Dynamic light scattering (DLS) measurement provides and effective way to investigate the formation of nanotube of gamma-cyclodextrin (gamma-CD) induced by N,N'-diphenylbenzidine (DPB) in water. With the combination of steady-state fluorescence and fluorescence anisotropy experiments, it was found that for alpha- and beta-CD, only 1:2 (guest:host) inclusion complexes were formed and for gamma-CD, cyclodextrin nanotube was formed involving 16 gamma-CD units at maximum. The pH effect studies with both DLS and fluorescence anisotropy measurement indicated that the hydrogen bonding between neighboring CDs was necessary to the formation of cyclodextrin nanotube. In the temperature experiment, we found that the nanotube of DPB-gamma-CD could exist stably at relatively high temperatures and the transition point for structural collapse was estimated to be around 54 degrees C. The aggregation states of both gamma-Cd itself and DPB-gamma-CD nanotube were observed with TEM. (c) 2005 Elsevier Inc. All rights reserved.