Synthesis Of Gold Nanoparticles Using Protocatechuic Acid As Reductant And Detection Of Silver(Ⅰ) Ions Based On Gold Nanoparticles

Owing to their unique properties in optics, electrics, magnetics, and catalysis, gold nanoparticles have been widely applied in the fields of environment, medicine, catalysis, and so on. Synthesis of gold nanoparticles with uniform size and good stability is the premise of gold nanoparticles’ applications. Chemical reduction method is a preferred method for preparation of gold nanoparticles owing to its simple and quick operation, and the uniform size and good stability of the synthesized nanoparticles. Besides, no special expensive equipment is needed in the method. In the analytical applications of gold nanoparticles, the gold nanoparticle-based colorimetric assay has attracted a lot of attention due to the advantages of high speed, simplicity, accuracy and so on.In chapter 1, the special properties, synthesis, characterization of gold nanoparticles and their applications in analytical chemistry were summarized. The purpose and design of this paper were proposed in the end.In chapter 2, a novel one-step synthetic method for gold nanoparticles using protocatechuic acid as reductant in the presence of cetyl trimethyl ammonium bromide (CTAB) was developed The effecte of the molar ratio of protocatechuic acid to gold, concentration of CTAB, reaction temperature and reaction time on gold nanoparticles were optimized. Gold nanoparticles with uniform size and good stability were synthesized. This method provides a new way for the preparation of gold nanoparticles, requiring no special expensive equipments and featuring ease operation, fast response, low cost and so on.In chapter 3, we have developed a colorimetric mehod based on the deoxycytidine triphosphates (dCTPs)-functionalized AuNPs for quantitative detection of Ag+ in aqueous solution. The dCTPs-modified AuNPs are stable in a high-salt solution. When silver(Ⅰ) ions specifically bind with dCTPs, dCTPs are desorbed from the surfaces of the AuNPs. Then salt-induced AuNPs aggregation occurs, which induces color change of the AuNPs aqueous solution, and thus Ag+ could be detected. A detection limit of 8.3×10-8 mol/L (3σ/S) was obtained for the determination of Ag+. The method was validated by recovery tests using tap water and lake water samples, and the recovery ranged from 97.7 to 106.7%. The present AuNPs-based colorimetric method featured simplicity of operation, fast speed, high sensitivity and selectivity. Compared with DNA-functionalized AuNP-based method, it was economical and time saving due to avoiding any design and synthesis of various sophisticated DNA oligomer probes and separation process.In chapter 4, the work of using protocatechuic acid as reductant and CTAB as protectant to prepare gold nanoparticles and colorimetric assay based on the dCTPs-functionalized AuNPs for quantitative detection of Ag+ in aqueous solution were summarized and predicted.