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

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.