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 γ-hydroxybutyric-β-cyclodextrin (γ-HB-β-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 γ-HB-β-CD. The formation mechanism and pH-responsive properties of the vesicle-like particles made by MO·γ-HB-β-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·β-CD complexes in fluorescent probes and bio-mimicking, etc.