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Pierre Gaspard, Raymond Kapral
Microscopic dynamical aspects of the propulsion of nanomotors by self-phoretic mechanisms are considered. Propulsion by self-diffusiophoresis relies on the mechanochemical coupling between the fluid velocity field and the concentration fields induced by asymmetric catalytic reactions on the motor surface. The consistency between the thermodynamics of this coupling and the microscopic reversibility of the underlying molecular dynamics is investigated. For this purpose, a mechanochemical fluctuation theorem for the joint probability to find the motor at position r after n reactive events have occurred during the time interval t is derived, starting from coupled Langevin equations for the translational, rotational, and chemical fluctuations of self-phoretic motors...
December 7, 2017: Journal of Chemical Physics
Jinxing Li, Pavimol Angsantikul, Wenjuan Liu, Berta Esteban-Fernández de Ávila, Xiaocong Chang, Elodie Sandraz, Yuyan Liang, Siyu Zhu, Yue Zhang, Chuanrui Chen, Weiwei Gao, Liangfang Zhang, Joseph Wang
One emerging and exciting topic in robotics research is the design of micro-/nanoscale robots for biomedical operations. Unlike industrial robots that are developed primarily to automate routine and dangerous tasks, biomedical nanorobots are designed for complex, physiologically relevant environments, and tasks that involve unanticipated biological events. Here, a biologically interfaced nanorobot is reported, made of magnetic helical nanomotors cloaked with the plasma membrane of human platelets. The resulting biomimetic nanorobots possess a biological membrane coating consisting of diverse functional proteins associated with human platelets...
November 28, 2017: Advanced Materials
Chuanrui Chen, Xiaocong Chang, Hazhir Teymourian, Doris E Ramírez Herrera, Berta Esteban Fernández de Ávila, Xiaolong Lu, Jinxing Li, Sha He, Chengcheng Fang, Yuyan Liang, Fangzhi Mou, Jianguo Guan, Joseph Wang
While chemical communication plays a key role in diverse natural processes, the intelligent chemical communication between synthetic nanomotors remains unexplored. Here we demonstrate the design and operation of bio-inspired synthetic nanomotors capable of chemical communication among themselves that influences their propulsion behavior. The chemical message is sent from a moving 'activator' motor to a nearby 'activated' (receiver) one, and involves release of silver ions from a Janus PS/Ni/Au/Ag 'activator' motor to the 'activated' Janus SiO2/Pt nanomotor...
November 15, 2017: Angewandte Chemie
Sebastian Gliga, Gino Hrkac, Claire Donnelly, Jonathan Büchi, Armin Kleibert, Jizhai Cui, Alan Farhan, Eugenie Kirk, Rajesh V Chopdekar, Yusuke Masaki, Nicholas S Bingham, Andreas Scholl, Robert L Stamps, Laura J Heyderman
Modern nanofabrication techniques have opened the possibility to create novel functional materials, whose properties transcend those of their constituent elements. In particular, tuning the magnetostatic interactions in geometrically frustrated arrangements of nanoelements called artificial spin ice can lead to specific collective behaviour, including emergent magnetic monopoles, charge screening and transport, as well as magnonic response. Here, we demonstrate a spin-ice-based active material in which energy is converted into unidirectional dynamics...
October 23, 2017: Nature Materials
Xiao-Ni Zhang, Kun Cai, Jiao Shi, Qing-Hua Qin
The rotation transmission system made from co-axial multi-walled nanotubes (MWNT) has a function of regulating the input rotation from a nanomotor. The mechanism for the regulation is that the friction among the tubes during rotation governs the rotation of the rotors in the nanosystem. Integrating a rotary nanomotor and a nanobearing into a MWNT-based rotation transmission system, it is discovered that the stator (outer tube) provides relative greater friction on the rotors by penetrating the motor tube which has a higher stable rotational frequency...
October 12, 2017: Nanotechnology
Dekai Zhou, Liqiang Ren, Yuguang C Li, Pengtao Xu, Yuan Gao, Guangyu Zhang, Wei Wang, Thomas E Mallouk, Longqiu Li
We report the synthesis and properties of rod-shaped gold/iron oxide nanomotors that are powered by visible light in dilute hydrogen peroxide solutions. Electrochemical measurements confirmed that the light-driven nanomotors operate by a self-electrophoretic mechanism, modulated by the photovoltage and the photoconductivity of gold/iron oxide. Due to the magnetism of iron oxide, the nanomotors can be steered by an external magnetic field without incorporating additional magnetic materials into the nanomotors...
