together with the in situ cross-linking, the string-shaped scaffold provides an efficient methodology to fabricate a cell-dense 3D muscle tissue, which could be applied in regenerative medicine in future.

  8. Method and system for aligning fibers during electrospinning

    NASA Technical Reports Server (NTRS)

    Scott-Carnell, Lisa A. (Inventor); Stephens, Ralph M (Inventor); Holloway, Nancy M. (Inventor); Rhim, Caroline (Inventor); Niklason, Laura (Inventor); Clark, Robert L. (Inventor); Siochi, Emilie J. (Inventor)

    2011-01-01

    A method and system are provided for aligning fibers in an electrospinning process. A jet of a fiberizable material is directed towards an uncharged collector from a dispensing location that is spaced apart from the collector. While the fiberizable material is directed towards the collector, an elliptical electric field is generated via the electrically charged dispenser and an oppositely-charged control location. The field spans between the dispensing location and the control location that is within line-of-sight of the dispensing location, and impinges upon at least a portion of the collector. Various combinations of numbers and geometries of dispensers, collectors, and electrodes can be used.

  9. CHARACTERIZATION OF THE COMPLETE FIBER NETWORK TOPOLOGY OF PLANAR FIBROUS TISSUES AND SCAFFOLDS

    PubMed Central

    D'Amore, Antonio; Stella, John A.; Wagner, William R.; Sacks, Michael S.

    2010-01-01

    Understanding how engineered tissue scaffold architecture affects cell morphology, metabolism, phenotypic expression, as well as predicting material mechanical behavior have recently received increased attention. In the present study, an image-based analysis approach that provides an automated tool to characterize engineered tissue fiber network topology is presented. Micro-architectural features that fully defined fiber network topology were detected and quantified, which include fiber orientation, connectivity, intersection spatial density, and diameter. Algorithm performance was tested using scanning electron microscopy (SEM) images of electrospun poly(ester urethane)urea (ES-PEUU) scaffolds. SEM images of rabbit mesenchymal stem cell (MSC) seeded collagen gel scaffolds and decellularized rat carotid arteries were also analyzed to further evaluate the ability of the algorithm to capture fiber network morphology regardless of scaffold type and the evaluated size scale. The image analysis procedure was validated qualitatively and quantitatively, comparing fiber network topology manually detected by human operators (n=5) with that automatically detected by the algorithm. Correlation values between manual detected and algorithm detected results for the fiber angle distribution and for the fiber connectivity distribution were 0.86 and 0.93 respectively. Algorithm detected fiber intersections and fiber diameter values were comparable (within the mean ± standard deviation) with those detected by human operators. This automated approach identifies and quantifies fiber network morphology as demonstrated for three relevant scaffold types and provides a means to: (1) guarantee objectivity, (2) significantly reduce analysis time, and (3) potentiate broader analysis of scaffold architecture effects on cell behavior and tissue development both in vitro and in vivo. PMID:20398930

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  11. Biomimetic, Osteoconductive Non-mulberry Silk Fiber Reinforced Tricomposite Scaffolds for Bone Tissue Engineering.

    PubMed

    Gupta, Prerak; Adhikary, Mimi; M, Joseph Christakiran; Kumar, Manishekhar; Bhardwaj, Nandana; Mandal, Biman B

    2016-11-16

    Composite biomaterials as artificial bone graft materials are pushing the present frontiers of bioengineering. In this study, a biomimetic, osteoconductive tricomposite scaffold made of hydroxyapatite (HA) embedded in non-mulberry Antheraea assama (A. assama) silk fibroin fibers and its fibroin solution is explored for its osteogenic potential. Scaffolds were physico-chemically characterized for morphology, porosity, secondary structure conformation, water retention ability, biodegradability, and mechanical property. The results revealed a ∼5-fold increase in scaffold compressive modulus on addition of HA and silk fibers to liquid silk as compared to pure silk scaffolds while maintaining high scaffold porosity (∼90%) with slower degradation rates. X-ray diffraction (XRD) results confirmed deposition of HA crystals on composite scaffolds. Furthermore, the crystallite size of HA within scaffolds was strongly regulated by the intrinsic physical cues of silk fibroin. Fourier transform infrared (FTIR) spectroscopy studies indicated strong interactions between HA and silk fibroin. The fabricated tricomposite scaffolds supported enhanced cellular viability and function (ALP activity) for both MG63 osteosarcoma and human bone marrow stem cells (hBMSCs) as compared to pure silk scaffolds without fiber or HA addition. In addition, higher expression of osteogenic gene markers such as collagen I (Col-I), osteocalcin (OCN), osteopontin (OPN), and bone sialoprotein (BSP) further substantiated the applicability of HA composite silk scaffolds for bone related applications. Immunostaining studies confirmed localization of Col-I and BSP and were in agreement with real-time gene expression results. These findings demonstrate the osteogenic potential of developed biodegradable tricomposite scaffolds with the added advantage of the affordability of its components as bone graft substitute materials.

  12. Engineering the microstructure of electrospun fibrous scaffolds by microtopography.

    PubMed

    Cheng, Qian; Lee, Benjamin L-P; Komvopoulos, Kyriakos; Li, Song

    2013-05-13

    Controlling the structure and organization of electrospun fibers is desirable for fabricating scaffolds and materials with defined microstructures. However, the effects of microtopography on the deposition and, in turn, the organization of the electrospun fibers are not well understood. In this study, conductive polydimethylsiloxane (PDMS) templates with different micropatterns were fabricated by combining photolithography, silicon wet etching, and PDMS molding techniques. The fiber organization was varied by fine-tuning the microtopography of the electrospinning collector. Fiber conformity and alignment were influenced by the depth and the slope of microtopography features, resulting in scaffolds comprising either an array of microdomains with different porosity and fiber alignment or an array of microwells. Microtopography affected the fiber organization for hundreds of micrometers below the scaffold surface, resulting in scaffolds with distinct surface properties on each side. In addition, the fiber diameter was also affected by the fiber conformity. The effects of the fiber arrangement in the scaffolds on the morphology, migration, and infiltration of cells were examined by in vitro and in vivo experiments. Cell morphology and organization were guided by the fibers in the microdomains, and cell migration was enhanced by the aligned fibers and the three-dimensional scaffold structure. Cell infiltration was correlated with the microdomain porosity. Microscale control of the fiber organization and the porosity at the surface and through the thickness of the fibrous scaffolds, as demonstrated by the results of this study, provides a powerful means of engineering the three-dimensional structure of electrospun fibrous scaffolds for cell and tissue engineering.

  13. Electrospinning of unidirectionally and orthogonally aligned thermoplastic polyurethane nanofibers: Fiber orientation and cell migration

    PubMed Central

    Mi, Hao-Yang; Salick, Max R.; Jing, Xin; Crone, Wendy C.; Peng, Xiang-Fang; Turng, Lih-Sheng

    2015-01-01

    Unidirectionally and orthogonally aligned thermoplastic polyurethane (TPU) nanofibers were electrospun using a custom-built electrospinning device. The unidirectionally aligned fibers were collected using two parallel copper plates, and the orthogonally aligned fibers were collected using two orthogonal sets of parallel copper plates with alternate negative connections. Carbon nanotubes (CNT) and polyacrylic acid (PAA) were added to modify the polymer solution. It was found that both CNT and PAA were capable of increasing solution conductivity. The TPU/PAA fiber showed the highest degree of fiber orientation with more than 90% of the fibers having an orientation angle between −10° and 10° for unidirectionally aligned fibers, and for orthogonally aligned fibers, the orientation angle of 50% fibers located between −10° and 10° and 48% fibers located between 80° and 100°. Viability assessment of 3T3 fibroblasts cultured on TPU/PAA fibers suggested that the material was cytocompatible. The cells’ orientation and migration direction closely matched the fibers’ orientation. The cell migration velocity and distance were both enhanced with the guidance of fibers compared with cells cultured on random fibers and common tissue culture plastic. Controlling cell migration velocity and directionality may provide ways to influence differentiation and gene expression and systems that would allow further exploration of wound repair and metastatic cell behavior. PMID:24771704

  14. Regulated Non-Viral Gene Delivery from Coaxial Electrospun Fiber Mesh Scaffolds

    PubMed Central

    Saraf, Anita; Baggett, L. Scott; Raphael, Robert M.; Kasper, F. Kurtis; Mikos, Antonios G.

    2009-01-01

    In an effort to add to the versatility of three-dimensional scaffolds for tissue engineering applications, recent experimental designs are incorporating biological molecules such as plasmids and proteins within the scaffold structure. Such scaffolds act as reservoirs for the biological molecules of interest while regulating their release over various durations of time. Here, we describe the use of coaxial electrospinning as a means for the fabrication of fiber mesh scaffolds and the encapsulation and subsequent release of a non-viral gene delivery vector over a period of up to 60 days. Various fiber mesh scaffolds containing plasmid DNA (pDNA) within the core and the non-viral gene delivery vector poly(ethylenimine)-hyaluronic acid (PEI-HA) within the sheath of coaxial fibers were fabricated based on a fractional factorial design that investigated the effects of four processing parameters at two levels. Poly(ε-caprolactone) sheath polymer concentration, poly(ethylene glycol) core polymer molecular weight and concentration, and the concentration of pDNA were investigated for their effects on average fiber diameter, release kinetics of PEI-HA, and transfection efficiency. It was determined that increasing the values of each of the investigated parameters caused an increase in the average diameter of the fibers. The release kinetics of PEI-HA from the fibers were affected by the loading concentration of pDNA (with PEI-HA concentration adjusted accordingly to maintain a constant nitrogen to phosphorous (N:P) ratio within the complexes). Two-dimensional cell culture experiments with model fibroblast-like cells demonstrated that complexes of pDNA with PEI-HA released from fiber mesh scaffolds could successfully transfect cells and induce expression of enhanced green fluorescent protein (EGFP). Peak EGFP expression varied with the investigated processing parameters, and the average transfection observed was a function of poly(ethylene glycol) (core) molecular weight and

  15. Regulated non-viral gene delivery from coaxial electrospun fiber mesh scaffolds.

    PubMed

    Saraf, Anita; Baggett, L Scott; Raphael, Robert M; Kasper, F Kurtis; Mikos, Antonios G

    2010-04-02

    In an effort to add to the versatility of three-dimensional scaffolds for tissue engineering applications, recent experimental designs are incorporating biological molecules such as plasmids and proteins within the scaffold structure. Such scaffolds act as reservoirs for the biological molecules of interest while regulating their release over various durations of time. Here, we describe the use of coaxial electrospinning as a means for the fabrication of fiber mesh scaffolds and the encapsulation and subsequent release of a non-viral gene delivery vector over a period of up to 60 days. Various fiber mesh scaffolds containing plasmid DNA (pDNA) within the core and the non-viral gene delivery vector poly(ethylenimine)-hyaluronic acid (PEI-HA) within the sheath of coaxial fibers were fabricated based on a fractional factorial design that investigated the effects of four processing parameters at two levels. Poly(epsilon-caprolactone) sheath polymer concentration, poly(ethylene glycol) core polymer molecular weight and concentration, and the concentration of pDNA were investigated for their effects on average fiber diameter, release kinetics of PEI-HA, and transfection efficiency. It was determined that increasing the values of each of the investigated parameters caused an increase in the average diameter of the fibers. The release kinetics of PEI-HA from the fibers were affected by the loading concentration of pDNA (with PEI-HA concentration adjusted accordingly to maintain a constant nitrogen to phosphorous (N:P) ratio within the complexes). Two-dimensional cell culture experiments with model fibroblast-like cells demonstrated that complexes of pDNA with PEI-HA released from fiber mesh scaffolds could successfully transfect cells and induce expression of enhanced green fluorescent protein (EGFP). Peak EGFP expression varied with the investigated processing parameters, and the average transfection observed was a function of poly(ethylene glycol) (core) molecular weight

  16. Micro-CT of Porous Apatite Fiber Scaffolds Studied by Projection X-ray Microscopy

    NASA Astrophysics Data System (ADS)

    Moriya, J.; Aizawa, M.; Yoshimura, H.

    2011-09-01

    Hydroxyapatite (HAp) has been widely used as a scaffold for repairing fractured bone. For bone regeneration, the crystal structure, crystal orientation, and composition of HAp as well as the morphology of apatite scaffold are considered to be important. The apatite scaffold constructed by single-crystal fibers with pores showed good results for cellular response. Especially, apatite fiber scaffold (AFS) with large pores, 100 to 250 μm, was found to enhance cell activities such as cell proliferation and differentiation. Here, the three-dimensional (3-D) structure of apatite scaffolds was investigated by means of x-ray computed tomography (x-ray CT) using a scanning electron microscope (SEM) modified projection x-ray microscope. The 3-D structures of apatite fiber scaffolds (AFS) were reconstructed from a series of 180 x-ray projection images taken around a single rotation axis using the Feldkamp-based cone-beam reconstruction method. Extracted cross sections from CT data revealed a network-structure of apatite fibers. The distribution of pores inside the AFS in different preparations was compared.

  17. Design of biphasic polymeric 3-dimensional fiber deposited scaffolds for cartilage tissue engineering applications.

    PubMed

    Moroni, L; Hendriks, J A A; Schotel, R; de Wijn, J R; van Blitterswijk, C A

    2007-02-01

    This report describes a novel system to create rapid prototyped 3-dimensional (3D) fibrous scaffolds with a shell-core fiber architecture in which the core polymer supplies the mechanical properties and the shell polymer acts as a coating providing the desired physicochemical surface properties. Poly[(ethylene oxide) terephthalate-co-poly(butylene) terephthalate] (PEOT/PBT) 3D fiber deposited (3DF) scaffolds were fabricated and examined for articular cartilage tissue regeneration. The shell polymer contained a higher molecular weight of the initial poly(ethylene glycol) (PEG) segments used in the copolymerization and a higher weight percentage of the PEOT domains compared with the core polymer. The 3DF scaffolds entirely produced with the shell or with the core polymers were also considered. After 3 weeks of culture, scaffolds were homogeneously filled with cartilage tissue, as assessed by scanning electron microscopy. Although comparable amounts of entrapped chondrocytes and of extracellular matrix formation were found for all analyzed scaffolds, chondrocytes maintained their rounded shape and aggregated during the culture period on shell-core 3DF scaffolds, suggesting a proper cell differentiation into articular cartilage. This finding was also observed in the 3DF scaffolds fabricated with the shell composition only. In contrast, cells spread and attached on scaffolds made simply with the core polymer, implying a lower degree of differentiation into articular cartilaginous tissue. Furthermore, the shell-core scaffolds displayed an improved dynamic stiffness as a result of a "prestress" action of the shell polymer on the core one. In addition, the dynamic stiffness of the constructs increased compared with the stiffness of the bare scaffolds before culture. These findings suggest that shell-core 3DF PEOT/PBT scaffolds with desired mechanical and surface properties are a promising solution for improved cartilage tissue engineering.

  18. Electric Field Effects on Fiber Alignment Using an Auxiliary Electrode During Electrospinning

    NASA Technical Reports Server (NTRS)

    Carnell, Lisa S.; Siochi, Emilie J.; Wincheski, Russell A.; Holloway, Nancy M.; Clark, Robert L.

    2009-01-01

    Control of electrospun fiber placement and distribution was investigated by examining the effect of electric field parameters on the electrospinning of fibers. The experimental set-up used in this study eliminated the bending instability and whipping, allowing the jet to be modeled as a stable trajectory. Coupling of experimental and computational results suggests the potential for predicting aligned fiber distribution in electrospun mats.

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

    PubMed

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

    2016-06-05

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  2. CODEX-aligned dietary fiber definitions help to bridge the 'fiber gap'.

    PubMed

    Jones, Julie Miller

    2014-04-12

    A comprehensive dietary fiber (DF) definition was adopted by the CODEX Alimentarius Commission (CAC) (1) to reflect the current state of knowledge about DF, (2) to recognize that all substances that behave like fiber regardless of how they are produced can be named as DF if they show physiological benefits, and (3) to promote international harmonization for food labeling and food composition tables. This review gives the history and evolution of the state of DF knowledge as looked at by refinements in DF methods and definitions subsequent to the launch of the DF hypothesis. The refinements parallel both interventional and epidemiological research leading to better understanding of the role of DF in contributing to the numerous physiological benefits imparted by all the various digestion resistant carbohydrates. A comparison of the CODEX definition (including its footnote that authorizes the inclusion of polymers with DP 3-9) and approved CODEX Type 1 methods with other existing definitions and methods will point out differences and emphasize the importance of adoption of CODEX-aligned definitions by all jurisdictions. Such harmonization enables comparison of nutrition research, recommendations, food composition tables and nutrition labels the world over. A case will be made that fibers are analogous to vitamins, in that they vary in structure, function and amount needed, but each when present in the right amount contributes to optimal health. Since the intake of DF is significantly below recommended levels throughout the world, the recognition that 'all fibers fit' is an important strategy in bridging the 'fiber gap' by enfranchising and encouraging greater intake of foods with inherent and added DF. Fortifying foods with added DF makes it easier to increase intakes while maintaining calories at recommended levels.

  3. Osteogenic and osteoclastogenic differentiation of co-cultured cells in polylactic acid-nanohydroxyapatite fiber scaffolds.

    PubMed

    Morelli, Sabrina; Salerno, Simona; Holopainen, Jani; Ritala, Mikko; De Bartolo, Loredana

    2015-06-20

    The design of bone substitutes involves the creation of a microenvironment supporting molecular cross-talk between cells and scaffolds during tissue formation and remodelling. Bone remodelling process includes the cooperation of bone-building cells and bone-resorbing cells. In this paper we developed polylactic acid (PLA) and composite PLA-nanohydroxyapatite (nHA) scaffolds with 20 and 50wt.% of nHA by electrospinning technique to be used in bone tissue engineering. The developed scaffolds have different fiber diameter, porosity with interconnected pores and mechanical properties. Taking cues from the bone environment features we investigated the differentiation of human mesenchymal stem cells (hMSCs) from bone marrow in osteoblasts and the osteoclastogenesis in the developed scaffolds in homotypic and in co-culture up to 46 days. PLA and composite PLA-nHA scaffolds induced osteogenic and osteoclastogenic differentiation. Both osteoblasts and osteoclasts displayed high expression of specific markers (osteopontin, osteocalcin, RANK, RANKL) and functions such as secretion of ALP, cathepsin K and TRAP activity on composite scaffolds especially on PLA-nHA containing 20wt.% of nHA. The heterotypic interactions between osteoblasts and osteoclasts co-cultured in the developed scaffolds triggered their functional differentiation and activation.

  4. The Effect of Surface Modification of Aligned Poly-L-Lactic Acid Electrospun Fibers on Fiber Degradation and Neurite Extension

    PubMed Central

    Schaub, Nicholas J.; Le Beux, Clémentine; Miao, Jianjun; Linhardt, Robert J.; Alauzun, Johan G.; Laurencin, Danielle; Gilbert, Ryan J.

    2015-01-01

    The surface of aligned, electrospun poly-L-lactic acid (PLLA) fibers was chemically modified to determine if surface chemistry and hydrophilicity could improve neurite extension from chick dorsal root ganglia. Specifically, diethylenetriamine (DTA, for amine functionalization), 2-(2-aminoethoxy)ethanol (AEO, for alcohol functionalization), or GRGDS (cell adhesion peptide) were covalently attached to the surface of electrospun fibers. Water contact angle measurements revealed that surface modification of electrospun fibers significantly improved fiber hydrophilicity compared to unmodified fibers (p < 0.05). Scanning electron microscopy (SEM) of fibers revealed that surface modification changed fiber topography modestly, with DTA modified fibers displaying the roughest surface structure. Degradation of chemically modified fibers revealed no change in fiber diameter in any group over a period of seven days. Unexpectedly, neurites from chick DRG were longest on fibers without surface modification (1651 ± 488 μm) and fibers containing GRGDS (1560 ± 107 μm). Fibers modified with oxygen plasma (1240 ± 143 μm) or DTA (1118 ± 82 μm) produced shorter neurites than the GRGDS or unmodified fibers, but were not statistically shorter than unmodified and GRGDS modified fibers. Fibers modified with AEO (844 ± 151 μm) were significantly shorter than unmodified and GRGDS modified fibers (p<0.05). Based on these results, we conclude that fiber hydrophilic enhancement alone on electrospun PLLA fibers does not enhance neurite outgrowth. Further work must be conducted to better understand why neurite extension was not improved on more hydrophilic fibers, but the results presented here do not recommend hydrophilic surface modification for the purpose of improving neurite extension unless a bioactive ligand is used. PMID:26340351

  5. Reinforcement of a porous collagen scaffold with surface-activated PLA fibers.

    PubMed

    Liu, Xi; Huang, Changbin; Feng, Yujie; Liang, Jie; Fan, Yujiang; Gu, Zhongwei; Zhang, Xingdong

    2010-01-01

    A hybrid porous collagen scaffold mechanically reinforced with surface-activated poly(lactic acid) (PLA) fiber was prepared. PLA fibers, 20 mum in diameter and 1 mm in length, were aminolyzed with hexanediamine to introduce free amino groups on the surfaces. After the amino groups were transferred to aldehyde groups by treatment with glutaraldehyde, different amounts (1.5, 3, 5 and 8 mg) of surface-activated PLA fibers were homogeneously mixed with 2 ml type-I collagen solution (pH 2.8, 0.6 wt%). This mixture solution was then freeze-dried and cross-linked to obtain collagen sponges with surface-activated PLA fiber. Scanning electron microscopy observation indicated that the collagen sponges had a highly interconnected porous structure with an average pore size of 170 mum, irrespective of PLA fiber incorporation. The dispersion of surface-activated PLA fibers was homogeneous in collagen sponge, in contrast to unactivated PLA fibers. The compression modulus test results showed that, compared with unactivated PLA fibers, the surface-activated PLA fibers enhanced the resistance of collagen sponge to compression more significantly. Cytotoxicity assay by MTT test showed no cytotoxicity of these collagen sponges. L929 mouse fibroblast cell-culture studies in vitro revealed that the number of L929 cells attached to the collagen sponge with surface-activated PLA fibers, both 6 h and 24 h after seeding, was higher than that in pure collagen sponge and sponge with unactivated PLA fibers. In addition, a better distribution of cells infiltrated in collagen sponge with surface-activated PLA fibers was observed by histological staining. These results indicated that the collagen sponge reinforced with surface-activated PLA fibers is a promising biocompatible scaffold for tissue engineering.

  6. Polymer-derived ceramic composite fibers with aligned pristine multiwalled carbon nanotubes.

    PubMed

    Sarkar, Sourangsu; Zou, Jianhua; Liu, Jianhua; Xu, Chengying; An, Linan; Zhai, Lei

    2010-04-01

    Polymer-derived ceramic fibers with aligned multiwalled carbon nanotubes (MWCNTs) are fabricated through the electrospinning of polyaluminasilazane solutions with well-dispersed MWCNTs followed by pyrolysis. Poly(3-hexylthiophene)-b-poly (poly (ethylene glycol) methyl ether acrylate) (P3HT-b-PPEGA), a conjugated block copolymer compatible with polyaluminasilazane, is used to functionalize MWCNT surfaces with PPEGA, providing a noninvasive approach to disperse carbon nanotubes in polyaluminasilazane chloroform solutions. The electrospinning of the MWCNT/polyaluminasilazane solutions generates polymer fibers with aligned MWCNTs where MWCNTs are oriented along the electrospun jet by a sink flow. The subsequent pyrolysis of the obtained composite fibers produces ceramic fibers with aligned MWCNTs. The study of the effect of polymer and CNT concentration on the fiber structures shows that the fiber size increases with the increment of polymer concentration, whereas higher CNT content in the polymer solutions leads to thinner fibers attributable to the increased conductivity. Both the SEM and TEM characterization of the polymer and ceramic fibers demonstrates the uniform orientation of CNTs along the fibers, suggesting excellent dispersion of CNTs and efficient CNT alignment via the electrospinning. The electrical conductivity of a ceramic fibers with 1.2% aligned MWCNTs is measured to be 1.58 x 10(-6) S/cm, which is more than 500 times higher than that of bulk ceramic (3.43 x 10(-9) S/cm). Such an approach provides a versatile method to disperse CNTs in preceramic polymer solutions and offers a new approach to integrate aligned CNTs in ceramics.

  7. Improved thermoplastic composite by alignment of vapor-grown carbon fiber

    NASA Astrophysics Data System (ADS)

    Kuriger, Rex Jerrald

    2000-10-01

    Vapor grown carbon fiber (VGCF) is a new and inexpensive carbon fiber produced by vapor deposition of hydrocarbons on metal catalysts. Unlike continuous conventional PAN or pitch-derived carbon fibers, VGCF is discontinuous with diameters of about 200 nanometers and lengths ranging from 10 to 200 micrometers. The microscopic size and random entanglement of the fibers create several problems when processing VGCF composites. It is particularly difficult to disperse the entangled fibers in the matrix and orient them along a preferred axis to provide directional reinforcement. This work introduces a technique to produce an improved polymeric composite by alignment of vapor grown carbon nano-fibers in a polypropylene matrix. A twin-screw extruder was used to shear mix and disperse the fibers in the polymer matrix. The composite mixtures were extruded through a converging-annular die that generates flow-induced fiber alignment along the extrusion direction. The effect that the various extrusion conditions have on the bulk properties of the extrudate was investigated. It was found that the extrusion process is strongly dependent on the fiber content of the composite. The extrusion pressure increased and the flow rate decreased with fiber volume fraction. The tensile strength and modulus for the composite samples varied with extrusion temperature and screw speed, and the void content increased with fiber volume fraction. It was shown that fiber alignment could be improved by increasing the residence time in the die channel and was verified using x-ray diffraction. The mechanical properties of the aligned samples increased with fiber content. Also, the tensile strength improved with greater fiber orientation; however, more fiber alignment had little affect on the modulus. To better predict the strength of these partially aligned fiber composites, an experimental and theoretical approach was introduced. The experimental data correspond reasonably well when compared with the

  8. Efficient delivery of human single fiber-derived muscle precursor cells via biocompatible scaffold.

    PubMed

    Boldrin, Luisa; Malerba, Alberto; Vitiello, Libero; Cimetta, Elisa; Piccoli, Martina; Messina, Chiara; Gamba, Pier Giorgio; Elvassore, Nicola; De Coppi, Paolo

    2008-01-01

    The success of cell therapy for skeletal muscle disorders depends upon two main factors: the cell source and the method of delivery. In this work we have explored the therapeutic potential of human muscle precursor cells (hMPCs), obtained from single human muscle fibers, implanted in vivo via micropatterned scaffolds. hMPCs were initially expanded and characterized in vitro by immunostaining and flow cytometric analysis. For in vivo studies, hMPCs were seeded onto micropatterned poly-lactic-glycolic acid 3D-scaffolds fabricated using soft-lithography and thermal membrane lamination. Seeded scaffolds were then implanted in predamaged tibialis anterior muscles of CD1 nude mice; hMPCs were also directly injected in contralateral limbs as controls. Similarly to what we previously described with mouse precursors cells, we found that hMPCs were able to participate in muscle regeneration and scaffold-implanted muscles contained a greater number of human nuclei, as revealed by immunostaining and Western blot analyses. These results indicate that hMPCs derived from single fibers could be a good and reliable cell source for the design of therapeutic protocols and that implantation of cellularized scaffolds is superior to direct injection for the delivery of myogenic cells into regenerating skeletal muscle.

  9. Local alignment vectors reveal cancer cell-induced ECM fiber remodeling dynamics.

    PubMed

    Lee, Byoungkoo; Konen, Jessica; Wilkinson, Scott; Marcus, Adam I; Jiang, Yi

    2017-01-03

    Invasive cancer cells interact with the surrounding extracellular matrix (ECM), remodeling ECM fiber network structure by condensing, degrading, and aligning these fibers. We developed a novel local alignment vector analysis method to quantitatively measure collagen fiber alignment as a vector field using Circular Statistics. This method was applied to human non-small cell lung carcinoma (NSCLC) cell lines, embedded as spheroids in a collagen gel. Collagen remodeling was monitored using second harmonic generation imaging under normal conditions and when the LKB1-MARK1 pathway was disrupted through RNAi-based approaches. The results showed that inhibiting LKB1 or MARK1 in NSCLC increases the collagen fiber alignment and captures outward alignment vectors from the tumor spheroid, corresponding to high invasiveness of LKB1 mutant cancer cells. With time-lapse imaging of ECM micro-fiber morphology, the local alignment vector can measure the dynamic signature of invasive cancer cell activity and cell-migration-induced ECM and collagen remodeling and realigning dynamics.

  10. Local alignment vectors reveal cancer cell-induced ECM fiber remodeling dynamics

    PubMed Central

    Lee, Byoungkoo; Konen, Jessica; Wilkinson, Scott; Marcus, Adam I.; Jiang, Yi

    2017-01-01

    Invasive cancer cells interact with the surrounding extracellular matrix (ECM), remodeling ECM fiber network structure by condensing, degrading, and aligning these fibers. We developed a novel local alignment vector analysis method to quantitatively measure collagen fiber alignment as a vector field using Circular Statistics. This method was applied to human non-small cell lung carcinoma (NSCLC) cell lines, embedded as spheroids in a collagen gel. Collagen remodeling was monitored using second harmonic generation imaging under normal conditions and when the LKB1-MARK1 pathway was disrupted through RNAi-based approaches. The results showed that inhibiting LKB1 or MARK1 in NSCLC increases the collagen fiber alignment and captures outward alignment vectors from the tumor spheroid, corresponding to high invasiveness of LKB1 mutant cancer cells. With time-lapse imaging of ECM micro-fiber morphology, the local alignment vector can measure the dynamic signature of invasive cancer cell activity and cell-migration-induced ECM and collagen remodeling and realigning dynamics. PMID:28045069

  11. Cell Alignment Driven by Mechanically Induced Collagen Fiber Alignment in Collagen/Alginate Coatings

    PubMed Central

    Chaubaroux, Christophe; Perrin-Schmitt, Fabienne; Senger, Bernard; Vidal, Loïc; Voegel, Jean-Claude; Schaaf, Pierre; Haikel, Youssef; Boulmedais, Fouzia; Lavalle, Philippe

    2015-01-01

    For many years it has been a major challenge to regenerate damaged tissues using synthetic or natural materials. To favor the healing processes after tendon, cornea, muscle, or brain injuries, aligned collagen-based architectures are of utmost interest. In this study, we define a novel aligned coating based on a collagen/alginate (COL/ALG) multilayer film. The coating exhibiting a nanofibrillar structure is cross-linked with genipin for stability in physiological conditions. By stretching COL/ALG-coated polydimethylsiloxane substrates, we developed a versatile method to align the collagen fibrils of the polymeric coating. Assays on cell morphology and alignment were performed to investigate the properties of these films. Microscopic assessments revealed that cells align with the stretched collagen fibrils of the coating. The degree of alignment is tuned by the stretching rate (i.e., the strain) of the COL/ALG-coated elastic substrate. Such coatings are of great interest for strategies that require aligned nanofibrillar biological material as a substrate for tissue engineering. PMID:25658028

  12. 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 of expanded MFCs to scaffolds before in vitro repair improved integration with the native tissue, but did not influence maturation. In contrast, preculture of these same scaffolds for 1 month before repair decreased integration with the native tissue, but resulted in a more mature scaffold compared to implantation of cellular scaffolds or acellular scaffolds. This work will inform scaffold selection in future in vivo studies by identifying the ideal scaffold and seeding methods for meniscus tissue engineering. PMID:22994398

  13. New technology developments make passive laser/fiber alignment a reality

    NASA Astrophysics Data System (ADS)

    Collins, John V.; MacDonald, Brian M.; Lealman, I. F.; Jones, C. A.

    1996-01-01

    In this paper we report on the combination of a precision cleaved large spot laser and a silicon micromachined optical bench to achieve high coupling efficiencies by purely passive alignment. Coupling efficiencies of over 50% have been obtained by passively aligning precision cleaved large spot sized lasers to singlemode fiber on a silicon micromachined substrate. This is the highest known coupling figure reported for passive alignment. The packaging of semiconductor laser chips has always presented a range of technical problems due to the sub-micron tolerances required to obtain optimum coupling of the small laser spot size to the larger spot size of a singlemode fiber. Lasers have been developed that can ease these tolerances by matching the laser spot size to that of cleaved fiber. This is achieved by tapering the active layer to adiabatically expand the laser mode size. A method of controlling the physical size of laser diode chips to sub-micron accuracy has enabled these lasers to be bonded against substantial alignment features on a silicon micro-engineered optical bench which also includes a V-groove into which a cleaved single-mode optical fiber can be fixed. Results are also discussed for an alternative ferrule-based, non-hermetic laser packaging design which utilizes the relaxed alignment tolerances of the large spot lasers to give simple package assembly suitable for automation. Both of the packaging technologies discussed offer a viable route to obtaining the very low cost optoelectronic components required for fiber to the home networks.

  14. Seamless, axially aligned, fiber tubes, meshes, microbundles and gradient biomaterial constructs

    PubMed Central

    Elia, Roberto; Firpo, Matthew A.; Kaplan, David L.; Peattie, Robert A.

    2012-01-01

    A new electrospinning apparatus was developed to generate nanofibrous materials with improved organizational control. The system functions by oscillating the deposition signal (ODS) of multiple collectors, allowing significantly improved nanofiber control by manipulating the electric field which drives the electrospinning process. Other electrospinning techniques designed to impart deposited fiber organizational control, such as rotating mandrels or parallel collector systems, do not generate seamless constructs with high quality alignment in sizes large enough for medical devices. In contrast, the ODS collection system produces deposited fiber networks with highly pure alignment in a variety of forms and sizes, including flat (8 × 8 cm2), tubular (1.3 cm diameter), or rope-like microbundle (45 μm diameter) samples. Additionally, the mechanism of our technique allows for scale-up beyond these dimensions. The ODS collection system produced 81.6 % of fibers aligned within 5° of the axial direction, nearly a four-fold improvement over the rotating mandrel technique. The meshes produced from the 9 % (w/v) fibroin/PEO blend demonstrated significant mechanical anisotropy due to the fiber alignment. In 37 °C PBS, aligned samples produced an ultimate tensile strength of 16.47 ± 1.18 MPa, a Young's modulus of 37.33 MPa, and a yield strength of 7.79 ± 1.13 MPa. The material was 300 % stiffer when extended in the direction of fiber alignment and required 20 times the amount of force to be deformed, compared to aligned meshes extended perpendicular to the fiber direction. The ODS technique could be applied to any electrospinnable polymer to overcome the more limited uniformity and induced mechanical strain of rotating mandrel techniques, and greatly surpasses the limited length of standard parallel collector techniques. PMID:22890517

  15. Seamless, axially aligned, fiber tubes, meshes, microbundles and gradient biomaterial constructs.

    PubMed

    Jose, Rod R; Elia, Roberto; Firpo, Matthew A; Kaplan, David L; Peattie, Robert A

    2012-11-01

    A new electrospinning apparatus was developed to generate nanofibrous materials with improved organizational control. The system functions by oscillating the deposition signal (ODS) of multiple collectors, allowing significantly improved nanofiber control by manipulating the electric field which drives the electrospinning process. Other electrospinning techniques designed to impart deposited fiber organizational control, such as rotating mandrels or parallel collector systems, do not generate seamless constructs with high quality alignment in sizes large enough for medical devices. In contrast, the ODS collection system produces deposited fiber networks with highly pure alignment in a variety of forms and sizes, including flat (8 × 8 cm(2)), tubular (1.3 cm diameter), or rope-like microbundle (45 μm diameter) samples. Additionally, the mechanism of our technique allows for scale-up beyond these dimensions. The ODS collection system produced 81.6 % of fibers aligned within 5° of the axial direction, nearly a four-fold improvement over the rotating mandrel technique. The meshes produced from the 9 % (w/v) fibroin/PEO blend demonstrated significant mechanical anisotropy due to the fiber alignment. In 37 °C PBS, aligned samples produced an ultimate tensile strength of 16.47 ± 1.18 MPa, a Young's modulus of 37.33 MPa, and a yield strength of 7.79 ± 1.13 MPa. The material was 300 % stiffer when extended in the direction of fiber alignment and required 20 times the amount of force to be deformed, compared to aligned meshes extended perpendicular to the fiber direction. The ODS technique could be applied to any electrospinnable polymer to overcome the more limited uniformity and induced mechanical strain of rotating mandrel techniques, and greatly surpasses the limited length of standard parallel collector techniques.

  16. Clothing polymer fibers with well-aligned and high-aspect ratio carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sun, Gengzhi; Zheng, Lianxi; An, Jia; Pan, Yongzheng; Zhou, Jinyuan; Zhan, Zhaoyao; Pang, John H. L.; Chua, Chee Kai; Leong, Kah Fai; Li, Lin

    2013-03-01

    It is believed that the crucial step towards preparation of electrical conductive polymer-carbon nanotube (CNT) composites is dispersing CNTs with a high length-to-diameter aspect ratio in a well-aligned manner. However, this process is extremely challenging when dealing with long and entangled CNTs. Here in this study, a new approach is demonstrated to fabricate conductive polymer-CNT composite fibers without involving any dispersion process. Well-aligned CNT films were firstly drawn from CNT arrays, and then directly coated on polycaprolactone fibers to form polymer-CNT composite fibers. The conductivity of these composite fibers can be as high as 285 S m-1 with only 2.5 wt% CNT loading, and reach 1549 S m-1 when CNT loading is 13.4 wt%. As-prepared composite fibers also exhibit 82% retention of conductivity at a strain of 7%, and have improved mechanical properties.It is believed that the crucial step towards preparation of electrical conductive polymer-carbon nanotube (CNT) composites is dispersing CNTs with a high length-to-diameter aspect ratio in a well-aligned manner. However, this process is extremely challenging when dealing with long and entangled CNTs. Here in this study, a new approach is demonstrated to fabricate conductive polymer-CNT composite fibers without involving any dispersion process. Well-aligned CNT films were firstly drawn from CNT arrays, and then directly coated on polycaprolactone fibers to form polymer-CNT composite fibers. The conductivity of these composite fibers can be as high as 285 S m-1 with only 2.5 wt% CNT loading, and reach 1549 S m-1 when CNT loading is 13.4 wt%. As-prepared composite fibers also exhibit 82% retention of conductivity at a strain of 7%, and have improved mechanical properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr34208e

  17. Light Diffraction of Aligned Polymer Fibers Periodically Dispersed by Phase Separation of Liquid Crystal and Polymer

    NASA Astrophysics Data System (ADS)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2004-12-01

    We have confirmed light diffraction of aligned polymer fibers obtained by a phase separation of an anisotropic-phase solution of liquid crystal and polymer. He—Ne laser light passing through the polymer fibers was scattered in the axis vertical to the fibers, and had two peaks of light intensity symmetrical to the center of the transmitting laser spot. The two peaks were found to be caused by light diffraction due to the periodic polymer-fiber dispersion because the peaks corresponded to values calculated by intervals between the fibers. The periodical fiber networks are considered to be formed by anisotropic spinodal decomposition. This effect can be used to measure the dispersion order of the polymer fibers.

  18. Engineering controllable anisotropy in electrospun biodegradable nanofibrous scaffolds for musculoskeletal tissue engineering.

    PubMed

    Li, Wan-Ju; Mauck, Robert L; Cooper, James A; Yuan, Xiaoning; Tuan, Rocky S

    2007-01-01

    Many musculoskeletal tissues exhibit significant anisotropic mechanical properties reflective of a highly oriented underlying extracellular matrix. For tissue engineering, recreating this organization of the native tissue remains a challenge. To address this issue, this study explored the fabrication of biodegradable nanofibrous scaffolds composed of aligned fibers via electrospinning onto a rotating target, and characterized their mechanical anisotropy as a function of the production parameters. The characterization showed that nanofiber organization was dependent on the rotation speed of the target; randomly oriented fibers (33% fiber alignment) were produced on a stationary shaft, whereas highly oriented fibers (94% fiber alignment) were produced when rotation speed was increased to 9.3m/s. Non-aligned scaffolds had an isotropic tensile modulus of 2.1+/-0.4MPa, compared to highly anisotropic scaffolds whose modulus was 11.6+/-3.1MPa in the presumed fiber direction, suggesting that fiber alignment has a profound effect on the mechanical properties of scaffolds. Mechanical anisotropy was most pronounced at higher rotation speeds, with a greater than 33-fold enhancement of the Young's modulus in the fiber direction compared to perpendicular to the fiber direction when the rotation speed reached 8m/s. In cell culture, both the organization of actin filaments of human mesenchymal stem cells and the cellular alignment of meniscal fibroblasts were dictated by the prevailing nanofiber orientation. This study demonstrates that controllable and anisotropic mechanical properties of nanofibrous scaffolds can be achieved by dictating nanofiber organization through intelligent scaffold design.

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

    PubMed

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

    2014-10-01

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

  20. Thermal Shock Tolerance of Ferroelectric Liquid Crystal Stabilized by Aligned Polymer Fibers

    NASA Astrophysics Data System (ADS)

    Fujikake, Hideo; Murashige, Takeshi; Sato, Hiroto; Fujisaki, Yoshihide; Kawakita, Masahiro; Kikuchi, Hiroshi; Kurita, Taiichiro

    2003-02-01

    In this paper, we report the marked enhancement of thermal shock tolerance of smectic layer structures of ferroelectric liquid crystal stabilized by aligned fine polymer fibers, which were formed by photopolymerization-induced phase separation. It was found that a smectic layer structure with such polymer fibers, which are aligned perpendicular to the smectic layer, generates no zigzag defects even after the composite film is cooled to -15°C, which is lower than the chiral smectic C-to-crystal phase-transition temperature, or heated to 100°C, which is above the chiral nematic-to-isotropic phase-transition temperature.

  1. Improved cellular infiltration into nanofibrous electrospun cross-linked gelatin scaffolds templated with micrometer sized polyethylene glycol fibers

    PubMed Central

    Skotak, Maciej; Ragusa, Jorge; Gonzalez, Daniela; Subramanian, Anuradha

    2011-01-01

    Gelatin-based nanofibrous scaffolds with a mean fiber diameter of 300 nm were prepared with and without micrometer-sized polyethylene glycol (PEG) fibers that served as sacrificial templates. Upon fabrication of the scaffolds via electrospinning, the gelatin fibers were crosslinked with glutaraldehyde, and the PEG templates were removed using tert-butanol to yield nanofibrous scaffolds with pore diameters ranging from 10 to 100 µm, as estimated with mercury intrusion porosimetry. Non-templated gelatin-based nanofibrous matrices had an average pore size of 1 µm. Fibroblasts were seeded onto both types of the gelatin-based nanfibrous surfaces and cultured for 14 days. For comparative purposes, chitosan-based and polyurethane (PU)-based macroporous scaffolds with pore sizes of 100 µm and 170 µm, respectively, also were included. The number of cells as a function of the depth into the scaffold was judged and quantitatively assessed using nuclei staining. Cell penetration up to a depth of 250 µm and 90 µm was noted in gelatin scaffolds prepared with sacrificial templates and gelatin-only nanofibrous scaffolds. Noticeably, scaffold preparation protocol presented here allowed the structural integrity to be maintained even with high template content (95 %) and can be easily extended towards other classes of electrospun polymer matrices for tissue engineering. PMID:21931195

  2. Effect of random/aligned nylon-6/MWCNT fibers on dental resin composite reinforcement.

    PubMed

    Borges, Alexandre L S; Münchow, Eliseu A; de Oliveira Souza, Ana Carolina; Yoshida, Takamitsu; Vallittu, Pekka K; Bottino, Marco C

    2015-08-01

    The aims of this study were (1) to synthesize and characterize random and aligned nanocomposite fibers of multi-walled carbon nanotubes (MWCNT)/nylon-6 and (2) to determine their reinforcing effects on the flexural strength of a dental resin composite. Nylon-6 was dissolved in hexafluoropropanol (10 wt%), followed by the addition of MWCNT (hereafter referred to as nanotubes) at two distinct concentrations (i.e., 0.5 or 1.5 wt%). Neat nylon-6 fibers (without nanotubes) were also prepared. The solutions were electrospun using parameters under low- (120 rpm) or high-speed (6000 rpm) mandrel rotation to collect random and aligned fibers, respectively. The processed fiber mats were characterized by scanning (SEM) and transmission (TEM) electron microscopies, as well as by uni-axial tensile testing. To determine the reinforcing effects on the flexural strength of a dental resin composite, bar-shaped (20×2×2 mm(3)) resin composite specimens were prepared by first placing one increment of the composite, followed by one strip of the mat, and one last increment of composite. Non-reinforced composite specimens were used as the control. The specimens were then evaluated using flexural strength testing. SEM was done on the fractured surfaces. The data were analyzed using ANOVA and the Tukey׳s test (α=5%). Nanotubes were successfully incorporated into the nylon-6 fibers. Aligned and random fibers were obtained using high- and low-speed electrospinning, respectively, where the former were significantly (p<0.001) stronger than the latter, regardless of the nanotubes׳ presence. Indeed, the dental resin composite tested was significantly reinforced when combined with nylon-6 fibrous mats composed of aligned fibers (with or without nanotubes) or random fibers incorporated with nanotubes at 0.5 wt%.

  3. Enzyme activity assays within microstructured optical fibers enabled by automated alignment

    PubMed Central

    Warren-Smith, Stephen C.; Nie, Guiying; Schartner, Erik P.; Salamonsen, Lois A.; Monro, Tanya M.

    2012-01-01

    A fluorescence-based enzyme activity assay has been demonstrated within a small-core microstructured optical fiber (MOF) for the first time. To achieve this, a reflection-based automated alignment system has been developed, which uses feedback and piezoelectric actuators to maintain optical alignment. The auto-alignment system provides optical stability for the time required to perform an activity assay. The chosen assay is based on the enzyme proprotein convertase 5/6 (PC6) and has important applications in women’s health. PMID:23243579

  4. Electrospinning of photocrosslinked and degradable fibrous scaffolds.

    PubMed

    Tan, Andrea R; Ifkovits, Jamie L; Baker, Brendon M; Brey, Darren M; Mauck, Robert L; Burdick, Jason A

    2008-12-15

    Electrospun fibrous scaffolds are being developed for the engineering of numerous tissues. Advantages of electrospun scaffolds include the similarity in fiber diameter to elements of the native extracellular matrix and the ability to align fibers within the scaffold to control and direct cellular interactions and matrix deposition. To further expand the range of properties available in fibrous scaffolds, we developed a process to electrospin photocrosslinkable macromers from a library of multifunctional poly(beta-amino ester)s. In this study, we utilized one macromer (A6) from this library for initial examination of fibrous scaffold formation. A carrier polymer [poly(ethylene oxide) (PEO)] was used for fiber formation because of limitations in electrospinning A6 alone. Various ratios of A6 and PEO were successfully electrospun and influenced the scaffold fiber diameter and appearance. When electrospun with a photoinitiator and exposed to light, the macromers crosslinked rapidly to high double bond conversions and fibrous scaffolds displayed higher elastic moduli compared to uncrosslinked scaffolds. When these fibers were deposited onto a rotating mandrel and crosslinked, organized fibrous scaffolds were obtained, which possessed higher moduli (approximately 4-fold) in the fiber direction than perpendicular to the fiber direction, as well as higher moduli (approximately 12-fold) than that of nonaligned crosslinked scaffolds. With exposure to water, a significant mass loss and a decrease in mechanical properties were observed, correlating to a rapid initial loss of PEO which reached an equilibrium after 7 days. Overall, these results present a process that allows for formation of fibrous scaffolds from a wide variety of possible photocrosslinkable macromers, increasing the diversity and range of properties achievable in fibrous scaffolds for tissue regeneration.

  5. Active or passive fiber-chip-alignment: approaches to efficient solutions

    NASA Astrophysics Data System (ADS)

    Böttger, Gunnar; Schröder, Henning; Jordan, Rafael

    2013-02-01

    High precision approaches for active and passive alignment and assembly on optoelectronic micro benches have been realized at Fraunhofer IZM for various material systems and different scales. The alignment and reliable mounting of optical subcomponents such as semiconductor laser and photo diodes, micro lenses and micro prisms require far higher mounting and alignment accuracies than for micro-electronic parts. When connecting from silicon photonics chip level to single mode optical fibers, even higher precisions are called for (typically < 100 nm). Alignment and assembly commonly are performed on specialized lab equipment which needs manual operation, consuming a lot of time, with less possibilities for automation. To introduce a higher degree of automatized production, like it has become standard in large volume electronics, one can choose either active or passive alignment processes - or possibly a combination of both. In this article we will present examples of micro-optic benches and optical interconnections that include alignment structures for passive alignment - where the accuracy lies in the components to be assembled, and mounting takes place on a less accurate machine ("fit into place"). But there is also a lot of progress on optical "pick, measure and place" machines that realize a flexible and fully automated active alignment using vision systems and activated components of less cost, with machine and process robustness for usability in industrial environments. As connecting elements, passive optical components like optical fibers are commonly used. These fragile and flexible elements pose additional challenges in secure picking, placing and fixing, at long lengths vs. small diameters. A very recent and specific approach to use more robust plastic optical fibers (POF) for very short and cost effective optical interconnects by means of wire bonding machines will be presented.

  6. Circumferentially aligned fibers guided functional neoartery regeneration in vivo.

    PubMed

    Zhu, Meifeng; Wang, Zhihong; Zhang, Jiamin; Wang, Lina; Yang, Xiaohu; Chen, Jingrui; Fan, Guanwei; Ji, Shenglu; Xing, Cheng; Wang, Kai; Zhao, Qiang; Zhu, Yan; Kong, Deling; Wang, Lianyong

    2015-08-01

    An ideal vascular graft should have the ability to guide the regeneration of neovessels with structure and function similar to those of the native blood vessels. Regeneration of vascular smooth muscle cells (VSMCs) with circumferential orientation within the grafts is crucial for functional vascular reconstruction in vivo. To date, designing and fabricating a vascular graft with well-defined geometric cues to facilitate simultaneously VSMCs infiltration and their circumferential alignment remains a great challenge and scarcely reported in vivo. Thus, we have designed a bi-layered vascular graft, of which the internal layer is composed of circumferentially aligned microfibers prepared by wet-spinning and an external layer composed of random nanofibers prepared by electrospinning. While the internal circumferentially aligned microfibers provide topographic guidance for in vivo regeneration of circumferentially aligned VSMCs, the external random nanofibers can offer enhanced mechanical property and prevent bleeding during and after graft implantation. VSMCs infiltration and alignment within the scaffold was then evaluated in vitro and in vivo. Our results demonstrated that the circumferentially oriented VSMCs and longitudinally aligned ECs were successfully regenerated in vivo after the bi-layered vascular grafts were implanted in rat abdominal aorta. No formation of thrombosis or intimal hyperplasia was observed up to 3 month post implantation. Further, the regenerated neoartery exhibited contraction and relaxation property in response to vasoactive agents. This new strategy may bring cell-free small diameter vascular grafts closer to clinical application.

  7. Electric Field Effects on Fiber Alignment Using an Auxiliary Electrode during Electrospinning

    NASA Technical Reports Server (NTRS)

    Carnell, Lisa S.; Wincheski, Russell A.; Siochi, Emilie, J.; Holloway, Nancy M.; Clark, Robert L.

    2007-01-01

    This viewgraph presentation reviews auxiliary and electric field effects on fiber alignment during the process of electrospinning. The contents include: 1) Electrospinning Overview; 2) Experimental Set-up; 3) Jet Exit; 4) Auxiliary Electrode Effects; 5) Electrospinning High Speed Video; 6) Effect of Auxiliary Electrode Position; 7) Micro & Nano Fibers Produced; 8) Micro and Nano Fibrous Mats; 9) Field Effect on Fiber Distribution; 10) Modeling; 11) Calculated trajectories: 5, 10, 15 & 20cm electrode spacing; 12) Off Axis Auxiliary Electrode; 13) Field Strength Effects; and 14) Potential Applications.

  8. Note: Aligned deposition and modal characterization of micron and submicron poly(methyl methacyrlate) fiber cantilevers.

    PubMed

    Nain, Amrinder S; Filiz, Sinan; Ozdoganlar, O Burak; Sitti, Metin; Amon, Cristina

    2010-01-01

    Polymeric micro-/nanofibers are finding increasing use as sensors for novel applications. Here, we demonstrate the ability to deposit an array of poly(methyl methacyrlate) fibers with micron and submicron diameters in aligned configurations on customized piezoelectric shakers. Using lateral motion of an atomic force microscope tip, fibers are broken to obtain fiber cantilevers of high aspect ratio (length/diameter > 20). The resonant frequencies of fabricated microfiber cantilevers are experimentally measured using a laser Doppler vibrometer. An average Young's modulus of 3.5 GPa and quality factor of 20 were estimated from the experimentally obtained frequency responses.

  9. Aligned poly(L-lactic-co-e-caprolactone) electrospun microfibers and knitted structure: a novel composite scaffold for ligament tissue engineering.

    PubMed

    Vaquette, Cédryck; Kahn, Cyril; Frochot, Céline; Nouvel, Cécile; Six, Jean-Luc; De Isla, Natalia; Luo, Li-Hua; Cooper-White, Justin; Rahouadj, Rachid; Wang, Xiong

    2010-09-15

    We developed a novel technique involving knitting and electrospinning to fabricate a composite scaffold for ligament tissue engineering. Knitted structures were coated with poly(L-lactic-co-e-caprolactone) (PLCL) and then placed onto a rotating cylinder and a PLCL solution was electrospun onto the structure. Highly aligned 2-microm-diameter microfibers covered the space between the stitches and adhered to the knitted scaffolds. The stress-strain tensile curves exhibited an initial toe region similar to the tensile behavior of ligaments. Composite scaffolds had an elastic modulus (150 +/- 14 MPa) similar to the modulus of human ligaments. Biological evaluation showed that cells proliferated on the composite scaffolds and they spontaneously orientated along the direction of microfiber alignment. The microfiber architecture also induced a high level of extracellular matrix secretion, which was characterized by immunostaining. We found that cells produced collagen type I and type III, two main components found in ligaments. After 14 days of culture, collagen type III started to form a fibrous network. We fabricated a composite scaffold having the mechanical properties of the knitted structure and the morphological properties of the aligned microfibers. It is difficult to seed a highly macroporous structure with cells, however the technique we developed enabled an easy cell seeding due to presence of the microfiber layer. Therefore, these scaffolds presented attractive properties for a future use in bioreactors for ligament tissue engineering.

  10. Preparation of active 3D film patches via aligned fiber electrohydrodynamic (EHD) printing

    NASA Astrophysics Data System (ADS)

    Wang, Jun-Chuan; Zheng, Hongxia; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

    2017-03-01

    The design, preparation and application of three-dimensional (3D) printed structures have gained appreciable interest in recent times, particularly for drug dosage development. In this study, the electrohydrodynamic (EHD) printing technique was developed to fabricate aligned-fiber antibiotic (tetracycline hydrochloride, TE-HCL) patches using polycaprolactone (PCL), polyvinyl pyrrolidone (PVP) and their composite system (PVP-PCL). Drug loaded 3D patches possessed perfectly aligned fibers giving rise to fibrous strut orientation, variable inter-strut pore size and controlled film width (via layering). The effect of operating parameters on fiber deposition and alignment were explored, and the impact of the film structure, composition and drug loading was evaluated. FTIR demonstrated successful TE-HCL encapsulation in aligned fibers. Patches prepared using PVP and TE-HCL displayed enhanced hydrophobicity. Tensile tests exhibited changes to mechanical properties arising from additive effects. Release of antibiotic from PCL-PVP dosage forms was shown over 5 days and was slower compared to pure PCL or PVP. The printed patch void size also influenced antibiotic release behavior. The EHDA printing technique provides an exciting opportunity to tailor dosage forms in a single-step with minimal excipients and operations. These developments are crucial to meet demands where dosage forms cannot be manufactured rapidly or when a personalized approach is required.

  11. Preparation of active 3D film patches via aligned fiber electrohydrodynamic (EHD) printing

    PubMed Central

    Wang, Jun-Chuan; Zheng, Hongxia; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

    2017-01-01

    The design, preparation and application of three-dimensional (3D) printed structures have gained appreciable interest in recent times, particularly for drug dosage development. In this study, the electrohydrodynamic (EHD) printing technique was developed to fabricate aligned-fiber antibiotic (tetracycline hydrochloride, TE-HCL) patches using polycaprolactone (PCL), polyvinyl pyrrolidone (PVP) and their composite system (PVP-PCL). Drug loaded 3D patches possessed perfectly aligned fibers giving rise to fibrous strut orientation, variable inter-strut pore size and controlled film width (via layering). The effect of operating parameters on fiber deposition and alignment were explored, and the impact of the film structure, composition and drug loading was evaluated. FTIR demonstrated successful TE-HCL encapsulation in aligned fibers. Patches prepared using PVP and TE-HCL displayed enhanced hydrophobicity. Tensile tests exhibited changes to mechanical properties arising from additive effects. Release of antibiotic from PCL-PVP dosage forms was shown over 5 days and was slower compared to pure PCL or PVP. The printed patch void size also influenced antibiotic release behavior. The EHDA printing technique provides an exciting opportunity to tailor dosage forms in a single-step with minimal excipients and operations. These developments are crucial to meet demands where dosage forms cannot be manufactured rapidly or when a personalized approach is required. PMID:28272513

  12. Passively aligned multichannel fiber-pigtailing of planar integrated optical waveguides

    NASA Astrophysics Data System (ADS)

    Kremmel, Johannes; Lamprecht, Tobias; Crameri, Nino; Michler, Markus

    2017-02-01

    A silicon device to simplify the coupling of multiple single-mode fibers to embedded single-mode waveguides has been developed. The silicon device features alignment structures that enable a passive alignment of fibers to integrated waveguides. For passive alignment, precisely machined V-grooves on a silicon device are used and the planar lightwave circuit board features high-precision structures acting as a mechanical stop. The approach has been tested for up to eight fiber-to-waveguide connections. The alignment approach, the design, and the fabrication of the silicon device as well as the assembly process are presented. The characterization of the fiber-to-waveguide link reveals total coupling losses of (0.45±0.20 dB) per coupling interface, which is significantly lower than the values reported in earlier works. Subsequent climate tests reveal that the coupling losses remain stable during thermal cycling but increases significantly during an 85°C/85 Rh-test. All applied fabrication and bonding steps have been performed using standard MOEMS fabrication and packaging processes.

  13. Preparation of active 3D film patches via aligned fiber electrohydrodynamic (EHD) printing.

    PubMed

    Wang, Jun-Chuan; Zheng, Hongxia; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

    2017-03-08

    The design, preparation and application of three-dimensional (3D) printed structures have gained appreciable interest in recent times, particularly for drug dosage development. In this study, the electrohydrodynamic (EHD) printing technique was developed to fabricate aligned-fiber antibiotic (tetracycline hydrochloride, TE-HCL) patches using polycaprolactone (PCL), polyvinyl pyrrolidone (PVP) and their composite system (PVP-PCL). Drug loaded 3D patches possessed perfectly aligned fibers giving rise to fibrous strut orientation, variable inter-strut pore size and controlled film width (via layering). The effect of operating parameters on fiber deposition and alignment were explored, and the impact of the film structure, composition and drug loading was evaluated. FTIR demonstrated successful TE-HCL encapsulation in aligned fibers. Patches prepared using PVP and TE-HCL displayed enhanced hydrophobicity. Tensile tests exhibited changes to mechanical properties arising from additive effects. Release of antibiotic from PCL-PVP dosage forms was shown over 5 days and was slower compared to pure PCL or PVP. The printed patch void size also influenced antibiotic release behavior. The EHDA printing technique provides an exciting opportunity to tailor dosage forms in a single-step with minimal excipients and operations. These developments are crucial to meet demands where dosage forms cannot be manufactured rapidly or when a personalized approach is required.

