Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Nano Lett. 2013 Feb 13;13(2):423-9. doi: 10.1021/nl303576q. Epub 2013 Jan 11.
From their realization just over a decade ago, nanopores in silicon nitride membranes have allowed numerous transport-based single-molecule measurements. Here we report the use of these nanopores as subzeptoliter mixing volumes for the controlled synthesis of metal nanoparticles. Particle synthesis is controlled and monitored through an electric field applied across the nanopore membrane, which is positioned so as to separate electrolyte solutions of a metal precursor and a reducing agent. When the electric field drives reactive ions to the nanopore, a characteristic drop in the ion current is observed, indicating the formation of a nanoparticle inside the nanopore. While traditional chemical synthesis relies on temperature and timing to monitor particle growth, here we observe it in real time by monitoring electrical current. We describe the dynamics of gold particle formation in sub-10 nm diameter silicon nitride pores and the effects of salt concentration and additives on the particle's shape and size. The current versus time signal during particle formation in the nanopore is in excellent agreement with the Richards growth curve, indicating an access-limited growth mechanism.
从十多年前的发现开始，氮化硅膜中的纳米孔就已经允许进行许多基于传输的单分子测量。在这里，我们报告了将这些纳米孔用作亚zeptoliter 混合体积，以控制金属纳米粒子的合成。通过施加在纳米孔膜上的电场来控制和监测颗粒的合成，该电场的位置使得金属前体和还原剂的电解质溶液得以分离。当电场将反应离子驱动到纳米孔时，观察到离子电流的特征下降，表明在纳米孔内形成了纳米颗粒。虽然传统的化学合成依赖于温度和时间来监测颗粒的生长，但在这里，我们通过监测电流来实时观察它。我们描述了亚 10nm 直径氮化硅孔中金颗粒形成的动力学以及盐浓度和添加剂对颗粒形状和尺寸的影响。在纳米孔中形成颗粒期间的电流与时间信号与 Richards 生长曲线非常吻合，表明存在受限进入的生长机制。
