A simple and convenient electrochemiluminescence immunoassay by using gold nanoparticles as both label and co-reactant

A simple and convenient electrochemiluminescence immunoassay (ECLIA) has been developed by using gold nanoparticles (AuNPs) as both label and co-reactant. In this novel ECLIA, the detection antibodies labeled with AuNPs as co-reactant reacts directly with ruthenium complex to produce electrochemiluminescence (ECL), which avoids the weakness of luminophore as a label. The feasibility of the new method was investigated through the sandwich ECL immunosensor for the determination of human immunoglobulin (HIgG), and excitation of luminescence was respectively driven by linear sweep voltammetry and step potential. Under the optimal conditions, ECL intensity of the immunosensor increased with HIgG concentration in a wide range from 0.01 to 10.0 ng/mL and displayed linear response to logarithm of HIgG concentration. The results showed that the detection limit was 5 pg/mL, and the relative error was no more than 4.6% for the repeated measurements. The relative standard deviation was less than 2.9% for the determination of the standard sample, which can meet the requirement of ECLIA.