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Rainer Haag - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of Herpes Simplex Virus Type 1 Attachment and Infection by Sulfated Polyglycerols with Different Architectures.
Biomacromolecules, 2021Co-Authors: Paria Pouyan, Stefanie Wedepohl, Chuanxiong Nie, Sumati Bhatia, Katharina Achazi, Nikolaus Osterrieder, Rainer HaagAbstract:Inhibition of herpes simplex virus type 1 (HSV-1) binding to the host cell surface by highly sulfated architectures is among the promising strategies to prevent virus entry and infection. However, the structural flexibility of multivalent inhibitors plays a major role in effective blockage and inhibition of virus receptors. In this study, we demonstrate the inhibitory effect of a polymer scaffold on the HSV-1 infection by using highly sulfated Polyglycerols with different architectures (linear, dendronized, and hyperbranched). IC50 values for all synthesized sulfated Polyglycerols and the natural sulfated polymer heparin were determined using plaque reduction infection assays. Interestingly, an increase in the IC50 value from 0.03 to 374 nM from highly flexible linear Polyglycerol sulfate (LPGS) to less flexible scaffolds, namely, dendronized Polyglycerol sulfate and hyperbranched Polyglycerol sulfate was observed. The most potent LPGS inhibits HSV-1 infection 295 times more efficiently than heparin, and we show that LPGS has a much reduced anticoagulant capacity when compared to heparin as evidenced by measuring the activated partial thromboplastin time. Furthermore, prevention of infection by LPGS and the commercially available drug acyclovir were compared. All tested sulfated polymers do not show any cytotoxicity at concentrations of up to 1 mg/mL in different cell lines. We conclude from our results that more flexible Polyglycerol sulfates are superior to less flexible sulfated polymers with respect to inhibition of HSV-1 infection and may constitute an alternative to the current antiviral treatments of this ubiquitous pathogen.
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Droplet‐Based Microfluidic Templating of Polyglycerol‐Based Microgels for the Encapsulation of Cells: A Comparative Study
Macromolecular bioscience, 2018Co-Authors: Era Kapourani, Katharina Achazi, Jens Dernedde, Falko Neumann, Rainer HaagAbstract:Cell microencapsulation holds great promise as a therapeutic strategy for the controlled and sustained delivery of biologically relevant agents. The authors developed cell-laden microgel scaffolds with excellent long-term viabilities by combining bioorthogonal strain promoted azide-alkyne cycloaddition (SPAAC) and droplet-based microfluidic templating. Star-shaped Polyglycerol hexaazide, α,ω-bis azido-linear Polyglycerol or polyethylene glycol as well as dendritic Polyglycerol-(polycyclooctyne) served as bioinert hydrogel precursors. The authors demonstrate for the first time the generation of entirely Polyglycerol-based microcapsules with excellent stability and full retention of viability of the packed cells for longer than 3 weeks. As a result, our microgel particles could be used for long-term immunoisolation of cells enabling their study during encapsulation.
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Green Synthesis of Hyperbranched Polyglycerol at Room Temperature
ACS Macro Letters, 2016Co-Authors: Ehsan Mohammadifar, Mohsen Adeli, Ali Bodaghi, Abbas Dadkhahtehrani, Ali Nemati Kharat, Rainer HaagAbstract:In this work we report on a new method for the cationic polymerization of glycidol by citric acid at ambient and solvent free conditions. In this polymerization, citric acid is a proton donor and is able to incorporate in the structure of Polyglycerol by reaction with the activated monomer. The molecular weight and degree of branching of the synthesized polymers are affected by the glycidol/citric acid molar ratios and reaction temperature. Due to the citric acid core of the hyperbranched Polyglycerols, they are able to break down into the smaller segments at neutral or acidic conditions. Apart from citric acid, glycidol, and water, other reagents or organic solvents have not been used in the synthetic and purification processes. Taking advantage of the green synthesis and ability to cleave under physiological conditions, in addition to the intrinsic biocompatibility of Polyglycerol, the synthesized polymers are promising candidates for future biomedical applications.
