The linkages between AuNP, GO, and electrodes were based on covalent bonding through aryldiazonium salt coupling chemistry, which enhanced the stability of the sensing interface. The researchers immobilized the anti-cTnI detection antibody on GO modified with ferrocene molecules, which functioned as a signal reporter for the detection of cTnI. They monitored the modification process using electrochemistry, SEM, and XPS. The immunosensor showed high sensitivity and selectivity against human-cTnI, with a detection limit of 0.05 ng mL-1, which is 100 times lower than that possible by conventional methods. The researchers suggest that this portable sensing platform based on AuNPs and GO nanocomposites has the potential for future point-of-care diagnostics. Another study was conducted on the use of nitrogen-doped reduced graphene oxide (N-prGO) for detecting and quantifying cardiac troponin I (cTnI), a human cardiac protein biomarker, under physiologically relevant conditions. The N-prGO was modified noncovalently with 1-pyrenecarboxylic acid (py-COOH) and poly(ethylene glycol) modified pyrene (py-PEG) ligands to enable covalent integration of the Tro4 aptamer, which is known for its high selectivity towards cTnI. Using differential pulse voltammetry (DPV), a label-free electrochemical sensor was developed for cTnI detection with concentrations as low as 1 pg mL-1 in human serum.