The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Xulin Jiang - One of the best experts on this subject based on the ideXlab platform.
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separation and characterization of benzaldehyde functional Polyethylene Glycols by liquid chromatography under critical conditions
Polymer Chemistry, 2016Co-Authors: Y Z Wei, Renxi Zhuo, Xulin Jiang, Y F Chu, Elena Uliyanchenko, Peter J SchoenmakersAbstract:The distributions of non-, mono- and bi-functional benzaldehyde-substituted Polyethylene Glycols (PEGs) need to be accurately determined for biomedical applications. The baseline separation of PEGs and their derivatives based on the number of functional end groups without an obvious effect of molar mass is achieved by high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC) using reversed-phase packing columns under critical isocratic elution conditions. The effects of organic solvent percentage, column temperature and buffer concentration on the retention times of PEGs and benzaldehyde-substituted PEGs have been investigated. The separation was mainly due to the hydrophobic interaction between the benzaldehyde end-groups and column packing. HPLC analysis can provide useful information to optimize the synthesis of functional PEGs. To our knowledge, this is the first report on separation of benzaldehyde-functional PEGs based on the functionality independent of the molar mass by isocratic elution.
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separation of Polyethylene Glycols and maleimide terminated Polyethylene Glycols by reversed phase liquid chromatography under critical conditions
Journal of Separation Science, 2016Co-Authors: Yanzhen Wei, Renxi Zhuo, Xulin JiangAbstract:The separation of Polyethylene Glycols and maleimide-substituted Polyethylene glycol derivatives based on the number of maleimide end-groups under critical liquid chromatography conditions has been investigated on a reversed-phase column. The critical solvent compositions for non-functional Polyethylene Glycols and bi-functional maleimide-substituted Polyethylene Glycols were determined to be identical at about 40% acetonitrile in water on a reversed-phase octadecyl carbon chain-bonded silica column using mixtures of acetonitrile and water of varying composition as the mobile phase at 25°C. The maleimide-functionalized Polyethylene Glycols were successfully separated according to maleimide functionality (with zero, one, two or three maleimide end-groups, respectively) under the critical isocratic elution conditions without obvious effect of molar mass. The separation was mainly due to the hydrophobic interaction between the maleimide end-groups and the column packing. Off-line matrix-assisted laser desorption/ionization time of flight mass spectrometry was used to identify the repeating units and, especially, the end-groups of the maleimide-substituted Polyethylene Glycols. Liquid chromatography analysis at critical conditions could provide useful information to optimize the synthesis of functional Polyethylene Glycols. To our knowledge, this is the first report of the baseline separation of maleimide-functionalized Polyethylene Glycols based on the functionality independent of the molar mass without derivatization by isocratic elution. This article is protected by copyright. All rights reserved
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separation of Polyethylene Glycols and amino terminated Polyethylene Glycols by high performance liquid chromatography under near critical conditions
Journal of Chromatography A, 2016Co-Authors: Y Z Wei, Renxi Zhuo, Xulin JiangAbstract:The separation and characterization of Polyethylene Glycols (PEGs) and amino-substituted derivatives on common silica-based reversed-phase packing columns using isocratic elution is described. This separation is achieved by liquid chromatography under the near critical conditions (LCCC), based on the number of amino functional end groups without obvious effect of molar mass for PEGs. The mobile phase is acetonitrile in water with an optimal ammonium acetate buffer. The separation mechanism of PEG and amino-substituted PEG under the near LCCC on silica-based packing columns is confirmed to be ion-exchange interaction. Under the LCCC of PEG backbone, with fine tune of buffer concentration, the retention factor ratios for benzylamine and phenol in buffered mobile phases, α(benzylamine/phenol)-values, were used to assess the ion-exchange capacity on silica-based reversed-phase packing columns. To the best of our knowledge, this is the first report on separation of amino-functional PEGs independent of the molar mass by isocratic elution using common C18 or phenyl reversed-phase packing columns.
M H Rubinstein - One of the best experts on this subject based on the ideXlab platform.
