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.     

Treatment of Superbug Infection through a Membrane-Disruption and Immune-Regulation Cascade Effect Based on Supramolecular Peptide Hydrogels

Infections from antimicrobial resistant pathogens have been considered as lethal threats to human health if antibiotic treatments become ineffective. Antimicrobial peptides (AMPs) show broad-spectrum antimicrobial activity against resistant strains via a membrane disruptive mechanism without developing further resistance and are promising candidates to combat resistant microbes. However, currently developed small molecular AMPs are limited by weak antimicrobial efficacy and potential cytotoxicity. Herein, an antimicrobial AMP hydrogel based on supramolecular self-assembly is developed. The hydrogel shows strong antimicrobial activity and high potency against antimicrobial resistant microbes. It also possesses high cytocompatibility and immunoregulative activity. The synergistic effects lead to its significant healing of the skin abscess disease induced by the methicillin-resistant Staphylococcus aureus infection. This study not only sheds light on the design strategies and immune-related antimicrobial actions of supramolecular AMP hydrogels, but also advances the development of self-assembly peptide platform to fight against antimicrobial resistant infections.     

Design and Engineering of Amyloid Aggregation-Prone Fragments and Their Antimicrobial Conjugates with Multi-Target Functionality

Amyloid aggregation and microbial infection are considered major risk factors for neurodegeneration and neuroinflammation in protein misfolding diseases (PMDs), including Alzheimer's disease (AD) and Type 2 diabetes (T2D). However, current amyloid inhibitors are mostly limited to single-target prevention strategies against specific amyloid proteins or pathogenic microbes, leading to no success for clinical cures of PMDs. Here, a step-by-step strategy to design new, multi-target amyloid aggregation-prone fragments (APFs) and their APFs antimicrobial agent conjugates is proposed, capable of achieving the stepwise improved multifunctionality of amyloid inhibition, antimicrobial activity, and amyloid imaging. The two APFs of KLVFF from Aβ (associated with AD) and FGAIL from hIAPP (associated with T2D) with β-structure-forming property are selected and used as building block to construct a hybrid KLVFFGAIL peptide (K9) and a K9-AMC (7-amino-4-methylcoumarin) fluorescence conjugate, both of which have demonstrated the improved, multiple-target, sequence-independent functions to inhibit the aggregation of both Aβ and hIAPP, reduce both Aβ- and hIAPP-induced cell toxicity, prevent different microbial growth, and introduce fluorescence images for amyloid fibrils. The sequence-independent amyloid inhibition function of K9 and K9-AMC mainly stems from their cross-interactions with amyloid proteins via β-structure and aromatic interactions. This work provides a proof-of-concept example to not only explore a new family of APFs as antimicrobial and anti-amyloid drugs for the therapeutic potential of PMDs, but also better understand the pathological links between protein aggregation and microbial infection in PMDs along the gut–brain axis.     

Multifunctional Nano‐Biointerfaces: Cytocompatible Antimicrobial Nanocarriers from Stabilizer‐Free Cubosomes

The rational design of alternative antimicrobial materials with reduced toxicity toward mammalian cells is highly desired due to the growing occurrence of bacteria resistant to conventional antibiotics. A promising approach is the design of lipid‐based antimicrobial nanocarriers. However, most of the commonly used polymer‐stabilized nanocarriers are cytotoxic. Herein, the design of a novel, stabilizer‐free nanocarrier for the human cathelicidin derived antimicrobial peptide LL‐37 that is cytocompatible and promotes cell proliferation for improved wound healing is reported. The nanocarrier is formed through the spontaneous integration of LL‐37 into novel, stabilizer‐free glycerol mono‐oleate (GMO)‐based cubosomes. Transformations in the internal structure of the cubosomes from Pn3m to Im3m‐type and eventually their transition into small vesicles and spherical micelles are demonstrated upon the encapsulation of LL‐37 into their internal bicontinuous cubic structure using small angle X‐ray scattering, cryogenic transmission electron microscopy, and light scattering techniques. Additional in vitro biological assays show the antimicrobial activity of the stabilizer‐free nano‐objects on a variety of bacteria strains, their cytocompatibility, and cell‐proliferation enhancing effect. The results outline a promising strategy for the comprehensive design of antimicrobial, cytocompatible lipid nanocarriers for the protection and delivery of bioactive molecules with potential for application as advanced wound healing materials.     

