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

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.