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Nam JH, Nayak G, Exarhos S, Mueller CM, Xu D, Schatz GC, Bruggeman PJ. Mechanisms of controlled stabilizer-free synthesis of gold nanoparticles in liquid aerosol containing plasma. Chem Sci 2024; 15:11643-11656. [PMID: 39055030 PMCID: PMC11268499 DOI: 10.1039/d4sc01192a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 06/09/2024] [Indexed: 07/27/2024] Open
Abstract
The interaction between low-temperature plasma and liquid enables highly reactive solution phase chemistry and fast reaction kinetics. In this work, we demonstrate the rapid synthesis of stabilizer-free, spherical and crystalline gold nanoparticles (AuNP). More than 70% of gold ion complex (AuCl- 4) conversion is achieved within a droplet residence time in the plasma of ∼10 ms. The average size of the AuNPs increases with an increase in the droplet residence time and the particle synthesis showed a power threshold effect suggesting the applicability of the classical nucleation theory. Leveraging UV-vis absorption and emission spectroscopy, and nanoparticle size distributions obtained from TEM measurements, we showed that the AuCl- 4 conversion exceeded by 250 times the maximum faradaic efficiency. We identified important roles of both short-lived reducing species including solvated electrons and possibly vacuum ultraviolet (VUV) photons, and long-lived species, H2O2, in the reduction of AuCl- 4. A quantitative investigation was performed by a 1-D reaction-diffusion model which includes transport, plasma-enabled interfacial reduction of AuCl- 4, classical nucleation, monomer absorption and autocatalytic surface growth enabled by H2O2. The model shows good agreement with the experimental results. The timescale analysis of the simulation revealed that nucleation is enabled by fast reduction of gold ions, and autocatalytic growth mainly determines the particle size and is responsible for the majority of the ion precursor conversion while also explaining the excessively large faradaic efficiency found experimentally.
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Affiliation(s)
- Jae Hyun Nam
- Department of Mechanical Engineering, University of Minnesota Minneapolis MN-55455 USA
| | - Gaurav Nayak
- Department of Mechanical Engineering, University of Minnesota Minneapolis MN-55455 USA
| | - Stephen Exarhos
- Department of Mechanical Engineering, University of Minnesota Minneapolis MN-55455 USA
| | - Chelsea M Mueller
- Department of Chemistry, Northwestern University Evanston IL-60208 USA
| | - Dongxuan Xu
- Department of Mechanical Engineering, University of Minnesota Minneapolis MN-55455 USA
| | - George C Schatz
- Department of Chemistry, Northwestern University Evanston IL-60208 USA
| | - Peter J Bruggeman
- Department of Mechanical Engineering, University of Minnesota Minneapolis MN-55455 USA
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2
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Huang H, Xue L, Lu G, Cheng S, Bu Y. Hydrated electrons as nodes in porous clathrate hydrates. J Chem Phys 2023; 158:114504. [PMID: 36948798 DOI: 10.1063/5.0135335] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
We investigate the structures of hydrated electrons (e- aq) in one of water's solid phases, namely, clathrate hydrates (CHs). Using density functional theory (DFT) calculations, DFT-based ab initio molecular dynamics (AIMD), and path-integral AIMD simulations with periodic boundary conditions, we find that the structure of the e- aq@node model is in good agreement with the experiment, suggesting that an e- aq could form a node in CHs. The node is a H2O defect in CHs that is supposed to be composed of four unsaturated hydrogen bonds. Since CHs are porous crystals that possess cavities that can accommodate small guest molecules, we expect that these guest molecules can be used to tailor the electronic structure of the e- aq@node, and it leads to experimentally observed optical absorption spectra of CHs. Our findings have a general interest and extend the knowledge of e- aq into porous aqueous systems.
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Affiliation(s)
- Haibei Huang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, People's Republic of China
| | - Lijuan Xue
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, People's Republic of China
| | - Gang Lu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, People's Republic of China
| | - Shibo Cheng
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, People's Republic of China
| | - Yuxiang Bu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, People's Republic of China
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3
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Carter-Fenk K, Johnson BA, Herbert JM, Schenter GK, Mundy CJ. Birth of the Hydrated Electron via Charge-Transfer-to-Solvent Excitation of Aqueous Iodide. J Phys Chem Lett 2023; 14:870-878. [PMID: 36657160 DOI: 10.1021/acs.jpclett.2c03460] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
A primary means to generate hydrated electrons in laboratory experiments is excitation to the charge-transfer-to-solvent (CTTS) state of a solute such as I-(aq), but this initial step in the genesis of e-(aq) has never been simulated directly using ab initio molecular dynamics. We report the first such simulations, combining ground- and excited-state simulations of I-(aq) with a detailed analysis of fluctuations in the Coulomb potential experienced by the nascent solvated electron. What emerges is a two-step picture of the evolution of e-(aq) starting from the CTTS state: I-(aq) + hν → I-*(aq) → I•(aq) + e-(aq). Notably, the equilibrated ground state of e-(aq) evolves from I-*(aq) without any nonadiabatic transitions, simply as a result of solvent reorganization. The methodology used here should be applicable to other photochemical electron transfer processes in solution, an important class of problems directly relevant to photocatalysis and energy transfer.
