Silica hydrogel composites as a platform for soft drug formulations and cosmetic compositions

In this work, silica hydrogels are considered as potential basis for the development of new soft drug formulations and cosmetic products. For this purpose, the hydrogel drug-silica composites having pH ∼7 were synthesized by two-step sol-gel method under different synthesis conditions (concentration of acidic catalyst, addition of co-solvent (DMSO), drug loading). Lipoamide, a powerful antioxidant, was used as the drug. Since biomedical functionality of the hydrogel materials is largely determined by their mechanical properties, response of the hydrogels to deformation under compression, tension and shear was measured, and their thixotropic behavior was also studied. The release kinetics of the drug from the hydrogel composites was investigated in vitro. It was shown that the synthesis conditions influenced significantly on the indicated properties of the synthesized hydrogels. The compression Young's moduli and the thixotropic indexes decreased with increasing catalyst concentration and drug loading due to the destabilizing effect of these factors on microstructure of the hydrogels. However, DMSO promoted improvement of the mechanical properties of the hydrogels. The tensile properties of the hydrogels were very low. It was found that the drug release from the hydrogel composites followed zero order kinetic for two days due to mechanism of anomalous diffusion. The drug release from the hydrogel composites prepared using the highest catalyst concentration and high drug loading is characterized by higher rate constants. • Silica hydrogels (HGs) and their drug composites with pH∼ 7.0 were synthesized (80). • Effects of synthesis conditions on properties of hydrogel materials were revealed (81). • Increasing catalyst concentration and drug loading destabilize hydrogel structure (81). • Addition of DMSO improves mechanical properties of hydrogel materials (69). • Drug release from hydrogel composites follows zero order kinetic for two days (77).