Carbon Nanomaterials Enhanced Electrochemical Biosensor For DNA Detection In Genetically Modified Food

In recent years,with the emergence of genetically modified foods,genetically modified food safety issues become a public concern.Detection of specific nucleotide sequences of genetically modified food is becoming more and more important.The development of simple,rapid,cheap,miniaturized DNA sensor has become a research hotspot.The electrochemical DNA sensor has become a new topic in biology and medicine because of its quick response,good selectivity,high sensitivity and low cost.In this paper,the specific transgenic sequence is the detection object.Hemin-rGO nanocomposites,Gold nanopartic-les(AuNPs),multi-walled carbon nanotubes(WMCNTs)and gold nanoparticles-thionine(THi-AuNPs)were used to modify the glassy carbon electrode(GCE),and a new type of electrochemical DNA biosensor with high convenience,high sensitivity and low detection line was constructed.Analysis of genetically modified food.The main contents of this paper include the following four parts: 1.Preparation and characterization of Hemin-rGO nanocompositesMixed with oxidized graphite and Hemin,and then added with reducing agent hydrazine hydrate and ammonia,after stirring,the oil bath,centrifugal cleaning to obtain a stable presence of Hemin-rGO nanocomposites.The structure and surface morphology were characterized by UV-vis and X-ray photoelectron spectroscopy(XPS).The electrochemical sensors was prepared by modification of GCE with Au NPs and Hemin-rGO nanocomposites,and the electrochemical performance was characterized by electrochemical method.2.Non-labeled electrochemical gene sensor for ultra low detection of glassy carbon electrode based on heme-graphene nanocomposites and gold nanoparticlesThe electrochemical sensors was prepared by modification of GCE with Au NPs and Hemin-rGO nanocomposites.Double-stranded DNA formed by HS-DNA and cDNA base complementary pairing blocks hemin redox reaction to reduce the current accordingly.In the absence of any external label,a simple,sensitive and selective sensing platform was build for detecting cDNA.The detection range of cDNA was from 1×10-18 to 1×10-13 M,the coefficient was 0.998,and the detection limit was 1.41×10-19 M.This method validates the sample detection rate and the percent recovery of the standard sample.The experiments shows that the sensor has the advantages of reliability,high selectivity and reproducibility,and it is the ideal platform for detecting DNA.3.Preparation and characterization of thionine-gold Nanoparticles-DNA NanocompositesThe THi-AuNPs nanocomposites were formed by immobilizing THi onto the surface of gold nanoparticles reduced by chloroauric acid.And then it mixed with the activated mercapto-labeled DNA(S1)to prepare THi-AuNPs-S1 nanocomposites successfully.The structure and surface morphology were characterized by UV-Vis spectroscopy.And the electrochemical performance was characterized by electrochemical method.4.DNA technology based on amination of multi-walled carbon nanotubes and horseradish peroxidase double signal amplificationThe electrochemical DNA sensors based on amination WMCNTs,AuNPs,THi and horseradish peroxidase modified GCE was prepared.The horseradish peroxidase catalyzes the peak of the CV reduction peak of hydrogen peroxide to detect DNA and achieve the dual signal detection of DNA.The electrochemical DNA sensor detection limit is 3.524×10-21 M and in the appropriate detection conditions it can achieve the detection of DNA.And the electrochemical DNA sensor has good selectivity,stability,reproducibility and high reproducibility,which is the ideal platform for detecting DNA of genetically modified food.