Metal-free microRNA-320b electrochemical sensor based on blue light-driven ring-opening metathesis polymerization signal amplification

Developing efficient strategies for the sensitive and accurate detection of esophageal squamous cell carcinoma (ESCC) biomarkers is critical for improving early diagnosis and preventive interventions. An electrochemical sensor incorporating a photo-redox mediated ring-opening metathesis polymerization (photo-ROMP) strategy was designed to achieve sensitive and selective detection of microRNA-320b (miRNA-320b), a key biomarker for ESCC. Two DNA strands served as capture probes to form a sandwich structure with miRNA-320b, and the initiator 2-(vinyloxy)ethanol (VEOH) was chemically attached to the DNA terminus. Upon blue LED irradiation, the photosensitizer 2,4,6-Tris(4-methoxyphenyl)pyridinium tetrafluoroborate becomes excited, oxidizes VEOH, generates active radical cations, and initiates the polymerization reaction, thereby amplifying the detection signal. The VEOH-triggered photo-ROMP strategy provides the advantages of metal-free operation, improved sensitivity, and simplified handling. Consistently, the method achieves a remarkably low detection limit of 1.1 fM, demonstrating its high sensitivity. In addition, the sensor exhibits good selectivity, stability and anti-interference ability, and still maintain excellent performance in complex actual samples, showing its application potential in early screening of ESCC.