Carboxyl end‐functionalized poly[poly(ethylene glycol) methyl ether methacrylate] [P(PEGMEMA)] and its block copolymer with gemcitabine substituted poly(N‐hydroxysuccinimide methacrylate) [PGem‐block‐P(PEGMEMA)] are synthesized via reversible addition‐fragmentation transfer (RAFT) polymerization. Then, two polymers are grafted onto the surface of amine‐functionalized nanodiamonds to obtain [P(PEGMEMA)]‐grafted nanodiamonds (ND‐PEG) and [PGem‐block‐P(PEGMEMA)]‐grafted nanodiamonds (ND‐PF). Gemcitabine is physically absorbed to ND‐PEG to produce ND‐PEG (Gem). Two polymer‐grafted nanodiamonds (i.e., with physically absorbed gemcitabine ND‐PEG (Gem) and with chemically conjugated gemcitabine ND‐PF) are characterized using attenuated total reflectance infrared spectroscopy, dynamic light scattering, and thermogravimetric analysis. The drug release, cytotoxicity (to seed human pancreatic carcinoma AsPC‐1 cells), and cellular uptake of ND‐PEG (Gem) and ND‐PF are also investigated.
A series of well‐defined triblock copolymers, poly(N, N‐dimethylacrylamide)‐block‐poly(ethylene oxide)‐block‐poly(N, N‐dimethylacrylamide) (PDMA‐b‐PEO‐b‐PDMA) synthesized by atom transfer radical polymerization, were used as physical coatings for protein separation. A comparative study of EOF showed that the triblock copolymer presented good capillary coating ability and EOF efficient suppression. The effects of the Mr of PDMA block in PDMA‐b‐PEO‐b‐PDMA triblock copolymer and buffer pH on the separation of basic protein for CE were investigated. Moreover, the influence of the copolymer structure on separation of basic protein was studied by comparing the performance of PDMA‐b‐PEO‐b‐PDMA triblock copolymer with PEO‐b‐PDMA diblock copolymer. Furthermore, the triblock copolymer coating showed higher separation efficiency and better migration time repeatability than fused‐silica capillary when used in protein mixture separation and milk powder samples separation, respectively. The results demonstrated that the triblock copolymer coatings would have a wide application in the field of protein separation. 相似文献
The impact of the molecular architecture on the transfection efficiency of PEGylated poly(amino acid) block copolymers was investigated for PEG‐b‐p(l ‐Lys)x‐b‐p(l ‐Leu)y, PEG‐b‐p(l ‐Leu)x‐b‐p(l ‐Lys)y, and PEG‐b‐p((l ‐Leu)x‐co‐(l ‐Lys)y). The block lengths of p(l ‐Lys) and p(l ‐Leu) were varied between 10, 20, and 40; and 10 and 20, respectively, to study the influence of the ionic/hydrophobic balance. The results show that ABC triblock copolymers form smaller and more stable polyplexes with plasmid DNA than AB diblock copolymers—as verified by long‐term aggregation and ethidium bromide exclusion studies—protect the DNA more effectively against nucleases, and provide better transfection efficiencies, as indicated by total protein as well as luciferase expression. More detailed studies revealed that triblock copolymers with p(l ‐Leu) forming the C‐block were most efficient in DNA complexation with a 2.3 times higher transfection rate. Furthermore, increasing the cationic character by increasing the p(l ‐Lys) chain length led to up to 25% higher transfection but at the same time induced some cytotoxicity. Diblock copolymers, where the amino acid–building blocks exist as a random copolymer, bind more loosely with DNA leading to less compact and less stable aggregates with lower transfection efficiencies. 相似文献
An electroactive triblock copolymer of poly(ethylene glycol) (PEG) and aniline pentamer (AP), PEG‐block‐AP‐block‐PEG (PAP), was synthesized via polycondensation in the presence of N,N'‐dicyclohexylcarbodiimide (DCC). The UV‐vis spectra and cyclic‐voltammograms (CV) spectra exhibited an excellent electroactivity of the triblock copolymer. The amphiphilic triblock copolymer self‐assembles spontaneously into uniform micellar aggregates when the triblock copolymer was added directly to the aqueous solution. The size of the aggregates can be changed with the oxidation state of the AP segment in the PAP copolymer and the aggregates were pH‐sensitive to the surrounding water solution, which provides a potential application in controlled drug release.