Synergistic Oxidative Damage with Gene Therapy Potentiates Targeted Sterilization of Broad-Spectrum Microorganisms

Nanoparticle-based approaches addressed the barriers to antibiotic resistance faced by traditional antimicrobial agents. However, nanotherapies against multibacterial infections still suffered from the lack of broad-spectrum targeting ability and the mono-inhibition pathway. In this study, a multimodality therapeutic nanoplatform (denoted as Asza) is introduced, which combines specific recognition, synergistic oxidative damage, and gene therapy, to effectively inhibit the emergence of bacterial resistance, achieving broad-spectrum sterilization activity against two Gram-positive (B. subt, S. epider) and two Gram-negative bacteria (E. coli, E. aero). In addition to the oxidative damage generated from gold nanoclusters, DNA aptamer, and CRISPR-Cas modules are combined in the Asza to recognize multiple bacteria and cleave the ftsz gene with high specificity, allowing precision treatment of multibacterial infections without damaging surrounding healthy cells. Furthermore, multimodal antimicrobial strategies can reduce the risk of the generation of bacterial resistance to single-modality therapy and significantly boost the efficiency of antibacterial therapy. This study offers a promising approach to advance the applications of nanomaterials in clinical antimicrobial therapy.     

A Shape‐Adaptive,Antibacterial‐Coating of Immobilized Quaternary‐Ammonium Compounds Tethered on Hyperbranched Polyurea and its Mechanism of Action

Quaternary‐ammonium‐compounds are potent cationic antimicrobials used in everyday consumer products. Surface‐immobilized, quaternary‐ammonium‐compounds create an antimicrobial contact‐killing coating. We describe the preparation of a shape‐adaptive, contact‐killing coating by tethering quaternary‐ammonium‐compounds onto hyperbranched polyurea coatings, able to kill adhering bacteria by partially enveloping them. Even after extensive washing, coatings caused high contact‐killing of Staphylococcus epidermidis, both in culture‐based assays and through confocal‐laser‐scanning‐microscopic examination of the membrane‐damage of adhering bacteria. In culture‐based assays, at a challenge of 1600 CFU/cm², contact‐killing was >99.99%. The working‐mechanism of dissolved quaternary‐ammonium‐compounds is based on their interdigitation in bacterial membranes, but it is difficult to envisage how immobilized quaternary‐ammonium‐molecules can exert such a mechanism of action. Staphylococcal adhesion forces to hyperbranched quaternary‐ammonium coatings were extremely high, indicating that quaternary‐ammonium‐molecules on hyperbranched polyurea partially envelope adhering bacteria upon contact. These lethally strong adhesion forces upon adhering bacteria then cause removal of membrane lipids and eventually lead to bacterial death.     

Self‐Defensive Biomaterial Coating Against Bacteria and Yeasts: Polysaccharide Multilayer Film with Embedded Antimicrobial Peptide

Prevention of pathogen colonization of medical implants is a major medical and financial issue since infection by microorganisms constitutes one of the most serious complications after surgery or critical care. Immobilization of antimicrobial molecules on biomaterials surfaces is an efficient approach to prevent biofilm formation. Herein, the first self‐defensive coating against both bacteria and yeasts is reported, where the release of the antimicrobial peptide is triggered by enzymatic degradation of the film due to the pathogens themselves. Biocompatible and biodegradable polysaccharide multilayer films based on functionalized hyaluronic acid by cateslytin (CTL), an endogenous host‐defensive antimicrobial peptide, and chitosan (HA‐CTL‐C/CHI) are deposited on a planar surface with the aim of designing both antibacterial and antifungal coating. After 24 h of incubation, HA‐CTL‐C/CHI films fully inhibit the development of Gram‐positive Staphylococcus aureus bacteria and Candida albicans yeasts, which are common and virulent pathogens agents encountered in care‐associated diseases. Hyaluronidase, secreted by the pathogens, leads to the film degradation and the antimicrobial action of the peptide. Furthermore, the limited fibroblasts adhesion, without cytotoxicity, on HA‐CTL‐C/CHI films highlights a medically relevant application to prevent infections on catheters or tracheal tubes where fibrous tissue encapsulation is undesirable.     

