Fabrication of paper-based SERS substrates for detecting trace MG molecules in complex samples

The sensitivity of surface-enhanced Raman scattering (SERS) highly depends on the number of hotspots under laser spot and the number of analyte molecules near hotspots. Thus, a SERS substrate was constructed by assembling Ag nanocubes on a paper, which was previously modified with molecularly imprinted polymers (MIP) through in-situ polymerization. On the prepared substrate, the density of hotspots and analyte molecules near the hotspots are increased by the high surface area of paper and the modification of MIP. Malachite green (MG) is a toxic and prohibited drug that is very polluted to the environment, so monitor of trace MG is vital in complex environment. The minimum detectable concentration of MG molecules on the paper-based SERS substrate is 3.65 × 10 −3  ng/mL. The relative standard deviation (RSD) is 8.58 % and the EF is approximate to 1.78 × 10 7 . In addition, MG molecules can be accurately detected in the presence of interfering molecules, the imprinting factors of MG is up to 1.69. Furthermore, the substrate can be used for the detection of MG in shrimp leach liquor, and its minimum detectable concentration is as low as 0.365 ng/mL, the RSD is 7.49 %. The above results indicate that this substrate can be used for detecting trace molecule in complex samples.