ARTificial protein Engineering for Metamaterial Integration and Self-assembly – ARTEMIS

The tailoring of optical properties has reached the nanometer-scale with the advent of plasmonics, the technology exploiting the collective properties of surface electrons in noble metals. It occurred in recent years that crystalline metal colloids could offer enhanced performances owing to the limited better spatial confinement and more limited dissipation, which could advantageously be coupled to the absorption and emission properties of metallic or semiconducting quantum dots. Potential applications of such nano-systems encompass biomedical diagnosis (imaging) and therapy (hyperthermia) as well as optical information processing at the nanometer-scale, provided that synthetic routes to biocompatible nanoparticles with controlled size and morphology can be developed and that spatial organization of the nanoparticles into 2D and 3D higher-order architectures of well-controlled topology can be achieved. The most advanced approaches to these goals currently use polymers, peptides, DNA or natural proteins but all present serious limitations.
Beyond this state-of-the-art, the ARTEMIS aims, first, at designing and producing artificial proteins that specifically bind to an arbitrarily chosen crystalline inorganic surface - without prior knowledge of protein/mineral interaction mechanisms. Our versatile artificial proteins will bear one of the three following functions. (i) The specific affinity to metallic or semiconductor crystal facets and, hence, to direct the formation of crystalline anisotropic nanoparticles by facet growth inhibition. (ii) The propensity to self-assemble into higher order protein architectures, akin to viruses, therefore widening the morphosynthesis of metal nanoparticle to templated mechanisms and new shapes. (iii) The ability to drive and control the 3D self-assembly of plasmonic and/or luminescent nanoparticles by protein pair formation.
Beyond the mere creation of new protein-nanoparticle conjugates, the innovative objectives of this platform are threefold.(1) Proteins have sophisticated molecular recognition capacities, far more general than DNA or peptides, but are complex to design and synthesize. Therefore, the best fitted proteins exhibiting high affinity for inorganic crystalline substrates, polymer surfaces and/or chosen protein targets will be created by combinatorial biology methods. (2) Plasmonic metallic nanoparticles will be synthesized using artificial proteins and their assemblies as selective modifiers or preformed templates, respectively, to control the particle shape, size and crystallographic orientation. (3) High-affinity protein pairs will be exploited to direct the assembly of plasmonic and luminescent nanoparticles into higher-order metamaterials superstructures such as dimers, chains and networks. This biochemical platform will allow to control the optical and thermal properties of the hybrid conjugates by tuning the protein : nanoparticle stoichiometry and exploiting orthogonal recognition between protein pairs. The ARTEMIS project gathers biologists (IBBMC Orsay and ESPCI Paris), chemists and physicists (SCR Rennes and CEMES Toulouse) who will develop together the protein design, selection, synthesis and self-assembly, exploit the inorganic growth control of proteins to produce protein-coated metallic nanoparticles with defined morphologies and couple plasmonic and/or luminescence behaviours using the selective affinity of the protein pairs. The protein-nanoparticles hybrid structures and assemblies will provide innovative objects for the study of coupling, confinement and enhancement of plasmonic, luminescent and thermal properties to the recently started project ANR-2013-SIMI10 PlaCoRe dedicated to colloidal plasmonics and led by Partner 2.