A rapid dual-channel readout approach for sensing carbendazim with 4-aminobenzenethiol-functionalized core–shell Au@Ag nanoparticles

In this study, a 4-aminobenzenethiol-functionalized core–shell silver-coated gold nanoparticle (Au@Ag-4ABT NP) system was designed for the rapid sensing of carbendazim (CBZ) using a combination of naked-eye colorimetry and surface-enhanced Raman spectroscopy (SERS) dual-channel approach. Under alkaline conditions, the deprotonated CBZ species could interact with Ag surfaces via the N–Ag–O and N–Ag–N bonds. As a result, the neighboring Au@Ag-4ABT NPs would come closer through π–π interactions inducing the aggregation of Au@Ag-4ABT NPs. The aggregation of nanoparticles caused changes in the optical properties of the colloidal system, allowing observation with naked eyes, while the generation of more localized surface plasmon resonance “hotspots” between the adjacent Au@Ag nanoparticles permitted monitoring by the SERS technique. The proposed method showed effective sensitivity toward CBZ with limit of detection and limit of quantitation values of 37 and 122 ppb, respectively. In addition, the proposed dual-channel assay could serve as a simple and rapid method for sensing CBZ in tap water, cauliflower, and pear juice within 30 min.