329 results on '"Huib J. Bakker"'
Search Results
2. Slow Proton Transfer in Nanoconfined Water
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Oleksandr O. Sofronov and Huib J. Bakker
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Chemistry ,QD1-999 - Published
- 2020
- Full Text
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3. Thermodynamic Stabilization of Mixed-Halide Perovskites against Phase Segregation
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Eline M. Hutter, Loreta A. Muscarella, Francesca Wittmann, Jan Versluis, Lucie McGovern, Huib J. Bakker, Young-Won Woo, Young-Kwang Jung, Aron Walsh, and Bruno Ehrler
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mixed-halide perovskites ,segregation ,pressure ,thermodynamics ,Physics ,QC1-999 - Abstract
Summary: Mixing iodide and bromide in halide perovskite semiconductors is an effective strategy to tune their band gap; therefore, mixed-halide perovskites hold great promise for color-tunable LEDs and tandem solar cells. However, the band gap of mixed-halide perovskites is unstable under (sun-)light, since the halides segregate into domains of different band gaps. Using pressure-dependent ultrafast transient absorption spectroscopy, we find that high external pressure increases the range of stable halide mixing ratios. Chemical compression, by inserting a smaller cation, has the same effect, which means that any iodide:bromide ratio can be stabilized by tuning the crystal volume and compressibility. We interpret these findings as an increased thermodynamic stabilization through alteration of the Gibbs free energy via the largely overlooked PΔV term.
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- 2020
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4. The interfacial structure of water droplets in a hydrophobic liquid
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Nikolay Smolentsev, Wilbert J. Smit, Huib J. Bakker, and Sylvie Roke
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Science - Abstract
Nanoscopic water droplets in a hydrophobic liquid are abundant in the earth, our bodies and the sky. Here, it is shown that the surface of such a droplet has stronger hydrogen bonds than a planar interface of water and a hydrophobic liquid, equivalent to a 50 K reduction of the surface temperature.
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- 2017
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5. Effect of Antifreeze Glycoproteins on Organoid Survival during and after Hypothermic Storage
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Guizela Huelsz-Prince, Arthur L. DeVries, Huib J. Bakker, Jeroen S. van Zon, and Konrad Meister
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antifreeze glycoproteins ,organoids ,hypothermic storage ,fluorescence microscopy ,Microbiology ,QR1-502 - Abstract
We study the effect of antifreeze glycoproteins (AFGPs) on the survival of organoids under hypothermic conditions. We find that the survival of organoids in cold conditions depends on their developmental stage. Mature organoids die within 24 h when being stored at 4 °C, while cystic organoids can survive up to 48 h. We find that in the presence of AFGPs, the organoid survival is prolonged up to 72 h, irrespective of their developmental stage. Fluorescence microscopy experiments reveal that the AFGPs predominately localize at the cell surface and cover the cell membranes. Our findings support a mechanism in which the positive effect of AFGPs on cell survival during hypothermic storage involves the direct interaction of AFGPs with the cell membrane. Our research highlights organoids as an attractive multicellular model system for studying the action of AFGPs that bridges the gap between single-cell and whole-organ studies.
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- 2019
- Full Text
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6. Observing Aqueous Proton-Uptake Reactions Triggered by Light
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Balázs Antalicz, Jan Versluis, and Huib J. Bakker
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Published
- 2023
7. Molecular Orientation of Carboxylate Anions at the Water–Air Interface Studied with Heterodyne-Detected Vibrational Sum-Frequency Generation
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Alexander A. Korotkevich, Carolyn J. Moll, Jan Versluis, and Huib J. Bakker
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Materials Chemistry ,Physical and Theoretical Chemistry ,Surfaces, Coatings and Films - Published
- 2023
8. Water-Induced Restructuring of the Surface of a Deep Eutectic Solvent
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Rahul Gera, Carolyn J. Moll, Aditi Bhattacherjee, and Huib J. Bakker
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Letter ,General Materials Science ,Physical and Theoretical Chemistry - Abstract
We study the molecular-scale structure of the surface of Reline, a DES made from urea and choline chloride, using heterodyne-detected vibrational sum frequency generation (HD-VSFG). Reline absorbs water when exposed to the ambient atmosphere, and following structure-specific changes at the Reline/air interface is crucial and difficult. For Reline (dry, 0 wt %, w/w, water) we observe vibrational signatures of both urea and choline ions at the surface. Upon increase of the water content, there is a gradual depletion of urea from the surface, an enhanced alignment, and an enrichment of the surface with choline cations, indicating surface speciation of ChCl. Above 40% w/w water content, choline cations abruptly deplete from the surface, as evidenced by the decrease of the vibrational signal of the −CH2– groups of choline and the rapid rise of a water signal. Above 60% w/w water content, the surface spectrum of aqueous Reline becomes indistinguishable from that of neat water.
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- 2022
9. Accelerated Vibrational Energy Relaxation of Water in Alkaline Environments
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Sander Woutersen, Huib J. Bakker, Roberto Cota, Time-resolved vibrational spectroscopy, and Molecular Spectroscopy (HIMS, FNWI)
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Physics::Biological Physics ,Quantitative Biology::Biomolecules ,Materials science ,Aqueous solution ,Water ,Dissipation ,Molecular physics ,Vibration ,Article ,Surfaces, Coatings and Films ,Ion ,chemistry.chemical_compound ,chemistry ,Energy Transfer ,Excited state ,Materials Chemistry ,Vibrational energy relaxation ,Physics::Atomic and Molecular Clusters ,Relaxation (physics) ,Hydroxide ,Molecule ,Physical and Theoretical Chemistry ,Physics::Chemical Physics - Abstract
We observe that hydrated hydroxide ions introduce an additional relaxation channel for the vibrational relaxation of the OD vibrations of HDO molecules in aqueous NaOH solutions. This additional relaxation path involves resonant (Förster) vibrational energy transfer from the excited OD vibration to OH stretch vibrations of hydrated OH- complexes. This energy transfer constitutes an efficient mechanism for dissipation of the OD vibrational energy, as the accepting OH stretch vibrations show an extremely rapid subsequent relaxation with a time constant of
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- 2021
10. Direct Probing of Vibrational Interactions in UiO-66 Polycrystalline Membranes with Femtosecond Two-Dimensional Infrared Spectroscopy
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Alexander A. Korotkevich, Oleksandr O. Sofronov, Olivier Lugier, Sanghamitra Sengupta, Stefania Tanase, Huib J. Bakker, Spectroscopy and Photonic Materials (HIMS, FNWI), HCSC+ (HIMS, FNWI), and Molecular Spectroscopy (HIMS, FNWI)
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General Materials Science ,Physical and Theoretical Chemistry - Abstract
UiO-66 is a benchmark metal-organic framework that holds great promise for the design of new functional materials. In this work, we perform two-dimensional infrared measurements on polycrystalline membranes of UiO-66 grown on c-sapphire substrates. We study the symmetric and antisymmetric stretch vibrations of the carboxylate groups of the terephthalate linker ions and find that these vibrations show a rapid energy exchange and a collective vibrational relaxation with a time constant of 1.3 ps. We also find that the symmetric vibration of the carboxylate group is strongly coupled to a vibration of the aromatic ring of the terephthalate ion. We observe that the antisymmetric carboxylate vibrations of different terephthalate linkers show rapid resonant (Förster) energy transfer with a time constant of ∼1 ps.
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- 2022
11. Molecular Structure and Surface Accumulation Dynamics of Hyaluronan at the Water–Air Interface
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Giulia Giubertoni, Jan Versluis, Gijsje H. Koenderink, Carolyn J. Moll, Huib J. Bakker, Lennard van Buren, IoP (FNWI), and Molecular Spectroscopy (HIMS, FNWI)
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Polymers and Plastics ,Kinetics ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Article ,Inorganic Chemistry ,Materials Chemistry ,Molecule ,chemistry.chemical_classification ,Aqueous solution ,integumentary system ,Hydrogen bond ,Chemistry ,Organic Chemistry ,Dynamics (mechanics) ,Polymer ,021001 nanoscience & nanotechnology ,Electrostatics ,0104 chemical sciences ,carbohydrates (lipids) ,engineering ,Biophysics ,Biopolymer ,0210 nano-technology - Abstract
Hyaluronan is a biopolymer that is essential for many biological processes in the human body, like the regulation of tissue lubrication and inflammatory responses. Here, we study the behavior of hyaluronan at aqueous surfaces using heterodyne-detected vibrational sum-frequency generation spectroscopy (HD-VSFG). Low-molecular-weight hyaluronan (similar to 150 I(Da) gradually covers the water-air interface within hours, leading to a negatively charged surface and a reorientation of interfacial water molecules. The rate of surface accumulation strongly increases when the bulk concentration of low-molecular-weight hyaluronan is increased. In contrast, high-molecular-weight hyaluronan (>1 MDa) cannot be detected at the surface, even hours after the addition of the polymer to the aqueous solution. The strong dependence on the polymer molecular weight can be explained by entanglements of the hyaluronan polymers. We also find that for low-molecular-weight hyaluronan the migration kinetics of hyaluronan in aqueous media shows an anomalous dependence on the pH of the solution, which can be explained from the interplay of hydrogen bonding and electrostatic interactions of hyaluronan polymers.
