Functional copolymers of N-isopropylacrylamide for bioengineering applications

Rzaev, Zakır M. O.; Dinçer, Sevil; Pi̇şki̇n, Erhan

doi:10.1016/j.progpolymsci.2007.01.006

Cited by 496 publications

(334 citation statements)

References 369 publications

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“…As one of the most widely used injectable hydrogels, PNIPAAm is a thermosensitive intelligent material which undergoes a reversible sol-gel transition around 32°C in an aqueous condition, converting from flowable solution to hydrogel when heated above its lower critical solution temperature (LCST). 25 LCST is decided by the hydrophilicity of the polymer chain and can be altered by copolymerizing with other monomers. 26 These characteristics of tunable fast phase transition and low cytotoxicity make PNIPAAm and its copolymers appropriate materials to be applied in cell encapsulating and proliferation, despite the disadvantage of nonbiodegradability in the body.…”

Section: Introductionmentioning

confidence: 99%

Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

Lian

Xiao²,

Bian³

et al. 2012

IJN

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A series of biodegradable thermosensitive copolymers was synthesized by free radical polymerization with N-isopropylacrylamide (NIPAAm), acrylic acid (AAc) and macromer 2-hydroxylethyl methacrylate-poly(ε-caprolactone) (HEMAPCL). The structure and composition of the obtained terpolymers were confirmed by proton nuclear magnetic resonance spectroscopy, while their molecular weight was measured using gel permeation chromatography. The copolymers were dissolved in phosphate-buffered saline (PBS) solution (pH = 7.4) with different concentrations to prepare hydrogels. The lower critical solution temperature (LCST), cloud point, and rheological property of the hydrogels were determined by differential scanning calorimetry, ultraviolet-visible spectrometry, and rotational rheometry, respectively. It was found that LCST of the hydrogel increased significantly with the increasing NIPAAm content, and hydrogel with higher AAc/HEMAPCL ratio exhibited better storage modulus, water content, and injectability. The hydrogels were formed by maintaining the copolymer solution at 37°C. The degradation experiment on the formed hydrogels was conducted in PBS solution for 2 weeks and demonstrated a less than 20% weight loss. Scanning electron microscopy was also used to study the morphology of the hydrogel. The copolymer with NIPAAm/AAc/HEMAPCL ratio of 88:9.6:2.4 was bioconjugated with type I collagen for the purpose of biocompatibility enhancement. In-vitro cytotoxicity of the hydrogels both with and without collagen was also addressed.

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Section: Introductionmentioning

confidence: 99%

Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

Lian

Xiao²,

Bian³

et al. 2012

IJN

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“…[1][2][3][4] In aqueous solutions it undergoes a reversible coil-globule transition at temperature of ca. 32°C, and upon heating beyond this temperature, the changes in the PNIPAM chain conformation occur in a sharp manner, within a few degrees.…”

Section: Introductionmentioning

confidence: 99%

Direct Imaging of Nanoscopic Plastic Deformation below Bulk T_g and Chain Stretching in Temperature-Responsive Block Copolymer Hydrogels by Cryo-TEM

Nykänen¹,

Nuopponen

Hiekkataipale³

et al. 2008

Macromolecules

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This work describes the thermoresponsive transition in polystyrene-block-poly(N-isopropylacrylamide)-block-polystyrene (PS-block-PNIPAM-block-PS) triblock copolymer hydrogels, as observed by both direct and reciprocal space in-situ characterization. The hydrogel morphology was studied in both the dry and wet state, at temperatures below and beyond the coil-globule transition of PNIPAM, using vitrified ice cryotransmission electron microscopy (cryo-TEM), in-situ freeze-drying technique, and small-angle X-ray scattering (SAXS). The selected PS-block-PNIPAM-block-PS triblock copolymers were intentionally designed in such a molecular architecture to self-assemble into spherical and bicontinuous morphology with the poly(N-isopropylacrylamide) forming the continuous matrix. The phase behavior in bulk was directly investigated by SAXS as a function of temperature, while free-standing polymer thin films of samples quenched from different temperatures, allowed observing by cryo-TEM the changes in hydrogel microstructure. Finally, sublimation of water via controlled freeze-drying in the TEM column allowed studying systems without the presence of vitrified water, which enables direct imaging of the densely connected physically cross-linked polymer network. By combining these techniques on samples exhibiting both spherical and gyroidal morphologies, it was demonstrated that (i) PNIPAM form physically connected networks in spherical structures and bicontinuous morphologies in the gyroidal phase, (ii) in PNIPAM chains strands are strongly stretched above the polymer coil-to-globule transition, and (iii) surprisingly, upon the gel swelling process, the PS domains undergo extensive plastic deformation although temperature is always maintained well below the PS glass transition bulk temperature. The possible physical mechanisms responsible for this plastic deformation can be understood in terms of the dependence of PS glass transition temperature on the size of nanometer-scaled domains.

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“…[1][2][3][4][5][6][7][8] They exhibit structural and property changes to external changes such as pH, temperature, and light. The increasing demand for "smartness" in biomedical and material devices has generated an increasing interest for synthetic polymers that can serve as an ideal platform for locating stimuli-responsive molecular elements.…”

Section: Introductionmentioning

confidence: 99%

Well-Defined Thermoresponsive Copolymers with Tunable LCST and UCST in Water

Jung¹,

Lee²

2014

Bulletin of the Korean Chemical Society

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A thermoresponsive polymer, poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), was successfully synthesized by atom transfer radical polymerization (ATRP). Different amounts of 1,3-propanesultone were used as quaternization agent to transit the PDMAEMA into partially modified poly(zwitterions), resulting in p[DMAEMA-co-3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate] (PDMAEMA-co-PDMAPS). Molecular weight, molecular weight distribution, and degree of quarternization were determined by gel permeation chromatography (GPC) and 1 H NMR spectroscopy. The transmission spectra of the 1.0 wt % aqueous solutions of the resulting polymers at 650 nm were measured as a function of temperature. Results showed that the lower critical solution temperature (LCST) and the upper critical solution temperature (UCST) could be easily controlled by the different composition of dimethylamino and zwitterion groups. The effect of partial quaternization on thermoresponsive properties was also studied by dynamic light scattering (DLS) with the same aqueous concentration (1.0 wt %) as employed for turbidimetry studies. The LCST and UCST values measured by DLS correlated well with those determined by turbidimetry.

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Functional copolymers of N-isopropylacrylamide for bioengineering applications

Cited by 496 publications

References 369 publications

Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

Direct Imaging of Nanoscopic Plastic Deformation below Bulk T_g and Chain Stretching in Temperature-Responsive Block Copolymer Hydrogels by Cryo-TEM

Well-Defined Thermoresponsive Copolymers with Tunable LCST and UCST in Water

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Functional copolymers of N-isopropylacrylamide for bioengineering applications

Cited by 496 publications

References 369 publications

Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

Direct Imaging of Nanoscopic Plastic Deformation below Bulk Tg and Chain Stretching in Temperature-Responsive Block Copolymer Hydrogels by Cryo-TEM

Well-Defined Thermoresponsive Copolymers with Tunable LCST and UCST in Water

Contact Info

Product

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About

Direct Imaging of Nanoscopic Plastic Deformation below Bulk T_g and Chain Stretching in Temperature-Responsive Block Copolymer Hydrogels by Cryo-TEM