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Darvin ME. Optical Methods for Non-Invasive Determination of Skin Penetration: Current Trends, Advances, Possibilities, Prospects, and Translation into In Vivo Human Studies. Pharmaceutics 2023; 15:2272. [PMID: 37765241 PMCID: PMC10538180 DOI: 10.3390/pharmaceutics15092272] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/19/2023] [Accepted: 08/24/2023] [Indexed: 09/29/2023] Open
Abstract
Information on the penetration depth, pathways, metabolization, storage of vehicles, active pharmaceutical ingredients (APIs), and functional cosmetic ingredients (FCIs) of topically applied formulations or contaminants (substances) in skin is of great importance for understanding their interaction with skin targets, treatment efficacy, and risk assessment-a challenging task in dermatology, cosmetology, and pharmacy. Non-invasive methods for the qualitative and quantitative visualization of substances in skin in vivo are favored and limited to optical imaging and spectroscopic methods such as fluorescence/reflectance confocal laser scanning microscopy (CLSM); two-photon tomography (2PT) combined with autofluorescence (2PT-AF), fluorescence lifetime imaging (2PT-FLIM), second-harmonic generation (SHG), coherent anti-Stokes Raman scattering (CARS), and reflectance confocal microscopy (2PT-RCM); three-photon tomography (3PT); confocal Raman micro-spectroscopy (CRM); surface-enhanced Raman scattering (SERS) micro-spectroscopy; stimulated Raman scattering (SRS) microscopy; and optical coherence tomography (OCT). This review summarizes the state of the art in the use of the CLSM, 2PT, 3PT, CRM, SERS, SRS, and OCT optical methods to study skin penetration in vivo non-invasively (302 references). The advantages, limitations, possibilities, and prospects of the reviewed optical methods are comprehensively discussed. The ex vivo studies discussed are potentially translatable into in vivo measurements. The requirements for the optical properties of substances to determine their penetration into skin by certain methods are highlighted.
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Choe C, Schleusener J, Ri J, Choe S, Kim P, Lademann J, Darvin ME. Quantitative determination of concentration profiles of skin components and topically applied oils by tailored multivariate curve resolution-alternating least squares using in vivo confocal Raman micro-spectroscopy. JOURNAL OF BIOPHOTONICS 2023; 16:e202200219. [PMID: 36106843 DOI: 10.1002/jbio.202200219] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 09/01/2022] [Accepted: 09/12/2022] [Indexed: 06/15/2023]
Abstract
The main components of the stratum corneum (SC), water, lipids, and proteins, are non-homogeneously distributed throughout the depth. The quantitative determination of their concentration profiles and penetration depth of topically applied substances are urgent topics of dermatological and cosmetic research. Confocal Raman micro-spectroscopy has distinct advantages when determining semi-quantitative concentrations of SC components and topically applied substances non-invasively and in vivo. In this work, we applied a tailored multivariate curve resolution-alternating least squares (tMCR-ALS) method to analyze Raman spectra of the SC in the 2000-4000 cm-1 region for quantitatively determining the concentrations of water, lipids, proteins, and topically applied oils using substance-related spectral loadings which were allowed to change depth-dependently from the SC's surface toward its bottom. tMCR-ALS makes matching of depth-dependent signal attenuation, that is, the normalization on keratin, unnecessary and requires only a few additional experiments for calibration - Raman spectra of the pure materials and their densities.
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Affiliation(s)
- ChunSik Choe
- Biomedical Materials Division, Faculty of Material Science, Kim Il Sung University, Pyongyang, Democratic People's Republic of Korea
| | - Johannes Schleusener
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - JinSong Ri
- Biomedical Materials Division, Faculty of Material Science, Kim Il Sung University, Pyongyang, Democratic People's Republic of Korea
| | - SeHyok Choe
- Biomedical Materials Division, Faculty of Material Science, Kim Il Sung University, Pyongyang, Democratic People's Republic of Korea
- Clinical Research Division, Pyongyang Cosmetic Research Institute, Pyongyang, Democratic People's Republic of Korea
| | - PokSil Kim
- Clinical Research Division, Pyongyang Cosmetic Research Institute, Pyongyang, Democratic People's Republic of Korea
| | - Jürgen Lademann
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Maxim E Darvin
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
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Fluhr JW, Tfayli A, Darlenski R, Darvin ME, Joly-Tonetti N, Lachmann N. Glycerol and natural sugar-derived complex modulate differentially stratum corneum water-binding properties and structural parameters in an in vitro Raman-desorption model. JOURNAL OF BIOPHOTONICS 2023; 16:e202200201. [PMID: 36153668 DOI: 10.1002/jbio.202200201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/21/2022] [Accepted: 09/22/2022] [Indexed: 06/16/2023]
Abstract
The epidermal protective functions are closely associated with skin hydration homeostasis. The understanding of different states of water binding is a rising concept in assessing topically applied formulations and their interaction within the stratum corneum (SC). In addition to global water content, primary bound water, partially bound water, and unbound water and barrier-related lipid lateral packing and protein secondary structure can be measured by Raman spectroscopy. This study aimed to establish an in vitro SC model to evaluate differences in the efficacy of a natural sugar-derived complex in combination with glycerol and a botanical extract in modulating SC water binding and structural proteins and barrier lipids. These compounds were selected due to their water-binding and soothing properties. The SC water profiles were assessed at the surface and in 8 μm SC depth. After a 12-hour hyperhydration and subsequent product incubation the measurements were performed during a 6 hours desiccation phase. The maximal water caption and the time until reaching a steady state are measured as well as water retention and resistance against water loss. Global water content, partially bound, and unbound water, as well as lipid and protein structures were assessed with confocal Raman microspectroscopy. Both the natural sugar-derived mixture and more pronounced, the same mixture with additional glycerol increased all three water-binding parameters at the surface and in 8 μm SC depth at the beginning and during the desiccation phase. Further addition of botanical extract did not result in an additional increase of the water-binding. All three formulations showed an increase in the lipid lateral packing values prevented the protein alteration as measured by β-sheets signal compared to blank. The present model is suited for screening studies comparing the specific effects of different compounds on hydration states. The natural sugar-derived mixture Aquaxyl showed evidence for an improvement of all SC hydration states, lipid and protein structure which was further enhanced by the addition of glycerol 5%. This improvement was evidenced at the surface and within the SC for all hydration-related parameters, and the lipid as well the protein structures. The addition of botanical extract phytoessence blue daisy did not show further improvement.
