With minor modifications, the β-cyclodextrin -M MMT solution was synthesized according to the literature. To produce a homogeneous mixture, β-cyclodextrin (1g) was dissolved in 25 ml acetic acid solution (1%) and stirred for 4 h. A suspension of 2% M MMT (500 mg) in acetic acid solution (1%, 25 ml) was also prepared. The suspension was added into the resulting gel. To produce a homogeneous β-CD-M MMT suspension, the mixture was stirred at 50°C for 2 days and then freeze dried.