The Experts below are selected from a list of 71658 Experts worldwide ranked by ideXlab platform
H A Tajmirriahi - One of the best experts on this subject based on the ideXlab platform.
-
effect of peg and MPEG anthracene on trna aggregation and particle formation
Biomacromolecules, 2012Co-Authors: E Froehlich, J S Mandeville, D Arnold, Laurent Kreplak, H A TajmirriahiAbstract:Poly(ethylene glycol) (PEG) and its derivatives are synthetic polymers with major applications in gene and drug delivery systems. Synthetic polymers are also used to transport miRNA and siRNA in vitro. We studied the interaction of tRNA with several PEGs of different compositions, such as PEG 3350, PEG 6000, and MPEG-anthracene under physiological conditions. FTIR, UV–visible, CD, and fluorescence spectroscopic methods as well as atomic force microscopy (AFM) were used to analyze the PEG binding mode, the binding constant, and the effects of polymer complexation on tRNA stability, aggregation, and particle formation. Structural analysis showed that PEG-tRNA interaction occurs via RNA bases and the backbone phosphate group with both hydrophilic and hydrophobic contacts. The overall binding constants of KPEG 3350-tRNA= 1.9 (±0.5) × 104 M–1, KPEG 6000-tRNA = 8.9 (±1) × 104 M–1, and KMPEG-anthracene= 1.2 (±0.40) × 103 M–1 show stronger polymer–RNA complexation by PEG 6000 and by PEG 3350 than the MPEG-anthrac...
-
complexes of dendrimers with bovine serum albumin
Biomacromolecules, 2010Co-Authors: J S Mandeville, H A TajmirriahiAbstract:We report the complexation of bovine serum albumin (BSA) with several dendrimers of different compositions MPEG-PAMAM (G3), MPEG-PAMAM (G4), and PAMAM (G4) at physiological conditions using constant protein concentration and various dendrimer contents. FTIR, CD, and fluorescence spectroscopic methods were used to analyze polymer binding mode, the binding constant, and the effects of dendrimer complexation on BSA stability and conformation. Structural analysis showed that dendrimers bind BSA via hydrophilic and hydrophobic interactions with a number of bound polymers (n): 1.30 for MPEG-PAMAM-G3, 1.30 for MPEG-PAMAM-G4, and 1.0 for PAMAM-G4. The polymer−BSA binding constants were KMPEG-G3 = 5.0 (±0.8) × 103 M−1, KMPEG-G4 = 1.0 (±0.3) × 104 M−1, and KPAMAM-G4 = 1.1 (±0.4) × 104 M−1. Dendrimer binding altered BSA conformation with a major reduction of α-helix and an increase in random coil and turn structures, indicating a partial protein unfolding.
E Froehlich - One of the best experts on this subject based on the ideXlab platform.
-
effect of peg and MPEG anthracene on trna aggregation and particle formation
Biomacromolecules, 2012Co-Authors: E Froehlich, J S Mandeville, D Arnold, Laurent Kreplak, H A TajmirriahiAbstract:Poly(ethylene glycol) (PEG) and its derivatives are synthetic polymers with major applications in gene and drug delivery systems. Synthetic polymers are also used to transport miRNA and siRNA in vitro. We studied the interaction of tRNA with several PEGs of different compositions, such as PEG 3350, PEG 6000, and MPEG-anthracene under physiological conditions. FTIR, UV–visible, CD, and fluorescence spectroscopic methods as well as atomic force microscopy (AFM) were used to analyze the PEG binding mode, the binding constant, and the effects of polymer complexation on tRNA stability, aggregation, and particle formation. Structural analysis showed that PEG-tRNA interaction occurs via RNA bases and the backbone phosphate group with both hydrophilic and hydrophobic contacts. The overall binding constants of KPEG 3350-tRNA= 1.9 (±0.5) × 104 M–1, KPEG 6000-tRNA = 8.9 (±1) × 104 M–1, and KMPEG-anthracene= 1.2 (±0.40) × 103 M–1 show stronger polymer–RNA complexation by PEG 6000 and by PEG 3350 than the MPEG-anthrac...
-
Aggregation and particle formation of tRNA by dendrimers.
Biomacromolecules, 2011Co-Authors: E Froehlich, J S Mandeville, Laurent Kreplak, Heidar-ali Tajmir-riahiAbstract:Major attention has been focused on dendrimer–DNA complexes because of their applications in gene delivery systems. Dendrimers are also used to transport miRNA and siRNA in vitro. We examine the interaction of tRNA with several dendrimers of different compositions, MPEG-PAMAM (G3), MPEG-PAMAM (G4), and PAMAM (G4) under physiological conditions using constant tRNA concentration and various dendrimer contents. FTIR, UV–visible, and CD spectroscopic methods as well as atomic force microscopy (AFM) were used to analyze the macromolecule binding mode, the binding constant, and the effects of dendrimer complexation on RNA stability, aggregation, particle formation, and conformation. Structural analysis showed that dendrimer–tRNA complexation occurred via RNA bases and the backbone phosphate group with both hydrophilic and hydrophobic contacts. The overall binding constants of KMPEG-G3 = 7.6 (±0.9) × 103 M–1, KMPEG-G4 = 1.5 (±0.40) × 104 M–1, and KPAMAM-G4 = 5.3 (±0.60) × 104 M–1 show stronger polymer–RNA comple...
