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Ren C, Sun W, Zhao T, Li C, Jiang C, Duan P. A Single-Enantiomer Emitter Enabled Superstructural Helix Inversion for Upconverting and Downshifting Luminescence with Bidirectional Circular Polarization. Angew Chem Int Ed Engl 2023; 62:e202315136. [PMID: 37902429 DOI: 10.1002/anie.202315136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 10/28/2023] [Accepted: 10/30/2023] [Indexed: 10/31/2023]
Abstract
The helical twisting tendency of liquid crystals (LCs) is generally governed by the inherent configuration of the chiral emitter. Here, we introduce the multistage inversion of supramolecular chirality as well as circularly polarized luminescence (CPL) by manipulating the ratio of single enantiomeric emitters (R-PCP) to LC monomers (5CB). Increasing the content of R-PCP from 1 wt % to 3 wt % inverted the helix of LCs from left-handed to right-handed, accompanying a CPL sign changed from positive to negative. The biaxiality of chiral emitters, as well as the steric effect of chiral-chiral and chiral-achiral interaction, were identified as the reasons for helical sense inversion. Due to the strong helical twisting power, 4 wt % R-PCP drove the photonic band gap (PBG) of chiral LCs to match up with their emission range, leading to an inversion of the CPL again with a high dissymmetry factor (≈1.2). Directly adjusting the PBG using chiral emitters is seldom achieved in cholesteric LCs. On this basis, an achiral sensitizer PtTPBP was assembled into the helical superstructure. The generation of triplet-triplet annihilation-induced upconverted CPL from R-PCP and the downshifting CPL from PtTPBP with opposite rotation was achieved in a single chiral LC system by tuning the position of the PBG.
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Affiliation(s)
- Chao Ren
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), No. 11, ZhongGuanCun BeiYiTiao, Beijing, 100190, P. R. China
| | - Wenjing Sun
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), No. 11, ZhongGuanCun BeiYiTiao, Beijing, 100190, P. R. China
| | - Tonghan Zhao
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), No. 11, ZhongGuanCun BeiYiTiao, Beijing, 100190, P. R. China
| | - Chengxi Li
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), No. 11, ZhongGuanCun BeiYiTiao, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, 100049, Beijing, P. R. China
| | - Chengyu Jiang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), No. 11, ZhongGuanCun BeiYiTiao, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, 100049, Beijing, P. R. China
| | - Pengfei Duan
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), No. 11, ZhongGuanCun BeiYiTiao, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, 100049, Beijing, P. R. China
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Ding L, Pelcovits RA, Powers TR. Chiral fluid membranes with orientational order and multiple edges. SOFT MATTER 2023; 19:8453-8464. [PMID: 37882610 DOI: 10.1039/d3sm01158e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
Abstract
We carry out Monte Carlo simulations on fluid membranes with orientational order and multiple edges in the presence and absence of external forces. The membrane resists bending and has an edge tension, the orientational order couples with the membrane surface normal through a cost for tilting, and there is a chiral liquid crystalline interaction. In the absence of external forces, a membrane initialized as a vesicle will form a disk at low chirality, with the directors forming a smectic-A phase with alignment perpendicular to the membrane surface except near the edge. At large chirality a catenoid-like shape or a trinoid-like shape is formed, depending on the number of edges in the initial vesicle. This shape change is accompanied by cholesteric ordering of the directors and multiple π walls connecting the membrane edges and wrapping around the membrane neck. If the membrane is initialized instead in a cylindrical shape and stretched by an external force, it maintains a nearly cylindrical shape but additional liquid crystalline phases appear. For large tilt coupling and low chirality, a smectic-A phase forms where the directors are normal to the surface of the membrane. For lower values of the tilt coupling, a nematic phase appears at zero chirality with the average director oriented perpendicular to the long axis of the membrane, while for nonzero chirality a cholesteric phase appears. The π walls are tilt walls at low chirality and transition to twist walls as chirality is increased. We construct a continuum model of the director field to explain this behavior.
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Affiliation(s)
- Lijie Ding
- Department of Physics, Brown University, Providence, RI 02912, USA.
| | - Robert A Pelcovits
- Department of Physics, Brown University, Providence, RI 02912, USA.
- Brown Theoretical Physics Center, Brown University, Providence, RI 02912, USA
| | - Thomas R Powers
- Department of Physics, Brown University, Providence, RI 02912, USA.
- Brown Theoretical Physics Center, Brown University, Providence, RI 02912, USA
- School of Engineering, Brown University, Providence, RI 02912, USA
- Center for Fluid Mechanics, Brown University, Providence, RI 02912, USA
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3
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Controlling the shape and topology of two-component colloidal membranes. Proc Natl Acad Sci U S A 2022; 119:e2204453119. [PMID: 35914159 PMCID: PMC9371715 DOI: 10.1073/pnas.2204453119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Changes in the geometry and topology of self-assembled membranes underlie diverse processes across cellular biology and engineering. Similar to lipid bilayers, monolayer colloidal membranes have in-plane fluid-like dynamics and out-of-plane bending elasticity. Their open edges and micrometer-length scale provide a tractable system to study the equilibrium energetics and dynamic pathways of membrane assembly and reconfiguration. Here, we find that doping colloidal membranes with short miscible rods transforms disk-shaped membranes into saddle-shaped surfaces with complex edge structures. The saddle-shaped membranes are well approximated by Enneper's minimal surfaces. Theoretical modeling demonstrates that their formation is driven by increasing the positive Gaussian modulus, which in turn, is controlled by the fraction of short rods. Further coalescence of saddle-shaped surfaces leads to diverse topologically distinct structures, including shapes similar to catenoids, trinoids, four-noids, and higher-order structures. At long timescales, we observe the formation of a system-spanning, sponge-like phase. The unique features of colloidal membranes reveal the topological transformations that accompany coalescence pathways in real time. We enhance the functionality of these membranes by making their shape responsive to external stimuli. Our results demonstrate a pathway toward control of thin elastic sheets' shape and topology-a pathway driven by the emergent elasticity induced by compositional heterogeneity.
