Electrochemiluminescent competitive immunosensor based on polyethyleneimine capped SiO2 nanomaterials as labels to release Ru(bpy)32+ fixed in 3D Cu/Ni oxalate for the detection of aflatoxin B1

In this work, a highly-efficient competitive method-based electrochemiluminescence (ECL) immunosensor was proposed based on {[Ru(bpy)3][Cu2xNi2(1−x)(ox)3]}n (Cu/Ni/Ru) as luminophor to efficiently detect aflatoxins B1 (AFB1). Cu/Ni/Ru exhibited excellent ECL behavior. While polyethyleneimine capped silicon dioxide (PEI@SiO2) could decrease the ECL performance of Cu/Ni/Ru due that PEI could destroy the structure of Cu/Ni/Ru via producing the complex between PEI and metal ions (Cu(II)/Ni(II)), inducing the release of Ru(bpy)32+. Since Au nanoparticles can directly combine with antibody and antigen, the Cu/Ni/Ru and PEI@SiO2 was functionalized by Au nanoparticles. The quantitative detection of AFB1 was based on the competitive binding between AFB1-bovine serum albumin labeled Au-PEI@SiO2 (Au-PEI@SiO2-AFB1-BSA) and free AFB1 with antibody-AFB1 which immobilized on Au-Cu/Ni/Ru. The ECL signal increased with augmenting the concentrations of the free AFB1 due to less Au-PEI@SiO2-AFB1-BSA combining with antibodies. Under optimal conditions, the proposed immunosensor exhibited a wide linear range from 0.01 ng mL−1 to 100 ng mL−1 with a detection limit of 0.0039 ng mL−1 (S/N = 3). The proposed immunosensor also provides a promising approach for ultrasensitive detection of other mycotoxins.