Influence of the composition and preparation method on the morphology and swelling behavior of alginate-chitosan hydrogels

In this study, a 24 factorial experimental design was employed in order to evaluate the influence of the reaction conditions and preparation method on alginate-chitosan hydrogel properties. Alginate content, pH, chitosan molecular weight and the hydrogel preparation method were the independent variables and the reaction yield, particle size, swelling degree and point of zero surface charge were the dependent variables. The results showed that hydrogels were spherical with an average diameter of 5.0 +/- 2.0 mu m. Reaction yield varied according to the parameters, and chitosan molecular weight showed the greatest influence. Furthermore, the swelling degree and point of zero surface charge showed a linear dependence on the alginate content. In this regard, the study showed that hydrogels with a specific charge and swelling degree can be obtained by controlling the alginate content using the equation here provided to give an enhanced and site-specific controlled drug release. (C) 2008 Elsevier Ltd. All rights reserved.