The Application Research On Multi-channel Series Piezoelectric Quartz Crystal Biosensor For The Detection And Identification Of Fungus And Urease-producing Bacteria

The multi-channel series piezoelectric quartz crystal sensor (MSPQC) isdesigned based on the principle of series piezoelectric quartz crystal (SPQC). It is anew type of bioelectrochemical device which has the ability of detectionmulti-samples at one time. This sensor can respond to the parameter changes (such asconductance and capacitance) of aqueous solutions sensitively. MSPQC has attractedmany analysts due to its high sensitivity, easy operation, broad sensing spectrum andlow cost. Based on the study of our group and the special response of MSPQC, somenew detection methods were presented in this dissertation. These new methods hadbroadened the application of MSPQC in clinic. The main work could be summarizedas follows:1. A molecular wire piezoelectric urease-producing bacteria (MWPUB) sensorwas constructed for detecting urease-producing bacteria in the blood. In this sensor,polypyrrole chemically deposited on polyimide film was used as probe in place ofsteel electrode in SPQC sensor. The probe was not directly touching with medium.Therefore, the sensor could overcome response noise which caused by slight corrosionof metal electrodes in liquid media. The sensor can apply to detect urease-producingbacteria, based on the following principle: polypyrrole film can react with ammoniaproduced by the growth of bacteria in medium, which caused the obvious conductancechange of the film. This change can be sensitively monitored by MWPUB. Comparingwith SPQC, the sensor reported here was rapid, sensitive, and stable in culturemedium.2. A new medium based on MSPQC was proposed for specific detection offungus. During the growing process of fungus in the proposed medium, it couldconsume ammonium ions and produce hydrogen ion. The reaction of hydrogen ionwith tartrate ion, leaded to the overall reduction in the negative charges and decreasein conductance. The conductance change can be sensitively monitored by MSPQC andgood response signal was got. However, poor respone signals of clinical commonbacteria, such as Escherichia coli, Pseudomonas aeruginosa and Micrococcus luteus,were obtained by this method. It was proved a specificity identification method forfungus. In comparison with YC medium, the new medium method for detectingfungus has some advantages as follows;(1) the medium composition is simple and do not need to adjust pH value;(2) the method has obvious respone signal and largefrequency shift;(3) the detection time is short.3. A method based on MSPQC senonr with ammonium tartrate media andtrehalose media for identification of Candida albicans. From the above, we can findthat the ammonium tartrate media was specific for fungus identification. The methodof MSPQC senonr with trehalose media was used for detecting several clinicalcommon fungi. The results demonstrated that only the response signal of Candidaalbicans was poor. So this method can be used for rapid identification of Candidaalbicans from other clinical common fungus and bacteria.