1
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Govey-Scotland J, Johnstone L, Myant C, Friddin MS. Towards skin-on-a-chip for screening the dermal absorption of cosmetics. LAB ON A CHIP 2023; 23:5068-5080. [PMID: 37938128 DOI: 10.1039/d3lc00691c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Over the past few decades, there have been increasing global efforts to limit or ban the use of animals for testing cosmetic products. This ambition has been at the heart of international endeavours to develop new in vitro and animal-free approaches for assessing the safety of cosmetics. While several of these new approach methodologies (NAMs) have been approved for assessing different toxicological endpoints in the UK and across the EU, there remains an absence of animal-free methods for screening for dermal absorption; a measure that assesses the degree to which chemical substances can become systemically available through contact with human skin. Here, we identify some of the major technical barriers that have impacted regulatory recognition of an in vitro skin model for this purpose and propose how these could be overcome on-chip using artificial cells engineered from the bottom-up. As part of our future perspective, we suggest how this could be realised using a digital biomanufacturing pipeline that connects the design, microfluidic generation and 3D printing of artificial cells into user-crafted synthetic tissues. We highlight milestone achievements towards this goal, identify future challenges, and suggest how the ability to engineer animal-free skin models could have significant long-term consequences for dermal absorption screening, as well as for other applications.
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Affiliation(s)
- Jessica Govey-Scotland
- Dyson School of Design Engineering, Imperial College London, Exhibition Road, South Kensington, SW7 2AZ, London, UK.
- Institute for Molecular Sciences and Engineering, Imperial College London, Exhibition Road, South Kensington, SW7 2AZ, London, UK
| | - Liam Johnstone
- Office for Product Safety and Standards, 1 Victoria Street, SW1H 0ET, London, UK
| | - Connor Myant
- Dyson School of Design Engineering, Imperial College London, Exhibition Road, South Kensington, SW7 2AZ, London, UK.
| | - Mark S Friddin
- Dyson School of Design Engineering, Imperial College London, Exhibition Road, South Kensington, SW7 2AZ, London, UK.
- Institute for Molecular Sciences and Engineering, Imperial College London, Exhibition Road, South Kensington, SW7 2AZ, London, UK
- fabriCELL, Imperial College London and Kings College London, London, UK
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2
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Shamaprasad P, Frame CO, Moore TC, Yang A, Iacovella CR, Bouwstra JA, Bunge AL, McCabe C. Using molecular simulation to understand the skin barrier. Prog Lipid Res 2022; 88:101184. [PMID: 35988796 PMCID: PMC10116345 DOI: 10.1016/j.plipres.2022.101184] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 11/15/2022]
Abstract
Skin's effectiveness as a barrier to permeation of water and other chemicals rests almost entirely in the outermost layer of the epidermis, the stratum corneum (SC), which consists of layers of corneocytes surrounded by highly organized lipid lamellae. As the only continuous path through the SC, transdermal permeation necessarily involves diffusion through these lipid layers. The role of the SC as a protective barrier is supported by its exceptional lipid composition consisting of ceramides (CERs), cholesterol (CHOL), and free fatty acids (FFAs) and the complete absence of phospholipids, which are present in most biological membranes. Molecular simulation, which provides molecular level detail of lipid configurations that can be connected with barrier function, has become a popular tool for studying SC lipid systems. We review this ever-increasing body of literature with the goals of (1) enabling the experimental skin community to understand, interpret and use the information generated from the simulations, (2) providing simulation experts with a solid background in the chemistry of SC lipids including the composition, structure and organization, and barrier function, and (3) presenting a state of the art picture of the field of SC lipid simulations, highlighting the difficulties and best practices for studying these systems, to encourage the generation of robust reproducible studies in the future. This review describes molecular simulation methodology and then critically examines results derived from simulations using atomistic and then coarse-grained models.
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Affiliation(s)
- Parashara Shamaprasad
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Chloe O Frame
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Timothy C Moore
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Alexander Yang
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Christopher R Iacovella
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Joke A Bouwstra
- Division of BioTherapeutics, LACDR, Leiden University, 2333 CC Leiden, the Netherlands
| | - Annette L Bunge
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, United States of America
| | - Clare McCabe
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America; School of Engineering and Physical Science, Heriot-Watt University, Edinburgh, United Kingdom.
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3
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Chen Y, Liao M, Ma K, Wang Z, Demé B, Penfold J, Lu JR, R P Webster J, Li P. Implications of surfactant hydrophobic chain architecture on the Surfactant-Skin lipid model interaction. J Colloid Interface Sci 2022; 608:405-415. [PMID: 34628313 DOI: 10.1016/j.jcis.2021.09.098] [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: 07/30/2021] [Revised: 09/15/2021] [Accepted: 09/18/2021] [Indexed: 10/20/2022]
Abstract
Although surfactants have been widely used in skin care and other related applications, our knowledge about how surfactants interact with stratum corneum (SC) lipids remains limited. This work reports how surfactants interact with a lipid SC model by neutron diffraction and molecular dynamics (MD) simulations, focusing on examining the impact of surfactant molecular architecture. The surfactant-SC mixed membrane was constructed by an equimolar mixture of ceramide/cholesterol/fatty acids and surfactant at 1% molar ratio of total lipids. The arrangements of water and surfactant molecules in the membrane were obtained through neutron scattering length density (NSLD) profiles via contrast variation method, meanwhile, MD simulation clearly demonstrated the mechanism of hydration change in the surfactant-model SC mixed membrane. No drastic difference was detected in the repeating distance of the short periodicity phase (SPP) upon adding surfactants, however, it significantly enhanced the membrane hydration and reduced the amount of phase separated crystalline cholesterol, showing a strong dependence on surfactant chain length, branching and double bond. This work clearly demonstrates how surfactant architecture affects its interaction with the SC membrane, providing useful guidance for either choosing an existing surfactant or designing a new one for surfactant-based transdermal application.
