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Seeram Ramakrishna - One of the best experts on this subject based on the ideXlab platform.

  • Electrospun Composite Nanofibers for Tissue Regeneration
    Journal of Nanoscience and Nanotechnology, 2011
    Co-Authors: Molamma P. Prabhakaran, Laleh Ghasemi-mobarakeh, Seeram Ramakrishna
    Abstract:

    Nanotechnology assists in the development of biocomposite nanofibrous scaffolds that can react positively to changes in the immediate cellular environment and stimulate specific regenerative events at molecular level to generate healthy tissues. Recently, electrospinning has gained huge momentum with greater accessibility of fabrication of composite, controlled and oriented nanofibers with sufficient porosity required for effective tissue regeneration. Current developments include the fabrication of nanofibrous scaffolds which can provide chemical, mechanical and biological signals to respond to the environmental stimuli. These nanofibers are fabricated by simple coating, blending of polymers/bioactive molecules or by surface modification methods. For obtaining optimized sur-face functionality, with specially designed architectures for the nanofibers (multi-layered, core–shell, aligned), electrospinning process has been modified and simultaneous 'electrospin-electrospraying' process is one of the most lately introduced technique in this perspective. Properties such as poros-ity, biodegradation and mechanical properties of composite Electrospun nanofibers along with their utilization for nerve, cardiac, bone, skin, vascular and cartilage tissue engineering are discussed in this review. In order to locally deliver electrical stimulus and provide a physical template for cell proliferations, and to gain an external control on the level and duration of stimulation, electrically conducting polymeric nanofibers are also fabricated by electrospinning. Electrospun polypyrrole (PPy) and polyaniline (PAN) based scaffolds are the most extensively studied composite substrates for nerve and cardiac tissue engineering with or without electrical stimulations, and are discussed here. However, the major focus of ongoing and future research in regenerative medicine is to effec-tively exploit the pluripotent potential of Mesenchymal Stem Cell (MSC) differentiation on composite nanofibrous scaffolds for repair of organs.

  • Processing nanoengineered scaffolds through electrospinning and mineralization suitable for biomimetic bone tissue engineering
    Journal of the Mechanical Behavior of Biomedical Materials, 2008
    Co-Authors: Susan Liao, Ramaswamy Murugan, Casey K Chan, Seeram Ramakrishna
    Abstract:

    Processing scaffolds that mimic the extracellular matrix (ECM) of natural bone in structure and chemical composition is a potential promising option for engineering physiologically functional bone tissue. In this article, we report a novel method, by combining electrospinning and mineralization, to process a series of nano-fibrous scaffolding systems with desirable characteristics suitable for biomimetic bone tissue engineering. We have chosen two types of polymers, namely collagen and poly (lactic-co-glycolic acid) (PLGA), natural and synthetic of its kind, respectively, to electrospin into nano-fibrous scaffolds. The Electrospun scaffolds have high surface area, high porosity and well connected open pore network. In order to mimic the chemical composition of native bone ECM, the Electrospun scaffolds were subjected to mineralization under optimal conditions. From the experimental results, we observed that the formation of bone-like apatite into collagen was relatively abundant and significantly more uniform than PLGA. The major finding of this study has suggested that the surface functional groups of the scaffolding material, such as carboxyl and carbonyl groups of collagen, are important for the mineralization in vitro. In addition, this study revealed that the mineralization process predominantly induce the formation of nanosize carbonated hydroxyapatite (CHA) during collagen mineralization, whilst nanosize hydroxyapatite (HA) is formed during PLGA mineralization. These findings are critically important while selecting the material for processing bone scaffolding system. © 2008 Elsevier Ltd. All rights reserved.

