Affordable Paper-Based Surface-Enhanced Raman Scattering Substrates Containing Silver Nanorods Using Glancing-Angle Deposition for Nosocomial Infection Detection

An excellent surface-enhanced Raman scattering (SERS) substrate offers exceptional signal enhancement and amplification while boasting a substantial surface area. The substrate should be straightforward to fabricate and cost-effective. Therefore, here we propose a cellulose-based substrate with silver nanorods (AgNRs) fabricated on it using glancing angle deposition (GLAD) method, leading to a highly cost-effective, flexible, biodegradable substrate. The porous and fibrous nature of the paper-based substrate provides high roughness and surface area and hence enhances the plasmonic effect. Due to the properties of paperlike capillary and wicking action, the bioanalytes to be detected can bind strongly to the metal nanostructures, amplifying the SERS signals. In this study, using GLAD, two-arm zigzag AgNRs were fabricated on the paper that was used as a SERS substrate. Both the nanoregime features of Ag and the versatility of paper represent an improved SERS substrate. Further, to determine its applicability in public health, nosocomial-infection-causing bacteria like Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus were detected. Also, the lower limit of detection was estimated, which was found to be 10 2 copies/mL for all three different bacterial strains. The spectral intensity on the paper-based SERS substrate was observed to be around 10 times higher compared to that on the glass-based SERS substrate. Furthermore, a clear separation between Gram-positive and Gram-negative bacteria was observed using this substrate, showing immense potential in detecting biomolecules.