The Preparation Of DNA Sensor And The Detection Of Salmonella DNA And P53 Gene Respectively

Graphene oxide(GO)was reduced during the conventional carboxylation process caused by sodium hydroxide.Therefore,this work eventually proposed a protocol that sodium citrate and chloroacetic acid can be employed to enhance the density of carboxyl of graphene,in addition,carboxylated graphene oxide(CGO)offers lager surface area and thus provides much more favourable sites to attach probe DNA.Based on this novel method,positively charged Fe3Oa NPs was attached onto the surface of graphene oxide via electrostatic self-assembly,subsequently,probe DNA labeled with amino was covalently grafted onto the surface glassy carbon electrode modified by the composition of Fe3O4 NPs/CGO.Infrared spectrum(IR),nuclear magnetic resomance(NMR)and scan electron microscopy(SEM)were used to characterize GO,CGO,Fe3Oa NPs/GO and Fe3Oa NPs/CGO,respectively.Cyclic voltammetry(CV)was utilized to investigate Fe3Oa NPs was assembled onto the surface of GO and CGO more effectively,how electron transfer resistance changed and the amount of probe DNA was attached owing to the carboxylation process.Electrochemical impedance spectroscopes(EIS)was used to confirm the results obtained from CV.Differential pulse voltammetry(DPV)was finally employed to survey the detection performance of the developed DNA biosensor using methylene blue(MB)as a redox indicator,manifesting the linear detection range from 10-17 to 10-9 M for target DNA analysis with the detection limit up to 3.16×10-18M(S/N=3).Herein we designed a three-segment DNA biosensor based on carboxylated multi-walled carbon nanotubes(CMCNT)and CdTe qunatum dots for the detection of p53 tumor suppressor genes,scanning electron microscope was employed to characterize the shape of CMCNT.CdTe quantum dots were determined by IR,ultraviolet spectometer(UV),X ray diffiractometer(XRD).CV was utilized to characterize the stepwise preparation of the DNA biosensor.DPV was used to determine various concentration of capture DNA,and it indicates that the biosensor could achieve linear detection range from 10-9-10-13 M with the detection limit of 4.26×10-13 M(S/N=3).