Gel Properties of Carboxymethyl Hyaluronic Acid/Polyacrylic Acid Hydrogels Prepared by Electron Beam Irradiation

Abstract

Semi-synthetic hydrogels made of carboxymethyl hyaluronic acid (CMHA) and polyacrylic acid (PAA) were synthesized using electron beam irradiation. CMHA, with a degree of substitution of 0.87 and a molecular weight of 149 kDa, was mixed with linear PAA and slightly crosslinked PAA (Carbopol). The equal weight ratio of the CMHA-Carbopol blends (10% CMHA, 10% Carbopol) was successfully crosslinked, even at a low irradiation dose of 20 kGy, producing a hydrogel with 60% gel fraction and 430 g/g degrees of swelling. The gel properties of this formulation showed good stability when exposed in PBS (pH 7.4) at 37 °C. Furthermore, the FT-IR spectra of the 10% CMHA, 10% Carbopol blends showed an increase in peak intensity at 1405 cm−1 due to the neutralization reaction between the COOH and COO- groups of PAA and CMHA polymers. The interaction effects between the concentration of CMHA and PAA and varying irradiation doses in the gel properties in CMHA-PAA hydrogels will be explored in a future study. Radiation crosslinking of biocompatible CMHA to other synthetic polymers, such as PAA, provides a cleaner method of producing biomaterials with tunable properties that are ideal for pharmaceutical, medical, and cosmetic applications.