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Affiliation(s)
- Yao Chen
- ISIS Facility, Rutherford Appleton Laboratory, STFC, Didcot, OXON, UK OX11 0QX
| | - Mingrui Liao
- Department of Physics & Astronomy, the University of Manchester, Manchester M13 9PL, UK
| | - Kun Ma
- ISIS Facility, Rutherford Appleton Laboratory, STFC, Didcot, OXON, UK OX11 0QX
| | - Zi Wang
- School of Science, State Key Laboratory of Heavy Oil Processing, China University of Petroleum , Qingdao 266580, China
| | - Bruno Demé
- Institut Laue-Langevin, Grenoble, France
| | - Jeff Penfold
- ISIS Facility, Rutherford Appleton Laboratory, STFC, Didcot, OXON, UK OX11 0QX
| | - Jian R Lu
- Department of Physics & Astronomy, the University of Manchester, Manchester M13 9PL, UK
| | - John R P Webster
- ISIS Facility, Rutherford Appleton Laboratory, STFC, Didcot, OXON, UK OX11 0QX
| | - Peixun Li
- ISIS Facility, Rutherford Appleton Laboratory, STFC, Didcot, OXON, UK OX11 0QX.
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4
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Schmitt T, Neubert RHH. State of the Art in Stratum Corneum Research. Part II: Hypothetical Stratum Corneum Lipid Matrix Models. Skin Pharmacol Physiol 2020; 33:213-230. [PMID: 32683377 DOI: 10.1159/000509019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 05/05/2020] [Indexed: 12/31/2022]
Abstract
This review is the second part of a series which presents the state of the art in stratum corneum (SC) lipid matrix (LM) research in depth. In this part, the various hypothetical models which were developed to describe the structure and function of the SC LM as the skin's barrier will be discussed. New as well as a cumulative assortment of older results which change the view on the different models are considered to conclude how well the different models are holding up today. As a final conclusion, a model, factoring in as much of the known data as possible, is concluded, unifying the varying different models into one which can be developed further, as new results are found in the future. So far, the model is described with a single crystalline or gel-like phase with a certain amount of nanocrystallites of concentrated ceramides (CERs) and free fatty acids and more fluid nanodomains caused by a fluidizing effect of the cholesterol. These domains are dynamically resolved and reformed and do not impair the barrier function. The chain conformation is not completely clear yet; however, an equilibrium of fully extended and hairpin-folded CERs with ratios depending on the properties of each individual CER species is proposed as most likely. An overlapping middle layer as described for the tri-layer model in part I of this series would be present for both conformations. The macroscopic broad-narrow-broad layering, observed in electron micrographs, is explained by an external templating by the lipid envelope, and an internal templating by short and long lipid chains each preferentially show a homophilic association, forming thicker and thinner bilayers, respectively. The degree of influence of the very long ω-hydroxy-CERs is discussed as well.
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Affiliation(s)
- Thomas Schmitt
- Department I, Institute of Anatomy and Cell Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Reinhard H H Neubert
- Institute of Applied Dermatopharmacy at the Martin Luther University Halle-Wittenberg (IADP), Halle/Saale, Germany, .,Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Halle/Saale, Germany,
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5
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Martinotti C, Ruiz-Perez L, Deplazes E, Mancera RL. Molecular Dynamics Simulation of Small Molecules Interacting with Biological Membranes. Chemphyschem 2020; 21:1486-1514. [PMID: 32452115 DOI: 10.1002/cphc.202000219] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 05/22/2020] [Indexed: 12/12/2022]
Abstract
Cell membranes protect and compartmentalise cells and their organelles. The semi-permeable nature of these membranes controls the exchange of solutes across their structure. Characterising the interaction of small molecules with biological membranes is critical to understanding of physiological processes, drug action and permeation, and many biotechnological applications. This review provides an overview of how molecular simulations are used to study the interaction of small molecules with biological membranes, with a particular focus on the interactions of water, organic compounds, drugs and short peptides with models of plasma cell membrane and stratum corneum lipid bilayers. This review will not delve on other types of membranes which might have different composition and arrangement, such as thylakoid or mitochondrial membranes. The application of unbiased molecular dynamics simulations and enhanced sampling methods such as umbrella sampling, metadynamics and replica exchange are described using key examples. This review demonstrates how state-of-the-art molecular simulations have been used successfully to describe the mechanism of binding and permeation of small molecules with biological membranes, as well as associated changes to the structure and dynamics of these membranes. The review concludes with an outlook on future directions in this field.
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Affiliation(s)
- Carlo Martinotti
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute and, Curtin Institute for Computation, Curtin University, Perth, WA 6845, Australia
| | - Lanie Ruiz-Perez
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute and, Curtin Institute for Computation, Curtin University, Perth, WA 6845, Australia
| | - Evelyne Deplazes
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Ricardo L Mancera
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute and, Curtin Institute for Computation, Curtin University, Perth, WA 6845, Australia
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6
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Antunes E, Cavaco-Paulo A. Stratum corneum lipid matrix with unusual packing: A molecular dynamics study. Colloids Surf B Biointerfaces 2020; 190:110928. [DOI: 10.1016/j.colsurfb.2020.110928] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 01/22/2020] [Accepted: 03/01/2020] [Indexed: 01/08/2023]
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7
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MacDermaid CM, Hall KW, DeVane RH, Klein ML, Fiorin G. Coexistence of Lipid Phases Stabilizes Interstitial Water in the Outer Layer of Mammalian Skin. Biophys J 2020; 118:1588-1601. [PMID: 32101711 DOI: 10.1016/j.bpj.2020.01.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 01/20/2020] [Accepted: 01/27/2020] [Indexed: 12/22/2022] Open
Abstract
The lipid matrix in the outer layer of mammalian skin, the stratum corneum, has been previously investigated by multiple biophysical techniques aimed at identifying hydrophilic and lipophilic pathways of permeation. Although consensus is developing over the microscopic structure of the lipid matrix, no molecular-resolution model describes the permeability of all chemical species simultaneously. Using molecular dynamics simulations of a model mixture of skin lipids, the self-assembly of the lipid matrix lamellae has been studied. At higher humidity, the resulting lamellar phase is maintained by partitioning excess water into isolated droplets of controlled size and spatial distribution. The droplets may fuse together to form intralamellar water channels, thereby providing a pathway for the permeation of hydrophilic species. These results reconcile competing data on the outer skin's structure and broaden the scope of molecular-based methods to improve the safety of topical products and to advance transdermal drug delivery.
