Intracellular ROS Induction by Ag@ZnO Core–Shell Nanoparticles: Frontiers of Permanent Optically Active Holes in Breast Cancer Theranostic

In this study, we investigated whether ZnO coating on Ag nanoparticles (NPs) tunes electron flux and hole figuration at the metal-semiconductor interface under UV radiation. This effect triggers the photoactivity and generation of reactive oxygen species from Ag@ZnO NPs, which results in enhanced cytotoxic effects and apoptotic cell death in human breast cancer cells (MDA-MB231). In this context, upregulation of apoptotic cascade proteins (i.e., Bax/Bcl2 association, p53, cytochrome c, and caspase-3) along with activation of oxidative stress proteins suggested the occurrence of apoptosis by Ag@ZnO NPs in cancer cells through the mitochondrial pathway. Also, preincubation of breast cancer cells with Ag@ZnO NPs in dark conditions muted NP-related toxic effects and consequent apoptotic fate, highlighting biocompatible properties of unexcited Ag@ZnO NPs. Furthermore, the diagnostic efficacy of Ag@ZnO NPs as computed tomography (CT)/optical nanoprobes was investigated. Results confirmed the efficacy of the photoactivated system in obtaining desirable outcomes from CT/optical imaging, which represents novel theranostic NPs for simultaneous imaging and treatment of cancer.