Enzyme-free amplification-enhanced ratiometric fluorescence method for highly sensitive detection of acute myocardial infarction biomarkers

A wide range of proteins, including enzymes, hormones, immune factors and regulatory proteins, are essential for a variety of physiological processes. Dysregulation of the levels of specific proteins in organisms is known to adversely affects the human body. Given the pathophysiological significance of cardiac troponin I (cTnI), simple methods for detecting the sensitivity and selectivity of cTnI in biological systems are in high demand and have therefore been extensively explored. Nonetheless, the early detection of low concentrations of cTnI in the human body continues to be a focal point and area of interest in bioassays, due to the low levels and intricate composition of biomarkers in bodily fluids (e.g., blood, sweat, urine, and saliva), which impose rigorous demands on the sensitivity and stability of detection methods. The assay platform is isothermal, homogeneous and has simple experimental conditions without proteases. Using ratiometric fluorescence with built-in self-correction, we achieved low background values and improved the accuracy of the assay results. Our method enhances detection sensitivity by utilizing the cycling of probe X during strand replacement. Triple sensitization was achieved by combining ratiometric fluorescence on the basis of normal strand displacement reaction. In the experiment, the dual sensitization was reflected by the high sensitivity (0.001 ng/mL) and wide linear detection range (0.001 ng/mL similar to 1000 ng/mL) of cTnI in real serum samples. In particular, the snapshots of the simulation process were recorded through accurate simulation calculations and multidimensional characterization analysis, which revealed the changes in the system energy during the simulation process. The sensing platform combines multiple technological advantages, and we are optimistic that the versatility of this research has great potential for application in the fields of early screening and diagnosis and military medical applications.