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stimuli responsive materials

Shrikrishnan Sankaran, Leena Jaatinen, Jenny Brinkmann, Tomaso Zambelli, Janos Vörös, Pascal Jonkheijm
Biomimetic and stimuli-responsive cell-material interfaces are actively being developed to study and control various cell-dynamics phenomena. Since cells naturally reside in the highly dynamic and complex environment of the extracellular matrix, attempts are being made to replicate these conditions in synthetic biomaterials. Supramolecular chemistry, dealing with non-covalent interactions, has recently provided possibilities to incorporate such dynamicity and responsiveness in various types of architectures...
March 20, 2017: ACS Nano
Yingjie Wu, Kai Wang, Shuo Huang, Cangjie Yang, Mingfeng Wang
Near-infrared (NIR) light-responsive hydrogels are important for biomedical applications such as remotely controlled release, but the NIR agents previously used have been largely limited to heavy-metal inorganic materials such as gold nanoparticles. In this article, we report a new type of NIR photothermal responsive hydrogels, which could undergo structural changes in response to NIR light for biomedical applications in drug delivery and controlled release. The hydrogels synthesized by integrating a narrow bandgap semiconductor polymer poly(diketopyrrolopyrrole-alt-3,4-ethylenedioxythiophene) (PDPPEDOT) with polymerization of N-isopropylacrylamide (NIPAM) show rapid and reversible mechanical shrinkage upon NIR light irradiation and can serve as carriers for anticancer drug loading and spatial/temporal control of drug release...
March 17, 2017: ACS Applied Materials & Interfaces
Jingyi Zong, Steven L Cobb, Neil R Cameron
Colloidal gold solutions have been used for centuries in a wide variety of applications including staining glass and in the colouring of ceramics. More recently, gold nanoparticles (GNPs) have been studied extensively due to their interesting size-dependent electronic and optical properties. GNPs can be functionalized easily with biomolecules that contain thiols, amines, or even phosphine moieties. For example, the reaction of thiol-containing peptides with GNPs has been used extensively to prepare novel hybrid materials for biomedical applications...
March 17, 2017: Biomaterials Science
Nuria Oliva, João Conde, Kui Wang, Natalie Artzi
Systemic administration of therapeutic agents has been the preferred approach to treat most pathological conditions, in particular for cancer therapy. This treatment modality is associated with side effects, off-target accumulation, toxicity, and rapid renal and hepatic clearance. Multiple efforts have focused on incorporating targeting moieties into systemic therapeutic vehicles to enhance retention and minimize clearance and side effects. However, only a small percentage of the nanoparticles administered systemically accumulate at the tumor site, leading to poor therapeutic efficacy...
March 16, 2017: Accounts of Chemical Research
Huanhuan Xing, Xiaowei Zhang, Qingfeng Zhai, Jing Li, Erkang Wang
A highly efficient fluorescence switch system based on closed bipolar electrode (C-BPE) system was proposed for the first time. Here, Au nanoclusters (Au NCs) were pre-modified on one pole of the BPE and acted as the fluorescent donor. Based on the spectral overlap between the absorbance of electrochromic material-Prussian blue (PB) and fluorescence spectrum of Au NCs, fluorescence quenching ("off" state) induced by inner filter effect was observed. Due to the electrochemical reversible redox reaction between PB and Prussian white, switching the polarity of driving voltage could easily achieve the fluorescence recovery of the Au NCs, corresponding to the "on" state...
March 13, 2017: Analytical Chemistry
Lily Tao, Marcus Taft
Foreign accent in speech often presents listeners with challenging listening conditions. Consequently, listeners may need to draw on additional cognitive resources in order to perceive and comprehend such speech. Previous research has shown that, for older adults, executive functions predicted perception of speech material spoken in a novel, artificially created (and therefore unfamiliar) accent. The present study investigates the influences of executive functions, information processing speed, and working memory on perception of unfamiliar foreign accented speech, in healthy young adults...
2017: Frontiers in Psychology
Shivaranjan Raghuraman, Meagan B Elinski, James D Batteas, Jonathan R Felts
Driving and measuring chemical reactions at the nanoscale is crucial for developing safer, more efficient and environ-ment-friendly reactors and for surface engineering. Quantitative understanding of surface chemical reactions in real operating environments is challenging due to resolution and environmental limitations of existing techniques. Here we report an atomic force microscope technique that can measure reaction kinetics driven at the nanoscale by multi-physical stimuli in an ambient environment. We demonstrate the technique by measuring local reduction of graphene oxide as a function of both temperature and force at the sliding contact...
