Low-temperature DLP 3D printing of low-concentration collagen methacryloyl for the fabrication of durable and bioactive personalized scaffolds

Digital Light Processing (DLP) bioprinting has revolutionized tissue engineering and regenerative medicine with its speed and precision. Although commonly used in DLP printing, Gelatin Methacrylate (GelMA) lacks the mechanical strength and complex biological signaling of collagen, owing to the absence of collagen's unique triple helix structure. However, collagen faces challenges such as denaturation at high temperatures and aggregation at neutral pH, limiting its use as a bioink. Herein, we present for the first time the development of a low-temperature DLP 3D printing technique using low-concentration Collagen Methacryloyl (ColMA) for fabricating durable and bioactive personalized scaffolds. Our study shows that pH significantly influences ColMA printing, with pH 3 producing low-concentration scaffolds that exhibit enhanced mechanical properties, minimal swelling, and prolonged resistance to enzymatic hydrolysis compared to high-concentration GelMA scaffolds, while low-concentration GelMA cannot be printed independently. ColMA scaffolds notably boost the proliferation, adhesion, migration, and differentiation of human foreskin fibroblasts. In vivo rat model tests demonstrate that ColMA scaffolds reduce inflammation, enhance collagen deposition, and accelerate epidermal regeneration. This method offers a robust solution for low-temperature DLP 3D printing of collagen ink, facilitating the creation of personalized scaffolds with superior bioactivity and representing a significant advancement in tissue engineering applications.