Research On The Detection System Of Neurotransmitter Concentration Based On Electrochemical Sensing Technology

The neural activity of the brain is a process combining electrical and chemical activities.At present,it is a very important research flied to study the brain from the perspective of chemical signals(especially neurotransmitters).The in-situ electrochemical sensing method has attractted more and more attention because it is small,convenient,fast,real-time,online and easy to operate.However,there are two key problems in the detection of neurotransmitters by electrochemical sensing method.On the one hand,the size,lower detection limit,and anti-interference ability of electrochemical sensor devices(microelectrodes)are still far from the requirements of actual detection;on the other hand,the lack of portable and reliable electrochemical detection instrument further restricts the practical application and promotion of the corresponding electrochemical sensor devices.Therefore,aiming at the above two key problems,this theis designs and implements a portable neurotransmitter concentration detection system based on electrochemical sensing technology.The system takes dopamine and glutamate,which are two of the representative neurotransmitters,as the main research objects.Novel dopamine and glutamate electrochemical sensors with high sensitivity and high selectivity that can work in the complex environment of organisms is designed.Moreover,for the requirements of body detection such as fast,high sensitivity,small size and anti-interference,a portable high-precision neurotransmitter detection instrument is designed.Finally,the sensors and the instrument are integrated into the electrochemical neurotransmitter detection system,and applied to the concentration monitoring of specific neurotransmitters in actual samples.The main contents and innovations of the thesis are as follows:1.A novel platinum wire electrochemical microelectrode based on reduced graphene oxide and gold nanoparticle composite nanomaterials is designed and realized.A uniformly distributed composite film of reduced graphene oxide and gold nanoparticles is formed on the surface of the platinum wire by electrodeposition,and the platinum wire microelectrode is constructed.The high specific surface area,high electronic conductivity and good biocompatibility of the composite membrane can resist dopamine fouling and alleviate the problem of surface aggregation and adsorption when detecting dopamine with platinum wire electrodes.The microelectrode shows high sensitivity and low detection limit(16.57 nM)to dopamine.At the same time,the electrode can effectively resist the interference of DA precursors and other monoamine neurotransmitters in a complex environment.Moreover,the electrode shows high reproducibility(relative standard deviation of 3.98%)and stability(3.43% loss after100 repeated scans).In vivo experiments verify that the electrode has the function of detecting changes of dopamine concentration in the striatum of anesthetized rats.The electrode shows great comprehensive performance,such as sensitivity and selectivity,and provides a new method for real-time dynamic monitoring of dopamine.The electrode has the potential to be used to study specific structures or multi-site dopamine detection in organisms.2.A novel microelectrode based on glutamate oxidase is designed and realized by the modification of reduced graphene oxide,Prussian blue,gold nanoparticles and chitosan material.The surface of high catalytic activity makes the electrode show superior electrocatalytic performance to glutamic acid,exhibit superior electrocatalytic performance for glutamate with a detection limit of 41.33 nM,and a linear concentration-current dependence in the physiological concentration range of the extracellular space.The electrode loses only 3.62% of signal intensity in 100 tests,and maintains 92.14% of the initial signal intensity within 14 days.In addition,in vivo experiments verifiy the anti-interference of the electrode in a complex physiological environment,and it is observed that the electrode can detect changes in the concentration of glutamate in the rat striatum.The electrode shows great comprehensive performance in terms of size,lower detection limit,anti-interference,and service life,provides a new method for real-time dynamic monitoring of glutamate,and shows the potential for monitoring multi-site and multi-channel transmitters in samples or organisms for a long time.3.A portable,high-precision,current-type neurotransmitter concentration detection instrument for neurotransmitter detection is designed and realized.By integrating the technology of microsignal detection and anti-jamming of power supply,the detection instrument realizes microcurrent signal detection under high disturbance,showing the advantages of small size,high precision(error<3%),high signal-to-noise ratio(77.52 d B),low detection limit(5.35 n A),wide linear range and wireless transmission.The portable detection instrument can be used to detect the concentration of dopamine and glutamate in the standard mixed solution system synchronously,and detect the change signal and dynamic metabolic signal of the concentration of dopamine and glutamate in the rat striatum,showing the potential of the system for long-term dynamic detection and research of multiple neurotransmitter levels in the biological brain.In summary,a portable neurotransmitter concentration detection system based on electrochemical sensing technology is designed and realized in this thesis.The system includes the dopamine and glutamate sensor with high sensitivity and high selectivity,as well as the high-precision,portable detection instrument.In vivo experiments show that the high-performance neurotransmitter detection system can be used to detect the dynamic changes of dopamine and glutamate concentration in a complex in-vivo environment,which is expected to play a role in the real-time monitoring of in-vivo neurotransmitter concentration and related research in the future.