Study And Application Of Biosensors Based On Hemoglobin/Chitosan Film

The biosensors are the advanced sensing devices from mutual connection of multi-subject. To the needs of people in clinical diagnosis, environmental detection and biochemical analysis, more and more extensive researches have performed for the biosensors.Cholesteorl is a most important steroid in human body, and it be called total cholesterol as a whole, which is consists of cholesterol ester and free cholesterol. Current medical research indicates that there is a strong positive correlation between high serum cholesterol level and arteriosclerosis, hypertension and myocardial infarction. Uric acid (UA), a last catabolism outcome of purine in biological systems, is a very important biological molecule present in body fluids. Its level serves as a marker for the detection of disorders associated with purine metabolism, and can well reflect the status of immunity. Therefore, developing new biosensors is very important for the determination of cholesterol and uric acid in clinical diagnosis. On the basis of the preparation and application of cholesterol and UA biosensors, the work of master paper is summarized as follows:1. A cholesterol biosensor based on direct electron transfer (DET) of hemoglobin encapsulated chitosan-modified glassy carbon electrode has developed for highly sensitive and selective analysis in serum samples. The electrode modified by films containing hemoglobin (Hb) and cholesterol oxidase was prepared by encapsulation of enzyme in chitosan matrix. The linear response of cholesterol concentrations was from 1.00×10^-5 to 6.00×10^-4 mol L^-1 with the correlation of 0.9969, and the detection limit of cholesterol was estimated to be 9.5μmol L^-1 at a signal/noise ratio of 3. The cholesterol biosensor can efficiently exclude the interference of commonly coexisted ascorbic acid, uric acid, dopamine, and epinephrine, etc. The relative standard deviation (RSD) was under 4.0% (n=5) for the determination of real samples. The biosensor is satisfactory to the determination of human serum samples.2. A highly selective cholesterol biosensor based on direct electron transfer of Hb- encapsulated chitosan-modified glassy carbon electrode was developed for determination of total cholesterol in human serum samples. The enzyme electrode was prepared by immobilization of Hb, cholesterol oxidase and cholesterol esterase in chitosan matrix. The linear response of cholesterol concentrations was from 10.0 110 mg dL^-1 with the correlation of 0.9965, and the detection limit of cholesterol was estimated to be 5.0 mg dL^-1 at a signal/noise ratio of 3. The cholesterol biosensor can efficiently exclude the interference of commonly coexisted ascorbic acid and uric acid. The biosensor is satisfactory to the determination of human serum samples. RSD was under 6.1% (n=7) for the determination of real samples.3. A uric acid biosensor based on direct electron transfer of Hb-encapsulated chitosan-modified glassy carbon electrode was developed for highly sensitive and selective analysis in urine samples. The electrode modified by films containing Hb and uricase, the electrode was prepared by encapsulation of enzymes in chitosan matrix. The linear response of uric acid concentrations ranged from 2.00 to 36.0μmol L^-1 with a correlation of 0.9992, and the detection limit of UA was estimated to be 0.85μmol L^-1 at a signal/noise ratio of 3. The uric acid biosensor can efficiently exclude the interference of commonly coexisted ascorbic acid, dopamine, epinephrine, etc. RSD was under 2.56% (n=5) for the determination of real samples.