Comparative Study of the Micellar and Antimicrobial Activity of Gemini-Conventional Surfactants in Pure and Mixed Micelles

We have carried out mixed micellization of pentanediyl-α,ω-bis(dimethyl cetylammonium bromide) (G5) with conventional cationic cetylpyridinium chloride (CPC) and nonionic polyoxyethylene (20) cetyl ether (C16E20) in aqueous media and explored their antimicrobial activity in single and binary systems against Escherichia coli (E.coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). The compounds tested showed excellent antibacterial activity: 0.76–3.38 g/l minimum inhibitory concentration (MIC) and were more active against gram +ve bacteria. For surfactant mixtures G5-C16E20 > G5-CPC, the ionic-nonionic binary surfactant showed greater antibacterial activity. The experimental results of this study may be profitably used to understand and predict the antibacterial activity of gemini-conventional surfactant systems and provide valuable information for selection of surfactant for microbiocidal action.     

The Antibacterial Activity of Ta-doped ZnO Nanoparticles

A novel photocatalyst of Ta-doped ZnO nanoparticles was prepared by a modified Pechini-type method. The antimicrobial study of Ta-doped ZnO nanoparticles on several bacteria of Gram-positive Bacillus subtilis (B. subtilis) and Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) were performed using a standard microbial method. The Ta-doping concentration effect on the minimum inhibitory concentration (MIC) of various bacteria under dark ambient has been evaluated. The photocatalytical inactivation of Ta-doped ZnO nanoparticles under visible light irradiation was examined. The MIC results indicate that the incorporation of Ta⁵⁺ ions into ZnO significantly improve the bacteriostasis effect of ZnO nanoparticles on E. coli, S. aureus, and B. subtilis in the absence of light. Compared to MIC results without light irradiation, Ta-doped ZnO and pure ZnO nanoparticles show much stronger bactericidal efficacy on P. aeruginosa, E. coli, and S. aureus under visible light illumination. The possible antimicrobial mechanisms in Ta-doped ZnO systems under visible light and dark conditions were also proposed. Ta-doped ZnO nanoparticles exhibit more effective bactericidal efficacy than pure ZnO in dark ambient, which can be attributed to the synergistic effect of enhanced surface bioactivity and increased electrostatic force due to the incorporation of Ta⁵⁺ ions into ZnO. Based on the antibacterial tests, 5 % Ta-doped ZnO is a more effective antimicrobial agent than pure ZnO.     

Enhanced functionality of colloidal polyaniline/polyvinyl alcohol nanocomposite as an antibacterial agent

This study describes the preparation of colloidal polyaniline/polyvinyl alcohol (PAn/PVA) nanocomposite by chemical polymerization of aniline (AN) in the presence of ammonium peroxydisulphate (APS) as an oxidant and PVA as a stabilizer. The product was characterized morphologically using a scanning electron microscope (SEM) and transmission electron microscopy (TEM), chemically using Fourier transform infrared (FTIR) and optically UV–visible. The prepared polymer was then tested for the antibacterial properties against gram‐negative bacteria: Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa); and gram‐positive bacteria: Staphylococcus aureus (S. aureus). The antibacterial properties were assessed by disk diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentrations (MBCs), and the bactericidal effect methods. The results clearly showed that colloidal PAn/PVA nanocomposite strongly inhibits the growth of wild‐type E. coli (19 ± 0.5) mm followed by P. aeruginosa (17 ± 0.5 mm) and S. aureus (17.5 ± 0.5 mm) bacteria. S. aureus was completely killed after exposure for only 15 min, whereas S. aureus and E. coli were completely killed after exposure for 25 min. J. VINYL ADDIT. TECHNOL., 22:267–272, 2016. © 2014 Society of Plastics Engineers     

Research of antibacterial activity on silver containing yttria-stabilized–zirconia bioceramic

An antibacterial bioceramic, silver containing yttria-stabilized zirconia (YSZ), was fabricated by sintering for dental prosthesis applications. The biocompatibility, hemocompatibility and antibacterial ability of the silver containing YSZ were evaluated. The addition of silver did not cause tetragonal phase to transform into monoclinic phase and the silver containing YSZ maintained an excellent mechanical property. Furthermore, the sintered silver containing YSZ showed no toxicity and possessed a good antibacterial ability against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) cell.     

