Department of Chemistry G. Ciamician, University of Bologna, via F. Selmi 2, I-40126 Bologna, Italy.
J Chromatogr A. 2009 Dec 25;1216(52):9106-12. doi: 10.1016/j.chroma.2009.06.037. Epub 2009 Jun 18.
Synthesis and applications of new functional nanoparticles are topics of increasing interest in many fields of nanotechnology. Chemical modifications of inorganic nanoparticles are often necessary to improve their features as spectroscopic tracers or chemical sensors, and to increase water solubility and biocompatibility for applications in nano-biotechnology. Analysis and characterization of structured nanoparticles are then key steps for their synthesis optimization and final quality control. Many properties of structured nanoparticles are size-dependent. Particle size distribution analysis then provides fundamental analytical information. Asymmetrical flow field-flow fractionation (AF4) with multi-angle light scattering (MALS) detection is able to size-separate and to characterize nanosized analytes in dispersion. In this work we focus on the central role of AF4-MALS to analyze and characterize different types of structured nanoparticles that are finding increasing applications in nano-biotechnology and nanomedicine: polymer-coated gold nanoparticles, fluorescent silica nanoparticles, and quantum dots. AF4 not only size-fractionated these nanoparticles and measured their hydrodynamic radius (r(h)) distribution but it also separated them from the unbound, relatively low-M(r) components of the nanoparticle structures which were still present in the sample solution. On-line MALS detection on real-time gave the gyration radius (r(g)) distribution of the fractionated nanoparticles. Additional information on nanoparticle morphology was then obtained from the r(h)/r(g) index. Stability of the nanoparticle dispersions was finally investigated. Aggregation of the fluorescent silica nanoparticles was found to depend on the concentration at which they were dispersed. Partial release of the polymeric coating from water-soluble QDs was found when shear stress was induced by increasing flowrates during fractionation.
新型功能纳米粒子的合成与应用是纳米技术诸多领域中日益关注的话题。为了改善无机纳米粒子作为光谱示踪剂或化学传感器的特性，并提高其在纳米生物技术应用中的水溶性和生物相容性，通常需要对其进行化学修饰。因此，对结构纳米粒子进行分析和特性研究是其合成优化和最终质量控制的关键步骤。许多结构纳米粒子的性能都与其尺寸有关。因此，粒径分布分析为其提供了基本的分析信息。采用多角度光散射（MALS）检测的不对称流场流分离（AF4）能够对分散体系中的纳米级分析物进行尺寸分离和特性研究。在这项工作中，我们重点研究了 AF4-MALS 在分析和表征不同类型结构纳米粒子方面的核心作用，这些纳米粒子在纳米生物技术和纳米医学领域的应用日益广泛，包括聚合物包覆的金纳米粒子、荧光硅纳米粒子和量子点。AF4 不仅对这些纳米粒子进行了尺寸分级，并测量了它们的流体力学半径（r(h)）分布，还将其与仍存在于样品溶液中的纳米粒子结构中未结合的、相对低分子量（M(r)）的组分分离。在线实时 MALS 检测给出了分级纳米粒子的回转半径（r(g)）分布。然后，从 r(h)/r(g) 指数获得有关纳米粒子形态的附加信息。最后还研究了纳米粒子分散体的稳定性。荧光硅纳米粒子的聚集情况取决于其分散时的浓度。在分级过程中通过增加流速来诱导剪切应力时，发现水溶性量子点的聚合物涂层部分释放。
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