1
|
Beaton AA, Guinness A, Franck JM. Rapidly Screening the Correlation between the Rotational Mobility and the Hydrogen Bonding Strength of Confined Water. J Phys Chem B 2024; 128:10749-10763. [PMID: 39439388 DOI: 10.1021/acs.jpcb.4c05397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2024]
Abstract
Automated Deuterium Relaxation-Ordered SpectroscopY in solution (ADROSYS), an automated two-dimensional deuterium NMR methodology, discriminates between D2O populations (as well as deuterium-labeled alcohol groups) whose properties differ as a result of being confined inside nanoscale volumes. In this contribution, a proof-of-principle demonstration on reverse micelles (RMs) yields the insight that as the length scale of the confinement decreases from several nanometers down to less than a nanometer, the position of the signal peak migrates through the two-dimensional (2D) spectrum, tracing out a distinctive path in the 2D space (of relaxation time vs chemical shift). The signals typically follow a relatively gentle linear path for water confined on the scale of several nanometers, before curving once the surfactants confine the water molecules to length scales smaller than 1-2 nm. The qualitative shape of this path, especially in the regime of strong confinement, can change with different choices of surfactants, i.e., a different choice of chemistry at the edges of the confining environment. An important facet of this research was to demonstrate the relatively wide applicability of these techniques by showing that both: (1) Standard modern NMR instrumentation is capable of deploying an automated measurement, even though the choice of a deuterium nucleus is nonstandard and frequently requires companion proton spectra in order to reference the chemical shifts; and (2) well-established (though underutilized) modern techniques can process the resulting signal even though it involves the somewhat unusual combination of chemical shifts along one dimension and a distribution of relaxation times along another dimension. In addition to demonstrating that this technique can be deployed across many samples of interest, detailed facts pertaining to the broadening or shifting of resulting signals upon inclusion of various guest molecules are also discussed.
Collapse
Affiliation(s)
- Alec A Beaton
- Department of Chemistry, Syracuse University, Syracuse, New York 13210, United States
| | - Alexandria Guinness
- Department of Chemistry, Syracuse University, Syracuse, New York 13210, United States
| | - John M Franck
- Department of Chemistry, Syracuse University, Syracuse, New York 13210, United States
| |
Collapse
|
2
|
Mat'usová A, Moody G, Dowding PJ, Eastoe J, Camp PJ. Experimental and simulation study of reverse micelles formed by aerosol-OT and water in non-polar solvents. Phys Chem Chem Phys 2024. [PMID: 39470246 DOI: 10.1039/d4cp03389b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/30/2024]
Abstract
The formation of reverse micelles by aerosol-OT [sodium bis(2-ethylhexyl) sulfosuccinate] in hydrocarbon solvents, and in the presence of water, is studied using a combination of atomistic molecular-dynamics simulations and small-angle neutron scattering (SANS). There have been many previous studies of aerosol-OT and its self-assembly in both water and non-aqueous solvents, but this work is focused on a combined experimental and simulation study of reverse-micelle formation. The effects of hydration (with water-to-surfactant molar ratios in the range 0-60) and solvent (cyclohexane and n-dodecane) are investigated. A force field is adapted that results in spontaneous formation of reverse micelles starting from completely randomized configurations. The computed dimensions of the reverse micelles compare very favourably with those determined in SANS experiments, providing validation of the simulation model. The kinetics of reverse-micelle formation are studied with a 50-ns, 1.7-million-atom system which contains, in the steady state, about 50 reverse micelles. The internal structures of reverse micelles are characterized with mass density profiles, and the effects of solvent, and the structural crossover from highly structured water to 'bulk' water in the core, are detailed. The corresponding changes in the molecular reorientation times of sequestered water are also determined. Overall, the combination of experiment and simulation gives a detailed picture of reverse-micelle self-assembly and structure.
Collapse
Affiliation(s)
- Angie Mat'usová
- School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, Scotland, UK.
| | - Georgina Moody
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | | | - Julian Eastoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Philip J Camp
- School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, Scotland, UK.
| |
Collapse
|
3
|
Wang CW, Kuo YW, Zeng JR, Tang PH, Wu TM. Confinement Effects on Reorientation Dynamics of Water Confined within Graphite Nanoslits. J Phys Chem B 2024; 128:9525-9535. [PMID: 39307993 PMCID: PMC11457136 DOI: 10.1021/acs.jpcb.4c03898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 09/04/2024] [Accepted: 09/04/2024] [Indexed: 10/04/2024]
Abstract
Molecular dynamics simulations were used to investigate the reorientation dynamics of water confined within graphite nanoslits of size less than 2 nm, where molecules formed inner and interfacial layers parallel to the confining walls. Significantly related to molecular reorientations, the hydrogen-bond (HB) network of nanoconfined water therein was scrutinized by HB configuration fractions compared to those of bulk water and the influences on interfacial-molecule orientations relative to a nearby C atom plate. The second-rank orientation time correlation functions (OTCFs) of nanoconfined water were calculated and found to follow stretched-exponential, power-law, and power-law decays in a time series. To understand this naïve behavior of reorientation relaxation, the approach of statistical mechanics was adopted in our studies. In terms of the orientation Van Hove function (OVHF), an alternative meaning was given to the second-rank OTCF, which is a measure of the deviation of the OVHF between a molecular system and free molecules in random orientations. Indicated by the OVHFs at related time scales, the stretched-exponential decay of the second-rank OTCF resulted from molecules evacuating out of HB cages formed by their neighbors. After the evacuations, the inner molecules relaxed at relatively fast rates toward random orientations, but the interfacial molecules reoriented at slow rates due to restrictions by hydrophobic interactions with graphite walls. The first power-law decay of the second-rank OTCF was attributed to the distinct relaxation rates of inner and interfacial molecules within a graphite nanoslit. When the inner molecules were completely random in orientation, the second-rank OTCFs changed to another power law decay with a power smaller than the first one.
Collapse
Affiliation(s)
- Chi-Wei Wang
- Institute of Physics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Yu-Wei Kuo
- Institute of Physics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Jing-Rong Zeng
- Institute of Physics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | | | - Ten-Ming Wu
- Institute of Physics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| |
Collapse
|
4
|
Meikle TG, Keizer DW, Separovic F, Yao S. Insights into dynamic properties of water in lipidic cubic phases by 2D nuclear Overhauser effect (NOE) NMR spectroscopy. J Colloid Interface Sci 2024; 666:659-669. [PMID: 38616448 DOI: 10.1016/j.jcis.2024.04.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/03/2024] [Accepted: 04/08/2024] [Indexed: 04/16/2024]
Abstract
Two-dimensional NOE (nuclear Overhauser effect) NMR spectroscopy was employed to investigate the dynamic properties of water within lyotropic bicontinuous lipidic cubic phases (LCPs) formed by monoolein (MO). Experiments observed categorically different effective residence times of water molecules: (i) in proximity to the glycerol moiety of MO, and (ii) adjacent to the hydrophobic chain towards the hydrocarbon tail of MO, as evidenced by the opposite signs of intermolecular NOE cross peaks between protons of water and those of MO in 2D 1H-1H NOESY spectra. Spectroscopic data delineating the different effective residence times of water molecules within both the gyroid (QIIG) and diamond (QIID) phase groups corresponding to hydration levels of 35 and 40 wt%, respectively, are presented. Additionally, an increase in effective residence time of water molecules in proximity to the glycerol moiety of MO in LCPs was observed upon storage at ambient temperature and in the presence of an additive lipid, cholesterol. Atom-specific NOE build-up curves for protons of water and those of MO are also given. The results presented herein provide new insight into the physicochemical properties and behaviour of water in LCPs, and demonstrate an additional avenue for experimental study of water-lipid interactions and hydration dynamics in model membranes and nanomaterials using 2D NOE NMR spectroscopy.
