title: Sunscreen remanence on the skin: a noninvasive real time in vivo spectral analysis assessing the quenching of specular ultraviolet A light reflectance.
abstract: BACKGROUND
  Under specific light illumination, particularly ultraviolet radiation (UVR), the skin produces both specular light reflectance and, possibly, specific fluorescent emission. A quenching effect of fluorescence is observed following the application of sunscreens active against UVA radiations.
  
  
  OBJECTIVE
  To assess noninvasively in a real-time process, the potential sunscreen remanence/substantivity after application on the skin.
  
  
  METHODS
  The Visiopor® device was used in a real-time procedure after application of sunscreens to the skin. A quenching effect of follicular fluorescence due to bacterial porphyrins was evaluated at 30-min intervals. The Visioscan(®) device was used as a distinct UVA emitter in a control procedure of spectral analysis of specular UVR emission and reflectance by dermal fibers.
  
  
  RESULTS
  Under UVA-1 irradiations, facial skin produced different patterns of specular UVR reflectance and fluorescent emission as well. The porphyrin-related follicular fluorescence was instantly abated by UVA blockers present in suncare products. The potential sunscreen remanence/substantivity was assessed by the follicular and interfollicular fluorescence recurrence all along the next hours.
  
  
  CONCLUSIONS
  All UVA blocker-containing suncare products exhibited a similar overall quenching effect on porphyrin-enriched facial hair follicles and dermal fibers. This effect lasted for a few hours. Differences in the fluorescence recovery were likely related to the amount in suncare application and the nature of the formulation components.
authors.affiliation: Laboratory of Skin Bioengineering and Imaging (LABIC), Department of Clinical Sciences, University of Liège, Liège, Belgium.
authors.forename: Gérald E
authors.initials: GE
authors.lastname: Piérard
authors.affiliation: CK Electronic, Cologne, Germany.
authors.forename: Diana
authors.initials: D
authors.lastname: Khazaka
authors.affiliation: CK Electronic, Cologne, Germany.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Khazaka
mesh_terms: D000328:Adult; D005145:Face; D005260:Female; D005453:Fluorescence; D018859:Hair Follicle / Q000737:chemistry / Q000382:microbiology / Q000528:radiation effects; D006801:Humans; D008297:Male; D011166:Porphyrins / Q000378:metabolism / Q000528:radiation effects; D011425:Propionibacterium acnes / Q000378:metabolism; D012867:Skin / Q000000981:diagnostic imaging*; D012869:Skin Absorption / Q000187:drug effects; D013057:Spectrum Analysis / Q000379:methods; D013473:Sunscreening Agents / Q000032:analysis* / Q000494:pharmacology*; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D011166:Porphyrins; D013473:Sunscreening Agents
keywords: Propionibacterium acnes; UVA protection factor; fluorophore; porphyrin; spectral analysis; sunburn protection factor; sunscreen