DEFORMATION PROPERTIES OF HYDROGEL COMPOSITES OF Α-LIPOIC ACID WITH COLLOID SILICA

Abstract

Hydrogels are widely used as the basis of soft drug formulations and cosmetic compositions (ointments, creams, gels, masks, dermal fillers, etc.). Deformation properties of these products are very important from the point of view of the convenience and safety of their application, as well as optimization of their production process. In this work, inorganic silica hydrogels are considered as a promising basis for the development of new soft drug formulations and products for cosmetology. The hydrogel composites of colloid silica with α-lipoic acid which is a well-known powerful antioxidant used for treatment of various skin diseases were synthesized. Besides, the drug has a rejuvenating effect on the skin. Taking into account the indicated potential application of the hydrogels and the methods of their administration (transdermal, injection), the hydrogels had a pH of 6.6- 7.4. Pure silica hydrogels and their composites with α-lipoic acid were synthesized by a two-step sol-gel method. Using the method of optical microscopy, it was shown that they have a highly porous surface. The deformation properties of the synthesized hydrogels under compression, tension, and shear were determined. It is shown that the synthesized hydrogels have a certain elasticity under axial compression, thixotropy and exhibit pseudoplasticity. The effects of the synthesis conditions (concentration of the catalyst for silica sol formation, the amount of the introduced drug) on the deformation properties of the composites have been established. The effects were explained in terms of the influence of these factors on the strength of the three-dimensional silica framework of the hydrogel materials. The discovered deformation properties of silica hydrogels make them promising for the development of new soft drug formulations for topical application.