Rheological characterization and release properties of inulin-based hydrogels

In the present study the rheological properties of hydrogels obtained through UV irradiation of an aqueous solution of methacrylated inulin (INUMA) alone or in the presence of four different crosslinkers, have been recorded as a function of irradiation time, at two different wavelengths (320 and 365 nm) and fixed frequency and amplitude by oscillatory experiments. Each hydrogel has been analyzed by measurements of the frequency-dependency of the elastic modulus, G′, in the linear viscoelastic region. The amount of polymeric chains giving an elastic response has been correlated to the chemical nature of the crosslinker used together with INUMA. Finally the release properties of the hydrogel exhibiting the highest elastic modulus have been tested by using 5-Fluorouracil, as a model drug, and two different loading procedures. The rheological characterization allowed us to determine the most effective condition (appropriate crosslinker, wavelength and irradiation time) to obtain a strong hydrogel that was able to give a modified drug release in simulated gastrointestinal fluids.