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Chen Y, El-Ghazaly A. Self-Assembly of Magnetic Nanochains in an Intrinsic Magnetic Dipole Force-Dominated Regime. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2205079. [PMID: 36504439 DOI: 10.1002/smll.202205079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 11/23/2022] [Indexed: 06/17/2023]
Abstract
Magnetic nanoparticle chains offer the anisotropic magnetic properties that are often desirable for micro- and nanoscale systems; however, to date, large-scale fabrication of these nanochains is limited by the need for an external magnetic field during the synthesis. In this work, the unique self-assembly of nanoparticles into chains as a result of their intrinsic dipolar interactions only is examined. In particular, it is shown that in a high concentration reaction regime, the dipole-dipole coupling between two neighboring magnetic iron cobalt (FeCo) nanocubes, was significantly strengthened due to small separation between particles and their high magnetic moments. This dipole-dipole interaction enables the independent alignment and synthesis of magnetic FeCo nanochains without the assistance of any templates, surfactants, or even external magnetic field. Furthermore, the precursor concentration ([M] = 0.016, 0.021, 0.032, 0.048, 0.064, and 0.096 m) that dictates the degree of dipole interaction is examined-a property dependent on particle size and inter-particle distance. By varying the spinner speed, it is demonstrated that the balance between magnetic dipole coupling and fluid dynamics can be used to understand the self-assembly process and control the final structural topology from that of dimers to linear chains (with aspect ratio >10:1) and even to branched networks. Simulations unveil the magnetic and fluid force landscapes that determine the individual nanoparticle interactions and provide a general insight into predicting the resulting nanochain morphology. This work uncovers the enormous potential of an intrinsic magnetic dipole-induced assembly, which is expected to open new doors for efficient fabrication of 1D magnetic materials, and the potential for more complex assemblies with further studies.
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Affiliation(s)
- Yulan Chen
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Amal El-Ghazaly
- School of Electrical and Computer Engineering, Cornell University, Ithaca, NY, 14853, USA
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Particle-based hematite crystallization is invariant to initial particle morphology. Proc Natl Acad Sci U S A 2022; 119:e2112679119. [PMID: 35275793 PMCID: PMC8931245 DOI: 10.1073/pnas.2112679119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Many crystallization processes occurring in nature produce highly ordered hierarchical architectures. Their formation cannot be explained using classical models of monomer-by-monomer growth. One of the possible pathways involves crystallization through the attachment of oriented nanocrystals. Thus, it requires detailed understanding of the mechanism of particle dynamics that leads to their precise crystallographic alignment along specific faces. In this study, we discover a particle-morphology–independent oriented attachment mechanism for hematite nanocrystals. Independent of crystal morphology, particles always align along the [001] direction driven by aligning interactions between (001) faces and repulsive interactions between other pairs of hematite faces. These results highlight that strong face specificity along one crystallographic direction can render oriented attachment to be independent of initial particle morphology. Understanding the mechanism of particle-based crystallization is a formidable problem due to the complexity of macroscopic and interfacial forces driving particle dynamics. The oriented attachment (OA) pathway presents a particularly challenging phenomenon because it occurs only under select conditions and involves a precise crystallographic alignment of particle faces often from distances of several nanometers. Despite the progress made in recent years in understanding the driving forces for particle face selectivity and alignment, questions about the competition between ion-by-ion crystallization, near-surface nucleation, and OA remain. This study examines hydrothermal conditions leading to apparent OA for hematite using three initial particle morphologies with various exposed faces. All three particle types formed single-crystal or twinned one-dimensional (1D) chain-like structures along the [001] direction driven by the attractive interactions between (001) faces and repulsive interactions between other pairs of hematite faces. Moreover, simulations of the potential of mean force for iron species and scanning transmission electron microscopy (S/TEM) imaging confirm that the formation of 1D chains is a result of the attachment of independently nucleated particles and does not follow the near-surface nucleation or ion-by-ion crystallization pathways. These results highlight that strong face specificity along one crystallographic direction can render OA to be independent of initial particle morphology.
