афротурист

Research

Biomimetic solar-to-fuel conversion


In natural photosynthesis, the primary charge separation in the reactions centres of photosystem II (PSII) and photosystem I (PSI) upon absorption of two quanta of light triggers vectorial electron flow from PSII to PSI via the cytochrome b6f complex, with the concomitant release of protons and molecular oxygen.

 

photosyntheticdiadram

 

PSI, via the second photoact, uses reducing equivalents (in the form of water-derived protons and electrons) to reduce the final acceptor ferredoxin. This feature has been utilised in the artificial photosynthetic devices aimed at mimicking the function of PSI as a powerful and stable oxidoreductase for the production of molecular hydrogen. By coupling either noble metal (e.g. Pt) nanoclusters or covalently linked hydrogenase to the acceptor side of PSI, photochemically excited electrons can reduce protons to hydrogen.

PSI based nanodevices

 

The eukaryotic unicellular red alga Cyanidioschyzon merolae provides an excellent model system to study the components of the photosynthetic electron transfer chain for production of carbon-free fuels (such as hydrogen) from water in biomimetic systems due to the high stability and activity of its photosynthetic complexes (Krupnik et al., 2013).

 

cmerolaecells

 

It is an extremophile which thrives at low pH (0.2–4) and high temperature (40–56ºC) environments.  Due to their intrinsic stability and high activity, the photosystems isolated from C. merolae cells can provide an excellent material for constructing a demonstration system for hydrogen gas production based on light driven water splitting. To this end, such a system can act as a blueprint for the development of cost-effective, efficient and stable solar-to-fuel chemical nanodevices.

 

Structure and function of photosystems in extreme growth conditions

We are investigating the molecular mechanism underlying the remarkable stability and high activity of photosystems in extremophilic algae and cyanobacteria. In particular, we aim to dissect the mechanisms of photoprotection of PSII and PSI both in vivo and in vitro, following exposure to high light and elevated temperature. To this end, we use RT and 77K fluorescence and absorbance spectroscopy, SDS-PAGE, as well as HPLC analyses of the pigments involved in the processes of rapid adaptation to high light and extreme temperatures.

 

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