Preparation of recombinant humanized type III collagen and its structural characterization and safety evaluation

• A high-yield recombinant humanized type III collagen-expressing E. coli strain was constructed, achieving a yield of 10 g/L in a 5 L fermenter. • The purified product showed structural fidelity with the designed sequence, as confirmed by peptide coverage and molecular mass analysis. • The melting temperature of the purified collagen was 79.72 °C, indicating high thermal stability. • Safety evaluations (intradermal reaction, skin sensitization, acute systemic toxicity, cell proliferation and migration) demonstrated good biocompatibility.