【作者】 凌凯；

【导师】 张其清；

【作者基本信息】 北京协和医学院 ， 生物医学工程， 2013， 博士

【摘要】 在分析科学领域中,纳米金比色检测法因其简便性和多样性吸引了相当多研究者的关注。纳米金比色法主要依赖于被检测物引起的纳米金粒子聚集,而这种聚集又导致了纳米金溶液剧烈的颜色变化。本文利用纳米金比色法在水溶液中测定了三种大分子的分子量,并且探讨了其测定的机理。主要内容和结果如下：1.纳米金比色法被用于测定聚酰胺-胺型(PAMAM)树状大分子分子量。这种方法是通过测定一定质量浓度下的溶液中PAMAM树状大分子的分子数量而得到其所对应的分子量。在一个确定质量浓度的树状大分子溶液中,其分子数量由分子量所决定。当PAMAM树状大分子浓度为32.4μg/ml时,纳米金溶液的颜色及吸光度随着第0代到第5代PAMAM树状大分子的分子量(从517至28826Da)变化而发生规律性改变。因此,纳米金比色法将不同的PAMAM树状大分子分子量转化为光学及颜色的信号。精确测定PAMAM树状大分子分子量只需要观测纳米金溶液的颜色变化即可。这种纳米金比色法使得PAMAM树状大分子分子量的测定变得更简单、方便和灵敏。纳米金比色法在数分钟内即可完成PAMAM树状大分子分子量的测定,无需精密仪器和特殊培训。2.纳米金比色法被用于测定支链型聚乙烯亚胺(BPEI)的分子量。这种方法是建立在BPEI引起的纳米金粒子聚集基础上。本研究发现,不同分子量的BPEI (1.25μg/ml)导致了纳米金粒子不同的团聚程度以及其溶液颜色的相应变化。因此,BPEI的不同分子量(从523至275300Da)就可以通过纳米金比色法直接用肉眼观测区别,用分光光度法测定其分子量。这种测定BPEI分子量的纳米金比色法简单(仅需在室温中共混溶液),快捷(仅需15min)和灵敏(仅与分子量有关)。3.纳米金比色法被用来测定聚乙二醇(PEG)的分子量。通常,PEG能吸附到纳米金粒子表面,稳定纳米金粒子。这种比色方法就是建立在不同分子量(从521至13646Da)的PEG对纳米金的不同稳定能力基础上。PEG对纳米金的稳定能力大小依赖于其分子的大小(均方根末端距<h2>05)和纳米金的粒径。在一个确定的粒径和纳米金粒子之间静电斥力被屏蔽掉的条件下,不同大小的PEG分子导致了不同的纳米金聚集度以及其溶液的不同颜色。因此,不同大小的PEG分子就可以通过纳米金比色法直接用肉眼观测区别,用分光光度法测定其具体的数值。然后,利用PEG分子的大小与其分子量之间的关系式计算得出PEG的分子量。这种比色法为PEG分子量的测定提供了一种全新的替代性分析方法。更多还原

【Abstract】 Gold nanoparticle (AuNP) colorimetric methods have attracted considerable attentions in analytical science, due to their simplicity and versatility. This colorimetric method typically depends on a quantitative coupling between analyte and the aggregation of AuNPs, which leads to a dramatic color change of the AuNPs solution. In this thesis, AuNP-based colorimetric methods were used to determine the molecular weight (MW) of three kinds macromolecules straightforwardly in solution and then were investigated the mechanisms. The main contents are as follows:1. A AuNP-based colorimetric method was developed for the MW determination of Poly(amido amine)(PAMAM) dendrimers. In particular, we used the method to identify the number of the dendrimer in solution, which corresponds to a specific MW at a certain mass concentration. At32.4μg/ml of PAMAM dendrimer solutions, the optical properties of the AuNPs were observed to change regularly from the Generation0to5dendrimer (from517to28826Da). Thus, the AuNPs based colorimetric method transformed the MW of PAMAM dendrimers into color signals. Determining the exact MW of PAMAM dendrimers simply required observing the color changes of the AuNPs. The determination methodology based on the AuNPs offers simplicity, convenience, and sensitivity. It can be accomplished in minutes without sophisticated instruments or specialized training.2. A AuNP-based colorimetric method was invented for the MW determination of branched polyethylenimine (BPEI), relied on the aggregation of AuNPs. We found that the different MW of BPEI (1.25μg/ml) leads to the different aggregation degrees of AuNPs and the color changes of the solutions. Thus, the MW (from523to275300Da) can be distinguished straightforwardly by visual inspection and determined by spectrophotometry. This novel approach is simple (mixing solutions at room temperature), rapid (within15min) and sensitive (only depending on the MW). 3. A AuNP-based colorimetric method was established for the MW determination of poly(ethylene glycol)(PEG), relied on the different stabilizing ability of PEG (from521to13646Da), which is used to adsorb onto AuNPs. The stabilizing ability of PEG is dependent on its molecular size (the root-mean-square end to end length (h2)0.5) and the gold nanoparticle size. After screening the electrostatic repulsion between AuNPs, the different sizes of PEG molecules lead to the different aggregation degrees of AuNPs and the color changes of the solutions. Thus, the sizes of PEG molecules can be distinguished straightforwardly by visual inspection and determined by spectrophotometry. And then, we can use the relation equation between the size and the MW of PEG to figure out PEG MW. This colorimetric method provides an alternative analytical technique to the MW determination of PEG更多还原