Combining ATRP and "click" chemistry: A promising platform toward functional biocompatible polymers and polymer bioconjugates

The bromine chain-ends of well-defined poly(oligo(ethylene glycol) acrylate) (POEGA) (M-n = 6850 g(.)mol(-1), M-w/M-n = 1.21) prepared using ATRP were successfully transformed into various functional end groups (omega-hydroxy, omega-amino, and omega-Fmoc-amino acid) via a two step pathway: (1) substitution of the bromine terminal atom by an azide function, (2) 1,3-dipolar cycloaddition of the terminal azide and functional alkynes (propargyl alcohol, propargylamine, and N-R-(9-fluorenylmethyloxycarbonyl)-L-propargylglycine). The efficient "click" cycloaddition was confirmed in all cases by H-1 NMR or SEC-UV analysis. Moreover, this two-step synthetic strategy was also studied for preparing polymer-b-oligopeptide bioconjugates. Well-defined POEGA-b-GGRGDG was obtained in high yields via the "click" ligation of the azido functional POEGA and the alkyne functional oligopeptide GGRGDG.