PtCo nanocubes/reduced graphene oxide hybrids and hybridization chain reaction-based dual amplified electrochemiluminescence immunosensing of antimyeloperoxidase.

Antimyeloperoxidase (anti-MPO) is regarded as one of the most important circulating autoantibodies for anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitides (AAVs). Hence, it is crucial for highly sensitive detection of anti-MPO to monitor efficacy of AAVs in clinical diagnosis. Herein, a highly sensitive electrochemiluminescence (ECL) immunosensor for anti-MPO detection was constructed by combining reduced graphene oxide-supported PtCo nanocubes hybrids (PtCo@rGO) with hybridization chain reaction (HCR) as signal amplification. Multiple ECL luminophores (Dox-ABEI) prepared by cross-linking of N-(aminobutyl)-N-(ethylisoluminol) (ABEI) and doxorubicin (Dox) were intercalated into dsDNA products of HCR, achieving the effective immobilization of ECL luminophores to obtain strong ECL emission. Benefiting from the efficient catalytic activity of PtCo@rGO toward H2O2, the massive the superoxide radical (O2●-) were generated to further react with ABEI for ECL emission. Thus, the designed ECL immunoassay for anti-MPO detection exhibited excellent sensitivity of a concentration variation from 50 fg/mL to 1 ng/mL and a detection limit of 15.68 fg/mL. Importantly, this work proposed an enzyme-free ECL immunoassay with high sensitivity, excellent specificity for protein detection in clinical diagnosis.