Mao Ting, Ong Quy, Kohlbrecher Joachim, Poliukhina Ekaterina, Silva Paulo Jacob, Stellacci Francesco
Institute of Materials, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
PSI Center for Neutron and Muon Sciences, Paul Scherrer Institute, Villigen PSI CH-5232, Switzerland.
Nanoscale Horiz. 2025 Sep 16. doi: 10.1039/d5nh00260e.
Colloidal dispersions are key in many fields of science and technology. Recently, we have shown that small molecules can stabilize dispersions of nanoscale objects, such as proteins and nanoparticles by screening their net attractive interactions. This new effect is essentially the opposite of the well-known salt screening of electrostatic interaction. Here we show that small molecule stabilization of nanoparticles is a phenomenon strongly linked to the hydrophobic content of the particles as well as to the strength of their hydrophobic attraction. We compare the effect of proline on gold nanoparticles coated with 11-mercaptoundecane sulfonate (MUS) at varying percentages of the hydrophobic ligand octanethiol (OT). We show that the larger the percentage of OT, the larger the proline stabilization effect is. We also compare the effect of proline on water dispersions of nanoparticles with that on heavy water dispersions. In the latter, the hydrophobic effect plays a bigger role. We find that in DO, proline stabilization is larger. We also compare the effect of proline on the same MUS:OT gold nanoparticles before and after an annealing process that is known to render the particle more hydrophilic. Proline is more effective on the particles before annealing. Finally, we study the effect of proline on non-aggregating allMUS nanoparticles. We find that proline stabilization of these particles is mainly due to a reduction in the long-range attraction coefficient. Overall, we show that proline stabilizes nanoparticle dispersions more effectively as the hydrophobic attraction between nanoparticles increases.
胶体分散体在许多科学和技术领域中都起着关键作用。最近，我们已经表明，小分子可以通过屏蔽纳米级物体（如蛋白质和纳米颗粒）的净吸引相互作用来稳定其分散体。这种新效应本质上与众所周知的静电相互作用的盐屏蔽相反。在这里，我们表明小分子对纳米颗粒的稳定作用是一种与颗粒的疏水含量及其疏水吸引力强度密切相关的现象。我们比较了脯氨酸对涂有11-巯基十一烷磺酸盐（MUS）的金纳米颗粒在不同百分比的疏水配体辛硫醇（OT）存在下的影响。我们表明，OT的百分比越高，脯氨酸的稳定作用就越大。我们还比较了脯氨酸对纳米颗粒水分散体和重水分散体的影响。在后者中，疏水效应起更大的作用。我们发现，在重水中，脯氨酸的稳定作用更大。我们还比较了脯氨酸对经过退火处理（已知该处理会使颗粒更亲水）前后的相同MUS:OT金纳米颗粒的影响。脯氨酸对退火前的颗粒更有效。最后，我们研究了脯氨酸对非聚集性全MUS纳米颗粒的影响。我们发现这些颗粒的脯氨酸稳定作用主要是由于长程吸引系数的降低。总体而言，我们表明随着纳米颗粒之间疏水吸引力的增加，脯氨酸能更有效地稳定纳米颗粒分散体。