Collapse
Affiliation(s)
- Thomas G Meikle
- Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia
| | - David W Keizer
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia
| | - Frances Separovic
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia; School of Chemistry, The University of Melbourne, VIC 3010, Australia
| | - Shenggen Yao
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia.
| |
Collapse
|
5
|
Gale CD, Derakhshani-Molayousefi M, Levinger NE. Shape of AOT Reverse Micelles: The Mesoscopic Assembly Is More Than the Sum of the Parts. J Phys Chem B 2024; 128:6410-6421. [PMID: 38900154 DOI: 10.1021/acs.jpcb.4c02569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
AOT reverse micelles are a common and convenient model system for studying the effects of nanoconfinement on aqueous solutions. The reverse micelle shape is important to understanding how the constituent components come together to form the coherent whole and the unique properties observed there. The shape of reverse micelles impacts the amount of interface present and the distance of the solute from the interface and is therefore vital to understanding interfacial properties and the behavior of solutes in the polar core. In this work, we use previously introduced measures of shape, the coordinate-pair eccentricity (CPE) and convexity, and apply them to a series of simulations of AOT reverse micelles. We simulate the most commonly used force field for AOT reverse micelles, the CHARMM force field, but we also adapt the OPLS force field for use with AOT, the first work to do so, in addition to using both 3- and 4-site water models. Altogether, these simulations are designed to examine the impact of the force field on the shape of the reverse micelles in detail. We also study the time autocorrelation of shape, the water rotational anisotropy decay, and how the CPE changes between the water pool and AOT tail groups. We find that although the force field changes the shape noticeably, AOT reverse micelles are always amorphous particles. The shape of the micelles changes on the order of 10 ns. The water rotational dynamics observed match the experiment and demonstrate slower dynamics relative to bulk water, suggesting a two-population model that fits a core/shell hypothesis. Taken together, our results indicate that it is likely not possible to create a perfect force field that can reproduce every aspect of the AOT reverse micelle accurately. However, the magnitude of the differences between simulations appears relatively small, suggesting that any reasonably derived force field should provide an acceptable model for most work on AOT reverse micelles.
Collapse
Affiliation(s)
- Christopher D Gale
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | | | - Nancy E Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
| |
Collapse
|
6
|
Crowder M, Tahiry F, Lizarraga I, Rodriguez S, Peña N, Sharma AK. Computatiaonal Analysis of Water Dynamics in AOT Reverse Micelles. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
|
7
|
Petersen MH, Telling MTF, Kneller G, Bordallo HN. Revisiting the modeling of quasielastic neutron scattering from bulk water. EPJ WEB OF CONFERENCES 2022. [DOI: 10.1051/epjconf/202227201012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Quasi-elastic neutron scattering (QENS) from bulk-water at 300 K, measured on the IRIS backscattering neutron spectrometer (ISIS, UK), is interpreted using the jump diffusion model (JDM), a “minimalistic” multi-timescale relaxation model (MRM) and molecular dynamics simulations (MD). In the case of MRM data analysis is performed in the time domain, where the relaxation of the intermediate scattering function is described by a stretched Mittag-Leffler function, Eα(−(|t|/τ)α). This function displays an asymptotic power law decay and contains the exponential relaxation function as a special case (α = 1). To further compare the two approaches, MD simulations of bulk water were performed using the SPCE force field and the resulting MD trajectories analysed using the nMoldyn software. We show that both JDM and MRM accurately describe the diffusion of bulk water observed by QENS at all length scales, and confirm that MD simulations do not fully describe the quantum effects of jump diffusion.
Collapse
|
8
|
Agosta L, Dzugutov M, Hermansson K. Supercooled liquid-like dynamics in water near a fully hydrated titania surface: Decoupling of rotational and translational diffusion. J Chem Phys 2021; 154:094708. [PMID: 33685161 DOI: 10.1063/5.0039693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report an ab initio molecular dynamics (MD) simulation investigating the effect of a fully hydrated surface of TiO2 on the water dynamics. It is found that the universal relation between the rotational and translational diffusion characteristics of bulk water is broken in the water layers near the surface with the rotational diffusion demonstrating progressive retardation relative to the translational diffusion when approaching the surface. This kind of rotation-translation decoupling has so far only been observed in the supercooled liquids approaching glass transition, and its observation in water at a normal liquid temperature is of conceptual interest. This finding is also of interest for the application-significant studies of the water interaction with fully hydrated nanoparticles. We note that this is the first observation of rotation-translation decoupling in an ab initio MD simulation of water.
Collapse
Affiliation(s)
- Lorenzo Agosta
- Department of Chemistry-Ångström, Uppsala University, S-75121 Uppsala, Sweden
| | - Mikhail Dzugutov
- Department of Chemistry-Ångström, Uppsala University, S-75121 Uppsala, Sweden
| | - Kersti Hermansson
- Department of Chemistry-Ångström, Uppsala University, S-75121 Uppsala, Sweden
| |
Collapse
|
9
|
Versatility of Reverse Micelles: From Biomimetic Models to Nano (Bio)Sensor Design. Processes (Basel) 2021. [DOI: 10.3390/pr9020345] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
This paper presents an overview of the principal structural and dynamics characteristics of reverse micelles (RMs) in order to highlight their structural flexibility and versatility, along with the possibility to modulate their parameters in a controlled manner. The multifunctionality in a large range of different scientific fields is exemplified in two distinct directions: a theoretical model for mimicry of the biological microenvironment and practical application in the field of nanotechnology and nano-based sensors. RMs represent a convenient experimental approach that limits the drawbacks of the conventionally biological studies in vitro, while the particular structure confers them the status of simplified mimics of cells by reproducing a complex supramolecular organization in an artificial system. The biological relevance of RMs is discussed in some particular cases referring to confinement and a crowded environment, as well as the molecular dynamics of water and a cell membrane structure. The use of RMs in a range of applications seems to be more promising due to their structural and compositional flexibility, high efficiency, and selectivity. Advances in nanotechnology are based on developing new methods of nanomaterial synthesis and deposition. This review highlights the advantages of using RMs in the synthesis of nanoparticles with specific properties and in nano (bio)sensor design.
Collapse
|
10
|
Acid Hydrolysis of Bis(2,2'; 6',2''–Terpyridyl) Iron(II) Complex in the Water Pools of CTAB/Hexane/Chloroform Reverse Micelles-A Kinetic Study in Confined Medium. BULLETIN OF CHEMICAL REACTION ENGINEERING & CATALYSIS 2020. [DOI: 10.9767/bcrec.15.3.8425.853-860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The kinetics of acid hydrolysis of bis(2,2';6',2''–terpyridyl) iron(II) complex has been studied in CTAB/Hexane/Chloroform reverse micelles. The reaction obeys first order kinetics with respect to each of the reactants at all values of W, {W= [H2O]/[CTAB]}. In the reverse micellar medium, the reaction is much slower compared to aqueous medium due to low micropolarity of the water pools which does not facilitate a reaction between reactants of same charge. The effect of variation of W {W=[H2O]/[CTAB]} at constant [CTAB] and variation of [CTAB] at fixed W has been studied. The second order rate constant (k2) of the reaction increases as the value of W increases up to W = 8.88 and remains constant thereafter and it is independent of concentration of [CTAB] at constant W. The variation of rate of reaction with W has been explained by considering variation of micropolarity and ionic strength of water pools of reverse micelles with W. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Collapse
|
11
|
Doucette KA, Chaiyasit P, Calkins DL, Martinez KN, Van Cleave C, Knebel CA, Tongraar A, Crans DC. The Interfacial Interactions of Glycine and Short Glycine Peptides in Model Membrane Systems. Int J Mol Sci 2020; 22:ijms22010162. [PMID: 33375246 PMCID: PMC7795424 DOI: 10.3390/ijms22010162] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/19/2020] [Accepted: 12/22/2020] [Indexed: 12/20/2022] Open
Abstract
The interactions of amino acids and peptides at model membrane interfaces have considerable implications for biological functions, with the ability to act as chemical messengers, hormones, neurotransmitters, and even as antibiotics and anticancer agents. In this study, glycine and the short glycine peptides diglycine, triglycine, and tetraglycine are studied with regards to their interactions at the model membrane interface of Aerosol-OT (AOT) reverse micelles via 1H NMR spectroscopy, dynamic light scattering (DLS), and Langmuir trough measurements. It was found that with the exception of monomeric glycine, the peptides prefer to associate between the interface and bulk water pool of the reverse micelle. Monomeric glycine, however, resides with the N-terminus in the ordered interstitial water (stern layer) and the C-terminus located in the bulk water pool of the reverse micelle.
