Dendritic Fe3O4@Poly(dopamine)@PAMAM Nanocomposite as Controllable NO‐Releasing Material: A Synergistic Photothermal and NO Antibacterial Study

Nowadays, antibiotic abuse increases the emergence of multidrug‐resistant bacterial strains, which is the major reason for the failure of conventional antibiotic therapies. Therefore, developing novel antibacterial materials or therapies is an urgent demand. In the present study, photothermal and NO‐releasing properties are integrated into a single nanocomposite to realize more efficient bactericidal effects. To this end, polydopamine (PDA) coated iron oxide nanocomposite (Fe₃O₄@PDA) is used as a photoconversion agent and the core, first three generation dendritic poly(amidoamine) (PAMAM‐G3) is grafted on the surface of Fe₃O₄@PDA, and subsequently NO is loaded with the formation of NONOate. The resultant Fe₃O₄@PDA@PAMAM@NONOate displays controllable NO release property under intermittent 808 nm laser irradiation and excellent bacteria‐separation efficiency. Moreover, excellent synergistic photothermal and NO antibacterial effects are observed against both Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus, where bacterial viability and biofilm are significantly reduced. An antibacterial mechanism study reveals that the materials first adsorb onto the bacterial membrane, then cause damage to the membrane by the increased local temperature and the released NO under laser irradiation conditions, finally leak the intracellular components like DNA and induce bacteria death. The work provides a novel way for designing of antibacterial materials with higher efficiency.     

Polycationic Synergistic Antibacterial Agents with Multiple Functional Components for Efficient Anti‐Infective Therapy

Multifunctional antibacterial photodynamic therapy is a promising method to combat regular and multidrug‐resistant bacteria. In this work, eosin Y (EY)‐based antibacterial polycations (EY‐QEGED? R, R = ? CH₃ or ? C₆H₁₃) with versatile types of functional components including quaternary ammonium, photosensitizer, primary amine, and hydroxyl species are readily synthesized based on simple ring‐opening reactions. In the presence of light irradiation, such antibacterial polymers exhibit high antibacterial efficiency against both Escherichia coli and Staphylococcus aureus. In particular, EY‐QEGED? R elicits a remarkable synergistic antibacterial activity owing to the combined photodynamic and quaternary ammonium antibacterial effects. Due to its rich primary amine groups, EY‐QEGED? R also can be readily coated on different substrates, such as glass slides and nonwoven fabrics via an adhesive layer of polydopamine. The resultant surface coating of EY‐QEGED? CH₃ (s‐EY‐QEGED? CH₃) produces excellent in vitro antibacterial efficacy. The plentiful hydroxyl groups impart s‐EY‐QEGED? CH₃ with potential antifouling capability against dead bacteria. The antibacterial polymer coatings also demonstrate low cytotoxicity and good hemocompatibility. More importantly, s‐EY‐QEGED? CH₃ significantly enhances in vivo therapeutic effects on an infected rat model. The present work provides an efficient strategy for the rational design of high‐performance antibacterial materials to fight biomedical device‐associated infections.     

Biodegradable Supramolecular Materials Based on Cationic Polyaspartamides and Pillar[5]arene for Targeting Gram‐Positive Bacteria and Mitigating Antimicrobial Resistance

The increasing number of infections caused by pathogenic bacteria has severely affected human society, for instance, numerous deaths are from Gram‐positive methicillin‐resistant Staphylococcus aureus (MRSA) each year. In this work, four biodegradable antibacterial polymer materials based on cationic polyaspartamide derivatives with different lengths of side chains are synthesized through the ring‐opening polymerization of β‐benzyl‐l ‐aspartate N‐carboxy anhydride, followed by an aminolysis reaction and subsequent methylation reaction. The cationic quaternary ammonium groups contribute to the insertion of the catiomers into the negatively charged bacterial membranes, which leads to membranolysis, the leakage of bacterial content, and the death of pathogens. Except for wiping out MRSA readily, the biodegradable polymers possessing alterable antibacterial potency can minimize the possibility of microbial resistance and mitigate drug accumulation by virtue of their cleavable backbone. To manipulate the poor biocompatibility of these polycations, carboxylatopillar[5]arene (CP[5]A) is introduced to the polymeric antibacterial catiomers through the supramolecular host–guest approach to obtain novel antibacterial materials with pH‐sensitive characteristics (with CP[5]A departure from cationic quaternary ammonium compounds under acid conditions) and selective targeting of Gram‐positive bacteria. Finally, the facile and robust antibacterial system is successfully applied to in vivo MRSA‐infected wound healing, providing a significant reference for the construction of advanced antibacterial biomaterials.     

