Chemical Engineering Department, University of Washington, Seattle, Washington 98195, USA.
Langmuir. 2012 Sep 18;28(37):13157-65. doi: 10.1021/la302130d. Epub 2012 Sep 4.
The surface concentration and conformation of thiol-terminated poly(ethylene glycol) (PEG) on gold nanoparticles are studied before and after coadsorption of alkane-thiols. Thermogravimetric analysis (TGA) indicates alkane-thiol ligands will competitively adsorb on gold surfaces of nanoparticles and that the extent of PEG-thiol replacement depends on the specific length of the alkane-thiol molecule. The conformation of the polymer is also affected by the length and packing density of the alkane-thiol. Dynamic light scattering (DLS) shows that the hydrodynamic size of coated particles has an intermediate maximum for the adsorption of octane-thiol, which also forms the most densely packed alkane-thiol monolayers. These two factors greatly impact the formation of clusters by nanoparticle surfactants. Small angle X-ray scattering (SAXS) shows that the largest clusters are formed when particles have a low PEG-thiol surface concentration and an extended PEG conformation.
巯基封端的聚乙二醇（PEG）在金纳米粒子表面的浓度和构象在烷硫醇共吸附前后进行了研究。热重分析（TGA）表明烷硫醇配体将在纳米粒子的金表面上竞争吸附，并且 PEG-硫醇取代的程度取决于烷硫醇分子的特定长度。聚合物的构象也受到烷硫醇的长度和堆积密度的影响。动态光散射（DLS）表明，对于辛烷硫醇的吸附，涂层颗粒的水动力尺寸具有中间最大值，其也形成最密集的烷硫醇单层。这两个因素极大地影响了纳米粒子表面活性剂形成的聚集体。小角 X 射线散射（SAXS）表明，当颗粒具有低的 PEG-硫醇表面浓度和扩展的 PEG 构象时，形成最大的聚集体。
