Quantification of human skin barrier function and susceptibility to quantum dot skin penetration

Abstract

In this study, we utilize in vivo human skin and a viable ex-vivo human skin model to investigate the effect of a commercial depilatory agent on barrier function. Tape stripping was used as a positive control. The magnitude of skin barrier was quantified by measuring transepidermal water loss values on in vivo human skin and transepithelial electrical resistance measurements and tissue histology on ex vivo skin. The susceptibility to carboxylated quantum dot penetration through ex vivo skin was investigated using fluorescent microcopy analysis of microtomed skin sections and flow cytometry to quantify quantum dot association with live epidermal cells. Results show that depilatory treatment modifies the outside-in barrier sufficiently to allow quantum dots to penetrate the stratum corneum but to a lesser extent than tape stripping. The implications of these finding are discussed.

Keywords::

• Quantum dots
• nanoparticles
• skin penetration
• depilatory agent
• tape stripping

Acknowledgements

The flow cytometry experiments were performed at the Flow Core in the University of Rochester headed by Dr. Timothy Bushnell. All experiments with the Ussing chamber were performed with the valuable help of Drs. Sadasivan Vidyasagar and Kunzhong Zhang (Department of Radiation and Oncology, now at the University of Florida, Gainsville). Skin slicing for histology studies was performed with the help of Fatat Sleiman (Department of Clinical Dermatology). We acknowledge Dr. Hong Zheng (Dermatology) for valuable assistance in developing the DHLA-QD ligand exchange procedure.

Declaration of interest: This work was supported by the National Science Foundation (CBET 0837891) and the National Institute of Health (NIDA K25AI060884). The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.