Academic literature on the topic 'Thermosensitive copolymers'
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Journal articles on the topic "Thermosensitive copolymers"
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Duflot, V. R., A. V. Gaivoronsky, and E. I. Lobanova. "Synthesis of thermosensitive copolymers of N-isopropylacrylamide with 2-aminoethylmethacrylate hydrochloride." Fine Chemical Technologies 16, no. 2 (May 25, 2021): 167–75. http://dx.doi.org/10.32362/2410-6593-2021-16-2-167-175.
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Objectives. Due to the increasing number of oncological diseases, active research into developing new radiopharmaceuticals is underway. Thermosensitive copolymers have valuable physicochemical properties that can be harnessed to develop therapeutic radiopharmaceuticals for treating solid tumors. The aim of this study was to develop a method for producing thermosensitive copolymers that can find use as radionuclide carriers to create therapeutic radiopharmaceuticals for treating solid tumors.Methods. Using radical copolymerization in polar solvents, we synthesized water-soluble copolymers based on N-isopropyl acrylamide and 2-aminoethyl methacrylate hydrochloride. The resulting copolymers were characterized in terms of molecular composition and hydrodynamic properties using gel permeation chromatography, IR spectroscopy, potentiometry, and viscometry. Changes in optical density during temperature scanning helped determine the phase transition temperature (PTT) of aqueous copolymer solutions.Results. We developed a method for preparing copolymers of N-isopropylacrylamide with 2-aminoethyl methacrylate using radical copolymerization in water and isopropanol with a content of 2-aminoethyl methacrylate hydrochloride in a copolymer up to 23 mol %. We studied how the second comonomer affected the PTT of the aqueous copolymer solutions. An increase in the content of 2-aminoethyl methacrylate in the copolymer caused the PTT to increase. We found that the change in the PTT depending on the content of 2-aminoethyl methacrylate units in the copolymer had a straightforward relationship with its content up to 17 mol %. The use of physiological saline as a solvent led to a temperature decrease of the phase transition by two degrees.Conclusions. The method of producing thermosensitive copolymers by radical copolymerization in isopropanol does not allow creating a radionuclide carrier. Solutions of the obtained lowmolecular weight oligomers form coacervate solutions, which will inevitably cause the radionuclide to spread throughout the body. The copolymers obtained by radical copolymerization in water with the content of the second comonomer 2-aminoethyl methacrylate from 10–17 mol % can be used as a radionuclides carrier provided that a physiological solution of sodium chloride is used as a solvent.
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Graillot, A., S. Djenadi, C. Faur, D. Bouyer, S. Monge, and J. J. Robin. "Removal of metal ions from aqueous effluents involving new thermosensitive polymeric sorbent." Water Science and Technology 67, no. 6 (March 1, 2013): 1181–87. http://dx.doi.org/10.2166/wst.2013.671.
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In this work, new thermosensitive copolymers bearing phosphonated groups were synthesized and used to remove metal pollution. Sorption properties are brought by hydrolyzed (dimethoxyphosphoryl)methyl 2-methylacrylate (hMAPC1) monomer. N-n-propylacrylamide (NnPAAm) led to the thermoresponsive properties of the copolymers. Low lower critical solution temperature (LCST) values were observed, ranging between 20 and 25 °C depending on the molar ratio of each monomer in the copolymer. Sorption properties of these copolymers towards nickel ions were evaluated for increasing temperatures (10–40 °C), Ni ion concentrations of 20 mg L−1 and pH values between 3 and 7. Best results were observed for temperatures just lower than the LCST (20 °C), when the copolymer was fully soluble in water solution. For temperature higher than the LCST, phosphonic diacid groups accessibility was considerably reduced by the precipitation of the thermosensitive part of the copolymer leading to lower sorption properties. In these conditions, the highest Ni removal by the copolymer was observed for pH = 7, when there was almost no competition between the sorption of H+ and Ni2+ ions on the phosphonic acid groups. These optimal conditions enabled removal of about 70% of the nickel in the synthetic effluent.
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Tanimoto, Satoshi, Naoto Yagi, and Hitoshi Yamaoka. "Application of Thermosensitive Peptide Copolymer Gels to Removal of Endocrine Disruptor." Research Letters in Materials Science 2009 (2009): 1–4. http://dx.doi.org/10.1155/2009/597308.
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Poly(L-leucine)-block-poly(ethylene glycol)-block-poly(L-leucine) triblock copolymers were synthesized by a ring-opening polymerization ofα-amino acid N-carboxyanhydride with amino-terminated PEG as an initiator. The chloroform solution of these peptide copolymers showed a thermo-sensitive sol-gel transition. The transition temperature varied as a function of the length of peptide segments. Additionally, we used these peptide copolymers to remove an endocrine disruptor such as bisphenol A from its aqueous solution. As a result, it became clear that the peptide copolymer gel used in this study could capture bisphenol A efficiently.
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Qin, Jian, Yun Suk Jo, and Mamoun Muhammed. "Coating Nanocrystals with Amphiphilic Thermosensitive Copolymers." Angewandte Chemie International Edition 48, no. 42 (October 5, 2009): 7845–49. http://dx.doi.org/10.1002/anie.200900489.
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Qin, Jian, Yun Suk Jo, and Mamoun Muhammed. "Coating Nanocrystals with Amphiphilic Thermosensitive Copolymers." Angewandte Chemie 121, no. 42 (October 5, 2009): 7985–89. http://dx.doi.org/10.1002/ange.200900489.
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Zhu, X. X., D. Avoce, H. Y. Liu, and A. Benrebouh. "Copolymers ofN-alkylacrylamides as thermosensitive hydrogels." Macromolecular Symposia 207, no. 1 (February 2004): 187–92. http://dx.doi.org/10.1002/masy.200450317.
