Development and characterization of Poly (vinyl alcohol) based hydrogels for potential use as an articular cartilage replacement

Hydroxyapatite (HA) reinforced Poly(vinyl alcohol) (PVA) hydrogel composites has been proposed as a promising biomaterial to replace diseased or damaged articular cartilage. Here, PVA/in-situ produced HA hydrogels with 0, 3 and 7.5 wt.% of HA content were obtained by freezing/thawing technique. Thermal, structural and mechanical characterizations were carried out. SEM micrographs revealed that HA was homogeneously distributed in PVA until 3 wt.% whereas partial agglomeration was observed for higher contents (7.5 wt.%). No significant changes were observed in the glass transition temperature (the average value was near to 78 °C ± 3 °C), the melting point and structural water content whereas the gel fraction slightly increased (from 0.72 to 0.78) with the increase the content of HA. The absorbed water decreased (from 85.7% to 80.5%) as a function of HA content The stress–strain curves were really different in hydrated and non-hydrated conditions, changing from non-linear, in presence of water, to linear behavior in a dried state, being in the first case consistent with the articular cartilage . The lowest friction coefficient was obtained for samples with 3 wt. % HA (0.067 ± 0.049), which is, together with a high resistance (721 ± 25 kPa), an important property for materials that will be used as articular replacement. The results indicate that this hydrogel could be used, after other studies, as articular cartilage replacement.