Simple and sensitive detection of miRNA-122 based on a micro-biosensor through square wave voltammetry

Abstract

The simple and sensitive detection of miRNA-122 in blood is crucially important for early hepatocellular carcinoma (HCC) diagnosis. In this work, a platinum microelectrode (PtμE) was prepared and electrodeposited with molybdenum disulfide (MoS₂) and gold nanoparticles (AuNP), respectively, and denoted as PtμE/MoS₂/Au. The prepared PtμE/MoS₂/Au was used as the microsensor for the detection of miRNA-122 combined with the probe DNA as a biorecognition element which is the complementary strand of miRNA-122. The PtμE/MoS₂/Au conjugated with the probe DNA modified with sulfydryl units was used as the micro-biosensor for the detection of miRNA-122. The square wave voltammetry was performed for the quantitative detection of miRNA-122 using [Fe(CN)₆]^4−/3− as a mediator. Under the optimized conditions, the PtμE/MoS₂/Au micro-biosensor shows a linear detection toward miRNA-122 ranging from 10⁻¹¹ to 10⁻⁸ M (S = 6.9 nA dec⁻¹, R² = 0.9997), and the detection limit is 1.6 × 10⁻¹² M (3σ/b). The PtμE/MoS₂/Au micro-biosensor demonstrates good selectivity against other types of proteins and small molecules, and has good reproducibility. Moreover, the PtμE/MoS₂/Au micro-biosensor was successfully applied for the measurement of miRNA-122 in real blood samples. Herein, the proposed detection assay could be a potential tool in HCC clinical diagnostics with high sensitivity.