Synthesis, Assembly Of Novel Silica, Gold Composite Nanomaterials And Their Applications In Biomedicine,Catalysis

Preparation, chemical functionalization and assembly of Au nanoparticles, silicon oxide nanomaterial and the Au/SiO2composite nanomaterials, and their applications are one of the most important subjects in the fields of chemistry, molecular biology, medicine and so on. The technologies of preparing and assembling Au, SiO2nanopartices, and their applications are reviewed in this dissertation. The main detail is as follows:Au@SiO2core/shell nanoparticles were synthesized by using (3-mercaptopropyl)trimethoxysilane (MPTMOS) as cross-linker instead of (3-amino-propyl)trimethoxysilane. The nanoparticles were characterized by UV-visible spectroscopy, TEM and fluorescence microscope. Our results showed the nanocrystals were uniformly spherical and high monodisperse in water. Single gold nanoparticle was located at the center of silicon oxide shell. Moreover, no obvious change of fluorescence intensity of Au/SiO2composite nano-materials was observed after it was excited for3600seconds by successive intense irradiation, which demonstrates that these nanoparticles had excellent photostability. In addition, Au@SiO2core/shell nanoparticles were covalently conjugated with the TPA using (3-aminopropyl)trimethoxysilane and glutaraldehyde as the crosslinker and successfully completed the fluorescence imaging of nasopharyngeal carcinoma cells CNE-1.Based on the principle that the-SH could be oxidated to form a disulfide bond, we had synthesized the gold-nanoparticle-modified silica nanowires in solution by employing3-mercapto-propyltrimethoxysilane as the cross-linker under mild conditions. The nanowires were characterized by UV-visible spectroscopy, TEM and fluorescence microscope. The results demonstrate that the silica nanowires of various thicknesses that the gold nanoparticles were embedded in and/or attached on SiNWs were prepared. The method is simple, low cost, safe and feasible, so it is helpful for meeting the social great demand by synthesizing the SiNWs in large scale. Gold-nanoparticles were loaded on SiNWs by chemical bond that it showed the good stability and excellent catalytic activity. The Catalytic reduction of reaction of p-nitrophenol follows the first-order kinetic process when NaBH4is excessive, the reaction rate constant k=0.85min-1. Moreover, the composite nanoparticles were easy to covalently conjugate with the target molecule (i.e. biological molecule), and it made them become ideal candidates for use in chemical sensor and biosensor.The monolayer membrane of gold nanoparticles was controllably prepared on the glass chip using optical glass as substrate and MPTMOS as agglomerant. Then, anti-TAP and BSA were used to functionalize this monolayer membrane of gold nanoparticles to prepare the optical immune sensing chip that could specifically response to TPA. This chip can directly detect the TPA in complex sample using ultraviolet visible spectrophotometer with good stabilization and selectivity. In addition, because this technique need only measure the absorbance change in the largest ultraviolet absorption wavelength of TPA to detect the content of TPA in samples, this method can be easily popularized for this kind of simple and fast format. Under the optimized conditions, the decreased absorbency (AA) was linear with TPA concentration (C) in the range of1～1000ng/L and the low detection limit was1.2×10-3ng/L. The results of determination for TPA in three synthetic samples were identical with the true values, the recovery (98.9%-102.4%) and the standard deviation (1.6～2.8%) was satisfactory. Moreover, the method was applied to the determination of the content of TPA in human serum samples. Compared to the serum of healthy person, the response value was improved obviously in cancer patients. The concept demonstrated that the application of Immunosensors based on the UV-Vis absorption of gold-nanoparticles to quantitative detecting the antigen was feasible.Liquid TPA optical bio-sensing probe was constructed using the anti-TPA, BSA and PEG functionalized gold nanoparticles. This method provides a fast, simple and efficient character for quantitative analysis of TPA. In this work, a series of factors (i.e. reaction time, reaction temperature and pH) were investigated to find the better determination condition. Under the optimized conditions, a linear relationship of the decreased absorbency (△A) and TPA concentration (C) was established in the range of0.4-200ng/mL using the equation-△A=0.02767C+0.00632(R=0.99271) and the low detection limit was0.108ng/mL. The results of the determination for TPA in serum real samples were identical with the true value, and the relatively error is at-4.0～8.7%.By using the (3-aminopropyl)trimethoxysilane as cross-linker, the multilayer chip was formed by alternating Au-nanoparticles and SiO2-nanoparticles on nano-Au single-layer. The multilayer chip was characterized by UV-visible spectroscopy, SEM and so on. The absorbing intensity at540nm of chip increased with enhancement of layer of Au-nanoparticles, but the position and shap of the absorption peak was nearly invariant. The TEM image of the multilayer film proved this method yielded the Au-nanopartices on the multilayer chip surface with20nm in diameter and uniform. The successful preparation of multilayer chip paved a way for further study and application. When the multilayer chip was modified by anti-TPA and the remaining active sites of multilayer chip were blocked by BSA, the as-prepared sensoring chip can specifically recognize TPA molecular and the absorbing intensity of sensoring chip at the maximum absorption wavelengths was decreased because of immune reaction between TPA and anti-TPA. The results showed a linear relationship of the decreased absorbency (△A) and TPA concentration (C) was established in the range of1～1000ng/L using the equation-△A=0.05266C+0.00758(R=0.99734) and the low detection limit was0.027ng/L. The results of the determination for TPA in three serum real samples were identical with the conventional method of hospital, and the standard deviation was satisfactory.