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stimuli responsive materials

Luca Nucara, Vincenzo Piazza, Francesco Greco, Valentina Robbiano, Valentina Cappello, Mauro Gemmi, Franco Cacialli, Virgilio Mattoli
Stimuli-responsive photonic crystals (PCs) represent an intriguing class of smart materials very promising for sensing applications. Here, selective ionic strength responsive polymeric PCs are reported. They are easily fabricated by partial sulfonation of polystyrene opals, without using toxic or expensive monomers and etching steps. The color of the resulting hydrogel-like ordered structures can be continuously shifted over the entire visible range (405-760 nm) by changing the content of ions over an extremely wide range of concentration (from about 70 M to 4 M)...
January 12, 2017: ACS Applied Materials & Interfaces
Ji Liu, Yang Lan, Ziyi Yu, Cindy S Y Tan, Richard M Parker, Chris Abell, Oren A Scherman
Microencapsulation is a fundamental concept behind a wide range of daily applications ranging from paints, adhesives, and pesticides to targeted drug delivery, transport of vaccines, and self-healing concretes. The beauty of microfluidics to generate microcapsules arises from the capability of fabricating monodisperse and micrometer-scale droplets, which can lead to microcapsules/particles with fine-tuned control over size, shape, and hierarchical structure, as well as high reproducibility, efficient material usage, and high-throughput manipulation...
January 11, 2017: Accounts of Chemical Research
Zhaoxia Qian, Kathryn N Guye, David J Masiello, David S Ginger
Responsive plasmonic nanomaterials composed of gold nanoparticles (AuNPs) and temperature-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogels offer the promise of designing smart materials that can change color in response to varying thermal, or photothermal stimuli. Typical AuNP/PNIPAM hybrids are heavily loaded with AuNPs. Here we demonstrate that PNIPAM spheres with small number AuNP loadings exhibit significant extinction shifts and a broad range of color changes with varying temperature. Hybrids with an average loading of 3 to 5 AuNPs per PNIPAM sphere exhibit peak extinction shifts of over 150 nm and color change from red to purple to gray, with very large extinction changes in the NIR, as the temperature increases from 25oC to 50oC...
January 11, 2017: Journal of Physical Chemistry. B
Andrew M Bodratti, Biswajit Sarkar, Paschalis Alexandridis
The adsorption of amphiphilic molecules of varying size on solid-liquid interfaces modulates the properties of colloidal systems. Nonionic, poly(ethylene oxide) (PEO)-based amphiphilic molecules are particularly useful because of their graded hydrophobic-hydrophilic nature, which allows for adsorption on a wide array of solid surfaces. Their adsorption also results in other useful properties, such as responsiveness to external stimuli and solubilization of hydrophobic compounds. This review focuses on the adsorption properties of PEO-based amphiphiles, beginning with a discussion of fundamental concepts pertaining to the adsorption of macromolecules on solid-liquid interfaces, and more specifically the adsorption of PEO homopolymers...
September 28, 2016: Advances in Colloid and Interface Science
Qun Wang, Jian-Ying Huang, Hua-Qiong Li, Allan Zi-Jian Zhao, Yi Wang, Ke-Qin Zhang, Hong-Tao Sun, Yue-Kun Lai
To address the limitations of traditional drug delivery, TiO2 nanotubes (TNTs) are recognized as a promising material for localized drug delivery systems. With regard to the excellent biocompatibility and physicochemical properties, TNTs prepared by a facile electrochemical anodizing process have been used to fabricate new drug-releasing implants for localized drug delivery. This review discusses the development of TNTs applied in localized drug delivery systems, focusing on several approaches to control drug release, including the regulation of the dimensions of TNTs, modification of internal chemical characteristics, adjusting pore openings by biopolymer coatings, and employing polymeric micelles as drug nanocarriers...
2017: International Journal of Nanomedicine
Graham A Ferrier, Cheryl Ann Zimmer, Richard K Zimmer
Wave-swept shores are valuable for developing and testing key ecological principles. A synthesis of research is nonetheless missing a critical component: the chemosensory basis for behavioral interactions that determine population- and community-wide attributes. Chemical signaling environments on wave-swept shores, given their intense, turbulent mixing and complex topographies, would be difficult or impossible to simulate in a laboratory setting. For this reason, appropriately scaled field studies are needed to advance understanding of chemical stimuli and their biotic effects...