Collapse
Affiliation(s)
- Kaitlin A. Doucette
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO 80523, USA;
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA; (D.L.C.); (K.N.M.); (C.V.C.); (C.A.K.)
| | - Prangthong Chaiyasit
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (P.C.); (A.T.)
| | - Donn L. Calkins
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA; (D.L.C.); (K.N.M.); (C.V.C.); (C.A.K.)
| | - Kayli N. Martinez
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA; (D.L.C.); (K.N.M.); (C.V.C.); (C.A.K.)
| | - Cameron Van Cleave
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA; (D.L.C.); (K.N.M.); (C.V.C.); (C.A.K.)
| | - Callan A. Knebel
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA; (D.L.C.); (K.N.M.); (C.V.C.); (C.A.K.)
| | - Anan Tongraar
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (P.C.); (A.T.)
| | - Debbie C. Crans
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO 80523, USA;
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA; (D.L.C.); (K.N.M.); (C.V.C.); (C.A.K.)
- Correspondence: ; Tel.: +1-970-491-7635
| |
Collapse
|
12
|
Stoppelman JP, McDaniel JG. Proton Transport in [BMIM+][BF4–]/Water Mixtures Near the Percolation Threshold. J Phys Chem B 2020; 124:5957-5970. [DOI: 10.1021/acs.jpcb.0c02487] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- John P. Stoppelman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia30332-0400, United States
| | - Jesse G. McDaniel
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia30332-0400, United States
| |
Collapse
|
13
|
Jackson GL, Kim SA, Jayaraman A, Diallo SO, Mahanthappa MK. Consequences of Convex Nanopore Chemistry on Confined Water Dynamics. J Phys Chem B 2020; 124:1495-1508. [PMID: 32065528 PMCID: PMC7122394 DOI: 10.1021/acs.jpcb.9b10176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A fundamental understanding of confined water is crucial for developing selective ion transport and water purification membranes, yet the roles of nanopore geometry and functionality on confined water dynamics remain unresolved. We report the synthesis of perdeuterated ionic alkylsulfonate amphiphiles and their water-induced self-assembly into lyotropic liquid crystal (LLC) mesophases with well-defined, convex, sulfonate-lined nanopores. Quasielastic neutron scattering (QENS) measurements demonstrate that the water self-diffusion coefficients within these sulfonate-lined convex nanopores depend on the hydration level and amphiphile counterion identity (H+, K+, NMe4+). The consistency of the observed counterion-dependent water dynamics trends with those of carboxylate LLCs is rationalized on the basis of similarities in the counterion spatial distributions in the water-filled channels, which we deduce from electron density maps derived from small-angle X-ray scattering (SAXS) analyses. These findings indicate that water diffusion is systematically faster in sulfonate-lined nanopores as compared to carboxylate-lined pores due to weaker water interactions with the softer and more hydrophobic-SO3- functionalities. These molecular-level insights into the relationships between convex pore wall chemical functionalities, hydrated counterions, and confined water diffusion may inform future development of new nanoporous media.
Collapse
Affiliation(s)
- Grayson L. Jackson
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706
| | - Sung A Kim
- Department of Chemical Engineering & Materials Science, University of Minnesota, 421 Washington Ave, S.E., Minneapolis, MN 55455
| | - Ashish Jayaraman
- Department of Chemical Engineering & Materials Science, University of Minnesota, 421 Washington Ave, S.E., Minneapolis, MN 55455
| | - Souleymane O. Diallo
- Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Mahesh K. Mahanthappa
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706
- Department of Chemical Engineering & Materials Science, University of Minnesota, 421 Washington Ave, S.E., Minneapolis, MN 55455
| |
Collapse
|
14
|
Zhou D, Wei Q, Wang S, Li X, Bian H. Counterion Effect on Vibrational Relaxation and the Rotational Dynamics of Interfacial Water and an Anionic Vibrational Probe in the Confined Reverse Micelles Environment. J Phys Chem Lett 2019; 10:176-182. [PMID: 30582817 DOI: 10.1021/acs.jpclett.8b03389] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Vibrational relaxation and the rotational dynamics of water molecules encapsulated in reverse micelles (RMs) have been investigated by ultrafast infrared (IR) spectroscopy and two-dimensional IR (2D IR) spectroscopy. By changing the counterion of the hydrophilic headgroup in the RMs formed by Aerosol-OT (AOT) from Na+ to K+, Cs+ and Ca2+, we could determine the specific counterion effects on the rotational dynamics of water molecules. The orientational relaxation time constant of water decreases in the order Ca2+ > Na+ > K+ > Cs+. The SCN- anionic probe and counterion can form ion pairs at the interfacial region of the RMs. The rotational dynamics of SCN- anion significantly decreases because of the synergistic effects of confinement and the surface interactions in the interfacial region of the RMs. The results can provide a new understanding of the cationic Hofmeister effect at the molecular level observed in biological studies.
Collapse
Affiliation(s)
- Dexia Zhou
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an , 710119 , China
| | - Qianshun Wei
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an , 710119 , China
| | - Shuyan Wang
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an , 710119 , China
| | - Xiaoqian Li
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an , 710119 , China
| | - Hongtao Bian
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an , 710119 , China
| |
Collapse
|
15
|
Jackson GL, Mantha S, Kim SA, Diallo SO, Herwig KW, Yethiraj A, Mahanthappa MK. Ion-Specific Confined Water Dynamics in Convex Nanopores of Gemini Surfactant Lyotropic Liquid Crystals. J Phys Chem B 2018; 122:10031-10043. [PMID: 30251848 DOI: 10.1021/acs.jpcb.8b05942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The impact of pore geometry and functionality on the dynamics of water nanoconfined in porous media are the subject of some debate. We report the synthesis and small-angle X-ray scattering (SAXS) characterization of a series of perdeuterated gemini surfactant lyotropic liquid crystals (LLCs), in which convex, water-filled nanopores of well-defined dimensions are lined with carboxylate functionalities. Quasielastic neutron scattering (QENS) measurements of the translational water dynamics in these dicarboxylate LLC nanopores as functions of the surfactant hydration state and the charge compensating counterion (Na+, K+, NMe4+) reveal that the measured dynamics depend primarily on surfactant hydration, with an unexpected counterion dependence that varies with hydration number. We rationalize these trends in terms of a balance between counterion-water attractions and the nanopore volume excluded by the counterions. On the basis of electron density maps derived from SAXS analyses of these LLCs, we directly show that the volume excluded by the counterions depends on both their size and spatial distribution in the water-filled channels. The translational water dynamics in the convex pores of these LLCs are also slower than those reported in the concave pores of AOT reverse micelles, implying that water dynamics also depend on the nanopore curvature.
