Determination of trace amount quercetin with magnetic molecularly imprinted electrochemical sensor sensitized by graphene oxide

Abstract

Molecularly imprinted polymer-based electrochemical sensors (MIP/ECS) have emerged as a promising platform for trace-level pollutant detection, particularly in food safety and environmental monitoring. However, their practical applications are frequently limited by inefficient collection of imprinted materials and sluggish electron-transfer kinetics, which ultimately compromise both selectivity and sensitivity. In this study, we report an innovative MIP/ECS design that integrates Fe₃O₄, graphene oxide (GO), and a molecularly imprinted polymer layer for the ultrasensitive and highly selective detection of quercetin (QR). Systematic investigations demonstrate that the incorporation of Fe₃O₄ enables rapid analyte adsorption under magnetic guidance, while GO significantly enhances electron-transfer efficiency. The polyacrylamide-based imprinted layer provides exceptional recognition specificity toward QR through hydrogen bonding and π–π stacking interactions. As a result, the fabricated sensor exhibits an ultralow LOD of 0.50 nM and a wide dynamic linear range from 0.01 to 1000 μM, comprising two linear regions (0.01–25 μM and 25–1000 μM) with excellent correlation coefficients (R₁² = 0.9973 and R₂² = 0.9997), along with outstanding stability and reliable performance in real-sample analysis. Moreover, the sensor was successfully applied to the determination of QR in Sophora japonica L. buds, onions, and apples, achieving satisfactory recovery values. This work provides a viable and effective strategy for developing high-performance MIP/ECS systems for the precise detection of QR in environmental and food-related samples.