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Physical sunscreens
... Moreover, Sayre and Kollias showed that these properties of inorganic filters maybe found into absorptive semiconductor materials including TiO2 and ZnO and non-absorptive scattering materials such as barium sulfate and talc [5]. ...
Skin cancer is the most common malignant cancer with an incidence of 1 million cases/year. It is well known that exposure to UV radiation from sunlight leads the most frequent risk factors for several skin disorders including skin cancer. Sunscreen filters represent a valid protection against dangerous effects derived from UV radiation, and they can be divided in organic and inorganic UV filters. Adding, at the product formulation, molecules with booster effect, or also substances that can increase the protecting effectiveness via synergic mechanisms, can further enhance their protection activity. Moreover, this approach leads to develop formulations with high SPF (Sun Protection Factor) with a reduced content of UV filters, this is in line with the recent decisions of yet a few countries (Palau, Thailand, Philippines, and Hawaii) to ban some sunscreen filters to preserve marine environments (i.e., reef). In this work, a new class of sunscreen UV filters has been synthesized, by means the combination of physical filter and Oxisol, an antioxidant molecule with booster effect. In this study, the synthesis of new physical multifunctional ingredients is reported, by means the direct surface functionalization of inorganic filters (in particular TiO2) with Oxisol. In this study, the full characterization of these multifunctional ingredients is also reported, in addition to the cytotoxicity tests, the photocatalytic activity and the rheological properties involved on skin application.
... The first sunscreen moisturizer ever known was produced in France by Eugene sculler in 1935. In 1946, sunscreen produced by Franz Greiter was commercially introduced into the market [16]. Schulze was credited with introducing the idea of SPF in 1956, thereby approximately estimating the effectiveness of sunscreen when applied to the skin evenly at 3mg/cm 2 , and the first Greiter's cream was appraised later to have SPF of 2. However, sunscreens have become a very essential skincare product worldwide. ...
... The first sunscreen moisturizer ever known was produced in France by Eugene sculler in 1935. In 1946, sunscreen produced by Franz Greiter was commercially introduced into the market [16]. Schulze was credited with introducing the idea of SPF in 1956, thereby approximately estimating the effectiveness of sunscreen when applied to the skin evenly at 3mg/cm 2 , and the first Greiter's cream was appraised later to have SPF of 2. However, sunscreens have become a very essential skincare product worldwide. ...
This research work aims at synthesizing two different types of moisturizers: a body butter and a lotion. Based on the methodology, three samples of the body butter and lotion was produced, by varying the percentage of zinc oxide and Shea butter, the samples were analyzed with a UV-spectrophotometer to determine the transmittance and absorbance strength which was in turn used to determine the SPF. Vaseline which is a standard organic lotion was also analyzed to determine the transmittance, absorbance strength and SPF. The results were compared. Of all the moisturizers synthesized in this research, the lotion which had 10% zinc oxide had the highest absorbance strength, and hence the highest SPF. Therefore, it was concluded that a minimum of 10% zinc oxide should be used in the production of sunscreen moisturizers to provide moderate sun protection.
... The absorption coefficient (α) spectra are shown in figure 2(F). In the case of talc and cat-litter, these spectra show band edges at 3.0-3.5 eV (350-400 nm), consistent with insulating behaviour but perhaps somewhat lower than the values of ~3.5 eV expected for talc [59] and >5 eV normally found for layered silicates [60]. However for clay the absorption coefficient never reached zero, even at high wavelength, implying the presence of metallic impurities. ...
Liquid phase exfoliation (LPE) has proven to be a versatile technique to produce uncharged 2D nanosheets from layered crystals. However, almost all studied starting materials consist of pure powder or crystals purchased from chemical suppliers. To test the true versatility of this process, we have attempted to process three starting materials with varying degrees of purity and composition. We subjected talcum powder (principle component: the layered compound talc), Fuller's earth cat litter (known to contain layered silicate compounds, most notably palygorskite and montmorillonite/bentonite) and beach sand (suspected to contain small amounts of layered clays) to a standard LPE procedure (sonication in a surfactant solution followed by centrifugation). In all cases, we produced dispersions containing large quantities of nanosheets with almost all non-nanosheet material removed by the centrifugation step. Powder x-ray diffraction identified the nanosheets produced to be talc, a bentonite/palygorskite mixture and mica for the three starting materials respectively. Particularly interesting is the fact that bentonite, palygorskite and mica sheets are charged and are always accompanied by charge balancing counterions. We believe this is the first example of LPE being used to exfoliate and purify charged layered crystals.
