Hydrophilic-hydrophobic poly(dimethyl siloxane)-based SERS substrate with internal Raman signaling

Poor signal uniformity and external interference have become two of the main issues that prevent the broad use of surface-enhanced Raman scattering (SERS) in the reliable and quantitative detection of trace molecule. Here, a hydrophilic-hydrophobic PDMS film decorated with SiO2@Ag nanoparticles (NPs) was developed. The improvement of SERS sensitivity and uniformity by the hydrophilic-hydrophobic strategy after eliminating coffee-ring effect was confirmed by calculating enhancement factor as 3.88 × 106 and recording SERS mapping with a relative standard deviation value of 17.18%. The dominant contribution of the intrinsic Raman signal (internal standard) of PDMS was proved in the detection of MB and 4MBA, resulting in perfect coefficients of determination (R2) as 0.997 and 0.998. Furthermore, the suitability of the quantitative SERS substrate on detecting trace thiram was demonstrated. All the results reveal that the simple design may provide an attractive quantitative SERS matrix for routine monitoring of trace biochemical molecules.