Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of present work was to develop a microporous-controlled delivery system for theophylline via coating a blend of PCL and PEG on the surface of tablets, where PCL was the major component of film coating material and PEG was acted as a leachable pore-forming agent when contacting with an aqueous medium. The influences of the type of solvent, the amount of PEG, and the thickness of films on the mechanical and thermal properties of coating films and drug release performance were investigated. The DSC thermograms and FTIR spectra indicated both PCL and PEG remained independently in the blended films. The mechanical data showed a decrease tendency as increase in the amount of PEG in the blends due to highly crystalline character of PEG. Slower evaporation rate of acetone than dichloromethane enhanced phase separation between PCL and PEG during film formation, and resulted in the pore size in films prepared from acetone larger than from dichloromethane. The release rate of coated tablets were increased by increasing the amount of pore-forming agent, and the corresponding values from tablets coated in dichloromethane were less than in acetone. Much denser structure and smaller pore size of films formed from dichloromethane contributed to this result. The release of drug from tablets coated in acetone showed a profile more close to a zero-order constant release profile. The penetration of water into drug core played an important role in influencing drug release pattern.
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PMID:Design of a microporous controlled delivery system for theophylline tablets. 1271 42

Poly(epsilon-caprolactone)-poly(ethylene glycol) (PECL) copolymers were synthesized from polyethylene glycol (PEG) and epsilon-caprolactone (epsilon-CL) using stannous octoate as catalyst at 160 degrees C by bulk polymerization. The effect of the molecular weight of PEG and the copolymer ratio on the properties of the copolymers was investigated by (1)H-NMR, IR, DSC and GPC. PCL and PECL microspheres containing human serum albumin were elaborated by solvent extraction method based on the formation of double w/o/w emulsion. Microspheres were characterized in terms of morphology, size, loading efficiency, and the efficiency of microspheres formation. The results show that the microspheres prepared from PECL-10 and PECL-15 copolymers achieved the highest loading efficiency (about 50%) among all copolymers. These results indicate that the properties of copolymers could be tailored by adjusting polymer composition. It is suggested that these matrix polymers may be optimized as carriers in the protein (antigen) delivery system for different purposes.
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PMID:Biodegradable poly(epsilon-caprolactone)-poly(ethylene glycol) block copolymers: characterization and their use as drug carriers for a controlled delivery system. 1280 85

The design of surface-engineered nanoparticles for targeting to specific sites is a major challenge. To our knowledge, no study in the literature deals with ligand functionalization of biodegradable nanoparticles through biotin-avidin interactions. With the aim of conceiving small-sized nanoparticles which can be easily functionalized with a variety of ligands or mixtures thereof, biotinylated and PEGylated biotin-poly(ethylene glycol)-poly(epsilon-caprolactone) (B-PEG-PCL) copolymers were synthesized and used to prepare nanoparticles of around 100 nm. Avidin, followed by biotinylated wheat germ agglutinin as a model lectin, were coupled to their surface by taking advantage of the strong biotin-avidin complex formation. The cytotoxicity of the nanospheres towards Caco-2 cells in culture was negligible (more than 82% cell survival for nanoparticle concentrations up to 300 microg/well). The amount of radiolabeled poly(lactic acid) (PLA) or PEG-PLA nanoparticles associated with Caco-2 cells was only 0.7% and 1.5% of the amount added, respectively. This value was increased to 8.5% when a sufficient amount of lectin was bound to the PEG-PLA copolymer. After further studies, the biotin-PEG-coated nanoparticles could be helpful tools for studying the interaction between cells and functionalized nanoparticles with various surface characteristics (PEG layer density and thickness, ligand type and density).
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PMID:Surface-engineered nanoparticles for multiple ligand coupling. 1292 62

