Directional self-assembly of biological electrical interconnects

Abstract

A method for controlled nucleation and growth of microtubules on substrates. The substrate is functionalized with a nucleating agent for microtubule growth. The method can be employed to generate nanoscale structures on substrates or between substrates by additional attachment of MT capture agents which function to capture the ends of growing MT to form connecting MT structures. The method can be used to form 2-and 3-D structures on or between substrates and can function to establish interconnects between nanoscale devices or molecular electronic devices and electrodes. A specific method for metallization of biological macromolecules and structures is provided which can be applied to metallized the MT formed by the growth and capture method. The metallization method is biologically benign and is particularly useful for copper metallization of MTs.

1 . A method for generating a nanoscale structure comprising one or more microtubules on or between one or more substrates which comprises the steps of:
 a. attaching one or more microtubule (MT) nucleating complexes to a substrate at one or more selected nucleation sites on the substrate;   b. attaching one or more microtubule (MT) capture complexes to a substrate at one or more selected capture sites on the substrate; each of the nucleation sites at a distinct location on the substrate from at least one of the capture sites;   c. contacting the one or more substrates with attached MT nucleating complexes and capture complexes with a liquid MT growth composition which comprises GTP, alpha and beta tubulin and a MT stabilizing agent, under conditions which allow MTs to grow from the nucleating sites and for a time that is at least sufficient to grow microtubules having length that will span the distance separating at least one nucleation site and one capture such that at least one MT growing from at least one nucleation site is captured at a capture site at a location on the substrate distinct from that of the nucleation site from which the MT was grown to form at least one nanoscale structure on or between the one or more substrates;   d. removing MT that have not been captured and residual MT nucleating composition to provide one or more substrates comprising a nanoscale structure comprising one or more substrate attached MTs.   
     
     
         2 . The method of  claim 1  wherein steps a-d are repeated a plurality of times to obtain the nanoscale structure. 
     
     
         3 . The method of  claim 1  wherein the nanoscale structure is an interconnect array. 
     
     
         4 . The method of  claim 1  wherein the nanoscale structure is an interconnect network. 
     
     
         5 . The method of  claim 1  wherein the direction of growth of the MT from at least a portion of the nucleation sites is controlled. 
     
     
         6 . The method of  claim 5  wherein the direction of growth of the MT is controlled by application of a directional flow of fluid to one or more of the substrates. 
     
     
         7 . The method of  claim 5  wherein the direction of growth of the MT is controlled by the application of an electric field to the substrate. 
     
     
         8 . The method of  claim 5  wherein the direction of growth of the MT is controlled by the establishment of a concentration gradient of one or more MT growth composition components required for MT growth. 
     
     
         9 . The method of  claim 1  wherein the nanoscale MT structure is formed between two electrodes on a substrate. 
     
     
         10 . The method of  claim 1  wherein the nanoscale MT structure is formed between a nanoscale device or molecular electronic device and the substrate. 
     
     
         11 . The method of  claim 1  wherein the contact time of the substrate with the MT nucleation composition is sufficient to form multiple MT interconnects on the substrate. 
     
     
         12 . The method of  claim 1  wherein the MT nucleating complex comprises gamma-tubulin. 
     
     
         13 . (canceled) 
     
     
         14 . The method of  claim 1  wherein the MT capture complex comprises alpha-tubulin or CLIP 170. 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . The method of  claim 1  further comprising a step of metallizing one or more MT on the substrate. 
     
     
         18 . The method of  claim 17  further comprising a step of fixing or crosslinking the MTS prior to metallization. 
     
     
         19 . (canceled) 
     
     
         20 . A method for generating one or more microtubules attached to a substrate which comprises the steps of:
 a. attaching one or more microtubulin (MT) nucleating complexes to a substrate at one or more selected nucleation sites on the substrate;   b. contacting the substrate with attached MT nucleating complexes with a liquid MT nucleating composition which comprises GTP, alpha and beta tubulin and a MT stabilizing agent, for a time sufficient to grow a microtubules having a desired length.   
     
     
         21 . The method of  claim 20  wherein the MT nucleating complexes comprise gamma-tubulin, a GST-gamma-tubulin fusion protein or a His-tagged gamma-tubulin. 
     
     
         22 . (canceled) 
     
     
         24 . The method of  claim 20  wherein steps a and b are repeated a plurality of times attaching MT nucleating complexes to distinct selected locations on the substrate. 
     
     
         25 . A nanoscale structure formed by the method of  claim 1 . 
     
     
         26 . A metallized nanostructure formed by metallization of a nanoscale structure formed by the method of  claim 1 . 
     
     
         27 . (canceled) 
     
     
         28 . A kit for preparation of nanoscale structures on or between substrates which comprises a plurality of MT nucleating complexes which are selectively tagged with different tags for selective attachment to a substrate, a plurality of MT capture complexes which are selectively tagged with different tags for selective attachment to a substrate wherein MT nucleating complexes having different tags and MT capture complexes having different tags are individually packaged for use. 
     
     
         29 . (canceled) 
     
     
         30 . A method for metallizing a protein comprising the step of contacting the protein-containing structure with a reducible metal salt in the presence of a reducing agent for a time sufficient to achieve a desired level of coating of the protein with the reduced metal on a surface of the protein. 
     
     
         31 .- 44 . (canceled)