The Experts below are selected from a list of 1221 Experts worldwide ranked by ideXlab platform
Thomas P Davis - One of the best experts on this subject based on the ideXlab platform.
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molecular weight hydrodynamic volume dictates the systemic pharmacokinetics and tumour disposition of polypeg star polymers
Nanomedicine: Nanotechnology Biology and Medicine, 2015Co-Authors: Song Yang Khor, Victoria M Mcleod, Jinming Hu, Lisa M Kaminskas, Michael R Whittaker, Christopher J H Porter, John F. Quinn, Mark Williamson, Thomas P DavisAbstract:Abstract Herein we report for the first time the biological fate of poly[(Oligoethylene Glycol) acrylate] (POEGA) star polymers synthesised via a versatile arm-first reversible addition-fragmentation chain transfer (RAFT) polymerisation approach. The biopharmaceutical behaviour of three different molecular weight (49, 64 and 94kDa) POEGA stars was evaluated in rats and nude mice bearing human MDA MB-231 tumours after intravenous administration. The 94kDa star polymer exhibited a longer plasma exposure time than the 49kDa or 64kDa star polymer; an observation attributable to differences in the rates of both polymer biodegradation and urinary excretion. Tumour biodistribution also correlated with molecular weight and was greatest for the longest circulating 94kDa star. Different patterns of liver and spleen biodistribution were observed between mice and rats for the different sized polymers. The polymers were also well-tolerated in vivo and in vitro at therapeutic concentrations. From the Clinical Editor Advances in nanotechnology has enabled scientists to produce nanoparticle as drug carriers in cancer therapeutics. In this article, the authors studied the biological fate of poly[(Oligoethylene Glycol) acrylate] (POEGA) star polymers of different size, after intravenous injections. This would allow the subsequent comparison to other drug delivery systems for better drug delivery.
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a block copolymer stabilized co precipitation approach to magnetic iron oxide nanoparticles for potential use as mri contrast agents
Polymer Chemistry, 2014Co-Authors: Johan Sebastian Basuki, Thomas P Davis, Cyrille Boyer, Lars Esser, Alexandre JacqueminAbstract:A library of magnetic nanoparticles was generated using in situ co-precipitation of ferrous (Fe2+) and ferric (Fe3+) ions from aqueous solutions in the presence of functional block copolymers. Three different iron oxide anchoring groups, viz., phosphonic acid, carboxylic acid or glycerol were incorporated into well-defined diblock copolymers of poly(Oligoethylene Glycol acrylate) employed to stabilize the iron oxide nanoparticles. The [copolymer] : [Fe] ratio was varied to wield control over nanoparticle diameters within the range of 7–20 nm. The relationship between colloidal stability and nanoparticle crystallinity was investigated using dynamic light scattering, transmission electron microscopy and X-ray diffraction measurements. The amount of polymer employed during the co-precipitation proved critical in governing crystallinity and colloidal stability. We report a correlation between the polymer grafting density and the chemical structure of the anchoring group. Finally, the transverse relaxivity of the iron oxide nanoparticles in water, was investigated using a 9.4T magnetic resonance imaging scanner yielding values varying from 70 to 370 mM−1 s−1.
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grafting of p oega onto magnetic nanoparticles using cu 0 mediated polymerization comparing grafting from and to approaches in the search for the optimal material design of nanoparticle mri contrast agents
Macromolecules, 2013Co-Authors: Johan Sebastian Basuki, Michael R Whittaker, Cyrille Boyer, Lars Esser, Per B Zetterlund, Thomas P DavisAbstract:Superparamagnetic iron oxide nanoparticles (IONPs) have been studied extensively as negative contrast agents to enhance MRI efficacy. For optimal effective clinical use in T2/T2* weighted MRI imaging, the aim is to maximize relaxivity (r2) of IONPs, and minimize r1 relaxivity. A prerequisite for successful clinical use of magnetic nanoparticles is colloidal stability in biologically relevant media; biocompatible polymers with antifouling properties such as poly(ethylene Glycol) (PEG) can be coated on the surface of IONPs, to improve stability and to impart longer blood circulation times. Our research aim was to optimize IONPs for use as contrast agents by achieving high grafting density and therefore colloidal stability, while retaining the magnetic properties of the IONP core. To attain the optimal material design the chemical functionalities and chain length of the polymeric layer must be precisely controlled. In this paper we describe the synthesis of poly(Oligoethylene Glycol acrylate) (P(OEGA)) funct...
