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Zhang Z, Han Y, Chen WR, Do C. Diffusion characteristics of water molecules in a lamellar structure formed by triblock copolymers. Phys Chem Chem Phys 2022; 24:8015-8021. [PMID: 35315475 DOI: 10.1039/d2cp00207h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The distribution and diffusion of water molecules are playing important roles in determining self-assembly and transport properties of polymeric systems. Small-angle neutron scattering (SANS) experiments and molecular dynamics (MD) simulation have been applied to understand the distribution of water molecules and their dynamics in the lamellar membrane formed by Pluronic L62 block copolymers. Penetration of water molecules into the polyethylene oxide (PEO) layers of the membranes has been estimated using scattering length density (SLD) profiles obtained from SANS measurements, which agree well with the molecular distribution observed from MD simulations. The water diffusion coefficient at different regions of the lamellar membrane was further investigated using MD simulation. The diffusion characteristic shows a transition from normal to anomalous diffusion as the position of the water molecule changes from the bulk to PEO and to the polypropylene oxide (PPO) layer. We find that water molecules within the PEO or PPO layers follow subdiffusive dynamics, which can be interpreted by the model of fractional Brownian motion.
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Affiliation(s)
- Zhe Zhang
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. .,Forschungszentrum Jülich, Jülich Center for Neutron Science, Outstation at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory, Oak Ridge Tennessee, 37831, USA
| | - Youngkyu Han
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Wei-Ren Chen
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Changwoo Do
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
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2
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Song XY, Chen K, Tian WD. PAMAM dendrimer in a phosphate solution: An atomistic simulation study. POLYMER 2020. [DOI: 10.1016/j.polymer.2020.122881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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3
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Jia D, Muthukumar M. Effect of Salt on the Ordinary-Extraordinary Transition in Solutions of Charged Macromolecules. J Am Chem Soc 2019; 141:5886-5896. [PMID: 30896938 DOI: 10.1021/jacs.9b00562] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using dynamic light scattering technique, we address the role of added salt at higher concentrations on the "ordinary-extraordinary" transition in solutions of charged macromolecules. The "ordinary" behavior has previously been associated with a "fast" diffusion coefficient which is independent of salt concentration Cs and polymer concentration Cp if the ratio Cp/ Cs is above a threshold value. The "extraordinary" transition is associated with formation of aggregates, with a "slow" diffusion coefficient, formed from similarly charged macromolecules. By investigating aqueous solutions of sodium poly(styrenesulfonate) and sodium chloride with variations in Cp, Cs, and polymer molecular weight, Mw, we report the emergence of a new diffusive "fast" relaxation mode at higher values of Cp, Cs, and Mw, in addition to the previously known "fast" and "slow" relaxation modes. Furthermore, we find that Mw plays a crucial role on the collective dynamics of polyelectrolyte solutions with salt, instead of just the Cp/ Cs ratio as previously postulated. As Mw is progressively decreased, the salty solution exhibits dynamical transitions from three modes to two modes and then to one mode of relaxation. The emergence of the new fast mode and the dynamical transitions are in marked departure from the general premise of the ordinary-extraordinary transition developed over several decades. In an effort to rationalize our experimental findings we present a theory for the collective dynamics of polyelectrolyte solutions with salt by addressing the coupling between the relaxations of polyelectrolyte chains, counterions from the polymer and added salt, and co-ions from the salt. The predictions are in qualitative agreement with experimental findings. The present combined work of experiments and theory forms the basis for accurately characterizing dynamics of charged macromolecules in salty solutions, which are ubiquitous in biological systems and polyelectrolyte-based technologies.
