pH Switchable Nanozyme Platform for Healing Skin Tumor Wound Infected with Drug-Resistant Bacteria

AI-Guided Design of Antimicrobial Peptide Hydrogels for Precise Treatment of Drug-resistant Bacterial Infections

Traditional biomaterial development lacks systematicity and predictability, posing significant challenges in addressing the intricate engineering issues related to infections with drug-resistant bacteria. The unprecedented ability of artificial intelligence (AI) to manage complex systems offers a novel paradigm for materials development. However, no AI model currently guides the development of antibacterial biomaterials based on an in-depth understanding of the interplay between biomaterials and bacteria. In this study, an AI-guided design platform (AMP-hydrogel-Designer) is developed to generate antibacterial biomaterials. This platform utilizes generative design and multi-objective constrained optimization to generate a novel thiol-containing high-efficiency antimicrobial peptide (AMP), that is functionally coupled with hydrogel to form a complex network structure. Additionally, Cu-modified barium titanate (Cu-BTO) is incorporated to facilitate further complex cross-linking via Cu2+/SH coordination to produce an AI-AMP-hydrogel. In vitro, the AI-AMP-hydrogel exhibits > 99.99% bactericidal efficacy against Methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). Furthermore, Cu-BTO converts mechanical stimulation into electrical signals, thereby promoting the expression of growth factors and angiogenesis. In a rat model with dynamic wounds, the AI-AMP hydrogel significantly reduces the MRSA load and markedly accelerates wound healing. Therefore, the AI-guided biomaterial development strategy offers an innovative solution to precisely treat drug-resistant bacterial infections.

Research Progress on Antibacterial Applications of Bioactive Materials in Wound Infections: Design, Challenges, and Prospects

Bacterial wound infections pose a significant threat to global health, exacerbated by the increase in multidrug-resistant bacteria (MDRB) and the formation of elastic biofilms. This review explores the transformative potential of bioactive materials in addressing these challenges, focusing on their design, mechanisms of action, and therapeutic effects. In vivo, bioactive materials are designed to respond to unique bacterial microenvironment (BME), utilizing enzyme activity, controlled gas release, surface functionalization, and immune regulation to combat infections. In vitro, this review provides a comprehensive overview of the latest advances in the rational design of these materials, emphasizing the synergistic integration of structural modifications (such as size and morphology) with external physical stimuli (such as light, sound, electricity, magnetism, and force) to enhance antibacterial performance. Finally, the outstanding challenges and prospects in this rapidly evolving field are discussed.

Recent advances in nanomaterials and their mechanisms for infected wounds management

Wounds infected by bacteria pose a considerable challenge in the field of healthcare, particularly with the increasing prevalence of antibiotic-resistant pathogens. Traditional antibiotics often fail to achieve effective results due to limited penetration, resistance development, and inadequate local concentration at wound sites. These limitations necessitate the exploration of alternative strategies that can overcome the drawbacks of conventional therapies. Nanomaterials have emerged as a promising solution for tackling bacterial infections and facilitating wound healing, thanks to their distinct physicochemical characteristics and multifunctional capabilities. This review highlights the latest developments in nanomaterials that demonstrated enhanced antibacterial efficacy and improved wound healing outcomes. The antibacterial mechanisms of nanomaterials are varied, including ion release, chemodynamic therapy, photothermal/photodynamic therapy, electrostatic interactions, and delivery of antibacterial drugs, which not only combat bacterial infections but also address the challenges posed by biofilms and antibiotic resistance. Furthermore, these nanomaterials create an optimal environment for tissue regeneration, promoting faster wound closure. By leveraging the unique attributes of nanomaterials, there is a significant opportunity to revolutionize the management of infected wounds and markedly improve patient outcomes.

Photodynamic therapy combined with quaternized chitosan antibacterial strategy for instant and prolonged bacterial infection treatment

Drug-resistant bacterial infections represent a critical global public health challenge, driven largely by the misuse and overuse of antibiotics. Tackling the growing threat of bacterial resistance necessitates the development of innovative antibacterial agents that function independently of traditional antibiotics. In this study, novel antibacterial nano-micelles were rationally designed by conjugating quaternized chitosan with the photosensitizer chlorin e6. These nano-micelles promoted the solubility and stability of chlorin e6 while maintaining robust singlet oxygen generation under 660 nm laser irradiation. The positively charged nano-micelles facilitated strong electrostatic interactions with bacterial surfaces, promoting efficient adhesion and enabling effective photodynamic antibacterial activity mediated by singlet oxygen. In vitro experiments revealed that the nano-micelles exhibited instant and prolonged antibacterial effects, effectively suppressing bacterial proliferation without inducing resistance and disrupting mature biofilms. Furthermore, in conjunction with laser treatment, nano-micelles exhibited remarkable in vivo antibacterial efficacy, significantly accelerating the healing of skin wounds infected with Methicillin-resistant Staphylococcus aureus while maintaining favorable biocompatibility. These findings highlight the potential of the nano-micelles as a promising non-antibiotic antibacterial formulation, offering a powerful strategy to combat drug-resistant bacterial infections and paving the way for their clinical application in infection management.

