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Mijaljica D, Townley JP, Spada F, Harrison IP. The heterogeneity and complexity of skin surface lipids in human skin health and disease. Prog Lipid Res 2024; 93:101264. [PMID: 37940006 DOI: 10.1016/j.plipres.2023.101264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 10/27/2023] [Accepted: 11/02/2023] [Indexed: 11/10/2023]
Abstract
The outermost epidermal layer of the skin, the stratum corneum, is not simply a barrier that safeguards skin integrity from external insults and invaders, it is also a delicately integrated interface composed of firm, essentially dead corneocytes and a distinctive lipid matrix. Together, the stratum corneum lipid matrix and sebum lipids derived from sebaceous glands give rise to a remarkably complex but quite unique blend of skin surface lipids that demonstrates tremendous heterogeneity and provides the skin with its indispensable protective coating. The stratum corneum lipid matrix is composed primarily of three major lipid classes: ceramides, non-esterified fatty acids and cholesterol, whereas sebum is a waxy mixture predominantly composed of acylglycerols, wax esters, non-esterified fatty acids, squalene, cholesterol and cholesterol esters. The balance of these skin surface lipids in terms of their relative abundance, composition, molecular organisation and dynamics, and their intricate interactions play a crucial role in the maintenance of healthy skin. For that reason, even minuscule alterations in skin surface lipid properties or overall lipid profile have been implicated in the aetiology of many common skin diseases including atopic dermatitis, psoriasis, xerosis, ichthyosis and acne. Novel lipid-based interventions aimed at correcting the skin surface lipid abnormalities have the potential to repair skin barrier integrity and the symptoms associated with such skin diseases, even though the exact mechanisms of lipid restoration remain elusive.
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Affiliation(s)
- Dalibor Mijaljica
- Department of Scientific Affairs, Ego Pharmaceuticals Pty Ltd, 21-31 Malcolm Road, Braeside, Victoria 3195, Australia.
| | - Joshua P Townley
- Department of Scientific Affairs, Ego Pharmaceuticals Pty Ltd, 21-31 Malcolm Road, Braeside, Victoria 3195, Australia.
| | - Fabrizio Spada
- Department of Scientific Affairs, Ego Pharmaceuticals Pty Ltd, 21-31 Malcolm Road, Braeside, Victoria 3195, Australia.
| | - Ian P Harrison
- Department of Scientific Affairs, Ego Pharmaceuticals Pty Ltd, 21-31 Malcolm Road, Braeside, Victoria 3195, Australia.
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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: 1] [Impact Index Per Article: 1.0] [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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Gupta KM, Das S, Wong ABH, Chow PS. Formulation and Skin Permeation of Active-Loaded Lipid Nanoparticles: Evaluation and Screening by Synergizing Molecular Dynamics Simulations and Experiments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:308-319. [PMID: 36573314 DOI: 10.1021/acs.langmuir.2c02550] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Encapsulation into nanoparticles (NPs) is a potential method to deliver pharmaceutical/cosmetic actives deep into the skin. However, understanding the NP formulations and underlying mechanism of active delivery to skin has scarcely been studied. We report a simulation platform that screens, evaluates, formulates, and provides atomic-resolution interpretation of NP-based formulations, and reveals the active permeation mechanism from NPs to skin. First, three actives, namely, ferulic acid (FA), clotrimazole (CZE), and tretinoin (TTN), and five lipid excipients' (Compritol, Precirol, Geleol, Gelot, Gelucire) combinations were screened by MD simulations for the best pairs. For each suggested pair, the actual active and lipid compositions for the synthesis of stable NP formulations were then obtained by experiments. MD simulations demonstrate that in NP formulations, FA and CZE actives are present at the surface of the NPs, whereas TTN actives are present at both the surface and interior of the NP core. The NP shapes obtained by simulation perfectly match with experiments. For each NP, separate MD simulations illustrate that active-loaded NPs approach the skin surface quickly, and then actives translocate from NP surface to skin surface followed by penetration of NPs through skin. The driving force for the translocation which initiates during the penetration process, is the stronger active-skin interaction compared to active-NP interaction. Permeation free energy indicates spontaneous transfer of actives from solution phase to the surface of the skin bilayer. The free energy barriers are increased in the order of FA < TTN < CZE. Significantly lower diffusions of actives are obtained in the main barrier region compared to bulk, and the average diffusion coefficients of actives are in the same order of magnitude (∼10-6 cm2/s). The estimated permeability coefficients (log P) of actives are mainly governed by free energy barriers. The study would facilitate the development of novel lipid-based NP formulations for personal-care/pharmaceutical applications.
