PVA-Coated Fluorescent Carbon Dot Nanocapsules as an Optical Amplifier for Enhanced Photosynthesis of Lettuce

By adopting an adhesive polyvinyl alcohol (PVA) to encapsulate fluorescent carbon dots (CDs), a novel approach to prolong foliar fluorescent CD retention for enhancing lettuce photosynthesis was developed. More importantly, the photoluminescent quantum efficiency of CD nanocapsules was as high as 72.6%. CD nanocapsules can effectively adhere to leaves and emit visible light that can be absorbed by chloroplasts. Eventually, the chloroplast captures a larger range of light to speed up electron transport. Herein, the growth behavior and physiological processes of the lettuce leaf as model plant tissue sprayed with CD nanocapsules were emphatically investigated. The results showed that spraying 3900 mg/L CD nanocapsules on leaves could significantly increase the photosynthesis rate, production yield, soluble sugar and soluble protein content of lettuce. This work offers a promising research field to explore new and facial nanoengineering strategy for spraying leaf with light-harvesting materials as light fertilizer to enhance photosynthesis, thus promoting plant growth and physiology processes.