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stimuli responsive materials

Raquel Garcia, Marco D R Gomes da Silva, Maria João Cabrita
Sample preparation still remains a great challenge in the analytical workflow representing the most time-consuming and laborious step in analytical procedures. Ideally, sample pre-treatment procedures must be more selective, cheap, quick and environmental friendly. Molecular imprinting technology is a powerful tool in the development of highly selective sample preparation methodologies enabling to preconcentrate the analytes from a complex food matrix. Actually, the design and development of molecularly imprinted polymers-based functional materials that merge an enhancement of selectivity with a controllable and switchable mode of action by means of specific stimulus constitutes a hot research topic in the field of food analysis...
January 1, 2018: Talanta
Natalie L Colich, Tiffany C Ho, Lara C Foland-Ross, Caitlin Eggleston, Sarah J Ordaz, Manpreet K Singh, Ian H Gotlib
BACKGROUND: Individuals with Major Depressive Disorder (MDD) are characterized by biases in attention to negative emotional material. While there is evidence that anomalous functioning in frontocingulate regions may underlie these biases, we know little about the neural correlates of negative emotional biases in depressed adolescents. METHODS: Eighteen adolescents diagnosed with MDD and 21 matched healthy control (CTL) adolescents underwent fMRI while performing an emotional distractor task...
July 2017: Biological Psychiatry: Cognitive Neuroscience and Neuroimaging
Wei Zheng, Guang Yang, Nannan Shao, Li-Jun Chen, Bo Ou, Shu-Ting Jiang, Guosong Chen, Hai-Bo Yang
Supramolecular polymeric gels cross-linked by well-defined, discrete metal-organic macrocycles (MOMs) or metal-organic cages (MOCs) have become a prevailing topic within the field of supramolecular self-assembly. However, the realization of supramolecular polymeric hydrogels cross-linked by discrete organometallic architectures with good biocompatibility is still a great challenge. Herein, we present the successful preparation of CO2 stimuli-responsive, injectable block copolymer hydrogels cross-linked by discrete organoplatinum(II) metallacycles...
September 8, 2017: Journal of the American Chemical Society
Xiao Zhou, Xiaoye Su, Pravin Pathak, Ryan Vik, Brittany Vinciguerra, Lyle Isaacs, Janarthanan Jayawickramarajah
Host-guest complexes are emerging as powerful components in functional systems with applications ranging from materials to biomedicine. In particular, CB7 based host-guest complexes have received much attention for the controlled release of drugs due to the remarkable ability of CB7 toward binding input molecules in water with high affinity leading to displacement of CB7 from included pharmacophores (or from drug loaded porous particles). However, the release of bound guests from CB7 in response to endogenous biological molecules remains limited since the input biomolecule needs to have the appropriate chemical structure to bind tightly into the CB7 cavity...
September 7, 2017: Journal of the American Chemical Society
Ning Zhou, Zeyuan Cao, Bing Xu
Crosslinking is an essential architecture for polymers to improve mechanical and thermal properties and to form three-dimensional (3D) structures. Although conventional synthetic crosslinkers usually only serve as bridges between different polymeric chains, biological crosslinkers are multifunctional. Recently, crosslinkers with active functionality after polymerization are promising a new dimension of molecular design for generating smart materials as they may exhibit dramatic changes in structures and properties in response to external stimuli...
September 7, 2017: Chemistry: a European Journal
Guoxing Liu, Ying-Ming Zhang, Conghui Wang, Yu Liu
The research in photochromic molecules switched by visible light are of particular significance for their application in bioimaging and stimuli-responsive materials. Here, a photoswitchable supramolecular assembly comprised of monocharged bispyridinium-modified diarylethenes (DAEs) and cucurbit[8]uril (CB[8]) has been constructed, exhibiting reversible photochromic behaviours with visible light in both directions. The intervention of CB[8] not only prompts the DAEs to form charge-transfer complex, but also restricts its intramolecular rotation to enhance fluorescence emission...
September 6, 2017: Chemistry: a European Journal
Siheng Gao, Lijie Li, Ismail Vohra, Daijun Zha, Lei You
As one of common dynamic covalent bonds, acylhydrazone bond plays an important role in developing intelligent responsive materials. In this report, we present acylhydrazone-based dynamic polymers with multi-stimuli responsiveness, particularly metal recognition behaviours and their modulation. A series of polyacylhydrazones with different metal-binding sites were designed and prepared in a modular fashion. Titration of these receptors with a diverse set of metal ions, including Cu(2+), Zn(2+) and La(3+), resulted in unique optical changes, and both the sensitivity and selectivity profiles can be regulated...
