Abstract

Ultraviolet (UV) filter nanocapsules were prepared by encapsulating organic UV filter octyl dimethyl para-aminobenzoic acid (OD-PABA) with miniemulsion polymerization using an amphiphilic random copolymer poly(styrene-co-methacrylic acid) (P(St-co-MAA)) as an emulsifier, methyl methacrylate (MMA) as the monomer and ethylene glycol dimethacrylate (EGDMA) as the crosslinker. TEM showed that the nanocapsules had irregularly spherical shape with an average diameter of 320 nm, and OD-PABA crystalline grains were encapsulated. The molar ratio of St to MAA in P(St-co-MAA) and the polymer emulsifier concentration, as well as the molar ratio of MMA to EGDMA in polymer coating significantly influenced the encapsulation efficiency and the leakage rate. At the optimum conditions, the encapsulation efficiency of OD-PABA reached to 33%. OD-PABA leakage in isopropyl myristate (IPM) could be ignored since the leakage rate maintained 1.3% during continuous stirring for 24 h. UV reflectance spectra showed that the UV filter nanocapsules had broad-spectrum UV blocking owing to the absorbance of OD-PABA combined with the scattering and reflection of the nanocapsules at submicron level. The sun protection factor (SPF) of the UV filter nanocapsules sunscreen improved by 300% compared with the free OD-PABA formulations. Moreover, OD-PABA encapsulated in the nanocapsules could reduce the cytotoxicity significantly through the evaluation of the sunscreen safety with MTT method.

摘要

通过使用两亲性无规共聚物聚（苯乙烯-co-甲基丙烯酸）（P（St- co- MAA）微乳液聚合封装有机紫外线过滤剂辛基二甲基对氨基苯甲酸（OD-PABA），制备紫外线（UV）过滤剂纳米胶囊) 作为乳化剂，甲基丙烯酸甲酯 (MMA) 作为单体，乙二醇二甲基丙烯酸酯 (EGDMA) 作为交联剂。TEM 表明纳米胶囊呈不规则球形，平均直径为 320 nm，OD-PABA 晶粒被包裹。P(St- co)中St与MAA的摩尔比-MAA) 和聚合物乳化剂浓度，以及聚合物涂层中 MMA 与 EGDMA 的摩尔比显着影响包封效率和泄漏率。在最佳条件下，OD-PABA的包封率达到33%。OD-PABA 在肉豆蔻酸异丙酯 (IPM) 中的泄漏可以忽略不计，因为在连续搅拌 24 小时期间泄漏率保持在 1.3%。紫外反射光谱表明，由于 OD-PABA 的吸收以及纳米胶囊在亚微米级的散射和反射，紫外线过滤纳米胶囊具有广谱的紫外线阻断作用。与游离 OD-PABA 配方相比，紫外线过滤纳米胶囊防晒霜的防晒系数 (SPF) 提高了 300%。而且，