Self-aggregation behavior of alkylated chitosan and its effect on the release of a hydrophobic drug.

Chitosan (CS) was hydrophobically modified with butyl bromide and dodecyl bromide. The self-aggregation in acetic acid solution was characterized by fluorescence spectroscopy and dynamic light-scattering method. The results indicate that introducing butyl and dodecyl moieties leads to the formation of self-aggregates. Along with the enhancement in the hydrophobicity of chitosan the self-association occurs at a lower concentration, and the mean size of self-aggregates increases. The loading capacity of butylated chitosan (4-CS) and dodecylated chitosan (12-CS) for vitamin B2 are markedly increased compared to that of chitosan, and the release of drug from alkylated chitosans is somewhat hindered due to its increased affinity for hydrophobic carriers.