Fabrication, characterization, and optimization of core–shell electrospun nanofibers for simultaneous sustained delivery of metformin and glibenclamide in type II diabetes treatment

In this study, we successfully fabricated and characterized core–shell electrospun nanofibers using a PCL–PEG/PCL–PEG system for the simultaneous sustained delivery of metformin and glibenclamide for the treatment of type II diabetes. The FTIR analysis confirmed the presence of the loaded drugs within the fibers, while XRD results indicated that the fibers were predominantly in the amorphous phase. FESEM micrographs revealed cylindrical fiber morphology with an average diameter ranging from 100 to 380 nm, and TEM imaging confirmed the core–shell structure. The effects of various parameters, including core/shell flow ratio, core PEG molecular weight, and shell electrical conductivity, on fiber properties and drug release kinetics were investigated. Notably, a higher shell/core flow ratio of 8:1 resulted in a 21% decrease in the total releasable drug amount ( \(A_{\infty }\) $A_{\infty }$ ) for metformin compared to a 1:1 ratio. Additionally, increasing the core PEG molecular weight from 6 to 35 kDa led to a 16% reduction in \(A_{\infty }\) $A_{\infty }$ for glibenclamide. Through mathematical modeling and optimization, the ideal formulation was identified, exhibiting an \(A_{\infty }\) $A_{\infty }$ of 4.67 mg/g and 4.19 mg/g for metformin and glibenclamide, respectively. The 60% release time (T60) for this optimized formulation was 83.28 h for metformin and 91.26 h for glibenclamide, demonstrating extended-release behavior. The comprehensive evaluations and mathematical modeling suggest that the presented core–shell drug release system outperforms fibers of the same material produced by conventional electrospinning, suggesting a promising approach for improving medication adherence in type II diabetes management.