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synthesis of functional core star polymers via raft polymerization for drug delivery applications
Macromolecular Rapid Communications, 2012Co-Authors: Jinna Liu, Michael R Whittaker, Thomas P Davis, Hien T T Duong, Cyrille BoyerAbstract:Poly(Oligoethylene Glycol) methyl ether acrylate was polymerized via reversible addition fragmentation transfer polymerization (RAFT), and then chain extended in the presence of both a cross-linker and vinyl benzaldehyde (VBA), yielding monodisperse star polymers. The presence of aldehyde groups in the core was exploited to attach doxorubicin. The drug loading was controlled by the amount of VBA incorporated (until 28 wt% in drug). The doxorubicin release was studied at pH = 5.5 and 7.4; conditions representative of endosomal and extra cellular environments. In vitro studies revealed that the doxorubicin-conjugated star polymers had a level of cytotoxicity comparable to that found for free doxorubicin. Confocal microscopy and flow cytometry studies confirmed efficient cell uptake of the star polymers.
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macromolecular ligands for gadolinium mri contrast agents
Macromolecules, 2012Co-Authors: Yang Li, Thomas P Davis, Hien T T Duong, Mariana Beija, Sophie Laurent, Luce Vander Elst, Robert N Muller, Andrew B Lowe, Cyrille BoyerAbstract:Macromolecular ligands for gadolinium contrast agents (CAs) were prepared via a “grafting to” strategy. Copolymers of Oligoethylene Glycol methyl ether acrylate (OEGA) and an activated ester monomer, pentafluorophenyl acrylate (PFPA), were synthesized and modified with the 1-(5-amino-3-aza-2-oxypentyl)-4,7,10-tris(tert-butoxycarbonylmethyl)-1,4,7,10-tetraazacyclododecane (DO3A-tBu-NH2) chelate for the complexation of Gd3+. The relaxivity properties of the ligated Gd3+ agents were then studied to evaluate the effect of macromolecular architecture on their behavior as magnetic resonance imaging (MRI) CAs. Ligands made from linear and hyperbranched macromolecules showed a substantially increased relaxivity in comparison to existing commercial Gd3+ MRI contrast agents. In contrast, star nanogel polymers exhibited a slightly lower relaxivity per Gd3+ ion (but still substantially higher relaxivity than existing low molecular weight commercial CAs). This work shows that macromolecular ligands have the potential ...
Cyrille Boyer - One of the best experts on this subject based on the ideXlab platform.
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nitric oxide loaded antimicrobial polymer for the synergistic eradication of bacterial biofilm
ACS Macro Letters, 2018Co-Authors: Rashin Namivandizangeneh, Zahra Sadrearhami, Edgar H. H. Wong, Ali Bagheri, Maeva Sauvagenguyen, Naresh Kumar, Cyrille BoyerAbstract:Bacterial biofilms are often difficult to treat and represent the main cause of chronic and recurrent infections. In this study, we report the synthesis of a novel antimicrobial/antibiofilm polymer that consists of biocompatible Oligoethylene Glycol, hydrophobic ethylhexyl, cationic primary amine, and nitric oxide (NO)-releasing functional groups. The NO-loaded polymer has dual-action capability as it can release NO which triggers the dispersion of biofilm, whereas the polymer can induce bacteria cell death via membrane wall disruption. By functionalizing the polymers with NO, we observed a synergistic effect in biofilm dispersal, planktonic and biofilm killing activities against Pseudomonas aeruginosa. The NO-loaded polymer results in 80% reduction in biofilm biomass and kills >99.999% of planktonic and biofilm P. aeruginosa cells within 1 h of treatment at a polymer concentration of 64 μg mL–1. To achieve this synergistic effect, it is imperative that the NO donors and antimicrobial polymer exist as a s...
