فهرست مطالب سعید قربانزاده مشکانی

Aims: In recent years, magnetotactic bacteria and their magnetic nanoparticles (magnetosomes) were considered in different fields of science, including medicine, biotechnology, and nanobiotechnology due to their novel and unique magnetic properties. The present study was performed with the aim of evaluating the effect of temperature and reducing agent on labeling of magnetosomes with 188Re and biodistribution of labeled magnetic nanoparticles. In this experimental study, Alphaproteobacterium MTB-KTN90 and sonication extraction method were used for the extraction of magnetic nanoparticles. After bacterial lysis, the magnetic nanoparticles produced by electron microscope were investigated and tin (II) chloride, as reducing agent, was used to check the labeling efficiency and rats were used to examine the biodistribution of the labeled magnetosomes. Findings: The highest efficiency in magnetosome labeling experiments was 11100kBq in the initial activity, which decreased with increasing activity. The increase in temperature did not have much effect on increasing the labeling efficiency. The labeling value in the absence of a reducing agent was 721.5kBq, while at a concentration of 2mg of this agent, the labeling value increased to 10745.91kBq. After the injection of magnetosomes through the sublingual vein of the rat, the magnetosomes accumulated in the liver. Magnetosomes extracted from Alphaproteobacterium MTB-KTN90 have a high potential for labeling by 188Re. Increasing temperature does not affect the labeling efficiency, but tin (II) chloride is a very important factor in optimizing the labeling efficiency, and the highest accumulation of magnetosomes labeled with 188Re after injection is in the liver of the rat.

In this study, the production of labeled vitamin B12 with one strain of actinomycet in a novel synthetic medium by batch fermentation method was investigated. After releasing vitamin B12 from microbial cells, the solution containing cobalamin analogues was fixed on amberlite XAD-4 exchanger and eluted by various solutions. Vitamin B12 in the collected fractions were measured by HPLC method and also in order to confirm the existence of cobalamin compounds in the samples, TLC technique was used. In the optimal conditions, production of vitamin B12 by this microorganism was 1456µg/l. The best recoveries of vitamin B12 from the column were obtained when the column was eluted by ethanol followed by acetone. The Rf values for cyanocobalamin and methylcobalamin, produced by this microorganism were the same as the standard values of Rf. The desorption of labeled vitamine B12 was carried out by different eluants, including acetone, ethanol (absolute), ethanol 25% and deionized water. The activity of labeled vitamin B12 was 8.55, 6.90, 0.79, 5.75 Bq/ml, respectively. Therefore, the total specific activity of 21.99Bq/ml was obtained for labeled vitamin B12.

One of the most important application of rhenium is its use in nuclear medicine.The recovery of rhenium via biosorption by micro-organisms, in contrast to other methods, has not been investigated yet. In the present study the biosorption of rhenium on Bacillus sp. MGG-83 in a batch of stirred system is reported, and its optimum condition has been determined. The optimum pH-value of the medium was found to be 2 for rhenium. The maximum biosorption of rhenium was obtained at a temperature between 35–40 0C. The rhenium take up increases by increasing the rhenium concentration, and for 250 mg/l the take up was 146.3 mg/g dry wt. The uptake of rhenium within 5 min of incubation is relatively rapid and the continuation of absorption behaves slowly thereafter. The reduction in the V/X0value causes an increase of the adsorbed rhenium and that is due to the increase of the adsorption surface area. The desorption of rhenium which has been carried out with 0.1 M sodium hydroxide at 25 0C was 55%.