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Affiliation(s)
- Christopher M MacDermaid
- Institute for Computational Molecular Science and Temple Materials Institute, Philadelphia, Pennsylvania
| | - Kyle Wm Hall
- Institute for Computational Molecular Science and Temple Materials Institute, Philadelphia, Pennsylvania
| | | | - Michael L Klein
- Institute for Computational Molecular Science and Temple Materials Institute, Philadelphia, Pennsylvania
| | - Giacomo Fiorin
- Institute for Computational Molecular Science and Temple Materials Institute, Philadelphia, Pennsylvania.
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8
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Karozis SN, Mavroudakis EI, Charalambopoulou GC, Kainourgiakis ME. Molecular simulations of self-assembled ceramide bilayers: comparison of structural and barrier properties. MOLECULAR SIMULATION 2020. [DOI: 10.1080/08927022.2019.1703975] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Stelios N. Karozis
- National Center for Scientific Research “Demokritos”, Ag. Paraskevi Attikis, Greece
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9
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Wang E, Klauda JB. Molecular Structure of the Long Periodicity Phase in the Stratum Corneum. J Am Chem Soc 2019; 141:16930-16943. [DOI: 10.1021/jacs.9b08995] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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10
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Verweij JE, Leermakers FAM, Sprakel J, van der Gucht J. Plasticity in colloidal gel strands. SOFT MATTER 2019; 15:6447-6454. [PMID: 31328199 DOI: 10.1039/c9sm00686a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Colloidal gels are space-spanning networks of aggregated particles. The mechanical response of colloidal gels is governed, to a large extent, by the properties of the individual gel strands. To study how colloidal gels respond to repeated deformations, we perform Brownian dynamics simulations on single strands of aggregated colloidal particles. While current models assume that gel failure is due to the brittle rupture of gel strands, our simulations show that gel strands undergo large plastic deformations prior to breaking. Rearrangement of particles within the strands leads to plastic lengthening and softening of the strands, which may ultimately lead to strand necking and ductile failure. This failure mechanism occurs irrespective of the thickness and length of the strands and the range and strength of the interaction potential. Rupture of gel strands is more likely for long and thin strands and for a long-ranged interaction potential.
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Affiliation(s)
- Joanne E Verweij
- Physical Chemistry and Soft Matter, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - Frans A M Leermakers
- Physical Chemistry and Soft Matter, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - Joris Sprakel
- Physical Chemistry and Soft Matter, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - Jasper van der Gucht
- Physical Chemistry and Soft Matter, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
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11
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Effect of Ceramide Tail Length on the Structure of Model Stratum Corneum Lipid Bilayers. Biophys J 2019; 114:113-125. [PMID: 29320678 DOI: 10.1016/j.bpj.2017.10.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/18/2017] [Accepted: 10/19/2017] [Indexed: 12/22/2022] Open
Abstract
Lipid bilayers composed of non-hydroxy sphingosine ceramide (CER NS), cholesterol (CHOL), and free fatty acids (FFAs), which are components of the human skin barrier, are studied via molecular dynamics simulations. Since mixtures of these lipids exist in dense gel phases with little molecular mobility at physiological conditions, care must be taken to ensure that the simulations become decorrelated from the initial conditions. Thus, we propose and validate an equilibration protocol based on simulated tempering, in which the simulation takes a random walk through temperature space, allowing the system to break out of metastable configurations and hence become decorrelated from its initial configuration. After validating the equilibration protocol, which we refer to as random-walk molecular dynamics, the effects of the lipid composition and ceramide tail length on bilayer properties are studied. Systems containing pure CER NS, CER NS + CHOL, and CER NS + CHOL + FFA, with the CER NS fatty acid tail length varied within each CER NS-CHOL-FFA composition, are simulated. The bilayer thickness is found to depend on the structure of the center of the bilayer, which arises as a result of the tail-length asymmetry between the lipids studied. The hydrogen bonding between the lipid headgroups and with water is found to change with the overall lipid composition, but is mostly independent of the CER fatty acid tail length. Subtle differences in the lateral packing of the lipid tails are also found as a function of CER tail length. Overall, these results provide insight into the experimentally observed trend of altered barrier properties in skin systems where there are more CERs with shorter tails present.
