Application of f-FeNC@GOx cascade enzyme nanomaterials in the healing of infected wounds

Achievements and challenges in glucose oxidase-instructed multimodal synergistic antibacterial applications

Glucose oxidase (GOx) with unique catalytic properties and inherent biocompatibility can effectively oxidize both endogenous and exogenous glucose with oxygen (O2) into gluconic acid and hydrogen peroxide (H2O2). Accordingly, the GOx-based catalytic chemistry offers new possibilities for designing and constructing multimodal synergistic antibacterial systems. The consumption of glucose permanently downregulates bacterial cell metabolism by blocking essential energy supplies, inhibiting their growth and survival. Additionally, the production of gluconic acid could downregulates the pH within the bacterial infection microenvironment, enhancing the production of hydroxyl radicals (∙OH) from H2O2 via enhanced Fenton or Fendon-like reactions and triggering the pH-responsive release of drugs. Furthermore, the generated H2O2 in situ avoids the addition of exogenous hydrogen peroxide. Therefore, it is possible to design GOx-based multimodal antibacterial synergistic therapies by combining GOx-instructed cascade reactions with other therapeutic approaches such as chemodynamic therapies (CDT), hypoxia-activated prodrugs, photosensitizers, and stimuli-responsive drug release. Such multimodal strategies are expected to exhibit better therapeutic effects than single therapeutic modes. This tutorial review highlights recent advancements in GOx-instructed multimodal synergistic antibacterial systems, focusing on design philosophy and construction strategies. Current challenges and future prospects for advancing GOx-based multimodal antibacterial synergistic therapies are discussed.

Silver functionalized chitosan composite hydrogel with sustained silver release and enhanced antibacterial properties promotes healing of infected wounds

Bacterial infections during wound healing often cause inflammation, which delays the healing process. Therefore, innovative wound dressings are urgently needed to inhibit bacterial infections and promote healing. This study proposes an Ag-functionalized chitosan hydrogel dressing, formed via a Schiff-base reaction between alkynyl Ag substituted chitosan (Ag-CS) and octafunctionalized polyhedral oligomeric silsesquioxane with benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO), to address the issue of bacterial infection in wounds. The hydrogel demonstrated excellent injectability and self-healing properties. AgNPs and alkynyl Ag, produced by the reducing effect of chitosan and the reversible reaction of alkynyl Ag, delay the release of Ag+. Furthermore, the hydrogel exhibits a broad-spectrum antibacterial effect and effectively inhibits bacterial biofilm formation. The release of Ag+ lasts for 7 days, ensuring sustainable antibacterial properties. In a mouse infected wound model, the composite hydrogel significantly accelerated wound healing. By the eighth day, the wound healing rate reached 99 %, whereas the control group achieved only 91 %. Histological and immunofluorescence staining results indicated that hydrogel-treated wounds had faster re-epithelialization, collagen deposition, and angiogenesis, with reduced inflammation. In conclusion, the Ag-functionalized chitosan hydrogel, with sustained Ag release and enhanced antibacterial properties, shows great potential as a wound dressing for promoting the healing of infected wounds.

Multifunctional SEBS/AgNWs Nanocomposite Films with Antimicrobial, Antioxidant, and Anti-Inflammatory Properties Promote Infected Wound Healing

Wound healing is a complex biological process that can trigger inflammation and oxidative stress and impair myofibrillogenesis and angiogenesis. Several advanced wound-dressing nanocomposite materials have been designed to address these issues. Here, we designed a new multifunctional styrene-ethylene-butylene-styrene/silver nanowire (SEBS/AgNWs)-based nanocomposite film with antimicrobial, antioxidant, and anti-inflammatory properties to promote wound healing. The porous morphological structure of SEBS/AgNWs enhances their antimicrobial, antioxidant, and anti-inflammatory properties. SEBS/AgNWs significantly inhibited the growth of Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Escherichia coli strains, effectively wiping out ABTS•+, DPPH•, hydrogen peroxide (H2O2), and hydroxyl (•OH) radicals, showing their effective ROS-scavenging properties. It further showed significant antioxidant properties by increasing the levels of enzyme-like catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH), while decreasing malonaldehyde (MDA) levels. Additionally, SEBS/AgNWs reduced the expression of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), while increasing levels of transforming growth factor- β (TGF-β), vascular endothelial growth factor-A (VEGF), and CD31 in wound healing. This suggests that applying a multifunctional nanoplatform based on SEBS/AgNWs could enhance wound healing and improve patient outcomes in wound care management.

Multifunctional nanocomposites mediated novel hydrogel for diabetic wound repair

The regeneration and repair of diabetic wounds, especially those including bacterial infection, have always been difficult and challenging using current treatment. Herein, an effective strategy is reported for constructing glucose-responsive functional hydrogels using nanocomposites as nodes. In fact, tannic acid (TA)-modified ceria nanocomposites (CNPs) and a zinc metal-organic framework (ZIF-8) were employed as nodes. Subsequent crosslinking with 3-acrylamidophenylboronic acid achieved functional nanocomposite-hydrogels (TA@CN gel, TA@ZMG gel) by radical-mediated polymerization. Compared with a simple physically mixed hydrogel system, the mechanical properties of TA@CN gel and TA@ZMG gel are significantly enhanced due to the intervention of the nanocomposite nodes. In addition, this kind of nanocomposite hydrogel can realize the programmed loading of drugs and release of drugs in response to glucose/PH, to coordinate and promote its application in the regeneration and repair of diabetic wounds and infected diabetic wounds. Specifically, TA@CN gel can remove reactive oxygen species and generate oxygen through its various enzymatic activities. At the same time, it can effectively promote neovascularization, thus promoting the regeneration and repair of diabetic wounds. Furthermore, glucose oxidase-loaded TA@ZMG gel exhibits glucose response and pH-regulating functions, triggering programmed metformin (Met) release by degrading the metal-organic framework (MOF) backbone. It also exhibited additional synergistic effects of antibacterial activity, hair regeneration and systemic blood glucose regulation, which make it suitable for the repair of more complex infected diabetic wounds. Overall, this novel nanocomposite-mediated hydrogel holds great potential as a biomaterial for the healing of chronic diabetic wounds, opening up new avenues for further biomedical applications.

Advanced nanozymes possess peroxidase-like catalytic activities in biomedical and antibacterial fields: review and progress

Infectious diseases caused by bacterial invasions have imposed a significant global health and economic burden. More worryingly, multidrug-resistant (MDR) pathogenic bacteria born under the abuse of antibiotics have further escalated the status quo. Nowadays, at the crossroads of multiple disciplines such as chemistry, nanoscience and biomedicine, nanozymes, as enzyme-mimicking nanomaterials, not only possess excellent bactericidal ability but also reduce the possibility of inducing resistance. Thus, nanozymes are promising to serve as an alternative to traditional antibiotics. Nanozymes that mimic peroxidase (POD) activity are also known as POD nanozymes. In recent years, POD nanozymes have become one of the most frequently reported and effective nanozymes due to their broad-spectrum bactericidal properties and unique sterilization mechanism. In this review, we introduce the mechanism as well as the classification of POD nanozymes. More importantly, to further improve the antibacterial efficacy of POD nanozymes, we elaborate on three aspects: (1) improving the physicochemical properties; (2) regulating the catalytic microenvironment; and (3) designing multimodel POD nanozymes. In addition, we review the nanosafety of POD nanozymes for discussing their potential toxicity. Finally, the remaining challenges of POD nanozymes and possible future directions are discussed. This work provides a systematic summary of POD nanozymes and hopefully contributes to the early clinical translation.