Oriented assembly of surface plasmon resonance biosensor through staphylococcal protein A for the chlorpyrifos detection.

In this study, we report a direct surface plasmon resonance (SPR) biosensor based on an oriented assembly of antibody for the rapid detection of chlorpyrifos residue in agricultural samples. In this covalent-orientated strategy, staphylococcal protein A (SPA) was first covalently bound to the surface for monitoring chlorpyrifos residue, with subsequent binding of the antibody in an orientated fashion via its fragment crystallizable (Fc) region. Consequently, the SPA-modified biosensor exhibited a satisfactory specificity and a low detection limit of 0.056 ng mL-1 for chlorpyrifos, with a linear detection range of 0.25-50.0 ng mL-1. Under optimal conditions, the sensor chip could be regenerated for at least 210 cycles. The results presented here indicate that the SPA-modified sensor chip can successfully improve the sensitivity and obviating the need of the modification of the antibody. The developed SPR biosensor method has the great potential for rapid, sensitive, and specific detection with broad applications in areas of environmental monitoring and food safety. Graphical abstract.