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    Home > Another coordination between cyclodextrin and stilbene: a simulant of linear molecular motor

    Another coordination between cyclodextrin and stilbene: a simulant of linear molecular motor

    • Last Update: 2018-11-20
    • Source: Internet
    • Author: User
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    Molecular motors is a kind of macromolecular protein which can convert chemical energy into kinetic energy It is widely distributed in human body, and plays an irreplaceable role in life activities such as material transport, mitosis and the formation of cytoskeleton With the development of supramolecular chemistry, scientists have developed many structures similar to molecular motors based on simple supramolecular aggregates such as rotaxane These structures can "orbit" or "rotate" under external stimulation (light, pH, voltage), and further understanding of these structures will greatly accelerate the development of bionics Fig 1 schematic diagram of the structure of hydrogel and its principle of deformation under illumination (photo source: J Am Chem Soc.) recently, two Yoshinori Takashima and Akira Harada scholars from Japan's Osaka University jointly reported a hydrogel with light stress reaction, which is two styrene and four amino acid terminal PEG wrapped by cyclodextrin Combined (Fig 1) This hydrogel will undergo rapid deformation under illumination, and this deformation can occur without solvent This achievement was published in the Journal of the American Chemical Society (DOI: 10.1021 / JACS 8b11351) under the title of "solved free photoresponsiveartificial muscles rapidly driven by molecular machines" The synthesis of hydrogels is not complicated First, the styrene modified cyclodextrin CD-Sti was obtained through the reaction of alpha cyclodextrin (alpha CD) and carboxyl substituted trans two styrene (trans -Sti) This structure will form a 1:1 inclusion compound (α CD STI) 2 in water due to the interaction of supramolecules Then, in the presence of 4- (4,6- two methoxy three azine) -4- methyl morpholine hydrochloride (DMT-MM), (alpha CD-Sti) 2 will react with the four branched chain PEG with terminal amino group to form hydrogel alpha CD-Sti hydrogel (Fig 1) In addition, another hydrogel Sti hydrogel was prepared by using trans styrene two and four branched chain PEG directly Fig 2 A-F) the change of the shape of alpha CD-Sti/Sti hydrogel after illumination G) the schematic diagram of deformation mechanism of alpha CD-Sti hydrogel, f) Sti hydrogel deformation mechanism schematic diagram (source: J Am J.) after obtaining two kinds of hydrogel materials, the author used xenon lamp as the light source to study the deformation properties of hydrogel in detail The results showed that the volume of alpha CD-Stihydrogel shrinks after 350 nm illumination (Fig 2B, c), while the illumination of 280 nm will restore the hydrogel to the original (Figure 2B, c), and the light bending test also shows similar results (Fig 2d-f) The authors found that under the same experimental conditions, the hydrogel Sti hydrogel without cyclodextrin showed a completely opposite deformation The authors speculate that the opposite deformation behavior is caused by the different response of cross-linked nodes to light stimulation For α CD STI hydrogen In terms of the binding capacity of cyclodextrin and trans styrene two, the hydrogel is in a "relaxed state" After illumination, two styrene is trans converted to cis form, and the binding capacity of cyclodextrin is greatly reduced, resulting in the dissociation of cyclodextrin and supramolecular structure of styrene, thus shortening the length of the whole chain, when the hydrogel is in a "tight" shape State (Fig 2G) For Sti hydrogel, spectroscopic data showed that when two styrene was in trans configuration, there existed a two styrene radical association complex in the hydrogel, and the excited association increased the volume of the hydrogel after 350 nm illumination (2f) Fig 3 the deformation of alpha CD-Sti hydrogel and the conversion of light energy into mechanical energy (source: J Am Chem Soc.) after understanding the mechanism of deformation of alpha CD-Sti hydrogel, the authors speculate that it can be deformed without solvent The results show that dry hydrogel will undergo obvious deformation under the light of 350 nm (Fig 3) In addition, the authors quantitatively studied the ability of the hydrogel to convert light energy into mechanical energy The results showed that the hydrogel based on cyclodextrin and two styrene had better performance compared with the previous hydrogel Highlights of the article: a photoresponse hydrogel was prepared by using cyclodextrin inclusion complex with two styrene as crosslinking point The hydrogel can achieve large deformation under illumination without solvent Author: Shinji ikejiri, Yoshinori Takashima, motofumiosaki, Hiroyasu Yamaguchi and Akira Harada
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