Multi-Hollow Surface Dielectric Barrier Discharge for Bacterial Biofilm Decontamination.

The plasma-activated gas is capable of decontaminating surfaces of different materials in remote distances. The effect of plasma-activated water vapor on Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli biofilm contamination was investigated on the polypropylene nonwoven textile surface. The robust and technically simple multi-hollow surface dielectric barrier discharge was used as a low-temperature atmospheric plasma source to activate the water-based medium. The germicidal efficiency of short and long-time exposure to plasma-activated water vapor was evaluated by standard microbiological cultivation and fluorescence analysis using a fluorescence multiwell plate reader. The test was repeated in different distances of the contaminated polypropylene nonwoven sample from the surface of the plasma source. The detection of reactive species in plasma-activated gas flow and condensed activated vapor, and thermal and electrical properties of the used plasma source, were measured. The bacterial biofilm decontamination efficiency increased with the exposure time and the plasma source power input. The log reduction of viable biofilm units decreased with the increasing distance from the dielectric surface.

Deposition of MoSe2 flakes using cyclic selenides.

The currently limited portfolio of volatile organoselenium compounds used for atomic layer deposition (ALD) has been extended by designing and preparing a series of four-, five- and six-membered cyclic silylselenides. Their fundamental properties were tailored by alternating the ring size, the number of embedded Se atoms and the used peripheral alkyl chains. In contrast to former preparations based on formation of sodium or lithium selenides, the newly developed synthetic method utilizes a direct and easy reaction of elemental selenium with chlorosilanes. Novel 2,2,4,4-tetraisopropyl-1,3,2,4-diselenadisiletane, which features good trade-off between chemical/thermal stability and reactivity, has been successfully used for gas-to-solid phase reaction with MoCl5 affording MoSe2. A thorough characterization of the as-deposited 2D MoSe2 flakes revealed its out-of-plane orientation and high purity. Hence, the developed four-membered cyclic silylselenide turned out to be well-suited Se-precursor for ALD of MoSe2.

Cold atmospheric pressure plasma: simple and efficient strategy for preparation of poly(2-oxazoline)-based coatings designed for biomedical applications.

Poly(2-oxazolines) (POx) are an attractive material of choice for biocompatible and bioactive coatings in medical applications. To prepare POx coatings, the plasma polymerization represents a fast and facile approach that is surface-independent. However, unfavorable factors of this method such as using the low-pressure regimes and noble gases, or poor control over the resulting surface chemistry limit its utilization. Here, we propose to overcome these drawbacks by using well-defined POx-based copolymers prepared by living cationic polymerization as a starting material. Chemically inert polytetrafluoroethylene (PTFE) is selected as a substrate due to its beneficial features for medical applications. The deposited POx layer is additionally post-treated by non-equilibrium plasma generated at atmospheric pressure. For this purpose, diffuse coplanar surface barrier discharge (DCSBD) is used as a source of "cold" homogeneous plasma, as it is operating at atmospheric pressure even in ambient air. Prepared POx coatings possess hydrophilic nature with an achieved water contact angle of 60°, which is noticeably lower in comparison to the initial value of 106° for raw PTFE. Moreover, the increased fibroblasts adhesion in comparison to raw PTFE is achieved, and the physical and biological properties of the POx-modified surfaces remain stable for 30 days.

Cyclic Silylselenides: Convenient Selenium Precursors for Atomic Layer Deposition.

Three cyclic silylselenides were prepared in a straightforward manner. Property tuning has been achieved by varying the ring size and the number of embedded selenium atoms. All silylselenides possess improved resistance towards moisture and oxidation as well as high thermal robustness and sufficient volatility with almost zero residues. The six-membered diselenide proved to be particularly superior Se precursors for atomic layer deposition and allowed facile preparation of MoSe2 layers. Their structure and composition have been investigated by Raman and X-ray photoelectron spectroscopy as well as scanning electron microscopy revealing vertically aligned flaky shaped nanosheets.

Atmospheric Dry Hydrogen Plasma Reduction of Inkjet-Printed Flexible Graphene Oxide Electrodes.

This study concerns a low-temperature method for dry hydrogen plasma reduction of inkjet-printed flexible graphene oxide (GO) electrodes, an approach compatible with processes envisaged for the manufacture of flexible electronics. The processing of GO to reduced graphene oxide (rGO) was performed in 1-64 s, and sp2 /sp2 +sp3 carbon concentration increased from approximately 20 % to 90 %. Since the plasma reduction was associated with an etching effect, the optimal reduction time occurred between 8 and 16 s. The surface showed good mechanical stability when deposited on polyethylene terephthalate flexible foils and significantly lower sheet resistance after plasma reduction. This method for dry plasma reduction could be important for large-area hydrogenation and reduction of GO flexible surfaces, with present and potential applications in a wide variety of emerging technologies.