Preparation And Application Of Bio-small Molecule Sensor Modified By Graphene Oxide Composite Nanomaterials

In this article,we present a simple and sensitive electrochemical DNA biosensor based on graphene oxide(GO)/chitosan(CS)hybrid nanocomposites modified glassy carbon electrode(GCE)for detection of Escherichia coli 0157:H7(E.coli 0157:H7).The morphology and composition of GO and hybrid nanocomposites were characterized by transmission electron microscope(TEM),X-ray powder diffraction(XRD),field emission scanning electron microscopy(FESEM),and Fourier transform infrared spectrum(FTIR).Cyclic voltammetry investigations indicated that the GO/CS/GCE showed excellent electron transfer ability and good linear relation.Under the optimal hybridization conditions,electrochemical impedance spectroscopy(EIS)responses of ssDNA/GO/CS/GCE biosensor were in linear with the target DNA in the concentration range from 1x10-14-1xl0-8 M with the detection limit as 3.584x10-15M(3?).Graphene oxide was synthesized in aqueous phase,and characterized by FTIR,transmission electron microscope(TEM),scanning electron microscope(SEM),and XRD.An electrochemical DNA biosensor was fabricated on graphene oxideand gold nanoparticles(AuNPs)modified GCE.The single-stranded DNA(ssDNA)probe was immobilized on the surface of electrode by biological coupling agent.Methylene blue was also used in the process of detection as hybridzation indicator.The process of detection was represented by scanning electron microscopy(SEM),cyclic voltammetry and differential-pulse voltammetry.As the results,the limit and range of detection were 5.372x10-13M(3?,n=5)and 1.0x10-11-1.0x10"7M,respectively.The electRochemical DNA biosensor based on graphene oxide(GO)/TiO2 hybrid nanocomposites modified glassy carbon electrode was synthesized,and characterized by transmission electron microscope(TEM),scanning electron microscope(SEM),cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS).