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Chettri A, Kaberov LI, Klosterhalfen N, Perera S, Jamshied M, Schacher FH, Dietzek-Ivanšić B. Poly(2-Oxazoline) Amphiphilicity Tunes the Excited-State Proton Transfer of Pyrenol-Based Polyphotoacids. Chemistry 2024; 30:e202401047. [PMID: 38699878 DOI: 10.1002/chem.202401047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 05/05/2024]
Abstract
The ability of light to change the properties of light-responsive polymers opens avenues for targeted release of cargo with a high degree of spatial and temporal control. Recently, we established photoacid polymers as light-switchable macromolecular amphiphiles. In these systems, light-induced excited-state proton transfer (ESPT) causes changes in amphilicity. However, as the intermolecular process itself critically depends on the local environment of the photoacid unit within the polymer, the overall amphiphilicity directly influences ESPT. Thus, understanding the impact of the local environment on the photophysics of photoacidic side chains is key to material design. In this contribution we address both thermodynamic and kinetic aspects of ESPT in oxazoline-based amphiphilic polymers with pyrenol-based photoacid side chains. We will compare the effect of polymer design, i. e. statistical and block arrangements, i. e. in poly[(2-ethyl-2-oxazoline)-co-(1-(6/8-hydroxyperene)sulphonylaziridine)] and poly(2-ethyl-2-oxazoline)-block-poly[(2-ethyl-2-oxazoline)-co-(2-(3-(6-hydroxypyrene)sulphonamide)propyl-2-oxazoline), on the intermolecular proton transfer reaction by combining steady-state and time-resolved absorption and emission spectroscopy. ESPT appears more prominent in the statistical copolymer compared to a block copolymer with overall similar pyrenol loading. We hypothesize that the difference is due to different local chain arrangements adopted by the polymers in the two cases.
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Affiliation(s)
- Avinash Chettri
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Research Department Functional Interfaces, Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Leonid I Kaberov
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, Humboldtstraße 10, 07743, Jena, Germany
- Jena Center for Soft Matter, Friedrich Schiller University Jena, Philosophenweg 7, 07743, Jena, Germany
| | - Niklas Klosterhalfen
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Research Department Functional Interfaces, Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Sandunika Perera
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, Humboldtstraße 10, 07743, Jena, Germany
- Jena Center for Soft Matter, Friedrich Schiller University Jena, Philosophenweg 7, 07743, Jena, Germany
| | - Mohammed Jamshied
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, Humboldtstraße 10, 07743, Jena, Germany
- Jena Center for Soft Matter, Friedrich Schiller University Jena, Philosophenweg 7, 07743, Jena, Germany
| | - Felix H Schacher
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, Humboldtstraße 10, 07743, Jena, Germany
- Jena Center for Soft Matter, Friedrich Schiller University Jena, Philosophenweg 7, 07743, Jena, Germany
| | - Benjamin Dietzek-Ivanšić
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Research Department Functional Interfaces, Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
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2
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Ramanthrikkovil Variyam A, Rzycki M, Yucknovsky A, Stuchebrukhov AA, Drabik D, Amdursky N. Proton diffusion on the surface of mixed lipid membranes highlights the role of membrane composition. Biophys J 2024:S0006-3495(24)00441-7. [PMID: 38961623 DOI: 10.1016/j.bpj.2024.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/13/2024] [Accepted: 07/01/2024] [Indexed: 07/05/2024] Open
Abstract
Proton circuits within biological membranes, the foundation of natural bioenergetic systems, are significantly influenced by the lipid compositions of different biological membranes. In this study, we investigate the influence of mixed lipid membrane composition on the proton transfer (PT) properties on the surface of the membrane. We track the excited-state PT (ESPT) process from a tethered probe to the membrane with timescales and length scales of PT relevant to bioenergetic systems. Two processes can happen during ESPT: the initial PT from the probe to the membrane at short timescales, followed by diffusion of dissociated protons around the probe on the membrane, and the possible geminate recombination with the probe at longer timescales. Here, we use membranes composed of mixtures of phosphatidylcholine (PC) and phosphatidic acid (PA). We show that the changes in the ESPT properties are not monotonous with the concentration of the lipid mixture; at a low concentration of PA in PC, we find that the membrane is a poor proton acceptor. Molecular dynamics simulations indicate that the membrane is more structured at this specific lipid mixture, with the least number of defects. Accordingly, we suggest that the structure of the membrane is an important factor in facilitating PT. We further show that the composition of the membrane affects the geminate proton diffusion around the probe, whereas, on a timescale of tens of nanoseconds, the dissociated proton is mostly lateral restricted to the membrane plane in PA membranes, while in PC, the diffusion is less restricted by the membrane.
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Affiliation(s)
| | - Mateusz Rzycki
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Anna Yucknovsky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
| | | | - Dominik Drabik
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Nadav Amdursky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel.