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perfluoroalkyl functionalized hyperbranched Polyglycerol as pore forming agents and supramolecular hosts in polymer microspheres
International Journal of Molecular Sciences, 2015Co-Authors: Olaf Wagner, David A. Weitz, Maximilian Zieringer, Wynter J Duncanson, Rainer HaagAbstract:Perfluoroalkyl-functionalized, hyperbranched Polyglycerols that produce stable microbubbles are integrated into a microfluidic emulsion to create porous microspheres. In a previously-presented work a dendrimer with a perfluorinated shell was used. By replacing this dendrimer core with a hyperbranched core and evaluating different core sizes and degrees of fluorinated shell functionalization, we optimized the process to a more convenient synthesis and higher porosities. The new hyperbranched Polyglycerol porogens produced more pores and can be used to prepare microspheres with porosity up to 12% (v/v). The presented preparation forms pores with a perfluoroalkyl-functionalized surface that enables the resulting microspheres to act as supramolecular host systems. The microspheres can incorporate gases into the pores and actives in the polymer matrix, while the perfluoroalkylated pore surface can be used to immobilize perfluoro-tagged molecules onto the pores by fluorous-fluorous interaction.
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Polyglycerol coated polypropylene surfaces for protein and bacteria resistance
Polymer Chemistry, 2015Co-Authors: Maike C. Lukowiak, Sascha Wettmarshausen, Gundula Hidde, Petra Landsberger, Viola Boenke, Karsten Rodenacker, Ulrike Braun, Jörg Friedrich, Anna A. Gorbushina, Rainer HaagAbstract:Polyglycerol (PG) coated polypropylene (PP) films were synthesized in a two-step approach that involved plasma bromination and subsequently grafting hyperbranched Polyglycerols with very few amino functionalities. The influence of different molecular weights and density of reactive linkers were investigated for the grafted PGs. Longer bromination times and higher amounts of linkers on the surface afforded long-term stability. The protein adsorption and bacteria attachment of the PP-PG films were studied. Their extremely low amine content proved to be beneficial for preventing bacteria attachment.
Davod Mohebbi-kalhori - One of the best experts on this subject based on the ideXlab platform.
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Polyglycerol sebacate/chitosan/gelatin nano-composite scaffolds for engineering neural construct
Materials Chemistry and Physics, 2019Co-Authors: Sanaz Saravani, Mehdi Ebrahimian-hosseinabadi, Davod Mohebbi-kalhoriAbstract:Abstract The aim of this study was designing and fabricating nano-composite scaffolds based on Polyglycerol sebacate in order to use in nerve tissue engineering. Semi-crystalline Polyglycerol sebacate polymer was synthesized and evaluated by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) methods. The synthesized Polyglycerol sebacate was electrospun with chitosan and gelatin at different concentrations under various conditions. The obtained samples were examined using Scanning electron microscopy (SEM) observations; the diameters of fibers were measured via image processing method, and the percentage of scaffolds porosity were obtained as well. Results demonstrated that semi-crystalline Polyglycerol sebacate/chitosan/gelatin could be electrospun to produce fibers with the diameter of about 80 nm in average. MTT assay were performed using PC12 cell line; after 3 days of cell culture, it seems that Polyglycerol sebacate/Chitosan/Gelatin nano-composite has potentiality for nerve tissue engineering applications.
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Polyglycerol sebacate/chitosan/gelatin nano-composite scaffolds for engineering neural construct
Materials Chemistry and Physics, 2019Co-Authors: Sanaz Saravani, Mehdi Ebrahimian-hosseinabadi, Davod Mohebbi-kalhoriAbstract:Abstract The aim of this study was designing and fabricating nano-composite scaffolds based on Polyglycerol sebacate in order to use in nerve tissue engineering. Semi-crystalline Polyglycerol sebacate polymer was synthesized and evaluated by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) methods. The synthesized Polyglycerol sebacate was electrospun with chitosan and gelatin at different concentrations under various conditions. The obtained samples were examined using Scanning electron microscopy (SEM) observations; the diameters of fibers were measured via image processing method, and the percentage of scaffolds porosity were obtained as well. Results demonstrated that semi-crystalline Polyglycerol sebacate/chitosan/gelatin could be electrospun to produce fibers with the diameter of about 80 nm in average. MTT assay were performed using PC12 cell line; after 3 days of cell culture, it seems that Polyglycerol sebacate/Chitosan/Gelatin nano-composite has potentiality for nerve tissue engineering applications.