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Affiliation(s)
- Kevin Carter-Fenk
- Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington99352, United States
- Department of Chemistry, University of California, Berkeley, California94720, United States
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio43210, United States
| | - Britta A Johnson
- Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington99352, United States
| | - John M Herbert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio43210, United States
| | - Gregory K Schenter
- Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington99352, United States
| | - Christopher J Mundy
- Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington99352, United States
- Department of Chemical Engineering, University of Washington, Seattle, Washington98195, United States
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4
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Prasselsperger A, Coughlan M, Breslin N, Yeung M, Arthur C, Donnelly H, White S, Afshari M, Speicher M, Yang R, Villagomez-Bernabe B, Currell FJ, Schreiber J, Dromey B. Real-Time Electron Solvation Induced by Bursts of Laser-Accelerated Protons in Liquid Water. PHYSICAL REVIEW LETTERS 2021; 127:186001. [PMID: 34767414 DOI: 10.1103/physrevlett.127.186001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/24/2021] [Indexed: 06/13/2023]
Abstract
Understanding the mechanisms of proton energy deposition in matter and subsequent damage formation is fundamental to radiation science. Here we exploit the picosecond (10^{-12} s) resolution of laser-driven accelerators to track ultrafast solvation dynamics for electrons due to proton radiolysis in liquid water (H_{2}O). Comparing these results with modeling that assumes initial conditions similar to those found in photolysis reveals that solvation time due to protons is extended by >20 ps. Supported by magnetohydrodynamic theory this indicates a highly dynamic phase in the immediate aftermath of the proton interaction that is not accounted for in current models.
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Affiliation(s)
- A Prasselsperger
- Fakultät für Physik, Ludwig-Maximilians-Universität München, 85748 Garching, Germany
- Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, United Kingdom
| | - M Coughlan
- Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, United Kingdom
| | - N Breslin
- Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, United Kingdom
| | - M Yeung
- Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, United Kingdom
| | - C Arthur
- Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, United Kingdom
| | - H Donnelly
- Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, United Kingdom
| | - S White
- Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, United Kingdom
| | - M Afshari
- Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, United Kingdom
| | - M Speicher
- Fakultät für Physik, Ludwig-Maximilians-Universität München, 85748 Garching, Germany
| | - R Yang
- Fakultät für Physik, Ludwig-Maximilians-Universität München, 85748 Garching, Germany
| | - B Villagomez-Bernabe
- The Dalton Cumbria Facility and the School of Chemistry, The University of Manchester, Oxford Rd, Manchester M13 9PL, United Kingdom
| | - F J Currell
- The Dalton Cumbria Facility and the School of Chemistry, The University of Manchester, Oxford Rd, Manchester M13 9PL, United Kingdom
| | - J Schreiber
- Fakultät für Physik, Ludwig-Maximilians-Universität München, 85748 Garching, Germany
| | - B Dromey
- Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, United Kingdom
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5
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Bahry T, Denisov SA, Moisy P, Ma J, Mostafavi M. Real-Time Observation of Solvation Dynamics of Electron in Actinide Extraction Binary Solutions of Water and n-Tributyl Phosphate. J Phys Chem B 2021; 125:3843-3849. [PMID: 33650867 DOI: 10.1021/acs.jpcb.0c10831] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The excess electron in solution is a highly reactive radical involved in various radiation-induced reactions. Its solvation state critically determines the subsequent pathway and rate of transfer. For instance, water plays a dominating role in the electron-induced dealkylation of n-tributyl phosphate in actinide extraction processing. However, the underlying electron solvation processes in such systems are lacking. Herein, we directly observed the solvation dynamics of electrons in H-bonded water and n-tributyl phosphate (TBP) binary solutions with a mole fraction of water (Xw) varying from 0.05 to 0.51 under ambient conditions. Following the evolution of the absorption spectrum of trapped electrons (not fully solvated) with picosecond resolution, we show that electrons statistically distributed would undergo preferential solvation within water molecules extracted in TBP. We determine the time scale of excess electron full solvation from the deconvoluted transient absorption-kinetical data. The process of solvent reorganization accelerates by increasing the water molar fraction, and the rate of this process is 2 orders of magnitude slower compared to bulk water. We assigned the solvation process to hydrogen network reorientation induced by a negative charge of the excess electron that strongly depends on the local water environment. Our findings suggest that water significantly stabilizes the electron in a deeper potential than the pure TBP case. In its new state, the electron is likely to inhibit the dealkylation of extractants in actinide separation.
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Affiliation(s)
- Teseer Bahry
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, P. R. China.,Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay 91405, Orsay, Cedex France
| | - Sergey A Denisov
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay 91405, Orsay, Cedex France
| | - Philippe Moisy
- CEA, DES/ISEC/DMRC, Univ. Montpellier, 34090 Marcoule, France
| | - Jun Ma
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, P. R. China
| | - Mehran Mostafavi
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay 91405, Orsay, Cedex France
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6
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Svoboda V, Michiels R, LaForge AC, Med J, Stienkemeier F, Slavíček P, Wörner HJ. Real-time observation of water radiolysis and hydrated electron formation induced by extreme-ultraviolet pulses. SCIENCE ADVANCES 2020; 6:eaaz0385. [PMID: 32010776 PMCID: PMC6968931 DOI: 10.1126/sciadv.aaz0385] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 11/26/2019] [Indexed: 05/17/2023]
Abstract
The dominant pathway of radiation damage begins with the ionization of water. Thus far, however, the underlying primary processes could not be conclusively elucidated. Here, we directly study the earliest steps of extreme ultraviolet (XUV)-induced water radiolysis through one-photon excitation of large water clusters using time-resolved photoelectron imaging. Results are presented for H2O and D2O clusters using femtosecond pump pulses centered at 133 or 80 nm. In both excitation schemes, hydrogen or proton transfer is observed to yield a prehydrated electron within 30 to 60 fs, followed by its solvation in 0.3 to 1.0 ps and its decay through geminate recombination on a ∼10-ps time scale. These results are interpreted by comparison with detailed multiconfigurational non-adiabatic ab-initio molecular dynamics calculations. Our results provide the first comprehensive picture of the primary steps of radiation chemistry and radiation damage and demonstrate new approaches for their study with unprecedented time resolution.
