Interactions between β-cyclodextrin and an amino acid-based anionic gemini surfactant derived from cysteine

► Anionic gemini surfactant derived from the amino acid cysteine forms a 1:1 inclusion complex with β-cyclodextrin. ► The binding constant is in the order of 102 dm3 mol−1, typical of a weakly bound β-CD-surfactant complex. ► Increasing β-CD concentration shifts the surfactant apparent critical micelle concentration to higher values.