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rational design of single chain polymeric nanoparticles that kill planktonic and biofilm bacteria
ACS Infectious Diseases, 2017Co-Authors: Thuykhanh Nguyen, Naresh Kumar, Cyrille Boyer, Shu Jie Lam, Greg G Qiao, Suhelen Egan, Edgar H. H. WongAbstract:Infections caused by multidrug-resistant bacteria are on the rise and, therefore, new antimicrobial agents are required to prevent the onset of a postantibiotic era. In this study, we develop new antimicrobial compounds in the form of single-chain polymeric nanoparticles (SCPNs) that exhibit excellent antimicrobial activity against Gram-negative bacteria (e.g., Pseudomonas aeruginosa) at micromolar concentrations (e.g., 1.4 μM) and remarkably kill ≥99.99% of both planktonic cells and biofilm within an hour. Linear random copolymers, which comprise Oligoethylene Glycol (OEG), hydrophobic, and amine groups, undergo self-folding in aqueous systems due to intramolecular hydrophobic interactions to yield these SCPNs. By systematically varying the hydrophobicity of the polymer, we can tune the extent of cell membrane wall disruption, which in turn governs the antimicrobial activity and rate of resistance acquisition in bacteria. We also show that the incorporation of OEG groups into the polymer design is essent...
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a block copolymer stabilized co precipitation approach to magnetic iron oxide nanoparticles for potential use as mri contrast agents
Polymer Chemistry, 2014Co-Authors: Johan Sebastian Basuki, Thomas P Davis, Cyrille Boyer, Lars Esser, Alexandre JacqueminAbstract:A library of magnetic nanoparticles was generated using in situ co-precipitation of ferrous (Fe2+) and ferric (Fe3+) ions from aqueous solutions in the presence of functional block copolymers. Three different iron oxide anchoring groups, viz., phosphonic acid, carboxylic acid or glycerol were incorporated into well-defined diblock copolymers of poly(Oligoethylene Glycol acrylate) employed to stabilize the iron oxide nanoparticles. The [copolymer] : [Fe] ratio was varied to wield control over nanoparticle diameters within the range of 7–20 nm. The relationship between colloidal stability and nanoparticle crystallinity was investigated using dynamic light scattering, transmission electron microscopy and X-ray diffraction measurements. The amount of polymer employed during the co-precipitation proved critical in governing crystallinity and colloidal stability. We report a correlation between the polymer grafting density and the chemical structure of the anchoring group. Finally, the transverse relaxivity of the iron oxide nanoparticles in water, was investigated using a 9.4T magnetic resonance imaging scanner yielding values varying from 70 to 370 mM−1 s−1.
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grafting of p oega onto magnetic nanoparticles using cu 0 mediated polymerization comparing grafting from and to approaches in the search for the optimal material design of nanoparticle mri contrast agents
Macromolecules, 2013Co-Authors: Johan Sebastian Basuki, Michael R Whittaker, Cyrille Boyer, Lars Esser, Per B Zetterlund, Thomas P DavisAbstract:Superparamagnetic iron oxide nanoparticles (IONPs) have been studied extensively as negative contrast agents to enhance MRI efficacy. For optimal effective clinical use in T2/T2* weighted MRI imaging, the aim is to maximize relaxivity (r2) of IONPs, and minimize r1 relaxivity. A prerequisite for successful clinical use of magnetic nanoparticles is colloidal stability in biologically relevant media; biocompatible polymers with antifouling properties such as poly(ethylene Glycol) (PEG) can be coated on the surface of IONPs, to improve stability and to impart longer blood circulation times. Our research aim was to optimize IONPs for use as contrast agents by achieving high grafting density and therefore colloidal stability, while retaining the magnetic properties of the IONP core. To attain the optimal material design the chemical functionalities and chain length of the polymeric layer must be precisely controlled. In this paper we describe the synthesis of poly(Oligoethylene Glycol acrylate) (P(OEGA)) funct...
