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stimuli responsive materials

Jakob Manhart, Santhosh Ayalur-Karunakaran, Simone Radl, Andreas Oesterreicher, Andreas Moser, Christian Ganser, Christian Teichert, Gerald Pinter, Wolfgang Kern, Thomas Griesser, Sandra Schlögl
The photo-reversible [4πs+4πs] cycloaddition reaction of pendant anthracene moieties represents a convenient strategy to impart wavelength dependent properties into hydrogenated carboxylated nitrile butadiene rubber (HXNBR) networks. The present article provides the (1)H NMR data on the reaction kinetics of the side chain functionalization of HXNBR. 2-(Anthracene-9-yl)oxirane with reactive epoxy groups is covalently attached to the polymer side chain of HXNBR via ring opening reaction between the epoxy and the carboxylic groups...
December 2016: Data in Brief
Elena Esra Foditsch, Reinhold Zimmermann
PURPOSE: The aim of this study was to develop a controlled approach for sacral neuromodulation (SNM) to improve both nerve targeting and tined lead placement, for which a new computed tomography (CT)-guided implantation technique was analyzed in minipigs. MATERIALS AND METHODS: This study included five female, adult Göttingen minipigs. In deep sedoanalgesia, the minipigs were placed in an extended prone position. Commercially available SNM materials were used (needle, introduction sheath, and quadripolar tined lead electrode)...
2016: Research and Reports in Urology
Jonas Kind, Lukas Kaltschnee, Martin Leyendecker, Christina M Thiele
Photochromic compounds like azobenzenes are widely used for the production of stimuli responsive materials. To analyse cascaded azobenzene switching inside a benzene-tricarboxamide (BTA) with three azobenzene moieties in a site-specific fashion, we used in situ irradiation NMR spectroscopy. Four photoisomers can be distinguished by their chemical shifts. Analysis of (1)H, (13)C and (15)N shifts reveals that the configuration of one sidechain has an influence on the chemical shifts of both the other sidechains...
October 13, 2016: Chemical Communications: Chem Comm
Gabriel S Longo, Monica Olvera de la Cruz, Igal Szleifer
The swelling/deswelling transition of pH-sensitive, electrode-grafted, hydrogel nanofilms when exposed to electric fields is studied by theoretical analysis. In acidic conditions, the response of these films to changes in pH is dominated by network-surface interactions, while intra-network electrostatic repulsions, which are highly modulated by the adsorption of salt ions, determine material response at a higher pH. Film thickness is a non-monotonic function of solution pH and displays a local maximum, a local minimum or both, depending on the salt concentration and the applied voltage...
October 12, 2016: Soft Matter
Gonzalo Prieto, Harun Tüysüz, Nicolas Duyckaerts, Johannes Knossalla, Guang-Hui Wang, Ferdi Schüth
Catalysis is at the core of almost every established and emerging chemical process and also plays a central role in the quest for novel technologies for the sustainable production and conversion of energy. Particularly since the early 2000s, a great surge of interest exists in the design and application of micro- and nanometer-sized materials with hollow interiors as solid catalysts. This review provides an updated and critical survey of the ever-expanding material architectures and applications of hollow structures in all branches of catalysis, including bio-, electro-, and photocatalysis...
October 7, 2016: Chemical Reviews
Syamal S Tallury, Behnam Pourdeyhimi, Melissa A Pasquinelli, Richard J Spontak
As emerging technologies continue to require diverse materials capable of exhibiting tunable stimuli-responsiveness, shape-memory materials are of considerable significance because they can change size and/or shape in controllable fashion upon environmental stimulation. Of particular interest, shape-memory polymers (SMPs) have secured a central role in the ongoing development of relatively lightweight and remotely deployable devices that can be further designed with specific surface properties. In the case of thermally-activated SMPs, two functional chemical species must be present to provide (i) an elastic network capable of restoring the SMP to a previous strain state and (ii) switching elements that either lock-in or release a temporary strain at a well-defined thermal transition...
October 6, 2016: Macromolecular Rapid Communications
Peet Cremer, Hartmut Löwen, Andreas M Menzel
Colloidal magnetic particles embedded in an elastic polymer matrix constitute a smart material called a ferrogel. It responds to an applied external magnetic field by changes in elastic properties, which can be exploited for various applications such as dampers, vibration absorbers, or actuators. Under appropriate conditions, the stress-strain behavior of a ferrogel can display a fascinating feature: superelasticity, the capability to reversibly deform by a huge amount while barely altering the applied load...
