ABSTRACT
Gold nanoparticles have found many applications in cancer diagnosis and therapy, drug and gene delivery and DNA and protein characterizations. Fungi are extremely good candidates in the synthesis of metal nanoparticles because of their ability to secrete large amounts of enzymes. The aim of this study was biosynthesis of gold nanoparticles by a fungus. The sampling was performed from the Ahar copper mine. The biomasses of isolated fungi were incubated with HAuCl[4] solution in a shaker-incubator for 72 hr, and the strains that were able to produce gold nanoparticles were identified. The production of gold nanoparticles was studied with UV-vis spectroscopy, X-ray diffraction [XRD] and transmission electron microscopy [TEM]. Among the eight types of fungi that were isolated from the Ahar copper mine, only Rhizopus oryza was able to synthesize gold nanoparticles. The synthesis of gold nanoparticles was confirmed by observing the characteristic peak at 540 nm using UV-vis spectroscopy. The XRD analysis confirmed that the produced gold nanoparticles are in the form of nanocrystaline. Transmission electron microscopy images showed that Rhizopus oryza produces gold nanoparticles with good monodispersity in spherical and trigonal shapes both intra- and extracellularly. Fungus Rhizopus oryza is able to produce gold nanoparticles in the size range of 10-70 nm. This biologic method has the potential to replace chemical and physical methods currently used for gold nanoparticles production
ABSTRACT
In this article the heavy metal concentrations in atmospheric wet precipitation and its relationship with the particles [PM[10]] in the air of the city of Zanjan are reported. Two hundreds samples of rain water and snow were collected with 45 particle samples collected monthly. Heavy metals in wet and dry samples were determined by atomic absorption spectrophotometery. The use of enrichment factors and correlation coefficients allowed us to predict the major sources of these metals. The ranges of concentration of Pb, Zn, Cr and Cd in rain water [micro g/L] were 5.8-22.2, 29.26-70, 1.4-4 and 0.25-1.2, respectively. The results showed that the concentrations of Pb, Zn, Cr and Cd in wet precipitation and [PM[10]] in samples collected in southern parts of the city where the traffic load and industrial activities are very high [zone 4], were 22.2, 70, 1.2 and 4 [micro g/L] and 840, 16233, 32 and 54.8 [ng/m[3]], respectively. These values were higher than those measured in the other parts of the city. Most of the calculated enrichment factors higher than 10 were attributed to the traffic and industrial activities. The enrichment factor and correlation coefficient values showed that the heavy metals in the air of Zanjan originate from similar sources. The concentration of particulate matter in 30 air samples of total 45 samples were found to be higher than 50 micro g/m[3]. The average concentrations of Pb and Cd in the city center and near the industrial complexes were higher than World Health Organization standards