Flexible MXene/au/PDMS SERS sensors for trace detection of agricultural residues

Modified PDMS with APTES and n-hexane enables in-situ self-assembly of AuNPs. • 2D MXene overlayer on AuNPs boosts SERS sensitivity and ensures sensor stability. • The flexible MXene/Au/PDMS sensor yields a high enhancement factor of 6.5 × 10 4 . • The SERS platform achieves LODs of 10 −10  g mL −1 (TBZ) and 2.25 × 10 −10  M (TC). • Swab-sampling enables rapid detection of pesticide residues on fruit surfaces. The overuse of pesticides and antibiotics in agriculture poses significant risks to food safety and human health, necessitating rapid and sensitive detection methods. This study develops a novel, flexible Surface-Enhanced Raman Spectroscopy (SERSa) platform by integrating gold nanoparticles (AuNPs) and 2D MXene nanosheets on a polydimethylsiloxane (PDMS) matrix for the ultra-sensitive trace detection of pesticide residues. To simplify conventional fabrication methods, 3-aminopropyltriethoxysilane (APTES) and n-hexane were directly incorporated into the PDMS prepolymer, enabling the uniform in-situ self-assembly of AuNPs via straightforward immersion in a chloroauric acid precursor. The subsequent addition of layered MXene nanosheets not only boosted SERS sensitivity through synergistic enhancement but also functioned as a protective barrier to ensure superior substrate stability. The optimized MXene/Au/PDMS sensor demonstrated exceptional SERS performance, achieving a high Enhancement Factor (EF) of 6.5 × 10 4 . Utilizing a simple swab-sampling technique, the flexible substrate effectively collected and identified trace residues directly from apple and cherry tomato surfaces. The platform achieved highly sensitive quantitative analysis, with limits of detection (LOD) reaching 10 −10  M for TBZ and tetracycline. Additionally, the sensor exhibited consistent large-scale spatial reproducibility and maintained robust environmental stability over a one-month storage period. These results confirm that the proposed flexible SERS substrate is a reliable and practical tool for the rapid, on-site monitoring of food safety hazards. Download: Download high-res image (145KB) Download: Download full-size image