By modifying chloroplasts with aggregation-induced emission luminogens, known as AIEgens, they can better split water, separate electrons, and create adenosine triphosphate (ATP). The AIEgens attached with click chemistry improve the chloroplasts by collecting light that is normally inaccessible to normal photosynthetic pigments.
Chloroplasts are the light-driven metabolic factories of higher plant cells that produce carbohydrates and oxygen from carbon dioxide and water during photosynthesis. Chlorophyll A and chlorophyll B are the main photosynthetic pigments in chloroplasts. However, the adsorption spectra of these pigments do not cover the entire spectrum of solar radiation and mean that chloroplasts cannot use all of the solar energy available to them. Chloroplasts mainly absorb blue and red light and cannot use light in the invisible ultraviolet range, which can damage DNA and proteins.
Now, a team led by Zhiyang Liu, Ryan Kwok and Ben Zhong Tang from the Hong Kong University of Science and Technology has developed two AIEgens that can collect both ultraviolet radiation and photosynthetic inefficient radiation and convert this radiation into blue and red light .
AIEgens are molecules that, when aggregated, emit intense fluorescence. The AIEgens developed by Liu, Kwok and Tang’s team contain activated alkyne groups derived from tetraphenylethylene and triphenylamine. These groups enabled the team to attach the AIEgens to living chloroplasts using a metal-free click reaction based on the high reactivity between alkynes and amines.
“Compared to the natural chloroplasts, the two AIEgen-modified chloroplasts showed an increase in ATP production of 30 and 50%, respectively, under our test conditions. We learn from nature and meanwhile try to go beyond nature. This work shows that we can modify units of photosynthesis and improve the use of solar energy in ordinary plants, ”says Tang.
Eva-Mari Aro of the University of Turku in Finland, whose research focuses on photosynthesis and bioenergy, says the work highlights the importance of collaboration between materials scientists and photosynthesis researchers. “Solar energy is the most promising option to displace fossil resources and promote the systemic transition to sustainable green and renewable chemicals and fuels made directly from sunlight. The new solar spectrum expansion materials presented here that are useful in photosynthetic energy conversion are very inspiring and not only promote the design of efficient bio-hybrid devices, but also other solar energy conversion devices that use natural photosynthesis. “