Nanostructured Lipid Carriers (NLC) in dermal and personal care formulations

Abstract

The present work concentrates on the development of nanostructured lipid carriers (NLC) for dermal application. It also shows the advantages of using the NLC in dermal and personal care formulations and studies the factors that affect these advantages. In the chapter of Production optimization of NLC The optimal NLC production conditions were 2 homogenization cycles, 800 bar homogenization pressure and a homogenization temperature about 10°C above the melting point of the solid lipid. Increasing the surfactant concentration led to a decrease in the particle size. On the other hand, the particle size did not noticeably decrease when the concentration of the surfactant was over 2%. Moreover, excessive amount of surfactant led to foam formation during homogenization. After homogenization the formulations were cooled down using a 15°C water bath. Coenzyme Q 10 and black currant seed oil loaded NLC and retinol-loaded NLC were produced and the physicochemical properties of these formulations were evaluated. The production of physically stable formulations, in terms of particle size, was successful for both formulations. By incorporating Coenzyme Q 10, black currant seed oil and retinol in NLC the chemical stability of these materials was improved. The developed formulations can be used in final topical products to achieve improved chemical stability. Regarding the Coenzyme Q 10 and black currant seed oil loaded NLC, the formulation based on carnauba wax and PlantaCare 2000 had the best physical and chemical stability. The most stable retinol formulations based on Retinol 15 D were the formulations containing 1% (w/w) retinol. The best two formulations were the NLC of the lipid Compritol ATO 888 and the surfactant Tween 80 and the NLC of the lipid Elfacos C 26 and the surfactant Miranol 32 (about 80% remaining retinol at RT after 1 year). Moreover, the formulation based on Retinol 50 C (containing 3% (w/w) retinol) showed a very good physical and chemical stability (about 77% remaining retinol at RT after 1 year). The third part of the work could show that placebo NLC block UV radiation. This makes it possible to produce cosmetic products that have photoprotection properties without the need of using any sunscreens in the formulation. To achieve a maximum UV blocking activity the particle size of the NLC was optimized (about 400 nm). Butyl methoxydibenzoylmethane (BMBM) as a model for organic UV blockers and titanium dioxide (TiO2) as inorganic UV blocker, were successfully incorporated in NLC. This incorporation increased the UV blocking activity of these UV blockers. Hence, it is possible to reduce the UV blocker concentration in the finished products while maintaining the desired high UV blocking activity. Different perfumes were successfully incorporated in NLC. Factors influencing the perfume release profile were studied. It was found that the interaction between the perfume and the solid lipid is an essential factor. When the perfume was enclosed in the solid lipid matrix a slower release of the perfume from the lipid matrix of the NLC was achieved. This release follows Higuchi equation for release from a solid matrix. Fine tuning of the release profile was achieved by controlling the particle size and by changing the type of lipid and surfactant used. Smaller particle sizes gave faster perfume release. Positively charged NLC were successfully produced and the positive charge maintained the NLC on the fabrics for a prolonged perfume release.