Highly structured optical materials based on protein containers and plasmonic nanoparticles for the manipulation of light at the nanoscale

• Applicant: Professor Dr. Tobias Beck
• Subject Area: Biological and Biomimetic Chemistry ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 401323995

In this project, a synthetic strategy towards optical materials will be established using protein containers and nanoparticles. The artificially assembled materials will be able to manipulate light at the nanoscale, which is important in metamaterials and for applications such as sensing, plasmon optics or light harvesting. To this end, plasmonic gold nanoparticles and quantum dots will be arranged into highly structured plasmonic and energy-transfer materials. Currently, major challenges in nanoparticle material fabrication are low-order assembly, small domain sizes and long interparticle distances. These limitations will be overcome by using protein containers as an atomically precise ligand shell. With protein containers as building blocks, nanoparticles will be assembled with high precision into mesoscale materials with optical properties that emerge from interactions between the components. With the recent advances in computational redesign of protein containers, it is now possible to combine these results with nanoparticle synthesis and protein crystallography in a highly interdisciplinary fashion. A new type of protein-based material will be realized by using an innovative design approach with two oppositely charged protein containers as building blocks. Binary nanoparticle superlattices with two different types of nanoparticles will be generated. For energy-transfer materials, fluorescent quantum dots will be co-assembled with plasmonic nanoparticles to enable energy transfer between the particles. The hybrid protein-nanoparticle materials will have a high nanoparticle content and display short interparticle distances (<10 nm, below the particle diameter). This is essential for emergent properties based on strong near-field interactions such as plasmonic coupling between the particles, but difficult to achieve with current approaches due to spacious linker materials. Because the protein scaffold is independent of the nanoparticle cargo, this modular approach, together with the binary nature of the materials, will enable tuning of the optical properties by choice of nanoparticle content, assembly type and protein container type. The proposed project will make a significant contribution to the synthesis and characterization of optical materials based on plasmonic nanoparticles and quantum dots and will provide improved understanding of light-matter interactions at the nanoscale for such systems. Furthermore, materials with plasmonic or energy-transfer properties have potential application as plasmonic waveguides or nanoscopic lasers (spasers) for manipulation of light signals at the nanoscale.

• DFG Programme: Research Grants