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Hua E, Gao J, Xu Y, Matsuo M, Nakata S. Self-propelled motion controlled by ionic liquids. Phys Chem Chem Phys 2024; 26:8488-8493. [PMID: 38411193 DOI: 10.1039/d3cp05630a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
We studied the self-propulsion of a camphor disk floating on a water surface using two types of ionic liquids (hexylammonium-trifluoroacetate (HHexam-TFA) and hexylethylenediaminium-trifluoroacetate (HHexen-TFA)). Bifurcation between continuous, oscillatory, and no motion was observed depending on the concentration of the ionic liquid. The bifurcation concentration between oscillatory and no motion for HHexam-TFA was lower than that for HHexen-TFA. The different bifurcation concentrations are discussed in relation to the surface tension and Fourier transform infrared spectra of the mixtures of camphor and ionic liquids. These results suggest that the interaction between the ionic liquid molecules at the air/water interface is weakened by the addition of camphor molecules and the features of self-propulsion vary due to the change in the driving force.
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Affiliation(s)
- Er Hua
- Chemical Science and Engineering College, Key Laboratory of Chemical Technology of State Ethnic Affairs Commission, North Minzu University, 204 Wenchang North Street, Xixia District, Yinchuan City, Ningxia 750021, China.
| | - Jun Gao
- Chemical Science and Engineering College, Key Laboratory of Chemical Technology of State Ethnic Affairs Commission, North Minzu University, 204 Wenchang North Street, Xixia District, Yinchuan City, Ningxia 750021, China.
| | - Yu Xu
- School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Chang'an Campus 1 Dongxiang Road, Chang'an District, Xi'an Shaanxi 710129, China
| | - Muneyuki Matsuo
- Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
- Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
| | - Satoshi Nakata
- Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
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2
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Khatri N, Kapral R. Clustering of chemically propelled nanomotors in chemically active environments. CHAOS (WOODBURY, N.Y.) 2024; 34:033103. [PMID: 38427933 DOI: 10.1063/5.0188624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 02/05/2024] [Indexed: 03/03/2024]
Abstract
Synthetic nanomotors powered by chemical reactions have been designed to act as vehicles for active cargo transport, drug delivery, and a variety of other uses. Collections of such motors, acting in consort, can self-assemble to form swarms or clusters, providing opportunities for applications on various length scales. While such collective behavior has been studied when the motors move in a chemically inactive fluid environment, when the medium in which they move is a chemical network that supports complex spatial and temporal patterns, through simulation and theoretical analysis we show that collective behavior changes. Spatial patterns in the environment can guide and control motor collective states, and interactions of the motors with their environment can give rise to distinctive spatiotemporal motor patterns. The results are illustrated by studies of the motor dynamics in systems that support Turing patterns and spiral waves. This work is relevant for potential applications that involve many active nanomotors moving in complex chemical or biological environments.
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Affiliation(s)
- Narender Khatri
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Raymond Kapral
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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3
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Fujino T, Matsuo M, Pimienta V, Nakata S. Oscillatory Motion of an Organic Droplet Reflecting a Reaction Scheme. J Phys Chem Lett 2023; 14:9279-9284. [PMID: 37815116 DOI: 10.1021/acs.jpclett.3c02130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
An organic droplet containing thymol acetate (TA) floating on a sodium dodecyl sulfate aqueous phase was examined to develop a novel self-propelled object based on reaction kinetics. Two types of oscillatory motion, without back-and-forth motion (Osc I) and with back-and-forth motion (Osc II), were observed by varying the pH of the aqueous phase. The oscillation frequency reached its maximum at pH 9.6, coinciding with the occurrence of Osc II. The kinetics of the hydrolysis of TA as a reactant and the acid-base equilibrium between thymol (TOH) and the thymolate ion (TO-) as products were evaluated experimentally. The driving force of motion was discussed on the basis of the interfacial tension. The pH dependence of the oscillation frequency and the selection of Osc I or II were attributed to the equilibrium between the TOH and TO-. These results highlight the possibility of designing self-propulsion systems by considering reaction kinetics and chemical properties.
