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
Due to importance of ionizing radiation on human health, many studies have been performed to measure the background gamma radiation all around the world as well as some cities in lran. This study was carried out to measure the amount of background gamma radiation in outdoor areas in different seasons in Zanjan to determine the annual effective dose of the city residents. To determine the dose rate of background gamma radiation in outdoor areas, 8 stations [4 in the main directions and 4 in the downtown areas] were selected using the map of the city. Eight measurements were performed for each station [twice in each season] using Geiger-Muller detector [RDS-110] calibrated by Cs-137. The mean value of dose rate and the annual effective dose due to background gamma radiation in different season in Zanjan were determined 126 nGy/h and 0.15 mSv respectively. The minimum and maximum mean values of dose rate were found 120 +/- 21 nGy/h and 134 +/- 18 nGy/h in summer and spring respectively. The results show that the dose rate and the annual effective dose for the city residents due to the background gamma radiation in outdoor areas is twice as much as international mean value reported by UNSCEAR-2000. To determine the total annual effective dose of Zanjan residents, measuring the dose rate in indoor areas is necessary