Deswelling mechanism for comb-type grafted poly(N-isopropylacrylamide) hydrogels with rapid temperature responses

Kaneko, Yuzo; Nakamura, Satoki; Sakai, Kiyotaka; Kikuchi, Akihiko; Aoyagi, Takaaki; Sakurai, Yasuhisa; Okano, Teruo

doi:10.1016/s0966-7822(98)00022-7

Cited by 54 publications

(40 citation statements)

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“…Increasing the mechanical stability by introducing more hydrophobic domains (and thus lowering the LCST and EWC) resulted in a decrease in respiratory activity and no significant cell proliferation in PNS-7.7. This may be the result of limited diffusion owing to the hydrophobic skin effect [45,46]. These compromises can be alleviated by separating the functions of transition temperature and permeability into different polymer blocks as discussed by Yoshioka et al and Yasuda et al when rationalizing their PEG-grafted system [23][24][25][26] and demonstrated by the present PNS-g-NVP system.…”

Section: Discussionmentioning

confidence: 77%

Thermally reversible colloidal gels for three-dimensional chondrocyte culture

Lapworth

Hatton

Goodchild

et al. 2011

J. R. Soc. Interface.

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Healthy cells are required in large numbers to form a tissue-engineered construct and primary cells must therefore be increased in number in a process termed 'expansion'. There are significant problems with existing procedures, including cell injury and an associated loss of phenotype, but three-dimensional culture has been reported to offer a solution. Reversible gels, which allow for the recovery of cells after expansion would therefore have great value in the expansion of chondrocytes for tissue engineering applications, but they have received relatively little attention to date. In this study, we examined the synthesis and use of thermoresponsive polymers that form reversible three-dimensional gels for chondrocyte cell culture. A series of polymers comprising N-isopropylacrylamide (NIPAM) and styrene was synthesized before studying their thermoresponsive solution behaviour and gelation. A poly(NIPAM-co-styrene-graft-N-vinylpyrrolidone) variant was also synthesized in order to provide increased water content. Both random-and graft-copolymers formed particulate gels above the lower critical solution temperature and, on cooling, re-dissolved to allow enzyme-free cell recovery. Chondrocytes remained viable in all of these materials for 24 days, increased in number and produced collagen type II and glycosaminoglycans.

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Section: Discussionmentioning

confidence: 77%

Thermally reversible colloidal gels for three-dimensional chondrocyte culture

Lapworth

Hatton

Goodchild

et al. 2011

J. R. Soc. Interface.

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“…Several years ago, our laboratory reported the comb-type grafted PIPAAm hydrogel [40,41]. Poly(ethylene glycol) (PEG) chains were grafted into a PIPAAm cross-linked network by co-polymerization of IPAAm and PEG macromonomer, which has been prepared by the etherification reaction of alpha-hydroxy-omega-methoxy-PEG with acryloyl chloride.…”

Section: Poly(n-isopropylacrylamide) Co-grafted With Poly(ethylene Glmentioning

confidence: 99%

Temperature-Responsive Polymer Modified Surface for Cell Sheet Engineering

2012

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Abstract:In the past two decades, as a novel approach for tissue engineering, cell sheet engineering has been proposed by our laboratory. Poly(N-isopropylacrylamide) (PIPAAm), which is a well-known temperature-responsive polymer, has been grafted on tissue culture polystyrene (TCPS) surfaces through an electron beam irradiated polymerization. At 37 °C, where the PIPAAm modified surface is hydrophobic, cells can adhere, spread on the surface and grow to confluence. By decreasing temperature to 20 °C, since the surface turns to hydrophilic, cells can detach themselves from the surface spontaneously and form an intact cell sheet with extracellular matrix. For obtaining a temperature-induced cell attachment and detachment, it is necessary to immobilize an ultra thin PIPAAm layer on the TCPS surfaces. This review focuses on the characteristics of PIAPAm modified surfaces exhibiting these intelligent properties. In addition, PIPAAm modified surfaces giving a rapid cell-sheet recovery has been further developed on the basis of the characteristic of the PIPAAm surface. The designs of temperature-responsive polymer layer have provided an enormous potential to fabricate clinically applicable regenerative medicine.

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“…Poly(N-isopropylacrylamide) (PNIPAAm), the most popular thermo-sensitive, watersoluble polymer, exhibits a lower critical solution temperature (LCST) of almost 32 o C. PNIPAAm chains hydrate to form an expanded structure at temperatures lower than 32 o C, but undergo a sharp phase transition at higher temperatures to form inter-and intra-chain associations, resulting in precipitation. [15][16][17][18][19][20][21][22][23] Note that an injectable gel should solidify rapidly after injecting into the body, otherwise, the polymer solution may dissipate into the surrounding tissues or organs. 4 Comb-type grafted materials were introduced to improve the kinetic temperature sensitivity; thus rapid phase transition occurs as a result of the free mobility of the temperature sensitive polymer at the chain end.…”

Section: Introductionmentioning

confidence: 99%

“…4 Comb-type grafted materials were introduced to improve the kinetic temperature sensitivity; thus rapid phase transition occurs as a result of the free mobility of the temperature sensitive polymer at the chain end. 21,22 Our previous studies revealed that the PNIPAAm comb-type grafted alginate hydrogels showed a rapid swelling and shrinking behavior. [24][25][26] Hyaluronic acid (HA) consists of 2-acetamide-2-deoxy-α-D-glucose and β-D-glucuronic acid residues linked by alternate (1-3) and (1-4) glycoside bonds.…”

Section: Introductionmentioning

confidence: 99%

Preparation of thermo-responsive and injectable hydrogels based on hyaluronic acid and poly(N-isopropylacrylamide) and their drug release behaviors

et al. 2006

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Copolymers composed of hyaluronic acid (HA) and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to create temperature-sensitive injectable gels for use in controlled drug delivery applications. Semi-telechelic PNIPAAm, with amino groups at the end of each main chain, was synthesized by radical polymerization using 2-aminoethanethiol hydrochloride (AESH) as the chain transfer agent, and was then grafted onto the carboxyl groups of HA using carbodiimide chemistry. The result of the thermo-optical analysis revealed that the phase transition of the PNIPAAm-grafted HA solution occurred at around 30~33 o C. As the graft yield of PNIPAAm onto the HA backbone increased, the HA-g-PNIPAAm copolymer solution exhibited sharper phase transition. The short chain PNIPAAm-grafted HA (M w = 6,100) showed a narrower temperature range for optical turbidity changes than the long chain PNIPAAm-grafted HA (M w = 13,100). PNIPAAm-grafted HA exhibited an increase in viscosity above 35 o C, thus allowing the gels to maintain their shape for 24 h after in vivo administration. From the in vitro riboflavin release study, the HA-g-PNIPAAm gel showed a more sustained release behavior when the grafting yield of PNIPAAm onto the HA backbone was increased. In addition, BSA released from the PNIPAAm-g-HA gels showed a maximum concentration in the blood 12 h after being injected into the dorsal surface of a rabbit, followed by a sustained release profile after 60 h.

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Deswelling mechanism for comb-type grafted poly(N-isopropylacrylamide) hydrogels with rapid temperature responses

Cited by 54 publications

References 0 publications

Thermally reversible colloidal gels for three-dimensional chondrocyte culture

Thermally reversible colloidal gels for three-dimensional chondrocyte culture

Temperature-Responsive Polymer Modified Surface for Cell Sheet Engineering

Preparation of thermo-responsive and injectable hydrogels based on hyaluronic acid and poly(N-isopropylacrylamide) and their drug release behaviors

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