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Affiliation(s)
- Takuya Fujino
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Muneyuki Matsuo
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
| | - Véronique Pimienta
- Laboratoire des IMRCP, Université de Toulouse, CNRS UMR 5623, Université Toulouse III - Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 9, France
| | - Satoshi Nakata
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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4
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Zhang Z, Xu L, Huang J. Controlling Chemical Waves by Transforming Transient Mass Transfer. ADVANCED THEORY AND SIMULATIONS 2021. [DOI: 10.1002/adts.202100375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Zeren Zhang
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory of Micro and Nano Photonic Structures (MOE) Fudan University Shanghai 200438 China
| | - Liujun Xu
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory of Micro and Nano Photonic Structures (MOE) Fudan University Shanghai 200438 China
| | - Jiping Huang
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory of Micro and Nano Photonic Structures (MOE) Fudan University Shanghai 200438 China
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5
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Affiliation(s)
- P. Bayati
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran
| | - A. Najafi
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran
- Research Center for Basic Sciences & Modern Technologies (RBST), Institute for Advanced Studies in Basic Sciences, Zanjan, Iran
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6
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Sahoo S, Singh SP, Thakur S. Enhanced self-propulsion of a sphere-dimer in viscoelastic fluid. SOFT MATTER 2019; 15:2170-2177. [PMID: 30758376 DOI: 10.1039/c8sm02311e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Micro-swimmers often have to encounter a medium that exhibits non-Newtonian behaviour. To understand the effect of complex environments on the propulsion dynamics of swimmers, here we have investigated a self-propelled sphere-dimer in a viscoelastic medium, using a coarse-grained hybrid mesoscopic simulation technique. We have shown that a viscoelastic fluid can result in the enhancement of swimming speed, as compared to the speed in a Newtonian fluid with the same viscosity. A non-linear response in the dimer velocity is seen for higher Péclet numbers in viscoelastic fluids. With help of various dynamical quantities, we have shown that the observed non-linear response of the directed velocity is associated with the micro-structural properties of the fluid. These include the alignment of the fluid elements and the density inhomogeneity around the moving dimer. The enhancement of self-propulsion velocity has been probed in detail, and the factors affecting the propulsion are identified.
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Affiliation(s)
- Soudamini Sahoo
- Department of Physics, Indian Institute of Science Education and Research Bhopal, Bhopal, 462066, India.
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Robertson B, Huang MJ, Chen JX, Kapral R. Synthetic Nanomotors: Working Together through Chemistry. Acc Chem Res 2018; 51:2355-2364. [PMID: 30207448 DOI: 10.1021/acs.accounts.8b00239] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Active matter, some of whose constituent elements are active agents that can move autonomously, behaves very differently from matter without such agents. The active agents can self-assemble into structures with a variety of forms and dynamical properties. Swarming, where groups of living agents move cooperatively, is commonly observed in the biological realm, but it is also seen in the physical realm in systems containing small synthetic motors. The existence of diverse forms of self-assembled structures has stimulated the search for new applications that involve active matter. We consider active systems where the agents are synthetic chemically powered motors with various shapes and sizes that operate by phoretic mechanisms, especially self-diffusiophoresis. These motors are able to move autonomously in solution by consuming fuel from their environment. Chemical reactions take place on catalytic portions of the motor surface and give rise to concentration gradients that lead to directed motion. They can operate in this way only if the chemical composition of the system is maintained in a nonequilibrium state since no net fluxes are possible in a system at equilibrium. In contrast to many other active systems, chemistry plays an essential part in determining the properties of the collective dynamics and self-assembly of these chemically powered motor systems. The inhomogeneous concentration fields that result from asymmetric motor reactions are felt by other motors in the system and strongly influence how they move. This chemical coupling effect often dominates other interactions due to fluid flow fields and direct interactions among motors and determines the form that the collective dynamics takes. Since we consider small motors with micrometer and nanometer sizes, thermal fluctuations are strong and cannot be neglected. The media in which the motors operate may not be simple and may contain crowding agents or molecular filaments that influence how the motors assemble and move. The collective motion is also influenced by the chemical gradients that arise from reactions in the surrounding medium. By adopting a microscopic perspective, where the motors, fluid environment, and crowding elements are treated at the coarse-grained molecular level, all of the many-body interactions that give rise to the collective behavior naturally emerge from the molecular dynamics. Through simulations and theory, this Account describes how active matter made from chemically powered nanomotors moving in simple and more complicated media can form different dynamical structures that are strongly influenced by interactions arising from cooperative chemical reactions on the motor surfaces.
