pH-Responsive Nanogel for Photothemal-Enhanced Chemodynamic Antibacterial Therapy

Chemodynamic therapy (CDT) and photothermal therapy (PTT) have been widely studied as treatment alternatives to anbiotics to avoid the occurrence of bacterial resistance because of their negligible bacterial resistance and high antibacterial efficiencies. Herein, we developed an infection microenviron-ment-responsive nanogel (STF) to successfully achieve a PTT synergized CDT for bacterial infection. Through a one-step/pot method, STF nanotherapeutics consisting of Fe3+/sodium alginate (SA) based nanogels and Fe3+/tannic acid (TA) based metal- phenolic networks (MPNs) were conveniently prepared by the coordination-triggered simultaneous self-assembly of SA, TA, and Fe3+ ions. Afterward, their photothermal and catalytic performances were intensively investigated. Moreover, the sterilization effect of the STF nanogel was evaluated through in vitro and in vivo bactericidal assays. The STF nanogel exhibited a photothermal enhanced peroxidase-like activity because of the good photothermal effect of MPNs. In addition, its Fenton activity was further accelerated by an extra amount of Fe2+ derived from the degradation of Fe3+-chelating agents (SA) and reduction of TA. Together, the STF nanogel possessed a photothermal/Fe2+ dual-augmented catalytic property. In vitro and in vivo antibacterial assays proved its satisfactory bactericidal efficiency owing to PTT/Fe2+ dual-enhanced CDT. Our research findings suggested that the developed intelligent bactericidal nanogel has great potential to be used as an antibiotic alternative to avoid bacterial resistance in future clinical treatments.