Responsive glyco-poly(2-oxazoline)s: synthesis, cloud point tuning, and lectin binding

A new sugar-substituted 2-oxazoline monomer was prepared using the copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. Its copolymerization with 2-ethyl-2-oxazoline as well as 2-(dec-9-enyl)-2-oxazoline, yielding well-defined copolymers with the possibility to tune the properties by thiol-ene "click" reactions, is described. Extensive solubility studies on the corresponding glycocopolymers demonstrated that the lower critical solution temperature behavior and pH-responsiveness of these copolymers can be adjusted in water and phosphate-buffered saline (PBS) depending on the choice of the thiol. By conjugation of 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose and subsequent deprotection of the sugar moieties, the hydrophilicity of the copolymer could be increased significantly, allowing a cloud-point tuning in the physiological range. Furthermore, the binding capability of the glycosylated copoly(2-oxazoline) to concanavalin A was investigated

Unexpected radical polymerization behavior of oligo(2-ethyl-2-oxazoline) macromonomers

A well-defined oligo(2-ethyl-2-oxazoline)acrylate (OEtOxA) macromonomer was obtained by direct end functionalization of the living cationic oxazolinium species from the cationic ring-opening polymerization of EtOx with in situ deprotonated acrylic acid. Kinetic studies during subsequent reversible addition-fragmentation chain transfer (RAFT) polymerization as well as nitroxide mediated polymerization (NMP) experiments revealed proceeding monomer consumption but no increase of the molar mass of the resulting comb polymers. The chain transfer during the radical polymerizations is proposed to result from backbiting and subsequent beta-scission of the formed mid-chain radical and took place in a well-defined manner, so that POEtOxA could also be obtained by free radical polymerization with a PDI value below 1.2. A series of POEtOxA was synthesized by RAFT polymerization with varying [monomer]/[chain transfer agent] (M/CTA) ratios and analyzed in detail by means of analytical ultracentrifugation and small angle neutron scattering, indicating that the backbone DP does not exceed 25, which is in accordance with the thermal polymer properties in bulk and in aqueous solution (T-g = 32 degrees C, T-cp approximate to 73 degrees C)

Grafting of thio glucose onto styrene and pentafluorostyrene containing polymers prepared via nitroxide mediated polymerization

The prepn. of homo- and copolymers of styrene and pentafluorostyrene was performed via nitroxide-mediated polymn. Well defined polymers were obtained with narrow polydispersity indexes. The polymers were subsequently used for the substitution reaction of acetylated thio glucose to the homopolymer of pentafluorostyrene. The rate of the substitution reaction was followed by 19F-NMR and quant. conversion was obtained in 1 h at room temp. Finally, the deprotection of the thio glucose was performed under mild reaction conditions to yield fluorinated glycopolymers with narrow polydispersity indexes. [on SciFinder (R)

Magnesium Perchlorate as Efficient Lewis Acid: A Simple and Convenient Route to 1,4-Dihydropyridines

A new protocol for the synthesis of various 1,2,3,4-tetrasubstituted 1,4-dihydropyridines from enamino or carbonylic derivatives promoted by Mg(ClO4)2 is presented

Optical coherence tomography angiography characteristics of choroidal neovascularization requiring varied dosing frequencies in treat-and-extend management: An analysis of the AVATAR study.

PurposeTo evaluate optical coherence tomography angiography (OCTA) characteristics of choroidal neovascularization (CNV) in eyes requiring different treatment frequency of anti-vascular endothelial growth factor (VEGF) therapy for neovascular age-related macular degeneration (NVAMD).DesignProspective observational case series.MethodsSubjects who had undergone anti-VEGF treatment for NVAMD in the AVATAR study were subdivided into 3 groups depending on required anti-VEGF dosing: (i) treat-and-extend requiring every 4-6 weeks dosing (TEq4-6w), (ii) treat-and-extend requiring every 7-12 weeks dosing (TEq7-12w), (iii) eyes not requiring injection within last 12 months (PRN >12mo). OCTA images were evaluated for the morphological characteristics of CNV and the choriocapillaris flow void.ResultsStudy consisted 40 eyes of 31 patients with a mean age of 79.9 ± 6.2 years. CNV morphology analysis on OCTA was feasible in 29 (73%) eyes. Ninety percent of CNVs in TEq7-12w group were irregular in shape involving foveal center, while 67% of CNVs in PRN>12mo group were circular in shape sparing foveal center. Among three groups, statistical difference was found in CNV shape (P = .012) and CNV location (P = .003), while no statistical difference was found in the CNV area (P = .14), vessel density (P = .19), presence of core vessels (P = .23), the presence of small margin loops (P = .20), large margin loops (P = .14), CNV maturity (P = .40), or the mean percentage of choriocapillaris area with flow void (P = .66).ConclusionThe combination of CNV sparing the foveal center with higher circularity may suggest a clinically inactive CNV following initial anti-VEGF therapy. We found minimal distinguishing OCTA characteristics between those eyes that required ongoing therapy with the treat-and-extend regimen. More research is needed to identify specific CNV characteristics on OCTA that may become a useful tool for the management of NVAMD and timing of treatment