A portable point-of-care testing platform for rapid and sensitive miRNA-21 detection for heart failure diagnosis.

Background: MicroRNAs (miRNAs) play a pivotal role in various physiological and pathological processes. In particular, miRNA-21 holds significant potential as a novel biomarker for the diagnosis of heart failure. The development of miRNA detection methods is rapidly advancing, with point-of-care testing (POCT) platforms garnering considerable attention. However, traditional methods are often hampered by their reliance on expensive instruments and complex procedures, limiting clinical applicability. Therefore, there is an urgent need to develop a simple, portable, sensitive, and rapid POCT platform for miRNA-21 detection.

Results: In this work, we proposed a portable POCT platform using a colorimetric biosensor specifically sensitive for miRNA-21. The platform utilized 3,3',5,5'-tetramethylbenzidine as the signaling molecule, and a Linear G-quadruplex loaded with Blocker Nanostructures (LGBN) generated by the RCA reaction as the probe. Furthermore, changes in primary color channels (R/G/B) of TMB for miRNA-21 detection were analyzed via smartphone-based digital image recognition. Under optimal conditions, the platform showed a linear detection range between 0.01 nM and 1 nM, with limits of detection of 8.3 pM (colorimetric methods) and 9.5 pM (digital image colorimetry). Moreover, the colorimetric biosensor exhibited excellent specificity and resistance to interference, successfully detecting miRNA-21 in serum samples from heart failure patients.

Significance: This detection method has an accuracy consistent with RT-qPCR results, providing a novel and practical approach with POCT for miRNA-21 detection.