Alternating amphiphilic multiblock copolymers, consisting of polyoxyethylene (POE) and poly(epsilon-caprolactone) (PCL) of various lengths, were synthesized by a polycondensation reaction between dicarboxylated PEG and dihydroxyl PCL. The polymer formed a physical hydrogel by PCL crystallization. For in vitro hydrolysis in phosphate-buffered saline solution, the change of molecular weight depended on the composing block length of POE. The polymer with longer POE showed a faster decline in molecular weight. The mass remaining at the end of two weeks at 25 degrees C was more than 95 w%. However, when the swollen hydrogels were exposed to temperatures slightly above PCL melting point for 30 min, the degradation rate was accelerated and the mass remaining dropped to less than 10 wt% in one week. In vivo degradation after hydrogel implantation, the polymer degraded as under in vitro. However, the implant irradiated with infrared (IR) accelerated its degradation similar to a treatment with elevated temperature.
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PMID:In situ accelerated degradation of polyoxyethylene/poly(epsilon-caprolactone) multiblock copolymer by moderate thermal treatment. 1466 69

Poly(epsilon-caprolactone)/poly(ethylene glycol) (abbreviated as CE) diblock copolymers were synthesized to make core-shell type nanoparticles for all-trans-retinoic acid (atRA). Fluorescence spectroscopy showed that critical association concentration (CAC) value decreased at higher MW of CE diblock copolymer. Drug loading characteristics were studied under various experimental conditions. Drug contents and loading efficiency increased as the MW of poly(epsilon-caprolactone) (PCL) block of CE and initial drug feeding amount increased. Solvent used and preparation method also affected drug contents and loading efficiency. According to 1H NMR using CDCl3 and D2O, specific peaks of the PCL block and drug appearing in CDCl3, disappeared at D2O, suggesting hydrophobic core with hydrophilic shell formed in water. atRA release was faster at smaller MW of copolymer and lower drug contents. Nanoparticles prepared in DMF showed faster release rate compared with those prepared in THF or acetone. Cytotoxicity of atRA against U87MG, U251MG and U343MG cell lines were increased by nanoencapsulation while empty nanoparticles of CE diblock copolymer were not significantly affected.
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PMID:All-trans-retinoic acid release from core-shell type nanoparticles of poly(epsilon-caprolactone)/poly(ethylene glycol) diblock copolymer. 1501 Jan 34

Controlled release polymer vesicles are prepared using hydrolysable diblock copolymers of polyethyleneglycol-poly-l-lactic acid (PEG-PLA) or polyethyleneglycol-polycaprolactone (PEG-PCL). Encapsulation studies with a common anti-cancer agent, doxorubicin, show loading comparable to liposomes. Rates of encapsulant release from the hydrolysable vesicles are accelerated with an increased proportion of PEG but are delayed with a more hydrophobic chain chemistry (i.e. PCL). Rates of release also rise linearly with the molar ratio of degradable copolymer blended into membranes of a non-degradable, PEG-based block copolymer (PEG-polybutadiene (PBD)). With all compositions, in both 100 nm and giant vesicles, the average release time (from hours to days) reflects a highly quantized process in which any given vesicle is either intact and retains its encapsulant, or is porated and slowly disintegrates. Poration occurs as the hydrophobic PLA or PCL block is hydrolytically scissioned, progressively generating an increasing number of pore-preferring copolymers in the membrane. Kinetics of this evolving detergent mechanism overlay the phase behavior of amphiphiles with transitions from membranes to micelles allowing controlled release.
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PMID:Self-porating polymersomes of PEG-PLA and PEG-PCL: hydrolysis-triggered controlled release vesicles. 1506 28

Poly(epsilon-caprolactone) (PCL) and its block copolymers with poly(ethylene glycol) (PEG) were prepared by ring-opening polymerization of epsilon-caprolactone in the presence of ethylene glycol or PEG, using zinc metal as catalyst. The resulting polymers were characterized by various analytical techniques such as (1)H NMR, SEC, DSC, IR, X-ray, ESEM, and CZE. PCL/PEG copolymers with long PCL chains presented the same crystalline structure as PCL homopolymer, whereas PEG-bearing short PCL blocks retained the crystalline structure of PEG and exhibited an amphiphilic behavior in aqueous solutions. Degradation of PCL and PCL/PEG diblock and triblock copolymers was realized in a 0.13 M, pH 7.4 phosphate buffer at 37 degrees C. The results indicated that the copolymers exhibited higher hydrophilicity and degradability compared with the PCL homopolymer. Large amounts of PEG were released from the bulk after 60 weeks' degradation. In vitro cell culture studies were conducted on scaffolds manufactured via solid free form fabrication by using primary human and rat bone marrow derived stromal cells (hMSC, rMSC). Light, scanning electron, and confocal laser microscopy, as well as immunocytochemistry, showed cell attachment, proliferation, and extracellular matrix production on the surface, as well as inside the scaffold architecture. Copolymers showed better performance in the cell culture studies than the PCL homopolymer.
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PMID:Degradation and cell culture studies on block copolymers prepared by ring opening polymerization of epsilon-caprolactone in the presence of poly(ethylene glycol). 1512 88

