Microtubules, which are polymers of a dimer protein called tubulin, are a key component of the cellular cytoskeleton. In vivo, they play a vital role in forming the dynamic infrastructure required to transport cargo and waste throughout the cell. In vitro, they readily polymerize from tubulin subunits to considerable lengths, and are easily functionalized and imaged. These properties make microtubules ideal tools for engineering nano-scale systems involving self-assembly. We aim to use microtubules to form a self-assembling microscale network, using streptavidin microspheres as nodes, and microtubules as edges, or links. To achieve this, we first polymerized biotinylated tubulin, giving rise to microtubules that were able to form the strong biotin-streptavidin bonds that are the basis of the network. The biotin-streptavidin bond is widely used in the field of biotechnology due to its strong covalent interaction (Kd = 10^-15M) [1], which in our experiments created a stable connection for the network.

Recently, microtubules have been grown from beads using microspheres coated with microtubule associated proteins [2]. However, whereas their goal was to create a “biomimetic aster,” (in other words, a structure mimicking the star shaped formation of microtubules that occurs during cell division), we stray away from biomimicry and instead attempt to utilize a network of beads and microtubules to self-assemble a circuit. Although it has been shown the metals can readily attach to microtubules [3], the use of metallic-coated microtubules in creating micro-circuitry has yet to be explored.