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Affiliation(s)
- Bryan Robertson
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Mu-Jie Huang
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Jiang-Xing Chen
- Department of Physics, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Raymond Kapral
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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Chen J, Chen Y, Kapral R. Chemically Propelled Motors Navigate Chemical Patterns. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2018; 5:1800028. [PMID: 30250781 PMCID: PMC6145410 DOI: 10.1002/advs.201800028] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 04/15/2018] [Indexed: 05/06/2023]
Abstract
Very small synthetic motors that use chemical reactions to drive their motion are being studied widely because of their potential applications, which often involve active transport and dynamics on nanoscales. Like biological molecular machines, they must be able to perform their tasks in complex, highly fluctuating environments that can form chemical patterns with diverse structures. Motors in such systems can actively assemble into dynamic clusters and other unique nonequilibrium states. It is shown how chemical patterns with small characteristic dimensions may be utilized to suppress rotational Brownian motions of motors and guide them to move along prescribed paths, properties that can be exploited in applications. In systems with larger pattern length scales, domains can serve as catch basins for motors through chemotactic effects. The resulting collective motor dynamics in such confining domains can be used to explore new aspects of active particle collective dynamics or promote specific types of active self-assembly. More generally, when chemically self-propelled motors operate in far-from-equilibrium active chemical media the variety of possible phenomena and the scope of their potential applications are substantially increased.
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Affiliation(s)
- Jiang‐Xing Chen
- Department of PhysicsHangzhou Dianzi UniversityHangzhou310018China
| | - Yu‐Guo Chen
- Department of PhysicsHangzhou Dianzi UniversityHangzhou310018China
| | - Raymond Kapral
- Chemical Physics Theory GroupDepartment of ChemistryUniversity of TorontoTorontoOntarioM5S 3H6Canada
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Zöttl A, Stark H. Simulating squirmers with multiparticle collision dynamics. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2018; 41:61. [PMID: 29766348 DOI: 10.1140/epje/i2018-11670-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 04/23/2018] [Indexed: 06/08/2023]
Abstract
Multiparticle collision dynamics is a modern coarse-grained simulation technique to treat the hydrodynamics of Newtonian fluids by solving the Navier-Stokes equations. Naturally, it also includes thermal noise. Initially it has been applied extensively to spherical colloids or bead-spring polymers immersed in a fluid. Here, we review and discuss the use of multiparticle collision dynamics for studying the motion of spherical model microswimmers called squirmers moving in viscous fluids.
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Affiliation(s)
- Andreas Zöttl
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, OX1 3NP, Oxford, UK.
- Institute for Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, 10623, Berlin, Germany.
| | - Holger Stark
- Institute for Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, 10623, Berlin, Germany
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10
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Taxis of Artificial Swimmers in a Spatio-Temporally Modulated Activation Medium. ENTROPY 2017. [DOI: 10.3390/e19030097] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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11
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Geiseler A, Hänggi P, Marchesoni F. Self-Polarizing Microswimmers in Active Density Waves. Sci Rep 2017; 7:41884. [PMID: 28181504 PMCID: PMC5299513 DOI: 10.1038/srep41884] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 12/30/2016] [Indexed: 11/09/2022] Open
Abstract
An artificial microswimmer drifts in response to spatio-temporal modulations of an activating suspension medium. We consider two competing mechanisms capable of influencing its tactic response: angular fluctuations, which help it explore its surroundings and thus diffuse faster toward more active regions, and self-polarization, a mechanism inherent to self-propulsion, which tends to orient the swimmer's velocity parallel or antiparallel to the local activation gradients. We investigate, both numerically and analytically, the combined action of such two mechanisms. By determining their relative magnitude, we characterize the selective transport of artificial microswimmers in inhomogeneous activating media.
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Affiliation(s)
| | - Peter Hänggi
- Institut für Physik, University of Augsburg, D-86159, Germany
- Nanosystems Initiative Munich, Schellingstraße 4, D-80799 München, Germany
- Department of Physics, National University of Singapore, 117551 Singapore, Republic of Singapore
| | - Fabio Marchesoni
- Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People’s Republic of China
- Dipartimento di Fisica, Università di Camerino, I-62032 Camerino, Italy
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12
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Zhao Z, Zhang H, Shu D, Montemagno C, Ding B, Li J, Guo P. Construction of Asymmetrical Hexameric Biomimetic Motors with Continuous Single-Directional Motion by Sequential Coordination. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:10.1002/smll.201601600. [PMID: 27709780 PMCID: PMC5217803 DOI: 10.1002/smll.201601600] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/12/2016] [Indexed: 05/21/2023]
Abstract
The significance of bionanomotors in nanotechnology is analogous to mechanical motors in daily life. Here the principle and approach for designing and constructing biomimetic nanomotors with continuous single-directional motion are reported. This bionanomotor is composed of a dodecameric protein channel, a six-pRNA ring, and an ATPase hexamer. Based on recent elucidations of the one-way revolving mechanisms of the phi29 double-stranded DNA (dsDNA) motor, various RNA and protein elements are designed and tested by single-molecule imaging and biochemical assays, with which the motor with active components has been constructed. The motor motion direction is controlled by three operation elements: (1) Asymmetrical ATPase with ATP-interacting domains for alternative DNA binding/pushing regulated by an arginine finger in a sequential action manner. The arginine finger bridges two adjacent ATPase subunits into a non-covalent dimer, resulting in an asymmetrical hexameric complex containing one dimer and four monomers. (2) The dsDNA translocation channel as a one-way valve. (3) The hexameric pRNA ring geared with left-/right-handed loops. Assessments of these constructs reveal that one inactive subunit of pRNA/ATPase is sufficient to completely block motor function (defined as K = 1), implying that these components work sequentially based on the principle of binomial distribution and Yang Hui's triangle.
