Influence of particle size on appearance and in vitro efficacy of sunscreens

Abstract

Nanotechnology applies to diverse sectors of science. In cosmetic area, investments have strengthened the idea that nanoproducts provide innumerable benefits to consumers. Extreme exposition to solar light can cause undesirable effects, thus, adding UV filters in cosmetic products are often used as prevention. Ethylhexyl methoxycinnamate and benzophenone-3 are UV filters widely used in sunscreen formulations, this UV filters absorb UVB and UVA radiation, respectively. In this study, sunscreen formulations were developed as nano and macroemulsion, but composed by the same raw material. Nanoemulsion was obtained by phase inversion temperature method (PIT). Physical and functional properties were evaluated by visual analysis, particle size distribution and by diffuse reflectance spectrophotometry. Achieved nanoemulsion showed bluish brightness aspect, less apparent consistency than macroemulsion, stability longer than 48 hours (22.0 ± 2.0 °C) and bimodal particle size distribution with average (mean) sizes around 10 nm (61%) and 4.5 μm (39%). Macroemulsion showed milky aspect, higher consistency than nanoemulsion, instability after 48 hours (22.0 ± 2.0 °C) and bimodal particle size distribution with average (mean) size around 202 nm (9%) and 10.4 μm (91%). Effectiveness profile of sunscreen formulations remained apparently similar, based on achieved results of in vitro SPF, UVA/UVB ratio and critical wavelength assays.Uniterms: Nanoemulsion. PIT method. Benzophenone-3. Ethylhexyl methoxycinnamate.A nanotecnologia se aplica a diversos setores da ciência. Na área de cosméticos, os investimentos têm reforçado a idéia de que nanoprodutos oferecem inúmeros benefícios para os consumidores. A exposição excessiva à luz solar pode causar efeitos indesejáveis, logo, a adição de filtros UV em produtos cosméticos é frequentemente usada como prevenção. O p-metoxicinamato de octila e a benzofenona-3 são filtros UV amplamente utilizados em formulações de protecção solar, que absorvem radiações UVB e UVA, respectivamente. Neste estudo, desenvolveram-se formulações de protetores solares na forma de nano e macroemulsão, mas compostos pelas mesmas matérias-primas. A nanoemulsão foi obtida pelo método da temperatura de inversão de fases (PIT). As propriedades físicas e funcionais foram avaliadas por análise visual, distribuição de tamanho de partículas e por espectrofotometria de reflectância difusa. A nanoemulsão obtida apresentou brilho azulado, menor consistência aparente quando comparada `a macroemulsão, estabilidade superior a 48 horas (22,0 ± 2,0 ° C) e distribuição de tamanhos de partícula bimodal, com média (média) de tamanhos ao redor de 10 nm (61%) e 4,5 μm (39%) . A macroemulsão apresentou aspecto leitoso, maior consistência aaprente do que nanoemulsão, instabilidade após 48 horas (22,0 ± 2,0 ºC) e distribuição de tamanhos de partícula bimodal, com média (média) de tamanhos ao redor de 202 nm (9%) e 10,4 μm (91%). O perfil de eficácia das formulações fotoprotetoras permaneceu aparentemente similar, com base em resultados ob...

Development and Evaluation of Herbal Sunscreen

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“…Meanwhile the samples were weighed after 6, 24, and 48 hours to determine water flux or evaporation through the filter paper. 19 Every experiment was performed in triplicate.…”

“…After 24 h, the amount of drug in the receptor compartment, the drug remaining on the skin, and the drug in the skin was determined by UV-vis spectrophotometer followed by extracting skin piece in alcohol. 19 …”

“…(Table 12) Occlusion is significant to moisturize and improve partitioning of skin which directly depends on thickness of applied sample layer. 19 …”

Gelatin-based microspheres crosslinked with glutaraldehyde and rutin oriented to cosmetics

“…The records of spectrophotometric absorbance values were performed in the wavelength range between 290.0 and 400.0 nm, rate of progression of 1.0 nm. The analysis was performed in triplicates for obtaining in vitro SPF (Springsteen et al, 1999;Velasco et al, 2008;Silva et al, 2013).…”