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Affiliation(s)
- Vít Svoboda
- Laboratory of Physical Chemistry, ETH-Zürich, 8093 Zürich, Switzerland
| | - Rupert Michiels
- Institute of Physics, University of Freiburg, 79104 Freiburg, Germany
| | - Aaron C. LaForge
- Institute of Physics, University of Freiburg, 79104 Freiburg, Germany
| | - Jakub Med
- Department of Physical chemistry, UCT Prague, 16628 Prague, Czech Republic
| | | | - Petr Slavíček
- Department of Physical chemistry, UCT Prague, 16628 Prague, Czech Republic
| | - Hans Jakob Wörner
- Laboratory of Physical Chemistry, ETH-Zürich, 8093 Zürich, Switzerland
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7
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Maza WA, Breslin VM, Plymale NT, DeSario PA, Epshteyn A, Owrutsky JC, Pate BB. Nanosecond transient absorption studies of the pH-dependent hydrated electron quenching by HSO 3. Photochem Photobiol Sci 2019; 18:1526-1532. [PMID: 30984955 DOI: 10.1039/c9pp00063a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The large standard reduction potential of an aqueous solvated electron (eaq-, E° = -2.9 V) makes it an attractive candidate for reductive treatment of wastewater contaminants. Using transient absorption spectroscopy, the nanosecond to microsecond dynamics of eaq- generated from 10 mM solutions of Na2SO3 at pH 4 to 11 in H2O and D2O are characterized, resulting in the determination that between pH 4 and 9 it is the HSO3-, and not H+ as previously postulated by others, that effectively quenches eaq-. The observed bimolecular quenching rate constant (k = 1.2 × 108 M-1 s-1) for eaq- deactivation by HSO3- is found to be consistent with a Brønsted acid catalysis mechanism resulting in formation of H˙ and SO32-. A large solvent isotope effect is observed from the lifetimes of the eaq- in H2O compared to D2O (kH2O/kD2O = 4.4). In addition, the bimolecular rate constant for eaq- deactivation by DSO3- (k = 2.7 × 107 M-1 s-1) is found to be an order of magnitude lower than by HSO3-. These results highlight the role of acids, such as HSO3-, in competition with organic contaminant targets for eaq- and, by extension, that knowledge of the pKa of eaq- sources can be a predictive measure of the effective pH range for the treatment of wastewater contaminants.
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Affiliation(s)
- William A Maza
- National Research Council, U.S. Naval Research Laboratory, Washington, D.C. 20375, USA.
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8
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Ma J, Marignier JL, Pernot P, Houée-Levin C, Kumar A, Sevilla MD, Adhikary A, Mostafavi M. Direct observation of the oxidation of DNA bases by phosphate radicals formed under radiation: a model of the backbone-to-base hole transfer. Phys Chem Chem Phys 2018; 20:14927-14937. [PMID: 29786710 DOI: 10.1039/c8cp00352a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In irradiated DNA, by the base-to-base and backbone-to-base hole transfer processes, the hole (i.e., the unpaired spin) localizes on the most electropositive base, guanine. Phosphate radicals formed via ionization events in the DNA-backbone must play an important role in the backbone-to-base hole transfer process. However, earlier studies on irradiated hydrated DNA, on irradiated DNA-models in frozen aqueous solution and in neat dimethyl phosphate showed the formation of carbon-centered radicals and not phosphate radicals. Therefore, to model the backbone-to-base hole transfer process, we report picosecond pulse radiolysis studies of the reactions between H2PO4˙ with the DNA bases - G, A, T, and C in 6 M H3PO4 at 22 °C. The time-resolved observations show that in 6 M H3PO4, H2PO4˙ causes the one-electron oxidation of adenine, guanine and thymine, by forming the cation radicals via a single electron transfer (SET) process; however, the rate constant of the reaction of H2PO4˙ with cytosine is too low (<107 L mol-1 s-1) to be measured. The rates of these reactions are influenced by the protonation states and the reorganization energies of the base radicals and of the phosphate radical in 6 M H3PO4.
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Affiliation(s)
- Jun Ma
- Laboratoire de Chimie Physique, CNRS/Université Paris-Sud 11, Bâtiment 349, 91405 Orsay, France.
