Tubulins are protein building blocks that are naturally preprogrammed to assemble into cytoskeletal microtubules (MTs). In this thesis, cationic polymers are used as a molecular switch, which triggers two-dimensional (2D) conformational changes of tubulins, to control tubulin-based nano-architectures. Synchrotron small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) reveal ‘tubulin double helices’ and tubulin double helix-based architectures in nanoscale. The new architectures are controlled by the size and concentration of cationic polymers, which suggests a mechanism of the molecular switch. Finally, tubulin-based nanotubes were developed for the application as anticancer drug delivery carriers.