Collapse
Affiliation(s)
- Grayson L Jackson
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States
| | - Sriteja Mantha
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States
| | - Sung A Kim
- Department of Chemical Engineering & Materials Science , University of Minnesota , 421 Washington Avenue, S.E. , Minneapolis , Minnesota 55455 , United States
| | | | | | - Arun Yethiraj
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States
| | - Mahesh K Mahanthappa
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States.,Department of Chemical Engineering & Materials Science , University of Minnesota , 421 Washington Avenue, S.E. , Minneapolis , Minnesota 55455 , United States
| |
Collapse
|
16
|
Piskulich ZA, Thompson WH. The activation energy for water reorientation differs between IR pump-probe and NMR measurements. J Chem Phys 2018; 149:164504. [DOI: 10.1063/1.5050203] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Zeke A. Piskulich
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA
- Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas 66047, USA
| | - Ward H. Thompson
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA
- Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas 66047, USA
| |
Collapse
|
17
|
Engstler J, Giovambattista N. Temperature Effects on Water-Mediated Interactions at the Nanoscale. J Phys Chem B 2018; 122:8908-8920. [PMID: 30178667 DOI: 10.1021/acs.jpcb.8b05430] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We perform molecular dynamics simulations to study the effects of temperature on the water-mediated interactions between nanoscale apolar solutes. Specifically, we calculate the potential of mean force (PMF) between two graphene plates immersed in water at 240 ≤ T ≤ 400 K and P = 0.1 MPa. These are thermodynamic conditions relevant to cooling- and heating-induced protein denaturation. It is found that both cooling and heating tend to suppress the attraction, and ultimate collapse, of the graphene plates. However, the underlying role played by water upon heating and cooling is different. Isobaric heating reduces the strength and range of the interactions between the plates. Instead, isobaric cooling stabilizes the plates separations that can accommodate an integer number of water layers between the graphene plates. In particular, the energy barriers separating these plate separations increase linearly with 1/ T. We also explore the sensitivity of the plates PMF to the water model employed. In the case of the TIP4P/2005 model, water confined between the plates crystallizes into a defective bilayer ice at low temperatures, whereas in the case of the SPC/E model, water remains in the liquid state at same thermodynamic conditions. The effects of varying water-graphene interactions on the plates PMF are also studied.
Collapse
Affiliation(s)
- Justin Engstler
- Department of Physics , Brooklyn College of the City University of New York , Brooklyn , New York 11210 , United States
| | - Nicolas Giovambattista
- Department of Physics , Brooklyn College of the City University of New York , Brooklyn , New York 11210 , United States.,Ph.D. Programs in Chemistry and Physics , The Graduate Center of the City University of New York , New York , New York 10016 , United States
| |
Collapse
|
18
|
Shudo Y, Izumi A, Hagita K, Yamada T, Shibata K, Shibayama M. Diffusion Behavior of Methanol Molecules Confined in Cross-Linked Phenolic Resins Studied Using Neutron Scattering and Molecular Dynamics Simulations. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00535] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yasuyuki Shudo
- Neutron Science Laboratory, Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
- Corporate Engineering Center, Sumitomo Bakelite Co., Ltd., 2100, Takayanagi, Fujieda, Shizuoka 426-0041, Japan
| | - Atsushi Izumi
- Corporate Engineering Center, Sumitomo Bakelite Co., Ltd., 2100, Takayanagi, Fujieda, Shizuoka 426-0041, Japan
| | - Katsumi Hagita
- Department of Applied Physics, National Defense Academy, 1-10-20, Hashirimizu, Yokosuka, Kanagawa 239-8686, Japan
| | - Takeshi Yamada
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan
| | - Kaoru Shibata
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Naka, Ibaraki 319-1195, Japan
| | - Mitsuhiro Shibayama
- Neutron Science Laboratory, Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| |
Collapse
|
19
|
Murakami H. Persistent optical hole-burning spectroscopy of nano-confined dye molecules in liquid at room temperature: Spectral narrowing due to a glassy state and extraordinary relaxation in a nano-cage. J Chem Phys 2018; 148:144505. [PMID: 29655335 DOI: 10.1063/1.5008448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Persistent optical hole-burning spectroscopy has been conducted for a dye molecule within a very small (∼1 nm) reverse micelle at room temperature. The spectra show a spectral narrowing due to site-selective excitation. This definitely demonstrates that the surroundings of the dye molecule are in a glassy state regardless of a solution at room temperature. On the other hand, the hole-burning spectra exhibit large shifts from excitation frequencies, and their positions are almost independent of excitation frequencies. The hole-burning spectra have been theoretically calculated by taking account of a vibronic absorption band of the dye molecule under the assumption that the surroundings of the dye molecule are in a glassy state. The calculated results agree with the experimental ones that were obtained for the dye molecule in a polymer glass for comparison, where it has been found that the ratio of hole-burning efficiencies of vibronic- to electronic-band excitations is quite high. On the other hand, the theoretical results do not explain the large spectral shift from the excitation frequency and small spectral narrowing observed in the hole-burning spectra measured for the dye-containing reverse micelle. It is thought that the spectral shift and broadening occur within the measurement time owing to the relaxation process of the surroundings that are hot with the thermal energy deposited by the dye molecule optically excited. Furthermore, the relaxation should be temporary because the cooling of the inside of the reverse micelle takes place with the dissipation of the excess thermal energy to the outer oil solvent, and so the surroundings of the dye molecule return to the glassy state and do not attain the thermal equilibrium. These results suggest that a very small reverse micelle provides a unique reaction field in which the diffusional motion can be controlled by light in a glassy state.
Collapse
Affiliation(s)
- Hiroshi Murakami
- QST Advanced Study Laboratory and Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology (QST), Kizugawa City, Kyoto 619-0215, Japan
| |
Collapse
|
20
|
Biswas R, Bagchi B. Anomalous water dynamics at surfaces and interfaces: synergistic effects of confinement and surface interactions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:013001. [PMID: 29205175 DOI: 10.1088/1361-648x/aa9b1d] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In nature, water is often found in contact with surfaces that are extended on the scale of molecule size but small on a macroscopic scale. Examples include lipid bilayers and reverse micelles as well as biomolecules like proteins, DNA and zeolites, to name a few. While the presence of surfaces and interfaces interrupts the continuous hydrogen bond network of liquid water, confinement on a mesoscopic scale introduces new features. Even when extended on a molecular scale, natural and biological surfaces often have features (like charge, hydrophobicity) that vary on the scale of the molecular diameter of water. As a result, many new and exotic features, which are not seen in the bulk, appear in the dynamics of water close to the surface. These different behaviors bear the signature of both water-surface interactions and of confinement. In other words, the altered properties are the result of the synergistic effects of surface-water interactions and confinement. Ultrafast spectroscopy, theoretical modeling and computer simulations together form powerful synergistic approaches towards an understanding of the properties of confined water in such systems as nanocavities, reverse micelles (RMs), water inside and outside biomolecules like proteins and DNA, and also between two hydrophobic walls. We shall review the experimental results and place them in the context of theory and simulations. For water confined within RMs, we discuss the possible interference effects propagating from opposite surfaces. Similar interference is found to give rise to an effective attractive force between two hydrophobic surfaces immersed and kept fixed at a separation of d, with the force showing an exponential dependence on this distance. For protein and DNA hydration, we shall examine a multitude of timescales that arise from frustration effects due to the inherent heterogeneity of these surfaces. We pay particular attention to the role of orientational correlations and modification of the same due to interaction with the surfaces.
