A Generalized Mechanism for Ligand-Induced Dipolar Assembly of Plasmonic Gold Nanoparticle Chain Networks
A Generalized Mechanism for Ligand-Induced Dipolar Assembly of Plasmonic Gold Nanoparticle Chain Networks
复制标题
DOI：
10.1002/adfm.201001754
复制
发表时间：
2011-03-08
影响因子：
19
通讯作者：
Mann, Stephen
中科院分区：
文献类型：
--
作者：
Li, Mei;Johnson, Sara;Mann, Stephen
研究了金纳米颗粒链组装的机制，该机制与通过巯基乙醇对表面吸附的柠檬酸根离子进行部分配体交换而产生电偶极-偶极相互作用的诱导有关。分别使用紫外可见分光光度法和电子显微镜来确定 5 至 50 摄氏度之间与一维纳米颗粒超结构形成相关的动力学和时间依赖性结构变化。结果表明，等离子体纳米颗粒网络的组装对温度变化极其敏感。纳米颗粒链的形成在 25-30 摄氏度下进行优化，并遵循一级动力学，随着初始纳米颗粒浓度的提高，反应速率不断增加。低于 25 摄氏度时，等离激元纳米颗粒网络会产生，但速率会显着降低。相比之下，在 30 摄氏度以上，短链网络会迅速形成，但该过程会被限制链增长并产生小碎片和孤立的金纳米颗粒的二级机制所取代。组装行为的变化归因于与金纳米颗粒表面相关的巯基乙醇分子的温度依赖性有序和无序。研究结果为基于配体诱导的电偶极相互作用的金属纳米颗粒自组装提供了通用机制模型，该相互作用总体上处于热力学控制之下，但对动力学方面敏感。还表明，可以进一步利用偶极机制引入更大的纳米粒子作为拓扑掺杂剂，这些掺杂剂专门存在于自组装一维纳米粒子网络的分支点或末端。
The mechanism of gold nanoparticle chain assembly associated with the induction of electric dipole-dipole interactions arising from the partial ligand exchange of surface-adsorbed citrate ions by mercaptoethanol is investigated. UV-vis spectrophotometry and electron microscopy are used, respectively, to determine the kinetics and time-dependent structural changes associated with formation of the 1D nanoparticle superstructures between 5 and 50 degrees C. The results indicate that assembly of the plasmonic nanoparticle networks is extremely sensitive to changes in temperature. Formation of the nanoparticle chains is optimized at 25-30 degrees C and follows first order kinetics with increasing reaction rates attained for higher initial nanoparticle concentrations. Below 25 degrees C, plasmonic nanoparticle networks are produced but at a considerably reduced rate. In contrast, above 30 degrees C, short-chain networks form rapidly but the process is superseded by a secondary mechanism that limits chain growth and produces small fragments and isolated Au nanoparticles. The changes in assembly behavior are attributed to the temperature-dependent ordering and disordering of mercaptoethanol molecules associated with the gold nanoparticle surface. The results provide a general mechanistic model for the self-assembly of metallic nanoparticles based on ligand-induced electric dipolar interactions, which are globally under thermodynamic control but sensitive to kinetic aspects. It is also shown that the dipolar mechanism can be further exploited to introduce larger nanoparticles as topological dopants that reside specifically at branching points or termini in the self-assembled 1D nanoparticle networks.