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Affiliation(s)
- Zhengyi Zhao
- College of Pharmacy; College of Medicine/Department of Physiology & Cell Biology/Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Hui Zhang
- College of Pharmacy; College of Medicine/Department of Physiology & Cell Biology/Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Dan Shu
- College of Pharmacy; College of Medicine/Department of Physiology & Cell Biology/Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Carlo Montemagno
- Chemical and Materials Engineering and Ingenuity Lab, University of Alberta, Edmonton, Alberta, Canada
| | - Baoquan Ding
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Jingyuan Li
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China and Institute of High Energy Physics, Beijing, China
| | - Peixuan Guo
- College of Pharmacy; College of Medicine/Department of Physiology & Cell Biology/Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
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Geiseler A, Hänggi P, Marchesoni F, Mulhern C, Savel'ev S. Chemotaxis of artificial microswimmers in active density waves. Phys Rev E 2016; 94:012613. [PMID: 27575185 DOI: 10.1103/physreve.94.012613] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Indexed: 06/06/2023]
Abstract
Living microorganisms are capable of a tactic response to external stimuli by swimming toward or away from the stimulus source; they do so by adapting their tactic signal transduction pathways to the environment. Their self-motility thus allows them to swim against a traveling tactic wave, whereas a simple fore-rear asymmetry argument would suggest the opposite. Their biomimetic counterpart, the artificial microswimmers, also propel themselves by harvesting kinetic energy from an active medium, but, in contrast, lack the adaptive capacity. Here we investigate the transport of artificial swimmers subject to traveling active waves and show, by means of analytical and numerical methods, that self-propelled particles can actually diffuse in either direction with respect to the wave, depending on its speed and waveform. Moreover, chiral swimmers, which move along spiraling trajectories, may diffuse preferably in a direction perpendicular to the active wave. Such a variety of tactic responses is explained by the modulation of the swimmer's diffusion inside traveling active pulses.
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Affiliation(s)
| | - Peter Hänggi
- Institut für Physik, University of Augsburg, D-86159, Germany
- Nanosystems Initiative Munich, Schellingstraße 4, D-80799 München, Germany
- Department of Physics, National University of Singapore, 117551 Singapore, Republic of Singapore
| | - Fabio Marchesoni
- Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
- Dipartimento di Fisica, Università di Camerino, I-62032 Camerino, Italy
| | - Colm Mulhern
- Institut für Physik, University of Augsburg, D-86159, Germany
| | - Sergey Savel'ev
- Department of Physics, Loughborough University, Loughborough, LE11 3TU, United Kingdom
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Chen JX, Chen YG, Ma YQ. Chemotactic dynamics of catalytic dimer nanomotors. SOFT MATTER 2016; 12:1876-1883. [PMID: 26679990 DOI: 10.1039/c5sm02647d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Synthetic chemically powered nanomotors possessing the ability of chemotaxis are desirable for target cargo delivery and self-assembly. The chemotactic properties of a sphere dimer motor, composed of linked catalytic and inactive monomers, are studied in a gradient field of fuel. Particle-based simulation is carried out by means of hybrid molecular dynamics/multiparticle collision dynamics. The detailed tracking and motion analysis describing the running and tumbling of the sphere dimer motor in the process of chemotaxis are investigated. Physical factors affecting chemotactic velocity are discussed, and quantitative relations are presented. The influence of the geometry of sphere dimer motors on the chemotactic dynamics is explored, which is beneficial for the design of motors with high sensitivity for detecting the surrounding environment.
