The methods of synthesis of silver (Ag) nanoparticles by the cyanobacteria Spirulina platensis and Nostoc linckia were studied. A complex of biochemical, spectral, and analytical methods was used to characterize biomass and to assess changes in the main components of biomass (proteins, lipids, carbohydrates, and phycobilin) during nanoparticle formation. The size and shape of Ag nanoparticles in the biomass of both types of cyanobacteria were determined. Neutron activation analysis was used to study the accumulation dynamics of the Ag quantity. The analytical results suggest that the major reduction of Ag concentration in solutions and the increase in biomass occur within the first 24 h of experiments. While in this time interval minor changes in the N. linckia and S. platensis biomass took place, a significant reduction of the levels of proteins, carbohydrates, and phycobiliproteins in both cultures and of lipids in S. platensis was observed after 48 h. At the same time, the antiradical activity of the biomass decreased. The obtained results show the necessity of determining the optimal conditions of the interaction between the biomass and the solution containing Ag ions that would allow nanoparticle formation without biomass degradation at the time of Ag nanoparticle formation by the studied cyanobacteria.
Tobacco-specific nitrosamines (TSNA) are among the most important and abundant strongly carcinogenic agents in unburned tobacco. It has been established that 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces lung tumors in rodents independent of the route of administration. N'-Nitrosonornicotine (NNN) causes tumors of the esophagus and nasal cavity in rats, lung in mice, and respiratory tract in hamsters. Although the manufacturing of cigarettes is an important domain of Moldovan industry, there are no reports in the literature on TSNA analysis in Moldovan tobacco. The main purpose of the present study was an initial evaluation of TSNA levels in Moldovan cigarette tobacco. Eighteen brands of Moldovan cigarettes, representing 78% of all brands produced in Moldova, were analyzed. Four TSNA-NNN, NNK, N'-nitrosoanatabine (NAT), and N'-nitrosoanabasine (NAB)-were analyzed by gas chromatography with nitrosamine selective detection (GC-TEA). Levels of TSNA in most Moldovan cigarettes were substantially lower than in American brands. Mean levels of NNN in three commercial American brands were 3.32 +/- 0.88 (SD) microg/g as compared to 0.579 +/- 0.548 microg/g, range 0.093-2.09 microg/g (N = 18), in the cigarettes produced in Moldova. For NNK and NAT, mean levels in the American brands were 1.57 +/- 0.178 and 1.99 +/- 0.579 microg/g, respectively, while the corresponding values for Moldovan cigarettes were 0.193 +/- 0.089, range 0.104-0.484 microg/g, and 0.160 +/- 0.114 microg/g, range 0.055-0.481 microg/g. The highest levels of NNN-1.10-2.09 microg/g-were observed in "American type" cigarettes manufactured from high-quality tobacco. The results of this study should be useful in heightening the awareness of the dangers of smoking in Moldova and can be envisioned as the initial step in the control of tobacco-related cancer in this republic.
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