Purification and characterization of recombinant human type III collagen (COL3A1) fragment (C9).

Collagen, a key structural component of the extracellular matrix (ECM), plays a critical role in tissue repair and regeneration. Compared to traditional animal-derived collagen, recombinant collagen presents enhanced safety and uniformity, avoiding immunogenicity and pathogen transmission. Here, we engineered a recombinant COL3A1-derived fragment, designated C9, composed of nine tandem repeats of the Gly228-Pro281 fragment from human COL3A1. C9 was successfully overexpressed in Escherichia coli under optimized conditions (initial OD600 of 0.8, 0.5 mM IPTG, 10 h, 25 °C). C9 was purified by nickel-affinity chromatography, yielding a final concentration of 3.7 mg/mL. In vitro assays revealed that C9 exhibits substantial antioxidant activity, efficiently scavenging DPPH and ABTS radicals. Cellular assays further demonstrated that C9 exhibited low cytotoxicity and favorable cytocompatibility. In addition, C9 significantly promoted NIH/3T3 cell proliferation, adhesion, and migration. Collectively, these findings highlight the preliminary biological activity of C9 and support its further investigation as a recombinant collagen-derived biomaterial.