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Kuhnhold A, Göth N, Helmer N. Colloidal membranes of chiral rod-like particles. SOFT MATTER 2022; 18:905-921. [PMID: 35014647 DOI: 10.1039/d1sm01303c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We study colloidal (or smectic) membranes composed of chiral rod-like particles through Monte Carlo simulations. These objects are formed due to the presence of Asakura-Oosawa spheres acting as depletants and creating an effective attraction between the rods. The membranes' shape and structure can be influenced by several parameters, e.g. the number of spheres and rods, their length and their interaction. In order to compare simulation results to an elastic theory, we follow two ansatzes, approximating the free elastic energy in different ways. Both of them lead to reasonable results and capture the behaviour of the colloidal membrane system. One approximation, however, is not suited for achiral rods, where twisting occurs due to surface energy rather than elastic energy. We extract the inverse cholesteric pitch and twist penetration depth for chiral rods with this approximation. The other one is used to introduce a complementary method to estimate elastic constants from the shape of colloidal membranes. Besides, we describe the transition from homogeneously twisted membranes to membranes composed of substructures that occur when the chiral interaction exceeds a length-dependent threshold. We believe that our detailed study and discussion of different aspects of this model system are valuable from a fundamental research viewpoint and suitable for material design suggestions.
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Affiliation(s)
- Anja Kuhnhold
- Institute of Physics, University of Freiburg, 79104 Freiburg (Breisgau), Germany.
| | - Nils Göth
- Institute of Physics, University of Freiburg, 79104 Freiburg (Breisgau), Germany.
| | - Nadja Helmer
- Institute of Physics, University of Freiburg, 79104 Freiburg (Breisgau), Germany.
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5
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Liu X, Chen Z, Liu Q, Sheetah GH, Sun N, Zhao P, Xie Y, Smalyukh II. Morphological and Orientational Controls of Self-Assembly of Gold Nanorods Directed by Evaporative Microflows. ACS APPLIED MATERIALS & INTERFACES 2021; 13:53143-53154. [PMID: 34711053 DOI: 10.1021/acsami.1c12594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Evaporative self-assembly of noble metal nanoparticles into ordered structures holds great promise for fabricating optical and plasmonic devices by virtue of its low cost, high efficiency, and ease of operation. However, poor control of Marangoni flows is one of the challenges accounting for realizing a well-defined assembly. Herein, based on the theoretical analysis of the influence of evaporative intensity on the assembly, two simple but reliable flow-field-confinement platforms are designed to control the evaporative microflows and to work concurrently with depletion forces to enable the regulated self-assembly of gold nanorods. Orientationally ordered assemblies are realized by the designed strong unidirectional microflow in a capillary, and a device-scale assembly of monolayer membrane is obtained by the created weak convection in homemade glass cells. Morphologically diversified superstructure assemblies, such as spherulite-like, boundary-twisted, chiral spiral assemblies, and merging membranes with a π-twisted domain wall, are obtained due to the spontaneous symmetry breaking or in the presence of defects, such as surface steps and screw dislocations. Optical anisotropy and polarization-dependent behaviors of these assemblies are further revealed, implying the potential applications in plasmonic coupling devices and optoelectronic components. An understanding of the entropy-driven assembly behaviors and control of evaporative microflows to guide the self-assembly of gold nanorods provides insights into the general bottom-up approach that is helpful for constructing complex yet robust nanosuperstructures.