Holger Frey - One of the best experts on this subject based on the ideXlab platform.
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Beyond Poly(ethylene glycol): Linear Polyglycerol as a Multifunctional Polyether for Biomedical and Pharmaceutical Applications
Biomacromolecules, 2014Co-Authors: Anja Thomas, Sophie S. Müller, Holger FreyAbstract:Polyglycerols (sometimes also called “polyglycidols”) represent a class of highly biocompatible and multihydroxy-functional polymers that may be considered as a multifunctional analogue of poly(ethylene glycol) (PEG). Various architectures based on a Polyglycerol scaffold are feasible depending on the monomer employed. While polymerization of glycidol leads to hyperbranched Polyglycerols, the precisely defined linear analogue is obtained by using suitably protected glycidol as a monomer, followed by removal of the protective group in a postpolymerization step. This review summarizes the properties and synthetic approaches toward linear Polyglycerols (linPG), which are at present mainly based on the application of ethoxyethyl glycidyl ether (EEGE) as an acetal-protected glycidol derivative. Particular emphasis is placed on the manifold functionalization strategies including, e.g., the synthesis of end-functional linPGs or multiheterofunctional modifications at the polyether backbone. Potential applications...
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entanglement transition in hyperbranched polyether polyols
Macromolecular Rapid Communications, 2010Co-Authors: Christoph Tonhauser, Holger Frey, Daniel Wilms, Yasmin Korth, Christian FriedrichAbstract:Are hyperbranched polymers capable of forming entanglements? This is the central issue of this contribution. Hyperbranched Polyglycerol (hbPG) samples with different molecular weights (600-106 000 g · mol(-1) ), narrow polydispersities (1.2-1.8) and high degrees of branching (≈0.6) were prepared by anionic ring-opening polymerization. The viscoelastic properties of these polymers with respect to molecular architecture and molar mass were investigated. At low molecular weights "classical" scaling behavior between zero shear viscosity and molecular weight can be observed, whereas between 3 000 and 10 000 g · mol(-1) a plateau-like area is found. The results indicate entanglement dynamics when exceeding a critical molar mass ($\overline {M} _{{\rm c}}^{*} $ ≈ 20 000 g · mol(-1) ) due to entangled hyperbranched Polyglycerols.
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hyperbranched Polyglycerols with elevated molecular weights a facile two step synthesis protocol based on Polyglycerol macroinitiators
Macromolecules, 2009Co-Authors: Daniel Wilms, Frederik R Wurm, Jorg Nieberle, Paul Bohm, Ulrike Kemmerjonas, Holger FreyAbstract:Hyperbranched Polyglycerol (PG) is established as one of the few hyperbranched polymers that offer the possibility to control molecular weight up to Mn = 6000 g/mol. This work introduces a facile 2-step strategy that relies on the use of a low molecular weight PG (Mn = 500 and 1000 g/mol) as a macroinitiator for the slow addition of glycidol, permitting to overcome previous limitations concerning molecular weights and molecular weight control. A systematic investigation of the effect of the degree of deprotonation on the control of the polymerization reaction has been carried out. A series of hyperbranched PGs with molecular weights up to Mn = 24000 g/mol has been obtained under fully controlled conditions. The polydispersities of the samples prepared were in the range of 1.3 to 1.8. In summary, we present the first example of a synthetic strategy for a hyperbranched polymer that is now accessible over a broad range of molecular weights (300−24000 g/mol) without the ubiquitous problem of large polydispers...
