Preparation and characterization of micelles of oligomeric chitosan linked to all-trans retinoic acid

New amphiphilic chitosan derivatives of all trans retinoic acid–chitosan (RA–chitosan) with different molar feeding ratios of all trans retinoic acid (ATRA) were synthesized. The degree of ATRA substitution ranged from 8.72% to 18.78%. The RA–chitosan formed micelles with an average size of 142.14–208.4 nm, and zeta potential of +27.25 to 34.48 mV. The critical association concentration (CAC) was found to range from 1.3 × 10−2 to 2.13 × 10−2 mg ml−1. Upon evaluation, the RA–chitosan shows no significant cytotoxicity on Hela and HepG2 cells. Analysis of micelles loaded with ATRA revealed that the size of micelles decreased by increasing loaded drug content while zeta potential did not change. ATRA was released slowly over 3-day period, and drug content had no effect on the release rate. These phenomena make RA–chitosan micelles as a candidate for drug carrier.