Rapid and sensitive detection of Candida albicans using nystatin-functionalized magnetic spheres

Candida albicans is the leading cause of invasive fungal disease; candidemia carries 30-40 % mortality. It commonly colonizes human mucosa as a commensal, but immunosuppression or disrupted microbiota enables opportunistic infection. Therefore, rapid, reliable diagnostics are vital to improve public health. In this study, a magnetic solid-phase microextraction (MSPE) technique based on nystatin-functionalized magnetic nanoparticles (Fe₃O₄@NYS) was developed to achieve the dual objectives of efficiently enriching C. albicans rapidly and extracting its deoxyribonucleic acid (DNA). Optimization of capture conditions enabled rapid enrichment of C. albicans with a maximum recovery rate of approximately 90 %. Subsequent to the capture of C. albicans, DNA extraction was performed on the Fe₃O₄@NYS-C. albicans complexes. Notably, Fe₃O₄@NYS facilitated the extraction of a substantial quantity of DNA, with the extraction yield reaching 1200 ng/mg. Therefore, the integration of DNA extraction with quantitative polymerase chain reaction (qPCR) technology enables sensitive and specific detection of C. albicans in real samples. The strategy demonstrated excellent linearity within the concentration range of 4.20 × 10² to 4.20 × 10⁷ CFU mL^-1 for C. albicans. The high sensitivity and accuracy of this method were confirmed in honey samples, showcasing a limit of detection (LOD) 420 CFU mL^-1, recoveries between 98.1 % and 99.8 %, and relative standard deviations (RSD) not exceeding 2.51 %. This method presents an innovative strategy for point-of-care clinical diagnosis, disease surveillance, and biosafety management, demonstrating substantial potential for the efficient isolation of DNA from complex biological matrices.