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Affiliation(s)
- Xiaoduo Liu
- School of Physics, Beihang University, Beijing 100191, China
| | - Ziyu Chen
- School of Physics, Beihang University, Beijing 100191, China
| | - Qingkun Liu
- Department of Physics, Material Science and Engineering Program, Department of Electrical, Computer, & Energy Engineering, and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States
- Department of Physics, Cornell University, Ithaca, New York 14850, United States
| | - Ghadah H Sheetah
- Physics Department, College of Science, King Faisal University, Hofuf 31982, Saudi Arabia
| | - Ningfei Sun
- School of Physics, Beihang University, Beijing 100191, China
| | - Peng Zhao
- School of Physics, Beihang University, Beijing 100191, China
| | - Yong Xie
- School of Physics, Beihang University, Beijing 100191, China
- Key Laboratory of Intelligent Systems and Equipment Electromagnetic Environment Effect, School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
| | - Ivan I Smalyukh
- Department of Physics, Material Science and Engineering Program, Department of Electrical, Computer, & Energy Engineering, and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, Colorado 80309, United States
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6
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Ding L, Pelcovits RA, Powers TR. Deformation and orientational order of chiral membranes with free edges. SOFT MATTER 2021; 17:6580-6588. [PMID: 34160539 DOI: 10.1039/d1sm00629k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Motivated by experiments on colloidal membranes composed of chiral rod-like viruses, we use Monte Carlo methods to simulate these systems and determine the phase diagram for the liquid crystalline order of the rods and the membrane shape. We generalize the Lebwohl-Lasher model for a nematic with a chiral coupling to a curved surface with edge tension and a resistance to bending, and include an energy cost for tilting of the rods relative to the local membrane normal. The membrane is represented by a triangular mesh of hard beads joined by bonds, where each bead is decorated by a director. The beads can move, the bonds can reconnect and the directors can rotate at each Monte Carlo step. When the cost of tilt is small, the membrane tends to be flat, with the rods only twisting near the edge for low chiral coupling, and remaining parallel to the normal in the interior of the membrane. At high chiral coupling, the rods twist everywhere, forming a cholesteric state. When the cost of tilt is large, the emergence of the cholesteric state at high values of the chiral coupling is accompanied by the bending of the membrane into a saddle shape. Increasing the edge tension tends to flatten the membrane. These results illustrate the geometric frustration arising from the inability of a surface normal to have twist.
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Affiliation(s)
- Lijie Ding
- Department of Physics, Brown University, Providence, RI 02912, USA.
| | - Robert A Pelcovits
- Department of Physics, Brown University, Providence, RI 02912, USA. and Brown Theoretical Physics Center, Brown University, Providence, RI 02912, USA
| | - Thomas R Powers
- Department of Physics, Brown University, Providence, RI 02912, USA. and Brown Theoretical Physics Center, Brown University, Providence, RI 02912, USA and School of Engineering, Brown University, Providence, RI 02912, USA and Center for Fluid Mechanics, Brown University, Providence, RI 02912, USA
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7
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Ding L, Pelcovits RA, Powers TR. Shapes of fluid membranes with chiral edges. Phys Rev E 2020; 102:032608. [PMID: 33075976 DOI: 10.1103/physreve.102.032608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 08/25/2020] [Indexed: 06/11/2023]
Abstract
We carry out Monte Carlo simulations of a colloidal fluid membrane with a free edge and composed of chiral rodlike viruses. The membrane is modeled by a triangular mesh of beads connected by bonds in which the bonds and beads are free to move at each Monte Carlo step. Since the constituent viruses are experimentally observed to twist only near the membrane edge, we use an effective energy that favors a particular sign of the geodesic torsion of the edge. The effective energy also includes the membrane bending stiffness, edge bending stiffness, and edge tension. We find three classes of membrane shapes resulting from the competition of the various terms in the free energy: branched shapes, chiral disks, and vesicles. Increasing the edge bending stiffness smooths the membrane edge, leading to correlations among the membrane normals at different points along the edge. The normalized power spectrum for edge displacements shows a peak with increasing preferred geodesic torsion. We also consider membrane shapes under an external force by fixing the distance between two ends of the membrane and finding the shape for increasing values of the distance between the two ends. As the distance increases, the membrane twists into a ribbon, with the force eventually reaching a plateau.
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Affiliation(s)
- Lijie Ding
- Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA
| | - Robert A Pelcovits
- Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA
- Brown Theoretical Physics Center and Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA
| | - Thomas R Powers
- Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA
- Center for Fluid Mechanics and Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA
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8
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Balchunas A, Jia LL, Zakhary MJ, Robaszewski J, Gibaud T, Dogic Z, Pelcovits RA, Powers TR. Force-Induced Formation of Twisted Chiral Ribbons. PHYSICAL REVIEW LETTERS 2020; 125:018002. [PMID: 32678628 DOI: 10.1103/physrevlett.125.018002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 03/06/2020] [Accepted: 05/12/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate that an achiral stretching force transforms disk-shaped colloidal membranes composed of chiral rods into twisted ribbons with handedness opposite the preferred twist of the rods. Using an experimental technique that enforces torque-free boundary conditions we simultaneously measure the force-extension curve and the ribbon shape. An effective theory that accounts for the membrane bending energy and uses geometric properties of the edge to model the internal liquid crystalline degrees of freedom explains both the measured force-extension curve and the force-induced twisted shape.
