Spectrophotometric estimation of the accessible inclusion sites of β-cyclodextrin fixed on cotton fabrics using phenolic dyestuffs

Abstract

Surface modified textiles with cyclodextrins are used in a wide range of applications. The presence of cyclodextrins on a textile material can be qualitatively proved by application of alkaline solutions of phenolphthalein and visual evaluation of the color change. However, there is no simple and universal method for quantitative determination of the amount of accessible cyclodextrins for complexation with guest molecules. In this article, we report a simple way based on colorimetric investigation of adsorption and desorption of phenolphthalein and phenol red in the cavities of cyclodextrins. To this end, woven cotton fabrics finished with different amounts of β-cyclodextrin were used. With the known stoichiometry of the complex formation of phenolic dyes with β-cyclodextrin, spectrophotometric study of complexation and decomplexation of these dyestuffs in cavities of cyclodextrins enables us to determine the accessible cyclodextrin sites quantitatively.