A bio-organic hybrid photosynthetic complex for enhaced photoconversion

Artificial photosynthetic systems capable of exploiting solar energy for photocatalysis and electrical energy production have attracted considerable interest in recent years. A possible approach to such systems consists in the assembly of hybrid architectures combining a synthetically tailored antenna for effective light harvesting with a natural photoconverter optimized by billion years of evolution. We have designed and synthesized a hybrid complex combining the photosynthetic reaction center (RC) of the bacterium Rhodobacter Sphaeroides R26 with tailored ?-conjugated fluorophores, which can act as antennas to extend the light harvesting capability of the natural RC in a wavelength range where the unmodified biological enzyme does not efficiently absorb [1]. The bio conjugation protocol developed enables to selectively functionalize the lysine residues of the RC that are best located for efficient energy transfer, and the molecular structures of the dyes preserve the enzyme full activity. The resulting hybrid systems are capable of efficient photoconversion in a wavelength range where the non-conjugated protein does not absorb, thus outperforming the natural system in light harvesting and conversion ability. Our study shows that it is possible to design effective organic/biological hybrid photosynthetic machines for energy conversion, and paves the way to a new generation of hybrid materials for artificial photosynthesis. References F. Milano, R.R. Tangorra, O. Hassan Omar, R. Ragni, A. Operamolla, A. Agostiano, G.M. Farinola, M. Trotta Angew. Chem. Int. Ed. 51, 11019 (2012)