Enzymatic degradation of ultrathin multilayer films composed of polysaccharides

Layer-by-layer assembled films between chitosan and alginic acid were prepared at 4°C by stepwise immersion of substrates into their aqueous solutions of 25 % formic acid and water, respectively. Then, the films were immersed in chitosanase acetate buffer solution at 37°C immediately. Chitosanase was electrostatically adsorbed onto multilayers ending alginic acid, since the enzyme was cationically charged in acetate buffer at pH 5.6 (pi of the enzyme = 9.3). Multilayers ending alginic acid prepared from the alginic acid solution at pH 7 were more rapidly desorbed by chitosanase than ending chitosan. On the other hand, the desorption rate of the multilayers were independent of the outermost surface when prepared from at pH 4.