Redox‐Responsive and Thermoresponsive Supramolecular Nanosheet Gels with High Young's Moduli

Zheng, Yijun; Wang, Dapeng; Cui, Jiaxi; Mezger, Markus; Auernhammer, Günter K.; Koynov, Kaloian; Butt, Hans‐Jürgen; Ikeda, Taichi

doi:10.1002/marc.201800282

Cited by 9 publications

(9 citation statements)

References 44 publications

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“…Synthesis of Compound 15. Imidazole-1-sulfonyl azide hydrogen sulfate (14•H 2 SO 4 , 647 mg, 2.39 mmol) was added to a mixture of the commercially available N 1 ,N 4 ,N 9 -tris(Boc)spermine (1.0 g, 1.99 mmol), K 2 CO 3 (0.5 mmol), and CuSO 4 •5H 2 O (5 mg, 0.02 mmol) in methanol (22 mL), and the resulting reaction mixture was stirred at r.t. for 30 h. It was diluted with H 2 O (50 mL) and extracted with ethyl acetate (3 × 50 mL). After drying the organic layer over anhydrous Na 2 SO 4 , the volatiles were removed under reduced pressure.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Despite being predominantly comprised of liquids, the resulting gels display solidlike mechanical properties in their rheological behavior . Importantly, in general, molecular organo- and hydrogels offer reversible control of their mechanical properties when perturbed by external stimuli, such as temperature, light, electric field, pH, oxidation–reduction, or mechanical stress . The reversible mechanical properties are consequences of the structural reorganization of gelators .…”

Section: Introductionmentioning

confidence: 99%

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Rapid Self-Healing and Thixotropic Organogelation of Amphiphilic Oleanolic Acid–Spermine Conjugates

et al. 2021

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Natural and abundant plant triterpenoids are attractive starting materials for the synthesis of conformationally rigid and chiral building blocks for functional soft materials. Here, we report the rational design of three oleanolic acid–triazole–spermine conjugates, containing either one or two spermine units in the target molecules, using the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction. The resulting amphiphile-like molecules 2 and 3, bearing just one spermine unit in the respective molecules, self-assemble into highly entangled fibrous networks leading to gelation at a concentration as low as 0.5% in alcoholic solvents. Using step-strain rheological measurements, we show rapid self-recovery (up to 96% of the initial storage modulus) and sol ⇔ gel transition under several cycles. Interestingly, rheological flow curves reveal the thixotropic behavior of the gels. To the best of our knowledge, this kind of behavior was not shown in the literature before, neither for a triterpenoid nor for its derivatives. Conjugate 4, having a bolaamphiphile-like structure, was found to be a nongelator. Our results indicate that the position and number of spermine units alter the gelation properties, gel strength, and their self-assembly behavior. Preliminary cytotoxicity studies of the target compounds 2–4 in four human cancer cell lines suggest that the position and number of spermine units affect the biological activity. Our results also encourage exploring other triterpenoids and their derivatives as sustainable, renewable, and biologically active building blocks for multifunctional soft organic nanomaterials.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rapid Self-Healing and Thixotropic Organogelation of Amphiphilic Oleanolic Acid–Spermine Conjugates

et al. 2021

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“…Furthermore, these materials showed temperature‐dependent mechanical properties, even undergoing sol–gel transitions. These kinds of materials that can be reversibly formed, offer a unique versatility for several applications in the biomedical field …”

Section: Viscoelastic Thermal and Water Swelling Characteristics Ofmentioning

confidence: 99%

Controlled Thermoreversible Formation of Supramolecular Hydrogels Based on Poly(vinyl alcohol) and Natural Phenolic Compounds

Euti

Wolfel

Picchio

et al. 2019

Macromol. Rapid Commun.