  14. Cellulose-polymer-Ag nanocomposite fibers for antibacterial fabrics/skin scaffolds.

    PubMed

    Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Varaprasad, Kokkarachedu; Sadiku, Rotimi; Ray, S Sinha; Mohana Raju, Konduru

    2013-04-02

    Natural carbohydrates (polysaccharides): gum acacia (GA) and gaur gum (GG) were employed in dilute solutions: 0.3%, 0.5% and 0.7% (w/v), as effective reductants for the green synthesis of silver nanoparticles (AgNPs) from AgNO3. The formed AgNPs were impregnated into cellulose fibers after confirming their formation by utilizing ultraviolet-visible (UV-vis) spectral studies, Fourier transforms infrared (FTIR) and transmission electron microscopy (TEM). The surface morphology of the developed cellulose-silver nanocomposite fibers (CSNCFs) were examined with scanning electron microscope-energy dispersive spectroscopy (SEM-EDS). The thermal stability and mechanical properties of the CSNCFs were found to be better than cellulose fibers alone. The antibacterial activity of the nanocomposites was studied by inhibition zone method against Escherichia coli, which suggested that the developed CSNCFs can function effectively as anti-microbial agents. Hence, the developed CSNCFs can effectively used for tissue scaffolding.

  15. Alignment of carbon nanotubes and reinforcing effects in nylon-6 polymer composite fibers

    NASA Astrophysics Data System (ADS)

    Rangari, Vijaya K.; Yousuf, Mohammed; Jeelani, Shaik; Pulikkathara, Merlyn X.; Khabashesku, Valery N.

    2008-06-01

    Alignment of pristine carbon nanotubes (P-CNTs) and fluorinated carbon nanotubes (F-CNTs) in nylon-6 polymer composite fibers (PCFs) has been achieved using a single-screw extrusion method. CNTs have been used as filler reinforcements to enhance the mechanical and thermal properties of nylon-6 composite fibers. The composites were fabricated by dry mixing nylon-6 polymer powder with the CNTs as the first step, then followed by the melt extrusion process of fiber materials in a single-screw extruder. The extruded fibers were stretched to their maxima and stabilized using a godet set-up. Finally, fibers were wound on a Wayne filament winder machine and tested for their tensile and thermal properties. The tests have shown a remarkable change in mechanical and thermal properties of nylon-6 polymer fibers with the addition of 0.5 wt% F-CNTs and 1.0 wt% of P-CNTs. To draw a comparison between the improvements achieved, the same process has been repeated with neat nylon-6 polymer. As a result, tensile strength has been increased by 230% for PCFs made with 0.5% F-CNTs and 1% P-CNTs as additives. These fibers have been further characterized by DSC, Raman spectroscopy and SEM which confirm the alignment of CNTs and interfacial bonding to nylon-6 polymer matrix.

  16. Alignment of carbon nanotubes and reinforcing effects in nylon-6 polymer composite fibers.

    PubMed

    Rangari, Vijaya K; Yousuf, Mohammed; Jeelani, Shaik; Pulikkathara, Merlyn X; Khabashesku, Valery N

    2008-06-18

    Alignment of pristine carbon nanotubes (P-CNTs) and fluorinated carbon nanotubes (F-CNTs) in nylon-6 polymer composite fibers (PCFs) has been achieved using a single-screw extrusion method. CNTs have been used as filler reinforcements to enhance the mechanical and thermal properties of nylon-6 composite fibers. The composites were fabricated by dry mixing nylon-6 polymer powder with the CNTs as the first step, then followed by the melt extrusion process of fiber materials in a single-screw extruder. The extruded fibers were stretched to their maxima and stabilized using a godet set-up. Finally, fibers were wound on a Wayne filament winder machine and tested for their tensile and thermal properties. The tests have shown a remarkable change in mechanical and thermal properties of nylon-6 polymer fibers with the addition of 0.5 wt% F-CNTs and 1.0 wt% of P-CNTs. To draw a comparison between the improvements achieved, the same process has been repeated with neat nylon-6 polymer. As a result, tensile strength has been increased by 230% for PCFs made with 0.5% F-CNTs and 1% P-CNTs as additives. These fibers have been further characterized by DSC, Raman spectroscopy and SEM which confirm the alignment of CNTs and interfacial bonding to nylon-6 polymer matrix.

  17. Image-based, fiber guiding scaffolds: a platform for regenerating tissue interfaces.

    PubMed

    Park, Chan Ho; Rios, Hector F; Taut, Andrei D; Padial-Molina, Miguel; Flanagan, Colleen L; Pilipchuk, Sophia P; Hollister, Scott J; Giannobile, William V

    2014-07-01

    In the oral and craniofacial complex, tooth loss is the most commonly acquired disfiguring injury. Among the most formidable challenges of reconstructing tooth-supporting osseous defects in the oral cavity is the regeneration of functional multi-tissue complexes involving bone, ligament, and tooth cementum. Furthermore, periodontal multi-tissue engineering with spatiotemporal orientation of the periodontal ligament (PDL) remains the most challenging obstacle for restoration of physiological loading and homeostasis. We report on the ability of a hybrid computer-designed scaffold--developed utilizing computed tomography--to predictably facilitate the regeneration and integration of dental supporting tissues. Here, we provide the protocol for rapid prototyping, manufacture, surgical implantation, and evaluation of dual-architecture scaffolds for controlling fiber orientation and facilitating morphogenesis of bone-ligament complexes. In contrast to conventional single-system methods of fibrous tissue formation, our protocol supports rigorous control of multi-compartmental scaffold architecture using computational scaffold design and manufacturing by 3D printing, as well as the evaluation of newly regenerated tissue physiology for clinical implementation.

  18. Polymeric Optical Waveguide with Plastic Optical Fiber Guides for Passive Alignment Fabricated by Hot Embossing

    NASA Astrophysics Data System (ADS)

    Mizuno, Hirotaka; Jordan, Shane; Sugihara, Okihiro; Kaino, Toshikuni; Okamoto, Naomichi; Ohama, Motoshi

    2004-11-01

    The simple fabrication of a passive alignment structure, and the simple connection of polymeric optical waveguides (POWs) and plastic optical fibers (POFs) are presented. Optical waveguides with large core sizes of 500 and 1000 μm were fabricated, and a low propagation loss of 0.21-0.23 dB/cm at 650 nm was achieved in these waveguides. Using a structure with the same core and fiber guide patterns as the master, a passive alignment structure was fabricated easily by hot embossing. POWs directly connected to POFs with passive alignment were realized and the coupling loss from POF to POF through POW was measured to be 1.6 dB at an optimum core width of 900 μm for 980 μm core size POFs.

  19. Flow perfusion enhances the calcified matrix deposition of marrow stromal cells in biodegradable nonwoven fiber mesh scaffolds.

    PubMed

    Sikavitsas, Vassilios I; Bancroft, Gregory N; Lemoine, Jeremy J; Liebschner, Michael A K; Dauner, Martin; Mikos, Antonios G

    2005-01-01

    In this study, we report on the ability of resorbable poly(L-lactic acid) (PLLA) nonwoven scaffolds to support the attachment, growth, and differentiation of marrow stromal cells (MSCs) under fluid flow. Rat MSCs were isolated from young male Wistar rats and expanded using established methods. The cells were then seeded on PLLA nonwoven fiber meshes. The PLLA nonwoven fiber meshes had 99% porosity, 17 microm fiber diameter, 10 mm scaffold diameter, and 1.7-mm thickness. The nonwoven PLLA meshes were seeded with a cell suspension of 5 x 10(5) cells in 300 microl, and cultured in a flow perfusion bioreactor and under static conditions. Cell/polymer nonwoven scaffolds cultured under flow perfusion had significantly higher amounts of calcified matrix deposited on them after 16 days of culture. Microcomputed tomography revealed that the in vitro generated extracellular matrix in the scaffolds cultured under static conditions was denser at the periphery of the scaffold while in the scaffolds cultured in the perfusion bioreactor the extracellular matrix demonstrated a more homogeneous distribution. These results show that flow perfusion accelerates the proliferation and differentiation of MSCs, seeded on nonwoven PLLA scaffolds, toward the osteoblastic phenotype, and improves the distribution of the in vitro generated calcified extracellular matrix.

  20. Mechanochromic photonic-crystal fibers based on continuous sheets of aligned carbon nanotubes.

    PubMed

    Sun, Xuemei; Zhang, Jing; Lu, Xin; Fang, Xin; Peng, Huisheng

    2015-03-16

    A new family of mechanochromic photonic-crystal fibers exhibits tunable structural colors under stretching. This novel mechanochromic fiber is prepared by depositing polymer microspheres onto a continuous aligned-carbon-nanotube sheet that has been wound on an elastic poly(dimethylsiloxane) fiber, followed by further embedding in poly(dimethylsiloxane). The color of the fiber can be tuned by varying the size and the center-to-center distance of the polymer spheres. It further experiences reversible and rapid multicolor changes during the stretch and release processes, for example, between red, green, and blue. Both the high sensitivity and stability were maintained after 1000 deformation cycles. These elastic photonic-crystal fibers were woven into patterns and smart fabrics for various display and sensing applications.

  1. In vitro performance of 13-93 bioactive glass fiber and trabecular scaffolds with MLO-A5 osteogenic cells.

    PubMed

    Modglin, Vernon C; Brown, Roger F; Fu, Qiang; Rahaman, Mohamed N; Jung, Steven B; Day, Delbert E

    2012-10-01

    This in vitro study was performed to evaluate the ability of two types of porous bioactive glass scaffolds to support the growth and differentiation of an established osteogenic cell line. The two scaffold types tested included 13-93 glass fiber and trabecular-like scaffolds seeded with murine MLO-A5 cells and cultured for intervals of 2 to 12 days. Culture in MTT-containing medium showed metabolically active cells both on the surface and within the interior of the scaffolds. Scanning electron microscopy revealed well-attached cells on both types of scaffolds with a continual increase in cell density over a 6-day period. Protein measurements also showed a linear increase in cell density during the incubation. Activity of alkaline phosphatase, a key indicator of osteoblast differentiation, increased about 10-fold during the 6-day incubation with both scaffold types. The addition of mineralization media to MLO-A5 seeded scaffolds triggered extensive formation of alizarin red-positive mineralized extracellular material, additional evidence of cell differentiation and completion of the final step of bone formation on the constructs. Collectively, the results indicate that the 13-93 glass fiber and trabecular scaffolds promote the attachment, growth, and differentiation of MLO-A5 osteogenic cells and could potentially be used for bone tissue engineering applications.

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

    PubMed

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

    2017-02-08

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

  3. High finesse optical fiber cavities: optimal alignment and robust stabilization (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ratschbacher, Lothar; Gallego, Jose; Ghosh, Sutapa; Alavi, Seyed; Alt, Wolfgang; Martinez-Dorantes, Miguel; Meschede, Dieter

    2016-04-01

    Fiber Fabry-Perot cavities, formed by micro-machined mirrors on the end-facets of optical fibers, are used in an increasing number of technical and scientific applications. Some of the most promising areas of application of these optical micro-resonators with high finesse and small mode volume are in the field of quantum communication and information. The resonator-enhanced light-matter interaction, for instance, provide basis for the realization of efficient optical interfaces between stationary matter-based quantum nodes and flying single-photon qubits. To date fiber Fabry-Perot cavities have been successfully applied in experiments interfacing single photons with a wide range of quantum systems, including cold atoms, ions and solid state emitters as well as quantum optomechanical experiments. Here we address some important practical questions that arise during the experimental implementation of high finesse fiber Fabry-Perot cavities: How can optimal fiber cavity alignment be achieved and how can the efficiency of coupling light from the optical fibers to the cavity mode and vice versa be characterized? How should optical fiber cavities be constructed and stabilized to fulfill their potential for miniaturization and integration into robust scientific and technological devices that can operate outside of dedicated laboratory environments in the future? The first two questions we answer with an analytic mode matching calculation that relates the alignment dependent fiber-to-cavity mode-matching efficiency to the easily measurable dip in the reflected light power at the cavity resonance. Our general analysis provides a simple recipe for the optimal alignment of fiber Fabry-Perot cavities and moreover for the first time explains the asymmetry in their reflective line shapes. The latter question we explore by investigating a novel, intrinsically rigid fiber cavity design that makes use of the high passive stability of a monolithic cavity spacer and employs thermal

  4. Extracellular Recordings of Patterned Human Pluripotent Stem Cell-Derived Cardiomyocytes on Aligned Fibers

    PubMed Central

    Minami, Itsunari; Yu, Leqian; Nakajima, Minako; Qiao, Jing; Shimono, Ken; Nakatsuji, Norio; Kotera, Hitetoshi; Chen, Yong

    2016-01-01

    Human induced pluripotent stem cell (hiPSC) derived cardiomyocytes (CMs) hold high potential for use in drug assessment and myocardial regeneration. To create tissue-like constructs of CMs for extracellular monitoring, we placed aligned fibers (AFs) on the surface of a microelectrode array and then seeded hiPSC-CMs for subsequent monitoring for 14 days. As expected, the CMs organized into anisotropic and matured tissue and the extracellular recordings showed reduced premature beating higher signal amplitude and a higher probability of T-wave detection as compared to the culture without fibers. The CMs on the aligned fibers samples also exhibited anisotropic propagation of the field potential. These results therefore suggest that the hiPSC-CMs cultured on AFs can be used more reliably for cell based assays. PMID:27446217

  5. Diagnostic apparatus and method for use in the alignment of one or more laser means onto a fiber optics interface

    DOEpatents

    Johnson, S.A.; Shannon, R.R.

    1985-01-18

    Diagnostic apparatus for use in determining the proper alignment of a plurality of laser beams onto a fiber optics interface is disclosed. The apparatus includes a lens assembly which serves two functions, first to focus a plurality of laser beams onto the fiber optics interface, and secondly to reflect and image the interface using scattered light to a monitor means. The monitor means permits indirect observation of the alignment or focusing of the laser beams onto the fiber optics interface.

  6. Diagnostic apparatus and method for use in the alignment of one or more laser means onto a fiber optics interface

    DOEpatents

    Johnson, Steve A.; Shannon, Robert R.

    1987-01-01

    Diagnostic apparatus for use in determining the proper alignment of a plurality of laser beams onto a fiber optics interface is disclosed. The apparatus includes a lens assembly which serves two functions, first to focus a plurality of laser beams onto the fiber optics interface, and secondly to reflect and image the interface using scattered light to a monitor means. The monitor means permits indirect observation of the alignment or focusing of the laser beams onto the fiber optics interface.

  7. Development of Chitosan Scaffolds with Enhanced Mechanical Properties for Intestinal Tissue Engineering Applications.

    PubMed

    Zakhem, Elie; Bitar, Khalil N

    2015-10-13

    Massive resections of segments of the gastrointestinal (GI) tract lead to intestinal discontinuity. Functional tubular replacements are needed. Different scaffolds were designed for intestinal tissue engineering application. However, none of the studies have evaluated the mechanical properties of the scaffolds. We have previously shown the biocompatibility of chitosan as a natural material in intestinal tissue engineering. Our scaffolds demonstrated weak mechanical properties. In this study, we enhanced the mechanical strength of the scaffolds with the use of chitosan fibers. Chitosan fibers were circumferentially-aligned around the tubular chitosan scaffolds either from the luminal side or from the outer side or both. Tensile strength, tensile strain, and Young's modulus were significantly increased in the scaffolds with fibers when compared with scaffolds without fibers. Burst pressure was also increased. The biocompatibility of the scaffolds was maintained as demonstrated by the adhesion of smooth muscle cells around the different kinds of scaffolds. The chitosan scaffolds with fibers provided a better candidate for intestinal tissue engineering. The novelty of this study was in the design of the fibers in a specific alignment and their incorporation within the scaffolds.

  8. Development of Chitosan Scaffolds with Enhanced Mechanical Properties for Intestinal Tissue Engineering Applications

    PubMed Central

    Zakhem, Elie; Bitar, Khalil N.

    2015-01-01

    Massive resections of segments of the gastrointestinal (GI) tract lead to intestinal discontinuity. Functional tubular replacements are needed. Different scaffolds were designed for intestinal tissue engineering application. However, none of the studies have evaluated the mechanical properties of the scaffolds. We have previously shown the biocompatibility of chitosan as a natural material in intestinal tissue engineering. Our scaffolds demonstrated weak mechanical properties. In this study, we enhanced the mechanical strength of the scaffolds with the use of chitosan fibers. Chitosan fibers were circumferentially-aligned around the tubular chitosan scaffolds either from the luminal side or from the outer side or both. Tensile strength, tensile strain, and Young’s modulus were significantly increased in the scaffolds with fibers when compared with scaffolds without fibers. Burst pressure was also increased. The biocompatibility of the scaffolds was maintained as demonstrated by the adhesion of smooth muscle cells around the different kinds of scaffolds. The chitosan scaffolds with fibers provided a better candidate for intestinal tissue engineering. The novelty of this study was in the design of the fibers in a specific alignment and their incorporation within the scaffolds. PMID:26473937

  9. Self-centering fiber alignment structures for high-precision field installable single-mode fiber connectors

    NASA Astrophysics Data System (ADS)

    Van Erps, Jürgen; Ebraert, Evert; Gao, Fei; Vervaeke, Michael; Berghmans, Francis; Beri, Stefano; Watté, Jan; Thienpont, Hugo

    2014-05-01

    There is a steady increase in the demand for internet bandwidth, primarily driven by cloud services and high-definition video streaming. Europe's Digital Agenda states the ambitious objective that by 2020 all Europeans should have access to internet at speeds of 30Mb/s or above, with 50% or more of households subscribing to connections of 100Mb/s. Today however, internet access in Europe is mainly based on the first generation of broadband, meaning internet accessed over legacy telephone copper and TV cable networks. In recent years, Fiber-To-The-Home (FTTH) networks have been adopted as a replacement of traditional electrical connections for the `last mile' transmission of information at bandwidths over 1Gb/s. However, FTTH penetration is still very low (< 5%) in most major Western economies. The main reason for this is the high deployment cost of FTTH networks. Indeed, the success and adoption of optical access networks critically depend on the quality and reliability of connections between optical fibers. In particular a further reduction of insertion loss of field- installable connectors must be achieved without a significant increase in component cost. This requires precise alignment of fibers that can differ in terms of ellipticity, eccentricity or diameter and seems hardly achievable using today's widespread ferrule-based alignment systems. In this paper, we present a field-installable connector based on deflectable/compressible spring structures, providing a self-centering functionality for the fiber. This way, it can accommodate for possible fiber cladding diameter variations (the tolerance on the cladding diameter of G.652 fiber is typically +/-0.7μm). The mechanical properties of the cantilever are derived through an analytical approximation and a mathematical model of the spring constant, and finite element-based simulations are carried out to find the maximum first principal stress as well as the stress distribution distribution in the fiber alignment

  10. Optical Dichroism in Fibers of Aligned SWNT Inferred from Polarized Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Alldredge, J. W.; Gommans, H. H.; Tashiro, H.; Park, J.; Magnuson, J.; Rinzler, A. G.

    2000-03-01

    To probe the 1D nature of single wall carbon nanotubes (SWNT) in bulk samples we devised a method for generating fibers of aligned SWNT. We measured polarization dependent Raman spectra on the oriented fibers to verify mode assignments appearing in the literature. Surprisingly, ALL the Raman line intensities are observed to decrease in EQUAL amounts for 647.1 nm laser excitation polarized perpendicular to the fiber axis versus that polarized parallel to the fiber axis. We attribute this anisotropy to a consequence of the 1D nature of the nanotubes. The strong Raman signal from SWNT has been ascribed to resonance Raman scattering with optical transitions between van Hove singularities in the 1D density of states. When the excitation is polarized along the nanotube axis it excites transitions between these singularities in the (metallic) nanotubes of the sample. For the polarization perpendicular to the nanotube axis, evidently no such optical transitions (resonant with our laser) are available, yielding the uniformly smaller Raman signal. The fibers thus exhibit optical dichroism. This effect frustrates the use of polarized Raman spectroscopy for identification of vibration mode symmetries, however the Raman polarization ratio provides a convenient measure of the degree of SWNT alignment in the fibers .

  11. Fatigue and human umbilical cord stem cell seeding characteristics of calcium phosphate-chitosan-biodegradable fiber scaffolds.

    PubMed

    Zhao, Liang; Burguera, Elena F; Xu, Hockin H K; Amin, Nikhil; Ryou, Heon; Arola, Dwayne D

    2010-02-01

    Calcium phosphate cement (CPC) has in situ-setting ability and bioactivity, but the brittleness and low strength limit CPC to only non-load-bearing bone repairs. Human umbilical cord mesenchymal stem cells (hUCMSCs) can be harvested without an invasive procedure required for the commonly studied bone marrow MSCs. However, little has been reported on hUCMSC delivery via bioactive scaffolds for bone tissue engineering. The objectives of this study were to develop CPC scaffolds with improved resistance to fatigue and fracture, and to investigate hUCMSC delivery for bone tissue engineering. In fast fracture, CPC with 15% chitosan and 20% polyglactin fibers (CPC-chitosan-fiber scaffold) had flexural strength of 26mPa, higher than 10mPa for CPC control (p<0.05). In cyclic loading, CPC-chitosan-fiber specimens that survived 2x10(6) cycles had the maximum stress of 10MPa, compared to 5MPa of CPC control. CPC-chitosan-fiber specimens that failed after multiple cycles had a mean stress-to-failure of 9MPa, compared to 5.8MPa for CPC control (p<0.05). hUCMSCs showed excellent viability when seeded on CPC and CPC-chitosan-fiber scaffolds. The percentage of live cells reached 96-99%. Cell density was about 300cells/mm(2) at day 1; it proliferated to 700cells/mm(2) at day 4. Wst-1 assay showed that the stronger CPC-chitosan-fiber scaffold had hUCMSC viability that matched the CPC control (p>0.1). In summary, this study showed that chitosan and polyglactin fibers substantially increased the fatigue resistance of CPC, and that hUCMSCs had excellent proliferation and viability on the scaffolds.

  12. Micro-vision servo control of a multi-axis alignment system for optical fiber assembly

    NASA Astrophysics Data System (ADS)

    Chen, Weihai; Yu, Fei; Qu, Jianliang; Chen, Wenjie; Zhang, Jianbin

    2017-04-01

    This paper describes a novel optical fiber assembly system featuring a multi-axis alignment function based on micro-vision feedback control. It consists of an active parallel alignment mechanism, a passive compensation mechanism, a micro-gripper and a micro-vision servo control system. The active parallel alignment part is a parallelogram-based design with remote-center-of-motion (RCM) function to achieve precise rotation without fatal lateral motion. The passive mechanism, with five degrees of freedom (5-DOF), is used to implement passive compensation for multi-axis errors. A specially designed 1-DOF micro-gripper mounted onto the active parallel alignment platform is adopted to grasp and rotate the optical fiber. A micro-vision system equipped with two charge-coupled device (CCD) cameras is introduced to observe the small field of view and obtain multi-axis errors for servo feedback control. The two CCD cameras are installed in an orthogonal arrangement—thus the errors can be easily measured via the captured images. Meanwhile, a series of tracking and measurement algorithms based on specific features of the target objects are developed. Details of the force and displacement sensor information acquisition in the assembly experiment are also provided. An experiment demonstrates the validity of the proposed visual algorithm by achieving the task of eliminating errors and inserting an optical fiber to the U-groove accurately.

  13. Electro-magnetic properties of composites with aligned Fe-Co hollow fibers

    NASA Astrophysics Data System (ADS)

    Cho, Seungchan; Choi, Jae Ryung; Jung, Byung Mun; Choi, U. Hyeok; Lee, Sang-Kwan; Kim, Ki Hyeon; Lee, Sang-Bok

    2016-05-01

    A novel Fe-Co binary hollow fiber was synthesized by electroless plating using hydrolyzed polyester fiber and its anisotropy characteristic was investigated for electromagnetic wave absorbing materials. The hollow fibers in parallel with magnetic field show higher saturated magnetization of 202 emu/g at the applied magnetic field of 10 kOe and lower coercivity (27.658 Oe), compared with the random and vertical oriented hollow fibers. From complex permittivity measurement, the Fe-Co hollow fiber composites clearly display a single dielectric resonance, located at ˜14 GHz. The Fe-Co hollow fibers not only provide excellent EM properties in GHz frequency ranges, resulting mainly from the strong resonance, but also adjust the soft magnetic properties through fiber alignments. The cavitary structure of the Fe-Co hollow fibers, not only giving rise to a dielectric loss resonance and also adjusting its peak frequency, may be a pathway to useful EM wave absorptive devices in GHz frequency ranges.

  14. Carbon-nanotube-interfaced glass fiber scaffold for regeneration of transected sciatic nerve.

    PubMed

    Ahn, Hong-Sun; Hwang, Ji-Young; Kim, Min Soo; Lee, Ja-Yeon; Kim, Jong-Wan; Kim, Hyun-Soo; Shin, Ueon Sang; Knowles, Jonathan C; Kim, Hae-Won; Hyun, Jung Keun

    2015-02-01

    Carbon nanotubes (CNTs), with their unique and unprecedented properties, have become very popular for the repair of tissues, particularly for those requiring electrical stimuli. Whilst most reports have demonstrated in vitro neural cell responses of the CNTs, few studies have been performed on the in vivo efficacy of CNT-interfaced biomaterials in the repair and regeneration of neural tissues. Thus, we report here for the first time the in vivo functions of CNT-interfaced nerve conduits in the regeneration of transected rat sciatic nerve. Aminated CNTs were chemically tethered onto the surface of aligned phosphate glass microfibers (PGFs) and CNT-interfaced PGFs (CNT-PGFs) were successfully placed into three-dimensional poly(L/D-lactic acid) (PLDLA) tubes. An in vitro study confirmed that neurites of dorsal root ganglion outgrew actively along the aligned CNT-PGFs and that the CNT interfacing significantly increased the maximal neurite length. Sixteen weeks after implantation of a CNT-PGF nerve conduit into the 10 mm gap of a transected rat sciatic nerve, the number of regenerating axons crossing the scaffold, the cross-sectional area of the re-innervated muscles and the electrophysiological findings were all significantly improved by the interfacing with CNTs. This first in vivo effect of using a CNT-interfaced scaffold in the regeneration process of a transected rat sciatic nerve strongly supports the potential use of CNT-interfaced PGFs at the interface between the nerve conduit and peripheral neural tissues.

  15. Effective combination of hydrostatic pressure and aligned nanofibrous scaffolds on human bladder smooth muscle cells: implication for bladder tissue engineering.

    PubMed

    Ahvaz, Hana Hanaee; Soleimani, Masoud; Mobasheri, Hamid; Bakhshandeh, Behnaz; Shakhssalim, Naser; Soudi, Sara; Hafizi, Maryam; Vasei, Mohammad; Dodel, Masumeh

    2012-09-01

    Bladder tissue engineering has been the focus of many studies due to its highly therapeutic potential. In this regard many aspects such as biochemical and biomechanical factors need to be studied extensively. Mechanical stimulations such as hydrostatic pressure and topology of the matrices are critical features which affect the normal functions of cells involved in bladder regeneration. In this study, hydrostatic pressure (10 cm H(2)O) and stretch forces were exerted on human bladder smooth muscle cells (hBSMCs) seeded on aligned nanofibrous polycaprolactone/PLLA scaffolds, and the alterations in gene and protein expressions were studied. The gene transcription patterns for collagen type I, III, IV, elastin, α-SMA, calponin and caldesmon were monitored on days 3 and 5 quantitatively. Changes in the expressions of α-SMA, desmin, collagen type I and III were quantified by Enzyme-linked immuno-sorbent assay. The scaffolds were characterized using scanning electron microscope, contact angle measurement and tensile testing. The positive effect of mechanical forces on the functional improvement of the engineered tissue was supported by translational down-regulation of α-SMA and VWF, up-regulation of desmin and improvement of collagen type III:I ratio. Altogether, our study reveals that proper hydrostatic pressure in combination with appropriate surface stimulation on hBSMCs causes a tissue-specific phenotype that needs to be considered in bladder tissue engineering.

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

    PubMed

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

    2014-10-01

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

  17. Three-dimensional aligned nanofibers-hydrogel scaffold for controlled non-viral drug/gene delivery to direct axon regeneration in spinal cord injury treatment

    PubMed Central

    Nguyen, Lan Huong; Gao, Mingyong; Lin, Junquan; Wu, Wutian; Wang, Jun; Chew, Sing Yian

    2017-01-01

    Spinal cord injuries (SCI) often lead to persistent neurological dysfunction due to failure in axon regeneration. Unfortunately, currently established treatments, such as direct drug administration, do not effectively treat SCI due to rapid drug clearance from our bodies. Here, we introduce a three-dimensional aligned nanofibers-hydrogel scaffold as a bio-functionalized platform to provide sustained non-viral delivery of proteins and nucleic acid therapeutics (small non-coding RNAs), along with synergistic contact guidance for nerve injury treatment. A hemi-incision model at cervical level 5 in the rat spinal cord was chosen to evaluate the efficacy of this scaffold design. Specifically, aligned axon regeneration was observed as early as one week post-injury. In addition, no excessive inflammatory response and scar tissue formation was triggered. Taken together, our results demonstrate the potential of our scaffold for neural tissue engineering applications. PMID:28169354

  18. Three-dimensional aligned nanofibers-hydrogel scaffold for controlled non-viral drug/gene delivery to direct axon regeneration in spinal cord injury treatment.

    PubMed

    Nguyen, Lan Huong; Gao, Mingyong; Lin, Junquan; Wu, Wutian; Wang, Jun; Chew, Sing Yian

    2017-02-07

    Spinal cord injuries (SCI) often lead to persistent neurological dysfunction due to failure in axon regeneration. Unfortunately, currently established treatments, such as direct drug administration, do not effectively treat SCI due to rapid drug clearance from our bodies. Here, we introduce a three-dimensional aligned nanofibers-hydrogel scaffold as a bio-functionalized platform to provide sustained non-viral delivery of proteins and nucleic acid therapeutics (small non-coding RNAs), along with synergistic contact guidance for nerve injury treatment. A hemi-incision model at cervical level 5 in the rat spinal cord was chosen to evaluate the efficacy of this scaffold design. Specifically, aligned axon regeneration was observed as early as one week post-injury. In addition, no excessive inflammatory response and scar tissue formation was triggered. Taken together, our results demonstrate the potential of our scaffold for neural tissue engineering applications.

  19. Alignment of Carbon Nanotubes in Carbon Nanotube Fibers Through Nanoparticles: A Route for Controlling Mechanical and Electrical Properties.

    PubMed

    Hossain, Muhammad Mohsin; Islam, Md Akherul; Shima, Hossain; Hasan, Mudassir; Lee, Moonyong

    2017-02-15

    This is the first study that describes how semiconducting ZnO can act as an alignment agent in carbon nanotubes (CNTs) fibers. Because of the alignment of CNTs through the ZnO nanoparticles linking groups, the CNTs inside the fibers were equally distributed by the attraction of bonding forces into sheetlike bunches, such that any applied mechanical breaking load was equally distributed to each CNT inside the fiber, making them mechanically robust against breaking loads. Although semiconductive ZnO nanoparticles were used here, the electrical conductivity of the aligned CNT fiber was comparable to bare CNT fibers, suggesting that the total electron movement through the CNTs inside the aligned CNT fiber is not disrupted by the insulating behavior of ZnO nanoparticles. A high degree of control over the electrical conductivity was also demonstrated by the ZnO nanoparticles, working as electron movement bridges between CNTs in the longitudinal and crosswise directions. Well-organized surface interface chemistry was also observed, which supports the notion of CNT alignment inside the fibers. This research represents a new area of surface interface chemistry for interfacially linked CNTs and ZnO nanomaterials with improved mechanical properties and electrical conductivity within aligned CNT fibers.

  20. Image-Based, Fiber Guiding Scaffolds: A Platform for Regenerating Tissue Interfaces

    PubMed Central

    Park, Chan Ho; Rios, Hector F.; Taut, Andrei D.; Padial-Molina, Miguel; Flanagan, Colleen L.; Pilipchuk, Sophia P.; Hollister, Scott J.

    2014-01-01

    In the oral and craniofacial complex, tooth loss is the most commonly acquired disfiguring injury. Among the most formidable challenges of reconstructing tooth-supporting osseous defects in the oral cavity is the regeneration of functional multi-tissue complexes involving bone, ligament, and tooth cementum. Furthermore, periodontal multi-tissue engineering with spatiotemporal orientation of the periodontal ligament (PDL) remains the most challenging obstacle for restoration of physiological loading and homeostasis. We report on the ability of a hybrid computer-designed scaffold—developed utilizing computed tomography—to predictably facilitate the regeneration and integration of dental supporting tissues. Here, we provide the protocol for rapid prototyping, manufacture, surgical implantation, and evaluation of dual-architecture scaffolds for controlling fiber orientation and facilitating morphogenesis of bone-ligament complexes. In contrast to conventional single-system methods of fibrous tissue formation, our protocol supports rigorous control of multi-compartmental scaffold architecture using computational scaffold design and manufacturing by 3D printing, as well as the evaluation of newly regenerated tissue physiology for clinical implementation. PMID:24188695

  1. Three-dimensional functional human neuronal networks in uncompressed low-density electrospun fiber scaffolds.

    PubMed

    Jakobsson, Albin; Ottosson, Maximilian; Zalis, Marina Castro; O'Carroll, David; Johansson, Ulrica Englund; Johansson, Fredrik

    2017-01-05

    We demonstrate an artificial three-dimensional (3D) electrical active human neuronal network system, by the growth of brain neural progenitors in highly porous low density electrospun poly-ε-caprolactone (PCL) fiber scaffolds. In neuroscience research cell-based assays are important experimental instruments for studying neuronal function in health and disease. Traditional cell culture at 2D-surfaces induces abnormal cell-cell contacts and network formation. Hence, there is a tremendous need to explore in vivo-resembling 3D neural cell culture approaches. We present an improved electrospinning method for fabrication of scaffolds that promote neuronal differentiation into highly 3D integrated networks, formation of inhibitory and excitatory synapses and extensive neurite growth. Notably, in 3D scaffolds in vivo-resembling intermixed neuronal and glial cell network were formed, whereas in parallel 2D cultures a neuronal cell layer grew separated from an underlying glial cell layer. Hence, the use of the 3D cell assay presented will most likely provide more physiological relevant results.

  2. Quantitative mapping of collagen fiber alignment in thick tissue samples using transmission polarized-light microscopy

    NASA Astrophysics Data System (ADS)

    Yakovlev, Dmitry D.; Shvachkina, Marina E.; Sherman, Maria M.; Spivak, Andrey V.; Pravdin, Alexander B.; Yakovlev, Dmitry A.

    2016-07-01

    Immersion optical clearing makes it possible to use transmission polarized-light microscopy for characterization of thick (200 to 2000 μm) layers of biological tissues. We discuss polarization properties of thick samples in the context of the problem of characterization of collagen fiber alignment in connective tissues such as sclera and dermis. Optical chirality caused by azimuthal variations of the macroscopic (effective) optic axis of the medium across the sample thickness should be considered in polarization mapping of thick samples of these tissues. We experimentally evaluate to what extent the optical chirality affects the measurement results in typical situations and show under what conditions it can be easily taken into account and does not hinder, but rather helps, in characterization of collagen fiber alignment.

  3. 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.

  4. Modulation of Gene Expression using Electrospun Scaffolds with Templated Architecture

    PubMed Central

    Wang, Y-N; Sanders, J.E.

    2012-01-01

    The fabrication of biomimetic scaffolds is a critical component to fulfill the promise of functional tissue engineered materials. We describe herein a simple technique, based on printed circuit board manufacturing, to produce novel templates for electrospinning scaffolds for tissue engineering applications. This technique facilitates fabrication of electrospun scaffolds with templated architecture, which we defined as a scaffold's bulk mechanical properties being driven by its fiber architecture. Electrospun scaffolds with templated architectures were characterized with regard to fiber alignment and mechanical properties. Fast Fourier transform analysis revealed a high degree of fiber alignment along the conducting traces of the templates. Mechanical testing showed that scaffolds demonstrated tunable mechanical properties as a function of templated architecture. Fibroblast seeded scaffolds were subjected to a peak strain of 3% or 10% at 0.5 Hz for 1 hour. Exposing seeded scaffolds to the low strain magnitude (3%) significantly increased collagen I gene expression compared to the high strain magnitude (10%) in a scaffold architecture dependent manner. These experiments indicate that scaffolds with templated architectures can be produced and modulation of gene expression is possible with templated architectures. This technology holds promise for the long term goal of creating tissue engineered replacements with the biomechanical and biochemical make-up of native tissues. PMID:22447576

  5. The effect of various denier capillary channel polymer fibers on the alignment of NHDF cells and type I collagen.

    PubMed

    Sinclair, Kristofer D; Webb, Ken; Brown, Philip J

    2010-12-15

    If tissue engineers are to successfully repair and regenerate native tendons and ligaments, it will be essential to implement contact guidance to induce cellular and type I collagen alignment to replicate the native structure. Capillary channel polymer (CC-P) fibers fabricated by melt-extrusion have aligned micrometer scale surface channels that may serve the goal of achieving biomimetic, physical templates for ligament growth and regeneration. Previous work characterizing the behavior of normal human dermal fibroblasts (NHDF), on the 19 denier per filament (dpf) CC-P fibers, demonstrated a need for improved cellular and type I collagen alignment. Therefore, 5 and 9 dpf CC-P fibers were manufactured to determine whether their channel dimensions would achieve greater alignment. A 29 dpf CC-P fiber was also examined to determine whether cellular guidance could still be achieved within the larger dimensions of the fiber's channels. The 9 dpf CC-P fiber appeared to approach the topographical constraints necessary to induce the cellular and type I collagen architecture that most closely mirrored that of native ACL tissue. This work demonstrated that the novel cross-section of the CC-P fiber geometry could approach the necessary surface topography to align NHDF cells along the longitudinal axis of each fiber.

  6. bFGF-containing electrospun gelatin scaffolds with controlled nano-architectural features for directed angiogenesis

    PubMed Central

    Montero, Ramon B.; Vial, Ximena; Nguyen, Dat Tat; Farhand, Sepehr; Reardon, Mark; Pham, Si M.; Tsechpenakis, Gavriil; Andreopoulos, Fotios M.

    2011-01-01

    Current therapeutic angiogenesis strategies are focused on the development of biologically responsive scaffolds that can deliver multiple angiogenic cytokines and/or cells in ischemic regions. Herein, we report on a novel electrospinning approach to fabricate cytokine-containing nanofibrous scaffolds with tunable architecture to promote angiogenesis. Fiber diameter and uniformity were controlled by varying the concentration of the polymeric (i.e. gelatin) solution, the feed rate, needle to collector distance, and electric field potential between the collector plate and injection needle. Scaffold fiber orientation (random vs. aligned) was achieved by alternating the polarity of two parallel electrodes placed on the collector plate thus dictating fiber deposition patterns. Basic fibroblast growth factor (bFGF) was physically immobilized within the gelatin scaffolds at variable concentrations and human umbilical vein endothelial cells (HUVEC) were seeded on the top of the scaffolds. Cell proliferation and migration was assessed as a function of growth factor loading and scaffold architecture. HUVECs successfully adhered onto gelatin B scaffolds and cell proliferation was directly proportional to the loading concentrations of the growth factor (0–100 bFGF ng/mL). Fiber orientation had a pronounced effect on cell morphology and orientation. Cells were spread along the fibers of the electrospun scaffolds with the aligned orientation and developed a spindle-like morphology parallel to the scaffold's fibers. In contrast, cells seeded onto the scaffolds with random fiber orientation, did not demonstrate any directionality and appeared to have a rounder shape. Capillary formation (i.e. sprouts length and number of sprouts per bead), assessed in a 3-D in vitro angiogenesis assay, was a function of bFGF loading concentration (0 ng, 50 ng and 100 ng per scaffold) for both types of electrospun scaffolds (i.e. with aligned or random fiber orientation). PMID:22200610

  7. Osteogenic induction of bone marrow-derived stromal cells on simvastatin-releasing, biodegradable, nano- to microscale fiber scaffolds.

    PubMed

    Wadagaki, Ryu; Mizuno, Daiki; Yamawaki-Ogata, Aika; Satake, Makoto; Kaneko, Hiroaki; Hagiwara, Sumitaka; Yamamoto, Noriyuki; Narita, Yuji; Hibi, Hideharu; Ueda, Minoru

    2011-07-01

    Tissue engineering is an effective approach for the treatment of bone defects. Statins have been demonstrated to promote osteoblastic differentiation of bone marrow-derived stromal cells (BMSCs). Electrospun biodegradable fibers have also shown applicability to drug delivery in the form of bone tissue engineered scaffolds with nano- to microscale topography and high porosity similar to the natural extracellular matrix (ECM). The aim of this study was to investigate the feasibility of a simvastatin-releasing, biodegradable, nano- to microscale fiber scaffold (SRBFS) for bone tissue engineering with BMSCs. Simvastatin was released from SRBFS slowly. BMSCs were observed to spread actively and rigidly adhere to SRBFS. BMSCs on SRBFS showed an increase in alkaline phosphatase activity 2 weeks after cell culture. Furthermore, osteoclastogenesis was suppressed by SRBFS in vitro. The new bone formation and mineralization in the SRBFS group were significantly better than in the biodegradable fiber scaffold (BFS) without simvastatin 12 weeks after implantation of the cell-scaffold construct into an ectopic site on the murine back. These results suggest that SRBFS promoted osteoblastic differentiation of BMSCs in vitro and in vivo, and demonstrate feasibility as a bone engineering scaffold.

  8. Time-varying gyrocompass alignment for fiber-optic-gyro inertial navigation system with large misalignment angle

    NASA Astrophysics Data System (ADS)

    Ben, Yueyang; Li, Qian; Zhang, Yi; Huo, Liang

    2014-09-01

    Conventional strapdown gyrocompass alignment methods are based on the assumption that the fiber-optic-gyro inertial navigation system has a small azimuth misalignment angle. A large azimuth misalignment angle would lead to an extension of the alignment duration. A time-varying gyrocompass alignment method to solve this problem is provided. An appropriate parameter setting is given for the gyrocompass alignment with a large misalignment angle. Also, a proper protocol for a parametric switch is derived. Simulation and trail results show that the proposed method has better alignment performance than conventional ones, as the system has large misalignment angles.

  9. Winding aligned carbon nanotube composite yarns into coaxial fiber full batteries with high performances.

    PubMed

    Weng, Wei; Sun, Qian; Zhang, Ye; Lin, Huijuan; Ren, Jing; Lu, Xin; Wang, Min; Peng, Huisheng

    2014-06-11

    Inspired by the fantastic and fast-growing wearable electronics such as Google Glass and Apple iWatch, matchable lightweight and weaveable energy storage systems are urgently demanded while remaining as a bottleneck in the whole technology. Fiber-shaped energy storage devices that can be woven into electronic textiles may represent a general and effective strategy to overcome the above difficulty. Here a coaxial fiber lithium-ion battery has been achieved by sequentially winding aligned carbon nanotube composite yarn cathode and anode onto a cotton fiber. Novel yarn structures are designed to enable a high performance with a linear energy density of 0.75 mWh cm(-1). A wearable energy storage textile is also produced with an areal energy density of 4.5 mWh cm(-2).

  10. Biomimetic fiber mesh scaffolds based on gelatin and hydroxyapatite nano-rods: Designing intrinsic skills to attain bone reparation abilities.

    PubMed

    Sartuqui, Javier; Gravina, A Noel; Rial, Ramón; Benedini, Luciano A; Yahia, L'Hocine; Ruso, Juan M; Messina, Paula V

    2016-09-01

    Intrinsic material skills have a deep effect on the mechanical and biological performance of bone substitutes, as well as on its associated biodegradation properties. In this work we have manipulated the preparation of collagenous derived fiber mesh frameworks to display a specific composition, morphology, open macroporosity, surface roughness and permeability characteristics. Next, the effect of the induced physicochemical attributes on the scaffold's mechanical behavior, bone bonding potential and biodegradability were evaluated. It was found that the scaffold microstructure, their inherent surface roughness, and the compression strength of the gelatin scaffolds can be modulated by the effect of the cross-linking agent and, essentially, by mimicking the nano-scale size of hydroxyapatite in natural bone. A clear effect of bioactive hydroxyapatite nano-rods on the scaffolds skills can be appreciated and it is greater than the effect of the cross-linking agent, offering a huge perspective for the upcoming progress of bone implant technology.

  11. Far-infrared spectroscopy of salt penetration into a collagen fiber scaffold.

    PubMed

    Mizuno, Maya; Yamada, Akira; Fukunaga, Kaori; Kojima, Hiroaki

    2015-06-01

    We employed far-infrared spectroscopy to observe the amount of salt that penetrates into collagen fiber masses. The absorption properties of collagen sheets prepared from tilapia skin, bovine skin, rat tail, and sea cucumber dermis were measured using a transmission Fourier transform spectrometer in a band from approximately 100 to 700 cm(-1). We confirmed that the absorbance spectra of the four types of dried collagen sheet show good agreement, even though the amino acid compositions differed. The absorbance peaks observed in the band corresponded to collective vibrations of plural functional groups such as methylene and imino groups in collagen. When salt solution was added to the collagen sheets and then dried, the spectral shapes of the sheets at approximately 166 cm(-1) were clearly different from those of the plain collagen sheets. The differential absorbance between wavenumbers 166 cm(-1) and 250 cm(-1) sensitively reflected the difference between higher-order structures, and the salt diffusion (crystallization) depended on the collagen fiber condition. From these results, we consider that spectral changes can be used for the numerical evaluation of salt penetration into a collagen fiber scaffold.

  12. Cytocompatible cross-linking of electrospun zein fibers for the development of water-stable tissue engineering scaffolds.

    PubMed

    Jiang, Qiuran; Reddy, Narendra; Yang, Yiqi

    2010-10-01

    This paper reports a new method of cross-linking electrospun zein fibers using citric acid as a non-toxic cross-linker to enhance the water stability and cytocompatibility of zein fibers for tissue engineering and other medical applications. The electrospun structure has many advantages over other types of structures and protein-based biomaterials possess unique properties preferred for tissue engineering and other medical applications. However, ultrafine fiber matrices developed from proteins have poor mechanical properties and morphological stability in the aqueous environments required for medical applications. Efforts have been made to improve the water stability of electrospun protein scaffolds using cross-linking and other approaches, but the current methods have major limitations, such as cytotoxicity and low efficiency. In this research electrospun zein fibers were cross-linked with citric acid without using any toxic catalysts. The stability of the cross-linked fibers in phosphate-buffered saline and their ability to support the attachment, spreading and proliferation of mouse fibroblast cells were studied. The cross-linked electrospun fibers retained their ultrafine fibrous structure even after immersion in PBS at 37 degrees C for up to 15 days. Citric acid cross-linked electrospun zein scaffolds showed better attachment, spreading and proliferation of fibroblast cells than uncross-linked electrospun zein fibers, cross-linked zein films and electrospun polylactide fibers.

  13. Design and prototyping of self-centering optical single-mode fiber alignment structures

    NASA Astrophysics Data System (ADS)

    Ebraert, Evert; Gao, Fei; Beri, Stefano; Watté, Jan; Thienpont, Hugo; Van Erps, Jürgen

    2016-06-01

    The European Commission’s goal of providing each European household with at least a 30 Mb s-1 Internet connection by 2020 would be facilitated by a widespread deployment of fibre-to-the-home, which would in turn be sped up by the development of connector essential components, such as high-precision alignment features. Currently, the performance of state-of-the-art physical contact optical fiber connectors is limited by the tolerance on the cladding of standard telecom-grade single-mode fiber (SMF), which is typically smaller than  ±1 μm. We propose to overcome this limit by developing micro-spring-based self-centering alignment structures (SCAS) for SMF-connectors. We design these alignment structures with robustness and low-cost replication in mind, allowing for large-scale deployment. Both theoretical and finite element analysis (FEA) models are used to determine the optimal dimensions of the beams of which the micro-springs of the SCAS are comprised. Two topologies of the SCAS, consisting of three and four micro-springs respectively, are investigated for two materials: polysulfone (PSU) and polyetherimide (PEI). These materials hold great potential for high-performance fiber connectors while being compatible with low-cost production and with the harsh environmental operation conditions of those connectors. The theory and FEA agree well (<3% difference) for a simple micro-spring. When including a pedestal on the micro-spring (to bring it further away from the fiber) and for shorter spring lengths the agreement worsens. This is due to spring compression effects not being taken into account in our theoretical model. Prototypes are successfully fabricated using deep proton writing and subsequently characterized. The controlled insertion of an SMF in the SCAS is investigated and we determine that a force of 0.11 N is required. The fiber insertion also causes an out-of-plane deformation of the micro-springs in the SCAS of about 7 μm, which is no problem for

  14. Macroscopic constitutive relations for elastomers reinforced with short aligned fibers: Instabilities and post-bifurcation response

    NASA Astrophysics Data System (ADS)

    Avazmohammadi, Reza; Ponte Castañeda, Pedro

    2016-12-01

    This paper is concerned with the characterization of the macroscopic response and possible development of instabilities in a certain class of anisotropic composite materials consisting of random distributions of aligned rigid fibers of elliptical cross section in a soft elastomeric matrix, which are subjected to general plane strain loading conditions. For this purpose, use is made of an estimate for the stored-energy function that was derived by Lopez-Pamies and Ponte Castañeda (2006b) for this class of reinforced elastomers by means of the second-order linear comparison homogenization method. This homogenization estimate has been shown to lose strong ellipticity by the development of shear localization bands, when the composite is loaded in compression along the (in-plane) long axes of the fibers. The instability is produced by the sudden, collective rotation of a band of fibers to partially release the high stresses that develop in the elastomer matrix when the composite is compressed along the stiff, long-fiber direction. Consistent with the mode of the impending instability, a lower-energy, post-bifurcation solution is constructed where "striped domain" microstructures consisting of layers with alternating fiber orientations develop in the composite. The volume fractions of the layers and the fiber orientations within the layers adjust themselves to satisfy equilibrium and compatibility across the layers, while remaining compatible with the imposed overall deformation. Mathematically, this construction is shown to correspond to the rank-one convex envelope of the original estimate for the energy, and is further shown to be polyconvex and therefore quasiconvex. Thus, it corresponds to the "relaxation" of the stored-energy function of the composite, and can in turn be viewed as a stress-driven "phase transition," where the symmetry of the fiber microstructures changes from nematic to smectic.

  15. 3D cell culture and osteogenic differentiation of human bone marrow stromal cells plated onto jet-sprayed or electrospun micro-fiber scaffolds.

    PubMed

    Brennan, Meadhbh Á; Renaud, Audrey; Gamblin, Anne-Laure; D'Arros, Cyril; Nedellec, Steven; Trichet, Valerie; Layrolle, Pierre

    2015-08-04

    A major limitation of the 2D culture systems is that they fail to recapitulate the in vivo 3D cellular microenvironment whereby cell-cell and cell-extracellular matrix (ECM) interactions occur. In this paper, a biomaterial scaffold that mimics the structure of collagen fibers was produced by jet-spraying. This micro-fiber polycaprolactone (PCL) scaffold was evaluated for 3D culture of human bone marrow mesenchymal stromal cells (MSCs) in comparison with a commercially available electrospun scaffold. The jet-sprayed scaffolds had larger pore diameters, greater porosity, smaller diameter fibers, and more heterogeneous fiber diameter size distribution compared to the electrospun scaffolds. Cells on jet-sprayed constructs exhibited spread morphology with abundant cytoskeleton staining, whereas MSCs on electrospun scaffolds appeared less extended with fewer actin filaments. MSC proliferation and cell infiltration occurred at a faster rate on jet-sprayed compared to electrospun scaffolds. Osteogenic differentiation of MSCs and ECM production as measured by ALP, collagen and calcium deposition was superior on jet-sprayed compared to electrospun scaffolds. The jet-sprayed scaffold which mimics the native ECM and permits homogeneous cell infiltration is important for 3D in vitro applications such as bone cellular interaction studies or drug testing, as well as bone tissue engineering strategies.

  16. Nerve guidance conduits from aligned nanofibers: improvement of nerve regeneration through longitudinal nanogrooves on a fiber surface.

    PubMed

    Huang, Chen; Ouyang, Yuanming; Niu, Haitao; He, Nanfei; Ke, Qinfei; Jin, Xiangyu; Li, Dawei; Fang, Jun; Liu, Wanjun; Fan, Cunyi; Lin, Tong

    2015-04-08

    A novel fibrous conduit consisting of well-aligned nanofibers with longitudinal nanogrooves on the fiber surface was prepared by electrospinning and was subjected to an in vivo nerve regeneration study on rats using a sciatic nerve injury model. For comparison, a fibrous conduit having a similar fiber alignment structure without surface groove and an autograft were also conducted in the same test. The electrophysiological, walking track, gastrocnemius muscle, triple-immunofluorescence, and immunohistological analyses indicated that grooved fibers effectively improved sciatic nerve regeneration. This is mainly attributed to the highly ordered secondary structure formed by surface grooves and an increase in the specific surface area. Fibrous conduits made of longitudinally aligned nanofibers with longitudinal nanogrooves on the fiber surface may offer a new nerve guidance conduit for peripheral nerve repair and regeneration.

  17. Automated co-alignment of coherent fiber laser arrays via active phase-locking.

    PubMed

    Goodno, Gregory D; Weiss, S Benjamin

    2012-07-02

    We demonstrate a novel closed-loop approach for high-precision co-alignment of laser beams in an actively phase-locked, coherently combined fiber laser array. The approach ensures interferometric precision by optically transducing beam-to-beam pointing errors into phase errors on a single detector, which are subsequently nulled by duplication of closed-loop phasing controls. Using this approach, beams from five coherent fiber tips were simultaneously phase-locked and position-locked with sub-micron accuracy. Spatial filtering of the sensed light is shown to extend the control range over multiple beam diameters by recovering spatial coherence despite the lack of far-field beam overlap.

  18. Compact cryogenic self-aligning fiber-to-detector coupling with losses below one percent.

    PubMed

    Miller, Aaron J; Lita, Adriana E; Calkins, Brice; Vayshenker, Igor; Gruber, Steven M; Nam, Sae Woo

    2011-05-09

    We present a compact packaging technique for coupling light from a single-mode telecommunication fiber to cryogenic single-photon sensitive devices. Our single-photon detectors are superconducting transition-edge sensors (TESs) with a collection area only a factor of a few larger than the area of the fiber core which presents significant challenges to low-loss fiber-to-detector coupling. The coupling method presented here has low loss, cryogenic compatibility, easy and reproducible assembly and low component cost. The system efficiency of the packaged single-photon counting detectors is verified by the "triplet method" of power-source calibration along with the "multiple attenuator" method that produces a calibrated single-photon flux. These calibration techniques, when used in combination with through-wafer imaging and fiber back-reflection measurements, give us confidence that we have achieved coupling losses below 1% for all devices packaged according to the self-alignment method presented in this paper.

  19. A new route to produce starch-based fiber mesh scaffolds by wet spinning and subsequent surface modification as a way to improve cell attachment and proliferation.

    PubMed

    Tuzlakoglu, K; Pashkuleva, I; Rodrigues, M T; Gomes, M E; van Lenthe, G H; Müller, R; Reis, R L

    2010-01-01

    This study proposes a new route for producing fiber mesh scaffolds from a starch-polycaprolactone (SPCL) blend. It was demonstrated that the scaffolds with 77% porosity could be obtained by a simple wet-spinning technique based on solution/precipitation of a polymeric blend. To enhance the cell attachment and proliferation, Ar plasma treatment was applied to the scaffolds. It was observed that the surface morphology and chemical composition were significantly changed because of the etching and functionalization of the fiber surfaces. XPS analyses showed an increase of the oxygen content of the fiber surfaces after plasma treatment (untreated scaffolds O/C:0.32 and plasma-treated scaffolds O/C:0.41). Both untreated and treated scaffolds were examined using a SaOs-2 human osteoblast-like cell line during 2 weeks of culture. The cell seeded on wet-spun SPCL fiber mesh scaffolds showed high viability and alkaline phosphatase enzyme activity, with those values being even higher for the cells seeded on the plasma-treated scaffolds.

  20. Optimal Parameter Design of Coarse Alignment for Fiber Optic Gyro Inertial Navigation System.

    PubMed

    Lu, Baofeng; Wang, Qiuying; Yu, Chunmei; Gao, Wei

    2015-06-25

    Two different coarse alignment algorithms for Fiber Optic Gyro (FOG) Inertial Navigation System (INS) based on inertial reference frame are discussed in this paper. Both of them are based on gravity vector integration, therefore, the performance of these algorithms is determined by integration time. In previous works, integration time is selected by experience. In order to give a criterion for the selection process, and make the selection of the integration time more accurate, optimal parameter design of these algorithms for FOG INS is performed in this paper. The design process is accomplished based on the analysis of the error characteristics of these two coarse alignment algorithms. Moreover, this analysis and optimal parameter design allow us to make an adequate selection of the most accurate algorithm for FOG INS according to the actual operational conditions. The analysis and simulation results show that the parameter provided by this work is the optimal value, and indicate that in different operational conditions, the coarse alignment algorithms adopted for FOG INS are different in order to achieve better performance. Lastly, the experiment results validate the effectiveness of the proposed algorithm.

  1. Improving Fiber Alignment in HARDI by Combining Contextual PDE Flow with Constrained Spherical Deconvolution

    PubMed Central

    Portegies, J. M.; Fick, R. H. J.; Sanguinetti, G. R.; Meesters, S. P. L.; Girard, G.; Duits, R.

    2015-01-01

    We propose two strategies to improve the quality of tractography results computed from diffusion weighted magnetic resonance imaging (DW-MRI) data. Both methods are based on the same PDE framework, defined in the coupled space of positions and orientations, associated with a stochastic process describing the enhancement of elongated structures while preserving crossing structures. In the first method we use the enhancement PDE for contextual regularization of a fiber orientation distribution (FOD) that is obtained on individual voxels from high angular resolution diffusion imaging (HARDI) data via constrained spherical deconvolution (CSD). Thereby we improve the FOD as input for subsequent tractography. Secondly, we introduce the fiber to bundle coherence (FBC), a measure for quantification of fiber alignment. The FBC is computed from a tractography result using the same PDE framework and provides a criterion for removing the spurious fibers. We validate the proposed combination of CSD and enhancement on phantom data and on human data, acquired with different scanning protocols. On the phantom data we find that PDE enhancements improve both local metrics and global metrics of tractography results, compared to CSD without enhancements. On the human data we show that the enhancements allow for a better reconstruction of crossing fiber bundles and they reduce the variability of the tractography output with respect to the acquisition parameters. Finally, we show that both the enhancement of the FODs and the use of the FBC measure on the tractography improve the stability with respect to different stochastic realizations of probabilistic tractography. This is shown in a clinical application: the reconstruction of the optic radiation for epilepsy surgery planning. PMID:26465600

  2. Alignment of the Fibrin Network Within an Autologous Plasma Clot.

    PubMed

    Gessmann, Jan; Seybold, Dominik; Peter, Elvira; Schildhauer, Thomas Armin; Köller, Manfred

    2016-01-01

    Autologous plasma clots with longitudinally aligned fibrin fibers could serve as a scaffold for longitudinal axonal regrowth in cases of traumatic peripheral nerve injuries. Three different techniques for assembling longitudinally oriented fibrin fibers during the fibrin polymerization process were investigated as follows: fiber alignment was induced by the application of either a magnetic field or-as a novel approach-electric field or by the induction of orientated flow. Fiber alignment was characterized by scanning electron microscopy analysis followed by image processing using fast Fourier transformation (FFT). Besides FFT output images, area xmin to xmax, as well as full width at half maximum (FWHM) of the FFT graph plot peaks, was calculated to determine the relative degree of fiber alignment. In addition, fluorescently labeled human fibrinogen and mesenchymal stem cells (MSCs) were used to visualize fibrin and cell orientation in aligned and nonaligned plasma clots. Varying degrees of fiber alignment were achieved by the three different methods, with the electric field application producing the highest degree of fiber alignment. The embedded MSCs showed a longitudinal orientation in the electric field-aligned plasma clots. The key feature of this study is the ability to produce autologous plasma clots with aligned fibrin fibers using physical techniques. This orientated internal structure of an autologous biomaterial is promising for distinct therapeutic applications, such as a guiding structure for cell migration and growth dynamics.