Collapse
|
21
|
Crans DC, Peters BJ, Wu X, McLauchlan CC. Does anion-cation organization in Na+-containing X-ray crystal structures relate to solution interactions in inhomogeneous nanoscale environments: Sodium-decavanadate in solid state materials, minerals, and microemulsions. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.03.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
22
|
Dutta C, Svirida A, Mammetkuliyev M, Rukhadze M, Benderskii AV. Insight into Water Structure at the Surfactant Surfaces and in Microemulsion Confinement. J Phys Chem B 2017; 121:7447-7454. [DOI: 10.1021/acs.jpcb.7b04733] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chayan Dutta
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Anton Svirida
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Muhammet Mammetkuliyev
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Marina Rukhadze
- Faculty
of Exact and Natural Sciences, Ivane Javakhishvili Tbilisi State University, 3 I. Chavchavadze Avenue, Tbilisi 0128, Georgia
| | - Alexander V. Benderskii
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| |
Collapse
|
23
|
Chatzidaki MD, Papavasileiou KD, Papadopoulos MG, Xenakis A. Reverse Micelles As Antioxidant Carriers: An Experimental and Molecular Dynamics Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5077-5085. [PMID: 28481539 DOI: 10.1021/acs.langmuir.7b00213] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Water-in-oil microemulsions with biocompatible components were formulated to be used as carriers of natural antioxidants, such as hydroxytyrosol (HT) and gallic acid (GA). The system was composed of a mixture of natural surfactants, lecithin and monoglycerides, medium chain triglycerides, and aqueous phase. A dual approach was undertaken to study the structure and dynamics of these complicated systems. First, experimental data were collected by using adequate techniques, such as dynamic light scattering (DLS) and electron paramagnetic resonance (EPR) spectroscopy. Following this, a coarse-grained molecular dynamics (CGMD) study based on the experimental composition using the MARTINI force field was conducted. The simulations revealed the spontaneous formation of reverse micelles (RMs) starting from completely random initial conformations, underlying their enhanced thermodynamic stability. The location of the bioactive molecules, as well as the structure of the RM, were in accordance with the experimental findings. Furthermore, GA molecules were found to be located inside the water core, in contrast to the HT ones, which seem to lie at the surfactant interfacial layer. The difference in the antioxidants' molecular location was only revealed in detail from the computational analysis and explains the RM's swelling observed by GA in DLS measurements.
Collapse
Affiliation(s)
- Maria D Chatzidaki
- Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation , 116 35 Athens, Greece
| | - Konstantinos D Papavasileiou
- Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation , 116 35 Athens, Greece
- National Center for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology , Aghia Paraskevi Attikis, 153 10 Athens, Greece
| | - Manthos G Papadopoulos
- Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation , 116 35 Athens, Greece
| | - Aristotelis Xenakis
- Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation , 116 35 Athens, Greece
| |
Collapse
|
24
|
Yuan R, Yan C, Nishida J, Fayer MD. Dynamics in a Water Interfacial Boundary Layer Investigated with IR Polarization-Selective Pump–Probe Experiments. J Phys Chem B 2017; 121:4530-4537. [DOI: 10.1021/acs.jpcb.7b01028] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Rongfeng Yuan
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Chang Yan
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jun Nishida
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Michael D. Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| |
Collapse
|
25
|
Aferni AE, Guettari M, Tajouri T. Determination of the Water/AOT/Isooctane Reverse Micelles Size Parameters from Their Refractive Index Data. J SOLUTION CHEM 2017. [DOI: 10.1007/s10953-016-0563-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
26
|
Wiebenga-Sanford BP, DiVerdi J, Rithner CD, Levinger NE. Nanoconfinement's Dramatic Impact on Proton Exchange between Glucose and Water. J Phys Chem Lett 2016; 7:4597-4601. [PMID: 27779880 DOI: 10.1021/acs.jpclett.6b01651] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Glucose nanoconfined by solubilization in water-containing AOT (sodium bis(2-ethylhexyl) sulfosuccinate) reverse micelles has been investigated using 1H NMR. NMR spectra reveal well-defined signals for the glucose hydroxyl groups that suggest slow chemical exchange between them and the water hydroxyl groups. Using the EXSY (ZZ-exchange) method, the chemical exchange rate from water to glucose hydroxyl groups was measured for glucose in reverse micelles as a function of size (water pool diameter of ∼1-5 nm) at 25 °C. The chemical exchange rates observed in the nanoconfined interior are dramatically slower (5-20 times) than those observed for glucose in bulk aqueous solution at the same concentration as the micelle interior. Exchange rate constants are calculated via a mechanism that accounts for these observations, and implications of these results are presented and discussed.
Collapse
Affiliation(s)
| | - Joseph DiVerdi
- Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States
| | - Christopher D Rithner
- Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States
| | - Nancy E Levinger
- Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States
| |
Collapse
|
27
|
Abel S, Galamba N, Karakas E, Marchi M, Thompson WH, Laage D. On the Structural and Dynamical Properties of DOPC Reverse Micelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10610-10620. [PMID: 27649391 DOI: 10.1021/acs.langmuir.6b02566] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The structure and dynamics of phospholipid reverse micelles are studied by molecular dynamics. We report all-atom unconstrained simulations of 1,2-dioleoyl-sn-phosphatidylcholine (DOPC) reverse micelles in benzene of increasing sizes, with water-to-surfactant number ratios ranging from W0 = 1 to 16. The aggregation number, i.e., the number of DOPC molecules per reverse micelle, is determined to fit experimental light-scattering measurements of the reverse micelle diameter. The simulated reverse micelles are found to be approximately spherical. Larger reverse micelles (W0 > 4) exhibit a layered structure with a water core and the hydration structure of DOPC phosphate head groups is similar to that found in phospholipid membranes. In contrast, the structure of smaller reverse micelles (W0 ≤ 4) cannot be described as a series of concentric layers successively containing water, surfactant head groups, and surfactant tails, and the head groups are only partly hydrated and frequently present in the core. The dynamics of water molecules within the phospholipid reverse micelles slow down as the reverse micelle size decreases, in agreement with prior studies on AOT and Igepal reverse micelles. However, the average water reorientation dynamics in DOPC reverse micelles is found to be much slower than in AOT and Igepal reverse micelles with the same W0 ratio. This is explained by the smaller water pool and by the stronger interactions between water and the charged head groups, as confirmed by the red-shift of the computed infrared line shape with decreasing W0.