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9
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Wang Y, Guo H, Zheng Q, Saidi WA, Zhao J. Tuning Solvated Electrons by Polar-Nonpolar Oxide Heterostructure. J Phys Chem Lett 2018; 9:3049-3056. [PMID: 29767527 DOI: 10.1021/acs.jpclett.8b00938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Solvated electron states at the oxide/aqueous interface represent the lowest energy charge-transfer pathways, thereby playing an important role in photocatalysis and electronic device applications. However, their energies are usually higher than the conduction band minimum (CBM), which makes the solvated electrons difficult to utilize in charge-transfer processes. Thus it is essential to stabilize the energy of the solvated electron states. Taking LaAlO3/SrTiO3 (LAO/STO) oxide heterostructure with H2O-adsorbed monolayer as a prototypical system, we show using DFT and ab initio time-dependent nonadiabatic molecular dynamics simulation that the energy and dynamics of solvated electrons can be tuned by the electric field in the polar-nonpolar oxide heterostructure. In particular, for LAO/STO with p-type interface, the CBM is contributed by the solvated electron state when LAO is thicker than four unit cells. Furthermore, the solvated electron band minimum can be partially occupied when LAO is thicker than eight unit cells. We propose that the tunability of solvated electron states can be achieved on polar-nonpolar oxide heterostructure surfaces as well as on ferroelectric oxides, which is important for charge and proton transfer at oxide/aqueous interfaces.
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Affiliation(s)
- Yanan Wang
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Hongli Guo
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- School of Physics and Technology, Center for Nanoscience and Nanotechnology, and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education , Wuhan University , Wuhan 430072 , China
| | - Qijing Zheng
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Wissam A Saidi
- Department of Mechanical Engineering and Materials Science , University of Pittsburgh , Pittsburgh , Pennsylvania 15261 , United States
| | - Jin Zhao
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
- Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
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Abstract
The ionizing radiation in aqueous solutions of gold nanoparticles, stabilized by electrostatic non-covalent intermolecular forces and steric interactions, with antimicrobial compounds, are investigated with picosecond pulse radiolysis techniques. Upon pulse radiolysis of an aqueous solution containing very low concentrations of gold nanoparticles with naked surfaces available in water (not obstructed by chemical bonds), a change to Cerenkov spectrum over a large range of wavelengths are observed and pre-solvated electrons are captured by gold nanoparticles exclusively (not by ionic liquid surfactants used to stabilize the nanoparticles). The solvated electrons are also found to decay rapidly compared with the decay kinetics in water. These very fast reactions with electrons in water could provide an enhanced oxidizing zone around gold nanoparticles and this could be the reason for radio sensitizing behavior of gold nanoparticles in radiation therapy.
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Wang F, Archirel P, Muroya Y, Yamashita S, Pernot P, Yin C, El Omar AK, Schmidhammer U, Teuler JM, Mostafavi M. Effect of the solvation state of electron in dissociative electron attachment reaction in aqueous solutions. Phys Chem Chem Phys 2018; 19:23068-23077. [PMID: 28817148 DOI: 10.1039/c7cp03997b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It is generally considered that the pre-solvated electron and the solvated electron reacting with a solute yield the same product. Silver cyanide complex, Ag(CN)2-, is used as a simple probe to demonstrate unambiguously the existence of a different reduction mechanism for pre-hydrated electrons. Using systematic multichannel transient absorption measurements at different solute concentrations from millimolar to decimolar, global data analysis and theoretical calculations, we present the dissociative electron attachment on Ag(CN)2-. The short-lived silver complex, Ag0(CN)22-, formed by hydrated electron with nanosecond pulse radiolysis, can be observed at room temperature. However, at higher temperatures only the free silver atom, Ag0, is detected, suggesting that Ag0(CN)22- dissociation is fast. Surprisingly, pulse radiolysis measurements on Ag(CN)2- reduction, performed by a 7 ps electron pulse at room temperature, show clearly that a new reduced form of silver complex, AgCN-, is produced within the pulse. This species, absorbing at 560 nm, is not formed by the hydrated electron but exclusively by its precursor. DFT calculations show that the different reactivity of the hydrated and pre-hydrated electrons can be due to the formation of different electronic states of Ag0(CN)22-: the prehydrated electron can form an excited state of this complex, which mainly dissociates into Ag0CN- + CN-.
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Affiliation(s)
- Furong Wang
- Laboratoire de Chimie Physique, UMR 8000 CNRS/Université Paris-Sud, Bât. 349, Orsay, 91405, Cedex, France.
| | - Pierre Archirel
- Laboratoire de Chimie Physique, UMR 8000 CNRS/Université Paris-Sud, Bât. 349, Orsay, 91405, Cedex, France.
| | - Yusa Muroya
- Department of Beam Materials Science, Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Shinichi Yamashita
- Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata Shirane, Tokai-mura, Naka-gun, Ibaraki 319-1188, Japan
| | - Pascal Pernot
- Laboratoire de Chimie Physique, UMR 8000 CNRS/Université Paris-Sud, Bât. 349, Orsay, 91405, Cedex, France.
| | - Chengying Yin
- Laboratoire de Chimie Physique, UMR 8000 CNRS/Université Paris-Sud, Bât. 349, Orsay, 91405, Cedex, France.
| | - Abdel Karim El Omar
- Laboratoire de Physique et Modélisation, Ecole Doctorale des Sciences et de Technologie, Lebanese University, Tripoli, Lebanon
| | - Uli Schmidhammer
- Laboratoire de Chimie Physique, UMR 8000 CNRS/Université Paris-Sud, Bât. 349, Orsay, 91405, Cedex, France.
| | - Jean-Marie Teuler
- Laboratoire de Chimie Physique, UMR 8000 CNRS/Université Paris-Sud, Bât. 349, Orsay, 91405, Cedex, France.
| | - Mehran Mostafavi
- Laboratoire de Chimie Physique, UMR 8000 CNRS/Université Paris-Sud, Bât. 349, Orsay, 91405, Cedex, France.
