{'fraction_non_alphanumeric': 0.06134603930911257, 'fraction_numerical': 0.05539011316259678, 'mean_word_length': 4.936395759717315, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Stratum corneum lipid organization as observed by atomic force, confocal and two‐photon excitation fluorescence microscopy

Skin moisturization is largely a function of stratum corneum barrier capacity, which in turn is a function of the physical state and structural organization of the stratum corneum extracellular lipid matrix [ J. Invest. Dermatol.18, 433 (1952); AIChE J. 21, 985 (1975); Acta Derm. Venereol.74, 1 (1994); J. Invest. Dermatol.117, 830 (2001) ]. Three unsolved key questions with respect to this lipid matrix’ structural organization [ Acta Derm. Venereol.74, 1 (1994); J. Invest. Dermatol.117, 830 (2001); J. Invest. Dermatol.118, 897 (2002); J. Invest. Dermatol.118, 899 (2002) ] are: i) whether the lipid matrix is constituted by a single‐gel phase or by co‐existing solid (crystalline or gel) domains, ii) whether a separate fluid (liquid crystalline) phase is present and iii) whether the local pH has a direct effect on the lipid matrix’ phase behaviour. Using an array of complementary visual‐related biophysical techniques (e.g. atomic force microscopy and confocal/two‐photon excitation fluorescence microscopy), it was recently shown that reconstituted membranes composed of extracted decontaminated human stratum corneum lipids do not form a fluid phase, but exclusively a single‐gel phase that segregates into co‐existing microscopic domains below pH 6 [ Biophys. J.93, 3142 (2007) ]. It was further shown that the role of cholesterol is related to dispersion of ceramide‐enriched domains. This effect is counteracted by the presence of free fatty acids, which mix with skin ceramides but not with cholesterol [ J. Struct. Biol.158, 386 (2007) ].