“…Immunoassays are a principal analytical technique in bioanalysis constructed by the formation of an immunocomplex between an antigen and antibody, which uses different labels like radioactive isotopes, enzymes, and fluorophores for signal development. − Currently, these molecular labels are gradually being replaced by functional composite nanomaterials since they have tremendous optical and catalytic properties or biological activities and enhanced chemical stability. − Numerous nanomaterial-based immunoassays have been developed for the detection of various biological and chemical targets such as cells, proteins, pathogens, and small molecular toxins. − Presently, according to the labels used, immunoassays are of several types, including enzyme-linked immunosorbent assay (ELISA), ,, radioimmunoassay (RIA), , electrophoretic immunoassay (EIA), − colorimetric immunoassay, , fluorescence immunoassay (FIA), , chemiluminescence immunoassay (CLIA), , electrochemical immunoassay (ECIA), − and electrochemiluminescence immunoassay (ECLIA). − Among them, ECLIA has been paid excited attention in clinical practice due to its high sensitivity, specificity, easy operation, and low background signal, and it does not require any radioactive materials. − For instance, ECLIA has been successfully applied to detect various targets in 50–150 μL of serum sample with the limit of detection (LOD) up to picomolar concentration. − Though, the concentration of some target analytes associated with early cancer or infectious diseases found in the blood serum and plasma samples of patients is <10 –15 mol/L. , Thus, the development of an ultrasensitive ECLIA for the selective detection of trace biological analytes in real samples is highly challenging.…”