Enhanced DNAzyme-Based Tetrahedron Amplifier for Ultrasensitive Determination and Intracellular Imaging of Breast Cancer-Related microRNAs

MicroRNAs (miRNAs) have emerged as promising biomarkers for cancer diagnosis, making their accurate detection critical for early-stage diagnosis, effective treatment, and improved patient outcomes. To fully realize their clinical potential, there is an urgent need to develop an efficient and flexible miRNA detection platform that not only meets point-of-care testing (POCT) requirements but also enables the sensitive monitoring of spatiotemporal miRNA changes in living cells. Here, we developed a novel DNA tetrahedron amplifier, termed the tetrahedron (TDN)-DNAzyme-based catalytic hairpin assembly (CHA) reaction (TDCR). The TDCR system innovatively integrates the dual-cyclic mechanisms of DNAzyme activity and catalytic hairpin assembly, employing DNAzyme cleavage and DNA self-assembly to cascade amplify signals for detecting trace levels of miRNAs, with a sensitivity limit as low as 1.32 fM. Moreover, the system exhibits good anti-interference capability and stability, enabling precise detection in complex biological fluids. By combining biosensor chip technology with TDCR, we achieved visual detection under a fluorescence detector, fulfilling high-throughput detection needs. Furthermore, the TDCR sensor platform has been proven feasible for monitoring tumor-associated miRNAs expression in living cells, exhibiting excellent biocompatibility and signal stability. We envision that TDCR will enhance the clinical applicability of miRNAs-based liquid biopsy and facilitate the development of miRNAs as biomarkers for cancer diagnosis and prognosis.