Thioctic Acid-Modified Silver Nanoplates on Copper Foil for Low Interference Detection of Fluoranthene by Surface-Enhanced Raman Spectroscopy

Surface-enhanced Raman spectroscopy (SERS) has been widely used for chemical and biological analyses because of its ultrahigh sensitivity and label-free molecular specificity. However, SERS analysis of analytes with weak affinity for a substrate must rely on substrate surface modifications that trap analytes into the active sites. The interference from the Raman signal of the modified layer limits the improvement in the detection limit. Herein, we report a surface modification strategy for the enrichment and SERS detection of fluoranthene, which involves the functionalization of silver nanoplates on copper foil with thioctic acid. The modified SERS substrate provides high analyte enrichment and low interference from the modified layer. The fixed position of Raman peaks for fluoranthene enables quantitative detection from a minimum detectable concentration of 0.1 ng/mL up to 0.1 mg/mL. This study based on a simple and cost-effective method affords unique insights into the surface enrichment of analytes, which could facilitate high-performance SERS analysis of various analytes.