| Nanotechnology refers to research and technology development at the atomic, molecular,and macromolecular scale,leading to the controlled manipulation and study of structures and devices with length scales from 1 to 100 nm range. Nanomaterials have unique chemical and physical properties that offer important possibilities for analytical chemistry.For example,nanoparticles represent an excellent biocompatibility with biomolecules,and display unique structural,electronic, magnetic,optical and catalytic properties which have made them a very attractive material as labels in the detection of DNA hybridization using optical methods,e.g., surface plasmon resonance or different electrochemical techniques between other applications.Biosensors have experienced rapid,extensive development.To maintain the bioactivity of biomolecules and to give the electrochemical output singal required, appropriate bioimmobilization matrices for biomolecules are critical.Recent progess in biosening technologies based on nanomaterials has resulted by the development of several novel sensor devices with their challenging applications. Morden biosensors developed with advanced microfabrication and singal processing approaches are becoming inexpensive,accurate,and reliable.This progress in miniature devices and instrumentation development will significantly impact me practice of medical care as well as future advances in bioelectrochemistry. Electrochemical,optical,and acoustic wave sensing technologies have currently emerged as some of the most promising biosensor technologies.In this paper,several new nanomaterials were prepared and characterized.We used these materials to prepare several biosensors.These biosensors were used to detect H2O2,glucose and NO2-.Chapter 1 The preparation,mechanism and applications of several new nano materials in bioelectrochemistry were reviewed.Also the new biosensors were designed and applied in some samples detection.Chapter 2 Electrochemical glucose biosensor based on tri-ferrocenyl pyridinium salt as a novel redox mediatorA novel tri-ferrocenyl pyridininium salt,with pyridinium cation as electron acceptor and ferrocenyl as electron donor(2,4,6-tris(ferrocenylvinyl)-N-ethylpyridinium iodide,TFc),was studied by SEM,FT-IR,UV-Vis spectrometry and electrochemical method.With the objective of insight into its potential application in sensors,the TFc was modified,on the surface of glassy carbon(GC)electrode for H2O2 measurement. We find that the TFc yields excellent performances as electron transfer mediator for electrocatalysis oxidation H2O2.Furthermore,glucose oxidase was immobilized over the TFc modified electrode in order to develop a novel glucose biosensor. Performance and characteristics of the biosensor were investigated with respect to response time,selectivity and dependence on applied potential,pH as well as reproducibility and operating stability.Under the optimized conditions,the glucose biosensor shows a linear response over the range from 8.0×10-5to 1.0×10-2mol/L, with detection limit(S/N=3)of 1.0×10-5mol/L.Chapter 3 Encapsulation of Horseradish Peroxidase into Hydrogel and its BioelectrochemistryHydrogels are a promising class of biomaterials for protein immobilization.In this paper,a biohybrid hydrogel is fabricated by integrating horseradish peroxidase(HRP) with polyhydroxyl cellulose(PHC),which is prepared by mixing of poly(vinyl alcohol)(PVA)and carboxymethyl hydroxyethyl cellulose(CMHEC).PHC provides a biocompatible microenvironment for HRP to maintain its natural configuration. Peroxidase activity of HRP is investigated by enzymatic polymerization of aniline in the presence of H2O2.The results indicate that the enzymatic activity of HRP-loaded biohydrogel is well retained relative to free HRP.Based on the direct electrochemistry and electrocatalytic ability of HRP,a third-generation H2O2 biosensor is developed. Under the optimized conditions,the H2O2 biosensor shows a linear response over the range from 1.0×10-6to 1.0×10-3mol·L-1,with detection limit(S/N=3)of 5.0×10-7 mol·L-1.Chapter 4 Nanostructured Electrochemical biosensors built by Layer-by-Layer Assembly of Multiwall Carbon Nanotubes and Zn-salen Carbon nanotubes have a high electrochemically accessible area of porous tubes,good electronic conductance and strong mechanical property.These properties essentially suggest that CNTs are attractive materials for the construction of nanoscaled biosensors.Ligand frameworks such as the schiff base containing salen ligand,which can be sterically and electronically modified with ease,are very attractive.The chemistry of SALEN-type ligands with transition metals and their application in homogeneous catalysis has been intensively explored.In this paper,we prepare three kinds of electrodes modified by MWCNTs,Zn-salen and MWCNTs/Zn-salen separately via layer-by-layer assembly technology.We find that {MCNTs/Zn-salen}3 multilayer films have excellent electrocatalytic activity for NO and H2O2. {MCNYs/Zn-salen}3 modified electrode shows that the response to NO is linear within the concentration range from 6.0×10-7to 1.0×10-2mol·L-1.The detection limit was 1.0×10-7mol·L-1(S/N=3).
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