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- 2021
12. Observation of strong synergy in the interfacial water response of binary ionic and non-ionic surfactant mixtures
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Sanghamitra Sengupta, Rahul Gera, Colin Egan, Uriel N. Morzan, Jan Versluis, Ali Hassanali, and Huib J. Bakker
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General Materials Science ,Physical and Theoretical Chemistry - Abstract
We have used heterodyne detected vibrational sum-frequency generation spectroscopy (HDVSFG) to probe the interfacial structure of binary mixtures of sodium dodecyl sulfate (SDS) and hexaethylene glycol monododecyl ether (C12E6) surfactants. Our results show that in the presence of C12E6 at CMC (70 µM) the effect of SDS on the orientation of interfacial water molecules is strongly enhanced. Molecular dynamics simulations show that the adsorption free energy of DS− ions to a water surface covered with C12E6 is significantly more attractive by ~ 10 kBT compared to the adsorption energy of DS− to the surface of pure water. The simulations also show that the adsorption of DS− to a water surface covered with C12E6 induces a strong restructuring and enhanced orientation of the near-surface water layers, explaining the HDVSFG results.
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- 2022
13. Disaccharide Residues are Required for Native Antifreeze Glycoprotein Activity
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Huib J. Bakker, Manfred Wagner, Giulia Giubertoni, Konrad Meister, Arthur L. DeVries, Yuling Sun, Jie Liu, and David Y. W. Ng
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Circular dichroism ,Magnetic Resonance Spectroscopy ,Recrystallization (geology) ,Polymers and Plastics ,Stereochemistry ,Disaccharide ,Bioengineering ,02 engineering and technology ,Disaccharides ,010402 general chemistry ,01 natural sciences ,Article ,Biomaterials ,Hydrophobic effect ,chemistry.chemical_compound ,Antifreeze Proteins ,Materials Chemistry ,Threonine ,Glycoproteins ,Alanine ,chemistry.chemical_classification ,Ice ,Hydrogen Bonding ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Antifreeze ,0210 nano-technology ,Glycoprotein - Abstract
Antifreeze glycoproteins (AFGPs) are able to bind to ice, halt its growth, and are the most potent inhibitors of ice recrystallization known. The structural basis for AFGP’s unique properties remains largely elusive. Here we determined the antifreeze activities of AFGP variants that we constructed by chemically modifying the hydroxyl groups of the disaccharide of natural AFGPs. Using nuclear magnetic resonance, two-dimensional infrared spectroscopy, and circular dichroism, the expected modifications were confirmed as well as their effect on AFGPs solution structure. We find that the presence of all the hydroxyls on the disaccharides is a requirement for the native AFGP hysteresis as well as the maximal inhibition of ice recrystallization. The saccharide hydroxyls are apparently as important as the acetyl group on the galactosamine, the α-linkage between the disaccharide and threonine, and the methyl groups on the threonine and alanine. We conclude that the use of hydrogen-bonding through the hydroxyl groups of the disaccharide and hydrophobic interactions through the polypeptide backbone are equally important in promoting the antifreeze activities observed in the native AFGPs. These important criteria should be considered when designing synthetic mimics.
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- 2021
14. The molecular structure of the surface of water–ethanol mixtures
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Arnaldo Naves de Brito, Anderson Herbert de Abreu Gomes, Huib J. Bakker, Johannes Kirschner, R. R. T. Marinho, Hans Ågren, Vincenzo Carravetta, Niklas Ottosson, and Olle Björneholm
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chemistry.chemical_compound ,Ethanol ,chemistry ,X-ray photoelectron spectroscopy ,Chemical engineering ,Amphiphile ,General Physics and Astronomy ,Molecule ,Alcohol ,Physical and Theoretical Chemistry ,Surface concentration ,Spectroscopy ,Mole fraction - Abstract
Mixtures of water and alcohol exhibit an excess surface concentration of alcohol as a result of the amphiphilic nature of the alcohol molecule, which has important consequences for the physico-chemical properties of water-alcohol mixtures. Here we use a combination of intensity vibrational sum-frequency generation (VSFG) spectroscopy, heterodyne-detected VSFG (HD-VSFG), and core-level photoelectron spectroscopy (PES) to investigate the molecular properties of water-ethanol mixtures at the air-liquid interface. We find that increasing the ethanol concentration up to a molar fraction (MF) of 0.1 leads to a steep increase of the surface density of the ethanol molecules, and an increased ordering of the ethanol molecules at the surface. When the ethanol concentration is further increased, the surface density of ethanol remains more or less constant, while the orientation of the ethanol molecules becomes increasingly disordered. The used techniques of PES and VSFG provide complementary information on the density and orientation of ethanol molecules at the surface of water, thus providing new information on the molecular-scale properties of the surface of water-alcohol mixtures over a wide range of compositions. This information is invaluable in understanding the chemical and physical properties of water-alcohol mixtures.
- Published
- 2021
15. Connecting the Stimuli-Responsive Rheology of Biopolymer Hydrogels to Underlying Hydrogen-Bonding Interactions
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Federica Burla, Gijsje H. Koenderink, Giulia Giubertoni, and Huib J. Bakker
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chemistry.chemical_classification ,Polymers and Plastics ,Hydrogen bond ,Organic Chemistry ,02 engineering and technology ,Polymer ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Viscoelasticity ,Article ,0104 chemical sciences ,Inorganic Chemistry ,Reptation ,chemistry ,Rheology ,Chemical engineering ,Self-healing hydrogels ,Materials Chemistry ,Stress relaxation ,engineering ,Biopolymer ,0210 nano-technology - Abstract
Many biopolymer hydrogels are environmentally responsive because they are held together by physical associations that depend on pH and temperature. Here we investigate how the pH and temperature response of the rheology of hyaluronan hydrogels is connected to the underlying molecular interactions. Hyaluronan is an essential structural biopolymer in the human body with many applications in biomedicine. Using two-dimensional infrared (2DIR) spectroscopy, we show that hyaluronan chains become connected by hydrogen bonds when the pH is changed from 7.0 to 2.5, and that the bond density at pH 2.5 is independent of temperature. Temperature-dependent rheology measurements show that due to this hydrogen bonding the stress relaxation at pH 2.5 is strongly slowed down in comparison to pH 7.0, consistent with the sticky reptation model of associative polymers. From the flow activation energy we conclude that each polymer is crosslinked by multiple (5-15) hydrogen bonds to others, causing slow macroscopic stress relaxation, despite the short time scale of breaking and reformation of each individual hydrogen bond. Our findings can aid the design of stimuli-responsive hydrogels with tailored viscoelastic properties for biomedical applications.
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- 2020
16. Slowing Down of the Molecular Reorientation of Water in Concentrated Alkaline Solutions
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Sander Woutersen, Roberto Cota, Huib J. Bakker, Eliane P. van Dam, Molecular Spectroscopy (HIMS, FNWI), and Time-resolved vibrational spectroscopy
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Solid-state chemistry ,010304 chemical physics ,Hydrogen bond ,Diffusion ,010402 general chemistry ,01 natural sciences ,Fick's laws of diffusion ,Article ,0104 chemical sciences ,Surfaces, Coatings and Films ,Ion ,chemistry.chemical_compound ,chemistry ,Deuterium ,0103 physical sciences ,Materials Chemistry ,Hydroxide ,Physical chemistry ,Molecule ,Physical and Theoretical Chemistry - Abstract
It is generally accepted that the hydroxide ion (OH–) is a strong hydrogen bond acceptor and that its anomalously high diffusion constant in water results from a Grotthuss-like structural diffusion mechanism. However, the spatial extent over which OH– ions influence the dynamics of the hydrogen-bond network of water remained largely unclear. Here, we measure the ultrafast dynamics of OH groups of HDO molecules interacting with the deuterated hydroxide ion OD–. For solutions with OD– concentrations up to 4 M, we find that HDO molecules that are not directly interacting with the ions have a reorientation time constant of ∼2.7 ps, similar to that of pure liquid water. When the concentration of OD– ions is increased, the reorientation time constant increases, indicating a strong slowing down of the structural dynamics of the solution.