  3. 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.

  4. 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

  5. Fabrication of aligned Eu(TTA)3phen/PS fiber bundles from high molecular weight polymer solution by electrospinning

    NASA Astrophysics Data System (ADS)

    Yu, Hongquan; Li, Yue; Li, Tao; Chen, Baojiu; Li, Peng; Wu, Yanbo

    2015-12-01

    Super-long aligned luminescent Eu(TTA)3phen/PS composite fibers (TTA = thenoyltrifluoroacetone, phen = 1,10-phenanthroline, PS = polystyrene) with diameter in the range of 1-10 μm were prepared via an electrospinning method. The key to the success of alignment of these fibers was the usage of high molecular weight PS in the electrospinning solution and the low speed collecting drum. Luminescent properties of the composite fibers were systemically studied in comparison with that of the corresponding pure europium complex Eu(TTA)3phen. The results showed that the fluorescence lifetime for the 5 D 0 state in the composite fibers became shorter compared to that in the pure europium complex and decreases gradually with the concentration of Eu(DBM)3phen complex.

  6. Enhanced Cardiac Differentiation of Human Cardiovascular Disease Patient-Specific Induced Pluripotent Stem Cells by Applying Unidirectional Electrical Pulses Using Aligned Electroactive Nanofibrous Scaffolds.

    PubMed

    Mohammadi Amirabad, Leila; Massumi, Mohammad; Shamsara, Mehdi; Shabani, Iman; Amari, Afshin; Mossahebi Mohammadi, Majid; Hosseinzadeh, Simzar; Vakilian, Saeid; Steinbach, Sarah K; Khorramizadeh, Mohammad R; Soleimani, Masoud; Barzin, Jalal

    2017-03-01

    In the embryonic heart, electrical impulses propagate in a unidirectional manner from the sinus venosus and appear to be involved in cardiogenesis. In this work, aligned and random polyaniline/polyetersulfone (PANI/PES) nanofibrous scaffolds doped by Camphor-10-sulfonic acid (β) (CPSA) were fabricated via electrospinning and used to conduct electrical impulses in a unidirectional and multidirectional fashion, respectively. A bioreactor was subsequently engineered to apply electrical impulses to cells cultured on PANI/PES scaffolds. We established cardiovascular disease-specific induced pluripotent stem cells (CVD-iPSCs) from the fibroblasts of patients undergoing cardiothoracic surgeries. The CVD-iPSCs were seeded onto the scaffolds, cultured in cardiomyocyte-inducing factors, and exposed to electrical impulses for 1 h/day, over a 15-day time period in the bioreactor. The application of the unidirectional electrical stimulation to the cells significantly increased the number of cardiac Troponin T (cTnT+) cells in comparison to multidirectional electrical stimulation using random fibrous scaffolds. This was confirmed by real-time polymerase chain reaction for cardiac-related transcription factors (NKX2.5, GATA4, and NPPA) and a cardiac-specific structural gene (TNNT2). Here we report for the first time that applying electrical pulses in a unidirectional manner mimicking the unidirectional wave of electrical stimulation in the heart, could increase the derivation of cardiomyocytes from CVD-iPSCs.

  7. Effects of composite formulation on the mechanical properties of biodegradable poly(propylene fumarate)/bone fiber scaffolds

    PubMed Central

    Zhu, Xun; Liu, Nathan; Yaszemski, Michael J.; Lu, Lichun

    2010-01-01

    The objective of our study was to determine the effects of composite formulation on the compressive modulus and ultimate strength of a biodegradable, in situ polymerizable poly(propylene fumarate) (PPF) and bone fiber scaffold. The following parameters were investigated: the incorporation of bone fibers (either mineralized or demineralized), PPF molecular weight, N-vinyl pyrrolidinone (NVP) crosslinker amount, benzoyl peroxide (BP) initiator amount, and sodium chloride porogen amount. Eight formulations were chosen based on a resolution III two level fractional factorial design. The compressive modulus and ultimate strength of these formulations were measured on a materials testing machine. Absolute values for compressive modulus varied from 21.3 to 271 MPa and 2.8 to 358 MPa for dry and wet samples, respectively. The ultimate strength of the crosslinked composites varied from 2.1 to 20.3 MPa for dry samples and from 0.4 to 16.6 MPa for wet samples. Main effects of each parameter on the measured property were calculated. The incorporation of mineralized bone fibers and an increase in PPF molecular weight resulted in higher compressive modulus and ultimate strength. Both mechanical properties also increased as the amount of benzoyl peroxide increased or the NVP amount decreased in the formulation. Sodium chloride had a dominating effect on the increase of mechanical properties in dry samples but showed little effects in wet samples. Demineralization of bone fibers led to a decrease in the compressive modulus and ultimate strength. Our results suggest that bone fibers are appropriate as structural enforcement components in PPF scaffolds. The desired orthopaedic PPF scaffold might be obtained by changing a variety of composite formulation parameters. PMID:22034584

  8. Effects of composite formulation on the mechanical properties of biodegradable poly(propylene fumarate)/bone fiber scaffolds.

    PubMed

    Zhu, Xun; Liu, Nathan; Yaszemski, Michael J; Lu, Lichun

    2010-01-01

    The objective of our study was to determine the effects of composite formulation on the compressive modulus and ultimate strength of a biodegradable, in situ polymerizable poly(propylene fumarate) (PPF) and bone fiber scaffold. The following parameters were investigated: the incorporation of bone fibers (either mineralized or demineralized), PPF molecular weight, N-vinyl pyrrolidinone (NVP) crosslinker amount, benzoyl peroxide (BP) initiator amount, and sodium chloride porogen amount. Eight formulations were chosen based on a resolution III two level fractional factorial design. The compressive modulus and ultimate strength of these formulations were measured on a materials testing machine. Absolute values for compressive modulus varied from 21.3 to 271 MPa and 2.8 to 358 MPa for dry and wet samples, respectively. The ultimate strength of the crosslinked composites varied from 2.1 to 20.3 MPa for dry samples and from 0.4 to 16.6 MPa for wet samples. Main effects of each parameter on the measured property were calculated. The incorporation of mineralized bone fibers and an increase in PPF molecular weight resulted in higher compressive modulus and ultimate strength. Both mechanical properties also increased as the amount of benzoyl peroxide increased or the NVP amount decreased in the formulation. Sodium chloride had a dominating effect on the increase of mechanical properties in dry samples but showed little effects in wet samples. Demineralization of bone fibers led to a decrease in the compressive modulus and ultimate strength. Our results suggest that bone fibers are appropriate as structural enforcement components in PPF scaffolds. The desired orthopaedic PPF scaffold might be obtained by changing a variety of composite formulation parameters.

  9. Cellular automata simulation of osteoblast growth on microfibrous-carbon-based scaffolds.

    PubMed

    Czarnecki, Jarema S; Jolivet, Simon; Blackmore, Mary E; Lafdi, Khalid; Tsonis, Panagiotis A

    2014-12-01

    The objective of this study was to investigate the use of three fibrous carbon materials (T300, P25, and P120) for bone repair and develop and validate theoretical and computational methods in which bone tissue regeneration and repair could be accurately predicted. T300 was prepared from polyacrylonitrile precursor while P25 and P120 fibers were prepared from pitch, both common fiber precursors. Results showed that osteoblast growth on carbon scaffolds was enhanced with increased crystallinity, surface roughness, and material orientation. For unidirectional scaffolds at 120 h, there was 33% difference in cell growth between T300 and P25 fibers and 64% difference between P25 and P120 fibers. Moreover, for multidirectional fibers at 120 h, there was 35% difference in cell growth between T300 and P25 fibers and 43% difference between P25 and P120 fibers. Results showed that material alignment was integral to promoting cell growth with multidirectional scaffolds having the capacity for greater growth over unidirectional scaffolds. At 120 h there was 24% increase in cell growth between unidirectional alignment and multidirectional alignment on high-crystalline carbon fibers. Ultimately, data indicated that carbon scaffolds exhibited excellent bioactivity and may be tuned to stimulate unique reactions. Additionally, numerical and computational simulations provided evidence that corroborated experimental data with simulations. Results illustrated the capability of cellular automata models for assessing osteoblast cell response to biomaterials.

  10. Direct E-jet printing of three-dimensional fibrous scaffold for tendon tissue engineering.

    PubMed

    Wu, Yang; Wang, Zuyong; Ying Hsi Fuh, Jerry; San Wong, Yoke; Wang, Wilson; San Thian, Eng

    2017-04-01

    Tissue engineering (TE) offers a promising strategy to restore diseased tendon tissue. However, a suitable scaffold for tendon TE has not been achieved with current fabrication techniques. Herein, we report the development of a novel electrohydrodynamic jet printing (E-jetting) for engineering 3D tendon scaffold with high porosity and orientated micrometer-size fibers. The E-jetted scaffold comprised tubular multilayered micrometer-size fibrous bundles, with interconnected spacing and geometric anisotropy along the longitudinal direction of the scaffold. Fiber diameter, stacking pattern, and interfiber distance have been observed to affect the structural stability of the scaffold, of which the enhanced mechanical strength can be obtained for scaffolds with thick fibers as the supporting layer. Human tenocytes showed a significant increase in cellular metabolism on the E-jetted scaffolds as compared to that on conventional electrospun scaffolds (2.7-, 2.8-, and 3.1-fold increase for 150, 300, and 600 µm interfiber distance, respectively; p < 0.05). Furthermore, the scaffolds provided structural support for human tenocytes to align with controlled orientation along the longitudinal direction of the scaffold, and promoted the expression of collagen type I. For the first time, E-jetting has been explored as a novel scaffolding approach for tendon TE, and offers a 3D fibrous scaffold to promote organized tissue reconstruction for potential tendon healing. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 616-627, 2017.

  11. Crack Propagation Versus Fiber Alignment in Collagen Gels: Experiments and Multiscale Simulation

    PubMed Central

    Vanderheiden, Sarah M.; Hadi, Mohammad F.; Barocas, V. H.

    2015-01-01

    It is well known that the organization of the fibers constituting a collagenous tissue can affect its failure behavior. Less clear is how that effect can be described computationally so as to predict the failure of a native or engineered tissue under the complex loading conditions that can occur in vivo. Toward the goal of a general predictive strategy, we applied our multiscale model of collagen gel mechanics to the failure of a double-notched gel under tension, comparing the results for aligned and isotropic samples. In both computational and laboratory experiments, we found that the aligned gels were more likely to fail by connecting the two notches than the isotropic gels. For example, when the initial notches were 30% of the sample width (normalized tip-to-edge distance = 0.7), the normalized tip-to-tip distance at which the transition occurred from between-notch failure to across-sample failure shifted from 0.6 to 1.0. When the model predictions for the type of failure event (between the two notches versus across the sample width) were compared to the experimental results, the two were found to be strongly covariant by Fisher’s exact test (p < 0.05) for both the aligned and isotropic gels with no fitting parameters. Although the double-notch system is idealized, and the collagen gel system is simpler than a true tissue, it presents a simple model system for studying failure of anisotropic tissues in a controlled setting. The success of the computational model suggests that the multiscale approach, in which the structural complexity is incorporated via changes in the model networks rather than via changes to a constitutive equation, has the potential to predict tissue failure under a wide range of conditions. PMID:26355475

  12. Electrospun fiber scaffolds of poly (glycerol-dodecanedioate) and its gelatin blended polymers for soft tissue engineering.

    PubMed

    Dai, Xizi; Kathiria, Khadija; Huang, Yen-Chih

    2014-09-01

    For tissue engineering applications, biodegradable scaffolds play a vital role in supporting and guiding the seeded cells to form functional tissues by mimicking the structure and function of native extracellular matrices. Previously, we have developed a biodegradable elastomer poly (glycerol-dodecanedioate) (PGD) with mechanical properties suitable for soft tissue engineering. In the study, we found that the PGD and PGD blended with gelatin (PGD/gelatin) were able to be electrospun into fibrous scaffolds, and the diameters of the fibers could be adjusted by controlling the PGD concentration. When using our newly designed electrospinning collector, fibers could be easily harvested and the size of the fiber mat could be flexibly adjusted. The data of Raman spectra also confirmed the esterfication reaction in PGD polymerization and showed no significant structure change after electrospinning. Biocompatibility testing of the PGD and PGD/gelatin, by using human foreskin fibroblasts, indicated that gelatin could enhance cell adhesion and proliferation. Overall, electrospun fibers made from PGD and PGD/gelatin exhibited several advantages including easy synthesis from renewable raw materials, flexible fabrication by using less toxic solvents like ethanol, and good biocompatibility.

  13. Guiding the orientation of smooth muscle cells on random and aligned polyurethane/collagen nanofibers.

    PubMed

    Jia, Lin; Prabhakaran, Molamma P; Qin, Xiaohong; Ramakrishna, Seeram

    2014-09-01

    Fabricating scaffolds that can simulate the architecture and functionality of native extracellular matrix is a huge challenge in vascular tissue engineering. Various kinds of materials are engineered via nano-technological approaches to meet the current challenges in vascular tissue regeneration. During this study, nanofibers from pure polyurethane and hybrid polyurethane/collagen in two different morphologies (random and aligned) and in three different ratios of polyurethane:collagen (75:25; 50:50; 25:75) are fabricated by electrospinning. The fiber diameters of the nanofibrous scaffolds are in the range of 174-453 nm and 145-419 for random and aligned fibers, respectively, where they closely mimic the nanoscale dimensions of native extracellular matrix. The aligned polyurethane/collagen nanofibers expressed anisotropic wettability with mechanical properties which is suitable for regeneration of the artery. After 12 days of human aortic smooth muscle cells culture on different scaffolds, the proliferation of smooth muscle cells on hybrid polyurethane/collagen (3:1) nanofibers was 173% and 212% higher than on pure polyurethane scaffolds for random and aligned scaffolds, respectively. The results of cell morphology and protein staining showed that the aligned polyurethane/collagen (3:1) scaffold promote smooth muscle cells alignment through contact guidance, while the random polyurethane/collagen (3:1) also guided cell orientation most probably due to the inherent biochemical composition. Our studies demonstrate the potential of aligned and random polyurethane/collagen (3:1) as promising substrates for vascular tissue regeneration.

  14. Development of fibroblast culture in three-dimensional activated carbon fiber-based scaffold for wound healing.

    PubMed

    Huang, Wen-Ying; Yeh, Chia-Lin; Lin, Jui-Hsiang; Yang, Jai-Sing; Ko, Tse-Hao; Lin, Yu-Hsin

    2012-06-01

    This work developed a novel bi-layer wound dressing composed of 3D activated carbon fibers that allows facilitates fibroblast cell growth and migration to a wound site for tissue reconstruction, and the gentamicin is incorporated into a poly(γ-glutamic acid)/gelatin membrane to prevent bacterial infection. In an in vitro, field emission scanning electron microscopy shows that rat skin fibroblasts appeared and spread on the surface of activated carbon fibers, and penetrated the interior and exterior of the 3D activated carbon fiber construct to a depth of roughly 200 μm. An in vivo analysis shows that fibroblast cells containing the proposed 3D scaffold had the potential of a biologically functionalized dressing to accelerate wound closure. Additionally, fibroblasts migrated to the wound site in a bi-layer wound dressing containing fibroblasts, enhancing fibronectin and type I collagen expression, resulting in faster skin regeneration than that achieved with a Tegaderm™ hydrocolloid dressing or gauze.

  15. Modifying the strength and strain concentration profile within collagen scaffolds using customizable arrays of poly-lactic acid fibers.

    PubMed

    Mozdzen, Laura C; Vucetic, Alan; Harley, Brendan A C

    2017-02-01

    The tendon-to-bone junction is a highly specialized tissue which dissipates stress concentrations between mechanically dissimilar tendon and bone. Upon injury, the local heterogeneities across this insertion are not regenerated, leading to poor functional outcomes such as formation of scar tissue at the insertion and re-failure rates exceeding 90%. Although current tissue engineering methods are moving towards the development of spatially-graded biomaterials to begin to address these injuries, significant opportunities remain to engineer the often complex local mechanical behavior of such biomaterials to enhance their bioactivity. Here, we describe the use of three-dimensional printing techniques to create customizable arrays of poly-lactic acid (PLA) fibers that can be incorporated into a collagen scaffold under development for tendon bone junction repair. Notably, we use additive manufacturing concepts to generate arrays of spatially-graded fibers from biodegradable PLA that are incorporated into collagen scaffolds to create a collagen-PLA composite. We demonstrate the ability to tune the mechanical performance of the fiber-scaffold composite at the bulk scale. We also demonstrate the incorporation of spatially-heterogeneous fiber designs to establish non-uniform local mechanical performance of the composite biomaterial under tensile load, a critical element in the design of multi-compartment biomaterials for tendon-to-bone regeneration applications. Together, this work highlights the capacity to use multi-scale composite biomaterials to control local and bulk mechanical properties, and provides key insights into design elements under consideration for mechanically competent, multi-tissue regeneration platforms.

  16. Effects of chitosan-coated fibers as a scaffold for three-dimensional cultures of rabbit fibroblasts for ligament tissue engineering.

    PubMed

    Sarukawa, Junichiro; Takahashi, Masaaki; Abe, Masashi; Suzuki, Daisuke; Tokura, Seiichi; Furuike, Tetsuya; Tamura, Hiroshi

    2011-01-01

    Material selection in tissue-engineering scaffolds is one of the primary factors defining cellular response and matrix formation. In this study, we fabricated chitosan-coated poly(lactic acid) (PLA) fiber scaffolds to test our hypothesis that PLA fibers coated with chitosan highly promoted cell supporting properties compared to those without chitosan. Both PLA fibers (PLA group) and chitosan-coated PLA fibers (PLA-chitosan group) were fabricated for this study. Anterior cruciate ligament (ACL) fibroblasts were isolated from Japanese white rabbits and cultured on scaffolds consisting of each type of fiber. The effects of cell adhesivity, proliferation, and synthesis of the extracellular matrix (ECM) for each fiber were analyzed by cell counting, hydroxyproline assay, scanning electron microscopy and quantitative RT-PCR. Cell adhesivity, proliferation, hydroxyproline content and the expression of type-I collagen mRNA were significantly higher in the PLA-chitosan group than in the PLA group. Scanning electron microscopic observation showed that fibroblasts proliferated with a high level of ECM synthesis around the cells. Chitosan coating improved ACL fibroblast adhesion and proliferation, and had a positive effect on matrix production. Thus, the advantages of chitosan-coated PLA fibers show them to be a suitable biomaterial for ACL tissue-engineering scaffolds.

  17. A simplified implementation of edge detection in MATLAB is faster and more sensitive than fast fourier transform for actin fiber alignment quantification.

    PubMed

    Kemeny, Steven Frank; Clyne, Alisa Morss

    2011-04-01

    Fiber alignment plays a critical role in the structure and function of cells and tissues. While fiber alignment quantification is important to experimental analysis and several different methods for quantifying fiber alignment exist, many studies focus on qualitative rather than quantitative analysis perhaps due to the complexity of current fiber alignment methods. Speed and sensitivity were compared in edge detection and fast Fourier transform (FFT) for measuring actin fiber alignment in cells exposed to shear stress. While edge detection using matrix multiplication was consistently more sensitive than FFT, image processing time was significantly longer. However, when MATLAB functions were used to implement edge detection, MATLAB's efficient element-by-element calculations and fast filtering techniques reduced computation cost 100 times compared to the matrix multiplication edge detection method. The new computation time was comparable to the FFT method, and MATLAB edge detection produced well-distributed fiber angle distributions that statistically distinguished aligned and unaligned fibers in half as many sample images. When the FFT sensitivity was improved by dividing images into smaller subsections, processing time grew larger than the time required for MATLAB edge detection. Implementation of edge detection in MATLAB is simpler, faster, and more sensitive than FFT for fiber alignment quantification.

  18. Engineering hybrid polymer-protein super-aligned nanofibers via rotary jet spinning.

    PubMed

    Badrossamay, Mohammad R; Balachandran, Kartik; Capulli, Andrew K; Golecki, Holly M; Agarwal, Ashutosh; Goss, Josue A; Kim, Hansu; Shin, Kwanwoo; Parker, Kevin Kit

    2014-03-01

    Cellular microenvironments are important in coaxing cells to behave collectively as functional, structured tissues. Important cues in this microenvironment are the chemical, mechanical and spatial arrangement of the supporting matrix in the extracellular space. In engineered tissues, synthetic scaffolding provides many of these microenvironmental cues. Key requirements are that synthetic scaffolds should recapitulate the native three-dimensional (3D) hierarchical fibrillar structure, possess biomimetic surface properties and demonstrate mechanical integrity, and in some tissues, anisotropy. Electrospinning is a popular technique used to fabricate anisotropic nanofiber scaffolds. However, it suffers from relatively low production rates and poor control of fiber alignment without substantial modifications to the fiber collector mechanism. Additionally, many biomaterials are not amenable for fabrication via high-voltage electrospinning methods. Hence, we reasoned that we could utilize rotary jet spinning (RJS) to fabricate highly aligned hybrid protein-polymer with tunable chemical and physical properties. In this study, we engineered highly aligned nanofiber constructs with robust fiber alignment from blends of the proteins collagen and gelatin, and the polymer poly-ε-caprolactone via RJS and electrospinning. RJS-spun fibers retain greater protein content on the surface and are also fabricated at a higher production rate compared to those fabricated via electrospinning. We measured increased fiber diameter and viscosity, and decreasing fiber alignment as protein content increased in RJS hybrid fibers. RJS nanofiber constructs also demonstrate highly anisotropic mechanical properties mimicking several biological tissue types. We demonstrate the bio-functionality of RJS scaffold fibers by testing their ability to support cell growth and maturation with a variety of cell types. Our highly anisotropic RJS fibers are therefore able to support cellular alignment

  19. Patterned electrospun nanofibers for tissue scaffolds

    NASA Astrophysics Data System (ADS)

    Farboodmanesh, Samira

    There has been a considerable growth and development in electrospun nanofibers for research activity, as well as commercial fabrication over the past couple of decades. These continuous nanofibers are solution driven exclusively by an electric field. Numerous studies on electrospun fibrous scaffolds have demonstrated sufficient mechanical properties and support of cell growth for tissue engineering. Despite these substantial achievements, there is still an Edisonian-type procedure to acquire the desired scaffold orientation and mechanical response that mimics the native tissue behavior. In this dissertation, the electrospun scaffolds are fabricated with different fiber orientation---i.e. aligned and patterned (0/90)---by modifying the electrospinning process, specifically electric field and target, over large areas and lengths (30 mm x 30 mm). Mechanical behavior of controlled scaffold parameters at macro/micro- and nanoscale is investigated for an effective tissue replacement. In addition a mechanics of material model is used to predict and capture the fibrous scaffold mechanical response, with desired fiber orientation, fiber volume fraction, and fiber diameter. Finally, the model predictions are compared to the experimental results.

  20. Initial Fiber Alignment Pattern Alters Extracellular Matrix Synthesis in Fibroblast Populated Fibrin Gel Cruciforms and Correlates with Predicted Tension

    PubMed Central

    Sander, E.A.; Barocas, V.H.; Tranquillo, R.T.

    2013-01-01

    Human dermal fibroblasts entrapped in fibrin gels cast in cross-shaped (cruciform) geometries with 1:1 and 1:0.5 ratios of arm widths were studied to assess whether tension and alignment of the cells and fibrils affected ECM deposition. The cruciforms of contrasting geometry (symmetric vs. asymmetric), which developed different fiber alignment patterns, were harvested at 2, 5, and 10 weeks of culture. Cruciforms were subjected to planar biaxial testing, polarimetric imaging, DNA and biochemical analyses, histological staining, and SEM imaging. As the cruciforms compacted and developed fiber alignment, fibrin was degraded and elastin and collagen were produced in a geometry-dependent manner. Using a continuum mechanical model that accounts for direction-dependent stress due to cell traction forces and cell contact guidance with aligned fibers that occurs in the cruciforms, the mechanical stress environment was concluded to influence collagen deposition, with deposition being greatest in the narrow arms of the asymmetric cruciform where stress was predicted to be largest. PMID:21046467

  1. Replication of self-centering optical fiber alignment structures using hot embossing

    NASA Astrophysics Data System (ADS)

    Ebraert, Evert; Wissmann, Markus; Barié, Nicole; Guttmann, Markus; Schneider, Marc; Kolew, Alexander; Worgull, Matthias; Beri, Stefano; Watté, Jan; Thienpont, Hugo; Van Erps, Jürgen

    2016-04-01

    With the demand for broadband connectivity on the rise due to various services like video-on-demand and cloud computing becoming more popular, the need for better connectivity infrastructure is high. The only future- proof option to supply this infrastructure is to deploy "fiber to the home" (FTTH) networks. One of the main difficulties with the deployment of FTTH is the vast amount of single-mode fiber (SMF) connections that need to be made. Hence there is a strong need for components which enable high performance, robust and easy-to- use SMF connectors. Since large-scale deployment is the goal, these components should be mass-producible at low cost. We discuss a rapid prototyping process on the basis of hot embossing replication of a self-centering alignment system (SCAS) based on three micro-springs, which can position a SMF independently of its diameter. This is beneficial since there is a fabrication tolerance of up to +/-1 μm on a standard G.652 SMF's diameter that can lead to losses if the outer diameter is used as a reference for alignment. The SCAS is first prototyped with deep proton writing (DPW) in polymethylmethacrylate (PMMA) after which it is glued to a copper substrate with an adhesive. Using an electroforming process, a nickel block is grown over the PMMA prototype followed by mechanical finishing to fabricate a structured nickel mould insert. Even though the mould insert shows non- ideal and rounded features it is used to create PMMA replicas of the SCAS by means of hot embossing. The SCAS possesses a central opening in which a bare SMF can be clamped, which is designed with a diameter of 121 μm. PMMA replicas are dimensionally characterized using a multisensor coordinate measurement machine and show a central opening diameter of 128.3 +/- 2.8 μm. This should be compared to the central opening diameter of the DPW prototype used for mould formation which was measured to be 120.5 μm. This shows that the electroforming and subsequent replication

  2. A novel method for segmenting and aligning the pre- and post-implantation scaffolds of resorbable calcium-phosphate bone substitutes.

    PubMed

    Sweedy, Ahmed; Bohner, Marc; van Lenthe, G Harry; Baroud, Gamal

    2017-03-02

    Micro-computed tomography (microCT) is commonly used to characterize the three-dimensional structure of bone graft scaffolds before and after implantation in order to assess changes occurring during implantation. The accurate processing of the microCT datasets of explanted β-tricalcium phosphate (β-TCP) scaffolds poses significant challenges because of (a) the overlap in the grey values distribution of ceramic remnants, bone, and soft tissue, and of (b) the resorption of the bone substitute during the implantation. To address those challenges, this article introduces and rigorously validates a new processing technique to accurately distinguish these three phases found in the explanted β-TCP scaffolds. Specifically, the microCT datasets obtained before and after implantation of β-TCP scaffolds were aligned in 3D, and the characteristic grey value distributions of the three phases were extracted, thus allowing for (i) the accurate differentiation between these three phases (ceramic remnants, bone, soft tissue), and additionally for (ii) the localization of the defect site in the post-implantation microCT dataset. Using the similarity matrix, a 94±1% agreement was found between algorithmic results and the visual assessment of 556,800 pixels. Moreover, the comparison of the segmentation results of the same microCT and histology section further confirmed the validity of the present segmentation algorithm. This new technique could lead to a more common use of microCT in analyzing the complex 3D processes and to a better understanding of the biological processes occurring after the implantation of ceramic bone graft substitutes.

  3. Regulated release of a novel non-viral gene delivery vector from electrospun coaxial fiber mesh scaffolds

    NASA Astrophysics Data System (ADS)

    Saraf, Anita

    The development of novel strategies for tissue engineering entails the evolution of biopolymers into multifunctional constructs that can support the proliferation of cells and stimulate their differentiation into functional tissues. With that in mind, biocompatible polymers were fabricated into a novel gene delivery agent as well as three dimensional scaffolds that act as reservoirs and controlled release constructs. To fabricate a novel gene delivery agent a commercially available cationic polymer, poly(ethylenimine), PEI, was chemically conjugated to a ubiquitous glycosaminoglycan, hyaluronic acid (HA). The novel polymer, PEI-HA, had significantly reduced toxicity and improved transfection efficiency with multipotent human mesenchymal stem cells. This transfection efficiency could further be modulated by changing the concentration of sodium chloride and temperature used to assemble PEI-HA/DNA complexes. To facilitate the regulated delivery of these complexes in the context of tissue engineering, an emerging technology for scaffold fabrication, coaxial electrospinning was adapted to include PEI-HA and plasmid DNA within the scaffold fibers. Initially, a factorial design was employed to assess the influence of processing parameters in the absence of gene delivery vectors and plasmids. The study elucidated the role of sheath polymer concentration and core polymer concentration and molecular weight and the presence of sodium chloride on fiber diameters and morphologies. Subsequently, PEI-HA and plasmid DNA were entrapped within the sheath and core compartments of these fibers and the influence of processing parameters was assessed in the context of fiber diameter, release kinetics and transfection efficiency over a period of 60 days. The release of PEI-HA was found to be dependent upon the loading dose of the vector and plasmid. However, the transfection efficiency correlated to the core polymer properties, concentration and molecular weight. The processing

  4. The Effect of Electrospun Gelatin Fibers Alignment on Schwann Cell and Axon Behavior and Organization in the Perspective of Artificial Nerve Design.

    PubMed

    Gnavi, Sara; Fornasari, Benedetta Elena; Tonda-Turo, Chiara; Laurano, Rossella; Zanetti, Marco; Ciardelli, Gianluca; Geuna, Stefano

    2015-06-08

    Electrospun fibrous substrates mimicking extracellular matrices can be prepared by electrospinning, yielding aligned fibrous matrices as internal fillers to manufacture artificial nerves. Gelatin aligned nano-fibers were prepared by electrospinning after tuning the collector rotation speed. The effect of alignment on cell adhesion and proliferation was tested in vitro using primary cultures, the Schwann cell line, RT4-D6P2T, and the sensory neuron-like cell line, 50B11. Cell adhesion and proliferation were assessed by quantifying at several time-points. Aligned nano-fibers reduced adhesion and proliferation rate compared with random fibers. Schwann cell morphology and organization were investigated by immunostaining of the cytoskeleton. Cells were elongated with their longitudinal body parallel to the aligned fibers. B5011 neuron-like cells were aligned and had parallel axon growth when cultured on the aligned gelatin fibers. The data show that the alignment of electrospun gelatin fibers can modulate Schwann cells and axon organization in vitro, suggesting that this substrate shows promise as an internal filler for the design of artificial nerves for peripheral nerve reconstruction.

  5. Effect of polyvinylidene fluoride electrospun fiber orientation on neural stem cell differentiation.

    PubMed

    Lins, Luanda C; Wianny, Florence; Livi, Sebastien; Dehay, Colette; Duchet-Rumeau, Jannick; Gérard, Jean-François

    2016-08-29

    Electrospun polymer piezoelectric fibers can be used in neural tissue engineering (NTE) to mimic the physical, biological, and material properties of the native extracellular matrix. In this work, we have developed scaffolds based on polymer fiber architectures for application in NTE. To study the role of such three-dimensional scaffolds, a rotating drum collector was used for electrospinning poly(vinylidene) fluoride (PVDF) polymer at various rotation speeds. The morphology, orientation, polymorphism, as well as the mechanical behavior of the nonaligned and aligned fiber-based architectures were characterized. We have demonstrated that the jet flow and the electrostatic forces generated by electrospinning of PVDF induced local conformation changes which promote the generation of the β-phase. Fiber anisotropy could be a critical feature for the design of suitable scaffolds for NTEs. We thus assessed the impact of PVDF fiber alignment on the behavior of monkey neural stem cells (NSCs). NSCs were seeded on nonaligned and aligned scaffolds and their morphology, adhesion, and differentiation capacities into the neuronal and glial pathways were studied using microscopic techniques. Significant changes in the growth and differentiation capacities of NSCs into neuronal and glial cells as a function of the fiber alignment were evidenced. These results demonstrate that PVDF scaffolds may serve as instructive scaffolds for NSC survival and differentiation, and may be valuable tools for the development of cell- and scaffold-based strategies for neural repair. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  6. Performance of graphite fiber-reinforced polyimide composites in self-aligning plain bearings to 315 C

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.; Jacobson, T. P.

    1975-01-01

    A 50/50 (weight percent) composite of graphite fibers and polyimide was studied in self-aligning plain bearings oscillating + or - 15 degrees at 1 hz. The friction coefficient was 0.15 + or - 0.05 at 250 C, and 0.05 + or - 0.02 at 315 C. Best results were obtained with a molded composite liner with chopped graphite fibers randomly oriented in the composite. The specific wear rate is given. It was found that the dynamic unit load capacity was higher for a composite bushing (thin liner), than for a composite ball.

  7. A comparative evaluation of the effect of polymer chemistry and fiber orientation on mesenchymal stem cell differentiation

    PubMed Central

    Rowland, David C.L.; Aquilina, Thomas; Klein, Andrei; Hakimi, Osnat; Alexis‐Mouthuy, Pierre; Carr, Andrew J

    2016-01-01

    Abstract Bioengineered tissue scaffolds in combination with cells hold great promise for tissue regeneration. The aim of this study was to determine how the chemistry and fiber orientation of engineered scaffolds affect the differentiation of mesenchymal stem cells (MSCs). Adipogenic, chondrogenic, and osteogenic differentiation on aligned and randomly orientated electrospun scaffolds of Poly (lactic‐co‐glycolic) acid (PLGA) and Polydioxanone (PDO) were compared. MSCs were seeded onto scaffolds and cultured for 14 days under adipogenic‐, chondrogenic‐, or osteogenic‐inducing conditions. Cell viability was assessed by alamarBlue metabolic activity assays and gene expression was determined by qRT‐PCR. Cell‐scaffold interactions were visualized using fluorescence and scanning electron microscopy. Cells grew in response to scaffold fiber orientation and cell viability, cell coverage, and gene expression analysis showed that PDO supports greater multilineage differentiation of MSCs. An aligned PDO scaffold supports highest adipogenic and osteogenic differentiation whereas fiber orientation did not have a consistent effect on chondrogenesis. Electrospun scaffolds, selected on the basis of fiber chemistry and alignment parameters could provide great therapeutic potential for restoration of fat, cartilage, and bone tissue. This study supports the continued investigation of an electrospun PDO scaffold for tissue repair and regeneration and highlights the potential of optimizing fiber orientation for improved utility. © 2016 The Authors Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2843–2853, 2016. PMID:27399850

  8. “Controlled release of neurotrophin-3 from fibrin-based tissue engineering scaffolds enhances neural fiber sprouting following subacute spinal cord injury”†

    PubMed Central

    Johnson, Philip J; Parker, Stanley R; Sakiyama-Elbert, Shelly E.

    2009-01-01

    This study investigated whether delayed treatment of spinal cord injury with controlled release of neurotrophin-3 (NT-3) from fibrin scaffolds can stimulate enhanced neural fiber sprouting. Long Evans rats received a T9 dorsal hemisection spinal cord injury. Two weeks later, the injury site was re-exposed, and either a fibrin scaffold alone, a fibrin scaffold containing a heparin-based delivery system with different concentrations of NT-3 (500 and 1000 ng/mL), or a fibrin scaffold containing 1000 ng/mL of NT-3 (no delivery system) was implanted into the injury site. The injured spinal cords were evaluated for morphological differences using markers for neurons, astrocytes, and chondroitin sulfate proteoglycans 2 weeks after treatment. The addition of 500 ng/mL of NT-3 with the delivery system resulted in an increase in neural fiber density compared to fibrin alone. These results demonstrate that the controlled release of NT-3 from fibrin scaffolds can enhance neural fiber sprouting even when treatment is delayed 2 weeks following injury. PMID:19603426

  9. Fabrication, measurement, and alignment uniformity analysis of linear arrays of optical fibers

    SciTech Connect

    Klingsporn, P.E.

    1997-06-01

    Techniques were developed for assembling a linear array of optical fibers between two silicon plates and polishing the fiber ends in a plane perpendicular to the fiber axis. The silicon plates contained etched V-grooves for capturing the fibers. Optical fibers from two sources were evaluated, along with silicon plates supplied by two sources. Most of the arrays were assembled by epoxy bonding, but some effort was made to form a eutectic bond using gold metallized fibers with gold-coated silicon plates. Measurements were made of the uniformity of spacing of the fiber mode field centers in the linear array. The work was performed to develop a multi-fiber linear array connector to couple optical signals to and from optoelectronic devices.

  10. Pullout problem and fracture mechanism of quasi-brittle material reinforced with discontinous aligned fibers subjected to uniaxial tension

    NASA Astrophysics Data System (ADS)

    Cheng, Cheng-Jang

    The objective of this research is to characterize the postpeak pseudo strain-hardening behavior of the discontinuous aligned fiber composites subjected to uniaxial tension. In order to fully understand the fiber axial force-debonding relationship, fiber pullout problem was first investigated. Unlike most models this theory assumes a triangularly distributed interface shear stress. Besides, R-curve approach was adopted to evaluate the maximum pullout load. In quasi-brittle materials when the value of energy release rate G increases with the applied load, the value of crack resistance R also increases. As a result, the equality of G and R can only serve as the necessary condition for crack propagation. In order to further distinguish stable and unstable crack propagation, a second condition must be included. Namely, the first derivatives of G and R must also equal to each other for the onset of unstable crack propagation. The applied load corresponding to this status is assumed to be the maximum pullout load the fiber can sustain. The corresponding debond length is referred to critical debond length ldc. It was found that ldc increases with embedment length le. This model reproduced the experimental results pretty well. The same concept of R-curve was adopted to investigate the fracture mechanism of the uniaxial tension problem. While determining strain energy of the fiber reinforced composite, equivalent inclusion method and Mori-Tanaka theory was utilized. Again, whenever the above two conditions are satisfied simultaneously, unstable crack propagation initiates. However, are the fibers being pulled out or is there another unstable crack propagation? The comparison of the force sustained by all the fibers in the entire cross section with its allowable value sets the criterion. Besides, unlike most models, this model takes account of the impact of fiber distribution. Thus a model distinguishing single cracking from multiple cracking fracture mechanism has been

  11. 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.

  12. The use of fiber-reinforced scaffolds cocultured with Schwann cells and vascular endothelial cells to repair rabbit sciatic nerve defect with vascularization.

    PubMed

    Gao, Hongyang; You, Yang; Zhang, Guoping; Zhao, Feng; Sha, Ziyi; Shen, Yong

    2013-01-01

    To explore the feasibility of biodegradable fiber-reinforced 3D scaffolds with satisfactory mechanical properties for the repair of long-distance sciatic nerve defect in rabbits and effects of vascularized graft in early stage on the recovery of neurological function, Schwann cells and vascular endothelial cells were cocultured in the fiber-reinforced 3D scaffolds. Experiment group which used prevascularized nerve complex for the repair of sciatic nerve defect and control group which only cultured with Schwann cells were set. The animals in both groups underwent electromyography to show the status of the neurological function recovery at 4, 8, and 16 weeks after the surgery. Sciatic nerve regeneration and myelination were observed under the light microscope and electron microscope. Myelin sheath thickness, axonal diameter, and number of myelinated nerve fiber were quantitatively analyzed using image analysis system. The recovery of foot ulcer, the velocity of nerve conduction, the number of regenerating nerve fiber, and the recovery of ultrastructure were increased in the experimental group than those in the control group. Prevascularized tissue engineered fiber-reinforced 3D scaffolds for the repair of sciatic nerve defects in rabbits can effectively promote the recovery of neurological function.

  13. Fulleretic Well-Defined Scaffolds: Donor-Fullerene Alignment Through Metal Coordination and Its Effect on Photophysics.

    PubMed

    Williams, Derek E; Dolgopolova, Ekaterina A; Godfrey, Danielle C; Ermolaeva, Evgeniya D; Pellechia, Perry J; Greytak, Andrew B; Smith, Mark D; Avdoshenko, Stanislav M; Popov, Alexey A; Shustova, Natalia B

    2016-07-25

    Herein, we report the first example of a crystalline metal-donor-fullerene framework, in which control of the donor-fullerene mutual orientation was achieved through chemical bond formation, in particular, by metal coordination. The (13) C cross-polarization magic-angle spinning NMR spectroscopy, X-ray diffraction, and time-resolved fluorescence spectroscopy were performed for comprehensive structural analysis and energy-transfer (ET) studies of the fulleretic donor-acceptor scaffold. Furthermore, in combination with photoluminescence measurements, the theoretical calculations of the spectral overlap function, Förster radius, excitation energies, and band structure were employed to elucidate the photophysical and ET processes in the prepared fulleretic material. We envision that the well-defined fulleretic donor-acceptor materials could contribute not only to the basic science of fullerene chemistry but would also be used towards effective development of organic photovoltaics and molecular electronics.

  14. Anisotropic Poly (glycerol sebacate)-Poly (ε-caprolactone) Electrospun Fibers Promote Endothelial Cell Guidance

    PubMed Central

    Gaharwar, Akhilesh K.; Nikkhah, Mehdi; Sant, Shilpa; Khademhosseini, Ali

    2015-01-01

    Topographical cell guidance is utilized to engineer highly organized and aligned cellular constructs for numerous tissue engineering applications. Recently, electrospun scaffolds fabricated using poly(glycerol sebacate) (PGS) and poly(ε-caprolactone) (PCL) have shown a great promise to support valvular interstitial cell functions for the development of tissue engineered heart valves. However, one of the major drawbacks of PGS-PCL scaffolds is the lack of control over cellular alignment. In this work we investigate the role of scaffold architecture on the endothelial cell alignment, proliferation and formation of organized cellular structures. In particular, PGS-PCL scaffolds with randomly oriented and highly aligned fibers with tunable mechanical properties were fabricated using electrospinning technique. After one week of culture, endothelial cells on the aligned scaffolds exhibit higher proliferation compared to those cultures on randomly oriented fibrous scaffolds. Furthermore, the endothelial cells reorganize in response to the topographical features of anisotropic scaffolds forming highly organize cellular constructs. Thus, the topographical contact guidance, provided by aligned PGS-PCL scaffolds, is envisioned to be useful in developing aligned cellular structures for vascular tissue engineering. PMID:25516556

  15. Anisotropic poly (glycerol sebacate)-poly (ϵ-caprolactone) electrospun fibers promote endothelial cell guidance.

    PubMed

    Gaharwar, Akhilesh K; Nikkhah, Mehdi; Sant, Shilpa; Khademhosseini, Ali

    2014-12-17

    Topographical cell guidance is utilized to engineer highly organized and aligned cellular constructs for numerous tissue engineering applications. Recently, electrospun scaffolds fabricated using poly(glycerol sebacate) (PGS) and poly(ϵ-caprolactone) (PCL) have shown a great promise to support valvular interstitial cell functions for the development of tissue engineered heart valves. However, one of the major drawbacks of PGS-PCL scaffolds is the lack of control over cellular alignment. In this work, we investigate the role of scaffold architecture on the endothelial cell alignment, proliferation and formation of organized cellular structures. In particular, PGS-PCL scaffolds with randomly oriented and highly aligned fibers with tunable mechanical properties were fabricated using electrospinning technique. After one week of culture, endothelial cells on the aligned scaffolds exhibited higher proliferation compared to those cultures on randomly oriented fibrous scaffolds. Furthermore, the endothelial cells reorganized in response to the topographical features of aligned scaffolds forming highly organized cellular constructs. Thus, topographical contact guidance, provided by aligned PGS-PCL scaffolds, is envisioned to be useful in developing cellular structures for vascular tissue engineering.

  16. Scintillating Fiber Array Characterization and Alignment for Neutron Imaging using the High Energy X-ray (HEX) Facility

    SciTech Connect

    Buckles, R. A., Ali, Z. A., Cradick, J. R., Traille, A. J., Warthan, W. A.

    2009-09-04

    The Neutron Imager diagnostic at the National Ignition Facility (NIF) located at Lawrence Livermore National Laboratory (LLNL) will produce high-resolution, gated images of neutron-generating implosions. A similar pinhole imaging experiment (PINEX) diagnostic was recently deployed at the Z facility at Sandia National Laboratories (SNL). Both the SNL and LLNL neutron imagers use similar fiber array scintillators (BCF-99-555). Despite diverse resolution and magnification requirements, both diagnostics put significant onus on the scintillator spatial quality and alignment precision to maintain optimal point spread. Characterization and alignment of the Z-PINEX scintillator and imaging system were done at NSTec/Livermore Operations in 2009, and is currently underway for the NIF Neutron Imager.

  17. 3D Scaffold of Electrosprayed Fibers with Large Pore Size for Tissue Regeneration

    PubMed Central

    Hong, Jong Kyu; Madihally, Sundararajan V.

    2010-01-01

    Regeneration of tissues using biodegradable porous scaffolds has been an intensely investigated area. Since electrospinning can produce scaffolds mimicking nanofibrous architecture found in the body, it recently has gained widespread attention. However, a major problem is the lack of pore size necessary for infiltration of cells into the layers below the surface, restricting cell colonization to the surfaces only. This study describes a novel twist to the traditional electrospinning technology. In particular, collector plates are designed which allows forming very thin layers with pore sizes suitable for cell infiltration. Thin samples can be handled without mechanically damaging the structure and can be transferred into cell culture. These thin layers were stacked by layer-by-layer assembly to develop thick structures. Thirty day cultures of fibroblasts show attachment and spreading of cells in every layer. This concept is useful in regenerating thick tissues with uniformly distributed cells and others in vitro cell culture. PMID:20620245

  18. Hot-embossing replication of self-centering optical fiber alignment structures prototyped by deep proton writing

    NASA Astrophysics Data System (ADS)

    Ebraert, Evert; Wissmann, Markus; Guttmann, Markus; Kolew, Alexander; Worgull, Matthias; Barié, Nicole; Schneider, Marc; Hofmann, Andreas; Beri, Stefano; Watté, Jan; Thienpont, Hugo; Van Erps, Jürgen

    2016-07-01

    This paper presents the hot-embossing replication of self-centering fiber alignment structures for high-precision, single-mode optical fiber connectors. To this end, a metal mold insert was fabricated by electroforming a polymer prototype patterned by means of deep proton writing (DPW). To achieve through-hole structures, we developed a postembossing process step to remove the residual layer inherently present in hot-embossed structures. The geometrical characteristics of the hot-embossed replicas are compared, before and after removal of the residual layer, with the DPW prototypes. Initial measurements on the optical performance of the replicas are performed. The successful replication of these components paves the way toward low-cost mass replication of DPW-fabricated prototypes in a variety of high-tech plastics.

  19. Radially aligned, electrospun nanofibers as dural substitutes for wound closure and tissue regeneration applications.

    PubMed

    Xie, Jingwei; Macewan, Matthew R; Ray, Wilson Z; Liu, Wenying; Siewe, Daku Y; Xia, Younan

    2010-09-28

    This paper reports the fabrication of scaffolds consisting of radially aligned poly(ε-caprolactone) nanofibers by utilizing a collector composed of a central point electrode and a peripheral ring electrode. This novel class of scaffolds was able to present nanoscale topographic cues to cultured cells, directing and enhancing their migration from the periphery to the center. We also established that such scaffolds could induce faster cellular migration and population than nonwoven mats consisting of random nanofibers. Dural fibroblast cells cultured on these two types of scaffolds were found to express type I collagen, the main extracellular matrix component in dural mater. The type I collagen exhibited a high degree of organization on the scaffolds of radially aligned fibers and a haphazard distribution on the scaffolds of random fibers. Taken together, the scaffolds based on radially aligned, electrospun nanofibers show great potential as artificial dural substitutes and may be particularly useful as biomedical patches or grafts to induce wound closure and/or tissue regeneration.

  20. Production of a Self-Aligned Scaffold, Free of Exogenous Material, from Dermal Fibroblasts Using the Self-Assembly Technique

    PubMed Central

    Bolduc, Stéphane

    2016-01-01

    Many pathologies of skin, especially ageing and cancer, involve modifications in the matrix alignment. Such tissue reorganization could have impact on cell behaviour and/or more global biological processes. Tissue engineering provides accurate study model by mimicking the skin and it allows the construction of versatile tridimensional models using human cells. It also avoids the use of animals, which gave sometimes nontranslatable results. Among the various techniques existing, the self-assembly method allows production of a near native skin, free of exogenous material. After cultivating human dermal fibroblasts in the presence of ascorbate during two weeks, a reseeding of these cells takes place after elevation of the resulting stroma on a permeable ring and culture pursued for another two weeks. This protocol induces a clear realignment of matrix fibres and cells parallel to the horizon. The thickness of this stretched reconstructed tissue is reduced compared to the stroma produced by the standard technique. Cell count is also reduced. In conclusion, a new, easy, and inexpensive method to produce aligned tissue free of exogenous material could be used for fundamental research applications in dermatology. PMID:27051415

  1. Use of natural neural scaffolds consisting of engineered vascular endothelial growth factor immobilized on ordered collagen fibers filled in a collagen tube for peripheral nerve regeneration in rats.

    PubMed

    Ma, Fukai; Xiao, Zhifeng; Meng, Danqing; Hou, Xianglin; Zhu, Jianhong; Dai, Jianwu; Xu, Ruxiang

    2014-10-15

    The search for effective strategies for peripheral nerve regeneration has attracted much attention in recent years. In this study, ordered collagen fibers were used as intraluminal fibers after nerve injury in rats. Vascular endothelial growth factor (VEGF) plays an important role in nerve regeneration, but its very fast initial burst of activity within a short time has largely limited its clinical use. For the stable binding of VEGF to ordered collagen fibers, we fused a collagen-binding domain (CBD) to VEGF through recombinant DNA technology. Then, we filled the ordered collagen fibers-CBD-VEGF targeting delivery system in a collagen tube to construct natural neural scaffolds, which were then used to bridge transected nerve stumps in a rat sciatic nerve transection model. After transplantation, the natural neural scaffolds showed minimal foreign body reactions and good integration into the host tissue. Oriented collagen fibers in the collagen tube could guide regenerating axons in an oriented manner to the distal, degenerating nerve segment, maximizing the chance of target reinnervation. Functional and histological analyses indicated that the recovery of nerve function in the natural neural scaffolds-treated group was superior to the other grafted groups. The guiding of oriented axonal regeneration and effective delivery systems surmounting the otherwise rapid and short-lived diffusion of growth factors in body fluids are two important strategies in promoting peripheral nerve regeneration. The natural neural scaffolds described take advantage of these two aspects and may produce synergistic effects. These properties qualified the artificial nerve conduits as a putative candidate system for the fabrication of peripheral nerve reconstruction devices.

  2. Novel genipin-collagen immobilization of polylactic acid (PLA) fibers for use as tissue engineering scaffolds.

    PubMed

    Tambe, Nisarg; Di, Jin; Zhang, Ze; Bernacki, Susan; El-Shafei, Ahmed; King, Martin W

    2015-08-01

    The material surface plays an important role in the case of biomaterials used as tissue engineering scaffolds. On exposure to a biological environment, extra cellular matrix (ECM) proteins are adsorbed non-specifically onto the surface and cells interact indirectly with the surface through the adsorbed proteins. Most synthetic polymeric biomaterials lack the desirable surface properties for cells as well as have poor cellular adhesion due to their hydrophobic nature. The main objective of this study was to harness surface functionalization technologies to fabricate scaffolds that would be biocompatible and support the adhesion and proliferation of fibroblast cells. The collagen was immobilized on the surface of functionalized PLA via a novel natural cross-linking molecule genipin which resulted in improved cell proliferation of human dermal fibroblasts as compared to the PLA surface coated with collagen without genipin. It is believed that genipin helps reduce steric problems between the functional groups and large protein molecules, and enables immobilized peptide to move more freely in a biological environment.

  3. Fluid-structure interaction model of aortic valve with porcine-specific collagen fiber alignment in the cusps.

    PubMed

    Marom, Gil; Peleg, Mor; Halevi, Rotem; Rosenfeld, Moshe; Raanani, Ehud; Hamdan, Ashraf; Haj-Ali, Rami

    2013-10-01

    Native aortic valve cusps are composed of collagen fibers embedded in their layers. Each valve cusp has its own distinctive fiber alignment with varying orientations and sizes of its fiber bundles. However, prior mechanical behavior models have not been able to account for the valve-specific collagen fiber networks (CFN) or for their differences between the cusps. This study investigates the influence of this asymmetry on the hemodynamics by employing two fully coupled fluid-structure interaction (FSI) models, one with asymmetric-mapped CFN from measurements of porcine valve and the other with simplified-symmetric CFN. The FSI models are based on coupled structural and fluid dynamic solvers. The partitioned solver has nonconformal meshes and the flow is modeled by employing the Eulerian approach. The collagen in the CFNs, the surrounding elastin matrix, and the aortic sinus tissues have hyperelastic mechanical behavior. The coaptation is modeled with a master-slave contact algorithm. A full cardiac cycle is simulated by imposing the same physiological blood pressure at the upstream and downstream boundaries for both models. The mapped case showed highly asymmetric valve kinematics and hemodynamics even though there were only small differences between the opening areas and cardiac outputs of the two cases. The regions with a less dense fiber network are more prone to damage since they are subjected to higher principal stress in the tissues and a higher level of flow shear stress. This asymmetric flow leeward of the valve might damage not only the valve itself but also the ascending aorta.

  4. Bioinspired crystallization of CaCO3 coatings on electrospun cellulose acetate fiber scaffolds and corresponding CaCO3 microtube networks.

    PubMed

    Liu, Lei; He, Dian; Wang, Guang-Sheng; Yu, Shu-Hong

    2011-06-07

    This article describes the mineralization behavior of CaCO(3) crystals on electrospun cellulose acetate (CA) fibers by using poly(acrylic acid) (PAA) as a crystal growth modifier and further templating synthesis of CaCO(3) microtubes. Calcite film coatings composed of nanoneedles can form on the surfaces of CA fibers while maintaining the fibrous and macroporous structures if the concentration of PAA is in a suitable range. In the presence of a suitable concentration of PAA, the acidic PAA molecules will first adsorb onto the surface of CA fibers by the interaction between the OH moieties of CA and the carboxylic groups of PAA, and then the redundant carboxylic groups of PAA can ionically bind Ca(2+) ions on the surfaces of CA fibers, resulting in the local supersaturation of Ca(2+) ions on and near the fiber surface, which can induce the nucleation of CaCO(3) on the CA fibers instead of in bulk solution. Calcite microtube networks on the macroscale can be prepared by the removal of CA fibers after the CA@CaCO(3) composite is treated with acetone. When the CA fiber scaffold is immersed in CaCl(2) solution with an extended incubation time, the first deposited calcite coatings can act as secondary substrate, leading to the formation of smaller calcite mesocrystal fibers. The present work proves that inorganic crystal growth can occur even at an organic interface without the need for commensurability between the lattices of the organic and inorganic counterparts.

  5. Gel-spinning of mimetic collagen and collagen/nano-carbon fibers: Understanding multi-scale influences on molecular ordering and fibril alignment.

    PubMed

    Green, Emily C; Zhang, Yiying; Li, Heng; Minus, Marilyn L

    2017-01-01

    Synthetic gel-spun collagen and collagen/nano-carbon fibers were found to exhibit structural mimicry comparable to native tendons. X-ray scattering and microscopy analyses are used to characterize the molecular and fibrillar alignment in the synthetic fibers, where D-banding is observed throughout the spun fibers - consistent with native collagen. For the composite collagen/nano-carbon fibers, the morphology and dispersion quality of the nano-carbons within was found to play a significant role in influencing collagen molecular ordering and fibril alignment. Fibrillar and molecular alignment was also better preserved during elongation of the composites as compared to the control collagen fibers. These results show the structural influence of a rigid inclusion on the collagen fibril structure. Both dry- and wet-state tensile testing were performed on the collagen fibers, and these results show behavior comparable to the native materials. Dry-state tests also reveal interfacial interaction between the nano-fillers and the collagen fibrils through theoretical analysis. Wet-state tensile testing indicates the structure-property behavior of the mimetic hierarchical structure within the synthetic fibers.

  6. Orientational alignment in solids from bidimensional isotropic-anisotropic nuclear magnetic resonance spectroscopy: applications to the analysis of aramide fibers.

    PubMed

    Sachleben, J R; Frydman, L

    1997-02-01

    The use of two-dimensional isotropic-anisotropic correlation spectroscopy for the analysis of orientational alignment in solids is presented. The theoretical background and advantages of this natural-abundance 13C NMR method of measurement are discussed, and demonstrated with a series of powder and single-crystal variable-angle correlation spectroscopy (VACSY) experiments on model systems. The technique is subsequently employed to analyze the orientational distributions of three polymer fibers: Kevlar 29, Kevlar 49 and Kevlar 149. Using complementary two-dimensional NMR data recorded on synthetic samples of poly(p-phenyleneterephthalamide), the precursor of Kevlar, it was found that these commercial fibers possess molecules distributed over a very narrow orientational range with respect to the macroscopic director. The widths measured for these director distribution arrangements were (12 +/- 1.5) degrees for Kevlar 29, (15 +/- 1.5) degrees for Kevlar 49, and (8 +/- 1.5) degrees for Kevlar 149. These figures compare well with previous results obtained for non-commercial fiber samples derived from the same polymer.

  7. Fabrication and modeling of dynamic multipolymer nanofibrous scaffolds.

    PubMed

    Baker, Brendon M; Nerurkar, Nandan L; Burdick, Jason A; Elliott, Dawn M; Mauck, Robert L

    2009-10-01

    Aligned nanofibrous scaffolds hold tremendous potential for the engineering of dense connective tissues. These biomimetic micropatterns direct organized cell-mediated matrix deposition and can be tuned to possess nonlinear and anisotropic mechanical properties. For these scaffolds to function in vivo, however, they must either recapitulate the full dynamic mechanical range of the native tissue upon implantation or must foster cell infiltration and matrix deposition so as to enable construct maturation to meet these criteria. In our recent studies, we noted that cell infiltration into dense aligned structures is limited but could be expedited via the inclusion of a distinct rapidly eroding sacrificial component. In the present study, we sought to further the fabrication of dynamic nanofibrous constructs by combining multiple-fiber populations, each with distinct mechanical characteristics, into a single composite nanofibrous scaffold. Toward this goal, we developed a novel method for the generation of aligned electrospun composites containing rapidly eroding (PEO), moderately degradable (PLGA and PCL/PLGA), and slowly degrading (PCL) fiber populations. We evaluated the mechanical properties of these composites upon formation and with degradation in a physiologic environment. Furthermore, we employed a hyperelastic constrained-mixture model to capture the nonlinear and time-dependent properties of these scaffolds when formed as single-fiber populations or in multipolymer composites. After validating this model, we demonstrated that by carefully selecting fiber populations with differing mechanical properties and altering the relative fraction of each, a wide range of mechanical properties (and degradation characteristics) can be achieved. This advance allows for the rational design of nanofibrous scaffolds to match native tissue properties and will significantly enhance our ability to fabricate replacements for load-bearing tissues of the musculoskeletal system.