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Supramolecular materials based on noncovalent bonds have attracted considerable attention in several fields due to their special characteristics such as self-healing, shape memory, and stimuli-responsive properties among others. [1][2][3][4][5][6][7][8][9][10] Indeed, multiple hydrogen bonding are ideal reversible noncovalent interactions for preparing supramolecular networks combining high strength and excellent reversibility. [11][12][13][14][15][16][17][18][19][20][21] Supramolecular Thermoresponsive Hydrogels Supramolecular hydrogels have promising applications in a wide variety of fields including 3D bioprinting, sensors and actuators, biomedicine, and controlled drug delivery. This communication reports the facile reversible thermotriggered formation of novel pH-responsive supramolecular hydrogels based on poly(vinyl alcohol) (PVA) bonded via dynamic H-bridge with small phenolic biomolecules. PVA and phenolic compounds form a clear solution when they are physically mixed in water at high temperature, but a fast gelation is produced at room temperature through multiple strong H-bonding interactions. The structure and type of functional groups of different phenolic molecules allow preparing hydrogels with tailor-made viscoelastic properties, controlled low phase transition temperature, and pH-dependent swelling behavior. This combination makes these supramolecular networks very interesting candidates to be used in 3D bioprinting and topical drug delivery of thermolabile biomolecules.

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“…Nakahata et al demonstrated a redox-responsive gel based on the different interactions of ferrocene to β-cyclodextrin and styrenesulfonic acid sodium salt under oxidative and reductive conditions . Although these studies were valuable, however, most of the changes resulted from redox stimuli in supramolecular gels are phase transitions, , color or mechanical properties, , and few studies have examined redox-responsive gel with the switch of luminescence. Obviously, luminescence based on intramolecular energy transitions are more sensitive and convenient to detect.…”

Section: Introductionmentioning

confidence: 99%

Reversible Redox Switching of Concurrent Luminescence and Visual Color Change Based on Lanthanide Metallogel

et al. 2019

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The development of reversible redox supramolecular gels capable of concurrent luminescence switch and visible color change with the facile redox process has always been an intriguing challenge. A redox-responsive supramolecular lanthanide metallogel with strong luminescence and yellow color is obtained via coordination interaction between 3,5-dinitrosalicylic acid (DNSA) and europium (Eu3+). Upon the addition of TiO2 to the prepared gel (DNSA/Eu3+ gel), the oxidation process of the gel (DNSA/Eu3+/TiO2 gel) can be easily achieved by UV irradiation. The DNSA/Eu3+/TiO2 gel exhibits a concurrent reversible “on–off” luminescence and color change in response to redox stimuli. The DNSA/Eu3+/TiO2 gel shows a concurrent quench of luminescence and a color change from yellow to red when the gel was stimulated by the reductant. Upon UV irradiation, the luminescence and color of the reduced DNSA/Eu3+/TiO2 gel restored to its initial state due to the strong oxidation ability of hydroxyl radicals derived from photocatalytic oxidation of TiO2. The results of UV–vis and mass spectroscopy indicated that the reversible redox responsiveness of DNSA/Eu3+/TiO2 gel depends on the reversible oxidation–reduction reactions of DNSA. Moreover, DNSA/Eu3+/TiO2 gel remains stable because the morphology of the gel had no change during the redox process. Exemplarily, the application of DNSA/Eu3+/TiO2 gels to achieve luminescent patterning was investigated. The results demonstrated that the prepared metallogel has potential applications in the fields of writable materials, anticounterfeiting, sensors, and others.

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Redox‐Responsive and Thermoresponsive Supramolecular Nanosheet Gels with High Young's Moduli

Cited by 9 publications

References 44 publications

Rapid Self-Healing and Thixotropic Organogelation of Amphiphilic Oleanolic Acid–Spermine Conjugates

Rapid Self-Healing and Thixotropic Organogelation of Amphiphilic Oleanolic Acid–Spermine Conjugates

Controlled Thermoreversible Formation of Supramolecular Hydrogels Based on Poly(vinyl alcohol) and Natural Phenolic Compounds

Reversible Redox Switching of Concurrent Luminescence and Visual Color Change Based on Lanthanide Metallogel

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