September 29, 2016: Physical Chemistry Chemical Physics: PCCP
Naveena Yanamala, Elena R Kisin, Autumn L Menas, Mariana T Farcas, Timur O Khaliullin, Ulla Vogel, Galina V Shurin, Diane Schwegler-Berry, Philip M Fournier, Alexander Star, Anna A Shvedova
A significant amount of research towards commercial development of cellulose based nanomaterials (CNM) is now in progress with some potential applications. Using human A549 and THP-1 cells, we evaluated the biological responses of various CNMs, made out of similar material but with functional and morphological variations. While A549 cells displayed minimal or no cytotoxic responses following exposure to CNMs, THP-1 cells were more susceptible to cytotoxicity, cellular damage and inflammatory responses. Further analysis of these biological responses evaluated using hierarchical clustering approaches was effective in discriminating (dis)-similarities of various CNMs studied and identified potential inflammatory factors contributing to cytotoxicity...
October 6, 2016: Biomacromolecules
John Joseph Keating, Joseph Imbrogno, Georges Belfort
The fundamentals and applications of polymer brush modified membranes are reviewed. This new class of synthetic membranes is explored with an emphasis on tuning the membrane performance through polymer brush grafting. This work highlights the intriguing performance characteristics of polymer brush modified membranes in a variety of separations. Polymer brushes are a versatile and effective means in designing membranes for applications in protein adsorption and purification, colloid stabilization, sensors, water purification, pervaporation of organic compounds, gas separations, and as stimuli responsive materials...
October 6, 2016: ACS Applied Materials & Interfaces
Angélica Cruz, Lorena García-Uriostegui, Alejandra Ortega, Takashi Isoshima, Guillermina Burillo
The aim of this study was to synthesize chitosan hydrogels, in macro- and nano-size, grafted with N-vinylcaprolactam (NVCL) using gamma radiation, and evaluate their potential application as a drug delivery system, using 5-fluorouracil (5-FU) as a model drug. The effect of dose and monomer concentration in the grafting process was studied, and the materials were characterized by FTIR, TGA, DLS, SEM and AFM. Higher grafting percentages were observed for the nanogels system. Although both the grafted macro- and nanogels, (net-CS)-g-NVCL, showed a response to pH (4...
January 2, 2017: Carbohydrate Polymers
Christian Ryan, Martina Stafford, Robert James King
Faces are one of the most socially significant visual stimuli encountered in the environment, whereas pareidolias are illusions of faces arising from ambiguous stimuli in the environment. Autism spectrum disorder (ASD) is characterised by deficits in response to social stimuli. We found that children with ASD (n = 60) identify significantly fewer pareidolic faces in a sequence of ambiguous stimuli than typically developing peers. The two groups did not differ in the number of objects identified, indicating that the children with ASD had a specific lack of attention to faces...
September 30, 2016: Journal of Autism and Developmental Disorders
M de-Pedro-Herráez, J Mesa-Jiménez, C Fernández-de-Las-Peñas, J-L de-la-Hoz-Aizpurua
Myogenic temporomandibular disorders (MTMD) frequently coexist with other clinical conditions in the same individual. In the last decades, several authors have analyzed these comorbidities looking for the origin of this overlapping. _Objetives: The aim of this study was to perform a comparative anaylisis between a group of patients with MTMD and a control group of dental patients without dysfunctional pathology to assess whether there are significant differences in the presence of systemic medical comorbidities between the two groups...
October 1, 2016: Medicina Oral, Patología Oral y Cirugía Bucal
Marta Maycas, Kevin A McAndrews, Amy Y Sato, Gretel G Pellegrini, Drew M Brown, Matthew R Allen, Lilian I Plotkin, Arancha R Gortazar, Pedro Esbrit, Teresita Bellido
There is an unmet need to understand the mechanisms underlying skeletal deterioration in diabetes mellitus (DM) and to develop therapeutic approaches to treat bone fragility in diabetic patients. We demonstrate herein that mice with type 1 DM induced by streptozotocin exhibited low bone mass, inferior mechanical and material properties, increased bone resorption, decreased bone formation, increased apoptosis of osteocytes, and increased expression of the osteocyte-derived bone formation inhibitor Sost/sclerostin...
