Metal–Organic Framework/Ag-Based Hybrid Nanoagents for Rapid and Synergistic Bacterial Eradication

Photo-responsive antibacterial metal organic frameworks

The misuse and overuse of antibiotics have caused the emergence of antibiotic-resistant bacteria, making bacterial infections more challenging. The increasing prevalence of multidrug-resistant pathogens has driven researchers to explore novel therapeutic strategies. Phototherapy strategies that utilize photo-responsive biomaterials for their antibacterial properties have gained widespread attention due to their capability of precisely controlling bacterial inactivation with minimal side effects. Despite their potential, photodynamic therapies suffer from phototoxicity and low efficiency of photosensitizers, while photothermal therapy risks overheating, which may harm healthy tissues, thus restricting its broader application. Metal organic frameworks (MOFs) have unique physicochemical properties, which provide a promising way to deal with these challenges. MOFs can function as reservoirs, loading and releasing antibacterial agents, such as antibiotics or metal ions, upon light illumination by virtue of their metastable coordination bonds. Their porous structures enable controlled drug release and encapsulation of photosensitizers. Furthermore, MOFs' tunable composition and pore structure allow for the light-triggered generation of heat and reactive oxygen species, enhancing their antibacterial effectiveness. By doping MOFs with functional materials, it is possible to achieve multi-mode antibacterial effects. In this review, we will outline recent advancements of photo-responsive antibacterial MOFs, categorize their underlying mechanisms of action and highlight their prospects in addressing bacterial resistance.

Advances in photothermal therapy for cancer and bacterial cells ablation using various nanomaterials

Bacterial pathogens can cause severe infections leading to mortality and morbidity. The current method of treatment for bacteria is the use of multiple antibiotics. Due to the overuse of antibiotics, many bacteria have become antibiotic-resistant. An alternative and effective treatment for bacterial infection is needed, and photothermal therapy (PTT) has emerged as a new solution for treating bacterial infection. Similarly, one of the main challenges in cancer treatment is the overuse of drugs that have multiple side effects. In recent years, there have been significantly more research activities in alternative therapy for pathogenic bacteria and cancer cells. Recently, PTT has also been used to treat various medical conditions like cancer, bacterial infections, or bacterial biofilm. Different kinds of nanomaterials like gold nanoparticles (AuNPs), Graphene Oxide (GO), Carbon nanotubes (CNTs), etc. have been explored for this purpose. In this particular review, we will elaborate on different kinds of nanomaterials (metallic, non-metallic, polymeric) widely used for PTT applications for bacteria and cancer cells. These kinds of nanoparticles have strong absorption in the NIR region and can convert light energy into heat energy, leading to hyperthermia. Further different types of PTT will be elaborated on, along with challenges and future applications. The current review will pave a new way for the therapeutic potential of different nanomaterials for bacterial infection and cancer treatment.

Dual-responsive polydopamine-embellished Zn-MOFs enabling synergistic photothermal and antibacterial metal ion therapy for oral biofilm eradication

Oral biofilms are associated with various oral diseases causing pain and discomfort, and pose a severe threat to general health. Conventional surgical debridement and antibacterial therapy often yield unsatisfactory outcomes because they either fail to fully and painlessly eliminate biofilms or increase the risk of bacterial resistance. In this study, we synthesized polydopamine-embellished Zn-MOFs (ZIF-8@PDA NPs), which can degrade under mildly acidic conditions to release Zn2+. These nanoparticles also convert near-infrared light energy into heat, thereby enabling synergistic photothermal and antibacterial metal ion therapy for oral biofilm eradication. Our findings reveal that therapy with ZIF-8@PDA NPs, when exposed to near-infrared radiation, demonstrates exceptional antibacterial efficacy and is highly effective in eradicating oral biofilms both in vitro and ex vivo. Furthermore, we used an in vivo rodent tooth biofilm model to demonstrate the suppression of dental caries. This work presents a promising solution for preventing and suppressing dental caries as well as other treating diseases linked to oral biofilm infections.

Optimization of Metal-Based Nanoparticle Composite Formulations and Their Application in Wound Dressings

Metal-based nanoparticles (MNPs) have great potential for applications in wound healing and tissue engineering, and due to their unique structures, high bioactivities, and excellent designability characteristics, an increasing number of studies have been devoted to modifying these species to generate novel composites with desirable optical, electrical, and magnetic properties. However, few systematic and detailed reviews have been performed relating to the modification approaches available for MNPs and their resulting composites. In this review, a comprehensive summary is performed regarding the optimized modification formulations of MNPs for application in wound dressings, and the techniques used to prepare composite wound dressings are discussed. In addition, the safety profiles of the novel nanocomposite formulations and the limitations of the reported systems are evaluated. More importantly, a number of solution strategies are proposed to address these limitations. Overall, this review provides new ideas for the design of MNPs to facilitate their application in the field of skin tissue repair, and also looks into the future direction of MNPs in the biomedical field.

Versatile nanomaterials used in combatting biofilm infections

Microbial infections are a pressing global health issue, exacerbated by the rise of antibiotic-resistant bacteria due to widespread antibiotic overuse. This resistance diminishes the effectiveness of current treatments, intensifying the need for new antimicrobial agents and innovative drug delivery strategies. Nanotechnology presents promising solutions, leveraging the unique properties of nanomaterials such as tunable optical and electronic characteristics, nanoscale size, and high surface-to-volume ratios. These features enhance their effectiveness as innovative antimicrobial agents and versatile drug delivery systems. This minireview classifies antimicrobial nanomaterials into four categories based on their mechanisms of action: thermal generation, reactive oxygen species generation, gas generation, and nanocarrier systems such as liposomes, polymersomes, and metal-organic frameworks. Uniquely, this review integrates a comparative analysis of these mechanisms, highlighting their relative advantages, limitations, and applications across diverse microbial targets. Additionally, it identifies emerging trends in the field, providing a forward-looking perspective on how recent advancements in nanotechnology can be leveraged to address unmet clinical needs. Finally, this article discusses future directions and emerging opportunities in antimicrobial nanotechnology.

Exploring the multifaceted roles of metal-organic frameworks in ecosystem regulation

Achieving microecological balance is a complex environmental challenge. This is because the equilibrium of microecological systems necessitates both the eradication of harmful microorganisms and preservation of the beneficial ones. Conventional materials predominantly target the elimination of pathogenic microorganisms and often neglect the protection of advantageous microbial species. Metal-organic frameworks (MOFs) with excellent physicochemical properties (such as crystalline particles of various dimensions with highly porous network topology, variable local networking structures, diverse compositions with functional groups, high specific surface areas and pore volumes for surface and porous guest molecular adsorption/adhesion/affinity/binding and separation) have been extensively studied as a type of bactericidal material. However, only recently, studies on using MOFs to protect microorganisms have been reported. This review provides a comprehensive analysis of the mechanisms and applications of various MOFs (such as ZIF-8, ZIF-90, HKUST-1, MOF-5, and MIL-101) in both microbial eradication and protection. Insights into previous studies on MOF development, the material-bacteria interaction mechanisms, and potential clinical and environmental applications are also elucidated. MOFs with different framework structures/topologies (zeolite, sodalite, scaffolding, diamond, one-dimensional, and spherical/cylindrical cavities/pore networks), particle dimensions, polyhedral, cubic, rod and open/uncoordinated metal centers or fully coordinated metal centers, and ligand functional groups are discussed to understand the varying degrees of activation and interaction of microorganisms. This review holds potential in guiding future research on the design, synthesis, utilization, and integration of MOFs for the targeted eradication and protection of microorganisms and generating novel MOFs with selective antimicrobial and protective properties. Moreover, this review delivers a timely update and outlines future prospects for MOFs and their interaction with microorganisms, emphasizing their potential as a promising candidate among the next generation of smart materials in the field of ecosystem regulation.

Photo-responsive Cu-tannic acid nanoparticle-mediated antibacterial film for efficient preservation of strawberries

The existing films used for fruit preservation suffer from insufficient preservation abilities. This study introduces Cu-tannic acid (Cu-TA) nanoparticles, synthesized from tannic acid (TA) and Cu2+, to enhance food packaging properties. Integrated into a chitosan-gelatin (CG) matrix, the resultant Cu-TA nanocomposite films exhibit superior antibacterial efficacy and killing rates of Escherichia coli and Staphylococcus aureus more than 99 %, and double the shelf life of strawberries, underscoring the exceptional freshness preservation capabilities of film. Additionally, the tensile strength of the Cu-TA nanocomposite films increased by 1.75 times, the DPPH radical scavenging percentage increased from 29.4 % to 68.4 %, and the water vapor permeability (WVP) decreased by about 60 % compared to the pure CG films. Comprehensive cytotoxicity and migration assessments confirm the safety of film, paving the way for their application in food packaging. The excellent performance of the Cu-TA nanocomposite films positions them as a formidable solution for protecting perishable food items.

Harnessing Nanoparticles to Overcome Antimicrobial Resistance: Promises and Challenges

The rise of antimicrobial resistance (AMR) has become a serious global health issue that kills millions of people each year globally. AMR developed in bacteria is difficult to treat and poses a challenge to clinicians. Bacteria develop resistance through a variety of processes, including biofilm growth, targeted area alterations, and therapeutic drug alteration, prolonging the period they remain within cells, where antibiotics are useless at therapeutic levels. This rise in resistance is linked to increased illness and death, highlighting the urgent need for effective solutions to combat this growing challenge. Nanoparticles (NPs) offer unique solutions for fighting AMR bacteria. Being smaller in size with a high surface area, enhancing interaction with bacteria makes the NPs strong antibacterial agents against various infections. In this review, we have discussed the epidemiology and mechanism of AMR development. Furthermore, the role of nanoparticles as antibacterial agents, and their role in drug delivery has been addressed. Additionally, the potential, challenges, toxicity, and future prospects of nanoparticles as antibacterial agents against AMR pathogens have been discussed. The research work discussed in this review links with Sustainable Development Goal 3 (SDG-3), which aims to ensure disease-free lives and promote well-being for all ages.

Antimicrobial zeolites and metal-organic frameworks

The current surge in antibiotic resistance and the emergence of pandemics have created an urgent need for novel antimicrobial strategies. The controlled release of antimicrobial active principles remains the most viable strategy to date, and transition metal ions currently represent the main alternative to antibiotics. In this review, we explore the potential of two types of materials, zeolites and metal-organic frameworks (MOFs), for the controlled release of antimicrobial active principles, notably transition metal ions. These materials have unique crystalline microporous structures that act as reservoirs, enabling sustained bactericidal effects in various applications such as coatings, packaging, and medical devices. However, there are currently no convenient and standardised methods for evaluating their metal ion release and antimicrobial efficacy. This work discusses analytical techniques and the proposed mechanisms of action while highlighting recent advances in film, membrane, and coating technologies. By addressing the current limitations, microporous materials can revolutionise antimicrobial approaches, offering enhanced effectiveness and long-term sustainability.

Nano-encapsulation of drugs to target hepatic stellate cells: Toward precision treatments of liver fibrosis

Liver fibrosis is characterized by excessive extracellular matrix (ECM) deposition triggered by hepatic stellate cells (HSCs). As central players in fibrosis progression, HSCs are the most important therapeutic targets for antifibrotic therapy. However, owing to the limitations of systemic drug administration, there is still no suitable and effective clinical treatment. In recent years, nanosystems have demonstrated expansive therapeutic potential and evolved into a clinical modality. In liver fibrosis, nanosystems have undergone a paradigm shift from targeting the whole liver to locally targeted modifying processes. Nanomedicine delivered to HSCs has significant potential in managing liver fibrosis, where optimal management would benefit from targeted delivery, personalized therapy based on the specific site of interest, and minor side effects. In this review, we present a brief overview of the role of HSCs in the pathogenesis of liver fibrosis, summarize the different types of nanocarriers and their specific delivery applications in liver fibrosis, and highlight the biological barriers associated with the use of nanosystems to target HSCs and approaches available to solve this issue. We further discuss in-depth all the molecular target receptors overexpressed during HSC activation in liver fibrosis and their corresponding ligands that have been used for drug or gene delivery targeting HSCs.

Biomedical Metal-Organic Framework Materials: Perspectives and Challenges

Metal-organic framework (MOF) materials are gaining significant interest in biomedical research, owing to their high porosity, crystallinity, and structural and compositional diversity. Their versatile hybrid organic/inorganic chemistry endows MOFs with the capacity to retain organic (drug) molecules, metals, and gases, to effectively channel electrons and photons, to survive harsh physiological conditions such as low pH, and even to protect sensitive biomolecules. Extensive preclinical research has been carried out with MOFs to treat several pathologies and, recently, their integration with other biomedical materials such as stents and implants has demonstrated promising performance in regenerative medicine. However, there remains a significant gap between MOF preclinical research and translation into clinically and societally relevant medicinal products. Here, we outline the intrinsic features of MOFs and discuss how these are suited to specific biomedical applications like detoxification, drug and gas delivery, or as (combination) therapy platforms. We furthermore describe relevant examples of how MOFs have been engineered and evaluated in different medical indications, including cancer, microbial, and inflammatory diseases. Finally, we critically examine the challenges facing their translation into the clinic, with the goal of establishing promising research directions and more realistic approaches that can bridge the translational gap of MOFs and MOF-containing (nano)materials.

Bacteriophage-like Nanobiocatalysts with Spiky Topography and Dual-Atom Sites for Treating Drug-Resistant Bacteria

Overuse of antibiotics leads to the proliferation of drug-resistant bacterial strains, worsening global morbidity, and mortality rates. Bioinspired nanomaterials present a promising avenue for developing nonantibiotic strategies against drug-resistant bacteria. Here, we engineer a bacteriophage-inspired artificial nanobiocatalyst via nonstoichiometric W18O49 that features a spiky topography and synergistic dual-atom sites for combating drug-resistant bacterial infection. Benefiting from the strong interaction within the synergistic Fe-O-Mo sites, the synthesized spiky artificial nanobiocatalyst exhibits superior reactive oxygen species (ROS)-catalytic activity, attributed to the regulated adsorption affinity between the reaction intermediates and catalytic sites. The experimental and theoretical investigations demonstrate that the bioinspired biocatalyst can effectively capture and kill bacteria through its spiky morphology and potent ROS-catalytic activity, which can enable a significant reduction in bacterial viability through downregulating genes associated with biosynthesis, cellular maintenance, and respiration. In vivo experiments demonstrate that the spiky artificial biocatalyst accelerates the reconstruction of drug-resistant bacteria-infected skin wounds in rabbits, exhibiting efficacy comparable to that of vancomycin. It is expected that this bioinspired study on spiky artificial nanobiocatalysts offers a straightforward path to facilitate the development of both bionic and nonantibiotic disinfection strategies.

