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Inorganic Particles against Reactive Oxygen Species for Sun Protective Products
Published in Claudia Altavilla, Enrico Ciliberto, Inorganic Nanoparticles: Synthesis, Applications, and Perspectives, 2017
Lee Wilson A., Raifailovich Miriam
The overall effect from the UV decomposition of the organic materials, free radical generation after UV exposure of TiO2, and penetration risk factor from the nanoparticles significantly attenuates the protection attributes provided by the product. Even when TiO2 is >100 nm, which is considered safe in respect to skin penetration by most industries, it can still drive various chemical reactions when exposed to UV illumination due to its strong oxidizing and reducing ability. It has been suggested by Cai et al. (1992) that TiO2 particles produce hydroxyl radical and hydrogen peroxide when exposed to UV light. As a result, consumers rely on the belief that sunscreen containing TiO2 is supposed to protect them from UV damages, but, on the contrary, the free radical generated from TiO2 after UV illumination actually oxidizes their skin. Dondi et al. (2006) has further shown the loss of UV protection when sunscreen containing both TiO2 and organic sunscreens, like octyl methoxycinnamate (OMC) or avobenzone, Parsol 1789, after exposure to UV light. As a result, fragmentation of OMC, or avobenzone could potentially react with DNA pyrimi-dines, if sunscreen agents indeed penetrate the skin (Pflucker et al. 1999).
Smart Delivery Systems for Personal Care and Cosmetic Products
Published in Munmaya K. Mishra, Applications of Encapsulation and Controlled Release, 2019
Incompatibility of UV absorbers in the sunscreen formulations and during the end use application can be a major concern. For example, the presence of octyl methoxycinnamate (OMC) can accelerate the degradation of avobenzone through a Norrish type addition reaction pathway. Encapsulation technology will be one of the key approaches to resolve these problems.5 The sol-gel encapsulation process developed and patented by Avnir and coworkers at Sol-Gel Technologies was designed for precisely this purpose.6 OMC and avobenzone were encapsulated separately by the sol-gel method. In this sol-gel method, the hydrophobic solution containing the UV absorber and sol-gel precursors was emulsified in an aqueous solution under high shear. The formation of inorganic silica spheres, as shown in Figure 12.1, was carefully controlled by the appropriate reaction conditions, such as the selected pH change, so that the leaching rate of UV absorbers from the encapsulated product was very low. Examples of sol-gel precursors include tetraethoxysilane, methyltriethoxysilane, and poly (diethoxysiloxane). When these separate UV absorber microcapsules were formulated into the sunscreen formulation, good photostability was demonstrated for the OMC/avobenzone pair due to their physical separation inside their individual capsule walls. In addition to the improvement of photostability, the sol-gel UV absorber microcapsules were shown to be safer than their unencapsulated counterparts in terms of phototoxicity, plasmid DNA nicking, and amount of extractable UV absorber.7 The last property suggests that the encapsulation of UV absorber can prevent the penetration of actives into the skin, which is not desirable in this application, as shown in Figure 12.2.8 Furthermore, the encapsulation of UV absorbers can improve aesthetic feel without the oily and sticky feel encountered from the unencapsulated counterpart. Finally, the technology can provide formulation flexibility, with the product supplied as either a water-based slurry or isolated dry powder.9Sol-gel chemistry.
Straightforward sustainable synthesis of novel non-endocrine disruptive bio-based organic UV-B filters with antimicrobial activity
Published in Green Chemistry Letters and Reviews, 2023
Matthieu M. Mention, Cédric Peyrot, Blandine Godon, Jimmy Alarcan, Fanny Brunissen, Marina Grimaldi, Patrick Balaguer, Albert Braeuning, Florent Allais
While crucial for life on Earth, significant exposure to solar light can have negative effect on human skin (1). It has been widely shown that UV-B (280–320 nm) and UV-A (320–400 nm) radiations penetrate most of the skin barriers, leading to the formation of Reactive Oxygen Species (ROS) (2), which in turn, induce oxidative stress and damage such as skin photoaging, inflammations, lipid membrane alteration or DNA mutation (3–6). In order to protect oneself against those radiations, a wide range of sunscreens is available, containing either mineral (i.e. TiO2, ZnO) or organic filters (i.e. octinoxate, avobenzone or octocrylene). Those petroleum-based organic filters are increasingly criticized due to their negative impact on both humans and the environment (i.e. endocrine disruption, coral bleaching, toxic degradation products) (7–9). In response to this issue, some countries have started to ban such filters, for instance, Hawaii issued a bill against the use and sale of avobenzone- or octinoxate-containing sunscreens from January 1st, 2021 (10). Consequently, offering a bio-based alternative, with reduced environmental and public health risks, is essential to protect humans against those harmful radiations while reducing or eliminating the negative impact of such UV filters.
A systematic approach to methyl cinnamate photodynamics
Published in Molecular Physics, 2021
Konstantina M. Krokidi, Matthew A. P. Turner, Philip A. J. Pearcy, Vasilios G. Stavros
In order to combat the harmful effects of UV radiation, chemical UV-filters are included within commercial sunscreen formulations [10–13], providing a front-line defence to excessive UV exposure. UV-filters are molecules that protect epidermal cells by absorbing UV-A and UV-B radiation before it can reach, and cause damage to, their DNA. An ideal UV-filter used in such formulations should therefore exhibit photodynamic processes which, upon UV absorption, lead to effective dissipation of the excess energy. This energy dissipation should be in the form of harmless heat and without the production of detrimental reactive photoproducts [14]. However, a number of the most well-known UV-filters used widely in commercial sunscreen formulations, such as oxybenzone and avobenzone, have been found to degrade following prolonged exposure to UV radiation [15,16]. Oxybenzone, among other UV-filters, is additionally known to disrupt the endocrine system [17,18]. Moreover, several studies have reported photoallergic reactions as a result of using sunscreen formulations containing chemical UV-filters [19–23]. Consequently, there is an ever-increasing demand for next generation sunscreen formulations which utilise more efficient and, importantly, safer UV-filters. This underscores the necessity to better understand the photochemistry and photophysics that govern current and prospective UV-filters.