Preparation of borneol–methyl-β-cyclodextrin inclusion complex by supercritical carbon dioxide processing

Abstract

In this work, the complex of borneol–methyl-β-cyclodextrin was prepared both by supercritical carbon dioxide processing and by the sealed heating treatment at mild pressure and temperature. An amorphous complex was obtained by the sealed heating treatment. A crystalline inclusion complex was obtained by the supercritical carbon dioxide processing. The crystalline complex is more stable than the amorphous complex. The apparent aqueous solubility of borneol could be enhanced about 70 times by complexation with methyl-β-cyclodextrin. In this work, a 1:1 crystalline inclusion complex between borneol and methyl-β-cyclodextrin was obtained by supercritical carbon dioxide processing at temperature about 100 °C and pressure about 100 bar. This inclusion complex is more stable than the amorphous complex prepared by the sealed heating method. The apparent aqueous solubility of borneol could be enhanced about 70 times by complexation with methyl-β-cyclodextrin. The possible complex structure is shown below: