Application of kinetic results of doxorubicin release from polyacrylic acid-based hydrogel to Higuchi, Korsmeyer-Peppas, Hixon-Crowell equations

In the study, the release processes of doxorubicin immobilized in the pH-sensitive water-swellable hydrogel sample obtained from the crosslinking of polyacrylic acid with an average molecular weight of 230 kDa with 10% (mass) N,N'-methylene-bis-acrylamide were investigated. The immobilization of doxorubicin on the water-swelling polyacrylic acid-based hydrogel was carried out by the sorption method. The immobilization was monitored for 24 hours and continued until the equilibrium concentration of the drug in the medium was reached. It was found that the immobilization of doxorubicin on the polyacrylic acid-based gel occurs through non-covalent chemical interactions, including hydrogen bonding, electrostatic forces, and hydrophobic interactions. It has been shown that the immobilized organic substance, localized both inside and on the surface of the gel, retains its physicochemical properties for an extended period of time. The controlled release process was studied in a buffer medium of pH=7, which is close to the small intestine medium. The drug release was quantitatively characterized as a function of time. The kinetic data of the release were fitted to various kinetic equations such as zero order, first order, Higuchi square root law, Korsmeyer-Peppas and Hixson-Crowell cube root. It was found that the release of doxorubicin occurs by a non-Fickian diffusion mechanism and the direction of release fits well with the Higuchi model. Thus, the effective viscosity of polyacrylic acid and its ability to complex with metal ions to form gel systems provide the basis for its use in the preparation of materials for isolation formation water and sand protection in oil and gas industry applications. Keywords: polyacrylic acid; hydrogel; immobilization; controlled release; kinetic models.