The Influence of Silver-Containing Bionanomaterials Based on Humic Ligands on Biofilm Formation in Opportunistic Pathogens

The uncontrolled use of antibiotics has led to a global problem of antimicrobial resistance. One of the main mechanisms of bacterial resistance is the formation of biofilms. In order to prevent the growth of antimicrobial resistance, it is crucial to develop new antibacterial agents that are capable of inhibiting the formation of biofilms. This makes this area of research highly relevant today. Promising candidates for these antibacterial agents are new bionanomaterials made from natural humic substances and silver nanoparticles. These substances have the potential to not only directly kill microorganisms but also penetrate biofilms and inhibit their formation. The goal of this study is to synthesize active pharmaceutical substances in the form of bionanomaterials, using ultradispersed silver nanoparticles in a matrix of coal humic substances, perform their characterization (NMR spectroscopy, TEM, and ICP-AES methods), and research their influence on biofilm formation in the most dangerous opportunistic pathogens (E. coli, Methicillin-resistant St. Aureus, K. pneumoniae, P. aeruginosa, St. aureus, A. baumannii, and K. Pneumonia). The results showed that all of the studied bionanomaterials had antibacterial activity against all of the opportunistic pathogens. Furthermore, they were found to have a suppressive effect on both pre-existing biofilms of these bacteria and their formation.

Advances in antitumor application of ROS enzyme-mimetic catalysts

The rapid growth of research on enzyme-mimetic catalysts (Enz-Cats) is expected to promote further advances in nanomedicine for biological detection, diagnosis and treatment of disease, especially tumors. ROS-based nanomedicines present fascinating potential in antitumor therapy owing to the rapid development of nanotechnology. In this review, we focus on the applications of Enz-Cats based on ROS in antitumor therapy. Firstly, the definition and category of ROS are introduced, and the key factors enhancing ROS levels are carefully elucidated. Then, the rationally engineered Enz-Cats via different synthetic approaches with high ROS-producing efficiencies are comprehensively discussed. Subsequently, oncotherapy application of Enz-Cats is comprehensively discussed, which integrates diverse synergistic treatment modalities and exhibits high efficiency in ROS generation. Finally, the challenges and future research direction of this field are presented. This review is dedicated to unraveling the enigmas surrounding the interplay of nanomedicine and organisms.

Application of metal-organic frameworks in infectious wound healing

Metal-organic frameworks (MOFs) are metal-organic skeleton compounds composed of self-assembled metal ions or clusters and organic ligands. MOF materials often have porous structures, high specific surface areas, uniform and adjustable pores, high surface activity and easy modification and have a wide range of prospects for application. MOFs have been widely used. In recent years, with the continuous expansion of MOF materials, they have also achieved remarkable results in the field of antimicrobial agents. In this review, the structural composition and synthetic modification of MOF materials are introduced in detail, and the antimicrobial mechanisms and applications of these materials in the healing of infected wounds are described. Moreover, the opportunities and challenges encountered in the development of MOF materials are presented, and we expect that additional MOF materials with high biosafety and efficient antimicrobial capacity will be developed in the future.

A New Theranostic Platform Against Gram-Positive Bacteria Based on Near-Infrared-Emissive Aggregation-Induced Emission Nanoparticles

Infections induced by Gram-positive bacteria pose a great threat to public health. Antibiotic therapy, as the first chosen strategy against Gram-positive bacteria, is inevitably associated with antibiotic resistance selection. Novel therapeutic strategies for the discrimination and inactivation of Gram-positive bacteria are thus needed. Here, a specific type of aggregation-induced emission luminogen (AIEgen) with near-infrared fluorescence emission as a novel antibiotic-free therapeutic strategy against Gram-positive bacteria is proposed. With the combination of a positively charged group into a highly twisted architecture, self-assembled AIEgens (AIE nanoparticles (NPs)) at a relatively low concentration (5 µm) exhibited specific binding and photothermal effect against living Gram-positive bacteria both in vitro and in vivo. Moreover, toxicity assays demonstrated excellent biocompatibility of AIE NPs at this concentration. All these properties make the AIE NPs as a novel generation of theranostic platform for combating Gram-positive bacteria and highlight their promising potential for in vivo tracing of such bacteria.

Porous Microspheres as Pathogen Traps for Sepsis Therapy: Capturing Active Pathogens and Alleviating Inflammatory Reactions

Sepsis is a systemic inflammatory response syndrome caused by pathogen infection, while the current antibiotics mainly utilized in clinical practice to combat infection result in the release of pathogen-associated molecular patterns (PAMPs) in the body. Herein, we provide an innovative strategy for controlling sepsis, namely, capturing active pathogens by means of extracorporeal blood purification. Carbon nanotubes (CNTs) were modified with dimethyldiallylammonium chloride (DDA) through γ-ray irradiation-induced graft polymerization to confer a positive charge. Then, CNT-DDAs are blended with polyurethane (PU) to prepare porous microspheres using the electro-spraying method. The obtained microspheres with a pore diameter of 2 μm served as pathogen traps and are termed as PU-CNT-DDA microspheres. Even at a high flow rate of 50 mL·min-1, the capture efficiencies of the PU-CNT-DDAs for Escherichia coli and Staphylococcus aureus remained 94.7% and 98.8%, respectively. This approach circumvents pathogen lysis and mortality, significantly curtails the release of PAMPs, and hampers the production of pro-inflammatory cytokines. Therefore, hemoperfusion using porous PU-CNT-DDAs as pathogen traps to capture active pathogens and alleviate inflammation opens a new route for sepsis therapy.

Multifunctional Therapeutic Nanodiamond Hydrogels for Infected-Wound Healing and Cancer Therapy

Wound infection and tumor recurrence are the two main threats to cancer patients after surgery. Although researchers have developed new treatment systems to address the two significant challenges simultaneously, the potential side effects of the heavy-metal-ion-based treatment systems still severely limit their widespread application in therapy. In addition, the wounds from tumor removal compared with general operative wounds are more complex. The tumor wounds mainly exhibit more hemorrhage, larger trauma area, greater vulnerability to bacterial infection, and residual tumor cells. Therefore, a multifunctional treatment platform is urgently needed to integrate rapid hemostasis, sterilization, wound healing promotion, and antitumor functions. In this work, nanodiamonds (NDs), a material that has been well proven to have excellent biocompatibility, are added into a solution of acrylic-grafted chitosan (CEC) and oxidized hyaluronic acid (OHA) to construct a multifunctional treatment platform (CEC-OHA-NDs). The hydrogels exhibit rapid hemostasis, a wound-healing-promoting effect, excellent self-healing, and injectable abilities. Moreover, CEC-OHA-NDs can effectively eliminate bacteria and inhibit tumor proliferation by the warm photothermal effect of NDs under tissue-penetrable near-infrared laser irradiation (NIR) without cytotoxicity. Consequently, we adopt a simple and convenient strategy to construct a multifunctional treatment platform using carbon-based nanomaterials with excellent biocompatibility to promote the healing of infected wounds and to inhibit tumor cell proliferation simultaneously.

