1
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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] [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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Ciutara CO, Iasella SV, Huang B, Barman S, Zasadzinski JA. Evolution of interfacial mechanics of lung surfactant mimics progression of acute respiratory distress syndrome. Proc Natl Acad Sci U S A 2023; 120:e2309900120. [PMID: 38085774 PMCID: PMC10743378 DOI: 10.1073/pnas.2309900120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 10/06/2023] [Indexed: 12/18/2023] Open
Abstract
How acute respiratory distress syndrome progresses from underlying disease or trauma is poorly understood, and there are no generally accepted treatments resulting in a 40% mortality rate. However, during the inflammation that accompanies this disease, the phospholipase A2 concentration increases in the alveolar fluids leading to the hydrolysis of bacterial, viral, and lung surfactant phospholipids into soluble lysolipids. We show that if the lysolipid concentration in the subphase reaches or exceeds its critical micelle concentration, the surface tension, γ, of dipalmitoyl phosphatidylcholine (DPPC) or Curosurf monolayers increases and the dilatational modulus, [Formula: see text], decreases to that of a pure lysolipid interface. This is consistent with DPPC being solubilized in lysolipid micelles and being replaced by lysolipid at the interface. These changes lead to [Formula: see text] which is the criterion for the Laplace instability that can lead to mechanical instabilities during lung inflation, potentially causing alveolar collapse. These findings provide a mechanism behind the alveolar collapse and uneven lung inflation during ARDS.
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Affiliation(s)
- Clara O. Ciutara
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN55455
| | - Steven V. Iasella
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN55455
| | - Boxun Huang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN55455
| | - Sourav Barman
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN55455
| | - Joseph A. Zasadzinski
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN55455
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3
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Liu JY, Sayes CM. Lung surfactant as a biophysical assay for inhalation toxicology. Curr Res Toxicol 2022; 4:100101. [PMID: 36687216 PMCID: PMC9849875 DOI: 10.1016/j.crtox.2022.100101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 11/21/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
Lung surfactant (LS) is a mixture of lipids and proteins that forms a thin film at the gas-exchange surfaces of the alveoli. The components and ultrastructure of LS contribute to its biophysical and biochemical functions in the respiratory system, most notably the lowering of surface tension to facilitate breathing mechanics. LS inhibition can be caused by metabolic deficiencies or the intrusion of endogenous or exogenous substances. While LS has been sourced from animals or synthesized for clinical therapeutics, the biofluid mixture has also gained recent interest as a biophysical model for inhalation toxicity. Various methods can be used to evaluate LS function quantitatively or qualitatively after exposure to potential toxicants. A narrative review of the recent literature was conducted. Studies focused whether LS was inhibited by various environmental contaminants, nanoparticles, or manufactured products. A review is also conducted on synthetic lung surfactants (SLS), which have emerged as a promising alternative to conventional animal-sourced LS. The intrinsic advantages and recent advances of SLS make a strong case for more widespread usage in LS-based toxicological assays.
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Affiliation(s)
| | - Christie M. Sayes
- Corresponding author at: Baylor University, Department of Environmental Science, One Bear Place # 97266, Waco, TX 76798-7266.
