Nanomechanics of membrane tubulation and DNA assembly

We report an interesting regime of tubule formation in multilamellar membrane vesicles. An optically trapped bead is used to apply a localized subpicoNewton force on a cationic vesicle to form a membrane tubule. The force extension curves reveal a saturation phase, with the tubule length extending up to tens of microns, beyond a threshold force 0.6+/-0.2 pN. We then use the tubule as a sensor for monitoring the dynamics of charge induced DNA integration on cationic membrane vesicles. Our results may also have applications in the development of nanowires and nanofluidic devices. (C) 2003 American Institute of Physics.