Critical Kinetics of Volume Phase Transition of Gels

Tanaka, Toyoichi; Sato, Eriko; Hirokawa, Yoshitsugu; Hirotsu, Shunsuke; Peetermans, Joyce

doi:10.1103/physrevlett.55.2455

Cited by 339 publications

(250 citation statements)

References 8 publications

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“…The characteristic time correlates well with a power law of the form (solid line). (3) is similar to correlations reported by other researchers [24][25][26] for unconstrained expansion of the gel. In the case of a freely expanding gel, however, the characteristic time varies with the square of the initial volume, i.e.,…”

Section: Valve Characterizationsupporting

confidence: 90%

“…The potential ability of hydrogels to control the transport of fluids was also recognized. However, because of their slow response, Wang, J., Chen, Z., Mauk, M., Hong, K-S, Li, M., Yang, S., and Bau, H., H., 2005, Self-Actuated, ThermoResponsive Hydrogel Valves for Lab on a Chip, Biomedical Microdevices 7 (4), 313-322. which is proportional to the square of the gel's characteristic dimension [24][25][26], hydrogels were not used for valve construction until the appearance of microfluidic systems.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Self-Actuated, Thermo-Responsive Hydrogel Valves for Lab on a Chip

Wang

Chen

Mauk

et al. 2005

Biomed Microdevices

147

108

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An easy to fabricate, thermally-actuated, self-regulated hydrogel valve for flow control in pneumatically driven, microfluidic systems is described. This microvalve takes advantage of the properties of the hydrogel, poly(Nisopropylacrylamide), as well as the aqueous fluid itself to realize flow control. The valve was designed for use in a diagnostic system fabricated with polycarbonate and aimed at the detection of pathogens in oral fluids at the location of the sample collection. The paper describes the construction and characterization of the hydrogel valves and their application for flow control, sample and reagent metering, sample distribution into multiple analysis paths, and the sealing of a polymerase chain reaction (PCR) reactor to suppress bubble formation. The hydrogel-based flow control is electronically addressable, does not require any moving parts, introduces minimal dead volume, is leakage and contaminant free, and is biocompatible. KeywordsMicrovalve, microfluidics, hydrogel, lab-on-a-chip, metering, distribution, PCR Wang, J., Chen, Z., Mauk, M., Hong, K-S, Li, M., Yang, S., and Bau, H., H Wang, J., Chen, Z., Mauk, M., Hong, K-S, Li, M., Yang, S., and Bau, H., H., 2005, Self-Actuated, ThermoResponsive Hydrogel Valves for Lab on a Chip, Biomedical Microdevices 7 (4), 313-322.., 2005, Self-Actuated, Thermo-Responsive Hydrogel Valves for Lab on a Chip, Biomedical Microdevices 7 (4), 313-322. ABSTRACTAn easy to fabricate, thermally-actuated, self-regulated hydrogel valve for flow control in pneumatically driven, microfluidic systems is described. This microvalve takes advantage of the properties of the hydrogel, poly(N-isopropylacrylamide), as well as the aqueous fluid itself to realize flow control. The valve was designed for use in a diagnostic system fabricated with polycarbonate and aimed at the detection of pathogens in oral fluids at the location of the sample collection. The paper describes the construction and characterization of the hydrogel valves and their application for flow control, sample and reagent metering, sample distribution into multiple analysis paths, and the sealing of a polymerase chain reaction (PCR) reactor to suppress bubble formation. The hydrogel-based flow control is electronically addressable, does not require any moving parts, introduces minimal dead volume, is leakage and contaminant free, and is biocompatible.

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Section: Valve Characterizationsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Self-Actuated, Thermo-Responsive Hydrogel Valves for Lab on a Chip

Wang

Chen

Mauk

et al. 2005

Biomed Microdevices

147

108

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“…It is known that the liquid-solid phase transition is derived from the coil-globule transition of the PNIPAM chains in water at the LCST. Given end-group with higher hydrophobicity, PNIPAM formed aggregates below its LCST, which prompted a transition to occur into the insoluble globuleform at the lower temperature [6,51,52]. Indeed, PNIPAM aggregates have been demonstrated in the cold aqueous solutions of alkyl and aryl modified PNIPAM as reported by Duan et al [16] and Huh et al [50], respectively.…”

Section: Thermoresponsivity Of Pnipams Before and After Click Reactionmentioning

confidence: 78%

Well-defined poly(N-isopropylacrylamide) with a bifunctional end-group: synthesis, characterization, and thermoresponsive properties

