Antibacterial and Antifungal Activities of Pterocarya fraxinifolia Extract Encapsulated in ZIF-8

Abstract

Antibiotic resistance is an escalating global threat, prompting the urgent need for alternative antimicrobial strategies. In this study, a novel nanocomposite was developed by encapsulating Pterocarya fraxinifolia leaf extract (PF) into a zeolitic imidazolate framework-8 (ZIF-8), aiming to enhance its stability and antimicrobial efficacy. The synthesized PF@ZIF-8 composite was characterized using FTIR, XRD, BET, and SEM analyses, confirming successful encapsulation and preserved structural integrity. The antimicrobial activity of PF@ZIF-8 was evaluated against Candida albicans, Aspergillus flavus, Staphylococcus aureus, and Escherichia coli using well and disk diffusion methods. Compared to the free extract and ZIF-8 alone, the PF@ZIF-8 nanocomposite—particularly at 20% extract loading—demonstrated significantly larger inhibition zones and lower minimum inhibitory concentration (MIC) values. Notably, the nanocomposite showed superior performance against C. albicans and E. coli, suggesting selective and enhanced antimicrobial behavior. The improved efficacy is attributed to the sustained release and structural protection provided by the ZIF-8 matrix, along with potential synergism between Zn²⁺ ions and plant-derived phytochemicals. While cytotoxicity data were not included in this study, the natural origin of PF and the biocompatible nature of ZIF-8 highlight the potential for biomedical applications. These findings suggest that PF@ZIF-8 offers a promising green antimicrobial platform for combating resistant pathogens.