Negative Swelling and Mechanical Self‐Enhancement TAFe@PVA Photothermal Hydrogel Mediated Via Semi‐Crystallization for Medical Implants

Abstract Medical implants, important consumables, significantly promote patients’ healthcare, but still face challenges of foreign body responses and bacterial infection. Hydrogels can be ideal alternative materials, however, a few of them can meet the requirements. Herein, a TAFe@PVA photothermal hydrogel integrating with negative swelling, long‐term stability, antibacterial, anti‐adhesion, and tissue mechanical matching is developed to solve these issues. The TAFe@PVA hydrogel is crosslinked by H‐bonds and microcrystal domains which both can be enhanced by cations or anions based on Hofmeister effect, showing unique negative swelling and long‐term mechanical self‐enhancement performances in the physiological fluid. Attributing to self‐polymerization of tannic acid (TA) and negative swelling of polyvinyl alcohol (PVA) molecular networks, TAFe complexes can be strongly locked in PVA molecular networks, reaching long‐term photothermal stability. The TAFe@PVA hydrogel also exhibits great biocompatibility, anti‐oxidation, anti‐adhesion, and anti‐bacterial performances, comparing to the traditional implant material. Since the TAFe@PVA hydrogel can better match with skin tissues, fewer macrophages and myofibroblasts are activated, which depresses unexpected foreign body responses. Finally, the TAFe@PVA hydrogel as the implant can effectively solve abdominal adhesions after abdominal operation and promote defects healing. This study introduces a promising hydrogel implant, which potentially extends hydrogels to wider medical applications.