A novel DSN-based fluorescence assay for MicroRNA-133a detection and its application for LVH diagnosis in maintenance hemodialysis patients

Highly Sensitive Fluorescence Assay for miRNA Detection: Investigation of the DNA Spacer Effect on the DSN Enzyme Activity toward Magnetic-Bead-Tethered Probes

Researchers have recently designed various biosensors combining magnetic beads (MBs) and duplex-specific nuclease (DSN) enzyme to detect miRNAs. Yet, the interfacial mechanisms for surface-based hybridization and DSN-assisted target recycling are relatively not well understood. Thus, herein, we developed a highly sensitive and selective fluorescent biosensor to study the phenomenon that occurs on the local microenvironment surrounding the MB-tethered DNA probe via detecting microRNA-21 as a model. Using the above strategy, we investigated the influence of different DNA spacers, base-pair orientations, and surface densities on DSN-assisted target recycling. As a result, we were able to detect as low as 170 aM of miR-21 under the optimized conditions. Moreover, this approach exhibits a high selectivity in a fully matched target compared to a single-base mismatch, allowing the detection of miRNAs in serum with improved recovery. These results are attributed to the synergetic effect between the DSN enzyme activity and the neutral DNA spacer (triethylene glycol: TEG) to improve the miRNA detection's sensitivity. Finally, our strategy could create new paths for detecting microRNAs since it obliterates the enzyme-mediated cascade reaction used in previous studies, which is more expensive, more time-consuming, less sensitive, and requires double catalytic reactions.

A novel DSN-based fluorescence assay for MicroRNA-133a detection and its application for LVH diagnosis in maintenance hemodialysis patients

Left ventricular hypertrophy (LVH) is the most powerful predictor of cardiovascular mortality in maintenance hemodialysis (MHD) patients. Circulating microRNA-133a (miR-133a) was reported to be a potential biomarker for LVH in MHD patients. The aim of this experiment is to establish a novel DSN (duplex-specific-nuclease)-based fluorescence assay for the ultrasensitive detection of miR-133a and investigate its application for LVH diagnosis in MHD patients. The results indicate DSN enzyme combined with ultrathin metallic MoS₂ nanosheets presents high sensitivity, specificity, and low fluorescence background for miR-133a detection. Then, circulating miR-133a levels in plasma from 40 MHD patients and 20 healthy controls are analyzed by such assay. The levels of miR-133a are down-regulated in MHD patients with LVH compared to MHD patients without LVH and healthy controls, and the ROC (receiver operating characteristic) curve shows strong separation between MHD with LVH patients and MHD without LVH patients. Furthermore, the liner regression analysis shows negative correlation of miR-133a level and interventricular septum thickness (IVS) as well as left ventricular mass index (LVMI), the indicators of LVH. Therefore, our findings reveal DSN-based fluorescence assay for miR-133a is suitable for LVH diagnosis in MHD patients.