A Comparative Study on the Physicochemical Properties and Structural Conformation of Acid-Soluble Collagens from Four Swim Bladders

Fish-derived collagens represent highly promising alternatives to terrestrial matrices for advanced biomedical applications, yet how species-driven evolutionary divergence modulates their underlying supramolecular architectures and functional phenotypes remains poorly understood. Here, we systematically isolate and structurally map acid-soluble Type I collagens from four geographically and phylogenetically distinct teleost swim bladders: China large yellow croaker, New Zealand large yellow croaker, basa fish, and silver carp. Electrophoretic profiling confirmed the preservation of intact Type I collagen frameworks characterized by prominent α1 and α2 chains. The results show that the China large yellow croaker achieves a maximum yield of 23.0%, surpassing the lowest-yielding New Zealand matrix at 14.2% by a 62.0% relative margin. This China yellow croaker matrix exhibits superior primary structural preservation, featuring a peak glycine content of 20.48% and high triple-helical stability. Crucially, macro-thermal resilience tracks evolutionary climate adaptations. Tropical freshwater basa fish displays the highest denaturation temperature of 47.12 °C to establish a 10.63 °C thermal gap over cold-water New Zealand yellow croaker, whereas colloidal dispersion peaks in silver carp via a high ζ-potential of 32.3 mV and a minimum supramolecular aggregate diameter of 465.2 nm. Furthermore, scanning electron microscopy revealed distinct interspecific variations in sponge microstructures, where the New Zealand yellow croaker collagen displayed a relatively open, interconnected porous network. Coupled with localized triple-helical structural relaxation, this matrix achieved a peak hydroxyl radical scavenging efficacy of 53.2% at a concentration of 5 mg/mL. These findings provide a molecular blueprint for rational selection and engineering of source-specific fish-derived collagens as advanced biomaterials.