Toward Flexible Metal Semiconductor Sandwich Surface-Enhanced Raman scattering (SERS) sensors Pesticide Duplex Detection

The overuse of mixed pesticides poses a threat to both the ecosystem and human health, yet general pesticide detection methods are complex in terms of steps, such as the need for pretreatment and cleaning. Surface-enhanced Raman scattering (SERS) has been used for real-life trace detection of residues due to its rapid detection and ultra-high sensitivity. Here, we prepared a novel Ti3C2Tx (MXene)-noble metal hybrid flexible substrate with a layer of MXene on top of flower-like Ag nanoparticles (AgNFs), and finally grew Au nanoparticles (AuNPs) by galvanic replacement and self-reduction reactions. The limit of detection (LOD) can be as low as 2 × 10-12 M by detecting 4-mercaptobenzoic acid (4MBA). For efficient sampling, transparent and flexible platform made of polydimethylsiloxane (PDMS) were used for the extraction and detection of thiabendazole (TBZ), thiram, methyl parathion (MP) and their mixtures. Notably, the lowest concentrations detected by swabbing on the tomato surface (3.7 ng/mL, 2.8 ng/mL) were lower than the EU maximum permissible limits of pesticides on raw fruits and vegetables (4.0 mg/L, 6.33 mg/mL). This high performance Ti3C2Tx-noble metal hybrid flexible substrate offers a great advantage in the trace detection of molecules.