aThe binding constants (K a ) of phenolphthalein/β-cyclodextrin, phenolphthalein/(2-hydroxypropyl)-β-cyclodextrin, and phenolphthalein/(2,6-dimethyl)-β-cyclodextrin complexes were measured by ultraviolet-visible spectrophotometer. By regression of van't Hoff plot, thermodynamic parameters ( H • and S • ) of these complexes' formation were obtained. Based on these parameters, steric hindrance influence, spontaneous and enthalpically driven process for the interaction of phenolphthalein with cyclodextrins were further proved, and phenolphthalein, as a probe molecule, was used to determinate cyclodextrins' content due to less than 0.6% relative standard deviation of these quantifications and recoveries with the range of 90 ∼ 103%. Using microfiltration technique, the detection phenolphthalein probe technique was applied on the determination of surface activity of cyclodextrins grafting cellulose beads by different polycarboxylic acids, and the results exhibit the real encapsulation activity of the cyclodextrins containing these spherical functional biomaterials.