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Wang H, He T, Hao X, Huang Y, Yao H, Liu F, Cheng H, Qu L. Moisture adsorption-desorption full cycle power generation. Nat Commun 2022; 13:2524. [PMID: 35534468 PMCID: PMC9085775 DOI: 10.1038/s41467-022-30156-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 04/19/2022] [Indexed: 11/25/2022] Open
Abstract
Environment-adaptive power generation can play an important role in next-generation energy conversion. Herein, we propose a moisture adsorption-desorption power generator (MADG) based on porous ionizable assembly, which spontaneously adsorbs moisture at high RH and desorbs moisture at low RH, thus leading to cyclic electric output. A MADG unit can generate a high voltage of ~0.5 V and a current of 100 μA at 100% relative humidity (RH), delivers an electric output (~0.5 V and ~50 μA) at 15 ± 5% RH, and offers a maximum output power density approaching to 120 mW m−2. Such MADG devices could conduct enough power to illuminate a road lamp in outdoor application and directly drive electrochemical process. This work affords a closed-loop pathway for versatile moisture-based energy conversion. Reducing humanity’s reliance on fossil fuels will require the development of alternative, renewable energy technologies. Here, authors prepare a moisture adsorption-desorption power generator that asymmetrically adsorbs and desorbs moisture at high and low humidity to provide an electric output.
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Nap RJ, Qiao B, Palmer LC, Stupp SI, Olvera de la Cruz M, Szleifer I. Acid-Base Equilibrium and Dielectric Environment Regulate Charge in Supramolecular Nanofibers. Front Chem 2022; 10:852164. [PMID: 35372273 PMCID: PMC8965714 DOI: 10.3389/fchem.2022.852164] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/02/2022] [Indexed: 11/13/2022] Open
Abstract
Peptide amphiphiles are a class of molecules that can self-assemble into a variety of supramolecular structures, including high-aspect-ratio nanofibers. It is challenging to model and predict the charges in these supramolecular nanofibers because the ionization state of the peptides are not fixed but liable to change due to the acid-base equilibrium that is coupled to the structural organization of the peptide amphiphile molecules. Here, we have developed a theoretical model to describe and predict the amount of charge found on self-assembled peptide amphiphiles as a function of pH and ion concentration. In particular, we computed the amount of charge of peptide amphiphiles nanofibers with the sequence C16 − V2A2E2. In our theoretical formulation, we consider charge regulation of the carboxylic acid groups, which involves the acid-base chemical equilibrium of the glutamic acid residues and the possibility of ion condensation. The charge regulation is coupled with the local dielectric environment by allowing for a varying dielectric constant that also includes a position-dependent electrostatic solvation energy for the charged species. We find that the charges on the glutamic acid residues of the peptide amphiphile nanofiber are much lower than the same functional group in aqueous solution. There is a strong coupling between the charging via the acid-base equilibrium and the local dielectric environment. Our model predicts a much lower degree of deprotonation for a position-dependent relative dielectric constant compared to a constant dielectric background. Furthermore, the shape and size of the electrostatic potential as well as the counterion distribution are quantitatively and qualitatively different. These results indicate that an accurate model of peptide amphiphile self-assembly must take into account charge regulation of acidic groups through acid–base equilibria and ion condensation, as well as coupling to the local dielectric environment.
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Affiliation(s)
- Rikkert J. Nap
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, United States
- *Correspondence: Rikkert J. Nap, ; Igal Szleifer,
| | - Baofu Qiao
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, United States
| | - Liam C. Palmer
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL, United States
- Department of Chemistry, Northwestern University, Evanston, IL, United States
| | - Samuel I. Stupp
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, United States
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL, United States
- Department of Chemistry, Northwestern University, Evanston, IL, United States
- Department of Medicine, Northwestern University, Chicago, IL, United States
| | - Monica Olvera de la Cruz
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, United States
- Department of Chemistry, Northwestern University, Evanston, IL, United States
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, United States
- Department of Physics and Astronomy, Northwestern University, Evanston, IL, United States
- Center for Computation and Theory of Soft Materials, Northwestern University, Evanston, IL, United States
| | - Igal Szleifer
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, United States
- Department of Chemistry, Northwestern University, Evanston, IL, United States
- *Correspondence: Rikkert J. Nap, ; Igal Szleifer,
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Wallace M, Hicks T, Khimyak YZ, Angulo J. Self-Correcting Method for the Measurement of Free Calcium and Magnesium Concentrations by 1H NMR. Anal Chem 2019; 91:14442-14450. [PMID: 31613090 DOI: 10.1021/acs.analchem.9b03008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A method for the direct measurement of free Ca2+ and Mg2+ concentrations in the range of 1-100 mM by NMR spectroscopy is demonstrated. The method automatically corrects for the effect of ionic strength on the activity of the species in solution and works satisfactorily even when significant concentrations of competitive ions are present. The method requires only the measurement of the 1H chemical shifts of our reporter ligands, glycolate and sulfoacetate, and is easily implemented using NMR imaging techniques. As a proof of concept, we extract the thermodynamic binding constants and conformer distributions of analyte ligands using an in situ ion gradient. Existing approaches for the measurement of free Ca2+ or Mg2+ concentrations by NMR operate only at very low ion concentrations or else require careful recalibration for different sample conditions. By providing the free Ca2+ or Mg2+ concentrations, the proposed methodology significantly enhances the information obtainable via NMR investigations of ion-responsive systems.