  8. FABRICATION AND MODELING OF DYNAMIC MULTI-POLYMER NANOFIBROUS SCAFFOLDS

    PubMed Central

    Baker, Brendon M.; Nerurkar, Nandan L.; Burdick, Jason A.; Elliott, Dawn M.; Mauck, Robert L.

    2010-01-01

    Aligned nanofibrous scaffolds hold tremendous potential for the engineering of dense connective tissues. These biomimetic micro-patterns direct organized, cell-mediated matrix deposition, and can be tuned to possess nonlinear and anisotropic mechanical properties. For these scaffolds to function in vivo, however, they must either recapitulate the full dynamic mechanical range of the native tissue upon implantation, or must foster cell infiltration and matrix deposition so as to enable construct maturation to meet these criteria. In our recent studies, we noted that cell infiltration into dense aligned structures is limited, but could be expedited via the inclusion of a distinct, rapidly eroding sacrificial component. In the present study, we sought to further the fabrication of dynamic nanofibrous constructs by combining multiple fiber populations, each with distinct mechanical characteristics, into a single composite nanofibrous scaffold. Towards this goal, we developed a novel method for the generation of aligned electrospun composites containing rapidly eroding (PEO), moderately degradable (PLGA and PCL/PLGA), and slowly degrading (PCL) fiber populations. We evaluated the mechanical properties of these composites upon formation and with degradation in a physiologic environment. Further, we employed a hyperelastic constrained mixture model to capture the nonlinear and time-dependent properties of these scaffolds when formed as single-fiber populations or in multi-polymer composites. After validating this model, we demonstrated that by carefully selecting fiber populations with differing mechanical properties, and altering the relative fraction of each, a wide range of mechanical properties (and degradation characteristics) can be achieved. This advance allows for the rational design of nanofibrous scaffolds to match native tissue properties, and will significantly enhance our ability to fabricate replacements for load bearing tissues of the musculoskeletal system

  9. Meniscus tissue engineering using a novel combination of electrospun scaffolds and human meniscus cells embedded within an extracellular matrix hydrogel.

    PubMed

    Baek, Jihye; Chen, Xian; Sovani, Sujata; Jin, Sungho; Grogan, Shawn P; D'Lima, Darryl D

    2015-04-01

    Meniscus injury and degeneration have been linked to the development of secondary osteoarthritis (OA). Therapies that successfully repair or replace the meniscus are, therefore, likely to prevent or delay OA progression. We investigated the novel approach of building layers of aligned polylactic acid (PLA) electrospun (ES) scaffolds with human meniscus cells embedded in extracellular matrix (ECM) hydrogel to lead to formation of neotissues that resemble meniscus-like tissue. PLA ES scaffolds with randomly oriented or aligned fibers were seeded with human meniscus cells derived from vascular or avascular regions. Cell viability, cell morphology, and gene expression profiles were monitored via confocal microscopy, scanning electron microscopy (SEM), and real-time polymerase chain reaction (PCR), respectively. Seeded scaffolds were used to produce multilayered constructs and were examined via histology and immunohistochemistry. Morphology and mechanical properties of PLA scaffolds (with and without cells) were influenced by fiber direction of the scaffolds. Both PLA scaffolds supported meniscus tissue formation with increased COL1A1, SOX9, and COMP, yet no difference in gene expression was found between random and aligned PLA scaffolds. Overall, ES materials, which possess mechanical strength of meniscus and can support neotissue formation, show potential for use in cell-based meniscus regeneration strategies.

  10. Preparation of polypyrrole-embedded electrospun poly(lactic acid) nanofibrous scaffolds for nerve tissue engineering

    PubMed Central

    Zhou, Jun-feng; Wang, Yi-guo; Cheng, Liang; Wu, Zhao; Sun, Xiao-dan; Peng, Jiang

    2016-01-01

    Polypyrrole (PPy) is a biocompatible polymer with good conductivity. Studies combining PPy with electrospinning have been reported; however, the associated decrease in PPy conductivity has not yet been resolved. We embedded PPy into poly(lactic acid) (PLA) nanofibers via electrospinning and fabricated a PLA/PPy nanofibrous scaffold containing 15% PPy with sustained conductivity and aligned topography. There was good biocompatibility between the scaffold and human umbilical cord mesenchymal stem cells as well as Schwann cells. Additionally, the direction of cell elongation on the scaffold was parallel to the direction of fibers. Our findings suggest that the aligned PLA/PPy nanofibrous scaffold is a promising biomaterial for peripheral nerve regeneration. PMID:27904497

  11. Preparation and characterization of aligned porous PCL/zein scaffolds as drug delivery systems via improved unidirectional freeze-drying method.

    PubMed

    Fereshteh, Zeinab; Fathi, Mohammadhossein; Bagri, Akbar; Boccaccini, Aldo R

    2016-11-01

    A novel type of drug-delivery scaffold based on poly(ε-caprolactone) (PCL) and zein blends was prepared by improved unidirectional freeze-drying. Scaffolds with tube-like pore structure and high porosity, up to 89%, were obtained by adjusting the concentration of the PCL and zein solutions. Characters of the prepared scaffolds, such as microstructural, porosity, and compressive strength, were evaluated. The hydrophilicity and the degradability of the composite films were investigated in contact with phosphate buffer saline (PBS). It was found that the presence of zein accelerates the degradation rate of the scaffolds in the period time of investigation (28days). The results showed an acceptable way for controlling the in vitro degradation behavior of PCL composite scaffolds by adapting the concentration of zein. In vitro protein release and degradation results revealed that the absolute weight loss of the PCL/zein scaffolds exhibited an increasing trend by increasing the amount of zein concentration in the scaffolds. The drug delivery capability of the scaffolds was tested using tetracycline hydrochloride (TCH). Sustained release of the drug was obtained, and it was found that the proportion of zein in the scaffold had a great impact on the drug release kinetics. The results demonstrated the potential of the PCL/zein biocomposite scaffolds as a suitable candidate in tissue engineering strategies for bone defect treatment.

  12. A Comparison of Electrospun Polymers Reveals Poly(3-Hydroxybutyrate) Fiber as a Superior Scaffold for Cardiac Repair

    PubMed Central

    Castellano, Delia; Blanes, María; Marco, Bruno; Cerrada, Inmaculada; Ruiz-Saurí, Amparo; Pelacho, Beatriz; Araña, Miriam; Montero, Jose A.; Cambra, Vicente; Prosper, Felipe

    2014-01-01

    The development of biomaterials for myocardial tissue engineering requires a careful assessment of their performance with regards to functionality and biocompatibility, including the immune response. Poly(3-hydroxybutyrate) (PHB), poly(e-caprolactone) (PCL), silk, poly-lactic acid (PLA), and polyamide (PA) scaffolds were generated by electrospinning, and cell compatibility in vitro, and immune response and cardiac function in vitro and in vivo were compared with a noncrosslinked collagen membrane (Col) control material. Results showed that cell adhesion and growth of mesenchymal stem cells, cardiomyocytes, and cardiac fibroblasts in vitro was dependent on the polymer substrate, with PHB and PCL polymers permitting the greatest adhesion/growth of cells. Additionally, polymer substrates triggered unique expression profiles of anti- and pro-inflammatory cytokines in human peripheral blood mononuclear cells. Implantation of PCL, silk, PLA, and PA patches on the epicardial surface of healthy rats induced a classical foreign body reaction pattern, with encapsulation of polymer fibers and induction of the nonspecific immune response, whereas Col and PHB patches were progressively degraded. When implanted on infarcted rat heart, Col, PCL, and PHB reduced negative remodeling, but only PHB induced significant angiogenesis. Importantly, Col and PHB modified the inflammatory response to an M2 macrophage phenotype in cardiac tissue, indicating a more beneficial reparative process and remodeling. Collectively, these results identify PHB as a superior substrate for cardiac repair. PMID:24564648

  13. A comparison of electrospun polymers reveals poly(3-hydroxybutyrate) fiber as a superior scaffold for cardiac repair.

    PubMed

    Castellano, Delia; Blanes, María; Marco, Bruno; Cerrada, Inmaculada; Ruiz-Saurí, Amparo; Pelacho, Beatriz; Araña, Miriam; Montero, Jose A; Cambra, Vicente; Prosper, Felipe; Sepúlveda, Pilar

    2014-07-01

    The development of biomaterials for myocardial tissue engineering requires a careful assessment of their performance with regards to functionality and biocompatibility, including the immune response. Poly(3-hydroxybutyrate) (PHB), poly(e-caprolactone) (PCL), silk, poly-lactic acid (PLA), and polyamide (PA) scaffolds were generated by electrospinning, and cell compatibility in vitro, and immune response and cardiac function in vitro and in vivo were compared with a noncrosslinked collagen membrane (Col) control material. Results showed that cell adhesion and growth of mesenchymal stem cells, cardiomyocytes, and cardiac fibroblasts in vitro was dependent on the polymer substrate, with PHB and PCL polymers permitting the greatest adhesion/growth of cells. Additionally, polymer substrates triggered unique expression profiles of anti- and pro-inflammatory cytokines in human peripheral blood mononuclear cells. Implantation of PCL, silk, PLA, and PA patches on the epicardial surface of healthy rats induced a classical foreign body reaction pattern, with encapsulation of polymer fibers and induction of the nonspecific immune response, whereas Col and PHB patches were progressively degraded. When implanted on infarcted rat heart, Col, PCL, and PHB reduced negative remodeling, but only PHB induced significant angiogenesis. Importantly, Col and PHB modified the inflammatory response to an M2 macrophage phenotype in cardiac tissue, indicating a more beneficial reparative process and remodeling. Collectively, these results identify PHB as a superior substrate for cardiac repair.

  14. Syndecan-1-Induced ECM Fiber Alignment Requires Integrin αvβ3 and Syndecan-1 Ectodomain and Heparan Sulfate Chains.

    PubMed

    Yang, Ning; Friedl, Andreas

    2016-01-01

    Expression of the cell surface proteoglycan syndecan-1 (Sdc1) is frequently induced in stromal fibroblasts of invasive breast carcinomas. We have recently identified a correlation between stromal Sdc1 expression and extracellular matrix (ECM) fiber alignment, both in vitro and in vivo. ECMs derived from Sdc1-positive human mammary fibroblasts (HMF) showed an aligned fiber architecture, which contrasted markedly with the more random fiber arrangement in the ECM produced by Sdc1-negative HMFs. We further demonstrated that aligned fiber architecture promotes the directional migration and invasion of breast carcinoma cells. To decipher the molecular mechanisms governing the formation of an aligned, invasion-permissive ECM, a series of Sdc1 mutants was introduced into HMF. We found that both the ectodomain and heparan sulfate chains of Sdc1 were required for full activity of Sdc1 in regulating ECM alignment, while transmembrane and cytoplasmic domains were dispensable. Sdc1 regulates the activities of several integrins via its ectodomain. Integrins are key players in the assembly of fibronectin-rich ECM. In addition, integrins are capable of regulating cell morphology and cell shape and orientation may affect ECM architecture. Therefore, we investigated the role of integrins in Sdc1-mediated ECM fiber alignment. Sdc1-overexpressing HMF gained an enhanced spindle-shaped morphology when cultured in an overconfluent state under conditions permissive for ECM production, which was partially reversed by siRNA-mediated silencing of β3 integrin expression. Moreover, suppression of αvβ3 integrin activity by a function-blocking antibody or β3 knockdown largely abolished the aligned ECM fiber architecture and consequently the invasion-permissive properties of the ECM induced by Sdc1. The results suggest that Sdc1 may modulate fibronectin fibrillogenesis and/or alter cell morphology during ECM production through αvβ3 integrin, thereby mediating ECM fiber alignment

  15. Design of Electrically Conductive Structural Composites by Modulating Aligned CVD-Grown Carbon Nanotube Length on Glass Fibers.

    PubMed

    He, Delong; Fan, Benhui; Zhao, Hang; Lu, Xiaoxin; Yang, Minhao; Liu, Yu; Bai, Jinbo

    2017-01-25

    Function-integration in glass fiber (GF) reinforced polymer composites is highly desired for developing lightweight structures and devices with improved performance and structural health monitoring. In this study, homogeneously aligned carbon nanotube (CNT) shell was in situ grafted on GF by chemical vapor deposition (CVD). It was demonstrated that the CNT shell thickness and weight fraction can be modulated by controlling the CVD conditions. The obtained hierarchical CNTs-GF/epoxy composites show highly improved electrical conductivity and thermo-mechanical and flexural properties. The composite through-plane and in-plane electrical conductivities increase from a quasi-isolator value to ∼3.5 and 100 S/m, respectively, when the weight fraction of CNTs grafted on GF fabric varies from 0% to 7%, respectively. Meanwhile, the composite storage modulus and flexural modulus and strength improve as high as 12%, 21%, and 26%, respectively, with 100% retention of the glass transition temperature. The reinforcing mechanisms are investigated by analyzing the composite microstructure and the interfacial adhesion and wetting properties of CNTs-GF hybrids. Moreover, the specific damage-related resistance variation characteristics could be employed to in situ monitor the structural health state of the composites. The outstanding electrical and structural properties of the CNTs-GF composites were due to the specific interfacial and interphase structures created by homogeneously grafting aligned CNTs on each GF of the fabric.

  16. Vertically aligned carbon nanotubes/carbon fiber paper composite to support Pt nanoparticles for direct methanol fuel cell application

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Yi, Xi-bin; Liu, Shuo; Fan, Hui-Li; Ju, Wei; Wang, Qi-Chun; Ma, Jie

    2017-03-01

    Vertically aligned carbon nanotubes (VACNTs) grown on carbon fiber paper (CFP) by plasma enhanced chemical vapor deposition is introduced as a catalyst support material for direct methanol fuel cells (DMFCs). Well dispersed Pt nanoparticles on VACNTs surface are prepared by impregnation-reduction method. The VACNTs on CFP possess well-maintained alignment, large surface area and good electrical conductivity, which leading to the formation of Pt particles with a smaller size and enhance the Pt utilization rate. The structure and nature of resulting Pt/VACNTs/CFP catalysts for methanol oxidation are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning electron microscope (SEM). With the aid of VACNTs, well-dispersed Pt catalysts enable the reversibly rapid redox kinetic since electron transport efficiently passes through a one-dimensional pathway, which leads to enhance the catalytic activity and Pt utilization rate. Compared with the Pt/XC-72/CFP electrode, the electrochemical measurements results display that the Pt/VACNTs/CFP catalyst shows much higher electrocatalytic activity and better stability for methanol oxidation. In addition, the oxidation current from 200 to 1200 s decayed more slowly for the Pt/VACNTs/CFP than that of the Pt/XC-72/CFP catalysts, indicating less accumulation of adsorbed CO species. All those results imply that the Pt/VACNTs/CFP has a great potential for applications in DMFCs.

  17. Fabrication and material properties of fibrous PHBV scaffolds depending on the cross-ply angle for tissue engineering.

    PubMed

    Kim, Yang-Hee; Min, Young-Ki; Lee, Byong-Taek

    2012-11-01

    Fibrous PHBV cross-ply scaffolds were fabricated using the electrospinning technique. The electrospun fibers were arranged depending on angles of alignment, which were 180°, 90°, 60°, and 45°. The stress and strain values of the fibrous PHBV cross-ply scaffolds increased as the cross-ply angle increased. At 180°, the strength and strain values of the fibers depended on tensile loading directions. At an alignment of 90°, the PHBV scaffolds had a stress value of 3.5 MPa, which was more than two times higher than the random structure. The cell morphology and proliferation of L-929 cells was strongly dependant on the fiber alignment and the best results were observed when the angle alignment was high. The results of this study showed that the cross-ply structure of the PHBV scaffold affected not only the cell adhesion and spreading properties but also dictated the mechanical properties, which were dependent on the angles of alignment.

  18. Vertically aligned carbon nanotube-sheathed carbon fibers as pristine microelectrodes for selective monitoring of ascorbate in vivo.

    PubMed

    Xiang, Ling; Yu, Ping; Hao, Jie; Zhang, Meining; Zhu, Lin; Dai, Liming; Mao, Lanqun

    2014-04-15

    Using as-synthesized vertically aligned carbon nanotube-sheathed carbon fibers (VACNT-CFs) as microelectrodes without any postsynthesis functionalization, we have developed in this study a new method for in vivo monitoring of ascorbate with high selectivity and reproducibility. The VACNT-CFs are formed via pyrolysis of iron phthalocyanine (FePc) on the carbon fiber support. After electrochemical pretreatment in 1.0 M NaOH solution, the pristine VACNT-CF microelectrodes exhibit typical microelectrode behavior with fast electron transfer kinetics for electrochemical oxidation of ascorbate and are useful for selective ascorbate monitoring even with other electroactive species (e.g., dopamine, uric acid, and 5-hydroxytryptamine) coexisting in rat brain. Pristine VACNT-CFs are further demonstrated to be a reliable and stable microelectrode for in vivo recording of the dynamic increase of ascorbate evoked by intracerebral infusion of glutamate. Use of a pristine VACNT-CF microelectrode can effectively avoid any manual electrode modification and is free from person-to-person and/or electrode-to-electrode deviations intrinsically associated with conventional CF electrode fabrication, which often involves electrode surface modification with randomly distributed CNTs or other pretreatments, and hence allows easy fabrication of highly selective, reproducible, and stable microelectrodes even by nonelectrochemists. Thus, this study offers a new and reliable platform for in vivo monitoring of neurochemicals (e.g., ascorbate) to largely facilitate future studies on the neurochemical processes involved in various physiological events.

  19. Multiscale white matter fiber tract coregistration: a new feature-based approach to align diffusion tensor data.

    PubMed

    Leemans, A; Sijbers, J; De Backer, S; Vandervliet, E; Parizel, P

    2006-06-01

    In this paper an automatic multiscale feature-based rigid-body coregistration technique for diffusion tensor imaging (DTI) based on the local curvature kappa and torsion tau of the white matter (WM) fiber pathways is presented. As a similarity measure, the mean squared difference (MSD) of corresponding fiber pathways in (kappa, tau)-space is chosen. After the MSD is minimized along the arc length of the curve, principal component analysis is applied to calculate the transformation parameters. In addition, a scale-space representation of the space curves is incorporated, resulting in a multiscale robust coregistration technique. This fully automatic technique inherently allows one to apply region of interest (ROI) coregistration, and is adequate for performing both global and local transformations. Simulations were performed on synthetic DT data to evaluate the coregistration accuracy and precision. An in vivo coregistration example is presented and compared with a voxel-based coregistration approach, demonstrating the feasibility and advantages of the proposed technique to align DT data of the human brain.

  20. Dynamic mechanical analysis and high strain-rate energy absorption characteristics of vertically aligned carbon nanotube reinforced woven fiber-glass composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The dynamic mechanical behavior and energy absorption characteristics of nano-enhanced functionally graded composites, consisting of 3 layers of vertically aligned carbon nanotube (VACNT) forests grown on woven fiber-glass (FG) layer and embedded within 10 layers of woven FG, with polyester (PE) and...

  1. Wet-laid soy fiber reinforced hydrogel scaffold: Fabrication, mechano-morphological and cell studies.

    PubMed

    Wood, Andrew T; Everett, Dominique; Budhwani, Karim I; Dickinson, Brenna; Thomas, Vinoy

    2016-06-01

    Among materials used in biomedical applications, hydrogels have received consistent linear growth in interest over the past decade due to their large water volume and saliency to the natural extracellular matrix. These materials are often limited due to their sub-optimal mechanical properties which are typically improved via chemical or physical crosslinking. Chemical crosslinking forms strong inter-polymer bonds but typically uses reagents that are cytotoxic while physical crosslinking is more temperamental to environmental changes but can be formed without these toxic reagents. In this study, we added a fiber-reinforcement phase to a poly(vinyl alcohol) (PVA) hydrogel formed through successive freezing-thawing cycles by incorporating a non-woven microfiber mat formed by the wet-lay process. By reinforcing the hydrogel with a wet-laid fibrous mat, the ultimate tensile strength and modulus increased from 0.11 ± 0.01 MPa and 0.17 ± 0.02 kPa to 0.24 ± 0.02 MPa and 5.76 ± 1.12 kPa, respectively. An increase in toughness and elongation was also found increasing from 2.52 ± 0.37 MPa to 25.6 ± 3.84 and 51.89 ± 5.16% to 111.16 ± 9.68%, respectively. The soy fibers were also found to induce minimal cytotoxicity with endothelial cell viability showing 96.51% ± 1.91 living cells after a 48 h incubation. This approach to hydrogel-reinforcement presents a rapid, tunable method by which hydrogels can attain increased mechanical properties without sacrificing their inherent biologically favorable properties.

  2. Novel 3D electrospun scaffolds with fibers oriented randomly and evenly in three dimensions to closely mimic the unique architectures of extracellular matrices in soft tissues: fabrication and mechanism study.

    PubMed

    Cai, Shaobo; Xu, Helan; Jiang, Qiuran; Yang, Yiqi

    2013-02-19

    In this work, novel electrospun scaffolds with fibers oriented randomly and evenly in three dimensions (3D) including in the thickness direction were developed based on the principle of electrostatic repulsion. This unique structure is different from most electrospun scaffolds with fibers oriented mainly in one direction. The structure of novel 3D scaffolds could more closely mimic the 3D randomly oriented fibrous architectures in many native extracellular matrices (ECMs). The cell culture results of this study indicated that, instead of becoming flattened cells when cultured in conventional electrospun scaffolds, the cells cultured on novel 3D scaffolds could develop into stereoscopic topographies, which highly simulated in vivo 3D cellular morphologies and are believed to be of vital importance for cells to function and differentiate appropriately. Also, due to the randomly oriented fibrous structure, improvement of nearly 5 times in cell proliferation could be observed when comparing our 3D scaffolds with 2D counterparts after 7 days of cell culture, while most currently reported 3D scaffolds only showed 1.5- to 2.5-fold improvement for the similar comparison. One mechanism of this fabrication process has also been proposed and showed that the rapid delivery of electrons on the fibers was the crucial factor for formation of 3D architectures.

  3. Axially aligned organic fibers and amorphous calcium phosphate form the claws of a terrestrial isopod (Crustacea).

    PubMed

    Vittori, Miloš; Srot, Vesna; Žagar, Kristina; Bussmann, Birgit; van Aken, Peter A; Čeh, Miran; Štrus, Jasna

    2016-08-01

    Skeletal elements that are exposed to heavy mechanical loads may provide important insights into the evolutionary solutions to mechanical challenges. We analyzed the microscopic architecture of dactylus claws in the woodlice Porcellio scaber and correlated these observations with analyses of the claws' mineral composition with energy dispersive X-ray spectrometry (EDX), electron energy loss spectroscopy (EELS) and selected area electron diffraction (SAED). Extraordinarily, amorphous calcium phosphate is the predominant mineral in the claw endocuticle. Unlike the strongly calcified exocuticle of the dactylus base, the claw exocuticle is devoid of mineral and is highly brominated. The architecture of the dactylus claw cuticle is drastically different from that of other parts of the exoskeleton. In contrast to the quasi-isotropic structure with chitin-protein fibers oriented in multiple directions, characteristic of the arthropod exoskeleton, the chitin-protein fibers and mineral components in the endocuticle of P. scaber claws are exclusively axially oriented. Taken together, these characteristics suggest that the claw cuticle is highly structurally anisotropic and fracture resistant and can be explained as adaptations to predominant axial loading of the thin, elongated claws. The nanoscale architecture of the isopod claw may inspire technological solutions in the design of durable machine elements subjected to heavy loading and wear.

  4. Solvent-free fabrication of three dimensionally aligned polycaprolactone microfibers for engineering of anisotropic tissues.

    PubMed

    An, Jia; Chua, Chee Kai; Leong, Kah Fai; Chen, Chih-Hao; Chen, Jyh-Ping

    2012-10-01

    Fabrication of aligned microfiber scaffolds is critical in successful engineering of anisotropic tissues such as tendon, ligaments and nerves. Conventionally, aligned microfiber scaffolds are two dimensional and predominantly fabricated by electrospinning which is solvent dependent. In this paper, we report a novel technique, named microfiber melt drawing, to fabricate a bundle of three dimensionally aligned polycaprolactone microfibers without using any organic solvent. This technique is simple yet effective. It has been demonstrated that polycaprolactone microfibers of 10 μm fiber diameter can be directly drawn from a 2 mm orifice. Orifice diameter, temperature and take-up speed significantly influence the final linear density and fiber diameter of the microfibers. Mechanical test suggests that mechanical properties such as stiffness and breaking force of microfiber bundles can be easily adjusted by the number of fibers. In vitro study shows that these microfibers are able to support the proliferation of human dermal fibroblasts over 7 days. In vivo result of Achilles tendon repair in a rabbit model shows that the microfibers were highly infiltrated by tendon tissue as early as in 1 month, besides, the repaired tendon have a well-aligned tissue structure under the guidance of aligned microfibers. However whether these three dimensionally aligned microfibers can induce three dimensionally aligned cells remains inconclusive.

  5. Neuron-derived FGF9 is essential for scaffold formation of Bergmann radial fibers and migration of granule neurons in the cerebellum.

    PubMed

    Lin, Yongshun; Chen, Lijie; Lin, Chunhong; Luo, Yongde; Tsai, Robert Y L; Wang, Fen

    2009-05-01

    Although fibroblast growth factor 9 (FGF9) is widely expressed in the central nervous system (CNS), the function of FGF9 in neural development remains undefined. To address this question, we deleted the Fgf9 gene specifically in the neural tube and demonstrated that FGF9 plays a key role in the postnatal migration of cerebellar granule neurons. Fgf9-null mice showed severe ataxia associated with disrupted Bergmann fiber scaffold formation, impaired granule neuron migration, and upset Purkinje cell maturation. Ex vivo cultured wildtype or Fgf9-null glia displayed a stellate morphology. Coculture with wildtype neurons, but not Fgf9-deficient neurons, or treating with FGF1 or FGF9 induced the cells to adopt a radial glial morphology. In situ hybridization showed that Fgf9 was expressed in neurons and immunostaining revealed that FGF9 was broadly distributed in both neurons and Bergmann glial radial fibers. Genetic analyses revealed that the FGF9 activities in cerebellar development are primarily transduced by FGF receptors 1 and 2. Furthermore, inhibition of the MAP kinase pathway, but not the PI3K/AKT pathway, abrogated the FGF activity to induce glial morphological changes, suggesting that the activity is mediated by the MAP kinase pathway. This work demonstrates that granule neurons secrete FGF9 to control formation of the Bergmann fiber scaffold, which in turn, guides their own inward migration and maturation of Purkinje cells.

  6. Influence of random and oriented electrospun fibrous poly(lactic-co-glycolic acid) scaffolds on neural differentiation of mouse embryonic stem cells.

    PubMed

    Sperling, Laura E; Reis, Karina P; Pozzobon, Laura G; Girardi, Carolina S; Pranke, Patricia

    2017-05-01

    Engineering neural tissue by combining biodegradable materials, cells and growth factors is a promising strategy for the treatment of central and peripheral nervous system injuries. In this study, neural differentiation of mouse embryonic stem cells (mESCs) was investigated in combination with three dimensional (3D) electrospun nanofibers as a substitute for the extracellular matrix (ECM). Nano/microfibrous poly(lactic-co-glycolic acid) (PLGA) 3D scaffolds were fabricated through electrospinning and characterized. The scaffolds consisted of either a randomly oriented or an aligned structure of PLGA fibers. The mESCs were induced to differentiate into neuronal lineage and the effect of the polymer and fiber orientation on cell survival, morphology and differentiation efficiency was studied. The neural progenitors derived from the mESCs could survive and migrate onto the fibrous scaffolds. Aligned fibers provided more contact guidance with the neurites preferentially extending along the long axis of fiber. The mESCs differentiated into neural lineages expressing neural markers as seen by the immunocytochemistry. The nestin and beta3-tubulin expression was enhanced on the PLGA aligned fibers in comparison with the other groups, as seen by the quantitative analysis. Taken together, a combination of electrospun fiber scaffolds and mESC derived neural progenitor cells could provide valuable information about the effects of topology on neural differentiation and axonal regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1333-1345, 2017.

  7. Electrospun scaffolds for multiple tissues regeneration in vivo through topography dependent induction of lineage specific differentiation.

    PubMed

    Yin, Zi; Chen, Xiao; Song, Hai-Xin; Hu, Jia-Jie; Tang, Qiao-Mei; Zhu, Ting; Shen, Wei-Liang; Chen, Jia-Lin; Liu, Huanhuan; Heng, Boon Chin; Ouyang, Hong-Wei

    2015-03-01

    Physical topographic cues from various substrata have been shown to exert profound effects on the growth and differentiation of stem cells due to their niche-mimicking features. However, the biological function of different topographic materials utilized as bio-scaffolds in vivo have not been rigorously characterized. This study investigated the divergent differentiation pathways of mesenchymal stem cells (MSCs) and neo-tissue formation trigged by aligned and randomly-oriented fibrous scaffolds, both in vitro and in vivo. The aligned group was observed to form more mature tendon-like tissue in the Achilles tendon injury model, as evidenced by histological scoring and collagen I immunohistochemical staining data. In contrast, the randomly-oriented group exhibited much chondrogenesis and subsequent bone tissue formation through ossification. Additionally, X-ray imaging and osteocalcin immunohistochemical staining also demonstrated that osteogenesis in vivo is driven by randomly oriented topography. Furthermore, MSCs on the aligned substrate exhibited tenocyte-like morphology and enhanced tenogenic differentiation compared to cells grown on randomly-oriented scaffold. qRT-PCR analysis of osteogenic marker genes and alkaline phosphatase (ALP) staining demonstrated that MSCs cultured on randomly-oriented fiber scaffolds displayed enhanced osteogenic differentiation compared with cells cultured on aligned fiber scaffolds. Finally, it was demonstrated that cytoskeletal tension release abrogated the divergent differentiation pathways on different substrate topography. Collectively, these findings illustrate the relationship between topographic cues of the scaffold and their inductive role in tissue regeneration; thus providing an insight into future development of smart functionalized bio-scaffold design and its application in tissue engineering.

  8. Tissue engineering scaffolds electrospun from cotton cellulose.

    PubMed

    He, Xu; Cheng, Long; Zhang, Ximu; Xiao, Qiang; Zhang, Wei; Lu, Canhui

    2015-01-22

    Nonwovens of cellulose nanofibers were fabricated by electrospinning of cotton cellulose in its LiCl/DMAc solution. The key factors associated with the electrospinning process, including the intrinsic properties of cellulose solutions, the rotating speed of collector and the applied voltage, were systematically investigated. XRD data indicated the electrospun nanofibers were almost amorphous. When increasing the rotating speed of the collector, preferential alignment of fibers along the drawing direction and improved molecular orientation were revealed by scanning electron microscope and polarized FTIR, respectively. Tensile tests indicated the strength of the nonwovens along the orientation direction could be largely improved when collected at a higher speed. In light of the excellent biocompatibility and biodegradability as well as their unique porous structure, the nonwovens were further assessed as potential tissue engineering scaffolds. Cell culture experiments demonstrated human dental follicle cells could proliferate rapidly not only on the surface but also in the entire scaffold.

  9. Nitrogen-doped aligned carbon nanotube/graphene sandwiches: facile catalytic growth on bifunctional natural catalysts and their applications as scaffolds for high-rate lithium-sulfur batteries.

    PubMed

    Tang, Cheng; Zhang, Qiang; Zhao, Meng-Qiang; Huang, Jia-Qi; Cheng, Xin-Bing; Tian, Gui-Li; Peng, Hong-Jie; Wei, Fei

    2014-09-17

    Nitrogen-doped aligned CNT/graphene sandwiches are rationally designed and in-situ fabricated by a facile catalytic growth on bifunctional natural catalysts that exhibit high-rate performances as scaffolds for lithium-sulfur batteries, with a high initial capacity of 1152 mA h g(-1) at 1.0 C. A remarkable capacity of 770 mA h g(-1) can be achieved at 5.0 C. Such a design strategy for materials opens up new perspectives to novel advanced functional composites, especially interface-modified hierarchical nanocarbons for broad applications.

  10. Constitutive modeling of an electrospun tubular scaffold used for vascular tissue engineering.

    PubMed

    Hu, Jin-Jia

    2015-08-01

    In this study, we sought to model the mechanical behavior of an electrospun tubular scaffold previously reported for vascular tissue engineering with hyperelastic constitutive equations. Specifically, the scaffolds were made by wrapping electrospun polycaprolactone membranes that contain aligned fibers around a mandrel in such a way that they have microstructure similar to the native arterial media. The biaxial stress-stretch data of the scaffolds made of moderately or highly aligned fibers with three different off-axis fiber angles α (30°, 45°, and 60°) were fit by a phenomenological Fung model and a series of structurally motivated models considering fiber directions and fiber angle distributions. In particular, two forms of fiber strain energy in the structurally motivated model for a linear and a nonlinear fiber stress-strain relation, respectively, were tested. An isotropic neo-Hookean strain energy function was also added to the structurally motivated models to examine its contribution. The two forms of fiber strain energy did not result in significantly different goodness of fit for most groups of the scaffolds. The absence of the neo-Hookean term in the structurally motivated model led to obvious nonlinear stress-stretch fits at a greater axial stretch, especially when fitting data from the scaffolds with a small α. Of the models considered, the Fung model had the overall best fitting results; its applications are limited because of its phenomenological nature. Although a structurally motivated model using the nonlinear fiber stress-strain relation with the neo-Hookean term provided fits comparably as good as the Fung model, the values of its model parameters exhibited large within-group variations. Prescribing the dispersion of fiber orientation in the structurally motivated model, however, reduced the variations without compromising the fits and was thus considered to be the best structurally motivated model for the scaffolds. It appeared that the

  11. Dye-sensitized solar cells with vertically aligned TiO2 nanowire arrays grown on carbon fibers.

    PubMed

    Cai, Xin; Wu, Hongwei; Hou, Shaocong; Peng, Ming; Yu, Xiao; Zou, Dechun

    2014-02-01

    One-dimensional semiconductor TiO2 nanowires (TNWs) have received widespread attention from solar cell and related optoelectronics scientists. The controllable synthesis of ordered TNW arrays on arbitrary substrates would benefit both fundamental research and practical applications. Herein, vertically aligned TNW arrays in situ grown on carbon fiber (CF) substrates through a facile, controllable, and seed-assisted thermal process is presented. Also, hierarchical TiO2 -nanoparticle/TNW arrays were prepared that favor both the dye loading and depressed charge recombination of the CF/TNW photoanode. An impressive conversion efficiency of 2.48 % (under air mass 1.5 global illumination) and an apparent efficiency of 4.18 % (with a diffuse board) due to the 3D light harvesting of the wire solar cell were achieved. Moreover, efficient and inexpensive wire solar cells made from all-CF electrodes and completely flexible CF-based wire solar cells were demonstrated, taking into account actual application requirements. This work may provide an intriguing avenue for the pursuit of lightweight, cost-effective, and high-performance flexible/wearable solar cells.

  12. Fabrication and application of nanofibrous scaffolds in tissue engineering.

    PubMed

    Li, Wan-Ju; Tuan, Rocky S

    2009-03-01

    Nanofibers fabricated by electrospinning are morphological mimics of fibrous components of the native extracellular matrix, making nanofibrous scaffolds ideal for three-dimensional cell culture and tissue engineering applications. Although electrospinning is not a conventional technique in cell biology, the experimental setup may be constructed in a relatively straightforward manner, and the procedure can be carried out by individuals with limited engineering experience. Here, we detail a protocol for electrospinning of nanofibers and provide relevant specific details concerning the optimization of fiber formation (Basic Protocol 1). The protocol also includes conditions required for preparing biodegradable polymer solutions for the fabrication of nonwoven and aligned nanofibrous scaffolds suitable for various cell/tissue applications. In addition, information on effective cell loading into nanofibrous scaffolds and cellular constructs grown in a bioreactor is provided (Basic Protocol 2). Instructions for building the electrospinning apparatus are also included (see the Support Protocol).

  13. Mechanical properties of electrospun bilayer fibrous membranes as potential scaffolds for tissue engineering.

    PubMed

    Pu, Juan; Komvopoulos, Kyriakos

    2014-06-01

    Bilayer fibrous membranes of poly(l-lactic acid) (PLLA) were fabricated by electrospinning, using a parallel-disk mandrel configuration that resulted in the sequential deposition of a layer with fibers aligned across the two parallel disks and a layer with randomly oriented fibers, both layers deposited in a single process step. Membrane structure and fiber alignment were characterized by scanning electron microscopy and two-dimensional fast Fourier transform. Because of the intricacies of the generated electric field, bilayer membranes exhibited higher porosity than single-layer membranes consisting of randomly oriented fibers fabricated with a solid-drum collector. However, despite their higher porosity, bilayer membranes demonstrated generally higher elastic modulus, yield strength and toughness than single-layer membranes with random fibers. Bilayer membrane deformation at relatively high strain rates comprised multiple abrupt microfracture events characterized by discontinuous fiber breakage. Bilayer membrane elongation yielded excessive necking of the layer with random fibers and remarkable fiber stretching (on the order of 400%) in the layer with fibers aligned in the stress direction. In addition, fibers in both layers exhibited multiple localized necking, attributed to the nonuniform distribution of crystalline phases in the fibrillar structure. The high membrane porosity, good mechanical properties, and good biocompatibility and biodegradability of PLLA (demonstrated in previous studies) make the present bilayer membranes good scaffold candidates for a wide range of tissue engineering applications.

  14. Melt electrospinning of poly(ε-caprolactone) scaffolds: phenomenological observations associated with collection and direct writing.

    PubMed

    Brown, Toby D; Edin, Fredrik; Detta, Nicola; Skelton, Anthony D; Hutmacher, Dietmar W; Dalton, Paul D

    2014-12-01

    Melt electrospinning and its additive manufacturing analogue, melt electrospinning writing (MEW), are two processes which can produce porous materials for applications where solvent toxicity and accumulation in solution electrospinning are problematic. This study explores the melt electrospinning of poly(ε-caprolactone) (PCL) scaffolds, specifically for applications in tissue engineering. The research described here aims to inform researchers interested in melt electrospinning about technical aspects of the process. This includes rapid fiber characterization using glass microscope slides, allowing influential processing parameters on fiber morphology to be assessed, as well as observed fiber collection phenomena on different collector substrates. The distribution and alignment of melt electrospun PCL fibers can be controlled to a certain degree using patterned collectors to create large numbers of scaffolds with shaped macroporous architectures. However, the buildup of residual charge in the collected fibers limits the achievable thickness of the porous template through such scaffolds. One challenge identified for MEW is the ability to control charge buildup so that fibers can be placed accurately in close proximity, and in many centimeter heights. The scale and size of scaffolds produced using MEW, however, indicate that this emerging process will fill a technological niche in biofabrication.

  15. ERK Signals: Scaffolding Scaffolds?

    PubMed Central

    Casar, Berta; Crespo, Piero

    2016-01-01

    ERK1/2 MAP Kinases become activated in response to multiple intra- and extra-cellular stimuli through a signaling module composed of sequential tiers of cytoplasmic kinases. Scaffold proteins regulate ERK signals by connecting the different components of the module into a multi-enzymatic complex by which signal amplitude and duration are fine-tuned, and also provide signal fidelity by isolating this complex from external interferences. In addition, scaffold proteins play a central role as spatial regulators of ERKs signals. In this respect, depending on the subcellular localization from which the activating signals emanate, defined scaffolds specify which substrates are amenable to be phosphorylated. Recent evidence has unveiled direct interactions among different scaffold protein species. These scaffold-scaffold macro-complexes could constitute an additional level of regulation for ERK signals and may serve as nodes for the integration of incoming signals and the subsequent diversification of the outgoing signals with respect to substrate engagement. PMID:27303664

  16. Design and analysis of tissue engineering scaffolds that mimic soft tissue mechanical anisotropy.

    PubMed

    Courtney, Todd; Sacks, Michael S; Stankus, John; Guan, Jianjun; Wagner, William R

    2006-07-01

    Tissue engineered constructs must exhibit tissue-like functional properties, including mechanical behavior comparable to the native tissues they are intended to replace. Moreover, the ability to reversibly undergo large strains can help to promote and guide tissue growth. Electrospun poly (ester urethane) ureas (ES-PEUU) are elastomeric and allow for the control of fiber diameter, porosity, and degradation rate. ES-PEUU scaffolds can be fabricated to have a well-aligned fiber network, which is important for applications involving mechanically anisotropic soft tissues. We have developed ES-PEUU scaffolds under variable speed conditions and modeled the effects of fiber orientation on the macro-mechanical properties of the scaffold. To illustrate the ability to simulate native tissue mechanical behavior, we demonstrated that the high velocity spun scaffolds exhibited highly anisotropic mechanical properties closely resembling the native pulmonary heart valve leaflet. Moreover, use of the present fiber-level structural constitutive model allows for the determination of electrospinning conditions to tailor ES-PEUU scaffolds for specific soft tissue applications. The results of this study will help to provide the basis for rationally designed mechanically anisotropic soft tissue engineered implants.

  17. Cauda equina-derived extracellular matrix for fabrication of nanostructured hybrid scaffolds applied to neural tissue engineering.

    PubMed

    Wen, Xiaoxiao; Wang, Yu; Guo, Zhiyuan; Meng, Haoye; Huang, Jingxiang; Zhang, Li; Zhao, Bin; Zhao, Qing; Zheng, Yudong; Peng, Jiang

    2015-03-01

    Extracellular matrix (ECM) components have become important candidate materials for use as neural scaffolds for neural tissue engineering. In the current study, we prepared cauda equina-derived ECM materials for the production of scaffolds. Natural porcine cauda equina was decellularized using Triton X-100 and sodium deoxycholate, shattered physically, and made into a suspension by differential centrifugation. The decellularization procedure resulted in the removal of >94% of the nuclear material and preserved the extracellular collagen and sulfated glycosaminoglycan. Immunofluorescent staining confirmed the presence of collagen type I, laminin, and fibronectin in the ECM. The cauda equine-derived ECM was blended with poly(l-lactide-co-glycolide) (PLGA) to fabricate nanostructured scaffolds using electrospinning. The incorporation of the ECM increased the hydrophilicity of the scaffolds. Fourier transform infrared spectroscopy and multiphoton-induced autofluorescence images showed the presence of the ECM in the scaffolds. ECM/PLGA scaffolds were beneficial for the survival of Schwann cells compared with scaffolds consisting of PLGA alone, and the aligned fibers could regulate cell morphologic features by modulating cellular orientation. Axons in the dorsal root ganglia explants extended to a greater extent along ECM/PLGA compared with PLGA-alone fibers. The cauda equina ECM might be a promising material for forming scaffolds for use in neural tissue engineering.

  18. Nanofiber Alignment Regulates NIH3T3 Cell Orientation and Cytoskeletal Gene Expression on Electrospun PCL+Gelatin Nanofibers

    PubMed Central

    Fee, Timothy; Surianarayanan, Swetha; Downs, Crawford; Zhou, Yong; Berry, Joel

    2016-01-01

    To examine the influence of substrate topology on the behavior of fibroblasts, tissue engineering scaffolds were electrospun from polycaprolactone (PCL) and a blend of PCL and gelatin (PCL+Gel) to produce matrices with both random and aligned nanofibrous orientations. The addition of gelatin to the scaffold was shown to increase the hydrophilicity of the PCL matrix and to increase the proliferation of NIH3T3 cells compared to scaffolds of PCL alone. The orientation of nanofibers within the matrix did not have an effect on the proliferation of adherent cells, but cells on aligned substrates were shown to elongate and align parallel to the direction of substrate fiber alignment. A microarray of cyotoskeleton regulators was probed to examine differences in gene expression between cells grown on an aligned and randomly oriented substrates. It was found that transcriptional expression of eight genes was statistically different between the two conditions, with all of them being upregulated in the aligned condition. The proteins encoded by these genes are linked to production and polymerization of actin microfilaments, as well as focal adhesion assembly. Taken together, the data indicates NIH3T3 fibroblasts on aligned substrates align themselves parallel with their substrate and increase production of actin and focal adhesion related genes. PMID:27196306

  19. The design of electrospun PLLA nanofiber scaffolds compatible with serum-free growth of primary motor and sensory neurons.

    PubMed

    Corey, Joseph M; Gertz, Caitlyn C; Wang, Bor-Shuen; Birrell, Lisa K; Johnson, Sara L; Martin, David C; Feldman, Eva L

    2008-07-01

    Aligned electrospun nanofibers direct neurite growth and may prove effective for repair throughout the nervous system. Applying nanofiber scaffolds to different nervous system regions will require prior in vitro testing of scaffold designs with specific neuronal and glial cell types. This would be best accomplished using primary neurons in serum-free media; however, such growth on nanofiber substrates has not yet been achieved. Here we report the development of poly(L-lactic acid) (PLLA) nanofiber substrates that support serum-free growth of primary motor and sensory neurons at low plating densities. In our study, we first compared materials used to anchor fibers to glass to keep cells submerged and maintain fiber alignment. We found that poly(lactic-co-glycolic acid) (PLGA) anchors fibers to glass and is less toxic to primary neurons than bandage and glue used in other studies. We then designed a substrate produced by electrospinning PLLA nanofibers directly on cover slips pre-coated with PLGA. This substrate retains fiber alignment even when the fiber bundle detaches from the cover slip and keeps cells in the same focal plane. To see if increasing wettability improves motor neuron survival, some fibers were plasma etched before cell plating. Survival on etched fibers was reduced at the lower plating density. Finally, the alignment of neurons grown on this substrate was equal to nanofiber alignment and surpassed the alignment of neurites from explants tested in a previous study. This substrate should facilitate investigating the behavior of many neuronal types on electrospun fibers in serum-free conditions.

  20. A Biomimetic Collagen-Apatite Scaffold with a Multi-Level Lamellar Structure for Bone Tissue Engineering

    PubMed Central

    Xia, Z.; Villa, M. M.; Wei, M.

    2014-01-01

    Collagen-apatite (Col-Ap) scaffolds have been widely employed for bone tissue engineering. We fabricated a Col-Ap scaffold with a unique multi-level lamellar structure consisting of co-aligned micro and macro pores. The basic building blocks of this scaffold are bone-like mineralized collagen fibers developed via a biomimetic self-assembly process in a collagen-containing modified simulated body fluid (m-SBF). This biomimetic method preserves the structural integrity and great tensile strength of collagen by reinforcing the collagen hydrogel with apatite nano-particles. Unidirectional aligned macro pores with a size of 63.8 to 344 μm are created by controlling the freezing rate and direction. The thickness of Col-Ap lamellae can be adjusted in the range 3.6 to 23 μm depending on the self-compression time. Furthermore, the multi-level lamellar structure has led to a twelve-fold increase in Young's modulus and a two-fold increase in the compression modulus along the aligned direction compared to a scaffold of the same composition with an isotropic equiaxed pore structure. Moreover, this novel lamellar scaffold supports the attachment and spreading of MC3T3-E1osteoblasts. Therefore, owing to the biomimetic composition, tunable structure, improved mechanical strength, and good biocompatibility of this novel scaffold, it has great potential to be used in bone tissue engineering applications. PMID:24999428

  1. Electrospun aligned PHBV/collagen nanofibers as substrates for nerve tissue engineering.

    PubMed

    Prabhakaran, Molamma P; Vatankhah, Elham; Ramakrishna, Seeram

    2013-10-01

    Nerve regeneration following the injury of nerve tissue remains a major issue in the therapeutic medical field. Various bio-mimetic strategies are employed to direct the nerve growth in vitro, among which the chemical and topographical cues elicited by the scaffolds are crucial parameters that is primarily responsible for the axon growth and neurite extension involved in nerve regeneration. We carried out electrospinning for the first time, to fabricate both random and aligned nanofibers of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate; PHBV) and composite PHBV/collagen nanofibers with fiber diameters in the range of 386-472 nm and 205-266 nm, respectively. To evaluate the potential of electrospun aligned nanofibers of PHBV and composite scaffolds as a substrate for nerve regeneration, we cultured nerve cells (PC12) and studied the biocompatibility effect along with neurite extension by immunostaining studies. Cell proliferation assays showed 40.01% and 5.48% higher proliferation of nerve cells on aligned PHBV/Coll50:50 nanofibers compared to cell proliferation on aligned PHBV and PHBV/Col75:25 nanofibers, respectively. Aligned nanofibers of PHBV/Coll provided contact guidance to direct the orientation of nerve cells along the direction of the fibers, thus endowing elongated cell morphology, with bi-polar neurite extensions required for nerve regeneration. Results showed that aligned PHBV/Col nanofibers are promising substrates than the random PHBV/Col nanofibers for application as bioengineered grafts for nerve tissue regeneration.

  2. Fibrous scaffolds fabricated by emulsion electrospinning: from hosting capacity to in vivo biocompatibility.

    PubMed

    Spano, F; Quarta, A; Martelli, C; Ottobrini, L; Rossi, R M; Gigli, G; Blasi, L

    2016-04-28

    Electrospinning is a versatile method for preparing functional three-dimensional scaffolds. Synthetic and natural polymers have been used to produce micro- and nanofibers that mimic extracellular matrices. Here, we describe the use of emulsion electrospinning to prepare blended fibers capable of hosting aqueous species and releasing them in solution. The existence of an aqueous and a non-aqueous phase allows water-soluble molecules to be introduced without altering the structure and the degradation of the fibers, and means that their release properties under physiological conditions can be controlled. To demonstrate the loading capability and flexibility of the blend, various species were introduced, from magnetic nanoparticles and quantum rods to biological molecules. Cellular studies showed the spontaneous adhesion and alignment of cells along the fibers. Finally, in vivo experiments demonstrated the high biocompatibility and safety of the scaffolds up to 21 days post-implantation.

  3. Investigating Breast Cancer Cell Behavior Using Tissue Engineering Scaffolds

    PubMed Central

    Guiro, Khadidiatou; Patel, Shyam A.; Greco, Steven J.; Rameshwar, Pranela; Arinzeh, Treena L.

    2015-01-01

    Despite early detection through the use of mammograms and aggressive intervention, breast cancer (BC) remains a clinical dilemma. BC can resurge after >10 years of remission. Studies indicate that BC cells (BCCs) with self-renewal and chemoresistance could be involved in dormancy. The majority of studies use in vitro, two-dimensional (2-D) monolayer cultures, which do not recapitulate the in vivo microenvironment. Thus, to determine the effect of three-dimensional (3-D) microenvironment on BCCs, this study fabricated tissue engineering scaffolds made of poly (ε-caprolactone) (PCL) having aligned or random fibers. Random and aligned fibers mimic, respectively, the random and highly organized collagen fibers found in the tumor extracellular matrix. Chemoresistant BCCs were obtained by treating with carboplatin. Western blot analysis of carboplatin resistant (treated) MDA-MB-231 (highly invasive, basal-like) and T47D (low-invasive, luminal) BCCs showed an increase in Bcl-2, Oct-4 and Sox-2, suggesting protection from apoptosis and increase in stem-like markers. Further studies with MDA-MB-231 BCCs seeded on the scaffolds showed little to no change in cell number over time for non-treated BCCs whereas on tissue culture polystyrene (TCP), non-treated BCCs displayed a significant increase in cell number at days 4 and 7 as compared to day 1 (p<0.05). Treated BCCs did not proliferate on TCP and the fibrous scaffolds. Little to no cyclin D1 was expressed for non-treated BCCs on TCP. On fibrous scaffolds, non-treated BCCs stained for cyclin D1 during the 7-day culture period. Treated BCCs expressed cyclin D1 on TCP and fibrous scaffolds during the 7-day culture period. Proliferation, viability and cell cycle analysis indicated that this 3-D culture prompted the aggressive BCCs to adopt a dormant phenotype, while the treated BCCs retained their phenotype. The findings indicate that random and aligned fibrous PCL scaffolds may provide a useful system to study how the 3-D

  4. Integration of 3D Printed and Micropatterned Polycaprolactone Scaffolds for Guidance of Oriented Collagenous Tissue Formation In vivo

    PubMed Central

    Pilipchuk, Sophia P; Monje, Alberto; Jiao, Yizu; Hao, Jie; Kruger, Laura; Flanagan, Colleen L; Hollister, Scott J

    2016-01-01

    Scaffold design incorporating multi-scale cues for clinically-relevant, aligned tissue regeneration has potential to improve structural and functional integrity of multi-tissue interfaces. The objective of this pre-clinical study was to develop poly(ε-caprolactone) (PCL) scaffolds with mesoscale and microscale architectural cues specific to human ligament progenitor cells and assess their ability to form aligned bone-ligament-cementum complexes in vivo. PCL scaffolds were designed to integrate a 3D printed bone region with a micropatterned PCL thin film consisting of grooved pillars. The patterned film region was seeded with human ligament cells, fibroblasts transduced with BMP-7 genes seeded within the bone region, and a tooth dentin segment positioned on the ligament region prior to subcutaneous implantation into a murine model. Results indicated increased tissue alignment in vivo using micropatterned PCL films, compared to random-porous PCL. At 6 weeks, 30um groove depth significantly enhanced oriented collagen fiber thickness, overall cell alignment, and nuclear elongation relative to 10um groove depth. This study demonstrates for the first time that scaffolds with combined hierarchical mesoscale and microscale features can align cells in vivo for oral tissue repair with potential for improving the regenerative response of other bone-ligament complexes. PMID:26820240

  5. Integration of 3D Printed and Micropatterned Polycaprolactone Scaffolds for Guidance of Oriented Collagenous Tissue Formation In Vivo.

    PubMed

    Pilipchuk, Sophia P; Monje, Alberto; Jiao, Yizu; Hao, Jie; Kruger, Laura; Flanagan, Colleen L; Hollister, Scott J; Giannobile, William V

    2016-03-01

    Scaffold design incorporating multiscale cues for clinically relevant, aligned tissue regeneration has potential to improve structural and functional integrity of multitissue interfaces. The objective of this preclinical study is to develop poly(ε-caprolactone) (PCL) scaffolds with mesoscale and microscale architectural cues specific to human ligament progenitor cells and assess their ability to form aligned bone-ligament-cementum complexes in vivo. PCL scaffolds are designed to integrate a 3D printed bone region with a micropatterned PCL thin film consisting of grooved pillars. The patterned film region is seeded with human ligament cells, fibroblasts transduced with bone morphogenetic protein-7 genes seeded within the bone region, and a tooth dentin segment positioned on the ligament region prior to subcutaneous implantation into a murine model. Results indicate increased tissue alignment in vivo using micropatterned PCL films, compared to random-porous PCL. At week 6, 30 μm groove depth significantly enhances oriented collagen fiber thickness, overall cell alignment, and nuclear elongation relative to 10 μm groove depth. This study demonstrates for the first time that scaffolds with combined hierarchical mesoscale and microscale features can align cells in vivo for oral tissue repair with potential for improving the regenerative response of other bone-ligament complexes.

  6. Imaging Analysis of Collagen Fiber Networks in Cusps of Porcine Aortic Valves: Effect of their Local Distribution and Alignment on Valve Functionality

    PubMed Central

    Mega, Mor; Marom, Gil; Halevi, Rotem; Hamdan, Ashraf; Bluestein, Danny; Haj-Ali, Rami

    2015-01-01

    The cusps of native Aortic Valve (AV) are composed of collagen bundles embedded in soft tissue, creating a heterogenic tissue with asymmetric alignment in each cusp. This study compares native collagen fiber networks (CFNs) with a goal to better understand their influence on stress distribution and valve kinematics. Images of CFNs from five porcine tricuspid AVs are analyzed and fluid-structure interaction models are generated based on them. Although the valves had similar overall kinematics, the CFNs had distinctive influence on local mechanics. The regions with dilute CFN are more prone to damage since they are subjected to higher stress magnitudes. PMID:26406926

  7. Fibrous scaffolds fabricated by emulsion electrospinning: from hosting capacity to in vivo biocompatibility

    NASA Astrophysics Data System (ADS)

    Spano, F.; Quarta, A.; Martelli, C.; Ottobrini, L.; Rossi, R. M.; Gigli, G.; Blasi, L.

    2016-04-01

    Electrospinning is a versatile method for preparing functional three-dimensional scaffolds. Synthetic and natural polymers have been used to produce micro- and nanofibers that mimic extracellular matrices. Here, we describe the use of emulsion electrospinning to prepare blended fibers capable of hosting aqueous species and releasing them in solution. The existence of an aqueous and a non-aqueous phase allows water-soluble molecules to be introduced without altering the structure and the degradation of the fibers, and means that their release properties under physiological conditions can be controlled. To demonstrate the loading capability and flexibility of the blend, various species were introduced, from magnetic nanoparticles and quantum rods to biological molecules. Cellular studies showed the spontaneous adhesion and alignment of cells along the fibers. Finally, in vivo experiments demonstrated the high biocompatibility and safety of the scaffolds up to 21 days post-implantation.Electrospinning is a versatile method for preparing functional three-dimensional scaffolds. Synthetic and natural polymers have been used to produce micro- and nanofibers that mimic extracellular matrices. Here, we describe the use of emulsion electrospinning to prepare blended fibers capable of hosting aqueous species and releasing them in solution. The existence of an aqueous and a non-aqueous phase allows water-soluble molecules to be introduced without altering the structure and the degradation of the fibers, and means that their release properties under physiological conditions can be controlled. To demonstrate the loading capability and flexibility of the blend, various species were introduced, from magnetic nanoparticles and quantum rods to biological molecules. Cellular studies showed the spontaneous adhesion and alignment of cells along the fibers. Finally, in vivo experiments demonstrated the high biocompatibility and safety of the scaffolds up to 21 days post

  8. Electrospun silk fibroin fiber diameter influences in vitro dermal fibroblast behavior and promotes healing of ex vivo wound models

    PubMed Central

    Hodgkinson, Tom; Yuan, Xue-Feng

    2014-01-01

    Replicating the nanostructured components of extracellular matrix is a target for dermal tissue engineering and regenerative medicine. Electrospinning Bombyx mori silk fibroin (BMSF) allows the production of nano- to microscale fibrous scaffolds. For BMSF electrospun scaffolds to be successful, understanding and optimizing the cellular response to material morphology is essential. Primary human dermal fibroblast response to nine variants of BMSF scaffolds composed of nano- to microscale fibers ranging from ~250 to ~1200 nm was assessed in vitro with regard to cell proliferation, viability, cellular morphology, and gene expression. BMSF support of epithelial migration was then assessed through utilization of a novel ex vivo human skin wound healing model. Scaffolds composed of the smallest diameter fibers, ~250 -300 nm, supported cell proliferation significantly more than fibers with diameters approximately 1 μm (p < 0.001). Cell morphology was observed to depart from a stellate morphology with numerous cell -fiber interactions to an elongated, fiber-aligned morphology with interaction predominately with single fibers. The expressions of extracellular matrix genes, collagen types I and III (p < 0.001), and proliferation markers, proliferating cell nuclear antigen (p < 0.001), increased with decreasing fiber diameter. The re-epithelialization of ex vivo wound models was significantly improved with the addition of BMSF electrospun scaffolds, with migratory keratinocytes incorporated into scaffolds. BMSF scaffolds with nanofibrous architectures enhanced proliferation in comparison to microfibrous scaffolds and provided an effective template for migratory keratinocytes during re-epithelialization. The results may aid in the development of effective BMSF electrospun scaffolds for wound healing applications PMID:25383171

  9. Fiber

    MedlinePlus

    ... it can help with weight control. Fiber aids digestion and helps prevent constipation . It is sometimes used ... fiber attracts water and turns to gel during digestion. This slows digestion. Soluble fiber is found in ...