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12
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Ma J, Wang F, Denisov SA, Adhikary A, Mostafavi M. Reactivity of prehydrated electrons toward nucleobases and nucleotides in aqueous solution. SCIENCE ADVANCES 2017; 3:e1701669. [PMID: 29250599 PMCID: PMC5732001 DOI: 10.1126/sciadv.1701669] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 11/13/2017] [Indexed: 05/28/2023]
Abstract
DNA damage induced via dissociative attachment by low-energy electrons (0 to 20 eV) is well studied in both gas and condensed phases. However, the reactivity of ultrashort-lived prehydrated electrons ([Formula: see text]) with DNA components in a biologically relevant environment has not been fully explored to date. The electron transfer processes of [Formula: see text] to the DNA nucleobases G, A, C, and T and to nucleosides/nucleotides were investigated by using 7-ps electron pulse radiolysis coupled with pump-probe transient absorption spectroscopy in aqueous solutions. In contrast to previous results, obtained by using femtosecond laser pump-probe spectroscopy, we show that G and A cannot scavenge [Formula: see text] at concentrations of ≤50 mM. Observation of a substantial decrease of the initial yield of hydrated electrons ([Formula: see text]) and formation of nucleobase/nucleotide anion radicals at increasing nucleobase/nucleotide concentrations present direct evidence for the earliest step in reductive DNA damage by ionizing radiation. Our results show that [Formula: see text] is more reactive with pyrimidine than purine nucleobases/nucleotides with a reactivity order of T > C > A > G. In addition, analyses of transient signals show that the signal due to formation of the resulting anion radical directly correlates with the loss of the initial [Formula: see text] signal. Therefore, our results do not agree with the previously proposed dissociation of transient negative ions in nucleobase/nucleotide solutions within the timescale of these experiments. Moreover, in a molecularly crowded medium (for example, in the presence of 6 M phosphate), the scavenging efficiency of [Formula: see text] by G is significantly enhanced. This finding implies that reductive DNA damage by ionizing radiation depends on the microenvironment around [Formula: see text].
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Affiliation(s)
- Jun Ma
- Laboratoire de Chimie Physique, CNRS–Université Paris-Sud 11, Bâtiment 349, 91405 Orsay, France
| | - Furong Wang
- Laboratoire de Chimie Physique, CNRS–Université Paris-Sud 11, Bâtiment 349, 91405 Orsay, France
| | - Sergey A. Denisov
- Laboratoire de Chimie Physique, CNRS–Université Paris-Sud 11, Bâtiment 349, 91405 Orsay, France
| | - Amitava Adhikary
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309, USA
| | - Mehran Mostafavi
- Laboratoire de Chimie Physique, CNRS–Université Paris-Sud 11, Bâtiment 349, 91405 Orsay, France
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13
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Yamashita S, Ma J, Marignier JL, Hiroki A, Taguchi M, Mostafavi M, Katsumura Y. Radiation-Induced Chemical Reactions in Hydrogel of Hydroxypropyl Cellulose (HPC): A Pulse Radiolysis Study. Radiat Res 2016; 186:650-658. [DOI: 10.1667/rr14539.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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14
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Balcerzyk A, Schmidhammer U, Wang F, de la Lande A, Mostafavi M. Ultrafast Scavenging of the Precursor of H(•) Atom, (e(-), H3O(+)), in Aqueous Solutions. J Phys Chem B 2016; 120:9060-6. [PMID: 27472160 DOI: 10.1021/acs.jpcb.6b04944] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Picosecond pulse radiolysis measurements have been performed in several highly concentrated HClO4 and H3PO4 aqueous solutions containing silver ions at different concentrations. Silver ion reduction is used to unravel the ultrafast reduction reactions observed at the end of a 7 ps electron pulse. Solvated electrons and silver atoms are observed by the pulse (electron beam)-probe (supercontinuum light) method. In highly acidic solutions, ultrafast reduction of silver ions is observed, a finding that is not compatible with a reaction between the H(•) atom and silver ions, which is known to be thermally activated. In addition, silver ion reduction is found to be even more efficient in phosphoric acid solution than that in neutral solution. In the acidic solutions investigated here, the species responsible for the reduction of silver atoms is considered to be the precursor of the H(•) atom. This precursor, denoted (e(-), H3O(+)), is a pair constituting an electron (not fully solvated) and H3O(+). Its structure differs from that of the pair of a solvated electron and a hydronium ion (es(-), H3O(+)), which absorbs in the visible region. The (e(-), H3O(+)) pair , called the pre-H(•) atom here, undergoes ultrafast electron transfer and can, like the presolvated electron, reduce silver ions much faster than the H(•) atom. Moreover, it is found that with the same concentration of H3O(+) the reduction reaction is favored in the phosphoric acid solution compared to that in the perchloric acid solution because of the less-efficient electron solvation process. The kinetics show that among the three reducing species, (e(-), H3O(+)), (es(-), H3O(+)), and H(•) atom, the first one is the most efficient.