Research progress of metal-organic framework nanozymes in bacterial sensing, detection, and treatment

The high efficiency and specificity of enzymes make them play an important role in life activities, but the high cost, low stability and high sensitivity of natural enzymes severely restrict their application. In recent years, nanozymes have become convincing alternatives to natural enzymes, finding utility across diverse domains, including biosensing, antibacterial interventions, cancer treatment, and environmental preservation. Nanozymes are characterized by their remarkable attributes, encompassing high stability, cost-effectiveness and robust catalytic activity. Within the contemporary scientific landscape, metal-organic frameworks (MOFs) have garnered considerable attention, primarily due to their versatile applications, spanning catalysis. Notably, MOFs serve as scaffolds for the development of nanozymes, particularly in the context of bacterial detection and treatment. This paper presents a comprehensive review of recent literature pertaining to MOFs and their pivotal role in bacterial detection and treatment. We explored the limitations and prospects for the development of MOF-based nanozymes as a platform for bacterial detection and therapy, and anticipate their great potential and broader clinical applications in addressing medical challenges.

pH-responsive on-demand release of eugenol from metal-organic frameworks for synergistic bacterial killing

Bacterial infections are a big challenge in clinical treatment, making it urgent to develop innovative antibacterial systems and therapies to combat bacterial infections. In this study, we developed a novel MOF-based synergistic antibacterial system (Eu@B-UiO-66/Zn) by loading a natural antibacterial substance (eugenol) with hierarchically porous MOF B-UiO-66 as a carrier and further complexing it with divalent zinc ions. Results indicate that the system achieved a controlled release of eugenol under pH responsive stimulation, with the complexation ability of eugenol and Zn2+ ions as a switch. Due to the destruction of a coordination bond between eugenol and Zn2+ ions by an acidic medium, the release of eugenol loaded in Eu@B-UiO-66/Zn reached 80% at pH 5.8, which was significantly higher than that under pH 8.0 (51%). Moreover, the inhibitory effect of Eu@B-UiO-66/Zn against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) after 24 h was 96.4% and 99.7%, respectively, owing to the synergistic antibacterial effect of eugenol and Zn2+ ions, which was significantly stronger than free eugenol and Eu@B-UiO-66. We hope that this strategy for constructing responsive MOF-based antibacterial carriers could have potential possibilities for the application of MOF materials in antibacterial fields.

Metal-organic framework-based advanced therapeutic tools for antimicrobial applications

The escalating concern over conventional antibiotic resistance has emphasized the urgency in developing innovative antimicrobial agents. In recent times, metal-organic frameworks (MOFs) have garnered significant attention within the realm of antimicrobial research due to their multifaceted antimicrobial attributes, including the sustained release of intrinsic or exogenous antimicrobial components, chemodynamically catalyzed generation of reactive oxygen species (ROS), and formation of photogenerated ROS. This comprehensive review provides a thorough overview of the synthetic approaches employed in the production of MOF-based materials, elucidating their underlying antimicrobial mechanisms in depth. The focal point lies in elucidating the research advancements across various antimicrobial modalities, encompassing intrinsic component release system, extraneous component release system, auto-catalytical system, and energy conversion system. Additionally, the progress of MOF-based antimicrobial materials in addressing wound infections, osteomyelitis, and periodontitis is meticulously elucidated, culminating in a summary of the challenges and potential opportunities inherent within the realm of antimicrobial applications for MOF-based materials. STATEMENT OF SIGNIFICANCE: Growing concerns about conventional antibiotic resistance emphasized the need for alternative antimicrobial solutions. Metal-organic frameworks (MOFs) have gained significant attention in antimicrobial research due to their diverse attributes like sustained antimicrobial components release, catalytic generation of reactive oxygen species (ROS), and photogenerated ROS. This review covers MOF synthesis and their antimicrobial mechanisms. It explores advancements in intrinsic and extraneous component release, auto-catalysis, and energy conversion systems. The paper also discusses MOF-based materials' progress in addressing wound infections, osteomyelitis, and periodontitis, along with existing challenges and opportunities. Given the lack of related reviews, our findings hold promise for future MOF applications in antibacterial research, making it relevant to your journal's readership.

Spiky Artificial Peroxidases with V-O-Fe Pair Sites for Combating Antibiotic-Resistant Pathogens

With the sharp rise of antibiotic-resistant pathogens worldwide, it is of enormous importance to create new strategies for combating pathogenic bacteria. Here, we create an iron oxide-based spiky artificial peroxidase (POD) with V-O-Fe pair sites (V-Fe2 O3 ) for combating methicillin-resistant Staphylococcus aureus (MRSA). The experimental studies and theoretical calculations demonstrate that the V-Fe2 O3 can achieve the localized "capture and killing" bifunction from the spiky morphology and massive reactive oxygen species (ROS) production. The V-Fe2 O3 can reach nearly 100 % bacterial inhibition over a long period by efficiently oxidizing the lipid membrane. Our wound disinfection results identify that the V-Fe2 O3 can not only efficiently eliminate MRSA and their biofilm but also accelerate wound recovery without causing noticeable inflammation and toxicity. This work offers essential insights into the critical roles of V-O-Fe pair sites and localized "capture and killing" in biocatalytic disinfection and provides a promising pathway for the de novo design of efficient artificial peroxidases.

Peptide-containing nanoformulations: Skin barrier penetration and activity contribution

Transdermal drug delivery presents a less invasive pathway, circumventing the need to pass through the gastrointestinal tract and liver, thereby reducing drug breakdown, initial metabolism, and gastrointestinal discomfort. Nevertheless, the unique composition and dense structure of the stratum corneum present a significant barrier to transdermal delivery. This article presents an overview of the current developments in peptides and nanotechnology to address this challenge. Initially, we sum up peptide-containing nanoformulations for transdermal drug delivery, examining them through the lenses of both inorganic and organic materials. Particular emphasis is placed on the diverse roles that peptides play within these nanoformulations, including conferring functionality upon nanocarriers and enhancing the biological efficacy of drugs. Subsequently, we summarize innovative strategies for enhancing skin penetration, categorizing them into passive and active approaches. Lastly, we discuss the therapeutic potential of peptide-containing nanoformulations in addressing a range of diseases, drawing insights from the biological activities and functions of peptides. Furthermore, the challenges hindering clinical translation are also discussed, providing valuable insights for future advancements in transdermal drug delivery.

Nanomaterials-Enabled Physicochemical Antibacterial Therapeutics: Toward the Antibiotic-Free Disinfections

Bacterial infection continues to be an increasing global health problem with the most widely accepted treatment paradigms restricted to antibiotics. However, the overuse and misuse of antibiotics have triggered multidrug resistance of bacteria, frustrating therapeutic outcomes, and leading to higher mortality rates. Even worse, the tendency of bacteria to form biofilms on living and nonliving surfaces further increases the difficulty in confronting bacteria because the extracellular matrix can act as a robust barrier to prevent the penetration of antibiotics and resist environmental damage. As a result, the inability to eliminate bacteria and biofilms often leads to persistent infection, implant failure, and device damage. Therefore, it is of paramount importance to develop alternative antimicrobial agents while avoiding the generation of bacterial resistance to prevent the large-scale growth of bacterial resistance. In recent years, nano-antibacterial materials have played a vital role in the antibacterial field because of their excellent physical and chemical properties. This review focuses on new physicochemical antibacterial strategies and versatile antibacterial nanomaterials, especially the mechanism and types of 2D antibacterial nanomaterials. In addition, this advanced review provides guidance on the development direction of antibiotic-free disinfections in the antibacterial field in the future.