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Affiliation(s)
- Matthew Wallace
- School of Pharmacy , University of East Anglia , Norwich Research Park , Norwich NR4 7TJ , U.K
| | - Thomas Hicks
- School of Pharmacy , University of East Anglia , Norwich Research Park , Norwich NR4 7TJ , U.K
| | - Yaroslav Z Khimyak
- School of Pharmacy , University of East Anglia , Norwich Research Park , Norwich NR4 7TJ , U.K
| | - Jesús Angulo
- School of Pharmacy , University of East Anglia , Norwich Research Park , Norwich NR4 7TJ , U.K
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Karki I, Christen MT, Spiriti J, Slack RL, Oda M, Kanaori K, Zuckerman DM, Ishima R. Entire-Dataset Analysis of NMR Fast-Exchange Titration Spectra: A Mg 2+ Titration Analysis for HIV-1 Ribonuclease H Domain. J Phys Chem B 2016; 120:12420-12431. [PMID: 27973819 DOI: 10.1021/acs.jpcb.6b08323] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This article communicates our study to elucidate the molecular determinants of weak Mg2+ interaction with the ribonuclease H (RNH) domain of HIV-1 reverse transcriptase in solution. As the interaction is weak (a ligand-dissociation constant >1 mM), nonspecific Mg2+ interaction with the protein or interaction of the protein with other solutes that are present in the buffer solution can confound the observed Mg2+-titration data. To investigate these indirect effects, we monitored changes in the chemical shifts of backbone amides of RNH by recording NMR 1H-15N heteronuclear single-quantum coherence spectra upon titration of Mg2+ into an RNH solution. We performed the titration under three different conditions: (1) in the absence of NaCl, (2) in the presence of 50 mM NaCl, and (3) at a constant 160 mM Cl- concentration. Careful analysis of these three sets of titration data, along with molecular dynamics simulation data of RNH with Na+ and Cl- ions, demonstrates two characteristic phenomena distinct from the specific Mg2+ interaction with the active site: (1) weak interaction of Mg2+, as a salt, with the substrate-handle region of the protein and (2) overall apparent lower Mg2+ affinity in the absence of NaCl compared to that in the presence of 50 mM NaCl. A possible explanation may be that the titrated MgCl2 is consumed as a salt and interacts with RNH in the absence of NaCl. In addition, our data suggest that Na+ increases the kinetic rate of the specific Mg2+ interaction at the active site of RNH. Taken together, our study provides biophysical insight into the mechanism of weak metal interaction on a protein.
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Affiliation(s)
- Ichhuk Karki
- Department of Structural Biology and ‡Department of Computational and Systems Biology, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.,Graduate School of Life and Environmental Sciences, Kyoto Prefectural University and ⊥Department of Biomolecular Engineering, Kyoto Institute of Technology , Kyoto 606, Japan
| | - Martin T Christen
- Department of Structural Biology and ‡Department of Computational and Systems Biology, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.,Graduate School of Life and Environmental Sciences, Kyoto Prefectural University and ⊥Department of Biomolecular Engineering, Kyoto Institute of Technology , Kyoto 606, Japan
| | - Justin Spiriti
- Department of Structural Biology and ‡Department of Computational and Systems Biology, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.,Graduate School of Life and Environmental Sciences, Kyoto Prefectural University and ⊥Department of Biomolecular Engineering, Kyoto Institute of Technology , Kyoto 606, Japan
| | - Ryan L Slack
- Department of Structural Biology and ‡Department of Computational and Systems Biology, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.,Graduate School of Life and Environmental Sciences, Kyoto Prefectural University and ⊥Department of Biomolecular Engineering, Kyoto Institute of Technology , Kyoto 606, Japan
| | - Masayuki Oda
- Department of Structural Biology and ‡Department of Computational and Systems Biology, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.,Graduate School of Life and Environmental Sciences, Kyoto Prefectural University and ⊥Department of Biomolecular Engineering, Kyoto Institute of Technology , Kyoto 606, Japan
| | - Kenji Kanaori
- Department of Structural Biology and ‡Department of Computational and Systems Biology, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.,Graduate School of Life and Environmental Sciences, Kyoto Prefectural University and ⊥Department of Biomolecular Engineering, Kyoto Institute of Technology , Kyoto 606, Japan
| | - Daniel M Zuckerman
- Department of Structural Biology and ‡Department of Computational and Systems Biology, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.,Graduate School of Life and Environmental Sciences, Kyoto Prefectural University and ⊥Department of Biomolecular Engineering, Kyoto Institute of Technology , Kyoto 606, Japan
| | - Rieko Ishima
- Department of Structural Biology and ‡Department of Computational and Systems Biology, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.,Graduate School of Life and Environmental Sciences, Kyoto Prefectural University and ⊥Department of Biomolecular Engineering, Kyoto Institute of Technology , Kyoto 606, Japan
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