August 2017: Royal Society Open Science
Jianzhong Jiang, Duyan Zhang, JinChao Yin, Zhenggang Cui
A dual-stimuli responsive, wormlike micelle system was developed using a switchable selenium-containing surfactant, dihendecylcarboxylic acid sodium selenide (C11-Se-C11), and a commercially available surfactant, cetyltrimethyl ammonium bromide (CTAB). The solution showed a viscoelastic characteristic at low shear frequencies, and the synergism was significant when the concentrations of CTAB and C11-Se-C11 were 145 mM and 25 mM, respectively. Additionally, the system was fast and reversibly responded to CO2 and redox dual stimuli, and it showed a circulatory gel/sol transition, which reflected changes in the self-assembly from entangled worms to rodlike micelles...
September 6, 2017: Soft Matter
Jian Li, Zhihong Zhao, Dianming Li, Haifeng Tian, Fei Zha, Hua Feng, Lin Guo
Oil/water separation is of great importance for the treatment of oily wastewater, including immiscible light/heavy oil-water mixtures, oil-in-water or water-in-oil emulsions. Smart surfaces with responsive wettability have received extensive attention especially for controllable oil/water separation. However, traditional smart membranes with a switchable wettability between superhydrophobicity and superhydrophilicity are limited to certain responsive materials and continuous external stimuli, such as pH, electrical field or light irradiation...
September 6, 2017: Nanoscale
Yan Sheng, Jiaming Hu, Junfeng Shi, Ly James Lee
Stimuli-responsive carriers are a class of drug delivery systems which can change their physicochemical properties and/or structural conformations in response to specific stimuli. Although passive and active drug targeting has proved to reduce the side effects to normal cells, controlled intracellular drug release should be included in drug carriers to enhance the bioavailability of drugs at the disease site. This review focuses on several recent advances in the development of stimuli-responsive carriers for spatially and temporally controlled release of therapeutic agents in response to intracellular stimuli, such as pH, redox potential, reactive oxygen species, enzyme and temperature...
August 29, 2017: Current Medicinal Chemistry
L E Matolyak, J K Keum, K M Van de Voorde, L T J Korley
Nature has achieved diverse functionality via hierarchical organization driven by physical interactions such as hydrogen bonding. Synthetically, polymer-peptide hybrids have been utilized to achieve these architectural arrangements and obtain diverse mechanical properties, stimuli responsiveness, and bioactivity. Here, we explore the impact of peptide ordering and soft/hard phase interactions in PEG-based non-chain extended and chain extended peptidic polyurea (PU) and polyurea/polyurethane (PUU) hybrids towards tunable mechanics...
September 1, 2017: Organic & Biomolecular Chemistry
David L Arndt, Harriet de Wit
Introduction: Cannabidiol (CBD) is a nonpsychoactive constituent of whole plant cannabis that has been reported to reduce anxiety-like behaviors in both pre-clinical and human laboratory studies. Yet, no controlled clinical studies have demonstrated its ability to reduce negative mood or dampen responses to negative emotional stimuli in humans. The objective of this study was to investigate the effects of CBD on responses to negative emotional stimuli, as a model for its potential anxiety-reducing effects. Materials and Methods: The study used a double-blind, placebo (PLB)-controlled, within-subjects design in which 38 healthy, drug-free participants consumed oral CBD (300, 600, and 900 mg) or PLB before completing several behavioral tasks selected to assess reactivity to negative stimuli...
2017: Cannabis and Cannabinoid Research
Matteo Mauro, Stéphane Bellemin-Laponnaz, Cristina Cebrián Ávila
Functional materials that respond to external stimuli are of major current interest. In particular, supramolecular systems that can interact with surroundings, adapt to environmental changes and evolve with are even more fascinating, yet challenging. Combining the rich physico-chemical properties featured by metal centres with characteristics typical of classical organic polymers, metallopolymers or metallo-supramolecular polymers can be prepared, depending on their static vs. dynamic structural features. Additionally, multiple and orthogonal functionalities can be encoded in their chemical structure affording materials with widespread potential applications to be employed as "smart" materials for advanced technologies...