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Affiliation(s)
- Anna Balcerzyk
- Laboratoire de Chimie Physique, CNRS/Université Paris-Sud , Bâtiment 349, 91405 Orsay, France
| | - Uli Schmidhammer
- Laboratoire de Chimie Physique, CNRS/Université Paris-Sud , Bâtiment 349, 91405 Orsay, France
| | - Furong Wang
- Laboratoire de Chimie Physique, CNRS/Université Paris-Sud , Bâtiment 349, 91405 Orsay, France
| | - Aurélien de la Lande
- Laboratoire de Chimie Physique, CNRS/Université Paris-Sud , Bâtiment 349, 91405 Orsay, France
| | - Mehran Mostafavi
- Laboratoire de Chimie Physique, CNRS/Université Paris-Sud , Bâtiment 349, 91405 Orsay, France
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15
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Chaban VV, Prezhdo OV. Electron Solvation in Liquid Ammonia: Lithium, Sodium, Magnesium, and Calcium as Electron Sources. J Phys Chem B 2016; 120:2500-6. [PMID: 26886153 DOI: 10.1021/acs.jpcb.6b00412] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A free electron in solution, known as a solvated electron, is the smallest possible anion. Alkali and alkaline earth atoms serve as electron donors in solvents that mediate outer-sphere electron transfer. We report herein ab initio molecular dynamics simulations of lithium, sodium, magnesium, and calcium in liquid ammonia at 250 K. By analyzing the electronic properties and the ionic and solvation structures and dynamics, we systematically characterize these metals as electron donors and ammonia molecules as electron acceptors. We show that the solvated metal strongly modifies the properties of its solvation shells and that the observed effect is metal-specific. Specifically, the radius and charge exhibit major impacts. The single solvated electron present in the alkali metal systems is distributed more uniformly among the solvent molecules of each metal's two solvation shells. In contrast, alkaline earth metals favor a less uniform distribution of the electron density. Alkali and alkaline earth atoms are coordinated by four and six NH3 molecules, respectively. The smaller atoms, Li and Mg, are stronger electron donors than Na and Ca. This result is surprising, as smaller atoms in a column of the periodic table have higher ionization potentials. However, it can be explained by stronger electron donor-acceptor interactions between the smaller atoms and the solvent molecules. The structure of the first solvation shell is sharpest for Mg, which has a large charge and a small radius. Solvation is weakest for Na, which has a small charge and a large radius. Weak solvation leads to rapid dynamics, as reflected in the diffusion coefficients of NH3 molecules of the first two solvation shells and the Na atom. The properties of the solvated electrons established in the present study are important for radiation chemistry, synthetic chemistry, condensed-matter charge transfer, and energy sources.
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Affiliation(s)
- Vitaly V Chaban
- Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo , 12231-280 São José dos Campos, SP Brazil
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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16
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Chen R, Wang B, Chen L, Cai D, Li B, Chen C, Huang E, Liu C, Lin Z, Xie WB, Wang H. DNA damage-inducible transcript 4 (DDIT4) mediates methamphetamine-induced autophagy and apoptosis through mTOR signaling pathway in cardiomyocytes. Toxicol Appl Pharmacol 2016; 295:1-11. [PMID: 26825372 DOI: 10.1016/j.taap.2016.01.017] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 01/20/2016] [Accepted: 01/25/2016] [Indexed: 12/30/2022]
Abstract
Methamphetamine (METH) is an amphetamine-like psychostimulant that is commonly abused. Previous studies have shown that METH can induce damages to the nervous system and recent studies suggest that METH can also cause adverse and potentially lethal effects on the cardiovascular system. Recently, we demonstrated that DNA damage-inducible transcript 4 (DDIT4) regulates METH-induced neurotoxicity. However, the role of DDIT4 in METH-induced cardiotoxicity remains unknown. We hypothesized that DDIT4 may mediate METH-induced autophagy and apoptosis in cardiomyocytes. To test the hypothesis, we examined DDIT4 protein expression in cardiomyocytes and in heart tissues of rats exposed to METH with Western blotting. We also determined the effects on METH-induced autophagy and apoptosis after silencing DDIT4 expression with synthetic siRNA with or without pretreatment of a mTOR inhibitor rapamycin in cardiomyocytes using Western blot analysis, fluorescence microscopy and TUNEL staining. Our results showed that METH exposure increased DDIT4 expression and decreased phosphorylation of mTOR that was accompanied with increased autophagy and apoptosis both in vitro and in vivo. These effects were normalized after silencing DDIT4. On the other hand, rapamycin promoted METH-induced autophagy and apoptosis in DDIT4 knockdown cardiomyocytes. These results suggest that DDIT4 mediates METH-induced autophagy and apoptosis through mTOR signaling pathway in cardiomyocytes.
