Physical Properties of Different Gold Nanoparticles: Ultraviolet-Visible and Fluorescence Measurements

Abstract

Background: The light absorption and emission characteristics of Gold Nanoparticles (GNPs) are exploited in detection and treatment of cancer. The properties of Nanoparticles (NPs) give them high potential for use in various medical applications, particularly in diagnostics and therapy where they promise increased sensitivity, speed, and costeffectiveness. The Ultraviolet-Visible and fluorescence properties of non-functionalized GNPs have not thus far been comprehensively documented. This study evaluated the absorption and fluorescence spectra for solutions of GNPs at different concentrations. Methods: The mean sizes of these GNPs were calculated from Transmission Electron Microscope (TEM) images, which were also used to study the morphology of the GNPs. UV-Visible and fluorescence measurements, were made from 250-700 nm using 1 cm quartz cuvettes. Results: When the GNP size changed from 10 nm to 50 nm, the maximum extinction of the Surface Plasmon Band (SPB) shifted from 517 nm to 532 nm in the visible region which may be attributed to the surface plasmon oscillation of free electrons. At constant GNP size, the absorbance was found to be proportional to the concentration of gold. This is because an increased number of GNPs also increases the total surface for surface plasmon resonance. The Photoluminescence (PL) band centre appears at 423 nm. An increase in fluorescence intensity with increase in GNP size was observed. At a fixed GNP size of 10 nm, and with increasing GNP concentration, the intensity of the emission band increased, which was consistent with the changes observed for the surface plasmon band of GNPs. Conclusions: The absorption intensity and maxima are particle size dependent. The surface plasmon resonance of the gold particles is red shifted (from 517 to 532 nm) with increasing particle size. These results indicate that the fluorescence intensity and the absorption band of GNPs were concentration and particle size dependent.

Electrochemical synthesis, characterisation and phytogenic properties of silver nanoparticles

“…Nanomaterials are gaining interest and prominence due to their many new-fangled properties in contrast to that in traditional bulk materials. Among the metal nanoparticles (NPs), transition metal NPs, in particular the nanoparticles of cobalt (Farhadi and Safabakhsh 2013), nickel (Abdelhalim et al 2012;Huang et al 2007Au, He et al 2013Nejati and Zabihi 2012;Wang et al 2008), palladium (Xiong et al 2005;Jana et al 2000); platinum (Roldan Cuenya et al 2011;Zhang et al 2008), gold (Merza1 et al 2012) and titanium (Mishra et al 2010), have attracted much attention of the researchers for a long time due to their size-induced properties and application-oriented importance in many industries as well as in advanced technologies. Among these transition metal nanoparticles, silver nanoparticles (Ag NPs) have been extensively studied due to their surface enhanced properties with fascinating structures and unique electrical, chemical, optical and antimicrobial properties.…”

Synthesis of Ni nanoparticles with controllable magnetic properties by atmospheric pressure microplasma assisted process

“…First, the effect of discharge power was investigated, when the plasma power was varied from 1.3 to 3.4 W while keeping a constant precursor concentration (35 ppm, condition 1-4). Next, the influence of precursor concentration was studied by operating the plasmas in the same power range but with half the precursor concentrations (17.5 ppm, condition [5][6][7][8]. The typical procedure was as follows: a discharge was ignited in pure argon.…”

“…For example, the surface plasmon resonance of gold nanoparticles shows a red shift with increasing particle size, resulting in a considerable variation in optical properties. 6 Iron oxide nanoparticles of maghemite structure (c-Fe 2 O 3 ) show excellent superparamagnetic behavior, in contrast to the antiferromagnetic nature of hematite (a-Fe 2 O 3 ). 7 Also, the hyperthermia therapy efficacy of Ni nanoparticles is affected by several parameters: (1) Composition.…”

Rapid Synthesis of Gold Nanoparticles from Quercus incana and Their Antimicrobial Potential against Human Pathogens

“…Nanoparticles showed thermal stability ( Figure 3), but increase in absorption was observed after heating. The notable difference in UV-vis spectra for the synthesized GNPs was a change in the height of the peaks (which may relate to the number of the nanoparticles produced, as the optical density (OD) value correlates linearly with the concentration of the gold nanoparticles) [40]. The increase in absorption was due to their uniform distribution in size and small size [41].…”