December 2016: Biological Bulletin
Xiaoliang Qi, Junjian Li, Wei Wei, Ting Su, Gancheng Zuo, Xihao Pan, Jianfa Zhang, Wei Dong
Salecan is a water-soluble bacterial polysaccharide consisting of glucopyranosyl units linked by α-1,3 and β-1,3 glycosidic bonds. salecan is suitable for the development of hydrogels for biomedical applications, given its outstanding physicochemical and biological profiles. In this study we designed a new semi-interpenetrating polymer network hydrogel that introduces the salecan polysaccharide into a stimuli-responsive poly(2-acrylamido-2-methylpropanosulfonic acid-co-[2-(methacryloxy)ethyl]trimethylammonium chloride) (PAM) hydrogel matrix for controlled insulin release...
January 3, 2017: ChemMedChem
Sheng Li, Ling Xiao, Hongbing Deng, Xiaowen Shi, Qihua Cao
The construction of multifunctional microspheres for remote controlled drug release requires the exquisite selection of composite materials and preparation approaches. In this study, chitosan, an amino polysaccharide, was blended with inorganic nanocomponents, Fe3O4 and graphene oxide (GO) and electrosprayed to fabricate uniform microspheres with the diameters ranging from 100μm to 1100μm. An anti-cancer drug, doxorubicin (DOX), was loaded to the microspheres by an adsorption or embedding method. The microsphere is responsive to magnetic fields due to the presence of Fe3O4, and the incorporation of GO enhanced the drug loading capacity...
December 23, 2016: Colloids and Surfaces. B, Biointerfaces
Alessio Tommasi, Matteo Cocuzza, Denis Perrone, Candido Fabrizio Pirri, Roberto Mosca, Marco Villani, Nicola Delmonte, Andrea Zappettini, Davide Calestani, Simone Luigi Marasso
In the sensors field the active sensing material frequently needs a controlled temperature in order to work properly. In microsystems technology, micro-machined hotplates represent a platform consisting of a thin suspended membrane where the sensing material can be deposited, usually integrating electrical stimuli and temperature readout. The micro-hotplate ensures a series of advantages such as miniaturized size, fast response, high sensitivity, low power consumption and selectivity for chemical sensing. This work compares the coplanar and the buried approach for the micro-hotplate heaters design with the aim to optimize the fabrication process and to propose a guideline for the choice of the suitable design with respect to the applications...
December 30, 2016: Sensors
Qiang Matthew Zhang, Michael Serpe
A variety of stimuli-responsive polymers have been developed and used as actuators and/or artificial muscles, with the movement being driven by an external stimulus, e.g., electrical potential. This review highlights actuators constructed from liquid crystal elastomers, dielectric elastomers, ionic polymers, and conducting polymers. This review covers recent examples of a variety of actuators generated from these materials and their utility. The mechanism of actuation will be detailed for most examples in order to stimulate possible future research, and lead to new applications and advanced applications...
January 1, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Sytze J Buwalda, Tina Vermonden, Wim E Hennink
Hydrogels are attractive materials for the controlled release of therapeutics because of their capacity to embed biologically active agents in their water-swollen network. Recent advances in organic and polymer chemistry, bio-engineering and nanotechnology have resulted in several new developments in the field of hydrogels for therapeutic delivery. In this Perspective, we present our view on the state-of-the-art in the field, thereby focusing on a number of exciting topics, including bioorthogonal crosslinking methods, multi-component hydrogels, stimuli-responsive hydrogels, nanogels and the release of therapeutics from 3D printed hydrogels...
December 27, 2016: Biomacromolecules
Yan Liu, Kaihuan Zhang, Jinghong Ma, G Julius Vancso
Hydrogels with rapid and strong response to external stimuli and possessing high elasticity and strength have been considered as platform materials for numerous applications, e.g., in biomaterials engineering. Thermoresponsive hydrogels based on semi-interpenetrating polymer networks (semi-IPN) featuring N-isopropylacrylamide with copolymers of poly(N-isopropylacrylamide-co-hydroxyethyl methacrylate) p(NIPAM-HEMA) chains are prepared and described. The copolymer was characterized by FTIR, NMR, and GPC. The semi-IPN structured hydrogel and its responsive properties were evaluated by dynamic mechanical measurements, SEM, DSC, equilibrium swelling ratio, and dynamic deswelling tests...
December 27, 2016: ACS Applied Materials & Interfaces
André Wannemueller, Dirk Adolph, Hans-Peter Joehren, Simon E Blackwell, Jürgen Margraf
Psychophysiological responses indicating the preparation of defensive behaviour, such as heart rate (HR)-increase and startle-response (SR) potentiation, have often been reported amongst individuals suffering from phobic disorders when exposed to phobia-related information. Although exposure is widely considered the 'gold standard' for treatment of Specific Phobia, it is unclear to what extent psychophysiological defensive response patterns change following treatment, and whether any changes are maintained...
