The skin is our outer boundary surface of the body and is constantly exposed to various environmental influences that can affect the processes in the skin. However, to be able to perform its protective purpose, its barrier function must be well functioning. Antioxidants play an important role in this. Vitamin C is a natural exogenous antioxidant that has a good ability to scavenge radicals and regenerate free tocopheryl radicals into tocopherol (vitamin E). The latter, among other things, prevents the peroxidation of lipids of the stratum corneum. Novel colloidal carrier systems represent favourable characteristics for dermal delivery of active substances. Self micro-emulsifying systems increase the solubility and dissolution rate of poorly soluble active substances. Microemulsions enable controlled release of the active substance and facilitate the penetration of the active substance into the skin. Liquid crystals (lamellar) are also able to release the active substance in a controlled manner, due to their structural similarity to intercellular lipids within the epidermis.
The main aim of the diploma thesis was to determine the influence of structurally different lipid based systems on vitamins C and E release profiles. For this purpose, we studied three different nanostructured delivery systems; self micro-emulsifying system, water-in-oil microemulsion and lamellar liquid crystals consisting of the same components (lecithin, Tween 80, isopropyl myristate, butanol, water) but differ in quantitative structure, in which vitamins C and E were incorporated. The in vitro release test was performed using Franz diffusion cells. Rheological measurements confirmed that lamellar liquid crystals are the most viscous system, and its consistency increased even more after the incorporation of vitamins. The viscosity of other two tested systems did not change significantly after the incorporation of vitamins. The in vitro release test results show that viscosity affects the release profile of vitamins, as the least vitamin C was released from liquid crystals and the most from the water-in-oil microemulsion. We also confirmed that the release profile of vitamins C and E from the carrier systems is also affected by the inner structure of the systems and the solubility of the vitamin, as most vitamin E was released from liquid crystals and least from the self micro-emulsifying system. The results show that more vitamin C than vitamin E was released from all three carrier systems. Based on experimental results, we may conclude that lamellar liquid crystals are the most suitable systems for the dermal delivery of vitamins C and E, both in terms of inner structure and consistency, as well as the release profile.
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