Antiseptic treatment of <i>Pseudomonas aeruginosa</i> SG81 biofilms.

<p>The analytical results by the Number of samples (n), Colony reduction factor (CRF) in log₁₀ (CFU/cm²) ± Standard Deviation (SD), lower and upper 95% confidence limits (CI) after exposure to air plasma for 30–600 s treatment time respectively and 0.1% CHX after 600 s exposure time and untreated control of <i>Pseudomonas aeruginosa</i> SG81 biofilms [p-values of omnibus tests (Kruskal-Wallis) and two-sample tests (Whitney <i>U</i>); statistical significance: α = 0.05].</p>c<p>significantly different from CHX.</p>*<p>significantly different from the respective treatment time of <i>Staphylococcus epidermidis</i> RP62A.</p

Spectrometric graph of irradiance by SBD-B generated air plasma within 300 s of exposure time between 200 and 400 nm.

<p>Spectrometric graph of irradiance by SBD-B generated air plasma within 300 s of exposure time between 200 and 400 nm.</p

Scanning electron micrographs of untreated and air plasma treated biofilms on polycarbonate discs.

<p>A) untreated biofilm of <i>Pseudomonas aeruginosa</i> SG81 (5000-fold), B) untreated biofilm of <i>Staphylococcus epidermidis</i> RP62A (5000-fold), C) <i>Pseudomonas aeruginosa</i> SG81 biofilms after 300 s of air plasma treatment by SBD-A (2000-fold) and D) by SBD-B (1500-fold) as well as E) <i>Staphylococcus epidermidis</i> RP62A biofilms after 300 s of air plasma treatment by SBD-A (1000-fold) and F) by SBD-B (5000-fold).</p

Cytotoxicity of 0.1% chlorhexidine digluconate solution on L929 cell line (mouse fibroblasts).

<p>Measured values of MTT-Assay after 30–600 s treatment time with 0.1% of chlorhexidine dicluconate solution (in culture media) with the Number of samples (n), mean, standard deviation (SD), and the cell viability as ratio in comparison to the control in percent.</p

The atmospheric pressure plasma jet (kINPen08, INP Greifswald, Germany).

<p>(a) Schematic set-up of the plasma jet which consists of a pin-type electrode centered inside a quartz capillary with an inner diameter of 1.6 mm and an outer diameter of 4 mm. A high-frequency voltage (1.7 MHz, 2–6 kV_PP) is coupled to the electrode. The overall electric power of the plasma device is 65 W. The plasma jet was positioned perpendicular to the sample surface with a distance of 7 mm between the nozzle outlet and the substrate surface. (b) Photograph of the plasma jet, driven with 5 slm Ar and 0.05 slm O₂, impinging the PEEK surface.</p

Experimental setup of the SBD-A plasma source.

<p>A: Electrode and discs with biofilms on plastic flat grate. B: Configuration of the electrode in action mode. C: Schematic representation of the experimental setup of SBD-A.</p

Extent of the plasma-etched surface area after 180 s Ar/O₂ plasma exposure.

<p>Images taken at 50-fold magnification on the left and at 200-fold magnification on the right. Left: The dark area represents the densely packed biofilm whereas the bright areas display the PS wafer surface. An etched area of 2 mm in diameter was measured. Right: Sharp boundary between the plasma-affected area and the still present biofilm.</p

Experimental setup of the SBD-B plasma source.

<p>A: Overview of the experimental setup. B: Near focus of the electrode in action mode above the discs with biofilms. C: Schematic representation of the experimental setup of SBD-B in cross section.</p

Influence of different gas discharge plasmas on 7-day old <i>Candida albicans</i> biofilms grown on polystyrene wafer.

<p>The samples were washed and dried by air flow before plasma treatment. The microscopic images were taken with a magnification of 200 at the same sample position before (left column) and after plasma treatment (right column) A: The control sample was only exposed to the Ar/O₂ gas flow for 60 s without plasma ignition. B: The biofilm sample was exposed to 5 slm Ar plasma. C: The biofilm sample was exposed to plasma composed of a gas mixture of 5 slm Ar and 0.05 slm O₂ (total admixture of 1% O₂).</p

Radial distribution of plasma-generated species in the Ar/O₂ gas discharge plasma and the direct relation to the radial etching profile of poly(ether ether ketone) (PEEK).

<p>The upper graph shows the intensity of atomic Ar at 750.4 nm and atomic O at 844.6 nm depending on the radial distance recorded end-on at a distance of 7 mm to the jet-nozzle by means of a dual channel fiber optical spectrometer (Avantes AvaSpec 2048-2-USB2). The spectra were relative calibrated, normalized to the exposure time, and analyzed using the software Spectrum Analyzer. ‘0’ represents the position of the atmospheric pressure plasma jet. In the lower figure the radial etching profile of PEEK after 180 s Ar/O₂ plasma exposure is displayed. The surface profile was recorded by means of a stylus surface profiler (Dektak 3ST, Veeco, USA). The dashed lines mark the extent of the biofilm-etched surface (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042539#pone-0042539-g005" target="_blank">Fig. 5</a>).</p