Switchable Surfactants

Liu, Yingxin; Jessop, Philip G.; Cunningham, Michael F.; Eckert, Charles A.; Liotta, Charles L.

doi:10.1126/science.1128142

Cited by 761 publications

(671 citation statements)

References 14 publications

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“…14 An innovative approach to "green" switchable surfactants was recently reported by Jessop and co-workers. 15,16 The switching mechanism is based on the strong basicity of (long-chain) alkyl amidine, which turns into an effective surfactant in the presence of CO 2 when amidine is converted into amidinium bicarbonate. The surface activity of the molecule may be turned off by bubbling nitrogen or other gases at elevated temperatures.…”

Section: ■ Introductionmentioning

confidence: 99%

Protection/Deprotection of Surface Activity and Its Applications in the Controlled Release of Liposomal Contents

Zhao

2012

Langmuir

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The micelles of two tripropargylammonium-functionalized cationic surfactants were cross-linked by a disulfide-containing diazido cross-linker in the presence of Cu(I) catalysts. With multiple residual alkyne groups on the surface, the resulting surface cross-linked micelles (SCMs) were postfunctionalized by reaction with 2-azidoethanol and an azido-terminated poly(ethylene glycol), respectively, via the alkyne-azide click reaction. The water-soluble nanoparticles obtained had low surface activity due to the buried hydrophobic tails. Cleavage of the disulfide cross-links by dithiothreitol (DTT) exposed the hydrophobic tails and resumed surface activity of the "caged" surfactants within 2 min after DTT addition. The controlled breakage of the SCMs was used to lower the surface tension of aqueous solutions and trigger the release of liposomal contents on demand. Disciplines Chemistry CommentsReprinted (adapted) with permission from Langmuir 28 (2012) ABSTRACT: The micelles of two tripropargylammoniumfunctionalized cationic surfactants were cross-linked by a disulfidecontaining diazido cross-linker in the presence of Cu(I) catalysts. With multiple residual alkyne groups on the surface, the resulting surface cross-linked micelles (SCMs) were postfunctionalized by reaction with 2-azidoethanol and an azido-terminated poly(ethylene glycol), respectively, via the alkyne−azide click reaction. The water-soluble nanoparticles obtained had low surface activity due to the buried hydrophobic tails. Cleavage of the disulfide cross-links by dithiothreitol (DTT) exposed the hydrophobic tails and resumed surface activity of the "caged" surfactants within 2 min after DTT addition. The controlled breakage of the SCMs was used to lower the surface tension of aqueous solutions and trigger the release of liposomal contents on demand.

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Section: ■ Introductionmentioning

confidence: 99%

Protection/Deprotection of Surface Activity and Its Applications in the Controlled Release of Liposomal Contents

Zhao

2012

Langmuir

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“…The use of POMs for obtaining compounds that are magnetically active is well established [87] with many of them being investigated as molecular-based magnets. 6 and magnetic high-spin d 5 configurations [10]. The change in magnetic properties was nicely demonstrated using electron paramagnetic resonance (EPR) but unfortunately no further investigations were reported ( Figure 12).…”

Section: Polyoxometalate Surfactants (Poms) -Classmentioning

confidence: 90%

“…Interestingly, many of the redox-active surfactants would also be expected to be paramagnetic. For example, Ru-based polyoxometalate (POM) surfactants convert between low-spin d 6 and high-spin d 5 through electrochemical activity [10], and oxidized ferrocenyl-based surfactants contain high spin d 6 paramagnetic centres [11]. Similarly, metallosurfactants containing d-or f-block metals as integral structural components had also received attention as a means of facilitating catalytic activity at interfaces and templating mesoporous materials [12].…”

Section: Introductionmentioning

confidence: 99%

“…A more sophisticated approach is to use external stimuli to activate reversible changes in molecular structures with responsive surfactants [5]. This has been achieved through sensitivity towards changes in CO2 levels [6], light [7], enzymes [8] and electrical potential (redox) [9]. Interestingly, many of the redox-active surfactants would also be expected to be paramagnetic.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic surfactants

Brown

Hatton

Eastoe

2015

Current Opinion in Colloid & Interface Science

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms The use of these magneto-surfactants as novel molecular magnets is also investigated as well as looking forward to potential applications. Graphical AbstractHighlights  Introduce the 3 existing classes of magnetic surfactants; ionic, coordinating, covalently bound  Consider a potential 4 th class of magnetic surfactant  Describe how these surfactants function as molecular magnets  Report potential applications ranging biochemistry to water treatment  Discuss the origins of magnetism in dilute aqueous solutions

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“…Hence, CO 2 is sensed by the plants to adjust the opening of these pores and induce anion transport from one side of the membrane to the other. 26 Similarly, we developed artificial ion channels that utilize two amidine-containing [27][28][29][30][31][32][33] molecules with flexible and rigid molecular structures located on the inner wall of the channels to regulate the ion current. The reaction of CO 2 with amidine groups leads to the conversion of CO 2 , water and amidine groups to bicarbonate and amidine cations.…”

Section: Introductionmentioning

confidence: 99%

Mimicking how plants control CO2 influx: CO2 activation of ion current rectification in nanochannels

Zhang

Tong

et al. 2015

NPG Asia Mater

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One of the key processes of photosynthesis is to control the influx of atmospheric carbon dioxide (CO 2 ). Ion channels fulfill this process by regulating the opening and closing of stomatal pores in plants' leaves. Inspired by this natural process, we have developed an amidine-modified gas-responsive system that closely mimics stomatal pores: CO 2 rather than the variation in the pH value directly modulates the conductance state of the channel. The CO 2 -activated chemical reaction of amidine groups is reversible and produces an excess surface charge on the pore walls of asymmetric nanochannels, which makes the ions pass preferentially through the nanochannels in one direction relative to the conductance in the other direction, resulting in a significant ion current rectification. Furthermore, the influence of the different molecular conformation of the amidine-containing molecules on the current is investigated and discussed. The conclusive simulation of our system based on the Poisson and Nernst-Planck (PNP) model is also in good agreement with the experimental results. Accordingly, we have successfully mimicked the mechanism of stomatal closure in plants with our gas-activated nanosystem.

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Switchable Surfactants

Cited by 761 publications

References 14 publications

Protection/Deprotection of Surface Activity and Its Applications in the Controlled Release of Liposomal Contents

Protection/Deprotection of Surface Activity and Its Applications in the Controlled Release of Liposomal Contents

Magnetic surfactants

Mimicking how plants control CO2 influx: CO2 activation of ion current rectification in nanochannels

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