pH-responsive vesicle-like particles based on inclusion complexes between cyclodextrins and methyl orange

Micro-aggregates based on inclusion complexes between methyl orange (MO) and cyclodextrins (CDs) were investigated for the first time. The mixture of MO and gamma-hydroxybutyric-beta-cyclodextrin (gamma-HB-beta-CD) in water was observed to aggregate into vesicle-like particles by transmission electron microscopy (TEM), laser-confocal scanning microscopy (LCSM) and dynamic light scattering (DLS). Fluorescence measurements and NMR confirmed the existence of inclusion complexes between MO and gamma-HB-beta-CD. The formation mechanism and pH-responsive properties of the vesicle-like particles made by MO.gamma-HB-beta-CD have been investigated and discussed. This work is important reference for further investigating the vesicles and particles prepared based on host-guest interactions, and it is guide to understand the behavior of MO.beta-CD complexes in fluorescent probes and bio-mimicking, etc. (C) 2010 Elsevier B.V. All rights reserved.