【作者】 杜娟；

【导师】 夏之宁；

【作者基本信息】 重庆大学 ， 生物制药工程， 2013， 博士

【摘要】 金纳米粒子性质稳定、制备简单、粒径均匀、亲和力强、生物相容性好、易于生物分子固定修饰，是研究最早的贵金属纳米粒子之一，能广泛应用于纳米生物传感器和疾病的诊疗中。通过控制不同的合成条件和合成方法能够得到不同形状、不同尺寸的金纳米粒子，且具备不同的性质。金纳米粒子可用于分析化学的各个领域。合成性能更好、更稳定、粒径更均匀的金纳米颗粒是分析应用的第一步。本论文从建立新的合成方法出发，分别利用微波辅助加热法和水热反应法，合成了几种具有不同性质的金纳米粒子，对合成条件进行了优化，对得到的金纳米粒子的性质进行了表征，并利用光谱分析法考察了其在不同领域中的应用。全文主要工作及结论如下：①利用微波辅助加热法，利用柠檬酸钠为还原剂，合成了金纳米粒子。生成的金纳米粒子最大吸收波长位于520nm，形状为球形，粒径为13.3nm，粒径分布均匀。生成的金纳米粒子能成功用于溶菌酶的荧光猝灭研究中，溶菌酶的荧光强度随金纳米粒子用量的增加逐渐降低。通过S-V方程计算得到反应体系在不同温度下的S-V猝灭常数和双分子猝灭常数可知该反应体系为静态猝灭，并通过计算得到其结合常数和结合位点数。结果表明溶菌酶与金纳米粒子之间只有一个结合位点，反应体系温度升高结合常数增大，说明升高温度有利于反应的进行，该反应为吸热反应。通过对反应体系的热力学参数进行计算和讨论发现溶菌酶与金纳米粒子的结合过程是自发过程，反应物间的主要作用为疏水作用。②利用微波辅助加热法生成的金纳米粒子未经任何修饰直接用于对硝基苯酚与硼氢化钠反应体系的催化剂，并获得了成功。可由紫外光谱监测反应的情况。反应体系中硼氢化钠浓度大大过量，故可认为反应过程中其浓度保持不变，反应速率仅与对硝基苯酚的浓度有关，反应为假一级反应，且反应体系的表观反应速率随金纳米粒子浓度的增大而线性增大。论文中还对金纳米粒子用于三种硝基苯酚异构体与硼氢化钠反应的催化情况进行对比，结果表明，在相同反应条件下，加入相同浓度的金纳米粒子，三种异构体与硼氢化钠反应的表观反应速率的顺序如下：间硝基苯酚>对硝基苯酚>邻硝基苯酚。论文中对造成硝基苯酚三种异构体与硼氢化钠反应时反应速率存在差异的原因进行了初步的分析。③利用柠檬酸钠还原法生成粒径约为13nm的金纳米粒子，利用巯基化合物2-硫代巴比妥酸（TBA）对其进行修饰并表征。通过简单的操作步骤，TBA能够成功修饰至金纳米粒子的表面，修饰后的金纳米粒子紫外光谱的最大吸收峰由520nm红移至524nm。修饰之后的TBA-GNPs具有pH敏感的性质，有望用作pH传感器的研究中。经TBA修饰后的金纳米粒子性质更为稳定，在氯化钠溶液中的稳定性增加。纳米粒子表面所带负电荷增加，故与金属离子作用时更为灵敏。与未经修饰的金纳米粒子相比，修饰后的TBA-GNPs的无论对于硝基苯酚与硼氢化钠的反应体系还是铁氰化钾与硫代硫酸钠反应体系的催化活性均降低，论文中对出现该现象的原因进行了分析。④利用水热反应法，使用BSA为还原剂，在碱性条件下90oC下反应40分钟，获得了具有红色荧光的BSA-金纳米簇。金纳米簇的最大激发与最大发射波长分别位于550与650nm。以丽丝胺罗丹明B为参比物质测得所合成的金纳米的荧光量子产率约为1.11%。生成的金纳米簇具有“酸沉碱溶”的性质。即在酸性条件易析出生成沉淀，在碱性条件下又能重新溶解。汞离子能够使金纳米簇荧光完全猝灭，在汞离子浓度为2×10^-7至1×10^-5M金纳米簇荧光猝灭的程度与汞离子的浓度呈线性关系，检测限为0.6×10^-7M。在类似条件下，以HSA为还原剂，经过40分钟水热反应后，也生成了具有红色荧光的金纳米簇。⑤以卵清蛋白为还原剂，分别在37oC水浴条件下和90oC水热反应条件下生成了卵清蛋白-金纳米簇。通过优化得到了两个反应体系的最佳反应条件。在水浴加热条件下，当氯金酸浓度固定为2.33mM时，卵清蛋白及氢氧化钠的最佳反应浓度分别为10.71mg mL^-1及0.095M。水浴加热6小时时反应体系荧光达到最大值。在同样的反应物浓度下在90度下水热反应30分钟，反应体系荧光达到最大值。生成的金纳米簇均呈现红色荧光，最大发射峰分别位于636与637nm。对两个反应条件下反应生成的金纳米簇的表面结构进行了表征，结果表明卵清蛋白均已成功修饰至金纳米簇的表面。固定各反应物浓度不变，实验中还对比了反应体系在37℃下水浴加热反应6小时、90℃下水浴加热反应30分钟和90℃下水热反应30分钟所得到的各反应液的荧光强度，实验结果表明，在水热反应条件下生成的荧光金纳米簇具有最强的最强的荧光强度。更多还原