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12
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Marrink SJ, Corradi V, Souza PC, Ingólfsson HI, Tieleman DP, Sansom MS. Computational Modeling of Realistic Cell Membranes. Chem Rev 2019; 119:6184-6226. [PMID: 30623647 PMCID: PMC6509646 DOI: 10.1021/acs.chemrev.8b00460] [Citation(s) in RCA: 408] [Impact Index Per Article: 81.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 12/15/2022]
Abstract
Cell membranes contain a large variety of lipid types and are crowded with proteins, endowing them with the plasticity needed to fulfill their key roles in cell functioning. The compositional complexity of cellular membranes gives rise to a heterogeneous lateral organization, which is still poorly understood. Computational models, in particular molecular dynamics simulations and related techniques, have provided important insight into the organizational principles of cell membranes over the past decades. Now, we are witnessing a transition from simulations of simpler membrane models to multicomponent systems, culminating in realistic models of an increasing variety of cell types and organelles. Here, we review the state of the art in the field of realistic membrane simulations and discuss the current limitations and challenges ahead.
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Affiliation(s)
- Siewert J. Marrink
- Groningen
Biomolecular Sciences and Biotechnology Institute & Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Valentina Corradi
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Paulo C.T. Souza
- Groningen
Biomolecular Sciences and Biotechnology Institute & Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Helgi I. Ingólfsson
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - D. Peter Tieleman
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Mark S.P. Sansom
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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13
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Niroobakhsh Z, LaNasa JA, Belmonte A, Hickey RJ. Rapid Stabilization of Immiscible Fluids using Nanostructured Interfaces via Surfactant Association. PHYSICAL REVIEW LETTERS 2019; 122:178003. [PMID: 31107071 DOI: 10.1103/physrevlett.122.178003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Indexed: 06/09/2023]
Abstract
Surfactant molecules have been extensively used as emulsifying agents to stabilize immiscible fluids. Droplet stability has been shown to be increased when ordered nanoscale phases form at the interface of the two fluids due to surfactant association. Here, we report on using mixtures of a cationic surfactant and long chained alkenes with polar head groups [e.g., cetylpyridinium chloride (CPCl) and oleic acid] to create an ordered nanoscale lamellar morphology at aqueous-oil interfaces. The self-assembled nanostructure at the liquid-liquid interface was characterized using small-angle x-ray scattering, and the mechanical properties were measured using interfacial rheology. We hypothesize that the resulting lamellar morphology at the liquid-liquid interface is driven by the change in critical packing parameter when the CPCl molecules are diluted by the presence of the long chain alkenes with polar head groups, which leads to a spherical micelle-to-lamellar phase transition. The work presented here has larger implications for using nanostructured interfacial material to separate different fluids in flowing conditions for biosystems and in 3D printing technology.
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Affiliation(s)
- Zahra Niroobakhsh
- Department of Civil and Mechanical Engineering, University of Missouri-Kansas City, Kansas City, Missouri 64110, USA
| | - Jacob A LaNasa
- Department of Materials Science & Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Andrew Belmonte
- Department of Materials Science & Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Mathematics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Robert J Hickey
- Department of Materials Science & Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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14
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Wang E, Klauda JB. Structure and Permeability of Ceramide Bilayers and Multilayers. J Phys Chem B 2019; 123:2525-2535. [DOI: 10.1021/acs.jpcb.9b00037] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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15
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Wennberg CL, Narangifard A, Lundborg M, Norlén L, Lindahl E. Structural Transitions in Ceramide Cubic Phases during Formation of the Human Skin Barrier. Biophys J 2019. [PMID: 29539398 DOI: 10.1016/j.bpj.2017.12.039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
The stratum corneum is the outermost layer of human skin and the primary barrier toward the environment. The barrier function is maintained by stacked layers of saturated long-chain ceramides, free fatty acids, and cholesterol. This structure is formed through a reorganization of glycosylceramide-based bilayers with cubic-like symmetry into ceramide-based bilayers with stacked lamellar symmetry. The process is accompanied by deglycosylation of glycosylceramides and dehydration of the skin barrier lipid structure. Using coarse-grained molecular dynamics simulation, we show the effects of deglycosylation and dehydration on bilayers of human skin glycosylceramides and ceramides, folded in three dimensions with cubic (gyroid) symmetry. Deglycosylation of glycosylceramides destabilizes the cubic lipid bilayer phase and triggers a cubic-to-lamellar phase transition. Furthermore, subsequent dehydration of the deglycosylated lamellar ceramide system closes the remaining pores between adjacent lipid layers and locally induces a ceramide chain transformation from a hairpin-like to a splayed conformation.
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Affiliation(s)
- Christian L Wennberg
- Department of Physics, Swedish e-Science Research Center, KTH Royal Institute of Technology, Stockholm, Sweden; ERCO Pharma AB, Science for Life Laboratory, Stockholm, Sweden
| | - Ali Narangifard
- ERCO Pharma AB, Science for Life Laboratory, Stockholm, Sweden; Department of Cell and Molecular Biology (CMB), Karolinska Institutet, Stockholm, Sweden
| | - Magnus Lundborg
- ERCO Pharma AB, Science for Life Laboratory, Stockholm, Sweden
| | - Lars Norlén
- Department of Cell and Molecular Biology (CMB), Karolinska Institutet, Stockholm, Sweden; Dermatology Clinic, Karolinska University Hospital, Stockholm, Sweden.
| | - Erik Lindahl
- Department of Physics, Swedish e-Science Research Center, KTH Royal Institute of Technology, Stockholm, Sweden; Department of Biophysics and Biochemistry, Science for Life Laboratory, Stockholm University, Solna, Sweden.
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16
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Tascini AS, Noro MG, Seddon JM, Chen R, Bresme F. Mechanisms of lipid extraction from skin lipid bilayers by sebum triglycerides. Phys Chem Chem Phys 2019; 21:1471-1477. [DOI: 10.1039/c8cp05706k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Microsecond computations identify the pathways leading to the extraction of skin lipids by sebum triglycerides and the associated energetic costs.
