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Novel Electrochemical Enzyme Biosensor Research Based On Several Inorganic/organic Nanocomposites

Posted on:2012-11-12Degree:MasterType:Thesis
Country:ChinaCandidate:Y LeiFull Text:PDF
GTID:2218330371463193Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
Electrochemical biosensor whose research contents are rich, is one of the important areas of biotechnology analysis. In recent years, a large number of research results has been made, and is widely available. Nano-materials have large specific surface area, good biological activity, high adsorption capacity and other characteristics, can significantly improve the performance of biosensors. With the introduction of nano-technology, the development of biosensors comes to a more advanced stage. In this paper, in order to assemble ordered nano-systems to build several new type of electrochemical sensing interface with excellent performance, we use situ self-assembly method,template method and seed-mediated method respectively. The developed biosensors have the advantages of simple fabricaiton, excellent performance, good reliability and easy regeneration. The details are summarized as follows:(1) In chapter 2, a novel amperometric sensor for hydrogen peroxide (H2O2) was developed based on noble metal nanoparticles in-situ formed on the electrode surface. Poly(acrylic acid) (PAA) was first electrodeposited onto a gold electrode. Then a certain proportion of platinum and palladium ions were chemically adsorbed within the PAA network, and subsequently reduced by hydrazine hydrate to yield zerovalent metal. The resultant metal nanoparticles were uniformly dispersed in the PAA network. Thus modified electrode showed good current response to H2O2 due to the catalytic activity of Platinum and Palladium particles. Under optimal conditions, linear relationship was observed for H2O2 reduction in the concentration range from 500nM to 20mM at the applied potential of ?0.1V and the detection limit was 500nM. The resulted sensor shows sensitive detection. By changing the functional polymers, metal ions and fixed biological molecules, the method is expected to build a variety of chemical and biological sensors.(2) In chapter 3, we report a simple, biomolecular friendly protocol for the fabrication of a hydroxyapatite nanowires array (HANWA) biosensor and its application to cyanide sensing. The HANWA is performed by template-assisted electrodeposition and it has a large surface area, spatial orientation and numbers of adsorption sites. The electrochemical biosensor for the determination of cyanide through its inhibitory effect on horseradish peroxidase (HRP) encapsulated by chitosan (CHIT) on the platform of hydroxyapatite nanowires array is demonstrated. A sensitive detection limit of 0.6 ng mL-1 was obtained for cyanide. The proposed HANWA/CHIT-HRP biosensor has the advantages of spatial resolution, high sensitivity, rapid regeneration and fast response associated with individual nanowires. The new device holds great promise for food industrial and environmental monitoring of toxins.(3) In chapter 4, for the first time, we introduced the seed-mediated method to the growth of cobalt hexacyanoferrate nanoparticles (CoNPs), using 3.5 nm gold nanoparticles as seeds and multiwalled carbon nanotubes (MWCNT) as growth scaffold, one-step synthesized CoNPs and prepared CoNPs/CNT modified electrodes successfully . Combined with glucose oxidase, the sensing surface is applied as a biosensor for glucose. The nanoseeds bridge the CoNPs and CNTs to form a smart nanocomposite. The synergy of CNT is good for cobalt hexacyanoferrate nanocomposites to play excellent electrochemical catalytic performance. The synthesis and fabrication/modification is simple and fast, expected to be extended to other types of nano-iron cyanide system.
Keywords/Search Tags:Electrochemical biosensor, Situ self-assembly method, Template method, Seed-mediated method, poly(acrylic acid), Noble metal nanoparticles, Hydroxyapatite nanowires array, Cobalt hexacyanoferrate nanocomposite
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