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- 2020
17. Peptide Side-COOH Groups Have Two Distinct Conformations under Biorelevant Conditions
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Alberto Pérez de Alba Ortíz, Oleksandr O. Sofronov, Huib J. Bakker, Giulia Giubertoni, Bernd Ensing, Molecular Simulations (HIMS, FNWI), and Molecular Spectroscopy (HIMS, FNWI)
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Models, Molecular ,Letter ,Spectrophotometry, Infrared ,Stereochemistry ,Molecular Conformation ,Peptide ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Isomerism ,Amide ,Proton transport ,0103 physical sciences ,Aspartic acid ,Side chain ,General Materials Science ,Physical and Theoretical Chemistry ,Conformational isomerism ,chemistry.chemical_classification ,Aqueous solution ,010304 chemical physics ,Amides ,0104 chemical sciences ,Amino acid ,chemistry ,Peptides - Abstract
The carboxyl (COOH) side chain groups of amino acids, such as aspartic acid, play an important role in biochemical processes, including enzymatic proton transport. In many theoretical studies, it was found that the (bio)chemical reactivity of the carboxyl group strongly depends on the conformation of this group. Interestingly, up to now there has been no experimental investigation of the geometry and the stability of different COOH conformers under biorelevant conditions. Here, we investigate the conformational isomerism of the side chain COOH group of N-acetyl aspartic acid amide using polarization-resolved two-dimensional infrared spectroscopy. We find that the carboxyl group shows two distinct near-planar conformers (syn and anti) when dissolved in water at room temperature. Both conformers are significantly populated in aqueous solution (75 +/- 10% and 25 +/- 10% for syn and anti, respectively). Molecular dynamics simulations show that the anti conformer interacts more strongly with water molecules than the syn conformer, explaining why this conformer is significantly present in aqueous solution.
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- 2020
18. Studying Chemisorption at Metal–Polymer Interfaces by Complementary Use of Attenuated Total Reflection–Fourier Transform Infrared Spectroscopy (ATR-FTIR) in the Kretschmann Geometry and Visible–Infrared Sum-Frequency Generation Spectroscopy (SFG)
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Huib J. Bakker, Jan Versluis, L.I. Fockaert, Johannes M. C. Mol, Deborah Ganzinga-Jurg, B. Boelen, Herman Terryn, Materials and Surface Science & Engineering, Electrochemical and Surface Engineering, and Materials and Chemistry
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Nonlinear optics ,Materials science ,Infrared ,Interfaces ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Zinc ,010402 general chemistry ,01 natural sciences ,stomatognathic system ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Organic polymers ,Oxides ,Molecular configuration ,021001 nanoscience & nanotechnology ,Infrared light ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,General Energy ,chemistry ,Chemisorption ,Attenuated total reflection ,0210 nano-technology ,Sum frequency generation spectroscopy - Abstract
The molecular configuration and chemistry at the zinc/zinc oxide-polyester interface were studied by using two complementary spectroscopic techniques: attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and sum-frequency generation (SFG) spectroscopy. It was shown that ATR-FTIR should be considered as a (3D) interphase-sensitive technique with probing depths of 250-400 nm in the headgroup region (2000-1200 cm-1). On the other hand, SFG is known to be a (2D) interface-sensitive technique. The ATR-FTIR measurements showed that carboxylate groups are formed within the near-interface region of the polyester phase. SFG measurements showed that the carboxylic acid groups are stable at the polymer-zinc/zinc oxide interface. In addition, in situ ATR-FTIR and SFG measurements have been conducted when exposing the polyester-zinc/zinc oxide system to D2O. The exposure to D2O is observed to lead to an additional conversion of ester and carboxylic acid groups to carboxylate groups. The comparison of the SFG and ATR-FTIR measurements shows that this conversion occurs much slower at the polyester-zinc/zinc oxide interface than in the bulk of the polyester. Finally, the strengths and limitations as well as the complementarity of both techniques are discussed.
- Published
- 2020
19. Hydration interactions beyond the first solvation shell in aqueous phenolate solution
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Huib J. Bakker, Ambuj Tiwari, Sander Woutersen, Roberto Cota, Bernd Ensing, Molecular Spectroscopy (HIMS, FNWI), Simulation of Biomolecular Systems (HIMS, FNWI), Molecular Simulations (HIMS, FNWI), and Time-resolved vibrational spectroscopy
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Aqueous solution ,Chemistry ,Solvation ,General Physics and Astronomy ,Charge density ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Ion ,Molecular dynamics ,Solvation shell ,Chemical physics ,Molecule ,Density functional theory ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
We investigate the orientational dynamics of water molecules solvating phenolate ions using ultrafast vibrational spectroscopy and density functional theory-based molecular dynamics simulations. To assess the roles of the hydrophobic and hydrophilic parts of the anion, we also perform experiments and simulations on solutions of phenol. The experiments show that phenolate immobilizes (τor > 10 ps) 6.2 ± 0.5 water molecules beyond the first solvation shell of its oxygen atom, whereas phenol immobilizes only ∼2 water molecules, including the water molecules in its first solvation shell. The simulations reproduce the experiments very well, and show that phenolate causes a local ordering of the hydrogen-bond structure that extends beyond the first solvation shell, thus explaining the experimental observations. The comparison with phenol solution shows that the solvation interaction of phenolate beyond its first solvation shell is due to the high charge density of its negatively charged oxygen atom.
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- 2020
20. Nature of hydrated proton vibrations revealed by nonlinear spectroscopy of acid water nanodroplets
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Huib J. Bakker and Oleksandr O. Sofronov
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Chemistry ,Hydrogen bond ,Cationic polymerization ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Micelle ,0104 chemical sciences ,3. Good health ,chemistry.chemical_compound ,Sulfonate ,Molecule ,Physical and Theoretical Chemistry ,Absorption (chemistry) ,0210 nano-technology ,Spectroscopy ,Hexanol - Abstract
We use polarization-resolved femtosecond pump–probe spectroscopy to investigate the vibrations of hydrated protons in anionic (AOT) and cationic (CTAB/hexanol) reverse micelles in the frequency range 2000–3500 cm−1. For small AOT micelles the dominant proton hydration structure consists of H3O+ with two OH groups donating hydrogen bonds to water molecules, and one OH group donating a weaker hydrogen bond to sulfonate. For cationic reverse micelles, we find that the absorption at frequencies >2500 cm−1 is dominated by asymmetric proton-hydration structures in which one of the OH groups of H3O+ is more weakly hydrogen-bonded to water than the other two OH groups.
- Published
- 2020
21. Hyaluronan biopolymers release water upon pH-induced gelation
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Giulia Giubertoni, Eliane P. van Dam, Federica Burla, Huib J. Bakker, and Gijsje H. Koenderink
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chemistry.chemical_classification ,Aqueous solution ,Spectrophotometry, Infrared ,medicine.diagnostic_test ,Water ,General Physics and Astronomy ,Polymer ,Hydrogen-Ion Concentration ,Viscoelasticity ,Condensed Matter::Soft Condensed Matter ,Viscosity ,Biopolymers ,Chemical engineering ,chemistry ,Rheology ,Spectrophotometry ,medicine ,Molecule ,Hyaluronic Acid ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Spectroscopy ,Gels - Abstract
We study the relation between the macroscopic viscoelastic properties of aqueous hyaluronan polymer solutions and the molecular-scale dynamics of water using rheology measurements, differential dynamic microscopy, and polarization-resolved infrared pump-probe spectroscopy. We observe that the addition of hyaluronan to water leads to a slowing down of the reorientation of a fraction of the water molecules. Near pH 2.4, the viscosity of the hyaluronan solution reaches a maximum, while the number of slowed down water molecules reaches a minimum. This implies that the water molecules become on average more mobile when the solution becomes more viscous. This observation indicates that the increase in viscosity involves the expulsion of hydration water from the surfaces of the hyaluronan polymers, and a bundling of the hyaluronan polymer chains.
