One-Pot Synthesis of N-(4-Aminobutyl)-N-ethylisoluminol Doping Cuprous Oxide Nanocubes for Label-Free Chemiluminescence Immunoassay of Cardiac Troponin I

In this study, a novel chemiluminescence (CL)-functionalized nanomaterial, designated as ABEI@Cu₂O nanocubes, was synthesized by doping the CL reagent N-(4-aminobutyl)-N-ethylisoluminol (ABEI) into Cu₂O nanocubes via a simple one-pot method. The Cu₂O nanocubes not only functioned as an effective nanocarrier but also exhibited peroxidase-like activity, promoting the decomposition of H₂O₂ to enhance CL emission. The incorporation of ABEI into the Cu₂O nanocubes resulted in the concentration of the CL reagent within the cubic structures, reducing the spatial distance between the catalyst and ABEI and, thereby, enhancing the CL signal. The robust and stable CL emission of ABEI@Cu₂O nanocubes facilitated the development of a label-free CL immunoassay for the detection of cardiac troponin I (cTnI), a biomarker indicative of an acute myocardial infarction. This immunoassay demonstrated a wide linear detection range from 1.0 × 10^-13 to 1.0 × 10^-8 g/mL and a low detection limit of 3.27 × 10^-14 g/mL, surpassing all existing CL immunoassays for cTnI detection. Moreover, the proposed immunoassay demonstrated excellent sensitivity and precision in the quantitative detection of cTnI in serum samples from both healthy individuals and patients. The exceptional sensitivity and flexibility of this immunoassay, supported by the unique properties of the ABEI@Cu₂O nanocubes, highlight its significant potential for the detection of various biomarkers.