Controlled release of fluorouracil (5-FU) from chitosan-co-poly(ethylene glycol)/ poly(glycerol sebacate)-co-poly(ethylene glycol)-coated iron oxide

A blend of polyglycerol sebacate-poly ethylene glygol/chitosan-poly ethylene glycol-coated iron oxide (PGS-PEG/CS-PEG@Fe₃O₄) nanoparticles for 5FU delivery was prepared by reverse ultrasonic emulsification method. To enhance polymers’ solubility, PEG was grafted. Chemical characterization was performed through Fourier transformed infrared and proton nuclear magnetic resonance spectra. In vitro assay revealed that release profile of 5FU-loaded PGS-PEG/CS-PEG@Fe₃O₄ is sustained. Moreover, cytotoxicity was analyzed on HT29 cell line at the presence of external magnetic field using the lactate dehydrogenase and Alamar Blue. Results illustrate that (PGS-PEG/CS-PEG@Fe₃O₄) is promising to use as a carrier for 5FU anticancer agent with sustained tailored release.     

Synthesis of monomethoxy poly(ethylene glycol) without diol poly(ethylene glycol)

Since monomethoxy poly(ethylene glycol) (mPEG) inevitably contains diol PEG and is difficult to get high molecular weight through traditional synthesis at high temperature under high pressure, a novel synthetic technique via anionic solution polymerization was reported in this study. With a new initiating system, potassium naphthalene and methanol, was introduced, the polymerization proceeded at ambient temperature and side reactions were well restrained. Furthermore, a slight excess of potassium naphthalene can effectively remove the trace of water and oxygen in the reaction system. Under this condition, mPEG was nearly quantitatively obtained without containing diol PEG. Its Mn ranged from 1 to 30 kDa and the polydispersity was kept lower than 1.07. Characterization of the mPEG obtained was carried out using GPC to determine the content of diol PEG and ¹H‐NMR and MALDI‐ToF MS spectroscopic analysis to confirm the exact structure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Voltammetry in viscous poly(ethylene glycol) solutions at microelectrodes

Voltammetric currents of the ferrocenyl derivative in highly viscous poly(ethylene glycol) solution (PEG) at microelectrodes were independent of their viscosity, contrary to the prediction from the diffusion-controlled current combined with the Stokes–Einstein equation. The usage of microelectrodes generally prevents deformation of voltammograms by poor conductivity. However, the voltammograms even at the disk electrode 10 μm in diameter and slow scan rates exhibited hysteresis, because the diffusion coefficient in PEG was smaller than in water owing to high viscosity of the solution. The diffusion coefficients evaluated from the peak current through the diffusion equation at microelectrode were of the order of 10⁻⁷ cm² s⁻¹ for the viscosity ranging from 0.1 to 160 Pa s. They are at most by 1000 times larger than the values calculated from the viscosities by the Stokes–Einstein equation. A practical significance of this result is to suggest a possibility of using highly viscous PEG as solid-like solvents without large restriction of mass transport. A possible diffusion model is that the redox species diffuses through lowly viscous local domains, avoiding collision with the backbone of the polymer network.     

氨基化单甲氧基聚乙二醇的合成研究

首先合成了单甲氧基聚乙二醇对甲苯磺酸酯(mPEG-OTs),然后根据盖布瑞尔合成法原理,以邻苯二甲酰亚胺钾盐(PPI)为亲核试剂与mPEG-OTs反应,生成单甲氧基聚乙二醇的邻苯二甲酰亚胺衍生物(mPEG-PI),mPEG-PI与水合肼反应肼解生成伯胺,合成了一端为氨基的单甲氧基聚乙二醇(mPEG-NH2)。讨论了缚酸剂、溶剂、反应条件对反应的影响。通过红外、液质联用、核磁共振谱图证实了产物与目标分子的结构相吻合。     

