A novel bimetallic MXene derivative QD-based ECL sensor for miRNA-27a-3p detection

In this work, a novel ECL biosensor has been developed based on bimetallic MXene derivative QDs (Mo2TiC2 QDs) and SnS2 nanosheets/lipid bilayer to detect the gastric cancer marker miRNA-27a-3p. On the one hand, the inter-band excitation of Mo2TiC2 QDs can inject the additional carriers, which were less suppressed by boundary effects and made a significant contribution to the luminescence process. Semiconductor Mo2TiC2 further inhibited the formation of internal electric field and potential oxidation. Therefore, Mo2TiC2 QDs processed superior luminous intensity and better stability. On the other hand, SnS2 nanosheets coated with phospholipid bilayer were designed as sensing interface. SnS2 nanosheets not only enhanced the luminous intensity of Mo2TiC2 QDs by virtue of their large surface area and low dielectric constant, but also improved the stability of lipid bilayer. Due to the excellent properties and synergy work of Mo2TiC2 QDs and the lipid bilayer-modified SnS2 nanosheets, the sensing system displayed high sensitivity and good reproducibility in the analysis application. As a result, the biosensor displayed good linear correlation between the ECL intensity and the concentration of miRNA-27a-3p over a wide range from 1 fM to 10 nM with the detection limit as low as 1 fM. The sensing system including the joint contribution of Mo2TiC2 QDs, SnS2 nanosheets and lipid bilayers had great potential for clinical applications.