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Affiliation(s)
- Di Jia
- Department of Polymer Science and Engineering , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Murugappan Muthukumar
- Department of Polymer Science and Engineering , University of Massachusetts , Amherst , Massachusetts 01003 , United States
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4
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Yu C, Ma L, Li K, Li S, Liu Y, Liu L, Zhou Y, Yan D. Computer Simulation Studies on the pH-Responsive Self-Assembly of Amphiphilic Carboxy-Terminated Polyester Dendrimers in Aqueous Solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:388-399. [PMID: 28001081 DOI: 10.1021/acs.langmuir.6b03480] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This paper investigates the pH-responsive self-assembly of an amphiphilic carboxyl-terminated polyester dendrimer, H20-COOH, in aqueous solution using the dissipative particle dynamics method. The electrostatic interactions were described by introducing the explicit interaction between the smeared charges on ionized polymer beads and the counterions. The results show that the self-assemblies could change from unimolecular micelles, microphase-separated small micelles, wormlike micelles, sheetlike micelles, and small vesicles to large vesicles with the decrease in the degree of ionization (α) of carboxylic acid groups. In addition, the detailed self-assembly mechanisms and the molecular packing models have also been disclosed for each self-assembly stages. Interestingly, the wormlike micelles are found to change from linear to branched when α decreases from 0.182 to 0.109. The current work might serve as a comprehensive understanding on the effect of carboxylic acid groups on the self-assembly behaviors of dendritic polymers.
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Affiliation(s)
- Chunyang Yu
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
| | - Li Ma
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
| | - Ke Li
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
| | - Shanlong Li
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
| | - Yannan Liu
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
| | - Lifen Liu
- Center for Membrane and Water Science and Technology, Ocean College, Zhejiang University of Technology , Hangzhou 310014, China
| | - Yongfeng Zhou
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
| | - Deyue Yan
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
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5
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De Luca S, Seal P, Ouyang D, Parekh HS, Kannam SK, Smith SC. Dynamical Interactions of 5-Fluorouracil Drug with Dendritic Peptide Vectors: The Impact of Dendrimer Generation, Charge, Counterions, and Structured Water. J Phys Chem B 2016; 120:5732-43. [PMID: 27267604 DOI: 10.1021/acs.jpcb.6b00533] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Molecular dynamics simulations are utilized to investigate the interactions between the skin cancer drug 5-fluorouracil (5FU) and peptide-based dendritic carrier systems. We find that these drug-carrier interactions do not conform to the traditional picture of long-time retention of the drug within a hydrophobic core of the dendrimer carrier. Rather, 5FU, which is moderately soluble in its own right, experiences weak, transient chattering interactions all over the dendrimer, mediated through multiple short-lived hydrogen bonding and close contact events. We find that charge on the periphery of the dendrimer actually has a negative effect on the frequency of drug-carrier interactions due to a counterion screening effect that has not previously been observed. However, charge is nevertheless an important feature since neutral dendrimers are shown to have a significant mutual attraction that can lead to clustering or agglomeration. This clustering is prevented due to charge repulsion for the titrated dendrimers, such that they remain independent in solution.
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Affiliation(s)
- Sergio De Luca
- Integrated Materials Design Centre (IMDC), School of Chemical Engineering, UNSW Australia , Sydney, New South Wales 2052, Australia
| | - Prasenjit Seal
- Integrated Materials Design Centre (IMDC), School of Chemical Engineering, UNSW Australia , Sydney, New South Wales 2052, Australia
| | - Defang Ouyang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences (ICMS), University of Macau , Macau, China
| | - Harendra S Parekh
- School of Pharmacy, The University of Queensland , Brisbane, Queensland 4072, Australia
| | | | - Sean C Smith
- Integrated Materials Design Centre (IMDC), School of Chemical Engineering, UNSW Australia , Sydney, New South Wales 2052, Australia
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Zhang Z, Ohl M, Diallo SO, Jalarvo NH, Hong K, Han Y, Smith GS, Do C. Dynamics of Water Associated with Lithium Ions Distributed in Polyethylene Oxide. PHYSICAL REVIEW LETTERS 2015; 115:198301. [PMID: 26588420 DOI: 10.1103/physrevlett.115.198301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Indexed: 05/25/2023]
Abstract
The dynamics of water in polyethylene oxide (PEO)/LiCl solution has been studied with quasielastic neutron scattering experiments and molecular dynamics (MD) simulations. Two different time scales of water diffusion representing interfacial water and bulk water dynamics have been identified. The measured diffusion coefficient of interfacial water remained 5-10 times smaller than that of bulk water, but both were slowed by approximately 50% in the presence of Li(+). Detailed analysis of MD trajectories suggests that Li(+) is favorably found at the surface of the hydration layer, and the probability to find the caged Li(+) configuration formed by the PEO is lower than for the noncaged Li(+)-PEO configuration. In both configurations, however, the slowing down of water molecules is driven by reorienting water molecules and creating water-Li(+) hydration complexes. Performing the MD simulation with different ions (Na(+) and K(+)) revealed that smaller ionic radius of the ions is a key factor in disrupting the formation of PEO cages by allowing spaces for water molecules to come in between the ion and PEO.
