基于离心加速耗散作用的纳米金三角片高效分离方法研究

纳米金三角片由于制备和纯化困难,获得较纯、较好形貌的产物一直是个挑战。本文提出利用离心加速的耗散作用,采用十六烷基三甲基氯化铵(CTAC)作为絮凝剂,对纳米金三角片粗产物进行纯化,从而快速获得尺寸形貌均一且顶角保持尖锐的不同尺寸的三角形金纳米颗粒。通过紫外可见分光光度计对比了用不同浓度絮凝剂获得的胶体上清液与沉淀的颜色以及消光光谱,从而确定分离不同尺寸的金三角纳米颗粒所需的最佳絮凝剂浓度。通过透射电子显微镜(TEM)对比纯化前后颗粒形貌的变化,发现已有的静置纯化方法存在较大局限性,即耗时较长且对颗粒的形貌有明显影响;而辅助以离心加速的分离方法,不仅可实现对不同尺寸纳米金三角片的快速高效分离,且有效减小了纯化过程中纳米颗粒的尖端损失。特别是对小尺寸(边长小于50 nm)的三角纳米颗粒,经离心加速的耗散力诱导的凝聚作用分离所得的颗粒,其尖端仍能保持尖锐。此方法简便高效地实现了纳米金三角片的分离,并有望推广到其它成分、非球形、低对称性形貌的纳米颗粒的纯化。

Research on High Efficient Separation of Gold Nanotriangles Based on Centrifuge accelerated Depletion Effect

Hindered by the difficulties in preparation and purification,it is always a challenge to obtain the gold nanotriangles(AuNTs) products with purer and better morphology.In this paper,a method was systematically proposed for the rapid fabrication of triangular gold nanoparticles with various sizes,single morphology and less rounded corners by centrifuge accelerated depletion effect using cetyltrimethylammonium chloride(CTAC) as flocculant.The optimum concentrations of flocculant for different sizes of gold nanotriangles were found by using UV-Vis spectrophotometer to compare the colors and the extinction spectra of supernatant and redispersed precipitate colloids obtained with different concentrations of flocculant.By comparing the morphology variations of the nanoparticles before and after purification with transmission electron microscope(TEM),the limitations for the existing purification method through natural precipitation overnight were found,which took a long time and had a significant impact on the morphology of the particles.Results showed that the method could not only achieve a rapid and efficient purification toward the gold triangular nanoparticles with different sizes,but also effectively reduce the tip loss of nanoparticles in the purification process.Especially for the triangular nanoparticles with small sizes containing side length less than 50 nm,the tips of particles purified by centrifuge accelerated depletion induced coagulation could still maintain their sharpness.This method is simple and efficient for the separation of triangular gold nanoparticles.And it is expected to be extended to the purification of nanoparticles of other components,non spherical and low symmetry shapes.