Encapsulation of allopurinol by glucose cross-linked gelatin/zein nanofibers: Characterization and release behavior

In this study, various concentrations of allopurinol were encapsulated into the glucose cross-linked gelatin/zein (1:1, w/w) nanofibers. The encapsulation of allopurinol did not affect the production of smooth and uniform nanofibers. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) revealed the hydrogen bonding interactions between allopurinol and proteins. The homogenous dispersion of allopurinol at concentrations of 2.5% (A2.5), 5% (A5), and 10% (A10) was observed, while phase separation happened at a concentration of 20% (A20) allopurinol by recrystallization. The nanofiber wettability was significantly increased for the A2.5 and A5 fibers, but the wettability of the A10 and A20 fibers was even lower compared to the unencapsulated nanofibers. The release experiments of allopurinol from nanofibers into phosphate buffer, simulated gastric fluid, and simulated intestinal fluid suggested the anomalous pattern for the burst release, followed by the Fickian diffusion for the sustained release. In addition, the allopurinol encapsulated nanofibers showed effective suppression against xanthine oxidase. Our work suggest that the glucose cross-linked gelatin/zein nanofibers may be a promising delivery system for hydrophobic bioactive molecules.