pH‐Responsive Microrods Produced by Electric‐Field‐Induced Aggregation of Colloidal Particles

Snoswell, David R. E.; Brill, Robert K.; Vincent, Brian

doi:10.1002/adma.200601824

Cited by 20 publications

(21 citation statements)

References 30 publications

(29 reference statements)

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“…32 °C in water, has been well-established from the precipitation polymerization. [2][3][4][5][6][7][8][9][10] At the end of polymerization at a high temperature (70.0 °C) above the LCST of poly(NIPAM), the opalescent color was observed in the dispersion of the template microgels (Fig. 2a).…”

Section: Microgels Synthesismentioning

confidence: 99%

“…25,41,42 The deteriorative polymer-solvent affinity favors the gel shrinking. [6][7][8][9][10][11][12][13][14][15][16] Since the reaction is reversible, the microgels should be able to return to the initial status if ammonia is removed. Indeed, recycling experiments of adding/removing ammonia revealed the robustness of the ARM microgels.…”

Section: Volume Phase Transitionmentioning

confidence: 99%

“…[2][3][4][5] Of particular interests are those stimuli-responsive "smart" polymer microgels that can undergo volume phase transitions on receiving external stimuli that is derived from changes in milieu, such as the change in temperature or pH value, or that can be triggered exogenously by ultrasound, irradiation with light or exposure to the electrical and magnetic field. [6][7][8][9] Considering the importance of a chemical system to distinguish between molecules and regulate behaviors accordingly, the development of microgels that is responsive to the changes of a molecule concentration in the milieu is currently a major area of interest. [10][11][12][13][14][15][16] In this work, we aim to develop a type of polymer microgels that can respond to changes in the concentration of ammonia (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of ammonia-responsive polymer microgels

et al. 2015

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aWe report a type of polymer microgels that undergo rapid, reversible, and highly sensitive volume phase transitions upon varying ammonia concentrations in milieu. Such an ammonia-responsive microgel is made by tethering of a phenoxazinium, N-(5-(3-azidopropylamino)-9H-benzo[a]-phenoxazin-9-ylidene)-N-methylmethanaminium chloride, to the network chains of poly(N-isopropylacrylamide-co-propargyl acrylate) via copper(I)-catalyzed azide-alkene cycloaddition. Tethering of the ammonia-recognizable phenoxazinium onto polymer network chains makes the microgels responsive to ammonia. While a fast (<0.1 s) and stable shrinkage of the microgels can be reached upon adding ammonia over a clinically relevant range (0.25−2.9 ppm), the microgels can convert the elevated concentrations of the solution-/gas-phase ammonia into enhanced photoluminescence signals, which make the microgels different from the phenoxazinium or its analogs reported in previous arts that exhibit ammonia-induced quenching in photoluminescence. With the microgels as probes, the detection limit was ca. 7.3×10 -2 and 3.9 ppb, respectively, for the solution-and the gas-phase ammonia. These features enable "turn-on" photoluminescence detection of ammonia in breath.

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Section: Microgels Synthesismentioning

confidence: 99%

Section: Volume Phase Transitionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of ammonia-responsive polymer microgels

et al. 2015

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“…Electric field induced heteroaggregation of large negatively charge latex particles and small positively charged pH-responsive microgel particles was demonstrated by Snoswell et al [28] in the formation of pH-responsive particulate strings. The microgel particles were used to bridge the latex particle strings formed in the presence of an electric field allowing them to remain intact once the electric field was removed, as shown in Figure 4.…”

Section: Adjustable Phmentioning

confidence: 99%

Stimulus-Responsive Heteroaggregation of Colloidal Dispersions: Reversible Systems and Composite Materials

2011

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Abstract:Heteroaggregation is the aggregation of mixed particle systems where the colloidal particles may differ in charge, size and chemical composition. The phenomenon of heteroaggregation is of great relevance in industrial processes and the natural environment. This review will focus on binary heteroaggregation where at least one of the particles is a stimulus-responsive smart particle. Aggregation under various conditions of pH, temperature, light and relative concentration can be induced by the careful manipulation of any one or more of these environmental conditions during the heteroaggregation of smart particles. Stimulus response provides the potential for reversibility from an aggregated to a stable system and exceptional control over inter-particle interactions. The significant fundamental and applied studies that have made an impact in this area will be discussed.

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“…4 Recent advances in this area also include using dielectrophoretic forces 11 which have been employed to assemble conducting nanowires at electrodes without the need for electrostatic charges or chemical bonding of the assembled particles. 22,23 The DEP assembly of dispersed nanoparticles in aqueous media results from the polarisation of the electrical double layers of the particles in the AC eld which align in long chain-like structures that resemble microwires. 10 A range of materials have been assembled in more complex structures by DEP which includes AuNPs, [12][13][14][15][16] AgNWs, 17 SiNWs, 18 CNTs 19-21 and other colloids.…”

Section: Introductionmentioning

confidence: 99%

Dielectrophoretic fabrication of electrically anisotropic hydrogels with bio-functionalised silver nanowires

Small

Paunov

2013

J. Mater. Chem. B

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We have developed a device based on a microwire network formed from bio-functionalised silver nanowires (AgNWs) through dielectrophoresis (DEP) and hydrogel entrapment. This was achieved by carrying out the DEP assembly of AgNWs in an agarose aqueous solution above its gelling temperature and then cooling to encapsulate the assembled structure within the hydrogel which turns it into an electrically anisotropic material that contains up to 99% water. We have studied in detail the formation of microwires assembled from silver nanowires (AgNWs) in agarose gel, at fixed temperature and AC field voltage, which allowed us to build a "phase diagram" of the microwire assembly as a function of the agarose and AgNW concentration at three different lengths of the AgNWs. In this proof-of-concept study, the AgNWs were functionalised with thiolated biotin, then assembled into microwires by DEP and entrapped into a hydrogel. When exposed to a solution of streptavidin the biosensor device showed a marked increase of the cell conductivity due to compacting of the AgNWs which allows streptavidin detection. This generic type of biosensing device could find applications for detection of other biomolecules, the response to which can be directly converted to an electric signal. Conjugating specific antibodies on the AgNW surface would allow the detection of a matching antigen (e.g. protein) in the solution exposed to the anisotropic hydrogel.

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pH‐Responsive Microrods Produced by Electric‐Field‐Induced Aggregation of Colloidal Particles

Cited by 20 publications

References 30 publications

Synthesis and characterization of ammonia-responsive polymer microgels

Synthesis and characterization of ammonia-responsive polymer microgels

Stimulus-Responsive Heteroaggregation of Colloidal Dispersions: Reversible Systems and Composite Materials

Dielectrophoretic fabrication of electrically anisotropic hydrogels with bio-functionalised silver nanowires

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