Host–guest systems based on pH-sensitive acyclic cucurbit[n]urils for controlled release of camptothecin

Stimuli-responsive drug delivery systems may provide an effective way to treat cancer as they can release cargoes regularly according to changes in the human microenvironment. In this work, we design and prepare acid-controlled release complexes of camptothecin with three pH-sensitive acyclic cucurbit[n]urils. The inclusion complexes have been characterized by 1 H and 2D nuclear magnetic resonance, X-ray powder diffraction, and phase solubility diagram. Cells incubated with complexes have been analyzed by high-content analysis, and cytotoxicity tests have been completed by MTT assay. The results showed that complexes with different binding constants can release the drug substance in the physiological pH environment of cancer cells, maintain good anticancer activity, and have low cytotoxicity. This provides a strategy about targeted and responsive systems of CPT for clinical application.