Characterization, antimicrobial activity and biocompatibility evaluation of polymer/nano silicate platelet nanocomposites

• Main Authors: Ming-Chien Wang, 王明鍵
• Other Authors: Shenghong A. Dai
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/56779386190381342060

博士 === 國立中興大學 === 化學工程學系所 === 100 === A novel method to exfoliate the montmorillonite clay was developed previously to generate random nano silicate platelets (NSP). They are one kind of delaminated montmorillonite particles (DMtP) and one-dimensional nanomaterials in geometry. NSP were dispersed in water and mixed with waterborne polymer. To improve their dispersion in a polymer, NSP were modified by three types of surfactants (cationic Qa, nonionic Qb and anionic Qc) in this study. The zeta potential, antimicrobial ability and biocompatibility of NSQ were characterized. It was found that the zeta potential of NSQa was positive while those of NSP and the other two NSQ (NSQb and NSQc) were negative. All NSQ presented less cytotoxicity than NSP. NSQa and NSQc showed excellent antimicrobial activities against S. aureus (Gram-positive strain) and E. coli (Gram-negative strain). NSP and these surfactant modified NSP (abbreviated “NSQ”) were further used to prepare polymer nanocomposites in this study. In the first part, water dispersible NSP were mixed with Chitosan (CS) acetic acid solution to form CS/SNP nanocomposites. The dispersion of NSP in the CS matrix was good, probably as a result of the charge interaction between the two components. The CS/NSP demonstrated better dynamic mechanical moduli. NSP were found to be enriched on the surface of the nanocomposites when the amount of NSP was > 103 ppm. This was accompanied by a decrease of the contact angle. The proliferation of fibroblasts on CS/NSP 103 ppm was significantly greater than on other materials. The antimicrobial activity was enhanced markedly with the increased amount of NSP in CS/NSP. The inflammatory responses of NSP in vitro and in subcutaneous rats were not obvious until the concentration of NSP was > 103 ppm. The biocompatibility of CS/NSP 103 ppm was even better than that of CS. The biodegradation rate of the CS/NSP nanocomposite was much faster than that of the pure CS polymer. In the second part, organic solvent dispersible NSQ were mixed with polyurethane (PU) in dimethylacetamide to form PU/NSQ nanocomposites. The nanocomposites were then characterized for surface and mechanical properties, cell attachment and proliferation, antimicrobial activity in vitro and biocompatibility in vivo. A higher surfactant to NSP ratio was found to improve the dispersion of NSQ in PU matrix. The mechanical properties of all PU/NSQ nanocomposites were significantly enhanced. Among various NSQ, only NSQa were observed to migrate to the composite surface. The attachment and proliferation of endothelial cells and fibroblasts in vitro as well as biocompatibility in vivo were significantly better for PU/NSQa containing 1% of NSQa than other materials. The microbiostasis ratios of PU/NSQ nanocomposites containing 1% NSQa or NSQc were over 99%. Taken together, these results suggested safety and potential antimicrobial applications of biodegradable or biodurable polymer/NSP nanocomposites, especially 0.1% CS/NSP and 1% PU/NSQa nanocomposites.