Silver nanoparticles characteristics

JIANG H, MANOLACHE s, LEE WONG A c and DENES F s, Plasma-enhanced deposition of silver nanoparticles onto polymer and metal surfaces for the generation of antimicrobial characteristics . Journal of Applied Polymer Science, 2004 93 1411-1422. 

Moyer et al. [41] demonstrated that the two dimensionally domain size of nanocrystalline carbon was found to be in the order of 10 nm. Additional spectroscopic Raman measurements on nanocrystalline carbon adsorbed at separate isolated silver nanoparticles revealed temporal fluctuations in the peak intensities of the characteristic carbon bands and intermittent on/off behavior [41]. The SERS literature (e.g., [5, 10, 11]) frequently reports this phenomenon, called blinking. Most authors interpreted the blinking that only few nanocrystallites were involved. 

Journal of Applied Polymer Science 93, No.3, 5thAug.2004, p.1411-22 PLASMA-ENHANCED DEPOSITION OF SILVER NANOPARTICLES ONTO POLYMER AND METAL SURFACES FOR THE GENERATION OF ANTIMICROBIAL CHARACTERISTICS Jiang H Manolache S Wong ACL Denes F S Wisconsin,University... 

To study particle correlation effects in the plasmon resonance absorption in the visible we have firstly compared the spectral characteristics of silver nanoparticles monolayers at the various particle surface concentrations o (Fig- ) The monolayer overlap parameter j = ngn d l4 was equal to 0.4 for the particle diameter of... 

Fig. 1 presents the UV-Vis absorption spectrum and TEM image of freshly formed 23 nm silver nanoparticles. The absorption peak appeared near 400 nm corresponds to the characteristic wavelength of silver absorbance. TEM data, the narrow width of the absorption peak and the dark yellow colour of final solution indicate the monodisperse silver nanoparticles. 

The advances in synthesis, characterization, and utilization of DNA-AuNPs have tempted researchers to synthesize DNA-modified silver nanoparticles (DNA-AgNPs). Silver nanoparticles arc attractive due to their smface plasmon resonance ( max = 410nm), catalytic activities, high extinction coefficient, and Raman enhancing properties. These properties, when combined with the chemical and physical characteristics derived from the dense DNA loading, are expected to make... 

UV/VIS-SPECTRA OF SILVER NANOPARTICLES AS CHARACTERISTICS OF THEIR SIZES AND SIZES DISTRIBUTION... 

On a basis of the comparative analysis of the references the correlated dependencies between the optical characteristics of aqueous sols of spherical nanoparticles and their diameter have been discovered. As a result, the empirical dependencies between the values of the square of wave frequency in the adsorption maximum of the surface Plasmon resonance and average diameter of the nanoparticles were determined as well as between the values of the adsorption band width on a half of its height and silver nanoparticles distribution per size. Proposed dependencies are described by the linear equations with the correlation coefficients 0.97 and 0.84, respectively. 

Empirical dependencies between the dimensional and optical characteristics of silver nanoparticles were determined. Such dependencies can be used for estimation of value of the average diameter and distribution per size of Ag-NPs without application of complicated equipment. 

In order to explain and to investigate the chemical process of the silver nanoparticles synthesis the kinetic characteristics have been investigated, namely the change of the concentration of the silver ions during the experiment. 

In order to identify the obtained silver nanoparticles, their spectral characteristics were investigated (Fig. 4, a). The spectrum of silver nanoparticles adsorption is characterized by one maximum corresponding to their spherical form. Analyzing the references [5-7], it was discovered that the value of the square of wave fiequency in adsorption maximum of the surface Plasmon resonance of silver nanoparticles linearly depends on their size (Fig. 4, b), that gives the possibilities to calculate an average diameter of the obtained silver nanoparticles. Calculated values of the average diameter of silver nanoparticles consist of 12 - 35 nm. 

Instead of precursor metal salts, metal oxides could also be used. Silver-PS coreshell particles were thus recently synthesized using a two-step procedure [346]. First, hydrogen reduction of a saturated silver(I) oxide solution at elevated temperature was carried out in the presence of commercial sulfate-functionalized PS particles (200 nm) used as support for the reduction of Ag salt into silver. The formed Ag nanoparticles were attached to the PS particles (Fig. 42a). Subsequent acetone treatment led to the encapsulation of the silver nanoparticles inside the PS spheres (Fig. 42b), accompanied by a red-shift of the characteristic plasmon resonance frequency of the particles (Fig. 42c). 

Banach et al., in Chapter 12, Synthesis, characteristics, and biocidal activity of silver nanoparticles, report an up-to-date overview about the fabrication and applications of silver nanoparticles in the biomedical field. 

Synthesis, characteristics, and biocidal activity of silver nanoparticles... 

During the process, color changes from colorless to light yellow and yellow-brown indicating the formation of silver nanoparticles. After the process, the samples were subjected to spectrophotometric analysis. UV-Vis spectra are shown in Figure 12.3. The peak at 400—450 nm corresponds to the characteristic surface plasmon resonance of silver nanoparticles. Table 12.1 presents the results of nanoparticle size analysis. 

Gold nanoparticles (Au-NPs) and silver nanoparticles (Ag-NPs) are of particular interest in DNA sensors and immunosensors due to their advantageous properties, such as hydrophilicity, standard fabrication methods, excellent biocompatibility, unique characteristics in the conjugation with biological recognition elements, and multiplex capacity for signal transducer. Therefore, a large number of published methods use Au- or Ag-NPs in DNA [16,17,18] protein [19] and even cell [20] electrochemical detection besides optical detections like ICP-MS [21] or their use as ELISA enhancer [22]. 

Nanoparticle penetration has been measured with a wide range of filter media by using silver nanoparticles from 3 nm to 20 nm at three different face velocities in order to define nanoparticle filtration characteristics of commercial fibrous filter media. After size classification by using a nano-DMA, the particle counts were measured by an ultrafine condensation particle counter (UCPC) both upstream and downstream of the test filter in order to determine the nanoparticle penetration for each specific... 

Recently, the production of nanofibres using nanocomposites has attracted attention. This is due to the fact that this type of nanofibre combines the unique properties of nanocomposites with the outstanding characteristics of nanofibres. Metal/polymer nanocomposites have not only the potential to meet the requirements of applications such as photonic and electric sensors, filters, and artificial tissue, but also can act as catalysts. Silver nanoparticles are the most common embedded metal nanoparticles used in conjunction with polymers. This is because silver nanoparticles exhibit remarkable properties including catalytic activity, surface-enhanced Raman scattering activity, high electrical conductivity and antimicrobial activity. 

Three different types of nanomaterials, based on their dimensional characteristics, are generally used to prepare polymer nanocomposites. These include nanomaterials with only one dimension in the nanometre range (e.g. nano-clay), those with two dimensions in the nanometre scale (e.g. carbon nanotubes) and those that have all three dimensions in the nanometre scale (e.g. spherical silver nanoparticles), as stated earlier. Thus nanosize thin layered aluminosilicates or nanoclays, layer double hydroxide (LDH), a large number of nanoparticles of metals and their oxides, carbon nanotubes and cellulose nanofibres are used as nanomaterials in the preparation of vegetable oil-based polymer nanocomposites. 

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