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physical stability of solid dispersions containing triamterene or temazepam in Polyethylene Glycols
Journal of Pharmacy and Pharmacology, 1997Co-Authors: Stephen K. Dordunoo, James L Ford, M H RubinsteinAbstract:: The effect of storage on the physical stability of solid dispersions of triamterene or temazepam in Polyethylene Glycols was studied using differential scanning calorimetry (DSC), particle-size analysis and dissolution methods. The enthalpies of fusion of the carriers, without included drug and previously fused and crystallized, increased on storage. Analysis of similarly treated solid dispersions, containing either 10% temazepam or 10% triamterene, showed that each drug influenced the morphology of the Polyethylene glycol (PEG). The enthalpies and melting points of the solidus components of the dispersions' carriers were initially reduced after preparation, but on storage these increased. The particle sizes of the drugs dispersed in the PEGs increased on storage. The changes in dissolution after storage of triamterene or temazepam dispersions were smaller for dispersions in PEG 1500 than for dispersions in PEGs of higher molecular weight (PEG 2000, PEG 4000 or PEG 6000) in which the reduction in dissolution was particularly marked during the first month of storage. The rank order of changes in dissolution were PEG 1500 < < PEG 2000 < PEG 4000 approximately PEG 6000.
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solidification studies of Polyethylene Glycols gelucire 44 14 or their dispersions with triamterene or temazepam
Journal of Pharmacy and Pharmacology, 1996Co-Authors: Stephen K. Dordunoo, James L Ford, M H RubinsteinAbstract:The solidification of Polyethylene Glycols (PEG 1500, PEG 2000, PEG 4000, PEG 6000), gelucire 44/14 or their dispersions containing triamterene or temazepam were studied to assess the feasibility of using these dispersions to liquid-fill hard gelatin capsules. Solidification from melts, investigated by differential scanning calorimetry using cooling cycles, showed a tendency of the drugs, carriers or their dispersions to supercool. The degree of supercooling depended on the rate of cooling, the drug content and, for the PEGs, on the molecular weight. PEG 1500 and PEG 2000 gave one morphological form, irrespective of cooling rate; PEG 4000 and PEG 6000 solidified into at least two forms, depending on the cooling rate. Incorporation of drugs affected the morphology of the PEGs during solidification. The rate of crystal growth was, furthermore, influenced by the fusion temperature, molecular weight and the degree of supercooling. The degree of crystallinity, as measured by the enthalpies of solidification, decreased with increasing cooling rate. The results show that reducing the rate of solidification could lead to incomplete solidification, giving products that are liable to change on storage.
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preformulation studies on solid dispersions containing triamterene or temazepam in Polyethylene Glycols or gelucire 44 14 for liquid filling of hard gelatin capsules
Drug Development and Industrial Pharmacy, 1991Co-Authors: Stephen K. Dordunoo, James L Ford, M H RubinsteinAbstract:AbstractSolid dispersions of triamterene or temazepam in Polyethylene Glycols or gelucire 44/14 have been investigated. The phase equilibria of the drugs and carriers were determined by Differential Thermal Analysis and Hot Stage Microscopy. Particle Size Analysis was carried out using double image microscopy, whilst phase solubility techniques and dissolution methods were used to study solubility, dissolution and ageing.It has been shown that triamterene forms monotectics with Polyethylene Glycols and gelucire 44/14 and temzepam shows partial solubility. The effect of the carriers on particle size depends on the solubility of the drug in the carrier and size reduction is observed where the drug is soluble in the carrier.
Stephen K. Dordunoo - One of the best experts on this subject based on the ideXlab platform.
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physical stability of solid dispersions containing triamterene or temazepam in Polyethylene Glycols
Journal of Pharmacy and Pharmacology, 1997Co-Authors: Stephen K. Dordunoo, James L Ford, M H RubinsteinAbstract:: The effect of storage on the physical stability of solid dispersions of triamterene or temazepam in Polyethylene Glycols was studied using differential scanning calorimetry (DSC), particle-size analysis and dissolution methods. The enthalpies of fusion of the carriers, without included drug and previously fused and crystallized, increased on storage. Analysis of similarly treated solid dispersions, containing either 10% temazepam or 10% triamterene, showed that each drug influenced the morphology of the Polyethylene glycol (PEG). The enthalpies and melting points of the solidus components of the dispersions' carriers were initially reduced after preparation, but on storage these increased. The particle sizes of the drugs dispersed in the PEGs increased on storage. The changes in dissolution after storage of triamterene or temazepam dispersions were smaller for dispersions in PEG 1500 than for dispersions in PEGs of higher molecular weight (PEG 2000, PEG 4000 or PEG 6000) in which the reduction in dissolution was particularly marked during the first month of storage. The rank order of changes in dissolution were PEG 1500 < < PEG 2000 < PEG 4000 approximately PEG 6000.
