Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, Canada.
Langmuir. 2013 May 21;29(20):6018-24. doi: 10.1021/la3051093. Epub 2013 May 9.
An ideal colloidal system should be highly stable in a diverse range of buffer conditions while still retaining its surface accessibility. We recently reported that dispersing citrate-capped gold nanoparticles (AuNPs) in polymers, such as polyethylene glycol (PEG), can achieve such a goal because of contributions from depletion stabilization. Because AuNPs can weakly adsorb PEG to exert steric stabilization and the remaining citrate can impart charge stabilization, the extent of the contribution of depletion stabilization is unclear. In this work, we aim to dissect the contribution of each stabilizing factor. This is achieved by coating AuNPs with a layer of thiolated compound, which inhibits the adsorption of PEG and also allows for the control of surface charge. We found that depletion stabilization alone was insufficient to stabilize AuNPs at room temperature. However, when working together with other stabilization mechanisms, ultrahigh stability can be achieved. The size of both AuNPs and PEG was systematically varied, and the trends were compared to theoretical calculations. Finally, we report the importance of the surface chemistry of commercial AuNPs.
理想的胶体系统应在多种缓冲条件下高度稳定，同时仍保持其表面可及性。我们最近报道，在聚乙二醇（PEG）等聚合物中分散柠檬酸根封端的金纳米粒子（AuNPs）可以实现这一目标，因为这是由耗散稳定化的贡献。由于 AuNPs 可以弱吸附 PEG 以发挥空间稳定化作用，而剩余的柠檬酸根可以赋予电荷稳定化作用，因此耗散稳定化的贡献程度尚不清楚。在这项工作中，我们旨在剖析每个稳定化因素的贡献。这是通过在 AuNPs 上涂覆一层硫醇化合物来实现的，该化合物可以抑制 PEG 的吸附，并且还可以控制表面电荷。我们发现，仅靠耗散稳定化作用不足以在室温下稳定 AuNPs。然而，当与其他稳定化机制一起使用时，可以实现超高稳定性。AuNPs 和 PEG 的尺寸都被系统地改变，并将趋势与理论计算进行了比较。最后，我们报告了商业 AuNPs 的表面化学的重要性。
