Chemical Engineering / Kimya Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/14

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Author: search.filters.author.Huang, Xin

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  • Article
    Citation - WoS: 17
    Citation - Scopus: 16
    Ph-Labile Sheddable Block Copolymers by Raft Polymerization: Synthesis and Potential Use as Sirna Conjugates
    (Elsevier Ltd., 2013) Huang, Xin; Sevimli, Sema İlknur; Bulmuş, Volga
    Well-defined amphiphilic block copolymers composed of hydrophilic and hydrophobic blocks linked through an acid-labile acetal bond were synthesized directly by RAFT polymerization using a new poly(ethylene glycol) (PEG) macroRAFT agent modified with an acid-labile group at its R-terminal. The new macroRAFT agent was used for polymerization of poly(t-butyl methacrylate) (PtBMA) or poly(cholesterol-methacrylate) (PCMA) to synthesize well-defined block copolymers with a PEG block sheddable under acidic conditions. The chain extension polymerization kinetics showed known traits of RAFT polymerization. The molecular weight distributions of the copolymers prepared using the new macroRAFT agent remained below 1.2 during the polymerizations and the molecular weight of the copolymers was linearly proportional to monomer conversions. The acid-catalyzed hydrolysis behavior of the PEG-macroRAFT agent and the PEG-b-PtBMA (Mn = 13,600 by GPC, PDI = 1.10) was studied by GPC, 1H NMR and UV-vis spectroscopy. The half-life of acid-hydrolysis was 70 min at pH 2.2 and 92 h at pH 4.0. The potential use of the pH-labile shedding behavior of the copolymers was demonstrated by conjugating a thiol-modified siRNA to ω-pyridyldisulfide modified PEG-b-PCMA. The resultant PEG-b-PCMA-b-siRNA triblock modular polymer released PCMA-b-siRNA segment in acidic and siRNA segment in reductive conditions, as confirmed by polyacrylamide gel electrophoresis.
  • Article
    Citation - WoS: 24
    Citation - Scopus: 24
    Synthesis of Heterotelechelic Polymers With Affinity To Glutathione-S and Biotin-Tagged Proteins by Raft Polymerization and Thiol-Ene Reactions
    (Royal Society of Chemistry, 2011) Huang, Xin; Boyer, Cyrille; Davis, Thomas P.; Bulmuş, Volga
    α-Glutathione (GSH), ω-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 1H 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 α-allyl, ω-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 α-GSH, ω-biotin functionalized PNIPAAm. Glutathione S-transferase (GST) and streptavidin (SAv) were coupled in solution with heterofunctional PNIPAAm via bioaffinity interactions. Separately, α-GSH, ω-biotin functionalized PNIPAAm was further shown to bind GST-tagged Rac1, a potential cancer marker, and biotin-tagged bovine serum albumin (BSA).