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Patel, Sulabh P., Ravi Vaishya, Gyan Prakash Mishra, Viral Tamboli, Dhananjay Pal, and Ashim K. Mitra. "Tailor-Made Pentablock Copolymer Based Formulation for Sustained Ocular Delivery of Protein Therapeutics." Journal of Drug Delivery 2014 (June 22, 2014): 1–15. http://dx.doi.org/10.1155/2014/401747.
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The objective of this research article is to report the synthesis and evaluation of novel pentablock copolymers for controlled delivery of macromolecules in the treatment of posterior segment diseases. Novel biodegradable PB copolymers were synthesized by sequential ring-opening polymerization. Various ratios and molecular weights of each block (polyglycolic acid, polyethylene glycol, polylactic acid, and polycaprolactone) were selected for synthesis and to optimize release profile of FITC-BSA, IgG, and bevacizumab from nanoparticles (NPs) and thermosensitive gel. NPs were characterized for particle size, polydispersity, entrapment efficiency, and drug loading. In vitro release study of proteins from NPs alone and composite formulation (NPs suspended in thermosensitive gel) was performed. Composite formulations demonstrated no or negligible burst release with continuous near zero-order release in contrast to NPs alone. Hydrodynamic diameter of protein therapeutics and hydrophobicity of PB copolymer exhibited significant effect on entrapment efficiency and in vitro release profile. CD spectroscopy confirmed retention of structural conformation of released protein. Biological activity of released bevacizumab was confirmed by in vitro cell proliferation and cell migration assays. It can be concluded that novel PB polymers can serve a platform for sustained delivery of therapeutic proteins.
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Fu, Wenxin, and Bin Zhao. "Thermoreversible physically crosslinked hydrogels from UCST-type thermosensitive ABA linear triblock copolymers." Polymer Chemistry 7, no. 45 (2016): 6980–91. http://dx.doi.org/10.1039/c6py01517d.
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Castro-Hernández, Ana, and Norma Aidé Cortez-Lemus. "Thermo/pH Responsive Star and Linear Copolymers Containing a Cholic Acid-Derived Monomer, N-Isopropylacrylamide and Acrylic Acid: Synthesis and Solution Properties." Polymers 11, no. 11 (November 11, 2019): 1859. http://dx.doi.org/10.3390/polym11111859.
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In this work three CTAs trithiocarbonate-type were synthesized—bifunctional (with PEG), trifunctional (with glycerol), and tetrafunctional (PERT)—and used in the controlled polymerization of 2-(acryloyloxy)ethyl cholate (CAE) via reversible addition-fragmentation chain transfer (RAFT) polymerization. The resulting macroCTAs containing a cholic acid-derived polymer were chain extended with N-isopropylacrylamide with or without acrylic acid. The thermosensitive and/or pH properties of these copolymers were studied in PBS solutions. The copolymers synthesized without poly(acrylic acid) (PAAc) were unstable above the transition temperature. Similar behavior was observed for the copolymer solutions containing PAAc (2% in feed) at lower values of pH showing a faster precipitation above the LCST. On the contrary, copolymer solutions containing PAAc showed great stability at higher pH values for a longer time period at 37 °C. Interestingly, the Dh of the aggregates ranged from 18 to 30 nm in all copolymers (with or without PAAc) below the transition temperature, although the topology and the block sequence in the chain were significantly different.
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Nakan, U., T. Tolkyn, G. Zh Yeligbayeva, D. B. Adikanova, М. Е. Nursultanov, and Y. Shaymardan. "Preparation and characterization of thermosensitive hydrophilic copolymers." Vestnik KazNRTU 143, no. 2 (2021): 152–57. http://dx.doi.org/10.51301/vest.su.2021.i2.20.
Full textDissertations / Theses on the topic "Thermosensitive copolymers"
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Mert, Olcay. "Thermosensitive Biodegradable Mpeg-plla Block Copolymers: Syntheses, Characterizations And Applications In Drug Delivery Systems." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613268/index.pdf.
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Syntheses of biodegradable PLLA homopolymers and PLLA-mPEG diblock copolymers for the formation of thermo-sensitive gels were performed. The sol-gel transition temperature of the matrix was adjusted by altering the length of each PEG and LA component. PLLA-mPEG biocompatible copolymers, having appropriate length of each block component, showed sols at around 42-45 oC, suitable for the injection, then a gel with subsequent rapid cooling to body temperature. Topotecan and camptothecin were selected as anti-cancer drugs. Both drugs can easily hydrolyze at physiological conditions (pH=7.4). This causes the loss of its activity, and it turns into inactive toxic carboxylate form from active lactone state. To keep those anti cancer drugs in the lactone form, they were efficiently loaded into PLLA-mPEG gels in different loading ratios. Their stability in gel was fully examined with HPLC and fluorescence spectroscopy. It was found that both drugs were highly stable and in active form in the prepared gels (>95 %). Then, both release profile of drugs at different loading ratios showed prolonged release over weeks. Mechanistic studies on the stabilization of CPT anti cancer drug with PLLA-mPEG gels were carried out using ATR-FTIR, confocal and optic microscopes. The cytotoxic efficacy of TPT in the PLLA-mPEG platform (PLLA-mPEG-TPT) was evaluated on LLC-1 and 4T1 cancer cell lines by MTT assay. In vivo, the administration of PLLA-mPEG-TPT to the mice bearing breast tumours established with 4T1 cells resulted in a significant reduction in tumour size and better survival percentages. Additionally, stabilization of CPT and TPT with gels may find another application on solid tumors in brain via local injection. A novel conducting polymer was successfully synthesized via electropolymerization of 1-(1H-pyrrol-1-yl)-2,5-di(thiophen-2-yl)-1H-pyrrole. The electrochemical and electro-optical properties of the corresponding polymer, which was the first example of polymer containing 1,1&rsquo
-bipyrrole units, were elaborated using electroanalytical and spectroscopic techniques. Cyclic voltammograms and electrooptical studies showed that the polymer has a stable and well-defined reversible redox process as well as electrochromic behavior. The processable polymer film also possessed a yellowish orange light emitter property.