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3
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Pal T, Sahu K. Exploring cationic polyelectrolyte-micelle interaction via excited-state proton transfer. Signatures of probe transfer. Phys Chem Chem Phys 2023; 25:2963-2977. [PMID: 36606483 DOI: 10.1039/d2cp03883h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Excited-state proton transfer (ESPT) is a sensitive tool for the delicate monitoring of structural reorganization, hydration level, and confinement within surfactant and polymer assemblies. Here, we investigate the interaction of a cationic polyelectrolyte, poly(diallyl dimethylammonium chloride) (PDADMAC), with micelles of differently charged surfactants using 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) as an ESPT probe. We used three surfactants: anionic sodium dodecyl sulfate (SDS), cationic dodecyl trimethylammonium bromide (DTAB), and zwitterionic N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SB12), possessing the same alkyl (dodecyl) chain but varying headgroup charges. The fluorescence of HPTS residing initially within the micellar medium modulates differently in the presence of PDADMAC. For the anionic SDS and cationic DTAB micelles, the emission spectrum of HPTS does not alter significantly; however, for SB12 micelles, the emission spectrum undergoes a strong modulation upon adding the polyelectrolyte. The emission intensities quench strongly at a low concentration of PDADMAC but recover at a higher concentration. The emission intensity ratio of the two emission bands also changes significantly, implying strong modulation of the ESPT process with varying PDADMAC concentrations. The time-resolved area normalized emission spectra (TRANES) disclose single isoemissive points in the SB12 micelle at low and high concentrations of PDADMAC but two different isoemissive points (one characteristic of the SB12 micelle at 500 nm and another characteristic of the PDADMAC interface at 480 nm) in the mixed assembly at an intermediate concentration. Detailed analysis suggests that the polyelectrolyte can enforce the transfer of the anionic probe HPTS from the zwitterionic micelle to the PDADMAC assembly above a specific PDADMAC concentration. The transfer of the molecular probe between two assemblies resembles a drug sequestration event, and the study reveals necessary emission signatures.
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Affiliation(s)
- Tapas Pal
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
| | - Kalyanasis Sahu
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
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4
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Shabashini A, Kumar Panja S, Biswas A, Bera S, Chandra Nandi G. ICT based photoacid probe for microsolvation and H-bonding assisted proton transfer process from solute to solvents. J Photochem Photobiol A Chem 2022. [DOI: 10.1016/j.jphotochem.2022.114087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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5
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Nandi R, Amdursky N. The Dual Use of the Pyranine (HPTS) Fluorescent Probe: A Ground-State pH Indicator and an Excited-State Proton Transfer Probe. Acc Chem Res 2022; 55:2728-2739. [PMID: 36053265 PMCID: PMC9494743 DOI: 10.1021/acs.accounts.2c00458] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Indexed: 01/19/2023]
Abstract
Molecular fluorescent probes are an essential experimental tool in many fields, ranging from biology to chemistry and materials science, to study the localization and other environmental properties surrounding the fluorescent probe. Thousands of different molecular fluorescent probes can be grouped into different families according to their photophysical properties. This Account focuses on a unique class of fluorescent probes that distinguishes itself from all other probes. This class is termed photoacids, which are molecules exhibiting a change in their acid-base transition between the ground and excited states, resulting in a large change in their pKa values between these two states, which is thermodynamically described using the Förster cycle. While there are many different photoacids, we focus only on pyranine, which is the most used photoacid, with pKa values of ∼7.4 and ∼0.4 for its ground and excited states, respectively. Such a difference between the pKa values is the basis for the dual use of the pyranine fluorescent probe. Furthermore, the protonated and deprotonated states of pyranine absorb and emit at different wavelengths, making it easy to focus on a specific state. Pyranine has been used for decades as a fluorescent pH indicator for physiological pH values, which is based on its acid-base equilibrium in the ground state. While the unique excited-state proton transfer (ESPT) properties of photoacids have been explored for more than a half-century, it is only recently that photoacids and especially pyranine have been used as fluorescent probes for the local environment of the probe, especially the hydration layer surrounding it and related proton diffusion properties. Such use of photoacids is based on their capability for ESPT from the photoacid to a nearby proton acceptor, which is usually, but not necessarily, water. In this Account, we detail the photophysical properties of pyranine, distinguishing between the processes in the ground state and the ones in the excited state. We further review the different utilization of pyranine for probing different properties of the environment. Our main perspective is on the emerging use of the ESPT process for deciphering the hydration layer around the probe and other parameters related to proton diffusion taking place while the molecule is in the excited state, focusing primarily on bio-related materials. Special attention is given to how to perform the experiments and, most importantly, how to interpret their results. We also briefly discuss the breadth of possibilities in making pyranine derivatives and the use of pyranine for controlling dynamic reactions.
