Effect of pH on the optimization of cysteine‐functionalized gold core‐silver shell nanoparticles for surface‐enhanced Raman scattering‐based pesticide detection on apple peels

Abstract Background The rapid detection and efficient properties of surface‐enhanced Raman scattering (SERS) have been widely exploited in food safety. Purpose In this study, the SERS impact of cysteine‐functionalized gold core‐silver shell bimetallic nanoparticle (Au@Ag@CysNPs) substrates with different pH treatments on pesticide compounds was examined. Results The pH‐dependent SERS impact of Au@Ag@CysNPs on detecting pesticide compounds exhibited different enhancements over the pH range of 2–11 and exited the highest enhancement at a pH of 5 for thiabendazole and thiram pesticides. The prepared Au@Ag@CysNPs were further utilized in SERS‐based rapid detection of pesticides on apple peels by directly dropping Au@Ag@CysNPs on the surface of the samples, where the target molecules could be identified without elution or extraction. These findings revealed that this Au@Ag@CysNPs substrate exhibited excellent SERS performances for pesticide compounds and good stability. With additional optimization, detection limits of 0.1 ng/cm 2 for thiabendazole and thiram on apple peels were obtained.