Effects of a LED/UV nail polish dryer in human keratinocytes: focus on cytotoxicity and photoprotection

• Autor(a) principal: Lopes, Alexandra Catarina Ferreira
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/41027
• topic: Nail polish dryer; Helioguard™ 365; Benzophenone-3; Cytotoxicity; ROS; Photoprotection

Nail polish dryers are radiation-emitting devices used to dry and cure nail polishes, mostly required in the popularized gel nails making process. The radiation emitted by these devices is mostly situated in the ultraviolet A (UVA) range, but also in the visible light spectrum (in the case of those equipped with light emitting diodes, LEDs). Due to the increasing use of these devices and the scientific concerns related to the UVA radiation effects on human skin, the safety of the UV-nail polish dryers has been questioned. Recently, cytotoxic, genotoxic and mutagenic effects were demonstrated in human and murine cells. Bringing these findings together with previous reports associating the use of these devices and skin cancer, a wider evaluation of the effects involved is required, as well as exploring photoprotection strategies. The present dissertation pretended to evaluate the cytotoxic effects of a LED/UV nail polish dryer by accessing the effects on cell viability and intracellular reactive oxygen species (ROS). For that, human keratinocytes were exposed to the radiation during different time periods, namely: one, two or three cycles of 90 seconds, interspaced by 5 minute intervals, in the case of non-singular exposures. This approach aimed to mimicry the common procedure of gel nails making. Cytotoxic effects were confirmed both through the cell viability decrease observed 72 hours after all the radiation treatments, and intracellular ROS levels increase, 72 hours after exposing to two cycles of irradiation. Furthermore, a spatial division of the surface underneath the lamps, both in terms of irradiance received and cell cytotoxicity, allowed a better understanding of the effects observed. Three levels of severity of effects were associated to differently positioned cultured cells. Thus, the cells subjected to a level 1, 2 and 3 demonstrated the lowest, middle and higher levels of cytotoxicity, respectively. Based on that categorization, a slightly different spatial division was performed for each evaluation (cell viability and intracellular ROS content), and an agreement with the irradiance values heterogeneity was found for both cases. In the most severe level of exposure (level 3), mortality rates of almost 95% were observed for the longer exposure (three cycles of 90 seconds). In the case of the intracellular ROS content, an increase of 110% was also observed for level 3, when exposing to two cycles of irradiation. Finally, the photoprotective capacity against the radiation emitted by this particular nail polish dryer was evaluated for a commonly used UV-filter (Benzophenone-3) and a natural UV-screening mixture based on marine macroalgae compounds (Helioguard™ 365). No photoprotective effect was observed for the compounds tested. The results of the present dissertation reinforce the need to better characterize the cytotoxicity caused by the radiation emitted by these devices, as well as to continue the evaluation of the photoprotective capacity of UV-filters or sunscreens. The wide range of nail polish dryers available on the market, in function of each radiation source, should be considered. Public awareness on the potential risks associated with the use of these devices and, specially, to the need of using efficient photoprotective agents, should be cogitated.