Study Of Ce Enrichment And Separation Technology Based On Interface Accumulation And Au Nano-materials And Application

A dual concentration technique combining field-amplified sample injection andgold nanoparticles as multienzyme carriers was developed in this paper.AnovelE. coli detection platform based on immunoreaction, dual amplification focusing,capillary electrophoresis separation, and electrochemical detection was proposed forsensitive detection of E. coli in scallop samples. After noncompetitive immunoreactionbetween free E. coli antigen and excessive amount of horseradishperoxidase (HRP)-labeled anti-E. coli antibody tracer (Ab*) in liquid phase, theimmune sample was directly introduced into the separation capillary. Thefield-amplified sample injection process allows introducing large amount of analytesinto capillary to accumulate at the capillary inlet. Meanwhile, the negative chargedgold nanoparticles migrated to the anode and attracted the immune sample ions onto itssurface at the boundary of sample and buffer solution. Gold nanoparticles were used asmultienzyme carriers of the signaling Ab*and the bound enzyme-labeled complex(Ag-Ab*) in order to achieve a further amplification of the electrochemical detectionsignal. Then the bound Ag-Ab*and unbound Ab*were separated by capillaryelectrophoresis, and the E. coli could be detected according to theH2O2/o-phenylenediamine reaction currents catalyzed by HRP labeled on anti-E. coliantibody. The assay adopting field-amplified sample injection preconcentration andgold nanoparticles as enhancer resulted in the improved sensitivity of1400fold whencompared with traditional10kV electrokinetic injection for10s. The method allowedquantitative determination of E. coli concentration from2.0to2000cfu mL-1, with adetection limit of1.0cfu mL-1. The formed complex (Ag-Ab*) and the excessive Ab*were baseline separated with the separation efficiencies (theoretical plate number, N) greater than104plates/m. The relative standard deviation (RSD) values of the peakheight, peak area and migration time were2.6%,3.5%and3.1%, respectively. Theproposed field-amplified sample injection and gold nanoparticles enhanced capillaryelectrophoresis based immunoassay with electrochemical detection method wassuccessfully applied for the determination of E. coli in scallop samples.Capillary electrophoresis electrochemical detection technology Based on enhanced goldnanoparticles has been developed for Determination of shellfish toxins. After the competitiveimmune response between shellfish toxin antigen (Ag) and horseradish peroxidase (HRP)-labeledantigen (Ag*) and limited antibody (Ab), immune sample come into the capillary and react withgold nanoparticles. Gold particles change the moving speed of the analyte in the capillary, andincrease the resolution of the analyte. Besides, gold particles are used to carry more Ag*andenzyme markers (Ag*-Ab) in order to enhance the electrochemical (EC) signal strength. Fourkinds of shellfish toxins are baseline separated by gold nanoparticles modification. The standarddeviation of the migration time was1.3-3.5%and3.1-4.6%. The relative standard deviation of peakarea are2.8-4.6%and4.1-6.9%while the detection limit (S/N=3) is in3.1-36.7ng/L. Based onEC-IA (capillary electrophoresis with electrochemical detection) and horseradishperoxidase-conjugated gold nanoparticles matter strengthen capillary electrophoresis successfullyapplied to the simultaneous determination of four kinds of shellfish toxins in shellfish. This methodhas a high resolution and high sensitivity, showing a greatly potential in different ways of thesimultaneous determination of different red tide toxins in shellfish samples.Horseradish peroxidase (HRP) labeled antibody, using Au nanoparticles as carriers, we havediscovered a new technique for detection of E. coli. This technique is a kind of capillaryelectrophoresis electrochemical immunoassay technology which is based on Field-amplifiedsample and Au nanoparticles dual enrichment and is used together with the Electric stackingpreconcentration technique. Conduct field-amplified sample preconcentration directly after theimmune response of E. coli and enzyme-antibody, the immune sample quickly moved to the inletend of the capillary and aggregated. And at the same time, Au nanoparticles with a negative chargeill be moved to the anode end, and the sample ions is adsorbed up where the buffer solution incontact with the sample. Because Au nanoparticles exist and act as carriers, the detected signal isfurther amplified, and H2O2is catalyzed by the labeled HRP on the antibody. The current signalthat is used to detect the E.coli is produced by the oxidation of o-phenylenediamine. Comparedwith conventional electrokinetic injection capillary electrophoresis, techniques discussed in thischapter increases the detection sensitivity significantly1400times. Methods discussed in thisarticle has a detection limit of2.0~2000.0cfu mL-1, and outcome limit of1.0cfu mL-1, andcan rapidly and sensitively detect the presence of E. coli in a sample scallops.