High-Precision Microfluidic Impedance Sensing for Pretreatment and Detection of Multiple Mycotoxins.

Mycotoxin contamination frequently causes considerable food safety problems. Unfortunately, for on-site mycotoxin detection, the experimental continuity and the stability of the results are affected by human operation in the sample pretreatment process, which brings a series of errors and further affects the experiment. Considering that, a centrifugal microfluidic chip is developed for the continuous automatic operation of each preprocessing step, which can simultaneously pretreat ochratoxin A (OTA), deoxynivalenol (DON), and aflatoxin B1 (AFB1) with high throughput under optimal conditions. More importantly, the time-series impedance method is proposed for detection, which amplifies the signal difference of the three mycotoxins and provides better high temporal resolution. The whole on-chip pretreatment and detection took only 15 min. To further improve the advantage of the proposed sensor, the MXene@AuNPs modified electrode is proposed to obtain superb detection performance with high sensitivity. The standard curves of the three mycotoxins are established for accurate quantitative analysis. Variances of OTA, DON, and AFB1 standard curves are 0.9839, 0.9888, and 0.9793, respectively. The detection limits of OTA, DON, and AFB1 are 7.1 ng/L, 1.24 μg/L, and 11.8 ng/L. The average recovery of this method ranges from 94.0 to 106.1%, indicating good reliability and reproducibility. Moreover, the developed method exhibits negligible cross-reactions with other mycotoxins. This technique can be used for the early detection of mycotoxins, with great prospects and potential application for on-site instant detection.