Electric field-induced reversible trapping of microtubules along metallic glass microwire electrodes

Microtubules are among bio-polymers providing vital functions in dynamic cellular processes. Artificial organization of these bio-polymers is a requirement for transferring their native functions into device applications. Using electrophoresis, we achieve an accumulation of microtubules along a metallic glass (Pd_42.5Cu₃₀Ni_7.5P₂₀) microwire in solution. According to an estimate based on migration velocities of microtubules approaching the wire, the electrophoretic mobility of microtubules is around 10^-12 m²/Vs. This value is four orders of magnitude smaller than the typical mobility reported previously. Fluorescence microscopy at the individual-microtubule level shows microtubules aligning along the wire axis during the electric field-induced migration. Casein-treated electrodes are effective to reversibly release trapped microtubules upon removal of the external field. An additional result is the condensation of secondary filamentous structures from oriented microtubules.