Dual-mode electrochemical analysis of microRNA-21 using gold nanoparticle-decorated MoS₂ nanosheet

The detection of microRNA plays an important role in early cancer diagnosis. Herein, a dual-mode electronic biosensor was developed for microRNA-21 (miRNA-21) detection based on gold nanoparticle-decorated MoS₂ nanosheet (AuNPs@MoS₂). A classical DNA "sandwich" structure was employed to construct MoS₂-based electrochemical sensor, including capture DNA, target miRNA-21 and DNA-modified nanoprobe. [Fe(CN)₆]^3-/4- and [Ru(NH₃)₆]³⁺ were selected as electrochemical indicators to monitor the preparation process and evaluate the performance of MoS₂-based electrochemical biosensor by electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV), respectively. Such MoS₂-based biosensor exhibited excellent performance for miRNA-21 detection in the range from 10 fM to 1nM with detection limit of 0.78fM and 0.45fM for DPV and EIS technique, respectively. Furthermore, the proposed MoS₂-based biosensor displayed high selectivity and stability, which could be used to determine miRNA-21 in human serum samples with satisfactory results. All data suggested that such MoS₂-based nanocomposite may be a potential candidate for biosensing ranging from nucleic acid to protein detection.