Layer‐By‐Layer Coating of Aminocellulose and Quorum Quenching Acylase on Silver Nanoparticles Synergistically Eradicate Bacteria and Their Biofilms

The emergence of antibiotic‐resistant bacteria and the failure of the existing antibacterial therapeutics call for development of novel treatment strategies. Furthermore, the formation of bacterial biofilms restricts drug penetration and efficiency, causing life‐threatening infections. Bacterial attachment and biofilm formation are regulated by the cell‐to‐cell communication phenomenon called quorum sensing (QS). In this work, antimicrobial silver nanoparticles (AgNPs) are decorated in a layer‐by‐layer fashion with the oppositely charged aminocellulose (AM) and acylase to generate hybrid nanoentities with enhanced antibacterial and antibiofilm activities as well as reduced cytotoxicity. Acylase, a quorum‐quenching enzyme that degrades the QS signals in the extracellular environment of bacteria, disrupts the bacterial QS process and together with the bactericidal AM synergistically lowers fourfold the minimum inhibitory concentration of the AgNPs templates toward Gram‐negative Pseudomonas aeruginosa (P. aeruginosa). The hybrid nanoparticles in eightfold‐lower concentration than the AgNPs inhibit 45% of the QS‐regulated virulence factors produced by the reporter Chromobacterium violaceum bacterial strain and reduce by 100% the P. aeruginosa biofilm formation. Moreover, the sequential deposition of antibacterial/antibiofilm active and biocompatible biopolymers onto the AgNPs allows the engineering of safe nanomaterials that do not affect the viability of human cells.     

Enhanced Antibacterial Activity of Nanocrystalline ZnO Due to Increased ROS‐Mediated Cell Injury

An innovative study aimed at understanding the influence of the particle size of ZnO (from the microscale down to the nanoscale) on its antibacterial effect is reported herein. The antibacterial activity of ZnO has been found to be due to a reaction of the ZnO surface with water. Electron‐spin resonance measurements reveal that aqueous suspensions of small nanoparticles of ZnO produce increased levels of reactive oxygen species, namely hydroxyl radicals. Interestingly, a remarkable enhancement of the oxidative stress, beyond the level yielded by the ZnO itself, is detected following the antibacterial treatment. Likewise, an exposure of bacteria to the small ZnO nanoparticles results in an increased cellular internalization of the nanoparticles and bacterial cell damage. An examination of the antibacterial effect is performed on two bacterial species: Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive). The nanocrystalline particles of ZnO are synthesized using ultrasonic irradiation, and the particle sizes are controlled using different solvents during the sonication process. Taken as a whole, it is apparent that the unique properties (i.e., small size and corresponding large specific surface area) of small nanometer‐scale ZnO particles impose several effects that govern its antibacterial action. These effects are size dependent and do not exist in the range of microscale particles.     

Antimicrobial Gallium‐Doped Phosphate‐Based Glasses

Novel quaternary gallium‐doped phosphate‐based glasses (1, 3, and 5 mol % Ga₂O₃) were synthesized using a conventional melt quenching technique. The bactericidal activities of the glasses were tested against both Gram‐negative (Escherichia coli and Pseudomonas aeruginosa) and Gram‐positive (Staphylococcus aureus, methicillin‐resistant Staphylococcus aureus, and Clostridium difficile) bacteria. Results of the solubility and ion release studies showed that these glass systems are unique for controlled delivery of Ga³⁺. ⁷¹Ga NMR measurements showed that the gallium is mostly octahedrally coordinated by oxygen atoms, whilst FTIR spectroscopy provided evidence for the presence of a small proportion of tetrahedral gallium in the samples with the highest gallium content. FTIR and Raman spectra also afford an insight into the correlation between the structure and the observed dissolution behavior via an understanding of the atomic‐scale network bonding characteristics. The results confirmed that the net bactericidal effect was due to Ga³⁺, and a concentration as low as 1 mol % Ga₂O₃ was sufficient to mount a potent antibacterial effect. The dearth of new antibiotics in development makes Ga³⁺ a potentially promising new therapeutic agent for pathogenic bacteria including MRSA and C. difficile.     