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Affiliation(s)
- Andrew Balchunas
- The Martin Fisher School of Physics, Brandeis University, 415 South Street, Waltham, Massachusetts 02454, USA
| | - Leroy L Jia
- Division of Applied Mathematics, Brown University, Providence, Rhode Island 02912, USA
| | - Mark J Zakhary
- The Martin Fisher School of Physics, Brandeis University, 415 South Street, Waltham, Massachusetts 02454, USA
| | - Joanna Robaszewski
- The Martin Fisher School of Physics, Brandeis University, 415 South Street, Waltham, Massachusetts 02454, USA
- Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106, USA
| | - Thomas Gibaud
- Univ Lyon, ENS de Lyon, Univ Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, F-69342 Lyon, France
| | - Zvonimir Dogic
- The Martin Fisher School of Physics, Brandeis University, 415 South Street, Waltham, Massachusetts 02454, USA
- Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106, USA
| | - Robert A Pelcovits
- Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA
| | - Thomas R Powers
- Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA
- School of Engineering, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA
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Balchunas AJ, Cabanas RA, Zakhary MJ, Gibaud T, Fraden S, Sharma P, Hagan MF, Dogic Z. Equation of state of colloidal membranes. SOFT MATTER 2019; 15:6791-6802. [PMID: 31408077 DOI: 10.1039/c9sm01054h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In the presence of a non-adsorbing polymer, monodisperse rod-like colloids assemble into one-rod-length thick liquid-like monolayers, called colloidal membranes. The density of the rods within a colloidal membrane is determined by a balance between the osmotic pressure exerted by the enveloping polymer suspension and the repulsion between the colloidal rods. We developed a microfluidic device for continuously observing an isolated membrane while dynamically controlling the osmotic pressure of the polymer suspension. Using this technology we measured the membrane rod density over a range of osmotic pressures than is wider that what is accessible in equilibrium samples. With increasing density we observed a first-order phase transition, in which the in-plane membrane order transforms from a 2D fluid into a 2D solid. In the limit of low osmotic pressures, we measured the rate at which individual rods evaporate from the membrane. The developed microfluidic technique could have wide applicability for in situ investigation of various soft materials and how their properties depend on the solvent composition.
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Conformational switching of chiral colloidal rafts regulates raft-raft attractions and repulsions. Proc Natl Acad Sci U S A 2019; 116:15792-15801. [PMID: 31320590 DOI: 10.1073/pnas.1900615116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Membrane-mediated particle interactions depend both on the properties of the particles themselves and the membrane environment in which they are suspended. Experiments have shown that chiral rod-like inclusions dissolved in a colloidal membrane of opposite handedness assemble into colloidal rafts, which are finite-sized reconfigurable droplets consisting of a large but precisely defined number of rods. We systematically tune the chirality of the background membrane and find that, in the achiral limit, colloidal rafts acquire complex structural properties and interactions. In particular, rafts can switch between 2 chiral states of opposite handedness, which alters the nature of the membrane-mediated raft-raft interactions. Rafts with the same chirality have long-ranged repulsions, while those with opposite chirality acquire attractions with a well-defined minimum. Both attractive and repulsive interactions are qualitatively explained by a continuum model that accounts for the coupling between the membrane thickness and the local tilt of the constituent rods. These switchable interactions enable assembly of colloidal rafts into intricate higher-order architectures, including stable tetrameric clusters and "ionic crystallites" of counter-twisting domains organized on a binary square lattice. Furthermore, the properties of individual rafts, such as their sizes, are controlled by their complexation with other rafts. The emergence of these complex behaviors can be rationalized purely in terms of generic couplings between compositional and orientational order of fluids of rod-like elements. Thus, the uncovered principles might have relevance for conventional lipid bilayers, in which the assembly of higher-order structures is also mediated by complex membrane-mediated interactions.
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Zhao J, Gulan U, Horie T, Ohmura N, Han J, Yang C, Kong J, Wang S, Xu BB. Advances in Biological Liquid Crystals. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900019. [PMID: 30892830 DOI: 10.1002/smll.201900019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/17/2019] [Indexed: 06/09/2023]
Abstract
Biological liquid crystals, a rich set of soft materials with rod-like structures widely existing in nature, possess typical lyotropic liquid crystalline phase properties both in vitro (e.g., cellulose, peptides, and protein assemblies) and in vivo (e.g., cellular lipid membrane, packed DNA in bacteria, and aligned fibroblasts). Given the ability to undergo phase transition in response to various stimuli, numerous practices are exercised to spatially arrange biological liquid crystals. Here, a fundamental understanding of interactions between rod-shaped biological building blocks and their orientational ordering across multiple length scales is addressed. Discussions are made with regard to the dependence of physical properties of nonmotile objects on the first-order phase transition and the coexistence of multi-phases in passive liquid crystalline systems. This work also focuses on how the applied physical stimuli drives the reorganization of constituent passive particles for a new steady-state alignment. A number of recent progresses in the dynamics behaviors of active liquid crystals are presented, and particular attention is given to those self-propelled animate elements, like the formation of motile topological defects, active turbulence, correlation of orientational ordering, and cellular functions. Finally, future implications and potential applications of the biological liquid crystalline materials are discussed.
