Abstract
Development of novel nanomaterials for biosensors has intrigued widespread interest. Here, we report a method to graft the redox-active dye Methylene Blue (MB) onto molybdenum disulfide (MoS2) nanosheet surface via electrostatic and π-stacking interaction. The adsorption of MB on nanosheets was investigated by atomic force microscopy (AFM), which proved that the adsorption isotherm fits a Temkin not a Langmuir model. After studying the electrochemical properties of MB-decorated MoS2 nanocomposite (MoS2@MB) on a glassy carbon electrode (GCE), an electrochemical sensor for microRNA-21 detection was designed. The modified GCE can quantify microRNA-21 in concentrations as low as 68 fM, typically at a working potential of -0.28V (vs. SCE). The same modified electrode also shows outstanding electrocatalytic ability towards individual and simultaneous determination of dopamine (DA) and uric acid (UA) with electrochemical peaks at 0.16V (DA) and 0.45V (UA). The detection limits for simultaneous determination are 0.58μM for DA and 0.91μM for UA, respectively. Graphical abstract A powerful sensing electrode was obtained by grafting Methylene Blue (MB) on molybdenum disulfide (MoS2@MB) nanosheet surface. Such MoS2@MB-based electrochemical sensor was used to label-free detect microRNA and simultaneously determine dopamine and uric acid.
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