High Antibacterial Efficiency Research Articles

Aerosol inhalation delivery of cefazolin in mice: Pharmacokinetic measurements and antibacterial effect

Aerosol inhalation delivery of cefazolin, a broad-spectrum first-generation cephalosporin antibiotic, was investigated. Inhalation system based on ultrasonic nebulizer was developed for the generation of dry cefazolin aerosol within mean particle diameter range 0.5–3.0 μm and mass concentration 0.01–3 μg/cm3. Pharmacokinetic measurements were carried out for the aerosolized form of cefazolin delivered in mice using nose-only chamber. Cefazolin concentrations in blood serum and in the lungs of mice were measured as a function of time by means of high performance liquid chromatography. Body-delivered dose depending on particle size, concentration and inhalation time as well as other pharmacokinetic parameters were determined. The antibacterial effect of aerosolized cefazolin was assessed through the aerosol inhalation treatment of mice infected with Klebsiella pneumoniae. Survival rate for infected mice after the treatment with cefazolin aerosol demonstrated high antibacterial efficiency of the inhalation delivery of cefazolin in comparison with intraperitoneal delivery.

Exopolysaccharide production with high antibacterial efficiency from Lentinus edodes using sheep wool protein hydrolysate

Exopolysaccharide production with high antibacterial efficiency from Lentinus edodes using sheep wool protein hydrolysate

From Unimolecular Template to Silver Nanocrystal Clusters: An Effective Strategy to Balance Antibacterial Activity and Cytotoxicity.

Silver nanomaterials have attracted a great deal of interest due to their broad-spectrum antimicrobial activity. However, it is still challenging to balance the high antibacterial efficiency with low damage to biological cells of silver nanostructures, especially when the diameter decreases to less than 10 nm. Here, we developed a new type of Ag nanohybrid material via a unimolecular micelle template method, which presents amazing antibacterial activities and almost noncytotoxicity. First, water-soluble multiarm star-shaped brushlike copolymer α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 was precisely synthesized and its micelle behavior in different solvents was revealed. Then, nanocrystal clusters assembled by Ag grains (Ag@Template NCs) were prepared through an in situ redox route using the unimolecular micelle of α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 as the soft template, AgNO3 as a precursor, and tetrabutylammonium borohydride (TBAB) as the reducing agent. The overall size of the achieved Ag@Template NCs is controlled by the template structure at around 40 nm (Dh in DMF), and the size of the Ag grain can be easily regulated from ∼1 to ∼5 nm by adjusting the feeding ratio of AgNO3/acrylic acid (AA) units in the template from 1:10 to 1:1. Benefitting from the structural design of the template, all Ag@Template NCs prepared here exhibit excellent dispersibility and chemical stability in different aqueous environments (neutral, pH = 5.5, and 0.9% NaCl physiological saline solution), which play a crucial role in the long-term storage and potential application in a complex physiological environment. The antibacterial and cytotoxicity tests indicate that Ag@Template NCs display much better performance than Ag nanoparticles (Ag NPs), which have a comparable overall size of ∼25 nm. The inhibitory capability of Ag@Template NCs to bacteria strongly depends on the grain size. Specifically, the Ag@Template-1 NC assembled by the smallest grains (1.6 ± 0.3 nm) presents the best antibacterial activity. For E. coli (-), the MIC value is as low as 5 μg/mL (0.36 μg/mL of Ag), while for S. aureus (+), the value is around 10 μg/mL (0.72 μg/mL of Ag). The survival rate of L02 cells and lactate dehydrogenase assay together illustrate the low cytotoxicity possessed by the prepared Ag@Template NCs. Therefore, the proposed Ag@Template NC structure successfully resolves the high reactivity, instability, and fast oxidation issues of the ultrasmall Ag nanoparticles, and integrates high antibacterial efficiency and nontoxicity to biological cells into one platform, which implies its broad potential application in biomedicine.

