Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ETHYLENE OXIDE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed2005

Poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)-g-poly(vinyl pyrrolidone): synthesis and characterization.

Pluronic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers are grafted with poly(vinyl pyrrolidone) by free radical polymerization of vinyl pyrrolidone with simultaneous chain transfer to the Pluronic in dioxane. This modified polymer has both thermal responsiveness and remarkable capacity to interact with a wide variety of hydrophilic and hydrophobic pharmaceutical agents which is very attractive for medical applications. The chemical structure of the graft copolymers was characterized by FTIR and 1H NMR spectroscopy. Polymerization conditions such as initiators, feed ratio, and reaction times are studied to obtain the ideal graft copolymer.

Journal Article↗
PubMed1996

Self-Assembly in a Mixture of Two Poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) Copolymers in Water

The self-assembly behavior in water of a mixture of two poly (ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymers, (EO)13(PO)30(EO)13 (L64) and (EO)37(PO)58(EO)37 (P105), was explored at 25°C. The phase boundaries were established using 2H-NMR and inspection under polarized light; the structure of the various lyotropic liquid crystalline (LLC) phases was determined with small-angle X-ray scattering, while viscosity and differential scanning calorimetry measurements were used to probe the isotropic water-rich solution region. Isotropic regions, similar to the neat polymers, are stable at high polymer content. The addition of water induces structure in the amphiphilic block copolymer system. An extended lamellar (D) LLC phase is formed at 20-25% water content; a hexagonal (E) and a cubic (I) LLC phases supersede D at higher water contents. In addition to the above, a narrow isotropic region (L') is observed on the L64-water binary axis, in equilibrium with the E and the D phases. The hexagonal and lamellar LLC phases extended all the way from the L64-rich to the P105-rich side of the ternary L64-P105-water phase diagram; the characteristic hexagonal and lamellar structural dimensions varied linearly with P105 content in the L64-P105 mixture at a constant water concentration. An isotropic (micellar) solution phase (L1) dominates the high-water content corner of the ternary phase diagram. Viscosity measurements in this region provided evidence for increased interactions between the micelles as the boundary to the LLC phases was approached.

Journal Article↗
PubMed2001

Understanding drug release from poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) gels.

Experimental and mathematical studies were performed to understand the release mechanism of small molecular weight compounds from poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) polymer gels (trademarked Pluronic by BASF Corp.) of various concentrations. Studies of the diffusion coefficient of solutes in the polymer gels were performed using a novel technique to predict movement of drugs within the gel as release occurs. Studies were also performed to determine the diffusion coefficient of water in the polymer gel, as it is this parameter that controls the dissolution rate of the polymer, and in turn, the drug release rate. A model was formulated and solved numerically to determine the controlling release mechanism. By parameter modification, this algorithm for determining the overall mass of drug released from a drug loaded gel can be used for a number of drugs and for a wide range of initial polymer concentrations. Drug release data were obtained with a novel experimental setup and were used to verify the accuracy of the overall solution of the model. The results of the model indicate that although the rate of polymer dissolution ultimately controls the drug release, about 5% of the release is due to diffusion at the gel/liquid interface, giving rise to a slightly non-linear release. It was also found that agitation speed greatly affects the dissolution rates of these polymer gels.

Drug Delivery Systems↗
PubMedDate not supplied

Small-angle X-ray scattering study of the interaction of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers with lipid bilayers.

The relationship between molecular architecture and the nature of interactions with lipid bilayers has been studied for a series of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers using small-angle X-ray scattering (SAXS) and thermal analysis (differential scanning calorimetry, DSC). The number of molecular repeat units in the hydrophobic poly(propylene oxide), PPO, block has been found to be a critical determinant of the nature of triblock copolymer-lipid bilayer association. For dimyristoyl-sn-glycero-3-phosphocholine (DMPC)-based biomembrane structures, polymers possessing a PPO chain length commensurate with the acyl chain dimensions of the lipid bilayer yield highly ordered, swollen lamellar structures consistent with well-integrated (into the lipid bilayer) PPO blocks. Triblock copolymers of lesser PPO chain length yield materials with structural characteristics similar to a simple dispersion of DMPC in water. Increasing the concentration (from 4 to 12 mol %) of well-integrated triblock copolymers enhances the structural ordering of the lamellar phase, while concentrations exceeding 16 mol % result in the formation of a hexagonal phase. Examination of temperature-induced changes in the structure of these mesophases (complex fluids) reveals that if the temperature is reduced sufficiently, all compositions exclude polymer and thus exhibit the characteristic SAXS pattern for hydrated DMPC bilayers. Increasing the temperature promotes better insertion of the polymers possessing PPO chain lengths sufficient for membrane insertion. No temperature-induced structural changes are observed in compositions prepared with PEO-PPO-PEO polymers that feature PPO length insufficient to permit full incorporation into the lipid bilayer.