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Affiliation(s)
- Ramesh Nandi
- Schulich Faculty of Chemistry, Technion − Israel Institute of Technology, Haifa 3200003, Israel
| | - Nadav Amdursky
- Schulich Faculty of Chemistry, Technion − Israel Institute of Technology, Haifa 3200003, Israel
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6
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Gilchrist AM, Wang P, Carreira-Barral I, Alonso-Carrillo D, Wu X, Quesada R, Gale PA. Supramolecular methods: the 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) transport assay. Supramol Chem 2021. [DOI: 10.1080/10610278.2021.1999956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | - Patrick Wang
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | | | | | - Xin Wu
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | - Roberto Quesada
- Departmento De Química, Universidad De Burgos, Burgos, Spain
| | - Philip A. Gale
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
- The University of Sydney Nano Institute (Sydney Nano), The University of Sydney, Sydney, NSW 2006, Australia
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7
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Burnstine‐Townley A, Mondal S, Agam Y, Nandi R, Amdursky N. Light‐Modulated Cationic and Anionic Transport across Protein Biopolymers**. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202111024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Alex Burnstine‐Townley
- Schulich Faculty of Chemistry Technion—Israel Institute of Technology Haifa 3200003 Israel
| | - Somen Mondal
- Schulich Faculty of Chemistry Technion—Israel Institute of Technology Haifa 3200003 Israel
| | - Yuval Agam
- Schulich Faculty of Chemistry Technion—Israel Institute of Technology Haifa 3200003 Israel
| | - Ramesh Nandi
- Schulich Faculty of Chemistry Technion—Israel Institute of Technology Haifa 3200003 Israel
| | - Nadav Amdursky
- Schulich Faculty of Chemistry Technion—Israel Institute of Technology Haifa 3200003 Israel
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8
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Burnstine-Townley A, Mondal S, Agam Y, Nandi R, Amdursky N. Light-Modulated Cationic and Anionic Transport across Protein Biopolymers*. Angew Chem Int Ed Engl 2021; 60:24676-24685. [PMID: 34492153 DOI: 10.1002/anie.202111024] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Indexed: 12/13/2022]
Abstract
Light is a convenient source of energy and the heart of light-harvesting natural systems and devices. Here, we show light-modulation of both the chemical nature and ionic charge carrier concentration within a protein-based biopolymer that was covalently functionalized with photoacids or photobases. We explore the capability of the biopolymer-tethered photoacids and photobases to undergo excited-state proton transfer and capture, respectively. Electrical measurements show that both the photoacid- and photobase-functionalized biopolymers exhibit an impressive light-modulated increase in ionic conductivity. Whereas cationic protons are the charge carriers for the photoacid-functionalized biopolymer, water-derived anionic hydroxides are the suggested charge carriers for the photobase-functionalized biopolymer. Our work introduces a versatile toolbox to photomodulate both protons and hydroxides as charge carriers in polymers, which can be of interest for a variety of applications.
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Affiliation(s)
- Alex Burnstine-Townley
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, 3200003, Israel
| | - Somen Mondal
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, 3200003, Israel
| | - Yuval Agam
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, 3200003, Israel
| | - Ramesh Nandi
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, 3200003, Israel
| | - Nadav Amdursky
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, 3200003, Israel
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9
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Nandi R, Agam Y, Amdursky N. A Protein-Based Free-Standing Proton-Conducting Transparent Elastomer for Large-Scale Sensing Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101208. [PMID: 34219263 DOI: 10.1002/adma.202101208] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/20/2021] [Indexed: 05/26/2023]
Abstract
A most important endeavor in modern materials' research is the current shift toward green environmental and sustainable materials. Natural resources are one of the attractive building blocks for making environmentally friendly materials. In most cases, however, the performance of nature-derived materials is inferior to the performance of carefully designed synthetic materials. This is especially true for conductive polymers, which is the topic here. Inspired by the natural role of proteins in mediating protons, their utilization in the creation of a free-standing transparent polymer with a highly elastic nature and proton conductivity comparable to that of synthetic polymers, is demonstrated. Importantly, the polymerization process relies on natural protein crosslinkers and is spontaneous and energy-efficient. The protein used, bovine serum albumin, is one of the most affordable proteins, resulting in the ability to create large-scale materials at a low cost. Due to the inherent biodegradability and biocompatibility of the elastomer, it is promising for biomedical applications. Here, its immediate utilization as a solid-state interface for sensing of electrophysiological signals, is shown.
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Affiliation(s)
- Ramesh Nandi
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Yuval Agam
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Nadav Amdursky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
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10
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Langeland J, Persen NW, Gruber E, Kiefer HV, Kabylda AM, Bochenkova AV, Andersen LH. Controlling Light-Induced Proton Transfer from the GFP Chromophore. Chemphyschem 2021; 22:833-841. [PMID: 33591586 DOI: 10.1002/cphc.202100068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/16/2021] [Indexed: 01/01/2023]
Abstract
Green Fluorescent Protein (GFP) is known to undergo excited-state proton transfer (ESPT). Formation of a short H-bond favors ultrafast ESPT in GFP-like proteins, such as the GFP S65T/H148D mutant, but the detailed mechanism and its quantum nature remain to be resolved. Here we study in vacuo, light-induced proton transfer from the GFP chromophore in hydrogen-bonded complexes with two anionic proton acceptors, I- and deprotonated trichloroacetic acid (TCA- ). We address the role of the strong H-bond and the quantum mechanical proton-density distribution in the excited state, which determines the proton-transfer probability. Our study shows that chemical modifications to the molecular network drastically change the proton-transfer probability and it can become strongly wavelength dependent. The proton-transfer branching ratio is found to be 60 % for the TCA complex and 10 % for the iodide complex, being highly dependent on the photon energy in the latter case. Using high-level ab initio calculations, we show that light-induced proton transfer takes place in S1 , revealing intrinsic photoacid properties of the isolated GFP chromophore in strongly bound H-bonded complexes. ESPT is found to be very sensitive to the topography of the highly anharmonic potential in S1 , depending on the quantum-density distribution upon vibrational excitation. We also show that the S1 potential-energy surface, and hence excited-state proton transfer, can be controlled by altering the chromophore microenvironment.
