| Since the development of the first glucose biosensor in 1962 by Clark and Lyons, biosensors have developed to be a frontier and newly-interdisciplinary including biology, chemistry, medicine and electronics. Due to its simplicity, high sensitivity and potential ability for real-time and on-site analysis, biosensor has been widely applied in various fields including clinical diagnosis, environment monitoring, food control and industrial process, and so on.The development of nano-techonology provides a new opportunity to the development of biosensors. Nanobiosening technology is revealing its superiority not only have good effect on it, but also on biosensor. This dissertation focuses on 1) fabricating novel biosensors based on new nanomaterials and nanostructures, and integrated them with microdialysis, flow injection analysis, etc. 2) establishing the bases for application of them to detect glucose, hypoxanthine and organophosphate pesticides. We are adhering to an organic combination of nanotechnology, biosensing technology and clinical researches. The details are given as follows:Chapter One: PrefaceAt first, a critical review with regard to biosensors and the development of biosensors is given. Then the application of nanotechnology into biosensors attach with micro dialysis and flow inject analysis is highlighted. Nanotechnology is revolutionizing the development of biosensors. Sensitivity and other attributes of biosensors can be improved by using nanomaterials in their construction. Finally, the work and significance of this thesis was briefly introduced.Chapter Two: Biosensor based on Iron Porphyrin nanoparticles for amperometric detection of glucose Metalloporphyrin is a prototype of metal hexacyanoferrates with remarkable catalytic-, electro-, photo-, and biochemical properties. They are potentially used as electron-transfer mediators for the development of amperometric biosensors owing to their excellent electrochemical and electro-catalytic properties. In this paper, a type of iron (III)-porphyrin (FeTPP) nanoparticles was prepared and modified on the surface of glassy carbon electrode (GCE) as a novel redox electron mediator. Therefore a novel electrochemical sensor for glucose was developed. The effects of experimental conditions on biosensors' response have been investigated. The linear range for the determination of glucose is 1.0×10-5 ～ 2.1×10-3 mol·L-1 with a detection limit of 5.0×10-6 mol·L-1 (S/N = 3). A possible mechanism for the operation of the glucose biosensor was also proposed. This biosensor exhibited high sensitivity, stability and anti-interference. Finally the level of glucose in S.D. rat brain was also detected in order to demonstrate the practical usage of this biosensor. The result was in satisfactory agreement with the references.Chapter Three: Amperometric biosensor for hypoxanthine based on immobilized xanthine oxidase on Iron Porphyrin nanoparticles modified glassy carbon electrodeThe determination of hypoxanthine (Hx) has considerable importance for the detection of human's brain injure. The continuing development and application of analytical methods are proceeding at a rapid pace, and many methods have been proposed for the determination of trace amounts of Hx. In this paper, a type of iron (III)-porphyrin (FeTPP) nanoparticles was prepared and modified on the surface of glassy carbon electrode as a novel redox electron mediator. Therefore a novel electrochemical sensor for hypoxanthine was developed. The features of the enzymic biosensor were discussed in detail. Iron (III)-porphyrin (FeTPP) nanoparticles was dripped on the biosensor to exclude electro oxidizable interferants, such as ascorbic acid (AA) and uric acid (UA). The resulting sensor is stable, highly sensitive and shows a fast response time. The response conditions were optimized. Coupled with micro dialysis, the Hx in rat brains were measured with satisfactory results.Chapter Four: Mn Porphyrin nanoparticles modified Acetylcholinesterase biosensor coupled with flow injection analyzer for detecion of PesticidePesticides represent a major hazard to public health throughout the world, it is necessary to monitor them in the environment and foods. Biosensor technology is well suited for field of monitoring OP compounds. In this paper Mn Porphyrin (MnTPP) nanoparticles (NPs) were prepared using mixing solvent techniques. MnTPP NPs has been used for the immobilization and stabilization of the acetylcholinesterase (AChE). The use of MnTPP NPs is shown to provide significant enzyme stabilization, as well as the means for lowering the detection limit of the biosensor. The biosensor was optimized and the properties were described. Coupled with flow injection analyzer (FIA), the biosensor was used for the detection of organophosphate pesticides (OPs) trichlorfon. The concentration of this enzymatic inhibitor had the linear range from 1.0×10-9 mol·L-1 to 1.0×10-3 mol·L-1and the detection limit was found to be 5.0×10-10 mol·L-1.'So, a novel amperometric OPs biosensor based on MnTPP NPs has been firstly developed and showed excellent detection limit, the good precision and the relative stability.Chapter Five: Development of Quantum Dots modified acetylcholinesterase biosensor for the detection of trichlorfonQuantum dots (QDs) are semiconductors particles that have all three dimensions confined to the nanometer length scales which close to their Bohr exciton radius. And QDs exhibit unique optical and electronic properties. Recently, people are interested in QDs for potential use in many fields, especially in biosensing and bioconjugates. In this paper, we conceive that QDs as the enzyme biosensor platform could be advantageous for the sensitive detection of OP compounds. PVP-CdS QDs has been used for the immobilization and stabilization of the acetylcholinesterase (AChE). The electrocatalytic activity of PVP-CdS QDs leads to a greatly improved electrochemical detection and higher sensitivity and stability. The biosensor was used for the detection of organophosphate pesticides (OPs), such as trichlorfon. The sensor performance, including pH, was optimized with respect to operating conditions. The biosensor had excellent operational lifetime stability with very low decrease in the activity of enzymes for more than 10 repeated measurements over a 2-week period. |
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