Colorimetric-chemiluminescent competitive lateral flow immunoassay for cardiac troponin I detection based on Au@CoO NPs nanozyme

Cardiac Troponin I (cTnI), a critical biomarker for diagnosing acute myocardial infarction (AMI), plays an essential role in clinical practice. While traditional lateral flow immunoassays (LFIA) are widely used for cTnI detection due to their simplicity and rapid results, they often suffer from limited quantification capability, low sensitivity, and compromised accuracy, limiting their broader clinical application. To overcome these issues, we developed a dual-signal LFIA (dLFIA) by incorporating Au@CoO nanoparticles (NPs) for quantitative and precise cTnI determination. The synthesized Au@CoO NPs present black color as colorimetric signals and its peroxidase-like activity was adopted to yield chemiluminescence (CL) signals. It is worth noting that sodium perborate was employed to replace hydrogen peroxide as the co-reactant for the aim of enhancing long-term stability and CL intensity. Such dual-signal strategy offers self-checking merit, significantly improving detection reliability. What is more, a portable assay device was designed for automatic release of the reagents involved, further simplifying the detection process. The dLFIA demonstrated a wide linear range with limits of detection of 0.39 ng/mL in colorimetric mode and 0.22 ng/mL in chemiluminescent mode, which are 8 and 15 times more sensitive than traditional LFIA, respectively. This dLFIA platform can act as a promising assay tool for point-of-care testing, particularly in AMI diagnosis and potentially in other applications.