WS₂ nanosheets-based electrochemical biosensor for highly sensitive detection of tumor marker miRNA-4484

In this paper, a few-layer WS₂ nanosheets-based electrochemical biosensor was fabricated for the highly sensitive detection of breast cancer tumor marker miRNA-4484. Firstly, few-layer WS₂ nanosheets were prepared by shear stripping and characterized by SEM, TEM, AFM and UV spectrophotometer. After modification of few-layer WS₂ nanosheets on the electrode surface, the miRNA probe was fixed on the few-layer WS₂ nanosheets by polycytosine (PolyC). Then short-chain miRNA containing PolyC was used as the blocking agent to close the excess active sites on the surface of WS₂ nanosheets to complete the fabrication of the sensor biosensing interface. Finally, the current changes caused by the specific binding of miRNA-4484 to the probe were analyzed by differential pulse voltammetry (DPV). The results showed that the sensor had a good linear relationship for the detection of miRNA-4484 in the concentration range of 1 aM-100 fM, and the detection limit was as low as 1.61 aM. In addition, the electrochemical sensor had excellent selectivity, stability and reproducibility. The artificial sample tests indicated that the developed biosensors have the potential for clinical application in the future.