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2014-05-04 13:15  
讲座题目:Towards water-dispersible boron nitride nanotubes: thorough wrapping of polysaccharides on nanotubes by glycine-assisted interfacial assembly
主讲人:Dr. Yiu Ting Richard Lau
Nano and Advanced Materials Institute
Hong Kong Science Park, Shatin, Hong Kong
主办方:西安交大-香港科大可持续发展ag网站亚游登录 & 西安交大化学工程与技术ag网站亚游登录
地点:西安交大行政主楼B座 B-104
讲座摘要:BNNT has an analogous structure and isoelectronicity to a carbon nanotube (CNT) but displays more interesting features, such as high thermal conductivity, high-temperature oxidation resistance, controlled wettability, neutron capture, etc. However, the intrinsic entanglement and self-aggregation behavior of the BNNTs into bundles will limit their uses by hampering the material preparation and lowering their loading capacities as storage materials if these nanotubes are not well dispersed in a physiological medium for biological purposes. Much research effort has been made in improving the dispersity of BNNTs in solvents by surface functionalization and modification. Furthermore, there has been a wide controversy on the cytotoxicity of the BNNTs in the scientific community. Both positive and negative effects have been reported. Many factors, such as dimensionality, purity, aggregation, coating chemistry, cell line, on the biocompatibility of the BNNTs have been suggested. However, there were no related studies and discussions have been made so far on the coating uniformity and morphology, which may instigate remarkable implications for the equivocal results made in the biocompatibility studies on the BNNTs.
Our developed methodology1 offers a rapid, mild, and scalable route for debundling of BNNTs into water-disprersible biofunctional BNNTs that may serve as drug delivery vehicles or scaffolds in tissue engineering with the following advantages: (a) all-room-temperature process (b) aqueous-based (c) green process: no acid or oxidant pretreatment and (d) obtaining only nanotubes (~10 ?m) uniformly coated with either cationic or anionic or zwitterionic polysaccharides, such as chitosan, hyaluronic acid and phoshorylcholine-substituted chitosan. As illustrated in Figure 1, the method requires three major steps: (1) glycine adsorption (2) addition of the polysaccharide and finally (3) isolation of the uniformly coated nanotubes from the coarsely coated ones via an oil/water interfacial treatment step. The complete coverage of the polymer on the BNNT has relevant implications in the fabrication of nanohybrid materials for biological functions, such as minimizing any possible influential effects that can be introduced from a barely exposed surface of a coarsely-coated BNNT in a physiological environment. Our result had turned theoretical calculations into practice whereby the amine terminal of glycine binds to the B-sites of BNNTs, while the carboxylic acid terminal provides ionic anchoring sites for interactions with polyelectrolytes. Moreover, this was also the first report on the potential capability of the biofunctional BNNT as a Pickering emulsifier where such a unique property was successfully harnessed for length fractionation.2
Dr. Richard Lau received his PhD degrees from the Hong Kong University of Science and Technology (HKUST) under the supervision of Professor Chi Ming Chan. His research focused on the applications of ToF-SIMS in polymer surface determination, where his contributions to SIMS development were recognized by the International Scientific Committee in SIMS which granted him two awards: the Best Paper Award and the SIMS Best Paper Award on international meetings in 2007 and 2009, respectively. Later, he was granted with the Air Products Award from the HKUST in 2010. After his PhD graduation, he continued his postdoctoral research with Professor Francoise M. Winnik on hybrid bionanomaterials in the International Center for Nanoarchitectonics (MANA) of the National Institute for Materials Science (NIMS) in Japan. Currently, he is working in the Bio and Healthcare Sector of the Nano and Advanced Materials Institute (NAMI), one of the five R&D centres under the Innovation and Technology Commission of the Hong Kong Government. He is now managing an applied research project in collaboration with an industrial sponsor on the development of a whole-blood microfluidic biochip on ultrasensitive detection of influenza.
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