The Research Of Microbiological Detection Method And Chitosan's Characteristic With Piezoelectric Bulk Acoustic Wave Sensing Technique

Piezoelectric bulk acoustic wave (PBAW) sensor has been applied to numerous fields such as analytical chemistry, biochemistry, environmental monitoring, life science and molecular biology because of its advantages such as high sensitivity, broad sensing-spectrum, simple construction and low cost. Based on the response of one-face contacting liquid piezoelectric bulk acoustic sensor to the viscosity and density of the solution and the response of SPQC to the conductivity and permittivity, this thesis presents theoretical and applied studies for several new systems. The main content of this thesis is as follows:1. The absorption ability of chitosan to metal ion was discussed by the sensitive response of SPQC sensor to the conductivity of solution. The effect of DD value and the concentration of metal ion and chitosan on the absorbing characteristics were dissused in details. Moreover, a new method for the determination of degree of deacetylation with SPQC was proposed for the first time. This new method was more reliable due to elimination of the influence caused by the adsorptive acid and base.2. The inhibitory effect of Titania on the growth of bacteria was studies based on the relationship between the motional resistance and the viscosity -density changes of solution. By fitting â–³R_exp values towards the impedance response model, three growth kinetic parameters (A, μ_m ,λ ) for different growth situations were gained.According to the relationship between the amount of Titania and growth kinetic parameters, a new impedance response model reflecting this inhibition effect of Titania towards E.Coli was derived for the first time.3. According to the variation of viscosity and density in the solution during the growth of bacteria, the mutagenic and inhititory characteristics of sodium azide to Salmonella trphimurium strain TA100 was studies with bulk acoustic wave impedance analysis technique. The mutagenic and inhititory model was proposed theoretical. By fitting the experimentally obtained values of â–³R₁ towards the method. The mutagenic intensity coefficient (a=0.6063) and poisonous intensity coefficient (b=1.1998×10^-3) were obtained.4. A new method for studying the degradative characteristics of chitosan by enzyme preparation was proposed with bulk acoustic wave impedance analysistechnique. The chitosanolytic activity of pepsin under different degradation conditions was investigated using information provided by impedance response curve. In addition, the effect of degree of deacetylation on the enzymatic degradation was studied. The relationship between DD and the frequency shift response also established. Compared with other methods, the proposed method can not only avoid cumbersome and tedious operations, but also monitor the degradation process and provide real time information to characterize this process.