Nanocomposite polymer electrolytes containing silica nanoparticles: Comparison between poly(ethylene glycol) and poly(ethylene oxide) dimethyl ether

Nanocomposite polymer electrolytes consisting of low molecular weight poly(ethylene oxide) (PEO), iodine salt MI (M = K⁺, imidazolium⁺), and fumed silica nanoparticles have been prepared and characterized. The effect of terminal group in PEO, i.e., hydroxyl (? OH) and methyl (CH₃) using poly(ethylene glycol) (PEG) and PEO dimethyl ether (PEODME), respectively, was investigated on the interactions, structures, and ionic conductivities of polymer electrolytes. Wide angle X‐ray scattering (WAXS), differential scanning calorimetry (DSC), and complex viscositymeasurements clearly showed that the gelation of PEG electrolytes occurred more effectively than that of PEODME electrolytes. It was attributed to the fact that the hydroxyl groups of PEG participated in the hydrogen‐bonding interaction between silica nanoparticles, and consequently helped to accelerate the gelation reaction, as confirmed by FTIR spectroscopy. Because of its interaction, the ionic conductivities of PEG electrolytes (maximum value ～ 6.9 × 10^?4 S/cm) were lower than that of PEODME electrolytes (2.3 × 10^?3 S/cm). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Biodegradability of poly(ethylene terephthalate) copolymers with poly(ethylene glycol)s and poly(tetramethylene glycol)

Poly(ethylene terephthalate) copolymers were prepared by melt polycondensation of dimethyl terephthalate and excess ethylene glycol with 10–40mol% (in feed) of poly(ethylene glycol) (E) and poly(tetramethylene glycol) (B), with molecular weight (MW) of E and B 200–7500 and 1000, respectively. The reduced specific viscosity of copolymers increased with increasing MW and content of polyglycol comonomer. The temperature of melting (T_m), cold crystallization and glass transition (T_g) decreased with the copolymerization. T_m depression of copolymers suggested that the E series copolymers are the block type at higher content of the comonomer. T_g was decreased below room temperature by the copolymerization, which affected the crystallinity and the density of copolymer films. Water absorption increased with increasing content of comonomer, and the increase was much higher for E1000 series films than B1000 series films. The biodegradability was estimated by weight loss of copolymer films in buffer solution with and without a lipase at 37°C. The weight loss was enhanced a little by the presence of a lipase, and increased abruptly at higher comonomer content, which was correlated to the water absorption and the concentration of ester linkages between PET and PEG segments. The weight loss of B series films was much lower than that of E series films. The abrupt increase of the weight loss by alkaline hydrolysis is almost consistent with that by biodegradation.     

Self-assembly of thermo-responsive poly(oligo(ethylene glycol) methyl ether methacrylate)-C60 in water-methanol mixtures

Well-defined statistical copolymer of poly (di(ethylene glycol) methyl ether methacrylate-stat-oligo(ethylene glycol) methyl ether methacrylate-C₆₀ ((PMEO₂MA-stat-POEGMA₃₀₀)-C₆₀) was synthesized via atom transfer radical polymerization (ATRP) reaction and atom transfer radical addition (ATRA) processes. The lower critical solution temperature (LCST) of PMEO₂MA-stat-POEGMA₃₀₀ increased from 42 to 95 °C when the amounts of methanol was increased from 0 to 30 vol%, beyond which the LCST could not be quantified. Similarly, the LCST of (PMEO₂MA-stat-POEGMA₃₀₀)-C₆₀ also increased with methanol content, however it was lower than PMEO₂MA-stat-POEGMA₃₀₀ for all methanol/water compositions. The CMC of (PMEO₂MA-stat-POEGMA₃₀₀)-C₆₀ increased with increasing methanol content, suggesting that methanol is a better solvent for PMEO₂MA-stat-POEGMA₃₀₀ segment. The amphiphilic (PMEO₂MA-stat-POEGMA₃₀₀)-C₆₀ structure formed spherical micelles in water/methanol mixture, and larger micelles were formed at higher methanol content. The hydrodynamic radius (R_h) remained constant at temperature below the LCST. It increased dramatically at temperature greater than the LCST, and the (R_g/R_h) increased from ∼0.75 to ∼1.0. We believe that the (PMEO₂MA-stat-POEGMA₃₀₀) coronas dehydrate at higher temperature, and the micelles associate to form larger aggregates. In water/methanol mixtures, core-shell micelles and large compound micelles are produced below and above the LCST respectively.     

