The conjugation of chitosan 15 and 100 KD with anticancer drugs cis- and trans-Pt (NH3)2Cl2 (abbreviated cis-Pt and trans-Pt) were studied at pH 5-6. Using multiple spectroscopic methods and thermodynamic analysis to characterize the nature of drug-chitosan interactions and the potential application of chitosan nanoparticles in drug delivery. Analysis showed that both hydrophobic and hydrophilic contacts are involved in drug-polymer interactions, while chitosan size and charge play a major role in the stability of drug-polymer complexes. The overall binding constants are Kch-15-cis-Pt = 1.44 (±0.6) × 105 M-1, Kch-100-cis-Pt = 1.89 (±0.9) × 105 M-1 and Kch-15-trans-Pt = 9.84 (±0.5) × 104 M-1, and Kch-100-trans-Pt = 1.15 (±0.6) × 105 M-1. More stable complexes were formed with cis-Pt than with trans-Pt-chitosan adducts, while stronger binding was observed for chitosan 100 in comparison to chitosan 15 KD. This study indicates that polymer chitosan 100 is a stronger drug carrier than chitosan 15 KD in vitro.
Keywords: chitosan; cis and trans–Pt(II); delivery; loading efficacy; thermodynamic analysis.