The discovery that gold nanoparticles can induce luminescence in leaves has opened up the prospect of using roadside trees as streetlights. Post-doctor Yen-Hsun Su of Research Center for Applied Science (RCAS), Academia Sinica, Taiwan, implanted gold nanoparticles into Bacopa caroliniana plants and found that, when exposed to high wavelength ultraviolet light, the gold nanoparticles can produce a blue-violet fluorescence that triggers a red emission of the surrounding chlorophyll.

Dr. Yen-Hsun Su is a former student of the Department of Physics at National Cheng Kung University (NCKU) in Taiwan where he was supervised by Prof. Wei-Min Zhang of Department of Physics and Assistant Prof. Shih-Hui Chang of Institute of Electro-Optical Science and Engineering.

Upon learning of the discovery, Assistant Prof. Shih-Hui Chang said: “Light emitting diode (LED) has replaced traditional light source in many display panels and street lights on the road. A lot of light emitting diode, especially white light emitting diode, uses phosphor powder to stimulate light of different wavelengths. However, phosphor powder is highly toxic and its price is expensive. As a result, Dr. Yen-Hsun Wu had the idea to discover a method which is less toxic to replace phosphor powder which can harm human bodies and cause environmental pollution. This is a major motivation for him to engage in the research at the first place.”

Prof. Wei-Min Zhang, Assistant Prof. Shih-Hui Chang and Dr. Yen-Hsun Su have emphasized that the technologies and bioluminescence efficiency need to be improved for the trees to replace street lights in the future and reach the goal of energy saving and environmental protection, but Dr. Yen-Hsun Su is hopeful.

“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,” said Dr. Yen-Hsun Su in an interview with Chemistry World.