He Youduo, Xu Yongbin
Collagen-based scaffolds are widely utilized in wound healing applications. However, scaffolds prepared from collagen macromolecules typically exhibit isotropy, making it challenging to achieve anisotropic tissue repair and leading to scar formation. They have poor mechanical strength and often require crosslinking agents to enhance their mechanical properties. Small-molecule crosslinking agents can cause cytotoxicity, while large-molecule crosslinking agents can result in material heterogeneity. This study developed a directionally oriented cell scaffold with uniform pore structure through a directed freezing method by using collagen as the matrix and prepared xanthan gum nanoparticles (NPs) as crosslinking agents. The resulting scaffold was designated as the xanthan gum nanoparticle-collagen hydrogel (NPs-COL). Increasing nanoparticle content reduced equilibrium swelling, which stabilized at approximately 100 min, while enhancing static water contact angle and water retention, with more than 60% of the mass retained after 48 h. Mechanical properties, compressive strength, compressive modulus, and toughness approaching values reported for reinforced collagen scaffolds. Hemolysis remained minimal, approximately 0.3% for nanoparticle-modified scaffolds, well below ASTM thresholds. In vitro cytotoxicity assays demonstrated cell viability above 80%, corresponding to ISO 10993-5 Grade 1. In vivo, NPs-COL achieved nearly complete wound closure by day 18, accompanied by an increase in collagen deposition to approximately 40%. Gene expression analysis indicated an elevated BCL2/BAX ratio, consistent with reduced apoptosis. The results indicated that 0.70 mg/mL was the optimal crosslinking agent concentration. The scaffold exhibited a complete internal structure and excellent physicochemical properties, significantly outperforming traditional isotropic hydrogel scaffolds regarding mechanical properties, stability, and biological functionality.