Fabrication of novel narrow/wide band gap Bi4O5I2/BiOCl heterojunction with high antibacterial and degradation efficiency under LED and sunlight

It is necessary to construct photocatalytic heterojunctions with high efficiency to remove bacteria and antibiotics from polluted water. To achieve this goal, by selecting Bi4O5I2 with narrow band gap and BiOCl with wide band gap, a novel Bi4O5I2/BiOCl heterojunction was constructed by a simple precipitation method. Various characterizations including XRD, TEM and XPS confirmed that the Bi4O5I2/BiOCl heterojunction was successfully synthesized. The optimum sample 30% Bi4O5I2/BiOCl can inactivate Escherichia coli (E. coli) in 30 min, Staphylococcus aureus (S. aureus) in 75 min and degrade 76% tetracycline (TC) in 60 min in LED light. To further study the performance of the photocatalyst, the photocatalyst was tested in sunlight. It was found 30% Bi4O5I2/BiOCl could inactivate E. coli in 6 min, S. aureus in 15 min and degrade 84% TC in 60 min under sunlight, realizing a shorter reaction time and a better degradation efficiency. Photocurrent and electrochemical impedance tests (EIS) results confirmed higher electron hole separation efficiency in composites. The mechanism of removing pollutants under LED light and sunlight was verified by their respective capture experiments. This experiment provides a new possibility for the application of photocatalysts in a variety of light sources.

Antibacterial Peptides Produced by Alcalase from Cowpea Seed Proteins.

Cowpea seed protein hydrolysates (CPH) were output from cowpea seeds applying alcalase® from Bacillus licheniformis. CPH with an elevated level of hydrolysis was fractionated by size exclusion chromatography (SEC). Both CPH and SEC-portions showed to contain antimicrobial peptides (AMPs) as they inhibited both Gram-positive bacteria, such as Listeria monocytogenes LMG10470 (L. monocytogenes), Listeria innocua. LMG11387 (L. innocua), Staphylococcus aureus ATCC25923 (S.aureus), and Streptococcus pyogenes ATCC19615 (St.pyogenes), and Gram-negative bacteria, such as Klebsiella pnemoniae ATCC43816 (K. pnemoniae), Pseudomonas aeroginosa ATCC26853 (P. aeroginosa), Escherichia coli ATCC25468) (E.coli) and Salmonella typhimurium ATCC14028 (S. typhimurium).The data exhibited that both CPH and size exclusion chromatography-fraction 1 (SEC-F1) showed high antibacterial efficiency versus almost all the assessed bacteria. The MIC of the AMPs within SEC-F1 and CPHs were (25 µg/mL) against P. aeruginosa, E.coli and St. pyogenes. However, higher MICsof approximately 100–150 µg/mL showed for both CPHs and SEC-F1 against both S. aureus and L. innocua; it was 50 µg/mL of CPH against S.aureus. The Electro-spray-ionization-mass-spectrometry (ESI-MS) of fraction (1) revealed 10 dipeptides with a molecular masses arranged from 184 Da to 364 Da and one Penta peptide with a molecular mass of approximately 659 Da inthe case of positive ions. While the negative ions showed 4 dipeptides with the molecular masses that arranged from 330 Da to 373 Da. Transmission electron microscope (TEM) demonstrated that the SEC-F1 induced changes in the bacterial cells affected. Thus, the results suggested that the hydrolysis of cowpea seed proteins by Alcalase is an uncomplicated appliance to intensify its antibacterial efficiency.

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

AbstractIn 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.

The Antibacterial Effect of Bacteriophage-Like Gold Nanoparticles

The growth of pathogenic bacteria seriously threatens human health. Effective inhibition of pathogenic bacteria in the human body and the surrounding environment is of great urgency. In this work, we propose a strategy in preparing bacteriophage-like gold nanoparticles (B-AuNPs) for antibacterial applications. B-AuNPs were prepared by multiple in-situ reducing reactions on the surface of AuNPs. It was shown that the secondary-reduced AuNPs (B1-AuNPs) have a bacteriophage shaped morphology. Under near infrared laser, B1-AuNPs could almost completely inhibit bacterial growth at low concentrations within 5 min, due to the combined effects of increased temperature and reactive oxygen species (ROS). Moreover, B-AuNPs can be easily separated from the dead bacteria and the recycled B-AuNPs remain the high antibacterial efficiency. It is concluded that B-AuNPs have great potentials in the antibacterial researches for biocontrol, biomedicine and environmental engineering.