- Published
- 2020
22. The molecular structure and surface accumulation dynamics of hyaluronan at the water/air interface
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Huib J. Bakker, Gijsje H. Koenderink, Giulia Giubertoni, Jan Versluis, and Carolyn J. Moll
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chemistry.chemical_classification ,Aqueous solution ,chemistry ,Aqueous medium ,Dynamics (mechanics) ,Kinetics ,engineering ,Biophysics ,Molecule ,Polymer ,Biopolymer ,engineering.material ,Electrostatics - Abstract
Hyaluronan is a biopolymer that is essential for many biological processes in the human body, like the regulation of tissue lubrication and inflammatory responses. Here we study the behavior of hyaluronan at aqueous surfaces using heterodyne-detected vibrational sum-frequency generation spectroscopy (HD-VSFG). We find that high-molecular weight hyaluronan (>1 MDa) does not come to the surface, even hours after addition of the polymer to the aqueous solution. In contrast, low-molecular weight hyaluronan (~150 kDa) gradually covers the water-air interface within hours, leading to a negatively charged surface and a reorientation of the interfacial water molecules. This strong dependence on the polymer molecular weight can be explainend from entanglements of the hyaluronan polymers. We also find that the migration kinetics of hyaluronan in aqueous media shows an anomalous dependence on the pH of the solution, which can be explained from the interplay of hydrogen-bonding and electrostatic interactions of the hyaluronan polymers.
- Published
- 2021
23. Direct Observation of Intrachain Hydrogen Bonds in Aqueous Hyaluronan
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Giulia Giubertoni, Huib J. Bakker, and Gijsje H. Koenderink
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chemistry.chemical_classification ,Persistence length ,Aqueous solution ,010304 chemical physics ,Hydrogen bond ,Infrared spectroscopy ,Polymer ,010402 general chemistry ,01 natural sciences ,Article ,0104 chemical sciences ,Ion ,chemistry.chemical_compound ,chemistry ,Amide ,0103 physical sciences ,Polymer chemistry ,Carboxylate ,Physical and Theoretical Chemistry - Abstract
We use two-dimensional infrared spectroscopy to study the interactions between the amide and carboxylate anion groups of hyaluronan polymers at neutral pH. The spectra reveal the presence of intrachain hydrogen bonds between the amide and carboxylate anion groups in aqueous solution. We determine the relative orientation of the amide and carboxylate anion groups when forming this hydrogen bond and quantify the fraction of amide groups that participate in hydrogen bonding. We find that a variation of the pH and/or temperature has a negligible effect on this fraction, whereas the persistence length of the hyaluronan chains and the associated viscosity of hyaluronan solutions are known to change significantly. We conclude that the hydrogen bonding between the amide and carboxylate anion groups does not significantly contribute to the chain rigidity of hyaluronan polymers.
- Published
- 2019
24. Vibrational Relaxation Dynamics of the Core and Outer Part of Proton-Hydration Clusters
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Oleksandr O. Sofronov and Huib J. Bakker
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Materials science ,010304 chemical physics ,Proton ,010402 general chemistry ,01 natural sciences ,Molecular physics ,Article ,3. Good health ,0104 chemical sciences ,Surfaces, Coatings and Films ,0103 physical sciences ,Femtosecond ,Ultrafast laser spectroscopy ,Materials Chemistry ,Vibrational energy relaxation ,Cluster (physics) ,Relaxation (physics) ,Physical and Theoretical Chemistry ,Physics::Chemical Physics ,Spectroscopy ,Excitation - Abstract
We study the ultrafast relaxation dynamics of hydrated proton clusters in acetonitrile using femtosecond mid-infrared pump-probe spectroscopy. We observe a strong dependence of transient absorption dynamics on the frequency of excitation. When we excite the OH vibrations with frequencies ≤3100 cm-1, we observe an ultrafast energy relaxation that leads to the heating of the local environment of the proton. This response is assigned to the OH vibrations of the water molecules in the core of the hydrated proton cluster. When we excite with frequencies ≥3200 cm-1, we observe a relatively slow vibrational relaxation with a T1 time constant ranging from 0.22 ± 0.04 ps at νex = 3200 cm-1 to 0.37 ± 0.02 ps at νex = 3520 cm-1. We assign this response to water molecules in the outer part of the hydrated proton cluster.
- Published
- 2019
25. Observation of Distinct Carboxylic Acid Conformers in Aqueous Solution
- Author
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Giulia Giubertoni, Oleksandr O. Sofronov, and Huib J. Bakker
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chemistry.chemical_classification ,Aqueous solution ,Formic acid ,Carboxylic acid ,Infrared spectroscopy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Molecular geometry ,chemistry ,Group (periodic table) ,Polymer chemistry ,General Materials Science ,Physical and Theoretical Chemistry ,0210 nano-technology ,Acetonitrile ,Conformational isomerism - Abstract
[Image: see text] We investigate the molecular geometry of the carboxyl group of formic acid in acetonitrile and aqueous solutions at room temperature with two-dimensional infrared spectroscopy (2D-IR). We found that the carboxyl group adopts two distinct configurations: a configuration in which the carbonyl group is oriented antiparallel to the hydroxyl (anti-conformer), and a configuration in which the carbonyl group is oriented at an angle of ∼60° with respect to the hydroxyl (syn-conformer). These results constitute the first experimental evidence that carboxyl groups exist as two distinct and long-living conformational isomers in aqueous solution at room temperature.
- Published
- 2019
26. Surface Structure of Solutions of Poly(vinyl alcohol) in Water
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Carolyn J. Moll, Huib J. Bakker, Konrad Meister, and J. Kirschner
- Subjects
chemistry.chemical_classification ,Vinyl alcohol ,Materials science ,Aqueous solution ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Ion ,Surfaces, Coatings and Films ,Surface tension ,chemistry.chemical_compound ,Hydrolysis ,chemistry ,Chemical engineering ,Materials Chemistry ,Molecule ,Surface layer ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
We use surface-specific heterodyne-detected vibrational sum-frequency generation spectroscopy (HD-VSFG) and surface tension measurements to investigate the molecular structure of the surface of aqueous solutions of poly(vinyl alcohol) (PVA) polymers with average molecular weights of 10000 and 125000 g/mol. We find that the interfacial water molecules have a preferred orientation with their hydrogen-bonded O-H groups pointing away from the bulk, for both PVA10000 and PVA125000. This observation is explained from the ongoing hydrolysis of the acetyl impurities on the PVA polymer chains. This hydrolysis yields negatively charged acetate ions that have a relatively high surface propensity. For both PVA10000 and PVA125000 the strong positive signal vanishes when the pH is decreased, due to the neutralization of the acetate ions. For solutions with a high concentration of PVA10000 the interfacial water signal becomes very small, indicating that the surface gets completely covered with a disordered PVA polymer film. In contrast, for high concentrations of PVA125000, the strong positive water signal persists at high pH, which shows that the water surface does not get completely covered. The HD-VSFG data combined with surface tension data indicate that concentrated PVA125000 solutions form a structured surface layer with pores containing a high density of interfacial water.
- Published
- 2018
- Full Text
- View/download PDF
27. Emergence of Electric Fields at the Water–C12E6 Surfactant Interface
- Author
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Rahul Gera, Huib J. Bakker, Ricardo Franklin-Mergarejo, Uriel N. Morzan, Gabriele Falciani, Luca Bergamasco, Jan Versluis, Indraneel Sen, Silvia Dante, Eliodoro Chiavazzo, and Ali A. Hassanali
- Published
- 2021
- Full Text
- View/download PDF
28. Structure and Dynamics of a Temperature-Sensitive Hydrogel
- Author
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Eliane P. van Dam, Hongbo Yuan, Huib J. Bakker, and Paul H. J. Kouwer
- Subjects
chemistry.chemical_classification ,Aqueous solution ,Molecular Structure ,Hydrogen bond ,Chemistry ,Systems Chemistry ,Temperature ,Infrared spectroscopy ,Water ,Hydrogels ,Hydrogen Bonding ,Polymer ,Article ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Chemical engineering ,Amide ,Self-healing hydrogels ,Spectroscopy, Fourier Transform Infrared ,Materials Chemistry ,Side chain ,Molecule ,Physical and Theoretical Chemistry - Abstract
Polyisocyanotripeptides (TriPIC) are biomimetic polymers which consist of a β-helical backbone stabilized by hydrogen bonds between amide groups. Their oligoethylene glycol side chains give aqueous TriPIC solutions a thermoresponsive behavior: at 50 °C the solution becomes a hydrogel. In this paper we study the molecular structure and water dynamics of TriPIC aqueous solutions while undergoing gelation using FT-IR spectroscopy and polarization-resolved femtosecond infrared spectroscopy (fs-IR). We find evidence that the oligoethylene glycol side chains trap part of the water molecules upon gel formation, and we propose that the interaction between the oligoethylene glycol side chains and water plays an essential role in the bundling of the polymers and thus in the formation of a hydrogel.
