Temperature-responsive shrinking kinetics of poly (N-isopropylacrylamide) copolymer gels with hydrophilic and hydrophobic comonomers

Kaneko, Yuzo; Yoshida, Ryo; Sakai, Kiyotaka; Sakurai, Yasuhisa; Okano, Teruo

doi:10.1016/0376-7388(94)00268-4

Cited by 156 publications

(126 citation statements)

References 21 publications

Supporting

Mentioning

115

Contrasting

Order By: Relevance

“…As the best known member in the thermo-sensitive polymer family, PNIPAAm and its copolymers have been used successfully in the stimuli-responsive release of many medicines such as sodium salicylate, indomethacin, 4-acetamidophenol sigmaultra and ranitidine HCl (Bae et al 1991a;Kaneko et al 1995;Lue et al 2007). In the present study, the thermo-sensitive copolymer PNIPAAmco-BMA was introduced into seed pelleting.…”

Section: Discussionmentioning

confidence: 99%

“…The samples of media (1 ml) were withdrawn every half hour and replaced with the same amount of water. Finally, the concentration of SA was measured from the absorbance at 296.4 nm by UV spectrophotometer (UV-2450, Shimadzu, Japan) and the released amount of SA from the hydrogel was determined (Kaneko et al 1995).…”

Section: Synthesis Of the Pnipaam-co-bma Hydrogelmentioning

confidence: 99%

“…The 'skin layer' pattern, the main controlled drug delivery pattern of PNIPAAm and its copolymers, has been intensively studied for temperature controlled 'on-off' regulation of entrapped drug release (Kaneko et al 1995). At temperatures below the LCST, PNIPAAm or its copolymer is in the state 'on', and the entrapped drugs are released by the diffusion mechanism.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

“Intelligent” seed pellets may improve chilling tolerance in tobacco

Cui

Guan

et al. 2012

Frontiers in Life Science

View full text Add to dashboard Cite

Tobacco seeds and seedlings often encounter low temperature stress in China. An 'intelligent' tobacco seed pellet was developed to improve chilling tolerance by adding thermo-sensitive PNIPAAm-co-BMA (poly(N -isopropylacrylamide-cobutyl methacrylate)) hydrogel. PNIPAAm-co-BMA can detect changes in environmental temperature and change its reticular structure accordingly. In addition, the release rate of salicylic acid (SA) loaded in PNIPAAm-co-BMA hydrogel is changed. Tobacco seeds of two different chilling-tolerant tobacco varieties were pelleted by SA-loaded PNIPAAm-co-BMA, and then the germination characteristics, seedling quality and some physiological parameters of the seeds and seedlings were measured after a chilling stress at 11 • C for 5 d. The results showed that the germination percentage (GP), germination index (GI), root length, seedling dry weight and the activities of POD (peroxidase) were significantly increased and the concentration of MDA (malondialdehyde) was significantly decreased in the 'intelligent' seed pellets compared with the seeds without SA and PNIPAAm-co-BMA in both varieties. The results showed that the 'intelligent' seed pellets had thermo-sensitive traits; they enhanced and prolonged the efficiency and acting time of loaded SA. This indicated that the 'intelligent' seed pellets pelleted with SA-loaded PNIPAAm-co-BMA could be used to improve chilling tolerance.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Synthesis Of the Pnipaam-co-bma Hydrogelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

“Intelligent” seed pellets may improve chilling tolerance in tobacco

Cui

Guan

et al. 2012

Frontiers in Life Science

View full text Add to dashboard Cite

show abstract

“…Because of this unique thermal property, PNIPA has been applied widely. For example, PNIPAcontaining gel has been studied extensively for a new drug delivery system [5]. Immobilization of enzymes by PNIPA is another attractive field because its reactivity and solubility can be controlled easily by a slight change of temperature [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Surface Modification of Pigments with Temperature-Responsive Polymer Grafted by Plasma-Induced Polymerization.