The synergistic effect of enhanced photocatalytic activity and photothermal effect of oxygen-deficient Ni/reduced graphene oxide nanocomposite for rapid disinfection under near-infrared irradiation

The rational design of high antibacterial efficiency are urgently needed as the occurrence of drug-resistance issues. Hence, Ni/reduced graphene oxide nanocomposite (Ni/rGO) with different amounts of oxygen vacancies were fabricated for efficient disinfection. The optimized Ni/rGO (A100) exhibited highly effective inactivation efficacy of 99.6% and 99.5% against Escherichia coli and Bacillus subtilis within 8 min near-infrared (NIR) irradiation through the synergistic effects of photothermal therapy and oxidative damage, which were much higher than single treatment. The A100 nanocomposite achieved an extraordinary photothermal conversion efficiency (35.78%) under the 808 nm irradiation for enhanced photothermal hyperthermia, thereby destroying the cell membrane and accelerating the GSH depletion. The radical scavenger experiment confirmed that •O2- and •OH play the chief role in photodisinfection reaction. Besides, A100 could exert significant damage on the ATP synthesis. The excellent photothermal performance and photocatalytic activity can be attributed to the appropriate oxygen vacancy density, which improves the absorption of NIR light and facilitates the separation of photogenerated electron-hole pairs. Besides, the higher NiO content of A100 contributed to improving the photocatalytic effect. Our work demonstrated a promising strategy for efficient water pollution purification caused by pathogenic bacteria.

ZnO Nanoparticles-Modified Dressings to Inhibit Wound Pathogens.

Zinc oxide (ZnO) nanoparticles (NPs) have been investigated for various skin therapies in recent years. These NPs can improve the healing and modulate inflammation in the wounds, but the mechanisms involved in such changes are yet to be known. In this study, we have designed a facile ZnO nano-coated dressing with improved antimicrobial efficiency against typical wound pathogens involved in biofilm and chronic infections. ZnO NPs were obtained by hydrothermal method and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy. Antibacterial and antibiofilm effects were evaluated against laboratory and clinical isolates of significant Gram-negative (Pseudomonas aeruginosa and Escherichia coli) and Gram-positive (Staphylococcus aureus and Enterococcus faecalis) opportunistic pathogens, by quantitative methods. Our results have shown that the developed dressings have a high antibacterial efficiency after 6–24 h of contact when containing 0.6 and 0.9% ZnO NPs and this effect is similar against reference and clinical isolates. Moreover, biofilm development is significantly impaired for up to three days of contact, depending on the NPs load and microbial species. These results show that ZnO-coated dressings prevent biofilm development of main wound pathogens and represent efficient candidates for developing bioactive dressings to fight chronic wounds.

Chlorin e6 conjugated chitosan as an efficient photoantimicrobial agent

The development of antibacterial agents with high bacteria-binding capability and antibacterial efficiency is highly desirable. Herein, cationic polysaccharide chitosan (CS) was combined with photosensitizer Chlorin e6 (Ce6) to construct a novel photodynamic antibacterial agent (CS-Ce6 conjugates) for combating gram-positive bacteria Staphylococcus aureus (S. aureus) and gram-negative bacteria Escherichia coli (E. coli). CS-Ce6 conjugates with different degrees of substitution (DS) were synthesized and characterized by a spectroscopic method and organic elemental analysis to understand the relationship between structure and antibacterial effect. CS-Ce6 conjugates revealed good reactive oxygen species (ROS) generation ability and photodynamic antibacterial effect. Meanwhile, they both were positively correlated with DS in the range of 4.81% ~ 11.56% resulting in stronger photodynamic antibacterial ability. These findings highlight that CS-Ce6 conjugates have the potential as an effective photodynamic bactericidal agent in the antibacterial field.

Hydrothermally structured superhydrophobic surface with superior anti-corrosion, anti-bacterial and anti-icing behaviors

Corrosion and biofoulings are ubiquitous problems with detrimental impact for a variety of industries. Transforming intrinsically hydrophilicity of metallic surface to be non-wetting superhydrophobicity is highly desired for acquiring protective surfaces. In this paper, hydrothermal structured superhydrophobic surfaces were fabricated on aluminum alloy substrates through ammonia etching followed with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) modification. The surface morphologies, roughness, chemical compositions and the relationship between hydrothermal parameters and wettability transition were systematically investigated. Besides, the self-cleaning ability, corrosion resistance, NaCl deliquescence behavior, anti-bacterial and anti-icing properties were evaluated. The results demonstrated a remarkably improved charge transfer resistance ( R ct ), high anti-bacterial efficiency towards E. coli and S. aureus bacteria and significantly enhanced anti-icing performance. We believe the superior corrosion resisting, bacterial suppression and ice over delay performance of superhydrophobic metallic materials will exhibit promising applications in various industrial fields. • Superhydrophobic surface was achieved by hydrothermal etching and molecule grafting. • The wettability plays a key role in determining the properties of the surface. • The charge transfer resistance of superhydrophobic surface was greatly enhanced. • NaCl deliquescence behavior suggests potential atmospheric corrosion inhibition. • The superhydrophobic surface exhibit improved anti-bacterial and anti-icing properties.

