Kinetic study on the binding of lectin to mannose residues in a polymer brush.

A disulfide-carrying polymer with many pendent mannose residues (dithiolated poly(2-methacryloyloxyethyl D-mannopyranoside)) was obtained by atom transfer radical polymerization (ATRP) method using 2-(2'-bromoisobutyroyloxy)ethyl disulfide as initiator. The obtained disulfide-carrying glycopolymer (DT-PMEMan) was accumulated as a polymer brush on a colloidal gold-immobilized glass substrate, and the binding processes of a lectin, Concanavalin A (Con A), to mannose residues in the polymer brush were examined using a UV-vis spectrophotometer with the help of a localized surface plasmon resonance. Con A showed a concentration-dependent specific binding to the glycopolymer brush, and the apparent association constant of Con A with mannose residues in the brush was much larger than the association constant for small sugars due to the so-called cluster effect. Furthermore, the glycopolymer brush-coated device had a detection limit lower than 5 nM. The glycopolymer-carrying device examined here is expected to expand our knowledge of recognition phenomena at the surface of polymer brushes.