Sharp-edged silver nanocubes via polymer-mediated synthesis: A new frontier in SERS-based drug detection

This study reports the synthesis of sharp-edged silver nanocubes (AgNCs) with improved plasmonic characteristics and high structural stability, developed as a surface-enhanced Raman scattering (SERS) substrate for trace-level quantification of anticancer drug gemcitabine (GMC). Multiple techniques were employed to investigate the morphological and structural properties of AgNCs in comparison with conventional silver nanospheres. The polyvinylpyrrolidone (PVP)-stabilized AgNC substrate provided remarkable SERS responses, with diagnostic peaks assigned to the CN stretching mode (1174 cm^-1) and CO stretching mode (1196 cm^-1), together with prominent CF₂ bending (529 cm^-1) and ring deformation (460 cm^-1) modes. Ultrasensitive detection was achieved in aqueous media over a wide concentration range, with GMC signals experimentally detectable down to 10^-12 M. The calculated statistical LOD was 6.2 × 10^-11 M. The developed AgNC substrate demonstrates a long shelf life of up to five weeks. Density functional theory (DFT) calculations rationalize the possible analyte-substrate interactions and accompanying binding energies, indicating efficient adsorption through the nitrogen- and oxygen-containing pyrimidine and furanose ring systems, respectively, and supporting charge-transfer contributions that modulate the intensities of key vibrational markers under SERS conditions.