Eradicating Multidrug‐Resistant Bacteria Rapidly Using a Multi Functional g‐C3N4@ Bi2S3 Nanorod Heterojunction with or without Antibiotics

Wound infections caused by multidrug‐resistant (MDR) bacteria are hard to treat because of tolerance to existing antibiotics, repeated infection, and concomitant inflammation. Herein, zinc atom–doped g‐C₃N₄ and Bi₂S₃ nanorod heterojunctions (CN–Zn/BiS) are investigated for disinfection under near‐infrared light (NIR). The photocatalysis of CN–Zn/BiS is enhanced because of efficient charge separation during the interface electron field and increased oxygen adsorption capacity. Then, 99.2% antibacterial efficiency is shown toward methicillin‐resistant Staphylococcus aureus (MRSA) and 99.6% toward Escherichia coli under 10 min NIR irradiation. Meanwhile, a strategy for the combination of lapsed β‐lactam antibiotics with the photosensitizer CN–Zn/BiS is provided to kill MRSA by NIR without observable resistance, suggesting an approach to solve the problem of bacterial infection with NIR light penetrability and for exploiting new anti‐infection methods. The CN–Zn/BiS nanocomposite can also regulate genes and the inflammatory response through inflammatory factors (IL‐1β, IL‐6, TNF‐α, and iNOS) in vivo to accelerate tissue regeneration and thereby promote wound healing.     

Copper Clusters: An Effective Antibacterial for Eradicating Multidrug-Resistant Bacterial Infection In Vitro and In Vivo

Infections caused by multidrug-resistant (MDR) bacteria pose a threat to human health worldwide, making new effective antibacterial agents urgently desired. To date, it is still a great challenge to develop new antibiotics for MDR bacteria with clear antibacterial mechanisms. Herein, a novel alternative antibacterial copper clusters (CuCs) molecule is precisely synthesized utilizing an artificially designed theanine peptide. The prepared CuCs exhibit excellent broad-spectrum antibacterial activity in vitro, including gram-positive bacteria (methicillin-resistant Staphylococcus aureus [MRSA], Staphylococcus aureus, and Staphylococcus epidermidis) and gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The robust antibacterial effect is due to its ability to not only destroy the bacterial wall structure, but also regulate the ratio of GSH/GSSG by inhibiting the activity of glutathione reductase, thus causing the outbreak of reactive oxygen species and ultimately leading to bacterial death. In addition, in vivo studies demonstrate that CuCs can significantly rescue skin wound infections and sepsis in mice caused by MRSA, and has the same therapeutic efficacy as mupirocin ointment and first-line clinically anchored anti-MRSA drug vancomycin. Moreover, CuCs exhibit extremely low cytotoxicity to normal mammalian cells compared to silver and platinum clusters. With further development and optimization, CuCs has great potential as a new class of antibacterial agents to fight antibiotic-resistant pathogens.     

Shining Light on Multidrug-Resistant Bacterial Infections: Rational Design of Multifunctional Organosilver-Based AIEgen Probes as Light-Activated Theranostics for Combating Biofilms and Liver Abscesses