V2C Nanosheets as Dual-Functional Antibacterial Agents

Antibiotic-resistant bacterial strains have been continuously increasing and becoming a supreme threat to public health globally. The nanoparticle-based photothermal treatment has emerged as a powerful tool to combat toxic bacteria. Photothermal agents (PTAs) with cost-effective and high photothermal conversion efficiency are highly desirable. Herein, we unite the green process for delamination of V2AlC to produce a high yield mass of two-dimensional (2D) V2C nanosheets (NSs) by using algae extracts and demonstrate their high antibacterial efficiency. The resultant V2C NSs present decent structural reliability and intrinsic antibacterial ability. Powerful near-infrared (NIR) absorption and extraordinary photothermal conversion proficiency make it a good PTA for the photothermal treatment of bacteria. The antibacterial efficiency evaluation indicated that V2C NSs could effectively kill both Gram-positive S. aureus and Gram-negative E. coli. About 99.5% of both types of bacteria could be killed with low-dose of V2C NSs suspension (40 μg/mL) with 5 min NIR irradiation due to the intrinsic antibacterial ability and photothermal effect of V2C NSs, which is much higher than previous reports on Ta4C3, Ti3C2, MoSe2, and Nb2C. This work expands the application of MXene V2C NSs for rapid bacteria-killing and would gain promising attention for applications in the sterilization industry.

Bacterial hyperpolarization modulated by polyoxometalates for solutions of antibiotic resistance

Developing strategies against the antibiotic resistance is a major global challenge for public health. Here, we report the synergy of the combination of Preyssler-type polyoxometalates (POMs) ([NaP5W30O110]14− or [AgP5W30O110]14−) and ribosome-targeting antibiotics for high antibacterial efficiency with low risk of antibiotic resistance. Due to their ultra-small sizes and active surface ligands, POM anions show strong affinity to bacterial cell membrane and impose hyperpolarization of the bacterial cells as well as the decrease of Mg2+ influx by blocking Mg2+ transporters, which finally lead to the structural perturbations of ribosomes and instability of bacterial structures. The bacterial growth can, therefore, be regulated by the presence of POMs: a fraction of Bacillus subtilis shifted to a ‘dormant’, slow-growing cellular state (an extended lag phase) upon the application of subinhibitory concentration of POMs. An approach to combat antibiotic resistant bacteria by applying POMs at their early growth phase followed by antibiotic exposure is validated, and its high efficiency for bacterial control is confirmed.

Fe(II)-driven self-assembly of enzyme-like coordination polymer nanoparticles for cascade catalysis and wound disinfection applications

A kind of coordination polymer nanoparticles was facily prepared using Fe(II) and GMP as the motifs through a coordination-driven self-assembly process. The resultant Fe-GMP CPNs show excellent peroxidase-like activity via the conversion of H 2 O 2 into OH, accompanied by high antibacterial efficiency. GOX could be adaptively encapsulated into Fe-GMP CPNs, and the proposed GOX@Fe-GMP CPNs functioned as an enzyme cascade model with a glucose-responsive property in OH production, with excellent antibacterial and wound disinfection efficiency under physiological conditions. • Self-assemblied coordination polymer nanoparticles were prepared using Fe(II) and GMP. • The Fe-GMP CPNs show excellent peroxidase-like activity through OH production. • The Fe-GMP CPNs indicated high antibacterial efficiency for E. coli and S. aureus . • The prepared GOX@Fe-GMP CPNs functioned as an enzyme cascade model in OH production. • GOX@Fe-GMP CPNs have excellent antibacterial and wound disinfection efficiency. The intelligent regulation of reactive oxygen species by nanozymes and the corresponding cascade catalysis hold great potential as a promising next-generation therapeutic methodology. However, the preparation of nanozymes usually involves high material consumption and tedious multistep processes, especially during the packaging of several functional components to realize the enzyme cascade. Here, we propose a facile strategy to prepare the coordination polymer nanoparticles (CPNs) using ferrous ions as the iron source and guanosine monophosphate (GMP) as the supramolecular motif. The resultant Fe-GMP CPNs show excellent peroxidase-like activity via the conversion of H 2 O 2 into highly active OH, accompanied by high antibacterial efficiency, as well as high encapsulation capacity to simultaneously immobilize guest components through an adaptive self-assembly process. Typically, glucose oxidase (GOX) encapsulation endows as-prepared GOX@Fe-GMP CPNs with glucose-responsive properties, so that glucose can be ultimately converted into OH via intermediate H 2 O 2 . This convenient cascade catalysis system not only possesses excellent antibacterial efficiencies, inhibiting the growth of Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) by 99% and significantly promoting wound healing in the absence of additional H 2 O 2 , but also has great application potential in the fields of biocatalysis and biomedicine.

