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Gochev GG, Campbell RA, Schneck E, Zawala J, Warszynski P. Exploring proteins at soft interfaces and in thin liquid films - From classical methods to advanced applications of reflectometry. Adv Colloid Interface Sci 2024; 329:103187. [PMID: 38788307 DOI: 10.1016/j.cis.2024.103187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 05/12/2024] [Accepted: 05/12/2024] [Indexed: 05/26/2024]
Abstract
The history of the topic of proteins at soft interfaces dates back to the 19th century, and until the present day, it has continuously attracted great scientific interest. A multitude of experimental methods and theoretical approaches have been developed to serve the research progress in this large domain of colloid and interface science, including the area of soft colloids such as foams and emulsions. From classical methods like surface tension adsorption isotherms, surface pressure-area measurements for spread layers, and surface rheology probing the dynamics of adsorption, nowadays, advanced surface-sensitive techniques based on spectroscopy, microscopy, and the reflection of light, X-rays and neutrons at liquid/fluid interfaces offers important complementary sources of information. Apart from the fundamental characteristics of protein adsorption layers, i.e., surface tension and surface excess, the nanoscale structure of such layers and the interfacial protein conformations and morphologies are of pivotal importance for extending the depth of understanding on the topic. In this review article, we provide an extensive overview of the application of three methods, namely, ellipsometry, X-ray reflectometry and neutron reflectometry, for adsorption and structural studies on proteins at water/air and water/oil interfaces. The main attention is placed on the development of experimental approaches and on a discussion of the relevant achievements in terms of notable experimental results. We have attempted to cover the whole history of protein studies with these techniques, and thus, we believe the review should serve as a valuable reference to fuel ideas for a wide spectrum of researchers in different scientific fields where proteins at soft interface may be of relevance.
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Affiliation(s)
- Georgi G Gochev
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30239 Krakow, Poland; Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | - Richard A Campbell
- Division of Pharmacy and Optometry, University of Manchester, M13 9PT Manchester, UK
| | - Emanuel Schneck
- Physics Department, Technical University Darmstadt, 64289 Darmstadt, Germany
| | - Jan Zawala
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30239 Krakow, Poland
| | - Piotr Warszynski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30239 Krakow, Poland
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2
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Alobaid AA, Skoda MWA, Harris LK, Campbell RA. Translational use of homing peptides: Tumor and placental targeting. J Colloid Interface Sci 2024; 662:1033-1043. [PMID: 38387365 DOI: 10.1016/j.jcis.2024.02.103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 01/30/2024] [Accepted: 02/12/2024] [Indexed: 02/24/2024]
Abstract
HYPOTHESIS Tissue-specific homing peptides have been shown to improve chemotherapeutic efficacy due to their trophism for tumor cells. Other sequences that selectively home to the placenta are providing new and safer therapeutics to treat complications in pregnancy. Our hypothesis is that the placental homing peptide RSGVAKS (RSG) may have binding affinity to cancer cells, and that insight can be gained into the binding mechanisms of RSG and the tumor homing peptide CGKRK to model membranes that mimic the primary lipid compositions of the respective cells. EXPERIMENTS Following cell culture studies on the binding efficacy of the peptides on a breast cancer cell line, a systematic translational characterization is delivered using ellipsometry, Brewster angle microscopy and neutron reflectometry of the extents, structures, and dynamics of the interactions of the peptides with the model membranes on a Langmuir trough. FINDINGS We start by revealing that RSG does indeed have binding affinity to breast cancer cells. The peptide is then shown to exhibit stronger interactions and greater penetration than CGKRK into both model membranes, combined with greater disruption to the lipid component. RSG also forms aggregates bound to the model membranes, yet both peptides bind to a greater extent to the placental than cancer model membranes. The results demonstrate the potential for varying local reservoirs of peptide within cell membranes that may influence receptor binding. The innovative nature of our findings motivates the urgent need for more studies involving multifaceted experimental platforms to explore the use of specific peptide sequences to home to different cellular targets.
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Affiliation(s)
- Abdulaziz A Alobaid
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, United Kingdom; Department of Pharmaceutics, Faculty of Pharmacy, Kuwait University, P.O. Box 24923, Safat 13110, Kuwait
| | - Maximilian W A Skoda
- ISIS Neutron & Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - Lynda K Harris
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, United Kingdom; Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester M13 9WL, United Kingdom; St Mary's Hospital, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9WL, United Kingdom; Olson Center for Women's Health, University of Nebraska Medical Center, Omaha, NE 68198, United States.
| | - Richard A Campbell
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, United Kingdom.
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Le Brun AP, Gilbert EP. Advances in sample environments for neutron scattering for colloid and interface science. Adv Colloid Interface Sci 2024; 327:103141. [PMID: 38631095 DOI: 10.1016/j.cis.2024.103141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/19/2024]
Abstract
This review describes recent advances in sample environments across the full complement of applicable neutron scattering techniques to colloid and interface science. Temperature, pressure, flow, tensile testing, ultrasound, chemical reactions, IR/visible/UV light, confinement, humidity and electric and magnetic field application, as well as tandem X-ray methods, are all addressed. Consideration for material choices in sample environments and data acquisition methods are also covered as well as discussion of current and potential future use of machine learning and artificial intelligence.
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Affiliation(s)
- Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Elliot Paul Gilbert
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia.
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4
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Gochev GG, Schneck E, Miller R. Effects of Aqueous Isotopic Substitution on the Adsorption Dynamics and Dilational Rheology of β-Lactoglobulin Layers at the Water/Air Interface. J Phys Chem B 2024; 128:2821-2830. [PMID: 38471121 PMCID: PMC10961727 DOI: 10.1021/acs.jpcb.3c08417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 02/26/2024] [Accepted: 02/29/2024] [Indexed: 03/14/2024]
Abstract
The effect of the degree of isotopic substitution of the aqueous medium on the adsorption kinetics and the surface dilational rheological behavior at the water/air interface of the globular protein β-lactoglobulin was investigated. Aqueous solutions with fixed concentrations of 1 μM protein and 10 mM hydrogenous buffer with controlled pH 7 were prepared in H2O, D2O, and an isotopic mixture of 8.1% v/v D2O in H2O (called air contrast matched water, ACMW). Using a bubble shape analysis tensiometer, we obtained various experimental dependencies of the dilational viscoelasticity modulus E as a function of the dynamic surface pressure and of the frequency and amplitude of bubble surface area oscillations, either in the course of adsorption or after having reached a steady state. In general, the results revealed virtually no effect from substituting H2O by ACMW but distinct albeit relatively weak effects for intermediate adsorption times for D2O as the aqueous phase. In the final stage of adsorption, established after around 10 h, the equilibrium adsorption and the dilational rheological behavior of all protein layers under investigation are only very weakly affected by the presence of D2O. The obtained results help to design experimental protocols for protein adsorption studies, for example, by neutron reflectivity.
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Affiliation(s)
- Georgi G. Gochev
- Jerzy
Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30239 Krakow, Poland
- Institute
of Physical Chemistry, Bulgarian Academy
of Sciences, 1113 Sofia, Bulgaria
| | - Emanuel Schneck
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany
| | - Reinhard Miller
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany
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5
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Dolores Merchán M, Pawar N, Santamaria A, Sánchez-Fernández R, Konovalov O, Maestro A, Mercedes Velázquez M. Structure of graphene oxide-phospholipid monolayers: A grazing incidence X-ray diffraction and neutron and X-ray reflectivity study. J Colloid Interface Sci 2024; 655:664-675. [PMID: 37972452 DOI: 10.1016/j.jcis.2023.11.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 10/07/2023] [Accepted: 11/03/2023] [Indexed: 11/19/2023]
Abstract
HYPOTHESIS Graphene oxide-based nanotechnology has aroused a great interest due to its applications in the biomedical and optoelectronic fields. The wide use of these materials makes it necessary to study its potential toxicity associated with the inhalation of Graphene Oxide (GO) nanoparticles and its interaction with the lung surfactant. Langmuir monolayers have proven to be an excellent tool for studying the properties of the lung surfactant and the effect of intercalation of nanoparticles on its structure and properties. Therefore, to know the origin of the phospholipids/GO interaction and the structure of the lipid layer with GO, in this work we study the effect of the insertion of GO sheets on a Langmuir film of 1,2-Dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC). EXPERIMENTS Surface pressure-area isotherms, Neutron (NR) and X-ray Reflectivity (XRR) and Grazing Incidence X-ray Diffraction (GIXD) measurements of hydrogenated and deuterated DPPC monolayers with and without GO have been carried out. FINDINGS The results outline a strong interaction between the GO and the zwitterionic form of DPPC and prove that GO is in three regions of the DPPC monolayer, the aliphatic chains of DPPC, the head groups and water in the subphase. Comparison between results obtained with hydrogenated and deuterated DPPC allows concluding that both, electrostatic attractions, and dispersion forces are responsible of the interaction GO/DPPC. Results also demonstrated that the insertion of GO into the DPPC aliphatic chains does not induce significant changes on unit cell of DPPC.