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synthesis of functional core star polymers via raft polymerization for drug delivery applications
Macromolecular Rapid Communications, 2012Co-Authors: Jinna Liu, Michael R Whittaker, Thomas P Davis, Hien T T Duong, Cyrille BoyerAbstract:Poly(Oligoethylene Glycol) methyl ether acrylate was polymerized via reversible addition fragmentation transfer polymerization (RAFT), and then chain extended in the presence of both a cross-linker and vinyl benzaldehyde (VBA), yielding monodisperse star polymers. The presence of aldehyde groups in the core was exploited to attach doxorubicin. The drug loading was controlled by the amount of VBA incorporated (until 28 wt% in drug). The doxorubicin release was studied at pH = 5.5 and 7.4; conditions representative of endosomal and extra cellular environments. In vitro studies revealed that the doxorubicin-conjugated star polymers had a level of cytotoxicity comparable to that found for free doxorubicin. Confocal microscopy and flow cytometry studies confirmed efficient cell uptake of the star polymers.
Afang Zhang - One of the best experts on this subject based on the ideXlab platform.
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Multiple-Responsive Dendronized Hyperbranched Polymers
2019Co-Authors: Xiacong Zhang, Ting Liu, Jiatao Yan, Kun Liu, Afang ZhangAbstract:By combining topological structures of hyperbranched polymers with dendronized polymers, a series of hyperbranched poly(acylhydrazone)s pendanted with 3-fold branched dendritic Oligoethylene Glycol (OEG) units were efficiently prepared through A2 + B3 polycondensation. The constituents of these dendritic polymers can be mediated through dynamic covalent acylhydrazones. Owing to the dense OEG pendants, these dendronized hyperbranched polymers are biocompatible and thermoresponsive, and their cloud points (Tcps) can be modulated by the branched architecture, solution pH, and addition of a third component. Cell viability in the presence of these hyperbranched poly(acylhydrazone)s can be maintained above 80%. Based on the unique dendritic architecture with rich acylhydrazine groups, dynamic hydrogels cross-linked via acylhydrazone linkages with good mechanical property were prepared, which inherit the characteristic thermoresponsive behavior of the polymer precursors and also show remarkable self-healing properties. This novel kind of topological polymers and their corresponding hydrogels with dynamic and multiple smart properties may have promising applications as biomaterials
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thermoresponsive dendronized polypeptides showing switchable recognition to catechols
Macromolecules, 2016Co-Authors: Wen Li, Afang ZhangAbstract:A new class of thermoresponsive dendronized polypeptides was prepared through highly efficient oxime ligation between oxyamino-substituted polylysines and aldehyde-cored Oligoethylene Glycol (OEG) dendrons. Their secondary structures and thermoresponsive behavior were investigated. Because of the dendritic structures and stable oxime linkage, these OEG-based dendronized polypeptides exhibited fast and fully reversible phase transitions in neutrally aqueous solutions, and their phase transition temperatures can be controlled around physiological temperatures. The effect of OEG dendronization on secondary structures of polypeptides were examined to check their prominent dendritic shielding effect, steric hindrance, and thermally driven phase transitions. To further extend the functions and potential applications of these stimuli-responsive dendronized polypeptides, phenylboronic acid moieties were introduced to achieve the corresponding dendronized copolymers, which were utilized to specifically recognize c...
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low toxic thermoresponsive dendrimers based on Oligoethylene Glycols with sharp and fully reversible phase transitions
Chemical Communications, 2008Co-Authors: Afang Zhang, Yong Chen, Kirill Feldman, Dieter A SchluterAbstract:Novel first (G1) and second (G2) generation dendrimers based on three-fold branched Oligoethylene Glycol dendrons are efficiently synthesized which show characteristic thermoresponsive behavior and negligible cytotoxicity (for G2).
Hoogenboom Richard - One of the best experts on this subject based on the ideXlab platform.