J S Mandeville - One of the best experts on this subject based on the ideXlab platform.
-
effect of peg and MPEG anthracene on trna aggregation and particle formation
Biomacromolecules, 2012Co-Authors: E Froehlich, J S Mandeville, D Arnold, Laurent Kreplak, H A TajmirriahiAbstract:Poly(ethylene glycol) (PEG) and its derivatives are synthetic polymers with major applications in gene and drug delivery systems. Synthetic polymers are also used to transport miRNA and siRNA in vitro. We studied the interaction of tRNA with several PEGs of different compositions, such as PEG 3350, PEG 6000, and MPEG-anthracene under physiological conditions. FTIR, UV–visible, CD, and fluorescence spectroscopic methods as well as atomic force microscopy (AFM) were used to analyze the PEG binding mode, the binding constant, and the effects of polymer complexation on tRNA stability, aggregation, and particle formation. Structural analysis showed that PEG-tRNA interaction occurs via RNA bases and the backbone phosphate group with both hydrophilic and hydrophobic contacts. The overall binding constants of KPEG 3350-tRNA= 1.9 (±0.5) × 104 M–1, KPEG 6000-tRNA = 8.9 (±1) × 104 M–1, and KMPEG-anthracene= 1.2 (±0.40) × 103 M–1 show stronger polymer–RNA complexation by PEG 6000 and by PEG 3350 than the MPEG-anthrac...
-
Aggregation and particle formation of tRNA by dendrimers.
Biomacromolecules, 2011Co-Authors: E Froehlich, J S Mandeville, Laurent Kreplak, Heidar-ali Tajmir-riahiAbstract:Major attention has been focused on dendrimer–DNA complexes because of their applications in gene delivery systems. Dendrimers are also used to transport miRNA and siRNA in vitro. We examine the interaction of tRNA with several dendrimers of different compositions, MPEG-PAMAM (G3), MPEG-PAMAM (G4), and PAMAM (G4) under physiological conditions using constant tRNA concentration and various dendrimer contents. FTIR, UV–visible, and CD spectroscopic methods as well as atomic force microscopy (AFM) were used to analyze the macromolecule binding mode, the binding constant, and the effects of dendrimer complexation on RNA stability, aggregation, particle formation, and conformation. Structural analysis showed that dendrimer–tRNA complexation occurred via RNA bases and the backbone phosphate group with both hydrophilic and hydrophobic contacts. The overall binding constants of KMPEG-G3 = 7.6 (±0.9) × 103 M–1, KMPEG-G4 = 1.5 (±0.40) × 104 M–1, and KPAMAM-G4 = 5.3 (±0.60) × 104 M–1 show stronger polymer–RNA comple...
-
complexes of dendrimers with bovine serum albumin
Biomacromolecules, 2010Co-Authors: J S Mandeville, H A TajmirriahiAbstract:We report the complexation of bovine serum albumin (BSA) with several dendrimers of different compositions MPEG-PAMAM (G3), MPEG-PAMAM (G4), and PAMAM (G4) at physiological conditions using constant protein concentration and various dendrimer contents. FTIR, CD, and fluorescence spectroscopic methods were used to analyze polymer binding mode, the binding constant, and the effects of dendrimer complexation on BSA stability and conformation. Structural analysis showed that dendrimers bind BSA via hydrophilic and hydrophobic interactions with a number of bound polymers (n): 1.30 for MPEG-PAMAM-G3, 1.30 for MPEG-PAMAM-G4, and 1.0 for PAMAM-G4. The polymer−BSA binding constants were KMPEG-G3 = 5.0 (±0.8) × 103 M−1, KMPEG-G4 = 1.0 (±0.3) × 104 M−1, and KPAMAM-G4 = 1.1 (±0.4) × 104 M−1. Dendrimer binding altered BSA conformation with a major reduction of α-helix and an increase in random coil and turn structures, indicating a partial protein unfolding.
Johann Plank - One of the best experts on this subject based on the ideXlab platform.
-
dispersing performance of different kinds of polycarboxylate pce superplasticizers in cement blended with a calcined clay
Construction and Building Materials, 2020Co-Authors: Marlene Schmid, Johann PlankAbstract:Abstract This study investigates the dispersing effectiveness of purposely selected methacrylate ester (MPEG), isoprenol ether (IPEG) and methallyl ether (HPEG) based polycarboxylate (PCE) superplasticizers of different molecular structures in cements blended with 0–50 wt% of a calcined clay (CC) rich in meta illite–smectite. It was found that the water demand of the composite cements increases lineraly with the rate of clinker substitution, and that PCE dosages also increase proportionally with the amount of CC, namely approximately doubled at 50% clinker substitution. Among the PCEs, HPEG polymers proved most effective while MPEG and especially IPEG PCEs required higher dosages.