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Affiliation(s)
- Rui Chen
- Department of Forensic Medicine, School of Basic Medical Science, Southern Medical University, Guangzhou 510515, People's Republic of China; Department of Forensic Medicine, Guangdong Medical University, Dongguan 523808, People's Republic of China
| | - Bin Wang
- Department of Forensic Medicine, School of Basic Medical Science, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Ling Chen
- Department of Forensic Medicine, School of Basic Medical Science, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Dunpeng Cai
- Department of Forensic Medicine, School of Basic Medical Science, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Bing Li
- Department of Forensic Medicine, School of Basic Medical Science, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Chuanxiang Chen
- Department of Forensic Medicine, School of Basic Medical Science, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Enping Huang
- Department of Forensic Medicine, School of Basic Medical Science, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Chao Liu
- Guangzhou Forensic Science Institute, Guangzhou 510030, People's Republic of China
| | - Zhoumeng Lin
- Institute of Computational Comparative Medicine and Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
| | - Wei-Bing Xie
- Department of Forensic Medicine, School of Basic Medical Science, Southern Medical University, Guangzhou 510515, People's Republic of China.
| | - Huijun Wang
- Department of Forensic Medicine, School of Basic Medical Science, Southern Medical University, Guangzhou 510515, People's Republic of China.
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17
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Ma J, Archirel P, Pernot P, Schmidhammer U, Le Caër S, Mostafavi M. Identification of Transient Radical Anions (LiClO4)n– (n = 1–3) in THF Solutions: Experimental and Theoretical Investigation on Electron Localization in Oligomers. J Phys Chem B 2016; 120:773-84. [DOI: 10.1021/acs.jpcb.5b11315] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jun Ma
- Laboratoire de
Chimie Physique/ELYSE, UMR 8000, CNRS/Univ. Paris-Sud, Bât. 349, 91405 Orsay, Cedex, France
| | - Pierre Archirel
- Laboratoire de
Chimie Physique/ELYSE, UMR 8000, CNRS/Univ. Paris-Sud, Bât. 349, 91405 Orsay, Cedex, France
| | - Pascal Pernot
- Laboratoire de
Chimie Physique/ELYSE, UMR 8000, CNRS/Univ. Paris-Sud, Bât. 349, 91405 Orsay, Cedex, France
| | - Uli Schmidhammer
- Laboratoire de
Chimie Physique/ELYSE, UMR 8000, CNRS/Univ. Paris-Sud, Bât. 349, 91405 Orsay, Cedex, France
| | - Sophie Le Caër
- CEA/Saclay,
DSM/IRAMIS/NIMBE
UMR 3685/LIONS, Bât. 546, F-91191 Gif-sur-Yvette, Cedex, France
| | - Mehran Mostafavi
- Laboratoire de
Chimie Physique/ELYSE, UMR 8000, CNRS/Univ. Paris-Sud, Bât. 349, 91405 Orsay, Cedex, France
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18
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Musat RM, Crowell RA, Polyanskiy DE, Thomas MF, Wishart JF, Katsumura Y, Takahashi K. Ultrafast transient absorption spectrum of the room temperature Ionic liquid 1-hexyl-3-methylimidazolium bromide: Confounding effects of photo-degradation. Radiat Phys Chem Oxf Engl 1993 2015. [DOI: 10.1016/j.radphyschem.2015.07.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Balcerzyk A, Schmidhammer U, Horne G, Wang F, Ma J, Pimblott SM, de la Lande A, Mostafavi M. Unexpected Ultrafast Silver Ion Reduction: Dynamics Driven by the Solvent Structure. J Phys Chem B 2015; 119:10096-101. [DOI: 10.1021/acs.jpcb.5b04907] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anna Balcerzyk
- Laboratoire
de Chimie Physique, CNRS/Université Paris-Sud, Bâtiment
349, 91405 Orsay, France
| | - Uli Schmidhammer
- Laboratoire
de Chimie Physique, CNRS/Université Paris-Sud, Bâtiment
349, 91405 Orsay, France
| | - Gregory Horne
- Laboratoire
de Chimie Physique, CNRS/Université Paris-Sud, Bâtiment
349, 91405 Orsay, France
- Dalton
Cumbrian Facility, The University of Manchester, Westlakes Science and Technology
Park, Moor Row, Cumbria, CA24 3HA, United Kingdom
- School
of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Furong Wang
- Laboratoire
de Chimie Physique, CNRS/Université Paris-Sud, Bâtiment
349, 91405 Orsay, France
| | - Jun Ma
- Laboratoire
de Chimie Physique, CNRS/Université Paris-Sud, Bâtiment
349, 91405 Orsay, France
| | - Simon M. Pimblott
- Dalton
Cumbrian Facility, The University of Manchester, Westlakes Science and Technology
Park, Moor Row, Cumbria, CA24 3HA, United Kingdom
- School
of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Aurélien de la Lande
- Laboratoire
de Chimie Physique, CNRS/Université Paris-Sud, Bâtiment
349, 91405 Orsay, France
| | - Mehran Mostafavi
- Laboratoire
de Chimie Physique, CNRS/Université Paris-Sud, Bâtiment
349, 91405 Orsay, France
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20
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Do TD, Bowers MT. Diphenylalanine self assembly: novel ion mobility methods showing the essential role of water. Anal Chem 2015; 87:4245-52. [PMID: 25785477 DOI: 10.1021/ac5046774] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The mechanism and driving forces behind the formation of diphenylalanine (FF) nanotubes have attracted much attention in the past decades. The hollow structure of the nanotubes suggests a role for water during the self-assembly process. Here, we use novel ion-mobility mass spectrometry methods to probe the early oligomers formed by diphenylalanine peptides. Interestingly, water-bound oligomers are observed in nano-electrospray ionization (ESI) mass spectra in the absence of bulk solvent. In addition, ligated water clusters transit the ion mobility cell but (often) dissociate before detection. These water molecules are shown to be essential for the formation of diphenylalanine oligomers larger than the dimer. The ligated water molecules exist in the solvent free environment either as neutral water or as protonated water clusters, depending on the composition of solvent from which they are sprayed. Water adduction helps stabilize conformers that are otherwise energetically unstable ultimately leading to the assembly of FF nanotubes.