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Effect of host-guest complexation on the thermoresponsive behavior of poly(oligo ethylene Glycol acrylate)s functionalized with dialkoxynapththalene guest side chains
'Wiley', 2021Co-Authors: Ryskulova Kanykei, Hou Zhanyao, Woisel Patrice, Hoogenboom RichardAbstract:The combination of thermoresponsive polymers with supramolecular host-guest interactions enables accurate tuning of the phase transition temperature, while also providing additional response mechanisms based on host-guest complexation. Most studies focused on a single thermoresponsive polymer to demonstrate the effect of host-guest complexation on the responsive behavior. In this work, the effect of the polymer structure on the host-guest complexation and thermoresponsive behavior is reported. Therefore, different poly(Oligoethylene Glycol acrylate)s, namely, poly(2-hydroxyethylacrylate) (PHEA), poly(methoxy diethylene Glycol acrylate), poly(methoxy triethylene Glycol acrylate), and poly(methoxy tetraethylene Glycol acrylate), are synthesized functionalized with 1,5-dialkoxynaphthalene guest molecules in the side chain. Their complexation with the cyclobis(paraquat-p-phenylene) tetrachloride host is studied to understand the effect of polymer structure on the supramolecular association and the polymer phase transition, revealing that the Oligoethylene Glycol side chains lead to weaker host-guest complexation and also have a smaller increase in the cloud point temperature compared to PHEA
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Effect of Host–Guest Complexation on the Thermoresponsive Behavior of Poly(oligo ethylene Glycol acrylate)s Functionalized with Dialkoxynapththalene Guest Side Chains
'Wiley', 2021Co-Authors: Ryskulova Kanykei, Hou Zhanyao, Woisel Patrice, Hoogenboom RichardAbstract:International audienceThe combination of thermoresponsive polymers with supramolecular host–guest interactions enables accurate tuning of the phase transition temperature, while also providing additional response mechanisms based on host–guest complexation. Most studies focused on a single thermoresponsive polymer to demonstrate the effect of host–guest complexation on the responsive behavior. In this work, the effect of the polymer structure on the host–guest complexation and thermoresponsive behavior is reported. Therefore, different poly(Oligoethylene Glycol acrylate)s, namely, poly(2‐hydroxyethylacrylate) (PHEA), poly(methoxy diethylene Glycol acrylate), poly(methoxy triethylene Glycol acrylate), and poly(methoxy tetraethylene Glycol acrylate), are synthesized functionalized with 1,5‐dialkoxynaphthalene guest molecules in the side chain. Their complexation with the cyclobis(paraquat‐p‐phenylene) tetrachloride host is studied to understand the effect of polymer structure on the supramolecular association and the polymer phase transition, revealing that the Oligoethylene Glycol side chains lead to weaker host–guest complexation and also have a smaller increase in the cloud point temperature compared to PHEA
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Complexation of thermoresponsive dialkoxynaphthalene end-functionalized poly(Oligoethylene Glycol acrylate)s with CBPQT4+in water
'Royal Society of Chemistry (RSC)', 2016Co-Authors: Yeniad Bahar, Ryskulova Kanykei, Woisel Patrice, Fournier David, Lyskawa Joël, Cooke Graeme, Hoogenboom RichardAbstract:Four different Oligoethylene Glycol acrylates (OEGA), namely hydroxypropylacrylate (HPA), methoxy diethylene Glycol acrylate (mDEGA), methoxy triethylene Glycol acrylate (mTEGA) and 2-hydroxyethylacrylate (HEA) were homopolymerized via RAFT polymerization employing a naphthalene functionalized chain transfer agent resulting in thermoresponsive naphthalene-functionalized POEGAs with different hydrophilicities. Supramolecular inclusion complexes of these POEGAs with electron-deficient cyclophane cyclobis(paraquat-p-phenylene) tetrachloride (CBPQT4+) in water were studied. The association constants (Ka) were determined to study the effect that polymer hydrophilicity has on the Ka and results indicated that the nature of the polymer did not significantly influence the complexation strength and the association is mostly enthalpy driven. The impact of temperature on the host–guest complexes was also investigated. A continuous partial thermally induced dissociation of complexes was observed upon raising the temperature with a more distinct decrease in complexation around the cloud point temperature (TCP) of the POEGA employed, indicating the importance of the polymer phase transition for tuning the recognition properties of dialkoxynaphthalene end-decorated poly(Oligoethylene Glycol acrylate)s in water
