Solid particles surface-modified with beta-cyclodextrin for sustained release of flavor

Beta-cyclodextrin (β-CD) has promising applications in many fields based on its hydrophobic cavity at the central of the cyclic molecule, which can form inclusion complex with specific molecule via a host-guest interaction. However, the water solubility of β-CD limits its application. Herein, attempts have been made to graft β-CD onto two kinds of solid particles while retaining the function of β-CD, so as to expand its application. First, SiO 2 nanoparticles were modified with silane coupling agent KH-560 to offer epoxy groups. Then, the epoxy groups of the modified SiO 2 and the hydroxyl groups of β-CD were simultaneously esterified by a dicarboxylic acid of succinic acid in a non-toxic solvent medium to obtain the β-CD modified SiO 2 (SiO 2 @β-CD). On the other hand, microcrystalline cellulose (MCC) particles were also modified with β-CD (MCC@β-CD) through co-esterification of their hydroxyl groups with succinic acid. The syntheses were monitored by Fourier transform infrared (FT-IR) spectroscopy, and the obtained materials were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The degrees of β-CD modification for the particles have been measured and analyzed to optimize the synthesis conditions. The results indicate that the degree of β-CD modification for the SiO 2 @β-CD is relatively low, but the material exhibits over 60 ºC elevation of the thermal stability. In comparison, the degree of β-CD modification for MCC@β-CD reached as high as 422 mg/g. Due to the much higher content of β-CD, the synthesized MCC@β-CD was employed to load a flavor compound of D -limonene, and its sustained release was investigated to suggest the potential of the β-CD modified particles.