Ultrasensitive detection of miRNA-155 based on controlled fabrication of AuNPs@MoS2 nanostructures by atomic layer deposition.

MicroRNA-155 (miRNA-155) is a typical cancer-related biomarker, which often exists at ultralow concentrations in the plasma or body fluids of early patients. In this work, a novel label-free platform for ultrasensitive miRNA-155 detection was designed based on the precise fabrication of molybdenum disulfide (MoS2) by atomic layer deposition (ALD). Au nanoparticles (AuNPs)@MoS2 nanostructures were the core parts for the detection electrode, and the measurement precision of the sensing platform was modulated and optimized by ALD-based thickness and shape control of ultrathin MoS2 nanoflakes (thickness: ~14 nm, about 20 layers, uniform continuous distribution). In the detection experiment, MoS2 nanoflakes served as a conductive skeleton to support more AuNPs, and the results showed that the effective control of their morphology and thickness was of vital importance for ultrasensitive acquisition of detection signals. With using toluidine blue (TB) as a hybridization indicator, ultrasensitive detection record ranging from 1 fM to 10 nM with a detection limit of 0.32 fM can be achieved.