Paclitaxel-incorporated nanoparticles using block copolymers composed of poly(ethylene glycol)/poly(3-hydroxyoctanoate)

Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a ¹H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.) was analyzed with gel permeation chromatography (GPC). Paclitaxel as a model anticancer drug was incorporated into the nanoparticles of PHO/PEG block copolymer. They have spherical shapes and their particle sizes were less than 100 nm. In a ¹H-NMR study in D₂O, specific peaks of PEG solely appeared while peaks of PHO disappeared, indicating that nanoparticles have core-shell structures. The higher M.W. of PEG decreased loading efficiency and particle size. The higher drug feeding increased drug contents and average size of nanoparticles. In the drug release study, the higher M.W. of PEG block induced the acceleration of drug release rate. The increase in drug contents induced the slow release rate of drug. In an antitumor activity study in vitro, paclitaxel nanoparticles have practically similar anti-proliferation activity against HCT116 human colon carcinoma cells. In an in vivo animal study using HCT116 colon carcinoma cell-bearing mice, paclitaxel nanoparticles have enhanced antitumor activity compared to paclitaxel itself. Therefore, paclitaxel-incorporated nanoparticles of PHO/PEG block copolymer are a promising vehicle for antitumor drug delivery.     

单端马来酰亚胺基功能化聚乙二醇的制备

以PEG2000为初始原料,通过与小分子的反应,将其一端羟基保留,得到NH2-PEG2000-OH,然后将NH2-PEG2000-OH与6-(马来酰亚胺基)己酸琥珀酰亚胺酯反应,得到单端马来酰亚胺基修饰的聚乙二醇(Mal-(CH2)5-CONH-PEG2000-OH)。经过1H NMR验证,结果表明,通过这条合成路线能够成功得到单端马来酰亚胺基功能化的聚乙二醇。     

Facile and controllable synthesis of hybrid silica nanoparticles densely grafted with poly(ethylene glycol)

We report that a mixture of good and poor solvents greatly enhances the grafting density of nanosized silica grafted with poly(ethylene glycol) (PEG ) by the ‘grafting to’ method. Methoxypolyethylene glycol (MPEG ) (molecular weight 750, 2000 and 4000 g mol^?1) was modified in a controlled manner to prepare epoxide terminated PEG (MPEG‐EO ). Silica nanoparticles were modified with N ‐(2‐aminoethy)‐3‐aminopropylmethyldimethoxysilane through the silanization coupling reaction to obtain a well‐defined siloxane structure. MPEG‐EO was coupled to the modified silica by the reaction of their terminal groups in a mixed solvent (n ‐decane/toluene). The grafting density of MPEG‐EO was found to be controlled by the concentration of MPEG‐EO and the ratio of n ‐decane to toluene in the grafting system. Based on TGA , the maximum grafting density was found to be about 2.8, 1.47 and 0.76 chains nm^?2 for molecular weights of 750, 2000 and 4000, respectively, which is extremely high compared to previous reports. This high grafting density can be explained by the decreased chain dimension of PEG in the presence of the poor solvent. The method can be applied to other nanoparticles and polymers which can greatly enhance the application of SiO₂ nanocomposites. © 2017 Society of Chemical Industry     

Complexation of pepsin poly(ethylene glycol)

