A non-competitive surface plasmon resonance immunosensor for rapid detection of triazophos residue in environmental and agricultural samples

The wide application of an organophosphate pesticide triazophos raises concern on the environmental pollution and the potential risk to human health. Thus, it is crucial to regularly monitor triazophos residue in the environment and agro-products. Herein we described a non-competitive immunoassay for trace detection of triazophos using a direct surface plasmon resonance (SPR) biosensor. Two anti-triazophos monoclonal antibodies (mAbs) were immobilized on the sensor chip and characterized by SPR-based kinetic analysis. The mAb with relatively slow dissociation rate was used for direct immunosensing of triazophos. The biosensor assay showed a high specificity and a low detection limit of 0.096ngmL^-1 to triazophos, with the linear detection range of 0.98-8.29ngmL^-1. Under the optimal condition, the sensor chip could be regenerated for 160cycles at least. Moreover, the sensitive method was applied to determine triazophos in the spiked environmental water and agricultural products, as well as in unknown real-life samples (including Chinese cabbage, cucumber, and apple). Desirable results demonstrated that the newly-developed immunosensor could be used as a rapid, convenient, and reliable tool to regularly monitor triazophos and meet the detection requirement of its maximum residue limits.