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Affiliation(s)
| | | | | | - Rongjun Chen
- Department of Chemical Engineering
- Imperial College London
- UK
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17
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Klauda JB. Perspective: Computational modeling of accurate cellular membranes with molecular resolution. J Chem Phys 2018; 149:220901. [DOI: 10.1063/1.5055007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Jeffery B. Klauda
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, USA
- Biophysics Graduate Program, University of Maryland, College Park, Maryland 20742, USA
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18
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Podewitz M, Wang Y, Gkeka P, von Grafenstein S, Liedl KR, Cournia Z. Phase Diagram of a Stratum Corneum Lipid Mixture. J Phys Chem B 2018; 122:10505-10521. [DOI: 10.1021/acs.jpcb.8b07200] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Maren Podewitz
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Yin Wang
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Paraskevi Gkeka
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
| | - Susanne von Grafenstein
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Klaus R. Liedl
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
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19
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Human skin barrier formation takes place via a cubic to lamellar lipid phase transition as analyzed by cryo-electron microscopy and EM-simulation. Exp Cell Res 2018; 366:139-151. [DOI: 10.1016/j.yexcr.2018.03.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 03/06/2018] [Indexed: 01/14/2023]
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20
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Moore TC, Iacovella CR, Leonhard AC, Bunge AL, McCabe C. Molecular dynamics simulations of stratum corneum lipid mixtures: A multiscale perspective. Biochem Biophys Res Commun 2018; 498:313-318. [PMID: 28911866 PMCID: PMC5845828 DOI: 10.1016/j.bbrc.2017.09.040] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 09/04/2017] [Accepted: 09/08/2017] [Indexed: 10/18/2022]
Abstract
The lipid matrix of the stratum corneum (SC) layer of skin is essential for human survival; it acts as a barrier to prevent rapid dehydration while keeping potentially hazardous material outside the body. While the composition of the SC lipid matrix is known, the molecular-level details of its organization are difficult to infer experimentally, hindering the discovery of structure-property relationships. To this end, molecular dynamics simulations, which give molecular-level resolution, have begun to play an increasingly important role in understanding these relationships. However, most simulation studies of SC lipids have focused on preassembled bilayer configurations, which, owing to the slow dynamics of the lipids, may influence the final structure and hence the calculated properties. Self-assembled structures would avoid this dependence on the initial configuration, however, the size and length scales involved make self-assembly impractical to study with atomistic models. Here, we report on the development of coarse-grained models of SC lipids designed to study self-assembly. Building on previous work, we present the interactions between the headgroups of ceramide and free fatty acid developed using the multistate iterative Boltzmann inversion method. Validation of the new interactions is performed with simulations of preassembled bilayers and good agreement between the atomistic and coarse-grained models is found for structural properties. The self-assembly of mixtures of ceramide and free fatty acid is investigated and both bilayer and multilayer structures are found to form. This work therefore represents a necessary step in studying SC lipid systems on multiple time and length scales.
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Affiliation(s)
- Timothy C Moore
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, United States; Vanderbilt University Multiscale Modeling and Simulation Center, Nashville, TN 37235, United States
| | - Christopher R Iacovella
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, United States; Vanderbilt University Multiscale Modeling and Simulation Center, Nashville, TN 37235, United States
| | - Anne C Leonhard
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, United States; Vanderbilt University Multiscale Modeling and Simulation Center, Nashville, TN 37235, United States
| | - Annette L Bunge
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, United States
| | - Clare McCabe
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, United States; Vanderbilt University Multiscale Modeling and Simulation Center, Nashville, TN 37235, United States; Department of Chemistry, Vanderbilt University, Nashville, TN 37235, United States.
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21
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Wang E, Klauda JB. Simulations of Pure Ceramide and Ternary Lipid Mixtures as Simple Interior Stratum Corneum Models. J Phys Chem B 2018; 122:2757-2768. [DOI: 10.1021/acs.jpcb.8b00348] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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22
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Del Regno A, Notman R. Permeation pathways through lateral domains in model membranes of skin lipids. Phys Chem Chem Phys 2018; 20:2162-2174. [DOI: 10.1039/c7cp03258g] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Lateral organisation of skin lipids in membranes produces regions with different permeability; water permeation is favoured through cholesterol-rich regions.
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Affiliation(s)
| | - Rebecca Notman
- Department of Chemistry, University of Warwick
- Coventry
- UK
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23
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Striolo A, Grady BP. Surfactant Assemblies on Selected Nanostructured Surfaces: Evidence, Driving Forces, and Applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:8099-8113. [PMID: 28516778 DOI: 10.1021/acs.langmuir.7b00756] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Surfactant adsorption at solid-liquid interfaces is critical for a number of applications of vast industrial interest and can also be used to seed surface-modification processes. Many of the surfaces of interest are nanostructured, as they might present surface roughness at the molecular scale, chemical heterogeneity, as well as a combination of both surface roughness and chemical heterogeneity. These effects provide lateral confinement on the surfactant aggregates. It is of interest to quantify how much surfactant adsorbs on such nanostructured surfaces and how the surfactant aggregates vary as the degree of lateral confinement changes. This review focuses on experimental evidence on selected substrates, including gold- and carbon-based substrates, suggesting that lateral confinement can have pronounced effects both on the amount adsorbed and on the morphology of the aggregates as well as on a systematic study, via diverse simulation approaches, on the effect of lateral confinement on the structure of the surfactant aggregates. Atomistic and coarse-grained simulations conducted for surfactants on graphene sheets and carbon nanotubes are reviewed, as well as coarse-grained simulations for surfactant adsorption on nanostructured surfaces. Finally, we suggest a few possible extensions of these studies that could positively impact a few practical applications. In particular, the simultaneous effect of lateral confinement and of the coadsorption of molecular compounds within the surface aggregates is expected to yield interesting fundamental results with long-lasting consequences in applications ranging from drug delivery to the design of advanced materials.
