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García Daza FA, Puertas AM, Cuetos A, Patti A. Insight into the Viscoelasticity of Self-Assembling Smectic Liquid Crystals of Colloidal Rods from Active Microrheology Simulations. J Chem Theory Comput 2024; 20:1579-1589. [PMID: 37390389 PMCID: PMC10902840 DOI: 10.1021/acs.jctc.3c00356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2023]
Abstract
The rheology of colloidal suspensions is of utmost importance in a wide variety of interdisciplinary applications in formulation technology, determining equally interesting questions in fundamental science. This is especially intriguing when colloids exhibit a degree of long-range positional or orientational ordering, as in liquid crystals (LCs) of elongated particles. Along with standard methods, microrheology (MR) has emerged in recent years as a tool to assess the mechanical properties of materials at the microscopic level. In particular, by active MR one can infer the viscoelastic response of a soft material from the dynamics of a tracer particle being dragged through it by external forces. Although considerable efforts have been made to study the diffusion of guest particles in LCs, little is known about the combined effect of tracer size and directionality of the dragging force on the system's viscoelastic response. By dynamic Monte Carlo simulations, we apply active MR to investigate the viscoelasticity of self-assembling smectic (Sm) LCs consisting of rodlike particles. In particular, we track the motion of a spherical tracer whose size is varied within a range of values matching the system's characteristic length scales and being dragged by constant forces that are parallel, perpendicular, or at 45° to the nematic director. Our results reveal a uniform value of the effective friction coefficient as probed by the tracer at small and large forces, whereas a nonlinear, force-thinning regime is observed at intermediate forces. However, at relatively weak forces the effective friction is strongly determined by correlations between the tracer size and the structure of the host fluid. Moreover, we also show that external forces forming an angle with the nematic director provide additional details that cannot be simply inferred from the mere analysis of parallel and perpendicular forces. Our results highlight the fundamental interplay between tracer size and force direction in assessing the MR of Sm LC fluids.
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Affiliation(s)
- Fabián A García Daza
- Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, 41013 Sevilla, Spain
- Department of Chemical Engineering, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Antonio M Puertas
- Department of Chemistry and Physics, University of Almeriá, 04120 Almería, Spain
| | - Alejandro Cuetos
- Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, 41013 Sevilla, Spain
| | - Alessandro Patti
- Department of Chemical Engineering, The University of Manchester, Manchester M13 9PL, United Kingdom
- Department of Applied Physics, University of Granada, Avenida Fuente Nueva s/n, 18071 Granada, Spain
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Goral M, Clement E, Darnige T, Lopez-Leon T, Lindner A. Frustrated 'run and tumble' of swimming Escherichia coli bacteria in nematic liquid crystals. Interface Focus 2022; 12:20220039. [PMID: 36330319 PMCID: PMC9560793 DOI: 10.1098/rsfs.2022.0039] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 09/05/2022] [Indexed: 10/16/2023] Open
Abstract
In many situations, bacteria move in complex environments, as soils, oceans or the human gut-track, where carrier fluids show complex structures associated with non-Newtonian rheology. Many fundamental questions concerning the ability to navigate in such environments remain unsolved. Recently, it has been shown that the kinetics of bacterial motion in structured fluids as liquid crystals (LCs) is constrained by the orientational molecular order (or director field) and that novel spatio-temporal patterns arise. A question unaddressed so far is how bacteria change swimming direction in such an environment. In this work, we study the swimming mechanism of a single bacterium, Esherichia coli, constrained to move along the director field of a lyotropic chromonic liquid crystal confined to a planar cell. Here, the spontaneous 'run and tumble' motion of the bacterium gets frustrated: the elasticity of the LC prevents flagella from unbundling. Interestingly, to change direction, bacteria execute a reversal motion along the director field, driven by the relocation of a single flagellum, a 'frustrated tumble'. We characterize this phenomenon in detail experimentally, exploiting exceptional spatial and temporal resolution of bacterial and flagellar dynamics, using a two colour Lagrangian tracking technique. We suggest a possible mechanism accounting for these observations.
