Toxicity of a Binary Mixture of TiO2 and Imidacloprid Applied to Chlorella vulgaris

Abstract

Nanoparticles have applications in various fields such as manufacturing and materials synthesis, the environment, electronics, energy harvesting, and medicine. Besides many applications of nanoparticles, further research is required for toxic environmental effect investigation. The toxic effect of titanium dioxide nanoparticles on the physiology of the green alga Chlorella vulgaris was studied with a widely used pesticide, imidacloprid (IMD). Chlorella vulgaris was exposed for 120 h in Bold’s basal medium to different toxic compounds, such as (i) a high concentration of TiO2 nanoparticles, 150–2000 mg/L, usually optimised in the photocatalytic degradation of wastewater, (ii) an extremely toxic pesticide for the aquatic environment, imidacloprid, in concentrations ranging from 5 to 40 mg/L, (iii) TiO2 nanoparticles combined with imidacloprid, usually used in a photocatalytic system. The results show that the TiO2 nanoparticles and IMD inhibited Chlorella vulgaris cell growth and decreased the biovolume by approximately 80% when 2 g/L TiO2 was used, meaning that the cells devised a mechanism to cope with a potentially stressful situation; 120 h of Chlorella vulgaris exposure to 40 mg/L of IMD resulted in a 16% decreased cell diameter and a 41% decrease in cell volume relative to the control sample, associated with the toxic effect of pesticides on the cells. Our study confirms the toxicity of nanoparticles through algal growth inhibition with an effective concentration (EC50) value measured after 72 h of 388.14 mg/L for TiO2 and 13 mg/L for IMD in a single-toxic system. The EC50 of TiO2 slowly decreased from 258.42 to 311.11 mg/L when IMD from 5 to 20 mg/L was added to the binary-toxic system. The concentration of TiO2 in the binary-toxic system did not change the EC50 for IMD, and its value was 0.019 g/L. The photodegradation process of imidacloprid (range of 5–40 mg/L) was also investigated in the algal medium incubated with 150–600 mg/L of titanium dioxide.

Defense responses of the green microalgae Chlorella vulgaris to the vanadium pentoxide nanoparticles

“…Because of having simple cultivation requirements, a short life cycle, and sensitivity to different classes of contaminants, unicellular green microalgae were widely used as model microorganisms in the risk assessment of pollutants (DeLorenzo et al 2002;Karimi et al 2017a,b;Nazari et al 2018). In this context, the use of the Chlorella species in nanotoxicology investigations has been described by some previous studies (Adochite & Andronic 2021;Feizi et al 2022;Hamed et al 2017;Saxena et al 2021). Chlorella vulgaris (C. vulgaris) is a photosynthetic microalga with a noteworthy dispersal in the sea and freshwater.…”