Attachment of cyclodextrin acids to PEGA resin and study of binding with fluorescence microscopy

Abstract

Three different cyclodextrin acids, 6A,6D-di-O-(prop-2-carboxy-1,3-dienyl)-α-cyclodextrin (1), 6-deoxy-β-cyclodextrin-6-carboxylic acid (2), 6-deoxy-β-cyclodextrin-6-ethylenecarboxylic acid (3), were prepared and attached to amino PEGA resin as amides using coupling conditions with COMU and NEM. Host-guest binding to the resins was studied by fluorescence microscopy using 8-anilinoaphtalene-1-sulfonic acid (ANS) as guest, and was found to follow the equation IF = IFmax*[ANS]/([ANS] + Kd) where F, Fmax and Kd are the fluorescence, maximum fluorescence and Kd the dissociation constant for the ANS-cyclodextrin complex, respectively. Kd was 4.4, 2.4 and 4.9 × 10−4 M for the three resins. Competitive inhibition of ANS binding was performed with 1-adamantanylamine and octyl β-d-glucoside with the latter being selective for the α-cyclodextrin as expected.