The intricate environment of biofilms provides a heaven for bacteria to escape antibiotic eradication, leading to persistent chronic infections. Therefore, it is urgently needed to develop effective therapies to combat biofilm-associated infections. To address this problem, a series of antimicrobial agents are designed and synthesized utilizing triphenylamine imidazole silver complexes ( TPIMS ). Due to the photoactivated release of Ag⁺ coupled with aggregation-induced emission (AIE) properties and efficient ¹O₂ generation, TPIMS exhibits excellent visual diagnostic capabilities and potent broad-spectrum antimicrobial activity, showing antimicrobial efficacy against both Gram (+) and Gram (−) bacteria. Additionally, TPIMS shows extraordinary antibacterial performance and biofilm resistance against methicillin-resistant Staphylococcus aureus (MRSA), with reduced potential for resistance thanks to the synergistic effect of phototoxicity and dark toxicity. Notably, among the TPIMS variants tested, TPIMS-8 has demonstrated exceptional curative ability against resistant bacterial biofilm infections in vivo with minimal side effects. Furthermore, it is applied to clinical samples from infected patients and the results indicated that TPIMS-8 is able to achieve excellent bacterial-specific detection and superior killing of drug-resistant bacteria even in complex systems, demonstrating its great potential for clinical applications. This study presents a promising foundation for the development of advanced antimicrobial therapeutics targeting multidrug-resistant bacteria and biofilm-associated infections.     

Multivalent Glycosheets for Double Light–Driven Therapy of Multidrug‐Resistant Bacteria on Wounds

With the evergrowing threat posed by multidrug resistance of bacteria, the development of effective antibacterial agents remains a global challenge. Infection with multidrug‐resistant bacteria in hospitals significantly impairs the healing of wounds caused by deep‐burn injuries or diabetic foot ulceration, leading to a high mortality rate among these patients. A multivalent glycosheet for the double light–driven therapy against multidrug‐resistant Pseudomonas aeruginosa (P. aeruginosa) infection on wounds is developed here. Galactose‐ and fucose‐based ligands are self‐assembled to form a glyco‐layer on the surface of thin‐layer molybdenum disulfide, producing the glycosheets capable of selectively localizing P. aeruginosa through multivalent carbohydrate–lectin interactions. The glycosheets loaded with antibiotics have proven applicable for: 1) near‐infrared‐light driven, in situ thermal release of antibiotics, increasing bacterial membrane permeability, and 2) white light–driven reactive‐oxygen‐species production to more thoroughly kill the bacteria. The targetability, together with the light sensibility, of the glycosheets enables a highly effective and optically controlled therapeutic regime for the healing of wounds infected by multidrug‐resistant as well as clinically isolated P. aeruginosa.     

Ag Nanoparticles Cluster with pH‐Triggered Reassembly in Targeting Antimicrobial Applications

Antibacterial efficiency can be effectively improved by applying targeting antibacterial materials and strategies. Herein, the successful synthesis of uniform pH‐responsive Ag nanoparticle clusters (AgNCs) is demonstrated, which can collapse and reassemble into nonuniform Ag NPs upon exposure to the acidic microenvironment of bacterial infections. This pH triggered reassembly contributes greatly to the improved antibacterial activities of AgNCs against both methicillin‐resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). The minimum inhibitory concentration and minimum bactericidal concentration against MRSA are as low as 4 and 32 µg mL^?1 (which are 8 and 32 µg mL^?1 for E. coli), respectively. In vivo skin wound healing experiments confirm AgNCs can serve as an effective wound dressing to accelerate the healing of MRSA infection. The development of responsive AgNCs offers new materials and strategies in targeting antibacterial applications.     

Quaternized Silicon Nanoparticles with Polarity‐Sensitive Fluorescence for Selectively Imaging and Killing Gram‐Positive Bacteria

With the emergence of antibiotic resistance, developing new antibiotics and therapies for combating bacterial infections is urgently needed. Herein, a series of quaternized fluorescent silicon nanoparticles (SiNPs) are facilely prepared by the covalent reaction between amine‐functionalized SiNPs and carboxyl‐containing N‐alkyl betaines. It is found that the bactericidal efficacy of these quaternized SiNPs increases with the length of the N‐alkyl chain, and SiNPs conjugated with N,N‐dimethyl‐N‐octadecylbetaine (BS‐18), abbreviated as SiNPs‐C₁₈, show the best antibacterial effect, whose minimum inhibitory concentrations for Gram‐positive bacteria are 1–2 μg mL^?1. In vivo tests further confirm that SiNPs‐C₁₈ have excellent antibacterial efficacy and greatly reduce bacterial load in the infectious sites. The SiNPs‐C₁₈ exhibit low cytotoxicity toward mammalian cells (including normal liver and lung cells, red blood cells, and macrophages), enabling them to be useful for clinical applications. Besides, the quaternized SiNPs exhibit polarity‐dependent fluorescence emission property and can selectively image Gram‐positive bacteria, thereby providing a simple method to successfully differentiate Gram‐positive and Gram‐negative bacteria. The present work represents the first example that successfully turns fluorescent SiNPs into metal‐free NP‐based antibiotics with simultaneous bacterial imaging and killing capability, which broadens the applications of fluorescent SiNPs and advances the development of novel antibacterial agents.     

