Chitosan-alginate films prepared with chitosans of different molecular weights

Chitosan-alginate polyelectrolyte complex (CS-AL PEG) is water insoluble an d more effective in limiting the release of encapsulated materials compared to chitosan or alginate, Coherent CS-AL PEC films have been prepared in ou r laboratory hy casting and drying suspensions of chitosan-alginate coacerv ates. The objective of this study was to evaluate the properties of the CS- AL PEC films prepared with chitosans of different molecular weights. Films prepared with low-molecular-weight chitosan (M-v 1.30 x 10(5)) were twice a s thin and transparent, as well as 55% less permeable to water vapor, compa red to films prepared with high-molecular-weight chitosan (M-v 10.0 x 10(5) ), It may be inferred that the low-molecular-weight chitosan reacted more c ompletely with the sodium alginate (M-v 1.04 x 10(5)) than chitosan of high er molecular weight. A threshold molecular weight may be required, because chitosans of M-v 10.0 x 10(5) and 5.33 x 10(5) yielded films with similar p hysical properties. The PEC films exhibited different surface properties fr om the parent films, and contained a higher degree of chain alignment with the possible formation of new crystal types. The PEC films exhibited good i n vitro biocompatibility with mouse and human fibroblasts, suggesting that they can be further explored for biomedical applications. (C) 2001 John Wil ey & Sons. Inc.