Nanomaterial assisted maldi-tof ms-based antifugal susceptibility testing for Candida species

Abstract

Candida spp. infections have increased due to invasive procedures, widespread antimicrobial use and higher rates of immunocompromised statuses. These infections often lead to therapeutic failure, due to rising antifungal resistance. MALDI-TOF MS has been used to detect resistant Candida strains. However, its sensitivity and selectivity can be compromised by background interference from conventional organic matrices. In this study, nanoparticles (NPs) have been proposed as a promising alternative, offering reduced interference, enhanced sample clean-up and enrichment for complex analyses. This study aimed to evaluate the suitability of nanomaterials as potential matrices for MALDI-TOF MS-based antifungal resistance profiling of Candida spp. The syntheses of silver NP (AgNPs) and gold NP (AuNPs) were conducted using roasted Coffea arabica seeds (CAS) extract and characterized using ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD) and high-resolution electron microscopy (HRTEM). UV-Vis spectroscopy of AgNPs and AuNPs showed absorbance peaks at 410 nm and 520 nm respectively, due to surface plasmon resonance. Identification of Candida spp. was performed using chromogenic agar and Sabourauds Dextrose Agar. Candida spp. antifungal susceptibility testing was conducted using the TREK Sensititre YO10 drug panel. While some improvements were observed when combining traditional matrices like α-cyano-4-hydroxycinnamic acid (HCCA) with AuNPs and AgNP, overall analytical performance did not show significant enhancements compared to conventional organic matrices. Although the NPs demonstrated some promise, the results were limited by poor interactions with Candida spp., unfavourable surface properties, and the species' inherent resistance mechanisms, which restricted ionization efficiency and resulted in poor reproducibility. Enhancements observed when NPs were applied in combination with a traditional HCCA matrix, were insufficient to warrant a shift from conventional methods. This emphasizes the need for further refinement of NP-based matrices to enhance their applicability in antifungal resistance analysis.