Control experiments for linking of biotinylated cellulose with biotinylated microtubules. (a) Microtubules were observed to bind to biotinylated cellulose coated surface using neutravidin. (b) Absence of biotinylated cellulose lead to no binding of biotinylated microtubules showing the microtubules only bound to biotinylated cellulose and not to the glass surface non-specifically. (c) In absence of neutravidin biotinylated microtubules did not bind to biotinylated cellulose indicating the linkage between biotinylated cellulose and biotinylated microtubule is via biotin-neutravidin. This control again verified that microtubules do not bind non-specifically to the glass surface. Contrast was enhanced in (a). The scale bar is 10 μm.