| In this paper, two norepinephrine detection sensors that can be applied to the human body are preparated, they are L-serine modified boron-doped diamond electrodes and Mg O nano-structure modified BDD electrodes. Detection results and comparative analysis of the two sensors are introduced.Norepinephrine(NE) is a kind of important neurotransmitter of organism that belongs to catecholamines. The study shows that many human diseases are associated with the imbalance of concentration of neurotransmitters in the body. Therefore, test the concentration of norepinephrine in the body is of great significance in the medical and biological research. The main research focus on using chemically modified glassy carbon electrode to detect NE. Recent research show that diamond electrode has some advantages such as corrosion resistance、wide potential window and low background current.The detection sensitivity of the electrode can be greatly improved as combined with features of modifications.BDD film electrode and Mg O nano-structure are made in hydrogen-argon carbon source by direct current(DC) plasma jet chemical vapor deposition(CVD) method and characterization results show that the grain morphology of the BDD film is very clear and distributed evenly, the size of grain is in micron scale range, it has dense structure and grows well. The resistivity of the BDD electrode is 0.022 ?·cm and carrier concentration is 6.421×1019, which located the carrier concentration range of metal, so it has good conductivity. It has approximately 3.2V potential window, background current which close to zero and good stability. Mg O nano-structure consists of Mg O nanoparticles, Mg O nanobelts and many connections. The reaction of polycrystalline layer is sufficient, diameter of the particles is about 60 nm, the width of nanobelts is about 10 nm and the length is from several hundred nanometers to several microns. The size is uniform and has high density.L-serine and Mg O nano-structure modified BDD electrodes are made in electrochemical polymerization and NE solution with same concentration are detected. Results show that peak current reaches 0.0075 m A when detecting NE with L-serine modified BDD electrode, oxidation peak current is linear with the logarithm of concentration in basic within the range of 1.0×10-4 ~1.0×10-8 mol/L, the detection limit of L-serine modified BDD electrode for NE is 1.0×10-8 mol/L, the modified electrode has high detection accuracy; when detecting NE with Mg O nano-structure modified BDD electrode, oxidation peak potential is about 0.4V, peak current reaches 0.009 m A, detection sensitivity is much higher than the unmodified electrode. Oxidation peak current is linear with the logarithm of concentration within the range of 1.0×10-4 ~0.9×10-8 mol/L. And we can conclude that the detection limit of Mg O nano-structure modified BDD electrode for NE is 0.9×10-8 mol/L from tests, has higher detection accuracy.Affecting factors of detecting NE with two chemical modified electrodes are analyzed, include the value of PH, the scanning rate, interference testing and stability testing. Two kinds of electrodes both have its advantages. Preparation of L-serine modified BDD electrode is much simple than Mg O nano-structure modified BDD electrode and the peak potential is much lower which shows that the L-serine modified BDD electrode can detect NE in low potential, but Mg O nano-structure modified BDD electrode can play a stronger role in detecting NE with lower concentration, it has stronger stability and immunity, but the modification process is relatively complicated. In the application, modified electrodes can be selected according to the actual conditions.The results show that diamond electrodes have wide potential window, the background current which close to zero and good stability. These properties provide good conditions in their application of bioelectrochemical. Combines the advantages of the chemical modification, the detection sensitivity of such a diamond electrode can be greatly enhanced. |
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