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Affiliation(s)
- M Dolores Merchán
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad de Salamanca, E37008 Salamanca, Spain; Grupo de Nanotecnología, Universidad de Salamanca, E37008 Salamanca, Spain; Laboratorio de Nanoelectrónica and Nanomateriales, USAL-NANOLAB, Universidad de Salamanca, E37008 Salamanca, Spain
| | - Nisha Pawar
- Centro de Física de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, E-20018 San Sebastián, Spain
| | | | - Rosalía Sánchez-Fernández
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad de Salamanca, E37008 Salamanca, Spain; Institut Max von Laue and Paul Langevin, 38042 Grenoble, France
| | - Oleg Konovalov
- European Synchrotron Radiation Facility, 38000 Grenoble, France
| | - Armando Maestro
- Centro de Física de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, E-20018 San Sebastián, Spain; IKERBASQUE-Basque Foundation for Science, 48009 Bilbao, Spain.
| | - M Mercedes Velázquez
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad de Salamanca, E37008 Salamanca, Spain; Grupo de Nanotecnología, Universidad de Salamanca, E37008 Salamanca, Spain; Laboratorio de Nanoelectrónica and Nanomateriales, USAL-NANOLAB, Universidad de Salamanca, E37008 Salamanca, Spain.
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6
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Jones SH, King MD, Rennie AR, Ward AD, Campbell RA, Hughes AV. Aqueous Radical Initiated Oxidation of an Organic Monolayer at the Air-Water Interface as a Proxy for Thin Films on Atmospheric Aerosol Studied with Neutron Reflectometry. J Phys Chem A 2023; 127:8922-8934. [PMID: 37830513 PMCID: PMC10614302 DOI: 10.1021/acs.jpca.3c03846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 09/12/2023] [Indexed: 10/14/2023]
Abstract
Neutron reflectometry has been used to study the radical initiated oxidation of a monolayer of the lipid 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) at the air-solution interface by aqueous-phase hydroxyl, sulfate, and nitrate radicals. The oxidation of organic films at the surface of atmospheric aqueous aerosols can influence the optical properties of the aerosol and consequently can impact Earth's radiative balance and contribute to modern climate change. The amount of material at the air-solution interface was found to decrease on exposure to aqueous-phase radicals which was consistent with a multistep degradation mechanism, i.e., the products of reaction of the DSPC film with aqueous radicals were also surface active. The multistep degradation mechanism suggests that lipid molecules in the thin film degrade to form progressively shorter chain surface active products and several reactive steps are required to remove the film from the air-solution interface. Bimolecular rate constants for oxidation via the aqueous phase OH radical cluster around 1010 dm3 mol-1 s-1. Calculations to determine the film lifetime indicate that it will take ∼4-5 days for the film to degrade to 50% of its initial amount in the atmosphere, and therefore attack by aqueous radicals on organic films could be atmospherically important relative to typical atmospheric aerosol lifetimes.
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Affiliation(s)
- Stephanie H. Jones
- Centre
of Climate, Ocean and Atmosphere, Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, U.K.
- STFC,
Central Laser Facility, Research Complex
at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0FA, U.K.
| | - Martin D. King
- Centre
of Climate, Ocean and Atmosphere, Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, U.K.
| | - Adrian R. Rennie
- Department
of Chemistry, Angström Laboratory, Uppsala University, 75121 Uppsala, Sweden
| | - Andrew D. Ward
- STFC,
Central Laser Facility, Research Complex
at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0FA, U.K.
| | - Richard A. Campbell
- Institut
Laue-Langevin, BP 156, 6, 71 avenue des Martyrs, CS 20156, F-38042
Cedex 9 Grenoble, France
| | - Arwel V. Hughes
- ISIS
Pulsed Neutron and Muon source, Rutherford
Appleton Laboratory, Harwell Oxford, Oxfordshire OX11 0QX, U.K.
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7
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Hardt M, Busse F, Raschke S, Honnigfort C, Carrascosa-Tejedor J, Wenk P, Gutfreund P, Campbell RA, Heuer A, Braunschweig B. Photo-Responsive Control of Adsorption and Structure Formation at the Air-Water Interface with Arylazopyrazoles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:5861-5871. [PMID: 37058525 DOI: 10.1021/acs.langmuir.3c00294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Smart interfaces that are responsive to external triggers such as light are of great interest for the development of responsive or adaptive materials and interfaces. Using alkyl-arylazopyrazole butyl sulfonate surfactants (alkyl-AAP) that can undergo E/Z photoisomerization when irradiated with green (E) and UV (Z) lights, we demonstrate through a combination of experiments and computer simulations that there can be surprisingly large changes in surface tension and in the molecular structure and order at air-water interfaces. Surface tensiometry, vibrational sum-frequency generation (SFG) spectroscopy, and neutron reflectometry (NR) are applied to the study of custom-synthesized AAP surfactants with octyl- and H-terminal groups at air-water interfaces as a function of their bulk concentration and E/Z configuration. Upon photoswitching, a drastic influence of the alkyl chain on both the surface activity and the responsiveness of interfacial surfactants is revealed from changes in the surface tension, γ, where the largest changes in γ are observed for octyl-AAP (Δγ ∼ 23 mN/m) in contrast to H-AAP with Δγ < 10 mN/m. Results from vibrational SFG spectroscopy and NR show that the interfacial composition and the molecular order of the surfactants drastically change with E/Z photoisomerization and surface coverage. Indeed, from analysis of the S-O (head group) and C-H vibrational bands (hydrophobic tail), a qualitative analysis of orientational and structural changes of interfacial AAP surfactants is provided. The experiments are complemented by resolution of thermodynamic parameters such as equilibrium constants from ultra-coarse-grained simulations, which also capture details like island formation and interaction parameters of interfacial molecules. Here, the interparticle interaction ("stickiness") and the interaction with the surface are adjusted, closely reflecting experimental conditions.
