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stimuli responsive materials

Taichi Ikeda
Glycidyl triazolyl polymer (GTP), which is the product of the Huisgen dipolar cycloaddition reaction between glycidyl azide polymer and alkyne derivatives, is featured here. GTP is the multifunctionalized poly(ethylene glycol) (PEG). The drawback of PEG is that linear PEG has the functional group only at both ends. The low loading capability of the functional groups limits the possibilities of PEG applications. GTP facilitates the synthesis of multifunctionalized PEG derivatives. In this article, 74 examples of GTP homopolymers and copolymers are introduced...
March 12, 2018: Macromolecular Rapid Communications
Zhanfeng Li, Zonghua Wang, Xiaoyu Du, Chao Shi, Xuejun Cui
Stimuli-responsive polymer microcapsules (PMs) fabricated by the sonochemical method have emerged for developing useful drug delivery systems, and the latest developments are mainly focusing on the synthetic strategies and properties such as structure, size, stability, loading capacity, drug delivery, and release. There, the primary attribution of sonochemistry is to offer a simple and practical approach for the preparation of PMs. Structure, size, stability, and properties of PMs are designed mainly according to synthetic materials, implementation schemes, or specific demands...
March 12, 2018: Advanced Healthcare Materials
Yogev Kivity, Jonathan D Huppert
BACKGROUND: Models of social anxiety emphasize the role of emotion dysregulation, but the nature of these impairments needs clarification. METHODS: We utilized a mixed-method approach to examine impairments in cognitive reappraisal and expressive suppression in social anxiety disorder. Forty nine treatment-seeking individuals diagnosed with social anxiety disorder and 35 healthy controls completed self-reports and a lab-based task of suppression and reappraisal...
February 21, 2018: Journal of Affective Disorders
Lorenzo Vannozzi, Veronica Iacovacci, Arianna Menciassi, Leonardo Ricotti
INTRODUCTION: Traditional drug release systems normally rely on a passive delivery of therapeutic compounds, which can be partially programmed, prior to injection or implantation, through variations in the material composition. With this strategy, the drug release kinetics cannot be remotely modified and thus adapted to changing therapeutic needs. To overcome this issue, drug delivery systems able to respond to external stimuli are highly desirable, as they allow a high level of temporal and spatial control over drug release kinetics, in an operator-dependent fashion...
March 9, 2018: Expert Opinion on Drug Delivery
Zhenchao Qian, Zhen Wang, Ning Zhao, Jian Xu
Aerogels are gels in which the solvent is supplanted by air while the pores and networks are largely maintained. Owing to their low bulk density, high porosity, and large specific surface area (SSA), aerogels are promising for many applications. Various inorganic aerogels, e.g., silica aerogels, are intensively studied. However, the mechanical brittleness of common inorganic aerogels has seriously restricted their applications. In the past decade, nanofibers have been developed as building blocks for the construction of aerogels to improve their mechanical property...
March 8, 2018: Macromolecular Rapid Communications
Ming Chen, Lingzhi Li, Haiqiang Wu, Lingxiang Pan, Shiwu Li, Bairong He, Haoke Zhang, Jing Zhi Sun, Anjun Qin, Ben Zhong Tang
Polymers with aggregation-induced emission (AIE) characteristics have aroused tremendous interest because of their potential applications in large-area flexible display and luminescent self-assembling, and as stimuli-responsive and porous materials. However, the design of AIE-active polymers is always not as easy as that of small molecules because their properties are hard to predict. In some cases, the polymers prepared from the AIE-active monomers show the aggregation-caused quenching (ACQ) instead of AIE effect...
March 7, 2018: ACS Applied Materials & Interfaces
Haoran Wang, Jinyu Zhao, Guojian Yang, Fushuang Zhang, Jingbo Sun, Ran Lu
Fully-conjugated styrylbenzoxazoles and styrylbenzothiazoles of BOAF24, BOACl24, BOACl35, BOABr24, BOABr35, BTAF24, BTACl24 and BTABr24 without traditional gelation groups could form organogels. It was found that introduction of chlorine atoms in the 2,4-positions of the phenyl group would improve gelation abilities, and benzothiazole derivatives exhibited better gelation abilities than benzoxazoles with a similar π-skeleton due to better π-electron delocalization. Interestingly, the organogel of BTACl24 could change into solution by UV light due to trans-cis isomerization, which could also induce morphological changes in xerogels...
