Baoyou Geng and colleagues at the Anhui Normal University, Wuhu, made magnetite (Fe3O4) nanotubes in an egg white solution. The egg white protein - which has a high affinity for metal ions - forms organic-inorganic complexes with Fe(III). The complexes then aggregate to form nanosheets, a process that generates heat. The increase in temperature ruptures hydrogen and peptide-iron bonds so that the iron oxide dissociates from the egg white template. The iron oxide sheets then roll up to form hollow nanotubes.
Protein templated nanotubes - nanotubes have a wide range of applications from drug delivery to solar energy conversion
The use of proteins from bones and shells as templates is well known, but most need time consuming and complex methodologies to generate the biological template. Geng explains that their new strategy uses a cheap and easily obtainable protein template.
Nanotubes have a wide range of applications from drug delivery to solar energy conversion devices. And magnetite - one of the most magnetic minerals - is particularly interesting for magnetism related applications.
Xitian Zhang - a specialist in the preparation and applications of nanotubes from the Chinese University of Hong Kong, Shatin - says that this research 'provides a simple, novel and feasible method for the preparation of single-crystalline iron oxide nanotubes.' 'This approach not only enriches magnetite chemistry, but also provides a new strategy to synthesise similar materials,' he adds.
The next challenge is to investigate 'the reaction conditions on the egg white structure, which may result in morphology changes to the product,' says Geng. Geng and his team will also try synthesising other nanotubes to investigate the effects of different metal ions on egg white.