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Affiliation(s)
- Jeppe Langeland
- Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C, Denmark
| | - Natascha W Persen
- Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C, Denmark
| | - Elisabeth Gruber
- Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C, Denmark
| | - Hjalte V Kiefer
- Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C, Denmark
| | - Adil M Kabylda
- Department of Chemistry, Lomonosov Moscow State University, 119991, Moscow, Russia
| | | | - Lars H Andersen
- Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C, Denmark
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11
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Lutzweiler G, Barthes J, Charles AL, Ball V, Louis B, Geny B, Vrana NE. Improving the colonization and functions of Wharton's Jelly-derived mesenchymal stem cells by a synergetic combination of porous polyurethane scaffold with an albumin-derived hydrogel. ACTA ACUST UNITED AC 2020; 16:015005. [PMID: 33300500 DOI: 10.1088/1748-605x/abaf05] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The development of neo-tissues assisted by artificial scaffolds is continually progressing, but the reproduction of the extracellular environment surrounding cells is quite complex. While synthetic scaffolds can support cell growth, they lack biochemical cues that can prompt cell proliferation or differentiation. In this study, Wharton's Jelly-derived mesenchymal stem cells are seeded on a polyurethane (PU) scaffold combined with a hydrogel based on bovine serum albumin (BSA). BSA hydrogel is obtained through thermal treatment. While such treatment leads to partial unfolding of the protein, we show that the extent of denaturation is small enough to maintain its bioactivity, such as protein binding. Therefore, BSA provides a suitable playground for cells inside the scaffold, allowing higher spreading, proliferation and matrix secretions. Furthermore, the poor mechanical properties of the hydrogel are compensated for by the porous PU scaffold, whose architecture is well controlled. We show that even though PU by itself can allow cell adhesion and protein secretion, cell proliferation is 3.5 times higher in the PU + BSA scaffolds as compared to pure PU after 21 d, along with the non-collagenous protein secretions (389 versus 134 μmmg -1). Conversely, the secretion of sulphated glycosaminoglycans is 12.3-fold higher in the scaffold made solely of PU. Thereby, we propose a simple approach to generating a hybrid material composed of a combination of PU and BSA hydrogel as a promising scaffold for tissue regeneration.
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Affiliation(s)
- G Lutzweiler
- Institut National de la Santé et de la Recherche Medicale, UMR_S 1121, 11 rue Humann, 67085, Strasbourg Cedex, France
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12
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Empel C, Jana S, Pei C, Nguyen TV, Koenigs RM. Photochemical O–H Functionalization of Aryldiazoacetates with Phenols via Proton Transfer. Org Lett 2020; 22:7225-7229. [DOI: 10.1021/acs.orglett.0c02564] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Claire Empel
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
- School of Chemistry, University of New South Waley, Sydney 2052, Australia
| | - Sripati Jana
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
| | - Chao Pei
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
| | - Thanh Vinh Nguyen
- School of Chemistry, University of New South Waley, Sydney 2052, Australia
| | - Rene M. Koenigs
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
- School of Chemistry, University of New South Waley, Sydney 2052, Australia
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13
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Affiliation(s)
- Nadav Amdursky
- Schulich Faculty of ChemistryTechnion – Israel Institute of Technology Haifa 3200003 Israel
| | - Yiyang Lin
- State Key Laboratory of Organic-Inorganic Composites Beijing Laboratory of Biomedical MaterialsBeijing University of Chemical Technology Beijing 100029 China
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14
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Photoinduzierte Protonentransferreaktionen für milde O‐H‐Funktionalisierungsreaktionen unreaktiver Alkohole. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201915161] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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15
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Jana S, Yang Z, Li F, Empel C, Ho J, Koenigs RM. Photoinduced Proton-Transfer Reactions for Mild O-H Functionalization of Unreactive Alcohols. Angew Chem Int Ed Engl 2020; 59:5562-5566. [PMID: 31880397 PMCID: PMC7154649 DOI: 10.1002/anie.201915161] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/26/2019] [Indexed: 12/16/2022]
Abstract
Hexafluoroisopropanol is typically considered as an unreactive solvent and not as a reagent in organic synthesis. Herein, we report on a mild and efficient photochemical reaction of aryl diazoacetates with hexafluoroisopropanol that enables, under stoichiometric reaction conditions, the synthesis of fluorinated ethers in excellent yield. Mechanistic studies indicate there is a preorganization of hexafluoroisopropanol and the diazoalkane acts as an unreactive hydrogen-bonding complex. Only after photoexcitation does this complex undergo a protonation-substitution reaction to the reaction product. Investigations on the applicability of this photochemical transformation show that a broad variety of acidic alcohols can be subjected to this transformation and thus demonstrate the feasibility of this concept for O-H functionalization reactions (54 examples, up to 98 % yield).
