Electrochemical immunosensor based on ferrocene derivatives amplified signal for detection of acute myocardial infarction warning biomarker-cTnI

As a biomarker of acute myocardial infarction (AMI), screening for cardiac troponin I (cTnI) has extremely high clinical sensitivity and specificity, and is extremely important for early intervention and risk assessment of AMI. Therefore, a novel redox-active hybrid material, CS-Fc, was synthesized by the Schiff base reaction of chitosan (CS) and ferrocene-carboxylic acid (Fc(COOH)) to form an amide group bonded together, which was used as a substrate-modified material for screen-printed carbon electrode (SPCE), and then assembled with an antibody (Ab), which was constructed into a label-free electrochemical immunosensor for the highly sensitive and rapid detection of cTnI in this study. The redox activity and biocompatibility of the highly stable and conductive composite CS-Fc significantly increased the effective specific surface area, electron transfer rate, and achieved effective amplification and specific analysis of the response signal. Under the optimized experimental conditions, the immunosensor showed a good linear relationship between its response signal and cTnI concentration in the range of 2.44 × 10−2 ∼ 2.50 × 101 ng mL−1, with a limit of detection (LOD) as low as 3.70 × 10−3 ng mL−1 (3σ, n = 11). Meanwhile, when used for the detection of cTnI in actual serum samples, it showed better reproducibility and stability, and the analytical results were better than those of the ELISA method, which indicated that it has a great potential for the accurate and rapid detection of cTnI in serum samples. In addition, it also provides a reliable means and scientific basis for process screening, early warning and prognostic risk assessment of AMI.