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1.
Silver nanoparticles were covalently coated on a glass surface by overnight exposure of the glass substrate to nanoparticle solutions, using 3‐aminopropyltriethoxysilane (APTES) as a coupling agent. Washing and air‐drying yield a uniformly coated glass substrate, which can be used as a material capable of killing harmful microorganisms in food industry. Nanoparticles are stable on the glass surface and are not washed away by water; they even remain on the glass surface under short‐term ultrasonic irradiation. The morphology of silver nanoparticles on the glass substrate was characterized by scanning electron microscope (SEM). The existence of Ag nanoparticles on the substrate was also confirmed by ultraviolet‐visible (UV–Vis) spectroscopy. Fourier transform infrared (FT‐IR) measurement shows that the connection is based on covalent bonds between silver nanoparticle surface/APTES molecules. Combining the effects of low cost and effectiveness in prohibiting the growth of Escherichia coli, such materials are expected to be used as antibacterial coatings, which may have large potential applications in food industry. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

2.
《先进技术聚合物》2018,29(1):394-400
In the present study, cellulose acetate (CA) nanofibers were prepared by electrospinning technique. Alkaline hydrolysis was introduced for conversion of CA nanofibers to cellulose nanofibers. Nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). Furthermore, silver nanoparticles (AgNPs) were incorporated on regenerated cellulose nanofibers with different concentrations and used as an antimicrobial agent against Gram negative Escherichia coli BH5 α , Gram positive Spectromyces arenus, and Aspergillus flavus. Strong inhibition activities were determined.  相似文献   

3.
Copper nanoparticles (CuNPs) were biologically synthesized using peel extract of Punica granatum as reducing agent as well as capping agent. On treatment of aqueous solutions of CuSO4·5H2O with peel extract of P. granatum, stable CuNPs were formed. UV-Visible spectrophotometer analysis confirmed the formation of CuNPs. The synthesized nanoparticles were characterized with Fourier transform infrared spectroscopy, particles size analyzer and transmission electron microscopy (TEM). The electron microscopy analysis of CuNPs indicated that they ranged in size from 15 to 20?nm. The biologically synthesized CuNPs demonstrated high antibacterial activity against opportunistic pathogens, that is, Micrococcus luteus MTCC 1809, Pseudomonas aeruginosa MTCC 424, Salmonella enterica MTCC 1253 and Enterobactor aerogenes MTCC 2823 in vitro. Nanoparticles synthesized biologically using plant extracts have the potential to serve as possible ecofriendly alternatives to chemical and physical methods for biomedical applications and research.!  相似文献   

4.
Two polypyridyl ligands 6-fluro-3-(1H-imidazo [4,5-f] [1,10]-phenanthroline-2-yl)-4H-chromen-4-one (FIPC), 6-chloro-3-(1H-imidazo [4,5-f] [1,10]-phenanthroline-2-yl)-4H-chromen-4-one (ClIPC) polypyridyl ligands and their Ru(II) complexes [Ru(bipy)2FIPC]2+(1), [Ru(dmb)2FIPC]2+(2), [Ru(phen)2FIPC]2+(3), [Ru(bipy)2ClIPC]2+(4), [Ru(dmb)2ClIPC]2+(5) and [Ru(phen)2ClIPC]2+(6) ((bipy = 2,2′-bipyridine, dmb = 4,4′-dimethyl-2,2′-bipyridine and phen = 1,10-phenanthroline) have been synthesised and characterised by elemental analysis, Mass spectra, IR, 1H and 13C-NMR. The DNA-binding of the six complexes to calf-thymus DNA (CT-DNA) has been investigated by different spectrophotometric, fluorescence and viscosity measurements. The results suggest that 1–6 complexes bind to CT-DNA through intercalation. The variation in binding affinities of these complexes is rationalised by a consideration of electrostatic, steric factors and nature of ancillary ligands. Under irradiation at 365 nm, the three complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA. Inhibitor studies suggest that singlet oxygen (1O2) plays a significant role in the cleavage mechanism of Ru(II) complexes. Thereby, under comparable experimental conditions [Ru(phen)2FIPC]2+(3), [Ru(phen)2ClIPC]2+(6) cleaves DNA more effectively than 1, 2, 4 and 5 complexes do. The Ru(II) polypyridyl complexes (1–6) have been screened for antimicrobial activities.  相似文献   

