Abstract: A graphene oxide (GO)-silver nanoparticles (AgNPs)-Eu3+ fluorescent probe, a paper-based sensor, and a preparation method and use thereof are provided. The paper-based sensor is developed based on a GO-AgNPs-Eu3+ fluorescent probe-loaded polyvinylidene fluoride (PVDF) microporous membrane, which is further combined with a smartphone. The GO-AgNPs-Eu3+ fluorescent probe shows high selectivity for 2,6-dipicolinic acid (DPA), strong anti-interference ability, and low limit of detection (LOD) for the DPA and spores. The paper-based sensor realizes quantitative detection of the DPA and the spores through red, green, and blue (RGB) changes of the smartphone, and detection results are verified by an actual amount of the spores in milk and water. The rapid detection of foodborne spores is achieved through a dual-function platform based on fluorescence of the GO-AgNPs-Eu3+ fluorescent probe and the paper-based sensor.

Abstract: Disclosed are a method for preparing a AgNPs@SASP substrate material and application thereof. The present disclosure uses cyclohexane as an organic phase and ethanol as an inducer, and uses the interfacial tension of an organic/water interface for self-assembly to arrange the nanoparticles in a single layer. The addition of a low-dielectric solvent as an inducer reduces the charge density on the nanoparticles. As a result, the van der Waals force combined with the reduction of the Coulomb repulsion force cause the nanoparticles to reassemble at the organic/water interface to form a new equilibrium, and a SERS platform of AgNPs in a two-dimensional array is prepared. SERS detection and peak attribution analysis of different food-borne pathogen spores are carried out, and qualitative analysis is carried out by a multivariate statistical method to realize the rapid identification of spore-forming bacteria.