Recyclable characteristics of hyaluronate-polyhydroxyethyl acrylate blend hydrogel for controlled releases

Hyaluronate-hydroxyethyl acrylate blend hydrogels which have a wide range o f composition and characteristics were investigated. Glycidyl methacrylate derivatized hyaluronate (GMA-HA) were synthesized by coupling GMA to hyalur onate (HA) in the presence of a photoinduced initiator for polymerization. By copolymerizing radically GMA-HA and hydroxyethyl acrylate (HEA) under va rious compositions (weight ratios of HEA and GMA-HA: 1-20), GMA-HA hydrogel s could be prepared in wide ranges of characteristics. These HA-PHEA gels p ossessed the feature that the dried ones recovered completely to the origin al swelling states on repeated runs, i.e. recyclable gels. The water conten ts of these hydrogels in equilibrium swellings in water (W-w) were 0.99-0.8 6, and their viscoelastic properties were measured by a creep. The spontane ous elastic moduli were 1.05 X 10(5)-1.94 X 10(5) N m(-2), and they were me chanically tough. Their effective charge densities were estimated from the partition coefficients of sodium benzoate (NaBA) and decreased from -0.033 to -0.044 mol dm(-3) with increasing contents of HEA. Release of NaBA was s tudied, and the diffusion coefficients were found to be from 6.95 x 10(-10) to 0.12 x 10(-10) m(2) s(-1) with increasing the ratio of HEA. Their diffu sion coefficients were found to be much less than the values estimated from the lattice model. (C) 2001 Elsevier Science B.V. All rights reserved.