-
synthesis and performance of a modified polycarboxylate dispersant for concrete possessing enhanced cement compatibility
Journal of Applied Polymer Science, 2013Co-Authors: Ahmad Habbaba, Alex Lange, Johann PlankAbstract:It is well established that the performance of polycarboxylate (PCE) superplasticizers can be severely affected by the composition of individual cements. Here, a novel allylether/maleic anhydride (APEG)-based PCE was synthesized using allyl maleate monomer as a new, additional building block. When polymerized into the PCE main chain, this building block was found to form a cyclic lactone structure. The resulting PCE molecule was tested with respect to the dispersing force in cements possessing different phase compositions and alkali sulfate (K2SO4) contents. These data were compared with those from conventional APEG- and methacrylate ester (MPEG)-type PCEs. Results obtained from cement paste flowability and adsorption measurements suggest that the modified PCE disperses all cement samples well and hence is more robust against variations in cement composition. Apparently, the new building block induces a higher affinity of the polymer to the surface of cement and can form a denser polymer layer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
-
preferential adsorption of polycarboxylate superplasticizers on cement and silica fume in ultra high performance concrete uhpc
Cement and Concrete Research, 2012Co-Authors: Ch Schrofl, M Gruber, Johann PlankAbstract:UHPC is fluidized particularly well when a blend of MPEG- and APEG-type PCEs is applied. Here, the mechanism for this behavior was investigated. Testing individual cement and micro silica pastes revealed that the MPEG-PCE disperses cement better than silica whereas the APEG-PCE fluidizes silica particularly well. This behavior is explained by preferential adsorption of APEG-PCE on silica while MPEG-PCEs exhibit a more balanced affinity to both cement and silica. Adsorption data obtained from individual cement and micro silica pastes were compared with those found for the fully formulated UHPC containing a cement/silica blend. In the UHPC formulation, both PCEs still exhibit preferential and selective adsorption similar as was observed for individual cement and silica pastes. Preferential adsorption of PCEs is explained by their different stereochemistry whereby the carboxylate groups have to match with the steric position of calcium ions/atoms situated at the surfaces of cement hydrates or silica.
Laurent Kreplak - One of the best experts on this subject based on the ideXlab platform.
-
effect of peg and MPEG anthracene on trna aggregation and particle formation
Biomacromolecules, 2012Co-Authors: E Froehlich, J S Mandeville, D Arnold, Laurent Kreplak, H A TajmirriahiAbstract:Poly(ethylene glycol) (PEG) and its derivatives are synthetic polymers with major applications in gene and drug delivery systems. Synthetic polymers are also used to transport miRNA and siRNA in vitro. We studied the interaction of tRNA with several PEGs of different compositions, such as PEG 3350, PEG 6000, and MPEG-anthracene under physiological conditions. FTIR, UV–visible, CD, and fluorescence spectroscopic methods as well as atomic force microscopy (AFM) were used to analyze the PEG binding mode, the binding constant, and the effects of polymer complexation on tRNA stability, aggregation, and particle formation. Structural analysis showed that PEG-tRNA interaction occurs via RNA bases and the backbone phosphate group with both hydrophilic and hydrophobic contacts. The overall binding constants of KPEG 3350-tRNA= 1.9 (±0.5) × 104 M–1, KPEG 6000-tRNA = 8.9 (±1) × 104 M–1, and KMPEG-anthracene= 1.2 (±0.40) × 103 M–1 show stronger polymer–RNA complexation by PEG 6000 and by PEG 3350 than the MPEG-anthrac...
-
Aggregation and particle formation of tRNA by dendrimers.
Biomacromolecules, 2011Co-Authors: E Froehlich, J S Mandeville, Laurent Kreplak, Heidar-ali Tajmir-riahiAbstract:Major attention has been focused on dendrimer–DNA complexes because of their applications in gene delivery systems. Dendrimers are also used to transport miRNA and siRNA in vitro. We examine the interaction of tRNA with several dendrimers of different compositions, MPEG-PAMAM (G3), MPEG-PAMAM (G4), and PAMAM (G4) under physiological conditions using constant tRNA concentration and various dendrimer contents. FTIR, UV–visible, and CD spectroscopic methods as well as atomic force microscopy (AFM) were used to analyze the macromolecule binding mode, the binding constant, and the effects of dendrimer complexation on RNA stability, aggregation, particle formation, and conformation. Structural analysis showed that dendrimer–tRNA complexation occurred via RNA bases and the backbone phosphate group with both hydrophilic and hydrophobic contacts. The overall binding constants of KMPEG-G3 = 7.6 (±0.9) × 103 M–1, KMPEG-G4 = 1.5 (±0.40) × 104 M–1, and KPAMAM-G4 = 5.3 (±0.60) × 104 M–1 show stronger polymer–RNA comple...