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Affiliation(s)
- Martyna Goral
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes, UMR 7636, CNRS, ESPCI Paris-PSL, Sorbonne Université, Université Paris Cité, 75005 Paris, France
- Laboratoire Gulliver, UMR 7083, CNRS, ESPCI Paris-PSL, 75005 Paris, France
| | - Eric Clement
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes, UMR 7636, CNRS, ESPCI Paris-PSL, Sorbonne Université, Université Paris Cité, 75005 Paris, France
- Institut Universitaire de France (IUF), Paris, France
| | - Thierry Darnige
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes, UMR 7636, CNRS, ESPCI Paris-PSL, Sorbonne Université, Université Paris Cité, 75005 Paris, France
| | - Teresa Lopez-Leon
- Laboratoire Gulliver, UMR 7083, CNRS, ESPCI Paris-PSL, 75005 Paris, France
| | - Anke Lindner
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes, UMR 7636, CNRS, ESPCI Paris-PSL, Sorbonne Université, Université Paris Cité, 75005 Paris, France
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García Daza FA, Puertas AM, Cuetos A, Patti A. Microrheology of isotropic and liquid-crystalline phases of hard rods by dynamic Monte Carlo simulations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Rafael EM, Tonti L, Daza FAG, Patti A. Active microrheology of colloidal suspensions of hard cuboids. Phys Rev E 2022; 106:034612. [PMID: 36266794 DOI: 10.1103/physreve.106.034612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 08/31/2022] [Indexed: 06/16/2023]
Abstract
By performing dynamic Monte Carlo simulations, we investigate the microrheology of isotropic suspensions of hard-core colloidal cuboids. In particular, we infer the local viscoelastic behavior of these fluids by studying the dynamics of a probe spherical particle that is incorporated in the host phase and is dragged by an external force. This technique, known as active microrheology, allows one to characterize the microscopic response of soft materials upon application of a constant force, whose intensity spans here three orders of magnitude. By tuning the geometry of cuboids from oblate to prolate as well as the system density, we observe different responses that are quantified by measuring the effective friction perceived by the probe particle. The resulting friction coefficient exhibits a linear regime at forces that are much weaker and larger than the thermal forces, whereas a nonlinear, force-thinning regime is observed at intermediate force intensities.
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Affiliation(s)
- Effran Mirzad Rafael
- Department of Chemical Engineering, The University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Luca Tonti
- Department of Chemical Engineering, The University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Fabián A García Daza
- Department of Chemical Engineering, The University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Alessandro Patti
- Department of Chemical Engineering, The University of Manchester, Manchester, M13 9PL, United Kingdom
- Department of Applied Physics, University of Granada, Avenida Fuente Nueva s/n, 18071 Granada, Spain
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Berezney JP, Valentine MT. A compact rotary magnetic tweezers device for dynamic material analysis. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:093701. [PMID: 36182480 DOI: 10.1063/5.0090199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 07/18/2022] [Indexed: 06/16/2023]
Abstract
Here we present a new, compact magnetic tweezers design that enables precise application of a wide range of dynamic forces to soft materials without the need to raise or lower the magnet height above the sample. This is achieved through the controlled rotation of the permanent magnet array with respect to the fixed symmetry axis defined by a custom-built iron yoke. These design improvements increase the portability of the device and can be implemented within existing microscope setups without the need for extensive modification of the sample holders or light path. This device is particularly well-suited to active microrheology measurements using either creep analysis, in which a step force is applied to a micron-sized magnetic particle that is embedded in a complex fluid, or oscillatory microrheology, in which the particle is driven with a periodic waveform of controlled amplitude and frequency. In both cases, the motions of the particle are measured and analyzed to determine the local dynamic mechanical properties of the material.
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Affiliation(s)
- John P Berezney
- Mechanical Engineering Department, University of California, Santa Barbara, California 93106, USA
| | - Megan T Valentine
- Mechanical Engineering Department, University of California, Santa Barbara, California 93106, USA
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Yang X, Sui H, Liang H, Li J, Li B. Effects of M/G Ratios of Sodium Alginate on Physicochemical Stability and Calcium Release Behavior of Pickering Emulsion Stabilized by Calcium Carbonate. Front Nutr 2022; 8:818290. [PMID: 35087860 PMCID: PMC8786712 DOI: 10.3389/fnut.2021.818290] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 12/10/2021] [Indexed: 11/23/2022] Open
Abstract
The gel properties of sodium alginate (SA) have been revealed to be strongly correlated with its ratio of D-mannuronate to L-guluronate (M/G ratio). Herein, we focused on SA with different M/G ratios to conduct an in-depth study on the effect of the M/G ratio difference on physicochemical stability and calcium release behavior of the Pickering emulsion stabilized by calcium carbonate (CaCO3). The oil phase was added to the aqueous phase, prepared by SA with different M/G ratios (2.23, 0.89, and 0.56) and CaCO3, for one-step shearing to obtain the E1, E2, and E3 emulsions, respectively. The results of the particle size, microstructure, long-term stability, rheological, and microrheological properties of the emulsions showed that the E3 emulsion, prepared by SA with a smaller M/G ratio, had a smaller particle size and has remained in a flow condition during the long-term storage, while the E1 and E2 emulsions had a gelation behavior and a stronger viscoelasticity. Moreover, the emulsion, as a liquid calcium supplement, is not only convenient for oral intake while meeting the calcium needs of the body, but also controls the release of Ca2+. The calcium release of the emulsions in a simulated gastric environment demonstrated that the calcium release ratio increased with the decrease of SA concentration, with the increase of M/G ratio, and with the decrease of oil phase volume.
