Thermo-responsive polymers

Cammas, S., Suzuki, K., Sone, Y, Sakurai, Y., Kataoka, K., and Okano, T. Thermo-responsive polymer nanoparticles with a core-shell micelle structure as site-specific drug carriers. J. Contr. Rel, 1997,48, 157-164. 

Au NPs protected with a thermo-responsive polymer such as PNIPAM by the covalent grafting to technique with different end-functional PNIPAMs and various ratios between PNIPAM and HAuC14 has been studied. PNIPAM samples were synthesized through either conventional radical polymerization or living/controlled radical polymerization. With this approach, very small and quite monodisperse Au NPs are obtained with diameters ranging from 1.5 to 2.3 nm [94]. 

Poly(7V-isopropylacrylamide) (PNlPAAm) is a well-known thermo-responsive polymer and exhibits a lower critical solution temperature (LCST) of 32°C in water. It assnmes a random coil structure (hydrophilic state) below the LCST and a collapsed globnlar stractnre (hydrophobic state) above. Because of this sharp reversible transition, this polymer finds a vast array of applications,... 

The reversible solubility changes of thermo-responsive polymers are due to small temperature alterations. The aqueous solutions of these polymers exhibit a critical solution temperature at which the solubility phase of the polymer is changed. Thermo-responsive polymers that are soluble in water above a certain temperature and insoluble below it exhibit upper critical solution temperature behaviour. On the... 

M. Prabaharan, J.F. Mano, Stimuli-responsive hydrogels based on polysaccharides incwporaled with thermo-responsive polymers as novel biomalerials, Macromol. Biosci. 6 (12) (2006) 991—1008. 

Sosnik, A. Cohn, D. (2004) Ethoxysilane-capped PEO-PPO-PEO triblocks a new family of reverse thermo-responsive polymers. Biomaterials, 25, 2851-2858. 

Thermo-responsive polymers have been used to release encapsulated drugs in response to temperature changes. These polymers typically undergo a rapid and reversible hydration-dehydration at lower critical solution temperature (LCST, from soluble to insoluble) or upper critical solution temperature (UCST, from insoluble to soluble) upon heating. [71] For example, a thermo-responsive polymer, poly (2-isopropyl- 2-oxazoline) (PiPrOx), was conjugated to pH-responsive poly(benzyl ether)dendrons, which exhibited sharp thermal transitions as well as pH-dependent behaviors (Fig. 4a).[105]... 

One of the more recently developed material classes is that of thermo-responsive polymers. This accounts mainly for those polymers showing a so-called lower critical solution temperature (LOST) or - to a much less extent - an upper critical solution temperature (UCST), meaning polymers that change their solution status significantly upon temperature changes. In general, this behaviour is the result of a delicate balance of hydrophilic and hydrophobic groups in the polymer. The major... 

SIB Siband, E., Tran, Y., and Hourdet, D., pH- and thermo-responsive polymer assemblies in aqueous solution, Progr. Colloid Polym. Sci., 137, 19, 2010. 

TIA Tian, H.-Y., Yan, J.-J., Wang, D., Gu, C., You, Y.-Z., and Chen, X.-S., Synthesis of thermo-responsive polymers with both tunable UCST and LCST, Macromol. Rapid Commun., 32, 660, 2011. 

We hope that this brief review has given the reader a general feeling of the development and application of CE in the separation of nucleic acids. With the advent of capillary array electrophoresis and microchip electrophoresis, as well as remarkable improvements in separation matrices, CE has become a standardized and cost-effective technique in the separation of nucleic acids. Novel thermo-responsive polymer solutions combine the merits of different monomers, and offer the possibility to fine-tune the desirable properties of polymer molecular architecture and chemical composition. Artificial entropic trapping systems obviate the use of viscous polymer solutions, and even offer fast, unattended, miniaturized, and multiplexed platforms. Optimizing the geometry of these electrophoretic systems to both increase the separation and reduce the diffusion (band broadening) is the main topic for future research. 

Prabhakaran M, Mano JF (2006) Stmuli-responsive hydrogels based on polysaccharides incorporated with thermo-responsive polymers as novel biomataials. Macromol Biosci 8 991-1008... 

A very intriguing development concerns a drug delivery system for the treatment of periodontitis. It consists of two components. The first is a clay product loaded with tetracycline. The clay product is coated with chitosan to retard drug release. The second component is a thermo-responsive polymer mixed with polyethylene glycol that is syringable at room temperature but solidifies upon warming up to body temperature. The solidified polymer remains 60 min in situ. After that time, it still inhibits the formation of bacterial colonies, and still contains much more of the antibiotic than the control containing no chitosan. 

FIGURE 12.12 Schematic of mouse embryonic stem cells (mESC) attachment (above LCST) and detachment (below LCST) to/from thermo-responsive polymer substrates. Poly(ME02MA-co-OEGMA) polymer brushes are shown as chain extended at temperatures below the LCST forming a cell-resistant surface, whereas collapse of the bmshes above the LCST results in a more favorable surface for cell attachment [192]. 

Jonas, A. M. GUnel, K. Oren, R. Nysten, B. Huck, W. T. S. Thermo-responsive polymer brushes with tunable collapse temperatures in the physiological range. Macromolecules 2007,40, 4403 1405. 

Dey, S. Kellam, B. Alexander, M. R. Alexander, C. Rose, F. Enzyme-passage free culture of mouse embryonic stem cells on thermo-responsive polymer surfaces. J. Mater Chem. 2011, 21, 6883-6890. 

Ito, Y., Nogawa, N., and Yoshida, R. (2003) Temperature control of the Belousov-Zhabotinsky reaction using a thermo-responsive polymer. Lang/nuir, 19, 9577-9579. 

It would be of interest to add some functionalities such as properties in response to changes in pH, temperature, electrical potential and so on as well as hydrophilic properties to PTFE surfaces by the combined technique just described. Poly(AT-isopropylaoylamide) (PNIPA ) is a well-known thermo-responsive polymer whose hydrogel undergoes a volume change around 31 C in an aqueous solution. And further, poly 2-(dimethylamino)ethyl methacrylate (PDMA) in a pH 10 buffer solution exhibits a drastic decrease in the transmittance around 28 °C, which is considered to come from a phase transition of PDMA chains (ii). Therefore, we have tried to prepare JV -isopropylacrylamide (NIPAAm) or 2-(dimethylamino)ethyl... 

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