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Wang Z, Yu H, Liyanage A, Qiu J, Thushara D, Bao B, Zhao S. Collective diffusion of charged nanoparticles in microchannel under electric field. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2021.117264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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2
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Trinh Che L, Hiorth M, Hoogenboom R, Kjøniksen AL. Complex Temperature and Concentration Dependent Self-Assembly of Poly(2-oxazoline) Block Copolymers. Polymers (Basel) 2020; 12:polym12071495. [PMID: 32635506 PMCID: PMC7407653 DOI: 10.3390/polym12071495] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/24/2020] [Accepted: 06/26/2020] [Indexed: 11/17/2022] Open
Abstract
The effect of polymer concentration on the temperature-induced self-association of a block copolymer comprising a poly(2-ethyl-2-oxazoline) block and a random copolymer block consisting of 2-ethyl-2-oxazoline and 2-n-propyl-2-oxazoline (PEtO80-block-P(EtOxx-stat-PropO40-x) with x = 0, 4, or 8 were investigated by dynamic light scattering (DLS) and transmittance measurements (turbidimetry). The polymers reveal a complex aggregation behavior with up to three relaxation modes in the DLS data and with a transmittance that first goes through a minimum before it declines at high temperatures. At low temperatures, unassociated polymer chains were found to co-exist with larger aggregates. As the temperature is increased, enhanced association and contraction of the aggregates results in a drop of the transmittance values. The aggregates fragment into smaller micellar-like clusters when the temperature is raised further, causing the samples to become optically clear again. At high temperatures, the polymers aggregate into large compact clusters, and the samples become turbid. Interestingly, very large aggregates were observed at low temperatures when the polymer concentrations were low. The formation of these aggregates was also promoted by a more hydrophilic copolymer structure. The formation of large aggregates with an open structure at conditions where the solvent conditions are improved is probably caused by depletion flocculation of the smaller aggregates.
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Affiliation(s)
- Loan Trinh Che
- Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, 0315 Oslo, Norway;
| | - Marianne Hiorth
- Department of Pharmacy, School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway;
| | - Richard Hoogenboom
- Supramolecular Chemistry Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4, B-9000 Ghent, Belgium
- Correspondence: (R.H.); (A.-L.K.)
| | - Anna-Lena Kjøniksen
- Faculty of Engineering, Østfold University College, P.O. Box 700, 1757 Halden, Norway
- Correspondence: (R.H.); (A.-L.K.)
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3
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Controlling the material properties and rRNA processing function of the nucleolus using light. Proc Natl Acad Sci U S A 2019; 116:17330-17335. [PMID: 31399547 DOI: 10.1073/pnas.1903870116] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The nucleolus is a prominent nuclear condensate that plays a central role in ribosome biogenesis by facilitating the transcription and processing of nascent ribosomal RNA (rRNA). A number of studies have highlighted the active viscoelastic nature of the nucleolus, whose material properties and phase behavior are a consequence of underlying molecular interactions. However, the ways in which the material properties of the nucleolus impact its function in rRNA biogenesis are not understood. Here we utilize the Cry2olig optogenetic system to modulate the viscoelastic properties of the nucleolus. We show that above a threshold concentration of Cry2olig protein, the nucleolus can be gelled into a tightly linked, low mobility meshwork. Gelled nucleoli no longer coalesce and relax into spheres but nonetheless permit continued internal molecular mobility of small proteins. These changes in nucleolar material properties manifest in specific alterations in rRNA processing steps, including a buildup of larger rRNA precursors and a depletion of smaller rRNA precursors. We propose that the flux of processed rRNA may be actively tuned by the cell through modulating nucleolar material properties, which suggests the potential of materials-based approaches for therapeutic intervention in ribosomopathies.
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4
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Phase behaviour of disordered proteins underlying low density and high permeability of liquid organelles. Nat Chem 2017; 9:1118-1125. [PMID: 29064502 DOI: 10.1038/nchem.2803] [Citation(s) in RCA: 366] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 05/05/2017] [Indexed: 12/29/2022]
Abstract
Many intracellular membraneless organelles form via phase separation of intrinsically disordered proteins (IDPs) or regions (IDRs). These include the Caenorhabditis elegans protein LAF-1, which forms P granule-like droplets in vitro. However, the role of protein disorder in phase separation and the macromolecular organization within droplets remain elusive. Here, we utilize a novel technique, ultrafast-scanning fluorescence correlation spectroscopy, to measure the molecular interactions and full coexistence curves (binodals), which quantify the protein concentration within LAF-1 droplets. The binodals of LAF-1 and its IDR display a number of unusual features, including 'high concentration' binodal arms that correspond to remarkably dilute droplets. We find that LAF-1 and other in vitro and intracellular droplets are characterized by an effective mesh size of ∼3-8 nm, which determines the size scale at which droplet properties impact molecular diffusion and permeability. These findings reveal how specific IDPs can phase separate to form permeable, low-density (semi-dilute) liquids, whose structural features are likely to strongly impact biological function.
