Open AccessPolyoxyethylene/polyoxypropylene dimethyl ether (EPDME) random copolymer improves lipid structural ordering in stratum corneum of an epidermal‐equivalent model as seen by two‐photon microscopy
Author(s) -
Umino Yuki,
Ipponjima Sari,
Denda Mitsuhiro
Publication year - 2021
Publication title -
skin research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.521
H-Index - 69
eISSN - 1600-0846
pISSN - 0909-752X
DOI - 10.1111/srt.12996
Subject(s) - stratum corneum , laurdan , polyethylene glycol , peg ratio , biophysics , barrier function , chemistry , fluorescence microscope , poloxamer , copolymer , polymer , materials science , chemical engineering , polymer chemistry , fluorescence , membrane , lipid bilayer , organic chemistry , biochemistry , optics , medicine , mathematical optimization , physics , mathematics , finance , pathology , economics , biology , engineering
Background/Purpose Topical application of polyoxyethylene/polyoxypropylene dimethyl ether (EPDME) random copolymer improves the barrier function of skin, whereas polyethylene glycol (PEG) and polypropylene glycol (PPG) are ineffective. The aim of this work was to examine the interaction between these polymers and lipid molecules in the stratum corneum in order to establish whether EPDME‐specific changes in the structural ordering of lipids might account for the improvement of barrier function. Methods We used two‐photon microscopy to evaluate the effects of EPDME, PEG, and PPG on the structural ordering of lipids in an epidermal‐equivalent model in terms of the fluorescence changes of Laurdan, a fluorescent dye that responds to changes of membrane fluidity. The generalized polarization (GP) value, a parameter that reflects lipid ordering, was measured at various depths from the surface of the stratum corneum. Results EPDME increased the GP value to a depth of about 3 µm from the surface, indicating that lipid ordering was increased in this region, while PEG and PPG of the same molecular weight had no effect. Diffusion of Lucifer yellow into the epidermis was reduced after application of EPDME, indicating that the barrier function was improved. Conclusion These results support the view that EPDME improves barrier function by increasing the ordering of lipid structures in the stratum corneum. The methodology described here could be useful for screening new compounds that would improve the structural ordering of lipids.