5.
One new indole diterpenoid, drechmerin I (1), was isolated from the fermentation broth of Drechmeria sp. isolated from the root of Panax notoginseng. Its structure was elucidated based on 1 D and 2 D nuclear magnetic resonance (NMR), high resolution electrospray ionization mass spectrum (HRESIMS), and electronic circular dichroism (ECD) spectroscopic analyses as well as TD DFT calculations of ECD spectra. Drechmerin I (1) was assayed for its antimicrobial activity against Candida albicans, Staphylococcus aureus, Bacillus cereus, B. subtillis, Pseudomonas aeruginosa, and Klebsiella pneumonia, respectively. Drechmerin I (1) showed antimicrobial activities against B. subtillis with an MIC value of 200 μg/mL. The interaction of S. aureus peptide deformylase with drechmerin I (1) was investigated by molecular docking.  相似文献   

6.
The synthesis of 2-(substituted phenyl)-2-oxoethyl 4-(pyrimidin-2-yl)piperazin-1-carbodithiodate (A1-A24) derivatives and 2-(4-substituted thiazol-2-ylamino)-2-oxoethyl 4-(pyrimidin-2-yl)piperazin-1-carbodithiodate (B1-B14) derivatives was undertaken starting from the potassium salt of 4-(2-pyrimidinyl)piperazine dithiocarbamate. The structures of the obtained compounds were elucidated by 1H NMR, 13C NMR, MS spectral data, and elemental analysis. The antimicrobial activity of the thirty eight newly synthesized compounds were tested against 12 microorganism strains using the microdilution technique. Compounds 2-(4-ethoxycarbonylthiazol-2-ylamino)-2-oxoethyl 4-(pyrimidin-2-yl)piperazin-1-carbodithiodate (B12), 2-(3-fluorophenyl)-2-oxoethyl 4-(pyrimidin-2-yl)piperazin-1-carbodithiodate (A18) and 2-(3,4-difluorophenyl)-2-oxoethyl 4-(pyrimidin-2-yl)piperazin-1-carbodithiodate (A21) were determined to possess high antimicrobial activity.  相似文献   

7.
Fabrication of bioactive nanomaterials with improved stability and low toxicity towards healthy mammalian cells have recently been a topic of interest. Bioactive metal nanomaterials such as silver nanoparticles (AgNPs) tend to lose their stability with time and become toxic to some extent, limiting their biological applications. AgNPs were separately encapsulated and loaded on the surface of a biocompatible polydopamine (PDA) to produce Ag-PDA and Ag@PDA nanocomposites to unravel the issue of agglomeration. PDA was coated through the self-polymerization of dopamine on the surface of AgNPs to produce Ag-PDA core-shells nanocomposites. For Ag@PDA, PDA spheres were first designed through self-polymerization of dopamine followed by in situ reduction of silver nitrate (AgNO3) without any reductant. AgNPs sizes were controlled by varying the concentration of AgNO3. The TEM micrograms showed monodispersed PDA spheres with an average diameter of 238 nm for Ag-PDA and Ag@PDA nanocomposites. Compared to Ag@PDA, Ag-PDA nanocomposites have shown insignificant toxicity towards human embryonic kidney (HEK-293T) and human dermal fibroblasts (HDF) cells with cell viability of over 95% at concentration of 250 µg/mL. A excellent antimicrobial activity of the nanocomposites was observed; with Ag@PDA possessing bactericidal effect at concentration as low as 12.5 µg/mL. Ag-PDA on the other hand were only found to be bacteriostatic against gram-positive and gram-negative bacteria was also observed.  相似文献   

