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Fluorescence of Sunscreens Adsorbed to Dielectric Nanospheres: Parallels to Optical Behavior on HaCat Cells and Skin
Author(s) -
Krishnan Rajagopal,
Pradhan Sanjay,
Timares Laura,
Katiyar Santosh K.,
Elmets Craig A.,
Nordlund Thomas M.
Publication year - 2006
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2006.tb09811.x
Subject(s) - hacat , polystyrene , stratum corneum , fluorescence , chemistry , adsorption , photochemistry , biomolecule , penetration (warfare) , materials science , nanotechnology , polymer , organic chemistry , optics , biochemistry , physics , engineering , in vitro , medicine , pathology , operations research
Sunscreens applied to the skin are retained primarily in the stratum corneum, where they adsorb and act as a barrier preventing UV penetration to deeper layers. Photophysical properties of sunscreens have traditionally been studied either in solvents, which are very different from skin, or in skin or complex artificial skin systems, which are difficult to handle. The purpose of this study was to determine whether polystyrene nanospheres could serve as an improvement over solvents for evaluation of the photophysical properties of sunscreens without the presence of autofluorescence from and interactions with specific skin biomolecules. We used HaCat cells and excised skin for this comparative study with nanospheres. Fluorescence spectral properties of common hydrophobic sunscreens octyl salicylate, padimate O (2‐ethylhexyl‐4‐dimethylaminobenzoate) and octyl methoxycinnamate adsorbed to 220 nm polystyrene spheres are similar to those of sunscreens adsorbed to HaCat cells and excised skin. Specifically, similarity in the emission peaks and their approximate positions, excitation peak positions and a measurable reduction in scattering upon sunscreen addition suggest that polystyrene nanospheres constitute a useful system to evaluate the photophysical properties of topical sunscreens and may serve as a model system for high‐throughput evaluation of potential sunscreens. An unexpected result of this comparative study was the observation of an increase in a specific skin component emission caused by addition of padimate O.