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4
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Structural hallmarks of lung surfactant: Lipid-protein interactions, membrane structure and future challenges. Arch Biochem Biophys 2021; 703:108850. [PMID: 33753033 DOI: 10.1016/j.abb.2021.108850] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 02/20/2021] [Accepted: 03/16/2021] [Indexed: 11/23/2022]
Abstract
Lung surfactant (LS) is an outstanding example of how a highly regulated and dynamic membrane-based system has evolved to sustain a wealth of structural reorganizations in order to accomplish its biophysical function, as it coats and stabilizes the respiratory air-liquid interface in the mammalian lung. The present review dissects the complexity of the structure-function relationships in LS through an updated description of the lipid-protein interactions and the membrane structures that sustain its synthesis, secretion, interfacial performance and recycling. We also revise the current models and the biophysical techniques employed to study the membranous architecture of LS. It is important to consider that the structure and functional properties of LS are often studied in bulk or under static conditions, in spite that surfactant function is strongly connected with a highly dynamic behaviour, sustained by very polymorphic structures and lipid-lipid, lipid-protein and protein-protein interactions that reorganize in precise spatio-temporal coordinates. We have tried to underline the evidences available of the existence of such structural dynamism in LS. A last important aspect is that the synthesis and assembly of LS is a strongly regulated intracellular process to ensure the establishment of the proper interactions driving LS surface activity, while protecting the integrity of other cell membranes. The use of simplified lipid models or partial natural materials purified from animal tissues could be too simplistic to understand the true molecular mechanisms defining surfactant function in vivo. In this line, we will bring into the attention of the reader the methodological challenges and the questions still open to understand the structure-function relationships of LS at its full biological relevance.
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5
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Wang F, Liu J, Zeng H. Interactions of particulate matter and pulmonary surfactant: Implications for human health. Adv Colloid Interface Sci 2020; 284:102244. [PMID: 32871405 PMCID: PMC7435289 DOI: 10.1016/j.cis.2020.102244] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 08/12/2020] [Accepted: 08/14/2020] [Indexed: 12/22/2022]
Abstract
Particulate matter (PM), which is the primary contributor to air pollution, has become a pervasive global health threat. When PM enters into a respiratory tract, the first body tissues to be directly exposed are the cells of respiratory tissues and pulmonary surfactant. Pulmonary surfactant is a pivotal component to modulate surface tension of alveoli during respiration. Many studies have proved that PM would interact with pulmonary surfactant to affect the alveolar activity, and meanwhile, pulmonary surfactant would be adsorbed to the surface of PM to change the toxic effect of PM. This review focuses on recent studies of the interactions between micro/nanoparticles (synthesized and environmental particles) and pulmonary surfactant (natural surfactant and its models), as well as the health effects caused by PM through a few significant aspects, such as surface properties of PM, including size, surface charge, hydrophobicity, shape, chemical nature, etc. Moreover, in vitro and in vivo studies have shown that PM leads to oxidative stress, inflammatory response, fibrosis, and cancerization in living bodies. By providing a comprehensive picture of PM-surfactant interaction, this review will benefit both researchers for further studies and policy-makers for setting up more appropriate regulations to reduce the adverse effects of PM on public health.
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Affiliation(s)
- Feifei Wang
- The Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510700, China,Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Jifang Liu
- The Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510700, China.
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
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6
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Barman S, Davidson ML, Walker LM, Anna SL, Zasadzinski JA. Inflammation product effects on dilatational mechanics can trigger the Laplace instability and acute respiratory distress syndrome. SOFT MATTER 2020; 16:6890-6901. [PMID: 32643749 PMCID: PMC7462632 DOI: 10.1039/d0sm00415d] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In the lungs, the Laplace pressure, ΔP = 2γ/R, would be higher in smaller alveoli than larger alveoli unless the surface tension, γ decreases with alveolar interfacial area, A, such that 2ε > γ in which ε = A(dγ/dA) is the dilatational modulus. In Acute Respiratory Distress Syndrome (ARDS), lipase activity due to the immune response to an underlying trauma or disease causes single chain lysolipid concentrations to increase in the alveolar fluids via hydrolysis of double-chain phospholpids in bacterial, viral, and normal cell membranes. Increasing lysolipid concentrations decrease the dilatational modulus dramatically at breathing frequencies if the soluble lysolipid has sufficient time to diffuse off the interface, causing 2ε < γ, thereby potentially inducing the "Laplace Instability", in which larger alveoli have a lower internal pressure than smaller alveoli. This can lead to uneven lung inflation, alveolar flooding, and poor gas exchange, typical symptoms of ARDS. While the ARDS lung contains a number of lipid and protein species in the alveolar fluid in addition to lysolipids, the surface activity and frequency dependent dilatational modulus of lysolipid suggest how inflammation may lead to the lung instabilities associated with ARDS. At high frequencies, even at high lysolipid concentrations, 2ε - γ > 0, which may explain the benefits ARDS patients receive from high frequency oscillatory ventilation.
