Formulation of pH-sensitive aminated chitosan–gelatin crosslinked hydrogel for oral drug delivery

The objective of this study is to develop efficient pH-sensitive hydrogel based on aminated chitosan (AmCs) and gelatin (Gel) biopolymers for oral drug delivery. Herein, AmCs was chemically crosslinked with gelatin (Gel) biopolymer with different ratios, while their structures, thermal profiles and morphological properties were investigated by FTIR, TGA and SEM characterization tools, respectively. Moreover, gel-content, crosslinking density and rheological analysis were also performed. The results clarified that the developed AmCs-Gel crosslinked hydrogel displayed variable pH-sensitive swelling profiles. By increasing AmCs ratio, the swelling ratio was boosted at pH 1.2 and declined at pH 7.4. Besides, by increasing gelatin ratio in the hydrogel matrix, the loading efficiency of Oseltamivir phosphate (as a model of drug) was augmented and reached maximum value of 79.0% by AmCs-Gel (2:3) crosslinked hydrogel. The in vitro drug release profiles were investigated for 6 h in simulated gastric fluid [SGF; pH 1.2] and simulated colon fluid [SCF; pH 7.4]. Variable release profiles were realized depending on variation of AmCs and Gel ratios in the crosslinked hydrogel matrix. Finally, the formulated smart crosslinked AmCs-Gel hydrogels demonstrated acceptable biodegradability with no cellular toxicity, suggesting their applicability as pH-sensitive oral drug carriers.