A molecularly imprinted SERS sensor with both high-accuracy quantitative analysis and high-stability reuse based on spatial separation of catalytic sites

Abstract

A surface-enhanced Raman spectroscopy sensor combined with the molecular imprinting technique (MIT-SERS) has the ability of high sensitivity and specific recognition, but its accurate quantitative analysis and high-stability reuse are poor. To solve the above problems, a novel MIT-SERS sensor with internal standard self-correction and spatially separated photocatalysis is designed. This MIT-SERS sensor is composed of a SERS substrate and a MIT recognizer. Photocatalyst TiO₂, co-reductant catalyst Ag and co-oxidant catalyst Fe₂O₃ are the main materials of the SERS substrate. The occupying molecule C₃H₆S and the template molecule 4-ATP are adsorbed on the surface of Ag and Fe₂O₃ in turn. The molecularly imprinted layer is SiO₂. It is worth noting that the space-confined assembly of C₃H₆S and 4-ATP ensures that C₃H₆S is protected and 4-ATP is completely degraded during the photocatalysis process, realizing the reusability of the MIT-SERS sensor. In addition, SiO₂ is used as an internal standard to improve the accuracy of quantitative analysis of the sensor. For this MIT-SERS sensor, the detection limit (LOD) is as low as 2.24 × 10⁻¹¹ M and the linear fit (R²) of quantitative analysis is as high as 0.9975. During repeated use, the relative standard deviation (RSD) of the corrected signals from the MIT-SERS sensor is as low as 1.27%.