Search results for "Polymers."
showing 10 items of 3543 documents
Synthesis and noncovalent protein conjugation of linear-hyperbranched PEG-poly(glycerol) alpha,omega(n)-telechelics.
2009
Linear-hyperbranched, heterobifunctional alpha,omega(n) telechelic block copolymers consisting of a linear poly(ethylene glycol) (PEG) chain and a hyperbranched polyglycerol (PG) block have been prepared in five steps, using a protected amino-functional initiator. The polyfunctionality omega(n) (OH groups) can be adjusted by the degree of polymerization (DP(n)) of the polyglycerol block. Subsequent introduction of a single biotin unit by amidation in alpha-position permitted noncovalent bioconjugation with avidin.
Directing the self-assembly of semiconducting copolymers: the consequences of grafting linear or hyperbranched polyether side chains.
2013
The synthesis and self-assembly of novel semiconducting rod-coil type graft block copolymers based on poly(para-phenylene vinylene) (PPV) copolymers is presented, focusing on the ordering effect of linear versus hyperbranched side chains. Using an additional reactive ester block, highly polar, linear poly(ethylene glycol), and hyperbranched polyglycerol side chains are attached in a grafting-to approach. Remarkably, the resulting novel semiconducting graft copolymers with polyether side chains show different solubility and side-chain directed self-assembly behavior in various solvents, e.g., cylindrical or spherical superstructures in the size range of 10 to 120 nm, as shown by TEM. By adju…
Hyperbranched Polyglycerols: From the Controlled Synthesis of Biocompatible Polyether Polyols to Multipurpose Applications
2009
Dendritic macromolecules with random branch-on-branch topology, termed hyperbranched polymers in the late 1980s, have a decided advantage over symmetrical dendrimers by virtue of typically being accessible in a one-step synthesis. Saving this synthetic effort once had an unfortunate consequence, though: hyperbranching polymerization used to result in a broad distribution of molecular weights (that is, very high polydispersities, often M(w)/M(n)5). By contrast, a typical dendrimer synthesis yields a single molecule (in other words, M(w)/M(n) = 1.0), albeit by a labor-intensive, multistep process. But 10 years ago, Sunder and colleagues reported the controlled synthesis of well-defined hyperb…
Synthesis and Supramolecular Association of Immobilized NCN-Pincer Platinum(II) Complexes on Hyperbranched Polyglycerol Supports
2004
Pertosylation of hyperbranched polyglycerol (M(n)=2000; M(w)/M(n)=1.3) followed by partial displacement of the tosyl groups with carboxylic acid functionalized NCN-pincer platinum(II) complexes [PtI-2,6-(NMe(2)CH(2))(2)C(6)H(2)-4-COOH], resulted in covalent attachment of the NCN-pincer complexes to the polyglycerol. These functionalized hyperbranched macromolecules have been characterized by (1)H, (13)C, and (195)Pt NMR, UV-visible, and IR spectroscopy. The presence of Pt and I atoms renders them directly visible by transmission electron microscopy (TEM) without staining procedures, which offers images of associated hyperbranched macromolecules. TEM micrographs show disk-shaped structures w…
Inhalable polymer-glycerosomes as safe and effective carriers for rifampicin delivery to the lungs
2016
Rifampicin loaded glycerosomes, vesicles composed of phospholipids, glycerol and water, were combined with trimethyl chitosan chloride (TMC) to prepare TMC-glycerosomes or, alternatively, with sodium hyaluronate (HY) to obtain HY-glycerosomes. These new hybrid nanovesicles were tested as carriers for pulmonary delivery of rifampicin. Glycerosomes without polymers were also prepared and characterized. All vesicles were similar: they were spherical, multilamellar and able to incorporate good amount of rifampicin (EE%∼55%). The addition of the polymers to the formulations allowed an increase of mean diameter. All the glycerosomes, in particular HY-glycerosomes, were able to deliver the drug to…
Hybrid Organic-Inorganic Nanostructures Fabricated from Layer-by-Layer Self-Assembled Multilayers of Hyperbranched Polyglycerols and Phosphorus Dendr…
2007
Multilayer thin films of cationic phosphorous dendrimers and anionic hyperbranched polyglycerols were fabricated by electrostatic layer-by-layer (LbL) self-assembly (SA). The film formation was monitored by surface plasmon resonance (SPR) spectroscopy and UV-visible spectroscopy, and it was found that the stepwise, alternating deposition results in a linear growth up to four bilayers. Hybrid organic-TiO2 nanostructures were generated by exposing the supramolecular multilayers to TiCl4 precursors. The amounts of TiO2 incorporated inside the scaffolds could be tuned by controlling the porosity of the multilayers with the addition of a small amount of salts. The resulting hybrid films exhibit …
Stable, hydroxyl functional polycarbonates with glycerol side chains synthesized from CO(2) and isopropylidene(glyceryl glycidyl ether).
