不同抗衡离子大小的巯基十一烷酸包覆金纳米颗粒的稳定性与静电学
Stability and electrostatics of mercaptoundecanoic acid-capped gold nanoparticles with varying counterion size.
作者信息
Laaksonen Timo, Ahonen Päivi, Johans Christoffer, Kontturi Kyösti
机构信息
Laboratory of Physical Chemistry and Electrochemistry Helsinki University of Technology, P.O. Box 6100, 02015 HUT, Finland.
出版信息
Chemphyschem. 2006 Oct 13;7(10):2143-9. doi: 10.1002/cphc.200600307.
The solubility of charged nanoparticles is critically dependent on pH. However, the concentration range available with bases such as NaOH is quite narrow, since the particles precipitate due to compression of the electric double layer when the ionic strength is increased. The stability of mercaptoundecanoic acid-capped Au nanoparticles is studied at a set pH using the hydroxide as base and different cations of various sizes. The counterions used are sodium (Na(+)), tetramethylammonium (TMA(+)), tetraethylammonium (TEA(+)), and tetrabutylammonium (TBA(+)). The particles precipitate in the 70-90 mM range with Na(+) as the counterion, but with quaternary ammonium hydroxides the particles are stable even in concentrations exceeding 1 M. The change in solubility is linked to a strongly adsorbed layer on the surface of the ligand shell of the nanoparticles. The increased concentration range obtained with TEAOH is further used to facilitate thiol exchange which occurs at a greater extent than would be achieved in NaOH solution.
带电纳米颗粒的溶解度严重依赖于pH值。然而，像NaOH这样的碱所能达到的浓度范围相当窄，因为当离子强度增加时，颗粒会因双电层压缩而沉淀。使用氢氧化物作为碱以及不同大小的各种阳离子，在设定的pH值下研究了巯基十一烷酸包覆的金纳米颗粒的稳定性。所使用的抗衡离子是钠（Na(+)）、四甲基铵（TMA(+)）、四乙基铵（TEA(+)）和四丁基铵（TBA(+)）。以Na(+)作为抗衡离子时，颗粒在70 - 90 mM范围内沉淀，但使用季铵氢氧化物时，即使浓度超过1 M，颗粒仍保持稳定。溶解度的变化与纳米颗粒配体壳表面的强吸附层有关。用TEAOH获得的浓度范围增加，进一步用于促进硫醇交换，硫醇交换发生的程度比在NaOH溶液中更大。
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