  10. Multiphasic Scaffolds for Periodontal Tissue Engineering

    PubMed Central

    Ivanovski, S.; Vaquette, C.; Gronthos, S.; Hutmacher, D.W.; Bartold, P.M.

    2014-01-01

    For a successful clinical outcome, periodontal regeneration requires the coordinated response of multiple soft and hard tissues (periodontal ligament, gingiva, cementum, and bone) during the wound-healing process. Tissue-engineered constructs for regeneration of the periodontium must be of a complex 3-dimensional shape and adequate size and demonstrate biomechanical stability over time. A critical requirement is the ability to promote the formation of functional periodontal attachment between regenerated alveolar bone, and newly formed cementum on the root surface. This review outlines the current advances in multiphasic scaffold fabrication and how these scaffolds can be combined with cell- and growth factor–based approaches to form tissue-engineered constructs capable of recapitulating the complex temporal and spatial wound-healing events that will lead to predictable periodontal regeneration. This can be achieved through a variety of approaches, with promising strategies characterized by the use of scaffolds that can deliver and stabilize cells capable of cementogenesis onto the root surface, provide biomechanical cues that encourage perpendicular alignment of periodontal fibers to the root surface, and provide osteogenic cues and appropriate space to facilitate bone regeneration. Progress on the development of multiphasic constructs for periodontal tissue engineering is in the early stages of development, and these constructs need to be tested in large animal models and, ultimately, human clinical trials. PMID:25139362

  11. Multiphasic scaffolds for periodontal tissue engineering.

    PubMed

    Ivanovski, S; Vaquette, C; Gronthos, S; Hutmacher, D W; Bartold, P M

    2014-12-01

    For a successful clinical outcome, periodontal regeneration requires the coordinated response of multiple soft and hard tissues (periodontal ligament, gingiva, cementum, and bone) during the wound-healing process. Tissue-engineered constructs for regeneration of the periodontium must be of a complex 3-dimensional shape and adequate size and demonstrate biomechanical stability over time. A critical requirement is the ability to promote the formation of functional periodontal attachment between regenerated alveolar bone, and newly formed cementum on the root surface. This review outlines the current advances in multiphasic scaffold fabrication and how these scaffolds can be combined with cell- and growth factor-based approaches to form tissue-engineered constructs capable of recapitulating the complex temporal and spatial wound-healing events that will lead to predictable periodontal regeneration. This can be achieved through a variety of approaches, with promising strategies characterized by the use of scaffolds that can deliver and stabilize cells capable of cementogenesis onto the root surface, provide biomechanical cues that encourage perpendicular alignment of periodontal fibers to the root surface, and provide osteogenic cues and appropriate space to facilitate bone regeneration. Progress on the development of multiphasic constructs for periodontal tissue engineering is in the early stages of development, and these constructs need to be tested in large animal models and, ultimately, human clinical trials.

  12. Engineering meniscus structure and function via multi-layered mesenchymal stem cell-seeded nanofibrous scaffolds.

    PubMed

    Fisher, Matthew B; Henning, Elizabeth A; Söegaard, Nicole; Bostrom, Marc; Esterhai, John L; Mauck, Robert L

    2015-06-01

    Despite advances in tissue engineering for the knee meniscus, it remains a challenge to match the complex macroscopic and microscopic structural features of native tissue, including the circumferentially and radially aligned collagen bundles essential for mechanical function. To mimic this structural hierarchy, this study developed multi-lamellar mesenchymal stem cell (MSC)-seeded nanofibrous constructs. Bovine MSCs were seeded onto nanofibrous scaffolds comprised of poly(ε-caprolactone) with fibers aligned in a single direction (0° or 90° to the scaffold long axis) or circumferentially aligned (C). Multi-layer groups (0°/0°/0°, 90°/90°/90°, 0°/90°/0°, 90°/0°/90°, and C/C/C) were created and cultured for a total of 6 weeks under conditions favoring fibrocartilaginous tissue formation. Tensile testing showed that 0° and C single layer constructs had stiffness values several fold higher than 90° constructs. For multi-layer groups, the stiffness of 0°/0°/0° constructs was higher than all other groups, while 90°/90°/90° constructs had the lowest values. Data for collagen content showed a general positive interactive effect for multi-layers relative to single layer constructs, while a positive interaction for stiffness was found only for the C/C/C group. Collagen content and cell infiltration occurred independent of scaffold alignment, and newly formed collagenous matrix followed the scaffold fiber direction. Structural hierarchies within multi-lamellar constructs dictated biomechanical properties, and only the C/C/C constructs with non-orthogonal alignment within layers featured positive mechanical reinforcement as a consequence of the layered construction. These multi-layer constructs may serve as functional substitutes for the meniscus as well as test beds to understand the complex mechanical principles that enable meniscus function.

  13. Engineering Meniscus Structure and Function via Multi-layered Mesenchymal Stem Cell-seeded Nanofibrous Scaffolds

    PubMed Central

    Fisher, Matthew B.; Henning, Elizabeth A.; Söegaard, Nicole; Bostrom, Marc; Esterhai, John L.; Mauck, Robert L.

    2015-01-01

    Despite advances in tissue engineering for the knee meniscus, it remains a challenge to match the complex macroscopic and microscopic structural features of native tissue, including the circumferentially and radially aligned collagen bundles essential for mechanical function. To mimic this structural hierarchy, this study developed multi-lamellar mesenchymal stem cell (MSC)-seeded nanofibrous constructs. Bovine MSCs were seeded onto nanofibrous scaffolds comprised of poly(ε-caprolactone) with fibers aligned in a single direction (0° or 90° to the scaffold long axis) or circumferentially aligned (C). Multi-layer groups (0°/0°/0°, 90°/90°/90°, 0°/90°/0°, 90°/0°/90°, and C/C/C) were created and cultured for a total of 6 weeks under conditions favoring fibrocartilaginous tissue formation. Tensile testing showed that 0° and C single layer constructs had stiffness values several fold higher than 90° constructs. For multi-layer groups, the stiffness of 0°/0°/0° constructs was higher than all other groups, while 90°/90°/90° constructs had the lowest values. Data for collagen content showed a general positive interactive effect for multi-layers relative to single layer constructs, while a positive interaction for stiffness was found only for the C/C/C group. Collagen content and cell infiltration occurred independent of scaffold alignment, and newly formed collagenous matrix followed the scaffold fiber direction. Structural hierarchies within multi-lamellar constructs dictated biomechanical properties, and only the C/C/C constructs with non-orthogonal alignment within layers featured positive mechanical reinforcement as a consequence of the layered construction. These multi-layer constructs may serve as functional substitutes for the meniscus as well as test beds to understand the complex mechanical principles that enable meniscus function. PMID:25817333

  14. Effects of Fiber Orientation on the Frictional Properties and Damage of Regenerative Articular Cartilage Surfaces

    PubMed Central

    Accardi, Mario Alberto; McCullen, Seth D.; Callanan, Anthony; Chung, Sangwon; Cann, Philippa M.

    2013-01-01

    Articular cartilage provides a low-friction, wear-resistant surface for diarthrodial joints. Due to overloading and overuse, articular cartilage is known to undergo significant wear and degeneration potentially resulting in osteoarthritis (OA). Regenerative medicine strategies offer a promising solution for the treatment of articular cartilage defects and potentially localized early OA. Such strategies rely on the development of materials to restore some aspects of cartilage. In this study, microfibrous poly(ɛ-caprolactone) scaffolds of varying fiber orientations (random and aligned) were cultured with bovine chondrocytes for 4 weeks in vitro, and the mechanical and frictional properties were evaluated. Mechanical properties were quantified using unconfined compression and tensile testing techniques. Frictional properties were investigated at physiological compressive strains occurring in native articular cartilage. Scaffolds were sheared along the fiber direction, perpendicular to the fiber direction and in random orientation. The evolution of damage as a result of shear was evaluated via white light interferometry and scanning electron microscopy. As expected, the fiber orientation strongly affected the tensile properties as well as the compressive modulus of the scaffolds. Fiber orientation did not significantly affect the equilibrium frictional coefficient, but it was, however, a key factor in dictating the evolution of surface damage on the surface. Scaffolds shear tested perpendicular to the fiber orientation displayed the highest surface damage. Our results suggest that the fiber orientation of the scaffold implanted in the joint could strongly affect its resistance to damage due to shear. Scaffold fiber orientation should thus be carefully considered when using microfibrous scaffolds. PMID:23688110

  15. 29 CFR 1910.28 - Safety requirements for scaffolding.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... opening, consisting of No. 18 gauge U.S. Standard Wire one-half-inch mesh or the equivalent, where persons.... (22) Wire or fiber rope used for scaffold suspension shall be capable of supporting at least six times..., wire rope supported scaffolds shall be used. (24) The use of shore scaffolds or lean-to scaffolds...

  16. Biocompatibility and Structural Features of Biodegradable Polymer Scaffolds.

    PubMed

    Nasonova, M V; Glushkova, T V; Borisov, V V; Velikanova, E A; Burago, A Yu; Kudryavtseva, Yu A

    2015-11-01

    We performed a comparative analysis of physicochemical properties and biocompatibility of scaffolds of different composition on the basis of biodegradable polymers fabricated by casting and electrospinning methods. For production of polyhydroxyalkanoate-based scaffolds by electrospinning method, the optimal concentration of the polymer was 8-10%. Fiber diameter and properties of the scaffold produced by electrospinning method depended on polymer composition. Addition of polycaprolactone increased elasticity of the scaffolds. Bio- and hemocompatibility of the scaffolds largely depended on the composition formulation and method of scaffold fabrication. Polylactide introduced into the composition of polyhydroxybutyrate-oxyvalerate scaffolds accelerated degradation and increased adhesive properties of the scaffolds.

  17. Patterned and functionalized nanofiber scaffolds in three-dimensional hydrogel constructs enhance neurite outgrowth and directional control

    NASA Astrophysics Data System (ADS)

    McMurtrey, Richard J.

    2014-12-01

    Objective. Neural tissue engineering holds incredible potential to restore functional capabilities to damaged neural tissue. It was hypothesized that patterned and functionalized nanofiber scaffolds could control neurite direction and enhance neurite outgrowth. Approach. A method of creating aligned electrospun nanofibers was implemented and fiber characteristics were analyzed using environmental scanning electron microscopy. Nanofibers were composed of polycaprolactone (PCL) polymer, PCL mixed with gelatin, or PCL with a laminin coating. Three-dimensional hydrogels were then integrated with embedded aligned nanofibers to support neuronal cell cultures. Microscopic images were captured at high-resolution in single and multi-focal planes with eGFP-expressing neuronal SH-SY5Y cells in a fluorescent channel and nanofiber scaffolding in another channel. Neuronal morphology and neurite tracking of nanofibers were then analyzed in detail. Main results. Aligned nanofibers were shown to enable significant control over the direction of neurite outgrowth in both two-dimensional (2D) and three-dimensional (3D) neuronal cultures. Laminin-functionalized nanofibers in 3D hyaluronic acid (HA) hydrogels enabled significant alignment of neurites with nanofibers, enabled significant neurite tracking of nanofibers, and significantly increased the distance over which neurites could extend. Specifically, the average length of neurites per cell in 3D HA constructs with laminin-functionalized nanofibers increased by 66% compared to the same laminin fibers on 2D laminin surfaces, increased by 59% compared to 2D laminin-coated surface without fibers, and increased by 1052% compared to HA constructs without fibers. Laminin functionalization of fibers also doubled average neurite length over plain PCL fibers in the same 3D HA constructs. In addition, neurites also demonstrated tracking directly along the fibers, with 66% of neurite lengths directly tracking laminin-coated fibers in 3D HA

  18. Fabrication of seamless electrospun collagen/PLGA conduits whose walls comprise highly longitudinal aligned nanofibers for nerve regeneration.

    PubMed

    Ouyang, Yuanming; Huang, Chen; Zhu, Yi; Fan, Cunyi; Ke, Qinfei

    2013-06-01

    An ideal nerve scaffold should supply structural guidance and trophic support to facilitate nerve regeneration. Aligned electrospun nanofibers have shown considerable promise for the precise guidance of regenerating axons in vitro and in vivo. Therefore, uniaxially aligned three-dimension (3D) nanofiberous scaffolds may allow regenerating axons to traverse large gaps to treat severe nerve injuries. However, the aligned 3D conduit was always rolled by an aligned 2-dimensional (2D) sheet in current fabrication methods, which was inconvenient for transplant due to the discontinuous joint and inconsistent size. We developed a modified one-step electrospinning technique to produce a seamless 3D nanofiberous nerve conduit (NC) with highly longitudinal aligned nanofibers that combines the biocompatibility of natural collagen and the strength of the synthetic polymer poly(lactic-co-glycolic acid) (PLGA). Scanning electron microscopy (SEM) confirmed the parallel alignment of the scaffold fibers. To test the effectiveness of these scaffolds at restoring neuronal connections, they were implanted into adult rats across a 13 mm sciatic nerve defect. Tests of, motor function, nerve conduction, axonal and Schwann cell morphology, and marker expression all revealed that uniaxially aligned seamless 3D electrospun collagen/PLGA NCs were superior to randomly oriented NCs and inferior to autografts for promoting axon regeneration, myelination, action potential propagation, neuromuscular transmission, and functional recovery. These uniaxially aligned seamless 3D electrospun collagen/PLGA nerve guides can also incorporate signaling molecules and additional structural cues to guide nerve growth, and so may be a promising substitute for autogenous nerve grafts.

  19. Comparison of adenovirus fiber, protein IX, and hexon capsomeres as scaffolds for vector purification and cell targeting

    SciTech Connect

    Campos, Samuel K.; Barry, Michael A. . E-mail: mab@bcm.edu

    2006-06-05

    The direct genetic modification of adenoviral capsid proteins with new ligands is an attractive means to confer targeted tropism to adenoviral vectors. Although several capsid proteins have been reported to tolerate the genetic fusion of foreign peptides and proteins, direct comparison of cell targeting efficiencies through the different capsomeres has been lacking. Likewise, direct comparison of with one or multiple ligands has not been performed due to a lack of capsid-compatible ligands available for retargeting. Here we utilize a panel of metabolically biotinylated Ad vectors to directly compare targeted transduction through the fiber, protein IX, and hexon capsomeres using a variety of biotinylated ligands including antibodies, transferrin, EGF, and cholera toxin B. These results clearly demonstrate that cell targeting with a variety of high affinity receptor-binding ligands is only effective when transduction is redirected through the fiber protein. In contrast, protein IX and hexon-mediated targeting by the same set of ligands failed to mediate robust vector targeting, perhaps due to aberrant trafficking at the cell surface or inside targeted cells. These data suggest that vector targeting by genetic incorporation of high affinity ligands will likely be most efficient through modification of the adenovirus fiber rather than the protein IX and hexon capsomeres. In contrast, single-step monomeric avidin affinity purification of Ad vectors using the metabolic biotinylation system is most effective through capsomeres like protein IX and hexon.

  20. The control of cell orientation using biodegradable alginate fibers fabricated by near-field electrospinning.

    PubMed

    Fuh, Yiin-Kuen; Wu, Yun-Chung; He, Zhe-Yu; Huang, Zih-Ming; Hu, Wei-Wen

    2016-05-01

    For spatially controlling cell alignment, near field electrospinning (NFES) was developed to direct-write alginate fiber patterns. Compared to randomly electrospun fibers, NFES fibers guided the extension of HEK 293T cells and the levels of cell alignment increased with decreasing fiber distances. However, these guiding fibers were unfavorable for cell adhesion and limited cell growth. To preserve cell alignment ability and improve biocompatibility, the stability of patterned alginate fibers was adjusted by regulating the level of ion crosslinking. These partially crosslinked NFES fibers demonstrated parallel line-patterns in the initial stage while gradually degraded with time. The reduction of fiber density increased the available area for cell growth and enhanced cell viability. On the other hand, aligned cells were still found on these degraded patterns, suggesting that cell morphologies were mainly guided during cell seeding. This dynamically controlled fiber pattern system fulfilled the need of controlling cell orientation and biocompatibility, thus was potential to modify scaffold surfaces for tissue engineering application.

  1. In Vivo Biocompatibility of PLGA-Polyhexylthiophene Nanofiber Scaffolds in a Rat Model

    PubMed Central

    Subramanian, Anuradha; Krishnan, Uma Maheswari; Sethuraman, Swaminathan

    2013-01-01

    Electroactive polymers have applications in tissue engineering as a physical template for cell adhesion and carry electrical signals to improve tissue regeneration. Present study demonstrated the biocompatibility and biodegradability of poly(lactide-co-glycolide)-poly(3-hexylthiophene) (PLGA-PHT) blend electrospun scaffolds in a subcutaneous rat model. The biocompatibility of PLGA-undoped PHT, PLGA-doped PHT, and aligned PLGA-doped PHT nanofibers was evaluated and compared with random PLGA fibers. The animals were sacrificed at 2, 4, and 8 weeks; the surrounding tissue along with the implant was removed to evaluate biocompatibility and biodegradability by histologic analysis and GPC, respectively. Histology results demonstrated that all scaffolds except PLGA-undoped PHT showed decrease in inflammation over time. It was observed that the aligned PLGA-doped PHT fibers elicited moderate response at 2 weeks, which further reduced to a mild response over time with well-organized tissue structure and collagen deposition. The degradation of aligned nanofibers was found to be very slow when compared to random fibers. Further, there was no reduction in the molecular weight of undoped form of PHT throughout the study. These experiments revealed the biocompatibility and biodegradability of PLGA-PHT nanofibers that potentiate it to be used as a biomaterial for various applications. PMID:23971031

  2. Injectable polyurethane composite scaffolds delay wound contraction and support cellular infiltration and remodeling in rat excisional wounds.

    PubMed

    Adolph, Elizabeth J; Hafeman, Andrea E; Davidson, Jeffrey M; Nanney, Lillian B; Guelcher, Scott A

    2012-02-01

    Injectable scaffolds present compelling opportunities for wound repair and regeneration because of their ability to fill irregularly shaped defects and deliver biologics such as growth factors. In this study, we investigated the properties of injectable polyurethane (PUR) biocomposite scaffolds and their application in cutaneous wound repair using a rat excisional model. The scaffolds have a minimal reaction exotherm and clinically relevant working and setting times. Moreover, the biocomposites have mechanical and thermal properties consistent with rubbery elastomers. In the rat excisional wound model, injection of settable biocomposite scaffolds stented the wounds at early time points, resulting in a regenerative rather than a scarring phenotype at later time points. Measurements of wound length and thickness revealed that the treated wounds were less contracted at day 7 compared to blank wounds. Analysis of cell proliferation and apoptosis showed that the scaffolds were biocompatible and supported tissue ingrowth. Myofibroblast formation and collagen fiber organization provided evidence that the scaffolds have a positive effect on extracellular matrix remodeling by disrupting the formation of an aligned matrix under elevated tension. In summary, we have developed an injectable biodegradable PUR biocomposite scaffold that enhances cutaneous wound healing in a rat model.

  3. Structure of uniaxially aligned 13C labeled silk fibroin fibers with solid state 13C-NMR

    NASA Astrophysics Data System (ADS)

    Demura, Makoto; Yamazaki, Yasunobu; Asakura, Tetsuo; Ogawa, Katsuaki

    1998-01-01

    Carbon-13 isotopic labeling of B. mori silk fibroin was achieved biosynthetically with [1- 13C] glycine in order to determine the carbonyl bond orientation angle of glycine sites with the silk fibroin. Angular dependence of 13C solid state NMR spectra of uniaxially oriented silk fibroin fiber block sample due to the carbonyl 13C chemical shift anisotropy was simulated according to the chemical shift transformation with Euler angles, αF and βF, from principal axis system (PAS) to fiber axis system (FAS). The another Euler angles, αDCO and βDCO, for transformation from PAS to the molecular symmetry axis were determined from the [1- 13C] glycine sequence model compounds for the silk fibroin. By the combination of these Euler angles, the carbonyl bond orientation angle with respect to FAS of the [1- 13C] glycine sites of the silk fibroin was determined to be 90 ± 5°. This value is in agreement with the X-ray diffraction and our previous solid state NMR data of B. mori silk fibroin fiber (a typical β-pleated sheet) within experimental error.

  4. Wrapping Aligned Carbon Nanotube Composite Sheets around Vanadium Nitride Nanowire Arrays for Asymmetric Coaxial Fiber-Shaped Supercapacitors with Ultrahigh Energy Density.

    PubMed

    Zhang, Qichong; Wang, Xiaona; Pan, Zhenghui; Sun, Juan; Zhao, Jingxin; Zhang, Jun; Zhang, Cuixia; Tang, Lei; Luo, Jie; Song, Bin; Zhang, Zengxing; Lu, Weibang; Li, Qingwen; Zhang, Yuegang; Yao, Yagang

    2017-04-12

    The emergence of fiber-shaped supercapacitors (FSSs) has led to a revolution in portable and wearable electronic devices. However, obtaining high energy density FSSs for practical applications is still a key challenge. This article exhibits a facile and effective approach to directly grow well-aligned three-dimensional vanadium nitride (VN) nanowire arrays (NWAs) on carbon nanotube (CNT) fiber with an ultrahigh specific capacitance of 715 mF/cm(2) in a three-electrode system. Benefiting from their intriguing structural features, we successfully fabricated a prototype asymmetric coaxial FSS (ACFSS) with a maximum operating voltage of 1.8 V. From core to shell, this ACFSS consists of a CNT fiber core coated with VN@C NWAs as the negative electrode, Na2SO4 poly(vinyl alcohol) (PVA) as the solid electrolyte, and MnO2/conducting polymer/CNT sheets as the positive electrode. The novel coaxial architecture not only fully enables utilization of the effective surface area and decreases the contact resistance between the two electrodes but also, more importantly, provides a short pathway for the ultrafast transport of axial electrons and ions. The electrochemical results show that the optimized ACFSS exhibits a remarkable specific capacitance of 213.5 mF/cm(2) and an exceptional energy density of 96.07 μWh/cm(2), the highest areal capacitance and areal energy density yet reported in FSSs. Furthermore, the device possesses excellent flexibility in that its capacitance retention reaches 96.8% after bending 5000 times, which further allows it to be woven into flexible electronic clothes with conventional weaving techniques. Therefore, the asymmetric coaxial architectural design allows new opportunities to fabricate high-performance flexible FSSs for future portable and wearable electronic devices.

  5. Fabrication of cell penetration enhanced poly (l-lactic acid-co-ɛ-caprolactone)/silk vascular scaffolds utilizing air-impedance electrospinning.

    PubMed

    Yin, Anlin; Li, Jiukai; Bowlin, Gary L; Li, Dawei; Rodriguez, Isaac A; Wang, Jing; Wu, Tong; Ei-Hamshary, Hany A; Al-Deyab, Salem S; Mo, Xiumei

    2014-08-01

    In the vascular prosthetic field, the prevailing thought is that for clinical, long-term success, especially bioresorbable grafts, cellular migration and penetration into the prosthetic structure is required to promote neointima formation and vascular wall development. In this study, we fabricated poly (l-lactic acid-co-ɛ-caprolactone) P(LLA-CL)/silk fibroin (SF) vascular scaffolds through electrospinning using both perforated mandrel subjected to various intraluminal air pressures (0-300kPa), and solid mandrel. The scaffolds were evaluated the cellular infiltration in vitro and mechanical properties. Vascular scaffolds were seeded with smooth muscle cells (SMCs) to evaluate cellular infiltration at 1, 7, and 14 days. The results revealed that air-impedance scaffolds allowed significantly more cell infiltration as compared to the scaffolds fabricated with solid mandrel. Meanwhile, results showed that both mandrel model and applied air pressure determined the interfiber distance and the alignment of fibers in the enhanced porosity regions of the structure which influenced cell infiltration. Uniaxial tensile testing indicated that the air-impedance scaffolds have sufficient ultimate strength, suture retention strength, and burst pressure as well as compliance approximating a native artery. In conclusion, the air-impedance scaffolds improved cellular infiltration without compromising overall biomechanical properties. These results support the scaffold's potential for vascular grafting and in situ regeneration.

  6. Winner of the Young Investigator Award of the Society for Biomaterials (USA) for 2016, 10th World Biomaterials Congress, May 17-22, 2016, Montreal QC, Canada: Aligned microribbon-like hydrogels for guiding three-dimensional smooth muscle tissue regeneration.

    PubMed

    Lee, Soah; Tong, Xinming; Han, Li-Hsin; Behn, Anthony; Yang, Fan

    2016-05-01

    Smooth muscle tissue is characterized by aligned structures, which is critical for its contractile functions. Smooth muscle injury is common and can be caused by various diseases and degenerative processes, and there remains a strong need to develop effective therapies for smooth muscle tissue regeneration with restored structures. To guide cell alignment, previously cells were cultured on 2D nano/microgrooved substrates, but such method is limited to fabricating 2D aligned cell sheets only. Alternatively, aligned electrospun nanofiber has been employed as 3D scaffold for cell alignment, but cells can only be seeded post fabrication, and nanoporosity of electrospun fiber meshes often leads to poor cell distribution. To overcome these limitations, we report aligned gelatin-based microribbons (µRBs) as macroporous hydrogels for guiding smooth muscle alignment in 3D. We developed aligned µRB-like hydrogels using wet spinning, which allows easy fabrication of tissue-scale (cm) macroporous matrices with alignment cues and supports direct cell encapsulation. The macroporosity within µRB-based hydrogels facilitated cell proliferation, new matrix deposition, and nutrient diffusion. In aligned µRB scaffold, smooth muscle cells showed high viability, rapid adhesion, and alignment following µRB direction. Aligned µRB scaffolds supported retention of smooth muscle contractile phenotype, and accelerated uniaxial deposition of new matrix (collagen I/IV) along the µRB. In contrast, cells encapsulated in conventional gelatin hydrogels remained round with matrix deposition limited to pericellular regions only. We envision such aligned µRB scaffold can be broadly applicable in growing other anisotropic tissues including tendon, nerves and blood vessel.

  7. Comparison of cell behavior on pva/pva-gelatin electrospun nanofibers with random and aligned configuration

    PubMed Central

    Huang, Chen-Yu; Hu, Keng-Hsiang; Wei, Zung-Hang

    2016-01-01

    Electrospinning technique is able to create nanofibers with specific orientation. Poly(vinyl alcohol) (PVA) have good mechanical stability but poor cell adhesion property due to the low affinity of protein. In this paper, extracellular matrix, gelatin is incorporated into PVA solution to form electrospun PVA-gelatin nanofibers membrane. Both randomly oriented and aligned nanofibers are used to investigate the topography-induced behavior of fibroblasts. Surface morphology of the fibers is studied by optical microscopy and scanning electron microscopy (SEM) coupled with image analysis. Functional group composition in PVA or PVA-gelatin is investigated by Fourier Transform Infrared (FTIR). The morphological changes, surface coverage, viability and proliferation of fibroblasts influenced by PVA and PVA-gelatin nanofibers with randomly orientated or aligned configuration are systematically compared. Fibroblasts growing on PVA-gelatin fibers show significantly larger projected areas as compared with those cultivated on PVA fibers which p-value is smaller than 0.005. Cells on PVA-gelatin aligned fibers stretch out extensively and their intracellular stress fiber pull nucleus to deform. Results suggest that instead of the anisotropic topology within the scaffold trigger the preferential orientation of cells, the adhesion of cell membrane to gelatin have substantial influence on cellular behavior. PMID:27917883

  8. Comparison of cell behavior on pva/pva-gelatin electrospun nanofibers with random and aligned configuration

    NASA Astrophysics Data System (ADS)

    Huang, Chen-Yu; Hu, Keng-Hsiang; Wei, Zung-Hang

    2016-12-01

    Electrospinning technique is able to create nanofibers with specific orientation. Poly(vinyl alcohol) (PVA) have good mechanical stability but poor cell adhesion property due to the low affinity of protein. In this paper, extracellular matrix, gelatin is incorporated into PVA solution to form electrospun PVA-gelatin nanofibers membrane. Both randomly oriented and aligned nanofibers are used to investigate the topography-induced behavior of fibroblasts. Surface morphology of the fibers is studied by optical microscopy and scanning electron microscopy (SEM) coupled with image analysis. Functional group composition in PVA or PVA-gelatin is investigated by Fourier Transform Infrared (FTIR). The morphological changes, surface coverage, viability and proliferation of fibroblasts influenced by PVA and PVA-gelatin nanofibers with randomly orientated or aligned configuration are systematically compared. Fibroblasts growing on PVA-gelatin fibers show significantly larger projected areas as compared with those cultivated on PVA fibers which p-value is smaller than 0.005. Cells on PVA-gelatin aligned fibers stretch out extensively and their intracellular stress fiber pull nucleus to deform. Results suggest that instead of the anisotropic topology within the scaffold trigger the preferential orientation of cells, the adhesion of cell membrane to gelatin have substantial influence on cellular behavior.

  9. Real-time quantification of proteins secreted by artificial connective tissue made from uni- or multidirectional collagen I scaffolds and oral mucosa fibroblasts.

    PubMed

    Bustos, Rosa Helena; Suesca, Edward; Millán, Diana; González, José Manuel; Fontanilla, Marta R

    2014-03-04

    Previously, we found that oral autologous artificial connective tissue (AACT) had a different protein secretion profile to that of clot-embedded AACT. Other oral mucosa substitutes, having different cell types and scaffolds, had dissimilar secretion profiles of proteins (including that for AACT) that influence healing outcome; thus, to ascertain the profiles of factors secreted by artificial tissue and whether they are influenced by their microstructure might help in understanding their bioactivity. An important component of tissue microstructure is the fiber orientation of the scaffold used for manufacturing it. This work developed a surface plasmon resonance (SPR) methodology to quantify factors secreted by oral artificial connective tissue (ACT) in culture medium, and a method to manufacture unidirectional laminar collagen I scaffolds. The SPR methodology was used for assessing differences in the protein secretion profile of ACT made with collagen scaffolds having different fiber orientation (unidirectional vs multidirectional). Oral fibroblasts seeded onto unidirectional scaffolds increased the secretion of six factors involved in modulating healing compared to those seeded onto multidirectional scaffolds. Histological analysis of uni- and multidirectional ACT showed that cells differ in their alignment and morphology. This SPR-methodology led to nanoscale detection of paracrine factors and might be useful to study biomarkers of three-dimensional cell growth, cell differentiation, and wound-healing progression.

  10. Bioactive nanofibrous scaffolds for regenerative endodontics.

    PubMed

    Bottino, M C; Kamocki, K; Yassen, G H; Platt, J A; Vail, M M; Ehrlich, Y; Spolnik, K J; Gregory, R L

    2013-11-01

    Here we report the synthesis, materials characterization, antimicrobial capacity, and cytocompatibility of novel antibiotic-containing scaffolds. Metronidazole (MET) or Ciprofloxacin/(CIP) was mixed with a polydioxanone (PDS)polymer solution at 5 and 25 wt% and processed into fibers. PDS fibers served as a control. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), tensile testing, and high-performance liquid chromatography (HPLC) were used to assess fiber morphology, chemical structure, mechanical properties, and drug release, respectively. Antimicrobial properties were evaluated against those of Porphyromonas gingivalis/Pg and Enterococcus faecalis/Ef. Cytotoxicity was assessed in human dental pulp stem cells (hDPSCs). Statistics were performed, and significance was set at the 5% level. SEM imaging revealed a submicron fiber diameter. FTIR confirmed antibiotic incorporation. The tensile values of hydrated 25 wt% CIP scaffold were significantly lower than those of all other groups. Analysis of HPLC data confirmed gradual, sustained drug release from the scaffolds over 48 hrs. CIP-containing scaffolds significantly (p < .00001) inhibited biofilm growth of both bacteria. Conversely, MET-containing scaffolds inhibited only Pg growth. Agar diffusion confirmed the antimicrobial properties against specific bacteria for the antibiotic-containing scaffolds. Only the 25 wt% CIP-containing scaffolds were cytotoxic. Collectively, this study suggests that polymer-based antibiotic-containing electrospun scaffolds could function as a biologically safe antimicrobial drug delivery system for regenerative endodontics.

  11. Electrospun polycaprolactone scaffolds with tailored porosity using two approaches for enhanced cellular infiltration.

    PubMed

    Zander, Nicole E; Orlicki, Joshua A; Rawlett, Adam M; Beebe, Thomas P

    2013-01-01

    The impact of mat porosity of polycaprolactone (PCL) electrospun fibers on the infiltration of neuron-like PC12 cells was evaluated using two different approaches. In the first method, bi-component aligned fiber mats were fabricated via the co-electrospinning of PCL with polyethylene oxide (PEO). Variation of the PEO flow rate, followed by selective removal of PEO from the PCL/PEO mesh, allowed for control of the porosity of the resulting scaffold. In the second method, aligned fiber mats were fabricated from various concentrations of PCL solutions to generate fibers with diameters between 0.13 ± 0.06 and 9.10 ± 4.1 μm. Of the approaches examined, the variation of PCL fiber diameter was found to be the better method for increasing the infiltration of PC12 cells, with the optimal infiltration into the ca. 1.5-mm-thick meshes observed for the mats with the largest fiber diameters, and hence largest pore sizes.

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

    PubMed

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

    2015-01-01

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

  13. Strategies for regeneration of components of nervous system: scaffolds, cells and biomolecules.

    PubMed

    Tian, Lingling; Prabhakaran, Molamma P; Ramakrishna, Seeram

    2015-03-01

    Nerve diseases including acute injury such as peripheral nerve injury (PNI), spinal cord injury (SCI) and traumatic brain injury (TBI), and chronic disease like neurodegeneration disease can cause various function disorders of nervous system, such as those relating to memory and voluntary movement. These nerve diseases produce great burden for individual families and the society, for which a lot of efforts have been made. Axonal pathways represent a unidirectional and aligned architecture allowing systematic axonal development within the tissue. Following a traumatic injury, the intricate architecture suffers disruption leading to inhibition of growth and loss of guidance. Due to limited capacity of the body to regenerate axonal pathways, it is desirable to have biomimetic approach that has the capacity to graft a bridge across the lesion while providing optimal mechanical and biochemical cues for tissue regeneration. And for central nervous system injury, one more extra precondition is compulsory: creating a less inhibitory surrounding for axonal growth. Electrospinning is a cost-effective and straightforward technique to fabricate extracellular matrix (ECM)-like nanofibrous structures, with various fibrous forms such as random fibers, aligned fibers, 3D fibrous scaffold and core-shell fibers from a variety of polymers. The diversity and versatility of electrospinning technique, together with functionalizing cues such as neurotrophins, ECM-based proteins and conductive polymers, have gained considerable success for the nerve tissue applications. We are convinced that in the future the stem cell therapy with the support of functionalized electrospun nerve scaffolds could be a promising therapy to cure nerve diseases.

  14. Optimization of a biomimetic poly-(lactic acid) ligament scaffold

    NASA Astrophysics Data System (ADS)

    Uehlin, Andrew F.

    The anterior cruciate ligament (ACL) is the most commonly injured ligament of the knee, often requiring orthopedic reconstruction using autograft or allograph tissue, both with significant disadvantages. As a result, tissue engineering an ACL replacement graft has been heavily investigated. The present study attempts to replicate the morphology and mechanical properties of the ACL using a nanomatrix composite of highly-aligned poly(lactic acid) (PLA) fibers with various surface and biochemical modifications. Additionally, this study attempts to recreate the natural mineralization gradient found at the ACL enthesis onto the scaffold, capable of inducing a favorable cellular response in vitro. Unidirectional electrospinning was used to create nanofibers of PLA, followed by an induced degradation of the nanofibers via 0.25M NaOH hydrolysis. The effects of the unidirectional electrospinning as well as the effects of NaOH hydrolysis on fiber alignment, fiber diameter, surface morphology, crystallinity, in vitro swelling, immobilization of fibrin, and mechanical properties were investigated, resulting in a modified morphology correlating to the microstructure of native ligament tissue with similar mechanical properties. Furthering the development of the PLA nanomatrix composite, a bioinkjet printer was used to immobilize nanoparticulate hydroxyapatite (HANP) on the surface of the scaffold. A series of 300pL droplets of HANP bioink were printed over a gradient pattern mimetic of (and spatially corresponding to) the mineralization gradient found over the microanatomy at the ACL enthesis. Proliferation and differentiation response of human mesenchymal stem cells (hMSCs) in vitro was assessed on a variety of conditions and combinations of the PLA nanofiber scaffold surface modifications (inclusive and exclusive of HANP, fibrin, and various time dependent NaOH treatments). It was found that a combinatory effect of the HANP gradient with fibrin on 20 minute NaOH treated PLA

  15. Dual-source dual-power electrospinning and characteristics of multifunctional scaffolds for bone tissue engineering.

    PubMed

    Wang, Chong; Wang, Min

    2012-10-01

    Electrospun tissue engineering scaffolds are attractive due to their distinctive advantages over other types of scaffolds. As both osteoinductivity and osteoconductivity play crucial roles in bone tissue engineering, scaffolds possessing both properties are desirable. In this investigation, novel bicomponent scaffolds were constructed via dual-source dual-power electrospinning (DSDPES). One scaffold component was emulsion electrospun poly(D,L-lactic acid) (PDLLA) nanofibers containing recombinant human bone morphogenetic protein (rhBMP-2), and the other scaffold component was electrospun calcium phosphate (Ca-P) particle/poly(lactic-co-glycolic acid) (PLGA) nanocomposite fibers. The mass ratio of rhBMP-2/PDLLA fibers to Ca-P/PLGA fibers in bicomponent scaffolds could be controlled in the DSDPES process by adjusting the number of syringes used to supply solutions for electrospinning. Through process optimization, both types of fibers could be evenly distributed in bicomponent scaffolds. The structure and properties of each type of fibers in the scaffolds were studied. The morphological and structural properties and wettability of scaffolds were assessed. The effects of emulsion composition for rhBMP-2/PDLLA fibers and mass ratio of fibrous components in bicomponent scaffolds on in vitro release of rhBMP-2 from scaffolds were investigated. In vitro degradation of scaffolds was also studied by monitoring their morphological changes, weight losses and decreases in average molecular weight of fiber matrix polymers.

  16. Estimation of the poly (ε-caprolactone) [PCL] and α-cyclodextrin [α-CD] stoichiometric ratios in their inclusion complexes [ICs], and evaluation of porosity and fiber alignment in PCL nanofibers containing these ICs.

    PubMed

    Narayanan, Ganesh; Gupta, Bhupender S; Tonelli, Alan E

    2015-12-01

    This paper describes the utilization of Proton-Nuclear Magnetic Resonance spectroscopy ((1)H NMR) to quantify the stoichiometric ratios between poly (ε-caprolactone) [PCL] and α-cyclodextrin (α-CD) present in their non-stoichiometric inclusion complexes [(n-s)-ICs]. This paper further describes the porosity and fiber alignment of PCL nanofibers nucleated by the [(n-s)-ICs] during electrospinning. (1)H NMR indicated that the two non-stoichiometric inclusion complexes utilized in this study had differing stoichiometric ratios that were closely similar to those of the starting ratios used to make them. Studies on porosity and fiber alignments were conducted on the scanning electron microscope images using ImageJ. The data indicates that both fiber alignment as well as porosity values remain almost the same over all the samples. Thus we can conclude the improvement in mechanical properties was due only to the loading of the ICs, and their subsequent interaction with bulk unthreaded PCL.

  17. Three-dimensional fiber-deposited PEOT/PBT copolymer scaffolds for tissue engineering: influence of porosity, molecular network mesh size, and swelling in aqueous media on dynamic mechanical properties.

    PubMed

    Moroni, L; de Wijn, J R; van Blitterswijk, C A

    2005-12-15

    Among novel scaffold fabrication techniques, 3D fiber deposition (3DF) has recently emerged as a means to fabricate well-defined and custom-made scaffolds for tissue regeneration, with 100% interconnected pores. The mechanical behavior of these constructs is dependent not only on different three-dimensional architectural and geometric features, but also on the intrinsic chemical properties of the material used. These affect the mechanics of the solid material and eventually of 3D porous constructs derived from them. For instance, poly(ethylene oxide terephthalate)-poly(butylene terephthalate) (PEOT/PBT) block copolymers are known to have mechanical properties, depending on the PEOT/PBT weight ratio in block form and on the molecular weight of the initial poly(ethylene glycol) (PEG) blocks. These differences are enhanced even more by their different swelling properties in aqueous media. Therefore, this article examines the influence of copolymer compositions in terms of their swelling on dynamic mechanical properties of solid material and porous 3DF scaffolds. The molecular weight of the starting PEG blocks used in the copolymer synthesis varied from 300 to 1000 g/mol. The PEOT/PBT weight ratio in the blocks used varied from 55/45 to 80/20. This corresponded to an increase of the swelling ratio Q from 1.06 to 2.46, and of the mesh size xi from approximately 9 Angstrom to approximately 47 Angstrom. With increased swelling, dynamic mechanical analysis (DMA) revealed a decrease in elastic response and an increase of viscoelasticity. Thus, by coupling structural and chemical characteristics, the viscoelastic properties of PEOT/PBT 3DF scaffolds may be fine tuned to achieve mechanical requirements for a variety of engineered tissues. Ultimately, the combination of 3DF and DMA may be useful to validate the hypothesis that mimicking the biomechanical behavior of a specific tissue for its optimal replacement is an important issue for at least some tissue

  18. Aligned Poly(ε-caprolactone) Nanofibers Guide the Orientation and Migration of Human Pluripotent Stem Cell-Derived Neurons, Astrocytes, and Oligodendrocyte Precursor Cells In Vitro.

    PubMed

    Hyysalo, Anu; Ristola, Mervi; Joki, Tiina; Honkanen, Mari; Vippola, Minnamari; Narkilahti, Susanna

    2017-03-15

    Stem cell transplantations for spinal cord injury (SCI) have been studied extensively for the past decade in order to replace the damaged tissue with human pluripotent stem cell (hPSC)-derived neural cells. Transplanted cells may, however, benefit from supporting and guiding structures or scaffolds in order to remain viable and integrate into the host tissue. Biomaterials can be used as supporting scaffolds, as they mimic the characteristics of the natural cellular environment. In this study, hPSC-derived neurons, astrocytes, and oligodendrocyte precursor cells (OPCs) are cultured on aligned poly(ε-caprolactone) nanofiber platforms, which guide cell orientation to resemble that of spinal cord in vivo. All cell types are shown to efficiently spread over the nanofiber platform and orient according to the fiber alignment. Human neurons and astrocytes require extracellular matrix molecule coating for the nanofibers, but OPCs grow on nanofibers without additional treatment. Furthermore, the nanofiber platform is combined with a 3D hydrogel scaffold with controlled thickness, and nanofiber-mediated orientation of hPSC-derived neurons is also demonstrated in a 3D environment. In this work, clinically relevant materials and substrates for nanofibers, fiber coatings, and hydrogel scaffolds are used and combined with cells suitable for developing functional cell grafts for SCI repair.

  19. Scaffolded biology.

    PubMed

    Minelli, Alessandro

    2016-09-01

    Descriptions and interpretations of the natural world are dominated by dichotomies such as organism vs. environment, nature vs. nurture, genetic vs. epigenetic, but in the last couple of decades strong dissatisfaction with those partitions has been repeatedly voiced and a number of alternative perspectives have been suggested, from perspectives such as Dawkins' extended phenotype, Turner's extended organism, Oyama's Developmental Systems Theory and Odling-Smee's niche construction theory. Last in time is the description of biological phenomena in terms of hybrids between an organism (scaffolded system) and a living or non-living scaffold, forming unit systems to study processes such as reproduction and development. As scaffold, eventually, we can define any resource used by the biological system, especially in development and reproduction, without incorporating it as happens in the case of resources fueling metabolism. Addressing biological systems as functionally scaffolded systems may help pointing to functional relationships that can impart temporal marking to the developmental process and thus explain its irreversibility; revisiting the boundary between development and metabolism and also regeneration phenomena, by suggesting a conceptual framework within which to investigate phenomena of regular hypermorphic regeneration such as characteristic of deer antlers; fixing a periodization of development in terms of the times at which a scaffolding relationship begins or is terminated; and promoting plant galls to legitimate study objects of developmental biology.

  20. Fiber optic coupled optical sensor

    DOEpatents

    Fleming, Kevin J.

    2001-01-01

    A displacement sensor includes a first optical fiber for radiating light to a target, and a second optical fiber for receiving light from the target. The end of the first fiber is adjacent and not axially aligned with the second fiber end. A lens focuses light from the first fiber onto the target and light from the target onto the second fiber.

  1. Characterization, mechanical behavior and in vitro evaluation of a melt-drawn scaffold for esophageal tissue engineering.

    PubMed

    Tan, Yu Jun; Yeong, Wai Yee; Tan, Xipeng; An, Jia; Chian, Kerm Sin; Leong, Kah Fai

    2016-04-01

    Tubular esophageal scaffolds with fiber diameter ranging from 13.9±1.7μm to 65.7±6.2μm were fabricated from the highly elastic poly(l-lactide-co-ε-caprolactone) (PLC) via a melt-drawing method. The morphology, crystallinity, thermal and mechanical properties of the PLC fibers were investigated. They were highly aligned and have a uniform diameter. PLC is found to be semicrystalline consisting of α- and β- lactide (LA) crystals. The crystallinity increases up to 16.8% with increasing melt-drawing speeds due to strain-induced crystallization. Modulus and strength increases while ductility decreases with an increase in crystallinity of the PLC samples. Moisture will not degrade the overall tensile properties but affect its tangent modulus at the low strain. L929 cells are able to attach and proliferate on the scaffolds very well. The cells seeded on the scaffolds show normal morphology with >90% cell viability after 6 days of culture. These results demonstrate that the PLC fibrous scaffold has good potential for use in esophageal tissue engineering application.

  2. Further Development of Scaffolds for Regeneration of Nerves

    NASA Technical Reports Server (NTRS)

    Sakamoto, Jeffrey; Tuszynski, Mark

    2009-01-01

    Progress has been made in continuing research on scaffolds for the guided growth of nerves to replace damaged ones. The scaffolds contain pores that are approximately cylindrical and parallel, with nearly uniform widths ranging from tens to hundreds of microns. At the earlier stage of development, experimental scaffolds had been made from agarose hydrogel. Such a scaffold was made in a multistep process in which poly(methyl methacrylate) [PMMA] fibers were used as templates for the pores. The process included placement of a bundle of the PMMA fibers in a tube, filling the interstices in the tube with a hot agarose solution, cooling to turn the solution into a gel, and then immersion in acetone to dissolve the PMMA fibers. The scaffolds were typically limited to about 25 pores per scaffold, square cross sections of no more than about 1.5 by 1.5 mm, and lengths of no more than about 2 mm.

  3. Pore orientation mediated control of mechanical behavior of scaffolds and its application in cartilage-mimetic scaffold design.

    PubMed

    Arora, Aditya; Kothari, Anjaney; Katti, Dhirendra S

    2015-11-01

    Scaffolds with aligned pores are being explored in musculoskeletal tissue engineering due to their inherent structural anisotropy. However, influence of their structure on mechanical behavior remains poorly understood. In this work, we elucidate this dependence using chitosan-gelatin based random and aligned scaffolds. For this, scaffolds with horizontally or vertically aligned pores were fabricated using unidirectional freezing technique. Random, horizontal and vertical scaffolds were characterized for their mechanical behavior under compressive, tensile and shear loading regimes. The results revealed conserved trends in compressive, tensile and shear moduli, with horizontal scaffolds showing the least moduli, vertical showing the highest and random showing intermediate. Further, these scaffolds demonstrated a highly viscoelastic behavior under cyclic compressive loading, with a pore orientation dependent relative energy dissipation. These results established that mechanical behavior of porous scaffolds can be modulated by varying pore orientation alone. This finding paved the way to recreate the structural and consequent mechanical anisotropy of articular cartilage tissue using zonally varied pore orientation in scaffolds. To this end, monolithic multizonal scaffolds were fabricated using a novel sequential unidirectional freezing technique. The superficial zone of this scaffold had horizontally aligned pores while the deep zone consisted of vertically aligned pores, with a transition zone between the two having randomly oriented pores. This depth-dependent pore architecture closely mimicked the collagen alignment of native articular cartilage which translated into similar depth-dependent mechanical anisotropy as well. A facile fabrication technique, biomimetic pore architecture and associated mechanical anisotropy make this multizonal scaffold a promising candidate for cartilage tissue engineering.

  4. The effects of PHBV electrospun fibers with different diameters and orientations on growth behavior of bone-marrow-derived mesenchymal stem cells.

    PubMed

    Lü, Lan-Xin; Wang, Yan-Yan; Mao, Xi; Xiao, Zhong-Dang; Huang, Ning-Ping

    2012-02-01

    Microenvironments in which cells live play an important role in the attachment, growth and interactions of cells. To mimic the natural structure of extracellular matrices, electrospinning was applied to fabricate biomaterials into ultrafine fibers. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a biocompatible and biodegradable polyester, has been shown to be an excellent biomaterial candidate for tissue engineering. In this study, five types of PHBV fibrous scaffolds with different diameters and orientations were obtained by changing solvents, concentration of electrospun solution and collector. Three kinds of scaffolds with good continuity and suitable mechanical properties, selected according to the morphology and mechanical properties of the scaffolds, were used for studying the influence of fiber diameter and orientation on growth behavior of bone-marrow-derived mesenchymal stem cells (MSCs). The results indicated that the random-oriented nanofibrous scaffold is most favorable for cell growth compared to other scaffolds, while the microfibrous scaffold resulted in the lowest viability of MSCs. The orientation of nanofibers showed a distinct effect on cell morphology by guiding cell skeleton extension. Both the random-oriented and aligned PHBV nanofibrous scaffolds showed to be good candidates for applications in tissue engineering.

  5. Salicylic acid-derived poly(anhydride-ester) electrospun fibers designed for regenerating the peripheral nervous system

    PubMed Central

    Griffin, Jeremy; Delgado-Rivera, Roberto; Meiners, Sally; Uhrich, Kathryn E.

    2011-01-01

    Continuous biomaterial advances and the regenerating potential of the adult human peripheral nervous system offer great promise for restoring full function to innervated tissue following traumatic injury via synthetic nerve guidance conduits. To most effectively facilitate nerve regeneration, a tissue engineering scaffold within a conduit must be similar to the linear microenvironment of the healthy nerve. To mimic the native nerve structure, aligned poly(lactic-co-glycolic acid)/bioactive polyanhydride fibrous substrates were fabricated through optimized electrospinning parameters with diameters of 600 ± 200 nm. Scanning electron microscopy images show fibers with a high degree of alignment. Schwann cells and dissociated rat dorsal root ganglia demonstrated elongated and healthy proliferation in a direction parallel to orientated electrospun fibers with significantly longer Schwann cell process length and neurite outgrowth when compared to randomly orientated fibers. Results suggest that an aligned polyanhydride fiber mat holds tremendous promise as a supplement scaffold for the interior of a degradable polymer nerve guidance conduit. Bioactive salicylic acid based polyanhydride fibers are not limited to nerve regeneration and offer exciting promise for a wide variety of biomedical applications. PMID:21442724

  6. Topographical effects on fiber-mediated microRNA delivery to control oligodendroglial precursor cells development.

    PubMed

    Diao, Hua Jia; Low, Wei Ching; Lu, Q Richard; Chew, Sing Yian

    2015-11-01

    Effective remyelination in the central nervous system (CNS) facilitates the reversal of disability in patients with demyelinating diseases such as multiple sclerosis. Unfortunately until now, effective strategies of controlling oligodendrocyte (OL) differentiation and maturation remain limited. It is well known that topographical and biochemical signals play crucial roles in modulating cell fate commitment. Therefore, in this study, we explored the combined effects of scaffold topography and sustained gene silencing on oligodendroglial precursor cell (OPC) development. Specifically, microRNAs (miRs) were incorporated onto electrospun polycaprolactone (PCL) fiber scaffolds with different fiber diameters and orientations. Regardless of fiber diameter and orientation, efficient knockdown of differentiation inhibitory factors were achieved by either topography alone (up to 70%) or fibers integrated with miR-219 and miR-338 (up to 80%, p < 0.05). Small fiber promoted OPC differentiation by inducing more RIP(+) cells (p < 0.05) while large fiber promoted OL maturation by inducing more MBP(+) cells (p < 0.05). Random fiber enhanced more RIP(+) cells than aligned fibers (p < 0.05), regardless of fiber diameter. Upon miR-219/miR-338 incorporation, 2 μm aligned fibers supported the most MBP(+) cells (∼17%). These findings indicated that the coupling of substrate topographic cues with efficient gene silencing by sustained microRNA delivery is a promising way for directing OPC maturation in neural tissue engineering and controlling remyelination in the CNS.

  7. The effect of PVDF-TrFE scaffolds on stem cell derived cardiovascular cells.

    PubMed

    Hitscherich, Pamela; Wu, Siliang; Gordan, Richard; Xie, Lai-Hua; Arinzeh, Treena; Lee, Eun Jung

    2016-07-01

    Recently, electrospun polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) scaffolds have been developed for tissue engineering applications. These materials have piezoelectric activity, wherein they can generate electric charge with minute mechanical deformations. Since the myocardium is an electroactive tissue, the unique feature of a piezoelectric scaffold is attractive for cardiovascular tissue engineering applications. In this study, we examined the cytocompatibility and function of pluripotent stem cell derived cardiovascular cells including mouse embryonic stem cell-derived cardiomyocytes (mES-CM) and endothelial cells (mES-EC) on PVDF-TrFE scaffolds. MES-CM and mES-EC adhered well to PVDF-TrFE and became highly aligned along the fibers. When cultured on scaffolds, mES-CM spontaneously contracted, exhibited well-registered sarcomeres and expressed classic cardiac specific markers such as myosin heavy chain, cardiac troponin T, and connexin43. Moreover, mES-CM cultured on PVDF-TrFE scaffolds responded to exogenous electrical pacing and exhibited intracellular calcium handling behavior similar to that of mES-CM cultured in 2D. Similar to cardiomyocytes, mES-EC also demonstrated high viability and maintained a mature phenotype through uptake of low-density lipoprotein and expression of classic endothelial cell markers including platelet endothelial cell adhesion molecule, endothelial nitric oxide synthase, and the arterial specific marker, Notch-1. This study demonstrates the feasibility of PVDF-TrFE scaffold as a candidate material for developing engineered cardiovascular tissues utilizing stem cell-derived cells. Biotechnol. Bioeng. 2016;113: 1577-1585. © 2015 Wiley Periodicals, Inc.

  8. Tensile mechanical properties and hydraulic permeabilities of electrospun cellulose acetate fiber meshes.

    PubMed

    Stylianopoulos, Triantafyllos; Kokonou, Maria; Michael, Stefanos; Tryfonos, Antonia; Rebholz, Claus; Odysseos, Andreani D; Doumanidis, Charalambos

    2012-11-01

    The mechanical properties and hydraulic permeabilities of biomaterial scaffolds play a crucial role in their efficacy as tissue engineering platforms, separation processors, and drug delivery vehicles. In this study, electrospun cellulose acetate fiber meshes of random orientations were created using four different concentrations, 10.0, 12.5, 15.0, and 17.5 wt % in acetone or ethyl acetate. The tensile mechanical properties and the hydraulic permeabilities of these meshes were measured, and a multiscale model was employed to predict their mechanical behavior. Experimentally, the elastic modulus ranged from 3.5 to 12.4 MPa depending on the polymer concentration and the solvent. Model predictions agreed well with the experimental measurements when a fitted single-fiber modulus of 123.3 MPa was used. The model also predicted that changes in fiber alignment may result in a 3.6-fold increase in the elastic modulus for moderately aligned meshes and a 8.5-fold increase for highly align meshes. Hydraulic permeabilities ranged from 1.4 x 10(-12) to 8.9 x 10(-12) m(2) depending on polymer concentration but not the choice of solvent. In conclusion, polymer concentration, fiber alignment, and solvent have significant impact on the mechanical and fluid transport properties of electrospun cellulose acetate fiber meshes.

  9. Axially aligned 3D nanofibrous grafts of PLA-PCL for small diameter cardiovascular applications.

    PubMed

    Sankaran, Krishna Kumar; Krishnan, Uma Maheswari; Sethuraman, Swaminathan

    2014-01-01

    Axially aligned nanofibrous matrices were evaluated as small diameter cardiovascular grafts. Grafts were prepared using the poly(L-lactic acid) (PLA) and poly(ε-caprolactone) (PCL) physical blends in the ratios of 75:25 and 25:75 with the dimension of (40 × 0.2 × 4) millimeter by electrospinning using dynamic collector (1500 RPM). Hydrophobicity and tensile stress were significantly higher in PLA-PCL (75:25), whereas tensile strain and fiber density were significantly higher in PLA-PCL (25:75). Properties such as anastomatic strength porosity, average pore size, degradation with retained fiber orientation, and thromboresistivity were comparable between blends. Human umbilical vascular endothelial cells (HUVEC) adhesion on the scaffolds was observed within 24 h. Cell viability and proliferation were rationally influenced by the aligned nanofibers. Gene expression reveals the grafts thromboresistivity, elasticity, and aided neovascularization. Thus, these scaffolds could be an ideal candidate for small diameter blood vessel engineering.

  10. Enhanced GLT-1 mediated glutamate uptake and migration of primary astrocytes directed by fibronectin-coated electrospun poly-L-lactic acid fibers.

    PubMed

    Zuidema, Jonathan M; Hyzinski-García, María C; Van Vlasselaer, Kristien; Zaccor, Nicholas W; Plopper, George E; Mongin, Alexander A; Gilbert, Ryan J

    2014-02-01

    Bioengineered fiber substrates are increasingly studied as a means to promote regeneration and remodeling in the injured central nervous system (CNS). Previous reports largely focused on the ability of oriented scaffolds to bridge injured regions and direct outgrowth of axonal projections. In the present work, we explored the effects of electrospun microfibers on the migration and physiological properties of brain astroglial cells. Primary rat astrocytes were cultured on either fibronectin-coated poly-L-lactic acid (PLLA) films, fibronectin-coated randomly oriented PLLA electrospun fibers, or fibronectin-coated aligned PLLA electrospun fibers. Aligned PLLA fibers strongly altered astrocytic morphology, orienting cell processes, actin microfilaments, and microtubules along the length of the fibers. On aligned fibers, astrocytes also significantly increased their migration rates in the direction of fiber orientation. We further investigated if fiber topography modifies astrocytic neuroprotective properties, namely glutamate and glutamine transport and metabolism. This was done by quantifying changes in mRNA expression (qRT-PCR) and protein levels (Western blotting) for a battery of relevant biomolecules. Interestingly, we found that cells grown on random and/or aligned fibers increased the expression levels of two glutamate transporters, GLAST and GLT-1, and an important metabolic enzyme, glutamine synthetase, as compared to the fibronectin-coated films. Functional assays revealed increases in glutamate transport rates due to GLT-1 mediated uptake, which was largely determined by the dihydrokainate-sensitive GLT-1. Overall, this study suggests that aligned PLLA fibers can promote directed astrocytic migration, and, of most importance, our in vitro results indicate for the first time that electrospun PLLA fibers can positively modify neuroprotective properties of glial cells by increasing rates of glutamate uptake.

