Synergistic amplification via CHA–HCR for electrochemical and colourimetric dual-mode detection of carotid atherosclerosis biomarker

Abstract

Long non-coding RNA SOX2-OT (lncRNA SOX2-OT) has demonstrated notable potential for its clinical application as a potential biomarker of carotid atherosclerosis. However, accurate lncRNA-based carotid atherosclerosis diagnosis is hindered by the lack of ultrasensitive, simple, and highly specific detection methods. To tackle these challenges, we introduced an innovative strategy by integrating catalytic hairpin assembly (CHA) and hybridisation chain reaction (HCR) into a cascade signal amplification strategy to detect lncRNA SOX2-OT and enable precise carotid atherosclerosis diagnosis. CHA enables specific target recognition and initial signal amplification, whereas subsequent cascaded HCR generates long double-stranded DNA scaffolds with multiple G-quadruplexes. Simultaneously, methylene blue interacts with DNA structure, generating a potent electrochemical signal. Furthermore, the formation of peroxidase-mimicking hemin/G-quadruplex can catalyse 3,3’,5,5’-tetramethylbenzidine oxidation, enabling visual detection of the target. The biosensor exhibited a low limit of detection of 10 aM and successfully detected lncRNA SOX2-OT in serum samples. This CHA–HCR biosensor, with its enzyme-free, label-free, and highly sensitive nature, holds notable potential for clinical applications, particularly in assessing the severity of carotid atherosclerosis. This study introduces an ultrasensitive and highly specific method for lncRNA detection and offers a new analytical perspective and technical support for the diagnosis and molecular assessment of carotid atherosclerosis.