Multidentate-protected colloidal gold nanocrystals: pH control of cooperative precipitation and surface layer shedding.
Multidentate-protected colloidal gold nanocrystals: pH control of cooperative precipitation and surface layer shedding.
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DOI：
10.1021/ja2001506
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发表时间：
2011-05-18
影响因子：
15
通讯作者：
Nie, Shuming
中科院分区：
文献类型：
--
作者：
Kairdolf, Brad A.;Nie, Shuming
利用多齿聚合物配体合成了尺寸可调、具有特殊pH敏感特性的胶体金纳米晶。多齿配体同时含有羧基和空间受阻的脂肪链，在成核和生长过程中既能还原金前驱体，又能稳定金纳米团簇。合成的纳米晶由内配位层和外聚合物层保护，可溶于水和极性溶剂。当溶液的pH值仅降低0.6个单位(从pH 4.85降至4.25)时，颗粒将经历从可溶到不溶的戏剧性转变，从而允许快速分离、纯化和重新分散受多齿保护的纳米晶体。一个令人惊讶的发现是，当部分表面羧基被质子化中和时，粒子不可逆转地脱离其外层聚合物层，并在非极性有机溶剂中溶解。此外，与金上紧密堆积的烷基硫醇自组装单分子膜相比，多齿聚合物涂层对小有机分子具有渗透性。这些见解对于设计“智能”成像和治疗纳米粒子非常重要，这种纳米粒子可以通过肿瘤间质或内吞细胞器中的微小pH变化而被激活。
Colloidal gold nanocrystals with broad size tunability and unusual pH-sensitive properties have been synthesized by using multidentate polymer ligands. Containing both carboxylic functional groups and sterically hindered aliphatic chains, the multidentate ligands are able to both reduce gold precursors and to stabilize gold nanoclusters during nucleation and growth. The “as-synthesized” nanocrystals are protected by an inner coordinating layer and an outer polymer layer, and are soluble in water and polar solvents. When the solution pH is lowered by just 0.6 units (from pH 4.85 to 4.25), the particles undergo a dramatic cooperative transition from being soluble to insoluble, allowing rapid isolation, purification, and redispersion of the multidentate-protected nanocrystals. A surprise finding is that when a portion of the surface carboxylate groups is neutralized by protonation, the particles irreversibly shed their outer polymer layer and become soluble in nonpolar organic solvents. Further, the multidentate polymer coatings are permeable to small organic molecules, in contrast to tightly packed self-assembled monolayers of alkanethiols on gold. These insights are important towards the design of “smart” imaging and therapeutic nanoparticles that are activated by small pH changes in the tumor interstitial space or endocytic organelles.
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影响因子：
15
作者：
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通讯作者：
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