Two-end self-priming induced cascade amplification system for label-free photosensitization colorimetric detection of microRNA

MicroRNAs (miRNAs) are pivotal regulators in disease progression and have emerged as significant biomarkers for the early detection, therapeutic intervention, and management of ovarian cancer. The integration of highly sensitive and reliable miRNA detection techniques with ultrasound imaging has the potential to significantly improve the diagnostic accuracy of cancers. In this study, we developed a novel colorimetric approach for the sensitive and reliable detection of miRNAs. This method combines self-priming-mediated DNA polymerization with target recycling and a SYBR Green I (SG)-induced colorimetric response. The sensor operates through a three-stage mechanism: (i) target recognition initiates the formation of a self-priming structure; (ii) an exponential isothermal amplification process, driven by DNA polymerase, facilitates signal amplification; and (iii) a photo-catalyzed color change enables label-free signal generation. Using miRNA-21 as a model target, this approach allows for precise miRNA-21 detection without the need for primers, while the SG-based photo-catalyzed color reaction minimizes background signal interference. The sensor demonstrates the ability to distinguish single-base mismatches in homologous sequences and maintains robust performance in complex biological environments. Furthermore, the sensor has been successfully applied to accurately quantify miRNA-21 levels from constructed samples, highlighting its substantial potential for clinical diagnostics and disease monitoring applications.