GSH-depleting and H2O2-self-supplying hybrid nanozymes for intensive catalytic antibacterial therapy by photothermal-augmented co-catalysis.

Nanozyme-based chemodynamic therapy (CDT) has shown tremendous potential in the treatment of bacterial infections. However, the CDT antibacterial efficacy is severely limited by the catalytic activity of nanozymes or the infection microenvironments such as insufficient hydrogen peroxide (H2O2) and overexpressed glutathione (GSH). Herein, a versatile hybrid nanozyme (MoS2/CuO2) is rationally constructed by simply decorating ultrasmall CuO2 nanodots onto lamellar MoS2 platelets of hydrangea-like MoS2 nanocarrier via a covalent Cu-S bond. The MoS2/CuO2 nanozyme exhibits the peroxidase-mimic activity for catalytically converting H2O2 produced by acid-triggered decomposition of the decorated CuO2 into hydroxyl radical (•OH). Meanwhile, the MoS2/CuO2 can consume GSH overexpressed in the infection sites via redox reaction mediated by polyvalent transition metal ions (Cu2+ and Mo6+) for enhanced CDT. More importantly, MoS2 support can promote the conversion of Cu2+ to Cu+ by a co-catalytic reaction based on the Mo4+/Mo6+ redox couples, and provide photonic hyperthermia (PTT) to augment the peroxidase-mimic activity. The developed MoS2/CuO2 nanozymes possesses a desirable catalytic property, as well as a remarkably improved antibacterial efficiency both in vitro and in vivo. Taken together, this study proposes a synergetic multiple enhancement strategy to successfully construct the versatile hybrid nanozymes for intensive in vivo PTT/CDT dual-mode anti-infective therapy. STATEMENT OF SIGNIFICANCE: Chemodynamic therapy (CDT) has shown great potentialities in the treatment of bacterial infections, while its therapeutic efficiency is severely limited by the infection microenvironments such as insufficient hydrogen peroxide (H2O2) and overexpressed glutathione (GSH). Here, we rationally construct a hybrid nanozyme (MoS2/CuO2) with peroxidase-like activity that can enhance CDT by regulating local microenvironments, that is, simultaneously self-supplying H2O2 and consuming GSH. Importantly, MoS2 support can promote the conversion of Cu2+ to Cu+ by the Mo4+/Mo6+ redox couples, and provide photonic hyperthermia (PTT) to augment the peroxidase-mimic activity. The developed MoS2/CuO2 shows desirable PTT/CDT dual-mode antibacterial efficacy both in vitro and in vivo. This study proposes a versatile hybrid nanozyme with multiple enhancement effects for intensive in vivo anti-infective therapy.

A biofilm microenvironment-responsive one-for-all bactericidal nanoplatform for photothermal-augmented multimodal synergistic therapy of pathogenic bacterial biofilm infection.

Multimodal synergistic bactericidal agents display great potential for fighting biofilm infections. However, the rational design of biofilm microenvironment (BME)-activatable therapeutic agents with excellent specificities, effective eradications and minimal side effects remains a great challenge. Herein, we show a BME-responsive one-for-all bactericidal nanoplatform consisting of Fe3+-doped polydopamine (Fe/PDA)-capped ZnO nanoparticles with a successive assembly of methylene blue (MB) and poly(ethylene glycol) (PEG). In an acidic BME (pH 5.5), the constructed nanoagent (ZnPMp) can realize the co-delivery of dual metal ions (Zn2+ and Fe3+) and MB, and the latter shows an activated photodynamic antibacterial activity when irradiated with 635 nm laser. Zn2+ produced from acid-sensitive dissolution of ZnO is an effective chemical antibacterial agent. Additionally, the released Fe3+ is reduced to Fe2+ by glutathione (GSH) overexpressed in the BME to generate Fe2+/Fe3+ redox couples, which exhibit Fenton catalytic activity to convert endogenous H2O2 to hydroxyl radicals (˙OH) for chemodynamic sterilization and GSH depletion ability to improve ˙OH-induced oxidative damage. Interestingly, the hyperthermia caused by the Fe/PDA layer assisted with 808 nm laser can damage directly bacterial cells, accelerate the release of Zn2+, Fe3+and MB, and promote the catalytic activity of Fe2+/Fe3+ redox couples for photothermal-augmented multimodal antibiofilm therapy. With the help of dual lasers, ZnPMp displays the broad-spectrum antibacterial effect, inhibits effectively the formation of biofilms, and more importantly eliminates bacteria deep in mature biofilms. In addition, ZnPMp can be used to treat biofilm-related infections in vivo with excellent therapeutic performance and minimal toxicity. Overall, the developed ZnPMp may serve as a potential nano-antibacterial agent for intensive anti-infective therapy.

Rapid In Situ Deposition of Iron-Chelated Polydopamine Coating on the Polyacrylamide Hydrogel Dressings for Combined Photothermal and Chemodynamic Therapy of Skin Wound Infection.

Pathogenic bacterial infections of skin wounds have caused a significant threat to clinical treatment and human life safety. Here, we develop a bactericidal hydrogel dressing consisting of a polyacrylamide (PAM) hydrogel framework with in situ surface-deposition of iron-dopped polydopamine (FePDA). The prepared hydrogel dressing (FePDA-PAM) has a compact surface, good tensile strength, and excellent elastic recovery ability. The introduction of Fe3+ ions improve the photothermal therapy (PTT) efficiency of the PDA and endow the hydrogel dressing with chemodynamic therapy (CDT) properties. In vitro experiments show that the antibacterial effect of FePDA-PAM hydrogel on Staphylococcus aureus reach nearly 100% under the combined action of H2O2 and 808 nm near-infrared (NIR) laser, indicating an excellent combined antibacterial property of PTT and CDT. Furthermore, the FePDA-PAM + H2O2 + NIR treatment group in the in vivo antibacterial experiments displays lowest relative wound area and optimal wound healing within 5 days of treatment, thereby indicating the intensive skin wound disinfection. To summarize, the FePDA-PAM hydrogel has simple preparation and good biosafety. It may serve as a potential wound dressing for the combined PTT/CDT dual-mode antibacterial therapy.