8.
A new composite cotton fabric with hydrogel containing silver nanoparticles (AgNPs) has been synthesized by two steps, and simultaneous in situ synthesis of AgNPs under visible light irradiation has been performed. The influence of silver nitrate concentration upon the hydrogel and AgNP properties was studied by colorimetric analysis, scanning electron microscopy, and transmission electron microscopy. The antibacterial activities of the composite materials have been investigated against Acinetobacter johnsonii and Escherichia coli in agar medium and meat-peptone broth. The results showed high inhibition activity toward both test cultures which were better expressed against A. johnsonii.  相似文献   

9.
Lycopus europaeus L. leaves water extract (LEL) was subjected to phytochemical analysis, and evaluated for its antibacterial and antioxidant effects. Antibacterial activity testing was performed on Staphylococcus aureus clinical strains from catheter-related and skin infections by broth microdilution test. LEL showed bactericidal activity at concentrations from 2500 to 5000 μg/mL against all, including methicillin resistant and polyresistant nosocomial, strains. Antioxidant activity was examined using DPPH and ABTS (11.3 and 9.8 μg/mL, respectively) and by ferric reducing ability of the plasma method (891 μmol AAE/g dry extract). Phytochemical analysis of LEL was performed by LC-DAD-MS/MS. Ten phenolic compounds were identified; two minor compounds (glucopyranosyl rosmarinic acid and sagerinig acid) have not been described in Lycopus yet. The major compounds, considered to be responsible for biological activities detected in the study, were determined as rosmarinic acid (76 mg/g) and luteolin-7-O-glucuronide (23 mg/g). L. europaeus arises from our study as a promising source of antibacterial agent for topical usage.  相似文献   

10.
In the current work, we followed a green chemistry route to prepare and characterize the silver nanoparticles (AgNPs) using Syzygium aromaticum (clove) extract at room temperature. Suitably, the clove extract acted as a reducing agent as well as a capping agent, and these reactions occurred rapidly. The formation of the AgNPs was confirmed by the observation of the distinct absorption peak at a wavelength of 418 nm using ultraviolet–visible (UV–Vis) spectroscopy, and a morphological study confirmed the uniform distribution of the optimally spherical nanoparticles. Fourier transform infrared spectroscopy (FTIR) results indicated the methoxy and allyl functional groups of eugenol of the clove extract to be responsible for the bioreduction of silver ions and for the stabilization of the resulting nanoparticles (flavonoids). We also found the AgNPs to be effective catalysts of the degradation of three pollutant organic dyes viz., 4‐nitrophenol, methylene blue and rhodamine B, in the presence of excess NaBH4. The antibacterial and antifungal activities of the bio‐synthesized AgNPs were also explored. Overall, the results suggested the potential use of clove extract as a resource for the synthesis of AgNPs having a broad range of possible commercial and biomedical applications.  相似文献   

11.
Polymer complexes of Co(II), Ni(II), Mn(II), Cr(III) and Cd(II) were prepared by the reaction of 3‐allyl‐5‐[(4‐nitrophenylazo)]‐2‐thioxothiazolidine‐4‐one (HL) with metal ions. The structure of polymer complexes was characterized by elemental analysis, IR, UV–Vis spectra, X‐ray diffraction analysis, magnetic susceptibility, conductivity measurements and thermal analysis. Reaction of HL with Co(II), Ni(II), Mn(II), Cr(III) and Cd(II) ions (acetate or chloride) give polymer complexes ( 1–5 ) with general stoichiometric [M(L)(O2CCH3)(H2O)2]n (where L = anionic of HL and M = Co(II) (1) or Ni(II) (2) ), [Mn(HL)2(OCOCH3)2]n (3) , [Cr(L)2(Cl)(H2O)]n (4) and [Cd(HL)(O2CCH3)2]n (5) . The value of HOMO–LUMO energy gap (ΔE) for forms (A‐C) of monomer (HL) is 2.529, 2.296 and 2.235 eV, respectively. According to ΔE value, compound has minimum ΔE is the more stable, so keto hydrazone form (C) is more stable than the other forms (azo keto form (A), azo enol form (B)). The interaction between HL, polymer complexes of Co(II), Ni(II), Mn(II), Cr(III) and Cd(II) with Calf thymus DNA showed hypochromism effect. The HL and its polymer complexes were tested against some bacterial and fungal species. The results showed that the Cr(III) polymer complex (4) has more antibacterial activity than HL and polymer complexes (1–3 and 5) against Bacillus subtilis, Staphylococcus aureus and Salmonella typhimurium.  相似文献   

