Low background self-primer EXPAR coupled with colorimetric and lateral flow assay for rapid and sensitive point-of-care detection of miRNA

MicroRNAs (miRNAs) have emerged as powerful biomarkers for various diseases diagnosis, yet their clinical application is greatly plagued by the lack of reliable and rapid detection methods. Here, a simple, fast, and accurate point-of-care testing (POCT) platform for miRNA-155 detection was developed by interfacing self-primer exponential amplification reaction (SPEXPAR) with colorimetric and POCT lateral flow assay (LFA). In this platform, a hairpin template was designed for exponential amplification reaction, which could effectively avoid nonspecific template interactions and eventually effectively avoid undesirable background amplification; the colorimetric assay is based on the SPEXPAR amplicons induced gold nanoparticles (AuNPs) color change; and the LFA detection principle involves the amplicons hybridization with designed probes. Under the optimized conditions, the colorimetric assay could detect miRNA-155 as low as 0.41 pM in less than 35 min; and LFA could detect as low as 100 pM in less than 40 min. Furthermore, the method was adopted to detect miRNA-155 in human serum samples with satisfactory recoveries. In summary, this study offered a promising analytical tool for molecular diagnostic testing application.