The Piezoelectric Sensor Impedance Technology Research And Application In The Biological Field

In the fifties of the 20th century, Sauerbey had reported that the oscillation frequency of a piezoelectric quartz crystal (PQC) is linearly related to the mass change on the PQC electrode surface. Later, Martin investigated the relationship between PQC responses (resonance frequency, motional resistance and motional inductance) and the density-viscosity variation of solution. Because of its low cost, high sensitivity and simple construction, PQC technology has been applied in various fields, including analytical chemistry, clinic immunology, pharmaceutical science, surface science, environmental detection and etc.The biochemical analysis has become more and more important with the development of the biochemistry. However, most traditional biochemical analytical methods, for example HPLC, UV spectrophotometry, electrophoresis, still have some shortcomings, for instance, the requirement of expensive apparatus and reagents, cumbersome procedure and hardly to provide multidimensional in situ informations. PQC technology can be applied in the biochemistry widely by providing multidimensional in situ informations. In the present dissertation, on the basis of the relationship between PQC responses and solution's viscosity-density changes, the PQC method has been developed to investigate a number of biochemical systems.1. Herring DNA denaturation process has been investigated firstly using piezoelectric quartz crystal impedance method. The DNA melting temperature was evaluated. The effects of temperature, heating time, ionic strength were studied, and the results were in good agreement with other reports.2. Calf thymus DNA oxidative damage has been studied with PQC method firstly. The oxidative ability of different HiOa systems, including the systems containing Cu2+, Zn2+ and no-transition metal elements, was compared. The effect of HaC^ or Cu2+ concentration on the oxidative damage was also studied.3. Based on the a-amylase-catalyzed hydrolysis of starch, PQCI method has been developed to monitor the growth process of Bacillus subtilis and the variation of the a-amylase activity during the growth. Bacteria growth equations were derived based on the kinetics of the enzyme-catalyzed hydrolysis of starch. Kinetic parameters of the bacteria growth were obtained, which were in good agreement with those obtained from the pour plate count method. The influence of the initial bacteria concentration was also investigated.