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Wu, Xiao Yu; Lee, Ping I.

doi:10.1023/a:1018900114881

Cited by 52 publications

(29 citation statements)

References 11 publications

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“…As the temperature is raised above the phase transition temperature, these polymers shrink and the water content is reduced to » 20% [26]. Such dramatic decrease in hydration degree brings about marked change in various physicochemical properInteraction of PNIPAm/ MAA nanoparticles with proteins and cells 125 ties [25][26][27][28][29][30][31][32][33][34][35]. For example, greater than ten-fold reduction in the volume due to phase transition can be reached.…”

Section: Introductionmentioning

confidence: 99%

“…For example, greater than ten-fold reduction in the volume due to phase transition can be reached. This property has been utilized to design thermally regulated devices for biomedical applications [27,[29][30][31][32][33][34][35]. More recently, distinct alteration in interfacial properties associated with the phase transition of these polymers has been detected [35][36][37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%

“…PNIPAm /MAA nanoparticles, originally developed by Wu and Lee [27], exhibit pH-and temperature-dependent volume change in addition to the change in surface hydrophobicity [27,28,34,35,39,40]. Their volume phase transition temperature (T tr ) varies from 25 ± C to over 40 ± C and the volume can reduce ten times at the transition, depending upon the MAA content and pH [27,28,34,35].…”

Section: Introductionmentioning

confidence: 99%

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In vitro studies of the interaction of poly(NIPAm/MAA) nanoparticles with proteins and cells

Moselhy

Nicholov

et al. 2000

Journal of Biomaterials Science, Polymer Edition

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The pH- and temperature-responsive poly(N-isopropylacrylamide-co-methacrylic acid) (PNIPAm/MAA) nanoparticles are of potential application in targeted drug delivery. Their responsive properties in the presence of human serum albumin were investigated using dynamic light scattering (DLS), protein assay, and electron spin resonance (ESR) spectroscopy. Their interaction with human monocytes and polymorphonuclear leukocytes (PMNLs) was studied using scanning electron microscopy (SEM) and oxygen consumption method. The nanoparticles exhibited a volume phase transition at 35-40 degrees C in Hanks balanced salt solution (HBSS) and in phosphate buffer solution (PBS) of pH 7.4. The diameter of the nanoparticles decreased slightly in the presence of HSA at 25 degrees C at neutral pH, whereas an increase in the diameter in pH 6 PBS at 40 degrees C was revealed. The amount of albumin adsorbed onto the nanoparticles decreased with increasing temperature. The ESR spectra of spin labeled HSA indicated a more restricted environment in the nanoparticles at elevated temperatures. The stimulation of PMNL oxygen consumption by PNIPAm based nanoparticles, an indication of phagocytosis of the particles, was not observed regardless whether the nanoparticles were incubated in plasma or serum. In contrast, the more hydrophobic polystyrene (PSt) particles induced a significant increase in the rate of oxygen consumption after the incubation. PNIPAm/MAA-grafted-PSt particles behaved similarly to the PNIPAm/MAA nanoparticles, suggesting that surface properties dictate the recognition of colloids by PMNLs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In vitro studies of the interaction of poly(NIPAm/MAA) nanoparticles with proteins and cells

Moselhy

Nicholov

et al. 2000

Journal of Biomaterials Science, Polymer Edition

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“…[9][10][11][12] Poly(N-isopropylacrylamide), PNIPA, [13][14][15][16][17][18] is by far the beststudied and most prominent temperature responsive polymer. PNIPA exhibits a well defined lower critical solution temperature (LCST) in water at 32 o C around, below LCST the PNIPA are water soluble and above which they become water insoluble.…”

Section: Introductionmentioning

confidence: 99%

The effect of salt and pH on the phase transition behaviors of pH and temperature-responsive poly(N,N-diethylacrylamide-co-methylacrylic acid)

et al. 2008

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A series of pH and temperature-responsive (N,N-diethylacrylamide-co-methylacrylic acid) copolymers were synthesized by radical copolymerization and characterized by elemental analysis, Fourier-transform infrared (FT-IR), nuclear magnetic resonance (NMR)C and LLS. The effects of salt and pH on the phase transition behaviors of the copolymers were investigated by UV. With increasing NaCl concentration, significant salt effects on their phase transition behaviors were observed. UV spectroscopic studies showed that the phase transition became faster with increasing NaCl concentration. In addition, the phase transition behaviors of copolymers were sensitive to pH. The pH and temperature sensitivity of these copolymers would make an interesting drug delivery system.

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“…Grafting side-chains with different LCSTs on the NiPAM network resulted in hydrogels with multiple transition temperatures [22]. Gels containing charged groups, such as acrylic and methacrylic acids, exhibited transitions at elevated temperatures and underwent swelling that was dependent on ionic strength of the equilibrium buffer [15,[18][19][20]. Gels containing relatively hydrophobic monomers exhibited a transition temperature that was lower than the NiPAM LCST [21] and such gels had a higher elastic modulus due to association of hydrophobic monomers under aqueous conditions [16].…”

Section: Introductionmentioning

confidence: 99%

Hydrogels of Thermoreversible Comb‐Polymers Exhibit Increased Resistance for Dissolution

Jalil

Uludağ

2004

Materialwissenschaft Werkst

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The N-isopropylacrylamide (NiPAM) polymers exhibit thermoreversible properties in aqueous solutions. The resiliency of NiPAM hydrogels is believed to influence the outcome when the polymers are utilized in biomedical applications. To determine the influence of polymer architecture on hydrogel resiliency, polymers of Ni-PAM, methyl methacrylate (MMA) and acrylic acid were synthesized as random polymers and as comb polymers, where MMA was incorporated as side-chains. Random polymers exhibited a Lower Critical Solution Temperature (LCST) that decreased in proportion to MMA content in polymers. The LCST of comb polymers was not dependent on MMA content or the length of MMA side-chain (between 3.0 and 10.1 kD). Whereas low molecular weight ($100 kD) random polymers did not form intact gels, comb-polymers of equivalent molecular weight were capable of forming intact gels. Gel resiliency, as determined by propensity of hydrogels to dissolve upon cooling, was improved when the molecular weight of comb-polymers was increased but the length of the MMA sidebranch did not influence the gel resiliency. We conclude that hydrogel dissolution was dependent on polymer architecture as well as the polymer molecular weight.

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Cited by 52 publications

References 11 publications

In vitro studies of the interaction of poly(NIPAm/MAA) nanoparticles with proteins and cells

In vitro studies of the interaction of poly(NIPAm/MAA) nanoparticles with proteins and cells

The effect of salt and pH on the phase transition behaviors of pH and temperature-responsive poly(N,N-diethylacrylamide-co-methylacrylic acid)

Hydrogels of Thermoreversible Comb‐Polymers Exhibit Increased Resistance for Dissolution

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