Collapse
Affiliation(s)
- Stéphane Abel
- Commissariat à l'Energie Atomique et aux Energies Alternatives, DRF/iBiTEC-S/SB2SM & CNRS UMR 9198, 91191 Saclay, France
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, F-91198 Cedex Gif-sur-Yvette, France
| | - Nuno Galamba
- Ecole Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, PASTEUR, 75005 Paris, France
| | - Esra Karakas
- Commissariat à l'Energie Atomique et aux Energies Alternatives, DRF/iBiTEC-S/SB2SM & CNRS UMR 9198, 91191 Saclay, France
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, F-91198 Cedex Gif-sur-Yvette, France
- Maison de la Simulation, USR 3441, CEA-CNRS-INRIA-Univ Paris Sud - Univ Versailles, 91191 Cedex Gif-sur-Yvette, France
| | - Massimo Marchi
- Commissariat à l'Energie Atomique et aux Energies Alternatives, DRF/iBiTEC-S/SB2SM & CNRS UMR 9198, 91191 Saclay, France
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, F-91198 Cedex Gif-sur-Yvette, France
| | - Ward H Thompson
- Department of Chemistry, University of Kansas , Lawrence, Kansas 66045, United States
| | - Damien Laage
- Ecole Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, PASTEUR, 75005 Paris, France
| |
Collapse
|
28
|
Cerveny S, Mallamace F, Swenson J, Vogel M, Xu L. Confined Water as Model of Supercooled Water. Chem Rev 2016; 116:7608-25. [PMID: 26940794 DOI: 10.1021/acs.chemrev.5b00609] [Citation(s) in RCA: 171] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Water in confined geometries has obvious relevance in biology, geology, and other areas where the material properties are strongly dependent on the amount and behavior of water in these types of materials. Another reason to restrict the size of water domains by different types of geometrical confinements has been the possibility to study the structural and dynamical behavior of water in the deeply supercooled regime (e.g., 150-230 K at ambient pressure), where bulk water immediately crystallizes to ice. In this paper we give a short review of studies with this particular goal. However, from these studies it is also clear that the interpretations of the experimental data are far from evident. Therefore, we present three main interpretations to explain the experimental data, and we discuss their advantages and disadvantages. Unfortunately, none of the proposed scenarios is able to predict all the observations for supercooled and glassy bulk water, indicating that either the structural and dynamical alterations of confined water are too severe to make predictions for bulk water or the differences in how the studied water has been prepared (applied cooling rate, resulting density of the water, etc.) are too large for direct and quantitative comparisons.
Collapse
Affiliation(s)
- Silvina Cerveny
- Centro de Física de Materiales (CFM CSIC/EHU) - Material Physics Centre (MPC) , Paseo Manuel de Lardizabal 5, 20018 San Sebastian, Spain.,Donostia International Physics Center , Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain
| | - Francesco Mallamace
- Dipartimento di Fisica, Università di Messina , Vill. S. Agata, CP 55, I-98166 Messina, Italy
| | - Jan Swenson
- Department of Physics, Chalmers University of Technology , SE-412 96 Göteborg, Sweden
| | - Michael Vogel
- Institut für Festkörperphysik, Technische Universität Darmstadt , Hochschulstraße 6, 64289 Darmstadt, Germany
| | - Limei Xu
- International Centre for Quantum Materials and School of Physics, Peking University , , Beijing 100871, China.,Collaborative Innovation Center of Quantum Matter , Beijing 100871, China
| |
Collapse
|
29
|
Mantha S, Yethiraj A. Dynamics of water confined in lyotropic liquid crystals: Molecular dynamics simulations of the dynamic structure factor. J Chem Phys 2016; 144:084504. [DOI: 10.1063/1.4942471] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Sriteja Mantha
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Arun Yethiraj
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| |
Collapse
|
30
|
Hanot S, Lyonnard S, Mossa S. Sub-diffusion and population dynamics of water confined in soft environments. NANOSCALE 2016; 8:3314-3325. [PMID: 26690685 DOI: 10.1039/c5nr05853h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have studied by using molecular dynamics computer simulations the dynamics of water confined in ionic surfactant phases, ranging from well ordered lamellar structures to micelles at low and high water loading, respectively. We have analysed in depth the main dynamical features in terms of mean-squared displacements and intermediate scattering functions, and found clear evidence of sub-diffusive behaviour. We have identified water molecules lying at the charged interface with the hydrophobic confining matrix as the main factor responsible for this unusual feature, and given a comprehensive picture of dynamics based on a very precise analysis of lifetimes at the interface. We conclude by providing, for the first time to our knowledge, a unique framework for rationalizing the existence of important dynamical heterogeneities in fluids adsorbed in soft confining environments.
Collapse
Affiliation(s)
- Samuel Hanot
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France.
| | - Sandrine Lyonnard
- Univ. Grenoble Alpes, INAC-SPRAM, F-38000 Grenoble, France. and CNRS, INAC-SPRAM, F-38000 Grenoble, France and CEA, INAC-SPRAM, F-38000 Grenoble, France.
| | - Stefano Mossa
- Univ. Grenoble Alpes, INAC-SPRAM, F-38000 Grenoble, France. and CNRS, INAC-SPRAM, F-38000 Grenoble, France and CEA, INAC-SPRAM, F-38000 Grenoble, France.
| |
Collapse
|
31
|
Hande VR, Chakrabarty S. Exploration of the presence of bulk-like water in AOT reverse micelles and water-in-oil nanodroplets: the role of charged interfaces, confinement size and properties of water. Phys Chem Chem Phys 2016; 18:21767-79. [DOI: 10.1039/c6cp04378j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We show that the distance from the interface at which bulk-like properties are recovered strongly depends on the choice of order parameter being probed: translational < tetrahedral ≪ dipolar orientation.
Collapse
Affiliation(s)
- Vrushali R. Hande
- Physical and Materials Chemistry Division
- CSIR-National Chemical Laboratory
- Pune-411008
- India
| | - Suman Chakrabarty
- Physical and Materials Chemistry Division
- CSIR-National Chemical Laboratory
- Pune-411008
- India
| |
Collapse
|
32
|
Mukherjee B. Microscopic origin of temporal heterogeneities in translational dynamics of liquid water. J Chem Phys 2015; 143:054503. [PMID: 26254657 DOI: 10.1063/1.4927709] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Liquid water is known to reorient via a combination of large angular jumps (due to exchange of hydrogen bonding (H-bond) partners) and diffusive orientations. Translation of the molecule undergoing the orientational jump and its initial and final H-bond acceptors plays a key role in the microscopic reorientation process. Here, we partition the translational dynamics into those occurring during intervals when rotating water molecules (and their initial and final H-bonding partners) undergo orientational jump and those arising when molecules wait between consecutive orientational jumps. These intervals are chosen in such a way that none of the four possible H-bonds involving the chosen water molecule undergo an exchange process within its duration. Translational dynamics is analysed in terms of the distribution of particle displacements, van Hove functions, and its moments. We observe that the translational dynamics, calculated from molecular dynamics simulations of liquid water, is fastest during the orientational jumps and slowest during periods of waiting. The translational dynamics during all temporal intervals shows an intermediate behaviour. This is the microscopic origin of temporal dynamic heterogeneity in liquid water, which is mild at 300 K and systematically increases with supercooling. Study of such partitioned dynamics in supercooled water shows increased disparity in dynamics occurring in the two different types of intervals. Nature of the distribution of particle displacements in supercooled water is investigated and it reveals signatures non-Gaussian behaviour.
Collapse
Affiliation(s)
- Biswaroop Mukherjee
- Thematic Unit of Excellence-Computational Materials Science, S. N. Bose National Centre for Basic Sciences, Block JD, Sector-III, Salt Lake, Kolkata 700098, India
| |
Collapse
|
33
|
Basu I, Manna M, Mukhopadhyay C. Insights into the behavioral difference of water in the presence of GM1. FEBS Lett 2015; 589:3887-92. [DOI: 10.1016/j.febslet.2015.11.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/16/2015] [Accepted: 11/16/2015] [Indexed: 11/26/2022]
|
34
|
Aleksandrova R, Philipp M, Müller U, Riobóo RJ, Ostermeyer M, Sanctuary R, Müller-Buschbaum P, Krüger JK. phase instability and molecular kinetics provoked by repeated crossing of the demixing transition of PNIPAM solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:11792-11801. [PMID: 25215653 DOI: 10.1021/la5026763] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The demixing process of aqueous poly(N-isopropylacrylamide) (PNIPAM) solutions can occur either via a nucleation and growth process or via spinodal decomposition. The ensuing self-assembly, leading to heterogeneous morphologies within the PNIPAM solution, is codetermined by kinetic processes caused by molecular transport. By subjecting PNIPAM solutions to cyclic changes in temperature leading to repeated crossing of the demixing transition, we are able to assess the importance of kinetics as well as of overheating and supercooling of the phase transition within the metastable range delimited by the binodal and spinodal lines. First indications about the location of these stability limits for the low- and high-temperature phases, separated by about 1.6 K, could be gained by detailed kinetic studies of the refractive index. These investigations are made possible due to the novel technique of temperature-modulated optical refractometry.