  • Electrospun nanofibrous filtration membrane
    Journal of Membrane Science, 2006
    Co-Authors: Renuga Gopal, Casey K Chan, Seeram Ramakrishna, Satinderpal Kaur, Takeshi Matsuura
    Abstract:

    This paper explores the viability of developing a fibrous membrane via Electrospun nanofibrous web for liquid separation and demonstrates its applicability in particulate removal. Polyvinylidene fluoride nanofibers were Electrospun into membranes and characterized to relate its structural properties to membrane separation properties and performance. Characterization of these Electrospun membranes revealed that they have similar properties to that of conventional microfiltration membranes. The Electrospun membranes were used to separate 1, 5 and 10 μm polystyrene particles. The Electrospun membranes were successful in rejecting more than 90% of the micro-particles from solution. This work opens up the avenue of exploring the use of nanofibers for more mainstream application in the separation technology as a potential membrane for pre-treatment of water prior to reverse osmosis or as pre-filters to minimize fouling and contamination prior to ultra- or nano-filtration.

  • Biomimetic Electrospun nanofibers for tissue regeneration
    Biomedical Materials, 2006
    Co-Authors: Susan Liao, Casey K Chan, Bojun Li, Zuwei Ma, Seeram Ramakrishna
    Abstract:

    Nanofibers exist widely in human tissue with different patterns. Electrospinning nanotechnology has recently gained a new impetus due to the introduction of the concept of biomimetic nanofibers for tissue regeneration. The advanced electrospinning technique is a promising method to fabricate a controllable continuous nanofiber scaffold similar to the natural extracellular matrix. Thus, the biomedical field has become a significant possible application field of Electrospun fibers. Although electrospinning has developed rapidly over the past few years, Electrospun nanofibers are still at a premature research stage. Further comprehensive and deep studies on Electrospun nanofibers are essential for promoting their biomedical applications. Current Electrospun fiber materials include natural polymers, synthetic polymers and inorganic substances. This review briefly describes several typically Electrospun nanofiber materials or composites that have great potential for tissue regeneration, and describes their fabrication, advantages, drawbacks and future prospects.

  • Electrospinning and mechanical characterization of gelatin nanofibers
    Polymer, 2004
    Co-Authors: Zheng Ming Huang, Seeram Ramakrishna, Y. Z. Zhang, C. T. Lim
    Abstract:

    This paper investigates electrospinning of a natural biopolymer, gelatin, and the mass concentration-mechanical property relationship of the resulting nanofiber membranes. It has been recognized that although gelatin can be easily dissolved in water the gelatin/water solution was unable to electrospin into ultra fine fibers. A different organic solvent, 2,2,2-trifluoroethanol, is proven suitable for gelatin, and the resulting solution with a mass concentration in between 5 and 12.5% can be successfully Electrospun into nanofibers of a diameter in a range from 100 to 340 nm. Further lower or higher mass concentration was inapplicable in electrospinning at ambient conditions. We have found in this study that the highest mechanical behavior did not occur to the nanofibrous membrane Electrospun from the lowest or the highest mass concentration solution. Instead, the nanofiber mat that had the finest fiber structure and no beads on surface obtained from the 7.5% mass concentration exhibited the largest tensile modulus and ultimate tensile strength, which are respectively 40 and 60% greater than those produced from the remaining mass concentration, i.e. 5, 10, and 12.5%, solutions. © 2004 Elsevier Ltd. All rights reserved.

Benjamin S. Hsiao - One of the best experts on this subject based on the ideXlab platform.

  • functional Electrospun nanofibrous scaffolds for biomedical applications
    Advanced Drug Delivery Reviews, 2007
    Co-Authors: Dehai Liang, Benjamin S. Hsiao
    Abstract:

    Functional nanofibrous scaffolds produced by electrospinning have great potential in many biomedical applications, such as tissue engineering, wound dressing, enzyme immobilization and drug (gene) delivery. For a specific successful application, the chemical, physical and biological properties of Electrospun scaffolds should be adjusted to match the environment by using a combination of multi-component compositions and fabrication techniques where electrospinning has often become a pivotal tool. The property of the nanofibrous scaffold can be further improved with innovative development in electrospinning processes, such as two-component electrospinning and in-situ mixing electrospinning. Post modifications of Electrospun membranes also provide effective means to render the Electrospun scaffolds with controlled anisotropy and porosity. In this article, we review the materials, techniques and post modification methods to functionalize Electrospun nanofibrous scaffolds suitable for biomedical applications.

