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1.
Beyond their colorful appearances and versatile geometries, flowers can self‐shape‐morph by adapting to environmental changes. Such responses are often regulated by a delicate interplay between different stimuli such as temperature, light, and humidity, giving rise to the beauty and complexity of the plant kingdom. Nature inspires scientists to realize artificial systems that mimic their natural counterparts in function, flexibility, and adaptation. Yet, many of the artificial systems demonstrated to date fail to mimic the adaptive functions, due to the lack of multi‐responsivity and sophisticated control over deformation directionality. Herein, a new class of liquid‐crystal‐network (LCN) photoactuators whose response is controlled by delicate interplay between light and humidity is presented. Using a novel deformation mechanism in LCNs, humidity‐gated photoactuation, an artificial nocturnal flower is devised that is closed under daylight conditions when the humidity level is low and/or the light level is high, while it opens in the dark when the humidity level is high. The humidity‐gated photoactuators can be fueled with lower light intensities than conventional photothermal LCN actuators. This, combined with facile control over the speed, geometry, and directionality of movements, renders the “nocturnal actuator” promising for smart and adaptive bioinspired microrobotics.  相似文献   
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A novel method for synthesizing and photopatterning colloidal crystals via light-responsive DNA is developed. These crystals are composed of 10–30 nm gold nanoparticles interconnected with azobenzene-modified DNA strands. The photoisomerization of the azobenzene molecules leads to reversible assembly and disassembly of the base-centered cubic (bcc) and face-centered cubic (fcc) crystalline nanoparticle lattices. In addition, UV light is used as a trigger to selectively remove nanoparticles on centimeter-scale thin films of colloidal crystals, allowing them to be photopatterned into preconceived shapes. The design of the azobenzene-modified linking DNA is critical and involves complementary strands, with azobenzene moieties deliberately staggered between the bases that define the complementary code. This results in a tunable wavelength-dependent melting temperature (Tm) window (4.5–15 °C) and one suitable for affecting the desired transformations. In addition to the isomeric state of the azobenzene groups, the size of the particles can be used to modulate the Tm window over which these structures are light-responsive.  相似文献   
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It is well known that irradiation of azobenzene polymer films between 490 and 530 nm results in alignment of molecules perpendicular to the polarization of the incident beam. I have recently found that irradiation of amorphous azobenzene polymers with linearly polarized light at wavelengths between 560 and 630 nm, where the absorption is minimal, results in a possible uniaxial hedgehog arrangement of the molecules. Experiments performed with a dye laser, which can be tuned continuously between 560 and 630 nm, are described. Not only azobenzene but also another photosensitive molecule, bacteriorhodopsin, seems to exhibit this behavior.  相似文献   
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Photoswitchable lipids are emerging tools for the precise manipulation and study of lipid function. They can modulate many aspects of membrane biophysics, including permeability, fluidity, lipid mobility and domain formation. They are also very useful in lipid physiology and enable optical control of a wide array of lipid receptors, such as ion channels, G protein-coupled receptors, nuclear hormone receptors, and enzymes that translocate to membranes. Enzymes involved in lipid metabolism often process them in a light-dependent fashion. Photoswitchable lipids complement other functionalized lipids widely used in lipid chemical biology, including isotope-labeled lipids (lipidomics), fluorescent lipids (imaging), bifunctional lipids (lipid–protein crosslinking), photocaged lipids (photopharmacology), and other labeled variants.  相似文献   
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The design and synthesis of a new azobenzene-based methacrylate monomer (Azo-IEM) was demonstrated, and its polymerization behavior during reversible addition-fragmentation chain transfer (RAFT) polymerization was investigated. Well-defined homopolymer and amphiphilic block copolymer containing Azo-IEM monomeric units were successfully prepared as evidenced by NMR and GPC analysis. Moreover, the photo-triggered reversible isomerization of polymer products in selected solvents was investigated. Finally, TEM analysis showed that there were significant differences in the nanoparticle morphologies when the block copolymer samples were irradiated with different wavelengths of light (i.e., UV and visible). The size and shapes of the p(HEMA-b-Azo-IEM) polymer capable of transitions upon changes in Vis/UV light exposure which prepared from MeOH/CHCl3 mixture solvent. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47870.  相似文献   
6.
A low‐powered and highly selective photomechanical sensor system mimicking stomata in the epidermis of leaves harvested from nature is demonstrated. This device uses a light‐responsive composite consisting of 4‐amino‐1,1′‐azobenzene‐3,4′‐disulfonic acid monosodium salt (AZO) and poly(diallyldimethylammonium chloride) (PDDA) coated on a membrane with tens of nanometer‐size pores. The ionic current change through the pore channels as a function of pore size variation is then measured. The tran–cis isomerism of AZO–PDDA during light irradiation and the operation mechanism of photomechanical ion channel sensor are discussed and analyzed using UV–vis spectroscopy and atomic force microscopy analysis. It presents the discriminative current levels to the different light wavelengths. The response time of the photoreceptor is about 0.2 s and it consumes very low operating power (≈15 nW) at 0.1 V bias. In addition, it is found that the change of the pore diameter during the light irradiation is due to the photomechanical effect, which is capable of distinguishing light intensity and wavelength.  相似文献   
7.
以3,5-二叔丁基苯酚,三氟甲基磺酸酐和4,5-二乙炔基-2-甲氧基苯酚为原料合成4,5-双(3',5'-二叔丁基苯基乙炔基)-2-甲氧基苯酚,并在其羟基上引入4,4'-二(三甲基甲硅烷基乙炔基)偶氮苯,成功得到了以偶氮苯为核心第一代不对称共轭苯乙炔树状聚合物。该树状聚合物在波长为200~425 nm之间对紫外光有强的吸收,并在紫外光的激发下发出蓝色荧光。  相似文献   
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