October 6, 2017: Chemical Communications: Chem Comm
Pengyu Lv, Hai Le The, Jan Eijkel, Albert Van den Berg, Xuehua Zhang, Detlef Lohse
Whereas bubble growth out of gas-oversatured solutions has been quite well understood, including the formation and stability of surface nanobubbles, this is not the case for bubbles forming on catalytic surfaces due to catalytic reactions, though it has important implications for gas evolution reactions and self-propulsion of micro/nanomotors fueled by bubble release. In this work we have filled this gap by experimentally and theoretically examining the growth and detachment dynamics of oxygen bubbles from hydrogen peroxide decomposition catalyzed by gold...
September 28, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Renfeng Dong, Chun Wang, Qinglong Wang, Allen Pei, Xueling She, Yuxian Zhang, Yuepeng Cai
Improving the propulsion of artificial micro-nanomotors represents an exciting nanotechnology challenge, especially considering their cargo delivery ability and fuel efficiency. In light of the excellent photocatalytic performance of zinc oxide (ZnO) and chemical catalytic properties of platinum (Pt), ZnO-Pt microrockets with light-enhanced propulsion have been developed by atomic layer deposition (ALD) technology. The velocity of such microrockets is dramatically doubled upon irradiation by 77 mW cm(-2) ultraviolet (UV) light in 10% H2O2 and is almost 3 times higher than the classic poly(3,4-ethylenedioxythiophene)-Pt microrockets (PEDOT-Pt microrockets) even in 6% H2O2 under the same UV light...
October 12, 2017: Nanoscale
Leilei Xu, Fangzhi Mou, Haotian Gong, Ming Luo, Jianguo Guan
Light, as an external stimulus, is capable of driving the motion of micro/nanomotors (MNMs) with the advantages of reversible, wireless and remote manoeuvre on demand with excellent spatial and temporal resolution. This review focuses on the state-of-the-art light-driven MNMs, which are able to move in liquids or on a substrate surface by converting light energy into mechanical work. The general design strategies for constructing asymmetric fields around light-driven MNMs to propel themselves are introduced as well as the photoactive materials for light-driven MNMs, including photocatalytic materials, photothermal materials and photochromic materials...
November 13, 2017: Chemical Society Reviews
Kuiwen Zhao, Huiying Wu
The well-known fountain effect of superfluid helium can directly convert heat to mechanical work by the transport of the superfluid across narrow channels under a temperature difference. But it is regarded as a unique feature of superfluids, only occurring below the temperature of 2.17 K. Here we report a peculiar fountain effect of ice-like water across nanotubes at room temperature. Based on molecular simulations, we observed fascinating ultrafast fountain flow across nanotubes from the cold side to the hot side under a small temperature difference, due to the near-dissipationless nature of ice-like ordered water inside the nanotubes...
November 1, 2017: Physical Chemistry Chemical Physics: PCCP
Paula Díez, Berta Esteban-Fernández de Ávila, Doris E Ramírez-Herrera, Reynaldo Villalonga, Joseph Wang
We report herein the design of an autonomous glucose-responsive smart nanomachine for insulin (In) delivery based on ultrasound (US)-propelled nanomotors combined with an enzyme-based sensing-effector unit. Gold nanowire (AuNW) motors have been coupled with a mesoporous silica (MS) segment, which was gated with pH-responsive phenylboronic acid (PBA)-glucose oxidase (GOx) supramolecular nanovalves responsible for the insulin release. Glucose-induced protonation of the PBA groups triggers the opening of the pH-driven gate and uncapping of the insulin-loaded nanovalves...
October 5, 2017: Nanoscale
Liqiang Ren, Dekai Zhou, Zhangming Mao, Pengtao Xu, Tony Jun Huang, Thomas E Mallouk
Rheotaxis is a common phenomenon in nature that refers to the directed movement of micro-organisms as a result of shear flow. The ability to mimic natural rheotaxis using synthetic micro/nanomotors adds functionality to enable their applications in biomedicine and chemistry. Here, we present a hybrid strategy that can achieve both positive and negative rheotaxis of synthetic bimetallic micromotors by employing a combination of chemical fuel and acoustic force. An acoustofluidic device is developed for the integration of the two propulsion mechanisms...
October 24, 2017: ACS Nano
Weiwei Gao, Berta Esteban-Fernández de Ávila, Liangfang Zhang, Joseph Wang
Micro/nanomotors distinguish themselves with in situ energy conversion capability for autonomous movement, a feature that confers remarkable potential to improve cancer treatment. In this review article, three areas are highlighted where micro/nanomotors have established themselves with unique contributions, including propelled navigation to promote cancer cell targeting, powered cell membrane penetration to enhance intracellular delivery, and steered isolation of circulating tumor cells for detection. Progress made in these areas has offered promising inspiration and opportunities aimed for enhancing the efficiency and precision of drug targeting to cancer cells, improving the capability of delivering anticancer drug into cytoplasm for bioactivity, and enabling more rapid and sensitive cancer cell detection...
