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Kuroda A, Sakai K, Yahagi S, Mukawa T, Sato N, Nakamura N, Maezawa D, Masaki H, Banno T, Asakura K. Surface Structures of Cosmetic Standard Poly Methyl Methacrylate UV Evaluation Plates and their Influence on the in vitro Evaluation of UV Protection Abilities of Cosmetic Sunscreens. J Oleo Sci 2019; 68:175-182. [PMID: 30651410 DOI: 10.5650/jos.ess18207] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cosmetic standard poly methyl methacrylate (PMMA) UV evaluation plates, i.e., roughened PMMA plates, are used in the EU and the US for the in vitro evaluation of UV protection abilities of sunscreen, such as in vitro UVA-PF and critical wavelength for the Broad-spectrum approval. In our previous studies, inhomogeneity in the thickness of a pseudo-sunscreen layer applied on a flat quartz plate was observed to alter UV transmission. Thus, the surface roughness of the standard plates should have a significant influence on the in vitro evaluation. In the present study, we have analyzed the surface structures of three cosmetic standard PMMA UV evaluation plates: Helioplates HD6 (Sa = 6 µm) and ISO plates (Ra = 2 and 5 µm). A decamethylcyclopentasiloxane and 2-propanol-mixed solvent solution of acrylsilicone resin was prepared, and the solution was added dropwise onto the plates. After the evaporation of the solvents, the plates were cut and the cross section was analyzed using SEM-EDS. The distribution of silicon atoms at the cross-section suggested that the maximum depth of penetrating of acrylsilicone resin was larger than Ra for all the standard plates, and the surface structure was significantly different for each standard plate. In addition, cracks into which the acrylsilicone resin deeply penetrated were observed on the surface of some plates. Clear-solution-type pseudo-sunscreen samples in which UV absorbers and acrylsilicone resin were dissolved were deposited on the standard roughened PMMA plates. It was observed that the addition of acrylsilicone resin drastically changed the net UV transmission. The degree to which the hollows of the roughened surface were filled with the pseudo-sunscreen samples determined the variation of UV transmittance.
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Affiliation(s)
- Akihiro Kuroda
- Yokohama Research Center, Kuroda Consulting Inc.,Department of Applied Chemistry, Keio University
| | - Karin Sakai
- Department of Applied Chemistry, Keio University
| | - Shoichi Yahagi
- Department of Efficacy and Safety Evaluation, NIKKOL Group Cosmos Technical Center Co., LTD
| | | | | | | | - Daisuke Maezawa
- Department of Applied Chemistry, Keio University.,R & D Center, Para Hermosa Co., Ltd
| | - Hitoshi Masaki
- School of Bioscience and Biotechnology, Tokyo University of Technology
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da Silva Souza ID, Berkowitz E, Chea JD, McBride N, Sweet K, Torri D, Burgo RV, Savelski MJ, Stanzione JF. Efficient UV Filter Solubilizers Prevent Recrystallization Favoring Accurate and Safe Sun Protection. ACS APPLIED MATERIALS & INTERFACES 2018; 10:40411-40423. [PMID: 30395433 DOI: 10.1021/acsami.8b14204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Sun protection is a global concern, and maximizing sunscreen stability and efficacy depends partially on the prevention of UV filters recrystallization. We aimed to study the efficacy of hydrophobic solubilizers in preventing the recrystallization of solid hydrophobic UV filters in predissolutions, sunscreen formulations, and during simulated human use. Recrystallization of UV filters induced by ultrasonication, temperature variation, or simulated human application was analyzed by different methods. Maximum solubility of UV filters in solubilizers was determined. Surprisingly, the best solubilizer was not necessarily the best solvent to prevent recrystallization, suggesting there are different forces controlling these phenomena. Hydrophobic solubilizers tend to perform better than ethanol in predissolutions, but the presence of other components in final products may change their performance. Results suggest that some UV filters tend to form liquid clusters, which may behave as crystals and affect the desired even distribution of UV filters on the skin. UV filters were also found to respond differently to Hansen Solubility Parameters. Scanning electron microscopy supports the fact that recrystallization upon sunscreen application is an issue to be tested during development. A timesaving method to predict recrystallization of UV filters in clear systems was developed and is presented as a tool to enhance the efficacy of sunscreens.
