Some results from applying epithermal neutron activation analysis at FLNP JINR, Dubna, Russia, in medical biotechnology, environmental biotechnology and industrial biotechnology are reviewed. In the ...biomedical experiments biomass from the blue-green alga
Spirulina platensis
(
S. platensis
) has been used as a matrix for the development of pharmaceutical substances containing such essential trace elements as selenium, chromium and iodine. The feasibility of target-oriented introduction of these elements into
S. platensis
biocomplexes retaining its protein composition and natural beneficial properties was shown. The absorption of mercury on growth dynamics of
S. platensis
and other bacterial strains was observed. Detoxification of Cr and Hg by
Arthrobacter globiformis
151B was demonstrated. Microbial synthesis of technologically important silver nanoparticles by the novel actinomycete strain
Streptomyces glaucus
71 MD and blue-green alga
S. platensis
were characterized by a combined use of transmission electron microscopy, scanning electron microscopy and energy-dispersive analysis of X-rays. It was established that the tested actinomycete
S. glaucus
71 MD produces silver nanoparticles extracellularly when acted upon by the silver nitrate solution, which offers a great advantage over an intracellular process of synthesis from the point of view of applications. The synthesis of silver nanoparticles by
S. platensis
proceeded differently under the short-term and long-term silver action.
The time-dependent biosorption capacity of the cyanobacterium Spirulina platensis was studied in regards to nickel and chromium removal from the industrial effluents of electroplating units. The ...elemental content of the S. platensis biomass and the metal concentrations of industrial effluents were traced through two analytical techniques, neutron activation analysis and atomic adsorption spectrometry, respectively. A rapid rate of chromium adsorption (initial concentration 9.4 mg/L) was observed within the first 15 min of the reaction. Furthermore, a high amount of iron (48%) and nickel (94%) was removed from the chromium containing industrial effluents by the spirulina biomass. During a 1 h period of the reaction, the biomass of cyanobacterium accumulated from the nickel containing industrial effluents 66% of the initial nickel content (14.1 mg/L), 52% of the initial iron, 30% of the initial zinc, and 50% of the intial barium content. Fourier transform infrared spectroscopy was used to identify functional groups responsible for metal binding.
The synthesis of gold and silver nanoparticles by the blue-green algae Spirulina platensis for medical purposes was studied. A complex of optical and analytical methods was used in order to ...characterize produced nanoparticles. It was shown that the extracellular formation of metal nanoparticles of spherical shape with sizes in the range between 8 and 40 nm (the average size of 20-30 nm) takes place. The characteristics of gold and silver nanoparticles in the Spirulina biomass were compared. The role of biosorption processes in the synthesis of nanoparticles was estimated by using equilibrium dialysis. A positive influence of sonication on the process of microbial synthesis and yield of nanoparticles were demonstrated. The neutron activation analysis and the atomic absorption spectrometry were applied for characterizing the dynamics of gold and silver nanoparticles formation in the Spirulina platensis biomass. The neutron activation analysis was used for studying the elemental content of the Spirulina platensis biomass.
Epithermal neutron activation analysis (ENAA) has been applied to study elemental composition of Cr(VI)-reducer bacteria isolated from polluted basalts from the Republic of Georgia. Cr(VI)-reducing ...ability of the bacteria was examined by electron spin resonance, demonstrating that the bacteria differ in their rates of Cr(VI) reduction. A well-pronounced correlation between the ability of the bacteria to accumulate Cr(V) and their ability to reduce Cr(V) to Cr(III) observed in our experiments is discussed. Elemental analysis of these bacteria also revealed that basalt-inhabiting bacteria are distinguished by relative contents of essential elements such as K, Na, Mg, Fe, Mn, Zn, and Co. A high rate of Cr(III) formation correlates with a high concentration of Co in the bacterium. ENAA detected some similarity in the elemental composition of the bacteria. The relatively high contents of Fe detected in the bacteria (140−340 μg/g of dry weight) indicate bacterial adaptation to the environmental conditions typical of the basalts. The concentrations of at least 12−19 different elements were determined in each type of bacteria simultaneously starting with the major to ultratrace elements. The range of concentrations spans over 8 orders of magnitude.
The synthesis of gold nanoparticles by two novel strains of Arthrobacter sp. 61B and Arthrobacter globiformis 151B isolated from basalt rocks in Georgia was studied. The complex of optical and ...analytical methods was applied for investigation of experimental samples after exposure to gold chloroaurate （HAuC14） for different time intervals. To characterize formed gold nanoparticles UV-Vis spectrometry, Transmission electron microscopy （TEM）, Scanning electron microscopy （SEM）, Energy-dispersive analysis of X-rays （EDAX）, and X-ray diffraction （XRD） were used. It was shown that after 1.5-2 days the extracellular formation of nanoparticles of spherical form with size in the range of 8-40 nm （on average of 20 nm） took place. To determine gold concentrations in the bacterial biomass neutron activation analysis （NAA） and atomic absorption spectrometry （AAS） were applied. The results obtained evidence that the concentration of gold accumulated by bacterial biomass is rapidly growing in the beginning followed by an insignificant increase during the next few days.
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