Facile Synthetic Procedure for ω, Primary Amine Functionalization Directly in Water for Subsequent Fluorescent Labeling and Potential Bioconjugation of RAFT-Synthesized (Co)Polymers

Authors

Adam W. York, University of Southern MississippiFollow
Charles W. Scales, University of Southern Mississippi
Faqing Huang, University of Southern MississippiFollow
Charles L. McCormick, University of Southern MississippiFollow

Document Type

Article

Publication Date

8-1-2007

Department

Polymers and High Performance Materials

Abstract

We describe a facile method to amine functionalize and subsequently fluorescently label polymethacrylamides synthesized via reversible addition−fragmentation chain transfer (RAFT) polymerization. RAFT-generated poly(N-(2-hydroxypropyl) methacrylamide-b-N-[3-(dimethylamino)propyl] methacrylamide) (poly(HPMA-b-DMAPMA)), a water soluble biocompatible polymer, is first converted to a polymeric thiol and functionalized with a primary amine through a disulfide exchange reaction with cystamine and subsequently reacted with the amine-functionalized fluorescent dye, 6-(fluorescein-5-carboxamido)hexanoic acid, succinimidyl ester (5-SFX). Poly(HPMA₂₅₈-b-DMAPMA₁₃) (M_n = 39 700 g/mol, M_w/M_n = 1.06), previously synthesized by RAFT polymerization, was used to demonstrate this facile labeling method. The problem with labeling the ω-terminal chain end of a RAFT-synthesized polymethacrylamide is that the reduced end yields a tertiary thiol with low reactivity. The key to labeling poly(HPMA-b-DMAPMA) is to first reduce the dithioester chain end with a strong reducing agent such as NaBH₄, and then functionalize the tertiary polymeric thiol with a primary amine through a disulfide exchange reaction with dihydrochloride cystamine. We show that the disulfide exchange reaction is efficient and that the amine-functionalized poly(HPMA-b-DMAPMA) can be easily labeled with the fluorescent dye, 5-SFX. This concept is proven by using a ninhydrin assay to detect primary amines and UV−vis spectroscopy to measure the degree of conjugation.

Publication Title

Biomacromolecules

Volume

8

Issue

8

First Page

2337

Last Page

2341

Recommended Citation

York, A. W., Scales, C. W., Huang, F., McCormick, C. L. (2007). Facile Synthetic Procedure for ω, Primary Amine Functionalization Directly in Water for Subsequent Fluorescent Labeling and Potential Bioconjugation of RAFT-Synthesized (Co)Polymers. Biomacromolecules, 8(8), 2337-2341.
Available at: https://aquila.usm.edu/fac_pubs/15200