Quantum dot penetration into viable human skin

Abstract

Systematic studies probing the effects of nanoparticle surface modification and formulation pH are important in nanotoxicology and nanomedicine. In this study, we use laser-scanning fluorescence confocal microscopy to evaluate nanoparticle penetration in viable excised human skin that was intact or tape-stripped. Quantum dot (QD) fluorescent nanoparticles with three surface modifications: Polyethylene glycol (PEG), PEG-amine (PEG-NH₂) and PEG-carboxyl (PEG-COOH) were evaluated for human skin penetration from aqueous solutions at pH 7.0 and at pHs of solutions provided by the QD manufacturer: 8.3 (PEG, PEG-NH₂) and 9.0 (PEG-COOH). There was some penetration into intact viable epidermis of skin for the PEG-QD at pH 8.3, but not at pH 7.0 nor for any other QD at the pHs used. Upon tape stripping 30 strips of stratum corneum, all QDs penetrated through the viable epidermis and into the upper dermis within 24 h.

Keywords::

• Nanoparticles
• exposure
• nanotoxicology
• surface chemistry

Acknowledgements

Portions of this work were presented at the Gordon Research Conference on “Barrier Function of Mammalian Skin” in Newport, Rhode Island, USA, August 2007 and at the 47th Annual meeting of the Society of Toxicology, Seattle, WA, in March 2008.

Declaration of interest: This study was funded in part by Prof. Nancy Monteiro-Riviere's United States Air Force Office of Scientific Research (USAFOSR) grant FA 9550-08-1-0182 and Prof. Michael S. Roberts' Asian Office of Aerospace Research and Development (AOARD) grant and by the NH&MRC (Australia). The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.