Balancing Hydration and Mechanical Stability in One-Step Photocured GelMA/Poly(acrylic acid- co -hydroxyethyl acrylate) Composite Hydrogels

Abstract To address the challenge of balancing high-water content with structural stability in hydrogels, gelatin methacryloyl (GelMA) was introduced into a poly(acrylic acid-co-hydroxyethyl acrylate) system. GelMA/PAH composite hydrogels (Gel-PAH) were then prepared through one-step ultraviolet (UV) photocuring, and their network formation and overall properties were tuned by varying the glycerol dimethacrylate (GDMA) content. The Gel-PAH hydrogels exhibited higher hydration capacity and greater surface wettability than the corresponding PAH hydrogels. As the GDMA content increased, the gel fraction and tensile strength of both the PAH and Gel-PAH series generally increased. The tensile strength of the Gel-PAH hydrogels ranged from approximately 1.6 to 2.5 MPa. Gel-PAH-0.15 exhibited an equilibrium water content of 82.55%, a water contact angle of approximately 39°, and a relative cellular metabolic activity of approximately 84% after 24 h. Overall, Gel-PAH-0.15 achieved a favorable balance among network stability, hydration capacity, mechanical performance, and preliminary direct contact cytocompatibility. These results show that a compositionally simple AA/HEA-GelMA system provides a straightforward route to tune hydration and mechanical performance through one-step UV photocuring and adjustment of GDMA content, without introducing additional reinforcing fillers or sequential cross-linking processes.