【Abstract】 Gold nanomaterials have the advantages of good stability, simple preparation,uniform particle size, strong affinity, good biocompatibility and easy to biolabeling,which could be widely used in nano-biosensors and the diagnosis and treatment of thedisease. Gold nanomaterials with different shapes and sizes of can be synthesized bycontrolling the conditions and methods during the synthesizing process. Goldnanomaterials can be used in various fields in analytical chemistry. It is of mostimportance to synthesize gold nanomaterials with better properties, better stability, andmore uniform. In this thesis, we started from the establishment of new synthesismethods to synthesize gold nanoparticles.Microwave-assisted heating methods andhydrothermal methods were used. The conditions of the synthetic process wereoptimized and the characters of the as-prepared gold nanomaterials were measured. Theapplications of the as-prepared gold nanomaterials in different fields were determinedby spectrophotometry method.The main contents and conclusions are as follows:1. Gold nanoparticles （GNPs） were synthesized by microwave-assisted heatingunder reflux, using trisodium citrate as the reducing agent. GNPs had a maximumabsorption peak at520nm, with an average diameter of13.3nm in spherical shape.GNPs were then successfully used in the fluorescence quenching of lysozyme. Thefluorescence intensities of lysozyme were declined gradually with the increase of theconcentration of the GNPs. The fluorescence quenching mechanism was studied by theStern-Volmer quenching constant and the bimolecular quenching constant through theStern-Volmer equation. It was proved that the reactions of GNPs and lysozyme werestatic quenching processes. Binding constant and the number of the binding site of thereaction systems were also calculated. There is only one single binding site in lysozymewas existed for GNPs, while the binding constant increased with the increase of thetemperature, which suggesting that the interaction was endothermic. As can be inferredfrom the thermodynamic parameters, the binding processes between GNPs andlysozyme were spontaneous, while accompany with a strong contribution of thehydrophobic effect.2. GNPs synthesized by microwave-assisted heating method were successfullyused as catalyst in the borohydride reduction of nitrophenols without any further modification. The reaction could be monitored by time-dependent UV spectra. Theconcentration of NaBH4in the reactive system was so much excess to that of p-NP, sothat the rates of the reduction are assumed to be independent of the concentration ofNaBH4, and thus the kinetics of the reduction could be treated as pseudo-first-order inp-NP concentration. The apparent rate constant of the reaction system raised almostlinearly with the increase of the GNPs concentrations. Under the same reactionconditions, the apparent rate constant of different isomeric nitrophenols followed theorder m-nitrophenol> p-nitrophenol> o-nitrophenol. The reason why these phenomenahappened was analyzed.3. Gold nanoparticles with a13nm diameter were synthesized by using trisodiumcitrate as the reducing agent and modified by2-thiobarbituric acid （TBA）. Aftermodification, the maximum absorbance wavelength shifted from520to524nm. Themodified TBA-GNPs were pH-sensitive, and were hopefully applied in the research ofpH sensors. Compared with GNPs with no modification, TBA-GNPs existed morestability, and contained more negative charges, which causing the GNPs more stable inNaCl solutions and more sensitive by adding metal ions. The catalytic activity ofTBA-GNPs was determined, and was compared with unmodified GNPs. It was provedthat the catalytic activity of TBA-GNPs was reduced obviously either in theborohydride reduction of nitrophenols or redox reaction between potassium ferricyanideand sodium thiosulfate. The reason why this happened was analysed.4. BSA-gold nanoclusters with red fluorescence were synthesized by hydrothermalmethod at90oC for40min were reported, using BSA as the reducing regent. Themaximum excitation and emission wavelength was550and650nm, respectively. ALissamine rhodamine-B sulphonyl chloride （LRSC） dye solution was used as areference, and the quantum yield of the BSA-gold nanoclusters synthesized byhydrothermal method was1.11%. The fluorescence intensity of BSA-gold nanoclusterscould be switched on and off by controlling the pH value of the solution. SuchBSA-gold nanoclusters could be precipitate in acidic conditions or re-disperse inalkaline conditions. The BSA-gold nanoclusters could be used as fluorescence probe forHg²⁺sensing with high sensitivity and selectivity. The fluorescence intensity ofBSA-gold nanoclusters toward Hg²⁺decreased linearly over the Hg²⁺concentrationrange of2×10^-7to1×10^-5M. The limit of detection （LOD） for Hg²⁺was0.6×10^-7M.Under similar conditions, HSA-gold nanoclusters with red fluorescence were alsosynthesized by hydrothermal method.5. Ovalbumin-gold nanoclusters were synthesized by water bath heating method at 37oC and hydrothermal method at90oC, using ovalbumin as the reducing regent. Whenthe concentration of HAuCl4was constant at2.33mM, the optimum reaction conditionswere discussed and the best reaction concentration of ovalbumin and NaOH were10.71mg mL^-1and0.095M, respectively. The fluorescence intensity of OVA-goldnanoclusters reached to its maximum values when reacting at37oC,6h for water bathheating and at90oC,30min for hydrothermal heating. The maximum fluorescenceemission were636and637nm for gold nanoclusters synthesized by water bath heatingor hydrothermal heating, respectively, with bright red color. FT-IR spectra of theOVA-gold nanoclusters synthesized by different ways suggested that OVA weremodified on the surface of the gold nanoclsters successfully. While keeping theconcentration of all the reactants constant, the FL intensities of OVA-gold nanoclusterssynthesized by different ways were observed. The results suggested that OVA-goldnanoclusters synthesized by hydrothermal method have the highest FL intensity.更多还原