Antitumor activity of bimetallic silver/gold nanoparticles against MCF-7 breast cancer cells

Breast cancer poses a global threat with rising incidence and high mortality. Conventional treatments, including chemotherapy, radiation, surgery, and immunotherapy, have side effects, such as resistance issues and adverse effects due to genetic mutations. Meanwhile, noble metal nanoparticles (NPs) synthesized using environmentally friendly methods offer alternative treatments. Bimetallic gold (Au) and silver (Ag) NPs, using natural compounds like starch as stabilizers, enhance biomedical applications, including breast cancer therapies. In this work, the optical properties, stability, and particle size of colloidal bimetallic Ag/Au NPs were analyzed using UV-visible spectroscopy and ζ-potential measurements. The structural properties of the NPs were studied by powder X-ray diffraction (PXRD), while the morphology, chemical composition and particle size were determined using scanning transmission electron microscopy (STEM). The antitumor properties of the Ag/Au NPs were analyzed on human breast cancer cells (MCF-7) using the MTT viability method, reactive oxygen species (ROS) production, and genotoxicity assays. Peripheral blood mononuclear cells (PBMCs) were used as a reference of healthy cells. UV-vis spectroscopy and EDX mapping analysis confirmed the synthesis of bimetallic Ag/Au NPs. Localized surface plasmon resonance (LSPR) absorption bands shifted from 407 nm (Ag) to 524 nm (Au) based on the chemical composition of the NPs. The Ag/Au NPs showed cytocompatibility in PBMCs and a dose-dependent anticancer effect against MCF-7 cancer cells, as well as cell death dependent on ROS production was observed, particularly in NPs with atomic compositions of 50 and 75 at% Ag. This biological activity of the bimetallic NPs was associated with genotoxic damage of 20-24% greater than that observed in the monometallic counterparts. This study demonstrated the synthesis of mono- and bimetallic Ag/Au NPs using a rapid, reproducible and environmentally friendly method, with successful biomedical application against human breast cancer MCF-7 cells. Ag/Au NPs exhibit a ROS-dependent cell death mechanism, especially the bimetallic nanoparticles with a higher proportion of Ag in their atomic composition.