Design of amphiphilic poly(vinylidene fluoride-<Emphasis Type="Italic">co</Emphasis>-hexafluoropropylene)-based gel electrolytes for high-performance lithium-ion batteries

Gel polymer electrolytes (GPE) based on electrospun polymer membranes, poly(vinylidene fluoride-co-hexafluoropropylene), grafted poly(poly(ethylene glycol) methyl ether methacrylate) (PVDF-HFP-g-PPEGMA), and poly(vinylidene difluoride-co-hexafluoropropylene) (PVDF-HFP) are prepared for lithium ion batteries by incorporating with 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI). The uniform porosity and the compatibility of blend electrospun membranes avoiding the pore blocking are beneficial to enhance the electrolyte uptakes. The GPE based on the fibrous PVDF-HFP-g-PPEGMA/PVDF-HFP activated with 1 M LiTFSI (BMITFSI) show a maximum ionic conductivity of 2.3 × 10^?3 S cm^?1 at room temperature and electrochemical stability of up to 5.2 V. The Li/GPE/LiFePO₄ cells with GPE based on PVDF-HFP-g-PPEGMA/PVDF-HFP blend electrospun membrane deliver specific capacities of 163, 141, and 125 mAh g^?1 at 0.1, 0.5, and 1C rates, respectively, and remains well after 50 cycles for each rate. Therefore, the novel GPE have been demonstrated to be suitable for lithium-ion battery applications.     

Shape-controlled synthesis of Cu2O nano/microcrystals and their antibacterial activity

Uniform cuprous oxides with different morphologies have been successfully synthesized using polyvinylpyrrolidone (PVP) as a capping agent. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis spectrophotometer, Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy were employed to characterize the structure and morphology of cuprous oxides. It was found that the reaction conditions such as PVP, reducing agent and complexing agent played important roles in the formation of regular cuprous oxide crystals. In addition, their antibacterial activity against Bacillus subtilis (B. subtilis), Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) was also investigated by the Oxford cup method. Results suggested that cuprous oxides are selective in their antibacterial action. They display effective antibacterial activity against S. aureus, B. subtilis and P. aeruginosa. There is no bactericidal ability against E. coli in the tested concentration range, which indicates that E. coli may be a Cu(I)-tolerant bacterium.     

Preparation and characterization of antibacterial Au/C core-shell composite

An environment-friendly oxidation-reduction method was used to prepare Au/C core-shell composite using carbon as core and gold as shell. The chemical structures and morphologies of Au/C core-shell composite and carbon sphere were characterized by X-ray diffraction, transmission electron microscope, energy dispersion X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). The antibacterial properties of the Au/C core-shell composite against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans) were examined by the disk diffusion assay and minimal inhibition concentration (MIC) methods. In addition, antibacterial ability of Au/C core-shell composite was observed by atomic force microscope. Results demonstrated that gold homogeneously supported on the surface of carbon spheres without aggregation and showed efficient antibacterial abilities.     

Preparation and antibacterial effect of silver-hydroxyapatite/titania nanocomposite thin film on titanium

The composite which contains Ag⁺ and nanosized hydroxyapatite with TiO₂ was deposited onto titanium by dipping method. The morphology, chemical components and structures of the thin film were characterized by XRD, scanning electronic microscope (SEM) and energy dispersive X-ray analysis (EDX). Staphylococcus aureus and Escherichia coli were utilized to test the antibacterial effect. XRD results demonstrated that the films have characteristic diffraction peaks of pure HA. EDX results showed that the deposited films consisted of Ca, P, Ti, O and Ag, all of which distribute uniformly. With regard to the antibacterial effect, 98% of S. aureus and more than 99% of E. coli were killed after 24 h incubation and pictures of SEM showed obviously fewer cells on the surface with coating.     

New 7-piperazinylquinolones containing (benzo[<Emphasis Type="BoldItalic">d</Emphasis>]imidazol-2-yl)methyl moiety as potent antibacterial agents

A series of 7-piperazinylquinolones containing a (benzo[d]imidazol-2-yl)methyl moiety were designed and synthesized as new antibacterial agents. The antibacterial activity of title compounds was evaluated against Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumonia) microorganisms. Among the tested compounds, the N1-cyclopropyl derivative 4a showed the highest activity against S. aureus, S. epidermidis, B. subtilis and E. coli (\(\text {MIC} = 0.097\) \(\upmu \)g/mL), being 2–4 times more potent than reference drug norfloxacin. A structure-activity relationship study demonstrated that the effect of the nitro group on the benzimidazole ring depends on the pattern of substitutions on the piperazinylquinolone.     

