A schematic of the plasma treatment system using a multigas plasma jet source.

<p>A schematic of the plasma treatment system using a multigas plasma jet source.</p

Bacterial inactivation in PBS(−) by various gas plasmas: (a) <i>S</i>. <i>aureus</i>; (b) <i>P</i>. <i>aeruginosa</i>.

<p>Bacterial inactivation in PBS(−) by various gas plasmas: (a) <i>S</i>. <i>aureus</i>; (b) <i>P</i>. <i>aeruginosa</i>.</p

Setup parameter of plasma source.

<p>Setup parameter of plasma source.</p

A schematic of the plasma treatment system using a multigas plasma jet source.

<p>A schematic of the plasma treatment system using a multigas plasma jet source.</p

Reversible Off–On Fluorescence Probe for Hypoxia and Imaging of Hypoxia–Normoxia Cycles in Live Cells

We report a fully reversible off–on fluorescence probe for hypoxia. The design employs QSY-21 as a Förster resonance energy transfer (FRET) acceptor and cyanine dye Cy5 as a FRET donor, based on our finding that QSY-21 undergoes one-electron bioreduction to the radical under hypoxia, with an absorbance decrease at 660 nm. At that point, FRET can no longer occur, and the dye becomes strongly fluorescent. Upon recovery of normoxia, the radical is immediately reoxidized to QSY-21, with loss of fluorescence due to restoration of FRET. We show that this probe, RHyCy5, can monitor repeated hypoxia–normoxia cycles in live cells

Inactivation effects of nitrogen plasma and carbon dioxide plasma on <i>P</i>. <i>aeruginosa</i> suspension including each radical scavenger.

<p>(Treatment time, 60 s; initial bacteria concentration, 5.4 × 10⁷ CFU). SOD was used as a superoxide scavenger, catalase as a H₂O₂ scavenger, NaN₃ as a singlet oxygen scavenger, and DMSO as an OH radical scavenger.</p

Metallic-Nanostructure-Enhanced Optical Trapping of Flexible Polymer Chains in Aqueous Solution As Revealed by Confocal Fluorescence Microspectroscopy

Optical trapping of flexible polymer chains to a metallic nanostructured surface was explored by microscopic imaging and confocal fluorescence spectroscopy. A fluorescence-labeled poly­(<i>N</i>-isopropylacrylamide) was targeted, being a representative thermo-responsive polymer. Upon resonant plasmonic excitation, it was clearly observed that polymers were assembled into the excitation area to form molecular assemblies. Simultaneously, fluorescence from the area was obviously intensified, indicating an increase in the number of polymer chains at the area. The excitation threshold of light intensity that was required for obvious trapping was 1 kW/cm², which was much lower by a factor of 10⁴ than that for conventional trapping using a focused laser beam. The morphology of the assemblies was sensitive to excitation intensity. We precisely evaluated temperature rise (Δ<i><i>T</i></i>) around the metallic nanostructure upon plasmonic excitation: Δ<i><i>T</i></i> ≈ 10 K at 1 kW/cm² excitation. This temperature rise was an origin of a repulsive force that blocked stable trapping. On the basis of experimental observations and theoretical calculations, we quantitatively evaluated the plasmon-enhanced trapping force and the thermal repulsive force (Soret effect). The overall mechanisms that were involved in such plasmon-enhanced optical trapping are discussed in detail. The smooth catch-and-release trapping (manipulation) of polymer chains was successfully demonstrated

Metallic-Nanostructure-Enhanced Optical Trapping of Flexible Polymer Chains in Aqueous Solution As Revealed by Confocal Fluorescence Microspectroscopy

Optical trapping of flexible polymer chains to a metallic nanostructured surface was explored by microscopic imaging and confocal fluorescence spectroscopy. A fluorescence-labeled poly­(<i>N</i>-isopropylacrylamide) was targeted, being a representative thermo-responsive polymer. Upon resonant plasmonic excitation, it was clearly observed that polymers were assembled into the excitation area to form molecular assemblies. Simultaneously, fluorescence from the area was obviously intensified, indicating an increase in the number of polymer chains at the area. The excitation threshold of light intensity that was required for obvious trapping was 1 kW/cm², which was much lower by a factor of 10⁴ than that for conventional trapping using a focused laser beam. The morphology of the assemblies was sensitive to excitation intensity. We precisely evaluated temperature rise (Δ<i><i>T</i></i>) around the metallic nanostructure upon plasmonic excitation: Δ<i><i>T</i></i> ≈ 10 K at 1 kW/cm² excitation. This temperature rise was an origin of a repulsive force that blocked stable trapping. On the basis of experimental observations and theoretical calculations, we quantitatively evaluated the plasmon-enhanced trapping force and the thermal repulsive force (Soret effect). The overall mechanisms that were involved in such plasmon-enhanced optical trapping are discussed in detail. The smooth catch-and-release trapping (manipulation) of polymer chains was successfully demonstrated

Metallic-Nanostructure-Enhanced Optical Trapping of Flexible Polymer Chains in Aqueous Solution As Revealed by Confocal Fluorescence Microspectroscopy

Optical trapping of flexible polymer chains to a metallic nanostructured surface was explored by microscopic imaging and confocal fluorescence spectroscopy. A fluorescence-labeled poly­(<i>N</i>-isopropylacrylamide) was targeted, being a representative thermo-responsive polymer. Upon resonant plasmonic excitation, it was clearly observed that polymers were assembled into the excitation area to form molecular assemblies. Simultaneously, fluorescence from the area was obviously intensified, indicating an increase in the number of polymer chains at the area. The excitation threshold of light intensity that was required for obvious trapping was 1 kW/cm², which was much lower by a factor of 10⁴ than that for conventional trapping using a focused laser beam. The morphology of the assemblies was sensitive to excitation intensity. We precisely evaluated temperature rise (Δ<i><i>T</i></i>) around the metallic nanostructure upon plasmonic excitation: Δ<i><i>T</i></i> ≈ 10 K at 1 kW/cm² excitation. This temperature rise was an origin of a repulsive force that blocked stable trapping. On the basis of experimental observations and theoretical calculations, we quantitatively evaluated the plasmon-enhanced trapping force and the thermal repulsive force (Soret effect). The overall mechanisms that were involved in such plasmon-enhanced optical trapping are discussed in detail. The smooth catch-and-release trapping (manipulation) of polymer chains was successfully demonstrated