Hydrogel-Loaded Exosomes: A Promising Therapeutic Strategy for Musculoskeletal Disorders

Clinical treatment strategies for musculoskeletal disorders have been a hot research topic. Accumulating evidence suggests that hydrogels loaded with MSC-derived EVs show great potential in improving musculoskeletal injuries. The ideal hydrogels should be capable of promoting the development of new tissues and simulating the characteristics of target tissues, with the properties matching the cell-matrix constituents of autologous tissues. Although there have been numerous reports of hydrogels loaded with MSC-derived EVs for the repair of musculoskeletal injuries, such as intervertebral disc injury, tendinopathy, bone fractures, and cartilage injuries, there are still many hurdles to overcome before the clinical application of modified hydrogels. In this review, we focus on the advantages of the isolation technique of EVs in combination with different types of hydrogels. In this context, the efficacy of hydrogels loaded with MSC-derived EVs in different musculoskeletal injuries is discussed in detail to provide a reference for the future application of hydrogels loaded with MSC-derived EVs in the clinical treatment of musculoskeletal injuries.

Aptamer and DNAzyme-Functionalized Cu-MOF Hybrid Nanozymes for the Monitoring and Management of Bacteria-Infected Wounds

Metal-organic frameworks (MOFs) with peroxidase (POD)-like activity have great potential for combating drug-resistant bacterial infections. However, the use of POD-like activities is severely limited by low oxygen levels and high levels of glutathione (GSH) within the microenvironment of bacterial infection. Herein, G-quadruplex/hemin DNAzyme-aptamer probes and tannic acid-chelated Au nanoparticle (Au-TA)-decorated Cu-based MOF nanosheets (termed GATC) with triple-enzyme activities were developed for visual detection and efficient antibacterial therapy. First, the monometallic MOFs (Cu-ZIF) showed the best catalytic and loading capacity performance compared with the bimetallic MOFs (CoCu-ZIF and ZnCu-ZIF). Then, Cu-MOFs, Au-TA, and DNAzyme improve the POD-like activity to generate more hydroxyl radicals (•OH) to kill bacteria. GATC can bind to bacteria through aptamer recognition, increasing the bacterial surface contact area for efficient antibacterial activity. GATC can decompose H2O2 into O2 to alleviate hypoxia and improve the microenvironment due to its catalase (CAT)-like activity. In addition, GATC exhibited GSH peroxidase-like activity, which can avoid the loss of •OH and result in bacterial death more easily. Compared with previous studies, GATC exhibited extraordinary bactericidal ability at an extremely low dosage of 3 μg/mL against methicillin-resistant Staphylococcus aureus (MRSA). Notably, the GATC-catalyzed chromogenic reaction could accurately monitor the MRSA infection treatment process. Overall, this work could establish a therapeutic platform for the monitoring and management of bacteria-infected wounds.

Nitric Oxide-Assisted Photodynamic Therapy for Enhanced Penetration and Hypoxic Bacterial Biofilm Elimination

The presence of a biofilm matrix barrier and hypoxic microenvironment within the biofilm significantly impedes the efficacy of photodynamic therapy for bacterial biofilm infections. Herein, a phototherapeutic nanoagent with type-I photodynamic behavior and nitric oxide (NO) release performance is reported for overcoming biofilm-associated infectious diseases. Sodium nitroprusside (SNP), a NO donor, is loaded onto amino-modified mesoporous silica nanoparticles (MSN) to form MSN@SNP NPs. The resulting nanoparticles are further modified with a porphyrin-based metal-organic framework (Ti-TCPP MOF) to obtain MSN@MOF/SNP NPs (MMS NPs) for phototherapeutic applications. In the hypoxia biofilm microenvironment, the MMS NPs release NO to enhance the biofilm permeability and induce the generation of hydroxyl radical (•OH) and superoxide anion radical (O2 •- ) via Type-I photodynamic pathway under laser irradiation. Subsequently, the biofilm-associated infections are effectively eliminated through reactive oxygen species (ROS) and NO gas synergistic therapy. In addition, NO also stimulates collagen deposition and promotes angiogenesis in vivo. Therefore, the MMS NPs efficiently treat biofilm-related infections, providing an alternative approach to combat biofilm-associated infectious diseases.

Portable Biosensor with Bimetallic Metal-Organic Frameworks for Visual Detection and Elimination of Bacteria

A multifunctional platform that meets the demands of both bacterial detection and elimination is urgently needed because of their harm to human health. Herein, a "sense-and-treat" biosensor was developed by using immunomagnetic beads (IMBs) and AgPt nanoparticle-decorated PCN-223-Fe (AgPt/PCN-223-Fe, PCN stands for porous coordination network) metal-organic frameworks (MOFs). The synthesized AgPt/PCN-223-Fe not only exhibited excellent peroxidase-like activity but also could efficiently kill bacteria under near infrared (NIR) irradiation. This biosensor enabled the colorimetric detection of E. coli O157:H7 in the range of 103-108 CFU/mL with a limit of detection of 276 CFU/mL, accompanied with high selectivity, good reproducibility, and wide applicability in diverse real samples. Furthermore, the biosensor possessed a highly effective antibacterial rate of 99.94% against E. coli O157:H7 under 808 nm light irradiation for 20 min. This strategy can provide a reference for the design of novel versatile biosensors for bacterial discrimination and antibacterial applications.

Boosting Antibacterial Photodynamic Therapy in a Nanosized Zr MOF by the Combination of Ag NP Encapsulation and Porphyrin Doping

Antibacterial photodynamic therapy (aPDT) is regarded as one of the most promising antibacterial therapies due to its nonresistance, noninvasion, and rapid sterilization. However, the development of antibacterial materials with high aPDT efficacy is still a long-standing challenge. Herein, we develop an effective antibacterial photodynamic composite UiO-66-(SH)2@TCPP@AgNPs by Ag encapsulation and 4,4',4″,4‴-(porphine-5,10,15,20-tetrayl)tetrakis(benzoic acid) (TCPP) dopant. Through a mix-and-match strategy in the self-assembly process, 2,5-dimercaptoterephthalic acid containing -SH groups and TCPP were uniformly decorated into the UiO-66-type framework to form UiO-66-(SH)2@TCPP. After Ag(I) impregnation and in situ UV light reduction, Ag NPs were formed and encapsulated into UiO-66-(SH)2@TCPP to get UiO-66-(SH)2@TCPP@AgNPs. In the resulting composite, both Ag NPs and TCPP can effectively enhance the visible light absorption, largely boosting the generation efficiency of reactive oxygen species. Notably, the nanoscale size enables it to effectively contact and be endocytosed into bacteria. Consequently, UiO-66-(SH)2@TCPP@AgNPs show a very high aPDT efficacy against Gram-negative and Gram-positive bacteria as well as drug-resistant bacteria (MRSA). Furthermore, the Ag NPs were firmly anchored at the framework by the high density of -SH moieties, avoiding the cytotoxicity caused by the leakage of Ag NPs. By in vitro experiments, UiO-66-(SH)2@TCPP@AgNPs show a very high antibacterial activity and good biocompatibility as well as the potentiality to promote cell proliferation.

