Magnetically Driven Janus Micro‐Ellipsoids Realized via Asymmetric Gathering of the Magnetic Charge

Güell, Oriol; Sagués, Francesc; Tierno, Pietro

doi:10.1002/adma.201100902

Cited by 41 publications

(36 citation statements)

References 44 publications

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“…[1][2][3] Inspired by such rotary motors, various micro-/nanorotors have been developed, [4] including chemical-and light-driven artificial molecular rotors, [2,5] electricfield-driven DNA nanorotors, [6] chemical-fuel-driven catalytic micro-/nanorotors, [7][8][9] and electric-field-driven CNT-based NEMS. [10] A rotating magnetic field has also been used to rotate a variety of magnetic micro/nano-scale objects, such as single/ self-assembled beads, [11][12][13][14][15] rigid [16,17] and flexible wires, [18] and helical structures, [19,20] in fluid. Among these, helical micro-/ nanoswimmers, inspired by bacterial flagella, [21] convert rotational motion to translational motion, which is one of the well-known propulsion strategies for a low Reynolds number regime.…”

Section: Doi: 101002/adma201103818mentioning

confidence: 99%

Magnetic Helical Micromachines: Fabrication, Controlled Swimming, and Cargo Transport

et al. 2012

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Section: Doi: 101002/adma201103818mentioning

confidence: 99%

Magnetic Helical Micromachines: Fabrication, Controlled Swimming, and Cargo Transport

et al. 2012

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“…In order to visualize the rotational movement of a particle subject to an oscillating magnetic field, fluorescent, super-paramagnetic polystyrene microspheres (Spherotech, 4.88µm diameter) were elongated into prolate spheroids (29,30). Briefly, particles are first embedded in a thin vinyl film which is fitted onto a mechanical (b) The resulting shape allows visualization of the angular orientation θ as the spheroid is driven by an external field with orientation angle β.…”

Section: Magnetic Probe Particlesmentioning

confidence: 99%

Active Microrheology of Intestinal Mucus in the Larval Zebrafish

Taormina

Parthasarathy

2016

Preprint

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Mucus is a complex biological fluid that plays a variety of functional roles in many physiological systems. Intestinal mucus in particular serves as a physical barrier to pathogens, a medium for the diffusion of nutrients and metabolites, and an environmental home for colonizing microbes. Its rheological properties have therefore been the subject of many investigations, thus far limited, however, to in vitro studies due to the difficulty of measurement in the natural context of the gut. This limitation especially hinders our understanding of how the gut microbiota interact with the intestinal environment, since examination of this calls not only for in vivo measurement techniques, but for techniques that can be applied to model organisms in which the microbial state of the gut can be controlled. We address this challenge by developing a method that combines magnetic microrheology, light sheet fluorescence microscopy, and microgavage of particles, applying this to the larval zebrafish, a model vertebrate. We present measurements of the viscosity of mucus within the intestinal bulb of both germ-free (devoid of intestinal microbes) and conventionally reared larval zebrafish. At the length scale probed (≈ 10µm), we find that mucus behaves as a Newtonian fluid, with no discernable elastic component. Surprisingly, despite known differences in the the number of secretory cells in germ-free zebrafish and their conventional counterparts, the fluid viscosity for these two groups was very similar. Our measurements provide the first in vivo measurements of intestinal mucus rheology at micron length scales in living animals, quantifying of an important biomaterial environment and highlighting the utility of active magnetic microrheology for biophysical studies.Corresponding

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“…Although some particles of this kind were known from earlier work by others, previous emphasis was on their assembly or dynamics in the presence of external magnetic field [25][26][27][28][29][30][31] . Here, taking advantage of rapid progress in the synthesis of anisotropic colloids [32][33][34][35][36][37] , we go beyond this to delve into the role of shape and constituent anisotropy.…”

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confidence: 99%

Colloidal ribbons and rings from Janus magnetic rods

et al. 2013

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Dipolar particles are fundamental building blocks in nature and technology, yet the effect of particle anisotropy is seldom explored. Here, we fabricate colloidal silica rods coated with a hemicylindrical magnetic layer to satisfy multiple criteria: nearly monodisperse, easily imaged and magnetic interaction that dominates over gravity. We confirm long-predicted features of dipolar assembly and stress the microstructural variety brought about by shape and constituent anisotropy, especially by extrapolating knowledge learned from literal molecules. In this colloidal system, we describe analogies to liquid crystalline deformations with bend, splay and twist; an analogy to cis/trans isomerism in organic molecules, which in our system can be controllably and reversibly switched; and a field-switching methodology to direct single ribbons into not only single but also multiple rings that can subsequently undergo hierarchical self-assembly. We highlight subtle material issues of control and design rules for reconfigurable dipolar materials with building blocks of complex shape.

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Magnetically Driven Janus Micro‐Ellipsoids Realized via Asymmetric Gathering of the Magnetic Charge

Cited by 41 publications

References 44 publications

Magnetic Helical Micromachines: Fabrication, Controlled Swimming, and Cargo Transport

Magnetic Helical Micromachines: Fabrication, Controlled Swimming, and Cargo Transport

Active Microrheology of Intestinal Mucus in the Larval Zebrafish

Colloidal ribbons and rings from Janus magnetic rods

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