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Lopez CG, Horkay F, Schweins R, Richtering W. Solution Properties of Polyelectrolytes with Divalent Counterions. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Carlos G. Lopez
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, Aachen 52056, Germany
| | - Ferenc Horkay
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 13 South Drive, Bethesda, Maryland 20892, United States
| | - Ralf Schweins
- Institut Laue-Langevin, DS/LSS, 71 Avenue des Martyrs, CS 20156, Grenoble Cedex 9 38042, France
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, Aachen 52056, Germany
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Lin C, Qiang X, Dong HL, Huo J, Tan ZJ. Multivalent Ion-Mediated Attraction between Like-Charged Colloidal Particles: Nonmonotonic Dependence on the Particle Charge. ACS OMEGA 2021; 6:9876-9886. [PMID: 33869968 PMCID: PMC8047654 DOI: 10.1021/acsomega.1c00613] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 03/26/2021] [Indexed: 06/12/2023]
Abstract
Ion-mediated effective interactions are important for the structure and stability of charged particles such as colloids and nucleic acids. It has been known that the intrinsic electrostatic repulsion between like-charged particles can be modulated into effective attraction by multivalent ions. In this work, we examined the dependence of multivalent ion-mediated attraction between like-charged colloidal particles on the particle charge in a wide range by extensive Monte Carlo simulations. Our calculations show that for both divalent and trivalent salts, the effective attraction between like-charged colloidal particles becomes stronger with the increase of the particle charge, whereas it gradually becomes weakened when the particle charge exceeds a "critical" value. Correspondingly, as the particle charge is increased, the driving force for such effective attraction transits from an attractive electrostatic force to an attractive depletion force, and the attraction weakening by high particle charges is attributed to the transition of electrostatic force from attraction to repulsion. Our analyses suggest that the attractive depletion force and the repulsive electrostatic force at high particle charges result from the Coulomb depletion which suppresses the counterion condensation in the limited region between two like-charged colloidal particles. Moreover, our extensive calculations indicate that the "critical" particle charge decreases apparently for larger ions and smaller colloidal particles due to stronger Coulomb depletion and decreases slightly at higher salt concentrations due to the slightly enhanced Coulomb depletion in the intervening space between colloidal particles. Encouragingly, we derived an analytical formula for the "critical" particle charge based on the Lindemann melting law.
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Affiliation(s)
- Cheng Lin
- Center
for Theoretical Physics and Key Laboratory of Artificial Micro &
Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Xiaowei Qiang
- Center
for Theoretical Physics and Key Laboratory of Artificial Micro &
Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Hai-Long Dong
- Center
for Theoretical Physics and Key Laboratory of Artificial Micro &
Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jie Huo
- Center
for Theoretical Physics and Key Laboratory of Artificial Micro &
Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
- School
of Physics and Electronic-Electrical Engineering, Ningxia University, Yinchuan 750021, China
| | - Zhi-Jie Tan
- Center
for Theoretical Physics and Key Laboratory of Artificial Micro &
Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
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Zheng Y, Lin C, Zhang JS, Tan ZJ. Ion-mediated interactions between like-charged polyelectrolytes with bending flexibility. Sci Rep 2020; 10:21586. [PMID: 33299024 PMCID: PMC7726156 DOI: 10.1038/s41598-020-78684-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 11/27/2020] [Indexed: 12/12/2022] Open
Abstract
Ion-mediated interactions between polyelectrolytes (PEs) are crucial to the properties of flexible biopolymers such as nucleic acids and proteins but the effect of PE flexibility on such interactions has not been explicitly addressed until now. In this work, the potentials of mean force (PMFs) between like-charged PEs with different bending flexibility have been investigated by Monte Carlo simulations and a cylindrical confinement around each PE was involved to model two PEs in an array. We found that in the absence of trivalent salt, the PMFs between like-charged PEs in an array are apparently repulsive while the bending flexibility can visibly decrease the repulsive PMFs. With the addition of high trivalent salt, the PMFs become significantly attractive whereas the attractive PMFs can be apparently weakened by the bending flexibility. Our analyses reveal that the effect of bending flexibility is attributed to the increased PE conformational space, which allows the PEs to fluctuate away to decrease the monovalent ion-mediated repulsion or to weaken the trivalent ion-mediated attraction through disrupting trivalent ion-bridging configuration. Additionally, our further calculations show that the effect of bending flexibility on the ion-mediated interactions is less apparent for PEs without cylindrical confinement.
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Affiliation(s)
- Yitong Zheng
- Hongyi Honor School, Wuhan University, Wuhan, 430072, China
- Department of Physics and Key Laboratory of Artificial Micro and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Cheng Lin
- Department of Physics and Key Laboratory of Artificial Micro and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Jin-Si Zhang
- College of Electrical and Photoelectronic Engineering, West Anhui University, Lu'an, 237012, China
| | - Zhi-Jie Tan
- Department of Physics and Key Laboratory of Artificial Micro and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, 430072, China.
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Wang Y, Liu T, Yu T, Tan ZJ, Zhang W. Salt effect on thermodynamics and kinetics of a single RNA base pair. RNA (NEW YORK, N.Y.) 2020; 26:470-480. [PMID: 31988191 PMCID: PMC7075264 DOI: 10.1261/rna.073882.119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 01/11/2020] [Indexed: 05/09/2023]
Abstract
Due to the polyanionic nature of RNAs, the structural folding of RNAs are sensitive to solution salt conditions, while there is still lack of a deep understanding of the salt effect on the thermodynamics and kinetics of RNAs at a single base-pair level. In this work, the thermodynamic and the kinetic parameters for the base-pair AU closing/opening at different salt concentrations were calculated by 3-µsec all-atom molecular dynamics (MD) simulations at different temperatures. It was found that for the base-pair formation, the enthalpy change [Formula: see text] is nearly independent of salt concentration, while the entropy change [Formula: see text] exhibits a linear dependence on the logarithm of salt concentration, verifying the empirical assumption based on thermodynamic experiments. Our analyses revealed that such salt concentration dependence of the entropy change mainly results from the dependence of ion translational entropy change for the base pair closing/opening on salt concentration. Furthermore, the closing rate increases with the increasing of salt concentration, while the opening rate is nearly independent of salt concentration. Additionally, our analyses revealed that the free energy surface for describing the base-pair opening and closing dynamics becomes more rugged with the decrease of salt concentration.
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Affiliation(s)
- Yujie Wang
- Department of Physics and Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, Hubei, 430072, P.R. China
- Department of Physics and Telecommunication Engineering, Zhoukou Normal University, Zhoukou, Henan, 466001, P.R. China
| | - Taigang Liu
- Department of Physics and Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, Hubei, 430072, P.R. China
- School of Medical Engineering, Xinxiang Medical University, Xinxiang, Henan, 453003, P.R. China
| | - Ting Yu
- Department of Physics and Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, Hubei, 430072, P.R. China
| | - Zhi-Jie Tan
- Department of Physics and Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, Hubei, 430072, P.R. China
| | - Wenbing Zhang
- Department of Physics and Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, Hubei, 430072, P.R. China
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