MoS2 nanosheets supported on anodic aluminum oxide membrane: An effective interface for label-free electrochemical detection of microRNA

The interesting adsorption affinity of two-dimensional nanosheets to single stranded over double stranded nucleic acids have stimulated the exploration of these materials in biosensing. Herein, MoS2 nanosheets decorated anodic aluminum oxide (AAO) membrane was simply prepared by suction filtration. The MoS2/AAO hybrid membrane was initially applied to the electrochemical detection of microRNA using let-7a as the model. When let-7a was incubated with its complementary DNA, double stranded DNA-RNA formed and which displayed weak adsorption capability to the hybrid membrane. And thus the steric effect combining the electrostatic repulsion of the backbone phosphate of nucleic acids for [Fe(CN)6]3− transport across the hybrid membrane varied with the concentration of let-7a. In this way, a label-free electrochemical detection method for microRNA was established by monitoring the change of the redox current of [Fe(CN)6]3−. To further improve the detection sensitivity of the method, we proposed two separate strategies focusing on the amplification of the target-induced steric hindrance with DNA nanostructure and the magnification of the electrode sensitivity for [Fe(CN)6]3− by electrode modification. By using the two strategies, the hybrid membrane based-detection method exhibited broad linear range, low detection limit and good selectivity as well as reproducibility. Therefore, this study provided a proof-of-concept for the application of two-dimensional material to nucleic acids detection. MoS2 nanosheets were compacted onto the outer surface of the AAO membrane by vacuum filtration. And the MoS2/AAO hybrid membrane was applied as the interface to identify ssDNA probe and DNA-RNA duplex. The flux of the eletroactive reporter K3 [Fe(CN)6] across the hybrid membrane was monitored, allowing label-free electrochemical detection of microRNA. [Display omitted] •MoS2 nanosheets exhibited distinctive adsorbing capability to ssDNA and dsDNA.•MoS2/AAO was used as the effective detection interface.•Two strategies were proposed, which introduced G-quadruplex and modifying electrode respectively.•Both strategies improved the detection sensitivity.