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incorporation of a photosensitizer core within hyperbranched polyether polyols effect of the branched shell on the core properties
Macromolecules, 2008Co-Authors: Lourdes Pastorperez, Holger Frey, Emilie Barriau, Elena Bergernicoletti, Andreas F M Kilbinger, Julia Perezprieto, Salaheddine StiribaAbstract:A photosensitizer core has been covalently incorporated into a hyperbranched polyether polyol structure, using a one-step protocol. Partially deprotonated 2,2‘,4,4‘-tetrahydroxybenzophenone was used as initiator in the anionic polymerization of glycidol, yielding hyperbranched Polyglycerols with benzophenone core in every macromolecule formed. Molecular weights in the range of 1500 to 5800 g/mol and moderate polydispersity (1.3 < Mw/Mn < 2) were obtained. Incorporation of the functional core was unequivocally evidenced by MALDI−TOF mass spectroscopy. Further modification via acetylation of the Polyglycerol hydroxyl groups afforded polymers of lowered polarity. The photochemical and photophysical behavior of the obtained benzophenone core-containing hyperbranched Polyglycerols has been investigated in a variety of solvents and compared with that of the model compound 2,2‘,4,4‘-tetramethoxybenzophenone. The hyperbranched polymer periphery induced molecular weight-dependent properties in the photoactive core...
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hyperbranched molecular nanocapsules comparison of the hyperbranched architecture with the perfect linear analogue
Journal of the American Chemical Society, 2002Co-Authors: Salaheddine Stiriba, Holger Kautz, Holger FreyAbstract:The results of a comparative study of hyperbranched, partially esterified Polyglycerols with their linear Polyglycerol analogues with respect to molecular encapsulation and phase transfer are reported. Two hyperbranched Polyglycerol samples with molecular weights of 3000 and 8000 g/mol (Mw/Mn = 1.3), respectively, have been partially esterified using palmitoyl chloride. The same modification was applied to the structurally analogous linear Polyglycerol (3000 g/mol). A detailed UV−vis study correlated with viscosity experiments demonstrated that only the hyperbranched core−shell structures form “nanocapsules”, leading to the encapsulation of polar guest molecules. The results underline the crucial role of the hyperbranched topology and the resulting solution conformation for supramolecular guest encapsulation and phase transfer. The unusually compact (“collapsed”) structure assumed by the hyperbranched core−shell amphiphiles in apolar media is responsible for the formation of a hydrophilic compartment, cap...
Maria Gazda - One of the best experts on this subject based on the ideXlab platform.
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preparation and characterization of rigid polyurethane Polyglycerol nanocomposite foams
European Polymer Journal, 2012Co-Authors: Łukasz Piszczyk, Michał Strankowski, Magdalena Danowska, Józef Haponiuk, Maria GazdaAbstract:This work reports on the preparation of polyurethane–polyisocyanurate (PUR–PIR) foams containing different Polyglycerols and layered silicate nanoclays. The rigid polyurethane foams were obtained in a laboratory scale, in a single step method, from a two-component system with a NCO to OH groups ratio equal to two. The reaction mixture consisted of the proper amounts of a commercial oligoetherpolyol, Polyglycerol, catalysts, water, nanofiller, and polymeric diphenylmethane diisocyanate. The obtained foams containing 6% of one of three types of montmorillonite (MMT) (Cloisite 30B, Laponite RD, Bentonite) were characterized in terms of their structure, density, brittleness, compressive strength and thermal stability. The nanocomposite foams showed a higher number of cells with a smaller cell size in the presence of MMT, while the foams modified with nanofiller Cloisite 30B presented the best compressive strength and the best fire resistance.