Biocompatible Materials↗
PubMed2002

The effect of salts on the micellization temperature of aqueous poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) solutions and the dissolution rate and water diffusion coefficient in their corresponding gels.

Studies were performed to examine the effect of ionic salts on phase transitions, dissolution rates, and diffusion coefficients of water in gels of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) with polymer concentrations ranging from 22 to 32% w/w and salt concentrations ranging from 0 to 1.5% w/w. Salts tested include Na(3)PO(4), Na(2)SO(4), Na(2)HPO(4), NaH(2)PO(4), NaCH(3)CO(2), NaCl, and KI. Micellization transition temperatures were obtained using differential scanning calorimetry. The dissolution rates were obtained by measurement of the surface erosion rates, and diffusion coefficients were obtained by using a method to analyze the intrusion of water into the aqueous gels. It was found that salts had no effect on the dissolution rate of the polymer gels into deionized water. However, when the salt concentration in the aqueous dissolution media was adjusted to match the concentration in the gels, the dissolution rate of the polymer gel decreased with increasing salt concentration. The salts also had a profound effect on the critical micellization temperature (CMT) and the diffusion coefficient of water within the gel. The diffusion coefficient and CMT decreased in the presence of salts. The magnitude of these effects was comparable to their placement on the Hofmeister, or lyotropic series for salts. The effects of polymer and salt concentrations on the CMT were quantified, and a single correlation was proposed to predict the micellization temperatures for a wide range of salt and polymer concentrations.

Diffusion↗
PubMedDate not supplied

Formyl-ended heterobifunctional poly(ethylene oxide): synthesis of poly(ethylene oxide) with a formyl group at one end and a hydroxyl group at the other end.

Well-defined poly(ethylene oxide) (PEO) with a formyl group at one end and a hydroxyl group at the other terminus was synthesized by the anionic ring opening polymerization of ethylene oxide (EO) with a new organometallic initiator possessing an acetal moiety, potassium 3,3-diethoxypropyl alkoxide. Hydrolysis of the acetal moiety produced a formyl group-terminated heterobifunctional PEO with a hydroxyl group at the other end.

Chromatography, Gel↗
PubMed1995

Heparin-like anticoagulant activity of sulphonated poly(ethylene oxide) and sulphonated poly(ethylene oxide)-grafted polyurethane.

Sulphonated poly(ethylene oxide) (PEO-SO3) and PEO-SO3-grafted polyurethane (PU-PEO-SO3) were prepared by bulk modification and their anticoagulant and heparin-like activities were investigated. Anticoagulant activity measured by activated partial thromboplastin time of PU-PEO-SO3 displayed 2%, whereas that of PEO-SO3 itself reached 14% as compared to free heparin. In addition, the anticoagulant effects of these sulphonated polymers were not due to factor Xa inhibition but mainly thrombin inhibition. From the clotting time measurements using reptilase instead of thrombin and antithrombin III (AT III), PEO-SO3 and PU-PEO-SO3 indicated heparin-like activity which represents both prolonged thrombin time (TT) and normal reptilase time and increased TT in the presence of AT III. Thrombin was also neutralized by sulphonated polymers to a great extent. Therefore, the anticoagulant and heparin-like activities of PEO-SO3 and PU-PEO-SO3 seem to contribute to their improved blood compatibility.

Anticoagulants↗
PubMed1990

Men assigned to ethylene oxide production or other ethylene oxide related chemical manufacturing: a mortality study.

