"Light and Life"
The light-harvesting complexes of photosynthetic organisms are amongst the most complex systems in the universe – trying to understand how they work is a fascinating playground for a physicist’s creativity! And the plethora of organisms performing photosynthesis means there will always be something new and exciting to explore! Apart from the fascinating science on which the primary steps of photosynthesis are based, there is also potential commercial value in understanding their intricate details. We can gain a lot of inspiration from the smart ways in which these systems convert solar energy into biologically useful forms for making more efficient solar panels. Not to mention the remarkable level of light-harvesting regulation – by tweaking or controlling the underlying molecular mechanisms we can improve crop yield. Cyanobacteria may also become part of mankind’s food supply in the near future.
What are we doing?
1. Resolve - manipulate - full control
a. We firstly want to have a molecular understanding of energy transfer and its regulation in isolated light-harvesting complexes from various photosynthetic organisms. There is still so much not yet known. We then want to connect our observations to functions and properties of physiological significance. This means that we’re ultimately after finding protein structure–function relationships.
b. Our second step is to see how much we can improve some specific properties, for example the light-harvesting efficiency. For this purpose we use light, chemistry and nanoparticles to manipulate the complexes.
c. Our ultimate goal is to fully control the photosynthetically relevant parameters in isolated light-harvesting complexes.
2. More realistic environments
Taking protein complexes out of their native environment is quite a reductionistic approach. How do we know they behave the same as in their native environment when they’re isolated and placed in a test tube? The natural environment is too complex to mimic entirely, so in our test tube the protein complexes will always experience a different environment. We are therefore developing experimental methods that will enable us to investigate the protein complexes in more realistic environments, whilst not sacrificing the level of molecular detail we’re after.
3. Artificial photosynthesis
Every second the earth is lavished with an enormous amount of energy from the sun. So why doesn’t the whole world switch immediately to solar energy resources? One major challenge is in the area of light harvesting. We need to think differently about light harvesting technologies. Photosynthetic organisms use cheap and clean materials for diverse applications in a remarkably fine-tuned, regulated and economic fashion. There are many remarkable principles that underlie their function. For example, photosynthetic light-harvesting complexes (which we may call ‘natural’ solar panels) use a ‘bad’ thing like disorder for a ‘good’ purpose. Our current solar technologies need a paradigm shift and learn from nature! Does this mean that our solar panels should be green? Not quite, but it means that we should apply the design principles gleaned from research on the ‘natural’ solar panels.
What we’re doing with this idea is to synthesise and explore donor-acceptor assemblies, semiconductor–biological hybrid systems, and our own pigment-protein complexes – all in a multidisciplinary collaborative setting.
How do we do this?
We use optical spectroscopy as the main experimental tool and strongly back the experimental work by theoretical modelling. To gain as much from the data as possible we’re pushing the resolution to the extremes:
1. Femtosecond laser spectroscopy
Using a state-of-the-art setup we can resolve and control processes on timescales down to tens of femtoseconds. With this resolution one can see how energy flows from one part of the system to another part.
2. Single-molecule spectroscopy
That’s right: we perform spectroscopy on one molecule at a time! This approach avoids all sorts of averaging processes, which reveals a lot of new information. We have built (from scratch) the first single molecule spectroscopy setup on the continent! See the articles here and here.