Synthesis of heterotelechelic polymers with affinity to glutathione-S-transferase and biotin-tagged proteins by RAFT polymerization and thiol–ene reactions

Abstract

a-Glutathione (GSH), u-biotin functionalized poly(N-isopropylacrylamide) (PNIPAAm) was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization using a new R-group allyl functionalized trithiocarbonate chain transfer agent (CTA) and thiol-ene reactions. GPC and 1 H NMR results indicated that the allyl group had no adverse effect on the RAFT-controlled polymerization of NIPAAm and PEG-A, and the new CTA could efficiently control the polymerizations. Employing radical thiol-ene and Michael addition reactions, heterotelechelic a-allyl, u-carboxylic acid-PNIPAAm was first aminolyzed in the presence of maleimide-modified biotin and subsequently reacted with GSH via radical thiol-ene addition to yield a-GSH, u-biotin functionalized PNIPAAm. Glutathione S-transferase (GST) and streptavidin (SAv) were coupled in solution with heterofunctional PNIPAAm via bioaffinity interactions. Separately, a-GSH, u-biotin functionalized PNIPAAm was further shown to bind GST-tagged Rac1, a potential cancer marker, and biotin-tagged bovine serum albumin (BSA).

Telechelic polymers from reversible-deactivation radical polymerization for biomedical applications

“…The non-covalent interaction between GSH and glutathione-S-transferase (GST) was also employed for the synthesis of heterotelechelic polymers. 65 Synthesis of heterotelechelic a-GSH, o-biotin PNIPAAm was performed by RAFT, followed by coupling with GST and SAv in solution. a-GSH, o-biotin PNIPAAm was further shown to separately bind GST-tagged Rac1, a potential cancer marker, and biotin-tagged BSA.…”

Living Radical Polymerization by the RAFT Process – A Third Update

“…[454] This chemistry was also exploited in preparing a heterotelechelic conjugate from a-glutathione-v-biotin-poly(NIPAm). [450] Most of the approaches (a-g above) have also been used in making (non-biopolymer) block, star, and graft copolymers.…”

Phosphites as alternative coreagents for the one‐pot aminolysis/thiol‐ene synthesis of maleimide‐functionalized RAFT polymers

“…The reaction may proceed via a free‐radical8 or nucleophilic Michael‐type addition mechanism 9. The base‐ and nucleophile‐mediated thiol‐ene reaction with activated substrates such as maleimides has been applied on (co)polymers prepared by RAFT polymerization 10–17. Nakayama and Okano11 used 2‐ethanolamine in the aminolysis of dithioester‐terminal poly( N ‐isopropylacrylamide‐ co ‐ N,N ‐dimethylacrylamide) and later reacted with N ‐(1‐pyrene)maleimide.…”

“…Moreover, the use of P(OEt) 3 for a one‐pot aminolysis/thiol‐ene reaction to target maleimide‐functionalized PNIPAM was also investigated in this study. Davis et al10, 14–16 have reported the one‐pot chain‐end modification of polymers obtained by RAFT polymerization using the maleimide‐functionalized biotin. This specific maleimide is unique among maleimides as it is able to prevent bisulfide bonds and to avoid secondary reactions with primary amines.…”