Synthesis, characterization and application of silver nanoparticles on a macroporous polymer support.

U ovoj doktorskoj disertaciji prikazan je postupak dobijanja nanočestica srebra (Ag) na umreženom makroporoznom kopolimernom nosaču poli(glicidilmetakrilatu-ko-etilenglikol dimetakrilatu) (poli(GMA-ko-EGDMA))...In this doctoral dissertation is provided a method of obtaining silver (Ag) nanoparticles on a crosslinked macroporous copolymer support poly(glycidylmethacrylate-co-ethyleneglycol dimethacrylate) (poli(GMA-co-EGDMA))..

Controlled synthesis and optical properties of Ag nanoparticles

Nanosized hydrophobic, oleylamine stabilized silver (Ag) organosols were obtained in the reaction between the related metal salt and oleylamine in various organic solvents. The obtained hydrophobic colloids are stable and retain same particles morphology even after solvent evaporation and redispersion of the dried deposit in chloroform. The sizes of the Ag nanoparticles can be controlled from 8 to 25 nm by reaction temperatures. The position and shape of the surface plasmon resonance band depends upon the size and shape of Ag nanoparticles as well as dielectric constant of the medium

Surface Plasmon Enhancement of Eu3+ Emission Intensity in LaPO4/Ag Nanoparticles

A promising way to improve the performance of luminescent materials is to combine them with noble metal nanoparticles. Herein, a set of silver/europium-doped lanthanum orthophosphate (Ag/La0.95Eu0.05PO4) nanostructures with different concentrations of silver nanoparticles were prepared and investigated. The presented overlap between the strongest europium (Eu3+) excitation line and the broad silver nanoparticle surface plasmon resonance makes the combination prospective for coupling. X-ray powder diffraction confirmed the monoclinic monazite structure. The transmission electron microscopy revealed particles with a rod-like shape and ~4 aspect ratio. Photoluminescence spectra show characteristic Eu3+ ion red emission. One of the requirements for an enhanced luminescence effect is the precise control of the distance between the noble metal nanoparticles and the emitter ion. The distance is indirectly varied throughout the change of Ag nanoparticle concentration in the La0.95Eu0.05PO4 host. The emission intensity increases with the increase in Ag nanoparticles up to 0.6 mol %, after which the luminescence decreases due to the nanoparticles’ close packing and aggregation leading to the displacement of La0.95Eu0.05PO4 from the vicinity of the metal particles and reabsorption of the emitted light. The emission intensity of La0.95Eu0.05PO4 increases more than three times when the Eu3+ excitation is supported by the localized surface plasmon resonance in the Ag/La0.95Eu0.05PO4 nanostructures

The antimicrobial activity of triangular silver nanoplates on cotton fabric pretreated with chitozan

Triangular silver nanoplates are a type of most-studied noble-metal nanostructures over the past decade, owing to their special structural architecture, outstanding plasmonic features across both visible and IR regions, and catalytic properties for a wide range of applications. Herein, we used these nanoparticles to deposit on cotton (Co) fabric pretreated with biopolymer chitosan (CHT) and investigated their antimicrobial activity. The antimicrobial efficiency of the coated fabrics was evaluated toward Gram-negative bacteria E. coli, Gram-positive bacteria S. aureus and fungus C. albicans. It was found that deposited silver nanoparticles imparted excellent antimicrobial properties to Co fabric

Synthesis, characterization and application of silver nanoparticles on a macroporous polymer support.

U ovoj doktorskoj disertaciji prikazan je postupak dobijanja nanočestica srebra (Ag) na umreženom makroporoznom kopolimernom nosaču poli(glicidilmetakrilatu-ko-etilenglikol dimetakrilatu) (poli(GMA-ko-EGDMA))...In this doctoral dissertation is provided a method of obtaining silver (Ag) nanoparticles on a crosslinked macroporous copolymer support poly(glycidylmethacrylate-co-ethyleneglycol dimethacrylate) (poli(GMA-co-EGDMA))..

Size‐dependent antibacterial properties of Ag nanoparticles supported by amino‐functionalized poly(GMA‐ co ‐EGDMA) polymer

Size-dependent antimicrobial ability of silver nanoparticles (Ag NPs) supported by amino-functionalized poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (poly(GMA-co-EGDMA)) macroporous copolymer was tested against Gram-negative bacteria Escherichia coli. Inorganic/organic hybrids with distinctly different average sizes of Ag NPs (6.6 and 12.1 nm) were prepared by functionalization of poly(GMA-co-EGDMA) with either 1,8-diaminooctane or ammonia, and consequent reduction of silver ions with amino groups. The transmission electron microscopy (TEM), infrared and UV–Vis reflection spectroscopy, elemental analysis, and inductively coupled plasma atomic emission measurements were used to characterize synthesized hybrid materials. Time- and concentration-dependent antimicrobial performances of prepared samples revealed higher reduction rates of E. coli when hybrid with smaller in size Ag NPs was used. The difference between rates of reduction of E. coli for different size Ag NPs is becoming more pronounced by decrease of the concentration of silver. POLYM. COMPOS., 2018. © 2018 Society of Plastics Engineers. © 2018 Society of Plastics Engineer