Collapse
Affiliation(s)
- Ralitsa Aleksandrova
- Laboratoire de Physique des Matériaux, Université du Luxembourg , Campus Limpertsberg, 162A, avenue de la faïencerie, L-1511 Luxembourg, Luxembourg
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Koninti RK, Gavvala K, Sengupta A, Hazra P. Excited State Proton Transfer Dynamics of Topotecan Inside Biomimicking Nanocavity. J Phys Chem B 2014; 119:2363-71. [DOI: 10.1021/jp5066902] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raj Kumar Koninti
- Department
of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008, Maharashtra, India
| | - Krishna Gavvala
- Department
of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008, Maharashtra, India
| | - Abhigyan Sengupta
- Department
of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008, Maharashtra, India
| | - Partha Hazra
- Department
of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008, Maharashtra, India
| |
Collapse
|
36
|
Suffritti GB, Demontis P, Gulín-González J, Masia M. Distributions of single-molecule properties as tools for the study of dynamical heterogeneities in nanoconfined water. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:155103. [PMID: 24675399 DOI: 10.1088/0953-8984/26/15/155103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The explicit trend of the distribution functions of single-molecule rotational relaxation constants and atomic mean-square displacement are used to study the dynamical heterogeneities in nanoconfined water. The trend of the single-molecule properties distributions is related to the dynamic heterogeneities, and to the dynamic crossovers found in water clusters of different shapes and sizes and confined in a variety of zeolites. This was true in all the cases that were considered, in spite of the various shapes and sizes of the clusters. It is confirmed that the high temperature dynamical crossover occurring in the temperature range 200-230 K can be interpreted at a molecular level as the formation of almost translationally rigid clusters, characterized by some rotational freedom, hydrogen bond exchange and translational jumps as cage-to-cage processes. We also suggest a mechanism for the low temperature dynamical crossover (LTDC), falling in the temperature range 150-185 K, through which the adsorbed water clusters are made of nearly rigid sub-clusters, slightly mismatched, and thus permitting a relatively free librational motion at their borders. It appears that the condition required for LTDC to occur is the presence of highly heterogeneous environments for the adsorbed molecules, with some dangling hydrogen bonds or weaker than water-water hydrogen bonds. Under these conditions some dynamics are permitted at very low temperature, although most rotational motion is frozen. Therefore, it is unlikely, though not entirely excluded, that LTDC will be found in supercooled bulk water where no heterogeneous interface is present.
Collapse
Affiliation(s)
- G B Suffritti
- Dipartimento di Chimica e Farmacia, Università di Sassari and INSTM, Unità di ricerca di Sassari, Via Vienna 2, I-07100 Sassari, Italy
| | | | | | | |
Collapse
|
37
|
Philipp M, Kyriakos K, Silvi L, Lohstroh W, Petry W, Krüger JK, Papadakis CM, Müller-Buschbaum P. From molecular dehydration to excess volumes of phase-separating PNIPAM solutions. J Phys Chem B 2014; 118:4253-60. [PMID: 24666206 DOI: 10.1021/jp501539z] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
For aqueous poly(N-isopropyl acrylamide) (PNIPAM) solutions, a structural instability leads to the collapse and aggregation of the macromolecules at the temperature-induced demixing transition. The accompanying cooperative dehydration of the PNIPAM chains is known to play a crucial role in this phase separation. We elucidate the impact of partial dehydration of PNIPAM on the volume changes related to the phase separation of dilute to concentrated PNIPAM solutions. Quasi-elastic neutron scattering enables us to directly follow the isotropic jump diffusion behavior of the hydration water and the almost freely diffusing water. As the hydration number decreases from 8 to 2 for the demixing 25 mass % PNIPAM solution, only a partial dehydration of the PNIPAM chains occurs. Dilatation studies reveal that the transition-induced volume changes depend in a remarkable manner on the PNIPAM concentration of the solutions. The excess volume per mole of H2O molecules expelled from the solvation layers of PNIPAM during phase separation probably strongly increases from dilute to concentrated PNIPAM solutions. This finding is qualitatively related to the immense strain-softening previously observed for demixing PNIPAM solutions.
Collapse
Affiliation(s)
- Martine Philipp
- Lehrstuhl für Funktionelle Materialien/Fachgebiet Physik weicher Materie, Physik-Department, Technische Universität München , James-Franck-Str. 1, 85748 Garching, Germany
| | | | | | | | | | | | | | | |
Collapse
|
38
|
|
39
|
Maity A, Das S, Ghosh P, Das T, Seth SK, Mondal S, Gupta P, Purkayastha P. Dynamics of pyrenesemicarbazide and pyrenethiosemicarbazide in reverse micelle of AOT in n-heptane: Probing critical penetration of water molecules toward the palisade. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.09.055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
40
|
Biswas R, Furtado J, Bagchi B. Layerwise decomposition of water dynamics in reverse micelles: A simulation study of two-dimensional infrared spectrum. J Chem Phys 2013; 139:144906. [DOI: 10.1063/1.4824446] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
|
41
|
Bakulin AA, Cringus D, Pieniazek PA, Skinner JL, Jansen TLC, Pshenichnikov MS. Dynamics of water confined in reversed micelles: multidimensional vibrational spectroscopy study. J Phys Chem B 2013; 117:15545-58. [PMID: 23980543 DOI: 10.1021/jp405853j] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Here we perform a comprehensive study of ultrafast molecular and vibrational dynamics of water confined in small reversed micelles (RMs). The molecular picture is elucidated with two-dimensional infrared (2D IR) spectroscopy of water OH stretch vibrations and molecular dynamics simulations, bridged by theoretical calculations of linear and 2D IR vibrational spectra. To investigate the effects of intermolecular coupling, experiments and modeling are performed for isotopically diluted (HDO in D2O) and undiluted (H2O) water. We put a separation of water inside RMs into two subensembles (water-bound and surfactant-bound molecules), observed by many before, on a solid theoretical basis. Water molecules fully attached to the lipid interface ("shell" water) are decoupled from one another and from the central water nanopool ("core" water). The environmental fluctuations are largely "frozen" for the shell water, while the core waters demonstrate much faster dynamics but still not as fast as in the bulk case. A substantial nanoconfinement effect on the dynamics of the core water is observed after disentanglement of the shell water contribution, which is fully confirmed by the simulations of 2D IR spectra. Current results provide new insights into interaction between biological objects like membranes or proteins with the surrounding aqueous bath, and highlight peculiarities in vibrational energy redistribution near the lipid surface.
