Abstract
The lipid nanotube can provide intriguing hydrophilic internal and external surfaces unlike carbon nanotubes and therefore they have unique potentialities not only as cytomimetic tubules but also as hollow nano-spaces for chemical reactions, transferring biomolecules and so on. Here we introduce two types of manipulation techniques. One is to exploit the micromanipulator, which enables us to align the single lipid nanotube on a glass plate in an arbitrary direction simply by microextruding the aqueous dispersion. Our manipulation methodology is promising to open up fascinating possibilities of lipid nanotubes; for example, a nano-needle could be realized by extruding half of the single nanotube and fixing it at the tip of micro-needle. The other technique is to use the optical tweezers by which a single nanotube can be bent. When the laser beam is switched off after some bending occurs, the bow-shaped nanotube starts to relax to its initial straight form. From the relaxation time, we found the Young's modulus similar to those of microtubles. Namely the lipid nanotube could be a good candidate for a cytomimetic tubule. We also investigate the temperature dependence of the flexural rigidity, suggesting that frozen lipids melt to some extent before the transition temperature between tube and vesicle form.