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Affiliation(s)
- Michael Hardt
- Center for Soft Nanoscience, Busso-Peus-Straße 10, 48149 Münster, Germany
- Institute of Physical Chemistry, Corrensstraße 28/30, 48149 Münster, Germany
| | - Franziska Busse
- Institute of Physical Chemistry, Corrensstraße 28/30, 48149 Münster, Germany
| | - Simon Raschke
- Institute of Physical Chemistry, Corrensstraße 28/30, 48149 Münster, Germany
| | - Christian Honnigfort
- Center for Soft Nanoscience, Busso-Peus-Straße 10, 48149 Münster, Germany
- Institute of Physical Chemistry, Corrensstraße 28/30, 48149 Münster, Germany
| | - Javier Carrascosa-Tejedor
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
- Division of Pharmacy & Optometry, University of Manchester, M13 9PT Manchester, U.K
| | - Paul Wenk
- Institute of Physical Chemistry, Corrensstraße 28/30, 48149 Münster, Germany
| | - Philipp Gutfreund
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Richard A Campbell
- Division of Pharmacy & Optometry, University of Manchester, M13 9PT Manchester, U.K
| | - Andreas Heuer
- Institute of Physical Chemistry, Corrensstraße 28/30, 48149 Münster, Germany
| | - Björn Braunschweig
- Center for Soft Nanoscience, Busso-Peus-Straße 10, 48149 Münster, Germany
- Institute of Physical Chemistry, Corrensstraße 28/30, 48149 Münster, Germany
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8
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Ankner JF, Ashkar R, Browning JF, Charlton TR, Doucet M, Halbert CE, Islam F, Karim A, Kharlampieva E, Kilbey SM, Lin JYY, Phan MD, Smith GS, Sukhishvili SA, Thermer R, Veith GM, Watkins EB, Wilson D. Cinematic reflectometry using QIKR, the quite intense kinetics reflectometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:013302. [PMID: 36725568 DOI: 10.1063/5.0122279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 11/14/2022] [Indexed: 06/18/2023]
Abstract
The Quite Intense Kinetics Reflectometer (QIKR) will be a general-purpose, horizontal-sample-surface neutron reflectometer. Reflectometers measure the proportion of an incident probe beam reflected from a surface as a function of wavevector (momentum) transfer to infer the distribution and composition of matter near an interface. The unique scattering properties of neutrons make this technique especially useful in the study of soft matter, biomaterials, and materials used in energy storage. Exploiting the increased brilliance of the Spallation Neutron Source Second Target Station, QIKR will collect specular and off-specular reflectivity data faster than the best existing such machines. It will often be possible to collect complete specular reflectivity curves using a single instrument setting, enabling "cinematic" operation, wherein the user turns on the instrument and "films" the sample. Samples in time-dependent environments (e.g., temperature, electrochemical, or undergoing chemical alteration) will be observed in real time, in favorable cases with frame rates as fast as 1 Hz. Cinematic data acquisition promises to make time-dependent measurements routine, with time resolution specified during post-experiment data analysis. This capability will be deployed to observe such processes as in situ polymer diffusion, battery electrode charge-discharge cycles, hysteresis loops, and membrane protein insertion into lipid layers.
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Affiliation(s)
- J F Ankner
- Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - R Ashkar
- Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, USA
| | - J F Browning
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - T R Charlton
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M Doucet
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - C E Halbert
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - F Islam
- Neutron Technologies Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A Karim
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, USA
| | - E Kharlampieva
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - S M Kilbey
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - J Y Y Lin
- Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M D Phan
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - G S Smith
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S A Sukhishvili
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - R Thermer
- Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - G M Veith
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - E B Watkins
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - D Wilson
- Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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9
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Nagy B, Ekblad T, Fragneto G, Ederth T. Structure of Self-Initiated Photopolymerized Films: A Comparison of Models. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14004-14015. [PMID: 36377414 PMCID: PMC9671054 DOI: 10.1021/acs.langmuir.2c02396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/18/2022] [Indexed: 06/16/2023]
Abstract
Self-initiated photografting and photopolymerization (SI-PGP) uses UV illumination to graft polymers to surfaces without additional photoinitiators using the monomers as initiators, "inimers". A wider use of this method is obstructed by a lack of understanding of the resulting, presumably heterogeneous, polymer structure and of the parallel degradation under continuous UV illumination. We have used neutron reflectometry to investigate the structure of hydrated SI-PGP-prepared poly(HEMA-co-PEG10MA) (poly(2-hydroxyethyl methacrylate-co-(ethylene glycol)10 methacrylate)) films and compared parabolic, sigmoidal, and Gaussian models for the polymer volume fraction distributions. Results from fitting these models to the data suggest that either model can be used to approximate the volume fraction profile to similar accuracy. In addition, a second layer of deuterated poly(methacrylic acid) (poly(dMAA)) was grafted over the existing poly(HEMA-co-PEG10MA) layer, and the resulting double-grafted films were also studied by neutron reflectometry to shed light on the UV-polymerization process and the inevitable UV-induced degradation which competes with the grafting.
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Affiliation(s)
- Béla Nagy
- Division
of Biophysics and Bioengineering, Department of Physics, Chemistry
and Biology, Linköping University, SE-581 83Linköping, Sweden
| | - Tobias Ekblad
- Division
of Biophysics and Bioengineering, Department of Physics, Chemistry
and Biology, Linköping University, SE-581 83Linköping, Sweden
| | - Giovanna Fragneto
- Institut
Laue-Langevin, 71 avenue des Martyrs, BP 156, 38042Grenoble, France
| | - Thomas Ederth
- Division
of Biophysics and Bioengineering, Department of Physics, Chemistry
and Biology, Linköping University, SE-581 83Linköping, Sweden
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10
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Braun L, Uhlig M, Löhmann O, Campbell RA, Schneck E, von Klitzing R. Insights into Extended Structures and Their Driving Force: Influence of Salt on Polyelectrolyte/Surfactant Mixtures at the Air/Water Interface. ACS APPLIED MATERIALS & INTERFACES 2022; 14:27347-27359. [PMID: 35639454 DOI: 10.1021/acsami.2c04421] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
This paper addresses the effect of polyelectrolyte stiffness on the surface structure of polyelectrolyte (P)/surfactant (S) mixtures. Therefore, two different anionic Ps with different intrinsic persistence length lP are studied while varying the salt concentration (0-10-2 M). Either monosulfonated polyphenylene sulfone (sPSO2-220, lP ∼20 nm) or sodium poly(styrenesulfonate) (PSS, lP ∼1 nm) is mixed with the cationic surfactant tetradecyltrimethylammonium bromide (C14TAB) well below its critical micelle concentration and studied with tensiometry and neutron reflectivity experiments. We kept the S concentration (10-4 M) constant, while we varied the P concentration (10-5-10-3 M of the monomer, denoted as monoM). P and S adsorb at the air/water interface for all studied mixtures. Around the bulk stoichiometric mixing point (BSMP), PSS/C14TAB mixtures lose their surface activity, whereas sPSO2-220/C14TAB mixtures form extended structures perpendicular to the surface (meaning a layer of S with attached P and additional layers of P and S underneath instead of only a monolayer of S with P). Considering the different P monomer structures as well as the impact of salt, we identified the driving force for the formation of these extended structures: compensation of all interfacial charges (P/S ratio ∼1) to maximize the gain of entropy. By increasing the flexibility of P, we can tune the interfacial structures from extended structures to monolayers. These findings may help improve applications based on the adsorption of P/S mixtures in the fields of cosmetic or oil recovery.
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Affiliation(s)
- Larissa Braun
- Soft Matter at Interfaces, Department of Physics, Technische Universität Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany
| | - Martin Uhlig
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Oliver Löhmann
- Soft Matter at Interfaces, Department of Physics, Technische Universität Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany
| | | | - Emanuel Schneck
- Soft Matter Biophysics, Department of Physics, Technische Universität Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany
| | - Regine von Klitzing
- Soft Matter at Interfaces, Department of Physics, Technische Universität Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany
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11
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Liu P, Freeley M, Zarbakhsh A, Resmini M. Adsorption of soft NIPAM nanogels at hydrophobic and hydrophilic interfaces: Conformation of the interfacial layers determined by neutron reflectivity. J Colloid Interface Sci 2022; 623:337-347. [PMID: 35594592 DOI: 10.1016/j.jcis.2022.05.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/18/2022] [Accepted: 05/02/2022] [Indexed: 11/25/2022]
Abstract
The application of stimuli-responsive microgels and nanogels in drug delivery, catalysis, sensing, and coatings is restricted currently by the limited understanding of the factors influencing their adsorption dynamics and structural changes at interfaces. We have used neutron reflectivity to resolve, on the Ångström scale, the structure of 5% crosslinked N-isopropylacrylamide nanogels at both hydrophobic and hydrophilic interfaces in situ, as a function of temperature and bulk nanogel concentration. Our results show that the higher flexibility given by the low crosslinker content allows for a more ordered structure and packing. The adsorption of the thermoresponsive nanogels is primarily driven by temperature, more specifically its proximity to its volume phase transition temperature, while concentration plays a secondary role. Hydrophobic interactions drive the conformation of the first layer at the interface, which plays a key role in influencing the overall nanogel structure. The mobility of the first layer at the air-water interface as opposed to the interfacial confinement at the solid (SiC8)-liquid interface, results in a different conformation, a more compact and less deformed packing structure, which ultimately drives the structure of the subsequent layers. The evidence for the different structural conformations determined by the degree of hydrophobicity of the interface provides new knowledge, which is essential for the development of further applications. The key role of hydrophobic interactions in driving adsorption and interfacial behavior was also confirmed by fluid AFM experiments which visualized adherence of the nanogels to SiC8 modified surfaces.
