TY - JOUR
T1 - Unveiling the Dynamical Assembly of Magnetic Nanocrystal Zig-Zag Chains via In Situ TEM Imaging in Liquid
AU - Arciniegas, Milena P.
AU - Castelli, Andrea
AU - Brescia, Rosaria
AU - Serantes, David
AU - Ruta, Sergiu
AU - Hovorka, Ondrej
AU - Satoh, Akira
AU - Chantrell, Roy
AU - Pellegrino, Teresa
N1 - © 2020 The Authors
PY - 2020/6/25
Y1 - 2020/6/25
N2 - 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.
AB - 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.
KW - anisotropic nanocrystals
KW - assembly
KW - in situ liquid TEM
KW - magnetic nanocubes
UR - http://www.scopus.com/inward/record.url?scp=85085590389&partnerID=8YFLogxK
U2 - 10.1002/smll.201907419
DO - 10.1002/smll.201907419
M3 - Article
AN - SCOPUS:85085590389
SN - 1613-6810
VL - 16
JO - Small
JF - Small
IS - 25
M1 - e1907419
ER -