Recent Development of Nanozymes for Combating Bacterial Drug Resistance: A Review

The World Health Organization has warned that without effective action, deaths from drug-resistant bacteria can exceed 10 million annually, making it the leading cause of death. Conventional antibiotics are becoming less effective due to rapid bacterial drug resistance and slowed new antibiotic development, necessitating new strategies. Recently, materials with catalytic/enzymatic properties, known as nanozymes, have been developed, inspired by natural enzymes essential for bacterial eradication. Unlike recent literature reviews that broadly cover nanozyme design and biomedical applications, this review focuses on the latest advancements in nanozymes for combating bacterial drug resistance, emphasizing their design, structural characteristics, applications in combination therapy, and future prospects. This approach aims to promote nanozyme development for combating bacterial drug resistance, especially towards clinical translation.

Heterostructure Nanozyme with Hyperthermia-Amplified Enzyme-Like Activity and Controlled Silver Release for Synergistic Antibacterial Therapy

Heterostructure nanozymes as antibiotic-free antimicrobial agents exhibit great potential for multidrug-resistant (MDR) bacterial strains elimination. However, realization of heterostructure antimicrobials with enhanced interfacial interaction for synergistically amplified antibacterial therapy is still a great challenge. Herein, oxygen-vacancy-enriched glucose modified MoOx (G-MoOx) is exploited as a reducing agent to spontaneously reduce Ag (I) into Ag (0) that in situ grows onto the surface of G-MoOx. The resultant Ag doped G-MoOx (Ag/G-MoOx) heterostructure displays augmenting photothermal effect and NIR-enhanced oxidase-like activity after introducing Ag nanoparticles. What's more, NIR hyperthermia accelerate Ag+ ions release from Ag nanoparticles. Introduction of Ag greatly enhances antimicrobial activities of Ag/G-MoOx against MDR bacteria, especially the hybrid loading with 1 wt% Ag NPs exhibiting antibacterial efficacy up to 99.99% against Methicillin-resistant Staphylococcus aureus (MRSA, 1×106 CFU mL-1).

Tunable multi-enzyme activities of platinum nanoclusters for enhanced specificity and sensitivity in biosensing

Nanozymes have gained prominence for their utility in biosensing and disease diagnostics. However, challenges arise from complex sample matrices and nonspecific enzyme activities that contribute to false signals. This study introduces multifunctional platinum nanoclusters (Pt NCs) exhibiting peroxidase-like (POD-like), oxidase-like (OXD-like), and laccase-like activities tailored for enhanced biosensing capabilities. By adjusting pH, we optimized the conditions to achieve distinct POD-like and OXD-like responses, thereby reducing background signals and improving detection accuracy. The addition of ATP further amplified the POD-like activity while minimizing interference from OXD-like activity. This combined strategy substantially enhanced biomarker detection selectivity, demonstrated through glucose detection in human serum samples. Moreover, thiol inhibition of laccase-like activity in Pt NCs was leveraged for thiol-based antioxidant assessment, revealing their application in quantifying total antioxidant capacity (TAC) in human liver cancer cells, accounting for 44 % of TAC. The Pt NCs demonstrated robust sensitivity and reusability, offering a novel multi-enzyme nanomaterial with potential for precise and interference-free biosensing applications. These findings contribute to the development of advanced nanozyme-based biosensors, addressing specificity regulation challenges and expanding their practical application in biosensing and disease diagnostics.

