Volume 11, Issue 4 e201700169
FULL ARTICLE

Identification of polystyrene nanoparticle penetration across intact skin barrier as rare event at sites of focal particle aggregations

Nadine Döge

Nadine Döge

Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Berlin, Germany

Institute for Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, Germany

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Sabrina Hadam

Sabrina Hadam

Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Berlin, Germany

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Pierre Volz

Pierre Volz

Department of Physics, Freie Universität Berlin, Berlin, Germany

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Alexander Wolf

Alexander Wolf

Department of Physics, Freie Universität Berlin, Berlin, Germany

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Karl-Heinz Schönborn

Karl-Heinz Schönborn

W.O.M. World of Medicine GmbH, Berlin, Germany

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Ulrike Blume-Peytavi

Ulrike Blume-Peytavi

Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Berlin, Germany

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Ulrike Alexiev

Corresponding Author

Ulrike Alexiev

Department of Physics, Freie Universität Berlin, Berlin, Germany

Correspondence

Annika Vogt, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Charitéplatz 1, 10117 Berlin, Germany. Email: [email protected]

Ulrike Alexiev, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany. Email: [email protected]

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Annika Vogt

Corresponding Author

Annika Vogt

Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Berlin, Germany

Correspondence

Annika Vogt, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Charitéplatz 1, 10117 Berlin, Germany. Email: [email protected]

Ulrike Alexiev, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany. Email: [email protected]

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First published: 27 November 2017
Citations: 27

Abstract

The question whether nanoparticles can cross the skin barrier is highly debated. Even in intact skin rare events of deeper penetration have been reported, but technical limitations and possible artifacts require careful interpretation. In this study, horizontal scanning by 2-photon microscopy (2 PM) of full-thickness human skin samples placed in a lateral position yielded highly informative images for skin penetration studies of fluorescently tagged nanoparticles. Scanning of large fields of view allowed for detailed information on interfollicular and follicular penetration in tissue blocks without damaging the sample. Images in histomorphological correlation showed that 2P-excited fluorescence signals of fluorescently tagged 20 and 200 nm polystyrene nanoparticles preferentially accumulated in the stratum corneum (SC) and in the upper part of vellus hair follicles (HFs). Rare events of deeper penetration in the SC and in the infundibulum of vellus HFs were observed at sites of high focal particle aggregations. Wide-field 2 PM allows for imaging of nanoparticle penetration in large tissue blocks, whereas total internal reflection microscopy (TIRFM) enables selective detection of individual nanoparticles as well as clusters of nanoparticles in the SC and within the epidermal layer directly beneath the SC, thus confirming barrier crossing with high sensitivity.

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