The Effect of Gold Salt Concentration in the Production of Gold Nanospheres (original) (raw)
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Colloidal gold nanoparticles (spheres) have been prepared from HAuCl4 containing aqueous solution by using X-ray irradiation and by chemical reduction method. Gold nanorods were synthesized according to the seed-mediated growth method. The colloidal gold nanoparticles were characterized by using transmission electron microscopy, X-ray diffraction, and UV-VIS absorption spectroscopy. It was found that the concentration of the precursors affects the size of the nanoparticles. In the chemical reduction approach the size of nanoparticles can be controlled by varying amount of trisodium citrate, but in the photochemical method the size of nanoparticles can been controlled by varying the ratio of HAuCl4 to TX-100 and X-ray irradiation duration. Gold nanorods have been synthesized according to the seed-mediated growth method with two steps. The effect of silver acetate and CTAB on formation of gold nanorods has been studied.
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AuNPs (Gold Nanoparticles) are used in resonance scattering dark-field microscopy for the detection of microbial cells and their metabolites the bio-imaging of tumor cells and for the detection of receptors on their surface and for the study of endocytosis. They are small gold particles with a diameter of 1 to 100 nm which, once dispersed in water, are also known as colloidal gold. Spherical AuNPs possess useful attributes such as size-and shape-related optoelectronic properties, large surface-to-volume ratio, excellent biocompatibility, and low toxicity. These properties make AuNPs an important tool in bionanotechnology.
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Open Journal of Physical Chemistry, 2012
A comprehensive investigation on the formation mechanism of gold nanoparticles (AuNPs) in colloidal mixture obtained from the reduction of chloroauric acid (HAuCl 4) solution using a single reducing agent (sodium citrate; process-I), (tannic acid; process-II), and a combination of two reducing agents (sodium citrate plus tannic acid; process-III) is reported. The growth steps at different time intervals during synthesis of colloidal AuNPs were monitored in situ and ex situ using various methods for all the three processes. The measurement of changes in the surface plasmon band position of colloidal AuNPs, along with dynamic light scattering results gave important information for the first assessing of particle size, shape and distribution. Besides, the size and morphological changes at different stages during different processes were also analyzed by transmission electron microscopy. The final Au particles of processes-I & II exhibited different shapes (spherical and nanowires) with particle size and nano wire diameter of 12 nm and 17 nm, respectively. Nevertheless, combination of two reductants (process-III) surprisingly leads to drastically reduced size (ca. 3 nm) with spherical morphology compared to their parent solutions with either of single reducing agent. This result clearly indicates that the combination of reductants has a significant influence on the particle size, morphology and formation mechanism.
pH Dependence of Size Control in Gold Nanoparticles Synthesized at Room Temperature
Oriental Journal of Chemistry, 2018
We have developed the spherical gold nanoparticles (AuNPs) with different size at room temperature using L-ascorbic acid as a reducing agent. Controlling pH of L-ascorbic acid from 2.0 to 10.0 caused the decreasing of AuNPs size when measured using particle size analyzer. The alkaline condition leads to increase the reactivity of L-ascorbic acid even at room temperature. The homogeneous AuNPs were achieved even the synthesis was conducted at different pH of L-ascorbic acid (pH 2.0 to 12.0). The investigation using Transmission Electron Microscopy (TEM) confirmed that AuNPs performed a spherical shape. SEM-EDX measurement performed a strong characteristic peak of Au appeared at 2.0 keV. This research could be used to control of AuNPs size when synthesized at room temperature. The AuNPs obtained at optimum condition was stable up to 3 months.