Thermodriven Micrometer‐Scale Aqueous‐Phase Separation of Amphiphilic Oligoethylene Glycol Analogues

Kawasaki, Shunichi; Muraoka, Takahiro; Obara, Haruki; Ishii, Takerou; Hamada, Tsutomu

doi:10.1002/asia.201402134

Cited by 15 publications

(9 citation statements)

References 83 publications

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“…This level of selectivity has not previously been reported for peptides, although conventional polymers, such as inverse micelles and amphiphilic monodisperse PEGs, have been used as extraction agents for group separation of peptides. 66 , 67 The system described herein can be expected to be applicable to sample pretreatments for mass spectrometric analysis of peptides, which usually requires the extraction and condensation of target analytes coexisting with large amounts of bioimpurities. 68 , 69 …”

Section: Results and Discussionmentioning

confidence: 99%

RETRACTED: Soft Nanotubes Derivatized with Short PEG Chains for Thermally Controllable Extraction and Separation of Peptides

2017

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By means of a two-step self-assembly process involving three components, including short poly(ethylene glycol) (PEG) chains, we produced two different types of molecular monolayer nanotubes: nanotubes densely functionalized with PEG chains on the outer surface and nanotubes densely functionalized with PEG chains in the nanochannel. Turbidity measurements and fluorescence spectroscopy with an environmentally responsive probe suggested that the PEG chains underwent dehydration when the nanotubes were heated above 44–57 °C and rehydration when they were cooled back to 25 °C. Dehydration of the exterior or interior PEG chains rendered them hydrophobic and thus able to effectively extract hydrophobic amino acids from the bulk solution. Rehydration of the PEG chains restored their hydrophilicity, thus allowing the extracted amino acids to be squeezed out into the bulk solutions. The nanotubes with exterior PEG chains exhibited selectivity for all of the hydrophobic amino acids, whereas the interior PEG chains were selective for hydrophobic amino acids with an aliphatic side chain over hydrophobic amino acids with an aromatic side chain. The higher selectivity of the latter system is attributable that the extraction and back-extraction processes involve encapsulation and transportation of the amino acids in the nanotube channel. As the result, the latter system was useful for separation of peptides that differed by only a single amino acid, whereas the former system showed no such separation ability.

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Section: Results and Discussionmentioning

confidence: 99%

RETRACTED: Soft Nanotubes Derivatized with Short PEG Chains for Thermally Controllable Extraction and Separation of Peptides

2017

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“…In sharp contrast, 3 TEG exhibited a significant increase in the average particle size from 1.46 to 348 nm upon increasing the temperature to 70 °C and it retained the monodisperse profile (Figure e). Phase‐contrast microscopy (PCM) allowed the formation of the aggregates to be directly observed . At 20 °C, 3 TEG in water displayed no visible objects (Figure a), whereas the formation of sub‐micrometer‐sized spherical aggregates was observed upon increasing the temperature (black spots in Figure b).…”

Section: Resultsmentioning

confidence: 89%

Synthesis and Thermal Responses of Polygonal Poly(ethylene glycol) Analogues

Kawasaki

Muraoka

Hamada

et al. 2016

Chemistry An Asian Journal

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As a new type of topological poly(ethylene glycol) (PEG) analogue, a series of polygonal PEGs with digonal to hexagonal structures were developed. Polygonal PEGs with structures between the digonal and tetragonal types showed molecular-level dispersion in water at 20 °C, whereas the pentagonal and hexagonal PEGs aggregated, which is suggestive of enhanced hydrophobicity by ring expansion. Heating induced conformational changes in the polygonal PEGs and increased their hydrophobicity. Among the polygonal PEGs, only the trigonal and hexagonal PEGs showed a distinct thermal response to form and increase the size of the aggregates, respectively. Given that tetragonal and pentagonal PEGs only marginally responded to heat treatment, the thermal responses are likely due to a topological effect. At low temperatures, the larger polygonal PEGs are more restricted despite the expanded rings. The trigonal PEG showed the largest change in mobility, whereas the tetragonal PEG exhibited the smallest change. Hence, the topology of the polygonal PEGs influences the intramolecular packing and the local dynamics.

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“…The lower critical solution temperature (LCST) of 1 is 26.4 °C, as reported previously. 6 It is suggested that the phase separation of 1 in aqueous media is prompted by the gauche-to-anti conformational change at the carbon-carbon bond of the ethylene oxide units to increase the hydrophobicity.…”

Section: Resultsmentioning

confidence: 99%

“…5 Recently, we reported a temperature-responsive small amphiphile 1,1'-((2,5,8,11,14-pentaoxapentadecane-1,15-diyl)-bis(2-phenyl-1,3-dioxane-5,5-diyl))bis(2, 5,8,11-tetraoxatridecan-13-ol) (1) that shows micrometer-scale aggregation in water upon heating due to a conformational change at the ethylene oxide units. 6 The thermo-driven aggregation of 1 was useful for selective peptide extraction. In this study, we investigated protein extraction with 1 in comparison with PNIPAM.…”

Section: Introductionmentioning

confidence: 99%