Electrochemical determination of miRNA-155 using molybdenum carbide nanosheets and colloidal gold modified electrode coupled with mismatched catalytic hairpin assembly strategy

Abstract Catalytic hairpin assembly is a useful strategy for signal amplification. Nevertheless, the inherent high background makes it imperfectable in real applications. Herein, mismatched base pairs were introduced into the breathing sites of the hairpin substrates to improve the signal to noise ratio. An electrochemical biosensor for miRNA-155 detection using molybdenum carbide nanosheets and colloidal gold modified electrode based on mismatched catalytic hairpin assembly strategy was fabricated. Colloidal gold was electrodeposited onto molybdenum carbide nanosheets modified glassy carbon electrode to enhance electrochemical signal. Thioled H1 then was modified onto molybdenum carbide nanosheets and colloidal gold modified electrodes. In the presence of target miRNA-155 and ferrocenecarboxylic labeled H2 (H2-Fc), mismatched catalytic hairpin assembly was triggered, leading to the recycling of target. Thus H2-Fc was captured onto electrode surface. As a result, the electrochemical signal increases. The electrochemical signal increases linearly with the increase of miRNA-155 over the concentration range from 0.1 fM to 1.0 nM, with a detection limit of 0.033 fM (S/N = 3). The relative standard deviation was 3.2% when 10.0 fM miRNA-155 was measured under optimized conditions (n = 9). The results were satisfactory when this new method was applied to determine miRNA-155 in human serum samples.