In Situ Enzyme-Induced Self-Assembly of Antimicrobial-Antioxidative Peptides to Promote Wound Healing

Antimicrobial peptides (AMPs) with dual intrinsic antibacterial and antioxidative functions have emerged as promising choice to cure infected wound. However, the most widely applied approach to endow AMPs with antioxidative function is to combine with antioxidative moieties, which may affect the spatial structure and physiological stability of AMPs. Herein, a new type of AMPs with inherent desired stability, antibacterial activity, and reactive oxygen species (ROS) scavenging is developed to effectively heal the infected wound. This formulation is in situ formed at wound site by tyrosinase-triggered oxidation and self-assembly of lyophilized antimicrobial peptide Trp-Arg-Trp-Arg-Trp-Tyr, providing enhanced stability and a fourfold and sevenfold increasement in antibacterial efficiency against E. coli and S. aureus compared to peptide monomers. The antimicrobial peptide is first oxidized and then assembled into nanoparticles. The melanin-like structure has been demonstrated with efficient antioxidant properties, and the experimental data show that peptide nanoparticles to scavenge superoxide radicals, hydroxyl radicals, and H₂O₂. In vivo experiments confirmed that peptide nanoparticles effectively heal infected wounds and obviously reduce ROS. Overall, the research provides a new approach to formulating antimicrobial peptides to treat wound with high healing efficiency.     

Reactive Oxygen Species-Activated CO Versatile Nanomedicine with Innate Gut Immune and Microbiome Remodeling Effects for Treating Inflammatory Bowel Disease

Abnormal activation of the gut mucosal immune system and a highly dysregulated gut microbiota play essential roles in the progression of inflammatory bowel disease (IBD). The clinical treatment of IBD remains highly challenging, with first-line drugs showing limited efficacy and significant side effects. A reactive oxygen species (ROS)-activated CO versatile nanomedicine (CMPs) capable of remodeling the gut immune-microbiota microenvironment via potent anti-oxidant, anti-inflammatory, and antimicrobial effects is developed. CORM-401-loaded mannose-modified peptide dendrimer nanogel: CMPs preferentially congregate on the surface of damaged colon mucosa after rectal administration and are subsequently internalized by activated immune cells. CORM-401 can release numerous CO molecules in response to high ROS levels in cells and at the site of IBD, resulting in multiple therapeutic effects. In vitro and in vivo studies have demonstrated that CMPs scavenge ROS, suppress inflammatory responses, eliminate pathogens, and alleviate colitis in mouse models. RNA sequencing reveals that CMPs successfully remodel gut mucosal immune homeostasis by scavenging ROS, inhibiting NF-κB/p38MAPK, activating PI3K-Akt, and inhibiting HIF-1-induced glycolysis. 16S ribosomal RNA sequencing shows that CMPs can remodel the gut flora composition by restraining detrimental bacteria and augmenting beneficial bacteria. This study develops a promising and versatile nanomedicine for the management of IBD.     

