Tree Molecular Compound Preparation Of Nanometer Materials Modified Electrodes And Its Detection Of Poisonous And Harmful Chemicals

Chitosan (chitosan) has the excellent physicochemical andbiological properties of good biodegradability, biocompatibility,membranous forming, non-toxic and no pollution as a kind of naturalbiological polymer materials, application is very extensive.Poly(amidoamine)dendrimer is a kind of macromolecule which hasmany branches and three-dimensional spherical structure. because ofits structure contains a lot of definite numbered terminal groups and theinternal cavity, internal cavity can be loaded with good electricalcatalytic activity of the metal nanoparticles, and the terminal groupshave a critical impact on physical and chemical proterties of molecule.Moreover, the various functional groups can be combined on thedendrimer surface to expand its function. In this paper, we combinedmultiwalled carbon nanotubes, the metal nanoparticles and PAMAM toform modified electrode, and studied their electrochemicalapplications.Ⅰ.Preparation of Glassy Carbon Electrode Modified with AuNanoparticles Encapsulated in Dendrimers and Its Application forDetermination of NitriteA simple and reliable method was developed for theelectrochemical determination of nitrite based on glassy carbonelectrode(GCE) modified with Au nanoparticles(AuNPs) encapsulatedin dendrimers. Firstly, chitosan(Chit) was modified on the GCE, and inthe presence of coupling agent carbodiimide, carboxyl-terminatedpoly(amidoamine)(generation4.5) dendrimers were covalentlyattached onto chitosan through the formation of amide bondsbetween carboxylic acid groups of the dendrimer and amine groups ofchitosan. The Au (Ⅲ) ions were coordinated in the interior of dendrimer with nitrogen ligands and then reduced to form AuNPs，which waswritten as Den(AuNPs)/Chit/GC electrode. The Den(AuNPs)/Chit/GCelectrodes were characterized with cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS). The experimentalresults showed that the present Den (AuNPs)/Chit/GC electrodes haveexcellent sensitivity for nitrite determination. The chronoamperometricstudies revealed that the amperometric response was rapid andstable，and offered a linear dependence over the ranges of nitriteconcentrations from2μmol/L to20μmol/L and0.07mmol/L to1.12mmol/L with a limit of detection(S/N=3) down to1.0μmol/L. Themethod was applied in the determination of nitrite in real sample withsatisfactory result. Den(AuNPs)/Chit/GC electrodes are to provide ananostructured platform for the development of electrochemicalsensors and biosensors.Ⅱ.Electrochemical determination of Cr(VI) based on Aunanoparticle modified electrodesThis study describes a simple and reliable method for theelectrochemical determination of hexavalent chromium [Cr(VI)] basedon Au nanoparticles (AuNPs) modified carbon nanotube. MultiwalledCarbon nanotubes was drop onto the treated glassy carbon electrode(written as MWNT/GCE), The AuNPs were electrodeposited onto acarbon nanotubes modified electrode via an electrodeposition step(written as AuNPS/MWNT/GCE) and which were used for theelectrochemical determination of hexavalent chromium. The studiesshow that the AuNPS/MWNT/GCE modified electrodes demonstratedsignificantly enhanced electrochemical activity towards Cr(VI)reduction. The formed of Au nanoparticles were characterized bycyclic voltammetric (CV) and field emission scanning electronmicroscopy(FESEM). Chronoamperometry studies reveal that theamperometric response is rapid, stable,and the outstanding sensitivity and selectivity to Cr(Ⅵ) reduction. A linear relationship between thereduction current and Cr(Ⅵ) concentration was obtained covering theconcentration rang from1μumol/L to7μmol/L and10μmol/L to130μmol/Lwitha limit of detection (S/N=3) down to0.1μmol/L Ⅲ.Electro chemical behavior and detection of bisphenol A basedon AgNPs/PAMAM/MWNTs/GC modified electrodes This article describes a simple and reliable method fortheelectrochemical determination of BPA based onAgNPs/PAMAM/MWOTs/GCE modified electrodes. The carboxyl ofmultiwalled carbon nanotubes was drop onto the treated glassycarbon electrode (written as MWNTs/GCE), a mino-terminatedpoly(amidoamine)(generation4.0) dendrimers were covalentlyattached onto MWNTs through the formation of amide bonds. Agnanoparticles (AgNPs) encapsulate in dendrimers via anelectrodeposition step, which was written asAgNPs/PAMAM/MWNTs/GCE The AgNPs/PAMAM/MWNTs/GCEmodified electrodes were characterized using cyclic voltammetry(CV),electriche micalimpedance spectroscopy(EIS). The experimental re sultsshowed that the AgNPS/PAMAM/MWNTs/GCE modified electrodesdemonstrated significantly enhanced electrochemicalactivity towardsBPA. The chronoamperometry studies reveal that the amperometricresponse is rapid, stable, and offers a lineardependence overrange ofBPA from0.1μM～1.3μM with a limit of detection (S/N=3) down to0.01umol/L This method was applied in the determination of BPA in realsa mp le with sa tisfa c to ry re sult.