Supramolecular interaction of methotrexate with cucurbit[7]uril and analytical application.

The supramolecular interaction between cucurbit[7]uril (CB[7]) as the host and the anti-cancer drug methotrexate (MTX) as the guest was studied using fluorescence spectroscopy, UV–visible absorption spectroscopy, 1 H NMR, 2D NOESY, and theoretical calculations. The experimental results confirmed the formation of 1:2 inclusion complex with CB[7] and indicated a simple and sensitive competitive method for the fluorescence detection of MTX. It was found that the fluorescence intensities of CB[7]-palmatine, CB[7]-berberine and CB[7]-coptisine were quenched linearly upon the addition of MTX. The linear ranges obtained in the detection of MTX were 0.1–15 μg mL − 1 , 0.2–15 μg mL − 1 , and 0.4–15 μg mL − 1 with detection limits of 0.03 μg mL − 1 , 0.06 μg mL − 1 , and 0.13 μg mL − 1 , respectively. This method can be used for the determination of MTX in biological fluids. These results suggested that cucurbit[7]uril is a promising drug carrier for targeted MTX delivery and monitoring, with improved efficacy and reduced toxicity in normal tissues. [ABSTRACT FROM AUTHOR]