Sohn Myriam, Buehler Theodor, Imanidis Georgios
University of Applied Sciences Northwestern Switzerland, School of Life Sciences, Institute of Pharmaceutical Technology, Muttenz/Basel, Switzerland and University of Basel, Department of Pharmaceutical Sciences, Basel, Switzerland.
University of Applied Sciences Northwestern Switzerland, School of Life Sciences, Institute of Pharmaceutical Technology, Muttenz/Basel, Switzerland.
Photochem Photobiol Sci. 2016 Jul 6;15(7):861-71. doi: 10.1039/c6pp00024j.
Photoprotection provided by topical sunscreens is expressed by the sun protection factor (SPF) which depends primarily on the UV filters contained in the product and the applied sunscreen amount. Recently, the vehicle was shown to significantly impact film thickness distribution of an applied sunscreen and sunscreen efficacy. In the present work, repartition of the UV filters within the sunscreen film upon application is investigated for its role to affect sun protection efficacy. The spatial repartition of an oil-miscible and a water-soluble UV filter within the sunscreen film was studied using confocal Raman microspectroscopy. Epidermis of pig ear skin was used as substrate for application of three different sunscreen formulations, an oil-in-water emulsion, a water-in-oil emulsion, and a clear lipo-alcoholic spray (CAS) and SPF in vitro was measured. Considerable differences in the repartition of the UV filters upon application and evaporation of volatile ingredients were found between the tested formulations. A nearly continuous phase of lipid-miscible UV filter was formed only for the WO formulation with dispersed aggregates of water-soluble UV filter. OW emulsion and CAS exhibited interspersed patches of the two UV filters, whereas the segregated UV filter domains of the latter formulation were by comparison of a much larger scale and spanned the entire thickness of the sunscreen film. CAS therefore differed markedly from the other two formulations with respect to filter repartition. This difference should be reflected in SPF when the absorption spectra of the employed UV filters are not the same. Confocal Raman microspectroscopy was shown to be a powerful technique for studying this mechanism of sun protection performance of sunscreens.
局部防晒霜提供的光保护作用由防晒系数（SPF）表示，该系数主要取决于产品中所含的紫外线过滤剂和涂抹的防晒霜量。最近，已表明载体对涂抹的防晒霜的膜厚度分布和防晒效果有显著影响。在本研究中，研究了紫外线过滤剂在涂抹后在防晒膜中的重新分布对其影响防晒效果的作用。使用共聚焦拉曼显微光谱法研究了油溶性和水溶性紫外线过滤剂在防晒膜中的空间重新分布。将猪耳皮肤的表皮用作三种不同防晒配方的涂抹基质，即水包油乳液、油包水乳液和透明脂醇喷雾剂（CAS），并测量了体外SPF。在所测试的配方之间，发现紫外线过滤剂在挥发性成分涂抹和蒸发后的重新分布存在相当大的差异。仅对于具有分散的水溶性紫外线过滤剂聚集体的油包水配方，形成了几乎连续的与脂质混溶的紫外线过滤剂相。水包油乳液和CAS表现出两种紫外线过滤剂的散布斑块，而通过比较，后一种配方的分离的紫外线过滤剂域规模要大得多，并且跨越了防晒膜的整个厚度。因此，就过滤剂重新分布而言，CAS与其他两种配方有明显不同。当所用紫外线过滤剂的吸收光谱不同时，这种差异应反映在SPF中。共聚焦拉曼显微光谱法被证明是研究防晒霜防晒性能这一机制的有力技术。
