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Bioengineered Nanomaterials for research and applications

Final Report Summary - BENATURAL (Bioengineered Nanomaterials for Research and Applications)

BENATURAL aimed to translate the fundamental understanding drawn from self-assembling mechanisms of natural nanofibres and nanotubes into a fabrication strategy of nano-scale devices in a rational manner. The overall requirement for reaching this point was a thorough understanding of the relation between the assembly mechanisms, the crystalline structure of assembled structures, the physical and chemical properties of the structures, and finally how these aspects will perform when integrated for instance in a system.

Several constructs of natural fibrous proteins were designed, expressed and purified to homogeneity and crystallization trials were carried out. The crystal structure of the avian reovirus fibre sigmaC construct has been determined at 0.17 nm resolution and has been delivered ahead of time. New peptides based on the structure have been designed and studied for their ability to form self-assembling nanostructures in solution.

Short aromatic dipeptides containing the Fmoc group were designed and synthesized. Several fibrous building blocks have been identified. Both aromatic and fibrous building blocks were studied for their ability to self-assemble efficiently and readily into well-ordered structures at the nano-scale by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM).

Assessment of the bionanostructures for chemical and thermal stability was quantified using the atomic force microscopy (AFM) by ex situ imaging, thermal heating and nanothermal techniques. Morphological investigations of bionanostructures was also performed under a range of experimental conditions, using a variety of substrate chemistries, and where relevant incorporation into end application devices has been assessed by AFM and SEM. The mechanical properties of the nanostructures were investigated using a modification to the conventional tapping mode AFM, HarmoniX. The HarmoniX mode generates a mechanical map of the sample enabling the stiffness and adhesive nature of the material to be quantified. The information generated was continually fed into the consortium to aid development of building blocks with idealised properties dependent on end application requirements.

A field effect transistor (FET) with attached nanobioassemblies was fabricated and presented to the consortium by a project partner. The FET microchip was fabricated using standard photolithography and allowed the manipulation, immobilisation and electrical characterization of the peptide self-assembled nanostructures. A second FET microarray with attached nano-assemblies was fabricated using a similar technique but in this case having the option of parallel assembly.

The manipulation and immobilisation of the peptide self-assembled nanostructures was done by dielectrophoresis (DEP) and microfluidics. Using this type of FET microchip, empty peptide nanotubes and silver filled peptide nanotubes were manipulated, immobilised and an I-V curve was build to characterise the conductivity of these biological samples. In the I-V curve for a silver filled peptide nanotube a big increase in the current is obtained due to the presence of silver inside the nanotube; compared with the current obtained passing though an empty peptide nanotube the increase is about 10 (power of 9) times.

These results constitute a huge step in the development of a FET using biological fibres. A common United States patent on this subject was submitted on 28 December 2009. Another objective was to report on existing literature and know-how concerning properties of the assemblies and methods for combining them. The report was expanded into a review article (Castillo, J., Dimaki, M., and Svendsen, W. (2009) Integ. Biol. 1, 30-42) and will be further expanded in a shape of a handbook which is on preparation and will be published in 2011 by Taylor & Francis. A second report on initial electrical, structural and electrochemical measurement of the peptide nanotubes and nanofibres was circulated between the consortium describing the potential of these nanostructures for their future integration in biosensing devices.