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Affiliation(s)
- Alberto Striolo
- Department of Chemical Engineering University College London , London, WC1E 7JE United Kingdom
| | - Brian Patrick Grady
- School of Chemical, Biological and Materials Engineering, University of Oklahoma , Norman, Oklahoma 73019, United States
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24
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Gajula K, Gupta R, Sridhar DB, Rai B. In-Silico Skin Model: A Multiscale Simulation Study of Drug Transport. J Chem Inf Model 2017; 57:2027-2034. [PMID: 28718641 DOI: 10.1021/acs.jcim.7b00224] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Accurate in-silico models are required to predict the release of drug molecules through skin in order to supplement the in-vivo experiments for faster development/testing of drugs. The upper most layer of the skin, stratum corneum (SC), offers the main resistance for permeation of actives. Most of the SC's molecular level models comprise cholesterol and phospholipids only, which is far from reality. In this study we have implemented a multiscale modeling framework to obtain the release profile of three drugs, namely, caffeine, fentanyl, and naphthol, through skin SC. We report for the first time diffusion of drugs through a realistic skin molecular model comprised of ceramides, cholesterol, and free fatty acid. The diffusion coefficients of drugs in the SC lipid matrix were determined from multiple constrained molecular dynamics simulations. The calculated diffusion coefficients were then used in the macroscopic models to predict the release profiles of drugs through the SC. The obtained release profiles were in good agreement with available experimental data. The partition coefficient exhibits a greater effect on the release profiles. The reported multiscale modeling framework would provide insight into the delivery mechanisms of the drugs through the skin and shall act as a guiding tool in performing targeted experiments to come up with a suitable delivery system.
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Affiliation(s)
- Kishore Gajula
- Physical Sciences Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune-411013, India
| | - Rakesh Gupta
- Physical Sciences Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune-411013, India
| | - D B Sridhar
- Physical Sciences Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune-411013, India
| | - Beena Rai
- Physical Sciences Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune-411013, India
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25
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Gupta R, Dwadasi BS, Rai B. Molecular Dynamics Simulation of Skin Lipids: Effect of Ceramide Chain Lengths on Bilayer Properties. J Phys Chem B 2016; 120:12536-12546. [DOI: 10.1021/acs.jpcb.6b08059] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Rakesh Gupta
- Engineering & Physical Sciences, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services, 54B, Hadapsar Industrial Estate, Pune 411013, India
| | - Balarama Sridhar Dwadasi
- Engineering & Physical Sciences, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services, 54B, Hadapsar Industrial Estate, Pune 411013, India
| | - Beena Rai
- Engineering & Physical Sciences, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services, 54B, Hadapsar Industrial Estate, Pune 411013, India
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26
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Moore TC, Iacovella CR, Hartkamp R, Bunge AL, McCabe C. A Coarse-Grained Model of Stratum Corneum Lipids: Free Fatty Acids and Ceramide NS. J Phys Chem B 2016; 120:9944-58. [PMID: 27564869 PMCID: PMC5287476 DOI: 10.1021/acs.jpcb.6b08046] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Ceramide (CER)-based biological membranes are used both experimentally and in simulations as simplified model systems of the skin barrier. Molecular dynamics studies have generally focused on simulating preassembled structures using atomistically detailed models of CERs, which limit the system sizes and time scales that can practically be probed, rendering them ineffective for studying particular phenomena, including self-assembly into bilayer and lamellar superstructures. Here, we report on the development of a coarse-grained (CG) model for CER NS, the most abundant CER in human stratum corneum. Multistate iterative Boltzmann inversion is used to derive the intermolecular pair potentials, resulting in a force field that is applicable over a range of state points and suitable for studying ceramide self-assembly. The chosen CG mapping, which includes explicit interaction sites for hydroxyl groups, captures the directional nature of hydrogen bonding and allows for accurate predictions of several key structural properties of CER NS bilayers. Simulated wetting experiments allow the hydrophobicity of CG beads to be accurately tuned to match atomistic wetting behavior, which affects the whole system, since inaccurate hydrophobic character is found to unphysically alter the lipid packing in hydrated lamellar states. We find that CER NS can self-assemble into multilamellar structures, enabling the study of lipid systems more representative of the multilamellar lipid structures present in the skin barrier. The coarse-grained force field derived herein represents an important step in using molecular dynamics to study the human skin barrier, which gives a resolution not available through experiment alone.
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Affiliation(s)
- Timothy C. Moore
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235
- Vanderbilt University Multiscale Modeling and Simulation (MuMS) Facility, Nashville, TN 37235
| | - Christopher R. Iacovella
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235
- Vanderbilt University Multiscale Modeling and Simulation (MuMS) Facility, Nashville, TN 37235
| | - Remco Hartkamp
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235
- Vanderbilt University Multiscale Modeling and Simulation (MuMS) Facility, Nashville, TN 37235
| | - Annette L. Bunge
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401
| | - Clare McCabe
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235
- Vanderbilt University Multiscale Modeling and Simulation (MuMS) Facility, Nashville, TN 37235
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235
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27
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Gupta R, Sridhar DB, Rai B. Molecular Dynamics Simulation Study of Permeation of Molecules through Skin Lipid Bilayer. J Phys Chem B 2016; 120:8987-96. [PMID: 27518707 DOI: 10.1021/acs.jpcb.6b05451] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Stratum Corneum (SC), the outermost layer of skin, is mainly responsible for skin's barrier function. The complex lipid matrix of SC determines these barrier properties. In this study, the lipid matrix is modeled as an equimolar mixture of ceramide (CER), cholesterol (CHOL), and free fatty acid (FFA). The permeation of water, oxygen, ethanol, acetic acid, urea, butanol, benzene, dimethyl sulfoxide (DMSO), toluene, phenol, styrene, and ethylbenzene across this layer is studied using a constrained MD simulations technique. Several long constrained simulations are performed at a skin temperature of 310 K under NPT conditions. The free energy profiles and diffusion coefficients along the bilayer normal have been calculated for each molecule. Permeability coefficients are also calculated and compared with experimental data. The main resistance for the permeation of hydrophilic and hydrophobic permeants has been found to be in the interior of the lipid bilayer and near the lipid-water interface, respectively. The obtained permeability is found to be a few orders of magnitude higher than experimental values for hydrophilic molecules while for hydrophobic molecules more discrepancy was observed. Overall, the qualitative ranking is consistent with the experiments.
