Iron decoration in binary graphene oxide and copper iron sulfide nanocomposites boosting catalytic antibacterial activity in acidic microenvironment against antimicrobial resistance.

The strong antimicrobial resistance (AMR) of multidrug-resistant (MDR) bacteria and biofilm, especially the biofilm with extracellular polymeric substance (EPS) protection and persister cells, not only renders antibiotics ineffective but also causes chronic infections and makes the infectious tissue difficult to repair. Considering the acidic properties of bacterial infection microenvironment and biofilm, herein, a binary graphene oxide and copper iron sulfide nanocomposite (GO/CuFeSx NC) is synthesized by a surfactant free strategy and utilized as an alternative smart nanozyme to fight against the MDR bacteria and biofilm. For the GO/CuFeSx NC, the iron decoration facilitates the well distribution of bimetallic CuFeSx NPs on the GO surfaces compared to monometallic CuS NPs, providing synergistically enhanced peroxidase (POD)-like activity in acidic medium (pH 4 âˆ¼ 5) and intrinsic strong near infrared (NIR) light responsive photothermal activity, while the ultrathin and sharp structure of 2D GO nanosheet allows the GO/CuFeSx NC to strongly interact with the bacteria and biofilm, facilitating the catalytic and photothermal attacks on the bacterial surfaces. In addition, the GO in GO/CuFeSx NC exhibits a "Pseudo-Photo-Fenton" effect to promote the ROS generation. Therefore, the GO/CuFeSx NC can effectively kill bacteria and biofilm both in vitro and in vivo, finally eliminating the infections and accelerating the tissue repair when treating the biofilm-infected wound. This work paves a new way to the design of novel nanozyme for smart antibacterial therapy against antimicrobial resistance.

Amyloid-like nanofibrous network confined and aligned ultrafine bimetallic nanozymes for smart antibacterial therapy.

Nanozyme-based antibacterial therapy (NABT) has emerged as a promising strategy to combat bacterial antimicrobial resistance. Engineering the noble metal nanozymes with strong bacterial capture and high catalytic activity for enhanced NABT is highly anticipated but still challenged. Herein, we developed hybrid nanozymes by engineering ultrafine bimetallic Au/Cu nanoparticles confined on the lysozyme amyloid-like nanofibrous networks (LNF). The introduction of copper in the nanozymes facilitates the H2O2 adsorption and reduces the energy barrier for activating the H2O2 decomposition to form •OH, meanwhile displaying the significantly enhanced POD-like activity under NIR irradiation. Taking advantage of the inherent supramolecular networks inspired from human defensin 6-trapping bacteria mechanism, the hybrid nanozymes effectively capture the bacteria and allow the catalytic attack around the bacterial surfaces to improve the antibacterial efficiency. Finally, the as-prepared nanozymes exhibit the preeminent bactericidal efficacy against bacteria, especially for drug-resistant bacteria both in vitro and in vivo, and the effect on wound healing.

Alternative Copper-Based Single-Atom Nanozyme with Superior Multienzyme Activities and NIR-II Responsiveness to Fight against Deep Tissue Infections.

Nanozymes are considered to represent a new era of antibacterial agents, while their antibacterial efficiency is limited by the increasing tissue depth of infection. To address this issue, here, we report a copper and silk fibroin (Cu-SF) complex strategy to synthesize alternative copper single-atom nanozymes (SAzymes) with atomically dispersed copper sites anchored on ultrathin 2D porous N-doped carbon nanosheets (CuN x -CNS) and tunable N coordination numbers in the CuN x sites (x = 2 or 4). The CuN x -CNS SAzymes inherently possess triple peroxidase (POD)-, catalase (CAT)-, and oxidase (OXD)-like activities, facilitating the conversion of H2O2 and O2 into reactive oxygen species (ROS) through parallel POD- and OXD-like or cascaded CAT- and OXD-like reactions. Compared to CuN2-CNS, tailoring the N coordination number from 2 to 4 endows the SAzyme (CuN4-CNS) with higher multienzyme activities due to its superior electron structure and lower energy barrier. Meanwhile, CuN x -CNS display strong absorption in the second near-infrared (NIR-II) biowindow with deeper tissue penetration, offering NIR-II-responsive enhanced ROS generation and photothermal treatment in deep tissues. The in vitro and in vivo results demonstrate that the optimal CuN4-CNS can effectively inhibit multidrug-resistant bacteria and eliminate stubborn biofilms, thus exhibiting high therapeutic efficacy in both superficial skin wound and deep implant-related biofilm infections.