Fabrication of ZnO@Plant Polyphenols/Cellulose as Active Food Packaging and Its Enhanced Antibacterial Activity

To investigate the efficient use of bioresources and bioproducts, plant polyphenol (PPL) was extracted from larch bark and further applied to prepare ZnO@PPL/Cel with cellulose to examine its potential as an active package material. The structure and morphology were fully characterized by XRD, SEM, FTIR, XPS and Raman spectra. It was found that PPL is able to cover ZnO and form a coating layer. In addition, PPL cross-links with cellulose and makes ZnO distribute evenly on the cellulose fibers. Coating with PPL creates a pinecone-like morphology in ZnO, which is constructed by subunits of 50 nm ZnO slices. The interactions among ZnO, PPL and cellulose have been attributed to hydrogen bonding, which plays an important role in guiding the formation of composites. The antibacterial properties against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were tested by the inhibition zone method. Our composite ZnO@PPL/Cel has superior antibacterial activity compared to ZnO/Cel. The antibacterial mechanism has also been elaborated on. The low cost, simple preparation method and good performance of ZnO@PPL/Cel suggest the potential for it to be applied as active food packaging.     

Preparation of nylon-6/chitosan composites by nanospider technology and their use as candidate for antibacterial agents

Electrospun nylon-6/chitosan (nylon-6/Ch) nanofibers were prepared by nanospider technology. Quaternary ammonium salts as antibacterial agent were immobilized onto electrospun nylon-6/Ch nanofibers via surface modification by soaking the mat in aqueous solution of glycidyltrimethylammonium chloride (GTMAC) at room temperature overnight to give nylon-6/N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (nylon-6/HTCC). The morphological, structural and thermal properties of the nylon-6/ch nanofibers were studied by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). Biological screening has demonstrated the antibacterial activity of the electrospun nanofibers against Gram negative bacteria, Escherichia coli 35218, and Pseudomonas aeruginosa and Gram positive bacteria, Staphylococcus aureus 24213 among the tested microbes. Thus, the study ascertains the value of the use of electrospun nanofibers, which could be of considerable interest to the development of new antibacterial materials for biomedical applications.     

Development of g-C3N4/ZnO nanocomposite as a novel,highly effective and durable photocatalytic antibacterial coating for cotton fabric

Photocatalytic antibacterial coats are considered among the best solutions to bacterial contamination of fabrics, with the drawback of reduced efficacy after continued use and washing. In the present study, the g-C₃N₄/ZnO (CNZ) nanocomposite has been introduced as a novel cotton fabric coating, with high durability, and CNZ nanopowders were synthesized using a two-step thermal synthesis process and directly coated onto cotton fabric using the sonication technique. The synthesized nanoparticles (NPs) were examined using X-ray diffraction (XRD), UV–visible spectroscopy, photoluminescence (PL), Brunauer-Emmett-Teller (BET), and Fourier transform infrared (FTIR) analyzes. Besides, the SEM analysis confirmed the successful deposition of NPs on cotton fabric. The photodegradation of methylene blue (MB) stain was assessed as a functional test for the photocatalytic effectiveness of the coated fabric, then its antibacterial properties were evaluated under visible light, by direct contact with bacterial suspensions and culturing. The results revealed that the CNZ-coated cotton fabric containing 30% ZnO (CNZ-30) has significant photocatalytic antibacterial activity against both Escherichia coli (gram-negative), and Staphylococcus aureus (gram-positive) bacteria. The bacterial reduction rate of CNZ-30 coated fabric for both E. coli and S. aureus was above 98%, even after 18 washing cycles. This excellent performance is attributed to the effective coupling of ZnO with g-C₃N₄, improved light absorption, and reduced e⁻/h⁺ pair recombination rates. This study novel coating method can offer an environmentally friendly, cost-effective, and simple process to manufacture hybrid CNZ antibacterial cotton in the textile industry.     

Phytofabrication,Characterization and Antibacterial Activity of <Emphasis Type="Italic">Cassia auriculata</Emphasis> Leaf Extract Derived CuO Nanoparticles

A simple, eco-friendly phytosynthesis of copper oxide nanoparticles (CuO NPs) using Cassia auriculata leaf extract was reported. The prepared CuO NPs was characterized by UV–vis spectroscopy which exhibited the surface plasmon resonance (SPR) band at 380–385 nm. TEM and EDX analysis confirmed that CuO NPs were spherical and in size range of 30–35 nm with identified elements Cu and O. X-ray diffraction (XRD) spectrum showed the crystalline nature of the prepared CuO NPs. FTIR spectrum confirmed the presence of Cu–O functional groups. CuO NPs showed significant antibacterial efficacy against all the tested bacterial strains, i.e., Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. CuO NPs showed strong antibacterial action against B. subtilis and E. coli than P. aeruginosa and S. aureus. The results of this study revealed that C. auriculata leaf extract was found to be an effective bio-reducing agent for CuO NPs synthesis and also the antibacterial efficacy of phytofabricated CuO may be useful for its applications in medical and textile industries.     