Summary Complexation of porcine pepsin (or pepsin A) (EC.3.4.23.1) with poly(ethylene glycol) (PEG) in an aqueous solution was studied as a function of pH and PEG concentration. The addition of PEG increased the reduced viscosity of the enzyme solution at pH 3 but not at pH 4.5. An increase in pH was observed by mixing both PEG and enzyme solutions which were previously adjusted to pH 3. Under conditions of pH 2.5–3 and 50°C, PEG contributed to an increase in the hydrolyzing activity of pepsin towardN-acetyl-l-phenylalanyl-3,5-diiodo-l-tyrosine. These results indicate that pepsin forms a water-soluble complex with PEG mainly through hydrogen bonds between the carboxyl groups in the enzyme and the ether groups in PEG.     

聚乙二醇单甲醚羧基衍生物的制备

以相对分子质量(简称分子量,下同)为1 200、2 000、5 000的聚乙二醇单甲醚(mPEG)为原料,采用琼斯试剂氧化法室温下制备羧基化的聚乙二醇单甲醚。产物结构经1HNMR和IR进行了确证。以羧基转化率为指标,探讨了反应物料最佳摩尔比为:n(Cr2O3)∶n(聚乙二醇单甲醚羟基)=2∶1,3种分子量产物的羧基转化率分别为99.6%,99.4%,98.0%。采用固液萃取法进行后处理,以产物外观颜色为指标,结果表明,固液萃取法中,先蒸除丙酮再加入碳酸氢钠中和的处理顺序获得的产物的颜色为白色,产物纯度高。以产物产率为指标,以分子量为1 000,1 200,2 000,5 000的聚乙二醇单甲醚(mPEG)及分子量为800的聚乙二醇(PEG)为原料制备羧基化衍生物,结果表明,该法适合于分子量大于2 000的聚乙二醇及分子量大于1 000的聚乙二醇单甲醚的羧基衍生物的制备,5种分子量产物的产率分别为88.2%,93.5%,98.0%,98.2%,39.1%。     

Entrapment of enzyme-linked magnetic nanoparticles within poly(ethylene glycol) hydrogel microparticles prepared by photopatterning

In this study, hydrogel microparticles containing enzyme-linked magnetic nanoparticles (MNPs) were prepared. Peroxidase (POD), a model enzyme, was covalently immobilized on the surface of MNPs using 3-aminopropyltriethoxysilane (APTES), and the resultant POD-linked MNPs were entrapped within various shapes of hydrogel microparticles using photopatterning. Pre-immobilizing POD on the MNP surface made it possible to use hydrogels prepared from high molecular weight PEG without enzyme leaching, which enhanced the reaction rate of entrapped enzymes by reducing resistance to mass transport. Quantitative assays showed a linear correspondence between fluorescence intensity and H₂O₂ concentrations below 15 mM.     

Preparation of poly(ethylene glycol)-grafted silica nanoparticles using a facile esterification condensation method

Organic–inorganic hybrid nanoparticles have been prepared by the direct facile esterification condensation under extremely mild conditions as ambient temperature, moisture and atmospheric pressure, and the resulting composite particles are characterized by ESCA, FTIR, TEM, DLS, TGA, DSC, and XRD techniques. Results show that this facile graft method has high graft efficiency and the grafted poly(ethylene glycol) (PEG) accounts for about 55 wt% of the total silica composites. The resulting silica nanoparticles have core-shell structure with PEG on the outside and SiO₂ in the core. As a result, the dispersion behavior of nanoparticles and the thermal stability of the grafted PEG are improved by the formation of covalent ester bonds between PEG and the reactive silica nanoparticles. The PEG phase, however, is disturbed by the proximity of the oxide phase of SiO₂. Consequently, less crystal or faulty crystal of PEG is resulted when PEG is grafted onto the surfaces of silica nanoparticles.     

