Pyridoxine SERS sensing using small triangular-like silver nanoclusters

Silver nanoclusters (AgNCs) smaller than 2 nm, synthesized via a green approach, were evaluated. Transmission electron microscopy (TEM) characterized the morphology of the AgNCs, revealing faceted particles, particularly triangular shapes. Optical absorption analysis demonstrated behavior indicative of quantum confinement effects on their optical properties. The potential of AgNCs as substrates for surface-enhanced Raman spectroscopy (SERS) in detecting pyridoxine was assessed, with experimental results showing an intensification of specific vibrational bands of pyridoxine upon interaction with the AgNCs, suggesting strong analyte-metal surface interactions. Theoretical calculations based on density functional theory (DFT) and time-dependent density functional theory (TD-DFT), using the Perdew-Burke-Ernzerhof (PBE) functional, predicted this behavior and provided evidence of electronic transitions and the SERS effect. These results indicate that AgNCs hold significant potential for applications in molecular detection and spectroscopic analysis, underscoring the influence of size and morphology on their optical properties and SERS performance. Further theoretical evaluation of the total enhancement indicator (TEI) for different excitation wavelengths (532 and 638 nm) yielded key insights, offering a roadmap to optimize experimental conditions and enhance SERS sensitivity.