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Affiliation(s)
- Zhe Zhang
- Biology and Soft-Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Forschungszentrum Jülich, Jülich Center for Neutron Science, Outstation at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Michael Ohl
- Forschungszentrum Jülich, Jülich Center for Neutron Science, Outstation at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Souleymane O Diallo
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Niina H Jalarvo
- Forschungszentrum Jülich, Jülich Center for Neutron Science, Outstation at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Kunlun Hong
- Center For Nanophase Materials Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Youngkyu Han
- Biology and Soft-Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Gregory S Smith
- Biology and Soft-Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Changwoo Do
- Biology and Soft-Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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7
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Li X, Sánchez-Diáz LE, Wu B, Hamilton WA, Falus P, Porcar L, Liu Y, Do C, Faraone A, Smith GS, Egami T, Chen WR. Dynamical Threshold of Diluteness of Soft Colloids. ACS Macro Lett 2014; 3:1271-1275. [PMID: 35610839 DOI: 10.1021/mz500500c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Soft colloids are hybrids between linear polymers and hard colloids. Their solutions exhibit rich phase phenomenon due to their unique microstructure. In scaling theories, a geometrically defined overlap concentration c* is used to identify the concentration regimes of their solutions characterized with distinct conformational properties. Previous experiments showed that the average size of soft colloids remains invariant below c* and varies characteristically above it. This observation reveals the causality between the conformational evolution and the physical overlap between neighboring particles. Using neutron scattering, we demonstrate that the competition between the interparticle translational diffusion and intraparticle internal dynamics leads to significant conformational evolution below c*. Substantial structural dehydration and slowing-down of internal dynamics are both observed before physical overlap develops. Well below c*, a new threshold of diluteness cD* emerges as the crossover between the characteristic times associated with these two relaxation processes. Below this dynamically defined cD*, the two relaxation processes are essentially uncoupled, and therefore, the majority of the soft colloids retain their unperturbed conformational dimensions. Our observation demonstrates the importance of incorporating dynamical degrees of freedom in defining the threshold of diluteness for this important class of soft matter.
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Affiliation(s)
| | | | - Bin Wu
- Department of Materials Science and Engineering
and Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1508, United States
| | | | - Péter Falus
- Institut Laue-Langevin, B.P. 156, F-38042 Grenoble CEDEX
9, France
| | - Lionel Porcar
- Institut Laue-Langevin, B.P. 156, F-38042 Grenoble CEDEX
9, France
| | - Yun Liu
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6100, United States
- Department
of Chemical Engineering, University of Delaware, Newark, Delaware 19716, United States
| | | | - Antonio Faraone
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6100, United States
| | | | - Takeshi Egami
- Department of Materials Science and Engineering
and Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1508, United States
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Geitner NK, Wang B, Andorfer RE, Ladner DA, Ke PC, Ding F. Structure-function relationship of PAMAM dendrimers as robust oil dispersants. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:12868-12875. [PMID: 25279688 DOI: 10.1021/es5038194] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
PAMAM dendrimers have recently been investigated as efficient and biocompatible oil dispersants utilizing their encapsulation capacity; however, their high cationic charge density has been shown to be cytotoxic. It is therefore imperative to mitigate cationic charge-induced toxicity and understand the effects of such changes. Presented here is a synergistic experimental and computational approach to examine the effects of varying terminal surface charge on the capacity of dendrimers to disperse model liner, polycyclic aromatic, and hybrid hydrocarbons. Uncharged dendrimers collapse by forming intramolecular hydrogen bonds, which reduce the hosting capability. On the other hand, changing the surface charges from positive to negative greatly shifts the pKa of tertiary amines of the PAMAM dendrimer interior. As a result, the negatively charged dendrimers have a significant percentage of tertiary amines protonated, ∼30%. This unexpected change in the interior protonation state causes electrostatic interactions with the anionic terminal groups, leading to contraction and a marked decrease in hydrocarbon hosting capacity. The present work highlights the robust nature of dendrimer oil dispersion and also illuminates potentially unintended or unanticipated effects of varying dendrimer surface chemistry on their encapsulation or hosting efficacy, which is important for their environmental, industrial, and biomedical applications.
