Preparation and characterization of chitosan-polyvinyl alcohol blend hydrogels for the controlled release of nano-insulin

Chitosan (CS)-polyvinyl alcohol (PVA) blend hydrogels were prepared using glutaraldehyde as the cross-linking agent. The obtained hydrogels, which have the advantages of both PVA and CS, can be used as a material for the transdermal drug delivery (TDD) of insulin. The nano-insulin-loaded hydrogels were prepared under the following conditions: 1.2 g of polyethylene glycol, 1.5 g of CS, 1.2 g of PVA, 1.2 mL of 1% glutaraldehyde solution, 16 mL of water, and 40 mg of nano-insulin with 12 min of mixing time and 3 min of cross-linking time. The nano-insulin-loaded hydrogels were characterized using scanning electron microscopy, energy dispersive spectrometry, Fourier-transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, and its mechanical properties were analyzed. The results show that all molecules in the hydrogel have good compatibility and they formed a honeycomb-like structure. The hydrogel also showed good mechanical and thermal properties. The in vitro drug release of the hydrogel showed that the nano-insulin accorded with Fick's first law of diffusion and it has a high permeation rate (4.421 μg/(cm² h)). These results suggest that the nano-insulin-loaded hydrogels are a promising non-invasive TDD system for diabetes chemotherapy.