Induction of apoptosis in Caco-2 cells by exogenously added O₂⁻ produced by a nanodevice

The effects of reactive oxygen species on cells have attracted considerable attention in relation to oxidative stress and related disorders. Superoxide (O2(-)) is the primary reactive oxygen species formed in animals as a byproduct or purposeful product of enzymes. We recently established an O2(-)-generating nanodevice that produces O2(-) continuously even in culture medium, by improving an original nanodevice. The new nanodevice, named Device II, efficiently induced cell death in Caco-2 cells in a time- and dose-dependent manner. Catalase largely recovered the cell viability, while superoxide dismutase rather lowered the viability. Flow cytometric and fluorescence microscopic analyses revealed that phosphatidylserine was exposed on the cells and that caspase-3 was activated in the cells after treatment with Device II. These findings indicated that exogenously added O2(-) caused apoptosis in Caco-2 cells through its derivative H2O2.