  11. Biocompatibility and degradation of tendon-derived scaffolds

    PubMed Central

    Alberti, Kyle A.; Xu, Qiaobing

    2016-01-01

    Decellularized extracellular matrix has often been used as a biomaterial for tissue engineering applications. Its function, once implanted can be crucial to determining whether a tissue engineered construct will be successful, both in terms of how the material breaks down, and how the body reacts to the material’s presence in the first place. Collagen is one of the primary components of extracellular matrix and has been used for a number of biomedical applications. Scaffolds comprised of highly aligned collagen fibrils can be fabricated directly from decellularized tendon using a slicing, stacking, and rolling technique, to create two- and three-dimensional constructs. Here, the degradation characteristics of the material are evaluated in vitro, showing that chemical crosslinking can reduce degradation while maintaining fiber structure. In vivo, non-crosslinked and crosslinked samples are implanted, and their biological response and degradation evaluated through histological sectioning, trichrome staining, and immunohistochemical staining for macrophages. Non-crosslinked samples are rapidly degraded and lose fiber morphology while crosslinked samples retain both macroscopic structure as well as fiber orientation. The cellular response of both materials is also investigated. The in vivo response demonstrates that the decellularized tendon material is biocompatible, biodegradable and can be crosslinked to maintain surface features for extended periods of time in vivo. This study provides material characteristics for the use of decellularized tendon as biomaterial for tissue engineering. PMID:26816651

  12. Regulation of electrospun scaffold stiffness via coaxial core diameter.

    PubMed

    Drexler, J W; Powell, H M

    2011-03-01

    Scaffold mechanics influence cellular behavior, including migration, phenotype and viability. Scaffold stiffness is commonly modulated through cross-linking, polymer density, or bioactive coatings on stiff substrates. These approaches provide useful information about cellular response to substrate stiffness; however, they are not ideal as the processing can change substrate morphology, density or chemistry. Coaxial electrospinning was investigated as a fabrication method to produce scaffolds with tunable stiffness and strength without changing architecture or surface chemistry. Core solution concentration, solvent and feed rate were utilized to control core diameter with higher solution concentration and feed rate positively correlating with increased fiber diameter and stiffness. Coaxial scaffolds electrospun with an 8 wt./vol.% polycaprolactone (PCL)-HFP solution at 1 ml h(-1) formed scaffolds with an average core diameter of 1.1±0.2 μm and stiffness of 0.027±3.3×10(-3) N mm(-1). In contrast, fibers which were 2.6±0.1 μm in core diameter yielded scaffolds with a stiffness of 0.065±4.7×10(-3) N mm(-1). Strength and stiffness positively correlated with core diameter with no significant difference in total fiber diameter and interfiber distance observed in as-spun scaffolds. These data indicate that coaxial core diameter can be utilized to tailor mechanical properties of three-dimensional scaffolds and would provide an ideal scaffold for assessing the effect of scaffold mechanics on cell behavior.

  13. Electrospun polyurethane nanofiber scaffolds with ciprofloxacin oligomer versus free ciprofloxacin: Effect on drug release and cell attachment.

    PubMed

    Wright, Meghan Ee; Parrag, Ian C; Yang, Meilin; Santerre, J Paul

    2017-02-10

    An electrospun degradable polycarbonate urethane (PCNU) nanofiber scaffold loaded with antibiotic was investigated in terms of antibacterial efficacy and cell compatibility for potential use in gingival tissue engineering. Antimicrobial oligomer (AO), a compound which consists of two molecules of ciprofloxacin (CF) covalently bound via hydrolysable linkages to triethylene glycol (TEG), was incorporated via a one-step blend electrospinning process using a single solvent system at 7 and 15% w/w equivalent CF with respect to the PCNU. The oligomeric form of the drug was used to overcome the challenge of drug aggregation and burst release when antibiotics are incorporated as free drug. Electrospinning parameters were optimized to obtain scaffolds with similar alignment and fiber diameter to non-drug loaded fibers. AO that diffused from the fibers was hydrolysed to release CF slowly and in a linear manner over the duration of the study, whereas scaffolds with CF at the same concentration but in free form showed a burst release within 1h with no further release throughout the study duration. Human gingival fibroblast (HGF) adhesion and spreading was dependent on the concentration and form the CF was loaded (AO vs. free CF), which was attributed in part to differences in scaffold surface chemistry. Surface segregation of AO was quantified using surface-resolved X-ray photoelectron spectroscopy (XPS). These findings are encouraging and support further investigation for the use of AO as a means of attenuating the rapid release of drug loaded into nanofibers. The study also demonstrates through quantitative measures that drug additives have the potential to surface-locate without phase separating from the fibers, leading to fast dissolution and differential fibroblast cell attachment.

  14. Silk scaffolds for musculoskeletal tissue engineering

    PubMed Central

    Yao, Danyu

    2015-01-01

    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. 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.

  16. Alignment validation

    SciTech Connect

    ALICE; ATLAS; CMS; LHCb; Golling, Tobias

    2008-09-06

    The four experiments, ALICE, ATLAS, CMS and LHCb are currently under constructionat CERN. They will study the products of proton-proton collisions at the Large Hadron Collider. All experiments are equipped with sophisticated tracking systems, unprecedented in size and complexity. Full exploitation of both the inner detector andthe muon system requires an accurate alignment of all detector elements. Alignmentinformation is deduced from dedicated hardware alignment systems and the reconstruction of charged particles. However, the system is degenerate which means the data is insufficient to constrain all alignment degrees of freedom, so the techniques are prone to converging on wrong geometries. This deficiency necessitates validation and monitoring of the alignment. An exhaustive discussion of means to validate is subject to this document, including examples and plans from all four LHC experiments, as well as other high energy experiments.

  17. Aligned Nanofibers for Regenerating Arteries, Nerves, and Muscles

    NASA Astrophysics Data System (ADS)

    McClendon, Mark Trosper

    Cells are the fundamental unit of the human body, and therefore the ability to control cell behavior is the most important challenge in regenerative medicine. Peptides are the language of biology which is why synthetic peptide amphiphile (PA) molecules hold great potential as a biomaterial. The work presented in this dissertation explores a variety of liquid crystalline PA nanofibers as a means for directing cell growth. Shaping the alignment of these nanofiber networks requires a deep understanding of their rheological properties which presents a difficult challenge as they exist in complex solid and liquid environments. Using PA molecules that self-assemble into high aspect ratio nanofibers and liquid crystalline solutions, this work investigates the influence of shear flow on macroscopic and microscopic nanofiber alignment. To this end, a shear force applied to PA solutions was systematically varied while the alignment was probed using small angle x-ray scattering. Nanofibers were found to respond to shear flow by aligning parallel to the flow direction. By changing pH and PA chemical sequence it was observed that increasing the interfiber electrostatic repulsive interactions resulted in a greater dependence on shear rate. Nanofiber solutions having greater repulsion did not drastically increase in alignment when the applied strain was increased by two orders of magnitude (1 s -1 to 100 s-1), while solutions with nanofibers having less repulsion increased there alignment four fold with the same strain increase. say exactly what you mean by resulted in greater dependence: did it result in fibers aligning under lower shear rates or higher rates--give the results Anionic PA solutions typically used to encapsulate living cells at neutral pH were found to require minimal shear rates, <1s-1, to achieve significant nanofiber alignment. In an effort to produce tubular hydrogels composed of circumferentially aligned nanofibers, a procedure was designed that used an

  18. Electrospun meshes possessing region-wise differences in fiber orientation, diameter, chemistry and mechanical properties for engineering bone-ligament-bone tissues.

    PubMed

    Samavedi, Satyavrata; Vaidya, Prasad; Gaddam, Prudhvidhar; Whittington, Abby R; Goldstein, Aaron S

    2014-12-01

    Although bone-patellar tendon-bone (B-PT-B) autografts are the gold standard for repair of anterior cruciate ligament ruptures, they suffer from drawbacks such as donor site morbidity and limited supply. Engineered tissues modeled after B-PT-B autografts are promising alternatives because they have the potential to regenerate connective tissue and facilitate osseointegration. Towards the long-term goal of regenerating ligaments and their bony insertions, the objective of this study was to construct 2D meshes and 3D cylindrical composite scaffolds - possessing simultaneous region-wise differences in fiber orientation, diameter, chemistry and mechanical properties - by electrospinning two different polymers from off-set spinnerets. Using a dual drum collector, 2D meshes consisting of an aligned polycaprolactone (PCL) fiber region, randomly oriented poly(lactide-co-glycolide) (PLGA) fiber region and a transition region (comprised of both PCL and PLGA fibers) were prepared, and region-wise differences were confirmed by microscopy and tensile testing. Bone marrow stromal cells (BMSCs) cultured on these meshes exhibited random orientations and low aspect ratios on the random PLGA regions, and high aspect ratios and alignment on the aligned PCL regions. Next, meshes containing an aligned PCL region flanked by two transition regions and two randomly oriented PLGA regions were prepared and processed into 3D cylindrical composite scaffolds using an interpenetrating photo-crosslinkable polyethylene glycol diacrylate hydrogel to recapitulate the shape of B-PT-B autografts. Tensile testing indicated that cylindrical composites were mechanically robust, and eventually failed due to stress concentration in the aligned PCL region. In summary, this study demonstrates a process to fabricate electrospun meshes possessing region-wise differences in properties that can elicit region-dependent cell responses, and be readily processed into scaffolds with the shape of B-PT-B autografts.

  19. Modeling tissue growth within nonwoven scaffolds pores.

    PubMed

    Edwards, Sharon L; Church, Jeffrey S; Alexander, David L J; Russell, Stephen J; Ingham, Eileen; Ramshaw, John A M; Werkmeister, Jerome A

    2011-02-01

    In this study we present a novel approach for predicting tissue growth within the pores of fibrous tissue engineering scaffolds. Thin nonwoven polyethylene terephthalate scaffolds were prepared to characterize tissue growth within scaffold pores, by mouse NR6 fibroblast cells. On the basis of measurements of tissue lengths at fiber crossovers and along fiber segments, mathematical models were determined during the proliferative phase of cell growth. Tissue growth at fiber crossovers decreased with increasing interfiber angle, with exponential relationships determined on day 6 and 10 of culture. Analysis of tissue growth along fiber segments determined two growth profiles, one with enhanced growth as a result of increased tissue lengths near the fiber crossover, achieved in the latter stage of culture. Derived mathematical models were used in the development of a software program to visualize predicted tissue growth within a pore. This study identifies key pore parameters that contribute toward tissue growth, and suggests models for predicting this growth, based on fibroblast cells. Such models may be used in aiding scaffold design, for optimum pore infiltration during the tissue engineering process.

  20. Optical fiber stripper positioning apparatus

    DOEpatents

    Fyfe, Richard W.; Sanchez, Jr., Amadeo

    1990-01-01

    An optical fiber positioning apparatus for an optical fiber stripping device is disclosed which is capable of providing precise axial alignment between an optical fiber to be stripped of its outer jacket and the cutting blades of a stripping device. The apparatus includes a first bore having a width approximately equal to the diameter of an unstripped optical fiber and a counter bore axially aligned with the first bore and dimensioned to precisely receive a portion of the stripping device in axial alignment with notched cutting blades within the stripping device to thereby axially align the notched cutting blades of the stripping device with the axis of the optical fiber to permit the notched cutting blades to sever the jacket on the optical fiber without damaging the cladding on the optical fiber. In a preferred embodiment, the apparatus further includes a fiber stop which permits determination of the length of jacket to be removed from the optical fiber.

  1. Fabrication of polymeric scaffolds with a controlled distribution of pores.

    PubMed

    Capes, J S; Ando, H Y; Cameron, R E

    2005-12-01

    The design of tissue engineering scaffolds must take into account many factors including successful vascularisation and the growth of cells. Research has looked at refining scaffold architecture to promote more directed growth of tissues through well-defined anisotropy in the pore structure. In many cases it is also desirable to incorporate therapeutic ingredients, such as growth factors, into the scaffold so that their release occurs as the scaffold degrades. Therefore, scaffold fabrication techniques must be found to precisely control, not only the overall porosity of scaffolds, but also the pore size, shape and spatial distribution. This work describes the use of a regularly shaped porogen, sugar spheres, to manufacture polymeric scaffolds. Results show that pre-assembling the spheres created scaffolds with a constant porosity of 60%, but with varying pores sizes from 200-800 microm, leading to a variation in the surface area and likely degradation rate of the scaffolds. Employing different polymer impregnation techniques tailored the number of pores present with a diameter of less than 100 microm to suit different functions, and altering the packing structure of the sugar spheres created scaffolds with novel layered porosity. Replacing sugar spheres with sugar strands formed scaffolds with pores aligned in one direction.

  2. Bone regeneration and infiltration of an anisotropic composite scaffold: an experimental study of rabbit cranial defect repair.

    PubMed

    Li, Jidong; You, Fu; Li, Yubao; Zuo, Yi; Li, Limei; Jiang, Jiaxing; Qu, Yili; Lu, Minpeng; Man, Yi; Zou, Qin

    2016-01-01

    Tissue formation on scaffold outer edges after implantation may restrict cell infiltration and mass transfer to/from the scaffold center due to insufficient interconnectivity, leading to incidence of a necrotic core. Herein, a nano-hydroxyapatite/polyamide66 (n-HA/PA66) anisotropic scaffold with axially aligned channels was prepared with the aim to enhance pore interconnectivity. Bone tissue regeneration and infiltration inside of scaffold were assessed by rabbit cranial defect repair experiments. The amount of newly formed bone inside of anisotropic scaffold was much higher than isotropic scaffold, e.g., after 12 weeks, the new bone volume in the inner pores was greater in the anisotropic scaffolds (>50%) than the isotropic scaffolds (<30%). The results suggested that anisotropic scaffolds could accelerate the inducement of bone ingrowth into the inner pores in the non-load-bearing bone defects compared to isotropic scaffolds. Thus, anisotropic scaffolds hold promise for the application in bone tissue engineering.

  3. Synergistic effect of topography, surface chemistry and conductivity of the electrospun nanofibrous scaffold on cellular response of PC12 cells.

    PubMed

    Tian, Lingling; Prabhakaran, Molamma P; Hu, Jue; Chen, Menglin; Besenbacher, Flemming; Ramakrishna, Seeram

    2016-09-01

    Electrospun nanofibrous nerve implants is a promising therapy for peripheral nerve injury, and its performance can be tailored by chemical cues, topographical features as well as electrical properties. In this paper, a surface modified, electrically conductive, aligned nanofibrous scaffold composed of poly (lactic acid) (PLA) and polypyrrole (Ppy), referred to as o-PLAPpy_A, was fabricated for nerve regeneration. The morphology, surface chemistry and hydrophilicity of nanofibers were characterized by Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and water contact angle, respectively. The effects of these nanofibers on neuronal differentiation using PC12 cells were evaluated. A hydrophilic surface was created by Poly-ornithine coating, which was able to provide a better environment for cell attachment, and furthermore aligned fibers were proved to be able to guide PC12 cells grow along the fiber direction and be beneficial for neurite outgrowth. The cellular response of PC12 cells to pulsed electrical stimulation was evaluated by NF 200 and alpha tubulin expression, indicating that electrical stimulation with a voltage of 40mV could enhance the neurite outgrowth. The PC12 cells stimulated with electrical shock showed greater level of neurite outgrowth and smaller cell body size. Moreover, the PC12 cells under electrical stimulation showed better viability. In summary, the o-PLAPpy_A nanofibrous scaffold supported the attachment, proliferation and differentiation of PC12 cells in the absence of electrical stimulation, which could be potential candidate for nerve regeneration applications.

  4. Activated Schwann Cell-Like Cells on Aligned Fibrin-Poly(Lactic-Co-Glycolic Acid) Structures: A Novel Construct for Application in Peripheral Nerve Regeneration.

    PubMed

    Schuh, Christina M A P; Morton, Tatjana J; Banerjee, Asmita; Grasl, Christian; Schima, Heinrich; Schmidhammer, Robert; Redl, Heinz; Ruenzler, Dominik

    2015-01-01

    Tissue engineering approaches in nerve regeneration search for ways to support gold standard therapy (autologous nerve grafts) and to improve results by bridging nerve defects with different kinds of conduits. In this study, we describe electrospinning of aligned fibrin-poly(lactic-co-glycolic acid) (PLGA) fibers in an attempt to create a biomimicking tissue-like material seeded with Schwann cell-like cells (SCLs) in vitro for potential use as an in vivo scaffold. Rat adipose-derived stem cells (rASCs) were differentiated into SCLs and evaluated with flow cytometry concerning their differentiation and activation status [S100b, P75, myelin-associated glycoprotein (MAG), and protein 0 (P0)]. After receiving the proliferation stimulus forskolin, SCLs expressed S100b and P75; comparable to native, activated Schwann cells, while cultured without forskolin, cells switched to a promyelinating phenotype and expressed S100b, MAG, and P0. Human fibrinogen and thrombin, blended with PLGA, were electrospun and the alignment and homogeneity of the fibers were proven by scanning electron microscopy. Electrospun scaffolds were seeded with SCLs and the formation of Büngner-like structures in SCLs was evaluated with phalloidin/propidium iodide staining. Carrier fibrin gels containing rASCs acted as a self-shaping matrix to form a tubular structure. In this study, we could show that rASCs can be differentiated into activated, proliferating SCLs and that these cells react to minimal changes in stimulus, switching to a promyelinating phenotype. Aligned electrospun fibrin-PLGA fibers promoted the formation of Büngner-like structures in SCLs, which also rolled the fibrin-PLGA matrix into a tubular scaffold. These in vitro findings favor further in vivo testing.

  5. Strategies for regeneration of components of nervous system: scaffolds, cells and biomolecules

    PubMed Central

    Tian, Lingling; Prabhakaran, Molamma P.; Ramakrishna, Seeram

    2015-01-01

    Nerve diseases including acute injury such as peripheral nerve injury (PNI), spinal cord injury (SCI) and traumatic brain injury (TBI), and chronic disease like neurodegeneration disease can cause various function disorders of nervous system, such as those relating to memory and voluntary movement. These nerve diseases produce great burden for individual families and the society, for which a lot of efforts have been made. Axonal pathways represent a unidirectional and aligned architecture allowing systematic axonal development within the tissue. Following a traumatic injury, the intricate architecture suffers disruption leading to inhibition of growth and loss of guidance. Due to limited capacity of the body to regenerate axonal pathways, it is desirable to have biomimetic approach that has the capacity to graft a bridge across the lesion while providing optimal mechanical and biochemical cues for tissue regeneration. And for central nervous system injury, one more extra precondition is compulsory: creating a less inhibitory surrounding for axonal growth. Electrospinning is a cost-effective and straightforward technique to fabricate extracellular matrix (ECM)-like nanofibrous structures, with various fibrous forms such as random fibers, aligned fibers, 3D fibrous scaffold and core-shell fibers from a variety of polymers. The diversity and versatility of electrospinning technique, together with functionalizing cues such as neurotrophins, ECM-based proteins and conductive polymers, have gained considerable success for the nerve tissue applications. We are convinced that in the future the stem cell therapy with the support of functionalized electrospun nerve scaffolds could be a promising therapy to cure nerve diseases. PMID:26813399

  6. The Effect of Pulsatile Loading and Scaffold Structure for the Generation of a Medial Equivalent Tissue Engineered Vascular Graft

    PubMed Central

    Thomas, Lynda V.

    2013-01-01

    Abstract A reliable and cost-effective scaffold for tissue-engineered vascular graft that would not only support cell proliferation and growth but also maintain cell phenotype has been a long-term challenge. In this study, we propose a biodegradable and biomimetic copolymer of gelatin with vinyl acetate synthesized via a graft copolymerization technique to generate tubular scaffolds for vascular tissue engineering. Two fabrication techniques, freeze drying and electrospinning, were used to generate the differing architectures for the scaffolds and characterized. The electrospun scaffolds were found to have a faster rate of mass loss in physiological saline of 81.72% within 4 months compared with 60% mass loss for the freeze-dried samples, though the materials were more crystalline. Vascular (v) smooth muscle cells (SMCs) were seeded on these tubes, which were then subjected to dynamic pulsatile stimulation on a vascular bioreactor for a week. Gross examination of the tissue-engineered constructs revealed that the cells secreted extensive extracellular matrix, with the dynamically conditioned samples exhibiting well-orientated SMCs and collagenous fibers in comparison with growth in static conditions. In addition, the alignment of cells in the direction of strain was greater in the electrospun constructs. The electrospun scaffolds maintained the characteristic contractile phenotype of SMCs, which was confirmed by higher gene expression rates of contractile protein markers like SM22α and calponin. A significant increase in the total matrix components (collagen and elastin) in the electrospun constructs compared with the freeze-dried samples was confirmed by biochemical analysis. The results of this study indicate that a combination approach involving a biomimetic scaffold with the nanofibrillar architecture and good mechanical strength conducive to the growth of SMCs and the use of the pulsatile forces to modulate the cell morphology and phenotypic plasticity of v

  7. Influence of electrospun scaffolds prepared from distinct polymers on proliferation and viability of endothelial cells

    NASA Astrophysics Data System (ADS)

    Matveeva, V. G.; Antonova, L. V.; Velikanova, E. A.; Sergeeva, E. A.; Krivkina, E. O.; Glushkova, T. V.; Kudryavtseva, Yu. A.; Barbarash, O. L.; Barbarash, L. S.

    2015-10-01

    We compared electrospun nonwoven scaffolds from polylactic acid (PLA), polycaprolactone (PCL), and polyhydroxybutyrate/valerate (PHBV)/polycaprolactone (PHBV/PCL). The surface of PHBV/PCL and PCL scaffolds was highly porous and consisted of randomly distributed fibers, whilst the surface of PLA scaffolds consisted of thin straight fibers, which located more sparsely, forming large pores. Culture of EA.hy 926 endothelial cells on these scaffolds during 7 days and further fluorescent microscopy demonstrated that the surface of PHBV/PCL scaffolds was most favorable for efficient adhesion, proliferation, and viability of endothelial cells. The lowest proliferation rate and cell viability were detected on PLA scaffolds. Therefore, PHBV/PCL electrospun nonwoven scaffolds demonstrated the best results regarding endothelial cell proliferation and viability as compared to PCL and PLA scaffolds.

  8. Influence of electrospun scaffolds prepared from distinct polymers on proliferation and viability of endothelial cells

    SciTech Connect

    Matveeva, V. G. Antonova, L. V. Velikanova, E. A.; Sergeeva, E. A.; Krivkina, E. O.; Glushkova, T. V.; Kudryavtseva, Yu. A.; Barbarash, O. L.; Barbarash, L. S.

    2015-10-27

    We compared electrospun nonwoven scaffolds from polylactic acid (PLA), polycaprolactone (PCL), and polyhydroxybutyrate/valerate (PHBV)/polycaprolactone (PHBV/PCL). The surface of PHBV/PCL and PCL scaffolds was highly porous and consisted of randomly distributed fibers, whilst the surface of PLA scaffolds consisted of thin straight fibers, which located more sparsely, forming large pores. Culture of EA.hy 926 endothelial cells on these scaffolds during 7 days and further fluorescent microscopy demonstrated that the surface of PHBV/PCL scaffolds was most favorable for efficient adhesion, proliferation, and viability of endothelial cells. The lowest proliferation rate and cell viability were detected on PLA scaffolds. Therefore, PHBV/PCL electrospun nonwoven scaffolds demonstrated the best results regarding endothelial cell proliferation and viability as compared to PCL and PLA scaffolds.

  9. The Modulation of Endothelial Cell Morphology, Function, and Survival Using Anisotropic Nanofibrillar Collagen Scaffolds

    PubMed Central

    Huang, Ngan F.; Okogbaa, Janet; Lee, Jerry C.; Jha, Arshi; Zaitseva, Tatiana S.; Paukshto, Michael V.; Sun, John; Punjya, Niraj; Fuller, Gerald G.; Cooke, John P.

    2013-01-01

    Endothelial cells (ECs) are aligned longitudinally under laminar flow, whereas they are polygonal and poorly aligned in regions of disturbed flow. The unaligned ECs in disturbed flow fields manifest altered function and reduced survival that promote lesion formation. We demonstrate that the alignment of the ECs may directly influence their biology, independent of fluid flow. We developed aligned nanofibrillar collagen scaffolds that mimic the structure of collagen bundles in blood vessels, and examined the effects of these materials on EC alignment, function, and in vivo survival. ECs cultured on 30-nm diameter aligned fibrils re-organized their F-actin along the nanofibril direction, and were 50% less adhesive for monocytes than the ECs grown on randomly oriented fibrils. After EC transplantation into both subcutaneous tissue and the ischemic hindlimb, EC viability was enhanced when ECs were cultured and implanted on aligned nanofibrillar scaffolds, in contrast to non-patterned scaffolds. ECs derived from human induced pluripotent stem cells and cultured on aligned scaffolds also persisted for over 28 days, as assessed by bioluminescence imaging, when implanted in ischemic tissue. By contrast, ECs implanted on scaffolds without nanopatterning generated no detectable bioluminescent signal by day 4 in either normal or ischemic tissues. We demonstrate that 30-nm aligned nanofibrillar collagen scaffolds guide cellular organization, modulate endothelial inflammatory response, and enhance cell survival after implantation in normal and ischemic tissues. PMID:23480958

  10. The modulation of endothelial cell morphology, function, and survival using anisotropic nanofibrillar collagen scaffolds.

    PubMed

    Huang, Ngan F; Okogbaa, Janet; Lee, Jerry C; Jha, Arshi; Zaitseva, Tatiana S; Paukshto, Michael V; Sun, John S; Punjya, Niraj; Fuller, Gerald G; Cooke, John P

    2013-05-01

    Endothelial cells (ECs) are aligned longitudinally under laminar flow, whereas they are polygonal and poorly aligned in regions of disturbed flow. The unaligned ECs in disturbed flow fields manifest altered function and reduced survival that promote lesion formation. We demonstrate that the alignment of the ECs may directly influence their biology, independent of fluid flow. We developed aligned nanofibrillar collagen scaffolds that mimic the structure of collagen bundles in blood vessels, and examined the effects of these materials on EC alignment, function, and in vivo survival. ECs cultured on 30-nm diameter aligned fibrils re-organized their F-actin along the nanofibril direction, and were 50% less adhesive for monocytes than the ECs grown on randomly oriented fibrils. After EC transplantation into both subcutaneous tissue and the ischemic hindlimb, EC viability was enhanced when ECs were cultured and implanted on aligned nanofibrillar scaffolds, in contrast to non-patterned scaffolds. ECs derived from human induced pluripotent stem cells and cultured on aligned scaffolds also persisted for over 28 days, as assessed by bioluminescence imaging, when implanted in ischemic tissue. By contrast, ECs implanted on scaffolds without nanopatterning generated no detectable bioluminescent signal by day 4 in either normal or ischemic tissues. We demonstrate that 30-nm aligned nanofibrillar collagen scaffolds guide cellular organization, modulate endothelial inflammatory response, and enhance cell survival after implantation in normal and ischemic tissues.

  11. Three-dimensional polycaprolactone scaffold via needleless electrospinning promotes cell proliferation and infiltration.

    PubMed

    Li, Dawei; Wu, Tong; He, Nanfei; Wang, Jing; Chen, Weiming; He, Liping; Huang, Chen; Ei-Hamshary, Hany A; Al-Deyab, Salem S; Ke, Qinfei; Mo, Xiumei

    2014-09-01

    Electrospinning has been widely used in fabrication of tissue engineering scaffolds. Currently, most of the electrospun nanofibers performed like a conventional two-dimensional (2D) membrane, which hindered their further applications. Moreover, the low production rate of the traditional needle-electrospinning (NE) also limited the commercialization. In this article, disc-electrospinning (DE) was utilized to fabricate a three-dimensional (3D) scaffold consisting of porous macro/nanoscale fibers. The morphology of the porous structure was investigated by scanning electron microscopy images, which showed irregular pores of nanoscale spreading on the surface of DE polycaprolactone (PCL) fibers. Protein adsorption assessment illustrated the porous structure could significantly enhance proteins pickup, which was 55% higher than that of solid fiber scaffolds. Fibroblasts were cultured on the scaffold. The results demonstrated that DE fiber scaffold could enhance initial cell attachment. In the 7 days of culture, fibroblasts grew faster on DE fiber scaffold in comparison with solid fiber, solvent cast (SC) film and TCP. Fibroblasts on DE fibers showed a stretched shape and integrated with the porous surface tightly. Cells were also found to migrate into the DE scaffold up to 800μm. Results supported the use of DE PCL fibers as a 3D tissue engineering scaffold in soft tissue regeneration.

  12. E-spun composite fibers of collagen and dragline silk protein: fiber mechanics, biocompatibility, and application in stem cell differentiation.

    PubMed

    Zhu, Bofan; Li, Wen; Lewis, Randolph V; Segre, Carlo U; Wang, Rong

    2015-01-12

    Biocomposite matrices with high mechanical strength, high stability, and the ability to direct matrix-specific stem cell differentiation are essential for the reconstruction of lesioned tissues in tissue engineering and cell therapeutics. Toward this end, we used the electrospinning technique to fabricate well-aligned composite fibers from collagen and spider dragline silk protein, obtained from the milk of transgenic goats, mimicking the native extracellular matrix (ECM) on a similar scale. Collagen and the dragline silk proteins were found to mix homogeneously at all ratios in the electrospun (E-spun) fibers. As a result, the ultimate tensile strength and elasticity of the fibers increased monotonically with silk percentage, whereas the stretchability was slightly reduced. Strikingly, we found that the incorporation of silk proteins to collagen dramatically increased the matrix stability against excessive fiber swelling and shape deformation in cell culture medium. When human decidua parietalis placental stem cells (hdpPSCs) were seeded on the collagen-silk matrices, the matrices were found to support cell proliferation at a similar rate as that of the pure collagen matrix, but they provided cell adhesion with reduced strengths and induced cell polarization at varied levels. Matrices containing 15 and 30 wt % silk in collagen (CS15, CS30) were found to induce a level of neural differentiation comparable to that of pure collagen. In particular, CS15 matrix induced the highest extent of cell polarization and promoted the development of extended 1D neural filaments strictly in-line with the aligned fibers. Taking the increased mechanical strength and fiber stability into consideration, CS15 and CS30 E-spun fibers offer better alternatives to pure collagen fibers as scaffolds that can be potentially utilized in neural tissue repair and the development of future nanobiodevices.

  13. Aligned Electrospun Polyvinyl Pyrrolidone/Poly ɛ-Caprolactone Blend Nanofiber Mats for Tissue Engineering

    NASA Astrophysics Data System (ADS)

    Charernsriwilaiwat, Natthan; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2016-02-01

    Electrospun nanofibrous materials are widely used in medical applications such as tissue engineering scaffolds, wound dressing material and drug delivery carriers. For tissue engineering scaffolds, the structure of the nanofiber is similar to extracellular matrix (ECM) which promotes the cell growth and proliferation. In the present study, the aligned nanofiber mats of polyvinyl pyrrolidone (PVP) blended poly ɛ-caprolactone (PCL) was successfully generated using electrospinning technique. The morphology of PVP/PCL nanofiber mats were characterized by scanning electron microspore (SEM). The chemical and crystalline structure of PVP/PCL nanofiber mats were analyzed using Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffactometer (PXRD). The water contact angle of mats was investigated. Cell culture studies using normal human fibroblasts (NHF) were performed to assess cell morphology, cell alignment and cell proliferation. The results indicated that the fiber were in nanometer range. The PVP/PCL was well dispersed in nanofiber mats and was in amorphous form. The water contact angle of PVP/PCL nanofiber mats was lower than PCL nanofiber mats. The PVP/PCL nanofiber mats exhibited good biocompatibility with NHF cells. In summary, the PVP/PCL nanofiber mats had potential to be used in tissue engineering and regenerative medicine.

  14. Neuregulin 1 functionalization of organic fibers for Schwann cell guidance

    NASA Astrophysics Data System (ADS)

    Tonazzini, Ilaria; Moffa, Maria; Pisignano, Dario; Cecchini, Marco

    2017-04-01

    The repair of peripheral nerve lesions is a clinical problem where the functional recovery is often far from being satisfactory, although peripheral nerves generally retain good potential for regeneration. Here, we develop a novel scaffold approach based on bioactive fibers of poly(ε-caprolactone) where nanotopographical guidance and neuregulin 1 (NRG1) cues are combined. We interface them with rat primary Schwann cells (SCs), the peripheral glial cells that drive initial regeneration of injured nerves, and found that the combination of NRG1 with parallel nano-fibrous topographies is effective in improving SC growth up to 72 h, alignment to fiber topography, and bipolar differentiation, opening original perspectives for nerve repair applications.

  15. ALIGNING JIG

    DOEpatents

    Culver, J.S.; Tunnell, W.C.

    1958-08-01

    A jig or device is described for setting or aligning an opening in one member relative to another member or structure, with a predetermined offset, or it may be used for measuring the amount of offset with which the parts have previously been sct. This jig comprises two blocks rabbeted to each other, with means for securing thc upper block to the lower block. The upper block has fingers for contacting one of the members to be a1igmed, the lower block is designed to ride in grooves within the reference member, and calibration marks are provided to determine the amount of offset. This jig is specially designed to align the collimating slits of a mass spectrometer.

  16. Image alignment

    DOEpatents

    Dowell, Larry Jonathan

    2014-04-22

    Disclosed is a method and device for aligning at least two digital images. An embodiment may use frequency-domain transforms of small tiles created from each image to identify substantially similar, "distinguishing" features within each of the images, and then align the images together based on the location of the distinguishing features. To accomplish this, an embodiment may create equal sized tile sub-images for each image. A "key" for each tile may be created by performing a frequency-domain transform calculation on each tile. A information-distance difference between each possible pair of tiles on each image may be calculated to identify distinguishing features. From analysis of the information-distance differences of the pairs of tiles, a subset of tiles with high discrimination metrics in relation to other tiles may be located for each image. The subset of distinguishing tiles for each image may then be compared to locate tiles with substantially similar keys and/or information-distance metrics to other tiles of other images. Once similar tiles are located for each image, the images may be aligned in relation to the identified similar tiles.

  17. Fully passive-alignment pluggable compact parallel optical interconnection modules based on a direct-butt-coupling structure for fiber-optic applications

    NASA Astrophysics Data System (ADS)

    Lim, Kwon-Seob; Park, Hyoung-Jun; Kang, Hyun Seo; Kim, Young Sun; Jang, Jae-Hyung

    2016-02-01

    A low-cost packaging method utilizing a fully passive optical alignment and surface-mounting method is demonstrated for pluggable compact and slim multichannel optical interconnection modules using a VCSEL/PIN-PD chip array. The modules are based on a nonplanar bent right-angle electrical signal path on a silicon platform and direct-butt-optical coupling without a bulky and expensive microlens array. The measured optical direct-butt-coupling efficiencies of each channel without any bulky optics are as high as 33% and 95% for the transmitter and receiver, respectively. Excellent lateral optical alignment tolerance of larger than 60 μm for both the transmitter and receiver module significantly reduces the manufacturing and material costs as well as the packaging time. The clear eye diagrams, extinction ratios higher than 8 dB at 10.3 Gbps for the transmitter module, and receiver sensitivity of better than -13.1 dBm at 10.3 Gbps and a bit error rate of 10-12 for all channels are demonstrated. Considering that the optical output power of the transmitter is greater than 0 dBm, the module has a sufficient power margin of about 13 dB for 10.3 Gbps operations for all channels.

  18. Design of nano- and microfiber combined scaffolds by electrospinning of collagen onto starch-based fiber meshes: a man-made equivalent of natural extracellular matrix.

    PubMed

    Tuzlakoglu, Kadriye; Santos, Marina I; Neves, Nuno; Reis, Rui L

    2011-02-01

    Mimicking the structural organization and biologic function of natural extracellular matrix has been one of the main goals of tissue engineering. Nevertheless, the majority of scaffolding materials for bone regeneration highlights biochemical functionality in detriment of mechanical properties. In this work we present a rather innovative construct that combines in the same structure electrospun type I collagen nanofibers with starch-based microfibers. These combined structures were obtained by a two-step methodology and structurally consist in a type I collagen nano-network incorporated on a macro starch-based support. The morphology of the developed structures was assessed by several microscopy techniques and the collagenous nature of the nano-network was confirmed by immunohistochemistry. In addition, and especially regarding the requirements of large bone defects, we also successfully introduced the concept of layer by layer, as a way to produce thicker structures. In an attempt to recreate bone microenvironment, the design and biochemical composition of the combined structures also envisioned bone-forming cells and endothelial cells (ECs). The inclusion of a type I collagen nano-network induced a stretched morphology and improved the metabolic activity of osteoblasts. Regarding ECs, the presence of type I collagen on the combined structures provided adhesive support and obviated the need of precoating with fibronectin. It was also importantly observed that ECs on the nano-network organized into circular structures, a three-dimensional arrangement distinct from that observed for osteoblasts and resembling the microcappillary-like organizations formed during angiogenesis. By providing simultaneously physical and chemical cues for cells, the herein-proposed combined structures hold a great potential in bone regeneration as a man-made equivalent of extracellular matrix.

  19. Electrospinning of oriented and nonoriented ultrafine fibers of biopolymers

    NASA Astrophysics Data System (ADS)

    Vu, David

    2005-07-01

    Chitosan has long been known as a biocompatible and biodegradable material suitable for tissue engineering applications. Unfortunately, conventional chitosan solutions cannot be used for electrospinning due to their high conductivity, viscosity and surface tension. We have developed a method to produce clear chitosan solutions with conductivities, surface tension and viscosities that facilitate their processing into micron and submicron fibers via electrospinning. Acetic acid, carbon dioxide and organic solvents are key ingredients in preparing the chitosan solutions. Oriented and non oriented chitosan fibers were produced with the ultimate goal of designing a suitable tissue engineering scaffold. Circularly oriented, continuous, and aligned nanofibers were produced via this technique in the form of a thin membrane or fibrous "mat". Chitosan fiber diameters ranged from 5 micrometers down to 100 nanometers. The structure and mechanical properties of oriented and randomly aligned chitosan fiber deposits could potentially be exploited for cartilage tissue engineering. Ultrafine fibers of starch acetate (SA) also were prepared by the electrospinning process. In this study, solvent mixtures based on DMF, DMSO, pyrindine, acetic acid, acetone, THF, DMC, chloroform were used. A two-solvent formulation was used to study the effect of viscosity, surface tension, and conductivity to the fiber diameter. Also, water and ethanol were used to decrease the boiling point of the solvent, and to make bundled fibers. Several techniques such as scanning electron microscopy, conductmetry, viscometry, and tensiometry were used in this study. The results showed that the combined effects of viscosity, surface tension, and conductivity are of great importance in controlling the diameter of the fibers. We were able to produce SA fibers that was less than 40 nm in diameter. The dependence of fiber diameter on flow-rate, electric field and solvents also was investigated. A rotating disk and a

  20. Surface microstructures on planar substrates and textile fibers guide neurite outgrowth: a scaffold solution to push limits of critical nerve defect regeneration?

    PubMed

    Weigel, Stefan; Osterwalder, Thomas; Tobler, Ursina; Yao, Li; Wiesli, Manuel; Lehnert, Thomas; Pandit, Abhay; Bruinink, Arie

    2012-01-01

    The treatment of critical size peripheral nerve defects represents one of the most serious problems in neurosurgery. If the gap size exceeds a certain limit, healing can't be achieved. Connection mismatching may further reduce the clinical success. The present study investigates how far specific surface structures support neurite outgrowth and by that may represent one possibility to push distance limits that can be bridged. For this purpose, growth cone displacement of fluorescent embryonic chicken spinal cord neurons was monitored using time-lapse video. In a first series of experiments, parallel patterns of polyimide ridges of different geometry were created on planar silicon oxide surfaces. These channel-like structures were evaluated with and without amorphous hydrogenated carbon (a-C:H) coating. In a next step, structured and unstructured textile fibers were investigated. All planar surface materials (polyimide, silicon oxide and a-C:H) proved to be biocompatible, i.e. had no adverse effect on nerve cultures and supported neurite outgrowth. Mean growth cone migration velocity measured on 5 minute base was marginally affected by surface structuring. However, surface structure variability, i.e. ridge height, width and inter-ridge spacing, significantly enhanced the resulting net velocity by guiding the growth cone movement. Ridge height and inter-ridge distance affected the frequency of neurites crossing over ridges. Of the evaluated dimensions ridge height, width, and inter-ridge distance of respectively 3, 10, and 10 µm maximally supported net axon growth. Comparable artificial grooves, fabricated onto the surface of PET fibers by using an excimer laser, showed similar positive effects. Our data may help to further optimize surface characteristics of artificial nerve conduits and bioelectronic interfaces.

  1. Apparatus Impregnates Weak Fibers

    NASA Technical Reports Server (NTRS)

    Stanfield, Clarence E.; Wilson, Maywood L.

    1989-01-01

    Low-cost apparatus developed for use in conventional drum winding machine to impregnate fibrous materials having very low tensile strengths. Fiber fitted onto freely-spinning unwinding creel. Unwinds from creel between two tension bars onto guide spools, aligns fiber so properly enters sealed reservoir of resin. Stainless-steel metering die at entrance to reservoir aligns fiber and seals reservoir. Beneficial results obtained by use of reservoir made of polyethylene. Composite material made from resin matrices reinforced by fibers have great potential for solving challenging and often critical problems in design of spacecraft, space structures, and terrestrial structures.

  2. Electrospun biomaterial scaffolds with varied topographies for neuronal differentiation of human-induced pluripotent stem cells.

    PubMed

    Mohtaram, Nima Khadem; Ko, Junghyuk; King, Craig; Sun, Lin; Muller, Nathan; Jun, Martin Byung-Guk; Willerth, Stephanie M

    2015-08-01

    In this study, we investigated the effect of micro and nanoscale scaffold topography on promoting neuronal differentiation of human induced pluripotent stem cells (iPSCs) and directing the resulting neuronal outgrowth in an organized manner. We used melt electrospinning to fabricate poly (ε-caprolactone) (PCL) scaffolds with loop mesh and biaxial aligned microscale topographies. Biaxial aligned microscale scaffolds were further functionalized with retinoic acid releasing PCL nanofibers using solution electrospinning. These scaffolds were then seeded with neural progenitors derived from human iPSCs. We found that smaller diameter loop mesh scaffolds (43.7 ± 3.9 µm) induced higher expression of the neural markers Nestin and Pax6 compared to thicker diameter loop mesh scaffolds (85 ± 4 µm). The loop mesh and biaxial aligned scaffolds guided the neurite outgrowth of human iPSCs along the topographical features with the maximum neurite length of these cells being longer on the biaxial aligned scaffolds. Finally, our novel bimodal scaffolds also supported the neuronal differentiation of human iPSCs as they presented both physical and chemical cues to these cells, encouraging their differentiation. These results give insight into how physical and chemical cues can be used to engineer neural tissue.

  3. An Advanced Electrospinning Method of Fabricating Nanofibrous Patterned Architectures with Controlled Deposition and Desired Alignment

    NASA Astrophysics Data System (ADS)

    Rasel, Sheikh Md

    We introduce a versatile advanced method of electrospinning for fabricating various kinds of nanofibrous patterns along with desired alignment, controlled amount of deposition and locally variable density into the architectures. In this method, we employed multiple electrodes whose potentials have been altered in milliseconds with the help of microprocessor based control system. Therefore, key success of this method was that the electrical field as well as charge carrying fibers could be switched shortly from one electrode's location to another, as a result, electrospun fibers could be deposited on the designated areas with desired alignment. A wide range of nanofibrous patterned architectures were constructed using proper arrangement of multiple electrodes. By controlling the concurrent activation time of two adjacent electrodes, we demonstrated that amount of fibers going into the pattern can be adjusted and desired alignment in electrospun fibers can be obtained. We also revealed that the deposition density of electrospun fibers in different areas of patterned architectures can be varied. We showed that by controlling the deposition time between two adjacent electrodes, a number of functionally graded patterns can be generated with uniaxial alignment. We also demonstrated that this handy method was capable of producing random, aligned, and multidirectional nanofibrous mats by engaging a number of electrodes and switching them in desired patterns. A comprehensive study using finite element method was carried out to understand the effects of electrical field. Simulation results revealed that electrical field strength alters shortly based on electrode control switch patterns. Nanofibrous polyvinyl alcohol (PVA) scaffolds and its composite reinforced with wollastonite and wood flour were fabricated using rotating drum electrospinning technique. Morphological, mechanical, and thermal, properties were characterized on PVA/wollastonite and PVA/wood flour nanocomposites

  4. Laser-machined microfluidic bioreactors with printed scaffolds and integrated optical waveguides

    NASA Astrophysics Data System (ADS)

    Nguyen, Michael N.; Fahlenkamp, Heather D.; Higbee, Russell G.; Kachurin, Anatoly M.; Church, Kenneth H.; Warren, William L.

    2004-12-01

    Laser micromachining combined with digital printing allows rapid prototyping of complex bioreactors with reduced fabrication times compared to multi-mask photolithography. Microfluidic bioreactors with integrated optical waveguides for diagnostics have been fabricated via ultrashort pulse laser micromachining and digital printing. The microfluidic channels are directly laser machined into poly(dimethylsiloxane) (PDMS) silicone elastomer. Multimode optical waveguides are formed by coating the PDMS with alternating refractive index polymer layers and laser machining to define the waveguide geometry. Tapered alignment grooves are also laser machined to aid in coupling optical fibers to the waveguides. Three-dimensional (3-D) bio-scaffold matrices comprising liquid solutions that can be selectively and rapidly gelled are digitally printed inside the bioreactors and filled with nutrient rich media and cells. This paper will describe the maskless fabrication of complex 3-D bioreactors and discuss their performance characteristics.

  5. Fabrication of aligned poly (vinyl alcohol) nanofibers by electrospinning.

    PubMed

    Chuangchote, Surawut; Supaphol, Pitt

    2006-01-01

    Electrospinning has become a versatile tool for fabricating nanofibers from materials of diverse origins. Normally, mats of randomly-aligned fibers were obtained. A number of techniques have been proposed to arrive at uniaxially-aligned fibers. This work reports a new technique, i.e., dual vertical wire technique, for fabrication of uniaxially-aligned fibers. This technique utilized two stainless steel wires that were vertically set in a parallel manner between a charged needle and a grounded collector plate. This technique allowed simultaneous collection of aligned fibers (between the parallel vertical wires) and a randomly-aligned fiber mat (on the collector plate). Application of the technique on poly(vinyl alcohol) (PVA) to prepare uniaxially-aligned fibers was found to be successful at short collection times. Unexpected formation of a large fiber tow consisting of individual as-spun nanofibers that were bound into a bundle was observed at long collection times. Morphological appearance and size of the fiber tow was affected by the change in the distance between the two vertical wire electrodes, while the average diameter of the individual fibers was not (i.e., about 340 to 350 nm). Lastly, mechanical properties and thermal behavior of the fiber tow were also investigated.

  6. Global multiple protein-protein interaction network alignment by combining pairwise network alignments

    PubMed Central

    2015-01-01

    Background A wealth of protein interaction data has become available in recent years, creating an urgent need for powerful analysis techniques. In this context, the problem of finding biologically meaningful correspondences between different protein-protein interaction networks (PPIN) is of particular interest. The PPIN of a species can be compared with that of other species through the process of PPIN alignment. Such an alignment can provide insight into basic problems like species evolution and network component function determination, as well as translational problems such as target identification and elucidation of mechanisms of disease spread. Furthermore, multiple PPINs can be aligned simultaneously, expanding the analytical implications of the result. While there are several pairwise network alignment algorithms, few methods are capable of multiple network alignment. Results We propose SMAL, a MNA algorithm based on the philosophy of scaffold-based alignment. SMAL is capable of converting results from any global pairwise alignment algorithms into a MNA in linear time. Using this method, we have built multiple network alignments based on combining pairwise alignments from a number of publicly available (pairwise) network aligners. We tested SMAL using PPINs of eight species derived from the IntAct repository and employed a number of measures to evaluate performance. Additionally, as part of our experimental investigations, we compared the effectiveness of SMAL while aligning up to eight input PPINs, and examined the effect of scaffold network choice on the alignments. Conclusions A key advantage of SMAL lies in its ability to create MNAs through the use of pairwise network aligners for which native MNA implementations do not exist. Experiments indicate that the performance of SMAL was comparable to that of the native MNA implementation of established methods such as IsoRankN and SMETANA. However, in terms of computational time, SMAL was significantly faster

  7. Microstructures and martensitic transformation behavior of superelastic Ti-Ni-Ag scaffolds

    SciTech Connect

    Li, Shuanglei; Kim, Eun-soo; Kim, Yeon-wook; Nam, Tae-hyun

    2016-10-15

    Highlights: • The B2-R-B19′ transformation occurred in 49Ti-50.3Ni-0.7Ag alloy fibers. • Annealing treated alloy fibers showed superelastic recovery ratio of 93%. • Ageing treated scaffold had an elastic modulus of 0.67 GPa. • Ageing treated scaffold exhibited good superelasticity at human body temperature. - Abstract: Ti-Ni-Ag scaffolds were prepared by sintering rapidly solidified alloy fibers. Microstructures and transformation behaviors of alloy fibers and scaffolds were investigated by means of electron probe micro-analyzer (EPMA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The B2-R-B19′ transformation occurs in alloy fibers. The alloy fibers have good superelasticity with superelastic recovery ratio of 93% after annealing heat treatment. The as-sintered Ti-Ni-Ag scaffolds possess three-dimensional and interconnected pores and have the porosity level of 80%. The heat treated Ti-Ni-Ag scaffolds not only have an elastic modulus of 0.67 GPa, which match well with that of cancellous bone, but also show excellent superelasticity at human body temperature. In terms of the mechanical properties, the Ti-Ni-Ag scaffolds in this study can meet the main requirements of bone scaffold for the purpose of bone replacement applications.

  8. Cell infiltration and growth in a low density, uncompressed three-dimensional electrospun nanofibrous scaffold.

    PubMed

    Blakeney, Bryan A; Tambralli, Ajay; Anderson, Joel M; Andukuri, Adinarayana; Lim, Dong-Jin; Dean, Derrick R; Jun, Ho-Wook

    2011-02-01

    A limiting factor of traditional electrospinning is that the electrospun scaffolds consist entirely of tightly packed nanofiber layers that only provide a superficial porous structure due to the sheet-like assembly process. This unavoidable characteristic hinders cell infiltration and growth throughout the nanofibrous scaffolds. Numerous strategies have been tried to overcome this challenge, including the incorporation of nanoparticles, using larger microfibers, or removing embedded salt or water-soluble fibers to increase porosity. However, these methods still produce sheet-like nanofibrous scaffolds, failing to create a porous three-dimensional scaffold with good structural integrity. Thus, we have developed a three-dimensional cotton ball-like electrospun scaffold that consists of an accumulation of nanofibers in a low density and uncompressed manner. Instead of a traditional flat-plate collector, a grounded spherical dish and an array of needle-like probes were used to create a Focused, Low density, Uncompressed nanoFiber (FLUF) mesh scaffold. Scanning electron microscopy showed that the cotton ball-like scaffold consisted of electrospun nanofibers with a similar diameter but larger pores and less-dense structure compared to the traditional electrospun scaffolds. In addition, laser confocal microscopy demonstrated an open porosity and loosely packed structure throughout the depth of the cotton ball-like scaffold, contrasting the superficially porous and tightly packed structure of the traditional electrospun scaffold. Cells seeded on the cotton ball-like scaffold infiltrated into the scaffold after 7 days of growth, compared to no penetrating growth for the traditional electrospun scaffold. Quantitative analysis showed approximately a 40% higher growth rate for cells on the cotton ball-like scaffold over a 7 day period, possibly due to the increased space for in-growth within the three-dimensional scaffolds. Overall, this method assembles a nanofibrous scaffold

  9. The influence of specimen thickness and alignment on the material and failure properties of electrospun polycaprolactone nanofiber mats.

    PubMed

    Mubyana, Kuwabo; Koppes, Ryan A; Lee, Kristen L; Cooper, James A; Corr, David T

    2016-11-01

    Electrospinning is a versatile fabrication technique that has been recently expanded to create nanofibrous structures that mimic ECM topography. Like many materials, electrospun constructs are typically characterized on a smaller scale, and scaled up for various applications. This established practice is based on the assumption that material properties, such as toughness, failure stress and strain, are intrinsic to the material, and thus will not be influenced by specimen geometry. However, we hypothesized that the material and failure properties of electrospun nanofiber mats vary with specimen thickness. To test this, we mechanically characterized polycaprolactone (PCL) nanofiber mats of three different thicknesses in response to constant rate elongation to failure. To identify if any observed thickness-dependence could be attributed to fiber alignment, such as the effects of fiber reorientation during elongation, these tests were performed in mats with either random or aligned nanofiber orientation. Contrary to our hypothesis, the failure strain was conserved across the different thicknesses, indicating similar maximal elongation for specimens of different thickness. However, in both the aligned and randomly oriented groups, the ultimate tensile stress, short-range modulus, yield modulus, and toughness all decreased with increasing mat thickness, thereby indicating that these are not intrinsic material properties. These findings have important implications in engineered scaffolds for fibrous and soft tissue applications (e.g., tendon, ligament, muscle, and skin), where such oversights could result in unwanted laxity or reduced resistance to failure. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2794-2800, 2016.

  10. Fiber optics welder

    DOEpatents

    Higgins, R.W.; Robichaud, R.E.

    A system is described for welding fiber optic waveguides together. The ends of the two fibers to be joined together are accurately, collinearly aligned in a vertical orientation and subjected to a controlled, diffuse arc to effect welding and thermal conditioning. A front-surfaced mirror mounted at a 45/sup 0/ angle to the optical axis of a stereomicroscope mounted for viewing the junction of the ends provides two orthogonal views of the interface during the alignment operation.

  11. Poly(glycerol sebacate)/poly(butylene succinate-butylene dilinoleate) fibrous scaffolds for cardiac tissue engineering.

    PubMed

    Tallawi, Marwa; Zebrowski, David C; Rai, Ranjana; Roether, Judith A; Schubert, Dirk W; El Fray, Miroslawa; Engel, Felix B; Aifantis, Katerina E; Boccaccini, Aldo R

    2015-06-01

    The present article investigates the use of a novel electrospun fibrous blend of poly(glycerol sebacate) (PGS) and poly(butylene succinate-butylene dilinoleate) (PBS-DLA) as a candidate for cardiac tissue engineering. Random electrospun fibers with various PGS/PBS-DLA compositions (70/30, 60/40, 50/50, and 0/100) were fabricated. To examine the suitability of these fiber blends for heart patches, their morphology, as well as their physical, chemical, and mechanical properties were measured before examining their biocompatibility through cell adhesion. The fabricated fibers were bead-free and exhibited a relatively narrow diameter distribution. The addition of PBS-DLA to PGS resulted in an increase of the average fiber diameter, whereas increasing the amount of PBS-DLA decreased the hydrophilicity and the water uptake of the nanofibrous scaffolds to values that approached those of neat PBS-DLA nanofibers. Moreover, the addition of PBS-DLA significantly increased the elastic modulus. Initial toxicity studies with C2C12 myoblast cells up to 72 h confirmed nontoxic behavior of the blends. Immunofluorescence analyses and scanning electron microscopy analyses confirmed that C2C12 cells showed better cell attachment and proliferation on electrospun mats with higher PBS-DLA content. However, immunofluorescence analyses of the 3-day-old rat cardiomyocytes cultured for 2 and 5 days demonstrated better attachment on the 70/30 fibers containing well-aligned sarcomeres and expressing high amounts of connexin 43 in cellular junctions indicating efficient cell-to-cell communication. It can be concluded, therefore, that fibrous PGS/PBS-DLA scaffolds exhibit promising characteristics as a biomaterial for cardiac patch applications.

  12. Electrospun Polycaprolactone Scaffolds for Small-Diameter Tissue Engineered Blood Vessels

    NASA Astrophysics Data System (ADS)

    Lee, Carol Hsiu-Yueh

    Cardiovascular disease is the leading cause of death in the United States with many patients requiring coronary artery bypass grafting. The current standard is using autografts such as the saphenous vein or intimal mammary artery, however creating a synthetic graft could eliminate this painful and inconvenient procedure. Large diameter grafts have long been established with materials such as DacronRTM and TeflonRTM, however these materials have not proved successful in small-diameter (< 6 mm) grafts where thrombosis and intimal hyperplasia are common in graft failure. With the use of a synthetic biodegradable polymer (polycaprolactone) we utilize our expertise in electrospinning and femtosecond laser ablation to create a novel tri-layered tissue engineered blood vessel containing microchannels. The benefits of creating a tri-layer is to mimic native arteries that contain an endothelium to prevent thrombosis in the inner layer, aligned smooth muscle cells in the middle to control vasodilation and constriction, and a mechanically robust outer layer. The following work evaluates the mechanical properties of such a graft (tensile, fatigue, burst pressure, and suture retention strength), the ability to rapidly align cells in laser ablated microchannels in PCL scaffolds, and the biological integration (co-culture of endothelial and smooth muscle cells) with electrospun PCL scaffolds. The conclusions from this work establish that the electrospun tri-layers provide adequate mechanical strength as a tissue engineered blood vessel, that laser ablated microchannels are able to contain the smooth muscle cells, and that cells are able to adhere to PCL fibers. However, future work includes adjusting microchannel dimensions to properly align smooth muscle cells along with perfect co-cultures of endothelial and smooth muscle cells on the electrospun tri-layer.

  13. Biomimetic magnetic silk scaffolds.

    PubMed

    Samal, Sangram K; Dash, Mamoni; Shelyakova, Tatiana; Declercq, Heidi A; Uhlarz, Marc; Bañobre-López, Manuel; Dubruel, Peter; Cornelissen, Maria; Herrmannsdörfer, Thomas; Rivas, Jose; Padeletti, Giuseppina; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L; Dediu, V Alek

    2015-03-25

    Magnetic silk fibroin protein (SFP) scaffolds integrating magnetic materials and featuring magnetic gradients were prepared for potential utility in magnetic-field assisted tissue engineering. Magnetic nanoparticles (MNPs) were introduced into SFP scaffolds via dip-coating methods, resulting in magnetic SFP scaffolds with different strengths of magnetization. Magnetic SFP scaffolds showed excellent hyperthermia properties achieving temperature increases up to 8 °C in about 100 s. The scaffolds were not toxic to osteogenic cells and improved cell adhesion and proliferation. These findings suggest that tailored magnetized silk-based biomaterials can be engineered with interesting features for biomaterials and tissue-engineering applications.