March 7, 2018: Organic & Biomolecular Chemistry
Ling Liu, Patrick R Onck
Switchable materials in response to external stimuli serve as building blocks to construct microscale functionalized actuators and sensors. Azobenzene-modified liquid crystal (LC) polymeric networks, that combine liquid crystalline orientational order and elasticity, reversibly undergo conformational changes powered by light. We present a computational framework to describe photo-induced topographical transformations of azobenzene-modified LC glassy polymer coatings. A nonlinear light penetration model is combined with an opto-mechanical constitutive relation to simulate various ordered and corrugated topographical textures resulting from aligned or randomly distributed LC molecule orientations...
March 7, 2018: Soft Matter
Anju Toor, Sean Lamb, Brett Helms, Thomas P Russell
Interfacial assemblies of nanoparticles can stabilize liquid-liquid interfaces. Due to the interactions between functional groups on nanoparticles dispersed in one liquid and polymers having complementary end-functionality dissolved in a second immiscible fluid, the anchoring of a well-defined number of polymer chains onto the nanoparticles leads to the formation of NP-surfactants that assemble at the interface and reduce the interfacial energy. We have developed droplet interfaces covered with elastic, responsive monolayers of NP- surfactants...
March 6, 2018: ACS Nano
Wei Wang, Chenzhe Li, Maenghyo Cho, Sung-Hoon Ahn
Botanic nastic movements that occur in response to environmental stimuli have inspired many man-made shape-morphing systems. Tendril is an exemplification serving the climbing plants as their parasitic grasping component through transforming from a straight shape into a coiled configuration via the asymmetric contraction of internal stratiform plant tissues. Inspired by tendrils, this study using three-dimensional (3D) printing approach developed a class of soft gripper with pre-programmed deformations being capable of imitating the general motions of plant tendrils including bending, spiral and helical distortions for grasping...
March 5, 2018: ACS Applied Materials & Interfaces
Heshu Fang, Xia Zhao, Yuan Lin, Song Yang, Jun Hu
Construction of stimuli-responsive materials using naturally occurring molecules as building blocks has received increasing attention in terms of bioavailability, biocompatibility, and biodegradability. In this research, a symmetrical azobenzene-functionalized natural glycyrrhizic acid (trans-GAG) was synthesized, which could form the stable supramolecular gels in DMSO/H2O and MeOH/H2O, respectively. On account of trans-cis isomerization, this gel exhibited a typical light-responsive behavior, thus leading to a reversible gel-sol transition accompanied with the variation in morphology and rheology...
March 5, 2018: Chemistry, An Asian Journal
Yifei Jin, Yangyang Shen, Jun Yin, Jin Qian, Yong Huang
Stimuli-responsive hydrogels and/or composite hydrogels have been of great interest for various printing applications including four-dimensional (4D) printing. While various responsive hydrogels and/or composite hydrogels have been found to respond to given stimuli and change shapes as designed, the fabrication of three-dimensional (3D) structures from such responsive hydrogels is still a challenge due to their poor 3D printability, and most of responsive material-based patterns are two-dimensional (2D) in nature...
March 1, 2018: ACS Applied Materials & Interfaces
Radhika P Nagarkar, Stephen E Miller, Sheng Zhong, Darrin J Pochan, Joel P Schneider
The repetitive self-assembled structure of amyloid can serve as inspiration to design functional materials. Herein, we describe the design of α/β6, a peptide that contains distinct α-helical and β-structure forming domains. The folding and association state of each domain can be controlled by temperature. At low temperatures, the α-domain favors a coiled coil state while the β-domain is unstructured. Irreversible fibril formation via self-assembly of the β-domain is triggered at high temperatures where the α-domain is unfolded...
