Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
J Am Chem Soc. 2011 Jun 15;133(23):8884-7. doi: 10.1021/ja203328j. Epub 2011 May 19.
We demonstrate a high-resolution in situ experimental method for performing simultaneous size classification and characterization of functional gold nanoparticle clusters (GNCs) based on asymmetric-flow field flow fractionation (AFFF). Field emission scanning electron microscopy, atomic force microscopy, multi-angle light scattering (MALS), and in situ ultraviolet-visible optical spectroscopy provide complementary data and imagery confirming the cluster state (e.g., dimer, trimer, tetramer), packing structure, and purity of fractionated populations. An orthogonal analysis of GNC size distributions is obtained using electrospray-differential mobility analysis (ES-DMA). We find a linear correlation between the normalized MALS intensity (measured during AFFF elution) and the corresponding number concentration (measured by ES-DMA), establishing the capacity for AFFF to quantify the absolute number concentration of GNCs. The results and corresponding methodology summarized here provide the proof of concept for general applications involving the formation, isolation, and in situ analysis of both functional and adventitious nanoparticle clusters of finite size.
我们展示了一种基于不对称流场流分离（AFFF）的高分辨率原位实验方法，用于对功能金球簇（GNC）进行同时的尺寸分类和特性分析。场发射扫描电子显微镜、原子力显微镜、多角度光散射（MALS）和原位紫外可见光谱提供了互补的数据和图像，证实了簇的状态（例如二聚体、三聚体、四聚体）、组装结构和分馏群体的纯度。使用电喷雾差分迁移分析（ES-DMA）对 GNC 尺寸分布进行正交分析。我们发现，归一化 MALS 强度（在 AFFF 洗脱过程中测量）与相应的数浓度（通过 ES-DMA 测量）之间存在线性相关，从而确立了 AFFF 定量 GNC 绝对数浓度的能力。这里总结的结果和相应方法为涉及有限尺寸的功能和偶然纳米颗粒簇的形成、分离和原位分析的一般应用提供了概念验证。