Synthesis, Characterization, and Antimicrobial Activity of Silver Nanoparticles on Poly(GMA-co-EGDMA) Polymer Support

Poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (poly(GMA-co-EGDMA) macroporous copolymer decorated with silver nanoparticles was prepared by a modification of poly(GMA-co-EGDMA) in the reaction with arginine, and consequent reduction of silver ions with amino groups. The mercury intrusion porosimetry, transmission electron microscopy, X-ray diffraction, UV-vis reflection spectroscopy, and inductively coupled plasma atomic emission measurements were used to characterize obtained composite. The coordination of silver nanoparticles to the poly(GMA-co-EGDMA) copolymer was studied using infrared spectroscopy. Time dependence and concentration dependence of the antimicrobial efficiency of composite were tested against Gram-negative bacteria Escherichia coli, Gram-positive bacteria Staphylococcus aureus, and fungus Candida albicans. The composite ensured maximum reduction of both bacteria, while the fungi reduction reached satisfactory 96.8%. Preliminary antimicrobial efficiency measurements using laboratory flow setup indicated potential applicability of composite for wastewater treatment

Visible-light-responsive Al2O3 powder: Photocatalytic study

A visible-light-responsive hybrid material was prepared by surface-modification of γ-Al2O3, an insulator with a bandgap of about 8.7 eV, with 5-aminosalicylic acid (5-ASA), leading to the formation of an interfacial charge transfer (ICT) complex. The microstructural characterization of pristine γ-Al2O3 includes X-ray diffraction analysis, transmission electron microscopy, and nitrogen adsorption-desorption isotherms. The pristine γ-Al2O3 powder consists of agglomerated rod-like nanoparticles ((2-3) × (15-20) nm, diameter × length) with the large specific surface area (~420 m2/g). An enormous absorption red-shift is observed upon the formation of the ICT complex. The absorption onset of the inorganic-organic hybrid was found to be at 730 nm by diffuse reflection spectroscopy. The photocatalytic performance of prepared samples was thoroughly tested using the decolorization of the organic dye crystal violet (CV) under illumination in different spectral regions and different light intensities. Excitation with UV light leads to complete decolorization of CV, while the degradation kinetics are impeded when a visible light source is used. Also, the increase of UV light intensity induced significantly faster degradation kinetics of CV, while the degradation rates of CV are quite insensitive to the increase of visible light intensity

Characterization of silver/polystyrene nanocomposites prepared by in situ bulk radical polymerization

Nanocomposites (NCs) with different content of silver nanoparticles (Ag NPs) embeded in polystyrene (PS) matrix were prepared by in situ bulk radical polymerization. The nearly monodisperse Ag NPs protected with oleylamine were synthesized via organic solvo-thermal method and further used as a filler. The as-prepared spherical Ag NPs with diameter of 7.0 +/- 1.5 nm were well dispersed in the PS matrix. The structural properties of the resulting Ag/PS NCs were characterized by transmission electron microscope (TEM) and Fourier transform infrared (FTIR) spectroscopy, while optical properties were characterized using optical absorption measurements. The gel permeation chromatography (GPC) measurements showed that the presence of Ag NPs stabilized with oleylamine has no influence on the molecular weight and polydispersity of the PS matrix. The influence of silver content on the thermal properties of Ag/PS NCs was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicated that resistance of PS to thermal degradation was improved upon incorporation of Ag NPs. The Ag/PS NCs have lower glass transition temperatures than net PS because loosely packed oleylamine molecules at the interface caused the increase of free volume and chain segments mobility near the surface of Ag NPs

Dextran coated silver nanoparticles Chemical sensor for selective cysteine detection

A simple, fast and non-costly method for selective cysteine (Cys) detection, based on optical changes of silver colloids, is developed. For that purpose, stable colloids consisting of silver nanoparticles (Ag NPs) coated with polysaccharide dextran (Dex), isolated from bacterium species Leuconostoc mesenteroides T3, were prepared. The synthesized samples were thoroughly characterized including absorption and FTIR spectroscopy, as well as transmission electron microscopy and X-ray diffraction analysis. The silver colloids display high sensitivity and selectivity towards Cys detection in aqueous solutions. The Ag NPs coated with Dex provide possibility to detect Cys among a dozen amino acids and its detection limit was found to be 12.0 M. The sensing mechanism - red shift of optical absorption - is discussed in terms of the agglomeration of Ag NPs due to formation of hydrogen bonds between Cys molecules attached to different Ag NPs