Surface Modification Of Gold Nano-sol And In The Application Of Ph Sensors

With unique optical properties, gold nanoparticles have promising prospects in medical, sensing, analytical chemical, which have become a hot topic in recent years. In this thesis, gold nanoparticles have been investigated from three dimensions.Firstly, a series of gold nanoparticles with controllable diameters were prepared via reduction and an improved seed-mediated technique respectively. Comparison between these two methods was made, which laid a foundation for latter investigations, such as surface modification and spectroscopy property of gold nanoparticles.Secondly, We modified the surface of gold nanoparticles, and got excellent properties. Gold nanoparticles are tending to aggregate for their small diameter , large surface ratio and van der waals force. Linearα-methoxy-ω-mercapto-poly (ethylene glycol) molecules were chemically bonded to gold particle surfaces via the end group, SH, forming polymer brush-coated gold colloids. Experimental results indicate that the PEG-modified gold nanoparticles can resist aggregation under rigorous conditions of pH=1~13.5 or salt concentration as high as 1.20 mol/L, because the adsorbed PEG layer provides steric stabilization for the gold nanoparticles. Therefore, the PEG layer-coated gold nanoparticles largely solve the problems associated with nanoparticles, such as susceptivity to environment conditions and easiness in aggregation, and can survive in complex conditions (e.g. physiological conditions).Because of the water soluble, nontoxic, and biocompatible properties of PEG, the gold nanoparticle/PEG conjugated with high stability and excellent properties of both gold nanoparticles and PEG can serve as bio-nanoprobes for bio-analysis.Thirdly, we applied the gold nanoparticles to PH sensor. We modified successively the signals and PEG on the surface of gold nanoparticles, which then be tested. Experimental results show that the PEG-modified gold nanoparticles can resist aggregation under rigorous conditions of pH=1~13.5 or salt concentration as high as 1.20 mol/L, moreover they maintain preferable performance. Even dispersed in a series of PH buffer solution, the gold nanoparticles are sensitive to PH value. All the excellent properties lay a foundation for applying PH sensor of the gold nanoparticles to complicated bioanalysis.