Impact of supramolecular interactions on delivery of dexamethasone from a physical network of gelatin/ZnHAp composite scaffold

Abstract

Synthesis of a supramolecular composite hydrogel, a novel class of physical and dynamic hydrogels, is reported. The hydrogel comprised gelatin (Gel), Zn-doped nano-hydroxyapatite (nZnHAp), and dexamethasone disodium phosphate (DEX). nZnHAp was functionalized with ureidopyrimidinone (UPy; quadruple hydrogen-bond-forming groups). The nHAp, nZnHAp, and nZnHApUPy were characterized by FTIR, EDX, SEM, and TGA analysis. Gelatin was also functionalized with UPy groups (GelUPy), and the nanocomposites were prepared in solution (GelUPy/nZnHApUPy). Dexamethasone was added to the composite hydrogels (15, 20, and 25 wt%), as an osteoinductive and anti-inflammation medicine (GelUPy/nZnHApUPy/DEX). The mechanical (in compression mode), rheological, and thermal properties of the GelUPy/nZnHApUPy/DEX were compared with those of GelUPy/nZnHAp/DEX. The GelUPy/nZnHApUPy/DEX series showed the maximum compressive modulus (about 841 KPa) for GelUPy/nZnHApUPy/DEX25% in the swollen state. DSC analysis indicated that Tg of the pure GelUPy decreased significantly upon composite preparation and drug loading from 160 °C for GelUPy, down to 107 °C for GelUPy/nZnHApUPy/DEX15%. In-vitro drug release studies confirmed sustained release of DEX over a period of 12 days for GelUPy/nZnHApUPy composites with no remarkable initial burst compared to that of the pure GelUPy. Overall, our data suggests that the DEX carrying supramolecular nanocomposite can be used as an osteogenic hydrogel scaffold for bone tissue engineering applications.