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Affiliation(s)
- Sripati Jana
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Zhen Yang
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Fang Li
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Claire Empel
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Junming Ho
- School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Rene M Koenigs
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
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16
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17
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Nandi R, Yucknovsky A, Mazo MM, Amdursky N. Exploring the inner environment of protein hydrogels with fluorescence spectroscopy towards understanding their drug delivery capabilities. J Mater Chem B 2020; 8:6964-6974. [DOI: 10.1039/d0tb00818d] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Time-resolved fluorescence have used to explore the inner surface and solvation dynamics within protein hydrogels assisting in rationalizing their drug binding and release capabilities.
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Affiliation(s)
- Ramesh Nandi
- Schulich Faculty of Chemistry
- Technion Israel Institute of Technology
- Haifa-3200003
- Israel
| | - Anna Yucknovsky
- Schulich Faculty of Chemistry
- Technion Israel Institute of Technology
- Haifa-3200003
- Israel
| | - Manuel M. Mazo
- Cell Therapy Area
- Clinica Universidad de Navarra, and Regenerative Medicine Program
- Cima Universidad de Navarra
- Pamplona
- Spain
| | - Nadav Amdursky
- Schulich Faculty of Chemistry
- Technion Israel Institute of Technology
- Haifa-3200003
- Israel
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18
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Nelson KJ, Brown PJ, Rudel HE, Takematsu K. Divergent excited state proton transfer reactions of bifunctional photoacids 1-ammonium-2-naphthol and 3-ammonium-2-naphthol in water and methanol. Phys Chem Chem Phys 2019; 21:24383-24392. [PMID: 31663559 DOI: 10.1039/c9cp05269k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper highlights the challenge of predicting the excited state proton transfer (ESPT) reactions of small organic compounds with multiple proton transfer sites. Aminonaphthols, naphthalene compounds with both hydroxyl and amino substituents, can be viewed as a combination of two monoprotic photoacids, naphthol and naphthylammonium. Here, the ESPT reactions of 3-ammonium-2-naphthol (3N2OH) and 1-ammonium-2-naphthol (1N2OH) were studied in water and methanol using a combination of steady-state and time-correlated single-photon counting emission spectroscopy. For 3N2OH, ESPT was observed at the OH site in water but at neither of the sites in methanol; for 1N2OH, ESPT was observed at both the OH and NH3+ sites in water but only at the NH3+ site in methanol. Evidence of ESPT at the NH3+ site is limited for aminonaphthols. The divergent dynamics of 3N2OH and 1N2OH in water and methanol are discussed; dependent on the substitution and solvent, the ESPT reactions were analysed within the frameworks of reference photoacids 2-naphthol and 1-naphthylammonium. The application of crown ether and salt to control the release of select protons in non-aqueous media is also discussed.
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Affiliation(s)
- Kacie J Nelson
- Department of Chemistry, Bowdoin College, Brunswick, ME 04011, USA.
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19
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Ulrich S, Osypova A, Panzarasa G, Rossi RM, Bruns N, Boesel LF. Pyranine-Modified Amphiphilic Polymer Conetworks as Fluorescent Ratiometric pH Sensors. Macromol Rapid Commun 2019; 40:e1900360. [PMID: 31523877 DOI: 10.1002/marc.201900360] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 08/21/2019] [Indexed: 01/04/2023]
Abstract
The fluorescent dye 8-hydroxypyrene-1,3,6-trisulfonate (pyranine) combines high photostability with ratiometric pH detection in the physiological range, making it a prime candidate for optical sensors in biomedical applications, such as pH-based chronic wound monitoring. However, pyranine's high water solubility and the difficulty of covalent attachment pose severe limitations in terms of leaching from sensor matrices. Herein, pyranine-modified nanophase-separated amphiphilic polymer conetworks (APCNs) are reported as fluorescent ratiometric pH sensors. The thin, freestanding APCN membranes composed of one hydrophilic and one hydrophobic polymer provide an optically transparent, flexible, and stable ideal matrix that enables contact between dye and aqueous environment. An active ester-based conjugation approach results in a highly homogeneous and stable pyranine modification of the APCN's hydrophilic phase. This concept effectively solves the leaching challenge for pyranine without compromising its functionality, which is demonstrated by ratiometric pH detection in the range of pH 5-9.
