# Imogolite Nanotubes: A Flexible Nanoplatform with Multipurpose Applications
## 5 Conclusions and Perspectives  
We have shown that it is now possible designing innovative imogolite nanostructures with hybrid interfaces in a predictive way. This represents an important prerequisite for future developments in nanomaterials and nanotechnologies. With their controlled morphology, tunable interfaces and unique colloidal properties, synthetic INTs appear as promising and flexible building blocks with multipurpose applications. Although the unique properties of imogolite nanotubes have been recognized for a long time [35], their combination for potential applications has been developed only recently. It is interesting to note, however, that most of the applications explored up to now, employ at least two of these properties (Figure 9).  
This is likely related to a usage of INTs restricted only to their aluminosilicate form while Ge analogues just start to receive attention (Tables 2 and 3). This is particularly obvious in the case of hybrid imogolite/polymer nanocomposites, where the use of INTs with adjustable diameters by isomorphic substitution could open up new opportunities for molecular selectivity of confined species. As far as molecular confinement is concerned, INTs offer one of the rare possibilities to probe the confined dynamics of water in well-defined geometries and for different interactions with the interface, which will be relevant not only for fundamental physics but also in chemistry, geology or biology where water in nanopores of various natures is of prime importance [178; 179]. However, a comprehensive understanding of the confinement phenomena themselves (structural and dynamical processes) is still  
Figure 9: Schematic illustration of imogolite nanotubes properties (circles) and their combined uses for different applications.  
lacking, possibly due to the difficulty and complexity in obtaining experimental details in perfectly controlled samples. This challenging task should be considered for future nanofluidic applications based on INTs.  
Besides the possibility to synthesize either hydrophilic or hydrophobic INT structures, their growth mode by oriented attachment (OA) coupling [180] may also offer a unique path to control the morphology of the final nanotube. This feature could be employed to produce hybrid INTs with successive hydrophilic and hydrophobic sections and should be relevant for the development of innovative catalytic nanoreactors. Another attempt should be made by exploiting their ability to self-organize spontaneously in aqueous suspensions and their easy alignment in an electric field in order to drive nanotube organization in the resulting material. This could be the first step towards the elaboration of anisotropic nanocomposite materials with well-dispersed nanotube filler and may be used as artificial ion channel devices [181]. Moreover, potential photonic applications would be expected by doping INTs with dyes while controlling their spatial organization by applying external stimuli. Tissue engineering is another field [182], where INTs properties could be useful as scaffolds to support and promote the growth of new tissues. Some studies have been undertaken to investigate this possibility and paved the way for future research, in particular by using the full range of modifications offered by the imogolite structure [183; 159; 184]. Finally, it was recently suggested, on the basis of DFT calculations, that the permanent polarization of imogolite nanotubes could be used for polarization-enhanced photocatalysis [185; 186], an alternative to photorerelectrics [187; 188]. The promising use of polarized 1D nanotubes for coupling confinement and photocatalysis deserves to be explored experimentally in the near future.  
The author thanks [PERSON], [PERSON], [PERSON] and [PERSON] for helpful discussions.  
The author declares no conflict of interest.