ABSTRACT
Chitosan displays interesting properties such as biocompatibility and biodegradability, and its degradation products are nontoxic, nonimmunogenic, and noncarcinogenic. Therefore, chitosan has prospective applications in many ‰elds such as biomedicine, waste water treatment, functional membranes, and ©occulation. However, the commercial or practical use of chitin and chitosan (including monomers and oligomers) has been con-‰ned to the unmodi‰ed forms. For a breakthrough in utilization, chemical modi‰cation to introduce a variety of functional groups will be a key point. For this purpose, more fundamental studies on chemical modi‰cation will be required. Fortunately, chitosan is an amenable molecule. Without disturbing the degree of polymerization (DP) of chitosan, one can chemically modify this acquiescent polymer because it provides functional groups as primary amine and primary as well as secondary hydroxyl groups in its monomers.
