engleski

The effects of silver nanoparticles and ions on Chlorella vulgaris

Silver nanoparticles (AgNPs) are well known for their antimicrobial properties in many commercially available products, but due to their toxicity and reactivity, they can pose a risk to the aquatic environment. The model photosynthetic eukaryotic organism, Chlorella vulgaris, was used in this study. To evaluate the effect of AgNPs stabilized with polyvinylpyrrolidone (AgNP-PVP) and silver ions (AgNO3) on the microalgae, their growth, lipid peroxidation and catalase activity were measured upon their exposure to 0.5, 1.0, 1.5 and 2.0 ppm concentrations after 5, 24 and 48 hours in the modified liquid BBM nutrient medium. Additionally, the changes of pH, levels of dissolved oxygen and absorbance spectre in the range of 300-800 nm in the algae culture were analysed after the same period of treatment. Since stress conditions negatively affect ribulose bisphosphate carboxylase (Rubisco) protein synthesis, we used immunoblotting assay to analyse the expression levels of the large Rubisco chain to evaluate the fitness of algae upon treatment. After the treatment with AgNP-PVP or AgNO3 a significant dose-dependent decrease in cell number and an increase in dissolved oxygen and lipid peroxidation were observed. Furthermore, an increase in catalase activity was measured after all of the treatments, while an increase in pH was observed after 24 and 48 hours on treatments with 1.5 and 2.0 ppm of both AgNP-PVP and AgNO3. Visible light absorbance significantly decreased after the treatment with both AgNP-PVP and silver ions, with the decrease most noticeable in the characteristic chlorophyll a and b absorbance ranges. Immunoblotting revealed significant dose- dependent decrease in the levels of Rubisco large subunit after treatments with both AgNP-PVP and AgNO3.

Silver nanoparticles, Chlorella vulgaris, toxicity

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