Antifungal Potency of Biosynthesized Zinc Oxide Nanoparticles Combined with Allium sativum Extract Against Clinical Candida albicans Isolates from Dental Caries Patients

Abstract

Background: Increased Candida resistance to antifungal drugs, combined with the limited range of antifungal targets available given the eukaryotic nature of both yeast and host cells, has motivated the search for alternative antifungal agents, including nanoparticles and plant extracts.

Aim: This study aimed to biosynthesize and characterize zinc oxide nanoparticles (ZnONPs) and evaluate the antifungal activity of ZnONPs, garlic (Allium sativum) extract, and their combination against clinical Candida albicans isolates from dental caries patients.

Methods: Candida isolates were recovered from oral swabs of dental caries patients and identified by CHROM agar and the VITEK II system. ZnONPs were biosynthesized using garlic extract as a reducing/capping agent and characterized by UV-Vis, FT-IR, FESEM, DLS, and zeta potential. Antifungal activity of garlic extract, ZnONPs, and their combination (AS-ZnONPs) against C. albicans was assessed by agar well diffusion and broth microdilution (MIC/MFC).

Results: C. albicans was the predominant Candida species recovered (65.3%). Characterization confirmed successful ZnONP biosynthesis: UV-Vis absorption at 360 nm, a Zn–O FT-IR band at 500–600 cm⁻¹, spherical morphology (25.74 ± 8.75 nm, FESEM), a Z-average of 134.7 nm (DLS, PDI = 0.177), and zeta potential of −12.7 mV. AS-ZnONPs produced the largest inhibition zone (28.43 ± 0.76 mm), exceeding ZnONPs alone (22.80 ± 0.26 mm), garlic extract (15.86 ± 0.45 mm), and itraconazole (26.60 ± 0.13 mm), with the lowest MIC/MFC (125/250 µg/mL) among all tested agents.

Conclusion: AS-ZnONPs exhibited the strongest fungicidal activity against C. albicans, supporting their potential as a biosynthesized antifungal alternative warranting further in vivo and cytotoxicity evaluation.