Skin-inspired nanofibrillated cellulose-reinforced hydrogels with high mechanical strength, long-term antibacterial, and self‐recovery ability for wearable strain/pressure sensors

The advent of electric skins (E-skin) with tactile sensation, flexibility, and human affinity characteristics have attracted considerable attention in extensive research fields, including intelligent robots and health monitoring, etc. To improve the intrinsic brittleness of hydrogels, a multifunctional E-skin was fabricated involving a TEMPO-NFC and a covalently cross-linked polyacrylamide (PAM) network. In this work, silver nanoparticles (AgNPs) as long-term antibacterial agent and conductive fillers were coated onto NFC nanofibers. Subsequently, this nanocomposite hydrogel was synthesized by free radical copolymerization of AM monomers with PNAg fibers as interpenetrating fibers network. Importantly with NFC present, the nanocomposite hydrogel exhibited superior mechanical performance and excellent self-recovery ability. The obtained sensor with excellent mechanical stability and sensing performance could detect mechanotransduction signal of human movements. This work provides a practicable method to prepare high antibacterial efficiency, excellent mechanical performance, and dual-modal nanocellulose-based hydrogel sensor for the broad-range application in human-motion detection and intelligence skins.

Light-assisted therapy for biofilm infected micro-arc oxidation TiO2 coating on bone implants

Implant-associated infections is a main factor leading to the failure of titanium (Ti) implants. Micro-arc oxidation is a convenient and effective technique to form a biocompatible metal (Ag+, Cu2+ and Zn2+) ions-doped TiO2 coatings to combat bacterial infections. However, compared with the sterilization by metal ions, light-triggered antibacterial therapies have accepted more attention due to its higher antibacterial efficiency and security. Although TiO2 is an excellent photocatalyst, it can be triggered by ultraviolet light due to the wide band gap. Herein, molybdenum disulfide (MoS2) modified TiO2 coating was fabricated on Ti by a hybrid process of micro-arc oxidation and hydrothermal treatment. The hybrid coating exhibits excellent antibacterial activity under the irradiation of 808 nm near-infrared light because of the synergistic antibacterial effects of reactive oxygen species and hyperthermia, and Staphylococcus aureus (S. aureus) biofilm can be eradicated within 15 min both in vivo and in vitro. Furthermore, collagen decorated on the surface of the hybrid coating can improve the proliferation, adhesion and spreading of MC3T3-E1 osteoblasts.

Piezoelectric nanocomposites for sonodynamic bacterial elimination and wound healing

• Au@BTO nanocomposites are used as novel sonosensitizers to generate considerable ROS under US irradiation. • Au@BTO nanocomposites have significant antibacterial efficiency under US irradiation in vitro and in vivo . • Au@BTO nanocomposites also promote the migration of fibroblasts to promote wound healing. Sonodynamic therapy is considered as a minimally invasive method for pathogen elimination and cancer therapy with high spatial and temporal accuracy. However, sonosensitizers with good biocompatibility and high efficiency are still urgently needed. Herein, we have developed a piezoelectric nanocomposite, barium titanate (BaTiO 3 , BTO) nanocubes with Schottky junction modified by Au nanoparticles (Au@BTO) as a new kind of sonosensitizer for high-efficient sonodynamic therapy. Ultrasound as an exogenous mechanical wave can trigger the piezotronic effect of Au@BTO to facilitate the separation and migration of charge carriers at the piezoelectric/metal interface, which further effectively increases reactive oxygen species (ROS) generation via redox reaction. Due to the high ROS generation efficiency, Au@BTO as the sonosensitizer shows a high antibacterial efficiency against representative Gram-negative and Gram-positive bacteria. Furthermore, the in vitro and in vivo results illustrate that the sonodynamic process also promotes fibroblast migration, which contributes to dermal wound healing in mice. The proposed piezoelectric nanocomposite as a new kind of sonosensitizer has great potential for sonodynamic therapy.

