Microbial PHB/PCL Nanofibrous Scaffolds for Controlled Drug Delivery and Enhanced Wound Healing: Comprehensive In Vitro and In Vivo Evaluation

Wound management remains a significant global challenge due to delayed epithelialization, microbial infections, and resistance to traditional antibiotics. Particularly, in the era of antibiotic resistance, the combination of drugs has gained prominence due to their broad-spectrum antibacterial action, which enhances the efficacy of topical formulations for wound healing. The study explores the fabrication and evaluation of an electrospun nanofibrous scaffold composed of microbial poly-3-hydroxybutyrate (PHB) and polycaprolactone (PCL) loaded with a dual drug combination of cefixime (CFX) and azithromycin (AZM) for controlled drug delivery (CDD) in wound healing. PHB was produced from Bacillus cereus using sugar hydrolysate as a low-carbon source. Furthermore, the PHB polymer is blended with PCL to enhance flexibility, spinnability, and drug release performance. The nanofibrous scaffolds were fabricated by varying the PHB/PCL (3:1 and 1:1) ratio via electrospinning. FTIR and 1 H NMR analyses confirmed successful drug incorporation in PHB3/PCL1/CFX/AZM and PHB1/PCL1/CFX/AZM nanofibrous scaffolds. In vitro drug release studies revealed a sustained dual drug release profile with the Korsmeyer-Peppas best-fitting model, suggesting anomalous (non-Fickian) transport governed by diffusion and swelling or erosion phenomena. The drug-loaded scaffold demonstrated significant antibacterial activity against Escherichia coli, Acinetobacter baumannii, Staphylococcus aureus, and Enterococcus faecalis, achieving complete inhibition over 24 h. In vitro results reveal that the dual drug-loaded PHB/PCL scaffolds show good biocompatibility and enhanced cell proliferation and migration via a scratch assay. Additionally, in vivo studies displayed improved wound closure, reepithelialization, neovascularization, and collagen remodeling in treated wounds. These results suggest that a dual drug-loaded PHB/PCL nanofibrous scaffold, designed for CDD, offers a promising platform for wound healing management.