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Affiliation(s)
- Thanh D Do
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, United States
| | - Michael T Bowers
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, United States
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21
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Ma J, Yamashita S, Muroya Y, Katsumura Y, Mostafavi M. Deciphering the reaction between a hydrated electron and a hydronium ion at elevated temperatures. Phys Chem Chem Phys 2015; 17:22934-9. [DOI: 10.1039/c5cp04293c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The formation of a H˙ atom in liquid water from the reaction of a hydrated electron with a hydronium cation is a very challenging subject in chemical processes.
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Affiliation(s)
- Jun Ma
- Laboratoire de Chimie Physique/ELYSE
- Université Paris-Sud 11
- Orsay
- France
| | - Shinichi Yamashita
- Nuclear Professional School
- School of Engineering
- The University of Tokyo
- Naka-gun
- Japan
| | - Yusa Muroya
- The Institute of Scientific and Industrial Research (ISIR) Osaka University
- Ibaraki
- Japan
| | - Yosuke Katsumura
- Nuclear Professional School
- School of Engineering
- The University of Tokyo
- Naka-gun
- Japan
| | - Mehran Mostafavi
- Laboratoire de Chimie Physique/ELYSE
- Université Paris-Sud 11
- Orsay
- France
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22
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Yamashita S, Iwamatsu K, Maehashi Y, Taguchi M, Hata K, Muroya Y, Katsumura Y. Sequential radiation chemical reactions in aqueous bromide solutions: pulse radiolysis experiment and spur model simulation. RSC Adv 2015. [DOI: 10.1039/c5ra03101j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Pulse radiolysis experiments were carried out to observe transient absorptions of reaction intermediates produced in N2O- and Ar-saturated aqueous solutions containing 0.9–900 mM NaBr.
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Affiliation(s)
- S. Yamashita
- Nuclear Professional School
- School of Engineering
- the University of Tokyo
- Tokai-mura, Naka-gun
- Japan
| | - K. Iwamatsu
- Department of Nuclear Engineering and Management
- School of Engineering
- the University of Tokyo
- Bunkyo-ku
- Japan
| | - Y. Maehashi
- Department of Nuclear Engineering and Management
- School of Engineering
- the University of Tokyo
- Bunkyo-ku
- Japan
| | - M. Taguchi
- Quantum Beam Science Center
- Japan Atomic Energy Agency
- Takasaki
- Japan
| | - K. Hata
- Nuclear Safety Research Center
- Japan Atomic Energy Agency
- Tokai-mura, Naka-gun
- Japan
| | - Y. Muroya
- Department of Beam Materials Science
- Institute of Scientific and Industrial Research
- Osaka University
- Ibaraki
- Japan
| | - Y. Katsumura
- Nuclear Professional School
- School of Engineering
- the University of Tokyo
- Tokai-mura, Naka-gun
- Japan
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23
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Ma J, Schmidhammer U, Mostafavi M. Picosecond Pulse Radiolysis of Highly Concentrated Phosphoric Acid Solutions: Mechanism of Phosphate Radical Formation. J Phys Chem B 2014; 119:7180-5. [PMID: 25176139 DOI: 10.1021/jp507332u] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Eight solutions containing phosphoric acid with concentrations ranging from 2 mol L(-1) to neat acid have been studied by picosecond pulse radiolysis. The absorbance of the secondary radical H2PO4(•) formed within 7 ps of the electron pulse is observed using pulse-probe method in the visible. Kinetic analysis shows that the radicals of phosphoric acid are formed via two mechanisms: direct electron detachment and oxidation by the radical cation of water, H2O(•+). On the basis of molar extinction coefficient value of 1850 L mol(-1) cm(-1), at 15 ps the radiolytic yield of H2PO4(•) formation by direct energy absorption is 3.7 ± 0.1 × 10(-7) mol J(-1) in neat phosphoric acid. In highly concentrated phosphoric acid solutions, the total yield of phosphate radical at 15 ps exhibits an additional contribution that can be explained by electron transfer from phosphoric acid to H2O(•+). The efficiency of the electron transfer to this strongly oxidizing species in phosphoric acid solutions is lower compared with the one in sulfuric acid solutions. Two explanations are given to account for a relatively low efficiency of H2O(•+) scavenging in concentrated phosphoric acid solutions.
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Affiliation(s)
- Jun Ma
- Laboratoire de Chimie Physique, CNRS/Université Paris-Sud, Bât. 349, 91405 Orsay, France
| | - Uli Schmidhammer
- Laboratoire de Chimie Physique, CNRS/Université Paris-Sud, Bât. 349, 91405 Orsay, France
| | - Mehran Mostafavi
- Laboratoire de Chimie Physique, CNRS/Université Paris-Sud, Bât. 349, 91405 Orsay, France
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