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Affiliation(s)
- Jianguo Zhao
- Quanzhou Institute of Equipment Manufacturing, Haixi Institutes, Chinese Academy of Sciences, Quanzhou, 362200, China
- Third Institute of Physics-Biophysics, University of Göttingen, 37077, Göttingen, Germany
| | - Utku Gulan
- Institute of Environmental Engineering, ETH Zurich, 8093, Zurich, Switzerland
| | - Takafumi Horie
- Department of Chemical Science and Engineering, Kobe University, Kobe, 657-8501, Japan
| | - Naoto Ohmura
- Department of Chemical Science and Engineering, Kobe University, Kobe, 657-8501, Japan
| | - Jun Han
- Quanzhou Institute of Equipment Manufacturing, Haixi Institutes, Chinese Academy of Sciences, Quanzhou, 362200, China
| | - Chao Yang
- CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jie Kong
- Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Steven Wang
- School of Engineering, Newcastle University, Newcastle Upon Tyne, NE1 7RU, UK
| | - Ben Bin Xu
- Mechanical and Construction Engineering, Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK
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12
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Saikia L, Sharma P. Self assembly of cyclic polygon shaped fluid colloidal membranes through pinning. SOFT MATTER 2018; 14:9959-9966. [PMID: 30488940 DOI: 10.1039/c8sm01503a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
2D fluid monolayer membranes of rod-like viruses spontaneously form in a mixture of rods and polymers through depletion attraction. The rods are uniformly oriented within the bulk and twist in a zone around the membrane edge. Surprisingly, we find that cyclic polygonal shaped colloidal membranes form when polymers are added to a mixture of long and short-thick rods with the long and short-thick rods forming the faceted core and lobes of the polygon, respectively. We demonstrate that the origin of this anisotropic shape lies in the phenomenon of spreading of one liquid over another in the presence of disorder. As a membrane of short-thick rods spreads over another of longer rods, the edge bound rods untwist to become part of the newly formed two-rod interface. However, a small fraction of rods fail to untwist as the two rod interface forms and act as mobile pinning centers. Capillary flow of short-thick rods drives all the pinning centers to a single location in the composite membrane which now acts like a junction. This pinning junction inhibits complete engulfing of one membrane by the other. Repeated sequential events like this then lead to formation of multiple junctions and the overall cyclic polygon topology. We find that pinning junctions are weakly cross-linked in nature instead of being topological defects. We outline the necessary and sufficient constraints on the nature of rods to obtain stable out of equilibrium cyclic polygon membranes. Our results show a unique counter-intuitive scenario where defects lead to self-assembly of ordered structures.
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Affiliation(s)
- Lachit Saikia
- Department of Physics, Indian Institute of Science, Bengaluru, Karnataka 560012, India.
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Gibaud T. Filamentous phages as building blocks for reconfigurable and hierarchical self-assembly. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:493003. [PMID: 29099393 DOI: 10.1088/1361-648x/aa97f9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Filamentous bacteriophages such as fd-like viruses are monodisperse rod-like colloids that have well defined properties of diameter, length, rigidity, charge and chirality. Engineering these viruses leads to a library of colloidal rods, which can be used as building blocks for reconfigurable and hierarchical self-assembly. Their condensation in an aqueous solution with additive polymers, which act as depletants to induce attraction between the rods, leads to a myriad of fluid-like micronic structures ranging from isotropic/nematic droplets, colloid membranes, achiral membrane seeds, twisted ribbons, π-wall, pores, colloidal skyrmions, Möbius anchors, scallop membranes to membrane rafts. These structures, and the way that they shape-shift, not only shed light on the role of entropy, chiral frustration and topology in soft matter, but also mimic many structures encountered in different fields of science. On the one hand, filamentous phages being an experimental realization of colloidal hard rods, their condensation mediated by depletion interactions constitutes a blueprint for the self-assembly of rod-like particles and provides a fundamental foundation for bio- or material-oriented applications. On the other hand, the chiral properties of the viruses restrict the generalities of some results but vastly broaden the self-assembly possibilities.
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Affiliation(s)
- Thomas Gibaud
- Univ Lyon, Ens de Lyon, Univ Claude Bernard, CNRS, Laboratoire de Physique, F-69342 Lyon, France
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14
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Curvature instability of chiral colloidal membranes on crystallization. Nat Commun 2017; 8:1160. [PMID: 29074887 PMCID: PMC5658384 DOI: 10.1038/s41467-017-01441-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 09/19/2017] [Indexed: 11/08/2022] Open
Abstract
Buckling and wrinkling instabilities are failure modes of elastic sheets that are avoided in the traditional material design. Recently, a new paradigm has appeared where these instabilities are instead being utilized for high-performance applications. Multiple approaches such as heterogeneous gelation, capillary stresses, and confinement have been used to shape thin macroscopic elastic sheets. However, it remains a challenge to shape two-dimensional self-assembled monolayers at colloidal or molecular length scales. Here, we show the existence of a curvature instability that arises during the crystallization of finite-sized monolayer membranes of chiral colloidal rods. While the bulk of the membrane crystallizes, its edge remains fluid like and exhibits chiral ordering. The resulting internal stresses cause the flat membrane to buckle macroscopically and wrinkle locally. Our results demonstrate an alternate pathway based on intrinsic stresses instead of the usual external ones to assemble non-Euclidean sheets at the colloidal length scale. Buckling and wrinkling are instabilities which involve thin elastic sheets and are well-investigated phenomena at the macroscale. Here Saikia et al. investigate curvature instabilities at the colloidal lengthscale in quasi-2D monolayers of rod-like viruses across the fluid-crystal phase transition.
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15
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Sakhardande R, Stanojeviea S, Baskaran A, Baskaran A, Hagan MF, Chakraborty B. Theory of microphase separation in bidisperse chiral membranes. Phys Rev E 2017; 96:012704. [PMID: 29347212 DOI: 10.1103/physreve.96.012704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Indexed: 04/29/2023]
Abstract
We present a Ginzburg-Landau theory of microphase separation in a bidisperse chiral membrane consisting of rods of opposite handedness. This model system undergoes a phase transition from an equilibrium state where the two components are completely phase separated to a state composed of microdomains of a finite size comparable to the twist penetration depth. Characterizing the phenomenology using linear stability analysis and numerical studies, we trace the origin of the discontinuous change in microdomain size that occurs during this phase transition to a competition between the cost of creating an interface and the gain in twist energy for small microdomains in which the twist penetrates deep into the center of the domain.
