Biochemical changes in cyanobacteria during the synthesis of silver nanoparticles

Abstract

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.

Biochemical Changes in Nostoc linckia Associated with Selenium Nanoparticles Biosynthesis

“…After 48 h, the carbohydrate content in Nostoc Time biomass was reduced by 11%, without further change, indicating the protective function of exolysaccharide. Similar results were obtained for silver nanoparticles biosynthesis [22].…”

“…The data obtained by NAA for silver nanoparticles synthesis by N. linckia illustrated the rapid increase of silver concentration in the biomass without significant further changes [22]. In the case of SeNPs formation, the NAA data (Fig.…”

“…This phenomenon of "finer" Nostoc biomass component degradation is maintained also for proteins, whose content during silver nanoparticle formation was reduced by 45% in the first 48 h of reaction [22]. Protein reaction during the process of selenium nanoparticles formation was rather different (Fig.…”

“…Thus, the inconspicuous damage of the cell membrane leads to the decrease of the phycobilin content. In the experiment of silver nanoparticle synthesis, Nostoc biomass lost 86% of phycoerythrin content in the first 24 h. After 72 h, phycoerythrin content decreased by 92% [22]. Therefore, Nostoc affinity to selenium is manifested in a slower manner in comparison with that of the silver [22] phycobilin pigment degradation process.…”

“…Results presented in Figure 7 show that in in the first 48 h of reaction with selenite ions, the lipid content changed unsignificantly by 15%, while after 72 h no decrease was observed. For silver nanoparticles after 72 h, the content of lipids changed only by 9.7% [22]. To assess the activity of functional components of Nostoc biomass in the process of nanoparticle synthesis, the antioxidant tests of ABTS radical reduction were applied.…”