Liu

Liao

Yang

et al. 2012

Designed Monomers and Polymers

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(2013) Well-defined poly(N-isopropylacrylamide) with a bifunctional end-group: synthesis, characterization, and thermoresponsive properties, Designed Monomers and Polymers, 16:5, 465-474, DOI: 10.1080/15685551.2012 In this study, well-defined poly(N-isopropylacrylamide) (PNIPAM) with a bisalkyne end-group was synthesized by reversible addition-fragmentation chain transfer polymerization using 2-(2-(ethylthiocarbonothioylthio)-2-methylpropanoyl-oxy)ethyl 3,5-bis(prop-2-ynyloxy) benzoate (EMEB) as the chain transfer agent. The molecular weight and polydispersity index of polymer was determined by gel permeation chromatography (GPC). The linear increase in molecular weight with conversion, unimodal, and almost symmetrical peak in GPC trace together with low polydispersity indicated the controlled polymerization process of NIPAM mediated by EMEB. Subsequently, the Cu(I)-catalyzed [3 + 2] Huisgen cycloaddition between the end-group of polymer and azide derivatives was carried out to produce PNIPAM, in which the bisfunctional end-group was modified with phenyl, octyl, amido, and hydroxyl groups. After completing the click reaction, the structure of the polymer was characterized carefully by Fourier transform infrared spectroscopy (FTIR), 1 H NMR, and Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), indicating the complete consumption of alkyne end-groups. In addition, almost no change in molecular weight as well as the polydispersity was observed by comparison with the GPC traces of polymers before and after click reaction. The cloud point temperatures (T cp s) of the resulting PNIPAM derivatives in aqueous solution were investigated in detail by dynamic light scattering. The results showed that the values of T cp were ranged from 22 to 38°C, which depended largely on end-groups as well as the polymer molecular weights.

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“…(13) Crosslinked PNIPAAm hydrogels reversibly change from a water-swollen state to a shrunken (deswollen) state by exuding water when heated above their VPTT of ~35°C. (14)(15)(16)(17) As a result, both covalently grafted PNIPAAm chains and PNIPAAm hydrogels display a pronounced increase in surface hydrophobicity when heated above their LCST or VPTT, respectively. (9) Thus, the thermal modulation of both PNIPAAm-grafted surfaces and PNIPAAm hydrogels has been used to induce the release of cells.…”

Section: Introductionmentioning

confidence: 99%

Micropatterning of Poly (N-isopropylacrylamide) (PNIPAAm) Hydrogels: Effects on Thermosensitivity and Cell Release Behavior

Hou¹,

Hou²,

Grunlan³

et al. 2010

Sensors and Materials

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Materials, Vol. 22, No. 3 (2010) The thermally driven, reversible change in the surface properties of poly (N-isopropylacrylamide) (PNIPAAm) hydrogels from a hydrophilic (water-swollen) state to a hydrophobic (deswollen) state when heated above the volume phase transition temperature (VPTT, ~35°C) makes them useful in inducing controlled cell release. To improve the kinetics of swelling and deswelling, we have prepared microstructured (i.e., micropillared) thermoresponsive surfaces comprising pure PNIPAAm hydrogel and nanocomposite PNIPAAm hydrogel embedded with polysiloxane colloidal nanoparticles (~220 nm diameter, 1 wt%) via photopolymerization. The thermosensitivity (i.e., degree and rate of swelling/deswelling) of these surfaces and how it can be regulated using different micropillar sizes and densities were characterized by measuring the dynamic size changes in micropillar dimensions in response to thermal activation. Our results show that the dynamic thermal response rate can be increased by more than twofold when the micropillar size is reduced from 200 to 100 µ m. The temperature-controlled cell release behaviors of pure PNIPAAm and nanocomposite PNIPAAm micropatterned surfaces were successfully characterized using mesenchymal progenitor cells (10T½). This study demonstrates that the thermosensitivity of PNIPAAm surfaces can be regulated by introducing micropillars of different sizes and densities, while maintaining good temperature-controlled cell release behavior.

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Critical Kinetics of Volume Phase Transition of Gels

Cited by 339 publications

References 8 publications

Self-Actuated, Thermo-Responsive Hydrogel Valves for Lab on a Chip

Self-Actuated, Thermo-Responsive Hydrogel Valves for Lab on a Chip

Well-defined poly(N-isopropylacrylamide) with a bifunctional end-group: synthesis, characterization, and thermoresponsive properties

Micropatterning of Poly (N-isopropylacrylamide) (PNIPAAm) Hydrogels: Effects on Thermosensitivity and Cell Release Behavior

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