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Junio J, Cohen JA, Ou-Yang HD. Osmotic Bulk Modulus of Charged Colloids Measured by Ensemble Optical Trapping. J Phys Chem B 2016; 120:9187-94. [PMID: 27348273 DOI: 10.1021/acs.jpcb.6b05608] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The optical-bottle technique is used to measure osmotic bulk moduli of colloid suspensions. The bulk modulus is determined by optically trapping an ensemble of nanoparticles and invoking a steady-state force balance between confining optical-gradient forces and repulsive osmotic-pressure forces. Osmotic bulk moduli are reported for aqueous suspensions of charged polystyrene particles in NaCl solutions as a function of particle concentration and ionic strength, and are compared to those determined by turbidity measurements under the same conditions. Effective particle charges are calculated from the bulk moduli and are found to increase as a function of ionic strength, consistent with previously reported results.
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Affiliation(s)
- Joseph Junio
- Department of Physics, Lehigh University , Bethlehem, Pennsylvania 18015, United States
| | - Joel A Cohen
- Department of Physics, University of Massachusetts , Amherst, Massachusetts 01003, United States
| | - H Daniel Ou-Yang
- Department of Physics, Lehigh University , Bethlehem, Pennsylvania 18015, United States
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6
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Panczyk T, Konczak L, Zapotoczny S, Szabelski P, Nowakowska M. Molecular dynamics simulations of proton transverse relaxation times in suspensions of magnetic nanoparticles. J Colloid Interface Sci 2015; 437:187-196. [DOI: 10.1016/j.jcis.2014.08.066] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 08/27/2014] [Accepted: 08/29/2014] [Indexed: 11/16/2022]
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7
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Arzenšek D, Kuzman D, Podgornik R. Colloidal interactions between monoclonal antibodies in aqueous solutions. J Colloid Interface Sci 2012; 384:207-16. [DOI: 10.1016/j.jcis.2012.06.055] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 06/01/2012] [Accepted: 06/02/2012] [Indexed: 12/20/2022]
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8
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Trinh LTT, Lambermont-Thijs HML, Schubert US, Hoogenboom R, Kjøniksen AL. Thermoresponsive Poly(2-oxazoline) Block Copolymers Exhibiting Two Cloud Points: Complex Multistep Assembly Behavior. Macromolecules 2012. [DOI: 10.1021/ma300570j] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Loan T. T. Trinh
- Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo,
Norway
| | - Hanneke M. L. Lambermont-Thijs
- Laboratory of Macromolecular
Chemistry and Nanoscience, Eindhoven University of Technology, Den Dolech 2, 5612AZ Eindhoven, The Netherlands
| | - Ulrich S. Schubert
- Laboratory of Macromolecular
Chemistry and Nanoscience, Eindhoven University of Technology, Den Dolech 2, 5612AZ Eindhoven, The Netherlands
- Laboratory of Organic and Macromolecular
Chemistry (IOMC) and Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University Jena, Humboldtstr. 10,
07743 Jena, Germany
| | - Richard Hoogenboom
- Supramolecular
Chemistry Group,
Department of Organic Chemistry, Ghent University, Krijgslaan 281 S4, B-9000 Ghent, Belgium
| | - Anna-Lena Kjøniksen
- Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo,
Norway
- Department of Pharmacy, School
of Pharmacy, University of Oslo, P.O. Box
1068, Blindern, 0316 Oslo, Norway
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Gebauer JS, Treuel L. Influence of individual ionic components on the agglomeration kinetics of silver nanoparticles. J Colloid Interface Sci 2010; 354:546-54. [PMID: 21146829 DOI: 10.1016/j.jcis.2010.11.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Revised: 10/25/2010] [Accepted: 11/09/2010] [Indexed: 10/18/2022]
Abstract
The precise characteristic of the agglomeration behavior of colloidal suspensions is of paramount interest to many current studies in nanoscience. This work seeks to elucidate the influence that differently charged salts have on the agglomeration state of a Lee-Meisel-type silver colloid. Moreover, we investigate the influence of the chemical nature of individual ions on their potential to induce agglomeration. Raman spectroscopy and surface-enhanced Raman spectroscopy are used to give insights into mechanistic aspects of the agglomeration process and to assess the differences in the influence of different salts on the agglomeration behavior. Finally, we demonstrate the potential of the measurement procedure used in this work to determine the elementary charge on colloidal NPs.
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Affiliation(s)
- J S Gebauer
- Institute for Physical Chemistry and Centre for Water and Environmental Research, University of Duisburg-Essen, Universitaetsstrasse 5-7, 45117 Essen, Germany
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Ghofraniha N, Ruocco G, Conti C. Collective thermal diffusion of silica colloids studied by nonlinear optics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:12495-500. [PMID: 19817352 DOI: 10.1021/la9017272] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We investigate the collective thermal diffusion of silica charged spheres in Sulpho-Rhodamine B/water solution at different concentrations by measuring time-dependent thermal and Soret lensings. We show a significant concentration-dependence of the thermal diffusion coefficient D(T), not previously reported. Moreover, the results clearly show that both mass diffusion and Soret coefficient are collective quantities being strongly dependent on the particles' packing fraction. Our Z-scan setup allows us to investigate the dynamics of the system at low wave vector, which addresses the influence of the interparticle interactions on the thermal diffusion of the colloids.
