ABSTRACT
Symmetrical cyclodextrin-based 14-arm star polymers with poly(ethylene glycol) PEG branches were synthesized and characterized. Interactions of the star polymers with lipid bilayers were studied by the "black lipid membrane" technique in order to demonstrate the formation of monomolecular artificial channels. The conditions for the insertion are mainly based on dimensions and amphiphilic properties of the star polymers, in particular the molar mass of the water-soluble polymer branches. Translocation of single-strand DNA (ssDNA) through those synthetic nanopores was investigated, and the close dimension between the cross-section of ssDNA and the cyclodextrin cavity led to an energy barrier that slowed down the translocation process.
Subject(s)
Cell Membrane/chemistry , Cell Membrane/metabolism , Cyclodextrins/chemistry , Polyethylene Glycols/chemistry , Polynucleotides/metabolism , Base Sequence , Biological Transport , DNA/genetics , DNA/metabolism , Lipid Bilayers/chemistry , Lipid Bilayers/metabolismABSTRACT
Anionic polymerization initiated by cyclodextrins suffers from a poor solubility of those derivatives in standard polymerization solvents. The possibility to perform ethylene oxide polymerization initiated by monofunctional initiators (allyl alcohol, 2-methoxyethanol) by living ring opening polymerization in DMF, a good solvent for any CD derivative, was demonstrated by SEC, (1)H and (13)C NMR analyses. The study was extended to the use of native CD as initiator, leading to the synthesis of ill-defined structures, explained by the reactivity scale of the various hydroxyl functions. Two selectively modified CD derivatives are then used to synthesize a new family of star-shaped poly(ethylene oxide) polymers with CD core, having 14 or 21 arms. The polymerization was found to be living and DOSY experiments confirmed the well-defined structures for the synthesized star-polymers.
Subject(s)
Dimethylformamide/chemistry , Ethylene Oxide/chemistry , Polyethylene Glycols/chemical synthesis , Solvents/chemistry , beta-Cyclodextrins/chemistry , Carbohydrate Conformation , Catalysis , Kinetics , Light , Magnetic Resonance Spectroscopy , Polyethylene Glycols/chemistry , Polymerization , Scattering, Radiation , Spectrometry, Mass, Electrospray IonizationABSTRACT
The selective modification of cyclodextrins remains a real challenge to obtain well-defined structures. The targeted cycloheptakis-(1â4)-2,6-di-O-hydroxypropyl-3-O-methyl-α-D-glucopyranosyl [per(2,6-di-O-hydroxypropyl-3-O-methyl)-ß-CD] was obtained by a three-step procedure. The selective allylation of the hydroxyl functions at the positions 2 and 6 was used as a first step. This reaction was revisited then enlarged to α and γ-CDs to determine new conditions for a one-step synthesis in high yield. The per(2,6-di-O-allyl)-ß-CD derivative was then reacted with iodomethane to provide per(2,6-di-O-allyl-3-O-methyl)-ß-CD. Oxidative hydroboration of the allyl functions was then carried out in order to obtain a new CD derivative with seven primary hydroxyl functions on each side of the truncated cone, having a similar reactivity.