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Affiliation(s)
- Raunak Sakhardande
- Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Stefan Stanojeviea
- Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Arvind Baskaran
- Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Aparna Baskaran
- Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Michael F Hagan
- Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Bulbul Chakraborty
- Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
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16
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Jia LL, Zakhary MJ, Dogic Z, Pelcovits RA, Powers TR. Chiral edge fluctuations of colloidal membranes. Phys Rev E 2017; 95:060701. [PMID: 28709244 DOI: 10.1103/physreve.95.060701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Indexed: 06/07/2023]
Abstract
We study edge fluctuations of a flat colloidal membrane comprised of a monolayer of aligned filamentous viruses. Experiments reveal that a peak in the spectrum of the in-plane edge fluctuations arises for sufficiently strong virus chirality. Accounting for internal liquid crystalline degrees of freedom by the length, curvature, and geodesic torsion of the edge, we calculate the spectrum of the edge fluctuations. The theory quantitatively describes the experimental data, demonstrating that chirality couples in-plane and out-of-plane edge fluctuations to produce the peak.
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Affiliation(s)
- Leroy L Jia
- Division of Applied Mathematics, Brown University, Providence, Rhode Island 02912, USA
| | - Mark J Zakhary
- Martin Fisher School of Physics, Brandeis University, 415 South Street, Waltham, Massachusetts 02454, USA
| | - Zvonimir Dogic
- Martin Fisher School of Physics, Brandeis University, 415 South Street, Waltham, Massachusetts 02454, USA
| | - Robert A Pelcovits
- Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA
| | - Thomas R Powers
- School of Engineering and Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA
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17
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Achiral symmetry breaking and positive Gaussian modulus lead to scalloped colloidal membranes. Proc Natl Acad Sci U S A 2017; 114:E3376-E3384. [PMID: 28411214 DOI: 10.1073/pnas.1617043114] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In the presence of a nonadsorbing polymer, monodisperse rod-like particles assemble into colloidal membranes, which are one-rod-length-thick liquid-like monolayers of aligned rods. Unlike 3D edgeless bilayer vesicles, colloidal monolayer membranes form open structures with an exposed edge, thus presenting an opportunity to study elasticity of fluid sheets. Membranes assembled from single-component chiral rods form flat disks with uniform edge twist. In comparison, membranes composed of a mixture of rods with opposite chiralities can have the edge twist of either handedness. In this limit, disk-shaped membranes become unstable, instead forming structures with scalloped edges, where two adjacent lobes with opposite handedness are separated by a cusp-shaped point defect. Such membranes adopt a 3D configuration, with cusp defects alternatively located above and below the membrane plane. In the achiral regime, the cusp defects have repulsive interactions, but away from this limit we measure effective long-ranged attractive binding. A phenomenological model shows that the increase in the edge energy of scalloped membranes is compensated by concomitant decrease in the deformation energy due to Gaussian curvature associated with scalloped edges, demonstrating that colloidal membranes have positive Gaussian modulus. A simple excluded volume argument predicts the sign and magnitude of the Gaussian curvature modulus that is in agreement with experimental measurements. Our results provide insight into how the interplay between membrane elasticity, geometrical frustration, and achiral symmetry breaking can be used to fold colloidal membranes into 3D shapes.
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18
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Kang L, Lubensky TC. Chiral twist drives raft formation and organization in membranes composed of rod-like particles. Proc Natl Acad Sci U S A 2017; 114:E19-E27. [PMID: 27999184 PMCID: PMC5224397 DOI: 10.1073/pnas.1613732114] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lipid rafts are hypothesized to facilitate protein interaction, tension regulation, and trafficking in biological membranes, but the mechanisms responsible for their formation and maintenance are not clear. Insights into many other condensed matter phenomena have come from colloidal systems, whose micron-scale particles mimic basic properties of atoms and molecules but permit dynamic visualization with single-particle resolution. Recently, experiments showed that bidisperse mixtures of filamentous viruses can self-assemble into colloidal monolayers with thermodynamically stable rafts exhibiting chiral structure and repulsive interactions. We quantitatively explain these observations by modeling the membrane particles as chiral liquid crystals. Chiral twist promotes the formation of finite-sized rafts and mediates a repulsion that distributes them evenly throughout the membrane. Although this system is composed of filamentous viruses whose aggregation is entropically driven by dextran depletants instead of phospholipids and cholesterol with prominent electrostatic interactions, colloidal and biological membranes share many of the same physical symmetries. Chiral twist can contribute to the behavior of both systems and may account for certain stereospecific effects observed in molecular membranes.