Copper and Graphene activated ZnO nanopowders for enhanced photocatalytic and antibacterial activities

ZnO, ZnO:Cu and ZnO:Cu:Graphene nanopowders were synthesized via a facile wet chemical method. The XRD studies show that the synthesized samples have hexagonal wurtzite structure. It is found that graphene addition induces a decrease in crystallite size. UV–vis absorption spectra of the samples show sharp absorption edges around 380 nm. Photoluminescence studies reveal that the incorporation of copper and graphene in ZnO facilitates the efficient photo generated electron–hole pair separation. It is found that the ZnO:Cu and ZnO:Cu:Graphene nanopowder exhibit improved photocatalytic efficiency for the photodegradation of Methylene Blue (MB) under visible light irradiation. Moreover, improved antibacterial activity of ZnO:Cu:Graphene nanopowder against Escherichia coli and Staphylococcus aureus bacteria is observed.     

Mechanism and optimization of non-thermal plasma-activated water for bacterial inactivation by underwater plasma jet and delivery of reactive species underwater by cylindrical DBD plasma

Plasma-activated water (PAW) has been in use for the past decade in sanitization against bacteria and other microorganisms. This research study compared PAW generated by a DC positive flyback transformer (FBT) underwater plasma jet with delivery of reactive species underwater by cylindrical dielectric barrier discharge (C-DBD) with a neon transformer. A Box–Behnken design was adopted as a response surface methodology (RSM) to design the experimental plan and optimize operating parameters including time, gas flow, and gas ratio. The physical responses comprise optical emission spectroscopy (OES), pH, oxidation-reduction potential (ORP), and electrical conductivity (EC). The chemical responses consist of hydrogen peroxide (H₂O₂) and hydroxyl radicals (OH·). The biological responses include Escherichia coli reduction and Staphylococcus aureus reduction. The optimal condition for underwater plasma jet was found to be Ar gas with a flow rate of 3 slm for 6.5 min of treatment time, which can reduce E. coli and S. aureus to 7.14 ± 0.14 and 3.10 ± 0.26 in log, respectively. Also, the optimal condition for delivery of reactive species underwater by C-DBD plasma was found to be Ar (99%): O₂ (1%) gas mixture with an Ar gas flow rate of 4 slm for a treatment time of 11.5 min, which could reduce E. coli and S. aureus to 0.45 ± 0.07 and 2.45 ± 0.23 in log, respectively.     

Deposition of antibacterial of poly(1,3-bis-(p-carboxyphenoxy propane)-co-(sebacic anhydride)) 20:80/gentamicin sulfate composite coatings by MAPLE

We report on thin film deposition of poly(1,3-bis-(p-carboxyphenoxy propane)-co-sebacic anhydride)) 20:80 thin films containing several gentamicin concentrations by matrix assisted pulsed laser evaporation (MAPLE). A pulsed KrF* excimer laser was used to deposit the polymer-drug composite thin films. Release of gentamicin from these MAPLE-deposited polymer conjugate structures was assessed. Fourier transform infrared spectroscopy was used to demonstrate that the functional groups of the MAPLE-transferred materials were not changed by the deposition process nor were new functional groups formed. Scanning electron microscopy confirmed that MAPLE may be used to fabricate thin films of good morphological quality. The activity of gentamicin-doped films against Escherichia coli and Staphylococcus aureus bacteria was demonstrated using disk diffusion and antibacterial drop test. Our studies indicate that deposition of polymer-drug composite thin films prepared by MAPLE is a suitable technique for performing controlled drug delivery. Antimicrobial thin film coatings have several medical applications, including use for indwelling catheters and implanted medical devices.     

Preparation and antibacterial effect of plasma sprayed wollastonite coatings loading silver

In this work, the plasma sprayed wollastonite coating was soaked in 5 wt% AgNO₃ solution at room temperature to load silver for improving its antibacterial effect. The surface characteristics of the silver-loaded coating were investigated by SEM, EDS and XRD. The release rate of silver from the coating was measured by ICP-OES in deionized water. The osteotoxicity of the silver-loaded coating was evaluated by in vitro cell culturing test. The antibacterial activity against Staphylococcus aureus was examined by Zone of Inhibition test. The results showed that the loaded silver reacted with the wollastonite coating to form silver silicate, which ensured a sustained release of silver in deionized water for as long as 50 days. The antibacterial activity and cell culturing tests confirmed that the silver released from silver-loaded wollastonite coating had strong inhibition against the growth of S. aureus, while they did not exhibit any adverse effects on the osteoblasts proliferation.     

