Novel bile acid sequestrant: A biodegradable hydrogel based on amphiphilic allylamine copolymer

Amphiphilic copolymer P(AH-co-AHH) was synthesized by aqueous solution copolymerization of allylamine hydrochloride (AH) with allylhexylamine hydrochloride (AHH). The double Schiff-base cross-linked hydrogel, which could be used as a biodegradable bile acid sequestrant was prepared using P(AH-co-AHH) and the double aldehyde cross-linker (OG) obtained by the oxidation of methyl alpha-D-glucopyranoside by sodium periodate. The properties of the P(AH-co-AHH)/OG hydrogel material including the gelation mechanism, rheological research, SEM observations, swelling characteristics, and the in vitro biodegradability were systematically studied. The binding mechanism between sodium glycocholate (NaGC) and the P(AH-co-AHH) precursor was confirmed as an synergetic effect of electrostatic interactions and hydrophobic associations, which were investigated by isothermal titration calorimetry (ITC). Moreover, the hydrogel showed high equilibrium adsorption capacity towards NaGC within only 2 h and the adsorption kinetics and isotherms fit the pseudo-second-order model and Langmuir model, respectively. According to our experimental results, the hydrogel materials showed great potential to break the enterohepatic circulation of bile acid salts and could be further used for treating hypercholesterolemia. (C) 2016 Elsevier B.V. All rights reserved.