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Mahmood AU, Yingling YG. All-Atom Simulation Method for Zeeman Alignment and Dipolar Assembly of Magnetic Nanoparticles. J Chem Theory Comput 2022; 18:3122-3135. [PMID: 35271259 DOI: 10.1021/acs.jctc.1c01253] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Magnetic nanoparticles (MNPs) can organize into novel structures in solutions with excellent order and unique geometries. However, studies of the self-assembly of smaller MNPs are challenging due to a complicated interplay between external magnetic fields and van der Waals, electrostatic, dipolar, steric, and hydrodynamic interactions. Here, we present a novel all-atom molecular dynamics simulation method to enable detailed studies of the dynamics, self-assembly, structure, and properties of MNPs as a function of core sizes and shapes, ligand chemistry, solvent properties, and external field. We demonstrate the use and effectiveness of the model by simulating the self-assembly of oleic acid ligand-functionalized magnetite (Fe3O4) nanoparticles, with spherical and cubic shapes, into rings, lines, chains, and clusters under a uniform external magnetic field. We found that the long-range electrostatic interactions can favor the formation of a chain over a ring, the ligands promote MNP cluster growth, and the solvent can reduce the rotational diffusion of the MNPs. The algorithm has been parallelized to take advantage of multiple processors of a modern computer and can be used as a plugin for the popular simulation software LAMMPS to study the behavior of small MNPs and gain insights into the physics and chemistry of different magnetic assembly processes with atomistic details.
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Affiliation(s)
- Akhlak U Mahmood
- Department of Materials Science and Engineering, NC State University, Raleigh, North Carolina 27695, United States
| | - Yaroslava G Yingling
- Department of Materials Science and Engineering, NC State University, Raleigh, North Carolina 27695, United States
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Shen Y, Zhang W, Li G, Ning P, Li Z, Chen H, Wei X, Pan X, Qin Y, He B, Yu Z, Cheng Y. Adaptive Control of Nanomotor Swarms for Magnetic-Field-Programmed Cancer Cell Destruction. ACS NANO 2021; 15:20020-20031. [PMID: 34807565 DOI: 10.1021/acsnano.1c07615] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Magnetic nanomotors (MNMs), powered by a magnetic field, are ideal platforms to achieve versatile biomedical applications in a collective and spatiotemporal fashion. Although the programmable swarm of MNMs that mimics the highly ordered behaviors of living creatures has been extensively studied at the microscale, it is of vital importance to manipulate MNM swarms at the nanoscale for on-demand tasks at the cellular level. In this work, a Cy5-tagged caspase-3-specific peptide-modified MNM is designed, and the adaptive control behaviors of MNM swarms are revealed in lysosomes to induce the cancer cell apoptosis under a rotating magnetic field (RMF). A magneto-programmed vortex is predicted to occur with swarms under RMF by the finite element method model and verified in vitro. According to the dynamic model and numerical simulation, the critical rotating frequency under which MNMs are out of step is strongly correlated to their assembling and swarming properties. The adaptivity of swarms maximizes the synchronous rotation to achieve an optimal energy conversion rate. The frequency-adapted controllability of MNM swarms for cancer cell apoptosis is observed in real time in vitro and in vivo. This work provides theoretical and experimental insights to adaptively control MNM swarms for cancer treatment.
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Affiliation(s)
- Yajing Shen
- Shanghai East Hospital, School of Medicine, Tongji University, 1800 Yuntai Road, Shanghai 200120, China
| | - Wei Zhang
- College of Electronics and Information Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804, China
| | - Gang Li
- College of Electronics and Information Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804, China
| | - Peng Ning
- Shanghai East Hospital, School of Medicine, Tongji University, 1800 Yuntai Road, Shanghai 200120, China
| | - Zhenguang Li
- Shanghai East Hospital, School of Medicine, Tongji University, 1800 Yuntai Road, Shanghai 200120, China
| | - Haotian Chen
- Shanghai East Hospital, School of Medicine, Tongji University, 1800 Yuntai Road, Shanghai 200120, China
| | - Xueyan Wei
- Shanghai East Hospital, School of Medicine, Tongji University, 1800 Yuntai Road, Shanghai 200120, China
| | - Xin Pan
- Shanghai East Hospital, School of Life Sciences and Technology, Tongji University, 1800 Yuntai Road, Shanghai 200120, China
| | - Yao Qin
- Shanghai East Hospital, School of Medicine, Tongji University, 1800 Yuntai Road, Shanghai 200120, China
| | - Bin He
- College of Electronics and Information Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804, China
| | - Zuoren Yu
- Shanghai East Hospital, School of Medicine, Tongji University, 1800 Yuntai Road, Shanghai 200120, China
| | - Yu Cheng
- Shanghai East Hospital, School of Medicine, Tongji University, 1800 Yuntai Road, Shanghai 200120, China
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