Point-of-care testing of MicroRNA based on personal glucose meter and dual signal amplification to evaluate drug-induced kidney injury.

The upregulation or downregulation of microRNA-21 (miRNA-21) is closely related with drug-induced kidney injury (DIKI). As a potential and significant biomarker, the point-of-care testing (POCT) of miRNA-21 is worthy of attention and can provide essential information for clinical diagnosis. Hence, we design a portable and sensitive POCT assay for miRNA-21 using personal glucose meters (PGM). The whole operational system is constructed on streptavidin-coated magnetic beads (MBs) modified with substrate strands linked invertase and DNAzyme molecules each silenced by a locking strand. In the presence of miRNA-21, the locking strand can hybridize to miRNA-21, which originates the activation of the DNAzyme. The DNAzyme cleaves the substrate strands and induces the release of invertase from the surface of MBs. The separated invertase hydrolyzes sucrose to glucose which can be measured by PGM. The dual enzyme mediated catalyzation by DNAzyme and invertase therefore triggers the signal amplification. We establish a linear relationship between PGM and different concentration of miRNA-21 in the range of 100 fM to 1 pM. The limit of detection is 68.08 fM, which is comparable with some of the previous reports. The biosensor also exhibits excellent sequence selectivity, well-presented reproducibility and stability. Notably, by detecting miRNA-21 in urine, this method has been successfully used to predict DIKI and evaluate the protection effect of drugs on DIKI. Therefore, a dependable and low-cost POCT strategy for the detection of miRNA-21 is established, which is promising to supply valuable information for drug screening and evaluation of DIKI.