12.
The reaction of S-benzyl dithiocarbazate (SBDTC) with 2,4,5-trimethoxybenzaldehyde afforded a bidentate NS Schiff base 1 (benzyl-3-N-(2,4,5-trimethoxyphenylmethylenehydrazine carbodithioate), which on further reaction with M(II) (where M(II) = nickel(II), zinc(II), palladium(II) and copper(II)) in ethanol under reflux yielded bis-chelated inner complexes [ML2] 25 with deprotonated L. The ligand and its complexes were characterized by physicochemical techniques, viz., molar conductance, magnetic susceptibility measurement, IR, NMR, UV–Vis and mass spectroscopic techniques. The crystal structures of 1 and 5 were also determined by single-crystal X-ray crystallography. The crystal structure analysis showed that the ligand exists in its thione tautomeric form. In the complexes, each of the two deprotonated ligands chelated the metal ions through the β-nitrogen and the thione sulfur forming five-membered rings. The copper(II) complex (5) exhibited a square-planar geometry, where the two N2S2 chromophores are arranged trans. All the compounds showed strong antibacterial activity against S.-β-hemolyticus, Klebsiella pneumoni, and Escherichia coli. The compounds also showed strong antifungal activity against Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, and Candida albicans with the exception of the palladium(II) complex (4) which showed no activity, while all the compounds showed no activity against Fusarium vasinfectum.  相似文献   

13.
A novel chalcone, namely 5‐(4‐(dimethylamino)phenyl)‐1‐(thiophen‐2‐yl)penta‐2,4‐dien‐1‐one, DMATP, and its complexes with nickel(II), vanadium(III), palladium(II) and platinum(II) metal ions were synthesized and characterized using a set of chemical and spectroscopic tools including elemental analysis, electrical conductance, magnetic susceptibility and spectral techniques. The interactions of the synthesized chalcone and its metal complexes with DNA were studied using steady‐state absorption and emission techniques as well as viscosity and electrochemical measurements. The obtained results confirm DNA intercalation. Additionally, theoretical studies were performed for all the investigated compounds using DFT/B3LYP calculations. The optimized geometries are found to be in good agreement with the suggested experimental structures. The bond lengths, bond angles, chemical reactivity, energy components, binding energy and dipole moment were evaluated. Also, theoretical infrared intensities and thermodynamic parameters for all compounds were calculated. Molecular docking calculations show that the Ni(II) complex exhibits the highest DNA binding activity, which agrees well with the experimental results. Finally, the compounds were screened for antimicrobial activity using several microorganisms.  相似文献   

