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Visualization of zinc pyrithione particles deposited on the scalp from a shampoo by tape‐strip sampling and scanning electron microscopy/energy dispersive X‐ray spectroscopy measurement
Author(s) -
Chen G.,
Ji C.,
Collins L. Z.,
Hoptroff M.,
Janssen H.G.
Publication year - 2018
Publication title -
international journal of cosmetic science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 62
eISSN - 1468-2494
pISSN - 0142-5463
DOI - 10.1111/ics.12493
Subject(s) - shampoo , scanning electron microscope , zinc , energy dispersive x ray spectroscopy , deposition (geology) , materials science , particle size , particle (ecology) , nanotechnology , chemistry , metallurgy , composite material , organic chemistry , paleontology , oceanography , sediment , biology , geology
Objective Zinc pyrithione (Zn PT ) is widely used as an anti‐fungal active in commercial anti‐dandruff ( AD ) shampoos. The AD efficacy of Zn PT is highly dependent on the deposition of Zn PT particles onto the scalp during the process of shampoo application and rinse‐off. Since Zn PT materials with different particle sizes and morphologies have different deposition behaviours, the measurement of the actual Zn PT deposition is critical to understand the AD performance delivered by different Zn PT shampoos. The aim of this study is to develop a robust and reliable method for visualizing the particle size and morphology of Zn PT deposited on the scalp from AD shampoos. Methods Hair was washed with a commercially available AD shampoo containing Zn PT and zinc carbonate (Zn CO 3 ). Tape strips were applied to collect the deposited particles from the scalp after AD shampoo application and rinse‐off. The scalp tape strip samples were subjected to scanning electron microscopy/energy dispersive X‐ray spectroscopy ( SEM / EDX ) measurement. The morphology of the Zn PT particles was visualized by SEM imaging and identification of Zn PT particles was confirmed by EDX analysis. Results For the commercial shampoo studied it was observed that two zinc‐containing particulates with different morphologies and composition remained on the scalp after shampoo application and rinse‐off. As indicated by the EDX spectra, the Zn PT particles deposited onto the scalp surface had polygonal crystal structures. Zn CO 3 was also deposited onto the scalp surface. This material was mainly present as aggregated particulates. Conclusion An ex vivo method that combines tape strip sampling and SEM / EDX has been developed for measuring and visualizing the particle size, morphology and composition of Zn PT deposited on the scalp from AD shampoos. This ex vivo measurement method provides higher imaging resolution and more chemical specificity than reflectance confocal microscopy ( RCM ). To the best of our knowledge, this is the first time that Zn PT particles were distinguishable from other zinc particles on the scalp. Moreover, the new method allows the microstructures of both Zn PT and other zinc particles on the scalp to be imaged.