New 14-Membered Cyclopeptide Alkaloids from Zizyphus oxyphylla Edgew

Two new 14-membered cyclopeptide alkaloids, Oxyphylline B (4) and Oxyphylline C (5), along with three known 13-membered cyclopeptide alkaloids, were isolated from stem and roots of Zizyphus oxyphylla Edgew. The compounds were tested for antibacterial activity. Oxyphylline B (4) showed comparatively better antibacterial activities against Escherichia coli (MIC, 5 μg/mL) than other compounds. This compound also exhibited weak antimicrobial activities against Staphylococcus aureus (MIC, 25 μg/mL), Pseudomonas aeruginosa (MIC, 50 μg/mL) and Salmonella typhi (MIC, 50 μg/mL).     

Preparation,Antibacterial and Physicochemical Behavior of Chitosan/Ofloxacin Complexes

A novel chitosan derivative with ofloxacin (OFX) has been successfully prepared. The IR and 1H-NMR results revealed that the chitosan/ofloxacin (CH-OFX) complex exhibited an electrostatic interaction. The crystalline and surface morphology were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The antimicrobial activity of the complexes against various micro-organisms viz. Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus was tested. It was established that their antibacterial activity is up to four times greater than that of free quinolone drug and chitosan, probably due to the conjunction of favorable pharmacokinetics, excellent bacterial susceptibility and good stability towards metabolic degradation.     

Preparation and antibacterial properties of titanium-doped ZnO from different zinc salts

To research the relationship of micro-structures and antibacterial properties of the titanium-doped ZnO powders and probe their antibacterial mechanism, titanium-doped ZnO powders with different shapes and sizes were prepared from different zinc salts by alcohothermal method. The ZnO powders were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED), and the antibacterial activities of titanium-doped ZnO powders on Escherichia coli and Staphylococcus aureus were evaluated. Furthermore, the tested strains were characterized by SEM, and the electrical conductance variation trend of the bacterial suspension was characterized. The results indicate that the morphologies of the powders are different due to preparation from different zinc salts. The XRD results manifest that the samples synthesized from zinc acetate, zinc nitrate, and zinc chloride are zincite ZnO, and the sample synthesized from zinc sulfate is the mixture of ZnO, ZnTiO₃, and ZnSO₄ · 3Zn (OH)₂ crystal. UV-vis spectra show that the absorption edges of the titanium-doped ZnO powders are red shifted to more than 400 nm which are prepared from zinc acetate, zinc nitrate, and zinc chloride. The antibacterial activity of titanium-doped ZnO powders synthesized from zinc chloride is optimal, and its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) are lower than 0.25 g L⁻¹. Likewise, when the bacteria are treated by ZnO powders synthesized from zinc chloride, the bacterial cells are damaged most seriously, and the electrical conductance increment of bacterial suspension is slightly high. It can be inferred that the antibacterial properties of the titanium-doped ZnO powders are relevant to the microstructure, particle size, and the crystal. The powders can damage the cell walls; thus, the electrolyte is leaked from cells.     

Photocatalytic and antimicrobial effects of interior paints

The interior paints investigated have been formulated on the basis of aqueous acrylic dispersion, rutile titanium dioxide, extenders and special additives as photocatalytic nano zinc oxide and different types of photocatalytic anatase titanium dioxide. Organic dye Orange II was used as an indicator for the reactivity of photocatalytic surfaces. The absorbance change of Orange II solution was measured by a photometer. An agar plate method was used for the evaluation of antimicrobial effect of the coatings. The effectiveness of coatings was demonstrated using the following bacteria relevant to hygiene: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, fungi Aspergillus niger and Penicillium chrysogenum. The nano-form of ZnO was found to be the best photocatalytic agent and also the best and broadest spectrum antimicrobial agent for these interior paints. Statistically significant differences between the control coatings and the coatings with nano-form of ZnO were found using Rank-sum test.     

