Preparation Of Fluorescent Gold Nanoparticles And Its Application In Ion Detection

With the integration of chemical, biological, physics and medical,nanotechnology has been played a very important role in application of biologicalscience, imaging methods, analysis field in modern science. Nano material isresearched actively, which was closed to the actual apply, that cannot be ignored.Nanoparticles have unique properties （i.e. quantum size effect, small size effect,surface effect and the macroscopic quantum tunnel effect）, which play a crucial rolein wide field. And among the nano-materials, gold nanoparticles have excellentphysical performance，such as surface plasma resonance （SPR）-when the frequencyof the input photons are conformed to the frequency of free electrons of metal surfaceconcussion, it will happen energy resonance phenomenon, and the resonancefrequency of the surface plasma resonance is dependent upon the size, shapeinterparticle interactions of the nanoparticles. As the shape or size of the particlechanges, the surface geometry changes causing a shift in the electric field density onthe surface, which causes a change in the oscillation frequency of the electrons,generating different cross-sections for the optical properties including absorption andscattering. Using the surface plasma technology, we can qualitatively judge theinteraction between the molecules such as protein-nucleic acid, protein-protein,nucleic acids-nucleic acids, and that it has advantages in real time monitoring anddetection without marking. Since its size compared to the Fermi wavelength ofelectrons, these metal nanomaterial always show molecule-like behavior includingdiscreet electronic states and size-dependent fluorescence, which was the other uniqueoptical properties, and that could be widely used in sensor, which has established atypical analysis system. These properties of the gold nanoparticles are not onlydepended on their size, but also on their shape, therefore, how to control the size andthe shape of the metal particles getting the related properties was the hot spot.Recently, metal clusters （size less than5nm） was played close attention by agreat number of researchers. Because of the special properties, the fluorescentwater-soluble gold nanoparticles could be used as a biomarker, biological sensors,nanoscale glowing optoelectronic source.In the thesis, we have done something about preparation of functionalizedfluorescent gold nanoparticles and then making them act as gene carrier and environmental monitor, as follows：1.Synthesis of fluorescent gold nanoparticles with11-mercaptoacetic acid （MUA）and glutathione （GSH） and its application in Pb²⁺ detection. Using the method ofetching and ligand exchange, the ligand on functionalized clusters are MUA and GSH.The fluorescence of the particles were from MUA ligand to metal charge transfer, andGSH has a special function in identifying and capturing free lead ion which lead toparticles union and then the change of fluorescence, therefore it may show anexcellent selectivity in the detection of a large number of heavy metal ions.2. Synthesis of fluorescent gold nanoparticles with mercapto thymine （TSH） andMUA and its application in S2-detection. New gold nano-particles are formed throughone-pot with mercapto thymine （TSH） and MUA on the surface. The fluorescence ofthe particles were from MUA ligand to metal charge transfer, the structure of the TSHmolecules is used to build a space effect, and the special properties of the TSH couldaffect the sates between neighboring gold nanoparticles in present of target ions,which showing a height selectivity of the sulfur ions. Through the optimum condition,we plan to accomplish the detection of sulfur ions in the water.3. Polythyleneimine capped Au nanoparticles acted as carrier to transfection.Mixed PEI@Au with red fluorescent protein gene （RFP）, and culture together withcervical cancer cells （Hela） and embryonic stem cell, expecting to achieve lowtoxicity and high efficient dual-lable transfection.