title: The effect of formulation on the penetration of coated and uncoated zinc oxide nanoparticles into the viable epidermis of human skin in vivo.
abstract: The use of nanoparticulate zinc oxide (ZnO-NP) in sunscreens and other cosmetic products has raised public health concerns. The two key issues are the extent of exposure to ZnO-NP and the likely hazard after the application of ZnO-NP in sunscreen and cosmetic products to humans in vivo. Our aims were to assess exposure by the extent of ZnO-NP penetration into the viable epidermis and hazard by changes in the viable epidermal redox state for a number of topical products. Of particular interest is the role of the particle coating, formulation used, and the presence of any enhancers. Multiphoton tomography with fluorescence lifetime imaging microscopy (MPT-FLIM) was used to simultaneously observe ZnO-NP penetration and potential metabolic changes within the viable epidermis of human volunteers after topical application of various ZnO-NP products. Coated and uncoated ZnO-NP remained in the superficial layers of the SC and in the skin furrows. We observed limited penetration of coated ZnO-NP dispersed in a water-in-oil emulsion formulation, which was predominantly localized adjacent to the skin furrow. However, the presence of ZnO-NP in the viable epidermis did not alter the metabolic state or morphology of the cells. In summary, our data suggest that some limited penetration of coated and uncoated ZnO-NP may occur into viable stratum granulosum epidermis adjacent to furrows, but that the extent is not sufficient to affect the redox state of those viable cells.
authors: Therapeutics Research Centre, The University of Queensland, Woolloongabba, Australia.
authors: Vânia R
authors: VR
authors: Leite-Silva
authors: Marina
authors: M
authors: Le Lamer
authors: Washington Y
authors: WY
authors: Sanchez
authors: David C
authors: DC
authors: Liu
authors: Washington H
authors: WH
authors: Sanchez
authors: Isabel
authors: I
authors: Morrow
authors: Darren
authors: D
authors: Martin
authors: Heron D T
authors: HD
authors: Silva
authors: Tarl W
authors: TW
authors: Prow
authors: Jeffrey E
authors: JE
authors: Grice
authors: Michael S
authors: MS
authors: Roberts
mesh_terms: D000328:Adult; D003358:Cosmetics; D004337:Drug Carriers; D016503:Drug Delivery Systems; D004817:Epidermis / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D053768:Metal Nanoparticles; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D012867:Skin / Q000187:drug effects*; D012869:Skin Absorption; D013473:Sunscreening Agents / Q000737:chemistry* / Q000493:pharmacokinetics; D055815:Young Adult; D015034:Zinc Oxide / Q000737:chemistry* / Q000493:pharmacokinetics
chemical_list: D003358:Cosmetics; D004337:Drug Carriers; D013473:Sunscreening Agents; D015034:Zinc Oxide