Ultrasensitive SERS platform made via femtosecond laser micromachining for biomedical applications

Surface-enhanced Raman spectroscopy (SERS) is a research method in which a lack of cost-effective, versatile platforms with high enhancement factor (EF) is still a major obstacle toits widespread use. The platforms should be also easy to manufacture, stable in time (forweeks or even for months) and manufactured with a highly reproducible method.We demonstrate SERS platforms based on silicon modified on the surface by laserablation and covered with SERS-active metal. The substrates were fabricated by a femto-second laser, thus the method is simple, very fast and creates highly uniform SERS plat-forms in a large number. The platform was tested with para-mercaptobenzoic acid (p-MBA)in terms of sensitivity and reproducibility. The calculated EF was at the level of 108and thestandard deviation (SD) gives 7% for 106M solution ofp-MBA based on the intensity of theband at 1073 cm1. Optimized SERS substrate also exhibits excellent stability for up to sixmonths.We also give the proof-of-concept of using our platform and, for the first time, the SERSanalysis of the most important human opportunistic fungal pathogenCandidaspp. (Candidaglabrata,Candida albicans SN148andC. albicans BWP17). Finally, the chemometric analysis inthe form of Principal Component Analysis (PCA) allowed to strain differentiation ofCandidaspp.,and to distinguish the studiedCandida speciesfrom Gram-positive bacterial sampleswithStaphylococcus aureus.Our results demonstrate that the proposed SERS platform is aperfect substrate for detection, identification and differentiation between fungal andbacterial pathogens using SERS technique.