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Ta, Terence. "PH/thermosensitive liposomes modified with poly(N-isopropylacrylamide-co-propylacrylic acid) copolymers for focused ultrasound-triggered release of Doxorubicin." Thesis, Boston University, 2012. https://hdl.handle.net/2144/31615.
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Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
Chemotherapy requires the systemic administration of large doses of highly toxic antineoplastic agents in order to achieve therapeutically relevant concentrations at the tumor. These drugs typically act by impairing cell mitosis, effectively targeting rapidly-dividing cells that are the hallmarks of cancer. Non-cancerous cells that divide rapidly under normal circumstances are often damaged, leading to adverse side effects including myelosuppression, alopecia, and organ-specific toxicities. One potential means of reducing off-site toxicities is to encapsulate highly toxic chemotherapeutics into thermosensitive liposomes (TSL). These nanoscale structures are formed from temperature-sensitive lipids, and are designed to passively target the tumor by being large enough to avoid renal clearance while small enough to slip through leaky blood vessels characteristic of tumor vasculature. At the tumor, externally applied heating triggers a burst release of therapeutically relevant concentrations of drug. Current TSL formulations suffer from (i) approaches for heating that put healthy tissue surrounding the tumor at risk; (ii) lack of stability at physiological conditions (e.g. premature leakage of drug); and (iii) lack of noninvasive approaches for monitoring temperature elevation. This project presents a dual pH/thermosensitive liposome (PTSL) for the deliver of Doxorubicin (DOX), a commonly administered chemotherapeutic. Copolymers of temperature-responsive N-isopropylacrylamide (NIPAAm) and pH-responsive propylacrylic acid (PAA) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, yielding copolymers with dual pH/temperaturedependent phase transition properties. When attached to liposomes, copolymers were membrane-disruptive m a pH/temperature-dependent manner, conferring pH/temperature-sensitive drug release properties to the liposome. These dual-sensitive properties can potentially exploit the slightly acidic environment of the tumor when PTSL are administered with externally applied heating. PTSL demonstrated enhanced release profile, significantly lower thermal dose threshold, and lower IC50 when compared to traditional TSL, and were stable in serum with minimal premature drug leakage. The application of MR-guided focused ultrasound (MRgFUS) as a noninvasive, highly controllable thermal source for triggering drug release and monitoring temperature elevations was demonstrated in vivo. PTSL combined with MRgFUS treatment resulted in delayed tumor growth when compared to PTSL alone and control treatments. This PTSL-MRgFUS delivery system thus addresses the limitations of existing TSL therapies and has potential applications in the clinic.
2031-01-01
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Qayouh, Hicham. "Copolymères diblocs amphiphiles et thermostimulables : synthèse contrôlée et étude préliminaire de leur auto-organisation." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0230/document.
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Les travaux présentés dans ce manuscrit ont porté sur l'élaboration de nouveaux copolymères dibloc amphiphiles (poly(ε-caprolactone)-b-poly(méthacrylate d'oligo(éthylène glycol) méthyl éther) biodégradables, thermostimulables et susceptibles d'être employés dans des applications respectueuses de l'environnement comme le traitement des eaux contaminées. La particularité de ces copolymères provient d'une part de la différence de solubilité des deux blocs et d'autre part de l'association d'un bloc hydrophobe biodégradable à un bloc thermostimulable hydrophile. Les propriétés de ces copolymères en milieu aqueux ont ainsi été évaluées en fonction de la température. Ces composés ont été obtenus par la combinaison de deux techniques de polymérisation contrôlée en utilisant un amorceur difonctionnel. Pour cela, deux stratégies ont été testées : i) la polymérisation par ouverture de cycle (POC) de l'ε-caprolactone à partir d'un macro-amorceur de poly(méthacrylate d'oligo(éthylène glycol) méthyl éther) à terminaison OH après avoir mis au point les conditions expérimentales de la POC en comparant plusieurs catalyseurs. ii) par polymérisation radicalaire par transfert d'atome (ATRP) du méthacrylate d'oligo(éthylène glycol) amorcée à partir d'une poly(ε-caprolactone) à extrémité bromée. Les températures critiques inférieures de solubilité (LCST) de ces copolymères ont été déterminées par UV visible. Leurs comportements micellaires ont été étudiés par mesures HPPSThe development of new biodegradable diblock copolymers poly(ε-caprolactone)-b-poly[oligo(ethylene glycol)methyl ether methacrylate], which could be used in environmental friendly applications such as treatment of contaminated water has been the main goal of this work. For the preparation these copolymers, the ring-opening polymerization (ROP) and the Atom Transfer Radical Polymerization (ATRP) were combined by using a bifunctional initiator. The two-step route for the synthesis of these copolymers was using either ATRP or ROP as first step and the other polymerization secondly. Each polymerization was studied carefully in order to control the macromolecular parameters of the copolymers. On the one hand, the ATRP of methacrylates bearing oligo(ethylene glycol) was carried out by using poly(ε-caprolactone) with bromide end-group as macroinitiator. On the other hand, the ring opening polymerization of ε-caprolactone was initiated by the hydroxyl end-group of the poly[oligo(ethylene glycol)methyl ether methacrylate], using tin octoate, tin tetrakis(phenylethynyl) or bismuth triflate as catalysts. The Low Critical Solution Temperature (LCST) of these amphiphilic diblock copolymers in aqueous medium have been determined by UV-visible spectroscopy. Their micellar behaviors were also studied by measuring size by HPPS
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Lauber, Lionel. "Control of the rheological properties of hydrogels made by self-assocation of amphiphilic copolymers, blocks and grafts, anionics or cationics." Thesis, Le Mans, 2016. http://www.theses.fr/2016LEMA1010/document.