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Affiliation(s)
- Sebastian Ulrich
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, Lerchenfeldstrasse 5, 9014, St. Gallen, Switzerland.,Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700, Fribourg, Switzerland
| | - Alina Osypova
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, Lerchenfeldstrasse 5, 9014, St. Gallen, Switzerland
| | - Guido Panzarasa
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, Lerchenfeldstrasse 5, 9014, St. Gallen, Switzerland
| | - René M Rossi
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, Lerchenfeldstrasse 5, 9014, St. Gallen, Switzerland
| | - Nico Bruns
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700, Fribourg, Switzerland.,Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow, G1 1XL, UK
| | - Luciano F Boesel
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, Lerchenfeldstrasse 5, 9014, St. Gallen, Switzerland
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20
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Roy S, Ardo S, Furche F. 5-Methoxyquinoline Photobasicity Is Mediated by Water Oxidation. J Phys Chem A 2019; 123:6645-6651. [DOI: 10.1021/acs.jpca.9b05341] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Saswata Roy
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, California 92697-2025, United States
| | - Shane Ardo
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, California 92697-2025, United States
| | - Filipp Furche
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, California 92697-2025, United States
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21
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Dey N, Biswakarma D, Bajpai A, Moorthy JN, Bhattacharya S. Modulation of Excited-State Proton-Transfer Dynamics inside the Nanocavity of Microheterogeneous Systems: Microenvironment-Sensitive Förster Energy Transfer to Riboflavin. Chemphyschem 2019; 20:881-889. [PMID: 30548519 DOI: 10.1002/cphc.201801085] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 08/15/2018] [Indexed: 12/11/2022]
Abstract
The excited-state proton-transfer efficiency of a tetraarylpyrene derivative, 1,3,6,8-tetrakis(4-hydroxy-2,6-dimethylphenyl)pyrene (TDMPP), was investigated thoroughly in the presence of various surfactant assemblies, such as micelles and vesicles. The confined microheterogeneous environments can significantly retard the extent of the excited-state proton-transfer process, resulting in a distinguishable optical signal compared to that in the bulk medium. Physical characteristics of the surfactant assemblies, such as order, interfacial hydration, and surface charge, influence the proton transfer process and allow multiparametric sensing. A higher degree of interfacial hydration facilitates the proton-transfer process, while the positively charged head groups of the surfactants specifically stabilize the anionic form of the probe (TDMPP-O*). Furthermore, Forster energy transfer from the probe to riboflavin was studied in a phospholipid membrane, wherein the relative ratio of the neutral versus anionic forms (TDMPP-OH/TDMPP-O*) was found to influence the extent of energy transfer. Overall, we demonstrate how an ultrafast photophysical process, that is, the excited-state proton transfer, can be influenced by the microenvironment.
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Affiliation(s)
- Nilanjan Dey
- Department of Organic Chemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Dipen Biswakarma
- Department of Organic Chemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Alankriti Bajpai
- Department of Chemistry, Indian Institute of Technology Kalyanpur, Kanpur, Uttar Pradesh, 208016
| | - Jarugu Narasimha Moorthy
- Department of Chemistry, Indian Institute of Technology Kalyanpur, Kanpur, Uttar Pradesh, 208016
| | - Santanu Bhattacharya
- Department of Organic Chemistry, Indian Institute of Science, Bangalore, 560012, India.,Current Address: Director's Research Unit, Indian Association for Cultivation of Science, Kolkata, 700032, India
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22
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Bhat IA, Roy B, Hazra P, Kabir-Ud-Din. Conformational and solution dynamics of hemoglobin (Hb) in presence of a cleavable gemini surfactant: Insights from spectroscopy, atomic force microscopy, molecular docking and density functional theory. J Colloid Interface Sci 2019; 538:489-498. [PMID: 30537662 DOI: 10.1016/j.jcis.2018.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 11/19/2018] [Accepted: 12/02/2018] [Indexed: 12/30/2022]
Abstract
Herein, we have explored the conformational alterations of hemoglobin (Hb) in presence of a cleavable gemini surfactant (C16-C4O2-C16). The concerned surfactant was found to induce significant structural perturbations in Hb. UV-vis spectroscopy, steady-state/time-resolved fluorescence, and other utilized techniques have authenticated the complexation of Hb with the gemini surfactant. CD has demonstrated the alterations in secondary structural elements (α-helicity, β-sheet, β-turn, and random coil) of Hb upon C16-C4O2-C16 addition. Atomic force microscopy (AFM) has revealed the existence of unique star-shaped gemini surfactant microstructures aligned to Hb in a necklace pattern. The 1H NMR peak broadening and lower delta values hint at the binding of the concerned gemini surfactant to Hb. Molecular docking and DFT calculations have further substantiated the Hb-gemini complex formation and the involvement of electrostatic/hydrophobic forces therein. In future, these results might pave-the-way to construct self-assembled, sustainable, and green surfactant-protein mixtures for their end-use in industrial, engineering, biomedical, drug delivery, gene transfection, and other relevant excipient formulations.
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Affiliation(s)
- Imtiyaz Ahmad Bhat
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008, Maharashtra, India.
| | - Bibhisan Roy
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008, Maharashtra, India
| | - Partha Hazra
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008, Maharashtra, India
| | - Kabir-Ud-Din
- Department of Chemistry, Arba Minch University, Ethiopia
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23
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Exploring fast proton transfer events associated with lateral proton diffusion on the surface of membranes. Proc Natl Acad Sci U S A 2019; 116:2443-2451. [PMID: 30679274 DOI: 10.1073/pnas.1812351116] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proton diffusion (PD) across biological membranes is a fundamental process in many biological systems, and much experimental and theoretical effort has been employed for deciphering it. Here, we report on a spectroscopic probe, which can be tightly tethered to the membrane, for following fast (nanosecond) proton transfer events on the surface of membranes. Our probe is composed of a photoacid that serves as our light-induced proton source for the initiation of the PD process. We use our probe to follow PD, and its pH dependence, on the surface of lipid vesicles composed of a zwitterionic headgroup, a negative headgroup, a headgroup that is composed only from the negative phosphate group, or a positive headgroup without the phosphate group. We reveal that the PD kinetic parameters are highly sensitive to the nature of the lipid headgroup, ranging from a fast lateral diffusion at some membranes to the escape of protons from surface to bulk (and vice versa) at others. By referring to existing theoretical models for membrane PD, we found that while some of our results confirm the quasi-equilibrium model, other results are in line with the nonequilibrium model.