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Affiliation(s)
- Sourav Barman
- Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA
| | - Michael L Davidson
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Lynn M Walker
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Shelly L Anna
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Joseph A Zasadzinski
- Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA
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7
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Bai X, Xu L, Tang JY, Zuo YY, Hu G. Adsorption of Phospholipids at the Air-Water Surface. Biophys J 2019; 117:1224-1233. [PMID: 31519299 DOI: 10.1016/j.bpj.2019.08.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 08/03/2019] [Accepted: 08/19/2019] [Indexed: 11/15/2022] Open
Abstract
Phospholipids are ubiquitous components of biomembranes and common biomaterials used in many bioengineering applications. Understanding adsorption of phospholipids at the air-water surface plays an important role in the study of pulmonary surfactants and cell membranes. To date, however, the biophysical mechanisms of phospholipid adsorption are still unknown. It is challenging to reveal the molecular structure of adsorbed phospholipid films. Using combined experiments with constrained drop surfactometry and molecular dynamics simulations, here, we studied the biophysical mechanisms of dipalmitoylphosphatidylcholine (DPPC) adsorption at the air-water surface. It was found that the DPPC film adsorbed from vesicles showed distinct equilibrium surface tensions from the DPPC monolayer spread via organic solvents. Our simulations revealed that only the outer leaflet of the DPPC vesicle is capable of unzipping and spreading at the air-water surface, whereas the inner leaflet remains intact and forms an inverted micelle to the interfacial monolayer. This inverted micelle increases the local curvature of the monolayer, thus leading to a loosely packed monolayer at the air-water surface and hence a higher equilibrium surface tension. These findings provide novel insights, to our knowledge, into the mechanism of the phospholipid and pulmonary surfactant adsorption and may help understand the structure-function correlation in biomembranes.
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Affiliation(s)
- Xuan Bai
- Department of Engineering Mechanics, Zhejiang University, Hangzhou, China; The State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Lu Xu
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii
| | - Jenny Y Tang
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii
| | - Yi Y Zuo
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii; Department of Pediatrics, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii.
| | - Guoqing Hu
- Department of Engineering Mechanics, Zhejiang University, Hangzhou, China.
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8
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Interfacial curvature effects on the monolayer morphology and dynamics of a clinical lung surfactant. Proc Natl Acad Sci U S A 2017; 115:E134-E143. [PMID: 29279405 DOI: 10.1073/pnas.1715830115] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The morphology of surfactant monolayers is typically studied on the planar surface of a Langmuir trough, even though most physiological interfaces are curved at the micrometer scale. Here, we show that, as the radius of a clinical lung surfactant monolayer-covered bubble decreases to ∼100 µm, the monolayer morphology changes from dispersed circular liquid-condensed (LC) domains in a continuous liquid-expanded (LE) matrix to a continuous LC linear mesh separating discontinuous LE domains. The curvature-associated morphological transition cannot be readily explained by current liquid crystal theories based on isotropic domains. It is likely due to the anisotropic bending energy of the LC phase of the saturated phospholipids that are common to all natural and clinical lung surfactants. This continuous LC linear mesh morphology is also present on bilayer vesicles in solution. Surfactant adsorption and the dilatational modulus are also strongly influenced by the changes in morphology induced by interfacial curvature. The changes in morphology and dynamics may have physiological consequences for lung stability and function as the morphological transition occurs at alveolar dimensions.