September 28, 2016: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
Xi Lin, Bao Nguyen Quoc, Mathias Ulbricht
Stimuli-responsive membranes that can adjust mass transfer and interfacial properties "on demand" have drawn large interest over the last few decades. Here, we designed and prepared a novel magnetoresponsive separation membrane with remote switchable molecular sieving effect by simple one-step and scalable nonsolvent induced phase separation (NIPS) process. Specifically, poly(ether sulfone) (PES) as matrix for an anisotropic membrane, prefabricated poly(N-isopropylacrylamide) (PNIPAAm) nanogel (NG) particles as functional gates, and iron oxide magnetic nanoparticles (MNP) as localized heaters were combined in a synergistic way...
October 11, 2016: ACS Applied Materials & Interfaces
Giovanna Longhi, Ettore Castiglioni, Jun Koshoubu, Giuseppe Mazzeo, Sergio Abbate
We review the present status of experiments and calculations for circularly polarized luminescence (CPL) of simple organic molecules and of stimuli-responsive organic molecules. Together with the historical report of the main instrumental approaches, a few crucial points about experiments are tackled, with the aim of defining measurement protocols, in view of the wide availability of commercial apparatuses in the near future. The calculations aimed at interpreting the CPL spectra, mostly based on time-dependent Density Functional Theory (TD-DFT) calculations, which started around 2010, are reviewed, limiting the discussion to small to mid-sized molecules...
October 2016: Chirality
Kengo Manabe, Takeshi Matsubayashi, Mizuki Tenjimbayashi, Takeo Moriya, Yousuke Tsuge, KyuHong Kyung, Seimei Shiratori
Inspired by biointerfaces, such as the surfaces of lotus leaves and pitcher plants, researchers have developed innovative strategies for controlling surface wettability and transparency. In particular, great success has been achieved in obtaining low adhesion and high transmittance via the introduction of a liquid layer to form liquid-infused surfaces (LISs). Furthermore, smart surfaces that can change their surface properties according to external stimuli have recently attracted substantial interest. As some of the best-performing smart surface materials, slippery liquid-infused porous surfaces (SLIPSs), which are super-repellent, demonstrate the successful achievement of switchable adhesion and tunable transparency that can be controlled by a graded mechanical stimulus...
September 23, 2016: ACS Nano
Sachin Kumar, Kaushik Chatterjee
Recent research suggests that graphene holds great potential in the biomedical field because of its extraordinary properties. Whereas initial attempts focused on the use of suspended graphene for drug delivery and bioimaging, more recent work has demonstrated its advantages for preparing substrates for tissue engineering and biomedical devices and products. Cells are known to interact with and respond to nanoparticles differently when presented in the form of a substrate than in the form of a suspension. In tissue engineering, a stable and supportive substrate or scaffold is needed to provide mechanical support, chemical stimuli, and biological signals to cells...
October 4, 2016: ACS Applied Materials & Interfaces
Zhen Wu, Kai Pan, Baozhong Lü, Le Ma, Wantai Yang, Meizhen Yin
Spiropyran (SP), which can respond to acid, ultraviolet irradiation, and mechanical force, has received great attention as a classic molecule for the construction of stimuli-responsive materials. However, the self-assembly behavior of SP with a tunable morphology has rarely been investigated. In the present work, a SP derivative bearing two carboxyl groups and one hydroxyl group was prepared and used as a model to investigate the optical properties, molecular self-assembly, and morphology of SP. This pH-responsive derivative could undergo a large morphology variation from a sphere- to a rodlike structure by adjusting the acidity...
September 20, 2016: Chemistry, An Asian Journal
Amin GhavamiNejad, Melisa SamariKhalaj, Ludwig Erik Aguilar, Chan Hee Park, Cheol Sang Kim
This study reports on an intelligent composite hydrogel with both pH-dependent drug release in a cancer environment and heat generation based on NIR laser exposure, for the combined application of photothermal therapy (PTT) and multidrug chemotherapy. For the first time in the literature, Dopamine nanoparticle (DP) was incorporated as a highly effective photothermal agent as well as anticancer drug, bortezomib (BTZ) carrier inside a stimuli responsive pNIPAAm-co-pAAm hydrogel. When light is applied to the composite hydrogel, DP nanoparticle absorbs the light, which is dissipated locally as heat to impact cancer cells via hyperthermia...
2016: Scientific Reports
C Dispenza, G Spadaro, M Jonsson
Nanogels combine the favourable properties of hydrogels with those of colloids. They can be soft and conformable, stimuli-responsive and highly permeable, and can expose a large surface with functional groups for conjugation to small and large molecules, and even macromolecules. They are among the very few systems that can be generated and used as aqueous dispersions. Nanogels are emerging materials for targeted drug delivery and bio-imaging, but they have also shown potential for water purification and in catalysis...
October 2016: Top Curr Chem (J)
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