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Affiliation(s)
- Krishna M Gupta
- Institute of Sustainability for Chemicals, Energy and Environment, A*STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island627833, Singapore
| | - Surajit Das
- Institute of Sustainability for Chemicals, Energy and Environment, A*STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island627833, Singapore
| | - Annie B H Wong
- Institute of Sustainability for Chemicals, Energy and Environment, A*STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island627833, Singapore
| | - Pui Shan Chow
- Institute of Sustainability for Chemicals, Energy and Environment, A*STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island627833, Singapore
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HPLC Method for Separation of Cannabidiol Hemp Seed Oil with Skin Lipids and Tandem HRMS Technology for Characterization of a Chemical Marker. COSMETICS 2021. [DOI: 10.3390/cosmetics8040108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Cannabidiol (CBD) hemp seed oil is a commercial raw material with antioxidant and anti-inflammatory benefits that has been formulated into body wash and skin care products. The biggest analytical challenge is how to simultaneously quantify CBD and hemp seed oil as they deposited on the skin surface. CBD is easily separated and quantified from skin surface extracts via a HPLC-mass spectrometry methodology. However, the structural skeleton of triacylglycerides (TAGs) in hemp seed oil is same as those from the skin surface sebum. The strong hydrophobicity with subtle structural difference challenges their separation. In this project, a new reverse phase HPLC-high resolution mass spectrometry methodology was developed with a strong mobile phase normal propanol. The separated hemp seed oil TAGs in the chromatogram were identified and characterized using data-dependent acquisition (DDA) technology. Based on the daughter ion characterization, the separated peak with an ammonium adduct at 890.7226 [M + NH4]+ was confirmed as the parent ion of glycerol with three omega-3 fatty acid chains. This is the first time TAG structure with direct HPLC-tandem mass spectrometry technology has been elucidated without a hydrolysis reaction. The confirmed TAG structure with an ammonium adduct at 890.7226 ± 0.0020 can be used as a representative chemical marker for the hemp seed oil quantification.
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Domingo M, Faraudo J. Interaction between SARS-CoV-2 spike glycoprotein and human skin models: a molecular dynamics study. SOFT MATTER 2021; 17:9457-9468. [PMID: 34612290 DOI: 10.1039/d1sm01026c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The possibility of contamination of human skin by infectious virions plays an important role in indirect transmission of respiratory viruses but little is known about the fundamental physico-chemical aspects of the virus-skin interactions. In the case of coronaviruses, the interaction with surfaces (including the skin surface) is mediated by their large glycoprotein spikes that protrude from (and cover) the viral envelope. Here, we perform all atomic simulations between the SARS-CoV-2 spike glycoprotein and human skin models. We consider an "oily" skin covered by sebum and a "clean" skin exposing the stratum corneum. The simulations show that the spike tries to maximize the contacts with stratum corneum lipids, particularly ceramides, with substantial hydrogen bonding. In the case of "oily" skin, the spike is able to retain its structure, orientation and hydration over sebum with little interaction with sebum components. Comparison of these results with our previous simulations of the interaction of SARS-CoV-2 spike with hydrophilic and hydrophobic solid surfaces, suggests that the "soft" or "hard" nature of the surface plays an essential role in the interaction of the spike protein with materials.
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Affiliation(s)
- Marc Domingo
- Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, E-08193 Bellaterra, Barcelona, Spain.
| | - Jordi Faraudo
- Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, E-08193 Bellaterra, Barcelona, Spain.
