One-Pot Synthesis and Antifungal Activity of Nontoxic Silver-Loaded Hydroxyapatite Nanocomposites against Candida Species

The impact of fungal diseases and the development of antimicrobial agents against pathogenic fungi have emerged as a main global healthcare challenge. In this study, the antifungal activity of silver-loaded hydroxyapatite (Ag/HAP) nanocomposites (NCs) with different Ag content synthesized by a one-pot microwave-assisted solvothermal method was evaluated against sensitive and resistant Candida species. The NCs’ composition and morphology were characterized by X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and high-resolution transmission electron microscopy analysis. Antifungal studies were conducted by a microdilution method according to a protocol from the Clinical and Laboratory Standards Institute. The main inhibitory effect was observed against Candida krusei, with a minimum inhibitory concentration (MIC) of 31.2 μg/mL, followed by Candida parapsilosis sensu stricto and Candida tropicalis (62.5 μg/mL) and Candida glabrata and Candida albicans (125 μg/mL). Furthermore, a toxicity assay was performed in the in vivo model Galleria mellonella by bathing or inoculating with the same NC concentration used in the previously mentioned microdilution experiments. For both approaches, all NC concentrations were not toxic in the in vivo model. The specific antifungal activity demonstrated that NCs act efficiently against species of Candida. These results show a potential antifungal application for well-designed nanostructured Ag/HAP composites.