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solidification studies of Polyethylene Glycols gelucire 44 14 or their dispersions with triamterene or temazepam
Journal of Pharmacy and Pharmacology, 1996Co-Authors: Stephen K. Dordunoo, James L Ford, M H RubinsteinAbstract:The solidification of Polyethylene Glycols (PEG 1500, PEG 2000, PEG 4000, PEG 6000), gelucire 44/14 or their dispersions containing triamterene or temazepam were studied to assess the feasibility of using these dispersions to liquid-fill hard gelatin capsules. Solidification from melts, investigated by differential scanning calorimetry using cooling cycles, showed a tendency of the drugs, carriers or their dispersions to supercool. The degree of supercooling depended on the rate of cooling, the drug content and, for the PEGs, on the molecular weight. PEG 1500 and PEG 2000 gave one morphological form, irrespective of cooling rate; PEG 4000 and PEG 6000 solidified into at least two forms, depending on the cooling rate. Incorporation of drugs affected the morphology of the PEGs during solidification. The rate of crystal growth was, furthermore, influenced by the fusion temperature, molecular weight and the degree of supercooling. The degree of crystallinity, as measured by the enthalpies of solidification, decreased with increasing cooling rate. The results show that reducing the rate of solidification could lead to incomplete solidification, giving products that are liable to change on storage.
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preformulation studies on solid dispersions containing triamterene or temazepam in Polyethylene Glycols or gelucire 44 14 for liquid filling of hard gelatin capsules
Drug Development and Industrial Pharmacy, 1991Co-Authors: Stephen K. Dordunoo, James L Ford, M H RubinsteinAbstract:AbstractSolid dispersions of triamterene or temazepam in Polyethylene Glycols or gelucire 44/14 have been investigated. The phase equilibria of the drugs and carriers were determined by Differential Thermal Analysis and Hot Stage Microscopy. Particle Size Analysis was carried out using double image microscopy, whilst phase solubility techniques and dissolution methods were used to study solubility, dissolution and ageing.It has been shown that triamterene forms monotectics with Polyethylene Glycols and gelucire 44/14 and temzepam shows partial solubility. The effect of the carriers on particle size depends on the solubility of the drug in the carrier and size reduction is observed where the drug is soluble in the carrier.
Abolghasem Jouyban - One of the best experts on this subject based on the ideXlab platform.
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solubility of fluphenazine decanoate in aqueous mixtures of Polyethylene Glycols 400 and 600 at various temperatures
Fluid Phase Equilibria, 2014Co-Authors: Abolghasem Jouyban, Fleming Martinez, Vahid PanahiazarAbstract:Abstract The solubility of fluphenazine decanoate (FD) in aqueous binary mixtures of Polyethylene Glycols 400 (PEG 400) and 600 (PEG 600) at 298.0–318.0 K and atmospheric pressure along with some thermodynamic properties are reported. The previously trained version of the Jouyban–Acree model for PEG 400 + water, a recently proposed general cosolvency model employing partial solubility parameters, and a combination of the model with van’t Hoff equation were used to predict the solubility of FD in PEG 400 + water and PEG 600 + water at different temperatures. The results show that the Jouyban–Acree model can be used for solubility prediction of FD in aqueous mixtures of PEG 400 and PEG 600 at different temperatures. Densities of solute free aqueous mixtures of PEG 400 and PEG 600 along with their FD-saturated solutions are also reported.
