Controllable assembly of three-dimensional SERS substrate for highly sensitive detection of thiram residues in vegetables

In this work, a series of three-dimensional (3D) SERS substrate were successfully fabricated by assembling silver nanoparticles (AgNPs) onto a porous gelatin sponge (GS) for highly sensitive thiram residues detection in vegetables. These 3D micro-nanostructures could induce the sufficient surface plasmon resonance (SPR) effect of noble metals on their surface and achieve high enrichment of pollutant molecules. As crystal violet (CV) was used as a probe molecule, the lowest CV solution could be detected at 10−9 M, and the enhancement factor (EF) was calculated to be 9.53 × 106. These Raman enhancement effect was completely in accordance with the Finite-Difference Time-Domain (FDTD) simulations calculation. More critically, these 3D SERS substrates showed high sensitivity in the actual detection of thiram residue in vegetables, and a detection limit of 0.062 mg/kg was successfully obtained. This construction strategy is expected to provide a fast and simple method for the detection of harmful pollutants in the agriculture and aquaculture fields. •A three-dimensional SERS substrate was successfully fabricated in a facile method.•GS@AgNPs SERS substrate demonstrated high sensitivity for target molecule.•These 3D micro-nanostructures induce the sufficient surface plasmon resonance effect.•Thiram residues was sensitively detected by these flexible GS@AgNPs SERS platform.