Complexation of sugars with dihydroxyborylphenyl groups attached to magnetite particles via graft polymerization of acrylic acid

For the purpose of magnetic handling of sugars, dihydroxyborylphenyl (DHBP) groups were attached to magnetite particles. In advance, the magnetite particles were modified by the graft polymerization of acrylic acid initiated in a redox system consisting of mercapto groups introduced onto their surfaces and ceric ions. Succeedingly, DHBP groups were attached to the magnetite particles through amide linkages by the condensation reaction of 3-aminophenylboronic acid with carboxyl groups of the grafted poly(acrylic acid). Complexation of the attached DHBP groups was examined with various monosaccharides, disaccharides and oligosaccharides, and compared with that of free phenylboronic acid. The attached DHBP groups gave larger values of binding constant K for the complexation with oligosaccharides than free phenylboronic acid, whereas the K values of the DHBP groups for the complexation with monosaccharides and disaccharides were smaller than those of free phenylboronic acid. It was suggested from the result that neighboring DHBP groups on the magnetite particles interacted cooperatively with vicinal OH pairs on both the reducing and nonreducing ends of oligosaccharides. With respect to the complexation with monosaccharides, both the DHBP groups and free phenylboronic acid gave the K values corresponding to the content of furanose-type isomer in aqueous solution of each saccharide.