Self‐assembled lipid nanotube hosts: The dimension control for encapsulation of nanometer‐scale guest substances

Abstract

Supramolecular nanotube hosts with precisely controlled inner or outer diameters have been synthesized by self-assembly of unsymmetrical bolaamphiphilic monomers or glucopyranosylamide lipids, respectively. Time-resolved fluorescent measurement using 8-anilinonaphthalene-1-sulfonate (ANS) as a probe revealed that the water confined in a cardanyl-b-D-glucopyranoside lipid nanotube has relatively lower solvent polarity corresponding to that of propanol than bulk water. Extensively developed hydrogen bond networks also characterize the confined water in comparison to the case in bulk water. Encapsulation ability of the glucopyranosylamide lipid nanotube has been examined by filling the lyophilized LNTs with gold or silver nanoparticles, ferritin, or magnetic crystals. Filling the unsymmetrical bolaamphiphile nanotube possessing positively charged inner surfaces with negatively charged polymer beads or ferritin proved to be successful without depending on capillary action.

Organic nanotubes for drug loading and cellular delivery

“…Organic nanotubes can entrap proteins, nucleic acids, viruses, and metal nanoparticles, which cannot be achieved using cyclodextrin because organic nanotubes have at least a 10-fold larger inner diameter providing much greater space for the encapsulation of passenger molecules than cyclodextrin. Similar to cyclodextrin, organic nanotubes are expected to be applied for use in the medical and food fields (Yang et al, 2004a,b;Yui et al, 2005;Shimizu, 2006Shimizu, , 2008aKameta et al, 2005Kameta et al, , 2007Kameta et al, , 2008.…”

Self‐assembled organic nanotubes: Toward attoliter chemistry

“…60 Furthermore, confined water in the LNT hollow cylinder of 4 with 10 nm inner diameters proved to exhibit the physical properties of structured water similar to intracellular water. 61,62 In our early work, we found that capillary action enables the LNTs to encapsulate aqueous solutions or dispersions containing such guest substances into their internal hollow cylinders.…”

“…One has never needed to address those diverse factors to tailor advanced supramolecular nanotube hosts when designing conventional low-molecular-weight host compounds. 60 To achieve passive encapsulation of the guests independent of capillary action, we have started with rational modification of the LNT inner surface with designed functionalities as well as charges.…”

Fabrication and functionalization of lipid tubular microstructures

“…Apart from the surface modification of lipid tubes, encapsulation and embedding of appropriate nanoparticles into hollow cylinder and membrane lamella of lipid tubes, respectively, were studied by Shimizu's group 29,30 . They have succeeded in filling gold and silver nanoparticles into lyophilized lipid nanotubes to realize the 1-D arrangement of the nanodots that are shown in Figure 3b.…”