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Journal of Nanomaterials
Volume 2012, Article ID 721706, 8 pages
http://dx.doi.org/10.1155/2012/721706
Research Article

The Human Stratum Corneum Prevents Small Gold Nanoparticle Penetration and Their Potential Toxic Metabolic Consequences

1Dermatology Research Centre, School of Medicine, Princess Alexandra Hospital, The University of Queensland, Brisbane, QLD 4102, Australia
2Therapeutics Research Centre, School of Medicine, Princess Alexandra Hospital, The University of Queensland, Brisbane, QLD 4102, Australia
3Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
4School of Pharmacy and Medical Science, University of South Australia, Adelaide, SA 5001, Australia

Received 20 January 2012; Accepted 12 April 2012

Academic Editor: Xiaoming Li

Copyright © 2012 David C. Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Nanoparticles are being used in multiple applications, ranging from biomedical and skin care products (e.g., sunscreen) through to industrial manufacturing processes (e.g., water purification). The increase in exposure has led to multiple reports on nanoparticle penetration and toxicity. However, the correlation between nanoparticle size and its penetration without physical/chemical enhancers through the skin is poorly understood—with studies instead focusing primarily on skin penetration under disrupted conditions. In this paper, we investigate the penetration and metabolic effects of 10 nm, 30 nm, and 60 nm gold nanoparticles within viable excised human skin after 24-hour exposure using multiphoton tomograph-fluorescence lifetime imaging microscopy. After 24 hour treatment with the 10, 30, and 60 nm gold nanoparticles, there was no significant penetration detected below the stratum corneum. Furthermore, there were no changes in metabolic output (total NAD(P)H) in the viable epidermis posttreatment correlating with lack of penetration of nanoparticles. These results are significant for estimating topical nanoparticle exposure in humans where other model systems may overestimate the exposure of nanoparticles to the viable epidermis. Our data shows that viable human skin resists permeation of small nanoparticles in a size range that has been reported to penetrate deeply in other skin models.