In vitro drug release kinetics

The release kinetics of CUR from single- (gel+CD-CUR and gel+CUR) and dual-drug-loaded hydrogels (gel+DOX+CD-CUR) were determined in vitro. Single-drug-loaded hydrogels were incubated with 3 ml PBS (pH 7.4) or PBS (pH 7.4) containing Tween-80 (1% wt), while the dual-drug-loaded hydrogel was only incubated with PBS (pH 7.4). The samples were transferred to a shaker at 1.6 × g for 5 min at 37°C. At predetermined time intervals, 2 ml released medium was removed and an equal volume of fresh medium was re-added into the vials. The DOX release kinetics of gel+DOX and gel+DOX+CD-CUR were determined in unique PBS (pH 7.4) medium.

The amount of released CUR was measured by the method described by Gerola et al (28). The released medium was mixed with an equal volume of tetrahydrofuran (50% v/v) and the absorbance was measured by a UV spectrophotometer at 425 nm. The amount of released DOX was determined by fluorescence measurements at an excitation wavelength of 488 nm. Each experiment was performed in triplicate.