Preparation Of Metal-organic Framework Materials And Their Applications In Electrochemical Biosensing

With the development of science and technology,the study of electroanalytical chemistry for life is becoming one of the hottest topics in the field of life analytical chemistry in vivo.The study of brain chemistry processes involves cutting-edge research in the fields of analytical chemistry,life sciences,and so on.The development of analytical chemistry has contributed to the development of neuroscience,and it has provided more opportunities and challenges for analytical chemistry.The dynamic process of neurochemistry shows the uniqueness of neurons and brain structure in terms of response,transmission,distribution and so on.We need to dig deeper into the nature of the neurochemical processes that consists of complex neural activities in a living the organism.The evolution of the central nervous system for about 3.8 billion years has brought special complexity to its chemical studies.Neurochemistry is different from pure chemical reactions in reaction vessels or other biochemistry,and can not be understood only by traditional chemical methods.Fortunately,scientists have made great strides in the study of neuroscience,which is driven by new microscopic or nanoscience concepts and techniques,especially on qualitative and quantitative monitoring of neurochemicals in living brain real-time changes(called in vivo analysis).The real-time dynamic analysis of neurotransmitters,neuromodulators,energy metabolites,free radicals and other important physiologically active substances in the nervous system is carried out by electrochemical analysis in vivo which plays a significant role in physiological and pathological studies of brain function and various brain diseases.On the basis of a large number of previous research results,it is envisaged to use the advantages of materials to explore a new path for in vivo electrochemical analysis.The research of MOFs have become a hotspot in recent years.This thesis is based on their high porosity,large specific surface area and good controllability and designability.MOFs or their pyrolysis products are combined with multi-walled carbon nanotubes,graphene or carbon fiber.Carbon materials were employed as substrates of the composites to build a good electron transport channel between the electrode and the material,effectively overcome the shortcomings of MOFs such as poor conductivity.The microelectrodes made of carbon fiber based MOF material or its pyrolysis products composite have the characteristics of micron-sized dimensions,less damage to the organism,and have a higher time or spatial resolution in vivo voltammetry.It is very suitable for in vivo detection the electrochemical active substances in brain with physiological conditions.In this paper,a series of electrochemical biosensors were prepared by loading MOF structure or its pyrolysis products on different carbon material substrates,and some important physiological electrochemical active substances(serotonin and oxygen Etc.)were determined by the electrochemical analysis of the process of cranial nerve.The main research content and related conclusions include the following three parts:(1)We prepared the electrochemical biosensor of MOF(Al-MIL-53-NH2)composite material based on carbon material(multi-walled carbon nanotubes and graphene).The combination of MOF and the carbon material effectively improved the electron transfer path and the electrical conductivity of MOF was increased also.Using the good adsorption properties of porous MOF,dopamine was monitored through the approach of electrochemical analysis after enrichment.The results revealed that the oxidation peak current of dopamine showed a good linear relationship in a certain concentration range and the material also had some shielding effect on ascorbic acid.(2)We fabricated a carbon fiber microelectrode electrochemical biosensor based on the MOF(UiO-66-SO3H)and used the good enrichment effect of MOF to detect the basal concentration of serotonin in brain region of rat brain striatum successfully.The combination of MOF with the carbon fiber material builds a good electron transport channel and improves the electrical conductivity of MOF effectively.The experiments in vivo strongly demonstrate that the substances we tested for the physiological and electrochemistry activity of the brain are serotonin.The experimental results in vivo also show that the electrochemical biosensor of carbon fiber composite microelectrode based on MOF has the characteristics of good selectivity and high sensitivity.(3)We prepared a carbon fiber microelectrode electrochemical biosensor based on zeolite imidazolate framework(ZIF-67)pyrolysis products,which is a non-noble metal oxygen reduction catalyst with nearly four electrons in artificial cerebrospinal fluid,which greatly reduced the two electrons reduction of hydrogen peroxide production.Because of its anti-interference effect is very good,we used the biosensor for the detection of oxygen concentration in the brain successfully,and real-time monitored the oxygen level changes under a variety of physiological and pathological conditions.This is very important for both physiological and pathological research.