- Published
- 2021
29. Strong Reduction of the Chain Rigidity of Hyaluronan by Selective Binding of Ca2+ Ions
- Author
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Bernd Ensing, Dixy E. Green, Ralf P. Richter, Fouzia Bano, Alberto Pérez de Alba Ortíz, Paul L. DeAngelis, Xing Zhang, Robert J. Linhardt, Gijsje H. Koenderink, Giulia Giubertoni, Huib J. Bakker, HIMS Other Research (FNWI), Molecular Spectroscopy (HIMS, FNWI), and Molecular Simulations (HIMS, FNWI)
- Subjects
chemistry.chemical_classification ,Polymers and Plastics ,Organic Chemistry ,Force spectroscopy ,Infrared spectroscopy ,chemistry.chemical_element ,02 engineering and technology ,Calcium ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Polyelectrolyte ,Article ,0104 chemical sciences ,Divalent ,Inorganic Chemistry ,Molecular dynamics ,chemistry ,Intramolecular force ,Materials Chemistry ,Biophysics ,Binding site ,0210 nano-technology - Abstract
The biological functions of natural polyelectrolytes are strongly influenced by the presence of ions, which bind to the polymer chains and thereby modify their properties. Although the biological impact of such modifications is well recognized, a detailed molecular picture of the binding process and of the mechanisms that drive the subsequent structural changes in the polymer is lacking. Here, we study the molecular mechanism of the condensation of calcium, a divalent cation, on hyaluronan, a ubiquitous polymer in human tissues. By combining two-dimensional infrared spectroscopy experiments with molecular dynamics simulations, we find that calcium specifically binds to hyaluronan at millimolar concentrations. Because of its large size and charge, the calcium cation can bind simultaneously to the negatively charged carboxylate group and the amide group of adjacent saccharide units. Molecular dynamics simulations and single-chain force spectroscopy measurements provide evidence that the binding of the calcium ions weakens the intramolecular hydrogen-bond network of hyaluronan, increasing the flexibility of the polymer chain. We also observe that the binding of calcium to hyaluronan saturates at a maximum binding fraction of similar to 10-15 mol %. This saturation indicates that the binding of Ca2+ strongly reduces the probability of subsequent binding of Ca2+ at neighboring binding sites, possibly as a result of enhanced conformational fluctuations and/or electrostatic repulsion effects. Our findings provide a detailed molecular picture of ion condensation and reveal the severe effect of a few, selective and localized electrostatic interactions on the rigidity of a polyelectrolyte chain.
- Published
- 2021
30. Correction: The molecular structure of the surface of water–ethanol mixtures
- Author
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Johannes Kirschner, Anderson H. A. Gomes, Ricardo R. T. Marinho, Olle Björneholm, Hans Ågren, Vincenzo Carravetta, Niklas Ottosson, Arnaldo Naves de Brito, and Huib J. Bakker
- Subjects
General Physics and Astronomy ,Physical and Theoretical Chemistry - Abstract
Correction for ‘The molecular structure of the surface of water–ethanol mixtures’ by Johannes Kirschner et al., Phys. Chem. Chem. Phys., 2021, 23, 11568–11578, DOI: 10.1039/D0CP06387H.
- Published
- 2022
31. Strong reduction of the chain rigidity of hyaluronan by selective binding of Ca2+ ions
- Author
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Bernd Ensing, Giulia Giubertoni, Robert J. Linhardt, Gijsje H. Koenderink, Ralf P. Richter, Fouzia Bano, Dixy E. Green, Paul L. DeAngelis, A. Pérez de Alba Ortíz, Xing Zhang, and Huib J. Bakker
- Subjects
chemistry.chemical_classification ,Molecular dynamics ,chemistry ,Force spectroscopy ,Biophysics ,chemistry.chemical_element ,Infrared spectroscopy ,Polymer ,Calcium ,Binding site ,Polyelectrolyte ,Divalent - Abstract
The biological functions of natural polyelectrolytes are strongly influenced by the presence of ions, which bind to the polymer chains and thereby modify their properties. Although the biological impact of such modifications is well-recognized, a detailed molecular picture of the binding process and of the mechanisms that drive the subsequent structural changes in the polymer is lacking. Here, we study the molecular mechanism of the condensation of calcium, a divalent cation, on hyaluronan, a ubiquitous polymer in human tissues. By combining two-dimensional infrared spectroscopy experiments with molecular dynamics simulations, we find that calcium specifically binds to hyaluronan at millimolar concentrations. Because of its large size and charge, the calcium cation can bind simultaneously to the negatively charged carboxylate group and the amide group of adjacent saccharide units. Molecular dynamics simulations and single-chain force spectroscopy measurements provide evidence that the binding of the calcium ions weakens the intra-molecular hydrogen-bond network of hyaluronan, increasing the flexibility of the polymer chain. We also observe that the binding of calcium to hyaluronan saturates at a maximum binding fraction of ~10-15 mol %. This saturation indicates that the binding of Ca2+ strongly reduces the probability of subsequent binding of Ca2+ at neighboring binding sites, possibly as a result of enhanced conformational fluctuations and/or electrostatic repulsion effects. Our findings provide a detailed molecular picture of ion condensation, and reveal the severe effect of a few, selective and localized electrostatic interactions on the rigidity of a polyelectrolyte chain.TOC
- Published
- 2020
32. Thermodynamic stabilization of mixed-halide perovskites against phase segregation
- Author
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Bruno Ehrler, Aron Walsh, Huib J. Bakker, Jan Versluis, Young Won Woo, Young-Kwang Jung, Francesca Wittmann, Loreta A. Muscarella, Eline M. Hutter, Lucie McGovern, and Sub ARC Chemical Building Blocks Cons.
- Subjects
Materials science ,Chemistry(all) ,Band gap ,Iodide ,General Physics and Astronomy ,Halide ,FOS: Physical sciences ,Physics and Astronomy(all) ,chemistry.chemical_compound ,symbols.namesake ,pressure ,thermodynamics ,Condensed Matter::Materials Science ,Materials Science(all) ,Energy(all) ,Bromide ,Physics - Chemical Physics ,Phase (matter) ,Physics::Atomic and Molecular Clusters ,General Materials Science ,Physics::Chemical Physics ,Engineering(all) ,Perovskite (structure) ,chemistry.chemical_classification ,Chemical Physics (physics.chem-ph) ,business.industry ,General Engineering ,mixed-halide perovskites ,General Chemistry ,segregation ,lcsh:QC1-999 ,Gibbs free energy ,General Energy ,Semiconductor ,chemistry ,Chemical physics ,symbols ,business ,lcsh:Physics - Abstract
Summary Mixing iodide and bromide in halide perovskite semiconductors is an effective strategy to tune their band gap; therefore, mixed-halide perovskites hold great promise for color-tunable LEDs and tandem solar cells. However, the band gap of mixed-halide perovskites is unstable under (sun-)light, since the halides segregate into domains of different band gaps. Using pressure-dependent ultrafast transient absorption spectroscopy, we find that high external pressure increases the range of stable halide mixing ratios. Chemical compression, by inserting a smaller cation, has the same effect, which means that any iodide:bromide ratio can be stabilized by tuning the crystal volume and compressibility. We interpret these findings as an increased thermodynamic stabilization through alteration of the Gibbs free energy via the largely overlooked PΔV term.
- Published
- 2020
33. Slow Proton Transfer in Nanoconfined Water
- Author
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Huib J. Bakker and Oleksandr O. Sofronov
- Subjects
Materials science ,Proton ,010405 organic chemistry ,Hydrogen bond ,General Chemical Engineering ,Diffusion ,General Chemistry ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Chemistry ,Membrane ,Chemical physics ,Ultrafast laser spectroscopy ,Femtosecond ,Physics::Atomic and Molecular Clusters ,Molecule ,Physics::Chemical Physics ,Spectroscopy ,Nuclear Experiment ,QD1-999 ,Research Article - Abstract
The transport of protons in nanoconfined environments, such as in nanochannels of biological or artificial proton conductive membranes, is essential to chemistry, biology, and nanotechnology. In water, proton diffusion occurs by hopping of protons between water molecules. This process involves the rearrangement of many hydrogen bonds and as such can be strongly affected by nanoconfinement. We study the vibrational and structural dynamics of hydrated protons in water nanodroplets stabilized by a cationic surfactant using polarization-resolved femtosecond infrared transient absorption spectroscopy. We determine the time scale of proton hopping in the center of the water nanodroplets from the dynamics of the anisotropy of the transient absorption signals. We find that in small nanodroplets with a diameter, Time-resolved infrared spectroscopy shows that the hopping of an excess proton from one water molecule to another water molecule occurs much slower in nanodroplets than in bulk.