Electrospun Fibrous Membranes of Modified Polystyrene and its Copolymer With Butyl Acrylate and Their Respective Adsorption Capabilities for Cationic Blue and Copper Ions

Cationic dyes and metal ions in wastewater are considered as environmental pollutants. In order to treat these pollutants individually polystyrene (PS) and poly (styrene-co-butyl acrylate) (P(St-co-BA)) were first electrospun into fibrous membranes with a porous structure and then two simple modification methods were adopted to introduce -SO₃H and -COO^? groups into the PS fibrous membranes' and the P(St-co-BA) fibrous membranes' surfaces, respectively; finally the modified samples were used individually to adsorb either cationic blue dyes or copper ions, respectively. The results showed that the PS fibrous membranes were hydrophobic before modification but they became hydrophilic after modification due to the introduction of -SO₃H. Then the modified PS fibrous membranes had the capability to adsorb cationic blue dyes from water, and their adsorption efficiency, with an adsorption time of 300 min, reached 68.1%. For the P(St-co-BA) fibrous membranes, the -COO^? groups were introduced into their surfaces after hydrolysis in alkali lye; however, they showed very weak adsorption capability for copper ions due to the loss of the fiber-web structure. In addition, the thermal properties of the fibrous membranes before and after modification were analyzed, and the morphology was also observed by field emission scanning electron microscopy.     

Characterization of undoped and Co doped ZnO nanoparticles synthesized by DC thermal plasma method

ZnO nanopowders doped with 5 and 10 at% cobalt were synthesized and their antibacterial activity was studied. Cobalt doped ZnO powders were prepared using dc thermal plasma method. Crystal structure and grain size of the particles were characterized by X-ray diffractometry and optical properties were studied using UV-vis spectroscopy. The particle size and morphology was observed by SEM and HRTEM, revealing rod like morphology. The antibacterial activity of undoped ZnO and cobalt doped ZnO nanoparticles against a Gram-negative bacterium Escherichia coli and a Gram-positive bacterium Bacillus atrophaeus was investigated. Undoped ZnO and cobalt doped ZnO exhibited antibacterial activity against both E. coli and Staphylococcus aureus but it was considerably more effective in the cobalt doped ZnO.     

Ultrasound mediation for one-pot sonosynthesis and deposition of magnetite nanoparticles on cotton/polyester fabric as a novel magnetic,photocatalytic, sonocatalytic,antibacterial and antifungal textile

A magnetic cotton/polyester fabric with photocatalytic, sonocatalytic, antibacterial and antifungal activities was successfully prepared through in-situ sonosynthesis method under ultrasound irradiation. The process involved the oxidation of Fe²⁺ to Fe³⁺ via hydroxyl radicals generated through bubbles collapse in ultrasonic bath. The treated samples were analyzed by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometry. Photocatalytic and sonocatalytic activities of magnetite treated fabrics were also evaluated toward Reactive Blue 2 decoloration under sunlight and ultrasound irradiation. Central composite design based on response surface methodology was applied to study the influence of iron precursor, pH and surfactant concentration to obtain appropriate amount for the best magnetism. Findings suggested the potential of one-pot sonochemical method to synthesize and fabricate Fe₃O₄ nanoparticles on cotton/polyester fabric possessing appropriate saturation magnetization, 95% antibacterial efficiency against Staphylococcus aureus and 99% antifungal effect against Candida albicans, 87% and 70% dye photocatalytic and sonocatalytic decoloration along with enhanced mechanical properties using only one iron rich precursor at low temperature.     

