Probing the interaction of zero valent iron nanoparticles with blood system by biophysical, docking, cellular, and molecular studies

Human exposure to nanoparticles (NPs) is inevitable as NPs become more widely applied and, as a result, nanotoxicology study is now gaining attention. Herein, the interaction of zero valent iron NPs (ZVFe-NPs) with human hemoglobin (Hb) was evaluated using a variety of techniques including fluorescence spectroscopy, far circular dichroism (CD) spectroscopy as well as docking study. Also, the cytotoxicity of ZVFe-NPs on the human lymphocyte cell line as a model of blood system cell line was investigated by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), acridine orange/ethidium bromide (AO/EB) staining, flow cytometry, and real-time PCR assays. Fluorescence studies revealed that ZVFe-NPs bind to Hb via hydrogen bonds and induced conformational changes of Hb in a static denaturation mechanism. CD experiment showed that Hb retained its native structure in the presence of ZVFe-NP. Molecular docking study also demonstrated that polar residues of Hb provide convenient medium to establish hydrogen bonds with water molecules on ZVFe-NP surface. Likewise, it was also revealed that ZVFe-NPs impaired the viability of lymphocyte cells through apoptotic pathway. For NPs to move into the clinical area, it is crucial that nanotoxicology research provide pivotal information about the adverse effect of NPs against biological systems.