Application of Drug Delivery System Based on Nanozyme Cascade Technology in Chronic Wound

Chronic wounds are characterized by long-term inflammation, including diabetic ulcers, traumatic ulcers, etc., which provide an optimal environment for bacterial proliferation. At present, antibiotics are the main clinical treatment method for chronic wound infections. However, the overuse of antibiotics may accelerate the emergence of drug-resistant bacteria, which poses a significant threat to human health. Therefore, there is an urgent need to develop new therapeutic strategies for bacterial infections. Nanozyme-based antimicrobial therapy (NABT) is an emerging antimicrobial strategy with broad-spectrum activity and low drug resistance compared to traditional antibiotics. NABT has shown great potential as an emerging antimicrobial strategy by catalyzing the generation of reactive oxygen species (ROS) with its enzyme-like catalytic properties, producing a powerful bactericidal effect without developing drug resistance. Nanozyme-based cascade antimicrobial technology offers a new approach to infection control, effectively improving antimicrobial efficacy by activating cascades against bacterial cell membranes and intracellular DNA while minimizing potential side effects. However, it is worth noting that this technology is still in the early stages of research. This article comprehensively reviews wound classification, current methods for the treatment of wound infection, different types of nanozymes, the application of nanozyme cascade reaction technology in antimicrobial therapy, and future challenges and prospects.

An acidity-triggered aggregation nanoplatform based on degradable mesoporous organosilica nanoparticles for precise drug delivery and phototherapy of focal bacterial infection

It is crucial to precisely strike the bacterially infected area and avoid damaging healthy tissue in bacterial infection treatment. Herein, we report an acidity-triggered aggregation antibacterial nanoplatform based on biodegradable mesoporous organic silica nanoparticles (MON NPs). The surface of MON NPs modified with polydopamine (PDA) encapsulated ciprofloxacin (CIP) and methylene blue (MB) and was then further grafted with glycol chitosan to obtain MB/CIP@MON-PDA-GCS NPs (MCMPG NPs). In the bacterial infection environment with acidic characteristics, glycol chitosan (GCS) becomes positively charged. Consequently, the positively charged acidity-triggered GCS enables MCMPG NPs to accumulate on the negatively charged bacterial surfaces in the infected area and not in healthy tissue. The targeted method allows for the precise release of CIP and MB, ensuring the spatial accuracy of photodynamic therapy (PDT) and photothermal therapy (PTT) for effective bacteria-specific treatment.

Advances in H2O2-supplying materials for tumor therapy: synthesis, classification, mechanisms, and applications

Hydrogen peroxide (H2O2) as a reactive oxygen species produced by cellular metabolism can be used in antitumor therapy. However, the concentration of intracellular H2O2 limits its application. Some materials could enhance the concentration of intracellular H2O2 to strengthen antitumor therapy. In this review, the recent advances in H2O2-supplying materials in terms of promoting intracellular H2O2 production and exogenous H2O2 supply are summarized. Then the mechanism of H2O2-supplying materials for tumor therapy is discussed from three aspects: reconstruction of the tumor hypoxia microenvironment, enhancement of oxidative stress, and the intrinsic anti-tumor ability of H2O2-supplying materials. In addition, the application of H2O2-supplying materials for tumor therapy is discussed. Finally, the future of H2O2-supplying materials is presented. This review aims to provide a novel idea for the application of H2O2-supplying materials in tumor therapy.

Copper peroxide loaded gelatin/oxide dextran hydrogel with temperature and pH responsiveness for antibacterial and wound healing activity

Bacterial infection and tissue hypoxia always prevent wound healing, so multifunctional platforms with antimicrobial and oxygen-supplying functions were developed. However, they face many difficulties such as complex preparation and low oxygen release. To address this challenge, a copper peroxide loaded gelatin/oxide dextran hydrogel (CGO) was prepared. Surprisingly, CGO hydrogel as a wound dressing not only had good biocompatibility, injectivity, and mechanical properties, but also exhibited mild photothermal properties, temperature responsiveness, and pH responsiveness. After being applied to wounds infected with bacteria, CGO hydrogel released copper peroxide under near-infrared laser irradiation, which produced copper ions and hydrogen peroxide, combined with PTT to kill bacteria. After the bacteria were cleared from the wound and the pH of the wound was changed to be acidic, CGO hydrogel released copper peroxide via pH response. Copper ions and oxygen produced from copper peroxide accelerated wound healing by promoting angiogenesis. The multi-responsive and multi-mode treatment platform provided a potential strategy for treating bacteria-infected wounds.