Bacterial communities, potential pathogens and antibiotic resistance genes of silver-loaded stainless steel pipe wall biofilm in domestic hot water system

Silver-loaded stainless steel (Ag-SS) was applied in domestic hot water system (DHWS) to control the biofilm contamination. The antibacterial properties of Ag-SS, as well as the bacterial communities, potential pathogens and antibiotic resistance genes (ARGs) of pipe wall biofilm were investigated, with SS as control. Ag-SS maintained a high antibacterial efficiency on heterotrophic bacteria (70.60 ± 13.22 %) and Escherichia coli (73.56 ± 10.62 %) by contact bacteriostasis. Dominant phyla exhibited a lower relative abundance in Ag-SS than SS. The bacteria were further classified into abundant (≥ 1 %), moderately abundant (0.1∼1 %) and rare (≤ 0.1 %) taxa to investigate their responses to silver. There were 15.33 % of shared operational taxonomic units (OTUs) belonged to abundant taxa, while most unique OTUs (> 80 %) of each sample were identified as rare taxa. As the primary abundant genera, Mesorhizobium and Bradyrhizobium exhibited resistant and sensitive to silver, respectively. Most dominant moderately abundant and rare genera were resistant to silver. Moreover, among 19 detected potential pathogens, Legionella, Parachlamydia and Aeromonas were sensitive to silver, while Pseudomonas and Acinetobacter were resistant to silver. Furthermore, a total of 48 ARGs were detected and they exhibited similar distributions in both samples. The total abundance of ARGs in Ag-SS increased by 0.08 fold compared with that in SS, with efflux pumps as the main resistance mechanisms. This study highlights the different responses of abundant, moderately abundant and rare taxa to silver, and the occurrences of ARGs, confirming that Ag-SS was an effective disinfection strategy for biosafety protection of DHWS.

Iodine-doped carbon dots with inherent peroxidase catalytic activity for photocatalytic antibacterial and wound disinfection.

A new type of nitrogen-iodine co-doped carbon dot (N/I-CD) was synthesized by a one-step hydrothermal method with a fluorescence quantum yield of 37%. The prepared N/I-CDs exhibit peroxidase-like activity, can catalyze bio-safety levels of H2O2 to generate hydroxyl radicals (•OH) under visible light and enhance the level of reactive oxygen species (ROS) in bacteria cells. All in vitro experiments showed that the designed system has strong photocatalytic antibacterial activity against both E. coli and S. aureus bacteria. The light-induced antibacterial function of N/I-CDs was evaluated under the conditions of changing other experimental parameters. When the visible light irradiation time was extended to 60min, the antibacterial efficiency of N/I-CDs (0.21mg·mL-1) against S. aureus and E. coli reached 100% in the presence of exogenous H2O2 (0.07mM). More importantly, wound disinfection in vivo demonstrates the high antibacterial efficiency, low toxicity and application potential of good biocompatibility due to the nanozyme activity of N/I-CDs.

A flexible fibrous membrane based on copper(II) metal-organic framework/poly(lactic acid) composites with superior antibacterial performance.

A flexible antibacterial fibrous membrane employing high antibacterial efficiency has great potential in healthcare applications. Herein, a three-dimensional copper(ii) metal-organic framework [Cu2(CA)(H2O)2, Cu-MOF-1] and poly(lactic acid) (PLA) composite fibrous membrane was prepared through a facile electrospinning method. The sphere-like Cu-MOF-1 was rapidly synthesized by a microwave-assisted hydrothermal reaction of Cu(ii) salts with citric acid (H4CA) in the presence of polyvinyl pyrrolidone (PVP). The surface morphology, thermal stability, mechanical properties and hydrophilicity test of the as-prepared Cu-MOF-1/PLA fibrous membrane were studied systematically. Compared with commercial copper nanoparticles (Cu-NPs), citric acid and copper citrate, Cu-MOF-1 showed higher antibacterial properties with the bacteriostatic rates of 97.9% and 99.3% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively, when the used dose was 250 μg mL-1. The Cu-MOF-1/PLA fibrous membrane also exhibited outstanding bactericidal activities against E. coli and S. aureus with the antibacterial rates up to 99.3% and 99.8%, respectively. Mechanism investigation indicated that the slowly released Cu2+ ions could destroy the microenvironment of bacteria cells and destroy the integrity and permeability of the cell membrane, leading to enzyme inactivation. Therefore, the as-prepared flexible fibrous membrane will advance progress toward developing a broad spectrum antibacterial textile for healthcare protection related applications.