14.
The silver nanoparticles OC-AgNPs, synthesized from the aqueous extract of Oxalis corniculata (OC), showed antiviral activity against Herpes Simplex Virus-1 (HSV-1), and anti-biofilm, and antibacterial activities against human isolates of six multi-drug resistant (MDR) bacteria - Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, and Pseudomonas aeruginosa. The OC-AgNP was characterized by UV-Vis and FTIR spectroscopy; while its morphology and distribution were determined by transmission electron microscopy (TEM). The results revealed that the biogenic OC-AgNPs are spherical with an average diameter of 40 nm and has shown UV-Vis peak at 445 nm. The cytotoxicity and safety of OC-AgNP has been evaluated by MTT assay in Vero cells and triple-negative human breast cancer MDA-MB-468 cells. The plaque reduction assay has been used to test the antiviral activity against HSV-1F. The anti-biofilm activity was assessed by crystal violet staining, followed by light and confocal microscopy; while the antibacterial activity was determined by conventional disk-diffusion and broth-dilution methods. Moreover, the mechanism of anti-biofilm and antibacterial activity was examined by Field Emission Scanning Electron Microscopy (FESEM). The CC50 (cytotoxicity) on Vero cells was 300 μg/ml; while the survival percentage of MDA-MB-468 cells was 27.12% at 20 μM and 80.97% at 100 μM of, respectively. The OC-AgNP showed moderate antiviral activity against HSV-1F at EC50 of 25 μg/ml; but significantly inhibited the biofilm produced by Pseudomonus aeruginosa and Escherichia coli at 25-50 μg/ml; while at 30-50 μM we observed the dose-dependent lowering of fluorescence intensity under light and confocal microscope. Interestingly, the OC-AgNPs demonstrated significant antibacterial activity against Pseudomonas aeruginosa (20 mm), Klebsiella pneumoniae (15 mm), Escherichia coli (12 mm), Salmonella typhi (10 mm), Streptococcus pyogenes (11 mm) and Staphylococcus aureus (10 mm) with Minimum Inhibitory Concentration (MIC) of 0.65–0.90 μM (0.11- 0.153 μg), respectively. Further, the FESEM micrograph showed disruption of membrane structure with the damage of cell membrane integrity of Pseudomonus aeruginosa at its MIC.  相似文献   

15.
Abstract

A series of new class of diethyl N-2-hydroxyethyl-N'-substituted phosphoramidimidates 6(a–e) and diethyl P-morpholino-N-substituted phosphonimidates 6(f–j) was synthesized. The precursor intermediates, diethyl substituted phosphoramidites 3(a–b) were prepared initially by a reaction of various amines 1(a–b) and diethyl phosphorochloridite (2) and then they were treated by in situ with aromatic/alkyl azides through Staudinger reaction to accomplish title products. Structures of all the synthesized compounds were characterized by spectroscopic data such as IR, NMR (1H, 13C, 31P), mass, and elemental analyses. The synthesized compounds were screened for their in vitro antimicrobial activity to understand their biological potency. The biological screening results disclosed that compounds 6b, 6c, 6e, 6g, 6h and 6j having potent antimicrobial activity against all the tested pathogens.  相似文献   

16.
Fenghua Li 《Talanta》2010,81(3):1063-5138
A water-soluble and electroactive composite - Pt nanoparticles/polyelectrolyte-functionalized ionic liquid (PFIL)/graphene sheets (GS) nanocomposite was synthesized in one pot. The structure and composition of the Pt/PFIL/GS nanocomposite were studied by means of ultraviolet-visible (UV-vis) and X-ray photoelectron spectra (XPS). Scanning electron microscopy (SEM) and transmission electron microscope (TEM) images reveal Pt nanoparticles are densely dispersed on the transparent thin PFIL-functionalized graphene sheets. The obtained Pt/PFIL/GS nanocomposite-modified electrode was fabricated to simultaneously determine ascorbic acid (AA) and dopamine (DA) by cyclic voltammetry. It is worthwhile noting that the difference between the two peak potentials of AA and DA oxidation is over 200 mV, which leads to distinguishing AA from DA. The detection of increasing concentrations of AA in the presence of DA and the oxidation of continuous addition of DA in the presence of AA were also studied using differential pulse voltammetry. The proposed sensor in real sample analysis was also examined in human urine samples. Three independent oxidation peaks appear in urine sample containing AA and DA. Therefore, the Pt/PFIL/GS nanocomposite might offer a good possibility for applying it to routine analysis of AA and DA in clinical use.  相似文献   

