Sandwich-Like Sensor for the Highly Specific and Reproducible Detection of Rhodamine 6G on a Surface-Enhanced Raman Scattering Platform

Nonspecificity and low reproducibility are always the main challenges in surface-enhanced Raman scattering (SERS) detection, especially for testing real samples. In this study, we developed a sandwich-like sensor (AuA-pMIP) to detect rhodamine 6G (R6G) by integrating a porous molecularly imprinted polymer (pMIP) with a well-ordered AuNP array (AuA). To form a uniformly distributed hot spot, AuA was fabricated at an oil-water interface and was subsequently fixed between pMIP and a support slide. Finite-difference time-domain simulation indicated that the enhanced electric field covered a distance of ∼2 μm above the AuA, in which the pMIP provided effective mass-transfer channels and sufficient specific binding sites for target molecules. High specificity for AuA-pMIP in R6G detection was demonstrated by comparing the SERS performance of R6G on AuA-pMIP with that of its structural analogues on the same sensor. Remarkably, the stable sandwich-like structure allowed us to achieve a recyclable SERS sensor with high reproducibility. Finally, AuA-pMIP displayed excellent specificity and sensitivity toward R6G in a test based on a real orange juice sample. This study presents a promising method to achieve real sample testing on a SERS platform.