Effect of Gelatin Source on Hydrogel Properties and Cell Viability: A Comparison of Bovine, Porcine, and Cold-Water Fish Gelatin Hydrogels.

The selection of a gelatin source is a critical decision in biomaterial design, as its origin dictates key physicochemical and biological properties. This study systematically compares gelatin hydrogels from bovine, porcine, and cold-water fish sources to elucidate how biological origin influences performance as biomaterials. Comprehensive characterization confirmed that the distinct amino acid profiles of each source, verified by FTIR and Raman spectroscopy, govern their material behavior. Fish gelatin exhibited a lower primary amine content (approximately 70% of the free primary amine content of bovine gelatin, quantified by ninhydrin assay), reduced thermal stability (TGA), and a less ordered structural hierarchy (XRD) compared to mammalian gelatins. In cell culture, fibroblast viability was similar across all hydrogels, whereas osteoblast viability was lower on fish gelatin, and both cell types exhibited a more contracted morphology on fish gelatin hydrogels. In pull-off tests, fish gelatin hydrogels displayed a lower slope (-0.32 ± 0.03 N/mm) and a more gradual force decay, remaining attached to the probe over a larger displacement than the mammalian hydrogels (-1.73 ± 0.23 N/mm for porcine and -0.99 ± 0.40 N/mm for bovine). These observations suggest that, although fish gelatin remains a promising alternative to mammalian sources for certain applications, its structural and biological limitations require further material optimization. Notably, the pull-off behavior further suggests a possible niche as a bio-adhesive.