Self-assembly hydrothermal assisted synthesis of mesoporous anatase in the presence of ethylene glycol

Mesoporous nanocrystalline anatase was prepared hydrothermally employing P123 as structure-directing agent. Ethylene glycol was used as a key synthesis parameter to fine tune the morphology, crystal size and pore size of the resultant mesophases. The incorporation of EG in the synthesis gel resulted in the formation of 1–2 μm sphere-like shapes and led to an increase in the specific surface area from ∼95 to ∼170 m²/g, decrease in the average pore size from ∼11 to ∼4.8 nm, and decrease in the average crystallite size from ∼17 to ∼12 nm. These mesophases were used as photocatalysts for the UV degradation of methylene blue and methyl orange. The mesoporous anatase phases photodegraded MB ∼1.5–3× faster than commercially available P25 and showed limited photocatalytic behavior for methyl orange.     

Self-assembly and drug release control of dual-responsive copolymers based on oligo(ethylene glycol)methyl ether methacrylate and spiropyran

Iranian Polymer Journal - To compare the synthesis and drug release of random and block copolymers, random and block copolymerizations of oligo(ethylene glycol)methyl ether methacrylate (OEGMA) and...     

Self-assembly hydrothermal assisted synthesis of mesoporous anatase in the presence of ethylene glycol

Mesoporous nanocrystalline anatase was prepared hydrothermally employing P123 as structure-directing agent. Ethylene glycol was used as a key synthesis parameter to fine tune the morphology, crystal size and pore size of the resultant mesophases. The incorporation of EG in the synthesis gel resulted in the formation of 1–2 μm sphere-like shapes and led to an increase in the specific surface area from 95 to 170 m²/g, decrease in the average pore size from 11 to 4.8 nm, and decrease in the average crystallite size from 17 to 12 nm. These mesophases were used as photocatalysts for the UV degradation of methylene blue and methyl orange. The mesoporous anatase phases photodegraded MB 1.5–3× faster than commercially available P25 and showed limited photocatalytic behavior for methyl orange.     

Miscibility of polystyrene with poly(ethylene oxide) and poly(ethylene glycol)

The intrinsic viscosity of polystyrene–poly(ethylene oxide) (PS–PEO) and PS–poly(ethylene glycol) (PEG) blends have been measured in benzene as a function of blend composition for various molecular weights of PEO and PEG at 303.15 K. The compatibility of polymer pairs in solution were determined on the basis of the interaction parameter term, Δb, and the difference between the experimental and theoretical weight-average intrinsic viscosities of the two polymers, Δ[η]. The theoretical weight-average intrinsic viscosities were calculated by interpolation of the individual intrinsic viscosities of the blend components. The compatibility data based on [η] determined by a single specific viscosity measurement, as a quick method for the determination of the intrinsic viscosity, were compared with that obtained from [η] determined via the Huggins equation. The effect of molecular weights of the blend components and the polymer structure on the extent of compatibility was studied. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1471–1482, 1998     

不同PEG含量对PLA/PEG共混物结晶动力学的影响

采用溶液共混法制备了一系列不同配比的聚乳酸(PLA)/聚乙二醇(PEG)共混物。通过偏光显微镜(POM)、扫描电镜(SEM)和差式扫描量热仪(DSC)研究了不同PEG含量的PLA/PEG共混物在不同结晶温度下,聚乳酸的晶体形貌、球晶生长速率及热力学性能。研究发现,PEG能够显著提高聚乳酸球晶的生长速率。当PEG含量为60%时,PLA/PEG共混物中聚乳酸球晶的生长速率最快,达到23.6μm/min,比纯聚乳酸的最快球晶生长速率(0.5μm/min)高47倍。但是,当PEG含量高于60%时,聚乳酸球晶的生长速率有所降低。同时,PLA/PEG共混物中聚乳酸球晶速率随结晶温度变化的取向,均向低温移动。另外,PLA/PEG共混物中聚乳酸球晶呈现环状花纹。DSC测试结果表明,随着PEG含量的增加,PLA/PEG共混物的玻璃化转变温度明显降低。