Anionic polymerization of isoprene initiated by an alkyl lithium containing a silyl ether protected hydroxyl functionality followed by termination with ethylene oxide gave α,ω‐functionalized polyisoprene with narrow molecular weight distribution and prescribed molecular weight in high yield. Deprotection resulted in α,ω‐hydroxyl polyisoprene (HO‐PI‐OH) that was reacted with triethylaluminium to form the corresponding aluminium alkoxide macroinitiator. The macroinitiator was used for the controlled polymerization of lactide to yield polylactide‐block‐polyisoprene‐block‐polylactide triblock copolymers with narrow molecular weight distributions and free of homopolymer (HO‐PI‐OH) contamination. Microphase separation in these novel triblock copolymers was confirmed by SAXS and DSC. 相似文献
The anionic ring-opening polymerization of L-lactide was initiated by dipotassium-poly-isobutylene-alcoholate telechelic polymer to yield poly(L -lactide)-block-polyisobutylene-block-poly(L -lactide) triblock copolymer, a partially biodegradable thermoplastic elastomer. The pure triblock copolymer was obtained by gradient column chromatography on silica gel. The molar mass and molar mass distribution of the block copolymer was ascertained by SEC and quantitative 1H NMR spectroscopy. It showed two glass transitions and microphase separation. 相似文献
Summary: Spherical micelles have been formed by mixing, in DMF, a poly(styrene)‐block‐poly(2‐vinylpyridine)‐block‐poly(ethylene oxide) (PS‐block‐P2VP‐block‐PEO) triblock copolymer with either poly(acrylic acid) (PAA) or a tapered triblock copolymer consisting of a PAA central block and PEO macromonomer‐based outer blocks. Noncovalent interactions between PAA and P2VP result in the micellar core while the outer corona contains both PS and PEO chains. Segregation of the coronal chains is observed when the tapered copolymer is used.
Inclusion of comb‐like chains with short PEO teeth in the corona triggers the nanophase segregation of PS and PEO as illustrated here (PS = polystyrene; PEO = poly(ethylene oxide)). 相似文献
To mediate selective gene delivery to hepatocytes via the asialoglycoprotein receptors (ASGP‐Rs), we designed and synthesized well‐defined and narrowly dispersed galactose‐ and glucose‐functionalized cationic polycarbonate diblock copolymers (designated as Gal‐APC and Glu‐APC, respectively) using organocatalytic ring‐opening polymerization of functionalized carbonate monomers, with a subsequent quaternization step using bis‐tertiary amines to confer quaternary and tertiary amines for DNA binding and endosomal buffering, respectively. The sugar‐functionalized diblock copolymers effectively bound and condensed DNA to form positively charged nanoparticles (<100 nm in diameter and ≈30 mV zeta‐potential) that were stable under high physiological salt conditions. In comparison to the control Glu‐APC/DNA complexes, Gal‐APC/DNA complexes mediated significantly higher gene expression in ASGP‐R positive HepG2 cells with no significant difference observed in ASGP‐R negative HeLa cells. The co‐incubation of Gal‐APC/DNA complexes with a natural ASGP‐R ligand effectively led to a decrease in gene expression, hence providing evidence for the ASGP‐R mediated endocytosis of the polyplexes. Importantly, the Gal‐APC/DNA complexes induced minimal cytotoxicities in HepG2 cells at the N/P ratios tested. Taken together, the galactose‐functionalized cationic polycarbonate diblock copolymer has potential for use as a non‐viral gene vector for the targeted delivery of therapeutic genes to hepatocytes in the treatment of liver diseases.