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solubility of lamotrigine in binary and ternary mixtures of n methyl pyrrolidone and water with Polyethylene Glycols 200 400 and 600 at 298 2 k
Journal of Molecular Liquids, 2013Co-Authors: Shahla Soltanpour, Abolghasem JouybanAbstract:Abstract The solubility of lamotrigine in binary and ternary mixtures of N-methyl pyrrolidone and water with Polyethylene Glycols 200, 400, and 600 at 25 °C is determined and mathematically represented using two cosolvency models, i.e. the log-linear model of Yalkowsky (method I), the Jouyban–Acree model (method II), and a combined version of the Jouyban–Acree model with Hansen partial solubility parameters (method III). The density of the solute free solvent mixtures is measured and employed to train the Jouyban–Acree model and subsequently the density of the saturated solutions is predicted. For methods I and II, the overall mean relative deviations (OMRDs) for fitting the solubility data of lamotrigine in binary mixtures are 39.1% and 5.1%, respectively. Further, the OMRDs for fitting the solubilities in ternary solvent mixtures for lamotrigine are 42.9% and 22.1% for methods I and II, respectively. In method III, the OMRD value for fitting all 122 data points by means of the combined version of the Jouyban–Acree model with Hansen solubility parameters is 12.7%. The trained version of the Jouyban–Acree model was produced by using the density of the solute free solutions, and the prediction of OMRD for the density of saturated solutions is 1.6%.
Xiliang Luo - One of the best experts on this subject based on the ideXlab platform.
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gold nanoparticles and Polyethylene Glycols functionalized conducting polyaniline nanowires for ultrasensitive and low fouling immunosensing of alpha fetoprotein
Biosensors and Bioelectronics, 2016Co-Authors: Ni Hui, Xiaotian Sun, Zhiling Song, Shuyan Niu, Xiliang LuoAbstract:Abstract An ultrasensitive biosensor for alpha-fetoprotein was developed based on electrochemically synthesized polyaniline (PANI) nanowires, which were functionalized with gold nanoparticles (AuNPs) and Polyethylene Glycols (PEG). The prepared PEG/AuNPs/PANI composite, combining the electrical conductivity of the AuNPs/PANI with the robust antifouling ability of PEG, offered an ideal substrate for the development of low fouling electrochemical biosensors. Alpha-fetoprotein (AFP), a well-known hepatocellular carcinoma biomarker, was used as a model analyte, and its antibody was immobilized on the PEG/AuNPs/PANI for the construction of the AFP immunosensor. Using the redox current of PANI as the sensing signal, in addition to the good biocompatibility of PEG/AuNPs and the anti-biofouling property of PEG, the developed immunosensor showed improved biosensing performances, such as wide linear range and ultralow detection limit (0.007 pg mL−1). More importantly, it is label-free, reagentless and low fouling, making it capable of assaying AFP in real serum samples without suffering from significant interference or biofouling.
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low fouling label free dna sensor based on Polyethylene Glycols decorated with gold nanoparticles for the detection of breast cancer biomarkers
Biosensors and Bioelectronics, 2015Co-Authors: Wenting Wang, Xiaojian Fan, Jason J Davis, Xiliang LuoAbstract:A label-free and low fouling biosensor based on functional Polyethylene Glycols selective for breast cancer susceptibility gene (BRCA1) is reported. Sensory interfaces were prepared through the modification of a glassy carbon electrode with highly cross-linked Polyethylene glycol (PEG) film containing amine groups, followed by the self-assembly of gold nanoparticles and the immobilization of BRCA1 complementary single-strand 19-mer oligonucleotides. In the presence of a specific BRCA1 sequence capture and hybridization results in interfacial change sensitively monitored using electrochemical impedance spectroscopy. The combined utilization of a PEG polymer film and gold nanoparticle mixed interface enables very high levels of sensitivity and a highly effective assaying in patient samples. Assay linear range was from 50.0 fM to 1.0 nM, with a limit of detection of 1.72 fM. Furthermore, this label-free DNA sensor has been used for assaying BRCA1 in serum samples, showing its feasible potential for diagnostic applications in clinical analysis of breast cancer gene BRCA1. Foreseeable, this sensor made on this basis undoubtedly provide the most effective and sensitive detection for BRCA1.