Homogeneous preparation of water-soluble products from chitin under alkaline conditions and their cell proliferation in vitro

Abstract

The purpose of this study was to prepare water-soluble products by homogeneous depolymerization of chitin with H2O2 under alkaline conditions and investigate their potential application in wound healing. For the first time, water-soluble products were successfully prepared using a chitin-NaOH/urea solution; the products were chitosans with molecular weights (Mw) of 3.48–33.5 kDa and degrees of deacetylation (DD) > 0.5. Their Mw, DD and yield were affected by the reaction temperature, reaction time, concentration of H2O2 and chitin DD. The deacetylation and depolymerization of chitin were achieved simultaneously. The depolymerization of chitin was caused by hydrogen abstraction of HO, whereas the deacetylation resulted from the cleavage of amide bonds by HO− and HO2−, although the latter played a more important role. All water-soluble chitosans markedly promoted the proliferation of human skin fibroblast (HSF) cells, but they inhibited the proliferation of human keratinocyte cells. For the proliferation of HSF, a low concentration of chitosans was important. In addition, water-soluble chitosans with an Mw of 3.48–16.4 kDa markedly stimulated the expression of growth factors such as PDGF and TGF-β by macrophages. Water-soluble chitosans could be used as a potential active component in wound dressings.