Origin-Dependent Molecular Ordering in Gelatin and Its Impact on Electrospun Nanofiber

Electrospun nanofibrous mats from bovine, porcine, and fish gelatin were systematically fabricated at varying concentrations (15, 20, 25, and 30 wt.%) to investigate the influence of molecular characteristics on morphology, crystallinity, mechanical properties, thermal behavior, and solubility. Optimal ranges of viscosity (0.08-1.47 Pa·s), surface tension (35-50 mN·m^-1), and electrical conductivity (0.18-1.42 mS·cm^-1) were determined to successfully produce homogeneous fibers. Bovine and porcine gelatin, characterized by higher molecular weight and greater proline/hydroxyproline content, exhibited thicker (up to 725 ± 41 nm at 30 wt.%) and less uniform nanofibers due to higher viscosity and surface tension, restricting polymer jet stretching. Conversely, fish gelatin, with lower molecular weight and limited proline/hydroxyproline content, produced significantly thinner (as low as 205 ± 28 nm at 20 wt.%) and more uniform nanofibers. X-ray diffraction analysis revealed distinct crystallinity transitions associated with triple-helix and amorphous structures, dependent on gelatin type and concentration, including the emergence of peaks near 7.9° and 20.1° (2θ) for bovine gelatin. Mechanical tests demonstrated superior tensile strength for bovine gelatin (up to 2.9 MPa at 30 wt.%), balanced properties for porcine gelatin, and exceptional elasticity for fish gelatin. Thermal analysis indicated concentration-dependent shifts in viscoelastic behavior and damping performance. Solubility studies showed rapid dissolution of low-concentration fish gelatin fibers, moderate stability for intermediate-concentration porcine gelatin, and excellent structural retention for high-concentration bovine gelatin. These results demonstrate the potential for tailored gelatin nanofiber design to meet specific functional requirements in biomedical applications.