Preparation and characterization of inclusion complexes of a cationic beta-cyclodextrin polymer with butylparaben or triclosan

The preparation of a cationic β-cyclodextrin polymer (CPβCD) and its complexes with butylparaben and triclosan were reported in this paper. FT-IR and 2D ¹H–¹H gCOSY NMR spectra confirmed that the antibiotics could be included inside of the lipophilic cavities of CPβCD. The formation of complexation of CPβCD with the antibiotics significantly improved the water solubility. The solubility of the antibiotics linearly increased with the concentration of CPβCD, and the values of the association constant K_1:1 of the butylparapben/CPβCD and triclosan/CPβCD complexes were 3800 and 3082 M⁻¹, respectively. The results also suggested that it was easier for butylparaben, which had relative smaller molecular size, to form the complexes with CPβCD than triclosan. Due to the targeting effect after the complexation with CPβCD, the antimicrobial activity of butylparaben can be significantly improved. Meanwhile, this improvement effect was not obvious for triclosan.