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Affiliation(s)
- Neda Ghofraniha
- Dipartimento di Fisica - Universita' La Sapienza, Piazzale Aldo Moro 5, 00185, Rome, Italy.
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Calibration-free concentration determination of charged colloidal nanoparticles and determination of effective charges by capillary isotachophoresis. Anal Bioanal Chem 2009; 395:1681-91. [DOI: 10.1007/s00216-009-2887-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 05/29/2009] [Accepted: 06/03/2009] [Indexed: 10/20/2022]
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12
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d’Orlyé F, Varenne A, Gareil P. Determination of nanoparticle diffusion coefficients by Taylor dispersion analysis using a capillary electrophoresis instrument. J Chromatogr A 2008; 1204:226-32. [DOI: 10.1016/j.chroma.2008.08.008] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Revised: 08/01/2008] [Accepted: 08/04/2008] [Indexed: 11/24/2022]
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McPhie MG, Nägele G. Long-time self-diffusion of charged colloidal particles: electrokinetic and hydrodynamic interaction effects. J Chem Phys 2007; 127:034906. [PMID: 17655462 DOI: 10.1063/1.2753839] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The authors analyze the long-time self-diffusion of charge-stabilized colloidal macroions in nondilute suspensions using a mode-coupling scheme developed for multicomponent suspensions of interacting Brownian spheres. In this scheme, all ionic species, including counterions and electrolyte ions, are treated on an equal footing as charged hard spheres undergoing overdamped Brownian motion. Hydrodynamic interactions between all ions are accounted for on the far-field level. We show that the influence on the colloidal long-time self-diffusion coefficient arising from the relaxation of the microionic atmosphere surrounding the colloids, the so-called electrolyte friction effect, is usually insignificant in comparison with the friction contributions arising from direct and hydrodynamic interactions between the colloidal particles. This finding is true even for small colloid concentrations unless the mobility difference between colloidal particles and microions is not large. Furthermore, we observe an interesting nonmonotonic density dependence of the colloidal long-time self-diffusion coefficient in suspensions with low amount of added salt. We show that this unusual density dependence is due to colloid-colloid hydrodynamic interactions.
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Affiliation(s)
- Mathieu G McPhie
- Institut für Festkörperforschung, Teilinstitut Weiche Materie, Forschungszentrum Jülich, D-52425 Jülich, Germany.
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Gapinski J, Patkowski A, Banchio AJ, Holmqvist P, Meier G, Lettinga MP, Nägele G. Collective diffusion in charge-stabilized suspensions: Concentration and salt effects. J Chem Phys 2007; 126:104905. [PMID: 17362085 DOI: 10.1063/1.2538891] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The authors present a joint experimental-theoretical study of collective diffusion properties in aqueous suspensions of charge-stabilized fluorinated latex spheres. Small-angle x-ray scattering and x-ray photon correlation spectroscopy have been used to explore the concentration and ionic-strength dependence of the static and short-time dynamic properties including the hydrodynamic function H(q), the wave-number-dependent collective diffusion coefficient D(q), and the intermediate scattering function over the entire accessible range. They show that all experimental data can be quantitatively described and explained by means of a recently developed accelerated Stokesian dynamics simulation method, in combination with a modified hydrodynamic many-body theory. In particular, the behavior of H(q) for de-ionized and dense suspensions can be attributed to the influence of many-body hydrodynamics, without any need for postulating hydrodynamic screening to be present, as it was done in earlier work. Upper and lower boundaries are provided for the peak height of the hydrodynamic function and for the short-time self-diffusion coefficient over the entire range of added salt concentrations.
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Affiliation(s)
- J Gapinski
- Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznan, Poland
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15
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Gapinski J, Wilk A, Patkowski A, Häussler W, Banchio AJ, Pecora R, Nägele G. Diffusion and microstructural properties of solutions of charged nanosized proteins: Experiment versus theory. J Chem Phys 2005; 123:054708. [PMID: 16108686 DOI: 10.1063/1.1996569] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have reanalyzed our former static small-angle x-ray scattering and photon correlation spectroscopy results on dense solutions of charged spherical apoferritin proteins using theories recently developed for studies of colloids. The static structure factors S(q), and the small-wave-number collective diffusion coefficient D(c) determined from those experiments are interpreted now in terms of a theoretical scheme based on a Derjaguin-Landau-Verwey-Overbeek-type continuum model of charged colloidal spheres. This scheme accounts, in an approximate way, for many-body hydrodynamic interactions. Stokesian dynamics computer simulations of the hydrodynamic function have been performed for the first time for dense charge-stabilized dispersions to assess the accuracy of the theoretical scheme. We show that the continuum model allows for a consistent description of all experimental results, and that the effective particle charge is dependent upon the protein concentration relative to the added salt concentration. In addition, we discuss the consequences of small ions dynamics for the collective protein diffusion within the framework of the coupled-mode theory.
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Affiliation(s)
- J Gapinski
- Institute of Physics, A. Mickiewicz University, 61-614 Poznan, Poland.
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