One-pot green fabrication and antibacterial activity of thermally stable corn-like CNC/Ag nanocomposites

Corn-like cellulose nanocrystals/silver (CNC/Ag) nanocomposites were prepared by formic acid/hydrochloric acid hydrolysis of commercial microcrystalline cellulose (MCC), and redox reaction with silver ammonia aqueous solution (Ag(NH₃)₂(OH)) in one-pot green synthesis, in which the preparation and modification of CNCs were performed simultaneously and the resultant modified CNCs could be as reducing, stabilizing and supporting agents for silver nanoparticles. The influences of the Ag⁺ ion concentrations on the morphology, microstructure, and properties of the CNC/Ag nanocomposites were investigated. It is found that corn-like CNC/Ag nanocomposites containing Ag nanoparticles with diameter of about 20–40 nm were obtained. Compared to the MCCs, high crystallinity of 88.5 % and the maximum degradation temperature (T _max) of 364.5 °C can be achieved. Moreover, the CNC/Ag nanocomposites showed strong antibacterial activity against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Furthermore, such nanocomposites can act as bifunctional nanofillers to improve thermal stability, mechanical property, and antibacterial activity of commercial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(lactic acid).     

Selective Antimicrobial and Antibiofilm Disrupting Properties of Functionalized Diamond Nanoparticles Against Escherichia coli and Staphylococcus aureus

Diamond nanoparticles (NDs) have demonstrated great promise as useful materials in a variety of biomedical settings. In this paper, the antimicrobial and antibiofilm activities of variously functionalized NDs against two common bacterial targets Gram‐negative bacterium Escherichia coli and Gram‐positive bacterium Staphylococcus aureus are compared. Hydroxylated (ND‐OH), aminated (ND‐NH₂), carboxylated (ND‐COOH), mannose (ND‐Mannose), tri‐thiomannoside (ND‐Man₃), or tri‐thiolactoside (ND‐Lac₃)‐modified NDs are fabricated and evaluated in the present work. Of these, the mannose‐modified NDs are found to interfere most strongly with the survival of S. aureus, but not to influence the growth of E. coli. In contrast, particles featuring lactosyl units have the opposite effect on S. aureus growth. Sugar‐functionalized NPs reported to display antibacterial effects are rare. Only ND‐COOH particles are seen to have any effect on the growth profile of E. coli, but the effects are moderate. On the other hand, both ND‐NH₂ and ND‐COOH are found to inhibit E. coli‐induced biofilm formation at levels comparable to the known E. coli biofilm disruptor, ampicillin (albeit at concentrations of 100 μg mL^?1). However, none of the modified particles examined here reveal any significant activity as disruptors of S. aureus‐induced biofilm formation even at the highest concentrations studied.     

Fabrication and characterization chitosan/functionalized zinc oxide bionanocomposites and study of their antibacterial activity

This study deals with preparation and evaluation of properties of chitosan/zinc oxide bionanocomposites (CT/ZnO BNCs) with different amounts of modified zinc oxide nanoparticles (ZnO NPs) through ultrasonic irradiation technique. Due to the high surface energy and tendency for agglomeration, the surface ZnO NPs was modified by a coupling agent as 3-aminopropyltriethoxysilane (APS) to form APS–ZnO nanoparticles. Fourier transform infrared (FTIR) spectroscopy confirmed that APS was successfully grafted onto the ZnO nanoparticles surface. Thermogravimetric analysis (TGA) revealed a surface coverage of the coupling molecule of 2.6 wt%. The resulting bionanocomposites were characterized by FTIR spectra, X-ray diffraction patterns, and TGA. The antibacterial activity of bionanocomposite films was tested against gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The results of CT/ZnO BNCs revealed that the thermal and antibacterial properties obviously improved the presence of ZnO NPs in comparison with the pure CT and that this increase is higher when the NP content increases. Further, it was observed that antibacterial activity of the resulting hybrid biofilms showed somewhat higher for gram-positive bacteria compared to gram-negative bacteria.     

On the Effect of Nanosilver Reinforcement on the Mechanical,Physical, and Antimicrobial Properties of Polyethylene Blown Films

The simultaneous effect of silver nanoparticles on the antibacterial, mechanical, and physical properties of polyethylene (PE) films is evaluated. For this aim, uniaxial tensile, film rupture, and permeability tests and X-ray diffraction analysis were conducted. The biocidal performance against Escherichia coli and Staphylococcus aureus bacteria was also assessed. The results show that reinforcements with as little as 1 wt% nanosilver provided absolute antibacterial performance, while generally maintaining the mechanical properties. The reinforcement causes noticeable alterations in the crystallization behavior, which is manifested in the variations of gas permeability of the PE films.     