Short Synthetic β‐Sheet Forming Peptide Amphiphiles as Broad Spectrum Antimicrobials with Antibiofilm and Endotoxin Neutralizing Capabilities

Although naturally occurring membrane lytic antimicrobial peptides (AMPs) and their analogs hold enormous promise for antibiotics‐resistant infectious disease therapies, significant challenges such as systemic toxicities, long peptide sequences, poor understanding of structure‐activity relationships, and the potential for compromising innate host defense immunity have greatly limited their clinical applicability. To improve the clinical potential of AMPs, a facile approach is adopted to design a series of short synthetic β‐sheet folding peptide amphiphiles comprised of short recurring (X₁Y₁X₂Y₂)_n‐NH₂ sequences, where X₁ and X₂: hydrophobic residues (Val, Ile, Phe or Trp), Y₁ and Y₂: cationic residues (Arg or Lys), and n: number of repeat units; with systematic variations to the cationic and hydrophobic residues to obtain optimized AMP sequences bearing minimal resemblance to naturally occurring sequences. The designed β‐sheet forming peptides exhibit broad spectrum antimicrobial activities against various clinically relevant microorganisms, including Gram‐positive Staphylococcus epidermidis and Staphylococcus aureus, Gram‐negative Escherichia coli and Pseudomonas aeruginosa, and yeast Candida albicans, with excellent selectivities for microbial membranes. Optimal synthetic peptides with n = 2 and n = 3 repeat units, i.e., (IRIK)₂‐NH₂ and (IRVK)₃‐NH₂, efficiently inhibit sessile biofilm bacteria growth leading to biomass reduction. Additionally, sequences with n = 3 repeat units effectively neutralize endotoxins while causing minimal cytotoxicities. Taken together, these findings clearly demonstrate that the rationally designed synthetic β‐sheet folding peptides are highly selective, non‐cytotoxic at antimicrobial levels and have tremendous potential for use as broad spectrum antimicrobial agents to overcome multidrug resistance in a wide range of localized, systemic, or external therapeutic applications.     

Self‐Assembly of Antimicrobial Peptides on Gold Nanodots: Against Multidrug‐Resistant Bacteria and Wound‐Healing Application

Photoluminescent gold nanodots (Au NDs) are prepared via etching and codeposition of hybridized ligands, an antimicrobial peptide (surfactin; SFT), and 1‐dodecanethiol (DT), on gold nanoparticles (≈3.2 nm). As‐prepared ultrasmall SFT/DT–Au NDs (size ≈2.5 nm) are a highly efficient antimicrobial agent. The photoluminescence properties and stability as well as the antimicrobial activity of SFT/DT–Au NDs are highly dependent on the density of SFT on Au NDs. Relative to SFT, SFT/DT–Au NDs exhibit greater antimicrobial activity, not only to nonmultidrug‐resistant bacteria but also to the multidrug‐resistant bacteria. The minimal inhibitory concentration values of SFT/DT–Au NDs are much lower (>80‐fold) than that of SFT. The antimicrobial activity of SFT/DT–Au NDs is mainly due to the synergistic effect of SFT and DT–Au NDs on the disruption of the bacterial membrane. In vitro cytotoxicity and hemolysis analyses have revealed superior biocompatibility of SFT/DT–Au NDs than that of SFT. Moreover, in vivo methicillin‐resistant S. aureus–infected wound healing studies in rats show faster healing, better epithelialization, and are more efficient in the production of collagen fibers when SFT/DT–Au NDs are used as a dressing material. This study suggests that the SFT/DT–Au NDs are a promising antimicrobial candidate for preclinical applications in treating wounds and skin infections.     

Bacterium‐Templated Polymer for Self‐Selective Ablation of Multidrug‐Resistant Bacteria

The recognition and inactivation of specific pathogenic bacteria remain an enormous scientific challenge and an important therapeutic goal. Therefore, materials that can selectively target and kill specific pathogenic bacteria, without harming beneficial strains are highly desirable. Here, a material platform is reported that exploits bacteria as a template to synthesize polymers with aggregation‐induced emission (AIE) characteristic by copper‐catalyzed atom transfer radical polymerization for self‐selective killing of the bacteria that templates them with no antimicrobial resistance. The bacteria‐templated polymers show very weak fluorescence in aqueous media, however, the fluorescence is turned on upon recognition of the bacteria used as the template to synthesize the polymer even at a low concentration of 600 ng mL^?1. Moreover, the incorporated AIE fluorogens (AIEgens) can act as an efficient photosensitizer for reactive oxygen species (ROS) generation after bacteria surface binding, which endows the templated polymers with the capability for selective bacterial killing. The bacterium‐templated synthesis is generally applicable to a wide range of bacteria, including clinically isolated multidrug‐resistant bacterial strains. It is envisioned that the bacterium‐templated method provides a new strategy for bacteria‐specific diagnostic and therapeutic applications.     

