Vanillin crosslinked chitosan films: The states of water and the effect of carriers on curcumin uptake

In this work, chitosan chains were crosslinked with different contents of vanillin (Van), characterized and loaded with curcumin (CUR), a hydrophobic drug. Sodium dodecyl sulfate (SDS), Tween 20 (R) (T20) and beta-cyclodextrin (beta CD) were used as curcumin carriers. Films prepared with Van 20 % yielded gel content of 70 %, swelling degree of similar to 23 g(water)/g, bound water and capillary water, as revealed by Time-Domain Nuclear Magnetic Resonance measurements. Films prepared with higher Van contents showed small swelling degree (< 1.6 g(water)/g) and hydrophobicity, making them inadequate for drug loading. UV-Vis and fluorescence spectroscopic studies indicated that Van 20 % combined with SDS and SDS/beta CD presented the highest CUR uptake (similar to 3.0 mg/g), favored by electrostatic interactions and hydrophobic interactions. CHI and Van 20 % films did not present any cytotoxicity in human neuroblastoma SH-SY5Y cells. At pH 1.0 the films were completely soluble, pointing to their potential application as gastric delivery systems for hydrophobic drugs. Chemical compounds studied in the manuscript: Chitosan, vanillin, curcumin, beta-cyclodextrin, sodium dodecyl sulfate, polyethylene glycol sorbitan monolaurate.