Pyrene-labeled amphiphilic poly-(N-isopropylacrylamides) prepared by using a lipophilic radical initiator: synthesis, solution properties in water, and interactions with liposomes

1995 ◽  
Vol 73 (11) ◽  
pp. 2030-2040 ◽  
Author(s):  
Françoise M. Winnik ◽  
Alexander Adronov ◽  
Hiromi Kitano
Keyword(s):  
Polymeric Micelles ◽  
Polymer Concentration ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Solution Properties ◽  
Excimer Emission ◽  
Elastic Light Scattering ◽  
Critical Solution Temperature ◽  
Liposome Suspension ◽  
Hydrophobic Tail

Fluorescently labeled amphiphilic poly-(N-isopropylacrylamides) (PNIPAM) substituted with a N-[4-(1-pyrenyl)butyl]-N-n-octadecyl group at the chain end were prepared by free-radical polymerization in dioxane of N-isopropylacrylamide (NIPAM) using 4,4′-azobis{4-cyano-N,N-[4-(1-pyrenyl)butyl]-n-octadecyl}pentanamide as the initiator. The solution properties of the polymers in water were studied as a function of polymer concentration and temperature. Quasi-elastic light-scattering measurements and fluorescence experiments monitoring the pyrene excimer and pyrene monomer emissions revealed the presence of multimolecular polymeric micelles below the lower critical solution temperature (LCST) of PNIPAM. These underwent partial, reversible reorganization as they were heated above the LCST. The interactions of the pyrene-labeled amphiphilic PNIPAM with dimyristoylphosphatidylcholine (DMPC) liposomes have been examined in water at 25 °C. From fluorescence experiments it was established that the polymeric micelles are disrupted irreversibly upon contact with the liposomes. The anchoring of the polymer chains occurs by insertion of their hydrophobic tail within the phospholipidic bilayer, as evidenced from a large decrease of the pyrene excimer emission relative to pyrene monomer emission. The copolymers remained anchored within the bilayer as the temperature of the copolymer–liposome suspension was raised above the LCST of PNIPAM. Keywords: liposome, poly-(N-isopropylacrylamide), fluorescence, micelles.

scholarly journals Effects of the Hydrophilic–Lipophilic Balance of Alternating Peptides on Self-Assembly and Thermo-Responsive Behaviors

2019 ◽  
Vol 20 (18) ◽  
pp. 4604 ◽  
Author(s):  
Ihsan ◽  
Nargis ◽  
Koyama
Keyword(s):  
Aqueous Solutions ◽  
Self Assembly ◽  
Polymer Chains ◽  
Systematic Evaluation ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Hydrophilic Lipophilic Balance ◽  
Upper Critical Solution Temperature ◽  
Cloud Points ◽  
Micellization Behavior

A series of N-substituted poly(Gly–alter–Val) peptides were successfully synthesized for the systematic evaluation of the micellization behavior of alternating peptides. Three-component polymerization employing an aldehyde, a primary ammonium chloride, and potassium isocyanoacetate afforded four alternating peptides in excellent yields. We investigated the dependence of the hydrophilic–lipophilic balance of alternating peptides on the micellization behavior. All the aqueous solutions of alternating peptides exhibited upper critical solution temperature (UCST) behaviors, strongly indicating that the alternating binary pattern would mainly contribute to the UCST behaviors. The cloud points of alternating peptides shifted to higher temperatures as the side chains became more hydrophilic, which is opposite to the trend of typical surfactants. Such unusual micellization behaviors appeared to be dependent on the quasi-stable structure of single polymer chains formed in water.

scholarly journals Thermally responsive polymeric hydrogel brushes: synthesis, physical properties and use for the culture of chondrocytes

2006 ◽  
Vol 4 (12) ◽  
pp. 117-126 ◽  
Author(s):  
John Collett ◽  
Aileen Crawford ◽  
Paul V Hatton ◽  
Mark Geoghegan ◽  
Stephen Rimmer
Keyword(s):  
Crosslink Density ◽  
Cell Attachment ◽  
Viable Cell ◽  
Contact Angles ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Thermally Responsive ◽  
Isopropyl Acrylamide ◽  
Responsive Polymer

