Dual-Mode Electrochemical and Electrochemiluminescent Aptamer Biosensors for Point-of-Care Detection of Cardiac Troponin I

Acute myocardial infarction (AMI), a leading cause of global mortality, requires the rapid and accurate detection of cardiac troponin I (cTnI) for prompt intervention. To address this, we present an innovative dual-mode electrochemiluminescence-electrochemical (ECL-EC) aptasensor for point-of-care detection of cTnI. The platform employs Fe₃O₄/PEI/CdS quantum dots (QDs) (FePQ) functionalized with a Tro6 aptamer as ECL-active capture probes and ferrocene (Fc)-encapsulated UiO-66-NH₂ (UFc) conjugated with a Tro4 aptamer as dual-functional signal probes. Upon cTnI binding, a sandwich complex forms, enabling dual-signal transduction: ECL signal attenuation is achieved through energy transfer or electron transfer between FePQ and proximal UFc and enhanced square wave voltammetry (SWV) response from accumulated UFc moieties. This ECL-EC mechanism enables self-verification, significantly reducing false signals, while achieving a wide linear range from 0.001 to 100 ng/mL with low detection limits (0.49 and 0.74 pg/mL) for 60 min. Notably, the dual-mode detection system also demonstrates remarkable consistency for cTnI quantification in clinical samples. The integration of magnetic separation, aptamer-based recognition, and UiO-66-NH₂-enhanced signal amplification ensures clinical practicality. The system demonstrates exceptional specificity, reproducibility, and stability in human serum analysis, not only providing a transformative solution for point-of-care AMI diagnostics but also establishing a versatile framework for developing multimodal biosensors targeting other biomarkers, advancing precision medicine in cardiovascular care.