title: Assessment of Raman spectroscopy as a fast and non-invasive method for total stratum corneum thickness determination of pig skin.
abstract: Determination of total stratum corneum (SC) thickness is necessary to construct accurate SC drug concentration depth profiles that are used to evaluate the skin absorption of locally acting active components. Currently, different established methods such as the microscopic or gravimetric approach, estimation via transepidermal water loss or NIR densitometry are used. However, some of them represent time consuming strategies. In the present study, Raman spectroscopy was assessed as a non-invasive and fast method for total SC thickness estimation. All techniques employed in this study yielded comparable results with SC values of 11.15 ± 1.52 μm derived from Raman experiments, 10.22 ± 2.64 μm from NIR densitometry measurements and 10.91 ± 2.03 μm from light microscopy studies suggesting Raman spectroscopy as an appropriate and rapid method for total SC thickness determination. As a further objective of the study, the storage conditions of the skin samples during Raman measurements and the impact of keeping the skin on the cartilage during NIR densitometry measurements were investigated. Skin samples can be stored dry during Raman measurements, if immediate measurement is not feasible. Furthermore, skin samples for NIR densitometry studies should be kept on the cartilage during the stripping procedure to avoid SC thickness underestimation.
authors.affiliation: Department of Pharmaceutical Technology and Biopharmaceutics, Faculty of Life Sciences, University of Vienna, Vienna 1090, Austria.
authors.forename: Denise-Silvia
authors.initials: DS
authors.lastname: Mahrhauser
authors.affiliation: Department of Pharmaceutical Technology and Biopharmaceutics, Faculty of Life Sciences, University of Vienna, Vienna 1090, Austria.
authors.forename: Corinna
authors.initials: C
authors.lastname: Nagelreiter
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna 1090, Austria.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Gehrig
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna 1090, Austria.
authors.forename: Antonia
authors.initials: A
authors.lastname: Geyer
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna 1090, Austria.
authors.forename: Manfred
authors.initials: M
authors.lastname: Ogris
authors.affiliation: Department of Pharmaceutical Technology and Biopharmaceutics, Faculty of Life Sciences, University of Vienna, Vienna 1090, Austria.
authors.forename: Kristina
authors.initials: K
authors.lastname: Kwizda
authors.affiliation: Department of Pharmaceutical Technology and Biopharmaceutics, Faculty of Life Sciences, University of Vienna, Vienna 1090, Austria; Research Platform "Characterisation of Drug Delivery Systems on Skin and Investigations of Involved Mechanisms", University of Vienna, Vienna 1090, Austria. Electronic address: claudia.valenta@univie.ac.at.
authors.forename: Claudia
authors.initials: C
authors.lastname: Valenta
mesh_terms: D000818:Animals; D003720:Densitometry; D008853:Microscopy; D023421:Models, Animal; D012867:Skin / Q000033:anatomy & histology*; D012869:Skin Absorption; D013059:Spectrum Analysis, Raman / Q000379:methods* / Q000592:standards; D013552:Swine; D014867:Water
chemical_list: D014867:Water
keywords: Microscopy; NIR densitometry; Porcine skin; Raman spectroscopy; Stratum corneum thickness