A highly sensitive electrochemiluminescence immunosensor based on magnetic nanoparticles and its application in CA125 determination

A novel electrogenerated chemiluminescence (ECL) immunoassay based on enzyme amplification and magnetic nanoparticle enrichment was developed, and carbohydrate antigen 125 (CA125) was chosen as the analyte. Fe₃O₄ magnetic nanoparticles loaded with anti-CA125 were synthesized. The sandwich-type immunoassay was performed on the magnetic force-controlled carbon paste electrode via the immunoreactions among glucose oxidase-labeled anti-CA125, CA125, and anti-CA125 on the surface of magnetic nanoparticles. ECL was generated by the reaction between luminol and hydrogen peroxide. Hydrogen peroxide was produced during the enzymatic reaction with glucose and markedly increased in the presence of CA125 antigen. The CA125 concentrations were determined within the range of 0–10?mU?mL^?1, and the detection limit was 8.0 μU mL^?1. The CA125 immunosensor was more sensitive than those previously reported. The proposed ECL method also provided a simple selectivity immunoassay protocol, which was applied in the determination of CA125 in clinical serum samples.