LI BOJUN
Email Address
nnilb@nus.edu.sg
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Publication Biomimetic electrospun nanofibers for tissue regeneration(2006-09-01) Liao, S.; Li, B.; Ma, Z.; Wei, H.; Chan, C.; Ramakrishna, S.; ORTHOPAEDIC SURGERY; BIOENGINEERING; MECHANICAL ENGINEERING; NUS NANOSCIENCE & NANOTECH INITIATIVENanofibers 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. © 2006 IOP Publishing Ltd.Publication Collagen solubility testing, a quality assurance step for reproducible electro-spun nano-fibre fabrication. A technical note(2008-10-01) Zeugolis, D.I.; Li, B.; Lareu, R.R.; Chan, C.K.; Raghunath, M.; ORTHOPAEDIC SURGERY; BIOENGINEERING; NUS NANOSCIENCE & NANOTECH INITIATIVECollagen is the main component of the extra-cellular matrix and has been utilised for numerous clinical applications in many forms and products. However, since collagen remains a natural animal-derived biopolymer, variation between batches should be addressed and minimised to ensure reproducibility of the fabrication process. Recently, electro-spinning of collagen has been introduced as a leading technique for the production of bio-mimetic nano-scale scaffolds for tissue-engineering applications. However, no protocols are available that would allow comparisons of the quality of different collagen raw materials prior to the electro-spinning process. In order to bridge this gap we assessed the solubility of various freeze-dried collagens in 0.5 M acetic acid and analysed the solved collagen by gel electrophoresis. We show that raw material of limited solubility in acetic acid will not render high quality electro-spun nano-fibres using hexafluoropropanol. In particular, insoluble collagen directly failed to produce nano-fibres, collagen of reduced solubility produced fused nano-fibres with limited inter-nano-fibre space, whilst purified type-I collagen of high solubility produced smooth, reproducible nano-fibres. Gel electrophoresis confirmed the amount of solubility, as well as qualitative differences in terms of collagen cross-links and collagen types. We recommend this simple and fast step to save costs and to enhance control over the electro-spinning process of collagen. Furthermore, we believe that the solubility test should be introduced prior to any collagenous matrix preparation in order to ensure reproducibility and accuracy. © 2008 VSP.Publication Fabrication of nanofibers with antimicrobial functionality used as filters: Protection against bacterial contaminants(2007-08-15) Lala, N.L.; Ramaseshan, R.; Bojun, L.; Sundarrajan, S.; Barhate, R.S.; Liu, Y.-J.; Ramakrishna, S.; MECHANICAL ENGINEERING; NUS NANOSCIENCE & NANOTECH INITIATIVEA comparative study of antimicrobial activity is done using three different electrospun nanofibers namely - CA, PAN, and PVC used as control and with various amounts of AgNO3 being treated with UV-irradiation leading to the enhancement of silver nanoparticles. DMF is used as the common solvent which helps to undergo spontaneous slow reduction at room temperature to form silver nanoparticles followed by UV-irradiation using a 400 W source. The time required for the formation of silver nanoparticles is short and they are more or less well dispersed with few such aggregates. The presence of silver nanoparticles is confirmed using various characterization techniques. The antimicrobial activity is studied using nanofibers with fabricated functionality. © 2007 Wiley Periodicals, Inc.