Gelapin, a degradable genipin cross-linked gelatin hydrogel

The synthesis of genipin cross-linked gelatin (Gelapin) hydrogel materials is presented. Gelapin hydrogels were comprehensively characterised through chemical, mechanical and physical analysis techniques. It was found that the hydrogels could be cross-linked to up to 90% using a genipin concentration of 24.4% (w/w). The hydrogels reach a stable swollen state and cease leaching of residual starting materials after 72 h in phosphate buffered saline solution at 37 °C. The proteolytic degradation of Gelapin by collagenase is tuneable through manipulation of the material composition with the rate of degradation ranging from 60 mg per day up to 500 mg per day. The mechanical characteristics (at 37 °C) are controllable through adjustment of the gelatin and genipin concentrations resulting in compressive stress-at-failure values ranging from 26 kPa to 300 kPa. Gelapin gels were found to become more elastic and ductile during proteolytic degradation up to 70% mass loss. The ability for vascularisation of these hydrogels was demonstrated using a chick embryo chorioallantoic membrane assay method.