Cross-linkable di- and triblock copolymers of poly(epsilon-caprolactone) (PCL) and monomethoxyl poly(ethylene glycol) (MPEG) were synthesized. These amphiphilic copolymers self-assembled into nanoscale micelles capable of encapsulating hydrophobic paclitaxel in their hydrophobic cores in aqueous solutions. To further enhance their thermodynamic stability, the micelles were cross-linked by radical polymerization of the double bonds introduced into the PCL blocks. Reaction conditions were found to significantly affect both the cross-linking efficiency and the micelle size. The encapsulation of paclitaxel into the micelles was confirmed by the proton nuclear magnetic resonance (1H NMR) spectroscopy. Encouragingly, paclitaxel-loading efficiency of micelles was enhanced significantly upon micelle core-cross-linking. Both the micelle size and the drug loading efficiency increased markedly with increasing the PCL block lengths, no matter if the micelles were core-cross-linked or not. However, paclitaxel-loading did not obviously affect the micelle size or size distribution. The cross-linked micelles exhibited a significantly enhanced thermodynamic stability against dilution with aqueous solvents. The efficient cellular uptake of paclitaxel loaded in the nanomicelles was demonstrated by confocal laser scanning microscopy (CLSM) imaging. This new biodegradable nanoscale carrier system merits further investigations for parenteral drug delivery.
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PMID:Core-cross-linked polymeric micelles as paclitaxel carriers. 1514 70

In this study, we prepared diblock copolymers of poly(epsilon-caprolactone) (PCL) and poly(ethylene glycol) (PEG) by aluminum alkoxide catalysts. The biological responses to the spin cast surface of different PCL/PEG diblock copolymers were investigated in vitro. Our results showed that surface hydrophilicity improved with the increased PEG segments in diblock copolymers and that bacteria adhesion was inhibited by increased PEG contents. PCL-PEG 23:77 showed nanotopography on the surface. The number of adhered endothelial cells, platelets and monocytes on diblock copolymer surfaces was inhibited in PCL-PEG 77:23 and enhanced in PCL-PEG 23:77. Nevertheless, the platelet and monocyte activation on PCL-PEG 23:77 was reduced. PCL-PEG 23:77 had better cellular response as well as lower degree of platelet and monocyte activation. The current study was the first one to demonstrate that surface nanotopography could influence not only cell adhesion and growth but also platelet and monocyte activation.
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PMID:Biocompatibility of poly(epsilon-caprolactone)/poly(ethylene glycol) diblock copolymers with nanophase separation. 1515 75

The polymerization of epsilon-caprolactone (epsilon-CL) was initiated by the terminal alcohol of methoxy poly(ethylene glycol) (MPEG) as an initiator via activated ring-opening polymerization in the presence of HCl. Et2O as a monomer activator. The molecular weights of the poly(epsilon-caprolactone) (PCL) in MPEG-PCL diblock copolymers controlled with the feed ratio of epsilon-CL to MPEG. The polymerization was preceded by living fashion with no termination or chain transfer. This polymerization procedure offered MPEG-PCL diblock copolymers with well-defined structures. The gel-to-sol transitions of MPEG-PCL diblock copolymer solutions were also examined. The diblock copolymers synthesized with various MPEG and PCL lengths were dissolved in water at 80 degrees C in various concentrations. The polymer solutions formed gel at room temperature. The formed gel became fluids again by increasing the temperature. The gel-to-sol transition showed strong dependence on the length of the MPEG and PCL diblock segments. When the polymer solution was injected into rat, it became a gel at body temperature. The formed gel maintained for 1 month. We confirmed that MPEG-PCL diblock copolymers with well-defined structures served as new thermo-sensitive biomaterials.
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PMID:Preparation of poly(ethylene glycol)-block-poly(caprolactone) copolymers and their applications as thermo-sensitive materials. 1517 20


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