One-dimensional hollow cylinder and three-dimensional meshworks of supramolecular nanotube hydrogels for fixation of proteins

We have succeeded in a construction of supramolecular nanotube hydrogel, in which nanotube networks self-assembling from a novel asymmetric amphiphile act as a gelator. The hydrogel formation using pH stimulus under room temperature enabled us to separately fix a green fluorescent protein (GFP) and a myoglobin (Mb) into not only independent nanospaces consisting of three-dimensional meshworks formed in between nanotubes but also a one-dimensional hollow cylinder of the nanotube itself. The fixed GFP into the nanotube hollow cylinder with 9 nm inner diameter showed a strong resistance to denaturants at high concentrations and heating at high temperatures. Auto-oxidation rate of the fixed Mb into the nanotube hollow cylinder was much longer than those of the fixed Mb into the nanotube meshworks and the free Mb in bulk. Such a unique property of the nanotube hydrogel has never been seen for preceded supramolecular and polymer hydrogels having three-dimensional meshworks formed in between nanofibers. Therefore, the nanotube hydrogel can function as a novel soft material applicable to biological field.