- Published
- 2020
34. Temperature-induced collapse of elastin-like peptides studied by 2DIR spectroscopy
- Author
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Oleg Selig, Jan C. M. van Hest, Ana V. Cunha, Mark B. van Eldijk, Thomas L. C. Jansen, Yves L. A. Rezus, Huib J. Bakker, Theory of Condensed Matter, and Bio-Organic Chemistry
- Subjects
Conformational change ,Spectrophotometry, Infrared ,PROTEINS ,Protein Conformation ,Infrared spectroscopy ,Peptide ,Molecular Dynamics Simulation ,010402 general chemistry ,Peptides/chemistry ,01 natural sciences ,CONFORMATIONAL TRANSITION ,Bio-Organic Chemistry ,Vibration ,Phase Transition ,Molecular dynamics ,chemistry.chemical_compound ,Protein structure ,IR SPECTROSCOPY ,SYSTEMS ,Amide ,0103 physical sciences ,Materials Chemistry ,Molecule ,Physical and Theoretical Chemistry ,DRUG-DELIVERY ,Spectroscopy ,chemistry.chemical_classification ,010304 chemical physics ,Chemistry ,BETA-TURNS ,POLYPEPTIDES ,Temperature ,Water ,Amides ,0104 chemical sciences ,Surfaces, Coatings and Films ,SECONDARY-STRUCTURE FORMATION ,Crystallography ,MOLECULAR-DYNAMICS ,Spectrophotometry ,Water/chemistry ,Amides/chemistry ,Peptides ,Infrared ,Hydrophobic and Hydrophilic Interactions - Abstract
Elastin-like peptides are hydrophobic biopolymers that exhibit a reversible coacervation transition when the temperature is raised above a critical point. Here, we use a combination of linear infrared spectroscopy, two-dimensional infrared spectroscopy, and molecular dynamics simulations to study the structural dynamics of two elastin-like peptides. Specifically, we investigate the effect of the solvent environment and temperature on the structural dynamics of a short (5-residue) elastin-like peptide and of a long (450-residue) elastin-like peptide. We identify two vibrational energy transfer processes that take place within the amide I' band of both peptides. We observe that the rate constant of one of the exchange processes is strongly dependent on the solvent environment and argue that the coacervation transition is accompanied by a desolvation of the peptide backbone where up to 75% of the water molecules are displaced. We also study the spectral diffusion dynamics of the valine(1) residue that is present in both peptides. We find that these dynamics are relatively slow and indicative of an amide group that is shielded from the solvent. We conclude that the coacervation transition of elastin-like peptides is probably not associated with a conformational change involving this residue.
- Published
- 2018
35. Structure of micelles and micro-emulsions probed through the molecular reorientation of water
- Author
-
Huib J. Bakker and Eliane P. van Dam
- Subjects
010304 chemical physics ,Infrared ,Chemistry ,General Physics and Astronomy ,Fraction (chemistry) ,Bulk water ,010402 general chemistry ,01 natural sciences ,Micelle ,0104 chemical sciences ,Chemical engineering ,Water fraction ,0103 physical sciences ,Molecule ,Physical and Theoretical Chemistry ,Dodecyltrimethylammonium bromide ,Spectroscopy - Abstract
We study the structural properties of dodecyltrimethylammonium bromide (DTAB) micelles and micro-emulsions by probing the molecular reorientation of water with polarization-resolved infrared pump-probe spectroscopy. For all systems studied, we observe that a fraction of water reorients on a much slower timescale than bulk water. This slow water fraction increases sublinear with increasing DTAB concentration, indicating an increase of the micelle size and enhanced micelle aggregation with concentration. We observe that the addition of oil to the micelle solutions, leading to the formation of a micro-emulsion, does not lead to a significant change of the fraction of slow water, showing that the added oil molecules are well solvated within the core of the micelles, and thus completely shielded from water.
- Published
- 2018
36. Antifreeze Glycoproteins Bind Irreversibly to Ice
- Author
-
Ran Drori, Huib J. Bakker, Arthur L. DeVries, and Konrad Meister
- Subjects
Gene isoform ,Antifreeze Glycoproteins ,02 engineering and technology ,Plasma protein binding ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Adsorption ,Antifreeze protein ,Antifreeze Proteins ,Fluorescence microscope ,Animals ,Glycoproteins ,Ice crystals ,Chemistry ,Ice ,Water ,General Chemistry ,021001 nanoscience & nanotechnology ,Perciformes ,0104 chemical sciences ,Biophysics ,Growth inhibition ,0210 nano-technology ,Protein Binding - Abstract
Antifreeze proteins (AFPs) and antifreeze glycoproteins (AFGPs) inhibit ice growth via an adsorption-inhibition mechanism that assumes irreversible binding of AF(G)Ps to embryonic ice crystals and the inhibition of further growth. The irreversible binding of antifreeze glycoproteins (AFGPs) to ice has been questioned and remains poorly understood. Here, we used microfluidics and fluorescence microscopy to investigate the nature of the binding of small and large AFGP isoforms. We found that both AFGP isoforms bind irreversibly to ice, as evidenced by microfluidic solution exchange experiments. We measured the adsorption rate of the large AFGP isoform and found it to be 50% faster than that of AFP type III. We also found that the AFGP adsorption rate decreased by 65% in the presence of borate, a well-known inhibitor of AFGP activity. Our results demonstrate that the adsorption rate of AFGPs to ice is crucial for their ice growth inhibition capability.
- Published
- 2018
37. Molecular Insight into the Slipperiness of Ice
- Author
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Mischa Bonn, Stefania Ketzetzi, Wilbert J. Smit, Yuki Nagata, Bart Weber, Daniel Bonn, Ellen H. G. Backus, Fujie Tang, Huib J. Bakker, Soft Matter (WZI, IoP, FNWI), Molecular Spectroscopy (HIMS, FNWI), and IoP (FNWI)
- Subjects
Shearing (physics) ,Materials science ,integumentary system ,Arrhenius behavior ,02 engineering and technology ,Activation energy ,Atmospheric temperature range ,Low friction ,021001 nanoscience & nanotechnology ,01 natural sciences ,Molecular dynamics ,Chemical physics ,0103 physical sciences ,Molecule ,General Materials Science ,Physical and Theoretical Chemistry ,010306 general physics ,0210 nano-technology ,Ice skating ,human activities - Abstract
Measurements of the friction coefficient of steel-on-ice over a large temperature range reveal very high friction at low temperatures (-100 °C) and a steep decrease in the friction coefficient with increasing temperature. Very low friction is only found over the limited temperature range typical for ice skating. The strong decrease in the friction coefficient with increasing temperature exhibits Arrhenius behavior with an activation energy of Ea ≈ 11.5 kJ mol-1. Remarkably, molecular dynamics simulations of the ice-air interface reveal a very similar activation energy for the mobility of surface molecules. Weakly hydrogen-bonded surface molecules diffuse over the surface in a rolling motion, their number and mobility increasing with increasing temperature. This correlation between macroscopic friction and microscopic molecular mobility indicates that slippery ice arises from the high mobility of its surface molecules, making the ice surface smooth and the shearing of the weakly bonded surface molecules easy.
- Published
- 2018
38. Observation of Ultrafast Vibrational Energy Transfer in Fibrinogen and Fibrin Fibers
- Author
-
Bart Vos, Biplab Dutta, Gijsje H. Koenderink, Huib J. Bakker, and Yves L. A. Rezus
- Subjects
0301 basic medicine ,Materials science ,Spectrophotometry, Infrared ,Infrared spectroscopy ,Photochemistry ,Antiparallel (biochemistry) ,Fibrinogen ,Article ,Fibrin ,Polymerization ,03 medical and health sciences ,Materials Chemistry ,medicine ,Humans ,Fiber ,Physical and Theoretical Chemistry ,Protein secondary structure ,biology ,Surfaces, Coatings and Films ,Kinetics ,030104 developmental biology ,Energy Transfer ,Molecular vibration ,biology.protein ,Protein Conformation, beta-Strand ,medicine.drug - Abstract
We study the secondary structure of the blood protein fibrinogen using two-dimensional infrared spectroscopy. With this technique, we identify the amide I' vibrational modes of the antiparallel β-sheets and turns of fibrinogen. We observe ultrafast energy flow among these amide I' vibrational modes with a time constant of ∼7 ps. This energy transfer time constant does not change significantly upon fibrin fiber formation, indicating that the secondary structure of the fibrinogen monomers remains largely unchanged in the polymerization process.
