Regioselectively ordered silica nanotubes are formed on molecular polysaccharide derivatives under mild conditions by sol-gel processing using biomimetic principles. The cellulose molecules serve as a rigid backbone, whilst structure-directing oligopropylamino residues are introduced to mimic the functional groups responsible for silica formation by diatoms (see figure). The obtained silica nanotubes exhibit a dual microstructure, consisting of an ordered near-core region and an amorphous mantle.