Hydrogel brushes are materials composed of a water-swollen network, which contains polymer chains that are grafted with another polymer. Using a thermally responsive polymer, poly( N -isopropyl acrylamide) (polyNIPAM), as the graft component we are able to maintain the critical solution temperature ( T crit ), independent of the overall composition of the material, at approximately 32°C. The change in swelling at T crit is a function of the amount of polyNIPAM in the system. However, there is a much smaller change in the surface contact angles at T crit . PolyNIPAM-based materials have generated considerable interest, as ‘smart’ substrates for the culture of cells and here, we show the utility of hydrogel brushes in cell culture. Chondrocytes attached to the hydrogel brushes and yielded viable cell cultures. Moreover, the chondrocytes could be released from the hydrogel brushes without the use of proteases by reducing the temperature of the cultures to below T crit to induce a change in the conformation of the polyNIPAM chain at T crit . The importance of the crosslink hydrogel component is illustrated by significant changes in cell attachment/cell viability as the crosslink density is changed.

scholarly journals Constrained thermoresponsive polymers – new insights into fundamentals and applications

2021 ◽  
Vol 17 ◽  
pp. 2123-2163
Author(s):  
Patricia Flemming ◽  
Alexander S Münch ◽  
Andreas Fery ◽  
Petra Uhlmann
Keyword(s):  
Phase Transition ◽  
Current Knowledge ◽  
Polymer Chains ◽  
Switching Behavior ◽  
Solution Temperature ◽  
Miscibility Gap ◽  
Underlying Structure ◽  
Thermoresponsive Polymers ◽  
Critical Solution Temperature ◽  
Stimuli Responsive Polymers

In the last decades, numerous stimuli-responsive polymers have been developed and investigated regarding their switching properties. In particular, thermoresponsive polymers, which form a miscibility gap with the ambient solvent with a lower or upper critical demixing point depending on the temperature, have been intensively studied in solution. For the application of such polymers in novel sensors, drug delivery systems or as multifunctional coatings, they typically have to be transferred into specific arrangements, such as micelles, polymer films or grafted nanoparticles. However, it turns out that the thermodynamic concept for the phase transition of free polymer chains fails, when thermoresponsive polymers are assembled into such sterically confined architectures. Whereas many published studies focus on synthetic aspects as well as individual applications of thermoresponsive polymers, the underlying structure–property relationships governing the thermoresponse of sterically constrained assemblies, are still poorly understood. Furthermore, the clear majority of publications deals with polymers that exhibit a lower critical solution temperature (LCST) behavior, with PNIPAAM as their main representative. In contrast, for polymer arrangements with an upper critical solution temperature (UCST), there is only limited knowledge about preparation, application and precise physical understanding of the phase transition. This review article provides an overview about the current knowledge of thermoresponsive polymers with limited mobility focusing on UCST behavior and the possibilities for influencing their thermoresponsive switching characteristics. It comprises star polymers, micelles as well as polymer chains grafted to flat substrates and particulate inorganic surfaces. The elaboration of the physicochemical interplay between the architecture of the polymer assembly and the resulting thermoresponsive switching behavior will be in the foreground of this consideration.

scholarly journals Upper Critical Solution Temperature (UCST) Behavior of Polystyrene-Based Polyampholytes in Aqueous Solution

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 265 ◽  
Author(s):  
Komol Kanta Sharker ◽  
Yuki Ohara ◽  
Yusuke Shigeta ◽  
Shinji Ozoe ◽  
Shin-ichi Yusa
Keyword(s):  
Pure Water ◽  
Polymer Concentration ◽  
Degree Of Polymerization ◽  
Solution Temperature ◽  
Sulfonate Group ◽  
Trimethylammonium Chloride ◽  
Critical Solution Temperature ◽  
Reversible Addition ◽  
Upper Critical Solution Temperature ◽  
Quaternary Ammonium Group

