Preparation and Characterization of Zein-Metformin/Gelatin Nanofibers by Coaxial Electrospinning

Metformin is a drug commonly used for the treatment of type 2 diabetes. However, it has been associated with damaging side effects when used over a long period of time. A potential solution to this problem is the implementation of a prolonged-release system for metformin, which would enhance the efficiency of the doses administered to patients. To achieve this, it is necessary to use materials compatible with humans. Electrospinning is an efficient technique that can be employed for this purpose, utilizing solvents that are safe for human use. Therefore, the objective of this study was to prepare and characterize a system for the prolonged release of metformin from zein and gelatin through coaxial electrospinning as well as to investigate its in vitro release. Metformin-loaded zein/gelatin coaxial nanofibers were prepared using the coaxial electrospinning technique and then characterized by morphological, structural, and thermal analysis. Morphologically, metformin-loaded zein/gelatin coaxial nanofibers were obtained with an average diameter of 322.6 ± 44.5 nm and a smooth surface. Fourier transform infrared spectroscopy (FTIR) analysis showed band shifts at a higher wavenumber due to drug-protein interactions by hydrogen bonding between N-H and C=O groups. Thermal gravimetric analysis (TGA) results suggested a possible interaction between materials due to an increase in the degradation temperatures of zein and gelatin when metformin was included. The transition of the crystallinity of metformin to the amorphous form was also confirmed by differential scanning calorimetry (DSC). Coaxial nanofibers exhibited an encapsulation efficiency of 66% and a profile release that showed an initial release of metformin (40%) in the first hour, followed by a gradual release until it reached equilibrium at 60 h and a cumulative release of 97% of metformin. It was concluded that using the coaxial electrospinning technique, it is possible to obtain nanofibers from polymeric solutions of zein and gelatin to encapsulate metformin, with a potential application as a prolonged-release system.