Experimental and theoretical study of visible light driven scandium (III) doped ZnO for antibacterial activity

ZnO was doped with Sc(III) ions to obtain a low-cost and environment-friendly antibacterial material with highly synergistic antimicrobial activity. The combination of experimental results and theoretical insights was used to describe the effect of Sc doping on the electronic and structural properties of ZnO. Sc(III)-doped ZnO materials with different Sc(III) contents were deposited on white carbon black (WCB) by a facile sol-gel method. The Sc(III) doped antibacterial materials were characterized by FESEM, EDX, HR-TEM, BET, XPS, XRD, ICP-OES, UV–visible spectroscopy, Fastsage and Materials Studio (MS). The antibacterial activities of Zn WCB and Zn–Sc WCB were determined by counting Escherichia coli (E. coli) and Staphylococcus aureus (S.aureus) colonies on bacterial culture plates. The results show that the specific surface area of Sc-doped Zn on WCB was increased by 31.9 m²/g compared to Zn WCB. The optimum doping ratio of Zn and Sc was determined in Zn_0.9574Sc_0.0426O cut from hexagonal wurtzite structure ZnO. Moreover, pure ZnO and Zn_0.9574Sc_0.0426O models were established by density functional theory (DFT). The experimental results and DFT calculations demonstrated that ZnO WCB possessed excellent antibacterial properties after doping with Sc. This improved antibacterial activity was due to the effects of Sc₂O₃ on the ZnO lattice, which resulted in the generation of excess reactive oxygen species (ROS).     

Analytical detection and biological assay of antileukemic drug using gold nanoparticles

Gold nanoparticles are reported and evaluated as probes for the detection of anticancer drug 6-mercaptopurine (6-MP). The nature of binding between 6-MP and the gold nanoparticles via complexation is investigated using ultraviolet-visible spectrum, cyclic voltammetry, transmission electron microscopy, fluorescence and Fourier transform infrared (FT-IR) spectroscopy. The bound antileukemic drug is fluorescent and the quenching property of gold nanoparticles could be exploited for biological investigations. The 6-MP-colloidal gold complex is observed to have appreciable antibacterial and antifungal activity against Micrococcus luteus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Aspergillus fumigatus, and Aspergillus niger. The experimental studies suggest that gold nanoparticles have the potential to be used as effective carriers for anticancer drugs.     

Antibacterial and photocatalytic behaviour of green synthesis of Zn0.95Ag0.05O nanoparticles using herbal medicine extract

The present work aimed to synthesize Zn_0.95Ag_0.05O (ZnAgO) nanoparticles using rosemary leaf extracts as a green chemistry method. The characterization of Ag-doped ZnO nanoparticles was performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet–visible spectrophotometry (UV–visible). The XRD, FTIR, and UV–visible spectra confirmed the formation of the presence of hexagonal ZnAgO nanoparticles. FESEM micrograph shows that the nanoparticles have been distributed homogeneously and uniformly. The morphology of ZnAgO nanoparticles is quasi-spherical configuration. Also, the mean particle size is in the range of 22–40 nm. The photocatalytic degradation of methylene blue in the presence of Ag-doped ZnO nanoparticles is nearly 98.5% after exposing 100 min. The ultraviolet lamp was used as the light source for photocatalyst degradation. The disc diffusion method was chosen to study the antibacterial activity of as-synthesized ZnAgO nanoparticles. Antibacterial activity of Zn_0.95Ag_0.05O nanoparticles against Staphylococcus aureus and Escherichia coli revealed that the as-synthesized ZnAgO nanoparticles were efficient in inhibition of bacterial growth.     

TiO2 hollow spheres as a novel antibiotic carrier for the direct delivery of gentamicin

The TiO₂ hollow spheres were synthesized using a green, cheap, and easy process, in which carbonaceous spheres were chosen as the removable template. The prepared materials were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Atomic force microscopy (AFM), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis. According to the results, the obtained mesoporous TiO₂ hollow spheres demonstrated an external diameters less than 200?nm with shell thickness around 40?nm. The antibacterial activities of the TiO₂ hollow spheres were evaluated against gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa). No antibacterial activity was found for TiO₂ hollow spheres in the used concentrations. TiO₂ hollow spheres were loaded with gentamycin as a selected antibiotic to magnify their benefits in biomedical applications. TiO₂ hollow spheres exhibited good antibiotic carrier activity for the direct delivery of gentamicin, which was attributed to interaction between gentamicin and surface due to their larger specific surface area, more abundant porous structure, and their spherical morphology. The application of TiO₂ hollow spheres as gentamicin carrier undoubtedly opens an avenue to use hollow sphere materials in other drug delivery applications.     

