| With the fast development of life science,accurate analysis of biological samples is becoming one of the most front fields.To obtain comprehensive and accurate data about complex samples,the analytical methods must be accurate,sensitive and selective to realize the in vivo and on-line analysis.It is apparent that a single analytical technique is no longer qualified for the analysis of complex biological samples.The hyphenated technique is one of the trends in the development of analytical chemistry in the future.Research demonstrates that the abnormal content change of biological molecules are closely related many disease.However,many conventional analytical methods can't match the requirements because of the complex component and low content of biological samples.How to realize the accurate determination of biological samples, which plays an important role to the pathology and pharmacology research of disease, is an urgent problem.In this dissertation,we put our concentration on the research of novel electrochemical detectors(ECD) and established some hyphenated technique of sample analysis in life science.Some kinds of chemically modified electrodes(CME) which could enhance the sensitivity and selectivity in samples analysis were developed and used as ECD.These novel analytical methods were successfully applied to the research on the diagnosis and treatment of some diseases such as diabetes,hypertension and Parkinson's disease.The dissertation includes three chapters:1.Study on the monoamine neurotransmitters change in rat striatum caused by GABA using liquid chromatography coupled with Pt/poly-3-methylthiophene modified electrodeGABA is the major inhibitory neurotransmitter in the nervous system.In order to study its effect on monoamine neurotransmitters and their metabolites,a novel Pt/poly-3-methylthiophene chemically modified electrode(Pt/P3MT/CME) was developed in this article.The Pt/P3MT/CME was characterized by atomic force microscope(AFM).The electrochemical behaviors of monoamine neurotransmitters and their metabolites at the CME were investigated by cyclic voltammetry(CV) and differential pulse voltammetry(DPV).The results showed that the CME had a prominent electrocatalytic effect,high sensitivity and excellent stability for the determination of monoamine neurotransmitters.When being applied as the liquid chromatography(LC)detector,the CME exhibited a good linear relationship between the current responses and the analyte concentrations.The linear ranges were over three orders of magnitude and the detection limit was 2.0×10-10 mol/L for norepinephrine(NE),1.0×10-10 mol/L for dopamine(DA),3.0×10-10 mol/L for 3,4-dihydroxyphenylacetic acid(DOPAC),4.0×10-10 mol/L for 5-hydroxytryptamine (5-HT) and 7.0×10-10 mol/L for 5-hydroxyindoleacetic acid(5-HIAA).The application of this method coupled with microdialysis sampling for in vivo determination of monoamine neurotransmitters in rat striatum was satisfactory.The results demonstrated that GABA could substantially increase striatal concentration of monoamine neurotransmitters.2.Biosensors for simultaneous determination of glucose and cholesterol in human serum based on immobilization of bioenzyme in dual modified electrodeAn effective electrochemical method for simultaneous detection of glucose and cholesterol in human serum was demonstrated in this study.By entrapping horseradish peroxidase(HRP)in chitosan(CH) doped with gold nanaoparticles(GNp) on glassy carbon electrode surface which was electrodepositied with thionine(TH) before,a simple and effective method for hydrogen peroxide(H2O2) detection was developed.The glucose biosensor and cholesterol biosensor based on the electrochemical detection of enzymatically generated H2O2 were constructed by the effective immobilization of glucose oxidase(GOx) and cholesterol oxidase(ChOx). Both TH/GNp/CH/HRP/GOx and GNp/CH/HRP/ChOx modified electrodes showed prominent electrocatalytic effect towards glucose and cholesterol respectively. Moreover,when being applied as the dual electrochemical detector for flow injection analysis,the dual electrodes suffer from little cross-link and exhibit an acceptable accuracy,a good reproducibility and stability.The application of this method for simultaneous determination of glucose and cholesterol in human serum samples was satisfactory.3.A new microdialysis-electrochemical device for in vivo simultaneous determination of acetylcholine and choline in rat brain treated with N-methyl-(R)-salsolinolAcetylcholine(ACh) and choline(Ch) play a critical role in cholinergic neurotransmission and the abnormalities in their concentrations are related to several neural diseases.Therefore,the in vivo determination of ACh and Ch is important to the research on neurodegenerative disorders.In this work,electrochemical biosensors based on poly(m-(1,3)-phenylenediamine)(pmPD) and polytyramine(PTy) modified enzyme electrodes were fabricated.The electropolymerized pmPD polymer was used to exclude interfering substance and the PTy layer facilitated the immobilization of acetylcholinesterase(ACHE) and choline oxidase(ChO).Then,ACh/Ch sensor and Ch sensor were Coupled with microdialysis to produce a novel device,which provides a sensitive and selective method for simultaneous determination of ACh and Ch.This method has a detection limit of 63.0±3.4 nM for ACh and 25.0±1.2 nM for Ch.The integrated device was successfully applied to assessing the impact of endogenous neurotoxin N-methyl-(R)-salsolinol [1(R),2-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline,(R)-NMSal]on ACh and Ch concentration,which is of great benefit to understand the pathogenesis of Parkinson's disease.
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