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Objective assessment of nanoparticle disposition in mammalian skin after topical exposure
Link to Journal Abstract
The use of nanoparticles as formulation components of topical drug delivery systems for the skin has been widely investigated in the literature. Because of the conflicting conclusions resulting from these studies concerning the ultimate disposition of the nanoparticles employed, the research presented in this paper has been designed to evaluate objectively the fate of such structures when administered to mammalian skin. Confocal microscopy images of skin exposed to nanoparticles have therefore been assessed by quantitative statistical analysis. Sebum on the skin surface was naturally fluorescent and clearly defined the outermost part of the cutaneous barrier. Fluorescent polystyrene nanoparticles applied in aqueous suspension could infiltrate only the stratum disjunctum, i.e., skin layers in the final stages of desquamation. This minimal uptake was independent of contact time (up to 16 h) and of nanoparticle size tested (20–200 nm). When skin barrier function was modestly compromised, the nanoparticles remained incapable of penetration beyond the most superficial layers, corresponding to a depth of 2–3 ?m, of the stratum corneum (the outermost, 15–20 ?m skin layer). Overall, these results demonstrate objectively and semi-quantitatively that nanoparticles contacting intact, and even partially damaged, skin cannot penetrate beyond the superficial layers of the barrier, and are highly unlikely, therefore, to reach the viable cells of the epidermis or beyond. It follows that nanoparticulate-based, topical delivery systems may prove useful as skin surface reservoirs from which controlled drug release over time may be achieved.
In this paper, a quantitative approach is proposed and applied to the assessment of fluorescent nanoparticle disposition (i.e., spatial distribution) within the skin. The specific objective was to undertake a quantitative analysis of the position of polymeric nanoparticles on the skin and to determine whether these structures penetrated the stratum corneum.
Peer Reviewed Journal Article
Exposure Or Hazard Target
Method Of Study
Risk Exposure Group
Journal of Controlled Release, 162(1): 201-207 (August 2012)
Journal of Controlled Release
Campbell CSJ, Contreras-Rojas LR, Delgado-Charro MB, Guy RH
Last updated on October 12, 2012
This work is supported in part by the Nanoscale Science and Engineering Initiative of the National Science Foundation
under NSF Award Number EEC-0118007.
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