An AuNPs/Co3O4 nanocubic cage–based electrochemiluminescent immunosensor for Corin: A biomarker of stroke

Stroke, or cerebral apoplexy, is a paroxysmal disease that seriously threatens the neurological functions of middle-aged and older men, resulting in high rates of disability and mortality. The blood level of Corin can accurately predict the risk and subtype of stroke. Herein, an immunosensor was developed utilizing a nanocomposite of Au nanoparticles and Co3O4 nanocubic cages (AuNPs/Co3O4NcC) as the sensing substrate, with luminol serving as the sensing probe for Corin detection. Through the application of 3-aminopropyltrimethoxysilane, AuNPs/Co3O4NcC was affixed to the surface of indium tin oxide (ITO)-coated glass, considerably enhancing the electrochemiluminescence (ECL) performance of luminol due to its peroxidase-like activity. To confer biological specificity by immobilizing the Corin antibody on this substrate and to block residual active sites with bovine serum albumin, an immunosensor was developed. The capture of Corin protein by the antibody through an immune reaction, leading to its binding on the sensor, resulted in a decreased ECL signal. Under optimized conditions, the proposed ECL immunosensor demonstrated a broad linear response range from 1 pg/mL to 4800 pg/mL and a low detection limit of 0.26 pg/mL. This ECL immunosensor is characterized by its specificity, stability, and reproducibility and can detect Corin in real blood samples.