Biomineral-inspired TiO₂-loaded collagen nanofibrous hydrogels with enhanced mechanical robustness and environmental...

Collagen nanofibrous hydrogels have attracted considerable attention in tissue engineering due to their exceptional biological functionality. One conventional strategy to enhance the properties of collagen hydrogel is incorporating nanomaterials; however, their practical utility is still constrained by weak interfacial bonding. Drawing inspiration from the composition, structure, and mechanical strength of biominerals, we developed an innovative strategy for fabricating collagen nanofibrous hydrogels with superior mechanical robustness, environmental stability, and biocompatibility by loading TiO₂ onto the surface and within the interstices of collagen nanofibrils. The mature collagen nanofibrils were wrapped by TiO₂ nanoparticles with a uniform titanium distribution in TiO₂-loaded collagen hydrogels. Strong interfacial interactions - including hydrogen bonds between TiO₂ and collagen, as well as coordination bonds between the carboxyl/amino groups of collagen and Ti(IV) - were the key contributors to the remarkable improvements in the mechanical properties of the hydrogels. The storage modulus, rupture strength and resilience of TiO₂-loaded collagen nanofibrous hydrogels increased from 1.8 kPa, 0.22 MPa and 0.091 to 1616.4 kPa, 1.89 MPa and 0.380, respectively, highlighting a broad tunability. Furthermore, the environmental stability and adaptability of TiO₂-loaded collagen nanofibrous hydrogels achieved substantial improvements, as evidenced by elevated thermal denaturation temperatures and enzymatic resistance, antibacterial activity and reduced swelling ratios relative to pure collagen hydrogels. Importantly, the resultant hydrogels maintained excellent cell proliferation promotion. This work provided a simple yet effective strategy for strengthening collagen-nanomaterial interfacial interactions and fabricating collagen-based hydrogels with desirable properties.