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Affiliation(s)
- Rakesh Gupta
- Physical Science Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune - 411013, India
| | - D B Sridhar
- Physical Science Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune - 411013, India
| | - Beena Rai
- Physical Science Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune - 411013, India
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28
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Das C, Olmsted PD. The physics of stratum corneum lipid membranes. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:rsta.2015.0126. [PMID: 27298438 PMCID: PMC4920276 DOI: 10.1098/rsta.2015.0126] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/15/2016] [Indexed: 05/22/2023]
Abstract
The stratum corneum (SC), the outermost layer of skin, comprises rigid corneocytes (keratin-filled dead cells) in a specialized lipid matrix. The continuous lipid matrix provides the main barrier against uncontrolled water loss and invasion of external pathogens. Unlike all other biological lipid membranes (such as intracellular organelles and plasma membranes), molecules in the SC lipid matrix show small hydrophilic groups and large variability in the length of the alkyl tails and in the numbers and positions of groups that are capable of forming hydrogen bonds. Molecular simulations provide a route for systematically probing the effects of each of these differences separately. In this article, we present the results from atomistic molecular dynamics of selected lipid bilayers and multi-layers to probe the effect of these polydispersities. We address the nature of the tail packing in the gel-like phase, the hydrogen bond network among head groups, the bending moduli expected for leaflets comprising SC lipids and the conformation of very long ceramide lipids in multi-bilayer lipid assemblies.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'.
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Affiliation(s)
- Chinmay Das
- School of Mathematics, University of Leeds, Leeds LS2 9JT, UK
| | - Peter D Olmsted
- Department of Physics and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057, USA
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29
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Akinshina A, Das C, Noro MG. Effect of monoglycerides and fatty acids on a ceramide bilayer. Phys Chem Chem Phys 2016; 18:17446-60. [PMID: 27302426 DOI: 10.1039/c6cp01238h] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Monoglycerides and unsaturated fatty acids, naturally present in trace amounts in the stratum corneum (top layer of skin) lipid matrix, are commonly used in pharmaceutical, cosmetic and health care formulations. However, a detailed molecular understanding of how the oil additives get incorporated into the skin lipids from topical application and, once incorporated, how they affect the properties and integrity of the lipid matrix remains unexplored. Using ceramide 2 bilayers as skin lipid surrogates, we use a series of molecular dynamics simulations with six different natural oil ingredients at multiple concentrations to investigate the effect of the oils on the properties and stability of the bilayers. The six oils: monoolein, monostearin, monoelaidin, oleic acid, stearic acid and linoleic acid - all having the same length of the alkyl chain, C18, but a varying degree of saturation, allow us to systematically address the effect of unsaturation in the additives. Our results show that at low oil concentration (∼5%) the mixed bilayers containing any of the oils and ceramide 2 (CER2) become more rigid than pure CER2 bilayers due to more efficient lipid packing. Better packing also results in the formation of larger numbers of hydrogen bonds between the lipids, which occurs at the expense of the hydrogen bonds between lipids and water. The mixed bilayers with saturated or trans-unsaturated oils remain stable over the whole range of oil concentration. In contrast, the presence of the oils with at least one cis-double bond leads to bilayer instability and complete loss of bilayer structure at the oil content of about 50-65%. Two cis-double bonds in the lipid tail induce bilayer disruption at even lower concentration (∼30%). The mixed bilayers remain in the gel phase (without melting to a fluid phase) until the phase transition to a non-bilayer phase occurs. We also demonstrate that the stability of the bilayer strongly correlates with the order parameter of the lipid tails.
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Affiliation(s)
- Anna Akinshina
- Institute of Skin Integrity and Infection Prevention, School of Human and Health Sciences, University of Huddersfield, HD1 3DH, Huddersfield, UK.
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30
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Gupta R, Rai B. Molecular Dynamics Simulation Study of Skin Lipids: Effects of the Molar Ratio of Individual Components over a Wide Temperature Range. J Phys Chem B 2015; 119:11643-55. [DOI: 10.1021/acs.jpcb.5b02093] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rakesh Gupta
- Tata Research Development
and Design Centre, Tata Consultancy Services, 54B, Hadapsar Industrial Estate, Pune - 411013, India
| | - Beena Rai
- Tata Research Development
and Design Centre, Tata Consultancy Services, 54B, Hadapsar Industrial Estate, Pune - 411013, India
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31
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MacDermaid CM, DeVane RH, Klein ML, Fiorin G. Dehydration of multilamellar fatty acid membranes: towards a computational model of the stratum corneum. J Chem Phys 2015; 141:22D526. [PMID: 25494797 DOI: 10.1063/1.4902363] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The level of hydration controls the cohesion between apposed lamellae of saturated free fatty acids found in the lipid matrix of stratum corneum, the outermost layer of mammalian skin. This multilamellar lipid matrix is highly impermeable to water and ions, so that the local hydration shell of its fatty acids may not always be in equilibrium with the acidity and relative humidity, which significantly change over a course of days during skin growth. The homeostasis of the stratum corneum at each moment of its growth likely requires a balance between two factors, which affect in opposite ways the diffusion of hydrophilic species through the stratum corneum: (i) an increase in water order as the lipid lamellae come in closer contact, and (ii) a decrease in water order as the fraction of charged fatty acids is lowered by pH. Herein molecular dynamics simulations are employed to estimate the impact of both effects on water molecules confined between lamellae of fatty acids. Under conditions where membrane undulations are energetically favorable, the charged fatty acids are able to sequester cations around points of contact between lamellae that are fully dehydrated, while essentially maintaining a multilamellar structure for the entire system. This observation suggests that the undulations of the fatty acid lamellae control the diffusion of hydrophilic species through the water phase by altering the positional and rotational order of water molecules in the embedded/occluded "droplets."
