Quartz crystal microbalance sensor based on molecularly imprinted polymer membrane and three-dimensional Au nanoparticles@mesoporous carbon CMK-3 functional composite for ultrasensitive and specific determination of citrinin

• A novel 3D MIP based QCM sensor was constructed for trace CIT detection.
• AuNPs@CMK-3 was explored for amplifying the signal of MIP based QCM sensor.
• The proposed sensor displayed high sensitivity, good selectivity, reproducibility.
• This work may provide a promising method for ultrasensitive sensing applications.

Citrinin (CIT) is difficult to measure since only trace levels are present in commercial food products. In this study, a novel three-dimensional (3D) molecularly imprinted quartz crystal microbalance (QCM) sensor for trace CIT detection was constructed by electro-polymerizing o-aminothiophenol on Au nanoparticles@mesoporous carbon CMK-3 (AuNPs@CMK-3) functional composite modified Au electrode surface. Herein, AuNPs@CMK-3 functional composite acted as signal amplifier since the 3D structure and large specific surface area of AuNPs@CMK-3 functional composite were beneficial to increase the amount of effective imprinted sites and subsequently improve the sensitivity of the sensor. The preparation process of the QCM sensor was characterized by scanning electron microscope, transmission electron microscope, cyclic voltammetry and electrochemical impedance spectroscopy. Under the optimal conditions, the proposed sensor showed a linear frequency shift to the concentration of target CIT ranging from 6.0 × 10−9 to 2.0 × 10−7 mol L−1 with a low detection limit of 1.8 × 10−9 mol L−1 (S/N = 3). The sensitive sensor exhibited excellent selective recognition, anti-interference capability, reproducibility and long-term stability, and was successfully applied to analyze trace CIT in cereal samples with satisfactory recoveries, suggesting the proposed sensor is promising for the detection of CIT at trace levels in foods.