Ihara

Yukioka

Iriyama

1998

J. Photopol. Sci. Technol.

View full text Add to dashboard Cite

In order to develop temperature-responsive dispersing systems, we have grafted poly(N-isopropylacrylamide) (PNIPA), which is a temperature-responsive polymer having a lower critical solution temperature (LCST) at 32 °C, onto carbon black (CB) by plasmainduced graft polymerization technique. CB was treated with HO and/or 02 plasma, to which aqueous solution of the monomer (NIPA) was introduced, resulted in simultaneous graft polymerization. The dispersibility of the PNIPA-grafted CB in water at 25 and 35 °C was investigated by the measurement of the transmittance of visible light (500 nm). The most of the PNIPA-grafted CB showed better dispersibility at 25 °C (below the LCST) than at 35 °C (above the LCST). In many graft polymerization conditions, CB grafted in 2 wt% of the monomer concentration with ultrasonic irradiation at room temperature showed the most clear temperature response of the dispersibility in water.

show abstract

“…8,9 On the other hand, substitution to acrylamide increases the hydrophilicity of the polymer and heightens LCST. 10 The temperature-responsive polymers presently available, except for PNIPAAm, require a large temperature shift for complete precipitation. A rational procedure not only for controlling LCST of polymers, but also for making the temperature shift for precipitation small, should thus be developed.…”

mentioning

confidence: 99%

Control of the Solubility Transition in Novel Temperature-Responsive Linear Polymers Comprising α-Amino Acid Diamide Derivatives

2000

View full text Add to dashboard Cite

The present study was designed so as to control the temperature with the solubility change of temperature-responsive linear polymers through a modification of the hydrogen bonding of residues linked to the hydrocarbon backbones of polymers. Poly(N-isopropylacrylamide) (PNIPAAm), a well-known temperature-responsive polymer, 1 dissolves in water at below 32˚C and precipitates at over 32˚C. This polymer may be considered to be a pseudopeptide with numerous Nisopropylamide moieties grafted onto the backbone of the alkyl chain and, accordingly, the transition is similar to the thermal denaturation of peptides, the only difference being that the solubility change of the polymer is reversible. This transition, whose temperature is called the lower critical solution temperature (LCST), occurs when the hydrogen bonds between the amide units in the polymer and bulk water are cleaved at temperatures exceeding LCST. A desolvation of the polymer chains results in their aggregation with each other and eventual precipitation in water.Because the aggregation and extension of PNIPAAm related to the water solubility is reversible, the polymer is useful for drug delivery systems, 2,3 a scaffold in cell culturing, 4 thermoresponsive separation in solid extraction 5 and chromatography. 6,7 The regulation of LCSTs of temperature-responsive polymers must be desired for these applications. The most general approaches to LCST control are the co-polymerization of Nisopropylacrylamide with various monomers. Substitution of the N-isopropylamide moieties to butyl ester increases the hydrophobicity of the polymer and lowers LCST. 8,9 On the other hand, substitution to acrylamide increases the hydrophilicity of the polymer and heightens LCST. 10 The temperature-responsive polymers presently available, except for PNIPAAm, require a large temperature shift for complete precipitation. A rational procedure not only for controlling LCST of polymers, but also for making the temperature shift for precipitation small, should thus be developed.In this study, novel vinyl group-terminated monomers having amino acid diamide moieties were prepared, and an examination was made to determine how LCST changes by the Nmethylation of two different amide units and the changes in the α-substituents of the amino amide derivatives.N-Acryloylated L-amino amide monomers were prepared from L-alanine and L-valine both possessing the least hydrophobicity of all natural and chiral amino acids. Substitution of the two amide units in N-terminal amide and C-terminal amide with the N-methyl group should make possible regulation of LCST of polymers derived from L-alanine and L-valine. Either Nmethylation renders an amide hydrogen bond donor. Such chemical substitution significantly reduces the polymer capacity to form hydrogen bonds with the bulk aqueous phase or interresiduary hydrogen bonds, with consequent chain aggregation. A hydrophobic environment shielded from a bulk aqueous solution is thus produced. The inclusion and release of pharmaceuticals for drug delivery syste...

show abstract

Temperature-responsive shrinking kinetics of poly (N-isopropylacrylamide) copolymer gels with hydrophilic and hydrophobic comonomers

Cited by 156 publications

References 21 publications

“Intelligent” seed pellets may improve chilling tolerance in tobacco

“Intelligent” seed pellets may improve chilling tolerance in tobacco

Surface Modification of Pigments with Temperature-Responsive Polymer Grafted by Plasma-Induced Polymerization.

Control of the Solubility Transition in Novel Temperature-Responsive Linear Polymers Comprising α-Amino Acid Diamide Derivatives

Contact Info

Product

Resources

About