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Affiliation(s)
- Pengfei Liu
- Department of Chemistry, SPCS, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Mark Freeley
- Department of Chemistry, SPCS, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Ali Zarbakhsh
- Department of Chemistry, SPCS, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
| | - Marina Resmini
- Department of Chemistry, SPCS, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
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12
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Hall SCL, Tognoloni C, Campbell RA, Richens J, O'Shea P, Terry AE, Price GJ, Dafforn TR, Edler KJ, Arnold T. The interaction of styrene maleic acid copolymers with phospholipids in Langmuir monolayers, vesicles and nanodiscs; a structural study. J Colloid Interface Sci 2022; 625:220-236. [PMID: 35716617 DOI: 10.1016/j.jcis.2022.03.102] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 10/31/2022]
Abstract
HYPOTHESIS Self-assembly of amphipathic styrene maleic acid copolymers with phospholipids in aqueous solution results in the formation of 'nanodiscs' containing a planar segment of phospholipid bilayer encapsulated by a polymer belt. Recently, studies have reported that lipids rapidly exchange between both nanodiscs in solution and external sources of lipids. Outstanding questions remain regarding details of polymer-lipid interactions, factors influencing lipid exchange and structural effects of such exchange processes. Here, the dynamic behaviour of nanodiscs is investigated, specifically the role of membrane charge and polymer chemistry. EXPERIMENTS Two model systems are investigated: fluorescently labelled phospholipid vesicles, and Langmuir monolayers of phospholipids. Using fluorescence spectroscopy and time-resolved neutron reflectometry, the membrane potential, monolayer structure and composition are monitored with respect to time upon polymer and nanodisc interactions. FINDINGS In the presence of external lipids, polymer chains embed throughout lipid membranes, the extent of which is governed by the net membrane charge. Nanodiscs stabilised by three different polymers will all exchange lipids and polymer with monolayers to differing extents, related to the properties of the stabilising polymer belt. These results demonstrate the dynamic nature of nanodiscs which interact with the local environment and are likely to deposit both lipids and polymer at all stages of use.
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Affiliation(s)
- Stephen C L Hall
- School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK; Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 ODE, UK; ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK.
| | - Cecilia Tognoloni
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Richard A Campbell
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, France; Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, UK
| | - Joanna Richens
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Paul O'Shea
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK; Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YG, UK
| | - Ann E Terry
- MAX IV Laboratory, Lund University, SE-221 00 Lund, Sweden
| | - Gareth J Price
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Tim R Dafforn
- School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Karen J Edler
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Thomas Arnold
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK; ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK; Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK; European Spallation Source ERIC, P.O Box 176, SE-221 00 Lund, Sweden
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13
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Schnurbus M, Hardt M, Steinforth P, Carrascosa-Tejedor J, Winnall S, Gutfreund P, Schönhoff M, Campbell RA, Braunschweig B. Responsive Material and Interfacial Properties through Remote Control of Polyelectrolyte-Surfactant Mixtures. ACS APPLIED MATERIALS & INTERFACES 2022; 14:4656-4667. [PMID: 35029383 DOI: 10.1021/acsami.1c18934] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Polyelectrolyte/surfactant (P/S) mixtures find many applications but are static in nature and cannot be reversibly reconfigured through the application of external stimuli. Using a new type of photoswitchable surfactants, we use light to trigger property changes in mixtures of an anionic polyelectrolyte with a cationic photoswitch such as electrophoretic mobilities, particle size, as well as their interfacial structure and their ability to stabilize aqueous foam. For that, we show that prevailing hydrophobic intermolecular interactions can be remotely controlled between poly(sodium styrene sulfonate) (PSS) and arylazopyrazole tetraethylammonium bromide (AAP-TB). Shifting the chemical potential for P/S binding with E/Z photoisomerization of the surfactants can reversibly disintegrate even large aggregates (>4 μm) and is accompanied by a substantial change in the net charging state of PSS/AAP-TB complexes, e.g., from negative to positive excess charges upon light irradiation. In addition to the drastic changes in the bulk solution, also at air-water interfaces, the interfacial stoichiometry and structure change drastically on the molecular level with E/Z photoisomerization, which can also drive the stability of aqueous foam on a macroscopic level.
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Affiliation(s)
- Marco Schnurbus
- Institute of Physical Chemistry and Center of Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Michael Hardt
- Institute of Physical Chemistry and Center of Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Pascal Steinforth
- Institute of Physical Chemistry and Center of Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Javier Carrascosa-Tejedor
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
- Division of Pharmacy & Optometry, University of Manchester, M13 9PT Manchester, United Kingdom
| | - Samuel Winnall
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
- Division of Pharmacy & Optometry, University of Manchester, M13 9PT Manchester, United Kingdom
| | - Philipp Gutfreund
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Monika Schönhoff
- Institute of Physical Chemistry and Center of Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Richard A Campbell
- Division of Pharmacy & Optometry, University of Manchester, M13 9PT Manchester, United Kingdom
| | - Björn Braunschweig
- Institute of Physical Chemistry and Center of Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
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14
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New Design of a Sample Cell for Neutron Reflectometry in Liquid–Liquid Systems and Its Application for Studying Structures at Air–Liquid and Liquid–Liquid Interfaces. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12031215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Knowledge of interfacial structures in liquid–liquid systems is imperative, especially for improving two-phase biological and chemical reactions. Therefore, we developed a new sample cell for neutron reflectometry (NR), which enables us to observe the layer structure around the interface, and investigated the adsorption behavior of a typical surfactant, sodium dodecyl sulfate (SDS), on the toluene-d8-D2O interface under the new experimental conditions. The new cell was characterized by placing the PTFE frame at the bottom to produce a smooth interface and downsized compared to the conventional cell. The obtained NR profiles were readily analyzable and we determined a slight difference in the SDS adsorption layer structure at the interface between the toluene-d8-D2O and air-D2O systems. This could be owing to the difference in the adsorption behavior of the SDS molecules depending on the interfacial conditions.
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15
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Slastanova A, Campbell RA, Islas L, Welbourn RJL, R P Webster J, Vaccaro M, Chen M, Robles E, Briscoe WH. Interfacial complexation of a neutral amphiphilic 'tardigrade' co-polymer with a cationic surfactant: Transition from synergy to competition. J Colloid Interface Sci 2022; 606:1064-1076. [PMID: 34487929 DOI: 10.1016/j.jcis.2021.08.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 07/22/2021] [Accepted: 08/02/2021] [Indexed: 11/24/2022]
Abstract
HYPOTHESIS Neutral amphiphilic PEG-g-PVAc co-polymer (a "tardigrade" polymer consisting of a hydrophilic polyethylene glycol, PEG, backbone with hydrophobic polyvinyl acetate, PVAc, grafts) can form complexes at the air-water interface with cationic dodecyltrimethylammonium bromide (DTAB) via self-assembly. Compared to anionic SDS, cationic DTAB headgroups are expected to interact strongly with the negatively charged OH- groups from the partial dissociation of the PVAc grafts. We anticipate a transition from synergistic to competitive behaviour, which is expected to be dependent on the surfactant structural characteristics and concentration. EXPERIMENTS DTAB/PEG-g-PVAc mixtures were investigated using a combination of dynamic and equilibrium surface tension measurements, neutron reflectivity (NR) at the air-water interface, and foaming tests. We varied the concentrations of both the DTAB (0.05 to 5 critical micelle concentration, cmc) and that of PEG-g-PVAc (0.2 and 2 critical aggregation concentration, cac). FINDINGS Our results show that the interfacial interactions between DTAB and PEG-g-PVAc were both synergistic and antagonistic, depending sensitively on the surfactant concentration. At DTAB concentrations below its cmc, a pronounced cooperative adsorption behaviour was likely driven by the hydrophobic interactions between the DTAB tail and the PVAc grafts and the attraction between the DTAB headgroups and the partially dissociated -O- groups in the partially hydrolysed PVAc grafts, forming a mixed layer. This synergistic adsorption behaviour transitioned to a competitive adsorption behaviour at DTAB concentrations above its cmc, leading to polymer-surfactant partition, forming a "hanging" polymer layer underlying a surfactant monolayer at the interface. We postulate that DTAB/PEG-g-PVAc complexation in the bulk contributed to partial depletion of the mixture from the interface. We therefore consider this polymer/surfactant system to be a moderately interacting system at the air-water interface. No discernible differences in the foaming behaviour were observed between the DTAB/PEG-g-PVAc systems and the pure surfactant. Our results suggest that surfactant headgroup characteristics (particularly charges) were crucial in determining the structure and composition of polymer-surfactant complexes at the air-water interface, as well as the foamability and foam stability, whilst the coexistence of the synergistic and competitive adsorption behaviour is attributed to the unique architecture of the tardigrade polymer with amphiphilicity and partial charge, facilitating different surfactant-polymer interactions at different DTAB concentrations.