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Affiliation(s)
- Louis Kang
- Department of Physics & Astronomy, University of Pennsylvania, Philadelphia, PA 19104
| | - Tom C Lubensky
- Department of Physics & Astronomy, University of Pennsylvania, Philadelphia, PA 19104
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19
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Dogic Z. Filamentous Phages As a Model System in Soft Matter Physics. Front Microbiol 2016; 7:1013. [PMID: 27446051 PMCID: PMC4927585 DOI: 10.3389/fmicb.2016.01013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 06/14/2016] [Indexed: 02/04/2023] Open
Abstract
Filamentous phages have unique physical properties, such as uniform particle lengths, that are not found in other model systems of rod-like colloidal particles. Consequently, suspensions of such phages provided powerful model systems that have advanced our understanding of soft matter physics in general and liquid crystals in particular. We described some of these advances. In particular we briefly summarize how suspensions of filamentous phages have provided valuable insight into the field of colloidal liquid crystals. We also describe recent experiments on filamentous phages that have elucidated a robust pathway for assembly of 2D membrane-like materials. Finally, we outline unique structural properties of filamentous phages that have so far remained largely unexplored yet have the potential to further advance soft matter physics and material science.
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Affiliation(s)
- Zvonimir Dogic
- Department of Physics, Brandeis University Waltham, MA, USA
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20
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Xie S, Pelcovits RA, Hagan MF. Probing a self-assembled fd virus membrane with a microtubule. Phys Rev E 2016; 93:062608. [PMID: 27415321 DOI: 10.1103/physreve.93.062608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Indexed: 06/06/2023]
Abstract
The self-assembly of highly anisotropic colloidal particles leads to a rich variety of morphologies whose properties are just beginning to be understood. This article uses computer simulations to probe a particle-scale perturbation of a commonly studied colloidal assembly, a monolayer membrane composed of rodlike fd viruses in the presence of a polymer depletant. Motivated by experiments currently in progress, we simulate the interaction between a microtubule and a monolayer membrane as the microtubule "pokes" and penetrates the membrane face-on. Both the viruses and the microtubule are modeled as hard spherocylinders of the same diameter, while the depletant is modeled using ghost spheres. We find that the force exerted on the microtubule by the membrane is zero either when the microtubule is completely outside the membrane or when it has fully penetrated the membrane. The microtubule is initially repelled by the membrane as it begins to penetrate but experiences an attractive force as it penetrates further. We assess the roles played by translational and rotational fluctuations of the viruses and the osmotic pressure of the polymer depletant. We find that rotational fluctuations play a more important role than the translational ones. The dependence on the osmotic pressure of the depletant of the width and height of the repulsive barrier and the depth of the attractive potential well is consistent with the assumed depletion-induced attractive interaction between the microtubule and viruses. We discuss the relevance of these studies to the experimental investigations.
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Affiliation(s)
- Sheng Xie
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
| | - Robert A Pelcovits
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
| | - Michael F Hagan
- Department of Physics, Brandeis University, Waltham, Massachusetts 02454, USA
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21
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Xie S, Hagan MF, Pelcovits RA. Interaction of chiral rafts in self-assembled colloidal membranes. Phys Rev E 2016; 93:032706. [PMID: 27078426 DOI: 10.1103/physreve.93.032706] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Indexed: 06/05/2023]
Abstract
Colloidal membranes are monolayer assemblies of rodlike particles that capture the long-wavelength properties of lipid bilayer membranes on the colloidal scale. Recent experiments on colloidal membranes formed by chiral rodlike viruses showed that introducing a second species of virus with different length and opposite chirality leads to the formation of rafts--micron-sized domains of one virus species floating in a background of the other viruses [Sharma et al., Nature (London) 513, 77 (2014)]. In this article we study the interaction of such rafts using liquid crystal elasticity theory. By numerically minimizing the director elastic free energy, we predict the tilt angle profile for both a single raft and two rafts in a background membrane, and the interaction between two rafts as a function of their separation. We find that the chiral penetration depth in the background membrane sets the scale for the range of the interaction. We compare our results with the experimental data and find good agreement for the strength and range of the interaction. Unlike the experiments, however, we do not observe a complete collapse of the data when rescaled by the tilt angle at the raft edge.
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Affiliation(s)
- Sheng Xie
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
| | - Michael F Hagan
- Department of Physics, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Robert A Pelcovits
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
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22
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Kang L, Gibaud T, Dogic Z, Lubensky TC. Entropic forces stabilize diverse emergent structures in colloidal membranes. SOFT MATTER 2016; 12:386-401. [PMID: 26472139 DOI: 10.1039/c5sm02038g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The depletion interaction mediated by non-adsorbing polymers promotes condensation and assembly of repulsive colloidal particles into diverse higher-order structures and materials. One example, with particularly rich emergent behaviors, is the formation of two-dimensional colloidal membranes from a suspension of filamentous fd viruses, which act as rods with effective repulsive interactions, and dextran, which acts as a condensing, depletion-inducing agent. Colloidal membranes exhibit chiral twist even when the constituent virus mixture lacks macroscopic chirality, change from a circular shape to a striking starfish shape upon changing the chirality of constituent rods, and partially coalesce via domain walls through which the viruses twist by 180°. We formulate an entropically-motivated theory that can quantitatively explain these experimental structures and measurements, both previously published and newly performed, over a wide range of experimental conditions. Our results elucidate how entropy alone, manifested through the viruses as Frank elastic energy and through the depletants as an effective surface tension, drives the formation and behavior of these diverse structures. Our generalizable principles propose the existence of analogous effects in molecular membranes and can be exploited in the design of reconfigurable colloidal structures.
