Smart Biointerface with Photoswitched Functions between Bactericidal Activity and Bacteria-Releasing Ability

Smart biointerfaces with capability to regulate cell–surface interactions in response to external stimuli are of great interest for both fundamental research and practical applications. Smart surfaces with “ON/OFF” switchability for a single function such as cell attachment/detachment are well-known and useful, but the ability to switch between two different functions may be seen as the next level of “smart”. In this work reported, a smart supramolecular surface capable of switching functions reversibly between bactericidal activity and bacteria-releasing ability in response to UV–visible light is developed. This platform is composed of surface-containing azobenzene (Azo) groups and a biocidal β-cyclodextrin derivative conjugated with seven quaternary ammonium salt groups (CD-QAS). The surface-immobilized Azo groups in trans form can specially incorporate CD-QAS to achieve a strongly bactericidal surface that kill more than 90% attached bacteria. On irradiation with UV light, the Azo groups switch to cis form, resulting in the dissociation of the Azo/CD-QAS inclusion complex and release of dead bacteria from the surface. After the kill-and-release cycle, the surface can be easily regenerated for reuse by irradiation with visible light and reincorporation of fresh CD-QAS. The use of supramolecular chemistry represents a promising approach to the realization of smart, multifunctional surfaces, and has the potential to be applied to diverse materials and devices in the biomedical field

The effect of size on dislocation cell formation and strain hardening in aluminium

<div><p>The formation of dislocation cells has a significant impact on the strain hardening behaviour of metals. Dislocation cells can form in metals with a characteristic size defined by three-dimensional tangles of dislocations that serve as “walls” and less dense internal regions. It has been proposed that inhibiting the formation of dislocation cells could improve the strain hardening behaviour of metals such as Al. Here we employ <i>in situ</i> scanning electron microscope compression testing of pure Al single crystal pillars with physical dimensions larger, close to and smaller than the reported cell size in Al, respectively, to investigate the possible size effect on the formation of dislocation cell and the consequent change of mechanical properties. We observed that the formation of dislocation cells is inhibited as the pillar size decreases to a critical value and simultaneously both the strength and the strain hardening behaviour become strongly enhanced. This phenomenon is discussed in terms of the effect of dimensional restriction on the formation of dislocation cells. The reported mechanism could be applied in polycrystalline Al where the tunable physical dimension could be grain size instead of sample size, providing insight into Al alloy design.</p></div

GNV8ASA03

Collection ID: GNV8ASA03 | Taxon: Ambrosia trifida L. | Common name: Giant ragweed | Collection locality: Kampsville, IL, USA (latitude 39.16, longitude 90.37) | Plant tissues employed for EST library development: Roots, Leaves, Flower buds, Mature Flowers | Library type: Normalized, double-stranded | Sequence type: 45

GNV8ASA04

Collection ID: GNV8ASA04 | Taxon: Ambrosia trifida L. | Common name: Giant ragweed | Collection locality: Bloomington, IN, USA (latitude 39.92, longitude 86.31) | Plant tissues employed for EST library development: Roots, Leaves, Flower buds, Mature Flowers | Library type: Normalized, double-stranded | Sequence type: 45

GNV8ASA01

Collection ID: GNV8ASA01 | Taxon: Ambrosia trifida L. | Common name: Giant ragweed | Collection locality: Jilin, Jilin, China (latitude 43.50, longitude 126.32) | Plant tissues employed for EST library development: Roots, Leaves, Flower buds, Mature Flowers | Library type: Normalized, double-stranded | Sequence type: 45

Data_Sheet_1_Root exudates influence rhizosphere fungi and thereby synergistically regulate Panax ginseng yield and quality.pdf

Root exudates contain a complex array of primary and specialized metabolites that play important roles in plant growth due to their stimulatory and inhibitory activities that can select for specific microbes. In this study, we investigated the effects of different root exudate concentrations on the growth of ginseng (Panax ginseng C. A. Mey), ginsenoside levels, and soil fungal community composition and diversity. The results showed that low root exudate concentrations in the soil promoted ginseng rhizome biomass and ginsenoside levels (Rg1, Re, Rf, Rg2, Rb1, Ro, Rc, Rb2, Rb3, and Rd) in rhizomes. However, the rhizome biomass and ginsenoside levels gradually decreased with further increases in the root exudate concentration. ITS sequencing showed that low root exudate concentrations in the soil hardly altered the rhizosphere fungal community structure. High root exudate concentrations altered the structure, involving microecological imbalance, with reduced abundances of potentially beneficial fungi (such as Mortierella) and increased abundances of potentially pathogenic fungi (such as Fusarium). Correlation analysis showed that rhizome biomass and ginsenoside levels were significantly positively correlated with the abundances of potentially beneficial fungi, while the opposite was true for potentially pathogenic fungi. Overall, low root exudate concentrations promote the growth and development of ginseng; high root exudate concentrations lead to an imbalance in the rhizosphere fungal community of ginseng and reduce the plant’s adaptability. This may be an important factor in the reduced ginseng yield and quality and soil sickness when ginseng is grown continuously.</p

Nanopatterned Smart Polymer Surfaces for Controlled Attachment, Killing, and Release of Bacteria

Model surfaces with switchable functionality based on nanopatterned, thermoresponsive poly­(<i>N</i>-isopropylacrylamide) (PNIPAAm) brushes were fabricated using interferometric lithography combined with surface-initiated polymerization. The temperature-triggered hydration and conformational changes of nanopatterned PNIPAAm brushes reversibly modulate the spatial concealment and exposure of molecules that are immobilized in the intervals between nanopatterned brushes. A biocidal quaternary ammonium salt (QAS) was used to demonstrate the utility of nanopatterned PNIPAAm brushes to control biointerfacial interactions with bacteria. QAS was integrated into polymer-free regions of the substrate between nanopatterned PNIPAAm brushes. The biocidal efficacy and release properties of these surfaces were tested against <i>Escherichia coli</i> K12. Above the lower critical solution temperature (LCST) of PNIPAAm, desolvated, collapsed polymer chains facilitate the attachment of bacteria and expose QAS moieties that kill attached bacteria. Upon a reduction of the temperature below the LCST, swollen PNIPAAm chains promote the release of dead bacteria. These results demonstrate that nanopatterned PNIPAAm/QAS hybrid surfaces are model systems that exhibit an ability to undergo noncovalent, dynamic, and reversible changes in structure that can be used to control the attachment, killing, and release of bacteria in response to changes in temperature

Sch A inhibition of TRAF6 expression of NF-κB pathway in LPS-induced BV-2 cells.

<p>(A) BV-2 cells were treated with LPS (1 μg/ml) with or without Sch A (50 μM) for 0, 0.5, 1, 2 and 4 h, and then TRAF6 protein expression was measured by Western blot. (B) BV-2 cells were treated with LPS (1 μg/ml) with or without Sch A (10, 20 and 50 μM) for 0.5 h, and then TRAF6 expression was measured by Western blot. (C) BV-2 cells were treated with Sch A (10, 20 and 50 μM) for 0.5 h, and then TRAF6 was measured by Western blot. All data are shown as the mean ± S.D. from independent experiments performed in triplicate. ^#<i>P</i> < 0.05, ^##<i>P</i> < 0.01 relative to control group; *<i>P</i> < 0.05, **<i>P</i> < 0.01 relative to LPS group.</p

Chemical structure of Sch A.

<p>Chemical structure of Sch A.</p

KEGG results of differential unigenes between 18 hpi and 12 hpi SL221 cells.

<p>KEGG results of differential unigenes between 18 hpi and 12 hpi SL221 cells.</p