Study On Bacillus Cereus In Milk-derive Electrochemical Immunosensor Based On Gold Nanoparticles

Novel electrochemical biosensors for hydrogen peroxide,bovine immunoglobulin G and Bacillus cereus based on electrochemical detection analysis which could achieve automation detection,free the effects of sample color and turbidity,and simple equipments were needed;the efficiency of enzymatic reaction;and immunoassay which pretreatments such as enrichment and purification were needed were prepared for food safety.Covalent bonding,electrostatic adsorption and self-assembled were used to immobilize biomolecules onto the glassy carbon electrode combined the advantages of chitosan and gold nanoparticles.A novel hydrogen peroxide biosensor based on horseradish peroxidase/GNPs-thionine/chitosan has been developed.Gold nanoparticles fixed with horseradish peroxidase were adsorbed on glassy carbon electrode by the chitosan which cross-linked with the electron mediator of horseradish peroxidase as the bridge linking agent.The assembly procedures were monitored by UV-visible spectral scanning,bio-layer interferometry,cyclic voltammetric and alternating current impedance.The chronoamperometry was used to measure hydrogen peroxide.The hydrogen peroxide biosensor linear range of detection is 1×10-7~ 1×10-4mol/L,detection limit up to 5.0×10-8mol/L.Moreover the stability,reproducibility and selectivity of the biosensor were also studied and the results confirmed that the biosensor exhibit fast response to hydrogen peroxide and possess high sensitivity,good reproducibility and long-term stability.A novel construct immunosensor for bovine immunoglobulin G in the milk,dietary and colostrum supplements have been described.The sensing platform of the immunosensor combined advantages of the gold nanoparticles and chitosan,could maintain biological activity well.Anti-bovine IgG-HRP is immobilized by the gold nanoparticles.Assembly procedures are monitored by alternating current impedance and cyclic voltammetry to explore electrochemical properties of electrode surface.The chronoamperometry is used to measure the standard bovine IgG in phosphate buffer.The rates of the stable current before and after immunization are linening relationship with quality concentration of bovine IgG ranging from 0.1-10000 ng/mL and the correlation coefficient is 0.9976.The immunosensor is characteristics of excellent reproducibility and stability,low cost,easy operation,and could be applied to the quality control of bovine IgG products.A novel Bacillus cereus immunosensor based on double-layer gold nanoparticles has been developed,which the first layer of gold nanoparticles fixed on glassy carbon electrode by the chitosan,and the monoclonal antibody of Bacillus cereus was adsorbed;the second layer of gold nanoparticals was fixed by droping electrode with thionine-chitosan/NG-HRP complex.The assembly procedures were monitored by cyclic voltammetric and alternating current impedance.The chronoamperometry was used to measure Bacillus cereus.The Bacillus cereus immunosensor linear range of detection is form 5×101to 5×104cfu/mL with a correlation coefficient of 0.9966,while the detection limit up to 10 cfu/m L according to three times of the blank value standard deviation.And the preliminary practical application was studied what could lay the foundation for dairy quality control.