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Affiliation(s)
- Jiang-Xing Chen
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China.
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15
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Robertson B, Kapral R. Nanomotor dynamics in a chemically oscillating medium. J Chem Phys 2016; 142:154902. [PMID: 25903905 DOI: 10.1063/1.4918329] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Synthetic nanomotors powered by chemical reactions have potential uses as cargo transport vehicles in both in vivo and in vitro applications. In many situations, motors will have to operate in out-of-equilibrium complex chemically reacting media, which supply fuel to the motors and remove the products they produce. Using molecular simulation and mean-field theory, this paper describes some of the new features that arise when a chemically powered nanomotor, operating through a diffusiophoretic mechanism, moves in an environment that supports an oscillatory chemical reaction network. It is shown how oscillations in the concentrations in chemical species in the environment give rise to oscillatory motor dynamics. More importantly, since the catalytic reactions on the motor that are responsible for its propulsion couple to the bulk phase reaction network, the motor can change its local environment. This process can give rise to distinctive spatiotemporal structures in reaction-diffusion media that occur as a result of active motor motion. Such locally induced nonequilibrium structure will play an important role in applications that involve motor dynamics in complex chemical media.
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Affiliation(s)
- Bryan Robertson
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Raymond Kapral
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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16
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Colberg PH, Reigh SY, Robertson B, Kapral R. Chemistry in motion: tiny synthetic motors. Acc Chem Res 2014; 47:3504-11. [PMID: 25357202 DOI: 10.1021/ar5002582] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
CONSPECTUS: Diffusion is the principal transport mechanism that controls the motion of solute molecules and other species in solution; however, the random walk process that underlies diffusion is slow and often nonspecific. Although diffusion is an essential mechanism for transport in the biological realm, biological systems have devised more efficient transport mechanisms using molecular motors. Most biological motors utilize some form of chemical energy derived from their surroundings to induce conformational changes in order to carry out specific functions. These small molecular motors operate in the presence of strong thermal fluctuations and in the regime of low Reynolds numbers, where viscous forces dominate inertial forces. Thus, their dynamical behavior is fundamentally different from that of macroscopic motors, and different mechanisms are responsible for the production of useful mechanical motion. There is no reason why our interest should be confined to the small motors that occur naturally in biological systems. Recently, micron and nanoscale motors that use chemical energy to produce directed motion by a number of different mechanisms have been made in the laboratory. These small synthetic motors also experience strong thermal fluctuations and operate in regimes where viscous forces dominate. Potentially, these motors could be directed to perform different transport tasks, analogous to those of biological motors, for both in vivo and in vitro applications. Although some synthetic motors execute conformational changes to effect motion, the majority do not, and, instead, they use other mechanisms to convert chemical energy into directed motion. In this Account, we describe how synthetic motors that operate by self-diffusiophoresis make use of a self-generated concentration gradient to drive motor motion. A description of propulsion by self-diffusiophoresis is presented for Janus particle motors comprising catalytic and noncatalytic faces. The properties of the dynamics of chemically powered motors are illustrated by presenting the results of particle-based simulations of sphere-dimer motors constructed from linked catalytic and noncatalytic spheres. The geometries of both Janus and sphere-dimer motors with asymmetric catalytic activity support the formation of concentration gradients around the motors. Because directed motion can occur only when the system is not in equilibrium, the nature of the environment and the role it plays in motor dynamics are described. Rotational Brownian motion also acts to limit directed motion, and it has especially strong effects for very small motors. We address the following question: how small can motors be and still exhibit effects due to propulsion, even if only to enhance diffusion? Synthetic motors have the potential to transform the manner in which chemical dynamical processes are carried out for a wide range of applications.
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Affiliation(s)
- Peter H. Colberg
- Chemical Physics Theory Group,
Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Shang Yik Reigh
- Chemical Physics Theory Group,
Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Bryan Robertson
- Chemical Physics Theory Group,
Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Raymond Kapral
- Chemical Physics Theory Group,
Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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17
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Löber J, Martens S, Engel H. Shaping wave patterns in reaction-diffusion systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:062911. [PMID: 25615168 DOI: 10.1103/physreve.90.062911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Indexed: 06/04/2023]
Abstract
We present a method to control the two-dimensional shape of traveling wave solutions to reaction-diffusion systems, such as, interfaces and excitation pulses. Control signals that realize a pregiven wave shape are determined analytically from nonlinear evolution equation for isoconcentration lines as the perturbed nonlinear phase diffusion equation or the perturbed linear eikonal equation. While the control enforces a desired wave shape perpendicular to the local propagation direction, the wave profile along the propagation direction itself remains almost unaffected. Provided that the one-dimensional wave profile of all state variables and its propagation velocity can be measured experimentally, and the diffusion coefficients of the reacting species are given, the new approach can be applied even if the underlying nonlinear reaction kinetics are unknown.
