Ultrasensitive detection of miRNA based on single-walled carbon nanotube@MoS2 field-effect transistor regulated by atomic layer deposition

MicroRNAs (miRNAs) act as diagnostic markers for various diseases, and achieving ultra-sensitive detection of miRNAs has an important effect on early disease diagnosis. Field-effect transistor (FET) biosensor exhibits superior sensitivity compared to conventional clinical detection instruments in detecting biomolecules. However, developing high-sensitive FET biosensors for detecting microRNAs remains challenging. In this study, we developed a FET biosensor using MoS2 and a network film of semiconductor single-walled carbon nanotube (SWCNT) as channel materials. The MoS2 cycles were precisely controlled and optimized by atom layer deposition (ALD), and the optimized 3-cycle device exhibited the best performance. This adjustment is beneficial for enhancing the charge transfer between SWCNT and MoS2, as well as improving the on/off ratio and mobility of FET devices. Additionally, the SWCNT@MoS2 structure offers a larger specific surface area, providing more active binding sites on the sensing interface. These two favorable factors contribute to the realization of linear detection miRNA-21 from 1 × 10−17 to 1 × 10−10 mol L−1 in biosensors. The theoretical detection limit of the biosensor is 1.9 × 10−18 mol L−1. This work develops a novel approach to achieve highly sensitive detection of miRNA for high-performance FET biosensors.