Synchronous Visual-Photocurrent Dual-Readout for Cardiac Troponin I Sensing Enabled by Self-Powered Point-of-Care Platform

Abstract

Acute myocardial infarction is a life-threatening cardiovascular event, and point-of-care determination of cardiac troponin I (cTnI) is crucial for early diagnosis and timely intervention. Herein, a self-powered point-of-care sensing platform based on a light-driven bipolar electrode (BPE) for synchronous electrochromic and photoelectrochemical dual-readout detection of cTnI was reported. The BPE integrates a photocathodic sensing pole and an electrochromic reporting pole, enabling simultaneous generation of photocurrent and visual color change through a single photoinduced electron-transfer pathway. Magnetic molecularly imprinted microspheres (MMIPs) were employed as robust capture elements to selectively extract cTnI from biophysical samples. Subsequently, cTnI quantitatively bridges MMIPs with Cu-MOF@TiO2 nanoprobes to form a sandwich complex, which is immobilized onto the sensing pole. Upon light irradiation, the Cu-MOF@TiO2 composite generates photogenerated charge carriers, producing a photocurrent at the sensing pole while synchronously driving the reduction of Prussian blue (PB) to Prussian white (PW) at the reporting pole through the BPE circuit. The electrochromic response can be quantitatively analyzed by smartphone RGB imaging, providing visual detection of cTnI from 10–9 to 10–4 mg/mL, while the photoelectrochemical mode exhibits a wider linear range from 10–11 to 10–4 mg/mL. This work offers a portable, instrument-minimized, and self-powered dual-readout strategy for onsite cardiac biomarker analysis, and provides a versatile framework for future multiplexed biosensing applications.