Division of Physical Sciences and Engineering, Solar and Photovoltaic Engineering Research Centre, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Nanoscale. 2013 Jun 7;5(11):5017-26. doi: 10.1039/c3nr00990d. Epub 2013 May 2.
Size is a defining characteristic of nanoparticles; it influences their optical and electronic properties as well as their interactions with molecules and macromolecules. Producing nanoparticles with narrow size distributions remains one of the main challenges to their utilization. At this time, the number of practical approaches to optimize the size distribution of nanoparticles in many interesting materials systems, including diamond nanocrystals, remains limited. Diamond nanocrystals synthesized by detonation protocols - so-called detonation nanodiamonds (DNDs) - are promising systems for drug delivery, photonics, and composites. DNDs are composed of primary particles with diameters mainly <10 nm and their aggregates (ca. 10-500 nm). Here, we introduce a large-scale approach to rate-zonal density gradient ultracentrifugation to obtain monodispersed fractions of nanoparticles in high yields. We use this method to fractionate a highly concentrated and stable aqueous solution of DNDs and to investigate the size distribution of various fractions by dynamic light scattering, analytical ultracentrifugation, transmission electron microscopy and powder X-ray diffraction. This fractionation method enabled us to separate gram-scale amounts of DNDs into several size ranges within a relatively short period of time. In addition, the high product yields obtained for each fraction allowed us to apply the fractionation method iteratively to a particular size range of particles and to collect various fractions of highly monodispersed primary particles. Our method paves the way for in-depth studies of the physical and optical properties, growth, and aggregation mechanism of DNDs. Applications requiring DNDs with specific particle or aggregate sizes are now within reach.
尺寸是纳米颗粒的一个决定性特征；它影响纳米颗粒的光学和电子性质以及它们与分子和大分子的相互作用。生产具有窄尺寸分布的纳米颗粒仍然是它们应用的主要挑战之一。目前，在许多有趣的材料系统中优化纳米颗粒尺寸分布的实用方法数量仍然有限，包括金刚石纳米晶体。通过爆炸协议合成的金刚石纳米晶体 - 所谓的爆炸纳米金刚石（DND） - 是药物输送、光子学和复合材料的有前途的系统。DND 由直径主要 <10nm 的初级颗粒及其聚集体（约 10-500nm）组成。在这里，我们介绍了一种大规模的速率区带密度梯度超速离心法，以高产量获得单分散纳米颗粒的分数。我们使用该方法对高度浓缩和稳定的 DND 水溶液进行分级，并通过动态光散射、分析超速离心、透射电子显微镜和粉末 X 射线衍射研究各种级分的尺寸分布。这种分级方法使我们能够在相对较短的时间内将克级数量的 DND 分离成几个尺寸范围。此外，每个级分获得的高产物收率允许我们将分级方法迭代应用于特定尺寸范围的颗粒，并收集各种高度单分散初级颗粒的级分。我们的方法为 DND 的物理和光学性质、生长和聚集机制的深入研究铺平了道路。现在，需要特定颗粒或聚集体尺寸的 DND 的应用已经触手可及。
