Self-assembly of composite nanotubes and their applications

Combination of the layer-by-layer (LbL) technique with the porous template method has attracted significant interest as a versatile approach that has been used to prepare tubular nanomaterials with tailored properties. The process involves the sequential deposition of different species, such as polymers, nanoparticles, lipids, proteins, dyes and organic or inorganic small molecules into various porous templates, which are subsequently removed to yield free-standing nanotubes. At the same time, this approach permits the formation of composite nanotubes with the engineering features, including size, shape, composition and function. In this review, we summarize the synthesis and properties of various LbL-assembled composite nanotubes based on electrostatic attraction, hydrogen bonding, and covalent bonding. These assembled nanotubes possess potential application in biomedical fields such as bioseparations, biocatalysis, biosensor, and drug delivery.