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Affiliation(s)
- Ivan D da Silva Souza
- Department of Chemical Engineering , Rowan University , 201 Mullica Hill Road , Glassboro , New Jersey 08028-1701 , United States
| | - Emma Berkowitz
- Department of Chemical Engineering , Rowan University , 201 Mullica Hill Road , Glassboro , New Jersey 08028-1701 , United States
| | - John D Chea
- Department of Chemical Engineering , Rowan University , 201 Mullica Hill Road , Glassboro , New Jersey 08028-1701 , United States
| | - Nicholas McBride
- Department of Chemical Engineering , Rowan University , 201 Mullica Hill Road , Glassboro , New Jersey 08028-1701 , United States
| | - Kayla Sweet
- Department of Chemical Engineering , Rowan University , 201 Mullica Hill Road , Glassboro , New Jersey 08028-1701 , United States
| | - Daniel Torri
- Department of Chemical Engineering , Rowan University , 201 Mullica Hill Road , Glassboro , New Jersey 08028-1701 , United States
| | - Rocco V Burgo
- Department of Research and Development , INOLEX Inc. , 2101 South Swanson Street , Philadelphia , Pennsylvania 19148-3497 , United States
| | - Mariano J Savelski
- Department of Chemical Engineering , Rowan University , 201 Mullica Hill Road , Glassboro , New Jersey 08028-1701 , United States
| | - Joseph F Stanzione
- Department of Chemical Engineering , Rowan University , 201 Mullica Hill Road , Glassboro , New Jersey 08028-1701 , United States
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Wakabayashi M, Okano K, Mukawa T, Maezawa D, Masaki H, Kuroda A, Asakura K. Problems on the Evaluation of the Critical Wavelength of Sunscreens for "Broad Spectrum" Approval Brought on by Viscous Fingering During Sunscreen Application. Photochem Photobiol 2016; 92:637-43. [PMID: 27144668 DOI: 10.1111/php.12598] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 04/10/2016] [Indexed: 11/27/2022]
Abstract
When a viscous liquid is applied to a solid substrate, a patterned liquid layer is usually formed by the phenomenon called viscous fingering, since the moving liquid surface is in far-from-equilibrium conditions to let the morphological fluctuation to grow. Pseudosunscreen solutions were prepared and applied on a flat quartz plate. A spatially periodic stripe pattern was formed on the pseudosunscreen layer when a block applicator was used, whereas a flat surface layer was formed when a four-sided applicator was used. UV absorbance of the patterned layer was lower than that of the flat layer having the same average thickness. In addition, a larger decrease in the UV absorbance by the pattern formation was observed at wavelengths at which the UV absorbance of the flat layer was large, which was consistent with theoretical simulations. In 2011, US FDA introduced a new rule using the term "Broad Spectrum" for labeling the sunscreens. The different decrease in the UV absorbance at each wavelength was found to change the critical wavelength, which is a criterion for sunscreens to be labeled as "Broad Spectrum" protection. The result of this study makes the problem on the evaluation of the critical wavelength come to the surface.
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Affiliation(s)
- Misaki Wakabayashi
- Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Yokohama, Japan
| | - Kunihiko Okano
- Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Yokohama, Japan
| | | | - Daisuke Maezawa
- Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Yokohama, Japan.,R & D Center, Para Hermosa Co. Ltd., Yokohama, Japan
| | - Hitoshi Masaki
- School of Bioscience and Biotechnology, Tokyo University of Technology, Hachioji, Japan
| | - Akihiro Kuroda
- Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Yokohama, Japan.,Yokohama Research Center, Kuroda Consulting Inc., Yokohama, Japan
| | - Kouichi Asakura
- Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Yokohama, Japan
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