Gelatin methacryloyl (GelMA) is an ideal bioink that is commonly used in bioprinting. GelMA is primarily acquired from mammalian sources; however, the required amount makes the market price extremely high. Since garbage overflow is currently a global issue, we hypothesized that fish scales left over from the seafood industry could be used to synthesize GelMA. Clinically, the utilization of fish products is more advantageous than those derived from mammals as they lower the possibility of disease transmission from mammals to humans and are permissible for practitioners of all major religions. In this study, we used gelatin extracted from fish scales and conventional GelMA synthesis methods to synthesize GelMA, then tested it at different concentrations in order to evaluated and compared the mechanical properties and cell responses. The fish scale GelMA had a printing accuracy of 97%, a swelling ratio of 482%, and a compressive strength of about 85 kPa at a 10% w/v GelMA concentration. Keratinocyte cells (HaCaT cells) were bioprinted with the GelMA bioink to assess cell viability and proliferation. After 72 h of culture, the number of cells increased by almost three-fold compared to 24 h, as indicated by many fluorescent cell nuclei. Based on this finding, it is possible to use fish scale GelMA bioink as a scaffold to support and enhance cell viability and proliferation. Therefore, we conclude that fish scale-based GelMA has the potential to be used as an alternative biomaterial for a wide range of biomedical applications.

Collagen hydrolysates derived from tuna tendons have potential applications in various industries, but sterilization is crucial to ensure their safety. This study investigated the effects of ethylene oxide (EtO), beta radiation, and gamma radiation sterilization methods on the structural and functional properties of collagen hydrolysates using nuclear magnetic resonance (NMR) spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and differential scanning calorimetry (DSC). EtO sterilization caused significant physical and chemical changes in the hydrolysates, as evidenced by the altered appearance and ¹H-NMR and ¹³C-NMR spectra. In contrast, beta and gamma radiation did not induce notable changes in the physical characteristics and NMR spectra. MALDI-TOF MS analysis revealed slight alterations in the molecular weight distribution after sterilization, with beta irradiation causing a minor decrease and gamma irradiation and EtO leading to small increases. DSC analysis showed shifts in the heat absorption peaks after sterilization, indicating changes in the thermal properties. The findings suggest that while all three methods effectively sterilize collagen hydrolysates, EtO causes more significant structural modifications compared to beta and gamma radiation. This study provides valuable insights into the impact of sterilization on collagen hydrolysates, facilitating the selection of appropriate methods for specific applications.