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S-layer and carbon nanotube construction kit

Project Leader
Pum Dietmar, Project Leader
Type of Research
Basic Research
BOKU Research Units
Institute of Biophysik
Funded by
Fonds zur Förderung der wissenschaftlichen Forschung (FWF) , Sensengasse 1, 1090 Wien, Austria
Carbon nano tubes (CNTs) are cylindrical nano structures made of carbon atoms. Due to their outstanding mechanical and electrical properties, and thermal conductivity, they are already used as additives in various novel materials. Recently, CNTs have also been considered for several medical applications due to their small diameters and ability to penetrate cells and tissues. However, since CNTs are chemically inert and insoluble in water, they have to be chemically functionalized or coated with biomolecules to carry payloads or interact with the environment. Proteins bound to the surface of CNTs are preferred because they provide a better biocompatibility and offer functional groups for binding additional molecules. Nevertheless, their arrangement and density on the CNT surface and, consequently the availability of functional groups, varies considerably.
An alternative approach to functionalize CNTs with an - additionally closed and precisely ordered - protein layer is offered by bacterial surface layer (S-layers) proteins which have already attracted much attention in the functionalization of surfaces as well as supporting structures for biomembranes. In a broad range of bacteria and archaea S-layer proteins cover the cells completely and may be considered as one of the most abundant biopolymers on earth. S-layer protein lattices show parameters in the nanometer range and offer surface chemical groups and genetically introduced biologically functional domains in precisely defined locations and orientation on their surfaces. Moreover, and highly relevant for this project too, is the natural capability of isolated S-layer proteins to self-assemble into monolayers in solution and at interfaces (e.g. on solid supports).
The overall project aim is to conduct fundamental studies on the reassembly of S-layer proteins on CNTs and learn from nature how these new hybrid architectures may be used to make novel materials e.g. for biosensing. Key are the reassembly and binding properties of S-layer proteins which allow a highly specific and sensitive functionalization of the CNT surface. Moreover, novel hybrid organic-inorganic nano structures (e.g. nano containers for drug delivery) will become possible by using the S-layer coating as template in the biomineralization of silica, metals or other technologically important materials. Further on, it may also be assumed that the pores in the S-layer lattice will induce an ordered arrangement of metallic nanoparticles directly on the CNT surface and thus might lead to new electronic effects along the “one-dimensional” CNTs.
Based on these few examples of an S-layer protein and CNTs construction kit, we would like to stress that our research, although longer term in nature, might lead to a new technology for the functionalization of carbon nanotube surfaces.
biosensors; functional surfaces; carbon nano tubes; nanotechnology; S-layers;
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