Scientists in Taiwan discovered that placing gold nanoparticles in plants made them glow, which could turn them into an effective form of nighttime illumination:
Link via Popular Science | Photo (unrelated) by Flickr user Irargerich used under Creative Commons license
By implanting the gold nanoparticles into the leaves of the Bacopa caroliniana plants, the scientists were able to induce the chlorophyll in the leaves to produce a red emission. Under a high wavelength of ultraviolet light, the gold nanoparticles were able to produce a blue-violet fluorescence to trigger a red emission in the surrounding chlorophyll.[...]
“In the future, bio-LED could be used to make roadside trees luminescent at night. This will save energy and absorb CO2 as the bio-LED luminescence will cause the chloroplast to conduct photosynthesis,” Dr. Yen-Hsun Su said in an interview with Chemistry World.
Link via Popular Science | Photo (unrelated) by Flickr user Irargerich used under Creative Commons license
Of course, I realize that, depending on the actual quantities, gold nanoparticles may well be less expensive than whatever quantities of phosphor powder was needed alternatively, and it's certainly not toxic. But still, it sounds funny.