Physico-chemical and spectroscopic characterization of hyaluronic acid hydrogels crosslinked with 1,4-butanediol diglycidyl ether (BDDE).

Three hyaluronic acid (HA) - based hydrogels at different HA/1,4-butanediol diglycidyl ether (BDDE) ratios were prepared, and their network characterization and drug release properties were studied. Amoxicillin (AMX) loading and release behavior of the hydrogels were investigated as a function of cross-link density. The percentage release of amoxicillin increased as the cross-link density decreased. In the network characterization, the polymer-solvent interaction parameter (χ) of HA in PBS (pH 7.4) at 25 °C was determined to be 0.418 ± 0.002 from Zimm plot using light-scattering technique. The number average molecular weight between junction points of the hydrogels (Mc¯) was calculated as a function of the HA/BDDE ratio using Flory-Rehner theory. The crosslinking reaction of HA with BDDE was monitored in real-time by 1H NMR spectroscopy, which indicated that the reaction was completed in 55.5 h at 37 °C.