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L’objectif de ce travail était de contrôler les propriétés rhéologiques de solutions aqueuses de copolymères amphiphiles. Dans l’eau, ces copolymères s’auto-associent et leurs propriétés peuvent être contrôlées en partie par leur dynamique d’échange. Il avait précédemment était montré que cette dynamique pouvait être contrôlée par le pH et la quantité d’unités acide acrylique dans des triblocs BAB (THx) où le bloc A est du poly(acide acrylique) (PAA) et les blocs B sont des copolymères statistiques (MHx) d’acrylate de n-butyle (nBA) et d’acide acrylique (AA). Tout d’abord, l’étude de l’auto-association en solution des blocs B seuls (MHx) a montré un lien fort entre leur agrégation et celle des diblocs de type BA (DHx). Cette agrégation est contrôlée par la quantité de charge des blocs B. Par la suite, des mélanges de triblocs (BAB) THx contenant différentes proportions (x) d’unités AA ont permis la formation de réseaux hybrides dont les propriétés rhéologiques sont maîtrisées par formulation plutôt que via la chimie. Des propriétés rhéologiques similaires aux triblocs BAB (THx) ont été obtenues avec des copolymères greffés possédant un squelette hydrophile PAA et des greffons B. Leurs propriétés rhéologiques sont principalement contrôlées par la structure chimique des blocs B, mais aussi par le taux de greffage. Ces copolymères greffés devraient être plus simples à obtenir à l’échelle industrielle que des triblocs. Pour finir, l’approche consistant à incorporer des unités hydrophiles dans les blocs hydrophobes de copolymères amphiphiles pour en contrôler la dynamique d’échange a été appliquée avec succès à des copolymères à base de méthacrylate de diméthylaminoéthyle et de méthacrylate de n-butyle. Leurs propriétés rhéologiques peuvent être contrôlées à nouveau par le pH, mais dans une gamme différente des polymères à base d’acide acrylique, et aussi dans une certaine mesure par la températureThe aim of this work was to control the rheological properties of aqueous solutions of amphiphilic copolymers. In water, these copolymers self-assemble and part of their properties can be controlled by their dynamic of exchange. As previously reported, the exchange dynamics can be controlled by the pH and the acrylic acid (AA) content for BAB triblock copolymers (THx) consisting of a poly(acrylic acid) (PAA) A block and two statistical B blocks (MHx) of n-butyl acryle (nBA) and AA.First, the study of the self-association of B blocks (MHx) alone showed a strong relationship between their aggregation and the one of BA diblocks (DHx). This aggregation was mainly controlled by the amount of charges within the B blocks.Then, mixtures of BAB triblocks (THx) with different contents of AA units, x, formed hybrid networks the rheological properties of which were controlled by formulation rather than chemistry.Similar rheological properties were obtained using graft copolymers consisting of a PAA hydrophilic backbone and B grafts. Their rheological properties were mainly controlled by the chemical structure of the B grafts and by the grafting density. Such graft copolymers should be easier to produce at an industrial scale than triblock copolymers.To finish, the strategy consisting of incorporating hydrophilic units inside the hydrophobic blocks of amphiphilic copolymers to control their exchange dynamics was successfully applied to copolymers made of dimethylaminoethyl methacraylate and n-butyl methacrylate. Their rheological properties were controlled by the pH on a different pH-range than the AA based polymers, and, to some extent, by the temperature
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Kristen, Juliane Ute. "Amphiphilic BAB-triblock copolymers bearing fluorocarbon groups : synthesis and self-organization in aqueous media." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2012/6178/.
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In this work new fluorinated and non-fluorinated mono- and bifunctional trithiocarbonates of the structure Z-C(=S)-S-R and Z-C(=S)-S-R-S-C(=S)-Z were synthesized for the use as chain transfer agents (CTAs) in the RAFT-process. All newly synthesized CTAs were tested for their efficiency to moderate the free radical polymerization process by polymerizing styrene (M3). Besides characterization of the homopolymers by GPC measurements, end- group analysis of the synthesized block copolymers via 1H-, 19F-NMR, and in some cases also UV-vis spectroscopy, were performed attaching suitable fluorinated moieties to the Z- and/or R-groups of the CTAs.
Symmetric triblock copolymers of type BAB and non-symmetric fluorine end- capped polymers were accessible using the RAFT process in just two or one polymerization step. In particular, the RAFT-process enabled the controlled polymerization of hydrophilic monomers such as N-isopropylacrylamide (NIPAM) (M1) as well as N-acryloylpyrrolidine (NAP) (M2) for the A-blocks and of the hydrophobic monomers styrene (M3), 2-fluorostyrene (M4), 3-fluorostyrene (M5), 4-fluorostyrene (M6) and 2,3,4,5,6-pentafluorostyrene (M7) for the B-blocks.
The properties of the BAB-triblock copolymers were investigated in dilute, concentrated and highly concentrated aqueous solutions using DLS, turbidimetry, 1H- and 19F-NMR, rheology, determination of the CMC, foam height- and surface tension measurements and microscopy. Furthermore, their ability to stabilize emulsions and microemulsions and the wetting behaviour of their aqueous solutions on different substrates was investigated. The behaviour of the fluorine end-functionalized polymers to form micelles was studied applying DLS measurements in diluted organic solution.