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Preparation and characterization of rigid polyurethane–Polyglycerol nanocomposite foams
European Polymer Journal, 2012Co-Authors: Łukasz Piszczyk, Michał Strankowski, Magdalena Danowska, Józef Haponiuk, Maria GazdaAbstract:This work reports on the preparation of polyurethane–polyisocyanurate (PUR–PIR) foams containing different Polyglycerols and layered silicate nanoclays. The rigid polyurethane foams were obtained in a laboratory scale, in a single step method, from a two-component system with a NCO to OH groups ratio equal to two. The reaction mixture consisted of the proper amounts of a commercial oligoetherpolyol, Polyglycerol, catalysts, water, nanofiller, and polymeric diphenylmethane diisocyanate. The obtained foams containing 6% of one of three types of montmorillonite (MMT) (Cloisite 30B, Laponite RD, Bentonite) were characterized in terms of their structure, density, brittleness, compressive strength and thermal stability. The nanocomposite foams showed a higher number of cells with a smaller cell size in the presence of MMT, while the foams modified with nanofiller Cloisite 30B presented the best compressive strength and the best fire resistance.
Łukasz Piszczyk - One of the best experts on this subject based on the ideXlab platform.
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Rigid polyurethane foams from a Polyglycerol-based polyol
European Polymer Journal, 2014Co-Authors: Łukasz Piszczyk, Michał Strankowski, Magdalena Danowska, Aleksander Hejna, Józef HaponiukAbstract:Abstract Rigid polyurethane foams (rPUs) were synthesized by replacing 35 and 70 wt.% of petrochemical polyol with Polyglycerol. Two types of Polyglycerol with different molecular weights and hydroxyl numbers were used to obtain new “green” polyurethane–Polyglycerol foams. The foams were prepared by a single step method for the ratio of NCO/OH groups equal to 2. rPUs synthesized with Polyglycerol showed regular cellular structure, with cell diameters comparable to those of reference foam. The apparent density and compressive strength of foams increased with increasing content of Polyglycerols. The highest compressive strength of 240 kPa was observed for the foam containing 70 wt.% of Polyglycerol PGK. In the case of foams comprising 35 wt.% of Polyglycerols and the reference foam synthesized with petrochemical polyol only, the values of thermal stability, thermal conductivity (k value) and closed cell content were comparable.
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preparation and characterization of rigid polyurethane Polyglycerol nanocomposite foams
European Polymer Journal, 2012Co-Authors: Łukasz Piszczyk, Michał Strankowski, Magdalena Danowska, Józef Haponiuk, Maria GazdaAbstract:This work reports on the preparation of polyurethane–polyisocyanurate (PUR–PIR) foams containing different Polyglycerols and layered silicate nanoclays. The rigid polyurethane foams were obtained in a laboratory scale, in a single step method, from a two-component system with a NCO to OH groups ratio equal to two. The reaction mixture consisted of the proper amounts of a commercial oligoetherpolyol, Polyglycerol, catalysts, water, nanofiller, and polymeric diphenylmethane diisocyanate. The obtained foams containing 6% of one of three types of montmorillonite (MMT) (Cloisite 30B, Laponite RD, Bentonite) were characterized in terms of their structure, density, brittleness, compressive strength and thermal stability. The nanocomposite foams showed a higher number of cells with a smaller cell size in the presence of MMT, while the foams modified with nanofiller Cloisite 30B presented the best compressive strength and the best fire resistance.
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Preparation and characterization of rigid polyurethane–Polyglycerol nanocomposite foams
European Polymer Journal, 2012Co-Authors: Łukasz Piszczyk, Michał Strankowski, Magdalena Danowska, Józef Haponiuk, Maria GazdaAbstract:This work reports on the preparation of polyurethane–polyisocyanurate (PUR–PIR) foams containing different Polyglycerols and layered silicate nanoclays. The rigid polyurethane foams were obtained in a laboratory scale, in a single step method, from a two-component system with a NCO to OH groups ratio equal to two. The reaction mixture consisted of the proper amounts of a commercial oligoetherpolyol, Polyglycerol, catalysts, water, nanofiller, and polymeric diphenylmethane diisocyanate. The obtained foams containing 6% of one of three types of montmorillonite (MMT) (Cloisite 30B, Laponite RD, Bentonite) were characterized in terms of their structure, density, brittleness, compressive strength and thermal stability. The nanocomposite foams showed a higher number of cells with a smaller cell size in the presence of MMT, while the foams modified with nanofiller Cloisite 30B presented the best compressive strength and the best fire resistance.