Under aerobic conditions, excessive illumination results in the photogeneration of reactive oxygen species (ROS) responsible for protein damage and photo-inhibition during photosynthesis. We explore the effects of nanoceria (NC), a regenerative ROS scavenger, on chloroplasts isolated from plant leaves. The addition of dextran-wrapped nanoceria (dNC) was shown to decrease ROS concentrations in photoactive chloroplast solutions. We also explore the application of single-walled carbon nanotubes (SWCNTs) as vehicles for nanoparticle uptake inside not only chloroplasts, but also whole plant leaves of S. oleracea.