Investigations of the mechanism of gold nanoparticle stability and surface functionalization in capillary electrophoresis.
Investigations of the mechanism of gold nanoparticle stability and surface functionalization in capillary electrophoresis.
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DOI：
10.1021/nn8005619
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发表时间：
2009-02-24
期刊：
影响因子：
17.1
通讯作者：
Haes, Amanda J.
中科院分区：
文献类型：
--
作者：
Ivanov, Michael R.;Bednar, Heidi R.;Haes, Amanda J.
关键词：
钴功能化的金纳米粒子影响毛细管电泳分离的神经递质的浓度和表面化学依赖性的方式。金纳米粒子与主要共价官能化的羧酸（Au@COOH）或胺（Au@NH2）的表面基团，其特征在于使用消光光谱，透射电子显微镜，和zeta电位测量。纳米粒子及其表面化学的存在下的影响进行了研究，并发现至少有三个纳米粒子的具体机制，以影响分离。首先，纳米颗粒-纳米颗粒相互作用的程度使用称为临界纳米颗粒浓度（CNC）的新参数来量化。CNC定义为在特定缓冲液条件下诱导主要纳米颗粒聚集的纳米颗粒的最低浓度，并使用双波长光电二极管阵列检测来测定。一旦超过CNC，则不再观察到可再现的分离。其次，纳米颗粒-分析物相互作用由静电相互作用决定，静电相互作用取决于分析物的pKa和纳米颗粒的表面电荷。最后，纳米颗粒-毛细管相互作用以表面化学依赖的方式发生。运行缓冲液的粘度受到纳米颗粒稳态伪固定相沿毛细管壁沿着形成的影响。尽管缓冲液粘度的差异导致神经递质迁移率的变化，电渗流没有显着变化。由于这三种纳米颗粒特异性相互作用，Au@NH2纳米颗粒增加了神经递质的迁移率，而对于Au@COOH纳米颗粒则观察到较小的相反效应。了解纳米粒子在电场存在下的行为将对分离科学产生重大影响，其中纳米粒子可以用于提高目标分子的迁移率或检测灵敏度。
Covalently functionalized gold nanoparticles influence capillary electrophoresis separations of neurotransmitters in a concentration and surface chemistry–dependent manner. Gold nanoparticles with either primarily covalently functionalized carboxylic acid (Au@COOH) or amine (Au@NH2) surface groups are characterized using extinction spectroscopy, transmission electron microscopy, and zeta potential measurements. The impact the presence of nanoparticles and their surface chemistry is investigated, and at least three nanoparticle-specific mechanisms are found to effect separations. First, the degree of nanoparticle-nanoparticle interactions is quantified using a new parameter termed the critical nanoparticle concentration (CNC). CNC is defined as the lowest concentration of nanoparticles that induces predominant nanoparticle aggregation under specific buffer conditions and is determined using dual-wavelength photodiode array detection. Once the CNC has been exceeded, reproducible separations are no longer observed. Second, nanoparticle-analyte interactions are dictated by electrostatic interactions which depend on the pKa of the analyte and surface charge of the nanoparticle. Finally, nanoparticle-capillary interactions occur in a surface chemistry dependent manner. Run buffer viscosity is influenced by the formation of a nanoparticle steady-state pseudo-stationary phase along the capillary wall. Despite differences in buffer viscosity leading to changes in neurotransmitter mobilities, no significant changes in electroosmotic flow were observed. As a result of these three nanoparticle-specific interactions, Au@NH2 nanoparticles increase the mobility of the neurotransmitters while a smaller opposite effect is observed for Au@COOH nanoparticles. Understanding nanoparticle behavior in the presence of an electric field will have significant impacts in separation science where nanoparticles can serve to improve either the mobility or detection sensitivity of target molecules.
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