- Published
- 2018
39. Reduced Near-Resonant Vibrational Coupling at the Surfaces of Liquid Water and Ice
- Author
-
Mischa Bonn, Wilbert J. Smit, Huib J. Bakker, Ellen H. G. Backus, and Jan Versluis
- Subjects
Coupling ,Letter ,Materials science ,010304 chemical physics ,Liquid water ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Vibration ,Delocalized electron ,Chemical physics ,0103 physical sciences ,Molecule ,General Materials Science ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Rotational–vibrational coupling ,Spectroscopy ,Physics::Atmospheric and Oceanic Physics - Abstract
We study the resonant interaction of the OH stretch vibrations of water molecules at the surfaces of liquid water and ice using heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy. By studying different isotopic mixtures of H2O and D2O, we vary the strength of the interaction, and we monitor the resulting effect on the HD-SFG spectrum of the OH stretch vibrations. We observe that the near-resonant coupling effects are weaker at the surface than in the bulk, for both water and ice, indicating that for both phases of water the OH vibrations are less strongly delocalized at the surface than in the bulk.
- Published
- 2018
40. Orientation of Methylguanidinium Ions at the Water–Air Interface
- Author
-
Simona Strazdaite, Huib J. Bakker, Jan Versluis, and Niklas Ottosson
- Subjects
Surface (mathematics) ,Aqueous solution ,010304 chemical physics ,Antisymmetric relation ,Chemistry ,Plane (geometry) ,010402 general chemistry ,Polarization (waves) ,01 natural sciences ,Molecular physics ,Article ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Ion ,Molecular dynamics ,Crystallography ,General Energy ,Orientation (geometry) ,0103 physical sciences ,Physical and Theoretical Chemistry - Abstract
We use heterodyne-detected vibrational sum-frequency generation (HD-VSFG) to determine the orientation of the molecular plane of methylguanidinium ions at the surface of aqueous solutions. We measure the VSFG response of the symmetric and antisymmetric methyl stretch vibrations of the methylguanidinium ion with different polarization combinations. We find that for at least 50% of the methylguanidinium ions the molecular plane is at an angle >20° with respect to the surface plane. Hence, for only a minor fraction of the ions does the molecular plane have an orientation (near-)parallel to the surface plane, in contrast to the predictions of recent molecular dynamics simulation studies.
- Published
- 2017
41. Molecular structure of hydrophobins studied with site-directed mutagenesis and vibrational sum-frequency generation spectroscopy
- Author
-
Huib J. Bakker, Bart Speet, Arja Paananen, Konrad Meister, and Michael Lienemann
- Subjects
Fungal Proteins/chemistry ,Stereochemistry ,Hydrophobin ,Surface Properties ,Spectrophotometry/methods ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Vibration ,Article ,Protein–protein interaction ,Fungal Proteins ,Aspartic Acid/chemistry ,Amphiphile ,Molecular film ,Aspartic acid ,Materials Chemistry ,Site-Directed ,Physical and Theoretical Chemistry ,Site-directed mutagenesis ,ta216 ,ta116 ,Trichoderma ,Fungal protein ,Aspartic Acid ,Molecular Structure ,Chemistry ,Air ,Water ,021001 nanoscience & nanotechnology ,Elasticity ,0104 chemical sciences ,Surfaces, Coatings and Films ,Spectrophotometry ,Mutagenesis ,Water/chemistry ,Biophysics ,Mutagenesis, Site-Directed ,0210 nano-technology ,Hydrophobic and Hydrophilic Interactions ,Sum frequency generation spectroscopy - Abstract
Hydrophobins are surface-active fungal proteins that adsorb to the water-air interface and self-assemble into amphiphilic, water-repelling films that have a surface elasticity that is an order of magnitude higher than other molecular films. Here we use surface-specific sum-frequency generation spectroscopy (VSFG) and site-directed mutagenesis to study the properties of class I hydrophobin (HFBI) films from Trichoderma reesei at the molecular level. We identify protein specific HFBI signals in the frequency region 1200-1700 cm-1 that have not been observed in previous VSFG studies on proteins. We find evidence that the aspartic acid residue (D30) next to the hydrophobic patch is involved in lateral intermolecular protein interactions, while the two aspartic acid residues (D40, D43) opposite to the hydrophobic patch are primarily interacting with the water solvent.
- Published
- 2017
42. Observation and Identification of a New OH Stretch Vibrational Band at the Surface of Ice
- Author
-
Wilbert J. Smit, Mischa Bonn, Yuki Nagata, Taisuke Hasegawa, Ellen H. G. Backus, M. Alejandra Sánchez, Huib J. Bakker, and Fujie Tang
- Subjects
Surface (mathematics) ,Letter ,Chemistry ,Hydrogen bond ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Acceptor ,Molecular physics ,0104 chemical sciences ,Molecular dynamics ,Molecule ,General Materials Science ,Physical and Theoretical Chemistry ,Atomic physics ,0210 nano-technology - Abstract
We study the signatures of the OH stretch vibrations at the basal surface of ice using heterodyne-detected sum-frequency generation and molecular dynamics simulations. At 150 K, we observe seven distinct modes in the sum-frequency response, five of which have an analogue in the bulk, and two pure surface-specific modes at higher frequencies (∼3530 and ∼3700 cm–1). The band at ∼3530 cm–1 has not been reported previously. Using molecular dynamics simulations, we find that the ∼3530 cm–1 band contains contributions from OH stretch vibrations of both fully coordinated interfacial water molecules and water molecules with two donor and one acceptor hydrogen bond.
- Published
- 2017
43. Observation of pH-Induced Protein Reorientation at the Water Surface
- Author
-
Arja Paananen, Steven J. Roeters, Géza R. Szilvay, Sander Woutersen, Jan Versluis, Konrad Meister, Huib J. Bakker, Time-resolved vibrational spectroscopy, and Molecular Spectroscopy (HIMS, FNWI)
- Subjects
0301 basic medicine ,air-water interface ,Letter ,Hydrophobin ,Protein Conformation ,ta221 ,Janus particles ,010402 general chemistry ,01 natural sciences ,Protein Structure, Secondary ,Fungal Proteins ,03 medical and health sciences ,Adsorption ,Protein structure ,Amphiphile ,interfacial behavior ,Molecule ,General Materials Science ,Physical and Theoretical Chemistry ,ta216 ,Spectroscopy ,ta116 ,vibrational sum-frequency generation spectroscopy ,ta114 ,Chemistry ,Air ,Water ,hydophobin ,0104 chemical sciences ,Solvent ,Crystallography ,030104 developmental biology ,Chemical physics ,VSFGS ,Hydrophobic and Hydrophilic Interactions ,HFBII - Abstract
Hydrophobins are surface-active proteins that form a hydrophobic, water-repelling film around aerial fungal structures. They have a compact, particle-like structure, in which hydrophilic and hydrophobic regions are spatially, separated. This surface property renders them amphiphilic and is reminiscent of synthetic Janus particles. Here we report surface-specific chiral and nonchiral vibrational sum-frequency generation spectroscopy (VSFG) measurements of hydrophobins adsorbed to their natural place of action, the air-water interface. We observe that hydrophobin molecules undergo a reversible-change in orientation (tilt) at the interface when the pH is varied. We explain this local orientation toggle from the modification of the interprotein interactions and the interaction of hydrophobin with the water solvent, following the pH-induced change of the charge state of particular amino acids.
- Published
- 2017
44. Reduced Acid Dissociation of Amino-Acids at the Surface of Water
- Author
-
Simona Strazdaite, Konrad Meister, and Huib J. Bakker
- Subjects
Surface Properties ,Carboxylic acid ,Inorganic chemistry ,Carboxylic Acids ,02 engineering and technology ,010402 general chemistry ,Vibration ,01 natural sciences ,Biochemistry ,Article ,Catalysis ,Acid dissociation constant ,Ion ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Ionization ,Carboxylate ,Amino Acids ,Spectroscopy ,chemistry.chemical_classification ,Air ,Water ,General Chemistry ,Hydrogen-Ion Concentration ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Amino acid ,chemistry ,Attenuated total reflection ,0210 nano-technology ,Oxidation-Reduction - Abstract
We use surface-specific intensity vibrational sum-frequency generation and attenuated total reflection spectroscopy to probe the ionization state of the amino-acids l-alanine and l-proline at the air/water surface and in the bulk. The ionization state is determined by probing the vibrational signatures of the carboxylic acid group, representing the nondissociated acid form, and the carboxylate anion group, representing the dissociated form, over a wide range of pH values. We find that the carboxylic acid group deprotonates at a significantly higher pH at the surface than in the bulk.
