Nano electronics by genetically engineered phage viruses

In this project we will use genetic engineering to create a toolkit of nanowire-building blocks for the assembly of nanoscale hetero-wires. Such a hetero-wire is a single nanowire that consist of segments of different materials. The nanowires will be assembled using M13 bacteriophage viruses. The M13 virus is a rod shaped virus that can be modified by genetic engineering to express specific peptides on its capsid coat which in turn can nucleate inorganic materials (semiconductors, metals). This nucleation occurs with high specificity and control over the crystal structure and crystallographic orientation. Proteins that will be engineered into the ends of the rod-shaped virus will be used to assemble the individual nanowires into larger constructs and components. Two of the main issues in building electronic devices with nanowires are generating low resistance electrical contacts and their alignment to form larger scale devices. These tasks are difficult to perform with more than one nanowire at a time because the wires are very small (7-50nm diameter). Instead of fabricating the nanowire and successively aligning them, we will first create an organic scaffold on which we then can nucleate the nanowires already at their intended location. By using genetically programmed M13 viruses as templates for the nucleation of the nanowires we can build in a variety of specific molecular interactions that drive the self assembly of the wires into the desired structures. Using microcontact printing and self assembled monolayers on pre-patterned structures we can define positions on which the viruses will then self assemble the hetero-nanowires. To contact semiconducting nanowires we will fuse their nucleation viruses to viruses that are engineered to form gold wires. These gold wires can then be easily contacted to larger gold pads. We will use M13 bacteriophage viruses as a basis for our genetic modifications. The M13 virus is a rod shaped virus of ca. 900nm length and 5nm width. It consists of ca. 2700 identical major coat proteins on the virus capsid (called P8 proteins) and has several different proteins on the ends. Of these proteins on the ends we will genetically replace two (protein P3 on one end and protein P9 on the other) to express complementary binding molecules so that we can assemble long nanowires. By doing this with viruses that have genetically modified P8 proteins, we can make nanowires that consist of segments of different materials. The modifications on P3 and P9 can also be used to position and align the virus nanowires with respect to a substrate. We will first generate nanowires consisting of multiple viruses with different nucleation capabilities on their P8 proteins. Then we will use these viruses to generate trimers of gold-semiconductor/metal-gold binding viruses and deposit them on pre patterned gold substrates. After heat treatment we will do electrical measurements for material resistivity and contact resistance. By adding a gate electrode we will then attempt in a proof of concept to make a virus assembled field effect transistor.