Engineering Iron Oxide Hollow Nanospheres to Enhance Antimicrobial Property: Understanding the Cytotoxic Origin in Organic Rich Environment

Engineered magnetic iron oxide nanoparticles with surprisingly high antimicrobial activity and excellent safety profiles to mammalian cell lines have been developed. Hematite hollow nanospheres (HNSs) are prepared by a facile hard templating method; reduction of hematite HNSs by H₂ leads to magnetite HNSs. The antimicrobial activity of magnetite HNSs towards Gram negative (Escherichia coli) and Gram positive (Staphylococcus epidermidis) bacteria is evaluated against hematite HNSs and conventional magnetite (C‐magnetite; diameter <50 nm). Superior antibacterial performance is observed for magnetite HNSs towards both E. coli and S. epidermidis over hematite HNSs and C‐magnetite. The origin of the antimicrobial activity of magnetite HNSs is the high leaching of iron ions in the presence of microorganisms, which leads to high generation of reactive oxygen species. Magnetite HNSs allow multiple‐fold increase in the generation of soluble iron ions over hematite HNSs and C‐magnetite, showing that control over both the composition and nanostructure is crucial to tune the antimicrobial activity of iron oxides. Based on the current findings, magnetic HNSs show promising potential antimicrobial applications.     

Bottom‐Up Tailoring of Plasmonic Nanopeapods Making Use of the Periodical Topography of Carbon Nanocoil Templates

Au nanoparticle chains embedded in helical Al₂O₃ nanotubes (“nanopeapods”) are synthesized by annealing carbon nanocoils coated with Au by sputtering and Al₂O₃ by atomic layer deposition. Regular spacing between nanoparticles with a sharp size distribution is achieved by fragmentation of the Au coating in agreement with the pitch of the nanocoils arising from three‐dimensional periodical topography of the carbon nanocoil templates. A strong plasmonic resonance behavior of the fabricated nanopeapods manifests itself in confocal laser scanning microscopy by a clear polarization contrast at red wavelengths, which is absent in the blue. Numerical simulations confirm an incisive resonance enhancement for longitudinal polarization and suggest the nanopeapods as promising candidates for highly efficient, ultrathin waveguides. The waveguiding properties of the nanopeapods are investigated by electron energy‐loss spectroscopy and energy‐filtered TEM imaging.     

Construction of Chitosan‐Based Hydrogel Incorporated with Antimonene Nanosheets for Rapid Capture and Elimination of Bacteria

To elaborately construct a novel and efficient photothermal antibacterial nanoplatform is a promising strategy for treating bacterial wound infections. In this work, a composite hydrogel (CS/AM NSs hydrogel) with outstanding antibacterial ability is constructed by incorporating antimonene nanosheets (AM NSs) with extraordinary photothermal properties into the network structure of chitosan (CS). When cultured with bacteria, the CS/AM NSs hydrogel can gather bacteria on the surface through the interaction of CS with the bacterial cell membrane. Subsequently, the intrinsic bactericidal property of CS will kill some of the bacteria. After the introduction of near‐infrared laser, the AM NSs effectively convert light energy into localized heat to eliminate residual bacteria. By virtue of the synergistic action between the capture effect of CS and the photothermal effect of AM NSs, the CS/AM NSs hydrogel shows predominant antibacterial behavior against Escherichia coli and Staphylococcus aureus. In vitro assay and in vivo tests of infected full‐thickness defect wound healing confirm the satisfactory biocompatibility and antibacterial ability. Overall, this work reveals that the CS/AM NSs hydrogel holds great potential as a broad‐spectrum antibacterial wound dressing for treating bacteria‐infected wounds. Additionally, this is the first report of the application of AM NSs in the field of antibacterial treatment.     

