Synthesis Of Fluorescent Gold Nanoparticles And Their Applications In Chemical And Biological Sensing

With the continuous development of nanotechnology, nanomaterials have beenwidely used in chemistry, biology, environmental science and other fields owing totheir unique physical and optical properties. In particular fluorescent gold nanodots（AuNDs） show extensive application potential in chemo/biosensing, biomedicalengineering and material science because of their advantages, such as facile synthesisand modification, good photostability and excellent biocompatibility. On the basis ofprevious work, we have studied the synthesis of AuNDs as well as in chemical andbiological sensing. The main points of our work in thesis are summarized as follows:In chapter2, we introduced a one-pot synthesis strategy to prepare MUA-cappedfluorescent AuNDs, and demonstrated their applition for highly sensitive andselective Mercury （II） ions (Hg²⁺) detection in aqueous solution. The Hg²⁺-inducedflorescence quenching is mainly due to metal-metal interactions between Hg²⁺andAu⁺, and stronger thiophilic tendency of Hg²⁺. The limit of detection （LOD, S/N=3）is0.1nM for Hg²⁺, which is higher than previous works of Hg²⁺detection by usingMUA-capped AuNDs at least one order of magnitude. We found that the selectivity ofthe probe could be adjusted by controlling the pH value of solution and withoutdemand of any masking agent. To test the potential applications of our fluorescentAuNDs sensor for the analysis of Hg²⁺in environmental samples, we tested a springwater sample obtained from Yuelu Mountain. The concentration of Hg²⁺in the samplewe detected was in good agreement with that determined using cold absorptionspectrometry analysis.In chapter3, MUA-capped fluorescent Au nanodots have been synthesed usingconventional etching method, and were applied to highly selective cyanide sensing inaqueous solution based on Elsner reaction. The LOD towards cyanide is5nM （130ppt）, which is far below national standards specified value. To test the potentialapplications of the sensor in environmental samples, a actual water sample obtainedfrom Xiangjiang River was tested, the concentration can be detected the lower limit of20nm with external addition method.In chapter4, eight kinds of functionalized fluorescent AuNDs with similaremission have been designed and synthesized through dual ligands modificationmethod. These fluorescent probes are used to build a protein sensing array based on the “chemical nose/tongue” strategies. Fluorescence response patterns can be obtainedon the array and identified via linear discriminate analysis （LDA）. Eight kinds ofproteins can be effectively distinguished and discriminated at a concentration of UVabsorbance A280=0.005, and the unknown protein samples, can be correctly identified,with an identification accuracy of100%. We also created a barcode system of proteinsbased on the analysis strategy, and hoped to achieve rapid and accurate proteinidentification through barcode scanning. In addition, we studied the detectionmechanism according to energy transfer and particle dispersity preliminarily.