C. W. Chung1, H. W. Kim1,2, M. G. Chung1, and Y. H. Rhee1
1 Department of Microbiology, Chungnam National University, Daejeon 305-764, Korea
2 Institute of Biotechnology, Chungnam National University, Daejeon 305-764, Korea
Keywords: Biocompatibility, Chemical modification, Crosslink, Polyhydroxyalkanoate
Recently, due to their potential biodegradability and biocompatibility, bacterial polyhydroxyalkanoates (PHAs) have attracted significant commercial attention as potential new functional biomaterials for medical applications. In particular, PHAs containing unsaturated groups, such as C=C and CºC bonds, are of great interest because they can easily be modified by photochemical reactions. Crosslinking is a well-known method used to control polymer properties and generally leads to a more uniform polymer matrix with alternative physico-chemical properties. Crosslinking of unsaturated PHAs is expected to yield useful materials, such as biodegradable and biocompatible rubbers. It is also expected that crosslinked PHAs are less susceptible to biodegradation.
In this study, we describe the preparation of polymers with improved mechanical properties by thermal crosslinking of an unsaturated PHA and the biocompatibilities of resulting polymers. An amorphous MCL-PHA consisting of 90 mol% unsaturated repeating units, which possesses the number average molecular weight of approximately 50000, was produced by P. oleovorans ATCC 29347 from a mixture of 10% nonanoic acid and 90% 10-undecenoic acid. The unsaturated PHA was crosslinked by heating in the presence of 10 wt% benzoylperoxide as a cross-linker. Water contact angle and adhesive force of prepared film surfaces were measured by a sessile drop method and peel test, respectively. The surface of film was analyzed by electron element (ESCA). The material properties of the crosslinked PHAs (CL-PHAs) were determined by using differential scanning calorimetric, atomic force microscopy and thermogravimetric analyses as well as instron. The degree of crosslinking of the polymers was measured by FT-IR. In order to evaluate the cell and blood compatibility of the CL-PHAs, the cellular behavior of Chinese hamster ovary (CHO) cells and platelet-surface interaction on CL-polymers were investigated and compared to that on the original polymer. Of the PHAs tested, the CL-PHA with 50% of crosslinking density was the most biocompatible for CHO cells, and this CL-PHA was also found to be more biocompatible than poly(L-lactide). In addition, the increase of crosslinking density of the polymers resulted in the decrease of cell and platelet adhesion on the surface of polymer films. The results indicated that some CL-PHAs prepared in this study were very suitable as biocompatible materials for various biomedical applications.
[1] Williams, S.F., et al., 1999. Int. J. Biol. Macromol. 25, 111.
[2] Kim, D.Y., et al., 1998. Macromolecules 31, 4760.
[3] Chung, C.W., et al., 2003. Int. J. Biol. Macromol. 32, 17.
论文来源：International Symposium on Biological Polyesters ,Auguest 22-27, 2004
