Fabrication of flexible multidimensional CC/MoS₂@Ag@PDMS hybrids as stable and self-cleaning SERS substrate for sensitive and quantitative point-of-care testing

Flexible surface-enhanced Raman scattering (SERS) sensors are ideal for point-of-care testing (POCT) of hazardous materials. The key to practical applications lies in their quantitative detection capabilities and high stability for cycle use. In this study, we propose a simple method to develop a recoverable CC/MoS₂@Ag@PDMS composite SERS substrate using chemical vapor deposition (CVD) technology. This flexible SERS substrate, utilizing 4-aminothiophenol (4-ATP) as the detection molecule, demonstrated a high enhancement factor (∼ 10⁷) and a low detection limit (10⁻¹² M). The corrected linearity problem achieved good linear correlation (R² = 0.997) by using the intrinsic Raman signal from the polydimethylsiloxane (PDMS) substrate. The results of theoretical calculations illustrate this excellent SERS performance by a combination of electromagnetic and chemical enhancements. In addition, in the presence of MoS₂, the substrate demonstrated excellent self-cleaning cycle detection and maintained high SERS activity through more than 100 mechanical deformations of bending and twisting. In situ detection was performed for tetramethylthiuram disulfide (TMTD), ampicillin (AMP), and ciprofloxacin (CI) with detection limits of 10⁻⁹ M. These promising detection results suggest that this highly stable and flexible substrate can be used for POCT and environmental safety by simply wiping objects to obtain contaminant samples.