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24
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Amdursky N, Mazo MM, Thomas MR, Humphrey EJ, Puetzer JL, St-Pierre JP, Skaalure SC, Richardson RM, Terracciano CM, Stevens MM. Elastic serum-albumin based hydrogels: mechanism of formation and application in cardiac tissue engineering. J Mater Chem B 2018; 6:5604-5612. [PMID: 30283632 PMCID: PMC6166857 DOI: 10.1039/c8tb01014e] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Hydrogels are promising materials for mimicking the extra-cellular environment. Here, we present a simple methodology for the formation of a free-standing viscoelastic hydrogel from the abundant and low cost protein serum albumin. We show that the mechanical properties of the hydrogel exhibit a complicated behaviour as a function of the weight fraction of the protein component. We further use X-ray scattering to shed light on the mechanism of gelation from the formation of a fibrillary network at low weight fractions to interconnected aggregates at higher weight fractions. Given the match between our hydrogel elasticity and that of the myocardium, we investigated its potential for supporting cardiac cells in vitro. Interestingly, these hydrogels support the formation of several layers of myocytes and significantly promote the maintenance of a native-like gene expression profile compared to those cultured on glass. When confronted with a multicellular ventricular cell preparation, the hydrogels can support macroscopically contracting cardiac-like tissues with a distinct cell arrangement, and form mm-long vascular-like structures. We envisage that our simple approach for the formation of an elastic substrate from an abundant protein makes the hydrogel a compelling biomedical material candidate for a wide range of cell types.
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Affiliation(s)
- Nadav Amdursky
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College Lodon, London, SW7 2AZ, UK
| | - Manuel M. Mazo
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College Lodon, London, SW7 2AZ, UK
| | - Michael R. Thomas
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College Lodon, London, SW7 2AZ, UK
| | - Eleanor J. Humphrey
- National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London, SW7 2AZ, UK
| | - Jennifer L. Puetzer
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College Lodon, London, SW7 2AZ, UK
| | - Jean-Philippe St-Pierre
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College Lodon, London, SW7 2AZ, UK
| | - Stacey C. Skaalure
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College Lodon, London, SW7 2AZ, UK
| | | | - Cesare M. Terracciano
- National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London, SW7 2AZ, UK
| | - Molly M. Stevens
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College Lodon, London, SW7 2AZ, UK
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25
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Krishnakumar P, Kar R, Maity DK. Microhydration of 2-Naphthol at Ground, First Excited Triplet, and First Excited Singlet States: A Case Study on Photo Acids. J Phys Chem A 2018; 122:929-936. [PMID: 29320857 DOI: 10.1021/acs.jpca.7b09579] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular interactions of 2-naphthol (nap) with water molecules are studied at the ground, first excited triplet and first excited singlet states, applying DFT and TD-DFT methods. The minimum energy structure of hydrated clusters of 2-naphthol up to four water molecules are selected from several possible input geometries. It is observed that the minimum energy conformer of the tetra-hydrate of 2-naphthol has proton transfer occurring from nap to solvent water molecules, in its first excited singlet state. This is however not observed in case of its ground or first excited triplet state. It is consistent with the fact that the pKa of nap in the first excited singlet state is very much lower compared to the ground and first excited triplet state. This is also reflected in the O-H potential energy profile of tetrahydrate of nap, obtained by performing a rigid potential energy scan of the dissociating O-H bond of nap at ground, first excited triplet and first excited singlet states. Frequency of O-H stretching vibration of 2-napthol and its hydrated clusters in the ground (S0) as well as in the first excited singlet (S1) state are calculated and compared with the available experimental data. The performance of macroscopic solvation model is also examined in the ground and these excited states.
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Affiliation(s)
- Parvathi Krishnakumar
- Homi Bhabha National Institute , Training School Complex, Anushaktinagar, Mumbai-400094, India.,Bhabha Atomic Research Centre , Mumbai-400085, India
| | - Rahul Kar
- Department of Chemistry, Dibrugarh University , Dibrugarh-786004, Assam, India
| | - Dilip Kumar Maity
- Homi Bhabha National Institute , Training School Complex, Anushaktinagar, Mumbai-400094, India.,Bhabha Atomic Research Centre , Mumbai-400085, India
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26
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Amdursky N, Rashid MH, Stevens MM, Yarovsky I. Exploring the binding sites and proton diffusion on insulin amyloid fibril surfaces by naphthol-based photoacid fluorescence and molecular simulations. Sci Rep 2017; 7:6245. [PMID: 28740173 PMCID: PMC5524688 DOI: 10.1038/s41598-017-06030-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 06/09/2017] [Indexed: 11/18/2022] Open
Abstract
The diffusion of protons along biological surfaces and the interaction of biological structures with water are fundamental areas of interest in biology and chemistry. Here, we examine the surface of insulin amyloid fibrils and follow the binding of small molecules (photoacids) that differ according to the number and location of their sulfonic groups. We use transient fluorescence combined with a spherically-symmetric diffusion theory to show that the binding mode of different photoacids determines the efficiency of proton dissociation from the photoacid and the dimensionality of the proton’s diffusion. We use molecular dynamics simulations to examine the binding mode and mechanism of the photoacids and its influence on the unique kinetic rates and diffusion properties of the photoacid’s dissociated proton, where we also suggest a proton transfer process between one of the photoacids to proximal histidine residues. We show that the photoacids can be used as fluorescent markers for following the progression of amyloidogenic processes. The detailed characterisation of different binding modes to the surface of amyloid fibrils paves the way for better understanding of the binding mechanism of small molecules to amyloid fibrils.
