E-Beam Cross-Linking of Complex Hydrogels Formulation: The Influence of Poly(Ethylene Oxide) Concentration on the Hydrogel Properties

In the present study, we report on the complex hydrogels formulations based on collagen-poly(vinyl pyrrolidone) (PVP)-poly(ethylene oxide) (PEO) cross-linked by e-beam irradiation in an aqueous polymeric solution, aiming to investigate the influence of different PEO concentrations on the hydrogel properties. The hydrogel networks' structure and their composition were investigated using equilibrium swelling degree, complex rheological analysis, and FT-IR spectroscopy. Rheological analysis was performed to determine the elastic (G ') and viscous (G '') moduli, the average molecular weight between cross-linking points (Mc), cross-link density (V-e), and the mesh size (xi). The effect of the PEO concentration on the properties of the hydrogel was investigated as well. Depending on the PEO concentration added in their composition, the hydrogels swelling degree depends on the absorbed dose, being lower at low PEO concentrations. All hydrogel formulations showed higher G ' values (9.8 kPa) compared to G '' values (0.2 kPa), which shows that the hydrogels have a predominantly elastic behavior. They presented stability greater than 72 h in physiological pH buffers and reached equilibrium after 25 h. The Mc parameter is strongly dependent on the PEO concentration and the absorbed dose for all hydrogel compositions. The cross-linking density increased with the absorbed dose.