Advanced biophotonic materials: developing a toolkit for quantum dot-membrane-protein nanocomposites
Lead Research Organisation:
University of Leeds
Department Name: Physics and Astronomy
Abstract
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.
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.
| Description | Light-harvesting (LH) proteins have evolved over billions of years to absorb photons of light with great efficiency using a network of coordinated pigment molecules [1], albeit with a limited spectral range. Bio-hybrid nanomaterials allow optimized biological macromolecules, such as LH proteins, to be combined with custom-designed nanoparticles to create highly efficient "nanocomposite" light-harvesting materials. Quantum dots (QDs) are nanocrystalline semiconductors with tuneable photoluminescence properties allowing them to absorb photons across wider range of energies than natural LH proteins and have the potential to transfer their excited state energy to biomolecules via Förster Resonance Energy Transfer (FRET). In our ongoing research, we have utilized thin-film rehydration methods to self-assemble quantum dots and lipids into distinct nanocomposites as the first step in developing a model membrane system of photosynthetic proteins and tuneable QDs. We advance the understanding of how nanoparticle interactions affect their photophysical properties through the characterization of lipid-stabilized copper indium sulfide / zinc sulfide (CuInS2/ZnS) nanoclusters, using a combination of spectroscopy and microscopy techniques. The size and structure of these QD-lipid nanoclusters was assessed using light scattering and transmission electron microscopy. The photophysics was assessed using fluorescence spectroscopy and fluorescence lifetime imaging microscopy (FLIM) to map the energy transfer mechanisms at the ensemble and the the single-particle level (respectively). Overall, there is evidence of controlled nanocluster formation and a consistent, red-shifted fluorescence emission peak which suggests energetically downhill QD-QD FRET as compared to QDs that are isolated in organic solvents. With potential applications as a photo-active bio-hybrid material due to the retainment of energy transfer efficiency in similar structures [2], modular, self-assembling QD-membrane and QD-membrane-protein nanocomposites would be a promising advancement of existing light-harvesting nanomaterials. [1] B. Drop, et al., BBA. Bioenergetics. 1837(1), 63-72 (2014). [2] A.M. Hancock, et al., Nanoscale. 11(35), 16284-16292 (2019). |
| Exploitation Route | Research is still ongoing, although if successful, there is potential to utilise the methods developed within this project to create new light-harvesting nanocomposite materials due to the modular approach taken. Light-harvesting proteins could be interchanged, as could the types of quantum dots used, and the system could be combined with lipid dyes to enhance light absorption and investigate the pathways for energy transfer even further. |
| Sectors | Energy,Manufacturing, including Industrial Biotechology |
| Description | Fluorescence Lifetime Imaging Microscopy collaboration, providing data towards a planned publication with the working title 'An Investigation Into the Photophysics and Structure of Lipid-Stabilized Copper Indium Sulphide / Zinc Sulphide Nanoclusters for Use Within Light-Harvesting Nanocomposites' |
| Organisation | University of Leeds |
| Department | School and Chemical and Process Engineering |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | - Development of QD-lipid nanocomposite samples - Ensemble spectroscopy of various QD-lipid nanocomposite samples - 120keV TEM analysis for initial investigations of sample size and structure - Fluorescence microscopy of QD-lipid nanocomposite samples - Size analysis of QD-lipid nanocomposite samples via Dynamic Light Scattering (DLS) technique |
| Collaborator Contribution | Single-Particle Measurements of Quantum-Dot Nanoclusters/QD-Lipid Nanocomposites: Collaboration with Ashley Hancock where the Fluorescence Lifetime Imaging Microscope (FLIM) is used to characterise single quantum dot nanoclusters in order to investigate energy transfer mechanisms, leading to the mapping of a new energy level diagram or a kinetic model for energy transfer between quantum dots within nanoclusters. Transmission Electron Microscopy characterisation of Quantum-Dot Nanoclusters/QD-Lipid Nanocomposites: Collaboration with Zabeada Aslam where high-resolution 300keV TEM was used to characterise the size and structure of QD-lipid nanocomposites and copper indium sulfide / zinc sulphide (CIS/ZnS) quantum dots. |
| Impact | Collaboration still ongoing, final outcome will be a publication. |
| Start Year | 2022 |
| Description | Fluorescence Lifetime Imaging Microscopy collaboration, providing data towards a planned publication with the working title 'An Investigation Into the Photophysics and Structure of Lipid-Stabilized Copper Indium Sulphide / Zinc Sulphide Nanoclusters for Use Within Light-Harvesting Nanocomposites' |
| Organisation | University of Leeds |
| Department | School of Physics and Astronomy |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | - Development of QD-lipid nanocomposite samples - Ensemble spectroscopy of various QD-lipid nanocomposite samples - 120keV TEM analysis for initial investigations of sample size and structure - Fluorescence microscopy of QD-lipid nanocomposite samples - Size analysis of QD-lipid nanocomposite samples via Dynamic Light Scattering (DLS) technique |
| Collaborator Contribution | Single-Particle Measurements of Quantum-Dot Nanoclusters/QD-Lipid Nanocomposites: Collaboration with Ashley Hancock where the Fluorescence Lifetime Imaging Microscope (FLIM) is used to characterise single quantum dot nanoclusters in order to investigate energy transfer mechanisms, leading to the mapping of a new energy level diagram or a kinetic model for energy transfer between quantum dots within nanoclusters. Transmission Electron Microscopy characterisation of Quantum-Dot Nanoclusters/QD-Lipid Nanocomposites: Collaboration with Zabeada Aslam where high-resolution 300keV TEM was used to characterise the size and structure of QD-lipid nanocomposites and copper indium sulfide / zinc sulphide (CIS/ZnS) quantum dots. |
| Impact | Collaboration still ongoing, final outcome will be a publication. |
| Start Year | 2022 |
| Description | Online Poster Presentation at British Biophysical Society 60th Anniversary Conference |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Other audiences |
| Results and Impact | Online Poster Presentation to over 200 attendees at the 60th anniversary meeting of the British Biophysical Society. Theme of the conference was 'Biophysics through time and space'. |
| Year(s) Of Engagement Activity | 2020 |
| Description | Online poster presentation at the Physics Meets Biology conference hosted by the IOP Biological Physics group |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Online poster presentation at the Physics Meets Biology 2021 conference hosted by the Biological Physics Group of the Institute of Physics. Received multiple questions about research based on the presentation and had nice interactions with both academic staff and postgraduate students based outside of the UK as well as within the UK. |
| Year(s) Of Engagement Activity | 2021 |