All investigated BAB-triblock copolymers were able to form micelles and show surface activity at room temperature in dilute aqueous solution. The aqueous solutions displayed moderate foam formation. With different types and concentrations of oils, the formation of emulsions could be detected using a light microscope. A boosting effect in microemulsions could not be found adding BAB-triblock copolymers. At elevated polymer concentrations, the formation of hydrogels was proved applying rheology measurements.Im Rahmen dieser Arbeit wurden neue fluorierte und unfluorierte mono- und bifunktionelle Trithiocarbonate der Typen Z-C(=S)-S-R und Z-C(=S)-S-R-S-C(=S)-Z zur Anwendung als CTAs (chain- transfer agents) im RAFT-Polymerisationsverfahren hergestellt. Alle CTAs wurden erfolgreich auf ihre Effizienz zur Steuerung des radikalischen Polymerisationsverfahrens hin durch Polymerisation von Styrol (M3) getestet. Neben GPC-Messungen wurden Endgruppenanalysen der synthetisierten Blockcopolymere mittels 1H-, 19F-NMR und in manchen Fällen auch UV-Vis Spektroskopie durchgeführt. Dazu wurden die Z- und/oder R-Gruppen der CTAs mit geeigneten fluorierten Gruppen versehen. Durch Anwendung des RAFT Verfahrens konnten symmetrische Triblockcopolymere vom Typ BAB bzw. mit einer Fluoralkylgruppe endgecappte unsymmetrische Polymere in nur zwei bzw. einem Polymerisationsschritt hergestellt werden. Das RAFT- Polymerisationsverfahren ermöglicht sowohl die Polymerisation hydrophiler Monomere wie N-Isopropylacrylamid (NIPAM) (M1) oder N-Acryloylpyrrolidin (NAP) (M2) für die A-Blöcke als auch der hydropoben Monomere Styrol (M3), 2-Fluorostyrol (M4), 3-Fluorostyrol (M5), 4- Fluorostyrol (M6) und 2,3,4,5,6- Pentafluorostyrol (M7) für die B-Blöcke. Die Eigenschaften der Blockcopolymere in verdünnten, konzentrierten und hochkonzentrierten wässrigen Lösungen wurden mittels DLS, Trübungsphotometrie, 1H- und 19F-NMR, Rheologie, CMC- sowie Schaumhöhen- und Oberflächenspannungsmessungen und Lichtmikroskopie untersucht. Weiterhin wurden ihre Eigenschaften als Emulgatoren und in Mikroemulsion untersucht. Das Micellbildungsverhalten der hydrophob endfunktionalisierten Polymere wurde mittels DLS Messungen in verdünnter organischer Lösung untersucht. Alle untersuchten BAB-Triblöcke bildeten Micellen und zeigten Oberflächenaktivität bei Raumtemperatur in verdünnter, wässriger Lösung. Weiterhin zeigen die wässrigen Lösungen der Polymere mäßige Schaumbildung. Mit verschiedenen Öltypen und Ölkonzentrationen wurden Emulsionen bzw. Mikroemulsionen gebildet. In Mikroemulsion wurde durch Zugabe von BAB-Triblockopolymeren kein Boosting-Effekt erzielt werden. Bei Untersuchung höherer Polymerkonzentrationen wurde die Bildung von Hydrogelen mittels rheologischer Messungen nachgewiesen. Verschiedene Substrate konnten benetzt werden. Die hydrophob endgecappten Polymere bilden in verdünnter organischer Lösung Micellen, die mittels DLS untersucht wurden, und zeigen somit Tensidverhalten in nichtwässriger Lösung.
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Smolková, Miroslava. "Enkapsulace léčiv v termocitlivých micelárních gelech." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-295704.
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Presented diploma thesis deals with drug encapsulation of Sulfathiazole (STA) in thermosensitive hydrogel composed of amphiphilic fibrous molecules of copolymer poly(D,L-lactide-co-glycolide)-block-poly(ethylene glycol)-block-poly(D,L-lactide-co-glycolide) (PLGA-PEG-PLGA). In the experimental part, the structure of the micelles which is dependent on the concentration of the default copolymer, was thoroughly described. The method of dynamic light scattering (DLS) was used to dimensionally characterize the micellar size in aqueous solution. At the same time, the Cryo-Transmission Electron Microscopy (Cryo-TEM) imaging technique confirmed the transition from spherical micelles to fibrous branched structures with a number of topological interactions. The change in viscoelastic properties of micellar hydrogel after addition of STA was studied by rheological analysis. The studied triblock copolymer appears to be a suitable tissue engineering material as a carrier in applications for targeted drug delivery and tissue regeneration.
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Chamradová, Ivana. "Polymerní materiály pro řízenou administraci léčiv a řízené uvolňování aktivních látek." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2015. http://www.nusl.cz/ntk/nusl-233407.
