The synthesis of well-defined carboxylic acid-functionalized glycopolymers prepared via one-step postpolymerization modification of poly(N-[3-aminopropyl] methacrylamide) (PAPMA), a water-soluble primary amine methacrylamide, in aqueous medium is demonstrated. PAPMA was first polymerized via aqueous reversible addition-fragmentation chain transfer polymerization in aqueous buffer using 4-cyanopentanoic acid dithiobenzoate as the chain transfer agent and 4,4'-azobis(4-cyanovaleric acid) (V-501) as the initiator at 70 C. The resulting well-defined PAPMA was then conjugated with o-glucuronic acid sodium salt through reductive amination in alkaline medium (pH 8.5) at 45 degrees C. The successful bioconjugation was proven through proton (1H) and carbon (13C) nuclear magnetic resonance spectroscopy and matrix-assisted laser desorption/ionization time of flight mass spectrometry analysis, which indicated near quantitative conversion. A similar bioconjugation reaction was conducted with poly(2-aminoethyl methacrylate) (PAEMA) and poly(2-aminoethyl methacrylate-b-poly( N-[2hydroxypropyllmethacrylamide) (PAEMA-b-PHPMA). For the PAEMA homopolymers and block copolymers, however, lower conversion was obtained, most likely because of degradation reactions of PAEMA in alkaline medium. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3052-3061, 2010