September 9, 2017: Advanced Drug Delivery Reviews
Xuewen Fu, Bin Chen, Jau Tang, Ahmed H Zewail
Dynamics of active or propulsive Brownian particles in nonequilibrium status have recently attracted great interest in many fields including artificial micro/nanoscopic motors and biological entities. Understanding of their dynamics can provide insight into the statistical properties of physical and biological systems far from equilibrium. We report the translational dynamics of photon-activated gold nanoparticles (NPs) in water imaged by liquid-cell four-dimensional electron microscopy (4D-EM) with high spatiotemporal resolution...
August 2017: Science Advances
Yingfeng Tu, Fei Peng, Daniela A Wilson
Inspired by the self-migration of microorganisms in nature, artificial micro- and nanomotors can mimic this fantastic behavior by converting chemical fuel or external energy into mechanical motion. These self-propelled micro- and nanomotors, designed either by top-down or bottom-up approaches, are able to achieve different applications, such as environmental remediation, sensing, cargo/sperm transportation, drug delivery, and even precision micro-/nanosurgery. For these various applications, especially biomedical applications, regulating on-demand the motion of micro- and nanomotors is quite essential...
August 25, 2017: Advanced Materials
Peter H Colberg, Raymond Kapral
The collective behavior of chemically propelled sphere-dimer motors made from linked catalytic and noncatalytic spheres in a quasi-two-dimensional confined geometry is studied using a coarse-grained microscopic dynamical model. Chemical reactions at the catalytic spheres that convert fuel to product generate forces that couple to solvent degrees of freedom as a consequence of momentum conservation in the microscopic dynamics. The collective behavior of the many-body system is influenced by direct intermolecular interactions among the motors, chemotactic effects due to chemical gradients, hydrodynamic coupling, and thermal noise...
August 14, 2017: Journal of Chemical Physics
Yunru Yu, Luoran Shang, Wei Gao, Ze Zhao, Huan Wang, Yuanjin Zhao
Considerable efforts have been devoted to developing artificial micro/nanomotors that can convert energy into movement. A flow lithography integrated microfluidic spinning and spiraling system is developed for the continuous generation of bioinspired helical micromotors. Because the generation processes could be precisely tuned by adjusting the flow rates and the illuminating frequency, the length, diameter, and pitch of the helical micromotors were highly controllable. Benefiting from the fast online gelation and polymerization, the resultant helical micromotors could be imparted with Janus, triplex, and core-shell cross-sectional structures that have never been achieved by other methods...
July 29, 2017: Angewandte Chemie
Ognjen Ilic, Ido Kaminer, Bo Zhen, Owen D Miller, Hrvoje Buljan, Marin Soljačić
Shaping the topology of light, by way of spin or orbital angular momentum engineering, is a powerful tool to manipulate matter on the nanoscale. Conventionally, such methods focus on shaping the incident beam of light and not the full interaction between the light and the object to be manipulated. We theoretically show that tailoring the topology of the phase space of the light particle interaction is a fundamentally more versatile approach, enabling dynamics that may not be achievable by shaping of the light alone...
June 2017: Science Advances
Qianlan Rao, Tieyan Si, Zhiguang Wu, Mingjun Xuan, Qiang He
Self-propelled micro/nanomotors possess tremendous exciting promise in diverse fields. We describe an asymmetric, fuel-free and near-infrared light-powered torpedo micromotor, which is constructed by using a porous membrane-assisted layer-by-layer sol-gel method to form silica multilayer inside the pores, following by the deposition of gold nanoparticles on one end of the pores. In the absence of chemical fuels, the high propulsion of microtorpedoes under illumination of near-infrared light is owing to the photo-thermal effect of gold clusters, generating a thermal gradient inside the microtorpedoes...
July 4, 2017: Scientific Reports
José García-Torres, Albert Serrà, Pietro Tierno, Xavier Alcobé, Elisa Vallés
Electrochemically fabricated magnetic mesoporous CoNi@Pt nanorods are excellent nanomotors with controlled magnetic propulsion and excellent catalytic properties. The core-shell structure allows a double functionality: (i) controlled motion of the nanorods by applying rotating magnetic fields at different frequencies and field strengths and (ii) effective catalytic activity of the platinum shell for reactions involving sodium borohydride. The structure and magnetic properties of the CoNi core are not modified by the presence of the Pt shell...
July 19, 2017: ACS Applied Materials & Interfaces
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