March 10, 2017: Nano Letters
Sergey V Ovsyannikov, Natalia V Morozova, Igor V Korobeinikov, Vasyl Haborets, Ruslan Yevych, Yulian Vysochanskii, Vladimir V Shchennikov
External stimuli enabling either a continuous tuning or an abrupt switching of the basic properties of materials that are utilized in various industrial appliances could significantly extend their range of use. The key characteristics of semiconductors are basically linked to their electronic and optical properties. In this study, we experimentally demonstrated that two kindred wide-band-gap semiconductors, ferroelectric Sn2P2Se6 and paraelectric Pb2P2S6, which are commonly used in optical technologies, have remarkably different and unusual responses in their electronic band structures to applied moderate pressures...
March 10, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Haiqing Li, Matthew R Hill
Groundbreaking research over the past 15 years has established metal-organic frameworks (MOFs) as adsorbents capable of unprecedented gas adsorption capacity. This has encouraged the contemplation of their use in applications such as increasing the storage capacity in natural gas fuel tanks, or the capture of carbon dioxide from coal-fired flue gas streams. However, while the gas adsorption capacity of MOFs is large, not all stored gas can be readily released to realize the efficient regeneration of MOF adsorbents...
March 8, 2017: Accounts of Chemical Research
Assaf J Harnoy, Marina Buzhor, Einat Tirosh, Rona Shaharabani, Roy Beck, Roey J Amir
Self-assembled nanostructures and their stimuli-responsive degradation have been recently explored to meet the increasing need for advanced biocompatible and biodegradable materials for various biomedical applications. Incorporation of enzymes as triggers that can stimulate the degradation and disassembly of polymeric assemblies may be highly advantageous owing to their high selectivity and natural abundance in all living organisms. One of the key factors to consider when designing enzyme-responsive polymers is the ability to fine-tune the sensitivity of the platform toward its target enzyme in order to control the disassembly rate...
March 21, 2017: Biomacromolecules
Hyunhyub Ko, Ali Javey
Biological systems found in nature provide excellent stimuli-responsive functions. The camouflage adaptation of cephalopods (octopus, cuttlefish), rapid stiffness change of sea cucumbers, opening of pine cones in response to humidity, and rapid closure of Venus flytraps upon insect touch are some examples of nature's smart systems. Although current technologies are still premature to mimic these sophisticated structures and functions in smart biological systems, recent work on stimuli-responsive programmable matter has shown great progress...
March 6, 2017: Accounts of Chemical Research
Daewoo Han, Xinjun Yu, Qinyuan Chai, Neil Ayres, Andrew J Steckl
The first self-immolative polymer (SIP) nanofiber membrane have been demonstrated in this report, which the immolation can be triggered by external stimulus. Electrospun SIP/PAN fibers provide ~ 25 times quicker and more responsive depolymerization (i.e. immolation) than a cast film in the triggering condition. Depolymerization of SIP in the SIP/PAN blended fiber membrane results in the transition of the surface properties from hydrophobic (~110º) to hygroscopic (~ 0º). Triggered release of encapsulated functional molecules has been demonstrated using coaxially electrospun fiber membrane made of SIP/PAN blend sheath and PVP/dye core...
March 6, 2017: ACS Applied Materials & Interfaces
Sun-Je Kim, Hansik Yun, Kyungsoo Park, Jongwoo Hong, Jeong-Geun Yun, Kyookeun Lee, Joonsoo Kim, Sun Jae Jeong, Sang-Eun Mun, Jangwoon Sung, Yong Wook Lee, Byoungho Lee
Active switching of near-field directivity, which is an essential functionality for compact integrated photonics and small optoelectronic elements, has been challenging due to small modulation depth and complicated fabrication methods for devices including active optical materials. Here, we theoretically and experimentally realize a nanoscale active directional switching of surface plasmon polaritons (SPPs) using a phase transition material for the first time. The SPP switching device with noticeable distinction is demonstrated based on the phase transition of vanadium dioxide (VO2) at the telecom wavelength...