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Literární rešerše předložené dizertační práce shrnuje poznatky jak o současně používaných biomateriálech, tak i o tzv. „chytrých“ biomedicínských materiálech mezi které patří termocitlivé kopolymery. Mezi tyto kopolymery, jejichž vodné roztoky gelují při teplotě lidského těla (37 °C), řadíme amfifilní triblokové kopolymery skládající se z hydrofobního laktidu, glykolidu a hydrofilního polyethylen glykolu (PLGA PEG PLGA). Komerčně dostupné termocitlivé kopolymery známé pod názvem ReGel or OncoGel jsou v současné době využívány jako injekčně aplikovatelné nosiče s postupným uvolňováním léčiv, zejména při léčbě cukrovky nebo onkologického onemocnění. Nicméně PLGA PEG PLGA triblokový kopolymer může být použit I jako polymerní nosič anorganického léčiva případně jako biodegradabilní implantát v dentálních či ortopedickýchých aplikacích. Z toho důvodu byl vybrán anorganický biokompatibilní hydroxyapatit (HAp) pro své majoritní zastoupení v tvrdých tkáních. Experimentální část je zaměřena na přípravu HAp/PLGA PEG PLGA kompozitů, ve kterých je HAp buď ve formě nano- (n-HAp) nebo „core-shell“ částic (CS). Nové CS částice, připravené dvouemulzní metodou, jsou složeny z „tuhého“ HAp jádra obaleného termocitlivým kopolymerem, který je navíc funkcionalizován kyselinou itakonovou (ITA/PLGA PEG PLGA/ITA). Funkcionalizace pomocí ITA vnáší do původní struktury kopolymeru jak síťovatelné dvojné vazby, tak i koncové karboxylové skupiny. Volné karboxylové skupiny na koncích ITA/PLGA PEG PLGA/ITA kopolymerního obalu byly dále zesíťovány za vzniku 3D chemické sítě (CS-x), jejíž životnost je řízena a kontrolována. ATR-FTIR spektroskopie prokázala přítomnost „nových“ esterových vazeb vzniklých karbodiimidovou reakcí –OH a –COOH skupin, kterým náleží adsorpční pásy ve vlnové délce 1021 cm-1.. n-HAp a CS-x částice byly přidány do kopolymerní termocitlivé matrice (PLGA PEG PLGA) za účelem charakterizace jejich reologického chování. Bylo zjištěno, že pokud bylo do polymerní matrice přidáno méně než 10 hm. % CS-x částic a jen 5 hm.% n-HAp kompozit si zachoval své termocitlivé vlastnosti. Na druhou stranu, přídavek vyššího množství HAp částic do polymerní matrice zajistil změnu vodného polymerního solu v permanentní gel při teplotě nad 37 °C. Analýza ICP-OES prokázala rychlejší uvolňování CS-x částic z 10 hm/obj. % PLGA PEG PLGA polymerní matrice do inkubačního média (6 % 9. den) než tomu bylo u n-HAp částic (jen 3 %), které jsou vázány více v micelární struktuře kopolymeru. Proto, kompozit na bázi n-HAP částic tvořící tuhý trvalý gel při tělesné teplotě, je vhodný více jako biologicky rozložitelné kostní lepidlo, zatímco kompozit z CS-x částic a termocitlivého kopolymeru je vhodný jako nosič léčiv pro injekční aplikace.
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Boháčová, Zdeňka. "Polymerace za otevření kruhu laktonů a laktidů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2015. http://www.nusl.cz/ntk/nusl-233379.
Full textAbstract:
Medicínské aplikace tvoří z biodegradabilních alifatických polyesterů na bázi polylaktonů, polylaktidů a jejich kopolymerů velmi atraktivní skupinu materiálů. Metody přípravy těchto polymerů jsou založeny na polymeraci za otevření kruhu laktonů a laktidů. Mnoho organokovových sloučenin se vyznačují jako účinné a vysoce selektivní katalyzátory těchto polymerací, avšak je známo, že deriváty těžkých kovů jsou škodlivé pro lidský organismus. Z tohoto důvodu je v dnešní době rostoucí zájem o vývoj účinných „green“ polymeračních systémů pro syntézu biodegradabilních alifatických polyesterů. Předložená disertační práce se věnuje přípravě alifatických polyesterů založených na polykaprolaktonu, polylaktidu, polyglykolidu a zejména jejich kopolymeru pomocí organického katalyzátoru náležícího do skupiny N-heterocyklických karbenů (NHC) bez přítomnosti centrálního atomu těžkého kovu. Literární rešerše je zaměřená na pokroky v polymeraci za otevření kruhu (ROP) cyklických esterů (laktonů a laktidů) pomocí organických "metal-free" katalyzátorů. Nicméně, nebyly nalezeny žádné studie, kde se pro přípravu polyglykolidu nebo jeho kopolymerů využívá polymerace za otevření kruhu pomocí karbenových katalyzátorů. Experimentální část práce popisuje přípravu a vlastnosti 1,3-di-tert-butylimidazol-2-ylidenu (NHC-tBu) karbenu připraveného z jeho stabilní chloridové soli. Další část je zaměřena na přípravu polyesterů z cyklických monomerů, jmenovitě L-laktidu, D, L-laktidu, glykolidu a -kaprolaktonu pomocí NHC-tBu jako katalyzátoru. Byla zkoumána nová metoda přípravy termosenzitivního amfifilního triblokového kopolymeru na bázi biodegradabilního hydrofobního polylaktidu, polyglykolidu a biokompatibilního hydrofilního polyethylenglykolu (PLGA–PEG–PLGA) pomocí připraveného NHC-tBu. Dále byly studovány podmínky polymerace (například: přečištění monomeru, teploty polymerace, různé typy rozpouštědel, poměry rozpouštědla ku monomeru a nebo různé poměry iniciátoru ku katalyzátoru). Na závěr byl připravený PLGA–PEG–PLGA kopolymer srovnán s kopolymerem připraveným pomocí Sn(II)2-ethylhexanoátu. NHC-tBu se v přítomnosti PEG projevil jako účinný katalyzátor polymerace za otevření kruhu laktonu a laktidů. Připravené kopolymery dosahovaly vysoké konverze monomeru (70 – 85%) s polydisperzitou (Mw/Mn okolo 1,2). Byl připraven PLGA–PEG–PLGA kopolymer se dvěma fázovými přechody (sol-gel a gel suspenze) a gelační teplotou v rozmezí 35 – 43 °C. Změny polymeračních podmínek neměly ve většině případů zásadní vliv na chemické vlastnosti kopolymeru, jako jsou molekulová hmotnost nebo polydisperzita, ale měly významný vliv na visko-elastické vlastnosti.
