Mass-production technology for making functionalized organic nanotubes

Researchers at the Nanotube Research Center of the National Institute of Advanced Industrial Science and Technology (AIST; Tokyo; www.aist.go.jp) have developed a process for making organic nanotubes of metal complexes (photo, left). The scientists have produced organic nanotubes with metal ions (Zn⁺², Cu⁺², Co⁺², Ni⁺², Fe⁺² and Mg⁺²) complexed at the inner and outer surfaces of organic nanotubes (diagram, right), and believe such materials will find applications as: new catalysts with transient metal coordinated spatially on the inside; low-molecular-weight compounds with coordinated functional groups; DNA and protein inclusion, adsorption, and separation for biotechnology; and new electronic, magnetic and optical materials. For example, a Cu-complexed organic nanotube has been shown to selectively adsorb gold nanoparticles that have an amino group on their surface.

The new nanomaterials are made by adding aqueous solutions of metal salts to a suspension of peptide lipids in methanol or ethanol. Nanotubes form after 10 minutes, producing about 2 – 20 g/mL of suspension — a production rate about 200 times higher than alternative methods. The simple procedure consumes little energy and is easy to scale up, says AIST.

This is the third mass-production process for making organic nanotubes that has been developed by AIST. The previous processes produce organic nanotubes with hydroxyl and carboxyl groups on the surface.