A NIR-II light-modulated injectable self-healing hydrogel for synergistic photothermal/chemodynamic/chemo-therapy of melanoma and wound healing promotion

The development of an injectable multifunctional hydrogel with tumor therapy, antibacterial treatment and wound healing properties is essential for simultaneously eradicating melanoma and promoting wound healing of tumor-initiated skin defects. Herein, iron ion-doped polyaniline (PANI(Fe)) tethered with guar gum (GG) chains is employed for the first time as a building unit for constructing a superior hydrogel (GG@PANI(Fe)-borax) crosslinked by borate/didiol bonds. Due to the dynamic and reversible properties of boronate ester bonds, the GG@PANI(Fe)-borax hydrogels had convenient injectability, rapid self-healing ability, and reversible gel-sol transformations under thermal- or pH-stimuli. More importantly, they took advantage of the second near-infrared (NIR-II) responsive photothermal conversion capability, accompanied by the photothermal-enhanced high cytotoxic (OH)-O-center dot generation in the H2O2-enriched tumor microenvironment induced by iron-doped PANI. The as-prepared hydrogels exhibited excellent photothermal effects and controllable NIR-triggered drug release, leading to distinctly synergistic photothermal/chemodynamic/chemo-therapy effects of melanoma both in vitro (98.2%) and in vivo (98.8%). In addition, the obtained hydrogels also exhibited good anti-bacterial activity (> 97.1%) against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria because they were based on PANI(Fe) and borax, which exhibit antibacterial activity. Furthermore, these GG@PANI(Fe)-incorporated scaffolds could improve fibroblast cell proliferation and angiogenesis for accelerating wound repair in tumor-bearing and infected wound mice. Taken together, GG@PANI(Fe)-borax hydrogels may be used simultaneously for eradication of skin-tumor cells, inhibiting infection and accelerating wound healing. This work offers an effective and facile strategy to fabricate an "all-in-one'' multifunctional hydrogel platform for synergetic multimodal integrated therapy of tumors.