Study On The Determination Of Glucose And Choline By Novel Electrochemical Analysis

The electrochemical analysis method had many advantages such as convenience,economy,and high spatial and temporal resolution,which hold great promise for development of in vivo sensor.Past decades have witnessed the advance of electrochemical in vivo sensing strategies,and it is widely used to monitor a variety of brain neurochemical.At present,electrochemical methods for electrochemical in vivo analysis are mainly divided into two categories:one is the current method,such as amperometry,voltammetry,etc.;Another is the potentiometric method,such as galvanic redox potentiometry（GRP）and ion-selective electrodes.The brain contains a variety of neurochemicals,among these neurochemicals,glucose and choline（Cho）as important nutrients in the brain,affect many physiological processes of the human body.Therefore,accurate and real-time analysis of glucose and Cho content in vivo is of great significance to explain the molecular mechanism of brain function.Although electrochemical in vivo analysis had enabled the detection of a variety of neurochemicals,electrochemical in vivo analysis still remains two challenges:（1）how to construct new technologies which have biocompatibility and antifouling ability that can monitor neuro-substances.Due to characteristics such as antifouling and neuronal compatibility of GRP,it can perform quantitative analysis of neurochemicals represented by glucose under open-circuit potentiometry.（2）How to achieve accurate analysis of non-electrochemically active substances.Although there are some complicated antifouling modification strategies of the current method for in-situ analysis,its advantage of rapid analysis of target species endows it with a unique advantage in the application of in vivo micro-dialysis sampling-online electrochemical detection,which is conducive to the accurate analysis of substances with stable electrochemical properties.As two major nutrients,glucose and Cho are the main research objects of this work.GRP method and in vivo microdialysis sampling-online electrochemicaldetection technology areselected as the means of invivoglucose and Cho analysis,tobuild an excellent performance invivo analysis sensor.Specific research contents areas follows:Chapter 1:This chapter briefly summarized the frontiers of brain neurochemistry,and introduces the research progress of traditional electrochemical methods and the application of GRP in the field of in situ analytical chemistry.In addition,this chapter also introduces the various energy substrates in the human body andtheirroles in thenervous system.Chapter 2:The construction of enzymatic GRP sensor and test of the basic performance of the as-constructed sensor.In this work,the enzymatic sensor incorporating GRP was used for the quantitative analysis of glucose for the first time,and carbon black（CB）was added as a conductive enhancer to shorten the response time of the enzymatic sensing layer to glucose detection.By comparing the D_CTof thesensor with CB(1.43×10^-10cm²·s^-1)and without CB(4.35×10^-11cm²·s^-1),it is further demonstrated that CB can shorten the response time of the sensor.The constructed enzymatic sensor showed good linearity（R²=0.996）in the range of 0.10 m M to 2.25 m M.In addition,the sensor developed in this work has good reversibility,stability,and anti-oxygen interference ability.Therefore,the enzymatic sensor provides an experimental basis for further preparationof miniaturized sensors forinvivo analysis.Chapter 3:Construction of enzymatic GRP microsensor and monitoring of brain glucose dynamic.In order to meet conditions for monitoring glucose in rat brain,the enzymatic GRP sensor was miniaturized.The results from thework showthat the as-prepared microsensor has high sensitivity,good stability,and a wide linear range（0.10 m M-2.65m M）,which can meet the range of dynamicchanges of glucose in thebrain.More importantly,after the microsensorwas implanted into the brain of living rats,the sensor still showed excellent in vivo sensing performance,which could be used for real-time and quantitative study of brain glucose dynamics.In this study,a novel strategy of GRP and enzymatic microsensor is proposed,which provides a new method for real-timemonitoring of brain glucosemetabolism.Chapter 4:Research of choline detection performance of Pt/GDY.As one of the essential nutrients,choline plays a key role in the nervous system.It is of great significance to explore the choline dynamic in the nervous system.Due to the correlation between choline and acetylcholine in the nervous system,researchers often use choline oxidase to oxidize choline to acetylcholine,and achieve simultaneous detection of choline and acetylcholine.However,this method cannot distinguish the two substances,thus affecting the accuracy of the choline analysis.In addition,there are relatively few reports on the accurate detection methods of choline.The Pt/GDY sensor constructed in this work has good stability,and the sensor still has a stable response to choline after6 days.The selectivity test results showed that the Pt/GDY sensor exhibited good selectivity in response to choline,which was not affected by acetylcholine.In addition,the linear range of the as-constructed Pt/GDY sensor is 100μM～800μM,and the detection limit is 100μM.The Pt/GDY sensor proposed in this work provides a powerful detection technology for the accurate analysis of cholinein vivo by microdialysis sampling-on-lineelectrochemical detection platform.