- Published
- 2017
45. Vibrational and structural relaxation of hydrated protons in Nafion membranes
- Author
-
Liyuan Liu, Huib J. Bakker, and Stephan Lotze
- Subjects
Proton ,Infrared ,Hydrogen bond ,Chemistry ,Relaxation (NMR) ,General Physics and Astronomy ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Chemical physics ,Excited state ,Ultrafast laser spectroscopy ,Intermediate state ,Physical and Theoretical Chemistry ,0210 nano-technology ,Spectroscopy - Abstract
We study the vibrational dynamics of the bending mode at 1730 cm −1 of proton hydration structures in Nafion membranes with polarization-resolved infrared (IR) pump-probe spectroscopy. The bending mode relaxes to an intermediate state with a time constant T 1 of 170 ± 30 fs. Subsequently, the dissipated energy equilibrates with T eq of 1.5 ± 0.2 ps. The transient absorption signals show a long-living anisotropy, which indicates that for part of the excited proton hydration clusters the vibrational energy dissipation results in a local structural change, e.g. the breaking of a local hydrogen bond. This structural relaxation relaxes with a time constant of 38 ± 4 ps.
- Published
- 2017
46. Identification of the response of protein N–H vibrations in vibrational sum-frequency generation spectroscopy of aqueous protein films
- Author
-
Konrad Meister, Arja Paananen, and Huib J. Bakker
- Subjects
air-water interface ,Work (thermodynamics) ,Nitrogen ,Hydrophobin ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,Vibration ,01 natural sciences ,Spectral line ,interfacial behavior ,Molecule ,Physical and Theoretical Chemistry ,Spectroscopy ,ta116 ,vibrational sum-frequency generation spectroscopy ,Aqueous solution ,ta114 ,Chemistry ,Spectrum Analysis ,Proteins ,Water ,hydophobin ,Hydrogen-Ion Concentration ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Crystallography ,Molecular vibration ,VSFGS ,0210 nano-technology ,HFBI ,Hydrogen ,Sum frequency generation spectroscopy - Abstract
The N-H stretching vibration is an important probe for investigating structural and functional properties of proteins but is often difficult to analyze as it overlaps with the O-H stretching vibration of water molecules. In this work we investigate the N-H signals of hydrophobins using conventional (VSFG) and heterodyne-detected vibrational sum-frequency generation spectroscopy (HD-VSDG). Hydrophobins represent a group of surface active proteins that form highly-ordered protein films at the water-air interface and that give rise to prominent vibrational modes. We find that in conventional VSFG spectra N-H specific signals show significant changes in shape and intensity upon altering the pH values. These changes can easily be misinterpreted for conformational changes of the protein. Using HD-VSFG experiments, we demonstrate, that for hydrophobin films the change of the N-H response with pH can be well explained from the interference of the N-H response with the broad interfacial water O-H stretch band.
- Published
- 2017
47. Experimental and theoretical evidence for bilayer-by-bilayer surface melting of crystalline ice
- Author
-
Mara Jochum, Tatsuya Ishiyama, Jenée D. Cyran, Wilbert J. Smit, M. Alejandra Sánchez, Mischa Bonn, Tanja Kling, Marc Jan Van Zadel, Akihiro Morita, Huib J. Bakker, Markus Mezger, Patrick J. Bisson, Yuki Nagata, Mary Jane Shultz, Ellen H. G. Backus, and Davide Donadio
- Subjects
Multidisciplinary ,Sum-frequency generation ,Materials science ,Bilayer ,Transition temperature ,Sum frequency generation ,Surface melting ,Water ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Spectral line ,0104 chemical sciences ,Molecular dynamics ,Chemical physics ,Commentaries ,Melting point ,Stepwise ,0210 nano-technology ,Spectroscopy ,Crystalline ice ,Layer (electronics) - Abstract
On the surface of water ice, a quasi-liquid layer (QLL) has been extensively reported at temperatures below its bulk melting point at 273 K. Approaching the bulk melting temperature from below, the thickness of the QLL is known to increase. To elucidate the precise temperature variation of the QLL, and its nature, we investigate the surface melting of hexagonal ice by combining noncontact, surface-specific vibrational sum frequency generation (SFG) spectroscopy and spectra calculated from molecular dynamics simulations. Using SFG, we probe the outermost water layers of distinct single crystalline ice faces at different temperatures. For the basal face, a stepwise, sudden weakening of the hydrogen-bonded structure of the outermost water layers occurs at 257 K. The spectral calculations from the molecular dynamics simulations reproduce the experimental findings; this allows us to interpret our experimental findings in terms of a stepwise change from one to two molten bilayers at the transition temperature.
- Published
- 2016
48. Molecular Origin of the Elastic State of Aqueous Hyaluronic Acid
- Author
-
Gijsje H. Koenderink, Cristina Martinez-Torres, Eddie G. Pelan, Federica Burla, Biplab Dutta, Huib J. Bakker, Yves L. A. Rezus, Galja Pletikapić, and Giulia Giubertoni
- Subjects
Spectrophotometry, Infrared ,Disaccharide ,Infrared spectroscopy ,engineering.material ,010402 general chemistry ,Microscopy, Atomic Force ,01 natural sciences ,chemistry.chemical_compound ,Biopolymers ,Rheology ,0103 physical sciences ,Hyaluronic acid ,Materials Chemistry ,Physical and Theoretical Chemistry ,Hyaluronic Acid ,Aqueous solution ,010304 chemical physics ,Hydrogen bond ,Hydrogels ,Hydrogen Bonding ,Hydrogen-Ion Concentration ,Elasticity ,0104 chemical sciences ,Surfaces, Coatings and Films ,chemistry ,Chemical engineering ,Self-healing hydrogels ,engineering ,Biopolymer - Abstract
[Image: see text] The macroscopic mechanical properties of biological hydrogels are broadly studied and successfully mimicked in synthetic materials, but little is known about the molecular interactions that mediate these properties. Here, we use two-dimensional infrared spectroscopy to study the pH-induced gelation of hyaluronic acid, a ubiquitous biopolymer, which undergoes a transition from a viscous to an elastic state in a narrow pH range around 2.5. We find that the gelation originates from the enhanced formation of strong interchain connections, consisting of a double amide–COOH hydrogen bond and an N–D–COO(–) hydrogen bond on the adjacent sugars of the hyaluronan disaccharide unit. We confirm the enhanced interchain connectivity in the elastic state by atomic force microscopy imaging.
- Published
- 2019
49. Caffeine and taurine slow down water molecules
- Author
-
Roberto Cota, Eliane P. van Dam, Huib J. Bakker, Wilbert J. Smit, and Molecular Spectroscopy (HIMS, FNWI)
- Subjects
chemistry.chemical_compound ,Taurine ,Solvation shell ,Chemistry ,Femtosecond ,Relaxation (NMR) ,General Physics and Astronomy ,Molecule ,Dielectric ,Photochemistry ,Caffeine ,Spectroscopy - Abstract
In this work we study the effect of caffeine and taurine on the mobility of water molecules at 298 K using femtosecond mid-infrared and dielectric relaxation spectroscopy. We observe both molecules to have a slowing down effect on the mobility of surrounding water molecules: a single caffeine molecule slows down ~9 water molecules, a single taurine molecule slows down ~4 water molecules. The reorientation time constant of these slow water molecules is 4-5 times longer than the reorientation time constant of 2.5 ps of water molecules in bulk liquid water.
- Published
- 2019
50. Determination of the Solution Structure of Antifreeze Glycoproteins Using Two-Dimensional Infrared Spectroscopy
- Author
-
Huib J. Bakker, Konrad Meister, Arthur L. DeVries, and Giulia Giubertoni
- Subjects
Letter ,010304 chemical physics ,Absorption spectroscopy ,Spectrophotometry, Infrared ,Infrared ,Chemistry ,Temperature ,Infrared spectroscopy ,010402 general chemistry ,01 natural sciences ,Protein Structure, Secondary ,0104 chemical sciences ,chemistry.chemical_compound ,Crystallography ,Magnesium Sulfate ,Protein structure ,Amide ,Two-dimensional infrared spectroscopy ,Antifreeze Proteins ,0103 physical sciences ,Borates ,Side chain ,General Materials Science ,Physical and Theoretical Chemistry ,Polyproline helix - Abstract
We study the solution structure of antifreeze glycoproteins (AFGPs) with linear and two-dimensional infrared spectroscopy (2D-IR). With 2D-IR, we study the coupling between the amide I and amide II vibrations of AFGPs. The measured nonlinear spectral response constitutes a much more clearly resolved amide I spectrum than the linear absorption spectrum of the amide I vibrations and allows us to identify the different structural elements of AFGPs in solution. We find clear evidence for the presence of polyproline II (PPII) helical structures already at room temperature, and we find that the fraction of PPII structures increases when the temperature is decreased to the biological working temperature of AFGP. We observe that inhibition of the antifreeze activity of AFGP using borate buffer or enhancing the antifreeze activity using sulfate buffer does not lead to significant changes in the protein conformation. This finding indicates that AFGPs bind to ice with their sugar side chains.
- Published
- 2019
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