Quartz Crystal Microbalance Sensor Based On Molecularly Imprinted Polymer For Citrinin Determination

Citrinin(CIT),a mycotoxin with high toxicity,carcinogenicity,teratogenicity and mutagenicity,contaminates various commodities of plant origin,especially the cereals.Several analytical methods have been successfully developed to assay CIT in complex samples such as high performance liquid chromatography(HPLC),high performance liquid chromatography tandem mass spectrometry(HPLC-MS/MS),enzyme-linked immunosorbent assay(ELISA)and thin-layer chromatography(TLC).Nevertheless,every method was born with shortcomings,for example,HPLC and HPLC-MS/MS needed to consume a large amount of mobile phase,enzymes and antibodies used in ELISA were inconvenient to store,the sensitivity of TLC was relatively low in general.Consequently,the development of a rapid and sensitive method for the determination of CIT is highly desired.A novel three-dimensional(3D)molecularly imprinted quartz crystal microbalance(QCM)sensor for trace citrinin(CIT)detection was constructed by electro-polymerizing o-aminothiophenol(o-AT)in the presence of the dummy template 1-hydroxy-2-naphthoic acid(HNA)on an Au electrode(AuE)surface decorated by Au nanoparticles@mesoporous carbon CMK-3(AuNPs@CMK-3)functional composite.Herein,AuNPs@CMK-3 functional composite acted as a signal amplifier since the 3D structure and large specific surface area of the 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(SEM),transmission electron microscope(TEM),cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS).Several critical parameters which could affect the performance of the proposed sensor were investigated and optimized in detail.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.The proposed sensor was successfully applied to analyze trace CIT in cereal samples with satisfactory recoveries which were in accord with the results obtained from the traditional HPLC method,suggesting the proposed sensor is promising for the detection of CIT at trace level in foods.