Surface-enhanced Raman spectroscopy (SERS) substrates based on biosynthesized silver nanoparticles for identification of various candida species

This research showcases the production of silver nanoparticles (AgNPs) through the utilization of Cucumis prophetarum leaf extract. These nanoparticles were then utilized as substrates for surface-enhanced Raman scattering (SERS) to differentiate various Candida species. The biosynthesized AgNPs exhibited a surface plasmon resonance band at 425 nm, an average hydrodynamic diameter of 22.3 ± 5.7 nm, and a zeta potential of −32.6 ± 2.4 mV. SERS spectra obtained using these AgNP substrates revealed distinct features for C. albicans, C. glabrata, and C. parapsilosis, with key differentiating peaks at 783 cm⁻¹ , 1155 cm⁻¹ , and 1585 cm⁻¹ , respectively. The use of principal component analysis and linear discriminant analysis on the SERS data led to strong discrimination between the three Candida species, with a classification accuracy of 97.8 % in cross-validation and 93.3 % for an independent test set. The biosynthesized AgNP-based SERS substrates demonstrated high sensitivity with an enhancement factor of 10^6, good reproducibility with less than 10 % relative standard deviation between batches, and excellent stability over 30 days. This green synthesis approach offers a cost-effective and biocompatible method for producing SERS substrates, showing potential for rapid and reliable identification of Candida species in clinical settings.