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Affiliation(s)
- Anna Slastanova
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Richard A Campbell
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, UK; Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, Grenoble 38042, France
| | - Luisa Islas
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Rebecca J L Welbourn
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
| | - John R P Webster
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Mauro Vaccaro
- Procter & Gamble, Temselaan 100, 1853 Strombeek-Bever, Brussels, Belgium
| | - Meng Chen
- Procter & Gamble Beijing Innovation Centre, 35 Yu'an Rd, Shunyi District, Beijing, China
| | - Eric Robles
- Household Care Analytical, Procter & Gamble Newcastle Innovation Centre, Whitley Road, Longbenton, Newcastle NE12 9TS, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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16
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Carrascosa-Tejedor J, Santamaria A, Tummino A, Varga I, Efstratiou M, Lawrence MJ, Maestro A, Campbell RA. Polyelectrolyte/surfactant films: from 2D to 3D structural control. Chem Commun (Camb) 2022; 58:10687-10690. [DOI: 10.1039/d2cc03766a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reversible control of the 3D structure of polyelectrolyte/surfactant films at the air/water interface is showcased. A recently discovered mechanism is exploited to form highly efficient, stable and biocompatible films by...
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17
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Browning JF, Seo J, Wenzel JF, Veith GM, Doucet M, Ivanov AS, Halstenberg P, Lynn G, Dai S. A high temperature cell for investigating interfacial structure on the molecular scale in molten salt/alloy systems. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:123903. [PMID: 34972459 DOI: 10.1063/5.0065860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 11/17/2021] [Indexed: 06/14/2023]
Abstract
In this work, we describe the design and development of an in situ neutron reflectometry cell for high temperature investigations of structural changes occurring at the interface between inorganic salts, in their molten state up to 800 °C, and corrosion resistant alloys or other surfaces. In the cell, a molten salt is confined by an annular ring of single crystal sapphire constrained between the sample substrate and a sapphire plate using two gold O-rings, enclosing a liquid salt volume of 20 ml, along with a dynamic cell volume to accommodate expansion of the liquid with heating. As a test case for the cell, we report on an in situ neutron reflectometry measurement of the interface between a eutectic salt mixture of MgCl2-KCl (32:68 molar ratio) and a single crystal sapphire substrate at 450 °C, resulting in the formation of a 60 Å layer having a scattering length density of 1.72 × 10-6 Å-2. While the origin of this layer is uncertain, it is likely to have resulted from the salt reacting with an existing impurity layer on the sapphire substrate.
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Affiliation(s)
- James F Browning
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Joohyun Seo
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - John F Wenzel
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Gabriel M Veith
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Mathieu Doucet
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Alexander S Ivanov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Phillip Halstenberg
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Gary Lynn
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Sheng Dai
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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18
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Zec N, Mangiapia G, Hendry AC, Barker R, Koutsioubas A, Frielinghaus H, Campana M, Ortega-Roldan JL, Busch S, Moulin JF. Mutually Beneficial Combination of Molecular Dynamics Computer Simulations and Scattering Experiments. MEMBRANES 2021; 11:507. [PMID: 34357157 PMCID: PMC8304056 DOI: 10.3390/membranes11070507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/28/2021] [Accepted: 06/29/2021] [Indexed: 11/17/2022]
Abstract
We showcase the combination of experimental neutron scattering data and molecular dynamics (MD) simulations for exemplary phospholipid membrane systems. Neutron and X-ray reflectometry and small-angle scattering measurements are determined by the scattering length density profile in real space, but it is not usually possible to retrieve this profile unambiguously from the data alone. MD simulations predict these density profiles, but they require experimental control. Both issues can be addressed simultaneously by cross-validating scattering data and MD results. The strengths and weaknesses of each technique are discussed in detail with the aim of optimizing the opportunities provided by this combination.
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Affiliation(s)
- Nebojša Zec
- German Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz Zentrum (MLZ), Helmholtz-Zentrum Hereon, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (N.Z.); (G.M.)
| | - Gaetano Mangiapia
- German Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz Zentrum (MLZ), Helmholtz-Zentrum Hereon, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (N.Z.); (G.M.)
| | - Alex C. Hendry
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK; (A.C.H.); (J.L.O.-R.)
| | - Robert Barker
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, UK;
| | - Alexandros Koutsioubas
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (A.K.); (H.F.)
| | - Henrich Frielinghaus
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (A.K.); (H.F.)
| | - Mario Campana
- ISIS Neutron and Muon Facility, Rutherford Appleton Laboratory, Science & Technology Facilities Council, Didcot OX11 0QX, UK;
| | | | - Sebastian Busch
- German Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz Zentrum (MLZ), Helmholtz-Zentrum Hereon, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (N.Z.); (G.M.)
| | - Jean-François Moulin
- German Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz Zentrum (MLZ), Helmholtz-Zentrum Hereon, Lichtenbergstr. 1, 85748 Garching bei München, Germany; (N.Z.); (G.M.)
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19
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Liu X, Counil C, Shi D, Mendoza-Ortega EE, Vela-Gonzalez AV, Maestro A, Campbell RA, Krafft MP. First quantitative assessment of the adsorption of a fluorocarbon gas on phospholipid monolayers at the air/water interface. J Colloid Interface Sci 2021; 593:1-10. [DOI: 10.1016/j.jcis.2021.02.073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 12/19/2022]
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20
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In situ determination of the structure and composition of Langmuir monolayers at the air/water interface by neutron and X-ray reflectivity and ellipsometry. Adv Colloid Interface Sci 2021; 293:102434. [PMID: 34022749 DOI: 10.1016/j.cis.2021.102434] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 02/07/2023]
Abstract
This review focuses on the description of the structure and composition of a variety of Langmuir monolayers (LMs) deposited at the air/water interface by using ellipsometry, Brewster Angle microscopy and scattering techniques, mainly neutron and X-ray reflectometry. Since the first experiment done by Angels Pockels with a homemade trough in her home kitchen until today, LMs of different materials have been extensively studied providing not only relevant model systems in biology, physics and chemistry but also precursors of novel materials via their deposition on solid substrates. There is a vast amount of surface-active materials that can form LMs and, therefore, far from a revision of the state-of-the-art, we will emphasize here: (i) some fundamental aspects to understand the physics behind the molecular deposition at the air/water interface; (ii) the advantages in using in situ techniques, such as reflectometry or ellipsometry, to resolve the interfacial architecture and conformation of molecular films; and, finally, (iii) a summary of several systems that have certain interest from the experimental or conceptual point of view. Concretely, we will report here advances in polymers confined to interfaces and surfactants, from fatty acids and phospholipids monolayers to more unconventional ones such as graphene oxide.