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Affiliation(s)
- Louis Kang
- Department of Physics & Astronomy, University of Pennsylvania, 203 South 33rd Street, Philadelphia, Pennsylvania 19104, USA.
| | - Thomas Gibaud
- Laboratoire de Physique, École Normale Supérieure de Lyon, Université de Lyon, CNRS/UMR 5672, 46 allée d'Italie, 69007 Lyon, France
| | - Zvonimir Dogic
- The Martin Fisher School of Physics, Brandeis University, 415 South Street, Waltham, Massachusetts 02454, USA
| | - T C Lubensky
- Department of Physics & Astronomy, University of Pennsylvania, 203 South 33rd Street, Philadelphia, Pennsylvania 19104, USA.
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23
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Modlińska A, Alsayed AM, Gibaud T. Condensation and dissolution of nematic droplets in dispersions of colloidal rods with thermo-sensitive depletants. Sci Rep 2015; 5:18432. [PMID: 26656207 PMCID: PMC4995677 DOI: 10.1038/srep18432] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/18/2015] [Indexed: 01/08/2023] Open
Abstract
Nematic droplets are droplets composed of elongated molecules that tend to point in the same direction but do not have any positional order. Such droplets are well known to adopt a spindle shape called tactoid. How such droplets condensate or melt and how the orientational symmetry is broken remains however unclear. Here we use a colloidal system composed of filamentous viruses as model rod-like colloids and pnipam microgel particles to induce thermo-sensitive depletion attraction between the rods. Microscopy experiments coupled to particle tracking reveal that the condensation of a nematic droplet is preceded by the formation of a new phase, an isotropic droplet. As the viruses constitute an excellent experimental realization of hard rods, it follows that the phenomenology we describe should be relevant to diverse micro- and nano-sized rods that interact through excluded volume interactions. This transition between isotropic and nematic droplets provides a new and reversible pathway to break the symmetry and order colloidal rods within a droplet with an external stimulus, and could constitute a benchmark experiment for a variety of technologies relying on reconfigurable control of rods.
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Affiliation(s)
- Anna Modlińska
- Labaroire de physique, CNRS/UMR 5672, Ecole Normale Supérieure de Lyon – Université de Lyon, 46 allée d’Italie, 69007 Lyon, France
- Faculty of Technical Physics, Poznan University of Technology, ul. Piotrowo 3, 60-965 Poznań, Poland
| | - Ahmed M. Alsayed
- Complex Assemblies of Soft Matter (COMPASS), Solvay-CNRS-UPenn UMI 3254, Bristol, Pennsylvania 19007, USA
| | - Thomas Gibaud
- Labaroire de physique, CNRS/UMR 5672, Ecole Normale Supérieure de Lyon – Université de Lyon, 46 allée d’Italie, 69007 Lyon, France
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24
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Castles F. Liquid crystal research highlights. LIQUID CRYSTALS TODAY 2015. [DOI: 10.1080/1358314x.2014.973268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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25
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Hierarchical organization of chiral rafts in colloidal membranes. Nature 2014; 513:77-80. [DOI: 10.1038/nature13694] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 07/14/2014] [Indexed: 11/08/2022]
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26
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Cheng Y, Zheng F, Lu J, Shang L, Xie Z, Zhao Y, Chen Y, Gu Z. Bioinspired multicompartmental microfibers from microfluidics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:5184-90. [PMID: 24934291 DOI: 10.1002/adma.201400798] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/24/2014] [Indexed: 05/23/2023]
Abstract
Bioinspired multicompartmental microfibers are generated by novel capillary microfluidics. The resultant microfibers possess multicompartment body-and-shell compositions with specifically designed geometries. Potential use of these microfibers for tissue-engineering applications is demonstrated by creating multifunctional fibers with a spatially controlled encapsulation of cells.
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Affiliation(s)
- Yao Cheng
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing, 210096, China
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27
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Kaplan CN, Meyer RB. Colloidal membranes of hard rods: unified theory of free edge structure and twist walls. SOFT MATTER 2014; 10:4700-4710. [PMID: 24852267 DOI: 10.1039/c4sm00803k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Monodisperse suspensions of rod like chiral fd viruses are condensed into a rod-length thick colloidal monolayers of aligned rods by depletion forces. Twist deformations of the molecules are expelled to the monolayer edge as in a chiral smectic A liquid crystal, and a cholesteric band forms at the edge. Coalescence of two such isolated membranes results in a twist wall sandwiched between two regions of aligned rods, dubbed π-walls. By modeling the membrane as a binary fluid of coexisting cholesteric and chiral smectic A liquid-crystalline regions, we develop a unified theory of the π-walls and the monolayer edge. The mean-field analysis of our model yields the molecular tilt profiles, the local thickness change, and the crossover from smectic to cholesteric behavior at the monolayer edge and across the π-wall. Furthermore, we calculate the line tension associated with the formation of these interfaces. Our model offers insights regarding the stability and the detailed structure of the π-wall and the monolayer edge.
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Affiliation(s)
- C Nadir Kaplan
- The Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02454, USA.
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28
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Castles F. Liquid crystal research highlights. LIQUID CRYSTALS TODAY 2014. [DOI: 10.1080/1358314x.2014.912385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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