March 1, 2018: Protein Science: a Publication of the Protein Society
Zhaowei Chen, Zhenzhen Wang, Jinsong Ren, Xiaogang Qu
Bacterial infection continues to be a growing global health problem with the most widely accepted treatment paradigms restricted to antibiotics. However, antibiotics overuse and misuse have triggered increased multidrug resistance, frustrating the therapeutic outcomes and leading to higher mortalities. Even worse, the tendency of bacteria to form biofilms on living and nonliving surfaces further increases the difficulty in confronting bacteria because the extracellular matrix can act as a robust barrier to prevent the penetration of antibiotics and resist environmental stress...
February 28, 2018: Accounts of Chemical Research
Carles Otero, Mikel Aldaba, Silvia López, Fernando Díaz-Doutón, Fuensanta A Vera-Díaz, Jaume Pujol
PURPOSE: To study the accommodative dynamics for predictable and unpredictable stimuli using manual and automated accommodative facility tests Materials and Methods: Seventeen young healthy subjects were tested monocularly in two consecutive sessions, using five different conditions. Two conditions replicated the conventional monocular accommodative facility tests for far and near distances, performed with manually held flippers. The other three conditions were automated and conducted using an electro-optical system and open-field autorefractor...
February 28, 2018: Current Eye Research
Nureddin Ashammakhi, Outi Kaarela, Patrizia Ferretti
Much has already been done to achieve precisely controlled and customised regenerative therapies. Thanks to recent advances made in several areas relevant to regenerative medicine including the use of stimuli-responsive materials, 4-dimensional biofabrication, inducible pluripotent stem cells, control of stem cell fate using chemical and physical factors, minimal access delivery, and information-communication technology. In this short perspective, recent advances are discussed with a focus on a recent report on the use of mechanical stretching of nanoparticle-laden stem cells by using external magnetic field to induce defined cardiac line differentiation...
February 26, 2018: Journal of Craniofacial Surgery
Takehiro Hirao, Dong Sub Kim, Xiaodong Chi, Vincent M Lynch, Kazuaki Ohara, Jung Su Park, Kentaro Yamaguchi, Jonathan L Sessler
Recently, ligand-metal coordination, stimuli-responsive covalent bonds, and mechanically interlinked molecular constructs have been used to create systems with a large number of accessible structural states. However, accessing a multiplicity of states in sequence from more than one direction and doing so without the need for external energetic inputs remain as unmet challenges, as does the use of relatively weak noncovalent interactions to stabilize the underlying forms. Here we report a system based on a bispyridine-substituted calix[4]pyrrole that allows access to six different discrete states with directional control via the combined use of metal-based self-assembly and molecular recognition...
February 26, 2018: Nature Communications
Qingdi Zhu, Lihong Zhang, Krystyn J Van Vliet, Ali Miserez, Niels Holten-Andersen
Polymers that confer changes in optical properties in response to chemical or mechanical cues offer diverse sensing applications, particularly if this stimuli response is accessible in humid or aqueous environments. Here, luminescent hydrogels were fabricated using a facile aqueous process by incorporating lanthanide ions and carbon dots (CD) into a network of polyacrylamide and poly(acrylic acid). White luminescence was obtained by tuning the balance of blue light-emitting CD to green and red light-emitting lanthanide ions...
February 26, 2018: ACS Applied Materials & Interfaces
Sayantan Majumdar, Louis C Foucard, Alex J Levine, Margaret L Gardel
Understanding the response of complex materials to external force is central to fields ranging from materials science to biology. Here, we describe a novel type of mechanical adaptation in cross-linked networks of F-actin, a ubiquitous protein found in eukaryotic cells. We show that shear stress changes the network's nonlinear mechanical response even long after that stress is removed. The duration, magnitude and direction of forcing history all change this mechanical response. While the mechanical hysteresis is long-lived, it can be simply erased by force application in the opposite direction...
February 26, 2018: Soft Matter
Lei Zhou, Hao Wang, Yaping Li
Chemotherapy is still a main option for cancer therapy, but its efficacy is often unsatisfying due to multidrug resistance (MDR). The tumor microenvironment is considered a dominant factor causing MDR. Stimuli-responsive nanomedicines exhibit many superiorities for reversal of MDR. As smart systems, stimuli-responsive nanomedicines are desirable for achieving site-specific accumulation and triggered drug release in response to slight changes in physicochemical properties in pathological conditions or to exogenous stimuli...
2018: Theranostics
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