An electrochemical biosensor for direct detection of PIK3CA gene related to lung cancer was developed based on riboflavin 5'-monophosphate sodium salt (FMNs)-functionalized MoS2 nanosheets prepared by simple ultrasonication method. As a highly effective biodispersant, FMNs demonstrated excellent stabilization for obtaining highly dispersed MoS2 nanosheets in an aqueous solution. The prepared FMNs/MoS2 nanocomposite with fine electrochemical redox activity was employed as the platform to immobilize DNA probe and supplied the inherent indicator signal for DNA sensing. The amine-terminated ssDNA probe was covalently immobilized onto the FMNs/MoS2 nanocomposite with rich phosphonate groups. After the hybridization of the probe ssDNA with the complementary target DNA, the self-redox signal of the nanocomposite decreased ascribed to the changes in the conformation of DNA. The results indicated that the proposed self-signal detection platform displayed high sensitivity with a detection limit of 1.2 × 10–17 mol l−1 for PIK3CA gene from lung cancer, accompanied with fine selectivity, outstanding stability and reproducibility. The constructed biosensor was easy to design and had the potential for the detection of different pathogenic DNA without intricate label process.
In our study, we report the development of molybdenum disulfide (MoS2) nanosheet-supported poly(indole-6-carboxylic acid) (PIn6COOH) and its usage for the electrochemical determination of circulating tumor DNA (ctDNA) such as PIK3CA gene associated with breast cancer. The MoS2 nanosheets prepared by the solvent exfoliation method from commercial bulk MoS2 were first immobilized on the surface of a carbon paste electrode; then, PIn6COOH, a novel electroactive material, was electropolymerized on the MoS2 substrate by the potentiostatic method to form a unique nanocomposite structure. The physical adsorption between aromatic In6COOH monomers and MoS2 efficiently improved the electropolymerization efficiency, resulting in increased electrochemical response of PIn6COOH. Owing to the presence of abundant carboxyl groups, probe ssDNA was covalently immobilized on the carboxyl-terminated PIn6COOH/MoS2 nanocomposite through free amines of DNA sequences based on 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydrosulfosuccinimide crosslinking reaction. The covalently immobilized probe ssDNA could selectively hybridize with its target DNA to form dsDNA on the surface of the PIn6COOH/MoS2 nanocomposite. The self-signal changes of PIn6COOH induced by DNA immobilization and hybridization could be sensitively recognized via cyclic voltammetry and electrochemical impedance spectroscopy. This developed biosensor showed high performance of DNA hybridization with a detection limit of 1.5 × 10−17 mol L−1 for the detection of PIK3CA gene. The easy construction of this biosensor besides its fine sensitivity and very low time consumption can make this PIn6COOH/MoS2 nanocomposite very highly competitive for further applications in carcinoma diagnostic and therapeutic fields.
危险品化学品经营许可证（带存储）