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Affiliation(s)
- Nicholas K Geitner
- Department of Physics and Astronomy and ‡Department of Environmental Engineering and Earth Sciences, Clemson University , Clemson, South Carolina 29634, United States
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9
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Zhang Z, Carrillo JMY, Ahn SK, Wu B, Hong K, Smith GS, Do C. Atomistic Structure of Bottlebrush Polymers: Simulations and Neutron Scattering Studies. Macromolecules 2014. [DOI: 10.1021/ma500613c] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
| | | | | | - Bin Wu
- Department
of Physics and Astronomy, Joint Institute for Neutron Science, University of Tennessee, Knoxville, Tennessee 37996, United States
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10
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Modeling dendrimers charge interaction in solution: relevance in biosystems. Biochem Res Int 2014; 2014:837651. [PMID: 24719765 PMCID: PMC3955673 DOI: 10.1155/2014/837651] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 12/30/2013] [Accepted: 01/13/2014] [Indexed: 12/20/2022] Open
Abstract
Dendrimers are highly branched macromolecules obtained by stepwise controlled, reaction sequences. The ability to be designed for specific applications makes dendrimers unprecedented components to control the structural organization of matter during the bottom-up synthesis of functional nanostructures. For their applications in the field of biotechnology the determination of dendrimer structural properties as well as the investigation of the specific interaction with guest components are needed. We show how the analysis of the scattering structure factor S(q), in the framework of current models for charged systems in solution, allows for obtaining important information of the interdendrimers electrostatic interaction potential. The finding of the presented results outlines the important role of the dendrimer charge and the solvent conditions in regulating, through the modulation of the electrostatic interaction potential, great part of the main structural properties. This charge interaction has been indicated by many studies as a crucial factor for a wide range of structural processes involving their biomedical application. Due to their easily controllable properties dendrimers can be considered at the crossroad between traditional colloids, associating polymers, and biological systems and represent then an interesting new technological approach and a suitable model system of molecular organization in biochemistry and related fields.
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11
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Freire JJ, Ahmadi A, McBride C. Molecular Dynamics Simulations of the Protonated G4 PAMAM Dendrimer in an Ionic Liquid System. J Phys Chem B 2013; 117:15157-64. [DOI: 10.1021/jp402586s] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Juan J. Freire
- Departamento
de Ciencias y Técnicas Fisicoquímicas, Facultad de Ciencias, Universidad Nacional de Educación a Distancia (UNED), Paseo Senda del
Rey 9, 28040 Madrid, Spain
| | - Amirhossein Ahmadi
- Departamento
de Ciencias y Técnicas Fisicoquímicas, Facultad de Ciencias, Universidad Nacional de Educación a Distancia (UNED), Paseo Senda del
Rey 9, 28040 Madrid, Spain
| | - Carl McBride
- Departamento
de Ciencias y Técnicas Fisicoquímicas, Facultad de Ciencias, Universidad Nacional de Educación a Distancia (UNED), Paseo Senda del
Rey 9, 28040 Madrid, Spain
- Instituto de Química Física Rocasolano (CSIC), Serrano 119, 28006 Madrid, Spain
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