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Affiliation(s)
- Nadav Amdursky
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College London, London, SW7 2AZ, United Kingdom. .,Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 3200003, Israel.
| | - M Harunur Rashid
- School of Engineering, RMIT University, Melbourne, Victoria, 3001, Australia
| | - Molly M Stevens
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Irene Yarovsky
- School of Engineering, RMIT University, Melbourne, Victoria, 3001, Australia.
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27
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Mondal R, Ghosh N, Mukherjee S. Contrasting effects of pH on the modulation of the structural integrity of hemoglobin induced by sodium deoxycholate. Phys Chem Chem Phys 2016; 18:30867-30876. [PMID: 27801442 DOI: 10.1039/c6cp05216a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bile salt-mediated conformational modification of hemoglobin (Hb) was examined at three different pHs i.e., 3.2, 7.4 and 9.0. The added bile salt, sodium deoxycholate (NaDC), decreases the α-helicity in Hb (α-helix: 71.3% → 61.7% in the presence of 9.6 mM NaDC, and 83.2% → 66.2% in the presence of 14 mM NaDC, at pH 7.4 and 9.0, respectively), while a reverse pattern of modification in the Circular Dichroism (CD) spectra of Hb is found at pH 3.2. The acid-induced denatured Hb (pH 3.2) regains its structural integrity by changing conformation from a random coil to an α-helix rich secondary structure upon addition of NaDC (α-helix: 10.4% → 53.4%, β-sheet: 31.0% → 18.5% and random coil: 58.6% → 28.1%, in the presence of 0.65 mM NaDC). Also, a step-wise binding interaction pattern of Hb with NaDC was revealed at pH 7.4 and 9.0 upon variation of steady-state fluorescence intensity and average lifetime of Hb. From the fluorescence lifetime decay pattern, the decrement of energy transfer from Trp to a heme group was found upon the addition of NaDC at pH 7.4 and 9.0. However, at pH 3.2, the modification of the time-resolved fluorescence decay behavior of Hb within NaDC is typically reversed, where the energy transfer from Trp to heme is restored to some extent. Thermodynamic analysis suggests that the Hb-NaDC binding interaction is characterized by a dominant entropic contribution interpreted on the basis of release of ordered water molecules to the bulk aqueous phase.
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Affiliation(s)
- Ramakanta Mondal
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhauri, Bhopal Bypass Road, Bhopal 426066, Madhya Pradesh, India.
| | - Narayani Ghosh
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhauri, Bhopal Bypass Road, Bhopal 426066, Madhya Pradesh, India.
| | - Saptarshi Mukherjee
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhauri, Bhopal Bypass Road, Bhopal 426066, Madhya Pradesh, India.
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28
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Agmon N, Bakker HJ, Campen RK, Henchman RH, Pohl P, Roke S, Thämer M, Hassanali A. Protons and Hydroxide Ions in Aqueous Systems. Chem Rev 2016; 116:7642-72. [PMID: 27314430 DOI: 10.1021/acs.chemrev.5b00736] [Citation(s) in RCA: 287] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding the structure and dynamics of water's constituent ions, proton and hydroxide, has been a subject of numerous experimental and theoretical studies over the last century. Besides their obvious importance in acid-base chemistry, these ions play an important role in numerous applications ranging from enzyme catalysis to environmental chemistry. Despite a long history of research, many fundamental issues regarding their properties continue to be an active area of research. Here, we provide a review of the experimental and theoretical advances made in the last several decades in understanding the structure, dynamics, and transport of the proton and hydroxide ions in different aqueous environments, ranging from water clusters to the bulk liquid and its interfaces with hydrophobic surfaces. The propensity of these ions to accumulate at hydrophobic surfaces has been a subject of intense debate, and we highlight the open issues and challenges in this area. Biological applications reviewed include proton transport along the hydration layer of various membranes and through channel proteins, problems that are at the core of cellular bioenergetics.
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Affiliation(s)
- Noam Agmon
- The Fritz Haber Research Center, Institute of Chemistry, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
| | - Huib J Bakker
- FOM Institute AMOLF , Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - R Kramer Campen
- Fritz Haber Institute of the Max Planck Society , Faradayweg 4-6, 14195 Berlin, Germany
| | - Richard H Henchman
- Manchester Institute of Biotechnology, School of Chemistry, The University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom
| | - Peter Pohl
- Johannes Kepler University Linz , Institute of Biophysics, Gruberstrasse 40, 4020 Linz, Austria
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Material Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015, Lausanne, Switzerland
| | - Martin Thämer
- Fritz Haber Institute of the Max Planck Society , Faradayweg 4-6, 14195 Berlin, Germany.,Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - Ali Hassanali
- CMSP Section, The Abdus Salaam International Center for Theoretical Physics , I-34151 Trieste, Italy
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