A highly efficient heptamethine cyanine antenna for photosynthetic Reaction Center: From chemical design to ultrafast energy transfer investigation of the hybrid system

The photosynthetic Reaction Center (RC) from the purple bacterium Rhodobacter sphaeroides has unique photoconversion capabilities, that can be exploited in assembly biohybrid devices for applications in solar energy conversion. Extending the absorption cross section of isolated RC through covalent f...

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Bibliographic Details
Published in:Biochimica et biophysica acta. Bioenergetics 2019-04, Vol.1860 (4), p.350-359
Main Authors: la Gatta, Simona, Milano, Francesco, Farinola, Gianluca M., Agostiano, Angela, Di Donato, Mariangela, Lapini, Andrea, Foggi, Paolo, Trotta, Massimo, Ragni, Roberta
Format: Article
Language:English
Subjects:
Bioconjugation
Biophotovoltaic
Light harvesting antenna
Photocurrent
Photoenzyme
Photosynthetic bacteria
Solar energy conversion
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Summary:The photosynthetic Reaction Center (RC) from the purple bacterium Rhodobacter sphaeroides has unique photoconversion capabilities, that can be exploited in assembly biohybrid devices for applications in solar energy conversion. Extending the absorption cross section of isolated RC through covalent functionalization with ad-hoc synthesized artificial antennas is a successful strategy to outperform the efficiency of the pristine photoenzyme under visible light excitation. Here we report a new heptamethine cyanine antenna that, upon covalent binding to RC, forms a biohybrid (hCyN7-RC) which, under white light excitation, has doubled photoconversion efficiency versus the bare photoenzyme. The artificial antenna hCyN7 successfully meets appropriate optical properties, i.e. peak position of absorption and emission maximum in the visible and NIR region respectively, large Stokes shift, and high fluorescence quantum yield, required for improving the efficiency of the biohybrid in the production of the charge-separated state in the RC. The kinetics of energy transfer and charge separation of hCyN7-RC studied via ultrafast visible and IR spectroscopies are here presented. The antenna transfers energy to RC chromophores within
ISSN:0005-2728
1879-2650
DOI:10.1016/j.bbabio.2019.01.009