An electrochemiluminescence biosensor based on silver-cysteine nanorod as an emitter and AgNP-decorated FeMoO_ν as a signal amplifier for sensitive detection of heart-type fatty acid binding protein

An electrochemiluminescence (ECL) immunosensor was developed for the highly sensitive and specific detection of heart-type fatty acid binding protein (H-FABP) and the rapid diagnosis of acute myocardial infarction (AMI). H-FABP is a biomarker that is highly specific to cardiac tissue and is associated with a range of cardiac diseases. Following myocardial injury, the rate of increase in H-FABP levels is greater than that observed for myoglobin and troponin. Therefore, the measurement of H-FABP is crucial for the early exclusion of AMI. Silver-cysteine nanorod (AgCysNR), which served as the ECL emitter, was produced with a one-step, green, simple, template-free aqueous phase method. The surfaces of AgCysNR displayed many amino and carboxyl groups that were connected to a large number of a secondary H-FABP-specific antibody. Ferrum-doped molybdenum oxide (FeMoO_ν), with a large specific surface area, was richly decorated with silver nanoparticle (AgNP), which increased the interfacial electron transfer rate of FeMoO_ν. The AgNP was used as a co-reaction accelerator to promote persulfate to produce more sulfate anion radical and then enhance the ECL intensity of AgCysNR. The linear range of the ECL immunosensor was 10 fg/mL to 100 ng/mL, and the detection limit was 2.3 fg/mL (signal/noise = 3). The sensor was determined to be stable, repeatable, and reproducible, and the method achieved recoveries of 101.0 to 102.6% with relative standard deviations of 1.4 to 2.0%. This immunosensor represents a promising tool for the early diagnosis of AMI.