Innovative Synthesis of Adhesive-Assisted and Recyclable Fe3O4@PD-Ag Photomagnetic Nanocomposites as SERS probes for Ultrasensitive Thiram Detection on Fruit Peels

Abstract

Surface-enhanced Raman spectroscopy (SERS) with enormous advantages has emerged as a powerful tool for both highly sensitive structural detection of analytes and various imaging applications. A notable advancement in the realm of multifunctional SERS substrates is the integration of magnetic nanoparticles endowed with magnetic manipulation capabilities and noble metal nanoparticles exhibiting plasmonic resonance properties. This synergistic combination offers substantial practical benefits for trace analysis across diverse fields. In this paper, a new paradigm of Fe3O4@PEI-DTC-Ag (Fe3O4@PD-Ag) photomagnetic nanocomposites based on magnetic Fe3O4 nanoparticles (NPs), the noble metal silver quantum dots (Ag QDs) and the adhesive layer polyethyleneimine dithiocarbamate (PEI-DTC) for convenient recycling and ultrasensitive SERS detection was developed by engineering hydrothermal and seed-growth methods. The SERS performance of the Fe3O4@PD-Ag substrates with varying amounts of Ag was evaluated by detecting 4-aminothiophenol (4-ATP). Among the tested samples, Fe3O4@PD-Ag-4 with a silver solution volume of 200 ml exhibited the optimal performance, showcasing an enhancement factor (EF) of 4.418 × 105. Moreover, the relative standard deviations (RSDs) were calculated to be less than 11.5 %, demonstrating the SERS substrates exhibit good uniformity and spectral reproducibility. Of note, the SERS substrate has demonstrated successful trace detection of thiram molecules, achieving a limit of detection (LOD) of up to 10-9 M. The intensity of SERS signals shows a linear correlation with the logarithm of thiram concentration, ranging from 10-4 to 10-9 M, thus providing compelling evidence for quantitative detection. Importantly, the Fe3O4@PD-Ag-4 SERS substrate also showcases outstanding performance for detecting thiram in real food, underscoring its significant potential for application in food safety monitoring.