Herein, we present one three-way junction (TWJ) DNA based electrochemical biosensor for sensitive microRNAs detection with locked nucleic acid (LNA) as capture probe and enzyme-free redox cycling signal amplification strategy. LNA owns higher binding affinity and thermal stability compared to normal DNA sequence . In the presence of target microRNA (miRNA-21), novel TWJ structure can be specially triggered with the assistant of methylene blue (MB)-tagged DNA signal probe, thus producing an enhanced electrochemical current. Furthermore, a chemical reductant, tris (2-carboxyethyl) phosphine (TCEP), is adopted to lead a relayed electron transport between solution TCEP and TWJ-linked MB tag and amplified whole signal intensity. Based on the selectivity from target-induced LNA/DNA TWJ structure and enzyme-free MB cycling amplification strategy, the designed electrochemical biosensor exhibits sensitive miRNA-21 detection, with a linear range from 100 aM to 100 pM and a low detection limit of 77 aM. In addition, it can successfully discriminate the differences between the miRNA family members, presenting a promising response to the direct determination of target miRNA-21 in real biological fluids. Our work provides an alternative LNA-based electrochemical biosensor way in the area of miRNA diagnostics and clinical analysis without complicated enzyme/nanomaterials-assisted signal amplification.
Deoxynivalenol (DON) contamination in cereals is a widespread issue with global implications, necessitating the development of efficient detection methods. Here, a fluorescent aptasensor integrating target-responsive DNA three-way junction (TWJ) and DNA walking machine was developed to detect DON. The DON-specific aptamer (Apt) and the walker (Walker DNA) are integrated into TWJs. TWJs initiate the DNA walking machine with the assistance of Nb. Bbv CI to provide signal amplification for sensing events. The constructed fluorescent aptasensor selectively recognizes and detects DON. Additionally, the sensing platform explored the quantitative relationship between fluorescence signal changes and DON concentration, achieving a limit of detection (LOD) of 0.009 ng/mL. Ultimately, the method performed well in the detection of cornmeal samples with recoveries ranging from 95.49 % to 100.82 %. The method demonstrates good stability and is expected to be a potential candidate for the accurate detection of DON in grains.
危险品化学品经营许可证（带存储）