Rapid Detection Of Salmonella InvA Gene Based On Electrochemical Dna Sensing Method Sensitized By Nanocomposite

Salmonella is one of the main pathogens causing human food-borne diseases such as gastroenteritis and typhoid,is also one of the four causes of diarrhea in global wide.In recent years,the repeated incidents of food poisoning and food recalls resulting from Salmonella posed a serious threat to human health and cause tremendous economic.At present,the detection methods of Salmonella such as bacterial culture and immunological recognition with long time consuming,high cost and complicated experimental conditions could not satisfy the requirement of rapid detection.Therefore,it is urgent to find rapid and efficient analysis methods for Salmonella detection without complex equipment and large amount of manpower.In recent years,electrochemical DNA sensors which has characteristics in rapid detection,high sensitivity,low cost,easy operation and portability were widely used in the fields such as molecular biology and biological detection.In this paper,two ultra-sensitive DNA electrochemical sensing platforms of simple operation,good selectivity and repeatability was constructed by using gold nanoparticles(Au NPs),silver nanoclusters(Ag NCs),polypyrrole reduced graphene oxide(PPy-r GO)and avidin horseradish peroxidase(SA-HRP)separately with the fragment of inv A gene of Salmonella used as detection objectThe content of this paper contains two parts as follows:1.DNA electrochemical sensor based on Au NPs-s DNA Nanoprobe and in situ synthesis of silver nanoclustesIn this work,A sensitive electrochemical sensing method for detection of inv A gene sequence of Salmonella was described.GCE modified by Au nanoparticle layer(dep Au NP)was used to capture DNA probe,and Au NPs-s DNA nanoprobe prepared with Au NPs and thiol-s DNA was immobilized by connection of target DNA(t DNA)as to form sandwich-type hybridization construction.With Au NPs-s DNA nanoprobes as signal amplifying molecule and Ag NCs formed in the cytosine-rich oligonucleotide region as signal molecules,a novel and highly sensitive electrochemical DNA sensor was developed by electrochemical differential pulse voltammetry(DPV).The linear relationship between electrochemical signal and concentration ranged from 1 f M to 0.1n M(R=0.996)and the detection limit was 0.162 f M.the electrochemical DNA sensor showed good selectivity,stability,reproducibility and high reproducibility and could be used for real sample detection.2.DNA electrochemical sensor construction based on double signal amplification strategy by PPy-r GO nanocomposites and Au NPs-HRP-SA nanocompositesPyrrole monomer(Py)and graphene oxide(GO)were used as raw materials to prepare polypyrrole reduced graphene oxide complex(PPy-r GO)by chemical method,and the morphology and composition analysis of the composite were carried out.The polypyrrole reduced graphene oxide(PPy-r GO)and the avidin horseradish peroxidase modified gold nanoparticles(Au NPs-SA-HRP)were used as the bottom layer and the terminal signal amplifying molecule respectively to construct a sandwich type DNA electrochemical sensing platform while hydrogen peroxide(H2O2)and hydroquinone(HQ)was used as reaction substrate.The experiment indicated a good linearity range from 0.1 f M to 0.1 n M between the current signal of benzoquinone(BQ)which was oxidation products of hydroquinone(HQ)and concentration of t DNA by method of electrochemical differential pulse voltammetry(DPV).The detection limit was 15.8 a M(S/N = 3).The sensing platform showed good selectivity,stability,reproducibility,regeneration and potentiality for detecting Salmonella in real sample.