| Many living substances in the human body are closely related to human health.For example,lactic acid mainly comes from white skeletal muscle,brain,skin,kidney medulla,and red blood cells.It is produced primarily by pyruvate metabolizing glucose in the cytoplasm through glycolysis.Blood lactic acid concentration is a sensitive indicator of peripheral tissue perfusion and intracellular hypoxia,as well as an indicator of death.The dynamic change of Llactic acid is closely related to the internal environment of the body.Dynamic detection of Llactic acid value changes can help clinicians diagnose patients as early as possible and formulate treatment plans.It is of great significance in judging the degree of cell damage and tissue hypoxia,correcting it in time and improving the success rate of rescue.Therefore,many clinical laboratories use this program as an emergency test.It is very important to detect the concentration of L-lactic acid in human blood for monitoring human diseases and guiding healthy exercise.Vitamin C can fight scurvy,so it is also called ascorbic acid(AA).AA is a reducing substance that is involved in many metabolic processes in the human body.AA can also promote the utilization of iron,carbohydrates,fat and protein synthesis,maintain immune function,maintain the integrity of blood vessels,and promote the absorption of non-heme iron.In addition,vitamin C can also prevent cancer and reduce the incidence of cancer.The blood concentration of AA is also a routine test in clinical medicine.Repeated blood sampling to detect the concentration of vital substances in the human body will bring inconvenience to the subject and greatly increase the risk of infection.Fortunately,there is a certain relationship between the content of vital substances in human secretions and that in vivo can be reflected by the detection of the content of vital substances in human secretions collected in vitro.The method of analyzing secretions outside the body does not cause trauma to the human body and avoids the risk of infection.Therefore,it is of great significance to develop a rapid,sensitive and highly selective method for the detection of human secretions in vitro.Common methods of human body composition analysis in vitro secretion liquid chromatography,fluorescence colorimetric method,nuclear magnetic resonance(NMR)method and atomic absorption method and so on,these traditional methods are need to support large-scale instrument and equipment is expensive,complicated operation and equipped with professional operators,low efficiency,cannot be real-time online detection test and sample pretreatment such complicated faults.Electrochemical measurements are based on their Redox reactions on the surface of the electrode.Direct electrochemical oxidation of the target on a conventional electrode is an irreversible and slow reaction,requiring a high overpotential,which will lead to electrode contamination,instability and catalytic coexistence of other oxidizable substances resulting in interference to the test.In order to improve the selectivity of the target and reduce the overpotential of catalytic oxidation,the exposed electrode surface is usually modified with one or more electronic media,conductive or selective polymer membranes,and biological enzymes.Such electrode modification requires long and tedious preparation steps,and the introduction of a peripheral polymer film makes the electron transfer process extremely complicated.During the work of the master's degree,we developed a kind of enzyme-free photoelectric detection electrode and constructed a sensor for the concentration of vital substances in human secretions by using photoelectric potential method.The FTO electrode was modified by Dy single crystal photoelectric semiconductor,and the photoelectric detection electrode was prepared by calcination.Due to the microstructure law of Dy single crystal semiconductor,it is conducive to the separation and transmission of internal carriers under photoexcitation.After calcination,its chemical properties are stable,which helps to improve the stability and parallelism of the detection electrode.The optimized modified electrode scheme and detection parameters were obtained by selecting different temperature and excitation wavelength.Through a series of characterization,the detection electrode has been successfully prepared.In parallel and interference tests,the sensor shows good stability,parallelism and selectivity.In our work,we have guessed the detection principle of this kind of electrode,and deduced the mathematical expression of detection mechanism through the known basic theory and the verification of previous experiments,so as to lay a theoretical foundation for the application of sensors in detection.Through infrared spectrum characterization,it is found that the peak position of the electrode material moves before and after contact with the target,which proves that the molecules on the electrode surface form coordination bonds with the target,which also explains the origin of the selectivity of the sensor.In the actual sample test,the sensor system was compared with other methods to measure the content of vital substances in human secretions,which verified the practicality and feasibility of the sensor,and laid a foundation for the further development of practical products.In the development process of this kind of sensor,photoelectric potential testing technology is used.During the testing process,almost no current flows through the electrode surface,no Redox reaction occurs on the interface,no substance is consumed and no new substance is generated in the detection system,and the detection system is not damaged.More importantly,since there is no current flowing through the semiconductor material,the semiconductor itself is not corroded by photoelectricity,effectively ensuring the repeatability and stability of the electrode.For some photoelectric semiconductor materials with poor photoelectric stability,this method provides a new idea for their application in photoelectric detection. |
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