Department of Chemistry, Rice University, Houston, Texas 77005, United States.
Anal Chem. 2012 Nov 6;84(21):9238-45. doi: 10.1021/ac301980a. Epub 2012 Oct 9.
Many of the solution phase properties of nanoparticles, such as their colloidal stability and hydrodynamic diameter, are governed by the number of stabilizing groups bound to the particle surface (i.e., grafting density). Here, we show how two techniques, analytical ultracentrifugation (AUC) and total organic carbon analysis (TOC), can be applied separately to the measurement of this parameter. AUC directly measures the density of nanoparticle-polymer conjugates while TOC provides the total carbon content of its aqueous dispersions. When these techniques are applied to model gold nanoparticles capped with thiolated poly(ethylene glycol), the measured grafting densities across a range of polymer chain lengths, polymer concentrations, and nanoparticle diameters agree to within 20%. Moreover, the measured grafting densities correlate well with the polymer content determined by thermogravimetric analysis of solid conjugate samples. Using these tools, we examine the particle core diameter, polymer chain length, and polymer solution concentration dependence of nanoparticle grafting densities in a gold nanoparticle-poly(ethylene glycol) conjugate system.
许多纳米粒子的溶液相性质，如胶体稳定性和水动力直径，都受粒子表面结合的稳定基团数量（即接枝密度）的控制。在这里，我们展示了两种技术，分析超速离心（AUC）和总有机碳分析（TOC），如何分别应用于该参数的测量。AUC 直接测量纳米粒子-聚合物缀合物的密度，而 TOC 提供其水分散体的总碳含量。当将这些技术应用于巯基化聚乙二醇封端的金纳米粒子时，在一系列聚合物链长、聚合物浓度和纳米粒子直径范围内测量的接枝密度相差不超过 20%。此外，测量的接枝密度与通过固体缀合物样品的热重分析确定的聚合物含量很好地相关。使用这些工具，我们研究了在金纳米粒子-聚乙二醇缀合物体系中，颗粒核心直径、聚合物链长和聚合物溶液浓度对接枝密度的影响。