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Affiliation(s)
- Joachim W Fluhr
- Charité-Universitätsmedizin Berlin, Institute of Allergology, Berlin, Germany
- Allergology and Immunology, Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Berlin, Germany
| | - Ali Tfayli
- Lipides: Systèmes Analytiques et Biologiques, Lip(Sys)2, Faculty of Pharmacy, Paris-Saclay University, Orsay, France
| | - Razvigor Darlenski
- Department of Dermatology and Venereology, Acibadem City Clinic Tokuda Hospital-Sofia, Sofia, Bulgaria
- Department of Dermatology and Venereology, Medical Faculty, Trakia University-Stara Zagora, Stara Zagora, Bulgaria
| | - Maxim E Darvin
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology (CCP), Charité-Universitätsmedizin Berlin, Berlin, Germany
- Freie Universität Berlin, Berlin, Germany
- Humboldt-Universität zu Berlin, Berlin, Germany
| | | | - Nadège Lachmann
- Scientific and Claims Development, Galderma SA, Lausanne, Switzerland
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Choe C, Schleusener J, Choe S, Ri J, Lademann J, Darvin ME. Stratum corneum occlusion induces water transformation towards lower bonding state: a molecular level in vivo study by confocal Raman microspectroscopy. Int J Cosmet Sci 2020; 42:482-493. [PMID: 32692411 DOI: 10.1111/ics.12653] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/15/2020] [Accepted: 07/17/2020] [Indexed: 12/23/2022]
Abstract
OBJECTIVE It is conventionally understood that occlusive effects are the retention of excessive water in the stratum corneum (SC), the increase of SC thickness (swelling) and a decrease of the transepidermal water loss. However, the influence of occlusion on water binding properties in the SC is unknown. METHODS The action of plant-derived jojoba and almond oils, as well as mineral-derived paraffin oil and petrolatum topically applied on human skin, is investigated in vivo using confocal Raman microspectroscopy. To understand the oils' influence on the SC on the molecular level, the depth-dependent hydrogen bonding states of water in the SC and their relationship to the conformation of keratin, concentration of natural moisturizing factor (NMF) molecules and lipid organization were investigated. RESULTS A significant SC swelling was observed only in petrolatum-treated skin. The water concentration was increased in oil-treated skin in the intermediate SC region (40-70% SC depth). Meanwhile, the amount of free, weakly and tightly bound water increased, and strongly bound water decreased in the uppermost SC region (0-30% SC depth). The NMF concentration of oil-treated skin was significantly lower at 50-70% SC depth. The lateral organization of lipids in oil-treated skin was lower at 0-30% SC depth. The secondary structure of keratin was changed towards an increase of β-sheet content in mineral-derived oil-treated skin and changed towards an increase of α-helix content in plant-derived oil-treated skin. CONCLUSION The occlusive properties can be summarized as the increase of free water and the transformation of water from a more strongly to a more weakly hydrogen bonding state in the uppermost SC, although some oils cause insignificant changes of the SC thickness. The accompanied changes in the keratin conformation at the intermediate swelling region of the SC also emphasize the role of keratin in the SC's water-transporting system, that is the water in the SC transports intercellularly and intracellularly in the intermediate swelling region and only intercellularly in the uppermost non-swelling region. Bearing this in mind, almond, jojoba and paraffin oils, which are not occlusive from the conventional viewpoint, have an occlusion effect similar to petrolatum on the SC.
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Affiliation(s)
- C Choe
- Kim Il Sung University, Taesong District, Ryongnam-Dong, Pyongyang, DPR Korea
| | - J Schleusener
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Charitéplatz 1, Berlin, 10117, Germany
| | - S Choe
- Kim Il Sung University, Taesong District, Ryongnam-Dong, Pyongyang, DPR Korea
| | - J Ri
- Kim Il Sung University, Taesong District, Ryongnam-Dong, Pyongyang, DPR Korea
| | - J Lademann
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Charitéplatz 1, Berlin, 10117, Germany
| | - M E Darvin
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Charitéplatz 1, Berlin, 10117, Germany
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