17.
Mondal P  Roy K  Bayen SP  Chowdhury P 《Talanta》2011,83(5):6924-1486
Polypyrrole nanoparticles of desired structure have been synthesized through simple micelle technique. It is then grafted with functionalized silica gel to develop a novel organic-inorganic hybrid material. The role of dimethyl dichloro silane (coupling agent) in grafting is demonstrated. The nanoparticles are characterized by TEM, SEM and TGA. Grafting reactions are evaluated by spectral (FTIR) analysis and chemical test. The Cr(VI) binding behavior of the composite is studied in various pH of the medium. The selectivity in binding Cr(VI) is monitored. The metal ion adsorption capacity and surface area of the material are found to be 38 mg/g and 235 m2/g, respectively.  相似文献   

18.
Zinc oxide nanoparticles have attracted significant interest in recent years due to their unique multifunctional chemical and physical properties along with their biological activities. This study demonstrated for the first time the biogenetic synthesis of zinc oxide nanoparticles by utilization of the methanolic extract of Hypericum triquetrifolium (HT). The obtained nanoparticles (HT-ZnO) were characterized by ultraviolet–visible spectroscopy (UV–Vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The shape of the resulted nanoparticles is fusiform nanoflowers with an average hydrodynamic size of 275.46 ± 0.20 nm and a zeta potential of −8.23 ± 0.26 mV. SEM micrographs revealed that HT-ZnO nanoflowers have a multi-process structure in which one of the processes is large and the others have similar smaller dimensions. The synthesized nanoflowers have an average length of 312.28 ± 78.93 nm and the tip of its processes has a width of 48.69 ± 9.71 nm. The antimicrobial activity of HT-ZnO nanoflowers was performed using microbroth dilution format. It showed a bactericidal mode of action against Gram-positive Staphylococcus aureus and Enterococcus faecalis with MIC/MBC values of 20 μg/mL and 5 μg/mL, respectively. MTT assay had revealed that HT-ZnO nanoflowers caused a dose-dependent decline in the viability of A549 adenocarcinomic human alveolar basal epithelial cells with an IC50 value of 20.45 μg/mL. The effect of HT-ZnO nanoflowers on the migration and colony formation abilities against the same cells was evaluated as well. In conclusion, zinc oxide nanoflowers were successfully synthesized using methanolic extract of H. triquetrifolium. The resulting particles showed a bactericidal effect against Gram-positiveS. aureus and E. faecalis and a cytotoxic activity against A549 cells.  相似文献   

19.
N-[5-(3-Aminopropylamino)-10-methyl-9H-benzo[a]phenoxazin-9-ylidene]ethanaminium chloride (Bze-NH2) was prepared and used as a precursor in the synthesis of new polycyclic cationic dyes. In addition to the potentiality of Bze-NH2 as a non-covalent fluorescent probe, the presence of a free amino group in its structure prompted us to study the application of this functionalised heterocycle in the covalent labelling of glycine and valine amino acids, as models of biomolecules. All compounds obtained showed strong absorbance and high emission at long-wavelengths (λem >640 nm). Furthermore, all benzo[a]phenoxazine derivatives synthesised were evaluated as antifungal agents against Saccharomyces cerevisiae, considering the commercial Nile Blue A (NB) as a lead compound. The results revealed that they exhibited good activity, which was usually superior to NB, the most effective compound displaying a minimum inhibitory concentration (MIC) value of 15 μM.  相似文献   

20.
Packaging of foods in high barrier materials is essential to attain food safety. Nanocomposite technology is leading in search of the earlier said kind of packaging materials. The role of zinc oxide (ZnO) loadings on poly(butylene adipate‐co‐terephthalate) (PBAT) structure were investigated, in addition to that packaging properties such as barrier, thermal, and mechanical properties were studied. Antimicrobial films are developed based on PBAT and ZnO nanoparticles. The nanocomposites exhibits a significant increase in the mechanical and thermal stability. The resulting PBAT/ZnO nanofilms show superior antimicrobial activity against Escherichia coli and Staphylococcus aureus. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

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