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9
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Selladurai SL, Miclette Lamarche R, Schmidt R, DeWolf CE. Model Lung Surfactant Films: Why Composition Matters. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10767-10775. [PMID: 27641759 DOI: 10.1021/acs.langmuir.6b02945] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Lung surfactant replacement therapies, Survanta and Infasurf, and two lipid-only systems both containing saturated and unsaturated phospholipids and one containing additional palmitic acid were used to study the impact of buffered saline on the surface activity, morphology, rheology, and structure of Langmuir monolayer model membranes. Isotherms and Brewster angle microscopy show that buffered saline subphases induce a film expansion, except when the cationic protein, SP-B, is present in sufficient quantities to already screen electrostatic repulsion, thus limiting the effect of changing pH and adding counterions. Grazing incidence X-ray diffraction results indicate an expansion not only of the liquid expanded phase but also an expansion of the lattice of the condensed phase. The film expansion corresponded in all cases with a significant reduction in the viscosity and elasticity of the films. The viscoelastic parameters are dominated by liquid expanded phase properties and do not appear to be dependent on the structure of the condensed phase domains in a phase separated film. The results highlight that the choice of subphase and film composition is important for meaningful interpretations of measurements using model systems.
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Affiliation(s)
- Sahana L Selladurai
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University , 7141 Sherbrooke Street West, Montreal, Canada H4B 1R6
| | - Renaud Miclette Lamarche
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University , 7141 Sherbrooke Street West, Montreal, Canada H4B 1R6
| | - Rolf Schmidt
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University , 7141 Sherbrooke Street West, Montreal, Canada H4B 1R6
| | - Christine E DeWolf
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University , 7141 Sherbrooke Street West, Montreal, Canada H4B 1R6
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10
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You SS, Heffern CTR, Dai Y, Meron M, Henderson JM, Bu W, Xie W, Lee KYC, Lin B. Liquid Surface X-ray Studies of Gold Nanoparticle–Phospholipid Films at the Air/Water Interface. J Phys Chem B 2016; 120:9132-41. [DOI: 10.1021/acs.jpcb.6b03734] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Siheng Sean You
- James
Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
| | - Charles T. R. Heffern
- James
Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
- Department
of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Yeling Dai
- Department
of Physics, The University of California—San Diego, La Jolla, California 92093, United States
| | - Mati Meron
- Center
for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, United States
| | - J. Michael Henderson
- James
Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
- Department
of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Wei Bu
- Center
for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, United States
| | - Wenyi Xie
- James
Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
- Department
of Chemical Engineering, City College of New York, New York City, New York 10031, United States
| | - Ka Yee C. Lee
- James
Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
- Department
of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
- Institute
for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Binhua Lin
- James
Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
- Center
for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, United States
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11
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Composition, structure and mechanical properties define performance of pulmonary surfactant membranes and films. Chem Phys Lipids 2014; 185:153-75. [PMID: 25260665 DOI: 10.1016/j.chemphyslip.2014.09.002] [Citation(s) in RCA: 183] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/06/2014] [Accepted: 09/11/2014] [Indexed: 12/30/2022]
Abstract
The respiratory surface in the mammalian lung is stabilized by pulmonary surfactant, a membrane-based system composed of multiple lipids and specific proteins, the primary function of which is to minimize the surface tension at the alveolar air-liquid interface, optimizing the mechanics of breathing and avoiding alveolar collapse, especially at the end of expiration. The goal of the present review is to summarize current knowledge regarding the structure, lipid-protein interactions and mechanical features of surfactant membranes and films and how these properties correlate with surfactant biological function inside the lungs. Surfactant mechanical properties can be severely compromised by different agents, which lead to surfactant inhibition and ultimately contributes to the development of pulmonary disorders and pathologies in newborns, children and adults. A detailed comprehension of the unique mechanical and rheological properties of surfactant layers is crucial for the diagnostics and treatment of lung diseases, either by analyzing the contribution of surfactant impairment to the pathophysiology or by improving the formulations in surfactant replacement therapies. Finally, a short review is also included on the most relevant experimental techniques currently employed to evaluate lung surfactant mechanics, rheology, and inhibition and reactivation processes.
