Cytotoxic and stress-inducing effects of the silver nanoparticles to HeLa and U937 cells

Abstract

Amid rising of nanotechnology production, which are increasingly used in medicine, there is a problem of lack of systematic in formation on the toxic effects of metal nanoparticles. We analyzed the properties of the silver nanoparticles obtained by biochemical synthesis using reductants – flavonoids – and their effect on cells of the cervix epitheloid carcinoma HeLa and human histiocytic lymphoma U937. Biochemical synthesis method developed Egorova E.M. et al., based on the synthesis of nanoparticles of metal salts in reverse micelles – a ternary system: an aqueous metal salt solution, the surfactant AOT, nonpolar solvent. By dynamic light scattering it was evaluated the nanoparticle aggregate stability in complicated solutions – growth media. We found that synthesized silver nanoparticles aggregate at a concentration of 80*10-6 g ion / liter in RPM11640 medium, in a medium DMEM – in a concentration range of 20*10-6 g ion / liter – 80*10-6 g – ion/l, incubation of nanoparticles with the cells in an environment depleted of diva lent cations, and chloride ions leads to greater stability of the nanoparticles in the initial phase of incubation, however, after 24h incubation, aggregates still detected. MTT Cytotoxicity Assay was performed using nanoparticles at a concentration of 4.03*10-6 g ion/l, and stabilizer AOT showed significant toxicity, due to that the modification of the method of synthesis of the nanoparticles has been done to reduce the concentration of AOT. The toxicity of a new batch of nanoparticles with a concentration of 1.07*10-6 g ion/l determined in substantially proper metallic nanoparticles and toxicity was higher for the first batch of nanoparticles less cytotoxicity against AOT due to lower concentration of the stabilizer. Using an alternative method for assessing the toxicity of nanoparticles using Fluorescein diacetate 5(6)-isothiocyanate combined with propidium iodide for 4h exposure showed no significant toxicity of nanoparticles, indicating that probably the mechanism of delayed toxic effects of nanoparticles takes place and it is mediated probably by perturbations of mitochondrial function of the cells. The analysis of reactive oxygen species in HeLa cells, incubated with silver nanoparticles, showed a nonlinear dependence of growth of ROS concentration of nanoparticles that may be caused by instability of aggregation of nanoparticles in the growth medium.