The Construction Of Electrochemical Sensors Based On Nanomaterials And Detection Of Peroxide And Nitrite

Electrochemistry sensors are widely used in many fields such as clinical diagnosis,bioanalysis, environmental monitoring, pharmaceutical industry, food detection and so on,because they have the advantages of high sensibility, good stability and selectivity,convenience and on line detection. The key of electrochemical sensors is the preparation ofthe chemically modified electrodes (CME). The CME is to fix the excellent chemicalinorganic material, organic material, polymer, and biological macromolecule on the electrodessuface with physical and chemical methods. It presents filmchemical, electrochemical, oroptical properties. With the unique chemical property, and the advantages of cheap, robust,high sensitivity, and good selectivity, CME is the most active fronties in electrochemistry andelectroanalytic chemistry.Owing to the surface effects, small size effect, quantum size effect and quantum tunneleffect, nano-materials have shown distinctive function in many fields such as optical,electronic, magnetic, adsorption, catalysis and so on. By using of the nano-materials modifiedelectrode, the electrode surface increases rapidly, the response of current also increases, thedetection reduces, and sensitivities enhance, which can analyze small dose of micromoleculesand biological samples. In addition, when the nano-materials are used to modify electrode, theelectrochemical active of the electrode will be greatly strengthened, and rate of electrontransfer is accelerated, and can retain the biological activity of the protein in great extent.Moreover, the inorganic nanomaterial have the properties of non-toxic effect, and goodbiocompatibility to provide favorable microenvironment to fix enzyme, moreover, they arealso as the raw material of mimetic enzymes. In this paper, we have studied the effect of thenano-materials modified electrode to the micromolecules such as nitrite, which could bedivided into five aspects as follow:1. An enzymeless sensor is explored from Cu-Mg-Al calcined layered double hydroxide(CLDH) modified electrode in this study. The Cu-CLDH greatly promotes the electrontransfer between H2O2and GCE, and it is exemplified towards the non-enzymatic sensing ofH2O2. The results indicate that the Cu-CLDH exhibits excellent electrocatalytic property, highsensitivity, good reproducibility, long-term stability, and fast amperometric response towardsreduction of H2O2, thus it is promising for the future development of man-made mimics ofenzyme in H2O2sensors. This work opens a way to utilize simply Cu-CLDH as an electronmediator to fabricate an efficient H2O2biosensor, which exhibits great potential applicationsin varieties of simple, robust, and easy-to-make analytical approaches in the future. 2. A novel nitrite sensor is constructed based on electrodeposition of gold nanoparticles(AuNPs) on a copper calcined layered double hydroxide (Cu-CLDH) modified glassy carbonelectrode. Electrochemical experiments show that AuNPs/CLDH composite film exhibitsexcellent electrocatalytic oxidation activity with nitrite due to the synergistic effect of theCu-CLDH with AuNPs. The fabricated sensor exhibits excellent performance for nitritedetection within a wide concentration and with a low detection limit. The superiorelectrocatalytic response to nitrite is mainly attributed to the large surface area, minimizeddiffusion resistance, and the enhanced electron transfer of the Cu-CLDH and AuNPscomposition film. This platform offers a novel route for nitrite sensing with wide analyticalapplications and will supply the practical applications for a variety of simple, robust, andeasy-to-manufacture analytical approaches in the future.3. We have developed a novel hydrogen peroxide (H2O2) biosensor based onelectropolymerization of thiophene-3-boronic acid film (TBA) in ionic liquid via glucosidicbond with glycoprotein horseradish peroxidase (HRP). A thin film of poly(thiophene-3-boronic acid)(PTBA) has been synthesized by electropolymerization usingroom temperature ionic liquids (RTIL) as the growth medium and the supporting electrolyte.Horseradish peroxidase (HRP) in this study shows affinity interaction with the formed PTBAthin film. With the aid of hydroquinone (H2Q) mediator, the biosensor has a fast response ofand a low detection limit. The developed biosensor exhibits fast response, a low detectionlimit, high stability and very good reproducibility.4. The graphene nanosheets and carbon nanospheres mixture (GNS-CNS) is prepared byelectrolyzing graphite rob in KNO3solution under a constant current. The cationic chitosan(CS) coated prussian blue (PB) as an efficient redox mediator can interact with the anionGNS-CNS via electrostatic interaction. The synergy effect of CS@PB nanoparticles andGNS-CNS contribute to the excellent electrochemical response towards the nitrite oxidation.The as-prepared CS@PB/GNS-CNS modified glass carbonelectrode (GCE) demonstrates itshigh sensitivity, low detection limit, short response time, and wide concentration range for thenitrite detection.5. An enzyme-free amperometric method has been established for the electrochemicalreduction tert-butyl hydroperoxide (TBHP) on the utilization of nano-cobalt phthalocyanine(CoPc) loaded functionalized graphene (FGR) and to create a highly responsive organicperoxide sensor. FGR is synthesized with a simple and fast method of electrolysis withpotassium hexafluorophosphate (KPF6) solution as electrolyte under the static current of0.2A.In the present work, FGR is dispersed in the solution of CoPc to fabricate chemical modified electrode to detect TBHP. The electro-reduction of TBHP can be catalyzed by FGR-CoPc,which has an excellent electrocatalytical activity due to the synergistic effect of the FGR withCoPc. The sensor can be applied to the quantification of TBHP with a wide linear range, ahigh sensitivity, and a low detection limit. This proposed sensor is designed as a simple,robust, and cheap analytical device for the determination of TBHP in body lotion.