  14. Additive manufacturing of wet-spun polymeric scaffolds for bone tissue engineering.

    PubMed

    Puppi, Dario; Mota, Carlos; Gazzarri, Matteo; Dinucci, Dinuccio; Gloria, Antonio; Myrzabekova, Mairam; Ambrosio, Luigi; Chiellini, Federica

    2012-12-01

    An Additive Manufacturing technique for the fabrication of three-dimensional polymeric scaffolds, based on wet-spinning of poly(ε-caprolactone) (PCL) or PCL/hydroxyapatite (HA) solutions, was developed. The processing conditions to fabricate scaffolds with a layer-by-layer approach were optimized by studying their influence on fibres morphology and alignment. Two different scaffold architectures were designed and fabricated by tuning inter-fibre distance and fibres staggering. The developed scaffolds showed good reproducibility of the internal architecture characterized by highly porous, aligned fibres with an average diameter in the range 200-250 μm. Mechanical characterization showed that the architecture and HA loading influenced the scaffold compressive modulus and strength. Cell culture experiments employing MC3T3-E1 preosteoblast cell line showed good cell adhesion, proliferation, alkaline phosphatase activity and bone mineralization on the developed scaffolds.

  15. Scaffold architecture and fibrin gels promote meniscal cell proliferation

    SciTech Connect

    Pawelec, K. M. E-mail: jw626@cam.ac.uk; Best, S. M.; Cameron, R. E.; Wardale, R. J. E-mail: jw626@cam.ac.uk

    2015-01-01

    Stability of the knee relies on the meniscus, a complex connective tissue with poor healing ability. Current meniscal tissue engineering is inadequate, as the signals for increasing meniscal cell proliferation have not been established. In this study, collagen scaffold structure, isotropic or aligned, and fibrin gel addition were tested. Metabolic activity was promoted by fibrin addition. Cellular proliferation, however, was significantly increased by both aligned architectures and fibrin addition. None of the constructs impaired collagen type I production or triggered adverse inflammatory responses. It was demonstrated that both fibrin gel addition and optimized scaffold architecture effectively promote meniscal cell proliferation.

  16. Design of super-elastic biodegradable scaffolds with longitudinally oriented microchannels and optimization of the channel size for Schwann cell migration

    NASA Astrophysics Data System (ADS)

    Uto, Koichiro; Muroya, Takanari; Okamoto, Michio; Tanaka, Hiroyuki; Murase, Tsuyoshi; Ebara, Mitsuhiro; Aoyagi, Takao

    2012-12-01

    We newly designed super-elastic biodegradable scaffolds with longitudinally oriented microchannels for repair and regeneration of peripheral nerve defects. Four-armed poly(ɛ-caprolactone-co-D,L-lactide)s (P(CL-co-DLLA)s) were synthesized by ring-opening copolymerization of CL and DLLA from terminal hydroxyl groups of pentaerythritol, and acryloyl chloride was then reacted with the ends of the chains. The end-functionalized P(CL-co-DLLA) was crosslinked in a cylindrical mold in the presence of longitudinally oriented silica fibers as the templates, which were later dissolved by hydrofluoric acid. The elastic moduli of the crosslinked P(CL-co-DLLA)s were controlled between 10-1 and 102 MPa at 37 °C, depending on the composition. The scaffolds could be elongated to 700% of their original size without fracture or damage (‘super-elasticity’). Scanning electron microscopy images revealed that well-defined and highly aligned multiple channels consistent with the mold design were produced in the scaffolds. Owing to their elastic nature, the microchannels in the scaffolds did not collapse when they were bent to 90°. To evaluate the effect of the channel diameter on Schwann cell migration, microchannels were also fabricated in transparent poly(dimethylsiloxane), allowing observation of cell migration. The migration speed increased with channel size, but the Young's modulus of the scaffold decreased as the channel diameter increased. These findings may serve as the basis for designing tissue-engineering scaffolds for nerve regeneration and investigating the effects of the geometrical and dimensional properties on axonal outgrowth.

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

    PubMed

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

    2014-11-01

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

  18. Electrospun Silk Biomaterial Scaffolds for Regenerative Medicine

    PubMed Central

    Zhang, Xiaohui; Reagan, Michaela R; Kaplan, David L.

    2009-01-01

    Electrospinning is a versatile technique that enables the development of nanofiber-based biomaterial scaffolds. Scaffolds can be generated that are useful for tissue engineering and regenerative medicine since they mimic the nanoscale properties of certain fibrous components of the native extracellular matrix in tissues. Silk is a natural protein with excellent biocompatibility, remarkable mechanical properties as well as tailorable degradability. Integrating these protein polymer advantages with electrospinning results in scaffolds with combined biochemical, topographical and mechanical cues with versatility for a range of biomaterial, cell and tissue studies and applications. This review covers research related to electrospinning of silk, including process parameters, post treatment of the spun fibers, functionalization of nanofibers, and the potential applications for these material systems in regenerative medicine. Research challenges and future trends are also discussed. PMID:19643154

  19. Electrospun aligned PLGA and PLGA/gelatin nanofibers embedded with silica nanoparticles for tissue engineering.

    PubMed

    Mehrasa, Mohammad; Asadollahi, Mohammad Ali; Ghaedi, Kamran; Salehi, Hossein; Arpanaei, Ayyoob

    2015-08-01

    Aligned poly lactic-co-glycolic acid (PLGA) and PLGA/gelatin nanofibrous scaffolds embedded with mesoporous silica nanoparticles (MSNPs) were fabricated using electrospinning method. The mean diameters of nanofibers were 641±24 nm for the pure PLGA scaffolds vs 418±85 nm and 267±58 nm for the PLGA/10 wt% MSNPs and the PLGA/gelatin/10 wt% MSNPs scaffolds, respectively. The contact angle measurement results (102°±6.7 for the pure PLGA scaffold vs 81°±6.8 and 18°±8.7 for the PLGA/10 wt% MSNPs and the PLGA/gelatin/10 wt% MSNPs scaffolds, respectively) revealed enhanced hydrophilicity of scaffolds upon incorporation of gelatin and MSNPs. Besides, embedding the scaffolds with MSNPs resulted in improved tensile mechanical properties. Cultivation of PC12 cells on the scaffolds demonstrated that introduction of MSNPs into PLGA and PLGA/gelatin matrices leads to the improved cell attachment and proliferation as well as long cellular processes. DAPI staining results indicated that cell proliferations on the PLGA/10 wt% MSNPs and the PLGA/gelatin/10 wt% MSNPs scaffolds were strikingly (nearly 2.5 and 3 folds, respectively) higher than that on the aligned pure PLGA scaffolds. These results suggest superior properties of silica nanoparticles-incorporated PLGA/gelatin eletrospun nanofibrous scaffolds for the stem cell culture and tissue engineering applications.

  20. Neurogenic differentiation of human umbilical cord mesenchymal stem cells on aligned electrospun polypyrrole/polylactide composite nanofibers with electrical stimulation

    NASA Astrophysics Data System (ADS)

    Zhou, Junfeng; Cheng, Liang; Sun, Xiaodan; Wang, Xiumei; Jin, Shouhong; Li, Junxiang; Wu, Qiong

    2016-09-01

    Adult central nervous system (CNS) tissue has a limited capacity to recover after trauma or disease. Recent medical cell therapy using polymeric biomaterialloaded stem cells with the capability of differentiation to specific neural population has directed focuses toward the recovery of CNS. Fibers that can provide topographical, biochemical and electrical cues would be attractive for directing the differentiation of stem cells into electro-responsive cells such as neuronal cells. Here we report on the fabrication of an electrospun polypyrrole/polylactide composite nanofiber film that direct or determine the fate of mesenchymal stem cells (MSCs), via combination of aligned surface topography, and electrical stimulation (ES). The surface morphology, mechanical properties and electric properties of the film were characterized. Comparing with that on random surface film, expression of neurofilament-lowest and nestin of human umbilical cord mesenchymal stemcells (huMSCs) cultured on film with aligned surface topography and ES were obviously enhanced. These results suggest that aligned topography combining with ES facilitates the neurogenic differentiation of huMSCs and the aligned conductive film can act as a potential nerve scaffold.

  1. The effect of the fibre orientation of electrospun scaffolds on the matrix production of rabbit annulus fibrosus-derived stem cells

    PubMed Central

    Liu, Chen; Zhu, Caihong; Li, Jun; Zhou, Pinghui; Chen, Min; Yang, Huilin; Li, Bin

    2015-01-01

    Annulus fibrosus (AF) tissue engineering has recently received increasing attention as a treatment for intervertebral disc (IVD) degeneration; however, such engineering remains challenging because of the remarkable complexity of AF tissue. In order to engineer a functional AF replacement, the fabrication of cell-scaffold constructs that mimic the cellular, biochemical and structural features of native AF tissue is critical. In this study, we fabricated aligned fibrous polyurethane scaffolds using an electrospinning technique and used them for culturing AF-derived stem/progenitor cells (AFSCs). Random fibrous scaffolds, also prepared via electrospinning, were used as a control. We compared the morphology, proliferation, gene expression and matrix production of AFSCs on aligned scaffolds and random scaffolds. There was no apparent difference in the attachment or proliferation of cells cultured on aligned scaffolds and random scaffolds. However, compared to cells on random scaffolds, the AFSCs on aligned scaffolds were more elongated and better aligned, and they exhibited higher gene expression and matrix production of collagen-I and aggrecan. The gene expression and protein production of collagen-II did not appear to differ between the two groups. Together, these findings indicate that aligned fibrous scaffolds may provide a favourable microenvironment for the differentiation of AFSCs into cells similar to outer AF cells, which predominantly produce collagen-I matrix. PMID:26273539

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

    PubMed

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

    2007-01-01

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

  3. Tubular Scaffold with Shape Recovery Effect for Cell Guide Applications

    PubMed Central

    Hossain, Kazi M. Zakir; Zhu, Chenkai; Felfel, Reda M.; Sharmin, Nusrat; Ahmed, Ifty

    2015-01-01

    Tubular scaffolds with aligned polylactic acid (PLA) fibres were fabricated for cell guide applications by immersing rolled PLA fibre mats into a polyvinyl acetate (PVAc) solution to bind the mats. The PVAc solution was also mixed with up to 30 wt % β-tricalcium phosphate (β-TCP) content. Cross-sectional images of the scaffold materials obtained via scanning electron microscopy (SEM) revealed the aligned fibre morphology along with a significant number of voids in between the bundles of fibres. The addition of β-TCP into the scaffolds played an important role in increasing the void content from 17.1% to 25.3% for the 30 wt % β-TCP loading, which was measured via micro-CT (µCT) analysis. Furthermore, µCT analyses revealed the distribution of aggregated β-TCP particles in between the various PLA fibre layers of the scaffold. The compressive modulus properties of the scaffolds increased from 66 MPa to 83 MPa and the compressive strength properties decreased from 67 MPa to 41 MPa for the 30 wt % β-TCP content scaffold. The scaffolds produced were observed to change into a soft and flexible form which demonstrated shape recovery properties after immersion in phosphate buffered saline (PBS) media at 37 °C for 24 h. The cytocompatibility studies (using MG-63 human osteosarcoma cell line) revealed preferential cell proliferation along the longitudinal direction of the fibres as compared to the control tissue culture plastic. The manufacturing process highlighted above reveals a simple process for inducing controlled cell alignment and varying porosity features within tubular scaffolds for potential tissue engineering applications. PMID:26184328

  4. Tubular Scaffold with Shape Recovery Effect for Cell Guide Applications.

    PubMed

    Hossain, Kazi M Zakir; Zhu, Chenkai; Felfel, Reda M; Sharmin, Nusrat; Ahmed, Ifty

    2015-07-10

    Tubular scaffolds with aligned polylactic acid (PLA) fibres were fabricated for cell guide applications by immersing rolled PLA fibre mats into a polyvinyl acetate (PVAc) solution to bind the mats. The PVAc solution was also mixed with up to 30 wt % β-tricalcium phosphate (β-TCP) content. Cross-sectional images of the scaffold materials obtained via scanning electron microscopy (SEM) revealed the aligned fibre morphology along with a significant number of voids in between the bundles of fibres. The addition of β-TCP into the scaffolds played an important role in increasing the void content from 17.1% to 25.3% for the 30 wt % β-TCP loading, which was measured via micro-CT (µCT) analysis. Furthermore, µCT analyses revealed the distribution of aggregated β-TCP particles in between the various PLA fibre layers of the scaffold. The compressive modulus properties of the scaffolds increased from 66 MPa to 83 MPa and the compressive strength properties decreased from 67 MPa to 41 MPa for the 30 wt % β-TCP content scaffold. The scaffolds produced were observed to change into a soft and flexible form which demonstrated shape recovery properties after immersion in phosphate buffered saline (PBS) media at 37 °C for 24 h. The cytocompatibility studies (using MG-63 human osteosarcoma cell line) revealed preferential cell proliferation along the longitudinal direction of the fibres as compared to the control tissue culture plastic. The manufacturing process highlighted above reveals a simple process for inducing controlled cell alignment and varying porosity features within tubular scaffolds for potential tissue engineering applications.

  5. Fiber coating method

    DOEpatents

    Corman, Gregory Scot

    2001-01-01

    A coating is applied to reinforcing fibers arranged into a tow by coaxially aligning the tow with an adjacent separation layer and winding or wrapping the tow and separation layer onto a support structure in an interleaved manner so that the separation layer separates a wrap of the tow from an adjacent wrap of the tow. A coating can then be uniformly applied to the reinforcing fibers without defects caused by fiber tow to fiber tow contact. The separation layer can be a carbon fiber veil.

  6. Fiber coating method

    DOEpatents

    Corman, Gregory Scot

    2003-04-15

    A coating is applied to reinforcing fibers arranged into a tow by coaxially aligning the tow with an adjacent separation layer and winding or wrapping the tow and separation layer onto a support structure in an interleaved manner so that the separation layer separates a wrap of the tow from an adjacent wrap of the tow. A coating can then be uniformly applied to the reinforcing fibers without defects caused by fiber tow to fiber tow contact. The separation layer can be a carbon fiber veil.

  7. Preparation of scaffolds based on bulky sutures for cell therapy

    NASA Astrophysics Data System (ADS)

    Park, Young Hwan; Chun, Heung Jae; Kim, Sung Jin

    2012-04-01

    Scaffold for cell therapy was prepared with poly (lactide-co-glicolide, PLA/PGA (10:90). By using melt-spinning and draw texturing process, we could prepare microfibrous bulky suture which had heterogeneous macropore. Microfibrous structure has great potentiality as biomimicking architecture for cell growth and maintaining cell functions. The result of cell seeding showed that pore size, pore distribution, and fiber fineness of sutures were suitable as a biocompatible scaffold in vitro for NIH 3T3 Fibroblast cell. Also, we expect that prepared scaffold for cell-therapy will provide numerous benefits as a noninvasive alternative for tissue engineering applications.

  8. Preparation of scaffolds based on bulky sutures for cell therapy

    NASA Astrophysics Data System (ADS)

    Park, Young Hwan; Chun, Heung Jae; Kim, Sung Jin

    2011-11-01

    Scaffold for cell therapy was prepared with poly (lactide-co-glicolide, PLA/PGA (10:90). By using melt-spinning and draw texturing process, we could prepare microfibrous bulky suture which had heterogeneous macropore. Microfibrous structure has great potentiality as biomimicking architecture for cell growth and maintaining cell functions. The result of cell seeding showed that pore size, pore distribution, and fiber fineness of sutures were suitable as a biocompatible scaffold in vitro for NIH 3T3 Fibroblast cell. Also, we expect that prepared scaffold for cell-therapy will provide numerous benefits as a noninvasive alternative for tissue engineering applications.

  9. Electrospun cartilage-derived matrix scaffolds for cartilage tissue engineering.

    PubMed

    Garrigues, N William; Little, Dianne; Sanchez-Adams, Johannah; Ruch, David S; Guilak, Farshid

    2014-11-01

    Macroscale scaffolds created from cartilage-derived matrix (CDM) demonstrate chondroinductive or chondro-inductive properties, but many fabrication methods do not allow for control of nanoscale architecture. In this regard, electrospun scaffolds have shown significant promise for cartilage tissue engineering. However, nanofibrous materials generally exhibit a relatively small pore size and require techniques such as multilayering or the inclusion of sacrificial fibers to enhance cellular infiltration. The objectives of this study were (1) to compare multilayer to single-layer electrospun poly(ɛ-caprolactone) (PCL) scaffolds for cartilage tissue engineering, and (2) to determine whether incorporation of CDM into the PCL fibers would enhance chondrogenesis by human adipose-derived stem cells (hASCs). PCL and PCL-CDM scaffolds were prepared by sequential collection of 60 electrospun layers from the surface of a grounded saline bath into a single scaffold, or by continuous electrospinning onto the surface of a grounded saline bath and harvest as a single-layer scaffold. Scaffolds were seeded with hASCs and evaluated over 28 days in culture. The predominant effects on hASCs of incorporation of CDM into scaffolds were to stimulate sulfated glycosaminoglycan synthesis and COL10A1 gene expression. Compared with single-layer scaffolds, multilayer scaffolds enhanced cell infiltration and ACAN gene expression. However, compared with single-layer constructs, multilayer PCL constructs had a much lower elastic modulus, and PCL-CDM constructs had an elastic modulus approximately 1% that of PCL constructs. These data suggest that multilayer electrospun constructs enhance homogeneous cell seeding, and that the inclusion of CDM stimulates chondrogenesis-related bioactivity.

  10. Understanding anisotropy and architecture in ice-templated biopolymer scaffolds.

    PubMed

    Pawelec, K M; Husmann, A; Best, S M; Cameron, R E

    2014-04-01

    Biopolymer scaffolds have great therapeutic potential within tissue engineering due to their large interconnected porosity and biocompatibility. Using an ice-templated technique, where collagen is concentrated into a porous network by ice nucleation and growth, scaffolds with anisotropic pore architecture can be created, mimicking natural tissues like cardiac muscle and bone. This paper describes a systematic set of experiments undertaken to understand the effect of local temperatures on architecture in ice-templated biopolymer scaffolds. The scaffolds within this study were at least 10mm in all dimensions, making them applicable to critical sized defects for biomedical applications. It was found that monitoring the local freezing behavior within the slurry was critical to predicting scaffold structure. Aligned porosity was produced only in parts of the slurry volume which were above the equilibrium freezing temperature (0°C) at the time when nucleation first occurs in the sample as a whole. Thus, to create anisotropic scaffolds, local slurry cooling rates must be sufficiently different to ensure that the equilibrium freezing temperature is not reached throughout the slurry at nucleation. This principal was valid over a range of collagen slurries, demonstrating that by monitoring the temperature within slurry during freezing, scaffold anisotropy with ice-templated scaffolds can be predicted.

  11. Cell proliferation and migration in silk fibroin 3D scaffolds.

    PubMed

    Mandal, Biman B; Kundu, Subhas C

    2009-05-01

    Pore architecture in 3D polymeric scaffolds is known to play a critical role in tissue engineering as it provides the vital framework for the seeded cells to organize into a functioning tissue. In this report, we investigated the effects of different freezing temperature regimes on silk fibroin protein 3D scaffold pore microstructure. The fabricated scaffolds using freeze-dry technique were used as a 3D model to monitor cell proliferation and migration. Pores of 200-250microm diameter were formed by slow cooling at temperatures of -20 and -80 degrees C but were found to be limited in porosity and pore interconnectivity as observed through scanning electron microscopic images. In contrast, highly interconnected pores with 96% porosity were observed when silk solutions were rapidly frozen at -196 degrees C. A detailed study was conducted to assess the affect of pore size, porosity and interconnectivity on human dermal fibroblast cell proliferation and migration on these 3D scaffolds using confocal microscopy. The cells were observed to migrate within the scaffold interconnectivities and were found to reach scaffold periphery within 28 days of culture. Confocal images further confirmed normal cell attachment and alignment of actin filaments within the porous scaffold matrix with well-developed nuclei. This study indicates rapid freeze-drying technique as an alternative method to fabricate highly interconnected porous scaffolds for developing functional 3D silk fibroin matrices for potential tissue engineering, biomedical and biotechnological applications.

  12. Production and cross-sectional characterization of aligned co-electrospun hollow microfibrous bulk assemblies

    PubMed Central

    Zhou, Feng-Lei; Parker, Geoff J.M.; Eichhorn, Stephen J.; Hubbard Cristinacce, Penny L.

    2015-01-01

    The development of co-electrospun (co-ES) hollow microfibrous assemblies of an appreciable thickness is critical for many practical applications, including filtration membranes and tissue-mimicking scaffolds. In this study, thick uniaxially aligned hollow microfibrous assemblies forming fiber bundles and strips were prepared by co-ES of polycaprolactone (PCL) and polyethylene oxide (PEO) as shell and core materials, respectively. Hollow microfiber bundles were deposited on a fixed rotating disc, which resulted in non-controllable cross-sectional shapes on a macroscopic scale. In comparison, fiber strips were produced with tuneable thickness and width by additionally employing an x–y translation stage in co-ES. Scanning electron microscopy (SEM) images of cross-sections of fiber assemblies were analyzed to investigate the effects of production time (from 0.5 h to 12 h), core flow rate (from 0.8 mL/h to 2.0 mL/h) and/or translation speed (from 0.2 mm/s to 5 mm/s) on the pores and porosity. We observed significant changes in pore size and shape with core flow rate but the influence of production time varied; five strips produced under the same conditions had reasonably good size and porosity reproducibility; pore sizes didn't vary significantly from strip bottom to surface, although the porosity gradually decreased and then returned to the initial level. PMID:26702249

  13. Nanostructured polymer scaffolds for tissue engineering and regenerative medicine.

    PubMed

    Smith, I O; Liu, X H; Smith, L A; Ma, P X

    2009-01-01

    The structural features of tissue engineering scaffolds affect cell response and must be engineered to support cell adhesion, proliferation and differentiation. The scaffold acts as an interim synthetic extracellular matrix (ECM) that cells interact with prior to forming a new tissue. In this review, bone tissue engineering is used as the primary example for the sake of brevity. We focus on nanofibrous scaffolds and the incorporation of other components including other nanofeatures into the scaffold structure. Since the ECM is comprised in large part of collagen fibers, between 50 and 500 nm in diameter, well-designed nanofibrous scaffolds mimic this structure. Our group has developed a novel thermally induced phase separation (TIPS) process in which a solution of biodegradable polymer is cast into a porous scaffold, resulting in a nanofibrous pore-wall structure. These nanoscale fibers have a diameter (50-500 nm) comparable to those collagen fibers found in the ECM. This process can then be combined with a porogen leaching technique, also developed by our group, to engineer an interconnected pore structure that promotes cell migration and tissue ingrowth in three dimensions. To improve upon efforts to incorporate a ceramic component into polymer scaffolds by mixing, our group has also developed a technique where apatite crystals are grown onto biodegradable polymer scaffolds by soaking them in simulated body fluid (SBF). By changing the polymer used, the concentration of ions in the SBF and by varying the treatment time, the size and distribution of these crystals are varied. Work is currently being done to improve the distribution of these crystals throughout three-dimensional scaffolds and to create nanoscale apatite deposits that better mimic those found in the ECM. In both nanofibrous and composite scaffolds, cell adhesion, proliferation and differentiation improved when compared to control scaffolds. Additionally, composite scaffolds showed a decrease in

  14. Using mathematical modeling to control topographical properties of poly (ɛ-caprolactone) melt electrospun scaffolds

    NASA Astrophysics Data System (ADS)

    Ko, J.; Bhullar, S. K.; Mohtaram, N. K.; Willerth, S. M.; Jun, M. B. G.

    2014-06-01

    Melt electrospinning creates fibrous scaffolds using direct deposition. The main challenge of melt electrospinning is controlling the topography of the scaffolds for tissue engineering applications. Mathematical modeling enables a better understanding of the parameters that determine the topography of scaffolds. The objective of this study is to build two types of mathematical models. First, we modeled the melt electrospinning process by incorporating parameters such as nozzle size, counter electrode distance and applied voltage that influence fiber diameter and scaffold porosity. Our second model describes the accumulation of the extruded microfibers on flat and round surfaces using data from the microfiber modeling. These models were validated through the use of experimentally obtained data. Scanning electron microscopy (SEM) was used to image the scaffolds and the fiber diameters were measured using Quartz-PCI Image Management Systems® in SEM to measure scaffold porosity.

  15. Effect of hierarchically aligned fibrin hydrogel in regeneration of spinal cord injury demonstrated by tractography: A pilot study

    PubMed Central

    Zhang, Zhenxia; Yao, Shenglian; Xie, Sheng; Wang, Xiumei; Chang, Feiyan; Luo, Jie; Wang, Jingming; Fu, Jun

    2017-01-01

    Some studies have reported that scaffold or cell-based transplantation may improve functional recovery following SCI, but no imaging information regarding regeneration has been provided to date. This study used tractography to show the regenerating process induced by a new biomaterial-aligned fibrin hydrogel (AFG). A total of eight canines subjected to SCI procedures were assigned to the control or the AFG group. AFG was implanted into the SCI lesion immediately after injury in 5 canines. A follow-up was performed at 12 weeks to evaluate the therapeutic effect including the hindlimb functional recovery, anisotropy and continuity of fibers on tractography. Using tractography, we found new fibers running across the SCI in three canines of the AFG group. Further histological examination confirmed limited glial scarring and regenerated nerve fibers in the lesions. Moreover, Repeated Measures Analysis revealed a significantly different change in fractional anisotropy (FA) between the two groups during the follow-up interval. An increase in FA during the post injury time interval was detected in the AFG group, indicating a beneficial effect of AFG in the rehabilitation of injured axons. Using tractography, AFG was suggested to be helpful in the restoration of fibers in SCI lesions, thus leading to promoted functional recovery. PMID:28067245

  16. Polymeric scaffolds in tissue engineering: a literature review.

    PubMed

    Jafari, Maissa; Paknejad, Zahrasadat; Rad, Maryam Rezai; Motamedian, Saeed Reza; Eghbal, Mohammad Jafar; Nadjmi, Nasser; Khojasteh, Arash

    2017-02-01

    The tissue engineering scaffold acts as an extracellular matrix that interacts to the cells prior to forming new tissues. The chemical and structural characteristics of scaffolds are major concerns in fabricating of ideal three-dimensional structure for tissue engineering applications. The polymer scaffolds used for tissue engineering should possess proper architecture and mechanical properties in addition to supporting cell adhesion, proliferation, and differentiation. Much research has been done on the topic of polymeric scaffold properties such as surface topographic features (roughness and hydrophilicity) and scaffold microstructures (pore size, porosity, pore interconnectivity, and pore and fiber architectures) that influence the cell-scaffold interactions. In this review, efforts were given to evaluate the effect of both chemical and structural characteristics of scaffolds on cell behaviors such as adhesion, proliferation, migration, and differentiation. This review would provide the fundamental information which would be beneficial for scaffold design in future. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 431-459, 2017.

  17. A structural model for the flexural mechanics of nonwoven tissue engineering scaffolds.

    PubMed

    Engelmayr, George C; Sacks, Michael S

    2006-08-01

    The development of methods to predict the strength and stiffness of biomaterials used in tissue engineering is critical for load-bearing applications in which the essential functional requirements are primarily mechanical. We previously quantified changes in the effective stiffness (E) of needled nonwoven polyglycolic acid (PGA) and poly-L-lactic acid (PLLA) scaffolds due to tissue formation and scaffold degradation under three-point bending. Toward predicting these changes, we present a structural model for E of a needled nonwoven scaffold in flexure. The model accounted for the number and orientation of fibers within a representative volume element of the scaffold demarcated by the needling process. The spring-like effective stiffness of the curved fibers was calculated using the sinusoidal fiber shapes. Structural and mechanical properties of PGA and PLLA fibers and PGA, PLLA, and 50:50 PGA/PLLA scaffolds were measured and compared with model predictions. To verify the general predictive capability, the predicted dependence of E on fiber diameter was compared with experimental measurements. Needled nonwoven scaffolds were found to exhibit distinct preferred (PD) and cross-preferred (XD) fiber directions, with an E ratio (PD/XD) of approximately 3:1. The good agreement between the predicted and experimental dependence of E on fiber diameter (R2 = 0.987) suggests that the structural model can be used to design scaffolds with E values more similar to native soft tissues. A comparison with previous results for cell-seeded scaffolds (Engelmayr, G. C., Jr., et al., 2005, Biomaterials, 26(2), pp. 175-187) suggests, for the first time, that the primary mechanical effect of collagen deposition is an increase in the number of fiber-fiber bond points yielding effectively stiffer scaffold fibers. This finding indicated that the effects of tissue deposition on needled nonwoven scaffold mechanics do not follow a rule-of-mixtures behavior. These important results underscore

  18. The History of GalaFLEX P4HB Scaffold

    PubMed Central

    Williams, Simon F.; Martin, David P.; Moses, Arikha C.

    2016-01-01

    The GalaFLEX Scaffold (Galatea Surgical, Inc., Lexington, MA) for plastic and reconstructive surgery belongs to a new generation of products for soft tissue reinforcement made from poly-4-hydroxybutyrate (P4HB). Other members of this new family of products include MonoMax Suture (Aesculap AG, Tuttlingen, Germany) for soft tissue approximation, BioFiber Scaffold (Tornier, Inc., Edina, MN) for tendon repair, and Phasix Mesh (C.R. Bard, Inc., Murray Hill, NJ) for hernia repair. Each of these fully resorbable products provides prolonged strength retention, typically 50% to 70% strength retention at 12 weeks, and facilitates remodeling in vivo to provide a strong, lasting repair. P4HB belongs to a naturally occurring class of biopolymers and fibers made from it are uniquely strong, flexible, and biocompatible. GalaFLEX Scaffold is comprised of high-strength, resorbable P4HB monofilament fibers. It is a knitted macroporous scaffold intended to elevate, reinforce, and repair soft tissue. The scaffold acts as a lattice for new tissue growth, which is rapidly vascularized and becomes fully integrated with adjacent tissue as the fibers resorb. In this review, we describe the development of P4HB, its production, properties, safety, and biocompatibility of devices made from P4HB. Early clinical results and current clinical applications of products made from P4HB are also discussed. The results of post-market clinical studies evaluating the GalaFLEX Scaffold in rhytidectomy and cosmetic breast surgery demonstrate that the scaffold can reinforce lifted soft tissue, resulting in persistent surgical results in the face and neck at one year, and provide lower pole stability after breast lift at one year. PMID:27697885

  19. Effective Mechanical Properties of Fuzzy Fiber Composites

    DTIC Science & Technology

    2012-03-16

    fibers ’’. Numerical examples of compositesmade of epoxy resin, carbonfibers and carbon nanotubes are presented and the impact of the carbon nanotubes...been developed for carbon fibers [52,29,42,64,62], ceramic fibers [60,9] and glass fibers [2]. Modeling of composites containing CNTs has also...Herein we examine composites where carbon fibers , coated with radially aligned carbon nanotubes, are embedded in a matrix. These enhanced carbon fibers

  20. Exploring cellular adhesion and differentiation in a micro-/nano-hybrid polymer scaffold.

    PubMed

    Cheng, Ke; Kisaalita, William S

    2010-01-01

    Polymer scaffolds play an important role in three dimensional (3-D) cell culture and tissue engineering. To best mimic the archiecture of natural extracellular matrix (ECM), a nano-fibrous and micro-porous combined (NFMP) scaffold was fabricated by combining phase separation and particulate leaching techniques. The NFMP scaffold possesses architectural features at two levels, including the micro-scale pores and nano-scale fibers. To evaluate the advantages of micro/nano combination, control scaffolds with only micro-pores or nano-fibers were fabricated. Cell grown in NFMP and control scaffolds were characterized with respect to morphology, proliferation rate, diffentiation and adhesion. The NFMP scaffold combined the advantages of micro- and nano-scale structures. The NFMP scaffold nano-fibers promoted neural differentiation and induced "3-D matrix adhesion", while the NFMP scaffold micro-pores facilitated cell infiltration. This study represents a systematic comparison of cellular activities on micro-only, nano-only and micro/nano combined scaffolds, and demonstrates the unique advantages of the later.

  1. BBMap: A Fast, Accurate, Splice-Aware Aligner

    SciTech Connect

    Bushnell, Brian

    2014-03-17

    Alignment of reads is one of the primary computational tasks in bioinformatics. Of paramount importance to resequencing, alignment is also crucial to other areas - quality control, scaffolding, string-graph assembly, homology detection, assembly evaluation, error-correction, expression quantification, and even as a tool to evaluate other tools. An optimal aligner would greatly improve virtually any sequencing process, but optimal alignment is prohibitively expensive for gigabases of data. Here, we will present BBMap [1], a fast splice-aware aligner for short and long reads. We will demonstrate that BBMap has superior speed, sensitivity, and specificity to alternative high-throughput aligners bowtie2 [2], bwa [3], smalt, [4] GSNAP [5], and BLASR [6].

  2. Biodegradable scaffolds designed to mimic fascia-like properties for the treatment of pelvic organ prolapse and stress urinary incontinence.

    PubMed

    Roman, Sabiniano; Mangir, Naside; Bissoli, Julio; Chapple, Christopher R; MacNeil, Sheila

    2016-05-01

    There is an urgent clinical need for better synthetic materials to be used in surgical support of the pelvic floor. The aim of the current study was to construct biodegradable synthetic scaffolds that mimic the three-dimensional architecture of human fascia, which can integrate better into host tissues both mechanically and biologically. Therefore, four different polylactic acid (PLA) scaffolds with various degrees of fibre alignment were electrospun by modifying the electrospinning parameters. Physical and mechanical properties were assessed using a BOSE electroforce tensiometer. The attachment, viability and extracellular matrix production of adipose-derived stem cells cultured on the polylactic acid scaffolds were evaluated. The bulk density of the scaffolds decreased as the proportion of aligned fibres increased. Scaffolds became stronger and stiffer with increasing amounts of aligned fibres as measured along the axis parallel to the fibre alignment. In addition, more total collagen was produced on scaffolds with aligned fibres and was organised in the direction of the aligned fibres. In conclusion, the electrospinning technique can be easily modified to develop biodegradable scaffolds with a spectrum of mechanical properties allowing extracellular matrix organisation towards human-like fascia.

  3. Evaluation of the growth of chondrocytes and osteoblasts seeded into precision scaffolds fabricated by fused deposition manufacturing.

    PubMed

    Hsu, Shan-hui; Yen, Hung-Jen; Tseng, Ching-Shiow; Cheng, Chia-Sheng; Tsai, Ching-Lin

    2007-02-01

    In this study, fused deposition manufacturing (FDM) was utilized to fabricate the precision scaffolds for cartilage and bone regeneration. Cell seeding into such scaffolds was evaluated. For poly(D,l-lactide) (PLA) scaffolds used for cartilage regeneration, the structure with larger inner space, four direction stacking (4D) and small interval of fibers were better. Chondrocyte proliferated well with matrix accumulation in precision scaffolds coated with type II collagen at 4 weeks of in vitro culture. The seeding efficiency of osteoblasts in most polycaprolactone (PCL) scaffolds used for bone regeneration could arrive 50% of original cell seeding density, and the amount of cells in scaffolds increased to double fold after 2 weeks of in vitro culture. The histological cross-section also revealed proliferation and mineralization of osteoblasts among the PCL fibers. The results indicated that the highly porous and interconnected structure of precision scaffolds could benefit cell ingrowth.

  4. A collagen/smooth muscle cell-incorporated elastic scaffold for tissue-engineered vascular grafts.

    PubMed

    Park, In Su; Kim, Sang-Heon; Kim, Young Ha; Kim, Ik Hwan; Kim, Soo Hyun

    2009-01-01

    Biodegradable tubular scaffolds have been developed for vascular graft application. This study was focused to improve the adhesion and proliferation of vascular smooth muscle cells (SMCs) in a tubular scaffold. Tubular scaffolds (ID 4 mm, OD 6 mm) were fabricated from a biodegradable elastic polymer, poly(L-lactide-co-epsilon-caprolactone) (PLCL) (50:50, M(n) 1.58 x 10(5)), by an extrusion/particulate leaching method. SMCs suspended in a collagen solution were infiltrated in tubular PLCL scaffolds under vacuum and incubated for 1 h at 37 degrees C to form a collagenous gel. Results from SEM image analysis showed that collagen was infiltrated into the inside of the scaffolds. Cell adhesion and proliferation rate increased in collagen/SMC-incorporated tubular PLCL scaffolds as compared with the scaffolds in which only SMCs were seeded. From SEM image and histological analysis, we further found that SMCs grew on the inside as well as on the surface of collagen/SMCs-incorporated scaffolds and the cells continued to grow as a monolayer on collagen fibers. In particular, cell proliferation and elastin contents were the highest in a PLCL scaffold with 50-100 microm pore size than any other scaffolds used in this experiment. A collagen/SMC-incorporated PLCL scaffold may support SMC growth and functions and can be used as a scaffold for tissue engineering to facilitate small-diameter vascular-tissue formation.

  5. PGS:Gelatin Nanofibrous Scaffolds with Tunable Mechanical and Structural Properties for Engineering Cardiac Tissues

    PubMed Central

    Kharaziha, Mahshid; Nikkhah, Mehdi; Shin, Su-Ryon; Annabi, Nasim; Masoumi, Nafiseh; Gaharwar, Akhilesh K.; Camci-Unal, Gulden; Khademhosseini, Ali

    2013-01-01

    A significant challenge in cardiac tissue engineering is the development of biomimetic grafts that can potentially promote myocardial repair and regeneration. A number of approaches have used engineered scaffolds to mimic the architecture of the native myocardium tissue and precisely regulate cardiac cell functions. However previous attempts have not been able to simultaneously recapitulate chemical, mechanical, and structural properties of the myocardial extracellular matrix (ECM). In this study, we utilized an electrospinning approach to fabricate elastomeric biodegradable poly(glycerol-sebacate) (PGS):gelatin scaffolds with a wide range of chemical composition, stiffness and anisotropy. Our findings demonstrated that through incorporation of PGS, it is possible to create nanofibrous scaffolds with well-defined anisotropy that mimics the left ventricular myocardium architecture. Furthermore, we studied attachment, proliferation, differentiation and alignment of neonatal rat cardiac fibroblast cells (CFs) as well as protein expression, alignment, and contractile function of cardiomyocyte (CMs) on PGS:gelatin scaffolds with variable amount of PGS. Notably, aligned nanofibrous scaffold, consisting of 33 wt. % PGS, induced optimal synchronous contractions of CMs while significantly enhanced cellular alignment. Overall, our study suggests that the aligned nanofibrous PGS:gelatin scaffold support cardiac cell organization, phenotype and contraction and could potentially be used to develop clinically relevant constructs for cardiac tissue engineering. PMID:23747008

  6. PGS:Gelatin nanofibrous scaffolds with tunable mechanical and structural properties for engineering cardiac tissues.

    PubMed

    Kharaziha, Mahshid; Nikkhah, Mehdi; Shin, Su-Ryon; Annabi, Nasim; Masoumi, Nafiseh; Gaharwar, Akhilesh K; Camci-Unal, Gulden; Khademhosseini, Ali

    2013-09-01

    A significant challenge in cardiac tissue engineering is the development of biomimetic grafts that can potentially promote myocardial repair and regeneration. A number of approaches have used engineered scaffolds to mimic the architecture of the native myocardium tissue and precisely regulate cardiac cell functions. However, previous attempts have not been able to simultaneously recapitulate chemical, mechanical, and structural properties of the myocardial extracellular matrix (ECM). In this study, we utilized an electrospinning approach to fabricate elastomeric biodegradable poly(glycerol sebacate) (PGS):gelatin nanofibrous scaffolds with a wide range of chemical composition, stiffness and anisotropy. Our findings demonstrated that through incorporation of PGS, it is possible to create nanofibrous scaffolds with well-defined anisotropy that mimic the left ventricular myocardium architecture. Furthermore, we studied attachment, proliferation, differentiation and alignment of neonatal rat cardiac fibroblast cells (CFs) as well as protein expression, alignment, and contractile function of cardiomyocyte (CMs) on PGS:gelatin scaffolds with variable amount of PGS. Notably, aligned nanofibrous scaffold, consisting of 33 wt. % PGS, induced optimal synchronous contractions of CMs while significantly enhanced cellular alignment. Overall, our study suggests that the aligned nanofibrous PGS:gelatin scaffold support cardiac cell organization, phenotype and contraction and could potentially be used to develop clinically relevant constructs for cardiac tissue engineering.

  7. Nanoclay-Enriched Poly(ɛ-caprolactone) Electrospun Scaffolds for Osteogenic Differentiation of Human Mesenchymal Stem Cells

    PubMed Central

    Gaharwar, Akhilesh K.; Mukundan, Shilpaa; Karaca, Elif; Dolatshahi-Pirouz, Alireza; Patel, Alpesh; Rangarajan, Kaushik; Mihaila, Silvia M.; Iviglia, Giorgio; Zhang, Hongbin

    2014-01-01

    Musculoskeletal tissue engineering aims at repairing and regenerating damaged tissues using biological tissue substitutes. One approach to achieve this aim is to develop osteoconductive scaffolds that facilitate the formation of functional bone tissue. We have fabricated nanoclay-enriched electrospun poly(ɛ-caprolactone) (PCL) scaffolds for osteogenic differentiation of human mesenchymal stem cells (hMSCs). A range of electrospun scaffolds is fabricated by varying the nanoclay concentrations within the PCL scaffolds. The addition of nanoclay decreases fiber diameter and increases surface roughness of electrospun fibers. The enrichment of PCL scaffold with nanoclay promotes in vitro biomineralization when subjected to simulated body fluid (SBF), indicating bioactive characteristics of the hybrid scaffolds. The degradation rate of PCL increases due to the addition of nanoclay. In addition, a significant increase in crystallization temperature of PCL is also observed due to enhanced surface interactions between PCL and nanoclay. The effect of nanoclay on the mechanical properties of electrospun fibers is also evaluated. The feasibility of using nanoclay-enriched PCL scaffolds for tissue engineering applications is investigated in vitro using hMSCs. The nanoclay-enriched electrospun PCL scaffolds support hMSCs adhesion and proliferation. The addition of nanoclay significantly enhances osteogenic differentiation of hMSCs on the electrospun scaffolds as evident by an increase in alkaline phosphates activity of hMSCs and higher deposition of mineralized extracellular matrix compared to PCL scaffolds. Given its unique bioactive characteristics, nanoclay-enriched PCL fibrous scaffold may be used for musculoskeletal tissue engineering. PMID:24842693

  8. Hydroxyapatite (HA) bone scaffolds with controlled macrochannel pores.

    PubMed

    Bae, Chang-Jun; Kim, Hae-Won; Koh, Young-Hag; Kim, Hyoun-Ee

    2006-06-01

    Hydroxyapatite (HA) macrochanneled porous scaffolds, with a controlled pore structure, were fabricated via a combination of the extrusion and lamination processes. The scaffold was architectured by aligning and laminating the extruded HA and carbon filaments. The macrochannel pores were formed by removing the carbon filaments after thermal treatments (binder removal and sintering). The porosity of the scaffolds was varied between 48 and 73% with a controlled pore size of approximately 450 microm, by adjusting the fractions of HA and carbon filaments. As the porosity was increased from 48 to 73%, the compressive strength decreased from 11.5 to 3.2 MPa. However, the osteoblast-like cell responses on the scaffold, such as the proliferation rate and alkaline phosphatase (ALP) activity, were significantly enhanced as the porosity was increased.

  9. TISSUE-TO-CELLULAR LEVEL DEFORMATION COUPLING IN CELL-MICROINTEGRATED ELASTOMERIC SCAFFOLDS

    PubMed Central

    Stella, John A.; Liao, Jun; Hong, Yi; Merryman, W. David; Wagner, William R.; Sacks, Michael S.

    2008-01-01

    In engineered tissues we are challenged to reproduce extracellular matrix and cellular deformation coupling that occurs within native tissues, which is a meso-micro scale phenomenon that profoundly affects tissue growth and remodeling. With our ability to electrospin polymer fiber scaffolds while simultaneously electrospraying viable cells, we are provided with a unique platform to investigate cellular deformations within a three dimensional elastomeric fibrous scaffold. Scaffold specimens micro-integrated with vascular smooth muscle cells were subjected to controlled biaxial stretch with 3D cellular deformations and local fiber micro-architecture simultaneously quantified. We demonstrated that the local fiber geometry followed an affine behavior, so that it could be predicted by macro scaffold deformations. However, local cellular deformations depended non-linearly on changes in fiber microarchitecture and ceased at large strains where the scaffold fibers completely straightened. Thus, local scaffold microstructural changes induced by macro-level applied strain dominated cellular deformations, so that monotonic increases in scaffold strain do not necessitate similar levels of cellular deformation. This result has fundamental implications when attempting to elucidate the events of de-novo tissue development and remodeling in engineered tissues, which are thought to depend substantially on cellular deformations. PMID:18472154

  10. Semi-interpenetrating network (sIPN) gelatin nanofiber scaffolds for oral mucosal drug delivery.

    PubMed

    Aduba, Donald C; Hammer, Jeremy A; Yuan, Quan; Yeudall, W Andrew; Bowlin, Gary L; Yang, Hu

    2013-05-01

    The oral mucosa is a promising absorption site for drug administration because it is permeable, highly vascularized and allows for ease of administration. Nanofiber scaffolds for local or systemic drug delivery through the oral mucosa, however, have not been fully explored. In this work, we fabricated electrospun gelatin nanofiber scaffolds for oral mucosal drug delivery. To improve structural stability of the electrospun gelatin scaffolds and allow non-invasive incorporation of therapeutics into the scaffold, we employed photo-reactive polyethylene glycol diacrylate (PEG-DA575, 575 gmol(-1)) as a cross-linker to stabilize the scaffold by forming semi-interpenetrating network gelatin nanofiber scaffolds (sIPN NSs), during which cross-linker concentration was varied (1×, 2×, 4× and 8×). The results showed that electrospun gelatin nanofiber scaffolds after being cross-linked with PEG-DA575 (i.e. sIPN NS1×, 2×, 4× and 8×) retained fiber morphology and possessed improved structural stability. A series of structural parameters and properties of the cross-linked electrospun gelatin scaffolds were systematically characterized in terms of morphology, fiber diameter, mechanical properties, porosity, swelling and degradation. Mucin absorption onto sIPN NS4× was also confirmed, indicating this scaffold possessed greatest mucoadhesion properties among those tested. Slow release of nystatin, an anti-fungal reagent, from the sIPN gelatin nanofiber scaffold was demonstrated.

  11. Development of porous scaffolds for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Ramay, Hassna Rehman

    In bone tissue engineering, biodegradable scaffolds are used as a temporary biological and mechanical support for new tissue growth. A scaffold must have good biocompatibility, controllable degradation rate, and enough mechanical strength to support bone cell attachment, differentiation, and proliferation as it gradually degrades and finally is completely replaced by new bone tissues. Biological studies and clinical practices have established that a three-dimensional interconnected porous structure is necessary to allow cell attachment, proliferation, and differentiation, and to provide pathways for biofluids. However, the mechanical strength of a material generally decreases as increasing porosity. The conflicting interests between biological and mechanical requirements thus pose a challenge in developing porous scaffolds for load-bearing bone tissue engineering. Two types of ceramic scaffolds, (1) Hydroxaypatite and (2) Hydroxaypatite/tricalcium phosphate, are prepared in this study utilizing a novel technique that combines the gel casting and polymer sponge methods. This technique provides better control over material microstructure and can produce scaffolds with enhanced mechanical toughness and strength. The hydroxyapatite scaffolds prepared by this technique have an open, uniform and interconnected porous structure (˜porosity = 76%) with compressive modulus of 7 GPa, comparable to that of cortical bone, and compressive strength of 5 MPa, comparable to that of cancellous bone. The second type of ceramic scaffold is a biphasic nano composite with tricalcium phosphate as the main matrix reinforced with hydroxyapatite (HA) nano-fibers. The porous scaffold attained a compressive strength of 9.6 MPa (˜porosity = 73%), comparable to the high-end value of cancellous bone. The toughness of the scaffold increased from 1.00 to 1.72 kN/m (˜porosity = 73%), as the addition of HA nano-fibers increased up to 5 wt.%. Polymer scaffolds are prepared using a solid

  12. Design, construction and mechanical testing of digital 3D anatomical data-based PCL-HA bone tissue engineering scaffold.

    PubMed

    Yao, Qingqiang; Wei, Bo; Guo, Yang; Jin, Chengzhe; Du, Xiaotao; Yan, Chao; Yan, Junwei; Hu, Wenhao; Xu, Yan; Zhou, Zhi; Wang, Yijin; Wang, Liming

    2015-01-01

    The study aims to investigate the techniques of design and construction of CT 3D reconstructional data-based polycaprolactone (PCL)-hydroxyapatite (HA) scaffold. Femoral and lumbar spinal specimens of eight male New Zealand white rabbits were performed CT and laser scanning data-based 3D printing scaffold processing using PCL-HA powder. Each group was performed eight scaffolds. The CAD-based 3D printed porous cylindrical stents were 16 piece × 3 groups, including the orthogonal scaffold, the Pozi-hole scaffold and the triangular hole scaffold. The gross forms, fiber scaffold diameters and porosities of the scaffolds were measured, and the mechanical testing was performed towards eight pieces of the three kinds of cylindrical scaffolds, respectively. The loading force, deformation, maximum-affordable pressure and deformation value were recorded. The pore-connection rate of each scaffold was 100 % within each group, there was no significant difference in the gross parameters and micro-structural parameters of each scaffold when compared with the design values (P > 0.05). There was no significant difference in the loading force, deformation and deformation value under the maximum-affordable pressure of the three different cylinder scaffolds when the load was above 320 N. The combination of CT and CAD reverse technology could accomplish the design and manufacturing of complex bone tissue engineering scaffolds, with no significant difference in the impacts of the microstructures towards the physical properties of different porous scaffolds under large load.

  13. Improved fabrication of melt electrospun tissue engineering scaffolds using direct writing and advanced electric field control.

    PubMed

    Ristovski, Nikola; Bock, Nathalie; Liao, Sam; Powell, Sean K; Ren, Jiongyu; Kirby, Giles T S; Blackwood, Keith A; Woodruff, Maria A

    2015-03-25

    Direct writing melt electrospinning is an additive manufacturing technique capable of the layer-by-layer fabrication of highly ordered 3d tissue engineering scaffolds from micron-diameter fibers. The utility of these scaffolds, however, is limited by the maximum achievable height of controlled fiber deposition, beyond which the structure becomes increasingly disordered. A source of this disorder is charge build-up on the deposited polymer producing unwanted coulombic forces. In this study, the authors introduce a novel melt electrospinning platform with dual voltage power supplies to reduce undesirable charge effects and improve fiber deposition control. The authors produced and characterized several 90° cross-hatched fiber scaffolds using a range of needle/collector plate voltages. Fiber thickness was found to be sensitive only to overall potential and invariant to specific tip/collector voltage. The authors also produced ordered scaffolds up to 200 layers thick (fiber spacing 1 mm and diameter 40 μm) and characterized structure in terms of three distinct zones: ordered, semiordered, and disordered. Our in vitro analysis indicates successful cell attachment and distribution throughout the scaffolds, with little evidence of cell death after seven days. This study demonstrates the importance of electrostatic control for reducing destabilizing polymer charge effects and enabling the fabrication of morphologically suitable scaffolds for tissue engineering.

  14. Preparation of poly(ethylene glycol)/polylactide hybrid fibrous scaffolds for bone tissue engineering.

    PubMed

    Ni, PeiYan; Fu, ShaoZhi; Fan, Min; Guo, Gang; Shi, Shuai; Peng, JinRong; Luo, Feng; Qian, ZhiYong

    2011-01-01

    Polylactide (PLA) electrospun fibers have been reported as a scaffold for bone tissue engineering application, however, the great hydrophobicity limits its broad application. In this study, the hybrid amphiphilic poly(ethylene glycol) (PEG)/hydrophobic PLA fibrous scaffolds exhibited improved morphology with regular and continuous fibers compared to corresponding blank PLA fiber mats. The prepared PEG/PLA fibrous scaffolds favored mesenchymal stem cell (MSC) attachment and proliferation by providing an interconnected porous extracellular environment. Meanwhile, MSCs can penetrate into the fibrous scaffold through the interstitial pores and integrate well with the surrounding fibers, which is very important for favorable application in tissue engineering. More importantly, the electrospun hybrid PEG/PLA fibrous scaffolds can enhance MSCs to differentiate into bone-associated cells by comprehensively evaluating the representative markers of the osteogenic procedure with messenger ribonucleic acid quantitation and protein analysis. MSCs on the PEG/PLA fibrous scaffolds presented better differentiation potential with higher messenger ribonucleic acid expression of the earliest osteogenic marker Cbfa-1 and mid-stage osteogenic marker Col I. The significantly higher alkaline phosphatase activity of the PEG/PLA fibrous scaffolds indicated that these can enhance the differentiation of MSCs into osteoblast-like cells. Furthermore, the higher messenger ribonucleic acid level of the late osteogenic differentiation markers OCN (osteocalcin) and OPN (osteopontin), accompanied by the positive Alizarin red S staining, showed better maturation of osteogenic induction on the PEG/PLA fibrous scaffolds at the mineralization stage of differentiation. After transplantation into the thigh muscle pouches of rats, and evaluating the inflammatory cells surrounding the scaffolds and the physiological characteristics of the surrounding tissues, the PEG/PLA scaffolds presented good

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

    PubMed

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

    2013-07-10

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

  16. Polycaprolactone nanofiber interspersed collagen type-I scaffold for bone regeneration: a unique injectable osteogenic scaffold.

    PubMed

    Baylan, Nuray; Bhat, Samerna; Ditto, Maggie; Lawrence, Joseph G; Lecka-Czernik, Beata; Yildirim-Ayan, Eda

    2013-08-01

    There is an increasing demand for an injectable cell coupled three-dimensional (3D) scaffold to be used as bone fracture augmentation material. To address this demand, a novel injectable osteogenic scaffold called PN-COL was developed using cells, a natural polymer (collagen type-I), and a synthetic polymer (polycaprolactone (PCL)). The injectable nanofibrous PN-COL is created by interspersing PCL nanofibers within pre-osteoblast cell embedded collagen type-I. This simple yet novel and powerful approach provides a great benefit as an injectable bone scaffold over other non-living bone fracture stabilization polymers, such as polymethylmethacrylate and calcium content resin-based materials. The advantages of injectability and the biomimicry of collagen was coupled with the structural support of PCL nanofibers, to create cell encapsulated injectable 3D bone scaffolds with intricate porous internal architecture and high osteoconductivity. The effects of PCL nanofiber inclusion within the cell encapsulated collagen matrix has been evaluated for scaffold size retention and osteocompatibility, as well as for MC3T3-E1 cells osteogenic activity. The structural analysis of novel bioactive material proved that the material is chemically stable enough in an aqueous solution for an extended period of time without using crosslinking reagents, but it is also viscous enough to be injected through a syringe needle. Data from long-term in vitro proliferation and differentiation data suggests that novel PN-COL scaffolds promote the osteoblast proliferation, phenotype expression, and formation of mineralized matrix. This study demonstrates for the first time the feasibility of creating a structurally competent, injectable, cell embedded bone tissue scaffold. Furthermore, the results demonstrate the advantages of mimicking the hierarchical architecture of native bone with nano- and micro-size formation through introducing PCL nanofibers within macron-size collagen fibers and in

  17. Melt electrospinning of biodegradable polyurethane scaffolds

    PubMed Central

    Karchin, Ari; Simonovsky, Felix I.; Ratner, Buddy D.; Sanders, Joan E.

    2014-01-01

    Electrospinning from the melt, in contrast to from solution, is an attractive tissue engineering scaffold manufacturing process as it allows for the formation of small diameter fibers while eliminating potentially cytotoxic solvents. Despite this, there is a dearth of literature on scaffold formation via melt electrospinning. This is likely due to the technical challenges related to the need for a well-controlled high temperature setup and the difficulty in developing an appropriate polymer. In this paper, a biodegradable and thermally stable polyurethane (PU) is described specifically for use in melt electrospinning. Polymer formulations of aliphatic PUs based on (CH2)4-content diisocyanates, polycaprolactone (PCL), 1,4-butanediamine and 1,4-butanediol (BD) were evaluated for utility in the melt electrospinning process. The final polymer formulation, a catalyst-purified PU based on 1,4-butane diisocyanate, PCL and BD in a 4/1/3 molar ratio with a weight-average molecular weight of about 40 kDa, yielded a nontoxic polymer that could be readily electrospun from the melt. Scaffolds electrospun from this polymer contained point bonds between fibers and mechanical properties analogous to many in vivo soft tissues. PMID:21640853

  18. Connector For Embedded Optical Fiber

    NASA Technical Reports Server (NTRS)

    Wilkerson, Charles; Hiles, Steven; Houghton, J. Richard; Holland, Brent W.

    1994-01-01

    Partly embedded fixture is simpler and sturdier than other types of outlets for optical fibers embedded in solid structures. No need to align coupling prism and lenses. Fixture includes base, tube bent at 45 degree angle, and ceramic ferrule.

  19. Collagen a natural scaffold for biology and engineering

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Collagen, the most abundant protein in mammals, constitutes a quarter of the animal's total weight. The unique structure of fibrous collagens, a long triple helix that further associates into fibers, provides an insoluble scaffold that gives strength and form to the skin, tendons, bones, cornea and...

  20. Electrospun gelatin/PCL and collagen/PLCL scaffolds for vascular tissue engineering.

    PubMed

    Fu, Wei; Liu, Zhenling; Feng, Bei; Hu, Renjie; He, Xiaomin; Wang, Hao; Yin, Meng; Huang, Huimin; Zhang, Haibo; Wang, Wei

    2014-01-01

    Electrospun hybrid nanofibers prepared using combinations of natural and synthetic polymers have been widely investigated in cardiovascular tissue engineering. In this study, electrospun gelatin/polycaprolactone (PCL) and collagen/poly(l-lactic acid-co-ε-caprolactone) (PLCL) scaffolds were successfully produced. Scanning electron micrographs showed that fibers of both membranes were smooth and homogeneous. Water contact angle measurements further demonstrated that both scaffolds were hydrophilic. To determine cell attachment and migration on the scaffolds, both hybrid scaffolds were seeded with human umbilical arterial smooth muscle cells. Scanning electron micrographs and MTT assays showed that the cells grew and proliferated well on both hybrid scaffolds. Gross observation of the transplanted scaffolds revealed that the engineered collagen/PLCL scaffolds were smoother and brighter than the gelatin/PCL scaffolds. Hematoxylin and eosin staining showed that the engineered blood vessels constructed by collagen/PLCL electrospun membranes formed relatively homogenous vessel-like tissues. Interestingly, Young's modulus for the engineered collagen/PLCL scaffolds was greater than for the gelatin/PCL scaffolds. Together, these results indicate that nanofibrous collagen/PLCL membranes with favorable mechanical and biological properties may be a desirable scaffold for vascular tissue engineering.

