Properties and Encapsulation Capabilities of Beta-Cyclodextrin Modified with (Hydroxymethyl or...

Two beta-cyclodextrins (β-CD) modified with 2-hydroxyethyl-1,2,3-triazole or hydroxymethyl-1,2,3-triazole groups are synthesized utilizing copper catalyzed 1,3-Huisgen click cycloaddition reaction. A simple electrochemical purification process is employed to remove unwanted copper from the desired products affording up to 88% removal in 10 h. Physicochemical analysis of both purified modified β-CDs (Modβ-CDs) reveales marked differences caused just by the additional methyl group, not only between their physicochemical properties (such as melting point and hydrophilicity) but also in their capabilities to self-assemble forming aggregates at relatively low concentrations, which demonstrates to be efficient structures for encapsulating hydrophobic molecules, as it is demonstrated here with curcumin. These Modβ-CDs spontaneously formes aggregates that presented globular shapes with diameters between 100 and 400 nm (as verified by dynamic light scattering and atomic force microscopy analyses). Such type of aggregates could expand the notion of capturing larger molecules within these Modβ-CD-based structures (by not being confined just to the size of the β-CD toroidal cavity), thus increasing their performances to solubilize in a more efficient way hydrophobic compounds in aqueous solutions. This promising data suggests this simple modification could improve the ability of β-CD-based compounds to capture other large molecules of interest for the remediation of contaminated sites or for medicinal/pharmaceutical purposes.