Convenient self-assembled PDADMAC/PSS/Au@Ag NRs filter paper for swift SERS evaluate of non-systemic pesticides on fruit and vegetable surfaces.

• PDADMAC/PSS/Au@Ag NRs filter paper is a kind of disposable environment-friendly flexible SERS substrate. • The PDADMAC/PSS modified filter paper showed the potential of SERS substrate for nanoparticle self-assembly. • The prepared paper-based SERS substrate had high SERS activity and good reproducibility. • PDADMAC/PSS/Au@Ag NRs filter paper realized the "paste-reading" detection of MP, TMTD and CPF on the pericarp. The goal of food safety supervision is to directly identify the pesticide residues on the surface of fruits and vegetables. This study proposed to develop a facile, non-destructive, and sensitive method based on surface-enhanced Raman scattering (SERS) to detect non-systemic pesticides on the surface of fruits and vegetables. The composite material was prepared by loading CTAB guided Au@Ag NRs with positive charge onto filter paper which was modified with PDADMAC(+) and PSS(−) using electrostatic adsorption. Au@Ag NRs with bimetallic synergies were effectively adsorbed in the fiber grid to generate 3D SERS hotspots within a few microns of depth. The results showed that the 3D composite flexible substrate had a high SERS activity, great repeatability, and sensitivity when the method was utilized to detect 4-MBA, methyl-parathion, thiram and chlorpyrifos. Three kinds of non-systemic pesticides on the peel could be detected directly and quickly owing to the arbitrary bending of the substrate, demonstrating the efficiency of the SERS "paste-reading" method. The acquired findings demonstrated that PDADMAC/PSS/Au@Ag NRs composite filter paper had the potential to provide rapid feedback for in- situ analysis of pesticide residues on the surface of fruit and vegetable. [ABSTRACT FROM AUTHOR]