Influence of glutaraldehyde crosslinking degree on gelatin hydrogel surface properties and fibroblast attachment

The modification on surface properties of glutaraldehyde (GTA)-crosslinked gelatin (Ge) hydrogels was investigated in regard of crosslinking degree, and their effect on cell attachment and viability was assessed. Ge-GTA hydrogels were synthesized using different concentrations of GTA (0%, 0.5%, 1.5%, and 2.5%), crosslinking degree was determined by the consumption of NH 2 groups through a ninhydrin assay. Changes on surface properties were determined by FTIR-ATR, SEM, surface free energy, and hardness. Gingival fibroblasts attachment and viability were assessed by microscopic images, resazurin and Live/Dead assays, respectively. Crosslinking degrees of 0%, 46%, 75%, and 88% were obtained for the different GTA concentrations. Hydrogels exhibited a smooth topography with no changes, regardless of crosslinking degree; however, hardness increased whereas polar basic component of the surface free energy decreased with crosslinking degree. Fibroblasts adhered to the hydrogel surface and remained viable, although they exhibited a slightly contracted morphology, with some cells showing a rounded morphology. These effects became more pronounced with increasing crosslinking degree, likely due to the reduction of amine groups. In summary, results show that the surface properties of Ge hydrogels are modified by their crosslinking degree with GTA, which can be optimized for surface free energy, hardness and cell attachment.