▎ 摘　　要

NOVELTY - Preparing electrochemical DNA sensor of complex modified electrode based on chitosan-graphene-gold nanoparticle comprises preparing ionic liquid modified carbon paste electrode, modifying the nano-gold and chitosan-graphene complex sequentially, placing on ionic liquid modified carbon paste electrode, adding the ssDNA probe to the surface of modified electrode dropwise for immobilization to obtain the product. USE - The electrochemical DNA biosensor is useful for detecting Staphylococcus aureus characteristic sequence (claimed). ADVANTAGE - The biosensor increases electrochemical signal and has large surface area with good conductivity. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) electrochemical DNA biosensor; and (2) use method of electrochemical DNA biosensor comprising (1) preparing different modified electrode, placing the cyclic voltammetry and electrochemical impedance spectroscopy (EIS) to characterize the electrode at working electrode interface in potassium ferricyanide solution, (2) soaking the different immobilized electrode in methylene blue solution, washing with 0.5% sodium dodecyl sulfate and distilled water and studying with differential pulse voltammetry MB on different modified electrodes electrochemical behavior, (3) coating the phosphate buffered saline solution containing different concentrations of target ssDNA sequences on the surface of ssDNA-CTS-GR-AuNPs-CILE, hybridizaing, washing with 0.5% sodium dodecyl sulfate and secondary distilled water to remove unhybridized target sequences and to obtain electrode dsDNA-CTSGR-AuNPs-CILE, soaking the hybridized in solution of methylene blue, washing with 0.5% sodium dodecyl sulfate and secondary distilled water, measuring the reduction current by differential pulse voltammetry (DPV) to obtain the complementary ssDNA sequence concentration and current value of relationship between the size of curve to study the sensitivity of the electrochemical DNA sensor and (4) hybridizing ssDNA-CTS-GR-AuNPs-CILE with different target ssDNA sequences, soaking the hybridized electrodes in methylene blue solution, removing, washing with 0.5% sodium dodecyl sulfate and secondary distilled water, carrying out differential pulse voltammetry (DPV) assay, recording the response current of MB to build study the selectivity of DNA sensors.