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The Construction of Novel Biosensors and Their Applications in Environmental and Biological Detectio

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Tutor: LuoShengLian
School: Hunan University
Course: Chemical Engineering and Technology
Keywords: Biosensors,Pb ()ion,Trinitrotoluene,Benzene()pyrene,Thiol aminoacids,Detection
CLC: X83
Type: PhD thesis
Year:  2012
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Biosensor is an analytic device composed of biological sensor and signalprocessing components for biological, chemical analysis detection. On binding ofanalyte to biological sensor, the consequent signal was received, processed, converedand output by signal processing components, and as a result, the qualitative,quantitative analysis to the analyte are achieved. In view of the incomparableadvantage compared with conventional analysis methods, biosensor has alreadyevolved as an important technology for analysis and detection, and it has been widelyused in environmental monitoring, medicine, biology research, food testing,fermentation industrial production etc.Recently, the detection for environmental pollutant has become the key indicatorfor environmental evaluation and protection. The detection for biological moleculehas also become the effective reference for biology research. The design of thebiosensor to detect environmental pollutant and biological molecule is of greatscientific significance and promising practical application. Here,5novel biosensorsfor the determination of heavy metal lead ions, benzene()pyrene, TNT or thiol aminoacids are described.1. A type of Pb () ion biosensor has been generated based on glutathioneprotection of the silver nanoparticles(AgNPs). Glutathione can be conjugated toAgNPs via AgCS bond, helping AgNPs to resist against aggregation induced by salt.However, the interaction between glutathione and AgNPs can be compromised by Pb() ion binding to glutathione. As a result, Pb () mediated-aggregation of AgNPscan be reflected by the UV-Visible spectrum change, and the qualitative andquantitative detection for Pb () ion is accomplished, with the detection range0.5-4M and a detection limit of0.5M. Pb () ion in water sample has also beendetermined by this biosensor. The principle that glutathione is capable of enhancingthe stability of the AgNPs is first reported in this thesis. Furthermore, thevisualization and quantitative detection for Pb () ion biosensor was constructedbased on this principle. This study implies that a ligand which combines heavy metalions and silver nanomaterials can be used to construct biosensors to achieve thespecific detection.2. A type of trinitrotoluene (TNT) biosensor using fluorescence silver nanocluster has been proposed. In the presence of interaction between Ag+and cytosine,fluorescence silver nanocluster can be generated under the reduction effect of sodiumborohydride. TNT is a strong electronic receptor and an effective fluorescent quencher.The interaction between TNT and silver nanocluster leads to fluorescence quenching,thus the detection of TNT is realized, with detection linear range of0.5-6g/mL anddetection limit of0.5g/mL. TNT in the soil sample can be detected using thebiosensor, indicating its practical application. Moreover, the successful application offluorescence silver nanocluster in TNT biosensor provides referential experience inthe construction of biosensor using fluorescence nanomaterial.3. A type of benzene()pyrene biosensor based on dot blot has been proposed.Competitive immune response occurs between benzene()pyrene, benzene()pyreneantibody and benzene()pyrene antigen absorbed on nitrocellulose membrane.Detection signal can be collected by film. The biosensor can analyzed as low as5ng/mL of benzene()pyrene through a visualization detection. A semi-quantitativebenzene()pyrene detection can be achieved by using a professional analysis software.The water sample containing benzene()pyrene can be analyzed, imply the potentialpractical application. The principle of dot blot was firstly employed to designbiosensors, and provided qualitative and semi-quantitative detection without any useof instrument. The simplicity and high specificity of benzene()pyrene biosensorsheds new light on the development of environmental pollutant biosensor.4. A type of biological thiols biosensor for using ssDNA/sliver nanoparticlessystem has been proposed. The adsorbing ssDNA provides AgNPs high density chargeto prevent nanoparticles from aggregation induced by salt. However, homocysteine(cysteine or glutathione) can conjugate to AgNPs via Ag-S bond more powerfully thanssDNA, which restrain ssDNA from binding to AgNPs surface. In the presense ofhomocysteine, the salt induced AgNPs aggregation and the corresponding UV-Visiblespectrum change. Homocysteine,cysteine and glutathione can be determined in therange of10-500nM50-500nM100-500nM, respectively, with the detection limitof10nM50nM100nM, respectively. The method was successfully applied todetermine stimulant serum samples or urine sample containing homocysteine.Through the AgNPs color change, biological thiols biosensor provide simple, rapid,efficient, specific and visual detection for thiol amino acids, which may be instructiveto the biological molecule biosensor development.5. A type of cysteine biosensor based on ssDNA-stabilized gold nanoparticles(AuNPs) has been proposed. The adsorbing ssDNA provides AuNPs high density charge to prevent nanoparticles from aggregation induced by salt. In the presence ofcysteine, ssDNA is moved away by cysteine, resulting in the AuNPs aggregation viathe introduction of salt. Therefore, cysteine can be detected based on UV-Visiblespectrum change. A favorable linear correlation in the range of0.1-5M is obtainedwith a detection limit of0.1M. The biosensor is successfully applied to determinestimulant serum samples containing cysteine, suggesting the promising practicalapplication. The cysteine biosensor is simple, efficient, highly sensitive, which willpromote the biological molecule biosensor designed with nanomaterial.
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