Recently, more attention has been attracted by intelligent drug delivery systems (DDS), because the release of drug can be controlled via the system feedback responding to pathologic environment signals. Using natural polymers such as chitosan to compose this kind of pulsed DDS will be of benefit, because chitosan [.α(1→4)2-amino-2-deoxy-β-Dglucan] is one of the abundantly available polysaccharides in nature. As we know, chitosan is usually obtained by alkaline deacetylation of chitin, the principal component of shells of