Laboratory test system for the evaluation of nanomaterial toxicity on Dunaliella salina microalgae

We are reporting a new diagnostic test system for evaluating nanomaterial toxicity on halophile green microalgae Dunaliella salina based on colorimetric measurements enabling us to estimate cell death and growth-rate inhibition in microalgae suspension for serial dilutions of several toxicants. The principle of the method is the photodegradation of chlorophyll from damaged cells, resulting in the discoloration of the cell suspension, which enables us to estimate the microalgae population viability. The cell response was studied for two standard pollutants: formaldehyde and hydrogen peroxide. The toxic effect of free CTAB (cetyltrimetilammonium bromide, cationic detergent) water solution was compared with the effect of gold nanoparticles: nanorods, nanostars, and nanospheres, all synthesized in CTAB solutions. It was shown that toxicity is mainly caused by free (nonabsorbed on nanoparticles) surfactant molecules. The toxicity on microalgae D. salina decreases in the following order of silver-containing compounds: silver nitrate > silver proteinate ≫ colloidal silver in same order.