A colorimetric aptasensor based on gold nanoparticles for point-of-care testing of cardiac troponin I

As a key biomarker in clinical diagnostics, cardiac troponin I facilitates the early diagnosis of acute myocardial infarction. This study developed a rapid quantitative method for detecting cardiac troponin I in blood, aiming to establish its quantitative correlation with myocardial infarction area by accurately quantifying the serum cTnI concentration in patients suffering from acute myocardial infarction. We utilized a cTnI-specific aptamer as the recognition element. Gold nanoparticles exhibit salt-induced aggregation with visible color change. The aptamer protects gold nanoparticles from high-salt aggregation. Through systematic optimization, we established a gold nanoparticle-based colorimetric assay leveraging this anti-aggregation mechanism. Results demonstrated that under optimal conditions—200 mM NaCl and 800 nM aptamer concentration—the developed assay exhibited a promising linear response (R 2  = 0.942) across a cardiac troponin I concentration spanning from 0.1 to 0.8 μg/mL. According to the standard calibration method, the detection limit was estimated as 0.1 μg/mL. We observed recovery rates ranging from 105.6 % to 118.5 %. This research presents a highly sensitive, specific, and rapid point-of-care detection methodology for cardiac troponin I, offering enhanced field-testing efficiency and providing a low-cost alternative for serum cardiac troponin I detection. Moreover, it lays the groundwork for the development of a novel methodology enabling dynamic and quantitative assessment of infarct size in patients suffering from myocardial infarction.