Advanced biophotonic materials: developing a toolkit for quantum dot-membrane-protein nanocomposites

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Photosynthesis is essential for life on Earth and the light-absorbing proteins involved are a great source of inspiration for biophysicists. In contrast, quantum dots (QDs) are tiny inorganic semiconductor nanoparticles of great technologic interest. "Light-harvesting" (LH) proteins, found in plant biomembranes, absorb photons of light using a network of coordinated pigment molecules (e.g. chlorophylls). Energy absorbed by LH proteins is transferred as excited electronic states through membranes >100 nm with remarkable quantum efficiency (>90%). Yet, LH proteins are limited to specific biological pigments and their absorbance spectrum has gaps where solar photons are not harvested. QDs can absorb photons of a wide range of energies and transfer the energy to other molecules. The excellent optical properties of QDs make them an ideal partner for channelling energy to (or accepting energy from) LH proteins.Project objectives are to: (1) Design, generate and characterize a membrane-based system that combines QDs with photosynthetic proteins in order to increase the spectral range of photosynthesis. (2) Study how energy, and electron, transfer from QD is affected when they are interfaced with this biohybrid system. (3) Investigate use of your membrane/QD materials for applications to nanotechnology (e.g. functional thin-films). You will systematically compare nanocomposites of different compositions, e.g. (i) QDs embedded into the lipid bilayer or tethered to the membrane surface, (ii) QDs embedded within polymer micelles (iii) interfacing the above with a series of photosynthetic membrane proteins (LHCII, PSI, PSII), (iv) trialling QDs of different chemistries and sizes. You will use a range of world-class biophysical tools including: spectroscopy to characterize optical properties (absorbance, fluorescence, other) and various high-end microscopies to visualize the particles at high resolution (atomic force microscopy, fluorescence microscopy, electron microscopy), showing the improvement that QDs make over the protein alone.