Preparation of Carboxymethyl-chitin Nanoparticles by Covalent Crosslinking and Their In Vitro Evaluation

The degree of deacetylation and molecular weight of carboxymethyl-chitin (CM) were manipulated using 10% (w/v) NaOH aqueous solution at 25˚C and 5 M HCl aqueous solution at 40˚C, respectively. The resultant CMs were char- acterized by 1 H-NMR spectroscopy and size exclusion chromatography/multi-angle light scattering. The degree of deace- tylation of 7 - 35% (mol/mol) and molecular weight of 43,000 - 449,000 were achieved. Nanoparticles were prepared us- ing W/O emulsification and amide coupling. Nanoparticles with the size of less than 400 nm were obtained using CM with a high degree of deacetylation and low molecular weight, CM48-L. When the mixture of CM-mitomycin C conjugate and CM48-L underwent W/O emulsification and amide coupling, nanoparticles with the size of ca. 350 nm were obtained, and released mitomycin C fairly fast but gradually. CM with a high degree of deacetylation and low molecular weight was suggested to be useful for the production of CM nanoparticles.