  1. Biomolecule Gradient in Micropatterned Nanofibrous Scaffold for Spatiotemporal Release

    PubMed Central

    Bonani, Walter; Motta, Antonella; Migliaresi, Claudio; Tan, Wei

    2013-01-01

    Controlled molecule release from scaffolds can dramatically increase the scaffold ability of directing tissue regeneration in vitro and in vivo. Crucial to the regeneration is precise regulation over release direction and kinetics of multiple molecules (small genes, peptides, or larger proteins). To this end, we developed gradient micropatterns of electrospun nanofibers along the scaffold thickness through programming the deposition of heterogeneous nanofibers of poly(ε-caprolactone) (PCL) and poly(D,L-lactide-co-glycolide) acid (PLGA). Confocal images of the scaffolds containing fluorophore-impregnated nanofibers demonstrated close matching of actual and designed gradient fiber patterns; thermal analyses further showed their matching in the composition. Using acid-terminated PLGA (PLGAac) and ester-terminated PLGA (PLGAes) to impregnate molecules in the PCL-PLGA scaffolds, we demonstrated for the first time their differences in nanofiber degeneration and molecular weight change during degradation. PLGAac nanofibers were more stable with gradual and steady increase in the fiber diameter during degradation, resulting in more spatially confined molecule delivery from PCL-PLGA scaffolds. Thus, patterns of PCL-PLGAac nanofibers were used to design versatile controlled delivery scaffolds. To test the hypothesis that molecule-impregnated PLGAac in the gradient-patterned PCL-PLGAac scaffolds can program various modalities of molecule release, model molecules, including small fluorophores and larger proteins, were respectively used for time-lapse release studies. Gradient-patterns were used as building blocks in the scaffolds to program simultaneous release of one or multiple proteins to one side or, respectively, to the opposite sides of scaffolds for up to 50 days. Results showed that the separation efficiency of molecule delivery from all the scaffolds with a thickness of 200 μm achieved >88% for proteins and >82% for small molecules. In addition to versatile

  2. Exact approaches for scaffolding

    PubMed Central

    2015-01-01

    This paper presents new structural and algorithmic results around the scaffolding problem, which occurs prominently in next generation sequencing. The problem can be formalized as an optimization problem on a special graph, the "scaffold graph". We prove that the problem is polynomial if this graph is a tree by providing a dynamic programming algorithm for this case. This algorithm serves as a basis to deduce an exact algorithm for general graphs using a tree decomposition of the input. We explore other structural parameters, proving a linear-size problem kernel with respect to the size of a feedback-edge set on a restricted version of Scaffolding. Finally, we examine some parameters of scaffold graphs, which are based on real-world genomes, revealing that the feedback edge set is significantly smaller than the input size. PMID:26451725

  3. Scaffold: Quantum Programming Language

    DTIC Science & Technology

    2012-07-24

    it in pointer and addressing errors. • C2QG: A key feature of Scaffold is a Classical code to Quantum Gates sequence (C2QG) mod- ule. C2QG modules...Scaffold: Quantum Programming Language Ali Javadi Abhari, Arvin Faruque, Mohammad Javad Dousti, Lukas Svec, Oana Catu, Amlan Chakrabati, Chen-Fu...endorsements, either expressed or implied, of IARPA, DoI/NBC, or the U.S. Government. 1 Introduction Quantum computing is of significant research

  4. Electrospun nanofiber reinforcement of dental composites with electromagnetic alignment approach.

    PubMed

    Uyar, Tansel; Çökeliler, Dilek; Doğan, Mustafa; Koçum, Ismail Cengiz; Karatay, Okan; Denkbaş, Emir Baki

    2016-05-01

    Polymethylmethacrylate (PMMA) is commonly used as a base acrylic denture material with benefits of rapid and easy handling, however, when it is used in prosthetic dentistry, fracturing or cracking problems can be seen due to the relatively low strength issues. Besides, acrylic resin is the still prominent material for denture fabrication due to its handy and low cost features. Numerous proposed fillers that are used to produce PMMA composites, however electrospun polyvinylalcohol (PVA) nanofiber fillers for production of PMMA composite resins are not studied as much as the others. The other focus of the practice is to compare both mechanical properties and efficiency of aligned fibers versus non-aligned PVA nanofibers in PMMA based dental composites. Field-controlled electrospinning system is manufactured and provided good alignment in lab scale as one of contributions. Some novel auxiliary electrodes in controlled structure are augmented to obtain different patterns of alignment with a certain range of fiber diameters. Scanning electron microscopy is used for physical characterization to determine the range of fiber diameters. Non-woven fiber has no unique pattern due to chaotic nature of electrospinning process, but aligned fibers have round pattern or crossed lines. These produced fibers are structured as layer-by-layer form with different features, and these features are used in producing PMMA dental composites with different volume ratios. The maximum flexural strength figure shows that fiber load by weight of 0.25% w/w and above improves in the maximum level. As a result, mechanical properties of PMMA dental composites are improved by using PVA nanofibers as a filler, however the improvement was higher when aligned PVA nanofibers are used. The maximum values were 5.1 MPa (flexural strength), 0.8 GPa (elastic modulus), and 170 kJ/m(3) (toughness) in three-point bending test. In addition to the positive results of aligned and non-aligned nanofibers it was found

  5. The Proliferation Study of Hips Cell-Derived Neuronal Progenitors on Poly-Caprolactone Scaffold

    PubMed Central

    Havasi, Parvaneh; Soleimani, Masoud; Morovvati, Hassan; Bakhshandeh, Behnaz; Nabiuni, Mohammad

    2014-01-01

    Introduction The native inability of nervous system to regenerate, encourage researchers to consider neural tissue engineering as a potential treatment for spinal cord injuries. Considering the suitable characteristics of induced pluripotent stem cells (iPSCs) for tissue regeneration applications, in this study we investigated the adhesion, viability and proliferation of neural progenitors (derived from human iPSCs) on aligned poly-caprolactone (PCL) nanofibers. Methods Aligned poly-caprolactone nanofibrous scaffold was fabricated by electrospinning and characterized by scanning electron microscopy (SEM). Through neural induction, neural progenitor cells were derived from induced pluripotent stem cells. After cell seeding on the scaffolds, their proliferation was investigated on different days of culture. Results According to the SEM micrographs, the electrospun PCL scaffolds were aligned along with uniformed morphology. Evaluation of adhesion and viability of neural progenitor cells on plate (control) and PCL scaffold illustrated increasing trends in proliferation but this rate was higher in scaffold group. The statistical analyses confirmed significant differences between groups on 36h and 48h. Discussion Evaluation of cell proliferation along with morphological assessments, staining and SEM finding suggested biocompatibility of the PCL scaffolds and suitability of the combination of the mentioned scaffold and human iPS cells for neural regeneration. PMID:25337369

  6. Nano/macro porous bioactive glass scaffold

    NASA Astrophysics Data System (ADS)

    Wang, Shaojie

    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.

  7. Multifunctional hybrid three-dimensionally woven scaffolds for cartilage tissue engineering.

    PubMed

    Moutos, Franklin T; Estes, Bradley T; Guilak, Farshid

    2010-11-10

    The successful replacement of large-scale cartilage defects or osteoarthritic lesions using tissue-engineering approaches will likely require composite biomaterial scaffolds that have biomimetic mechanical properties and can provide cell-instructive cues to control the growth and differentiation of embedded stem or progenitor cells. This study describes a novel method of constructing multifunctional scaffolds for cartilage tissue engineering that can provide both mechanical support and biological stimulation to seeded progenitor cells. 3-D woven PCL scaffolds were infiltrated with a slurry of homogenized CDM of porcine origin, seeded with human ASCs, and cultured for up to 42 d under standard growth conditions. These constructs were compared to scaffolds derived solely from CDM as well as 3-D woven PCL fabric without CDM. While all scaffolds promoted a chondrogenic phenotype of the ASCs, CDM scaffolds showed low compressive and shear moduli and contracted significantly during culture. Fiber-reinforced CDM scaffolds and 3-D woven PCL scaffolds maintained their mechanical properties throughout the culture period, while supporting the accumulation of a cartilaginous extracellular matrix. These findings show that fiber-reinforced hybrid scaffolds can be produced with biomimetic mechanical properties as well as the ability to promote ASC differentiation and chondrogenesis in vitro.

  8. Scaffolds in Tendon Tissue Engineering

    PubMed Central

    Longo, Umile Giuseppe; Lamberti, Alfredo; Petrillo, Stefano; Maffulli, Nicola; Denaro, Vincenzo

    2012-01-01

    Tissue engineering techniques using novel scaffold materials offer potential alternatives for managing tendon disorders. Tissue engineering strategies to improve tendon repair healing include the use of scaffolds, growth factors, cell seeding, or a combination of these approaches. Scaffolds have been the most common strategy investigated to date. Available scaffolds for tendon repair include both biological scaffolds, obtained from mammalian tissues, and synthetic scaffolds, manufactured from chemical compounds. Preliminary studies support the idea that scaffolds can provide an alternative for tendon augmentation with an enormous therapeutic potential. However, available data are lacking to allow definitive conclusion on the use of scaffolds for tendon augmentation. We review the current basic science and clinical understanding in the field of scaffolds and tissue engineering for tendon repair. PMID:22190961

  9. Multiscale Poly-(ϵ-caprolactone) Scaffold Mimicking Nonlinearity in Tendon Tissue Mechanics

    PubMed Central

    Banik, Brittany L.; Lewis, Gregory S.; Brown, Justin L.

    2016-01-01

    Regenerative medicine plays a critical role in the future of medicine. However, challenges remain to balance stem cells, biomaterial scaffolds, and biochemical factors to create successful and effective scaffold designs. This project analyzes scaffold architecture with respect to mechanical capability and preliminary mesenchymal stem cell response for tendon regeneration. An electrospun fiber scaffold with tailorable properties based on a “Chinese-fingertrap” design is presented. The unique criss-crossed fiber structures demonstrate non-linear mechanical response similar to that observed in native tendon. Mechanical testing revealed that optimizing the fiber orientation resulted in the characteristic “S”-shaped curve, demonstrating a toe region and linear elastic region. This project has promising research potential across various disciplines: vascular engineering, nerve regeneration, and ligament and tendon tissue engineering. PMID:27141530

  10. Development of model hydroxyapatite bone scaffolds with multiscale porosity for potential load bearing applications

    NASA Astrophysics Data System (ADS)

    Dellinger, Jennifer Gwynne

    2005-11-01

    Model hydroxyapatite (HA) bone scaffolds consisting of a latticed pattern of rods were fabricated by a solid freeform fabrication (SFF) technique based on the robotic deposition of colloidal pastes. An optimal HA paste formulation for this method was developed. Local porosity, i.e. microporosity (1--30 mum) and sintering porosity (less than 1 mum), were produced by including polymer microsphere porogens in the HA pastes and by controlling the sintering of the scaffolds. Scaffolds with and without local porosity were evaluated with and without in vitro accelerated degradation. Percent weight loss of the scaffolds and calcium and phosphorus concentrations in solution increased with degradation time. After degradation, compressive strength and modulus decreased significantly for scaffolds with local porosity, but did not change significantly for scaffolds without local porosity. The compressive strength and modulus of scaffolds without local porosity were comparable to human cortical bone and were significantly greater than the scaffolds with local porosity. Micropores in HA disks caused surface pits that increased the surface roughness as compared to non-microporous HA disks. Mouse mesenchymal stem cells extended their cell processes into these microporous pits on HA disks in vitro. ALP expression was prolonged, cell attachment strength increased, and ECM production appeared greater on microporous HA disks compared to non-microporous HA disks and tissue culture treated polystyrene controls. Scaffolds with and without microporosity were implanted in goats bones. Microporous scaffolds with rhBMP-2 increased the percent of the scaffold filled with bone tissue compared to microporous scaffolds without rhBMP-2. Lamellar bone inside scaffolds was aligned near the rods junctions whereas lamellar bone was aligned in a more random configuration away from the rod junctions. Microporous scaffolds stained darkly with toluidine blue beneath areas of contact with new bone. This

  11. Indirect coculture of stem cells with fetal chondrons using PCL electrospun nanofiber scaffolds.

    PubMed

    Nikpou, Parisa; Soleimani Rad, Jafar; Mohammad Nejad, Daryoush; Samadi, Nasser; Roshangar, Leila; Navali, Amir Mohammad; Shafaei, Hajar; Nozad Charoudeh, Hojjatollah; Danandeh Oskoei, Neda; Soleimani Rad, Sara

    2017-03-01

    In vitro coculture system provides a powerful tool for tissue engineering. In this study, we evaluated the gene expressions of human adipose-derived stem cells (ASCs) on polycaprolactone (PCL) scaffold in coculture model with fetal chondrons. Electrospun PCL scaffolds (900 nm fiber diameter) were created and human infrapatellar fat pad-adipose-derived stem cells (IPFP-ASCs) were seeded on these scaffolds. Scanning electron microscopy (SEM) showed attachment of human IPFP-ASCs to scaffold. IPFP-ASCs on scaffolds were cocultured with fetal chondrons in transwell. Gene expressions were investigated using real-time polymerase chain reaction (real-time PCR). In comparison with control group, the expression level of collagen type 2 and aggrecan were significantly decreased but Indian Hedgehog(IHH) significantly increased (P < 0.05).These findings may interpreted that IPFP-ASCs seeded on PCL scaffold, in cocultures with fetal chondrons are tending toward osteogenesis rather than chondrogenesis.

  12. Direct alignment and patterning of silver nanowires by electrohydrodynamic jet printing.

    PubMed

    Lee, Hyungdong; Seong, Baekhoon; Kim, Jihoon; Jang, Yonghee; Byun, Doyoung

    2014-10-15

    Highly aligned and patterned silver nanowires (Ag NWs) are investigated by using electrohydrodynamic (EHD) jet printing. Interaction between the flow field and the electric field as well as the mechanical stretching of the fiber jet can successfully align the Ag NWs inside the jet fiber. This technique can be applied in fabricating 1D nanostructures-based printed micro/nanoscale devices.

  13. A fibrinogen-based precision microporous scaffold for tissue engineering.

    PubMed

    Linnes, Michael P; Ratner, Buddy D; Giachelli, Cecilia M

    2007-12-01

    Fibrin has been long used as an effective scaffolding material to grow a variety of cells and tissue constructs. It has been utilized mainly as a hydrogel in varying concentrations to provide an environment in which suspended cells work to rearrange the fibers and lay down their own extracellular matrix. For these fibrin hydrogels to be useful in many tissue-engineering applications, the gels must be cultured for long periods of time in order to increase their mechanical strength to the levels of native tissues. High concentrations of fibrinogen increase the mechanical strength of fibrin hydrogels, but at the same time reduce the ability of cells within the scaffold to spread and survive. We present a method to create a microporous, nanofibriliar fibrin scaffold that has controllable pore size, porosity, and microstructure for applications in tissue engineering. Fibrin has numerous advantages as a scaffolding material as it is normally used by the body as temporary scaffolding for tissue regeneration and healing, and can be autologously sourced. We present here a scaffolding process which enhances the mechanical properties of the fibrin hydrogel by forming it surrounding poly(methyl-methacrylate) beads, then removing the beads with acetone to form an interconnected microporous network. The acetone serves the dual purpose of precipitating and fixing the fibrinogen-based scaffolds as well as adding strength to the network during polymer bead removal. Effects of fibrinogen concentration and time in acetone were examined as well as polymerization with thrombin. A natural crosslinker, genipin, was also used to add strength to the scaffolds, producing a Young's modulus of up to 184+/-5 kPa after 36 h of reaction. Using these methods we were able to produce microporous fibrin scaffolds that support cell growth and have mechanical properties similar to many native tissues.

  14. Design of practical alignment device in KSTAR Thomson diagnostic

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Lee, S. H.; Yamada, I.

    2016-11-01

    The precise alignment of the laser path and collection optics in Thomson scattering measurements is essential for accurately determining electron temperature and density in tokamak experiments. For the last five years, during the development stage, the KSTAR tokamak's Thomson diagnostic system has had alignment fibers installed in its optical collection modules, but these lacked a proper alignment detection system. In order to address these difficulties, an alignment verifying detection device between lasers and an object field of collection optics is developed. The alignment detection device utilizes two types of filters: a narrow laser band wavelength for laser, and a broad wavelength filter for Thomson scattering signal. Four such alignment detection devices have been successfully developed for the KSTAR Thomson scattering system in this year, and these will be tested in KSTAR experiments in 2016. In this paper, we present the newly developed alignment detection device for KSTAR's Thomson scattering diagnostics.

  15. Optical Fiber Communications Cable Connector.

    DTIC Science & Technology

    1981-07-01

    incorp- oration of the TRW Cinch Optalign 4 double elbow " fiber alignment guide concept. Means for connecting either Siecor or ITT six fiber cable were...the guide, and forced toward the top cusp by the double elbow con- figuration. The geometry of the guide is such that normal tolerances of molded or

  16. Multilayered silk scaffolds for meniscus tissue engineering.

    PubMed

    Mandal, Biman B; Park, Sang-Hyug; Gil, Eun S; Kaplan, David L

    2011-01-01

    Removal of injured/damaged meniscus, a vital fibrocartilaginous load-bearing tissue, impairs normal knee function and predisposes patients to osteoarthritis. Meniscus tissue engineering solution is one option to improve outcomes and relieve pain. In an attempt to fabricate knee meniscus grafts three layered wedge shaped silk meniscal scaffold system was engineered to mimic native meniscus architecture. The scaffolds were seeded with human fibroblasts (outside) and chondrocytes (inside) in a spatial separated mode similar to native tissue, in order to generate meniscus-like tissue in vitro. In chondrogenic culture in the presence of TGF-b3, cell-seeded constructs increased in cellularity and extracellular matrix (ECM) content. Histology and Immunohistochemistry confirmed maintenance of chondrocytic phenotype with higher levels of sulfated glycosaminoglycans (sGAG) and collagen types I and II. Improved scaffold mechanical properties along with ECM alignment with time in culture suggest this multiporous silk construct as a useful micro-patterned template for directed tissue growth with respect to form and function of meniscus-like tissue.

  17. Multilayered silk scaffolds for meniscus tissue engineering

    PubMed Central

    Mandal, Biman B.; Park, Sang-Hyug; Gil, Eun Seok

    2010-01-01

    Removal of injured/damaged meniscus, a vital fibrocartilaginous load-bearing tissue, impairs normal knee function and predisposes patients to osteoarthritis. Meniscus tissue engineering solution is one option to improve outcomes and relieve pain. In an attempt to fabricate knee meniscus grafts three layered wedge shaped silk meniscal scaffold system was engineered to mimic native meniscus architecture. The scaffolds were seeded with human fibroblasts (outside) and chondrocytes (inside) in a spatial separated mode similar to native tissue, in order to generate meniscus-like tissue in vitro. In chondrogenic culture in the presence of TGF-b3, cell seeded constructs increased in cellularity and extracellular matrix (ECM) content. Histology and Immunohistochemistry confirmed maintenance of chondrocytic phenotype with higher levels of sulphated glycosaminoglycans (sGAG) and collagen types I and II. Improved scaffold mechanical properties along with ECM alignment with time in culture suggest this multiporous silk construct as a useful micro-patterned template for directed tissue growth with respect to form and function of meniscus-like tissue. PMID:20926132

  18. MP-Align: alignment of metabolic pathways

    PubMed Central

    2014-01-01

    Background Comparing the metabolic pathways of different species is useful for understanding metabolic functions and can help in studying diseases and engineering drugs. Several comparison techniques for metabolic pathways have been introduced in the literature as a first attempt in this direction. The approaches are based on some simplified representation of metabolic pathways and on a related definition of a similarity score (or distance measure) between two pathways. More recent comparative research focuses on alignment techniques that can identify similar parts between pathways. Results We propose a methodology for the pairwise comparison and alignment of metabolic pathways that aims at providing the largest conserved substructure of the pathways under consideration. The proposed methodology has been implemented in a tool called MP-Align, which has been used to perform several validation tests. The results showed that our similarity score makes it possible to discriminate between different domains and to reconstruct a meaningful phylogeny from metabolic data. The results further demonstrate that our alignment algorithm correctly identifies subpathways sharing a common biological function. Conclusion The results of the validation tests performed with MP-Align are encouraging. A comparison with another proposal in the literature showed that our alignment algorithm is particularly well-suited to finding the largest conserved subpathway of the pathways under examination. PMID:24886436

  19. Photovoltaic fibers

    NASA Astrophysics Data System (ADS)

    Gaudiana, Russell; Eckert, Robert; Cardone, John; Ryan, James; Montello, Alan

    2006-08-01

    It was realized early in the history of Konarka that the ability to produce fibers that generate power from solar energy could be applied to a wide variety of applications where fabrics are utilized currently. These applications include personal items such as jackets, shirts and hats, to architectural uses such as awnings, tents, large covers for cars, trucks and even doomed stadiums, to indoor furnishings such as window blinds, shades and drapes. They may also be used as small fabric patches or fiber bundles for powering or recharging batteries in small sensors. Power generating fabrics for clothing is of particular interest to the military where they would be used in uniforms and body armor where portable power is vital to field operations. In strong sunlight these power generating fabrics could be used as a primary source of energy, or they can be used in either direct sunlight or low light conditions to recharge batteries. Early in 2002, Konarka performed a series of proof-of-concept experiments to demonstrate the feasibility of building a photovoltaic cell using dye-sensitized titania and electrolyte on a metal wire core. The approach taken was based on the sequential coating processes used in making fiber optics, namely, a fiber core, e.g., a metal wire serving as the primary electrode, is passed through a series of vertically aligned coating cups. Each of the cups contains a coating fluid that has a specific function in the photocell. A second wire, used as the counter electrode, is brought into the process prior to entering the final coating cup. The latter contains a photopolymerizable, transparent cladding which hardens when passed through a UV chamber. Upon exiting the UV chamber, the finished PV fiber is spooled. Two hundred of foot lengths of PV fiber have been made using this process. When the fiber is exposed to visible radiation, it generates electrical power. The best efficiency exhibited by these fibers is 6% with an average value in the 4

  20. Girder Alignment Plan

    SciTech Connect

    Wolf, Zackary; Ruland, Robert; LeCocq, Catherine; Lundahl, Eric; Levashov, Yurii; Reese, Ed; Rago, Carl; Poling, Ben; Schafer, Donald; Nuhn, Heinz-Dieter; Wienands, Uli; /SLAC

    2010-11-18

    The girders for the LCLS undulator system contain components which must be aligned with high accuracy relative to each other. The alignment is one of the last steps before the girders go into the tunnel, so the alignment must be done efficiently, on a tight schedule. This note documents the alignment plan which includes efficiency and high accuracy. The motivation for girder alignment involves the following considerations. Using beam based alignment, the girder position will be adjusted until the beam goes through the center of the quadrupole and beam finder wire. For the machine to work properly, the undulator axis must be on this line and the center of the undulator beam pipe must be on this line. The physics reasons for the undulator axis and undulator beam pipe axis to be centered on the beam are different, but the alignment tolerance for both are similar. In addition, the beam position monitor must be centered on the beam to preserve its calibration. Thus, the undulator, undulator beam pipe, quadrupole, beam finder wire, and beam position monitor axes must all be aligned to a common line. All relative alignments are equally important, not just, for example, between quadrupole and undulator. We begin by making the common axis the nominal beam axis in the girder coordinate system. All components will be initially aligned to this axis. A more accurate alignment will then position the components relative to each other, without incorporating the girder itself.

  1. Biologically inspired growth of hydroxyapatite crystals on bio-organics-defined scaffolds

    SciTech Connect

    Yang, Chunrong; Li, Yuli; Nan, Kaihui

    2013-03-15

    Graphical abstract: Petal-like crystals were observed to form on the surface of the BG/COL/ChS scaffolds. Highlights: ► Porous scaffolds were prepared using bioglass, collagen and chondroitin sulfate. ► Highly oriented HA crystals were grown on scaffolds using simulated body fluids ► The microstructure and orientation of HA were explained by molecular configuration. - Abstract: Several bio-organics-defined composite scaffolds were prepared using 58s-bioglass (BG), collagen (Col) and chondroitin sulfate (ChS). These scaffolds possess highly porous structure. X-ray diffraction of these scaffolds strongly indicated that hydroxyapatite (HA) crystals formed on their surfaces in simulated body fluids within 3 d, and similar formation process of crystals could be obtained on BG/Col and BG/Col/ChS scaffolds. The morphology and structure of the crystals were further examined by scanning electron microscopy. The results obtained indicate that an apatite with petal-like structure similar to that found on BG/Col scaffolds can be produced on BG/Col/ChS scaffolds through biomimetic synthesis, while that on BG/ChS scaffolds took place differently. The differences could be explained by self-assembly processes and the different macromolecular configurations of the Col and ChS fibrils which self-assemble spontaneously into their fibers. On the other hand, the bio-organics-defined composites have good cell biocompability. The results may be applicable to develop tailored biomaterials for peculiar bone substitute.

  2. An approach to architecture 3D scaffold with interconnective microchannel networks inducing angiogenesis for tissue engineering.

    PubMed

    Sun, Jiaoxia; Wang, Yuanliang; Qian, Zhiyong; Hu, Chenbo

    2011-11-01

    The angiogenesis of 3D scaffold is one of the major current limitations in clinical practice tissue engineering. The new strategy of construction 3D scaffold with microchannel circulation network may improve angiogenesis. In this study, 3D poly(D: ,L: -lactic acid) scaffolds with controllable microchannel structures were fabricated using sacrificial sugar structures. Melt drawing sugar-fiber network produced by a modified filament spiral winding method was used to form the microchannel with adjustable diameters and porosity. This fabrication process was rapid, inexpensive, and highly scalable. The porosity, microchannel diameter, interconnectivity and surface topographies of the scaffold were characterized by scanning electron microscopy. Mechanical properties were evaluated by compression tests. The mean porosity values of the scaffolds were in the 65-78% and the scaffold exhibited microchannel structure with diameter in the 100-200 μm range. The results showed that the scaffolds exhibited an adequate porosity, interconnective microchannel network, and mechanical properties. The cell culture studies with endothelial cells (ECs) demonstrated that the scaffold allowed cells to proliferate and penetrate into the volume of the entire scaffold. Overall, these findings suggest that the fabrication process offers significant advantages and flexibility in generating a variety of non-cytotoxic tissue engineering scaffolds with controllable distributions of porosity and physical properties that could provide the necessary physical cues for ECs and further improve angiogenesis for tissue engineering.

  3. Biodegradable Fibrous Scaffolds with Diverse Properties by Electrospinning Candidates from a Combinatorial Macromer Library

    PubMed Central

    Metter, Robert B.; Ifkovits, Jamie L.; Hou, Kevin; Vincent, Ludovic; Hsu, Benjamin; Wang, Louis; Mauck, Robert L.; Burdick, Jason A.

    2009-01-01

    The properties of electrospun fibrous scaffolds, including degradation, mechanics and cellular interactions, are important for their use in tissue engineering applications. Although some diversity has been obtained previously in fibrous scaffolds, optimization of scaffold properties relies on iterative techniques in both polymer synthesis and processing. Here, we electrospun candidates from a combinatorial library of biodegradable and photopolymerizable poly(β-amino ester)s (PBAEs) to show that the diversity in properties found in this library is retained when processed into fibrous scaffolds. Specifically, three PBAE macromers were electrospun into scaffolds and possessed similar initial mechanical properties, but exhibited mass loss ranging from rapid (complete degradation within ∼2 weeks) to moderate (complete degradation within ∼ 3 months) to slow (only partial degradation after 3 months). These trends in mechanics and degradation mimicked what was previously observed in the bulk polymers. Although cellular adhesion was dependent on the polymer composition in films, adhesion to scaffolds that were electrospun with gelatin was similar on all formulations and controls. To further illustrate the diverse properties that are attainable in these systems, the fastest and slowest degrading polymers were electrospun together into one scaffold, but as distinct fiber populations. This dual-polymer scaffold exhibited behavior in mass loss and mechanics with time that fell between the single-polymer scaffolds. In general, this work indicates that combinatorial libraries may be an important source of information and specific polymer compositions for the fabrication of electrospun fibrous scaffolds with tunable properties. PMID:19853066

  4. Skeletal muscle regeneration on protein-grafted and microchannel-patterned scaffold for hypopharyngeal tissue engineering.

    PubMed

    Shen, Zhisen; Guo, Shanshan; Ye, Dong; Chen, Jingjing; Kang, Cheng; Qiu, Shejie; Lu, Dakai; Li, Qun; Xu, Kunjie; Lv, Jingjing; Zhu, Yabin

    2013-01-01

    In the field of tissue engineering, polymeric materials with high biocompatibility like polylactic acid and polyglycolic acid have been widely used for fabricating living constructs. For hypopharynx tissue engineering, skeletal muscle is one important functional part of the whole organ, which assembles the unidirectionally aligned myotubes. In this study, a polyurethane (PU) scaffold with microchannel patterns was used to provide aligning guidance for the seeded human myoblasts. Due to the low hydrophilicity of PU, the scaffold was grafted with silk fibroin (PU-SF) or gelatin (PU-Gel) to improve its cell adhesion properties. Scaffolds were observed to degrade slowly over time, and their mechanical properties and hydrophilicities were improved through the surface grafting. Also, the myoblasts seeded on PU-SF had the higher proliferative rate and better differentiation compared with those on the control or PU-Gel. Our results demonstrate that polyurethane scaffolds seeded with myoblasts hold promise to guide hypopharynx muscle regeneration.

  5. Skeletal Muscle Regeneration on Protein-Grafted and Microchannel-Patterned Scaffold for Hypopharyngeal Tissue Engineering

    PubMed Central

    Shen, Zhisen; Guo, Shanshan; Ye, Dong; Chen, Jingjing; Kang, Cheng; Qiu, Shejie; Lu, Dakai; Li, Qun; Xu, Kunjie; Lv, Jingjing

    2013-01-01

    In the field of tissue engineering, polymeric materials with high biocompatibility like polylactic acid and polyglycolic acid have been widely used for fabricating living constructs. For hypopharynx tissue engineering, skeletal muscle is one important functional part of the whole organ, which assembles the unidirectionally aligned myotubes. In this study, a polyurethane (PU) scaffold with microchannel patterns was used to provide aligning guidance for the seeded human myoblasts. Due to the low hydrophilicity of PU, the scaffold was grafted with silk fibroin (PU-SF) or gelatin (PU-Gel) to improve its cell adhesion properties. Scaffolds were observed to degrade slowly over time, and their mechanical properties and hydrophilicities were improved through the surface grafting. Also, the myoblasts seeded on PU-SF had the higher proliferative rate and better differentiation compared with those on the control or PU-Gel. Our results demonstrate that polyurethane scaffolds seeded with myoblasts hold promise to guide hypopharynx muscle regeneration. PMID:24175281

  6. Electrospun nanofibrous scaffolds for engineering soft connective tissues.

    PubMed

    James, Roshan; Toti, Udaya S; Laurencin, Cato T; Kumbar, Sangamesh G

    2011-01-01

    Tissue-engineered medical implants, such as polymeric nanofiber scaffolds, are potential alternatives to autografts and allografts, which are short in supply and carry risks of disease transmission. These scaffolds have been used to engineer various soft connective tissues such as skin, ligament, muscle, and tendon, as well as vascular and neural tissue. Bioactive versions of these materials have been produced by encapsulating molecules such as drugs and growth factors during fabrication. The fibers comprising these scaffolds can be designed to match the structure of the native extracellular matrix (ECM) closely by mimicking the dimensions of the collagen fiber bundles evident in soft connective tissues. These nanostructured implants show improved biological performance over the bulk materials in aspects of cellular infiltration and in vivo integration, and the topography of such scaffolds has been shown to dictate cellular attachment, migration, proliferation, and differentiation, which are critical steps in engineering complex functional tissues and crucial to improved biocompatibility and functional performance. Nanofiber matrices can be fabricated using a variety of techniques, including drawing, molecular self-assembly, freeze-drying, phase separation, and electrospinning. Among these processes, electrospinning has emerged as a simple, elegant, scalable, continuous, and reproducible technique to produce polymeric nanofiber matrices from solutions and their melts. We have shown the ability of this technique to be used to fabricate matrices composed of fibers from a few hundred nanometers to several microns in diameter by simply altering the polymer solution concentration. This chapter will discuss the use of the electrospinning technique in the fabrication of ECM-mimicking scaffolds. Furthermore, selected scaffolds will be seeded with primary adipose-derived stromal cells, imaged using scanning electron microscopy and confocal microscopy, and evaluated in terms

  7. Fiber pad for pressure mapping

    NASA Astrophysics Data System (ADS)

    Purwanto, H.; Fitriani, U. R.; Dwijosutomo, A.; Marzuki, A.

    2016-11-01

    Optical fiber sandwiched pad designed as a pressure mapping sensor has been configured and characterized. Optical fiber sensor was aligned to form a web-like configuration (x- y matrix). Several fibers were positioned to form lines parallel to y-axis while others are in parallel to x-axis. When a mass with a particular surface contour was loaded on the fiber pad, we have shown the dependence of the magnitude of light attenuation on the mass surface contour. Combining these light attenuation results we have successfully constructed a three dimensional contours showing the pressure distribution given by the mass to the fiber pad.

  8. Cryopreservation of Cell/Scaffold Tissue-Engineered Constructs

    PubMed Central

    Costa, Pedro F.; Dias, Ana F.; Reis, Rui L.

    2012-01-01

    The aim of this work was to study the effect of cryopreservation over the functionality of tissue-engineered constructs, analyzing the survival and viability of cells seeded, cultured, and cryopreserved onto 3D scaffolds. Further, it also evaluated the effect of cryopreservation over the properties of the scaffold material itself since these are critical for the engineering of most tissues and in particular, tissues such as bone. For this purpose, porous scaffolds, namely fiber meshes based on a starch and poly(caprolactone) blend were seeded with goat bone marrow stem cells (GBMSCs) and cryopreserved for 7 days. Discs of the same material seeded with GBMSCs were also used as controls. After this period, these samples were analyzed and compared to samples collected before the cryopreservation process. The obtained results demonstrate that it is possible to maintain cell viability and scaffolds properties upon cryopreservation of tissue-engineered constructs based on starch scaffolds and goat bone marrow mesenchymal cells using standard cryopreservation methods. In addition, the outcomes of this study suggest that the greater porosity and interconnectivity of scaffolds favor the retention of cellular content and cellular viability during cryopreservation processes, when compared with nonporous discs. These findings indicate that it might be possible to prepare off-the-shelf engineered tissue substitutes and preserve them to be immediately available upon request for patients' needs. PMID:22676448

  9. Increasing the pore sizes of bone-mimetic electrospun scaffolds comprised of polycaprolactone, collagen I and hydroxyapatite to enhance cell infiltration

    PubMed Central

    Phipps, Matthew C.; Clem, William C.; Grunda, Jessica M.; Clines, Gregory A.; Bellis, Susan L.

    2012-01-01

    Bone-mimetic electrospun scaffolds consisting of polycaprolactone (PCL), collagen I and nanoparticulate hydroxyapatite (HA) have previously been shown to support the adhesion, integrin-related signaling and proliferation of mesenchymal stem cells (MSCs), suggesting these matrices serve as promising degradable substrates for osteoregeneration. However, the small pore sizes in electrospun scaffolds hinder cell infiltration in vitro and tissue-ingrowth into the scaffold in vivo, limiting their clinical potential. In this study, three separate techniques were evaluated for their capability to increase the pore size of the PCL/col I/nanoHA scaffolds: limited protease digestion, decreasing the fiber packing density during electro-spinning, and inclusion of sacrificial fibers of the water-soluble polymer PEO. The PEO sacrificial fiber approach was found to be the most effective in increasing scaffold pore size. Furthermore, the use of sacrificial fibers promoted increased MSC infiltration into the scaffolds, as well as greater infiltration of endogenous cells within bone upon placement of scaffolds within calvarial organ cultures. These collective findings support the use of sacrificial PEO fibers as a means to increase the porosity of complex, bone-mimicking electrospun scaffolds, thereby enhancing tissue regenerative processes that depend upon cell infiltration, such as vascularization and replacement of the scaffold with native bone tissue. PMID:22014462

  10. Numerical modeling in the design and evaluation of scaffolds for orthopaedics applications.

    PubMed

    Swieszkowski, Wojciech; Kurzydlowski, Krzysztof J

    2012-01-01

    Numerical modeling becomes a very useful tool for design and preclinical evaluation of scaffold for tissue engineering. This chapter illustrates, how finite element analysis and genetic algorithm maybe applied to predict the mechanical performance of novel scaffolds, with a honeycomb-like pattern, a fully interconnected channel network, and controllable porosity fabricated in layers of directionally aligned microfibers deposited using a computer-controlled extrusion process.

  11. Design of functionalized biodegradable PHA-based electrospun scaffolds meant for tissue engineering applications.

    PubMed

    Grande, Daniel; Ramier, Julien; Versace, Davy Louis; Renard, Estelle; Langlois, Valérie

    2017-07-25

    Modification of electrospun nanofibrous poly(3-hydroxyalkanoate) (PHA)-based mats was implemented through two routes to obtain biomimetic scaffolds meant for tissue engineering applications. The first strategy relied on a physical functionalization of scaffolds thanks to an original route which combined both electrospinning and electrospraying, while the second approach implied the chemical modification of fiber surface via the introduction of reactive functional groups to further conjugate bioactive molecules. The degree of glycidyl methacrylate grafting on PHA reached 20% after 300s under photoactivation. Epoxy groups were modified via the attachment of a peptide sequence, such as Arg-Gly-Asp (RGD), to obtain biofunctionalized scaffolds. SEM and TEM analysis of mats showed uniform and well-oriented beadless fibers. The electrospinning/electrospraying tandem process afforded highly porous scaffolds characterized by a porosity ratio up to 83% and fibers with a surface largely covered by the electrosprayed bioceramic, i.e. hydroxyapatite. Gelatin was added to the latter PHA-based scaffolds to improve the hydrophilicity of the scaffolds (water contact angle about 0°) as well as their biological properties, in particular cell adhesion, proliferation, and osteogenic differentiation after 5days of human mesenchymal stromal culture. Human mesenchymal stromal cells exhibited a better adhesion and proliferation on the biofunctionalized scaffolds than that on non-functionalized PHA mats.

  12. Elastin-like-recombinamers multilayered nanofibrous scaffolds for cardiovascular applications.

    PubMed

    Putzu, M; Causa, F; Nele, V; de Torre, I González; Rodriguez-Cabello, J C; Netti, P A

    2016-11-15

    Coronary angioplasty is the most widely used technique for removing atherosclerotic plaques in blood vessels. The regeneration of the damaged intima layer after this treatment is still one of the major challenges in the field of cardiovascular tissue engineering. Different polymers have been used in scaffold manufacturing in order to improve tissue regeneration. Elastin-mimetic polymers are a new class of molecules that have been synthesized and used to obtain small diameter fibers with specific morphological characteristics. Elastin-like polymers produced by recombinant techniques and called elastin-like recombinamers (ELRs) are particularly promising due to their high degree of functionalization. Generally speaking, ELRs can show more complex molecular designs and a tighter control of their sequence than other chemically synthetized polymers Rodriguez Cabello et al (2009 Polymer 50 5159-69, 2011 Nanomedicine 6 111-22). For the fabrication of small diameter fibers, different ELRs were dissolved in 2,2,2-fluoroethanol (TFE). Dynamic light scattering was used to identify the transition temperature and get a deep characterization of the transition behavior of the recombinamers. In this work, we describe the use of electrospinning technique for the manufacturing of an elastic fibrous scaffold; the obtained fibers were characterized and their cytocompatibility was tested in vitro. A thorough study of the influence of voltage, flow rate and distance was carried out in order to determine the appropriate parameters to obtain fibrous mats without beads and defects. Moreover, using a rotating mandrel, we fabricated a tubular scaffold in which ELRs containing different cell adhesion sequences (mainly REDV and RGD) were collected. The stability of the scaffold was improved by using genipin as a crosslinking agent. Genipin-ELRs crosslinked scaffolds  show a good stability and fiber morphology. Human umbilical vein endothelial cells  were used to assess the in vitro

  13. Versatile wedge-based system for the construction of unidirectional collagen scaffolds by directional freezing: practical and theoretical considerations.

    PubMed

    Pot, Michiel W; Faraj, Kaeuis A; Adawy, Alaa; van Enckevort, Willem J P; van Moerkerk, Herman T B; Vlieg, Elias; Daamen, Willeke F; van Kuppevelt, Toin H

    2015-04-29

    Aligned unidirectional collagen scaffolds may aid regeneration of those tissues where alignment of cells and extracellular matrix is essential, as for instance in cartilage, nerve bundles, and skeletal muscle. Pores can be introduced by ice crystal formation followed by freeze-drying, the pore architecture reflecting the ice crystal morphology. In this study we developed a wedge-based system allowing the production of a wide range of collagen scaffolds with unidirectional pores by directional freezing. Insoluble type I collagen suspensions were frozen using a custom-made wedge system, facilitating the formation of a horizontal as well as a vertical temperature gradient and providing a controlled solidification area for ice dendrites. The system permitted the growth of aligned unidirectional ice crystals over a large distance (>2.5 cm), an insulator prolonging the freezing process and facilitating the construction of crack-free scaffolds. Unidirectional collagen scaffolds with tunable pore sizes and pore morphologies were constructed by varying freezing rates and suspension media. The versatility of the system was indicated by the construction of unidirectional scaffolds from albumin, poly(vinyl alcohol) (a synthetic polymer), and collagen-polymer blends producing hybrid scaffolds. Macroscopic observations, temperature measurements, and scanning electron microscopy indicated that directed horizontal ice dendrite formation, vertical ice crystal nucleation, and evolutionary selection were the basis of the aligned unidirectional ice crystal growth and, hence, the aligned unidirectional pore structure. In conclusion, a simple, highly adjustable freezing system has been developed allowing the construction of large (hybrid) bioscaffolds with tunable unidirectional pore architecture.

  14. A tissue engineering approach to anterior cruciate ligament regeneration using novel shaped capillary channel polymer fibers

    NASA Astrophysics Data System (ADS)

    Sinclair, Kristofer D.

    2009-12-01

    application of uniaxial cyclic strain the mechanical properties of the cell seeded CC-P fiber scaffold systems were shown to improve via the induction of increased cellular proliferation and extracellular matrix synthesis. Finally, unlike many studies examining the effects of cyclic strain on cellular behavior, the CC-P fiber geometry displayed the ability to maintain cellular alignment in the presence of an applied uniaxial cyclic strain.

  15. Self-Centering of a Ball Lens by Laser Trapping: Fiber-Ball-Fiber Coupling Analysis

    NASA Astrophysics Data System (ADS)

    Gauthier, Robert C.; Friesen, Michael; Gerrard, Thomas; Hassouneh, Wissam; Koziorowski, Piotr; Moore, Damian; Oprea, Karen; Uttamalingam, Sivasanker

    2003-03-01

    Fiber-to-fiber coupling through use of a laser-trapped microball lens is examined. A model based on radiation pressure predicts that the ball lens will align axially between the fiber endfaces. Laser manipulation of the ball lens axial position results in a configuration in which the ball lens optically bridges the gap between the fibers. Experimental results are presented for several fiber endface separations, and it is found that the presence of the microball lens can increase the coupling by a factor of 2 above the level expected by direct fiber-to-fiber coupling for the same fiber endface separation.

  16. Fibrous scaffolds loaded with protein prepared by blend or coaxial electrospinning.

    PubMed

    Ji, Wei; Yang, Fang; van den Beucken, Jeroen J J P; Bian, Zhuan; Fan, Mingwen; Chen, Zhi; Jansen, John A

    2010-11-01

    The aim of the present study was to fabricate polycaprolactone-based nanofibrous scaffolds with incorporated protein via either the blend or coaxial electrospinning technique. Both techniques were compared with respect to processing set-up and scaffold characteristics as well as the release kinetics and biological activity of the loaded protein. Bovine serum albumin was used as a model protein to determine release profiles, while alkaline phosphatase was used to determine protein activity after the electrospinning process. Coaxial electrospinning resulted in a uniform fiber morphology with a core-shell structure, and a homogeneous protein distribution throughout the core of the fibers. In contrast, blend electrospinning formed bead-like fibers with a heterogeneous protein distribution in the fibers. The coaxial scaffold exhibited more sustained release profiles than the comparative blend scaffold, and the additive poly(ethylene glycol) (PEG) in the coaxial scaffold accelerated protein release. Both electrospinning processes decreased the biological activity of the incorporated protein, but coaxial electrospinning with PEG as an additive showed up to 75% preservation of the initial biological activity. Thus, coaxial electrospinning was demonstrated to be superior to blend electrospinning for the preparation of nanofibrous scaffolds with a uniform fibrous structure and protein distribution and sustained protein release kinetics as well as high preservation of the protein activity.

  17. Antimicrobial effects of nanofiber poly(caprolactone) tissue scaffolds releasing rifampicin.

    PubMed

    Ruckh, Timothy T; Oldinski, Rachael A; Carroll, Derek A; Mikhova, Krasimira; Bryers, James D; Popat, Ketul C

    2012-06-01

    This study quantified the antibiotic release kinetics and subsequent bactericidal efficacy of rifampicin (RIF) against Gram-positive and Gram-negative bacteria under in vitro static conditions. Antibiotic-loaded scaffolds were fabricated by electrospinning poly(caprolactone) (PCL) with 10% or 20% (w/w) RIF. Scaffold fiber diameter and RIF loading were characterized, and RIF release kinetics were measured. RIF-releasing and RIF-free scaffolds were inoculated with Pseudomonas aeruginosa and Staphylococcus epidermidis, and the suspended concentration live and dead bacteria were determined by fluorescent microscopy. Adherent bacteria and biofilm formation were examined using scanning electron microscopy. Mean fiber diameters were 557 ± 399 nm for RIF-free, 402 ± 225 nm for 10% RIF, and 665 ± 402 nm for 20% RIF scaffolds. RIF release kinetics exhibited a short-burst release during the first hour, followed by a 7 h, zero-order release during which both RIF scaffolds released ~50% of their initial RIF mass loading. P. aeruginosa and S. epidermidis suspended cell populations proliferated in accordance with logarithmic growth models when exposed to control scaffolds; however both RIF-containing scaffolds completely inhibited bacterial growth in suspension and, subsequently, prevented biofilm formation within the scaffolds through the first 6 h.

  18. Poly(lactide-co-glycolide)/hydroxyapatite nanofibrous scaffolds fabricated by electrospinning for bone tissue engineering.

    PubMed

    Lao, Lihong; Wang, Yingjun; Zhu, Yang; Zhang, Yuying; Gao, Changyou

    2011-08-01

    Poly(lactide-co-glycolide) (PLGA) nanofibrous composite scaffolds having nano-hydroxyapatite particles (HAp) in the fibers were prepared by electrospinning of PLGA and HAp with an average diameter of 266.6 ± 7.3 nm. Microscopy and spectroscopy characterizations confirmed integration of the crystalline HAp in the scaffolds. Agglomerates gradually appeared and increased on the fiber surface along with increase of the HAp concentration. In vitro mineralization in a 5 × simulated body fluid (SBF) revealed that the PLGA/HAp nanofibrous scaffolds had a stronger biomineralization ability than the control PLGA scaffolds. Biological performance of the nanofibrous scaffolds of the control PLGA and PLGA with 5 wt% HAp (PLGA/5HAp) was assessed by in vitro culture of neonatal mouse calvaria-derived MC3T3-E1 osteoblasts. Both types of the scaffolds could support cell proliferation and showed sharp increase of viability until 7 days, but the cells cultured on the PLGA/5HAp nanofibers showed a more spreading morphology. Despite the similar level of the cell viability and cell number at each time interval, the alkaline phosphatase secretion was significantly enhanced on the PLGA/5HAp scaffolds, indicating the higher bioactivity of the as-prepared nano-HAp and the success of the present method for preparing biomimetic scaffold for bone regeneration.

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

    PubMed

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

    2017-01-11

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed Central

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

    2017-01-01

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

  2. 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.

  3. Approaching rational epitope vaccine design for hepatitis C virus with meta-server and multivalent scaffolding

    NASA Astrophysics Data System (ADS)

    He, Linling; Cheng, Yushao; Kong, Leopold; Azadnia, Parisa; Giang, Erick; Kim, Justin; Wood, Malcolm R.; Wilson, Ian A.; Law, Mansun; Zhu, Jiang

    2015-08-01

    Development of a prophylactic vaccine against hepatitis C virus (HCV) has been hampered by the extraordinary viral diversity and the poor host immune response. Scaffolding, by grafting an epitope onto a heterologous protein scaffold, offers a possible solution to epitope vaccine design. In this study, we designed and characterized epitope vaccine antigens for the antigenic sites of HCV envelope glycoproteins E1 (residues 314-324) and E2 (residues 412-423), for which neutralizing antibody-bound structures are available. We first combined six structural alignment algorithms in a “scaffolding meta-server” to search for diverse scaffolds that can structurally accommodate the HCV epitopes. For each antigenic site, ten scaffolds were selected for computational design, and the resulting epitope scaffolds were analyzed using structure-scoring functions and molecular dynamics simulation. We experimentally confirmed that three E1 and five E2 epitope scaffolds bound to their respective neutralizing antibodies, but with different kinetics. We then investigated a “multivalent scaffolding” approach by displaying 24 copies of an epitope scaffold on a self-assembling nanoparticle, which markedly increased the avidity of antibody binding. Our study thus demonstrates the utility of a multi-scale scaffolding strategy in epitope vaccine design and provides promising HCV immunogens for further assessment in vivo.

  4. L_RNA_scaffolder: scaffolding genomes with transcripts

    PubMed Central

    2013-01-01

    Background Generation of large mate-pair libraries is necessary for de novo genome assembly but the procedure is complex and time-consuming. Furthermore, in some complex genomes, it is hard to increase the N50 length even with large mate-pair libraries, which leads to low transcript coverage. Thus, it is necessary to develop other simple scaffolding approaches, to at least solve the elongation of transcribed fragments. Results We describe L_RNA_scaffolder, a novel genome scaffolding method that uses long transcriptome reads to order, orient and combine genomic fragments into larger sequences. To demonstrate the accuracy of the method, the zebrafish genome was scaffolded. With expanded human transcriptome data, the N50 of human genome was doubled and L_RNA_scaffolder out-performed most scaffolding results by existing scaffolders which employ mate-pair libraries. In these two examples, the transcript coverage was almost complete, especially for long transcripts. We applied L_RNA_scaffolder to the highly polymorphic pearl oyster draft genome and the gene model length significantly increased. Conclusions The simplicity and high-throughput of RNA-seq data makes this approach suitable for genome scaffolding. L_RNA_scaffolder is available at http://www.fishbrowser.org/software/L_RNA_scaffolder. PMID:24010822

  5. Bone tissue engineering scaffolding: computer-aided scaffolding techniques.

    PubMed

    Thavornyutikarn, Boonlom; Chantarapanich, Nattapon; Sitthiseripratip, Kriskrai; Thouas, George A; Chen, Qizhi

    Tissue engineering is essentially a technique for imitating nature. Natural tissues consist of three components: cells, signalling systems (e.g. growth factors) and extracellular matrix (ECM). The ECM forms a scaffold for its cells. Hence, the engineered tissue construct is an artificial scaffold populated with living cells and signalling molecules. A huge effort has been invested in bone tissue engineering, in which a highly porous scaffold plays a critical role in guiding bone and vascular tissue growth and regeneration in three dimensions. In the last two decades, numerous scaffolding techniques have been developed to fabricate highly interconnective, porous scaffolds for bone tissue engineering applications. This review provides an update on the progress of foaming technology of biomaterials, with a special attention being focused on computer-aided manufacturing (Andrade et al. 2002) techniques. This article starts with a brief introduction of tissue engineering (Bone tissue engineering and scaffolds) and scaffolding materials (Biomaterials used in bone tissue engineering). After a brief reviews on conventional scaffolding techniques (Conventional scaffolding techniques), a number of CAM techniques are reviewed in great detail. For each technique, the structure and mechanical integrity of fabricated scaffolds are discussed in detail. Finally, the advantaged and disadvantage of these techniques are compared (Comparison of scaffolding techniques) and summarised (Summary).

  6. Cardiac tissue engineering in magnetically actuated scaffolds

    NASA Astrophysics Data System (ADS)

    Sapir, Yulia; Polyak, Boris; Cohen, Smadar

    2014-01-01

    Cardiac tissue engineering offers new possibilities for the functional and structural restoration of damaged or lost heart tissue by applying cardiac patches created in vitro. Engineering such functional cardiac patches is a complex mission, involving material design on the nano- and microscale as well as the application of biological cues and stimulation patterns to promote cell survival and organization into a functional cardiac tissue. Herein, we present a novel strategy for creating a functional cardiac patch by combining the use of a macroporous alginate scaffold impregnated with magnetically responsive nanoparticles (MNPs) and the application of external magnetic stimulation. Neonatal rat cardiac cells seeded within the magnetically responsive scaffolds and stimulated by an alternating magnetic field of 5 Hz developed into matured myocardial tissue characterized by anisotropically organized striated cardiac fibers, which preserved its features for longer times than non-stimulated constructs. A greater activation of AKT phosphorylation in cardiac cell constructs after applying a short-term (20 min) external magnetic field indicated the efficacy of magnetic stimulation to actuate at a distance and provided a possible mechanism for its action. Our results point to a synergistic effect of magnetic field stimulation together with nanoparticulate features of the scaffold surface as providing the regenerating environment for cardiac cells driving their organization into functionally mature tissue.

  7. PLDLA/PCL-T Scaffold for Meniscus Tissue Engineering

    PubMed Central

    Moda, Marlon; Cattani, Silvia Mara de Melo; de Santana, Gracy Mara; Barbieri, Juliana Abreu; Munhoz, Monique Moron; Cardoso, Túlio Pereira; Barbo, Maria Lourdes Peris; Russo, Teresa; D'Amora, Ugo; Gloria, Antonio; Ambrosio, Luigi; Duek, Eliana Aparecida de Rezende

    2013-01-01

    Abstract The inability of the avascular region of the meniscus to regenerate has led to the use of tissue engineering to treat meniscal injuries. The aim of this study was to evaluate the ability of fibrochondrocytes preseeded on PLDLA/PCL-T [poly(L-co-D,L-lactic acid)/poly(caprolactone-triol)] scaffolds to stimulate regeneration of the whole meniscus. Porous PLDLA/PCL-T (90/10) scaffolds were obtained by solvent casting and particulate leaching. Compressive modulus of 9.5±1.0 MPa and maximum stress of 4.7±0.9 MPa were evaluated. Fibrochondrocytes from rabbit menisci were isolated, seeded directly on the scaffolds, and cultured for 21 days. New Zealand rabbits underwent total meniscectomy, after which implants consisting of cell-free scaffolds or cell-seeded scaffolds were introduced into the medial knee meniscus; the negative control group consisted of rabbits that received no implant. Macroscopic and histological evaluations of the neomeniscus were performed 12 and 24 weeks after implantation. The polymer scaffold implants adapted well to surrounding tissues, without apparent rejection, infection, or chronic inflammatory response. Fibrocartilaginous tissue with mature collagen fibers was observed predominantly in implants with seeded scaffolds compared to cell-free implants after 24 weeks. Similar results were not observed in the control group. Articular cartilage was preserved in the polymeric implants and showed higher chondrocyte cell number than the control group. These findings show that the PLDLA/PCL-T 90/10 scaffold has potential for orthopedic applications since this material allowed the formation of fibrocartilaginous tissue, a structure of crucial importance for repairing injuries to joints, including replacement of the meniscus and the protection of articular cartilage from degeneration. PMID:23593566

  8. PLDLA/PCL-T Scaffold for Meniscus Tissue Engineering.

    PubMed

    Esposito, Andrea Rodrigues; Moda, Marlon; Cattani, Silvia Mara de Melo; de Santana, Gracy Mara; Barbieri, Juliana Abreu; Munhoz, Monique Moron; Cardoso, Túlio Pereira; Barbo, Maria Lourdes Peris; Russo, Teresa; D'Amora, Ugo; Gloria, Antonio; Ambrosio, Luigi; Duek, Eliana Aparecida de Rezende

    2013-04-01

    The inability of the avascular region of the meniscus to regenerate has led to the use of tissue engineering to treat meniscal injuries. The aim of this study was to evaluate the ability of fibrochondrocytes preseeded on PLDLA/PCL-T [poly(L-co-D,L-lactic acid)/poly(caprolactone-triol)] scaffolds to stimulate regeneration of the whole meniscus. Porous PLDLA/PCL-T (90/10) scaffolds were obtained by solvent casting and particulate leaching. Compressive modulus of 9.5±1.0 MPa and maximum stress of 4.7±0.9 MPa were evaluated. Fibrochondrocytes from rabbit menisci were isolated, seeded directly on the scaffolds, and cultured for 21 days. New Zealand rabbits underwent total meniscectomy, after which implants consisting of cell-free scaffolds or cell-seeded scaffolds were introduced into the medial knee meniscus; the negative control group consisted of rabbits that received no implant. Macroscopic and histological evaluations of the neomeniscus were performed 12 and 24 weeks after implantation. The polymer scaffold implants adapted well to surrounding tissues, without apparent rejection, infection, or chronic inflammatory response. Fibrocartilaginous tissue with mature collagen fibers was observed predominantly in implants with seeded scaffolds compared to cell-free implants after 24 weeks. Similar results were not observed in the control group. Articular cartilage was preserved in the polymeric implants and showed higher chondrocyte cell number than the control group. These findings show that the PLDLA/PCL-T 90/10 scaffold has potential for orthopedic applications since this material allowed the formation of fibrocartilaginous tissue, a structure of crucial importance for repairing injuries to joints, including replacement of the meniscus and the protection of articular cartilage from degeneration.

  9. Strategies for neurotrophin-3 and chondroitinase ABC release from freeze-cast chitosan-alginate nerve-guidance scaffolds.

    PubMed

    Francis, Nicola L; Hunger, Philipp M; Donius, Amalie E; Wegst, Ulrike G K; Wheatley, Margaret A

    2017-01-01

    Freeze casting, or controlled unidirectional solidification, can be used to fabricate chitosan-alginate (C-A) scaffolds with highly aligned porosity that are suitable for use as nerve-guidance channels. To augment the guidance of growth across a spinal cord injury lesion, these scaffolds are now evaluated in vitro to assess their ability to release neurotrophin-3 (NT-3) and chondroitinase ABC (chABC) in a controlled manner. Protein-loaded microcapsules were incorporated into C-A scaffolds prior to freeze casting without affecting the original scaffold architecture. In vitro protein release was not significantly different when comparing protein loaded directly into the scaffolds with release from scaffolds containing incorporated microcapsules. NT-3 was released from the C-A scaffolds for 8 weeks in vitro, while chABC was released for up to 7 weeks. Low total percentages of protein released from the scaffolds over this time period were attributed to limitation of diffusion by the interpenetrating polymer network matrix of the scaffold walls. NT-3 and chABC released from the scaffolds retained bioactivity, as determined by a neurite outgrowth assay, and the promotion of neurite growth across an inhibitory barrier of chondroitin sulphate proteoglycans. This demonstrates the potential of these multifunctional scaffolds for enhancing axonal regeneration through growth-inhibiting glial scars via the sustained release of chABC and NT-3. Copyright © 2014 John Wiley & Sons, Ltd.

  10. Scaffolding Reading Comprehension Skills

    ERIC Educational Resources Information Center

    Salem, Ashraf Atta Mohamed Safein

    2017-01-01

    The current study investigates whether English language teachers use scaffolding strategies for developing their students' reading comprehension skills or just for assessing their comprehension. It also tries to demonstrate whether teachers are aware of these strategies or they use them as a matter of habit. A questionnaire as well as structured…

  11. Aligned carbon nanotube-silicon sheets: a novel nano-architecture for flexible lithium ion battery electrodes.

    PubMed

    Fu, Kun; Yildiz, Ozkan; Bhanushali, Hardik; Wang, Yongxin; Stano, Kelly; Xue, Leigang; Zhang, Xiangwu; Bradford, Philip D

    2013-09-25

    Aligned carbon nanotube sheets provide an engineered scaffold for the deposition of a silicon active material for lithium ion battery anodes. The sheets are low-density, allowing uniform deposition of silicon thin films while the alignment allows unconstrained volumetric expansion of the silicon, facilitating stable cycling performance. The flat sheet morphology is desirable for battery construction.