  • Functional Electrospun nanofibrous scaffolds for biomedical applications
    Advanced Drug Delivery Reviews, 2007
    Co-Authors: Dehai Liang, Benjamin S. Hsiao, Benjamin Chu
    Abstract:

    Functional nanofibrous scaffolds produced by electrospinning have great potential in many biomedical applications, such as tissue engineering, wound dressing, enzyme immobilization and drug (gene) delivery. For a specific successful application, the chemical, physical and biological properties of Electrospun scaffolds should be adjusted to match the environment by using a combination of multi-component compositions and fabrication techniques where electrospinning has often become a pivotal tool. The property of the nanofibrous scaffold can be further improved with innovative development in electrospinning processes, such as two-component electrospinning and in-situ mixing electrospinning. Post modifications of Electrospun membranes also provide effective means to render the Electrospun scaffolds with controlled anisotropy and porosity. In this article, we review the materials, techniques and post modification methods to functionalize Electrospun nanofibrous scaffolds suitable for biomedical applications. © 2007 Elsevier B.V. All rights reserved.

Chwee Teck Lim - One of the best experts on this subject based on the ideXlab platform.

  • Fabrication of Large Pores in Electrospun Nanofibrous Scaffolds for Cellular Infiltration: A Review
    Tissue Engineering Part B: Reviews, 2012
    Co-Authors: Shaoping Zhong, Yanzhong Zhang, Chwee Teck Lim
    Abstract:

    In the past decade, considerable effort has been made to construct biomimetic scaffolds from Electrospun nanofibers for engineering different tissues. However, one of the major concerns with Electrospun nanofibrous scaffolds is that the densely arranged architecture of fibers and small pores or voids between fibers hinder efficient cellular infiltration or prevent three dimensional (3D) cellular integration with host tissue in vivo after implantation. To overcome this problem, many concepts or strategies applicable during the electrospinning or post-electrospinning procedures have been proposed to enlarge pore size of Electrospun scaffolds. This article addresses the issues of pore geometry and cellular infiltration of Electrospun scaffolds, and first reviews the fabrication solutions/approaches applied to achieve larger micropores in Electrospun mats. The evidence and potential for fostering cellular infiltration using these improved porous scaffolds are then discussed. Finally, it is hoped that this will enable us to better exploit viable technologies or develop new ones for constructing ideal nanofibrous architecture for fulfilling specific tissue engineering needs.

Dehai Liang - One of the best experts on this subject based on the ideXlab platform.

  • functional Electrospun nanofibrous scaffolds for biomedical applications
    Advanced Drug Delivery Reviews, 2007
    Co-Authors: Dehai Liang, Benjamin S. Hsiao
    Abstract:

    Functional nanofibrous scaffolds produced by electrospinning have great potential in many biomedical applications, such as tissue engineering, wound dressing, enzyme immobilization and drug (gene) delivery. For a specific successful application, the chemical, physical and biological properties of Electrospun scaffolds should be adjusted to match the environment by using a combination of multi-component compositions and fabrication techniques where electrospinning has often become a pivotal tool. The property of the nanofibrous scaffold can be further improved with innovative development in electrospinning processes, such as two-component electrospinning and in-situ mixing electrospinning. Post modifications of Electrospun membranes also provide effective means to render the Electrospun scaffolds with controlled anisotropy and porosity. In this article, we review the materials, techniques and post modification methods to functionalize Electrospun nanofibrous scaffolds suitable for biomedical applications.

  • Functional Electrospun nanofibrous scaffolds for biomedical applications
    Advanced Drug Delivery Reviews, 2007
    Co-Authors: Dehai Liang, Benjamin S. Hsiao, Benjamin Chu
    Abstract:

    Functional nanofibrous scaffolds produced by electrospinning have great potential in many biomedical applications, such as tissue engineering, wound dressing, enzyme immobilization and drug (gene) delivery. For a specific successful application, the chemical, physical and biological properties of Electrospun scaffolds should be adjusted to match the environment by using a combination of multi-component compositions and fabrication techniques where electrospinning has often become a pivotal tool. The property of the nanofibrous scaffold can be further improved with innovative development in electrospinning processes, such as two-component electrospinning and in-situ mixing electrospinning. Post modifications of Electrospun membranes also provide effective means to render the Electrospun scaffolds with controlled anisotropy and porosity. In this article, we review the materials, techniques and post modification methods to functionalize Electrospun nanofibrous scaffolds suitable for biomedical applications. © 2007 Elsevier B.V. All rights reserved.

