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Development of Topical Formulations Containing 20% of Coated and Uncoated Zinc Oxide Nanoparticles: Stability Assessment and Penetration Evaluation by Reflectance Confocal Laser Microscopy
Assis Dias Alves, G.D.; Cuelho, C.H.F.; Fonseca, M.J.V.; Maia Campos, P.M.B.G. Development of Topical Formulations Containing 20% of Coated and Uncoated Zinc Oxide Nanoparticles: Stability Assessment and Penetration Evaluation by Reflectance Confocal Laser Microscopy. Cosmetics2024, 11, 6.
Assis Dias Alves, G.D.; Cuelho, C.H.F.; Fonseca, M.J.V.; Maia Campos, P.M.B.G. Development of Topical Formulations Containing 20% of Coated and Uncoated Zinc Oxide Nanoparticles: Stability Assessment and Penetration Evaluation by Reflectance Confocal Laser Microscopy. Cosmetics 2024, 11, 6.
Assis Dias Alves, G.D.; Cuelho, C.H.F.; Fonseca, M.J.V.; Maia Campos, P.M.B.G. Development of Topical Formulations Containing 20% of Coated and Uncoated Zinc Oxide Nanoparticles: Stability Assessment and Penetration Evaluation by Reflectance Confocal Laser Microscopy. Cosmetics2024, 11, 6.
Assis Dias Alves, G.D.; Cuelho, C.H.F.; Fonseca, M.J.V.; Maia Campos, P.M.B.G. Development of Topical Formulations Containing 20% of Coated and Uncoated Zinc Oxide Nanoparticles: Stability Assessment and Penetration Evaluation by Reflectance Confocal Laser Microscopy. Cosmetics 2024, 11, 6.
Abstract
The introduction on Zinc oxide nanoparticles (ZnOn) in sunscreens solved the issue of poor spreadability of these formulations, which often left a white film on the skin. However, safety concerns have arisen regarding the topical application of ZnOn. Some studies employed commercial sunscreens to address the safety issues of the topical application of ZnOn; however, commercial formulations are often complex and contain a wide range of ingredients that could attenuate the potential damage caused by the ZnOn. Therefore, in this study we aimed to develop a simple stable formulation containing 20% of coated and uncoated ZnOn, characterize the formulations and the nanoparticles, and assess the skin penetration in Franz diffusion cell. The Feret's diameter for the uncoated and coated ZnOn was 137 nm and 134 nm, respectively. For the uncoated ZnOn the hydrodynamic size in water was 368 nm and for the coated ZnOn, the average hydrodynamic size in ethyl acetate was 135 nm. The incorporation of ZnOn led to formulations more consistent and easier to spread, as suggested by the lower work of shear and higher values of firmness, cohesiveness, consistency and index of viscosity compared with the vehicle. The stability assessment at 45ºC suggested that the formulations containing the ZnOn were stable for 30 days and the vehicle was stable for 90 days. The assessment off the skin penetration by reflectance confocal laser microscopy indicated that the formulations did not permeate into the deepest layers of the skin, but accumulated on the skin furrows, hair and hair follicle.
Keywords
Transmission electron microscopy; dynamic light scattering; franz diffusion cell; texture; rheology
Subject
Chemistry and Materials Science, Nanotechnology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
