The Research On The Electrochemical DNA Biosensor For Detection Of The Specific Of Genetically Modified Food Based Au Nanoparticles

The raw materials of GMF contain specific promoters, terminator and marker genes, which come from microorganisms and are different from non-transgenic plants. The detection of the promoter, terminator and marker genes can determine whether is GFM or not. GMF commonly uses CaMV35S and NOS DNA fragments. The detection of the presence of CaMV35S promoter genes or NOS terminator genes can be sure from the transgenic plant of the sample to a certain extent. The present study on the Au nanoparticles-based-on electrochemical DNA biosensors is not rich in GMF testing aspects and has lower sensitivity. Therefore, the thesis uses Au nanoparticles because of its biocompatibility and high surface area, combined with electrochemical biosensors that are created simply, high sensitivity, good reproducibility, low cost, good selectivity and that can be used in vivo detection and that is easy to realize miniaturization. We develop the electrochemical biosensor to achieve the detection of CaMV35S specific DNA sequence, provide a theoretical basis for better monitoring and detection of genetically modified food. The paper includes the following three parts:1Study on the detection of CaMV35S promoter gene sequences based on Au nanoparticles self-assembled electrochemical DNA biosensorsThis chapter uses Au-S bond to immobilized HDT on a AuE and then fixed AuNPs using the same principles, preparing AuNPs/HDT/AuE and becoming a good platform for DNA hybridization. Application of DPV and electrochemical impedance spectroscopy characterizes DNA hybridization steps and the DPV signal of the electrochemical indicator of MB changes as a detection signal measurement of target DNA. Optimizing equilibration time of MB, hybridization time and the hybridization temperature help to establish a suitable DNA electrochemical biosensors with a high sensitivity. Experimental results show that the DNA electrochemical biosensor can successfully detect CaMV35S gene fragments. The linear range is from1.010-12to1.010-8mol/L and the linear correlation coefficient is0.9991. The detection limit is1.110-13mol/L.2Study on electrochemical biosensors for detecting CaMV35S gene sequences with Au-nanoparticles-labeled DNABy preparing the mercapto-modified DNA probe on Au electrode hybridized with Au nanoparticles-labeled target DNA, changes of the DPV current peak of the electrochemical indicator [Ru(NH3)6]3+are for detecting CaMV35S gene sequences. Electrochemical impedance spectroscopy characterizes DNA hybridization steps on the Au electrode surface. Optimizing the fixed time of DNA probe, hybridization time and ionic strength of the hybridization solution are good for the establishment of a selective, high sensitivity, good reproducibility and stability of electrochemical biosensors.3Study on electrochemical biosensors for detecting CaMV35S gene sequences based on "sandwich" structureThis chapter studys the capture probes SH-DNA1self-assembled on the Au electrode surface, formating self-assembled molecular layer by layer. The amplification of the signal is caused by each of a DNA-functionalized Au nanoparticles with a number of DNA strands. The self-assembled molecular layer, the target DNA and DNA-functionalized Au nanoparticles constitute an "sandwich" structure electrochemical DNA biosensors. Experimental results show that the DNA electrochemical biosensor can successfully detect CaMV35S gene fragments. The linear range is froml.010-13to1.010-8mol/L and the linear correlation coefficient is0.9984. The detection limit is2.410-13mol/L. The biosensor has a good stability.