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12
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Flasiński M, Broniatowski M, Wydro P, Dynarowicz-Łątka P. Comparative Characteristics of Membrane-Active Single-Chained Ether Phospholipids: PAF and Lyso-PAF in Langmuir Monolayers. J Phys Chem B 2012; 116:3155-63. [DOI: 10.1021/jp2121092] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Michał Flasiński
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland
| | - Marcin Broniatowski
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland
| | - Paweł Wydro
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland
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13
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Visualizing the analogy between competitive adsorption and colloid stability to restore lung surfactant function. Biophys J 2012; 102:777-86. [PMID: 22385848 DOI: 10.1016/j.bpj.2012.01.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 11/11/2011] [Accepted: 01/09/2012] [Indexed: 01/11/2023] Open
Abstract
We investigated a model of acute respiratory distress syndrome in which the serum protein albumin adsorbs to an air-liquid interface and prevents the thermodynamically preferable adsorption of the clinical lung surfactant Survanta by inducing steric and electrostatic energy barriers analogous to those that prevent colloidal aggregation. Chitosan and polyethylene glycol (PEG), two polymers that traditionally have been used to aggregate colloids, both allow Survanta to quantitatively displace albumin from the interface, but through two distinct mechanisms. Direct visualization with confocal microscopy shows that the polycation chitosan coadsorbs to interfacial layers of both Survanta and albumin, and also colocalizes with the anionic domains of Survanta at the air-liquid interface, consistent with it eliminating the electrostatic repulsion by neutralizing the surface charges on albumin and Survanta. In contrast, the PEG distribution does not change during the displacement of albumin by Survanta, consistent with PEG inducing a depletion attraction sufficient to overcome the repulsive energy barrier toward adsorption.
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14
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Dhar P, Eck E, Israelachvili JN, Lee DW, Min Y, Ramachandran A, Waring AJ, Zasadzinski JA. Lipid-protein interactions alter line tensions and domain size distributions in lung surfactant monolayers. Biophys J 2012; 102:56-65. [PMID: 22225798 PMCID: PMC3250676 DOI: 10.1016/j.bpj.2011.11.4007] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/01/2011] [Accepted: 11/07/2011] [Indexed: 01/15/2023] Open
Abstract
The size distribution of domains in phase-separated lung surfactant monolayers influences monolayer viscoelasticity and compressibility which, in turn, influence monolayer collapse and set the compression at which the minimum surface tension is reached. The surfactant-specific protein SP-B decreases the mean domain size and polydispersity as shown by fluorescence microscopy. From the images, the line tension and dipole density difference are determined by comparing the measured size distributions with a theory derived by minimizing the free energy associated with the domain energy and mixing entropy. We find that SP-B increases the line tension, dipole density difference, and the compressibility modulus at surface pressures up to the squeeze-out pressure. The increase in line tension due to SP-B indicates the protein avoids domain boundaries due to its solubility in the more fluid regions of the film.
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Affiliation(s)
- Prajnaparamita Dhar
- Department of Chemical Engineering, University of Kansas, Lawrence, Kansas, USA.
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15
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Ziblat R, Leiserowitz L, Addadi L. Kristalline Lipiddomänen: Charakterisierung durch Röntgenbeugung und ihre Rolle in der Biologie. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201004470] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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16
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Ziblat R, Leiserowitz L, Addadi L. Crystalline lipid domains: characterization by X-ray diffraction and their relation to biology. Angew Chem Int Ed Engl 2011; 50:3620-9. [PMID: 21472900 DOI: 10.1002/anie.201004470] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Indexed: 12/29/2022]
Abstract
Biological membranes comprise thousands of different lipids, differing in their alkyl chains, headgroups, and degree of saturation. It is estimated that 5% of the genes in the human genome are responsible for regulating the lipid composition of cell membranes. Conceivably, the functional explanation for this diversity is found, at least in part, in the propensity of lipids to segregate into distinct domains, which are important for cell function. X-ray diffraction has been used increasingly to characterize the packing and phase behavior of lipids in membranes. Crystalline domains have been studied in synthetic membranes using wide- and small-angle X-ray scattering, and grazing incidence X-ray diffraction. Herein we summarize recent results obtained using the various X-ray methods, discuss the correlation between crystalline domains and liquid ordered domains studied with other techniques, and the relevance of crystalline domains to functional lipid domains in biological membranes.
