Molybdenum disulfide/graphdiyne-based photoactive material derived photoelectrochemical strategy for highly sensitive MicroRNA assay

In this study, molybdenum disulfide-graphdiyne (MoS2-GDY) was successfully prepared. Utilizing the inherent reducibility of GDY, (NH4)(2)MoS4 was reduced to MoS2 forming photoactive material MoS2-GDY complex. MoS2-GDY made use of the large band-gap of MoS2 and the narrow band-gap of GDY. The naturally narrow band-gap of GDY enhanced the absorption of light and the combination of GDY and MoS2 reduced the electron-hole recombination rate so as to gain strong photoelectrochemical (PEC) signal. The PEC signal of MoS2-GDY changed with the mass ratio of GDY to (NH4)(2)MoS4. MoS2-GDY produced the strongest PEC performance at 1:25. MoS2-GDY with the mass ratio of 1:25 was used to fabricate a PEC assay for microRNA-141 detection. To obtain low background noise and strong PEC signal, a dual-modified probe coupling bio-bar code AuNPs and hybridization chain reaction strategy was designed. The dual-modified probe which labeled with MoS2-GDY on the one side, and marked with biotin on the other side. And the intensity of PEC depended on the concentration of microRNA-141. Under optimal conditions, 0.2 V potential, pH 7.5, the PEC assay had a linear range in 1.0 x 10(-17) mol/L to 1.0 x 10(-9) mol/L and a low detection limit of 3.3 x 10(-18) mol/L. The assay has been successfully applied to the determination of microRNA-141 in complex biological matrixes.