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21
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Roberts RA, Campbell RA, Sikakana P, Sadler C, Osier M, Xu Y, Feng JY, Mitchell M, Sakowicz R, Chester A, Paoli E, Wang J, Burns-Naas LA. Species-Specific Urothelial Toxicity with an anti-HIV Non-Catalytic Site Integrase Inhibitor (NCINI) is Related to Unusual pH-Dependent Physicochemical Changes. Toxicol Sci 2021; 183:105-116. [PMID: 34117767 DOI: 10.1093/toxsci/kfab073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
GS-9695 and GS-9822 are next generation Non-Catalytic Site Integrase Inhibitors (NCINIs) with significantly improved potency against HIV compared with previous drugs such as BI-224436. Development stopped due to vacuolation of the bladder urothelium seen in cynomolgus monkey but not in rat; this lesion was absent in equivalent preclinical studies with BI-224436 (tested in dog and rat). Lesions were unlikely to be attributable to target since NCINIs specifically target viral integrase protein and no mammalian homologue is known. Secondary pharmacology studies, mitochondrial toxicity studies, immunophenotyping and analysis of proteins implicated in cell-cell interactions and/or bladder integrity (e-cadherin, pan-cytokeratin, uroplakins) failed to offer any plausible explanation for the species-specificity of the lesion. Since it was characterized by inflammation and disruption of urothelial morphology, we investigated physicochemical changes in the bladder of cynomolgus monkey (urinary pH 5.5-7.4) that might not occur in the bladder of rats (urinary pH 7.3-8.5). In measurements of surface activity, GS-9822 showed an unusual transition from a monolayer to a bilayer at the air/water interface with decreasing pH, attributed to the strong association between drug molecules in adjacent bilayer leaflets and expected to be highly disruptive to the urothelium. Structural analysis of GS-9822 and GS-9695 showed zwitterionic characteristics over the range of pH expected in cynomolgus monkey but not rat urine. This exotic surface behaviour is unlikely with BI-224436 since it would transition from neutral to cationic (never zwitterionic) with decreasing pH. These data provide useful insights to guide discovery and development of NCINIs, related compounds and zwitterions.
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Affiliation(s)
| | - Richard A Campbell
- Division of Pharmacy and Optometry, Manchester, M13 9PT, United Kingdom For RAC: University of Manchester
| | | | | | - Mark Osier
- Nonclinical Safety & Pathobiology, Gilead Sciences, Inc, Foster City, USA
| | - Yili Xu
- Biology, Gilead Sciences, Inc, Foster City, CA, USA
| | - Joy Y Feng
- Biology, Gilead Sciences, Inc, Foster City, CA, USA
| | | | | | - Anne Chester
- Nonclinical Safety & Pathobiology, Gilead Sciences, Inc, Foster City, USA
| | - Eric Paoli
- Formulations and Process Development, Gilead Sciences, Inc, Foster City, CA, USA
| | - Jianhong Wang
- Drug Metabolism & Pharmacokinetics, Gilead Sciences, Inc, Foster City, CA, USA
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22
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Kinnun JJ, Scott HL, Ashkar R, Katsaras J. Biomembrane Structure and Material Properties Studied With Neutron Scattering. Front Chem 2021; 9:642851. [PMID: 33987167 PMCID: PMC8110834 DOI: 10.3389/fchem.2021.642851] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/16/2021] [Indexed: 12/12/2022] Open
Abstract
Cell membranes and their associated structures are dynamical supramolecular structures where different physiological processes take place. Detailed knowledge of their static and dynamic structures is therefore needed, to better understand membrane biology. The structure–function relationship is a basic tenet in biology and has been pursued using a range of different experimental approaches. In this review, we will discuss one approach, namely the use of neutron scattering techniques as applied, primarily, to model membrane systems composed of lipid bilayers. An advantage of neutron scattering, compared to other scattering techniques, is the differential sensitivity of neutrons to isotopes of hydrogen and, as a result, the relative ease of altering sample contrast by substituting protium for deuterium. This property makes neutrons an ideal probe for the study of hydrogen-rich materials, such as biomembranes. In this review article, we describe isotopic labeling studies of model and viable membranes, and discuss novel applications of neutron contrast variation in order to gain unique insights into the structure, dynamics, and molecular interactions of biological membranes. We specifically focus on how small-angle neutron scattering data is modeled using different contrast data and molecular dynamics simulations. We also briefly discuss neutron reflectometry and present a few recent advances that have taken place in neutron spin echo spectroscopy studies and the unique membrane mechanical data that can be derived from them, primarily due to new models used to fit the data.
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Affiliation(s)
- Jacob J Kinnun
- Large Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Oak Ridge National Laboratory, Shull-Wollan Center, Oak Ridge, TN, United States
| | - Haden L Scott
- Large Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Oak Ridge National Laboratory, Shull-Wollan Center, Oak Ridge, TN, United States
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, VA, United States.,Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, United States
| | - John Katsaras
- Oak Ridge National Laboratory, Shull-Wollan Center, Oak Ridge, TN, United States.,Sample Environment Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, United States
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Ciumac D, Gong H, Campbell RA, Campana M, Xu H, Lu JR. Structural elucidation upon binding of antimicrobial peptides into binary mixed lipid monolayers mimicking bacterial membranes. J Colloid Interface Sci 2021; 598:193-205. [PMID: 33901846 DOI: 10.1016/j.jcis.2021.04.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 04/07/2021] [Accepted: 04/09/2021] [Indexed: 11/28/2022]
Abstract
HYPOTHESIS Antimicrobial peptides (AMPs) kill microorganisms by causing structural damage to bacterial membranes. Different microorganisms often require a different type and concentration of an AMP to achieve full microbial killing. We hypothesise that the difference is caused by different membrane structure and composition. EXPERIMENTS Given the complexities of bacterial membranes, we have used monolayers of the binary DPPG/TMCL mixture to mimic the cytoplasmic membrane of Gram-positive bacteria and the binary DPPG/DPPE mixture to mimic the cytoplasmic membrane of Gram-negative bacteria, where DPPG, TMCL and DPPE stand for 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol), 1',3'-bis[1,2-dimyristoyl-sn-glycero-3-phospho]-sn-glycerol, and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, respectively. A Langmuir trough was specially designed to control the spread lipid monolayers and facilitate neutron reflectivity measurements. FINDINGS Surface pressure-area isotherm analysis revealed that all binary lipid systems mix non-ideally, but mixing is thermodynamically favoured. An increase in the surface pressure encourages demixing, resulting in phase separation and formation of clusters. Neutron reflectivity measurements were undertaken to study the binding of an antimicrobial peptide G(IIKK)4-I-NH2 (G4) to the binary DPPG/TMCL and DPPG/DPPE monolayer mixtures at the molar ratios of 6/4 and 3/7, respectively. The results revealed stronger binding and penetration of G4 to the DPPG/TMCL monolayer, indicating greater affinity of the antimicrobial peptide due to the electrostatic interaction and more extensive penetration into the more loosely packed lipid film. This work helps explain how AMPs attack different bacterial membranes, and the results are discussed in the context of other lipid models and antibacterial studies.
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Affiliation(s)
- Daniela Ciumac
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Schuster Building, Manchester M13 9PL, UK
| | - Haoning Gong
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Schuster Building, Manchester M13 9PL, UK
| | - Richard A Campbell
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS-20156, 38042 Grenoble, France; Division of Pharmacy and Optometry, University of Manchester, Oxford Road, Stopford Building, Manchester M13 9PT, UK
| | - Mario Campana
- ISIS Neutron Facility, STFC, Chilton, Didcot OX11 0QZ, UK
| | - Hai Xu
- Centre for Bioengineering and Biotechnology, China University of Petroleum, Qingdao, China
| | - Jian R Lu
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Schuster Building, Manchester M13 9PL, UK.
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King MD, Jones SH, Lucas COM, Thompson KC, Rennie AR, Ward AD, Marks AA, Fisher FN, Pfrang C, Hughes AV, Campbell RA. The reaction of oleic acid monolayers with gas-phase ozone at the air water interface: the effect of sub-phase viscosity, and inert secondary components. Phys Chem Chem Phys 2020; 22:28032-28044. [PMID: 33367378 DOI: 10.1039/d0cp03934a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Organic films that form on atmospheric particulate matter change the optical and cloud condensation nucleation properties of the particulate matter and consequently have implications for modern climate and climate models. The organic films are subject to attack from gas-phase oxidants present in ambient air. Here we revisit in greater detail the oxidation of a monolayer of oleic acid by gas-phase ozone at the air-water interface as this provides a model system for the oxidation reactions that occur at the air-water interface of aqueous atmospheric aerosol. Experiments were performed on monolayers of oleic acid at the air-liquid interface at atmospherically relevant ozone concentrations to investigate if the viscosity of the sub-phase influences the rate of the reaction and to determine the effect of the presence of a second component within the monolayer, stearic acid, which is generally considered to be non-reactive towards ozone, on the reaction kinetics as determined by neutron reflectometry measurements. Atmospheric aerosol can be extremely viscous. The kinetics of the reaction were found to be independent of the viscosity of the sub-phase below the monolayer over a range of moderate viscosities, , demonstrating no involvement of aqueous sub-phase oxidants in the rate determining step. The kinetics of oxidation of monolayers of pure oleic acid were found to depend on the surface coverage with different behaviour observed above and below a surface coverage of oleic acid of ∼1 × 1018 molecule m-2. Atmospheric aerosol are typically complex mixtures, and the presence of an additional compound in the monolayer that is inert to direct ozone oxidation, stearic acid, did not significantly change the reaction kinetics. It is demonstrated that oleic acid monolayers at the air-water interface do not leave any detectable material at the air-water interface, contradicting the previous work published in this journal which the authors now believe to be erroneous. The combined results presented here indicate that the kinetics, and thus the atmospheric chemical lifetime for unsaturated surface active materials at the air-water interface to loss by reaction with gas-phase ozone, can be considered to be independent of other materials present at either the air-water interface or in the aqueous sub-phase.
