Spontaneous Self-Assembly, Functionalization, and Meso-Scale Host-Guest Science of Organic Nanotubes

摘要

Self-assembly in water at pH 6 and 10 of a wedge-shaped bolaamphiphile (1), bearing amino and glucose hydrophilic headgroups, was found to give two types of nanotubes with different inner diameters of 20 and 80 nm, respectively. X-ray diffraction and IR measurement revealed that the nanotubes have distinct inner and outer surfaces covered with amino and glucose headgroups, respectively. The nanotubes were able to effectively encapsulate an anionic spherical protein, ferritin, and DNA into the hollow cylinder under neutral pH conditions. Positively charged amino groups in the nanotube hollow cylinder proved to accelerate the encapsulation of the anionic biomacromolecules via electrostatic interaction. Covalent modification of the amino groups with a fluorescent donor dye on the inner surface of the nanotube allowed us to achieve the construction of an optical recognition system for encapsulation of guest molecules. Fluorescence resonance energy transfer (FRET) from the fluorescent donor located on the inner surface to the ferritin labeled with fluorescent acceptor enabled us to visualize the encapsulation and transportation features of the ferritin in the nanochannel shaped by the hollow cylinder structure.