Photothermal/Photoacoustic Therapy Combined with Metal-Based Nanomaterials for the Treatment of Microbial Infections

The increased spread and persistence of bacterial drug-resistant phenotypes remains a public health concern and has contributed significantly to the challenge of combating antibiotic resistance. Nanotechnology is considered an encouraging strategy in the fight against antibiotic-resistant bacterial infections; this new strategy should improve therapeutic efficacy and minimize side effects. Evidence has shown that various nanomaterials with antibacterial performance, such as metal-based nanoparticles (i.e., silver, gold, copper, and zinc oxide) have intrinsic antibacterial properties. These antibacterial agents, such as those made of metal oxides, carbon nanomaterials, and polymers, have been used not only to improve antibacterial efficacy but also to reduce bacterial drug resistance due to their interaction with bacteria and their photophysical properties. These nanostructures have been used as effective agents for photothermal therapy (PTT) and photodynamic therapy (PDT) to kill bacteria locally by heating or the controlled production of reactive oxygen species. Additionally, PTT or PDT therapies have also been combined with photoacoustic (PA) imaging to simultaneously improve treatment efficacy, safety, and accuracy. In this present review, we present, on the one hand, a summary of research highlighting the use of PTT-sensitive metallic nanomaterials for the treatment of bacterial and fungal infections, and, on the other hand, an overview of studies showing the PA-mediated theranostic functionality of metal-based nanomaterials.

Improving the functionality of biodegradable food packaging materials via porous nanomaterials

Non-biodegradability and disposal problems are the major challenges associated with synthetic plastic packaging. This review article discusses a new generation of biodegradable active and smart packaging based on porous nanomaterials (PNMs), which maintains the quality and freshness of food products while meeting biodegradability requirements. PNMs have recently gained significant attention in the field of food packaging due to their large surface area, peculiar structures, functional flexibility, and thermal stability. We present for the first time the recently published literature on the incorporation of various PNMs into renewable materials to develop advanced, environmentally friendly, and high-quality packaging technology. Various emerging packaging technologies are discussed in this review, along with their advantages and disadvantages. Moreover, it provides general information about PNMs, their characterization, and fabrication methods. It also briefly describes the effects of different PNMs on the functionality of biopolymeric films. Furthermore, we examined how smart packaging loaded with PNMs can improve food shelf life and reduce food waste. The results indicate that PNMs play a critical role in improving the antimicrobial, thermal, physicochemical, and mechanical properties of natural packaging materials. These tailor-made materials can simultaneously extend the shelf life of food while reducing plastic usage and food waste.

Photoactive MOF-Derived Bimetallic Silver and Cobalt Nanocomposite with Enhanced Antibacterial Activity

Conventional antibiotic-based treatment of bacterial infections remains one of the most difficult challenges in medicine because of the threat of multidrug resistance caused by indiscriminate abuse. To solve these problems, it is essential to develop an effective antibacterial agent that can be used at a small dose while minimizing the occurrence of multiple resistance. Metal-organic frameworks (MOFs), which are hyper-porous hybrid materials containing metal ions linked by organic ligands, have recently attracted attention because of their strong antibacterial activity through metal-ion release, unlike conventional antibiotics. In this study, we developed a photoactive MOF-derived cobalt-silver bimetallic nanocomposite (Ag@CoMOF) by simply depositing silver nanoparticles on a cobalt-based MOF through nanoscale galvanic replacement. The nanocomposite structure continuously releases antibacterial metal ions (i.e., Ag and Co ions) in the aqueous phase and exhibits a strong photothermal conversion effect of Ag nanoparticles, accompanied by a rapid temperature increase of 25-80 °C under near-infrared (NIR) irradiation. Using this MOF-based bimetallic nanocomposite, superior antibacterial activities were achieved by 22.1-fold for Escherichia coli and 18.3-fold for Bacillus subtilis enhanced inhibition of bacterial growth in a liquid culture environment compared with the generally used chemical antibiotics. In addition, we confirmed the synergistic enhancement of the antibacterial ability of the bimetallic nanocomposite induced by NIR-triggered photothermal heating and bacterial membrane disruption even when using a small amount of the nanocomposites. We envision that this novel antibacterial agent using MOF-based nanostructures will replace traditional antibiotics to circumvent multidrug resistance and present a new approach to antibiotic development.

Bacterial cellulose-based hydrogel with antibacterial activity and vascularization for wound healing

Skin wounds need an appropriate wound dressing to help prevent bacterial infection and accelerate wound closure. Bacterial cellulose (BC) with a three-dimensional (3D) network structure is an important commercial dressing. However, how to effectively load antibacterial agents and balance the antibacterial activity is a lingering issue. Herein, this study aims to develop a functional BC hydrogel containing silver-loaded zeolitic imidazolate framework-8 (ZIF-8) antibacterial agent. The tensile strength of the prepared biopolymer dressing is >1 MPa, the swelling property is over 3000 %, the temperature can reach 50 °C in 5 min with near-infrared (NIR) and the release of Ag⁺ and Zn²⁺ is stable. In vitro investigation shows that the hydrogel displays enhanced antibacterial activity, and the bacteria survival ratios are only 0.85 % and 0.39 % against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In vitro cell experiments present that BC/polydopamine/ZIF-8/Ag (BC/PDA/ZIF-8/Ag) shows satisfactory biocompatibility and promising angiogenic ability. In vivo study, the full-thickness skin defect on rats demonstrates remarkably wound healing ability and accelerated skin re-epithelialization. This work presents a competitive functional dressing with effective antibacterial properties and accelerative angiogenesis activities for wound repair.

Photothermal Nanomaterials: A Powerful Light-to-Heat Converter

All forms of energy follow the law of conservation of energy, by which they can be neither created nor destroyed. Light-to-heat conversion as a traditional yet constantly evolving means of converting light into thermal energy has been of enduring appeal to researchers and the public. With the continuous development of advanced nanotechnologies, a variety of photothermal nanomaterials have been endowed with excellent light harvesting and photothermal conversion capabilities for exploring fascinating and prospective applications. Herein we review the latest progresses on photothermal nanomaterials, with a focus on their underlying mechanisms as powerful light-to-heat converters. We present an extensive catalogue of nanostructured photothermal materials, including metallic/semiconductor structures, carbon materials, organic polymers, and two-dimensional materials. The proper material selection and rational structural design for improving the photothermal performance are then discussed. We also provide a representative overview of the latest techniques for probing photothermally generated heat at the nanoscale. We finally review the recent significant developments of photothermal applications and give a brief outlook on the current challenges and future directions of photothermal nanomaterials.

