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Increased UV absorption properties of natural hydroxyapatite-based sunscreen through laser ablation modification in liquid
摘要： Sunfilters based on hydroxyapatite (HAp) and iron-containing compounds (Fe2O3 and calcium iron phosphates) are of increasing interest, as they show UV absorption without generating health endanger free radicals (usually observed when other inorganic sunscreens are used). In this paper, laser ablation of solids in liquids has been applied to improve the UV absorption properties of a HAp based Fe-containing sunscreen powder derived from cod fish bones. Two different laser wavelengths were explored (532 and 1064 nm, green and infrared respectively); an improved experimental device was used, to allow a fine control of the volume of the irradiated particles. Results show an increased UV absorbance for the laser-treated powders in comparison with the untreated ones; this can be explained considering the smaller particle size and increased surface area; the higher iron concentration in the powders may also be determinant. Enhanced absorption was also observed in the near-infrared range, making the powders even more suitable for sunscreen applications. The green laser was more effective than the infrared one. Overall, laser ablation showed to be a powerful technique to control the size of the sunscreen particles and tailor their optical properties.
关键词： hydroxyapatite,Liquid laser ablation,UV protection,sunscreen
更新于2025-11-14 15:25:21
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A sustainable multi-function biomorphic material for pollution remediation or UV absorption: Aerosol assisted preparation of highly porous ZnO-based materials from cork templates
摘要： For the first time, highly porous ZnO-based biomorphic materials were synthesised using cork as a natural sustainable template. In the first step, waste cork powder was pyrolysed and converted into inorganic carbon. This template was then infiltrated using a novel approach employing an aerosol of zinc-containing solutions. The infiltrated powders were calcined to convert the precursors into zinc oxide. Depending on temperature, these could form either a ZnO-graphite composite material, or pure ZnO. Their morphology, porosity, microstructure and composition were characterised; their optical band gap energies, ability to adsorb and photodegrade organic pollutants and UV absorption were also assessed. When heated to 350 oC they maintained the 3D porous cork structure, producing a graphite-containing composite material, with both physical adsorption and photocatalytic activity (Eg = 3.19 eV), suitable for environmental remediation. When heated to 700 oC, the powders were pure ZnO (no graphite), and they absorbed in the UV region, hence suitable for use as sunscreen. Doped ZnO ecoceramics were also produced, using silver and aluminium. An addition of 1 mol% Ag improved photocatalysis under solar light. Conversely, adding 2 mol% Al and calcining at 700 oC deactivated photocatalysis, but maintained strong UV absorption, producing a safer sunscreen material (no generation of free radicals). This is the first time that photocatalytic or UV absorption properties of any wood-derived biomorphic material or ecoceramic have been reported.
关键词： sunscreen.,zinc oxide,biomorphic/ecoceramic,aerosol,photocatalyst
更新于2025-10-22 19:40:53
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Electronic State and Photophysics of 2-Ethylhexyl-4-methoxycinnamate as UV-B Sunscreen under Jet-Cooled Condition
摘要： The title compound, 2-ethylhexyl-4-methoxycinnamate (2EH4MC), is known as a typical ingredient of sunscreen cosmetics that effectively converts the absorbed UV-B light to thermal energy. This energy conversion process includes the nonradiative decay (NRD): trans?cis isomerization and finally going back to the original structure with a release of thermal energy. In this study, we performed UV spectroscopy for jet-cooled 2EH4MC to investigate the electronic/geometrical structures as well as the NRD mechanism. Laser-induced-fluorescence (LIF) spectroscopy gave the well-resolved vibronic structure of the S1?S0 transition; UV?UV hole-burning (HB) spectroscopy and density functional theory (DFT) calculations revealed the presence of syn and anti isomers, where the methoxy (?OCH3) groups orient in opposite directions to each other. Picosecond UV?UV pump?probe spectroscopy revealed the NRD process from the excited singlet (S1 (1ππ*)) state occurs at a rate constant of ～1010?1011 s?1, attributed to internal conversion (IC) to the 1nπ* state. Nanosecond UV?deep UV (DUV) pump?probe spectroscopy identified a transient triplet (T1 (3ππ*)) state, whose energy (from S0) and lifetime are 18 400 cm?1 and 20 ns, respectively. These results demonstrate that the photoisomerization of 2EH4MC includes multistep internal conversions and intersystem crossings, described as "S1 (trans, 1ππ*) → 1nπ* → T1 (3ππ*) → S0 (cis)".
