Mandal Sadananda, Bera Rajesh, Das Somnath, Nayak Sandip K, Pramanik Amitava, Patra Amitava
Department of Materials Science, Indian Association for the Cultivation of Science, Kolkata, 700 032, India.
Department of Chemistry, Vivekananda Mahavidyalaya, Burdwan, Sripally, Burdwan-, 713103, West Bengal, India.
Chemphyschem. 2015 Dec 1;16(17):3618-24. doi: 10.1002/cphc.201500780. Epub 2015 Oct 14.
The ultraviolet light component in the solar spectrum is known to cause several harmful effects, such as allergy, skin ageing, and skin cancer. Thus, current research attention has been paid to the design and fundamental understanding of sunscreen-based materials. One of the most abundantly used sunscreen molecules is Avobenzone (AB), which exhibits two tautomers. Here, we highlight the preparation of spherically shaped nanoparticles from the sunscreen molecule AB as well as from sunscreen-molecule-encapsulated polymer nanoparticles in aqueous media and study their fundamental photophysical properties by steady-state and time-resolved spectroscopy. Steady-state studies confirm that the AB molecule is in the keto and enol forms in tetrahydrofuran, whereas the enol form is stable in the case of both AB nanoparticles and AB-encapsulated poly(methyl methacrylate) (PMMA) nanoparticles. Thus, the keto-enol transformation of AB molecules is restricted to a nanoenvironment. An enhancement of photostability in both the nanoparticle and PMMA-encapsulated forms under UV light irradiation is observed. The efficient excited energy transfer (60 %) from AB to porphyrin molecules opens up further prospects in potential applications as light-harvesting systems.
太阳光谱中的紫外线成分已知会造成多种有害影响，如过敏、皮肤老化和皮肤癌。因此，目前的研究重点已放在基于防晒霜材料的设计及基础认识上。最常用的防晒分子之一是阿伏苯宗（AB），它呈现两种互变异构体。在此，我们着重介绍在水介质中由防晒分子AB以及由包裹了防晒分子的聚合物纳米颗粒制备球形纳米颗粒，并通过稳态和时间分辨光谱研究它们的基础光物理性质。稳态研究证实，AB分子在四氢呋喃中以酮式和烯醇式存在，而在AB纳米颗粒和包裹了AB的聚甲基丙烯酸甲酯（PMMA）纳米颗粒中烯醇式是稳定的。因此，AB分子的酮 - 烯醇转化被限制在纳米环境中。在紫外线照射下，观察到纳米颗粒和PMMA包裹形式的光稳定性均有所增强。从AB到卟啉分子的高效激发能量转移（60%）为作为光捕获系统的潜在应用开辟了进一步的前景。