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Affiliation(s)
- Martin D King
- Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey, UK.
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25
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López-Diaz D, Merchán MD, Velázquez MM. The behavior of graphene oxide trapped at the air water interface. Adv Colloid Interface Sci 2020; 286:102312. [PMID: 33166724 DOI: 10.1016/j.cis.2020.102312] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/28/2020] [Accepted: 10/29/2020] [Indexed: 02/02/2023]
Abstract
Graphene oxide is a derivate of graphene obtained by oxidation of graphite and other carbonaceous materials. The more accepted structure consists in carbonyl and carboxyl groups located at the edge of the graphene network and hydroxyl and epoxy groups attached to the basal plane. The percentage of O-groups depends on the synthesis route and the material used as carbon source. In addition, highly oxidized fragments, called oxidative debris, OD, are produced during the oxidation process. These fragments are adsorbed onto the graphene oxide network and can be removed by alkaline washing. The purified material has lower O/C ratio than graphene oxide and its properties are also quite different. Due to its structure, graphene oxide can be adsorbed at the air-water interface of the aqueous solution by diffusion, Gibbs monolayers, or by spreading on a clean water subphase resulting in a Langmuir film. This review is intended to provide information on the importance of controlling the chemical composition, structure, size, and oxidative debris, on the manufacture of graphene oxide films. To this end the review shows the influence of the synthesis route and the starting material on the structure of graphene oxide and analyzes several examples of the behavior and properties of films prepared with different types of graphene oxides. The great variability of behaviors of graphene oxide films caused by the different structure of this material provides a great opportunity to fine-tune the properties of films according to the needs of different applications.
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26
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Akanno A, Guzmán E, Ortega F, Rubio RG. Behavior of the water/vapor interface of chitosan solutions with an anionic surfactant: effect of polymer-surfactant interactions. Phys Chem Chem Phys 2020; 22:23360-23373. [PMID: 33047113 DOI: 10.1039/d0cp02470h] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The adsorption of mixtures formed by chitosan and sodium lauryl ether sulfate (SLES) at the water/vapor interface has been studied on the basis of their impact on the equilibrium surface tension of the interface, and the response of such an interface to mechanical deformations. The analysis of the surfactant binding to the chitosan chains evidenced that the chitosan-SLES solutions were mixtures of polyelectrolyte-surfactant complexes and a non-negligible amount of free surfactant molecules. The interfacial properties showed two well-differentiated regions for interfacial adsorption as a function of the SLES concentration: (i) at a low surfactant concentration, co-adsorption of chitosan and SLES occurs, and (ii) at high concentrations, the surface is mostly occupied by SLES molecules. This behavior may be interpreted in terms of a complex equilibration mechanism of the interfacial layers, where different coupled dynamic processes may be involved. Furthermore, the use of the time-concentration superposition principle has confirmed the different dynamic behaviors of the chitosan-SLES adsorption as a function of the SLES concentration. This work sheds light on some of the most fundamental bases governing the physico-chemical behavior of mixtures formed by a biopolymer and a surfactant, where their complex behavior is governed by an intricate balance of bulk and interfacial interactions.
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Affiliation(s)
- Andrew Akanno
- Departamento de Química Física-Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain.
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27
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Matyszewska D, Nazaruk E, Campbell RA. Interactions of anticancer drugs doxorubicin and idarubicin with lipid monolayers: New insight into the composition, structure and morphology. J Colloid Interface Sci 2020; 581:403-416. [PMID: 32771749 DOI: 10.1016/j.jcis.2020.07.092] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/17/2020] [Accepted: 07/18/2020] [Indexed: 12/13/2022]
Abstract
We quantify directly here for the first time the extents of interactions of two different anthracycline drugs with pure and mixed lipid monolayers with respect to the surface pressure and elucidate differences in the resulting interaction mechanisms. The work concerns interactions of doxorubicin (DOx) and idarubicin (IDA) with monolayers of the zwitterionic DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) and negatively charged DMPS (1,2-dimyristoyl-sn-glycero-3-phospho-L-serine (sodium salt)) as well as a 7:3 mixture of the two lipids. These drugs are used in current cancer treatments, while the lipid systems were chosen as phosphocholines are the major lipid component of healthy cell membranes, and phosphoserines are the major lipid component that is externalized into the outer leaflet of cancerous cell membranes. It is shown that DOx interacts with DMPS monolayers to a greater extent than with DMPC monolayers by lower limits of a factor of 5 at a surface pressure of 10 mN/m and a factor of 12 at 30 mN/m. With increasing surface pressure, the small amount of drug (~0.3 µmol/m2) bound to DMPC monolayers is excluded from the interface, yet its interaction with DMPS monolayers is enhanced until there is even more drug (~3.2 µmol/m2) than lipid (~2.6 µmol/m2) at the interface. Direct evidence is presented for all systems studied that upon surface area compression lipid is reproducibly expelled from the monolayer, which we infer to be in the form of drug-lipid aggregates, yet the nature of adsorption of material back to the monolayer upon expansion is system-dependent. At 30 mN/m, most relevant to human physiology, the interactions of DOx and IDA are starkly different. For DOx, there is a conformational change in the interfacial layer driven by aggregation, resulting in the formation of lateral domains that have extended layers of drug. For the more lipophilic IDA, there is penetration of the drug into the hydrophobic acyl chain region of the monolayer and no indication of lateral segregation. In addition to the Langmuir technique, these advances were made as a result of direct measurements of the interfacial composition, structure and morphology using two different implementations of neutron reflectometry and Brewster angle microscopy. The results provide new insight into key processes that determine the uptake of drugs such as limited drug penetration through cell membranes by passive diffusion as well as activation of drug removal mechanisms related to multidrug resistance.
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Affiliation(s)
- Dorota Matyszewska
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland.
| | - Ewa Nazaruk
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | - Richard A Campbell
- Institut Laue-Langevin, 71 avenue des Martyrs, CS20156, 38042 Grenoble, France; Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, United Kingdom.
