A label-free electrochemical immunosensor based on AuNPs/GO-PEI-Ag-Nf for olaquindox detection in feedstuffs

Abstract

For the first time, a label-free electrochemical immunosensor was developed to detect olaquindox (OLA) in feedstuffs using graphene oxide (GO) nanocomposites (GO-PEI-Ag) decorated by silver nanoparticles (AgNPs) and functionalized by polyethyleneimine (PEI) as electrode modification materials. In this work, GO with huge specific surface area was used as a carrier to load abundant AgNPs, which exhibited good redox activity and perfect conductivity. The stability of GO-Ag in solution was ameliorated by PEI, which was utilized as a solubilizer. Nafion (Nf) was applied to attach tightly and uniformly GO-PEI-Ag nanomaterials on the electrode surface. The gold nanoparticles (AuNPs) were electrodeposited on the GO-PEI-Ag-Nf modified electrode surface for signal amplification and antibody immobilization. Above all, the electrochemical signal significantly improved. Under the optimal conditions, the signal intensity showed linear correlation with the logarithm of OLA concentration ranging from 0.01 ng mL−1 to 150 ng mL−1, along with the low detection limit of 4.8 pg mL−1. Moreover, the analytical performance in feedstuff samples was evaluated, showing favorable recovery of 90.0%-100.2% with RSD of 2.2%-6.9%. The fabricated biosensor can provide a suitable approach to measure OLA and is promising to detect other additives in feedstuffs.