Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA.
Langmuir. 2012 Dec 11;28(49):16751-60. doi: 10.1021/la301249a. Epub 2012 Nov 27.
We report that poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) copolymers that bear multiple thiol groups on the polymer backbone are exceptional ligands for gold nanoparticles (AuNPs). In general, these graft copolymer ligands stabilize AuNPs against environments that would ordinarily lead to particle aggregation. To characterize the effect of copolymer structure on AuNP stability, we synthesized thiolated PLL-g-PEGs (PLL-g-[PEG:SH]) with different backbone lengths, PEG grafting densities, and number of thiols per polymer chain. AuNPs were then combined with these polymer ligands, and the stabilities of the resulting AuNP@PLL-g-[PEG:SH] particles against high temperature, oxidants, and competing thiol ligands were characterized using dynamic light scattering, visible absorption spectroscopy, and fluorescence spectrophotometry. Our observations indicate that thiolated PLL-g-PEG ligands combine thermodynamic stabilization via multiple Au-S bonds and steric stabilization by PEG grafts, and the best graft copolymer ligands balance these two effects. We hope that this new ligand system enables AuNPs to be applied to biotechnological applications that require harsh experimental conditions.
我们报告称，带有多个巯基的聚（L-赖氨酸）-接枝-聚（乙二醇）（PLL-g-PEG）共聚物是金纳米粒子（AuNP）的特殊配体。通常情况下，这些接枝共聚物配体可以稳定 AuNP，使其免受通常会导致颗粒聚集的环境影响。为了表征共聚物结构对 AuNP 稳定性的影响，我们合成了具有不同主链长度、PEG 接枝密度和每个聚合物链上巯基数目的巯基化 PLL-g-PEG（PLL-g-[PEG:SH]）。然后将 AuNP 与这些聚合物配体结合，并使用动态光散射、可见吸收光谱和荧光分光光度法来表征所得 AuNP@PLL-g-[PEG:SH]颗粒在高温、氧化剂和竞争巯基配体下的稳定性。我们的观察表明，巯基化 PLL-g-PEG 配体通过多个 Au-S 键和 PEG 接枝的空间位阻稳定化来实现热力学稳定化，而最佳的接枝共聚物配体平衡了这两种效应。我们希望这个新的配体系统能够使 AuNP 应用于需要苛刻实验条件的生物技术应用。
