Preparation And Applications Of Functionalized Gold Nanoparticles

In recent years, gold nanoparticles (AuNPs) have been widely used in a variety of biochemistry analysis and biomedical detection techniques, and it gradually becomes into a high selectivity and high sensitivity bioanalyitcal detection methods. In this thesis work, we use hydrophilic compounds (such as peptides) as a stabilizer, to modify the gold nanoparticles by self-assembly technique (Au-S convalent bond). Then coumarin 343 was functionalized on gold nanoparticles. These functionalized gold nanoparticles could be used to detect the caspase 3. The sensing of glutathione was also studied on the base of the quenching properties of gold nanoparticles.In chapter one, the nature of the gold nanoparticles, the principle of luminescent quenching, the synthesis methods of gold nanoparticles, and the application in the chemical and biological sensing were introduced. Then the luminescence mechanism of ruthenium (Ⅱ) complexes and the applications in the biosensing field were introduced. In addition, the preparation of novel nano-materials functionalized by ruthenium (Ⅱ) complexes and its application in the biosensing field were introduced.In chapter two, a kind of coumarin-functionalized gold nanoparticle by the connection of polypeptide chains containing specific sequences (DEVD) was designed and synthesized. The fluorescence of coumarin was quenched due to the luminescent quenching properties of gold nanoparticles. The fluorescence would be restored after the particular polypeptide sequence (DEVD) was cut off by caspase 3. Based on this mechanism, the caspase enzyme activity in vitro could be detected by the fluorescence assay, and its biological sensing ability was studied. The effect of the different length of polypeptide chain on the luminescence quenching efficiency and sensing ability was also studied.In chapter three, silica nanoparticles embedded ruthenium (Ⅱ) complexes with carboxyl groups were synthesized and characterized. Based on the fluorescence quenching properties of gold nanoparticles, the colorimetric method and fluorescence essay were used to detect glutathione (GSH). Ruthenium (Ⅱ) complexes, silica nanoparticles embedded ruthenium (Ⅱ) complexes and silica nanoparticles embedded ruthenium (Ⅱ) complexes with carboxyl groups were compared in the sensing of the glutathione (GSH).