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Affiliation(s)
- Christopher M MacDermaid
- Institute for Computational Molecular Science, SERC Building (035-07), Temple University, 1925 North 12th Street, Philadelphia, Pennsylvania 19122, USA
| | - Russell H DeVane
- Modeling and Simulation, Corporate Research and Development, The Procter and Gamble Company, West Chester, Ohio 45069, USA
| | - Michael L Klein
- Institute for Computational Molecular Science, SERC Building (035-07), Temple University, 1925 North 12th Street, Philadelphia, Pennsylvania 19122, USA
| | - Giacomo Fiorin
- Institute for Computational Molecular Science, SERC Building (035-07), Temple University, 1925 North 12th Street, Philadelphia, Pennsylvania 19122, USA
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32
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Koumakis N, Moghimi E, Besseling R, Poon WCK, Brady JF, Petekidis G. Tuning colloidal gels by shear. SOFT MATTER 2015; 11:4640-4648. [PMID: 25962849 DOI: 10.1039/c5sm00411j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Using a powerful combination of experiments and simulations we demonstrate how the microstructure and its time evolution are linked with mechanical properties in a frustrated, out-of-equilibrium, particle gel under shear. An intermediate volume fraction colloid-polymer gel is used as a model system, allowing quantification of the interplay between interparticle attractions and shear forces. Rheometry, confocal microscopy and Brownian dynamics reveal that high shear rates, fully breaking the structure, lead after shear cessation to more homogeneous and stronger gels, whereas preshear at low rates creates largely heterogeneous weaker gels with reduced elasticity. We find that in comparison, thermal quenching cannot produce structural inhomogeneities under shear. We argue that external shear has strong implications on routes towards metastable equilibrium, and therefore gelation scenarios. Moreover, these results have strong implications for material design and industrial applications, such as mixing, processing and transport protocols coupled to the properties of the final material.
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Affiliation(s)
- Nick Koumakis
- FORTH/IESL and Department of Materials Science and Technology, University of Crete, 71110 Heraklion, Greece.
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33
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Sovová Ž, Berka K, Otyepka M, Jurečka P. Coarse-grain simulations of skin ceramide NS with newly derived parameters clarify structure of melted phase. J Phys Chem B 2015; 119:3988-98. [PMID: 25679231 DOI: 10.1021/jp5092366] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ceramides are lipids that are involved in numerous biologically important structures (e.g., the stratum corneum and ceramide-rich platforms) and processes (e.g., signal transduction and membrane fusion), but their behavior is not fully understood. We report coarse-grain force field parameters for N-lignocerylsphingosine (ceramide NS, also known as ceramide 2) that are consistent with the Martini force field. These parameters were optimized for simulations in the gel phase and validated against atomistic simulations. Coarse-grained simulations with our parameters provide areas per lipid, membrane thicknesses, and electron density profiles that are in good agreement with atomistic simulations. Properties of the simulated membranes are compared with available experimental data. The obtained parameters were used to model the phase behavior of ceramide NS as a function of temperature and hydration. At low water content and above the main phase transition temperature, the bilayer melts into an irregular phase, which may correspond to the unstructured melted-chain phase observed in X-ray diffraction experiments. The developed parameters also reproduce the extended conformation of ceramide, which may occur in the stratum corneum. The parameters presented herein will facilitate studies on important complex functional structures such as the uppermost layer of the skin and ceramide-rich platforms in phospholipid membranes.
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Affiliation(s)
- Žofie Sovová
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University , 17 Listopadu 12, 77146 Olomouc, Czech Republic
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34
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Williamson JJ, Evans RML. Measuring local volume fraction, long-wavelength correlations, and fractionation in a phase-separating polydisperse fluid. J Chem Phys 2014; 141:164901. [PMID: 25362335 DOI: 10.1063/1.4897560] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Affiliation(s)
- J. J. Williamson
- Department of Physics, Institute for Soft Matter Synthesis and Metrology, Georgetown University, 37th and O Streets, N.W., Washington, D.C. 20057, USA
| | - R. M. L. Evans
- School of Mathematics, University of Leeds, Leeds LS2 9JT, United Kingdom
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35
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Das C, Noro MG, Olmsted PD. Fast cholesterol flip-flop and lack of swelling in skin lipid multilayers. SOFT MATTER 2014; 10:7346-7352. [PMID: 25079959 DOI: 10.1039/c4sm01161a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Atomistic simulations were performed on hydrated model lipid multilayers that are representative of the lipid matrix in the outer skin (stratum corneum). We find that cholesterol transfers easily between adjacent leaflets belonging to the same bilayer via fast orientational diffusion (tumbling) in the inter-leaflet disordered region, while at the same time there is a large free energy cost against swelling. This fast flip-flop may play an important role in accommodating the variety of curvatures that would be required in the three dimensional arrangement of the lipid multilayers in skin, and for enabling mechanical or hydration induced strains without large curvature elastic costs.
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Affiliation(s)
- Chinmay Das
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK.
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