Strong polyampholytes comprising cationic vinylbenzyl trimethylammonium chloride (VBTAC) bearing a pendant quaternary ammonium group and anionic sodium p-styrenesulfonate (NaSS) bearing a pendant sulfonate group were prepared via reversible addition-fragmentation chain-transfer polymerization. The resultant polymers are labelled P(VBTAC/NaSS)n, where n indicates the degree of polymerization (n = 20 or 97). The percentage VBTAC content in P(VBTAC/NaSS)n is always about 50 mol%, as revealed by 1H NMR measurements, meaning that P(VBTAC/NaSS)n is a close to stoichiometrically charge-neutralized polymer. Although P(VBTAC/NaSS)n cannot dissolve in pure water at room temperature, the addition of NaCl or heating solubilizes the polymers. Furthermore, P(VBTAC/NaSS)n exhibits upper critical solution temperature (UCST) behavior in aqueous NaCl solutions. The UCST is shifted to higher temperatures by increasing the polymer concentration and molecular weight, and by decreasing the NaCl concentration. The UCST behavior was measured ranging the polymer concentrations from 0.5 to 5.0 g/L.

Anthracene functionalized thermosensitive and UV-crosslinkable polymeric micelles

2015 ◽  
Vol 6 (11) ◽  
pp. 2048-2053 ◽  
Author(s):  
Yang Shi ◽  
Renata M. Cardoso ◽  
Cornelus F. van Nostrum ◽  
Wim E. Hennink
Keyword(s):  
Aqueous Solution ◽  
Block Copolymer ◽  
Lower Critical Solution Temperature ◽  
Polymeric Micelles ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Uv Illumination ◽  
Uv Lamp

An anthracene-functionalized thermosensitive block copolymer was synthesized, which formed micelles by heating its aqueous solution above the lower critical solution temperature (LCST). The micelles were subsequently crosslinked by UV illumination at 365 nm with a normal handheld UV lamp.

scholarly journals Smart, Naturally-Derived Macromolecules for Controlled Drug Release

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1918
Author(s):  
Izabela Zaborniak ◽  
Angelika Macior ◽  
Paweł Chmielarz
Keyword(s):  
Smart Materials ◽  
Phase Transfer ◽  
Controlled Drug Release ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Hydrodynamic Diameter ◽  
Ph Responsive ◽  
Critical Solution Temperature ◽  
Vis Spectroscopy ◽  
Responsive Behavior

A series of troxerutin-based macromolecules with ten poly(acrylic acid) (PAA) or poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) homopolymer side chains were synthesized by a supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) approach. The prepared precisely-defined structures with low dispersity (Mw/Mn < 1.09 for PAA-based, and Mw/Mn < 1.71 for PDMAEMA-based macromolecules) exhibited pH-responsive behavior depending on the length of the polymer grafts. The properties of the received polyelectrolytes were investigated by dynamic light scattering (DLS) measurement to determine the hydrodynamic diameter and zeta potential upon pH changes. Additionally, PDMAEMA-based polymers showed thermoresponsive properties and exhibited phase transfer at a lower critical solution temperature (LCST). Thanks to polyelectrolyte characteristics, the prepared polymers were investigated as smart materials for controlled release of quercetin. The influence of the length of the polymer grafts for the quercetin release profile was examined by UV–VIS spectroscopy. The results suggest the strong correlation between the length of the polymer chains and the efficiency of active substance release, thus, the adjustment of the composition of the macromolecules characterized by branched architecture can precisely control the properties of smart delivery systems.

scholarly journals Upper or lower critical solution temperature, or both? Studies on cationic copolymers of N-isopropylacrylamide

2015 ◽  
Vol 6 (16) ◽  
pp. 3074-3082 ◽  
Author(s):  
Erno Karjalainen ◽  
Vladimir Aseyev ◽  
Heikki Tenhu
Keyword(s):  
Lower Critical Solution Temperature ◽  
Solution Temperature ◽  
Trimethylammonium Chloride ◽  
Solution Properties ◽  
Critical Solution Temperature ◽  
Isopropyl Acrylamide ◽  
Cationic Copolymers

The solution properties of statistical copolymers of N-isopropyl acrylamide (NIPAm) and cationic (3-acrylamidopropyl) trimethylammonium chloride (AMPTMA) have been studied.

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