Functionalizable organic nanochannels based on lipid nanotubes: Encapsulation and nanofluidic behavior of biomacromolecules

The amino groups on the inner surface of the nanotube that was self-assembled from unsymmetrical bolaamphiphile, N-(2-aminoethyl)-N'-(beta-D-glucopyranosyl)-icosanediamide 1, were modified covalently with a fluorescence donor dye. This functionalization of the nanotube inner surfaces has allowed us to achieve the construction of an optical recognition system for the encapsulation of guest molecules. Fluorescence resonance energy transfer (FRET) from the fluorescence donor located on the inner surface to the ferritin labeled with fluorescence acceptor enabled us to visualize the encapsulation and nanofluidic features of the ferritin in the nanochannel shaped by the hollow cylinder structure. By using this system, we were able to estimate the diffusion constants for ferritin and gold nanoparticles in the organic nanochannels on the basis of lipid nanotubes. We have also demonstrated that the size and surface charge of the nanochannel strongly affect the encapsulation behavior toward the biomacromolecules such as DNA and spherical proteins.