Flexible free-standing antibacterial nanoporous Ag ribbon

The biomedical field has the potential to significantly benefit from the use of flexible free-standing Ag nanostructures due to their outstanding mechanical and antibacterial properties. However, the intricate process of synthesizing these nanostructures, as well as the potential toxicity of nanostructured Ag, pose significant challenges. This study used a facile etching method to synthesize the free-standing nanoporous Ag (NP-Ag) ribbons with a homogeneous and bicontinuous three-dimensional ligament structure. The free-standing NP-Ag ribbons demonstrated stable mechanical performance and excellent flexibility when subjected to various deformation states on artificial fingers. Additionally, the NP-Ag ribbons exhibited remarkable antibacterial capacity with rates of 99.81 ± 0.14% against Escherichia coli, 96.11 ± 1.49% against Staphylococcus aureus, and 95.37 ± 1.24% against methicillin-resistant Staphylococcus aureus. The antibacterial mechanism of NP-Ag is attributed to the rapid release of Ag ions (Ag⁺) in 24 h, causing damage to the bacterial membrane. Moreover, the in vivo results demonstrate that the NP-Ag ribbons provide rapid antibacterial efficacy and are biosafe due to the long-term stable Ag⁺ release of NP-Ag. The development of these free-standing flexible NP-Ag ribbons offers a new avenue for wearable antibacterial applications.

Disintegration and Machine-Learning-Assisted Identification of Bacteria on Antimicrobial and Plasmonic Ag-CuxO Nanostructures

Bacteria cause many common infections and are the culprit of many outbreaks throughout history that have led to the loss of millions of lives. Contamination of inanimate surfaces in clinics, the food chain, and the environment poses a significant threat to humanity, with the increase in antimicrobial resistance exacerbating the issue. Two key strategies to address this issue are antibacterial coatings and effective detection of bacterial contamination. In this study, we present the formation of antimicrobial and plasmonic surfaces based on Ag-CuxO nanostructures using green synthesis methods and low-cost paper substrates. The fabricated nanostructured surfaces exhibit excellent bactericidal efficiency and high surface-enhanced Raman scattering (SERS) activity. The CuxO ensures outstanding and rapid antibacterial activity within 30 min, with a rate of >99.99% against typical Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. The plasmonic Ag nanoparticles facilitate the electromagnetic enhancement of Raman scattering and enables rapid, label-free, and sensitive identification of bacteria at a concentration as low as 103 cfu/mL. The detection of different strains at this low concentration is attributed to the leaching of the intracellular components of the bacteria caused by the nanostructures. Additionally, SERS is coupled with machine learning algorithms for the automated identification of bacteria with an accuracy that exceeds 96%. The proposed strategy achieves effective prevention of bacterial contamination and accurate identification of the bacteria on the same material platform by using sustainable and low-cost materials.

Bioinspired MoS2 Nanosheet-Modified Carbon Fibers for Synergetic Bacterial Elimination and Wound Disinfection

Bacterial infection is one of the most frequent wound complications and has become a major public health concern. Increasing resistance to antibiotics has been noted with these agents broadly used in wound management. It is an urgent demand to develop alternative antibacterial strategies with a reduced chance of resistance. Herein, a Nepenthes-mimicking nanosheet array of MoS₂ on carbon fibers (CF-MoS₂ ) is proposed to achieve dual bactericidal activities. First, the sharp edges of synthesized surfaces are capable of inducing physical disruption of cell membranes, demonstrating mechanical antibacterial activity like their natural counterparts. Second, in the presence of near-infrared light, bioinspired CF-MoS₂ nanosheets are able to cause the death of damaged bacteria owing to their inherent photothermal properties. Such dual-functional modes endow the surfaces with nearly 100% killing efficiency for highly concentrated Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Furthermore, their potential to be applied as wound dressings for photothermal treatment of infectious wounds is also investigated in vivo. Bioinspired CF-MoS₂ dressings show advantages of synergistic disinfection and efficient promotion of wound regeneration. It is foreseen that this high-performance and multifunctional CF-MoS₂ could afford a feasible broad-spectrum treatment for non-antibiotic disinfection.

How Effective are Metal Nanotherapeutic Platforms Against Bacterial Infections? A Comprehensive Review of Literature

The emergence of multidrug-resistant bacteria has been deemed a global crisis that affects humans worldwide. Novel anti-infection strategies are desperately needed because of the limitations of conventional antibiotics. However, the increasing gap between clinical demand and antimicrobial treatment innovation, as well as the membrane permeability obstacle especially in gram-negative bacteria fearfully restrict the reformation of antibacterial strategy. Metal-organic frameworks (MOFs) have the advantages of adjustable apertures, high drug-loading rates, tailorable structures, and superior biocompatibilities, enabling their utilization as drug delivery carriers in biotherapy applications. Additionally, the metal elements in MOFs are usually bactericidal. This article provides a review of the state-of-The-art design, the underlying antibacterial mechanisms and antibacterial applications of MOF- and MOF-based drug-loading materials. In addition, the existing problems and future perspectives of MOF- and MOF-based drug-loading materials are also discussed.

Enhanced antibacterial effect and biodegradation of coating via dual-in-situ growth based on carboxymethyl cellulose

The lack of antimicrobial effect of commercial paper coating for food packaging makes it difficult to prevent food spoilage and harms the environment by non-biodegradation. Herein, carboxymethyl cellulose (CMC) provides negatively charged sites for anchoring Ag⁺ and Zn²⁺ to grow AgNPs and ZIF-8 in situ on its molecular chains. The ZIF-8/AgNPs@CMC paper coating has excellent synergistic antibacterial activity to prolong the shelf-life of food. It not only has good thermal stability but binds closely to the paper and its adhesion force reaches 628.9 nN. Besides, the ZIF-8/AgNPs@CMC coated paper has better mechanical properties, water vapor barrier, and resists water solubility. Interestingly, due to the confinement effect of ZIF-8, the cumulative release of AgNPs after 168 h is only 2.66 % to avoid possible food safety risks. Especially, the coating can be almost biodegraded in the soil after 30 days, which provides the possibility to replace the non-biodegradable coatings in food packaging.

Photothermal Hydrogels for Promoting Infected Wound Healing

Photothermal therapies (PTT), with spatiotemporally controllable antibacterial capabilities without inducing resistance, have shown encouraging prospects in the field of infected wound treatments. As an important platform for PTT, photothermal hydrogels exhibit attractive advantages in the field of infected wound treatment due to their excellent biochemical properties and have been intensively explored in recent years. This review summarizes the progress of the photothermal hydrogels for promoting infected wound healing. Three major elements of photothermal hydrogels, i.e., photothermal materials, hydrogel matrix, and construction methods, are introduced. Furthermore, different strategies of photothermal hydrogels in the treatment of infected wounds are summarized. Finally, the challenges and prospects in the clinical treatment of photothermal hydrogels are discussed.

When Iodine Meets Starch: On-Demand Generation of Photothermal Hydrogels for Mild-Temperature Photothermal-Chemo Disinfection

As an emerging antibacterial strategy, photothermal disinfection attracts increasing attention due to its advantages of high efficacy, wide pertinence, and non-drug resistance. However, the unavoidable shielding of observation by photothermal components and the possible damage to normal tissue caused by hyperthermia restrict its applications. Herein, we propose a composite hydrogel with the ability of on-demand generation of photothermal components and mild-temperature photothermal disinfection by elegantly tuning the binding and release of iodine and starch. The composite hydrogel is obtained by blending iodine-adsorbed pH-responsive ZIF-8 nanoparticles (NPs) with a starch-based hydrogel matrix. Through a convenient pH response, the composite hydrogel leverages the triple functions of iodine, which serves as a disinfectant and reacts with starch to generate a photothermal agent and color indicator, allowing photothermal-chemotherapy combined disinfection on demand. In vitro antibacterial experiments show that the composite hydrogel can respond to the acidification of the microenvironment caused by bacterial metabolism and produce corresponding color changes, realizing naked-eye observation. Meanwhile, under the combined treatment of heating/I2/Zn2+, the composite hydrogel can completely kill Escherichia coli and Staphylococcus aureus at a mild temperature of ∼41 °C. This study represents a breakthrough in on-demand generation of photothermal hydrogels for mild-temperature photothermal disinfection.