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Affiliation(s)
- Xiaotong Yang
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Haomin Sui
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Hongshan Liang
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jing Li
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Bin Li
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China
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Tonti L, García Daza FA, Patti A. Diffusion of globular macromolecules in liquid crystals of colloidal cuboids. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116640] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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García Daza FA, Puertas AM, Cuetos A, Patti A. Microrheology of colloidal suspensions via dynamic Monte Carlo simulations. J Colloid Interface Sci 2021; 605:182-192. [PMID: 34325340 DOI: 10.1016/j.jcis.2021.07.088] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 11/20/2022]
Abstract
Understanding the rheology of colloidal suspensions is crucial in the formulation of a wide selection of industry-relevant products, such as paints, foods and inks. To characterise the viscoelastic behaviour of these soft materials, one can analyse the microscopic dynamics of colloidal tracers diffusing through the host fluid and generating local deformations and stresses. This technique, referred to as microrheology, links the bulk rheology of fluids to the microscopic dynamics at the particle scale. If tracers are subjected to external forces, rather than freely diffusing, it is called active microrheology. Motivated by the impact of microrheology in providing information on local structure in complex systems such as colloidal glasses, active matter or biological systems, we have extended the dynamic Monte Carlo (DMC) technique to investigate active microrheology in colloidal suspensions. The original DMC theoretical framework, able to accurately describe the Brownian dynamics of colloids at equilibrium, is here reconsidered and expanded to describe the effects of an external force pulling a tracer embedded in isotropic colloidal suspensions at different densities. To this end, we studied the dynamics of a spherical tracer dragged by a constant external force through a bath of spherical and rod-like particles of comparable size. We could extract valuable details on its effective friction coefficient, being constant at small and large values of the external force, but otherwise displaying a nonlinear behaviour that indicates the occurrence of a force-thinning regime. Our DMC simulation results are in excellent quantitative agreement with past Langevin dynamics simulations and theoretical works for the bath of spherical colloids. The bath of rod-like particles is studied in the isotropic phase, and displays an example where DMC is more convenient than Brownian or Langevin dynamics, in this case, in dealing with particle rotation.
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Affiliation(s)
- Fabián A García Daza
- Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, UK.
| | - Antonio M Puertas
- Department of Chemistry and Physics, University of Almería, 04120 Almería, Spain
| | - Alejandro Cuetos
- Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, 41013 Sevilla, Spain
| | - Alessandro Patti
- Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, UK.
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Baza H, Turiv T, Li BX, Li R, Yavitt BM, Fukuto M, Lavrentovich OD. Shear-induced polydomain structures of nematic lyotropic chromonic liquid crystal disodium cromoglycate. SOFT MATTER 2020; 16:8565-8576. [PMID: 32785364 DOI: 10.1039/d0sm01259a] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Lyotropic chromonic liquid crystals (LCLCs) represent aqueous dispersions of organic disk-like molecules that form cylindrical aggregates. Despite the growing interest in these materials, their flow behavior is poorly understood. Here, we explore the effect of shear on dynamic structures of the nematic LCLC, formed by 14 wt% water dispersion of disodium cromoglycate (DSCG). We employ in situ polarizing optical microscopy (POM) and small-angle and wide-angle X-ray scattering (SAXS/WAXS) to obtain independent and complementary information on the director structures over a wide range of shear rates. The DSCG nematic shows a shear-thinning behavior with two shear-thinning regions (Region I at [small gamma, Greek, dot above] < 1 s-1 and Region III at [small gamma, Greek, dot above] > 10 s-1) separated by a pseudo-Newtonian Region II (1 s-1 < [small gamma, Greek, dot above] < 10 s-1). The material is of a tumbling type. In Region I, [small gamma, Greek, dot above] < 1 s-1, the director realigns along the vorticity axis. An increase of [small gamma, Greek, dot above] above 1 s-1 triggers nucleation of disclination loops. The disclinations introduce patches of the director that deviates from the vorticity direction and form a polydomain texture. Extension of the domains along the flow and along the vorticity direction decreases with the increase of the shear rate to 10 s-1. Above 10 s-1, the domains begin to elongate along the flow. At [small gamma, Greek, dot above] > 100 s-1, the texture evolves into periodic stripes in which the director is predominantly along the flow with left and right tilts. The period of stripes decreases with an increase of [small gamma, Greek, dot above]. The shear-induced transformations are explained by the balance of the elastic and viscous energies. In particular, nucleation of disclinations is associated with an increase of the elastic energy at the walls separating nonsingular domains with different director tilts. The uncovered shear-induced structural effects would be of importance in the further development of LCLC applications.
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Affiliation(s)
- Hend Baza
- Department of Physics, Kent State University, Kent, OH 44242, USA. and Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA
| | - Taras Turiv
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA and Materials Science Graduate Program, Kent State University, Kent, OH 44242, USA
| | - Bing-Xiang Li
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA and Materials Science Graduate Program, Kent State University, Kent, OH 44242, USA
| | - Ruipeng Li
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Benjamin M Yavitt
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA and Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NY 11794, USA
| | - Masafumi Fukuto
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Oleg D Lavrentovich
- Department of Physics, Kent State University, Kent, OH 44242, USA. and Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA and Materials Science Graduate Program, Kent State University, Kent, OH 44242, USA
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