Thermal-Responsive Antibacterial Hydrogel with Photothermal Therapy and Improving Wound Microenvironment for Promote Healing

Skin damage is one of the most prevalent human injuries, which affects the health of human beings. However, skin damage is often accompanied by bacterial infection and wound microenvironment changes, causing damage to normal cells and inhibiting wound healing. Herein, we designed a thermal-responsive antibacterial hydrogel (GAG hydrogel) loaded with catalase (CAT)-like Au@Pt@MgSiO3 nanoparticles (APM NPs) and gentamicin (GM) to promote wound healing. The GAG hydrogel was used in a photothermal therapy (PTT)/antibiotic combination to kill bacteria, reduce the use of antibiotics, improve the wound microenvironment, promote cell proliferation, and accelerate wound healing. Under near-infrared laser irradiation, APM NPs in the hydrogel generated local hyperthermia to kill bacteria. Meanwhile, the generated heat led to a change in the hydrogel's morphology, enabling it to release GM and APM NPs to prevent the overuse of antibiotics. Subsequently, the CAT-like ability of the APM NPs decreased the oxidative stress caused by hydrogen peroxide (H2O2), thus remodeling the wound microenvironment. Then, the weakly acidic microenvironment of the wound caused the decomposition of the APM NPs and the release of magnesium ions (Mg2+), promoting the growth and migration of cells for wound healing. Therefore, the studied thermal-responsive antibacterial (GAG) hydrogel has potential in the field of wound healing.

H2O2/acid self-supplying double-layer electrospun nanofibers based on ZnO2 and Fe3O4 nanoparticles for efficient catalytic therapy of wound infection

Catalytic therapy based on nanozymes is promising for the treatment of bacterial infections. However, its therapeutic efficacy is usually restricted by the limited amount of hydrogen peroxide and the weak acidic environment in infected tissues. To solve these issues, we prepared polyvinyl alcohol (PVA)-polyacrylic acid (PAA)-iron oxide (Fe3O4)/polyvinyl alcohol (PVA)-zinc peroxide (ZnO2) double-layer electrospun nanofibers (PPF/PZ NFs). In this design, PVA serves as the carrier for ZnO2 nanoparticles (NPs), Fe3O4 NPs, and PAA. The double-layer structure of nanofibers can spatially separate the PAA and ZnO2 to avoid their reaction with each other during preparation and storage, while in the wet wound bed, PVA can dissolve and PAA can provide H+ ions to promote the generation of hydrogen peroxide and subsequent conversion to hydroxyl radicals for bacteria killing. In vitro experimental results demonstrated that PPF/PZ NFs can reduce the methicillin-resistant Staphylococcus aureus by 3.1 log (99.92%). Moreover, PPF/PZ NFs can efficiently treat the bacterial infection in a mouse wound model and promote wound healing with negligible toxicity to animals, indicating their potential use as "plug-and-play" antibacterial wound dressings. This work provides a novel strategy for the construction of double-layer electrospun nanofibers as catalytic wound dressings with hydrogen peroxide/acid self-supplying properties for the efficient treatment of bacterial infections.

Dual pH- and ATP-Responsive Antibacterial Nanospray: On-Demand Release of Antibacterial Factors, Imaging Monitoring, and Accelerated Healing of Bacteria-Infected Wounds under NIR Activation

The prevalence of pathogenic bacterial infections with high morbidity and mortality poses a widespread challenge to the healthcare system. Therefore, it is imperative to develop nanoformulations capable of adaptively releasing antimicrobial factors and demonstrating multimodal synergistic antimicrobial activity. Herein, an NIR-activated multifunctional synergistic antimicrobial nanospray MXene/ZIF-90@ICG was prepared by incorporating ZIF-90@ICG nanoparticles onto MXene-NH2 nanosheets. MXene/ZIF-90@ICG can on-demand release the antimicrobial factors MXenes, ICG, and Zn2+ in response to variations in pH and ATP levels within the bacterial infection microenvironment. Under NIR radiation, the combination of MXenes, Zn2+, and ICG generated a significant amount of ROS and elevated heat, thereby enhancing the antimicrobial efficacy of PDT and PTT. Meanwhile, NIR excitation could accelerate the further release of ICG and Zn2+, realizing the multimodal synergistic antibacterial effect of PDT/PTT/Zn2+. Notably, introducing MXenes improved the dispersion of the synthesized antimicrobial nanoparticles in aqueous solution, rendering MXene/ZIF-90@ICG a candidate for application as a nanospray. Importantly, MXene/ZIF-90@ICG demonstrated antimicrobial activity and accelerated wound healing in the constructed in vivo subcutaneous Staphylococcus aureus infection model with NIR activation, maintaining a favorable biosafety level. Therefore, MXene/ZIF-90@ICG holds promise as an innovative nanospray for adaptive multimodal synergistic and efficient antibacterial applications with NIR activation.

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.