Heme degradation and iron release of hemoglobin and oxidative stress of lymphocyte cells in the presence of silica nanoparticles.

Silica nanoparticles (SiO2 NPs) have been widely used in the medical and food sciences. However, their toxic effects against bio-macromolecules and cells are not well understood. The present study was aimed to investigate the adverse effects of fabricated SiO2 NPs on the human hemoglobin (Hb) by FTIR, CD, fluorescence, and UV-vis spectroscopic techniques. Moreover, the toxic effects of SiO2 NPs on the human lymphocyte cell was assessed by trypan blue, reactivate oxygen species (ROS), and apoptosis assays. It was shown that synthesized SiO2 NPs have an amorphous structure with dominant size of around 20-30 nm. FTIR results showed that SiO2 NPs bind to Hb and induce significant structural changes on the native structure of Hb. Near CD spectroscopy depicted that SiO2 NPs induced tertiary structural changes and heme displacement. Fluorescence spectroscopy demonstrated the production of heme degradation species in the Hb solution after interaction with SiO2 NPs. UV-vis spectroscopy experiment indicated the release of iron form Hb after interaction with SiO2 NPs in a concentration dependent manner. Live-dead staining, ROS detection and flow cytometry analysis revealed that human lymphocyte was sensitive towards the toxicity of SiO2 NPs in a ROS-mediated apoptosis mechanism. In conclusion, SiO2 NPs exhibited concentration-dependent toxicity.