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28
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Schnurbus M, Campbell RA, Droste J, Honnigfort C, Glikman D, Gutfreund P, Hansen MR, Braunschweig B. Photo-Switchable Surfactants for Responsive Air–Water Interfaces: Azo versus Arylazopyrazole Amphiphiles. J Phys Chem B 2020; 124:6913-6923. [DOI: 10.1021/acs.jpcb.0c02848] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Marco Schnurbus
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
- Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Busso-Peus-Straße 10, 48149 Münster, Germany
| | - Richard A. Campbell
- Division of Pharmacy & Optometry, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Jörn Droste
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Christian Honnigfort
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
- Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Busso-Peus-Straße 10, 48149 Münster, Germany
| | - Dana Glikman
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
- Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Busso-Peus-Straße 10, 48149 Münster, Germany
| | - Philipp Gutfreund
- Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, Grenoble CEDEX 9 38042, France
| | - Michael Ryan Hansen
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Björn Braunschweig
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
- Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Busso-Peus-Straße 10, 48149 Münster, Germany
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29
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Honnigfort C, Campbell RA, Droste J, Gutfreund P, Hansen MR, Ravoo BJ, Braunschweig B. Unexpected monolayer-to-bilayer transition of arylazopyrazole surfactants facilitates superior photo-control of fluid interfaces and colloids. Chem Sci 2020; 11:2085-2092. [PMID: 32190275 PMCID: PMC7059314 DOI: 10.1039/c9sc05490a] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/08/2020] [Indexed: 12/15/2022] Open
Abstract
Interfaces that can change their chemistry on demand have huge potential for applications and are prerequisites for responsive or adaptive materials. We report on the performance of a newly designed n-butyl-arylazopyrazole butyl sulfonate (butyl-AAP-C4S) surfactant that can change its structure at the air-water interface by E/Z photo-isomerization in an unprecedented way. Large and reversible changes in surface tension (Δγ = 27 mN m-1) and surface excess (ΔΓ > 2.9 μmol m-2) demonstrate superior performance of the butyl-AAP-C4S amphiphile to that of existing ionic surfactants. Neutron reflectometry and vibrational sum-frequency generation spectroscopy reveal that these large changes are caused by an unexpected monolayer-to-bilayer transition. This exceptional behavior is further shown to have dramatic consequences at larger length scales as highlighted by applications like the light-triggered collapse of aqueous foam which is tuned from high (>1 h) to low (<10 min) stabilities and light-actuated particle motion via Marangoni flows.
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Affiliation(s)
- Christian Honnigfort
- Institute of Physical Chemistry , Westfälische Wilhelms-Universität Münster , Corrensstraße 28/30 , 48149 Münster , Germany .
- Center for Soft Nanoscience (SoN) , Westfälische Wilhelms-Universität Münster , Busso-Peus-Straße 10 , 48149 Münster , Germany
| | - Richard A Campbell
- Division of Pharmacy & Optometry , School of Health Sciences , University of Manchester , Oxford Road , Manchester M13 9PT , UK
| | - Jörn Droste
- Institute of Physical Chemistry , Westfälische Wilhelms-Universität Münster , Corrensstraße 28/30 , 48149 Münster , Germany .
| | - Philipp Gutfreund
- Institut Laue-Langevin (ILL) , 71 Avenue des Martyrs, CS 20156 , 38042 Grenoble Cedex 9 , France
| | - Michael Ryan Hansen
- Institute of Physical Chemistry , Westfälische Wilhelms-Universität Münster , Corrensstraße 28/30 , 48149 Münster , Germany .
| | - Bart Jan Ravoo
- Center for Soft Nanoscience (SoN) , Westfälische Wilhelms-Universität Münster , Busso-Peus-Straße 10 , 48149 Münster , Germany
- Organic Chemistry Institute , Westfälische Wilhelms-Universität Münster , Corrensstraße 40 , 48149 Münster , Germany
| | - Björn Braunschweig
- Institute of Physical Chemistry , Westfälische Wilhelms-Universität Münster , Corrensstraße 28/30 , 48149 Münster , Germany .
- Center for Soft Nanoscience (SoN) , Westfälische Wilhelms-Universität Münster , Busso-Peus-Straße 10 , 48149 Münster , Germany
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30
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Schabes BK, Richmond GL. Helping Strands: Polyelectrolyte Assists in Surfactant Assembly below Critical Micelle Concentration. J Phys Chem B 2020; 124:234-239. [PMID: 31804084 DOI: 10.1021/acs.jpcb.9b08692] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Strongly adsorbing polymer/surfactant (P/S) combinations have been proposed for long-term applications such as emulsion stabilization. However, P/S systems are known to exhibit nonequilibrium behavior despite steady-state surface characteristics. This work examines the coadsorption of dodecyltrimethylammonium bromide and sodium poly(styrene sulfonate) (PSS) using oil/water tensiometry, UV absorption, and vibrational sum frequency spectroscopy. To determine which features do not represent true equilibrium, the molecular details of PSS adsorption are compared for fresh and aged samples. At surfactant concentrations concurrent with bulk precipitation, significant differences between fresh and aged samples indicate that the strong initial coadsorption within this system is a nonequilibrium feature. We conclude that the long equilibration timescales arise from the slow assembly of non-adsorbing polyelectrolyte/micelle complexes below the critical micelle concentration. This study resolves a recent debate regarding system equilibria of surface-active P/S combinations at a water surface.
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Affiliation(s)
- Brandon K Schabes
- Department of Chemistry and Biochemistry , University of Oregon , Eugene , Oregon 97403 , United States
| | - Geraldine L Richmond
- Department of Chemistry and Biochemistry , University of Oregon , Eugene , Oregon 97403 , United States
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31
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Synergy, competition, and the "hanging" polymer layer: Interactions between a neutral amphiphilic 'tardigrade' comb co-polymer with an anionic surfactant at the air-water interface. J Colloid Interface Sci 2019; 561:181-194. [PMID: 31830734 DOI: 10.1016/j.jcis.2019.11.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 11/03/2019] [Accepted: 11/05/2019] [Indexed: 12/21/2022]
Abstract
Understanding the structure of polymer/surfactant mixtures at the air-water interface is of fundamental importance and also of relevance to a variety of practical applications. Here, the complexation between a neutral 'tardigrade' comb co-polymer (consisting of a hydrophilic polyethylene glycol backbone with hydrophobic polyvinyl acetate grafts, PEG-g-PVAc) with an anionic surfactant (sodium dodecyl sulfate, SDS) at the air-water interface has been studied. Contrast-matched neutron reflectivity (NR) complemented by surface tension measurements allowed elucidation of the interfacial composition and structure of these mixed systems, as well as providing physical insights into the polymer/surfactant interactions at the air-water interface. For both polymer concentrations studied, below and above its critical aggregation concentration, cac, (0.2 cac and 2 cac, corresponding to 0.0002 wt% or 0.013 mM and 0.002 wt% or 0.13 mM respectively), we observed a synergistic cooperative behaviour at low surfactant concentrations with a 1-2 nm mixed interfacial layer; a competitive adsorption behaviour at higher surfactant concentrations was observed where the polymer was depleted from the air-water interface, with an overall interfacial layer thickness ~1.6 nm independent of the polymer concentration. The weakly associated polymer layer "hanging" proximally to the interface, however, played a role in enhancing foam stability, thus was relevant to the detergency efficacy in such polymer/surfactant mixtures in industrial formulations.
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Reflectometry Reveals Accumulation of Surfactant Impurities at Bare Oil/Water Interfaces. Molecules 2019; 24:molecules24224113. [PMID: 31739471 PMCID: PMC6891303 DOI: 10.3390/molecules24224113] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/06/2019] [Accepted: 11/09/2019] [Indexed: 12/04/2022] Open
Abstract
Bare interfaces between water and hydrophobic media like air or oil are of fundamental scientific interest and of great relevance for numerous applications. A number of observations involving water/hydrophobic interfaces have, however, eluded a consensus mechanistic interpretation so far. Recent theoretical studies ascribe these phenomena to an interfacial accumulation of charged surfactant impurities in water. In the present work, we show that identifying surfactant accumulation with X-ray reflectometry (XRR) or neutron reflectometry (NR) is challenging under conventional contrast configurations because interfacial surfactant layers are then hardly visible. On the other hand, both XRR and NR become more sensitive to surfactant accumulation when a suitable scattering length contrast is generated by using fluorinated oil. With this approach, significant interfacial accumulation of surfactant impurities at the bare oil/water interface is observed in experiments involving standard cleaning procedures. These results suggest that surfactant impurities may be a limiting factor for the investigation of fundamental phenomena involving water/hydrophobic interfaces.
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33
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Skoda MW. Recent developments in the application of X-ray and neutron reflectivity to soft-matter systems. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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34
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Maestro A. Tailoring the interfacial assembly of colloidal particles by engineering the mechanical properties of the interface. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.02.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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35
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Campbell RA, Saaka Y, Shao Y, Gerelli Y, Cubitt R, Nazaruk E, Matyszewska D, Lawrence MJ. Structure of surfactant and phospholipid monolayers at the air/water interface modeled from neutron reflectivity data. J Colloid Interface Sci 2018; 531:98-108. [DOI: 10.1016/j.jcis.2018.07.022] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/06/2018] [Accepted: 07/06/2018] [Indexed: 10/28/2022]
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36
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Combined surface analysis methods. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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