Elena Kirkesali

Neutron activation analysis for studying Cr uptake in the blue-green microalga Spirulina platensis

Exposure of Spirulina platensis cells to Cr(III) and Cr(VI) showed that unlike other organisms this blue-green alga demonstrates a protective ability against Cr(VI). In laboratory experiments, the less toxic Cr(III) was absorbed much more readily than the more toxic Cr(VI). Colorimetric and EPR tests indicated that higher oxidation states of Cr are not formed following the accumulation of Cr(III) in Spirulina platensis cells. Control of the protein content and cytological study of the alga cells indicated that Spirulina platensis retains its natural properties after exposure to significant amounts of Cr(III).

GOLD AND SILVER NANOPARTICLES IN Spirulina platensis BIOMASS FOR MEDICAL APPLICATION

Abstract 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. Abstrakt Zbadano syntezę nanocząstek złota i srebra przez niebieskozielone glony Spirulina platensis, które są wykorzystywane do celów medycznych. Do scharakteryzowania wytworzonych nanocząstek zastosowano szereg metod optycznych i analitycznych. Wykazano, że zachodzi tworzenie pozakomórkowej, sferycznej nanocząstki o rozmiarach w zakresie od 8 do 40 nm (średnia wielkość 20-30 nm). Porównano charakterystyki nanocząstek złota i srebra wytworzonych w biomasie Spiruliny. Do oceny roli procesów biosorpcji w syntezie nanocząstek wykorzystano dializy równowagowe. Wykazano pozytywny wpływ ultradźwięków na procesy mikrobiologiczne i na wydajność syntezy nanocząstek. Do określenia dynamiki tworzenia nanocząsteczek złota i srebra w biomasie Spirulina platensis zastosowano neutronową analizę aktywacyjną i spektrometrię absorpcji atomowej. Stężenia pierwiastków w biomasie Spirulina platensis określono za pomocą neutronowej analizy aktywacyjnej

Epithermal neutron activation analysis in applied microbiology

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.

Nostoc Linckia as Biosorbent of Chromium and Nickel from Electroplating Industry Wastewaters

The present study relates to the use of cyanobacterium Nostoc linkia for removal of chromium and nickel from wastewater of galvanic industry. To determine concentrations of Cr and Ni in wastewater samples atomic absorption spectrometry was used. The samples of dried nostoc biomass after exposure to wastewater were subject to nondestructive instrumental neutron activation analysis. During 30 min of the contact of biomass with wastewater 84% of chromium was removed from the wastewaters. Beside chromium after 30 min nostoc biomass accumulates the amount of iron and zinc that exceeds their concentrations in the control biomass samples by a factor of 6 and 8, respectively. Nickel content in biomass after interaction with Cr-containing wastewater increases sixty fold and copper-sixteen fold. During the same time of biomass-Ni-containing wastewater interaction, 50% of nickel were accumulated. The method of Fourier transform infrared spectroscopy was applied to identify functional groups responsible for metal binding.