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Affiliation(s)
- Roy Ziblat
- Department of Structural Biology, Weizmann Institute of Science, 76100 Rehovot, Israel
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17
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Fernsler J. A quasi-equilibrium theory of protein adsorption. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:148-157. [PMID: 21126036 DOI: 10.1021/la103316j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A model is developed to describe the adsorption and desorption of proteins to and from a surface film under quasi-equilibrium conditions. Starting from Fick's first law of diffusion, an equation for the flux of molecules to a surface is derived assuming a gradient in the chemical potential from the bulk to the surface and a potential barrier due to an existing surface film. Protein molecules are modeled as components with varying surface areas to depict the different orientations of molecules with respect to the film. For concentrated solutions, formation of multilayer protein films is described by allowing components with small minimum surface areas. The thermodynamic analysis is based on Butler's equation for the chemical potentials of the components of a Gibbs surface layer and a first-order model for the nonideality of the surface layer enthalpy and entropy. The model assumes reversible adsorption, consistent with globular proteins that show little denaturation or flexible-chain proteins that reversibly denature at the interface. The model predicts the behavior of five different experiments measuring film properties of the serum protein albumin in quasi-equilibrium and equilibrium conditions at over 2 orders of magnitude in concentration using a single set of parameters. This provides a new framework for analyzing interactions and adsorption of protein films. The key new features of this model are an extension of the classical Smoluchowski analysis to calculate the adsorption and desorption rate, a model of multilayers with decreased molecular areas to allow effective densities greater than a close-packed monolayer, and a concentration-dependent layer thickness.
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Affiliation(s)
- Jonathan Fernsler
- Department of Physics, California Polytechnic State University, San Luis Obispo, California, United States.
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Zasadzinski JA, Stenger PC, Shieh I, Dhar P. Overcoming rapid inactivation of lung surfactant: analogies between competitive adsorption and colloid stability. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1798:801-28. [PMID: 20026298 PMCID: PMC2834873 DOI: 10.1016/j.bbamem.2009.12.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 12/13/2009] [Accepted: 12/15/2009] [Indexed: 01/05/2023]
Abstract
Lung surfactant (LS) is a mixture of lipids and proteins that line the alveolar air-liquid interface, lowering the interfacial tension to levels that make breathing possible. In acute respiratory distress syndrome (ARDS), inactivation of LS is believed to play an important role in the development and severity of the disease. This review examines the competitive adsorption of LS and surface-active contaminants, such as serum proteins, present in the alveolar fluids of ARDS patients, and how this competitive adsorption can cause normal amounts of otherwise normal LS to be ineffective in lowering the interfacial tension. LS and serum proteins compete for the air-water interface when both are present in solution either in the alveolar fluids or in a Langmuir trough. Equilibrium favors LS as it has the lower equilibrium surface pressure, but the smaller proteins are kinetically favored over multi-micron LS bilayer aggregates by faster diffusion. If albumin reaches the interface, it creates an energy barrier to subsequent LS adsorption that slows or prevents the adsorption of the necessary amounts of LS required to lower surface tension. This process can be understood in terms of classic colloid stability theory in which an energy barrier to diffusion stabilizes colloidal suspensions against aggregation. This analogy provides qualitative and quantitative predictions regarding the origin of surfactant inactivation. An important corollary is that any additive that promotes colloid coagulation, such as increased electrolyte concentration, multivalent ions, hydrophilic non-adsorbing polymers such as PEG, dextran, etc. added to LS, or polyelectrolytes such as chitosan, also promotes LS adsorption in the presence of serum proteins and helps reverse surfactant inactivation. The theory provides quantitative tools to determine the optimal concentration of these additives and suggests that multiple additives may have a synergistic effect. A variety of physical and chemical techniques including isotherms, fluorescence microscopy, electron microscopy and X-ray diffraction show that LS adsorption is enhanced by this mechanism without substantially altering the structure or properties of the LS monolayer.