D. G. Simpson - One of the best experts on this subject based on the ideXlab platform.

  • 094 Electrospun Collagen in Dermal Regeneration
    Wound Repair and Regeneration, 2008
    Co-Authors: J.r. Bowan, Gary L Bowlin, C.e. Ayers, R Diegelman, D. G. Simpson
    Abstract:

    Electrospinning is a nonmechanical processing strategy that is used to fabricate tissue-engineering scaffolds composed of submicron diameter, banded fibrils of collagen. In biocompatibility tests these fibers are nonimmunogenic. Fiber diameter can be manipulated over a wide range by regulating the concentration of collagen present in the starting electrospinning solutions. Table 1 illustrates average fiber diameters and pore dimensions achieved under different conditions. Collagen Concentration Fiber Diameter Pore Area 40 mgs/ml TFE    113 ± 51 nm     184 ± 87.6 nm2 60 mgs/ml TFE    304 ± 120 nm  1,311 ± 384 nm2 80 mgs/ml TFE    761 ± 276 nm  4,913 ± 3978 nm2 100 mgs/ml TFE    745 ± 314 nm  5,039 ± 2947 nm2 120 mgs/ml TFE 1,534 ± 448 nm 19,154 ± 20809 nm2 We prepared four 1 cm2 full thickness dermal injuries on the dorsum of the guinea pig. Electrospun scaffolds composed of different fiber diameters were cut to fit the defects, sutured in place and then recovered at 7 and 14 days. Injuries treated with scaffolds composed of Electrospun collagen fibers greater than 300 nm in diameter exhibited extensive tongue formation, dense dermal cell infiltration and functional capillary beds. Dermal regeneration was substantially complete by 14 days. Scaffolds prepared with individual fiber diameters of less than 300 nm were well epithelialized but, less densely "populated by dermal fibroblasts and capillaries. Fibrils of Electrospun gelatin, a collagen isolate that is heat denatured prior to electrospinning, lack the banded appearance of Electrospun collagen. Scaffolds of Electrospun gelatin were less densely infiltrated than Electrospun collagen at all fiber diameters and pore dimensions, and induced inflammation. We conclude that banded fibrils of Electrospun collagen have unique biological activity. Funded in part NIH R01 EB003087. US & International Patents Issued and Pending.

  • Regulation of cellular infiltration into tissue engineering scaffolds composed of submicron diameter fibrils produced by electrospinning
    Acta Biomaterialia, 2005
    Co-Authors: Todd A. Telemeco, C. M. Baumgarten, J. Mathews, Chantal Ayres, Gary E. Wnek, Gary L Bowlin, N Cohen, Eugene D. Boland, D. G. Simpson
    Abstract:

    We characterize the infiltration of interstitial cells into tissue engineering scaffolds prepared with Electrospun collagen, Electrospun gelatin, Electrospun poly(glycolic) acid (PGA), Electrospun poly(lactic) acid (PLA), and an Electrospun PGA/PLA co-polymer. Electrospinning conditions were optimized to produce non-woven tissue engineering scaffolds composed of individual fibrils less than 1000 nm in diameter. Each of these materials was then Electrospun into a cylindrical construct with a 2 mm inside diameter with a wall thickness of 200-250 μm. Electrospun scaffolds of collagen were rapidly, and densely, infiltrated by interstitial and endothelial cells when implanted into the interstitial space of the rat vastus lateralis muscle. Functional blood vessels were evident within 7 days. In contrast, implants composed of Electrospun gelatin or the bio-resorbable synthetic polymers were not infiltrated to any great extent and induced fibrosis. Our data suggests that topographical features, unique to the Electrospun collagen fibril, promote cell migration and capillary formation. © 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.