DNA-guided Construction of Superconductive Carbon Nanotubes

The utilization of superconductive materials offers the possibility for significant technological advancement if the phenomenon can be harnessed in a cost-effective manner. The problem: most materials only enter the superconductive state under ultra-low temperatures or ultra-high pressures (see Dr. Ines Urdaneta’s RSF article on superconductivity at high pressures). Maintaining such environmental conditions are an engineering challenge and are cost-prohibitive for applications in personal-use technologies, like ultra-fast home computers and communications devices, or public infrastructure like mag-lev transit and electrical transmission (greatly reducing wasted energy and hence energy usage while simultaneously increasing feasibility of nearly perfectly efficient energy distribution).

For superconductivity to move beyond niche applications a room-temperature superconductor is required, and the quest to find a room-temperature superconductor that is scalable and affordable is ongoing, as such a capability will revolutionize our modern technologies and provide outstanding expediencies to our daily lives. This is the promise of a quite mundane element, carbon (which makes up most of the human body), but which when ordered at the molecular level has remarkable electrodynamic properties, such as near 100% efficient conduction of electrons. Essentially, in molecular configurations like carbon nanotubes, electrons are able to move along the molecular lattice at astonishing speeds in a highly coherent fashion with nearly zero resistances and therefore no energy loss to friction and heat.

Stanford physicist William Little was one of the first scientists to realize that organic macromolecules might be the perfect material for a room-temperature superconductor. In a publication over 50 years ago [1], William Little discussed the properties of organic macromolecules that made them potentially ideal room-temperature (or higher) superconductors:

…superconductivity should be able to occur in certain highly specific types of organic macromolecules… the transition temperature for the onset of superconductivity should be high compared to that of metallic superconductors.

It appears then that a whole new field of materials is opening up before us in which the enormous versatility of structure in concept and design which is available to us in the organic materials allows us a degree of sophistication undreamed of in the inorganic systems. –William A. Little. Superconductivity of Organic Polymers. Journal of Polymer Science, No. 17, PP. 3-12, 1967.

If the potential for high-temperature superconductivity of organic macromolecules has been known for over 50 years, why has there not been any large-scale manufacturing of such materials? One of the primary challenges facing materials scientists working with these remarkable macromolecules is that their initial state is often not fully compatible with technological exaptation—the molecules must undergo engineered modifications that “functionalize” the material, such as annealing additional molecules to the structure that will enhance, stabilize, or extend the quantum properties of the material.

This is nano-engineering, and while the living organism is the superlative nanoengineering system, us human engineers have not quite mastered the extremely challenging process of ordering atoms and molecules individually.

Now, scientists at the National Institute of Standards and Technology and their collaborators at the University of Virginia School of Medicine have reported in the journal Science a technique that utilizes DNA for precision nano-engineering and ordered functionalization of single-walled carbon nanotubes [2]. Normally, the functionalization, or placement of additional molecules onto the surface of carbon nanotubes is random, and hence non-amenable to the kind of ordered precision geometry necessary for quantum resonances that would enable full stabilized superconductivity.

The team used Guanine (G) – Cytosine (C) oligomer lattices to scaffold along the surface of a single-walled carbon nanotube and annealed the residues using photo-cross-linking reactions. The team demonstrated using cryo-electron microscopy that the sequences C₃GC₇GC₃ regularly created an ordered helical structure with a molecular periodicity. The resulting covalent modifications are a promising strategy for engineering the electronic properties of carbon nanotubes. The researcher team believes their remarkable DNA-guided approach to lattice construction could have a wide variety of useful research applications, especially in physics. But it also validates the possibility of building Little’s room-temperature superconductor. The scientists’ work, combined with other breakthroughs in superconductors in recent years, could ultimately transform technology as we know it.