March 6, 2017: Scientific Reports
Asja Pettignano, Santiago Grijalvo, Marleen Häring, Ramon Eritja, Nathalie Tanchoux, Françoise Quignard, David Díaz Díaz
One-step functionalization of alginate with boronic acid groups allowed spontaneous formation of biocompatible hydrogels under basic conditions without additional complementary molecules or crosslinking agents. The dynamic nature of boronate ester bonds formed with vicinal diols present on alginate pyranose rings provided remarkable self-healing, injectable and multi-stimuli responsive properties to the material.
March 6, 2017: Chemical Communications: Chem Comm
Hajime Shigemitsu, Itaru Hamachi
Stimuli-responsive hydrogels are intriguing biomaterials useful for spatiotemporal controlled release of drugs, cells, and biological cues, cell engineering for various applications, and medical diagnosis. To date, many physical and chemical stimuli-responsive polymer hydrogels have been developed by chemical modification of polymer chains and cross-linking points. In particular, conjugation with biomolecules to polymers produced promising biomolecule-responsive hydrogels. These examples clearly indicate high potentials of stimuli-responsive hydrogels as promising biomaterials...
March 2, 2017: Accounts of Chemical Research
David Gräfe, Philipp Frank, Tim Erdmann, Andreas Richter, Dietmar Appelhans, Brigitte Voit
Stimuli-responsive hydrogels combine sensor and actuator properties by converting an environmental stimulus into mechanical work. Those materials are highly interesting for applications as a chemomechanical valve in microsystem technologies. However, studies about key characteristics of hydrogels for this application are comparatively rare, and further research is needed to emphasize their real potential. The first part of this study depicts the synthesis of grafted hydrogels based on a poly(N-isopropylacrylamide) backbone and pH-sensitive poly(acrylic acid) graft chains...
March 1, 2017: ACS Applied Materials & Interfaces
Jason S Kahn, Yuwei Hu, Itamar Willner
The base sequence of nucleic acids encodes structural and functional information into the DNA biopolymer. External stimuli such as metal ions, pH, light, or added nucleic acid fuel strands provide triggers to reversibly switch nucleic acid structures such as metal-ion-bridged duplexes, i-motifs, triplex nucleic acids, G-quadruplexes, or programmed double-stranded hybrids of oligonucleotides (DNA). The signal-triggered oligonucleotide structures have been broadly applied to develop switchable DNA nanostructures and DNA machines, and these stimuli-responsive assemblies provide functional scaffolds for the rapidly developing area of DNA nanotechnology...
March 1, 2017: Accounts of Chemical Research
Danielle VanMensel, Subba Rao Chaganti, Ryan Boudens, Thomas Reid, Jan Ciborowski, Christopher Weisener
Open-pit mining of the Athabasca oil sands has generated large volumes of waste termed fluid fine tailings (FFT), stored in tailings ponds. Accumulation of toxic organic substances in the tailings ponds is one of the biggest concerns. Gamma irradiation (GI) treatment could accelerate the biodegradation of toxic organic substances. Hence, this research investigates the response of the microbial consortia in GI-treated FFT materials with an emphasis on changes in diversity and organism-related stimuli. FFT materials from aged and fresh ponds were used in the study under aerobic and anaerobic conditions...
March 1, 2017: Microbial Ecology
Wei-Chen Huang, Faisal Ali, Jingsi Zhao, Kelsey Rhee, Chenchen Mou, Christopher J Bettinger
Stimulus-responsive hydrogels make up an important class of programmable materials for a wide range of biomedical applications. Ultrasound (US) is a stimulus that offers utility because of its ability to permeate tissue and rapidly induce chemical alterations in aqueous media. Here we report on the synthesis and US-mediated disintegration of stimulus-responsive telechelic Dopa-modified polyethylene glycol-based hydrogels. Fe(3+)-[PEG-Dopa]4 hydrogels are formed through Fe(3+)-induced cross-linking of four-arm polyethylene glycol-dopamine precursors to produce networks...
March 9, 2017: Biomacromolecules
William A Morris, Tristan Butler, Milena Kolpaczynska, Cassandra L Fraser
Difluoroboron β-diketonate (BF2bdk) compounds exhibit solid-state switchable luminescence under excitation by UV light. This property is usually manifested as a blue-shift in emission when dye films are thermally annealed followed by a red-shift in response to mechanical shear (i.e. mechanochromic luminescence). Here we report thiophene and furan heterocycle-substituted dyes bearing short methoxy and long dodecyloxy chain substituents. Optical properties of the dyes were investigated in solution, pristine powders, and films on paper and glass...
January 1, 2017: Mater Chem Front
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