Dual-mode of electrochemical-colorimetric imprinted sensing strategy based on self-sacrifice beacon for diversified determination of cardiac troponin I in serum.

Diversified determination of cardiac troponin I (cTnI) in serum is of great significance for the clinical diagnose and daily monitoring of acute myocardial infarction. Herein, an electrochemical-colorimetric dual-mode imprinted sensing strategy was proposed. Firstly, the aptamer-functionalized Fe3+-polydopamine (Apt@Fe3+-PDA) was constructed as the self-sacrifice beacon. Furthermore, an epitope magnetic molecularly imprinted polymer was prepared to recognize cTnI. Once the cTnI was captured, the beacon was then bound to it through the aptamer, which formed a sandwich-like complex. Under acidic condition, the Apt@Fe3+-PDA was disintegrated to release large amount of Fe3+, and further converted to Prussian blue (PB). On one hand, the electrochemical response of the PB was sensitive to the cTnI amount. On the other hand, the addition of the yellow K3[Fe(CN)6] into different amounts of the produced PB was able to result in different colors, which enabled the visual detection of cTnI. Under the optimal condition, the sensing strategy exhibited a linear range from 1.0 × 10-2 to 1.0 × 103 ng mL-1, and the detection limits were 3.2 and 7.4 pg mL-1 for the electrochemical and colorimetric modes, respectively. Besides, It is demonstrated that the dual-mode strategy shows favorable selectivity and stability in the assays, indicating a diversified application prospect in both clinic analysis and daily care.