| The development of high sensitiv e and miniature senso r needs advancedtechnology. The design of high efficient sensor depends on the development ofmaterials. Nanomaterials have unique physical and chemical properties. It can improvesignal-to-noise ratio of biosensor. The adaption of nanomaterials in biology andmedicine has changed the bioanalytical detection range and expanded the widespreaduse. Nanoparticles are recently hottest research of nanomaterials. That’s because theyhave unique feature, such as quantum effect, small size effect and surface effect. Inrecent years, fluorescence silica nanoparticles are fascinating fluorescent probes andget a worldwide attention. The variety of chemical and physical modificationsimproves its biocompatibility and application. Fluorescence silica nanoparticles arehighly hydrophilic and easy to be modified. Noble metal nanomaterials have goodconductive properties and optical properties and so on. Here we mainly research ongold and silver nanomaterials.In this research, we construct several novel optical biosensors based on dye-dopedsilica nanoparticles, gold nanoparticles, gold nanoclusters and silver nanoclusters. Onthe basis of different conduction mechanism, it can realize the detection of highreactive oxygen species involved in various physiological and pathological regulation,environmental pollutants organic phosphorus and zirconium ions.(1) In chapter2, we have designed a ratiometric fluorescent sensor to detect highreactive oxygen species (hypochlorite, hydroxyl, Nitrite) based on GSH-Au NCs. First,CF dye was doped in the silica nanoparticles whose surface could be modified withstreptavidin. GSH-Au NCs was modified with the cell penetration peptide(NH2-RRRRRRRRK-biotin). Then, GSH-Au NCs and dye doped silica nanoparticlescould be joined together by the specific interaction of the biotin and streptavidin. Thefluorescence of GSH-Au NCs could be quenched by the high reactive oxygen species,but the fluorescence of the dye doped silica nanoparticles was not affected. So wecould detect high reactive oxygen species based on this ratiometric fluorescent sensorwith a high sensitivity. Compared with other methods, this method had the advantagesof simplicity and easy operation. Besides, it provide d a good platform to detect highreactive oxygen species.(2) In chapter3, a fluorescen t method for organophosphate detection based on the inhibitor of acetylcholinesterase (AChE) has been developed. The fluorescent probewas DNA-protected silver nanoclusters (DNA-Ag NCs). In this chapter, we choseinhibitor paraoxon as an example, which was an organophosphate compound. Theconcentration of acetylcholine was optimize d to improve the sensitivity. In thepresence of acetylcholinesterase and choline oxidase, the enzyme catalyzedacetylcholine to generate H2O2. H2O2could quench the fluorescence of DNA-Ag NCs.In the presence of paraoxon, acetylcholinesterase was inhibited. So no H2O2wasgenerated. This method could be used to achieve the detection of paraoxon with adetection limit of10.3ng/mL.(3) In chapter4, a simple colorimetric sensor with gold nanoparticles for sensitivedetection of zirconium ion was developed. We designed a phosphorylated peptidechain, the other was a control peptide chain. Gold nanoparticles were decorated withthe phosphorylated peptide and the control peptide. Without zirconium ions, goldnanoparticles remained red with good dispersion. In the presence of zirconium ions,zirconium ions could bind with two phosphates through a coordinate covalentinteration to form a network-structured assembly. Gold nanoparticles turned purplefrom red. The phenomenon revealed that the method allowed a specific, simple assayof zirconium ions. |
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