关键词： nonradiative decay,photophysics,DFT calculations,trans?cis isomerization,jet-cooled spectroscopy,2-ethylhexyl-4-methoxycinnamate,UV-B sunscreen
更新于2025-09-19 17:13:59
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Development of a Hybrid Chitosan- and Niacinamide-Coupled ZnO Nanoparticle Composite for Sun Protection Application
摘要： Zinc oxide nanoparticles (ZnO) have long been utilized as UV-protective sunscreen components due to their high durability and lower skin irritation while maintaining capability for blocking UV rays. However, the dispersal and transparency properties of ZnO need to be enhanced in order to improve the capacity for creating effective sunscreen through control of the physiochemical properties of ZnO. In this study, chitosan or niacinamide, which are suitable functional cosmetic compounds and effective skin lightening agents, are combined with ZnO for the development of better UV-protective products. Each biocompatible coating material is individually attached on its surface after the synthesis of ZnO. The size is 70 nm using the sol-gel method. Their morphology and chemical structure are characterized by FT-IR, XRD, SEM, TEM, TGA, and zeta potential. The results indicate that approximately 50% of chitosan and 5% niacinamide were coated on the ZnO. To confirm the capacity of each surface-coated ZnO with chitosan and niacinamide as a sunscreen, we measured their transmission, reflectance, and sun protection factor (SPF) using a UV spectrophotometer and SPF. As a result, the niacinamide-coated ZnO shows remarkably lower transmission and high reflectance against UV rays than that of bare ZnO and chitosan-coated ZnO. Furthermore, niacinamide-coated ZnO exhibits great lightening effects. Consequently, these results demonstrate that niacinamide coating is highly effective for the production of sunscreen emulsions.
关键词： Zinc oxide nanoparticles,TEM,FT-IR,SEM,XRD,UV-protective sunscreen,TGA,chitosan,SPF,sol-gel method,zeta potential,niacinamide,sun protection factor
更新于2025-09-12 10:27:22
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752 Clinical effects of LED blue light on skin pigmentation and carotenoid depletion
摘要： The growing evidence that visible light - and especially blue light - contributes to detrimental effects of sun exposure to skin, is becoming a subject of controversial debate nowadays. In this study we aimed to assess blue light-induced pigmentation and carotenoid depletion in vivo. Furthermore, we wanted to show a protective effect of SPF50 sunscreen formulations in a double-blind, placebo-controlled trial. The UVA/B filter system included the microfine particles titanium dioxide and methylene bis-benzotriazolyl tetramethylbutylphenol that extend effectiveness into the blue light range. Comparisons between repetitive irradiation with LED blue light (450 ± 20 nm) with 45 J/cm2 over 5 consecutive days after daily product application (2 mg/cm2) and irradiation only once with 135 J/cm2 after product application over 6 days were performed on the back of the volunteers. The extent of pigmentation and carotenoid depletion was investigated with the assessment of the skin color (ITA°) by chromameter measurements and the in vivo carotenoid concentration via multiple spatially resolved reflectance spectroscopy, respectively. Assessments were performed 5 hours, 24 hours, 1 week and 2 weeks after the last irradiation. Fourteen subjects terminated the study. Both, the single high-dose and the repetitive exposure resulted in comparable, immediate (≤5h) increase of skin pigmentation and carotenoid degradation (p<0.001). Skin pigmentation and carotenoid depletion attenuated on all test conditions already one day after the last irradiation. Both effects were still evident one and two weeks after the last irradiation. The application of the cosmetic formulations including UV pigments that scatter in the blue light range significantly reduced pigmentation (p<0.001) right after irradiation that might be considered for holistic light protection beyond UV.
关键词： carotenoid depletion,SPF50 sunscreen,UVA/B filter system,skin pigmentation,blue light
更新于2025-09-12 10:27:22
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A review of inorganic UV filters zinc oxide (ZnO) and titanium dioxide (TiO <sub/>2</sub> )
摘要： Photoprotection has become integral in the prevention of keratinocyte cancer and photoaging. Organic UV filters such as oxybenzone and octinoxate have become controversial due to their potential impact on the environmental and their potential human health risks. As such, inorganic UV filters, ZnO and TiO2, have become paramount in discussions about photoprotection. ZnO and TiO2 are used in sunscreens as nanoparticles, which denotes a size less than 100nm. The smaller size of these mineral particles increases their cosmetic acceptability by users as they are much less visible after application. ZnO has a broad UVA-UVB absorption curve, while TiO2 provides better UVB protection. Overall, the human health risks with inorganic filters are extremely low given a lack of percutaneous absorption; however, there is potential risk when exposed via inhalation, prompting recommendations against spray sunscreen products with nanoparticles. At this time, the known risk to the environment is low though the risk stratification may evolve with increasing usage of these filters and higher environmental concentrations. The continued practice of photoprotection is critical. The public should be counseled to seek shade, use photoprotective clothing including hats and glasses in addition to sunscreens on sun-exposed skin. For those concerned about emerging evidence of environmental impact of organic UV filters, based on current evidence, ZnO and TiO2-containing sunscreens are safe alternatives.
关键词： environmental impact,titanium dioxide,photoprotection,inorganic UV filters,nanoparticles,zinc oxide,health risks,sunscreen
更新于2025-09-09 09:28:46