The Study On Whole Living Cells Electrochemical Biosensor And Fluorescence

Plant cells can be induced out some secretary substances, such as phenols, quinones, alkaloids, coumarins, terpenoids and others. The biosensors composed of whole living plant cells or tissues, using the secretary substances as the bio-recognition units, may show some more advantages.In this thesis, two kinds of petals electrochemical whole living cells biosensors, and the induction effect of polyphenol enzymes in banana with o-diphenols were studied by electrochemistry and fluorescence spectrometry. Some interesting results were obtained as the followings.The fresh carnation petals were mashed into paste, covered on solid carbon paste electrode surface by differential pulse voltammetry, which construct an electrochemi-cal whole living cells biosensor. The biosensor shows an oxidation peak at 0.316V in the differential pulse voltammetric curve. The peak current decreases with the increase of urea concentration with two linear regions of 1.3x10-16-4.57×10-8mol/L and 3.4×10-7-1.3×10"1mol/L, the detection limit of urea was obtained as 7.5×10-16 mol/L, and the recovery of 95.7%, relative standard deviation of 4.99%. The biosensor has very higher selectivity, which is not interfered by ammonium and nitrate.Instead of carnation petals, the winter jasmine petals were used for another electrochemical whole living cells biosensor by differential pulse voltammetry, which shows the similar behavior as carnation petal on. And well responds to urea in the range of 1.30×10-17-6.98×10-6mol/L, and detection limit of 1.30×10-17 mol/L.In order to investigate the mechanism of the about biosensors, fluorescent spectrometry was used to study the interaction of carnation petal and winter jasmine petal with urea molecule. The petals show some new fluorescent peak after mashed, which indicate mashing can induced some secretary substances. The new fluorescent peaks are decrease with increase of urea concentration, which indicates the interaction between the secretary substance and urea molecule. There is also a incubation region in the concentration range of 10-8 -10-6 mol/L, in this region the new fluorescent peak slightly increases, which means the petals release more secretary substance in this concentration.The indubation concentration region was also found in the study of banana in inducing with o-diphenol by fluorescent spectrometry. The polyphenol oxidation enzymes can be induced by o-diphenol in the concentration range of 10-8-10-6mol/L, which makes the new fluorescent peaks increased with time and concentration of o-diphenol.