Chemical and Rheological Characterization of a Visco-modulated Polymeric Hydrogel for Biomedical Applications

The growing interest in the regeneration of pathologically altered tissues has involved a multitude of researches in the use of 3D scaffolds. In this scenario, hydrogels have received significant attention. A biodegradable scaffold can be infected by microorganisms; the consequent risk of disease transmission has been reduced through sterilization. However, PVA-, PVP- and PEO-based hydrogel formulations can be subjected to crosslinking reactions during irradiation processes; as a consequence, these hydrogels undergo to undesirable effects such as viscosity increase. Thanks to its antioxidant, anti-inflammatory and antimicrobial properties, hydroxytyrosol could be selected as a valid anti-crosslinking agent: the hypothesis is that radiation-induced crosslinking of hydrogels could be either prevented or limited by tailoring the concentration of hydroxytyrosol. In addition, this work aims to evaluate how the use of a specific kind of buffer saline solution can affect the final characteristics of the optimized hydrogel. The study has been performed by producing gels with PEO, HT and two different buffer (Phosphate and Citrate) solutions. The samples characterization has been carried out – in addition to a visual observation and pH measurement of the prepared hydrogels – on two analytical levels: the rheological and the chemical one (through Fourier-Transform Infrared Spectroscopy and High Performance Liquid Chromatography). The results obtained demonstrate that crosslinking of PEO-based hydrogels could be prevented by tailoring the concentration of hydroxytyrosol introduced as an anti-crosslinking agent. The different salinity of the buffers influences both the viscoelasticity of the gel and the formation of bonds after gamma radiation sterilization. In addition, since hydroxytyrosol results to be more preserved when formulated in Citrate Buffer Solution, the choice of the use of CBS is the most convenient in order to increase the biocompatibility of the final Sterile Hydrogels.