Novel Coumarin-Thiadiazole Hybrids and Their Cu(II) and Zn(II) Complexes as Potential Antimicrobial Agents and Acetylcholinesterase Inhibitors

A series of coumarin-thiadiazole hybrids and their corresponding Cu(II) and Zn(II) complexes were synthesized and characterized with the use of spectroscopic techniques. The results obtained indicate that all the coumarin-thiadiazole hybrids act as bidentate chelators of Cu(II) and Zn(II) ions. The complexes isolated differ in their ligand:metal ratio depending on the central metal. In most cases, the Zn(II) complexes are characteristic of a 1:1 ligand:metal ratio, while in the Cu(II) complexes the ligand:metal ratio is 2:1. All compounds were tested as potential antibacterial agents against Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacterial strains demonstrating activities notably lower than commercially available antibiotics. The more promising results were obtained from the assessment of antineurodegenerative potency as all compounds showed moderate acetylcholinesterase (AChE) inhibition activity     

Mesoporous Ag/ZnO hybrid cages derived from ZIF-8 for enhanced photocatalytic and antibacterial activities

Ag/ZnO hybrid cages with well-preserved polyhedron shape and rich mesoporous structures were prepared thorough in situ pyrolysis of AgNO₃ impregnated ZIF-8 precursor. Due to the bi-template function of ZIF-8, the as-prepared cages show well-defined hollow chamber inherited from the precursor and uniformly embedded Ag nanoparticles (NPs). The as-introduced Ag NPs could enhance the light absorption and promote charge separation, which finally improve the antibacterial performances. Therefore, compared with pure ZnO, the Ag/ZnO hybrid cages demonstrate prominent photocatalytic degradation of different organic dyes, such as Methylene Blue, Methylene Orange, Eosin and Rhodamine B under simulated sunlight. In addition, the hybrid Ag/ZnO cages exhibit outstanding inhibition performances against Escherichia coli, Staphylococcus aureus, and the highly infective Mycobacterium-tuberculosis. The photocatalytic and antibacterial mechanism of the hybrid Ag/ZnO cages were also studied in detail by means of optical/electrochemical dynamic tests and Ag⁺ and Zn²⁺ release measurements.     

Antibacterial and biodegradable properties of polyhydroxyalkanoates grafted with chitosan and chitooligosaccharides via ozone treatment

Acrylic acid was grafted to ozone‐treated poly(3‐hydroxybutyric acid) (PHB) and poly(3‐hydroxybutyric acid‐co‐3‐hydroxyvaleric acid) (PHBV) membranes. The resulting membranes were further grafted with chitosan (CS) or chitooligosaccharide (COS) via esterification. These CS‐ or COS‐grafted membranes showed antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, methicilin‐resistant Staphylococcus aureus (MRSA), and S. aureus. The antibacterial activity to E. coli was the highest, whereas the antibacterial activity to MRSA was the lowest among these four bacteria tested. Acrylic acid grafting can increase the biodegradability with Alcaligens faecalis, whereas CS and COS grafting can reduce the biodegradability. In addition, CS‐grafted PHBV membrane showed higher antibacterial activity and lower biodegradability than COS‐grafted PHBV membrane. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 12: 2797–2803, 2003     

Synthesis and Antimicrobial Activities of Oximes Derived from O-Benzylhydroxylamine as FabH Inhibitors

Forty‐three oxime derivatives were synthesized by allowing O‐benzylhydroxylamines to react with primary benzaldehydes or salicylaldehydes; these products were gauged as potential inhibitors of β‐ketoacyl‐(acyl‐carrier‐protein) synthase III (FabH). Among the 43 compounds, 38 are reported herein for the first time. These compounds were assayed for antimicrobial activities against Escherichia coli, Pseudomonas aeruginosa, Pseudomonas fluorescens, Bacillus subtilis, Staphylococcus aureus, and Enterococcus faecalis. Compounds with prominent antibacterial activities were tested for their E. coli FabH inhibitory activities. 3‐((2,4‐Dichlorobenzyloxyimino)methyl)benzaldehyde O‐2,4‐dichlorobenzyl oxime ( 44 ) showed the best antibacterial activity, with minimum inhibitory concentrations of 3.13–6.25 μg mL^?1 against the tested bacterial strains, exhibiting the best E. coli FabH inhibitory activity, with an IC₅₀ value of 1.7 mM . Docking simulations were performed to position compound 44 into the E. coli FabH active site in order to determine the most probable binding conformation.