Controlled synthesis of zinc oxide nanoparticles through flame spray pyrolysis and evaluation of their anticancer effects against gastric cancer cell

Abstract

Although zinc oxide nanoparticles (ZnO NPs) have demonstrated promising anticancer activity, their therapeutic performances are frequently influenced by the synthesis routes and associated distinct physicochemical characteristics. Herein, ZnO NPs were synthesized through a cost-effective flame spray pyrolysis-assisted approach and their selective anticancer effects and underlying intrinsic apoptosis signaling pathway in human gastric carcinoma cell line (AGS) were examined. Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and dynamic light scattering (DLS) investigations were used to characterize the synthesized ZnO NPs. Afterwards, AGS and normal fibroblast cells (L-929) were treated with various concentrations of ZnO NPs, and cell proliferation was examined by the MTT assay to determine the IC50 concentration of NPs. Furthermore, the quantification of ROS and apoptosis was done by fluorometer and flow cytometry assays. Additionally, superoxide dismutase (SOD) and catalase (CAT) activity assays were performed to evaluate the oxidative stress-induced cytotoxicity mediated by ZnO NPs against AGS cells. Moreover, caspase-3/-8/-9 activity and mitochondrial membrane potential (MMP) assays were done. Finally, the expression levels of p53, Bax, Bcl-2, caspase-9/-8/-3, and cytochrome c were assessed by quantitative real time PCR and western blot analyses to explore the probable mitochondrial apoptosis signaling pathway induced by ZnO NPs in AGS cells. The results showed that ZnO NPs with an absorption maximum at 350 nm, an average size of 70 nm, a hydrodynamic radius of 92.89 nm, and a zeta potential of −43.13 mV potentially and selectively inhibited the proliferation of AGS cells in comparison with L-929 cells through a remarkable increase in the production of ROS, induction of apoptosis, reduction of SOD and CAT activity, activation of caspase-9/-3, and MMP disruption. Moreover, ZnO NPs triggered up-regulation of p53, Bax, caspase-9/-3, cytochrome c and down-regulation of Bcl-2 at mRNA and protein levels. This study suggests that synthesized ZnO NPs through flame spray pyrolysis can induce selective anticancer effects against gastric cancer cells via intrinsic apoptosis signaling pathway.