Synergistic Antimicrobial Capability of Magnetically Oriented Graphene Oxide Conjugated with Gold Nanoclusters

Bacterial resistance toward antibiotics has been a worldwide threat; one way to fight against the resistance is to develop a multimechanism antibacterial agent to achieve synergistic performance. Graphene oxide (GO) is an emerging antibacterial agent combining multiple mechanisms (physical insertion and chemical disruption), and its rich functional groups enable the complexation/conjugation of nanomaterials to further improve antibacterial performance. Herein, a synergistic antimicrobial agent is established through the assembly of paramagnetic holmium ions and gold nanoclusters (AuNCs) onto GO nanosheets. The assembled nanosheets can be vertically aligned under weak and practical magnetic fields (<0.5 T ), providing high‐density sharp edges with preferential orientation to effectively pierce the bacterial membrane. Also, the conjugated AuNCs are efficiently delivered into bacteria to induce high oxidative stress, which strongly disturbs bacterial metabolism, leading to the death of both Gram‐positive and Gram‐negative bacteria. The antibacterial agent uses both physical (via oriented GO) and chemical (via GO and AuNCs) mechanisms to achieve synergistic antimicrobial performance with low IC₅₀ values of 9.8 µg mL^?1 on the basis of GO and 0.39 × 10^?6 m on the basis of AuNCs. This multicomponent agent with dual antimicrobial mechanisms is expected to be a promising multifunctional‐antimicrobial agent with high biosafety.     

Physical Double‐Network Hydrogel Adhesives with Rapid Shape Adaptability,Fast Self‐Healing,Antioxidant and NIR/pH Stimulus‐Responsiveness for Multidrug‐Resistant Bacterial Infection and Removable Wound Dressing

Developing physical double‐network (DN) removable hydrogel adhesives with both high healing efficiency and photothermal antibacterial activities to cope with multidrug‐resistant bacterial infection, wound closure, and wound healing remains an ongoing challenge. An injectable physical DN self‐healing hydrogel adhesive under physiological conditions is designed to treat multidrug‐resistant bacteria infection and full‐thickness skin incision/defect repair. The hydrogel adhesive consists of catechol–Fe³⁺ coordination cross‐linked poly(glycerol sebacate)‐co‐poly(ethylene glycol)‐g‐catechol and quadruple hydrogen bonding cross‐linked ureido‐pyrimidinone modified gelatin. It possesses excellent anti‐oxidation, NIR/pH responsiveness, and shape adaptation. Additionally, the hydrogel presents rapid self‐healing, good tissue adhesion, degradability, photothermal antibacterial activity, and NIR irradiation and/or acidic solution washing‐assisted removability. In vivo experiments prove that the hydrogels have good hemostasis of skin trauma and high killing ratio for methicillin‐resistant staphylococcus aureus (MRSA) and achieve better wound closure and healing of skin incision than medical glue and surgical suture. In particular, they can significantly promote full‐thickness skin defect wound healing by regulating inflammation, accelerating collagen deposition, promoting granulation tissue formation, and vascularization. These on‐demand dissolvable and antioxidant physical double‐network hydrogel adhesives are excellent multifunctional dressings for treating in vivo MRSA infection, wound closure, and wound healing.     

Copper‐Based Nanostructured Coatings on Natural Cellulose: Nanocomposites Exhibiting Rapid and Efficient Inhibition of a Multi‐Drug Resistant Wound Pathogen,A. baumannii,and Mammalian Cell Biocompatibility In Vitro

