Synthesis of Heterotelechelic Polymers for Conjugation of Two Different Proteins.

KarinaL Heredia, GregoryN Grover, Lei Tao, HeatherD Maynard

Index: Macromolecules 42 , 2360, (2009)

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Abstract

In this report we describe a straightforward approach to synthesize polymers with end-groups that bind site-specifically to two different proteins. Telechelic biotin, maleimide poly(N-isopropylacrylamide) (pNIPAAm) was synthesized for the formation of streptavidin (SAv)-bovine serum albumin (BSA) polymer conjugates. Reversible addition-fragmentation chain transfer (RAFT) polymerization of NIPAAm was conducted in the presence of biotinylated chain transfer agents (CTAs) with either ester or amide linkages, and the resultant -biotinylated pNIPAAm were formed with low polydispersity indices (PDI 1.09). UV-Vis analysis of the trithiocarbonate chain-ends indicated 88% or greater retention of the group. A maleimide was introduced to the chain-end via a radical cross-coupling reaction with a functionalized azo-initiator. The polymer structures were characterized by (1)H NMR spectroscopy and gel permeation chromatography (GPC). The resultant biotin-maleimide heterotelechelic polymer was used to form a SAv-BSA heterodimer conjugate. Bioconjugate formation was confirmed by gel electrophoresis.