Photodynamic ability of silver nanoparticles in inducing cytotoxic effects in breast and lung cancer cell lines

Ivan Mfouo-Tynga,¹ Ahmed El-Hussein,^1,2 Mohamed Abdel-Harith,² Heidi Abrahamse<sup>1

1</sup>Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, Doornfontein, South Africa; ²National Institute of Laser Enhanced Sciences, University of Cairo, Giza, Egypt

Abstract: Cancer is still a major health problem, and the use of nanomedicine for cancer treatment has become a new focus area for research. The multifunctional effects of silver nanoparticles (AgNPs) have made these nanostructures potent compounds for biomedical applications. AgNPs were characterized by transmission electron microscopy for their size, shape, and cellular localization; ultraviolet-visible spectroscopy for absorption properties; and their zeta potential for determining their surface charge. Cytotoxicity effects on both MCF-7 breast and A549 lung cancer cell lines were assessed using inverted light microscopy, Trypan blue exclusion assay, adenosine triphosphate luminescence, and lactate dehydrogenase membrane integrity assays. The cell death mechanism was determined by Annexin V and propidium iodide flow cytometric analysis. The results showed that AgNPs used during the present study were found to be of spherical shape, with −0.0261 mV surface net charges, with an average size of 27 nm, and they were positively identified in both cell lines. Irradiated AgNPs promoted decreased viability and proliferation, increased cytotoxicity, and induced programmed cell death through apoptosis. AgNPs exhibited photodynamic activity in both cancer cell lines, but MCF-7 cells showed enhanced cytotoxic effects over the A549 cells. The novelty related to the study presented is twofold: while the maximum absorbance of most AgNPs lies in the wavelength region of 370–450 nm, the AgNPs produced and used in this research have a peak absorption at 631 nm that is of great significance, since this wavelength lies within the biological therapeutic window. This work clearly demonstrates that our AgNPs activated at 635 nm contribute significantly to the cytotoxicity induced in cancer cells, but more so in breast cancer cells (MCF-7) than in lung cancer cells (A549).

Keywords: nanotechnology, silver nanoparticles, cell damage, breast cancer, lung cancer