Impedance based nanocrystalline silicon oxide immunosensor electronic tongue for ultrasensitive and low cost multiple food toxin detection

摘要

Nanocrystalline silicon oxide (nc-SiO2) immunosensor has been reported earlier to detect a single food toxin from a mixture of other toxins with a detection limit of 0.1 fg/ml by impedance spectroscopy method. But there are no reports of detecting multiple food toxins in complex mixtures using these sensors. Usually, detection of `n' number of food toxins requires `n' number of monoclonal antibodies which increases the fabrication cost. In this paper, for the first time, ultrasensitive detection of two target toxins-Aflatoxin B1 (AFB1) and Ochratoxin A (OTA) using only anti-AFBl antibody has been made possible by utilizing the selective peak frequency impedance response and the noise spectroscopy response of nc-SiO2 sensors. An electronic tongue (E-tongue) has been developed using an array of 5 such sensors. Corn seeds have been spiked with different toxin mixtures of AFB1 and OTA and tested with the E-tongue. The extracted parameters have been processed using principal component analysis (PCA) and partial least squares discriminate analysis (PLS-DA). It has been observed that the sensor array, functionalized with only anti-AFB1 antibodies, can quantify both AFB1 and OTA down to 0.1 fg/ml in unknown corn samples using multivariate data analysis. This is the most sensitive and economic E-tongue reported so far for food toxin estimation.