A retrospective cohort study was conducted to examine the mortality experience of 2174 men employed between 1940 and 1978 by a large chemical company and who had been assigned to a chemical production department that used or produced ethylene oxide (EO). Comparisons were made with the general United States population, the regional population, and with a group of 26,965 unexposed men from the same plants. Comparisons with general United States death rates showed fewer deaths than expected in the EO group due to all causes and for total cancers. There was no statistically significant excess of deaths due to any cause. Seven deaths each due to leukaemia and pancreatic cancer were observed with 3.0 and 4.1 deaths expected. Among the subcohort of men who worked where both average and peak exposure levels were probably highest, however, one death due to pancreatic cancer (0.9 expected) and no deaths due to leukaemia were observed. Four of the seven who died from leukaemia and six of the seven who died from pancreatic cancer had been assigned to the chlorohydrin department where the potential for exposure to EO is judged to have been low. The relative risk of death due to each disease was strongly related to duration of assignments to that department. When men who worked in the chlorohydrin department were excluded, there was no evidence for an association of exposure to EO with pancreatic cancer or leukaemia. Together with the failure to show independent EO associations, the chlorohydrin department results suggest that leukaemia and pancreatic cancer may have been associated primarily with production of ethylene chlorohydrin or propylene chlorohydrin, or both. These results emphasise the importance of examining additional concurrent/asynchronous exposures among human populations exposed to EO.

Adult↗
PubMed1992

Tensides from the group of propylene oxide and ethylene oxide copolymers. X. Solubilization of acetylsalicylic acid by polyetherodiol micelles.

The process of structural solubilization of acetylsalicylic acid in balanced systems (weight-balanced) by micelles of Rokopols of 30p160 and 30p60 types and, for comparison, by those of F-68 and F-108 Pluronics was investigated. The determined viscosity and hydrodynamic parameters allowed for the calculation of solubilizing activity of polyetherodiol micelles--n(s(A)). The results of the investigation point at Rokopols as an excipient, which may help to obtain new drug delivery systems.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1985

Sub-part-per-million diffusional sampling for ethylene oxide with the 3M #3550 ethylene oxide monitor.

A method is described for the collection and determination of ethylene oxide in air below the 1 ppm level. A passive diffusion-type monitor adsorbs the contaminant on a treated charcoal disc and converts it to 2-bromoethanol. This compound is then desorbed, injected into a gas chromatograph, and evaluated by electron capture detection. Laboratory testing was done by simultaneously challenging the monitors and Qazi-Ketcham charcoal tubes with 0.20 to 0.80 ppm ethylene oxide in air. At these levels, the bias of the monitors was +0.48% with overall accuracy of 13.8%; for the Qazi-Ketcham tubes it was -11.2% with an overall accuracy of 22.7%, well within the +/- 25% OSHA requirement. Field validation tests were performed using a specially-constructed chamber which simultaneously draws the work environment air over the monitors and through charcoal tubes to assure uniform sampling. The tube samples were analyzed in two laboratories. Results from the two collection devices agreed within 7.4% in the same laboratory, and results of the Qazi-Ketcham method between laboratories agreed within 21%. All results, lowest to highest, were within the OSHA +/- 25% limit.

Air Pollutants, Occupational↗
PubMed1970

Microbiological aspects of ethylene oxide sterilization. II. Microbial resistance to ethylene oxide.

The death rate kinetics of several sporeforming and nonsporeforming microorganisms, including radiation-resistant cocci, were determined by exposing them to a mixture of ethylene oxide and dichlorodifluoromethane (500 mg of ethylene oxide per liter, 30 to 50% relative humidity, and 54.4 C). Spore survivor curves obtained from tests of inoculated and exposed hygroscopic and nonhygroscopic carriers showed that the spores of Bacillus subtilis var. niger are more resistant to ethylene oxide than are spores of Clostridium sporogenes, B. stearothermophilus, and B. pumilus. The decimal reduction times (expressed as D values at 54.4 C-500 mg of ethylene oxide per liter) obtained under the test conditions for B. subtilis var. niger spores on hygroscopic and nonhygroscopic carriers exceeded the values obtained for the other organisms considered, both sporeformers and nonsporeformers. The decimal reduction times for the vegetative cells of the radiation-resistant organisms (Micrococcus radiodurans and two strains of Streptococcus faecalis) and the ATCC strain of S. faecalis demonstrated comparable resistance to ethylene oxide with the spores of C. sporogenes, B. stearothermophilus, and B. pumilus, but not those of B. subtilis var. niger.

Bacillus↗