title: Effect of size of TiO(2) nanoparticles applied onto glass slide and porcine skin on generation of free radicals under ultraviolet irradiation.
abstract: Titanium dioxide (TiO(2)) nanoparticles are extensively used today in sunscreens and coatings as protective compounds for human skin and material surfaces from UV radiation. In this paper, such particles are investigated by electron paramagnetic resonance spectroscopy as sources of free radicals under UV irradiation. The surface density of a placebo with embedded particles corresponds to the recommendations of dermatologists (2 mg cm(-2)). It is revealed that if applied onto glass, small particles 25 nm in diameter produce an increased amount of free radicals compared to the larger ones of 400 nm diam and the placebo itself. However, if applied onto porcine skin in vitro, there is no statistically distinct difference in the amount of radicals generated by the two kinds of particles on skin and by the skin itself. This proves that although particles as part of sunscreens produce free radicals, the effect is negligible in comparison to the production of radicals by skin in vitro.
authors.affiliation: University of Oulu and Infotech Oulu, Faculty of Technology, Department of Electrical Engineering, Optoelectronics and Measurement Techniques Laboratory, P.O. Box 4500, FI-90014 Oulu, Finland. dwelle@rambler.ru
authors.forename: Alexey P
authors.initials: AP
authors.lastname: Popov
authors.forename: Stefan
authors.initials: S
authors.lastname: Haag
authors.forename: Martina
authors.initials: M
authors.lastname: Meinke
authors.forename: Jürgen
authors.initials: J
authors.lastname: Lademann
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Priezzhev
authors.forename: Risto
authors.initials: R
authors.lastname: Myllylä
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D005609:Free Radicals / Q000378:metabolism*; D005898:Glass / Q000737:chemistry; D066298:In Vitro Techniques; D053758:Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry / Q000648:ultrastructure*; D010316:Particle Size; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000187:drug effects; D012867:Skin / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects*; D013552:Swine; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D005609:Free Radicals; C009495:titanium dioxide; D014025:Titanium