A novel electrochemiluminescence immunosensing strategy fabricated by Co(OH)2 two-dimensional nanosheets and Ru@SiO2–Au NPs for the highly sensitive detection of enrofloxacin

Abstract

In this work, a novel sensitive electrochemiluminescence immunosensor based on Ru@SiO₂–Au NPs and Co(OH)₂ two-dimensional nanosheets (2D Co(OH)₂) is constructed for the detection of enrofloxacin (ENR). Ruthenium bipyridine silica spheres and modified gold nanoparticles were synthesized as immune probe materials, which were combined with ENR antibodies (Abs) to form the immune probe part. 2D Co(OH)₂ with a large specific surface area and good catalytic effect was firstly used as an immune substrate material, and at the same time, it was conjugated with the coating antigen (Ae) of ENR to form an immune substrate. Based on the principle of competitive immunity, ENR and ENR coated antigen could jointly compete for the specific binding sites on the ENR antibody, so as to achieve efficient detection of ENR. Under optimal conditions, the prepared immunosensor exhibited high sensitivity with a wide linear range from 0.0001 to 1000 ng mL⁻¹ and a low detection limit (LOD) of 0.063 pg mL⁻¹. The proposed immunosensor has been successfully applied to the detection of ENR residues in poultry, aquatic products and lake water.