Investigating the Interaction of Silicon Dioxide Nanoparticles with Human Hemoglobin and Lymphocyte Cells by Biophysical, Computational, and Cellular Studies.

Nanoparticles (NPs) have received great attention in biological and medical applications because of their unique features. However, their induced adverse effects on the biological system are not well-explored. Herein, the interaction of silicon dioxide nanoparticles (SiO2 NPs) with human hemoglobin (Hb) and lymphocyte cell line was evaluated under physiological conditions by multispectroscopic [intrinsic and synchronous fluorescence spectroscopy and circular dichrosim (CD)], molecular docking, and cellular [3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) and acridine orange/ethidium bromide (AO/EB) staining] methods. Transmission electron microscopy and dynamic light scattering revealed the nanosized and spherical shaped SiO2 particle. The fluorescence and lifetime decay results indicated that SiO2 NPs quenched the intrinsic intensity of Hb through a static quenching mechanism. The binding affinity of SiO2 NPs toward Hb was directly correlated with temperature. The sign of thermodynamic parameters demonstrated that hydrophobic forces played a pivotal role in the interaction of SiO2 NPs with Hb. The results of synchronous fluorescence experiments displayed that Tyr residues are moved to a more hydrophilic microenvironment. Molecular docking studies exhibited that SiO2 and Si NPs were bound to Hb primarily by hydrophobic residues. The findings from CD data verified no alteration in the secondary structure of Hb upon binding to SiO2 NPs. The human lymphocyte cell line was treated with SiO2 NPs at varying concentrations and time intervals and the cytotoxicity assays by MTT and AO/EB staining showed that cell viability was reduced by the SiO2 NP-induced apoptosis mechanism in a dose and time-dependent manner. Therefore, it may be suggested that comprehensive details regarding the interaction of NPs and biological systems such as cells and proteins can provide useful information in the development of NP-based systems.