Enhanced fluorescence of photosynthetic pigments through conjugation with carbon quantum dots.

Light harvesting in photosynthesis is currently an issue on-debate and studied widely in all over the world. Studies on light harvesting mainly focus on enlightening molecular mechanism of the process and enhancing absorption capacity of light harvesting complexes (LHCs). Enhancement of absorption capacity of LHCs can be done either by natural methods or by synthetic methods. Quantum dots (QDs), fluorescent semiconductor nanocrystals, are important constituents of inorganic-organic hybrid structures which are built to enhance absorption capacity of LHCs through synthetic methods. In this study, we synthesized carbon and heteroatom doped carbon QDs through a microwave assisted synthesis method. Each QD had unique photophysical and structural properties. Photosynthetic pigments (PP) (isolated from spinach leaves) were mixed with each QD separately to build a QD-PP hybrid structure. Our results revealed that significant amount of energy is transferred from carbon QDs to PPs and therefore chlorophyll fluorescence capacity of PPs enhanced significantly in 360-420 nm excitation wavelength interval. Our results suggested that non-toxic, inexpensive and easily synthesized carbon QDs can be an important constituent for hybrid structures to enhance absorption capacity of LHCs in highly energetic region of visible spectrum.