Collapse
Affiliation(s)
- Artem A Bakulin
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | | | | | | | | | | |
Collapse
|
42
|
Das J, Flenner E, Kosztin I. Anomalous diffusion of water molecules in hydrated lipid bilayers. J Chem Phys 2013; 139:065102. [DOI: 10.1063/1.4817322] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
43
|
Hansen FY, Peters GH, Taub H, Miskowiec A. Diffusion of water and selected atoms in DMPC lipid bilayer membranes. J Chem Phys 2013. [PMID: 23206034 DOI: 10.1063/1.4767568] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular dynamics simulations have been used to determine the diffusion of water molecules as a function of their position in a fully hydrated freestanding 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) bilayer membrane at 303 K and 1 atm. The diffusion rate of water in a ∼10 Å thick layer just outside the membrane surface is reduced on average by a factor of ∼2 relative to bulk. For water molecules penetrating deeper into the membrane, there is an increasing reduction in the average diffusion rate with up to one order of magnitude decrease for those deepest in the membrane. A comparison with the diffusion rate of selected atoms in the lipid molecules shows that ∼6 water molecules per lipid molecule move on the same time scale as the lipids and may therefore be considered to be tightly bound to them. The quasielastic neutron scattering functions for water and selected atoms in the lipid molecule have been simulated and compared to observed quasielastic neutron scattering spectra from single-supported bilayer DMPC membranes.
Collapse
Affiliation(s)
- F Y Hansen
- Department of Chemistry, Technical University of Denmark, IK 207 DTU, DK-2800 Lyngby, Denmark.
| | | | | | | |
Collapse
|
44
|
Synthesis and photophysical properties of side-chain chlorinated benzo[a]phenoxazinium chlorides. Tetrahedron 2013. [DOI: 10.1016/j.tet.2013.01.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
45
|
Ladanyi BM. Computer simulation studies of counterion effects on the properties of surfactant systems. Curr Opin Colloid Interface Sci 2013. [DOI: 10.1016/j.cocis.2012.12.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
46
|
Chiapponi C, Di Bari MT, Gerelli Y, Deriu A, Chiessi E, Finelli I, Paradossi G, Russina M, Izaola Z, Sakai VG. Water dynamics in physical hydrogels based on partially hydrophobized hyaluronic acid. J Phys Chem B 2012; 116:12915-21. [PMID: 23067014 DOI: 10.1021/jp303657a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The dynamics of hyaluronate-based hydrogels has been investigated by quasielastic neutron scattering (QENS). Hyaluronate (HYA) has been compared, in the same conditions of temperature and polymer concentration, to a chemically modified form, HYADD, in which the backbone has been grafted with a hexadecyl (C(16)) side-chain with a degree of substitution of about 2% (mol/mol). This modification increases the hydrophobicity of the polysaccharide and leads to a stable gel already at polymer concentration of 0.3% (w/v), yielding a viscosupplementation with less quantity of polysaccharide. The time-scale covered by our measurements probes both water and segmental biopolymer motions. In both systems, the local dynamics of the network in the ps time-scale is mostly due to local reorientational motions of side groups. Such motions are not significantly affected by the small amount of aliphatic chains forming the hydrophobic junctions in HYADD. The diffusivity of water in both HYA and HYADD coincides with that of pure water within the experimental uncertainty. This result confirms previous ones on the dynamics of water in HYA solutions and it is of relevance for biomedical applications of hyaluronate-based systems because it affects the diffusive processes of metabolites and their interaction with tissues.
Collapse
Affiliation(s)
- Chiara Chiapponi
- Dipartimento di Fisica e Scienze della Terra, Università di Parma and CNISM, Parma, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Crans DC, Levinger NE. The conundrum of pH in water nanodroplets: sensing pH in reverse micelle water pools. Acc Chem Res 2012; 45:1637-45. [PMID: 22812536 DOI: 10.1021/ar200269g] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In aqueous environments, acidity is arguably the most important property dictating the chemical, physical, and biological processes that can occur. However, in a variety of environments where the minuscule size limits the number of water molecules, the conventional macroscopic description of pH is no longer valid. This situation arises for any and all nanoscopically confined water including cavities in minerals, porous solids, zeolites, atmospheric aerosols, enzyme active sites, membrane channels, and biological cells and organelles. To understand pH in these confined spaces, we have explored reverse micelles as a model system that confines water to nanoscale droplets. At the appropriate concentrations, reverse micelles form in ternary or higher order solutions of nonpolar solvent, polar solvent (usually water), and amphipathic molecules, usually surfactants or lipids. Measuring the acidity, or local density of protons, commonly known as pH, of these nanoscopic water pools in reverse micelles is challenging. First, because the volume of the water in these reverse micelles is so minute, we cannot probe its proton concentration using traditional pH meters. Second, the traditional concept of pH breaks down in a nanosystem that includes fewer than 10(7) water molecules. Third, the interpretation of results from studies attempting to measure acidity or pH in these environments is nontrivial because the conditions fall outside the accepted IUPAC definition for pH. Researchers have developed experimental methods to measure acidity indirectly using various spectroscopic probe molecules. Most measurements of intramicellar pH have employed optical spectroscopy of organic probe molecules containing at least one labile proton coupled to electronic transitions to track pH changes in the environment. These indirect measurements of the pH reflect the local environment sensed by the probe and are complicated by the probe location within the sample and how that location affects properties such as pK(a). Thus, interpretation of the measurement in the highly heterogeneous reverse micellar environment can be challenging. Organic pH probes can often produce ambiguous acidity measurements, because the probes can readily associate with or penetrate the micellar interface. Protonation can also dramatically change the polarity of the probe and shift the probe's location within the system. As a result, researchers have developed highly charged pH-sensitive probes such as hydroxypyrene trisulfonate, vanadate or phosphate that reside in the water pool both before and after protonation. For inorganic probes researchers have used multinuclear NMR spectroscopy to directly measure conditions in the water droplet. Regardless of the probe and method employed, reverse micellar studies include many implicit assumptions. All reported pH measurements comprise averages of molecular ensembles rather than the response of a single molecule. Experiments also represent averages of the dynamic reverse micelles over the time of the experiments. Thus the experiments report results from an average molecular position, pK(a), ionic strength, viscosity, etc. Although the exact meaning of pH in nanosized waterpools challenges scientific intuition and experimental data are non-trivial to interpret, continued experimental studies are critical to improve understanding of these nanoscopic water pools. Experimental data will allow theorists the tools to develop the models that further explore the meaning of pH in nanosized environments.
Collapse
Affiliation(s)
- Debbie C. Crans
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, United States
| | - Nancy E. Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, United States
| |
Collapse
|
48
|
Kosmella S, Koetz J. Polymer-modified w/o microemulsions - with tunable droplet-droplet interactions. Curr Opin Colloid Interface Sci 2012. [DOI: 10.1016/j.cocis.2012.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
49
|
Biedermann F, Uzunova VD, Scherman OA, Nau WM, De Simone A. Release of High-Energy Water as an Essential Driving Force for the High-Affinity Binding of Cucurbit[n]urils. J Am Chem Soc 2012; 134:15318-23. [DOI: 10.1021/ja303309e] [Citation(s) in RCA: 401] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Frank Biedermann
- Melville Laboratory for Polymer
Synthesis and Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, U.K
| | - Vanya D. Uzunova
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen,
Germany
| | - Oren A. Scherman
- Melville Laboratory for Polymer
Synthesis and Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, U.K
| | - Werner M. Nau
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen,
Germany
| | - Alfonso De Simone
- Division of Molecular
Biosciences, Imperial College London, South
Kensington, SW7 2AZ,
U.K
| |
Collapse
|
50
|
Correa NM, Silber JJ, Riter RE, Levinger NE. Nonaqueous Polar Solvents in Reverse Micelle Systems. Chem Rev 2012; 112:4569-602. [DOI: 10.1021/cr200254q] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- N. Mariano Correa
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia
Postal #3, C.P. X5804BYA Río Cuarto, Argentina
| | - Juana J. Silber
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia
Postal #3, C.P. X5804BYA Río Cuarto, Argentina
| | - Ruth E. Riter
- Department of Chemistry, Agnes Scott College, Decatur, Georgia 30030-3770, United
States
| | - Nancy E. Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872,
United States
| |
Collapse
|