Antibiofilm and antifungal properties of SrWO4 microstructures against multi-azole-resistant Candida albicans and other microbes

Abstract

Nanoparticles have shown significant potential in combating microbial resistance and biofilm-associated infections. Strontium tungsten oxide (SrWO₄) microstructures exhibit promising biomedical applications, including bone tissue engineering and anticancer properties, due to their osteogenic and photocatalytic effects. However, its antifungal and antibiofilm activities remain unexplored. SrWO₄ was chosen for this study for its ability to generate reactive oxygen species (ROS) and its structural similarity to antimicrobial metal oxides. In this study, SrWO₄ microstructures were synthesized using sonication, hydrothermal, and stirring methods. Notably, ultrasonicated SrWO₄ (SO-SrWO₄) showed potent antifungal and antibiofilm activity at 150 µg/ml, achieving tenfold biofilm inhibition, whereas its precursors (Na₂WO₄ and SrCl₂) required 1,000 µg/ml for similar effects. This enhanced efficacy is due to combined physicochemical properties of precursors and elevated ROS generation. SO-SrWO₄ inhibited biofilm formation in multiple drug-resistant pathogens, including Candida albicans, Staphylococcus aureus, and uropathogenic Escherichia coli. Mechanistic analyses revealed significant impairment of filamentous growth in C. albicans, accompanied by downregulation of biofilm and hyphae-related genes and enhanced ROS-mediated oxidative stress. Importantly, SO-SrWO₄ compared to various other nanoparticles demonstrated minimal toxicity against human HepG2 liver cells with an IC₅₀ greater than 1,600 µg/ml, Caenorhabditis elegans survival, and Brassica rapa growth. This study highlights the potential of SrWO₄ microstructures as an effective, and non-cytotoxic broad-spectrum antimicrobial agent, which is the first study to report on these properties. Their ability to inhibit biofilms in drug-resistant pathogens, combined with minimal toxicity, makes them a promising candidate for future biomedical applications, particularly in addressing antifungal resistance and biofilm-associated infections.