Both ultraviolet radiation and visible light have biologic effects on the skin. Visible light can induce erythema in light skinned individuals and pigmentation in dark skinned individuals. Broad spectrum sunscreens protect against ultraviolet radiation and do not adequately protect against visible light. For a sunscreen to protect against visible light, it must be visible on the skin. Inorganic filters (also known as mineral filters), namely, zinc oxide and titanium dioxide, are used in the form of nanoparticles in sunscreens to minimize the chalky and white appearance on the skin; as such, they do not protect against visible light. Tinted sunscreens use different formulations and concentrations of iron oxides and pigmentary titanium dioxide to provide protection against visible light. Many shades of tinted sunscreens are available by combining different amounts of iron oxides and pigmentary titanium dioxide to cater to all skin phototypes. Therefore, tinted sunscreens are beneficial for patients with visible light-induced photodermatoses and those with hyperpigmentation disorders such as melasma and post-inflammatory hyperpigmentation.
The DSc thesis is in the field of theoretical chemistry.
The tautomerism of five-membered heterocyclic compounds with two heteroatoms in the ring, as well as nitroso-oxime tautomerism in cyclic compounds, is studied. It is found that the semi-empirical MNDO, AM1 and PM3 quantum-chemical methods are not appropriate for studying this type of compounds - non-empirical quantum chemical methods including electron correlation of higher order are necessary.
A two-step mechanism of intramolecular proton transfer reactions in diotropic systems, Schiff bases and 2,2’-bipyridyl-3,3’-diol, is proposed.
The structure of 2-carboxyamide-indane-1,3-dione is determined. It is shown that the compound exists in two tautomeric forms turning rapidly into each other, in solution as well as in solid state.
A theoretical description of the mechanism of excited state proton transfer in benzoxazols and aromatic ketones is proposed. It is shown that proton tunneling occurs through the energy barrier in the excited state reactions for these compounds. A new mechanism of intramolecular hydrogen transfer in triplet excited state in 1,4-dimethyl-tetralone is put forward.
Bearing in mind the UV spectral characteristics and high photostability of 2-acetyl-indan-1,3-dione, it is suggested that this compound is suitable as an active component in sunscreens and sun lotions.
A mechanism of water-assisted tautomeric conversion in azolidines and 5-fluorouracil is presented, leading to the occurrence of “rare” tautomeric forms.
Objectives: Synergistic effects between UV absorbers can produce many advantages in sunscreen products such as: decreasing topical irritation, allergic reactions and skin absorption of sunscreen agents. Methods: six currently used UV filters of Eusolex® series (232, 6007, HMS, OS, 4360 and 9020) were studied. Various concentrations from each sunscreen were prepared in isopropyl alcohol and UV spectrums of them were taken in 290-400nm with reference concentration of each UV filters. Six commonly used solvents were used and the best solvent was selected. The best AUC for all sunscreens were obtained from their solutions in isopropyl alcohol as solvent. Single solutions and all probable binary mixtures of them were prepared and compared with another. Synergistic effects of two sunscreen agents in binary systems were compared based on AUCs and their absorption intensity in 310nm. Results: Maximum synergistic effects in UVB wavelengths was related to Eusolex® 9020- Eusolex® 4360 combination with 10%-90% ratio (about 64% in AUC and 65.7% in 310nm absorption intensity). Combination of Eusolex® 9020 and UVB filters with low weight retios also significantly improved AUC of Eusolex® 9020 in UVA wavelengths (up to 61% in combination with Eusolex® 6007). Eusolex® HMS and Eusolex® OS also showed markedly synergistic effect in combination with Eusolex® 4360 with low ratios (47% and 18.9 % respectively). Conclusion: these results demonstrated that exactly choosing the type and ratios of UV filters in sunscreens can greatly improve efficiency and decrease effective concentration of formulation active ingredients.
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