kinetic control of the self-assembly of (poly)peptides into 2- and 3-dimensional assemblies for hierarchical ordering of inorganic nanoparticles

• Applicant: Dr. Frank Polzer
• Subject Area: Preparatory and Physical Chemistry of Polymers
• Term: from 2014 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 249944173

The synthesis of block copolymers and their self-assembly behavior in solution have extensively been investigated in the last decades. Applications like in-vivo drug delivery or the patterning of surfaces are only two of the various interesting opportunities that these systems offer. Though the complexity of the derived structures is constantly increasing, natural or de-novo (poly)peptide assemblies (e.g. proteins) still exceed their synthetic analogs by far.Therefore, the proposed project kinetic control of the self-assembly of (poly)peptides into 2- and 3-dimensional assemblies for hierarchical ordering of inorganic nanoparticles will aim for the generation of 2D and 3D assemblies of de-novo (poly)peptides under different initial solution conditions (e.g. pH, temperature, ionic strength). Structural changes of the assemblies obtained at different solution conditions will provide information on the interactions of certain peptide motifs and can be used to either modify the (poly)peptide sequence or the self-assembly pathway. When 2D and 3D assemblies prove to be robust, further experiments will include a step-wise approach where several different helical bundles of (poly)peptides and/or inorganic nanoparticles will be incorporated into pre-assembled (poly)peptides to create hybrid structures. In addition direct co-assembly of (poly)peptides with nanoparticles will be tested as well and compared to the approach mentioned before. A third method for the generation of hybrid nanostructures that will be applied is the functionalization of the (poly)peptides with amino acid units that show metal-specific interactions.We will monitor the self-assembly process in-situ using spectroscopic and scattering methods, whereas intermediate and final assembled structures will be investigated intensively by small angle scattering and by microscopy techniques. Here cryogenic transmission electron microscopy (cryoTEM) will be utilized routinely for imaging the native, solubilized state of the assemblies. Furthermore, cryoTEM tomography will be applied to obtain full 3-dimensional real-space information of the (poly)peptide (hybrid)assemblies.Though the project is fundamental, the developed routines and techniques within this project will help to create 2D hierarchically ordered structures based on de-novo (poly)peptide hybrid assemblies that are expected to improve the light absorption fabrication of plasmonic solar cells.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Darrin Pochan, Ph.D.