December 14, 2016: Behaviour Research and Therapy
Xiaofei Liu, Jan Hermann, Alexandre Tkatchenko
Stimuli-responsive metal-organic frameworks (MOFs) and other framework materials exhibit a broad variety of useful properties, which mainly stem from an interplay of strong covalent bonds within the organic linkers with presumably weak van der Waals (vdW) interactions which determine the overall packing of the framework constituents. Using Ag3Co(CN)6 as a fundamental test case-a system with a colossal positive and negative thermal expansion [A. L. Goodwin et al., Science 319, 794 (2008)]-we demonstrate that its structure, stability, dielectric, vibrational, and mechanical properties are critically influenced by many-body electronic correlation contributions to non-covalent vdW interactions...
December 28, 2016: Journal of Chemical Physics
Ziwen Dai, Hoi Man Leung, Pik Kwan Lo
Stimuli-responsive DNA-based materials represent a major class of remarkable functional nanomaterials for nano-biotechnological applications. In this review, recent progress in the development of stimuli-responsive systems based on self-assembled DNA nanostructures is introduced and classified. Representative examples are presented in terms of their design, working principles and mechanisms to trigger the response of the stimuli-responsive DNA system upon expose to a large variety of stimuli including pH, metal ions, oligonucleotides, small molecules, enzymes, heat, and light...
December 22, 2016: Small
He Ma, Jiwei Hou, Xuewen Wang, Jin Zhang, Zhiquan Yuan, Lin Xiao, Yang Wei, Shoushan Fan, Kaili Jiang, Kai Liu
Flexible actuators responsive to multiple stimuli are much desired in wearable electronics. However, general designs containing organic materials are usually subject to slow response and limited lifetime, or high triggering threshold. In this study, we develop flexible, all-inorganic actuators based on bimorph structures composed of vanadium dioxide (VO2) and carbon nanotube (CNT) thin films. The drastic, reversible phase transition of VO2 drives the actuators to deliver giant amplitude, fast response up to ∼100 Hz, and long lifetime more than 1 000 000 actuation cycles...
December 27, 2016: Nano Letters
Kizhisseri Devi Renuka, C Lalitha Lekshmi, Kuruvilla Joseph, Sankarapillai Mahesh
Tuning the microstructure, conductance, band gap of a single molecule with an external stimuli such as light have vital importance in nanoscale molecular electronics. Azobenzene systems are inimitable light responsive molecules suitable for the development of optically modulated materials. In this work we have demonstrated the development of an optically active Multiwalled Carbon Nanotube (MWCNT)-hybrid material by the noncovalent functionalization of azo based chromophore derived from cardanol, a bioresource material...
December 21, 2016: ACS Applied Materials & Interfaces
Rui Wang, Michelle K Sing, Reginald K Avery, Bruno S Souza, Minkyu Kim, Bradley D Olsen
Polymer networks are widely used from commodity to biomedical materials. The space-spanning, net-like structure gives polymer networks their advantageous mechanical and dynamic properties, the most essential factor that governs their responses to external electrical, thermal, and chemical stimuli. Despite the ubiquity of applications and a century of active research on these materials, the way that chemistry and processing interact to yield the final structure and the material properties of polymer networks is not fully understood, which leads to a number of classical challenges in the physical chemistry of gels...
December 20, 2016: Accounts of Chemical Research
Peijun Guo, Matthew S Weimer, Jonathan D Emery, Benjamin T Diroll, Xinqi Chen, Adam S Hock, Robert P H Chang, Alex B F Martinson, Richard D Schaller
Actively tunable optical transmission through artificial metamaterials holds great promise for next-generation nanophotonic devices and metasurfaces. Plasmonic nanostructures and phase change materials have been extensively studied to this end due to their respective strong interactions with light and tunable dielectric constants under external stimuli. Seamlessly integrating plasmonic components with phase change materials, as demonstrated in the present work, can facilitate phase change by plasmonically enabled light confinement and meanwhile make use of the high sensitivity of plasmon resonances to the variation of dielectric constant associated with the phase change...
December 19, 2016: ACS Nano
Janette C Schult, Melanie C Steffens
The intention-superiority effect denotes faster response latencies to stimuli linked with a prospective memory task compared to stimuli linked with no prospective task or with a cancelled task. It is generally assumed that the increased accessibility of intention-related materials contributes to successful execution of prospective memory tasks at an appropriate opportunity. In two experiments we investigated the relationship between the intention-superiority effect and actual prospective memory performance under relatively realistic conditions...
December 15, 2016: Memory & Cognition
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