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Louguet, Stéphanie. "Nanoparticules hybrides thermosensibles pour la théranostique." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14242/document.
Full textAbstract:
Cette étude concerne le développement de nanoparticules hybrides offrant de nouvelles stratégies pour la thérapie et le diagnostic médical. Elles sont constituées d’un cœur magnétique jouant le rôle d’agent de contraste pour l’IRM et d’inducteur de chaleur par hyperthermie, d’une couronne de polymère thermosensible permettant d’encapsuler des principes actifs et de peptides de reconnaissance biologique. Une grande partie de l’étude a consisté à étudier les processus d'adsorption de copolymères poly(éther)-b-poly(L-lysine) de composition variable sur les particules magnétiques et à comprendre le rôle de la conformation des chaînes polymère à la surface des particules sur la stabilité des colloïdes en milieu physiologique. Un agent antitumoral a été encapsulé puis libéré de façon contrôlée sous l’effet d’un champ magnétique alternatif en exploitant le caractère thermosensible des blocs polyéthers. Des séquences peptidiques ciblant les zones d’inflammation de la barrière hémato-encéphalique ont été greffées sur les copolymères. L’efficacité du ciblage a été validée par IRM et fluorescence sur un modèle animal démontrant ainsi la multifonctionnalité des nanoparticulesThis work deals with the development of hybrid nanoparticles that could offer new strategies for therapy and diagnostic. These are based on a magnetic core which can play the role of contrast agent for MRI as well as heat inductor in AC magnetic field. This inorganic core is surrounded by a thermo-responsive polymeric brush that controls the loading and the release of drugs, and can be functionalized by specific ligands ensuring the targeting specificity. A large part of this work consists in studying the adsorption mechanism of poly(ether)-b-poly(L-lysine) based block copolymers onto magnetic particle and to better understand the influence of the polymer chain conformation at particles surface on the colloidal stability under physiological conditions. An anticancer drug has been loaded and released in a controlled manner under alternative magnetic field by taking advantage from the thermosensitivity of the polyether block. Targeting peptides specific of inflammation sites at the blood brain barrier have been grafted onto copolymers. The targeting specificity has been demonstrated by MRI and fluorescence imaging in rats attesting the multifunctionality of such nanoparticles
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Hemery, Gauvin. "Synthesis of magnetic and thermosensitive iron oxide based nanoparticles for biomedical applications." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0729/document.
Full textAbstract:
Cette thèse présente le développement de nanoparticules hybrides avec un coeur inorganique et une couronne organique pour des applications médicales. Des nanoparticules d’oxyde de fer ont été obtenues par synthèse polyol, en contrôlant leurs cristallinités, leurs morphologies (monocoeur ou multicoeur) et leurs tailles (de 4 à 37 nm). Leurs propriétés ont été évaluées et comparées pour de possibles applications théranostiques : en thérapie pour le traitement du cancer par hyperthermie magnétique, pour le diagnostic en tant qu’agents de contraste pour l’IRM. Les surfaces des nanoparticules ont été modifiées par greffage de polymères/polypeptides pour apporter de la stabilité en milieux biologiques et de nouvelles fonctionnalités. Le poly(éthylène glycol) (PEG) a été greffé pour ses propriétés de furtivité, le poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) et des polypeptides dérivés de l’élastine (ELPs) pour leurs propriétés thermosensibles, et la sonde fluorescente DY700 pour permettre le suivi des nanoparticules in vitro et in vivo. Les propriétés magnétiques et thermosensibles de ces nanoparticules coeur-couronne ont été étudiées avec un instrument unique combinant l’hyperthermie magnétique et un système de diffusion dynamique de la lumière. Ainsi, les variations de température, de diamètre et d’intensité diffusée ont pu être mesurées simultanément. Les propriétés de nanoparticules monocoeur et multicoeur greffées avec du PEG, et des nanoparticules monocoeur greffées avec un ELP contenant un peptide pénétrant ont d’abord été évaluées in vitro. Leurs internalisations dans des cellules de tumeur cérébrale humaine (glioblastome) ont permis d’étudier leurs cytotoxicités après traitement par hyperthermie magnétique, et ont montré une baisse de viabilité cellulaire jusqu’à 90 %. In vivo, l’injection intraveineuse de ces nanoparticules dans des souris a abouti à une accumulation dans les tumeurs. L’injection intratumorale suivie du traitement par hyperthermie magnétique a conduit à des élévations de température locales d’environ 10 °C, avec un effet significatif sur l’activité des tumeursThis thesis reports the development of hybrid nanoparticles made of an inorganic iron oxide core and an organic shell for medical applications. Iron oxide nanoparticles (IONPs) were produced by the polyol pathway, leading to a good control over their crystallinity and morphology (monocore or multicore). IONPs with diameters in the range of 4 to 37 nm were produced. Their properties as MRI contrast agents were assessed and compared, for possible theranostic applications. They can be used for treating cancer by magnetic hyperthermia, and as contrast agents for MR imaging. The surface of the IONPs was modified to bring stability in biological conditions, as well as new functionalities. Poly(ethylene glycol) was grafted for its stealth property, poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) and elastin-like polypeptides (ELPs) for their thermosensitive capabilities, and a DY700 fluorescent probe was grafted for tracking nanoparticles in vitro and in vivo. The magnetic and thermosensitive properties of the nanoparticles were studied using a unique set-up combining magnetic hyperthermia with dynamic-light scattering. This set-up allowed measuring the elevations of temperature of the samples as well as variations in diameter and backscattered intensity. Monocore and multicore IONPs grafted with PEG, and monore IONPs grafted with a diblock ELP were tested in vitro. Their interactions with glioblastoma cells were studied, from the internalization pathway inside the cells to their cytotoxic effect (up to 90 %) under magnetic hyperthermia. In vivo, nanoparticles intravenously injected in mice accumulated in the tumors. Intratumoral administration followed by magnetic hyperthermia treatment led to elevations of temperature of up to 10 °C, with a significant effect on the tumor activity
Book chapters on the topic "Thermosensitive copolymers"
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Nonaka, T., K. Makinose, and S. Kurihara. "Synthesis and Properties of Water-Soluble Thermosensitive Copolymers Having Phosphonium Groups." In Stimuli-Responsive Water Soluble and Amphiphilic Polymers, 255–66. Washington, DC: American Chemical Society, 2000. http://dx.doi.org/10.1021/bk-2001-0780.ch015.
