Ethanol-assisted electrochemical deposition of silver nanoflowers on silicon for highly sensitive SERS detection of Staphylococcus aureus.

The morphology and size of metallic nanostructures play a decisive role in determining their surface-enhanced Raman scattering (SERS) performance. Herein, we report an ethanol-assisted electrochemical deposition strategy for the direct fabrication of uniform silver nanoflowers (AgNFs) on Si substrates. The ethanol-based electrolyte plays a key role in regulating nucleation and anisotropic growth, enabling the formation of densely distributed flower-like Ag nanostructures with sizes of 80-100 nm and abundant inter-petal nanogaps. Under optimized deposition conditions, the AgNFs/Si substrate exhibited strong surface-enhanced Raman scattering (SERS) activity toward crystal violet, with an analytical enhancement factor of approximately 1010 and a detection limit of 10-12 M. The same substrate also enabled label-free detection of Staphylococcus aureus over a wide concentration range from 20 to 107 cfu mL-1, with an estimated limit of detection of 2.53 cfu mL-1. In addition, good signal uniformity and batch-to-batch reproducibility were achieved, with relative standard deviation values of approximately 9.64% and 11.05%, respectively. These results demonstrate that solvent-controlled electrodeposition provides a simple and effective route to high-performance Ag-based SERS substrates for practical biosensing applications.