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Affiliation(s)
- Joseph A Zasadzinski
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
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Dhar P, Cao Y, Fischer TM, Zasadzinski JA. Active interfacial shear microrheology of aging protein films. PHYSICAL REVIEW LETTERS 2010; 104:016001. [PMID: 20366371 PMCID: PMC3407536 DOI: 10.1103/physrevlett.104.016001] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Indexed: 05/11/2023]
Abstract
The magnetically driven rotation of 300 nm diameter rods shows the surface viscosity of albumin at an air-water interface increases from 10(-9) to 10(-5) N s/m over 2 h while the surface pressure saturates in minutes. The increase in surface viscosity is not accompanied by a corresponding increase in elasticity, suggesting that the protein film anneals with time, resulting in a more densely packed film leading to increased resistance to shear. The nanometer dimensions of the rods provide the same sensitivity as passive microrheology with an improved ability to measure more viscous films.
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Affiliation(s)
- Prajnaparamita Dhar
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93117
| | - Yanyan Cao
- Department of Chemistry, Pennsylvania State University, College Park, PA 16801
| | - Thomas M. Fischer
- Institut für Experimentalphysik V, Universität Bayreuth, 95440 Bayreuth, Germany
| | - J. A. Zasadzinski
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93117
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Stenger PC, Isbell SG, St Hillaire D, Zasadzinski JA. Rediscovering the Schulze-Hardy rule in competitive adsorption to an air-water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:10045-50. [PMID: 19705897 PMCID: PMC2734920 DOI: 10.1021/la9009724] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The ratio of divalent to monovalent ion concentration necessary to displace the surface-active protein, albumin, by lung surfactant monolayers and multilayers at an air-water interface scales as 2(-6), the same concentration dependence as the critical flocculation concentration (CFC) for colloids with a high surface potential. Confirming this analogy between competitive adsorption and colloid stability, polymer-induced depletion attraction and electrostatic potentials are additive in their effects; the range of the depletion attraction, twice the polymer radius of gyration, must be greater than the Debye length to have an effect on adsorption.
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Affiliation(s)
- Patrick C Stenger
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106-5080, USA
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Fernsler JG, Zasadzinski JA. Competitive adsorption: a physical model for lung surfactant inactivation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:8131-8143. [PMID: 19534502 PMCID: PMC2732715 DOI: 10.1021/la8039434] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Charged, surface-active serum proteins can severely reduce or eliminate the adsorption of lung surfactant from the subphase to the alveolar air-liquid interface via a kinetically controlled competitive adsorption process. The decreased surfactant concentration at the interface leads to higher surface tensions during the compression of the interface during breathing. The correspondence between the factors governing colloid stability and competitive adsorption is validated via a new method of measuring surfactant and serum protein adsorption rates to the air-water interface, using quantitative Brewster angle microscopy (BAM). Competitive adsorption from a 10 mg/mL albumin subphase prevents the adsorption of lung surfactant from even high subphase concentrations due to the fast diffusion of the water-soluble proteins to the interface. The formation of an albumin film causes an electrostatic and steric barrier to subsequent surfactant adsorption, which can destroy the necessary properties of functional lung surfactant: low surface tension during compression and rapid respreading after film collapse. Surfactant inactivation is at least partially due to decreased surfactant adsorption; such decreased adsorption due to the presence of serum proteins may play a role in the development and severity of acute respiratory distress syndrome.
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Affiliation(s)
- Jonathan G Fernsler
- Department of Physics, California Polytechnic University, San Luis Obispo, CA 93407, USA.
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