Photoacoustic Evaluation of Sunscreen Stability: Wind, Water, and the Influence of the Substrates

Autor: P. R. Barja, S. B. Pinto
Rok vydání: 2012
Předmět:
Zdroj: International Journal of Thermophysics. 33:1870-1875
ISSN: 1572-9567
0195-928X
DOI: 10.1007/s10765-012-1307-9
Popis: Sunscreens are designed to protect the skin against damage caused by excessive exposure to ultraviolet radiation—ranging from sunburns and premature aging to skin cancer. The photoacoustic (PA) technique can be employed to analyze topical products like sunscreens. This study aims to characterize the response of commercially available sunscreens subjected to wind and water exposure and applied in two different substrates: pig ear skin and artificial skin (Vitroskin ®). The light source of the experimental setup was a tungsten lamp (250 W) mechanically modulated at 11 Hz. Measurements employed a double-faced, open PA cell with a sapphire window on one side; the opposite side was closed by the sample itself. Initial measurements were performed: (i) before sunscreen application in the sample, and (ii) immediately after sunscreen application. The sample was then immersed in a saline solution for 3 s and exposed to the wind under ambient temperature for 30 min; after that, a new measurement was performed. This cycle was repeated each 30 min, up to a total time of 2 h. Fitting curves (Boltzmann type) for the time evolution of the PA signal were generated with the software Origin ®. After measurements, Vitroskin ® was found to be a more adequate substrate than pig skin in the analysis of sunscreen stability. Results obtained indicate that the stability is not dependent on the sun protection factor; measurements performed in Vitroskin ® show good stability of the topically applied products for up to 2 h after sunscreen application, with a fall of less than 40 % in the PA signal amplitude even after exposure to external agents (wind and water).
Databáze: OpenAIRE
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