Abstract
This paper investigated toxicity of three engineered nanoparticles (ENP), namely, Al2O3, SiO2, and TiO2to the unicellular green algae, exemplified byPseudokirchneriella subcapitatawith an emphasis on particle size. The changes in pH, cell counts, chlorophyll a, and lipid peroxidation were used to measure the responses of the algal species to ENP. The most toxic particle size was TiO2at 42 nm with an EC20 of 5.2 mg/L and Al2O3at 14–18 nm with an EC20 of 5.1 mg/L. SiO2was the least toxic with an EC20 of 318 mg/L. Toxicity was positively related to the surface charge of both ENP and algae. The chlorophyll content of the algal cells was influenced by the presence of ENP, which resulted in limited light and availability of nutrients due to increase in turbidity and nutrient adsorption onto the ENP surface, separately. Lipid peroxidation was attributed to reactive oxygen species (ROS). Fast reaction between algal cells and ROS due to direct contact between TiO2and algal cells is an important factor for lipid peroxidation.
Highlights
Nanomaterials have been used in industrial applications and commercial products at a rapid pace
Stock suspensions of 2 g/L were made with aluminum oxide, silica dioxide, or titanium dioxide in 150–500 mL of Erlenmeyer flask with algal growth medium [19]
The major objective of the present research was to determine how particle size and type will affect the physiology and biochemical behavior of algae exemplified by P. subcapitata
Summary
Nanomaterials have been used in industrial applications and commercial products at a rapid pace. New types of NM are being developed every day. These new materials can be more hazardous than their bulk states due to small size and numeral novel properties. Among these particles, TiO2, SiO2, and Al2O3 have been shown to have adverse effects on the pulmonary systems [1,2,3]. Warheit et al [5] reported growth inhibition of P. subcapitata with a 72-hour EC50 of 87 and 61 mg/L for TiO2 at size of 38.5 and 100 nm, respectively. More studies are needed to illustrate the mechanisms of microbial responses to ENP
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