标题： 金纳米颗粒悬浮液的离子特异性稳定性 显示英文标题

标题： Ion-specific Stability of Gold Nanoparticle Suspensions

摘要： 金纳米颗粒（AuNPs）由于其多方面的应用和生物相容性，在基础研究和开发中起着重要作用。 本研究探讨了在不同盐浓度（10 mM至100 mM）下，向三种AuNP悬浮液中添加各种钠盐沿著名的Hofmeister系列（NaF、NaCl、NaBr、 NaI、NaSCN）后的老化现象。 AuNP类型在尺寸（直径5 nm与11 nm）和封端类型（物理吸附的柠檬酸与共价结合的巯基丙酸（MPA））上有所不同。 我们通过光学方法（吸收光谱、摄影）和电子显微镜监测AuNPs的聚集和悬浮液的稳定性。 盐浓度的范围很大，导致胶体稳定性的多样性，例如从稳定的悬浮液到快速失稳并沉降。 在中间和高盐浓度下，出现强离子特异性效应，这些效应相对于Hofmeister系列不是单调的。 特别是，增溶盐NaI和NaSCN以非常不同的方式显著改变吸收光谱。 NaI将AuNPs融合在一起，影响主要吸收，而NaSCN在聚集过程中比其余的钠卤化物更强烈地保持AuNPs结构，导致二次吸收峰。 尽管减小AuNPs的尺寸会导致更稳定的悬浮液，但由于总可用表面积的增加，离子特异性效应更加明显。 即使共价结合的MPA封端也无法防止NaI引起的粒子融合，尽管它延缓了这一过程。 尽管离子对胶体分散体系稳定性的影响之间存在复杂的相互作用，但本研究通过吸附在界面和AuNPs桥接，从静电屏蔽到离子与AuNPs封端剂之间的竞争，解开了不同的影响。 显示英文摘要

摘要： Gold nanoparticles (AuNPs) play an important role in fundamental research and development due to their versatile applications and biocompatibility. This study addresses the aging of three AuNP suspensions after the addition of various sodium salts along the well-known Hofmeister series (NaF, NaCl, NaBr, NaI, NaSCN) at different salt concentrations between 10 mM and 100 mM. The AuNP types differ in size (5 nm vs. 11 nm in diameter) and the capping type (physisorbed citrate vs. covalently bound mercaptopropionic acid (MPA)). We monitor the aggregation of the AuNPs and the suspension stability optically (absorption spectroscopy, photography) and by electron microscopy. The large range of salt concentrations results in a large variety of colloidal stability, e.g., from stable suspensions to fast destabilization followed by sedimentation. At intermediate and high salt concentration strong ion-specific effects emerge that are non-monotonous with respect to the Hofmeister series. In particular, the chaotropic salts, NaI and NaSCN, strongly alter the absorption spectra in very different ways. NaI fuses AuNPs together influencing the primary absorption, while NaSCN retains AuNP structure during aggregation much stronger than the remaining sodium halides, resulting in a secondary absorption peak. Although decreasing the size of AuNPs leads to more stable suspensions, the ion specific effects are even more pronounced due to the increase in total available surface. Even the covalently bound MPA capping is not able to stabilize AuNPs against particle fusion by NaI, although it delays the process. Despite the complex interplay between different effects of ions on the stability of colloidal dispersions, this study disentangles the different effects from electrostatic screening, via adsorption at the interface and bridging of AuNPs, to the competition between ions and the capping agent of the AuNPs.