Functionalized beta-cyclodextrin polymers for the sorption of bile salts

Poly(beta-cyclodextrin) (PCD) resins were: prepared by a crosslinking react ion of beta-cyclodextrin with different amounts of epichlorhydrin. Some hyd roxyl groups of these polymers were functionalized with alkyl quaternary am monium groups. The polymers were tested for their ability to bind several b ile salts (including the sodium salts of cholic acid, glycocholic acid, and chenodeoxycholic acid), individually and competitively, from phosphate buf fer solutions. In all cases, the aminated PCD resin had a higher binding ca pacity for bile salts. The binding of chenodeoxycholate by the resins was m uch more effective than that of cholate and its conjugate, which indicates the importance of the host cavity size relative to that of the guest molecu les. The degree of hydrophobicity of bile acids also plays a role in their binding by PCD resins. The variable temperature studies indicate that the e lectrostatic interactions become weaker at higher temperatures while the hy drophobic interactions are not as much affected.