A Novel, Low-Voltage-Excited Luminol-OH^–Electrochemiluminescence System for Ultrasensitive Biosensing

Sensitive and accurate detection of low-abundance protein biomarkers is critical in biomedical research. In this work, a novel luminol-OH^–-Pd-WO_x/CNT electrochemiluminescence (ECL) system was developed, which is capable of generating intense ECL signals under low applied voltages (0–0.4 V) while eliminating the need for classical coreactants such as H₂O₂ or dissolved oxygen. As a result, it achieves enhanced ECL signal intensity with maintained signal stability, thereby establishing a robust foundation for the high-sensitivity signal output of the sensor. Furthermore, an intelligent responsive probe (DNAgel@MSN), gated by a dual-aptamer DNA hydrogel, was designed to achieve precise targeting and rapid response to the target analyte. The presence of the target protein triggers the disassembly of the gated structure, releasing signal molecules into the luminol-OH^–-Pd-WO_x/CNT ECL system to produce an ECL signal response. Ultimately, this approach enables the specific detection of carcinoembryonic antigen (CEA) with a remarkably low limit of detection (LOD) of 14.41 fg/mL.