High-performance electrochemical sensing of circulating tumor DNA in peripheral blood based on poly-xanthurenic acid functionalized MoS2 nanosheets

A high-performance sensing platform based on poly-xanthurenic acid (PXA) film functionalized MoS 2 nanosheets was developed for electrochemical detection of circulating tumor DNA in peripheral blood. The MoS 2 nanosheets were obtained using a simple ultrasonic method from bulk MoS 2 . The physical adsorption between MoS 2 and aromatic XA monomers effectively improved the electropolymerization efficiency, accompanied with an increased electrochemical response of PXA. The obtained PXA/MoS 2 nanocomposite not only served as a substrate for DNA immobilization but also reflected the electrochemical transduction originating from DNA immobilization and hybridization without any complex labelling processes or outer indicators. The immobilization of the probe ssDNA was achieved via noncovalent assembly due to the π–π interaction between PXA and DNA bases. After the hybridization of the probe ssDNA with the target DNA, the formation of helix structure induced the resulted dsDNA to be released from the surface of the PXA/MoS 2 nanocomposite. The detection limit of this constructed DNA biosensor was calculated in the linear target DNA concentrations range from 1.0 × 10 –16 mol/L to 1.0 × 10 -10 mol/L and it was found to be 1.8 × 10 –17 mol/L.