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Arciniegas MP, Castelli A, Brescia R, Serantes D, Ruta S, Hovorka O, Satoh A, Chantrell R, Pellegrino T. Unveiling the Dynamical Assembly of Magnetic Nanocrystal Zig-Zag Chains via In Situ TEM Imaging in Liquid. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e1907419. [PMID: 32459051 DOI: 10.1002/smll.201907419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/23/2020] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
The controlled assembly of colloidal magnetic nanocrystals is key to many applications such as nanoelectronics, storage memory devices, and nanomedicine. Here, the motion and ordering of ferrimagnetic nanocubes in water via liquid-cell transmission electron microscopy is directly imaged in situ. Through the experimental analysis, combined with molecular dynamics simulations and theoretical considerations, it is shown that the presence of highly competitive interactions leads to the formation of stable monomers and dimers, acting as nuclei, followed by a dynamic growth of zig-zag chain-like assemblies. It is demonstrated that such arrays can be explained by first, a maximization of short-range electrostatic interactions, which at a later stage become surpassed by magnetic forces acting through the easy magnetic axes of the nanocubes, causing their tilted orientation within the arrays. Moreover, in the confined volume of liquid in the experiments, interactions of the nanocube surfaces with the cell membranes, when irradiated at relatively low electron dose, slow down the kinetics of their self-assembly, facilitating the identification of different stages in the process. The study provides crucial insights for the formation of unconventional linear arrays made of ferrimagnetic nanocubes that are essential for their further exploitation in, for example, magnetic hyperthermia, magneto-transport devices, and nanotheranostic tools.
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Affiliation(s)
| | - Andrea Castelli
- Istituto Italiano di Tecnologia, Via Morego 30, Genova, 16163, Italy
| | - Rosaria Brescia
- Istituto Italiano di Tecnologia, Via Morego 30, Genova, 16163, Italy
| | - David Serantes
- Applied Physics Department and Instituto de Investigacións Tecnolóxicas, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain
| | - Sergiu Ruta
- Department of Physics, University of York, York, YO10 5DD, UK
| | - Ondrej Hovorka
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO16 7QF, UK
| | - Akira Satoh
- Faculty of System Science and Technology, Akita Prefecture University, Yurihonjo, 015-0055, Japan
| | - Roy Chantrell
- Department of Physics, University of York, York, YO10 5DD, UK
| | - Teresa Pellegrino
- Istituto Italiano di Tecnologia, Via Morego 30, Genova, 16163, Italy
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