2012
A series of functional polycarbonates, poly((isopropylidene glyceryl glycidyl ether)-co-(glycidyl methyl ether) carbonate) (P((IGG-co-GME) C)) random copolymers with different fractions of 1,2-isopropylidene glyceryl glycidyl ether (IGG) units, is synthesized. After acidic hydrolysis of the acetal protecting groups, a new type of functional polycarbonate prepared directly from CO(2) and glycerol is obtained, namely poly((glyceryl glycerol)-co-(glycidyl methyl ether) carbonate) (P((GG-co-GME) C)). All hydroxyl functional samples exhibit monomodal molecular weight distributions with PDIs between 2.5 and 3.3 and M(n) between 12 000 and 25 000 g mol(-1) . Thermal properties reflect the amorphou…
Squaric Acid Mediated Synthesis and Biological Activity of a Library of Linear and Hyperbranched Poly(Glycerol)-Protein Conjugates
2012
Polymer-protein conjugates generated from side chain functional synthetic polymers are attractive because they can be easily further modified with, for example, labeling groups or targeting ligands. The residue specific modification of proteins with side chain functional synthetic polymers using the traditional coupling strategies may be compromised due to the nonorthogonality of the side-chain and chain-end functional groups of the synthetic polymer, which may lead to side reactions. This study explores the feasibility of the squaric acid diethyl ester mediated coupling as an amine selective, hydroxyl tolerant, and hydrolysis insensitive route for the preparation of side-chain functional, …
Cytotoxicity and chemosensitizing activity of amphiphilic poly(glycerol)-poly(alkylene oxide) block copolymers.
2014
All polymeric chemosensitizers proposed thus far have a linear poly(ethylene glycol) (PEG) hydrophilic block. To testify whether precisely this chemical structure and architecture of the hydrophilic block is a prerequisite for chemosensitization, we tested a series of novel block copolymers containing a hyperbranched polyglycerol segment as a hydrophilic block (PPO-NG copolymers) on multi-drug-resistant (MDR) tumor cells in culture. PPO-NG copolymers inhibited MDR of three cell lines, indicating that the linear PEG can be substituted for a hyperbranched polyglycerol block without loss of the polymers' chemosensitizing activity. The extent of MDR reversal increased with the polymers affinity…
Phosphonylation Controls the Protein Corona of Multifunctional Polyglycerol-Modified Nanocarriers.
2018
Nanocarriers are a platform for modern drug delivery. In contact with blood, proteins adsorb to nanocarriers, altering their behavior in vivo. To reduce unspecific protein adsorption and unspecific cellular uptake, nanocarriers are modified with hydrophilic polymers like poly(ethylene glycol) (PEG). However, with PEG the attachment of further functional structures such as targeting units is limited. A method to introduce multifunctionality via polyglycerol (PG) while maintaining the hydrophilicity of PEG is introduced. Different amounts of negatively charged phosphonate groups (up to 29 mol%) are attached to the multifunctional PGs (Mn 2-4 kg mol-1 , Ð < 1.36) by post-modification. PGs are …