Silver Nanoparticles Deposited Layered Double Hydroxide Nanoporous Coatings with Excellent Antimicrobial Activities

Simple and facile processes to produce silver nanoparticles deposited layered double hydroxide (Ag‐LDH) coatings are reported. High quality nanoporous LDH coatings are obtained under hydrothermal conditions via an improved in situ growth method by immersing the substrates in LDH suspensions after removal of free electrolytes. Different types of substrates including metal, ceramics, and glass with planar and non‐planar surfaces can all be coated with the oriented LDH films with strong adhesion. The pore size can be easily tuned by changing the metal:NaOH ratio during the precipiation process of LDH precursors. In the presence of LDH coatings, silver ions can be readily reduced to metallic silver nanoparticles (Ag NPs) in aqueous solutions. The resulting Ag NPs are incorporated evenly on LDH surface. The Ag‐LDH coating exhibits excellent and durable antimicrobial activities against both Gram‐negative (E. Coli and P. Aeruginosa) and Gram‐positive (B. Subtilis and S. Aureus) bacteria. Even at the 4th recycled use, more than 99% of all types of bacteria can be killed. Moreover, the Ag‐LDH coating can also effectively inhibit the bacterial growth and prevent the biofilm formation in the nutrient solutions. These newly designed Ag‐LDH coatings may offer a promising antimicrobial solution for clinical and environmental applications.     

Molecular Evolution of Acceptor–Donor–Acceptor-type Conjugated Oligomer Nanoparticles for Efficient Photothermal Antimicrobial Therapy

Infectious diseases (such as wound infections) caused by pathogenic microorganisms can lead to serious consequences and even threaten life. The emergence of drug-resistant bacteria has severely prevented the validity of traditional antibiotics. Therefore, developing novel antimicrobial strategies without drug-resistant holds great promise for maximizing efficacy and minimizing the risk of drug-resistance of resistant bacterial infections. Herein, near-infrared (NIR)-absorbing A–D–A type conjugated oligomers with a tunable backbone are designed and synthesized for regulating their photothermal conversion. After being assembled into nanoparticles, the conjugated oligomer CP-F8P nanoparticles (NPs) containing a strong electron-donating component show the strongest photothermal conversion efficiency of 81.6%. The low concentration of CP-F8P NPs receive over 99% of antimicrobial efficiency against Amp^r E. coli, S. aureus, and C. albicans upon NIR irradiation, and the phototherapy treatment of CP-F8P NPs can effectively promote wound healing in diabetic mice with good biocompatibility. This work provides ideas for the design of efficient NIR-activated antimicrobial reagents against drug-resistant microbial infections.     

High‐Performance Photodetectors Based on Organometal Halide Perovskite Nanonets

The booming development of organometal halide perovskites has prompted the exploration of morphology‐engineering strategies to improve their performance in optoelectronic applications. However, the preparation of optoelectronic devices of perovskites with complex architectures and desirable properties is still highly challenging. Herein, novel CH₃NH₃PbI₃ nanonets and nanobowl arrays are fabricated facilely by using monolayer colloidal crystal (MCC) templates on different substrates. Specifically, highly ordered CH₃NH₃PbI₃ nanonets with high crystallinity are fabricated on a variety of flat substrates, whereas regular CH₃NH₃PbI₃ nanobowl arrays are produced on a coarse substrate. The photodetection performance of the CH₃NH₃PbI₃ nanonet‐based photodetectors is significantly enhanced compared to the photodetectors based on conventional CH₃NH₃PbI₃ compact films. Particularly, the nanonet photodetectors exhibit a high responsivity (10.33 A W^?1 under 700 nm monochromatic light), which is six times higher than that for the compact CH₃NH₃PbI₃ film devices, fast response speed, and good stability. Owing to the two‐dimensional arrayed structure, the CH₃NH₃PbI₃ nanonets exhibit an enhanced light harvesting ability and offer direct carrier transport pathways. Meanwhile, the MCC template brings about larger grain sizes with enhanced crystallinity. Furthermore, the perovskite nanonets can be formed on a flexible polyethylene terephthalate substrate for the fabrication of promising flexible nanonet photodetectors.     