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Gupta KM, Das S, Chow PS. Molecular dynamics simulations to elucidate translocation and permeation of active from lipid nanoparticle to skin: complemented by experiments. NANOSCALE 2021; 13:12916-12928. [PMID: 34477775 DOI: 10.1039/d1nr02652f] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
One of the most realistic approaches for delivering actives (pharmaceuticals/cosmetics) deep into skin layers is encapsulation into nanoparticles (NPs). Nonetheless, molecular-level mechanisms related to active delivery from NPs to the skin have scarcely been studied despite the large number of synthesis and characterization studies. We herein report the underlying mechanism of active translocation and permeation through the outermost layer of skin, the stratum corneum (SC), via molecular dynamics (MD) simulations complemented by experimental studies. A SC molecular model is constructed using current state-of-the-art methodology via incorporating the three most abundant skin lipids: ceramides, free fatty acids, and cholesterol. As a potent antioxidant, ferulic acid (FA) is used as the model active, and it is loaded into Gelucire 50/13 NP. MD simulations elucidate that, first, FA-loaded NP approaches the skin surface quickly, followed by slight penetration and adsorption onto the upper skin surface; FA then translocates from the NP surface to the skin surface due to stronger NP-skin interactions compared to the FA-NP interactions; then, once FA is released onto the skin surface, it slowly permeates deep into the skin bilayer. Both the free energy and resistance to permeation not only indicate the spontaneous transfer of FA from the bulk to the skin surface, but they also reveal that the main barrier against permeation exists in the middle of the lipid hydrophobic tails. Significantly lower diffusion of FA is obtained in the main barrier region compared to the bulk. The estimated permeability coefficient (log P) values are found to be higher than the experimental values. Importantly, the permeation process evaluated via MD simulations perfectly matches with experiments. The study suggests a molecular simulation platform that provides various crucial insights relating to active delivery from loaded NP to skin, and it could facilitate the design and development of novel NP-based formulations for transdermal delivery and the topical application of drugs/cosmetics.
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Affiliation(s)
- Krishna M Gupta
- Institute of Chemical & Engineering Sciences, A*STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, Singapore 627833.
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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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Pink DL, Loruthai O, Ziolek RM, Wasutrasawat P, Terry AE, Lawrence MJ, Lorenz CD. On the Structure of Solid Lipid Nanoparticles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1903156. [PMID: 31532892 DOI: 10.1002/smll.201903156] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/22/2019] [Indexed: 06/10/2023]
Abstract
Solid lipid nanoparticles (SLNs) have a crystalline lipid core which is stabilized by interfacial surfactants. SLNs are considered favorable candidates for drug delivery vehicles since their ability to store and release organic molecules can be tailored through the identity of the lipids and surfactants used. When stored, polymorphic transitions in the core of drug-loaded SLNs lead to the premature release of drug molecules. Significant experimental studies have been conducted with the aim of investigating the physicochemical properties of SLNs, however, no molecular scale investigations have been reported on the behaviors that drive SLN formation and their polymorphic transitions. A combination of small angle neutron scattering and all-atom molecular dynamics simulations is therefore used to yield a detailed atomistic description of the internal structure of an SLN comprising triglyceride, tripalmitin, and the nonionic surfactant, Brij O10 (C18:1 E10 ). The molecular scale mechanisms by which the surfactants stabilize the crystalline structure of the SLN lipid core are uncovered. By comparing these results to simulated liquid and solid aggregates of tripalmitin lipids, how the morphology of the lipids vary between these systems is demonstrated providing further insight into the mechanisms that control drug encapsulation and release from SLNs.
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Affiliation(s)
- Demi L Pink
- Department of Physics, King's College London, London, WC2R 2LS, UK
| | - Orathai Loruthai
- Pharmaceutical Biophysics Group, Institute of Pharmaceutical Science, King's College London, London, SW1 9NH, UK
| | - Robert M Ziolek
- Department of Physics, King's College London, London, WC2R 2LS, UK
| | - Prawarisa Wasutrasawat
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Ann E Terry
- CoSAXS Beamline, MAX IV Laboratory, Lund University, SE-221 00, Lund, Sweden
| | - M Jayne Lawrence
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester, M13 9PT, UK
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