Investigation of Mg(OH)2 nanoparticles as an antibacterial agent

Our experimental results of using Mg(OH)₂ nanoparticles as an antibacterial agent are reported in this study. The antibacterial behavior of Mg(OH)₂ nanoparticles in liquid culture and in paper sheets was investigated. The colony forming units (CFU) counting and the headspace gas chromatography (HS-GC) measurement were used to determine the cell viability. Results indicate that Mg(OH)₂ nanoparticles are effective antibacterial agent against Escherichia coli (E. coli) and Burkholderia phytofirmans, and the OH^? and Mg²⁺ ions in Mg(OH)₂ water suspension were found not to be the reason for killing the bacteria. Mg(OH)₂ nanoparticles could be added directly to wood pulp to make paper sheets, whose antibacterial efficiency increased with the increase of the nanoparticle amount. The possible mechanism of antibacterial effect of Mg(OH)₂ nanoparticles is discussed.     

Bioactive compounds and antibacterial activities in crystallized honey liquefied with ultrasound

The effect of ultrasound on the crystal size, phenols, flavonoids, Maillard products and antibacterial activity of crystallized honeys was studied. Three multifloral honeys (M), one monofloral (MO) and one honeydew (HD) honey were used. Ultrasound was performed at 42 kHz for different times (0, 5, 10 and 15 min). The antibacterial activities were tested against Salmonella typhimurium, Bacillus subtilis, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus and Escherichia coli. In all honeys, the parameters analyzed had significant differences ((P < 0.05)). After 15 min of ultrasound the HD had increments of 44 mg of gallic acid/100 g of honey in phenols, and some M showed increase in flavonoids (5.64 mg of quercitin /100 g of honey) and improvement in inhibition against Salmonella typhimurium was 13.1%. In some honeys the correlation between phenols or flavonoids and antibacterial activity were significant ((P < 0.05)). No correlation was found between Maillard products and antibacterial activity. The ultrasound treatment effect on the crystal size, phenols, flavonoid, Maillard products, and antibacterial activity of crystallized honeys were different in each honey.     

Bactericidal effects of Ag nanoparticles immobilized on surface of SiO2 thin film with high concentration

Bactericidal activity of high concentration Ag nanoparticles immobilized on surface of an aqueous sol–gel silica thin film was investigated against Escherichia coli and Staphylococcus aureus bacteria. Size of the surface nanoparticles was estimated in the range of 35–80 nm by using atomic force microscopy. Due to accumulation of the silver nanoparticles at near the surface (at depth of 6 nm and about 40 times greater than the silver concentration in the sol), the synthesized Ag–SiO₂ thin film (with area of 10 mm²) presented strong antibacterial activities against E. coli and S. aureus bacteria with relative rate of reduction of the viable bacteria of 1.05 and 0.73 h⁻¹ for initial concentration of about 10⁵ cfu/ml, respectively. In addition, the dominant mechanism of silver release in long times was determined based on water diffusion in surface pores of the silica film, unlike the usual diffusion of water on the surface of silver-based bulk materials. Therefore, the Ag nanoparticles embedded near the surface of the SiO₂ thin film can be utilized in various antibacterial applications with a strong and long life activity.     

Designing N-halamine based antibacterial surface on polymers: Fabrication, characterization, and biocidal functions

We demonstrate a valuable method to generate reactive groups on inert polymer surfaces and bond antibacterial agents for biocidal ability. Polystyrene (PS) surfaces were functionalized by spin coating of sub-monolayer and monolayer films of poly(styrene-b-tert-butyl acrylate) (PS-PtBA) block copolymer from solutions in toluene. PS-PtBA self-assembled to a bilayer structure on PS that contains a surface layer of the PtBA blocks ordering at the air-polymer interface and a bottom layer of the PS blocks entangling with the PS substrate. The thickness of PtBA layer could be linearly controlled by the concentration of the spin coating solution and a 2.5 nm saturated monolayer coverage of PtBA was achieved at 0.35% (w/w). Carboxyl groups were generated by exposing the tert-butyl ester groups of PtBA on saturated surface to trifluoroacetic acid (TFA) to bond tert-butylamine via amide bonds that were further chlorinated to N-halamine with NaOCl solution. The density of N-halamine on the chlorinated surface was calculated to be 1.05 × 10⁻⁵ mol/m² by iodimetric/thiosulfate titration. Presented data showed the N-halamine surface provided powerful antibacterial activities against Staphylococcus aureus and Escherichia coli. Over 50% of the chlorine lost after UVA irradiation could be regained upon rechlorination. This design concept can be virtually applied to any inert polymer by choosing appropriate block copolymers and antibacterial agents to attain desirable biocidal activity.