High-strength mechanically gradient hydrogels via physical crosslinking for tendon-mimetic tissue repair

The biomimetic materials that replicate the mechanical gradient transitions from muscle to tendon to bone remain a significant challenge in tissue engineering, particularly through simple and environmentally friendly approaches. This mechanical gradient is crucial for applications such as rotator cuff and Achilles tendon repair patches, which prevent stress shielding and ensure uniform stress distribution, addressing the stress concentration issues common in traditional repairs. Here, we present a strategy that achieves high strength even at high water content, enabling programmable modulus/structural gradients with broad applicability. Using rotator cuff tendon repair as a model system, we demonstrate successful in vivo tissue regeneration with integrated real-time sensing capabilities, providing quantitative data for rehabilitation protocols. The hydrogels exhibit precisely controlled regional mechanical properties and seamless interface transitions, mimicking the hierarchical structure of native tissue. This approach not only improves healing outcomes compared to conventional methods but also establishes a quantitative standard for rehabilitation training.