Antibacterial and Antiviral Coating on Surfaces through Dopamine-Assisted Codeposition of an Antifouling Polymer and In Situ Formed Nanosilver

Bacteria and viruses can adhere onto diverse surfaces and be transmitted in multiple ways. A bifunctional coating that integrates both antibacterial and antiviral activities is a promising approach to mitigate bacterial and viral infections arising from a contaminated surface. However, current coating approaches encounter a slow reaction, limited activity against diverse bacteria or viruses, short-term activity, difficulty in scaling-up, and poor adaptation to diverse material surfaces. Here, we report a new one-step strategy for the development of a polydopamine-based nonfouling antibacterial and antiviral coating by the codeposition of various components. The in situ formed nanosilver in the presence of polydopamine was incorporated into the coating and served as both antibacterial and antiviral agents. In addition, the coassembly of polydopamine and a nonfouling hydrophilic polymer was constructed to prevent the adhesion of bacteria and viruses on the coating. The coating was prepared on model surfaces and thoroughly characterized using various surface analytical techniques. The coating exhibited strong antifouling properties with a reduction of nonspecific protein adsorption up to 90%. The coating was tested against both Gram-positive and Gram-negative bacteria and showed long-term antibacterial effectiveness, which correlated with the composition of the coating. The antiviral activity of the coating was evaluated against human coronavirus 229E. A possible mechanism of action of the coating was proposed. We anticipate that the optimized coating will have applications in the development of infection prevention devices and surfaces.

Natural Small Biological Molecule Based Supramolecular Bioadhesives with Innate Photothermal Antibacterial Capability for Nonpressing Hemostasis and Effective Wound Healing

Bioadhesives with immediate wound closure, efficient hemostasis, and antibacterial properties that can well integrate with tissue are urgently needed in wound management. Natural small biological molecule based bioadhesives hold great promise for manipulating wound healing by taking advantage of integrated functionalities, synthetic simplification, and accuracy, cost efficiency and biosafety. Herein, a natural small biological molecule based bioadhesive, composed of natural small biological molecules (α-lipoic acid and tannic acid) and a small amount of ferric chloride, was prepared via an extremely simple and green route for wound management. In this system, covalent and noncovalent interactions between each component resulted in the self-healing supramolecular bioadhesive. It possessed appropriate wet-tissue adhesion, efficient nonpressing hemostasis and free radical scavenging abilities. More importantly, the interaction between tannic acid and Fe³⁺ endowed the bioadhesive with innate and steady photothermal activity, which showed excellent photothermal bactericidal activity to both E. coli and S. aureus. The bioadhesive promoted wound healing for linear and circular wounds in vivo, especially for infectious wounds under near-infrared (NIR) irradiation. This bioadhesive will have promising value as a safe and effective antimicrobial adhesive for infectious wound management.

Immunomodulatory biomaterials for implant-associated infections: from conventional to advanced therapeutic strategies

Implant-associated infection (IAI) is increasingly emerging as a serious threat with the massive application of biomaterials. Bacteria attached to the surface of implants are often difficult to remove and exhibit high resistance to bactericides. In the quest for novel antimicrobial strategies, conventional antimicrobial materials often fail to exert their function because they tend to focus on direct bactericidal activity while neglecting the modulation of immune systems. The inflammatory response induced by host immune cells was thought to be a detrimental force impeding wound healing. However, the immune system has recently received increasing attention as a vital player in the host's defense against infection. Anti-infective strategies based on the modulation of host immune defenses are emerging as a field of interest. This review explains the importance of the immune system in combating infections and describes current advanced immune-enhanced anti-infection strategies. First, the characteristics of traditional/conventional implant biomaterials and the reasons for the difficulty of bacterial clearance in IAI were reviewed. Second, the importance of immune cells in the battle against bacteria is elucidated. Then, we discuss how to design biomaterials that activate the defense function of immune cells to enhance the antimicrobial potential. Based on the key premise of restoring proper host-protective immunity, varying advanced immune-enhanced antimicrobial strategies were discussed. Finally, current issues and perspectives in this field were offered. This review will provide scientific guidance to enhance the development of advanced anti-infective biomaterials.

Triple-synergistic MOF-nanozyme for efficient antibacterial treatment

The abuse of antibiotics makes bacterial infection an increasingly serious global health threat. Reactive oxygen species (ROS) are the ideal alternative antibacterial approach for quick and effective sterilization. Although various antibacterial strategies based on ROS have been developed, many of them are still limited by insufficient antibacterial efficiency. Here, we have developed an acid-enhanced dual-modal antibacterial strategy based on zeolitic imidazolate frameworks-8 (ZIF8) -derived nanozyme. ZIF8, which can release Zn2+, is chosen as the carrier to integrate glucose oxidase (GOx) and gold nanoparticles (Au NPs) which can produce ROS via a cascade catalytic reaction. Thus, the bactericidal capability of ROS and Zn2+ have been integrated. More importantly, gluconic acid, a "by-product" of the catalytic reaction, can generate an acidic environment to promote both the ROS-producing and Zn2+-releasing, enhancing the overall antibacterial performance further. This triple-synergistic strategy exhibits extraordinary bactericidal ability at a low dosage of 4 μg/mL (for S. aureus) and 8 μg/mL (for E. coli), which shows a great potential of MOF-derived nanozyme for efficient bacterial eradication and diverse biomedical applications.

Nanoscale MOFs: From synthesis to drug delivery and theranostics applications

Since the first report in 1989, Metal-Organic Frameworks (MOFs) self-assembled from metal ions or clusters, as well as organic linkers, have attracted extensive attention. Due to their flexible composition, large surface areas, modifiable surface properties, and their degradability, there has been an exponential increase in the study of MOFs materials, specifically in drug delivery system areas such as infection, diabetes, pulmonary disease, ocular disease, imaging, tumor therapy, and especially cancer theranostics. In this review, we discuss the trends in MOFs biosafety, from "green" synthesis to applications in drug delivery systems. Firstly, we present the different "green" synthesis approaches used to prepare MOFs materials. Secondly, we detail the methods for the functional coating, either through grafting targeting units, poly(ethylene glycol) (PEG) chains or by using cell membranes. Then, we discuss drug encapsulation strategies, host-guest interactions, as well as drug release mechanisms. Lastly, we report on the drug delivery applications of nanoscale MOFs. In particular, we discuss MOFs-based imaging techniques, including magnetic resonance imaging (MRI), photoacoustic imaging (PAI), positron emission tomography (PET), and fluorescence imaging. MOFs-based cancer therapy methods are also presented, such as photothermal therapy (PTT), photodynamic therapy (PDT), radiotherapy (RT), chemotherapy, and immunotherapy.