Carbon dots based AuAg@AuNPs with oxidase-like activity for SERS dual-readouts detection of D-penicillamine

An oxidase (OXD) -like AuAg@AuNPs nanozyme was prepared by Au seeds growth using dopamine carbon dots as reducing and capping agents. The AuAg@AuNPs show excellent OXD-like and surface-enhanced Raman spectroscopy (SERS) activities and can oxidize the non-Raman-active leucomalachite green (LMG) into the Raman-active malachite green (MG). The research displays that D-penicillamine (D-PA) can effectively inhibit the OXD-like activity of Au@AgNPs and enhance the SERS signals as substrate. It is attributed to the formation of S–Au bond due to thiol (-SH) in D-PA. Therefore, a highly sensitive and specific SERS dual-readout sensing platform was proposed to assay D-PA with a limit of detection of 0.1 μg/mL (direct SERS mode) and 6.64 μg/L (indirect SERS mode). This approach was successfully used to determine D-PA in actual pharmaceutical formulations.