New insights regarding the cyclodextrin/AAS self-assembly: A molar ratio dependent system

The assembly between acetylsalicylic acid (AAS) and β-cyclodextrin (βCD), was characterized using NMR spectroscopy (1H, T1, and NOESY), Isothermal Titration Calorimetry (ITC) and Static Light Scattering (SLS). NMR data showed the preferential orientation inside the cyclodextrin cavity, yet suggests the formation of high ordered complexes. Calorimetric titration showed a gradually less exothermic signal in an overall range of analyzed βCD concentrations, suggesting simultaneous aggregation and dessolvation of inclusion compounds. SLS data confirmed the self assembly hypothesis above 10− 4 mM, bringing new insights regarding aggregation in cyclodextrin system, which could act as modulator of supramolecular structure of complex and consequently influence its use as control release system.