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Interactions and Attachment Pathways between Functionalized Gold Nanorods

TitleInteractions and Attachment Pathways between Functionalized Gold Nanorods
Publication TypeJournal Article
Year of Publication2017
AuthorsTan, Shu Fen, Anand Utkarsh, and Mirsaidov Utkur
JournalACS Nano
Date Published02/2017
Keywordsau nanorods, dynamics, growth, in situ TEM, inorganic nanoparticles, intermolecular forces, linker-mediated assembly, liquid, nanocrystals, nanodroplet, nanorods, python, self-assembly, side-by-side, transmission electron-microscopy

Nanoparticle (NP) self-assembly has been recognized as an important technological process for forming ordered nanostructures. However, the detailed dynamics of the assembly processes remain poorly understood. Using in situ liquid cell transmission electron microscopy, we describe the assembly modes of gold (Au) nanorods (NRs) in solution mediated by hydrogen bonding between NR-bound cysteamine linker molecules. Our observations reveal that by tuning the linker concentration, two different NR assembly modes can be achieved. These assembly modes proceed via the (1) end-to-end and (2) side-to side attachment of NRs at low and high linker concentrations in solution, respectively. In addition, our time-resolved observations reveal that the side-to-side NR assemblies can occur through two different pathways: (i) prealigned attachment, where two Au NRs prealign to be parallel prior to assembly, and postattachment alignment, where two Au NRs first undergo end-to-end attachment and pivot around the attachment point to form the side-to-side assembly. We attributed the observed assembly modes to the distribution of linkers on the NR surfaces and the electrostatic interactions between the NRs. The intermediate steps in the assembly reported here reveal how the shape and surface functionalities of NPs drive their self-assembly, which is important for the rational design of hierarchical nanostructures.


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