August 30, 2017: Chemistry: a European Journal
Nicole Kfoury, Eric Scott, Colin Orians, Albert Robbat
Plants produce volatile organic compounds (VOCs) with diverse structures and functions, which change in response to environmental stimuli and have important consequences for interactions with other organisms. To understand these changes, in situ sampling is necessary. In contrast to dynamic headspace (DHS), which is the most often employed method, direct contact sampling employing a magnetic stir bar held in place by a magnet eliminates artifacts produced by enclosing plant materials in glass or plastic chambers...
September 15, 2017: Journal of Agricultural and Food Chemistry
Bhupinder Singh, Rajneet Kaur Khurana, Babita Garg, Sumant Saini, Ranjot Kaur
With the advent of "intelligent" polymeric systems, the use of stimuli-responsive in situ gelling systems has been revolutionized. These interesting polymers exist as free-flowing aqueous solutions before administration and undergo a phase transition to form a viscoelastic gel in a physiological environ through various stimuli such as temperature, pH, solvent, biochemical, magnetic, electric, ultrasound, and photo-polymerization. These smart polymers are endowed with numerous merits such as ease of administration, sustained release, reduced frequent administration with improved patient compliance, and targeted and spatial delivery of a drug with reduced frequency of side effects...
2017: Critical Reviews in Therapeutic Drug Carrier Systems
Meizhi Zhao, Hui Feng, Jiaonan Han, Hang Ao, Zhaosheng Qian
Thiolate-protected copper nanoclusers (CuNCs) are emerging as a promising class of luminescent materials since its unique optical properties such as aggregation-induced emission (AIE) and intriguing molecular-like behavior have been explored for sensing application. In this work, multi-stimuli responsive property of CuNCs was first investigated in depth and further adopted to develop a reliable and sensitive ACP assay. Penicilamine-capped CuNCs from a facile one-pot synthesis possess bright red luminescence and distinctive multi-stimuli responsive behaviors...
September 1, 2017: Analytica Chimica Acta
Jisang Yoo, N Sanoj Rejinold, DaeYong Lee, Sangyong Jon, Yeu-Chun Kim
Reactive oxygen species (ROS)- or protease-responsive materials have been utilized as carriers in cancer therapies because ROS and specific proteases are overproduced in cancer cells. Methionine-based polypeptides containing a thioether group are promising candidates due to their ROS-responsiveness which provides a phase transition. Herein, we developed protease-activatable cell-penetrating peptide containing a ROS-responsive methionine, a cell permeable lysine chain, and a matrix metalloproteinase (MMP)-cleavable linker...
August 24, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
Lei Zhang, Songlin Li, Marco A Squillaci, Xiaolan Zhong, Yifan Yao, Emanuele Orgiu, Paolo Samorì
The use of biomimetic approaches toward the production of nonsolid yet functional architectures holds potential for the emergence of novel device concepts. Gels, in particular those obtained via self-assembly of π-conjugated molecules, are dynamic materials possessing unique (opto)electronic properties. Their adaptive nature imparts unprecedented responsivity to various stimuli. Hitherto, a viable device platform to electrically probe in situ a sol-gel transition is still lacking. Here we describe the fabrication of a sub-micrometer electrodic cavity, which enables low-voltage electrical operation of π-gels...
September 5, 2017: Journal of the American Chemical Society
Sjören Schweizerhof, Dan Eugen Demco, Ahmed Mourran, Helmut Keul, Radu Fechete, Martin Möller
Quantification of the stimuli-responsive phase transition in polymers is topical and important for the understanding and development of novel stimuli-responsive materials. The temperature-induced phase transition of poly(N-isopropylacrylamide) (PNIPAm) with one thiol end group depends on the confinement-free polymer or polymer brush-on the molecular weight and on the nature of the second end. This paper describes the synthesis of heterotelechelic PNIPAm of different molecular weights with a thiol end group-that specifically binds to gold nanorods and a hydrophilic NIPAm end group by reversible addition-fragmentation chain-transfer polymerization...
August 21, 2017: Macromolecular Rapid Communications
Heng Deng, Yuan Dong, Jheng-Wun Su, Cheng Zhang, Yunchao Xie, Chi Zhang, Matthew R Maschmann, Yuyi Lin, Jian Lin
Responsive materials with functions of forming three-dimensional (3D) origami and/or kirigami structures have a broad range of applications in bioelectronics, metamaterials, microrobotics, and microelectromechanical (MEMS) systems. To realize such functions, building blocks of actuating components usually possess localized inhomogeneity so that they respond differently to external stimuli. Previous fabrication strategies lie in localizing nonswellable or less-swellable guest components in their swellable host polymers to reduce swelling ability...
September 13, 2017: ACS Applied Materials & Interfaces
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