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Affiliation(s)
- Jakob Löber
- Institut für Theoretische Physik, Hardenbergstraße 36, EW 7-1, Technische Universität Berlin, 10623 Berlin, Germany
| | - Steffen Martens
- Institut für Theoretische Physik, Hardenbergstraße 36, EW 7-1, Technische Universität Berlin, 10623 Berlin, Germany
| | - Harald Engel
- Institut für Theoretische Physik, Hardenbergstraße 36, EW 7-1, Technische Universität Berlin, 10623 Berlin, Germany
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Kapral R. Perspective: nanomotors without moving parts that propel themselves in solution. J Chem Phys 2013; 138:020901. [PMID: 23320656 DOI: 10.1063/1.4773981] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Self-propelled nanomotors use chemical energy to produce directed motion. Like many molecular motors they suffer strong perturbations from the environment in which they move as a result of thermal fluctuations and do not rely on inertia for their propulsion. Such tiny motors are the subject of considerable research because of their potential applications, and a variety of synthetic motors have been made and are being studied for this purpose. Chemically powered self-propelled nanomotors without moving parts that rely on asymmetric chemical reactions to effect directed motion are the focus of this article. The mechanisms they use for propulsion, how size and fuel sources influence their motion, how they cope with strong molecular fluctuations, and how they behave collectively are described. The practical applications of such nanomotors are largely unrealized and the subject of speculation. Since molecular motors are ubiquitous in biology and perform a myriad of complex tasks, the hope is that synthetic motors might be able to perform analogous tasks. They may have the potential to change our perspective on how chemical dynamics takes place in complex systems.
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Affiliation(s)
- Raymond Kapral
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada.
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de Buyl P, Kapral R. Phoretic self-propulsion: a mesoscopic description of reaction dynamics that powers motion. NANOSCALE 2013; 5:1337-44. [PMID: 23282885 DOI: 10.1039/c2nr33711h] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The fabrication of synthetic self-propelled particles and the experimental investigations of their dynamics have stimulated interest in self-generated phoretic effects that propel nano- and micron-scale objects. Theoretical modeling of these phenomena is often based on a continuum description of the solvent for different phoretic propulsion mechanisms, including, self-electrophoresis, self-diffusiophoresis and self-thermophoresis. The work in this paper considers various types of catalytic chemical reaction at the motor surface and in the bulk fluid that come into play in mesoscopic descriptions of the dynamics. The formulation is illustrated by developing the mesoscopic reaction dynamics for exothermic and dissociation reactions that are used to power motor motion. The results of simulations of the self-propelled dynamics of composite Janus particles by these mechanisms are presented.
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Affiliation(s)
- Pierre de Buyl
- Center for Nonlinear Phenomena and Complex Systems, Université libre de Bruxelles, Campus Plaine - CP231, 50 Av. F. Roosevelt, 1050 Brussels, Belgium.
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Zhu L, Shen X, Zeng Z, Wang H, Zhang H, Chen H. Induced coiling action: exploring the intrinsic defects in five-fold twinned silver nanowires. ACS NANO 2012; 6:6033-6039. [PMID: 22712429 DOI: 10.1021/nn301096n] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Growth of polythiophene (PTh) on five-fold twinned Ag nanowires (NWs) is not symmetrical due to preferred etching of their intrinsic defects. This imbalance of polymer formation leads to consistent bending action along the etched NWs, coiling the resulting Ag-PTh nanocomposites into planar spirals. We studied the etching intermediates and also the effects of the surface ligands in order to understand the symmetry-breaking action. The defect-dependent etching chemistry offers a new means to induce motion and a novel perspective in the ordered occurrence of certain defects. We demonstrate that Ag can be deposited back onto the coiled Ag-PTh composite to form metallic spirals.
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Affiliation(s)
- Liangfang Zhu
- Division of Chemistry and Biological Chemistry, Nanyang Technological University, Singapore 637371
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Sabass B, Seifert U. Dynamics and efficiency of a self-propelled, diffusiophoretic swimmer. J Chem Phys 2012; 136:064508. [DOI: 10.1063/1.3681143] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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