This paper describes a layer‐by‐layer (LBL) electrostatic self‐assembly process for fabricating highly efficient antimicrobial nanocoatings on a natural cellulose substrate. The composite materials comprise a chemically modified cotton substrate and a layer of sub‐5 nm copper‐based nanoparticles. The LBL process involves a chemical preconditioning step to impart high negative surface charge on the cotton substrate for chelation controlled binding of cupric ions (Cu²⁺), followed by chemical reduction to yield nanostructured coatings on cotton fibers. These model wound dressings exhibit rapid and efficient killing of a multidrug resistant bacterial wound pathogen, A. baumannii, where an 8‐log reduction in bacterial growth can be achieved in as little as 10 min of contact. Comparative silver‐based nanocoated wound dressings–a more conventional antimicrobial composite material–exhibit much lower antimicrobial efficiencies; a 5‐log reduction in A. baumannii growth is possible after 24 h exposure times to silver nanoparticle‐coated cotton substrates. The copper nanoparticle–cotton composites described herein also resist leaching of copper species in the presence of buffer, and exhibit an order of magnitude higher killing efficiency using 20 times less total metal when compared to tests using soluble Cu²⁺. Together these data suggest that copper‐based nanoparticle‐coated cotton materials have facile antimicrobial properties in the presence of A. baumannii through a process that may be associated with contact killing, and not simply due to enhanced release of metal ion. The biocompatibility of these copper‐cotton composites toward embryonic fibroblast stem cells in vitro suggests their potential as a new paradigm in metal‐based wound care and combating pathogenic bacterial infections.     

Controlled Release of LL‐37‐Derived Synthetic Antimicrobial and Anti‐Biofilm Peptides SAAP‐145 and SAAP‐276 Prevents Experimental Biomaterial‐Associated Staphylococcus aureus Infection

The present study aims to develop an implant coating releasing novel antimicrobial agents to prevent biomaterial‐associated infections. The LL‐37‐derived synthetic antimicrobial and anti‐biofilm peptides (SAAP)‐145 and SAAP‐276 exhibit potent bactericidal and anti‐biofilm activities against clinical and multidrug‐resistant Staphylococcus aureus strains by rapid membrane permeabilization, without inducing resistance. Injection of SAAP‐145, but not SAAP‐276, along subcutaneous implants in mice reduces S. aureus implant colonization by approximately 2 log, but does not reduce bacterial numbers in surrounding tissue. To improve their efficacy, SAAP‐145 and SAAP‐276 are incorporated in a polymer–lipid encapsulation matrix (PLEX) coating, providing a constant release of 0.6% daily up to 30 d after an initial burst release of >50%. In a murine model for biomaterial‐associated infection, SAAP‐145‐PLEX and SAAP‐276‐PLEX coatings significantly reduce the number of culture positive implants and show ≥3.5 and ≥1.5 log lower S. aureus implant and tissue colonization, respectively. Interestingly, these peptide coatings are also highly effective against multidrug‐resistant S. aureus, both reducing implant colonization by ≥2 log. SAAP‐276‐PLEX additionally reduces tissue colonization by 1 log. Together, the peptide‐releasing PLEX coatings hold promise for further development as an alternative to coatings releasing conventional antibiotics to prevent biomaterial‐associated infections.     

Bamboo-Like Nanozyme Based on Nitrogen-Doped Carbon Nanotubes Encapsulating Cobalt Nanoparticles for Wound Antibacterial Applications

In this paper, an artificial nanozyme with efficient oxidase-mimicking activity is developed to investigate antibacterial performance. The bamboo-like nitrogen-doped carbon nanotubes encapsulating cobalt nanoparticles (N-CNTs@Co) are synthesized by pyrolysis of cobalt cyanide cobalt at high temperature. It is found that the oxidase-mimicking activity of N-CNTs@Co is higher than that of iron-centered nanomaterials synthesized by pyrolysis of prussian blue under the same conditions, confirming that the oxidase-mimicking activity is not only related to the active center, but also closely related to its morphology. In addition, the oxidase-mimicking activity of N-CNTs@Co is 12.1 times higher than that of the most reported CeO₂. N-CNTs@Co can catalyze oxygen to produce a large number of reactive oxygen species (ROS) under acidic conditions, resulting in a favorable antibacterial effect against two representative bacteria, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli). Because the bacterial membrane is damaged by the attack of ROS, the DNA is degraded, eventually causing the bacteria to die. Antibacterial experiments last for 20 days, nevertheless, S. aureus and E. coli do not develop resistance to N-CNTs@Co. The experiments of wound healing in vivo further confirm the high antibacterial efficiency of N-CNTs@Co.