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.     

Multifunctional and Stimuli‐Responsive Polydopamine Nanoparticle‐Based Platform for Targeted Antimicrobial Applications

The rising threat of antimicrobial resistance is a crisis of a global scale. If not addressed, it can lead to health care system problems worldwide. This warrants alternative therapeutic approaches whose mechanism of action starkly differs from conventional antibiotic‐based therapies. Here, a multifunctional and stimuli‐responsive (NIR laser‐activated) antimicrobial platform is engineered by combining the intrinsic photothermal capability and excellent biocompatibility of polydopamine nanoparticles (PdNPs), with the membrane targeting and lytic activities of an antimicrobial peptide (AMP). The resulting PdNP‐AMP nanosystem can specifically target and destabilize the mechanical integrity of the outer membrane of Escherichia coli, as measured using the atomic force microscope. Furthermore, the laser‐induced nano‐localized heating of PdNP—in close proximity to the already compromised bacterial envelope—induces further membrane damage. This results in a more efficient, laser‐activated, bacterial killing action of PdNP‐AMP. The antimicrobial platform developed in this work is shown to be effective against a drug‐resistant E. coli. Overall, this work highlights the advantage and strength of combining multiple and coordinated biocidal mechanisms, into one nanomaterial‐based system and its promise in treating drug‐resistant pathogens.     

Antimicrobial Peptide Functionalized Conductive Nanowire Array Electrode as a Promising Candidate for Bacterial Environment Application

Conductive polymer electrodes are widely used for electrical signal detection owing to their unique mechanical, redox, and impedance characteristics. However, the performance of electrodes is compromised due to the interference of adhered bacteria and most of the scientists have not taken the microbial environment into consideration during electrode design. Here, a facile approach to construct antimicrobial peptide (AMP) functionalized polypyrrole nanowire array conductive electrodes (PNW‐AMP) is reported. Instead of compromising the electrochemical properties as the other antibacterial agents do, the PNW‐AMP electrodes exhibit excellent redox and low interfacial impedance properties. More importantly, the PNW‐AMP can eliminate bacterial adhesion and maintain electrochemical stability simultaneously in the microbial microenvironment for a long time. The antibacterial rate of the PNW‐AMP electrode reaches 95.8% after exposing the electrode to air for one month, while the charge transfer resistance ( R_ct) value only increases by 9% at a bacterium (Escherichia. Coli ) concentration of 1 × 10⁴ colony forming unit (CFU) mL^?1. This research makes it possible to construct highly stable conductive polymer electrodes for bacterial environment electrical signal detection.     

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.     

General Fabrication of Monolayer SnO2 Nanonets for High‐Performance Ultraviolet Photodetectors

A facile approach for the fabrication of monolayer SnO₂ nanonet is presented using polymer colloid monolayer nanofilms from oil–water interface self‐assembly as sacrificial templates. The hole size of the nanonets can be adjusted easily by the mean diameter of polymer colloidal spheres. This method can be extended to the fabrication of a series of monolayer nanonets of semiconducting oxides such as TiO₂, ZnO, and CeO₂. Furthermore, the first photoresponse nanodevice based on monolayer SnO₂ nanonet is fabricated. This device presents ultrahigh photocurrent and sensitivity, excellent stability, and reproducibility.