Effect of structural variation within cationic azo-surfactant upon photoresponsive function in aqueous solution

Hayashita, Takashi; Kurosawa, Takahiko.; Miyata, Tomohiro; Tanaka, Kenta; Igawa, Manabu

doi:10.1007/bf00664729

Cited by 167 publications

(204 citation statements)

References 16 publications

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“…For azoTAB, the isomerization from trans to cis exposes the hydrophilic azo group (Fig. 1B), which causes the CMC to increase from 4 mM (trans, visible light) to 11 mM (cis, UV light) (12). Such light-modulated differences in aggregate structures arise directly from important and quantifiable differences in intermolecular interactions associated with the different light-dependent surfactant structures.…”

Section: Results and Analysesmentioning

confidence: 99%

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General hydrophobic interaction potential for surfactant/lipid bilayers from direct force measurements between light-modulated bilayers

Donaldson

Lee

Chmelka

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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We establish and quantify correlations among the molecular structures, interaction forces, and physical processes associated with light-responsive self-assembled surfactant monolayers or bilayers at interfaces. Using the surface forces apparatus (SFA), the interaction forces between adsorbed monolayers and bilayers of an azobenzene-functionalized surfactant can be drastically and controllably altered by light-induced conversion of trans and cis molecular conformations. These reversible conformation changes affect significantly the shape of the molecules, especially in the hydrophobic region, which induces dramatic transformations of molecular packing in self-assembled structures, causing corresponding modulation of electrostatic double layer, steric hydration, and hydrophobic interactions. For bilayers, the isomerization from trans to cis exposes more hydrophobic groups, making the cis bilayers more hydrophobic, which lowers the activation energy barrier for (hemi)fusion. A quantitative and general model is derived for the interaction potential of charged bilayers that includes the electrostatic double-layer force of the Derjaguin-Landau-Verwey-Overbeek theory, attractive hydrophobic interactions, and repulsive steric-hydration forces. The model quantitatively accounts for the elastic strains, deformations, long-range forces, energy maxima, adhesion minima, as well as the instability (when it exists) as two bilayers breakthrough and (hemi)fuse. These results have several important implications, including quantitative and qualitative understanding of the hydrophobic interaction, which is furthermore shown to be a nonadditive interaction.membrane fusion | hydrophilic-lipophilic balance | photoresponsive S elf-assembled surfactant structures, such as micelles, vesicles, adsorbed surfactant monolayers, and bilayers, are utilized in many industrial and technological processes, including detergents and other cleaning products, coatings, separation processes, nano-and micromicellar reactors, dispersants, emulsifiers, and drug delivery vehicles. In all of these, precise control of morphologies and phases is crucial, properties that are largely governed by the interplay of the intramolecular interactions within individual aggregates (headgroup repulsions, steric and hydrophobic chain interactions, molecular packing) and the intermolecular interactions with other aggregates or surfaces [DerjaguinLandau-Verwey-Overbeek (DLVO) forces, steric hydration forces, hydrophobic interactions, depletion forces]. Conventionally, one can modify these interactions by adjusting temperature, ionic strength, pH, or surfactant chain length, but only small changes occur in the resulting structures. New types of surfactants have been demonstrated to exhibit surfactant molecular structure and interactions that can be significantly and reversibly modified in situ by including active functional groups in the hydrophobic tail of the surfactant (1), thus causing dramatic corresponding transformations to surfactant morphologies and phases (i.e., m...

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Section: Results and Analysesmentioning

confidence: 99%

“…The photoresponsive surfactant azoTAB (M r ¼ 420.4 g∕mol) was synthesized as previously reported (12) and confirmed to have 99% purity by GC and NMR. Ultrapure water obtained from a Milli-Q (Elix 10 and Milli-Q Gradient A10) system was used to make aqueous solutions of azoTAB of given concentrations.…”

Section: Methodsmentioning

confidence: 99%

General hydrophobic interaction potential for surfactant/lipid bilayers from direct force measurements between light-modulated bilayers

Donaldson

Lee

Chmelka

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Usually, the solubility of the building blocks will be increased after the azobenzene changes from trans to cis form. [101][102][103] Sakai et al built up a model to control the reversible release of oily substances from the azobenzenecontaining micelles by light irradiation. When the azobenzene moiety in the middle hydrophobic part of the surfactant changed from trans to cis form, the micelle was destroyed and the small hydrophobic molecules preloaded in the micelle could be released under control.…”

Section: Photocontrolled Methodsmentioning

confidence: 99%

Tuning the Amphiphilicity of Building Blocks: Controlled Self‐Assembly and Disassembly for Functional Supramolecular Materials

2009

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Amphiphilicity is one of the molecular bases for self‐assembly. By tuning the amphiphilicity of building blocks, controllable self‐assembly can be realized. This article reviews different routes for tuning amphiphilicity and discusses different possibilities for self‐assembly and disassembly in a controlled manner. In general, this includes irreversible and reversible routes. The irreversible routes concern irreversible reactions taking place on the building blocks and changing their molecular amphiphilicity. The building blocks are then able to self‐assemble to form different supramolecular structures, but cannot remain stable upon loss of amphiphilicity. Compared to the irreversible routes, the reversible routes are more attractive due to the good control over the assembly and disassembly of the supramolecular structure formed via tuning of the amphiphilicity. These routes involve reversible chemical reactions and supramolecular approaches, and different external stimuli can be used to trigger reversible changes of amphiphilicity, including light, redox, pH, and enzymes. It is anticipated that this line of research can lead to the fabrication of new functional supramolecular assemblies and materials.

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“…Thus, their systems are too complex for the physical properties of the azobenzene surfactants to be clearly interpreted. In order to overcome this problem, Hayashita et al (15) have examined the design of azobenzene surfactant which showed good solubility in water and an effective change of critical micelle concentration (cmc) upon photoisomerization. The azobenzene surfactants with optimum alkyl chain length such as 4-butylazobenzene-4 -(oxyethyl)trimethylammonium bromide and 4-ethylazobenzene-4 -(oxybutyl)trimethylammonium bromide (Scheme 2) showed large changes in their cmcs upon photoirradiation.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Surface-Active Properties of New Photosensitive Surfactants Containing the Azobenzene Group

Kang

Lee

Yoon

et al. 2000

Journal of Colloid and Interface Science

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Effect of structural variation within cationic azo-surfactant upon photoresponsive function in aqueous solution

Cited by 167 publications

References 16 publications

General hydrophobic interaction potential for surfactant/lipid bilayers from direct force measurements between light-modulated bilayers

General hydrophobic interaction potential for surfactant/lipid bilayers from direct force measurements between light-modulated bilayers

Tuning the Amphiphilicity of Building Blocks: Controlled Self‐Assembly and Disassembly for Functional Supramolecular Materials

Synthesis and Surface-Active Properties of New Photosensitive Surfactants Containing the Azobenzene Group

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