Anticancer properties of gold nanoparticles biosynthesized by reducing of chloroaurate ions with Dunaliella salina aqueous extract

The use of Dunaliella salina microalgae as bioreactors allows to produce gold nanoparticles with anticancer activity by means of green chemistry. The method has been reported for the synthesis of gold nanoparticles using extract of D. salina. This green synthesis technique involves using bright sunlight that we consider as poorly controlled condition. The mechanism of nanoparticles toxicity is not yet elucidated. The toxic effect might arise either from toxic intermediates production during bioreduction of gold ions or from physical adsorption of bioactive molecules on nanoparticles surfaces. This research aimed to optimize gold nanoparticles biosynthesis using aqueous extract of D. salina (AED) and to clarify cytotoxic properties of synthesized nanoparticles. The synthesis of nanoparticles involved heating the reaction mixture and was carried out without using sunlight exposure. The fluorometric alamar blue-based toxicity tests with mammalian cell cultures HeLa and Vero were conducted. The following pollutants were tested: biogenic nanoparticles (AED-AuNPs), 15 nm citrate-capped gold nanoparticles stabilized by aqueous extract of D. salina (Cit-AuNPs@AED), 15 nm citrate-capped gold nanoparticles stabilized by polyethylene glycol (Cit-AuNPs@PEG). We have shown that heating the reaction mixture during bioreduction of HAuCl4 by AED led to the formation of gold nanoparticles with average diameter 12.1±4.1 nm. It has been shown that AED-AuNPs exerted a selective cytotoxic effect on the cancer cell line HeLa. Kidney epithelial cell line Vero appeared to be much more resistant to AED-AuNP than HeLa cells over testconcentration range 50-400 mg Au/L. Cit-AuNPs@AED were found to be non toxic. This evidence indicate that the toxicity of biogenic nanoparticles is likely to be associated with biotransformation of D. salina metabolites during the bioreduction of chloroaurate ions.