RHEOLOGICAL AND DEFORMATION PROPERTIES UNDER COMPRESSION AND TENSION OF HYALURONIC ACID ENCAPSULATED IN SILICA HYDROGELS

Hyaluronic acid is a well-known anti-inflammatory drug that is widely used clinically to treat various diseases of the joints, intestines, and skin. Due to its unique hydrating properties, hyaluronic acid hydrogels are part of a variety of cosmetic products. However, the low mechanical properties of hyaluronic acid hydrogels greatly limit their practical application. To overcome this drawback, hyaluronic acid with various average molecular weights (low molecular weight 20-50 kDa, middle molecular mass 50-100 kDa, and high molecular weight 1000-1500 kDa) was encapsulated in colloidal silica hydrogels by sol-gel method. The resulting composite hydrogels contained 1% and 2% acid. The effects of the amount of hyaluronic acid in the hydrogels and its average molecular mass on the deformation properties of the composite hydrogels during compression and stretching, as well as on their thixotropic properties were studied. The results showed that encapsulation of the middle and high molecular weight hyaluronic acid in silica hydrogels increases the resistance of the resulting materials to compressive forces. At the same time, an increase in the acid content in composite hydrogels from 1% to 2% contributes to the growth of these characteristics only for the high molecular mass hyaluronic acid. For the low and middle molecular mass acid the values of the compression characteristics coincide within the error range. The average molecular mass of the acid and its amount do not affect the tensile deformation characteristics. Unlike pure acid hydrogels, the composite hydrogels have thixotropic properties. The composite hydrogels with the high molecular weight acid have the highest thixotropy index, which is explained by the presence of a reinforced three-dimensional network in such composite hydrogels and their stronger structure compared to the hydrogels containing the acid with the lower molecular weight. A similar effect was observed with an increase in the content of middle and high molecular weight acid in the hydrogels. However, an increase in the content of the low molecular mass acid leads to a decrease in the value of the thixotropy index, which may be due to the special conformation of the low molecular mass acid in solution and its intensive interactions with silica particles in the hydrogel framework, which lead to the weakening of this framework. It was found that an increase in the average molecular mass of hyaluronic acid and its content in the composite hydrogels leads to a decrease in the degree of restoration of the structure of hydrogels after exposure to shear forces. The more interwoven (or entangled) hyaluronic acid network is and the more its molecules are contained in the composite hydrogel, the less fully its viscosity (structure) is restored. Overall, the results have shown that encapsulation of hyaluronic acid in a silica hydrogel matrix improves several important functional properties of the drug, and the resulting composite hydrogels are attractive materials for the development of topical and injectable drug systems based thereon. For citation: Selivanova V.O., Belyaeva M.A., Dolinina E.S., Parfenyuk E.V. Rheological and deformation properties under compression and tension of hyaluronic acid encapsulated in silica hydrogels. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2026. V. 69. N 3. P. 30-37. DOI: 10.6060/ivkkt.20266903.6718.