Thermosensitive affinity behavior of poly(N-isopropylacrylamide) hydrogels with β-cyclodextrin moieties

beta-Cyclodextrin-incorporated poly(N-isopropylacrylamide) hydrogels [P(NIPAM-co-CD) gel] were prepared via copolymerization of N-isopropylacrylamide (NIPAM) with mono-(6-N-allylamino-6-deoxy)-beta-cyclodextrin (ACD). Using 8-anilino-1-naphthalenesulfonic acid ammonium salt (ANS) as the guest molecule, an experimental study on the temperature dependence of affinity behavior of P(NIPAM-co-CD) gels and PNIPAM gels with ANS was carried out within a wide range of temperatures (21-60 degrees C). When the temperature increased from below the lower critical solution temperature (LCST) to above the LCST, both P(NIPAM-co-CD) and PNIPAM gels exhibited much more enhanced association constants with ANS than they did at temperatures below the LCST. Moreover, P(NIPAM-co-CD) gels showed greater affinity toward ANS than PNIPAM gels due to the presence of beta-cyclodextrin moieties in the polymeric network. Compared with the PNIPAM gel, the P(NIPAM-co-CD) gel exhibited an increased LCST in deionized water and a decreased LCST in dilute aqueous ANS solution.