Gelatin/dextran-based hydrogel cross-linked by Diels–Alder click chemistry: the swelling and potassium diclofenac releasing

Abstract

In the present work, gelatin and dextran were derivatized in order to obtain a chemically cross-linked hydrogel by Diels–Alder click chemistry reaction. The main interest in cross-linking by the Diels–Alder reaction is the absence of by-products and mild synthetic conditions, being a great advantage for biomedical applications. Thus, maleic anhydride (MA) and 2-furoic acid (FA) were successfully grafted onto gelatin and dextran, respectively, making available the diene and dienophile groups for further cross-linking. The derivatization was evaluated by nuclear magnetic resonance (NMR) spectroscopy, size-exclusion chromatography (SEC) and differential scanning calorimetry (DSC). The Diels–Alder cross-linking was confirmed by UV/Vis spectroscopy, and hydrogel behaviour was evaluated by rheological measurements. The hydrogel swelling properties and the cumulative release profile of diclofenac potassium (DFK) were studied in different dissolution media. The increase in swelling capacity was followed by faster DFK releasing from the platform, being the gelatin/dextran-based Diels–Alder click hydrogel suitable for biomedical applications.