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Complexation of thermoresponsive dialkoxynaphthalene end-functionalized poly(Oligoethylene Glycol acrylate)s with CBPQT(4+) in water
'Royal Society of Chemistry (RSC)', 2016Co-Authors: Yeniad Bahar, Ryskulova Kanykei, Woisel Patrice, Fournier David, Lyskawa Joël, Cooke Graeme, Hoogenboom RichardAbstract:Four different Oligoethylene Glycol acrylates (OEGA), namely hydroxypropylacrylate (HPA), methoxy diethylene Glycol acrylate (mDEGA), methoxy triethylene Glycol acrylate (mTEGA) and 2-hydroxyethyl-acrylate (HEA) were homopolymerized via RAFT polymerization employing a naphthalene functionalized chain transfer agent resulting in thermoresponsive naphthalene-functionalized POEGAs with different hydrophilicities. Supramolecular inclusion complexes of these POEGAs with electron-deficient cyclophane cyclobis(paraquat-p-phenylene) tetrachloride (CBPQT(4+)) in water were studied. The association constants (K-a) were determined to study the effect that polymer hydrophilicity has on the K-a and results indicated that the nature of the polymer did not significantly influence the complexation strength and the association is mostly enthalpy driven. The impact of temperature on the host-guest complexes was also investigated. A continuous partial thermally induced dissociation of complexes was observed upon raising the temperature with a more distinct decrease in complexation around the cloud point temperature (T-CP) of the POEGA employed, indicating the importance of the polymer phase transition for tuning the recognition properties of dialkoxynaphthalene end-decorated poly(Oligoethylene Glycol acrylate)s in water
Timothy J Deming - One of the best experts on this subject based on the ideXlab platform.
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role of side chain molecular features in tuning lower critical solution temperatures lcsts of Oligoethylene Glycol modified polypeptides
Journal of Physical Chemistry B, 2016Co-Authors: Eric G Gharakhanian, Timothy J DemingAbstract:A series of thermoresponsive polypeptides has been synthesized using a methodology that allowed facile adjustment of side-chain functional groups. The lower critical solution temperature (LCST) properties of these polymers in water were then evaluated relative to systematic molecular modifications in their side-chains. It was found that in addition to the number of ethylene Glycol repeats in the side-chains, terminal and linker groups also have substantial and predictable effects on cloud point temperatures (Tcp). In particular, we found that the structure of these polypeptides allowed for inclusion of polar hydroxyl groups, which significantly increased their hydrophilicity and decreased the need to use long Oligoethylene Glycol repeats to obtain LCSTs. The thioether linkages in these polypeptides were found to provide an additional structural feature for reversible switching of both polypeptide conformation and thermoresponsive properties.
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Role of Side-Chain Molecular Features in Tuning Lower Critical Solution Temperatures (LCSTs) of Oligoethylene Glycol Modified Polypeptides
2016Co-Authors: Eric G Gharakhanian, Timothy J DemingAbstract:A series of thermoresponsive polypeptides has been synthesized using a methodology that allowed facile adjustment of side-chain functional groups. The lower critical solution temperature (LCST) properties of these polymers in water were then evaluated relative to systematic molecular modifications in their side-chains. It was found that in addition to the number of ethylene Glycol repeats in the side-chains, terminal and linker groups also have substantial and predictable effects on cloud point temperatures (Tcp). In particular, we found that the structure of these polypeptides allowed for inclusion of polar hydroxyl groups, which significantly increased their hydrophilicity and decreased the need to use long Oligoethylene Glycol repeats to obtain LCSTs. The thioether linkages in these polypeptides were found to provide an additional structural feature for reversible switching of both polypeptide conformation and thermoresponsive properties
