| The field of nanotechnology aims to create useful structures and devices from components ∼1 to 100nm. However, control over the synthesis and arrangement of matter at this length scale remains quite challenging. Biological self-assembly is one promising avenue in which to overcome such issues, and living systems offer a wealth of design paradigms for the efficient and environmentally sustainable manufacture of nanoscale materials. The long-term goal of this work is the development of a system of engineered rod-like proteins 5nm in diameter and 50-150nm in length that can be rationally assembled into ordered materials with nanometer resolution. These rods are derived from the long tail fiber proteins of bacteriophage T4. Purified tail fiber components are a source of robust, effectively monodisperse, rod-shaped particles that are readily modified using standard techniques of recombinant biotechnology.;In the present work, we report a novel 10 liter scale purification scheme resulting in highly purified, stable, concentrated solutions of engineered protein rods. This process is scalable and well suited for production use. In addition, we describe the ability to control the length of the tail fiber after its production using bacteriophage infection via site-specific protease cleavage. Also described is the in vivo biotinylation of the fiber rods at discrete locations, providing a versatile attachment strategy with highly accurate nanoscale spatial control.;Finally, as an initial translational outlet of the platform, we also report on work to develop a magnetically labeled rod-shaped Brownian molecular sensor. Measurement of the AC magnetic susceptibility of magnetic nanocrystals is known to yield information about the hydrodynamic behavior of the magnet and has been shown to be an effective method to detect protein binding. Our approach uses sensors constructed of a 14nm diameter magnetic CoFe2O 4 nanocrystal attached to tail fiber derived protein rods. The rod-like shape of our sensor offers several theoretical advantages over spherical geometry. We describe the functionalization and magnetic characterization of highly monodisperse CoFe2O4 nanocrystals and their attachment to biotinylated tail fiber proteins using streptavidin. |
