Photoreactivity and ROS production: Looking at TiO2 (2011)  In
the image above, the heads and tails of developing zebrafish are
shown. In the top row, the developing transgenic ARE-gfp embryos
were exposed to TiO2 nanoparticles without illumination, while
in the bottom row the fish were exposed to particles and intense
illumination, simulating sunlight. The yolk sacs of the fish
normally produce some fluorescence, which can be seen in both
sets of images. However, the individual green-marked cells
producing GFP are seen only with the combination of the
nanoparticles and illumination. The GFP signals the production
of ROS by the TiO2 nanoparticles.  The properties of
nanoparticles that make them special can also make them
potentially dangerous. One type of nanoparticle with special
properties is titanium dioxide (TiO2). Found in different
crystalline forms, TiO2 nanoparticles can collect light and use
that energy to drive the production of different very reactive
forms of oxygen, known as reactive oxygen speci