Full textConference papers on the topic "Thermosensitive copolymers"
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Geisler, Chris G., Ho-Lung Li, David M. Wootton, Peter I. Lelkes, and Jack G. Zhou. "Soft Biomaterial Study for 3-D Tissue Scaffold Printing." In ASME 2010 International Manufacturing Science and Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/msec2010-34274.
Full textAbstract:
In 3-D scaffold printing, it is critical to find a material that is suitable for your printing method, printing speed, and ease of use. For a biomaterial to best suit solid freeform fabrication techniques, it must: 1) be a low-viscous solution before being printed, 2) involve easily joined on-substrate mixing to form a homogenous gel, 3) have a short solution to gel transition time, 4) be a mechanically strong gel, and 5) have an irreversible gelation processes. Ionic crosslinkable, photocrosslinkable, and thermo-sensitive hydrogels have all been investigated and found to not fully satisfy our every requirement for SFF printing. Ionic crosslinking hydrogels can gel rapidly but tend to involve additional steps for crosslinking like freeze drying, stirring, and shaking, while some form beads, not homogenous gels. Some photocrosslinkable hydrogels would not work due to the concern for viability of cells in initial gel layers receiving copious amount of UV light. Thermosensitive hydrogels meet most of the requirements except that they are reversible gels. A new type of gel that obtains the qualities of a photocrosslinkable and thermosensitive hydrogel satisfies every requirement. A PEG-PLGA-PEG thermosensitive triblock copolymer additionally crosslinked with photocrosslinkable Irgacure 2959 allows for quick transition from solution to gel with a post-processing step utilizing UV light would add additional crosslinks to the gel structure resulting in an irreversible hydrogel.
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Geisler, Chris G., Ho-Lung Li, Qingwei Zhang, Jack G. Zhou, David M. Wootton, and Peter I. Lelkes. "Thermosensitive/Photocrosslinkable Hydrogel for Soft Tissue Scaffold Printing." In ASME 2011 International Manufacturing Science and Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/msec2011-50166.
Full textAbstract:
A new type of hydrogel for solid free-form fabrication (SFF) and rapid prototyping (RP) that obtains the qualities of a photocrosslinkable and thermosensitive hydrogel would benefit the tissue engineering field. For a material to best suit SFF and RP, it must: 1) be a low-viscous solution before being printed, 2) involve easily joined on-substrate mixing to form a homogenous gel, 3) have a short solution to gel transition time, 4) be a mechanically strong gel, and 5) have an irreversible gelation processes. A biodegradable, biocompatable thermosensitive triblock copolymer, poly(ethylene glycol-b-(DLlactic acid-co-glycolic acid)-b-ethylene glycol) (PEG-PLGA-PEG), crosslinked with photocrosslinkable Irgacure 2959 allows for quick irreversible transition from solution to gel with a post-processing step utilizing UV light. A material that gels instantaneously from a non-viscous solution to a 3-dimensional building gel could be used in multiple different types of SFF methods already developed. Since the material is also biocompatible, it can be used to replicate many different types of tissues. In this paper, the mechanism of gelation is proposed and the material relationship to the initial viscosity is investigated.
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Li, Ho-Lung, Chris G. Geisler, David M. Wootton, and Jack G. Zhou. "A New Flexible and Multi-Purpose System Design for 3-Dimensional Printing." In ASME 2011 International Manufacturing Science and Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/msec2011-50176.
Full textAbstract:
A new type of Solid freeform fabrication (SFF) machine based on Automatically Programmed Tools (APT) language has been developed to construct hydrogel scaffolds and porous structures. The system comprises three servo motors, three motor drives, three appropriate optical linear encoders, digital/analogue input and output interfaces, an air pressure control system, a UV light device, a hot plate, and a nozzle with dispensing controller. In this study, the system was connected into a PC to act as a high-performance servo controller for monitoring the control of a three axis x-y-z moving arms. The printing procedures were repeated layer-by-layer to form a 3D structure. A biocompatible and thermosensitive material, PEG-PLGA-PEG triblock copolymer, has been printed by this new three-dimensional direct printing machine and the experimental results are discussed with respect to potential applications. Our novel SFF printing system has some advantages over other commercial SFF machines, which includes: 1. Changeable printing nozzles for materials with different viscosities. 2. Re-constructible system setup for different printing purposes. 3. Capability for heterogeneous printing. 4. User-friendly software development 5. Economic system design. The study of the hardware and software and their integration are described and its new heterogeneous printing algorithm is discussed for multiple purpose uses. The integrated software has been developed to link all components of the control system together and it is easy to adapt to different applications.