Journées GDR ABioPlas, 2010, Orléans (FRANCE)

Journées GDR ABioPlas, 2010, Orléans (FRANCE

Plasma-deposited nanosilver-containing coating to prevent yeast adhesion : influence of released silver on the cell chemical composition

International audienc

Plasma-engineered polymer thin films with embedded nanosilver for prevention of fungal biofilm formation

International audienc

PECVD nanosilver embedded in organosilicon matrix for prevention of microbial adhesion

International audienc

Ageing of plasma-mediated coatings with embedded silver nanoparticles on stainless steel: An XPS and ToF-SIMS investigation

International audienceNanocomposite thin films (~170 nm), composed of silver nanoparticles enclosed in an organosilicon matrix, were deposited onto stainless steel, with the aim of preventing biofilm formation. The film deposition was carried out under cold plasma conditions, combining radiofrequency (RF) glow discharge fed with argon and hexamethyldisiloxane and simultaneous silver sputtering. XPS and ToF-SIMS were used to characterize Ag-organosilicon films in native form and after ageing in saline solution (NaCl 0.15 M), in order to further correlate their lifetime with their anti-fouling properties. Two coatings with significantly different silver contents (7.5% and 20.3%) were tested. Surface analysis confirmed the presence of metallic silver in the pristine coating and revealed significant modifications after immersion in the saline solution. Two different ageing mechanisms were observed, depending on the initial silver concentration in the film. For the sample exhibiting the low silver content (7.5%), the metal amount decreased at the surface in contact with the solution, due to the release of silver from the coating. As a result, aftera 2-day exposure, silver nanoparticles located at the extreme surface were entirely released, whereas silver is still present in the inner part of the film. The coating thickness was not modified during ageing. In contrast, for the high silver content film (20.3%), the thickness decreased with immersion time, due to significant silver release and matrix erosion, assigned to a percolation-like effect. However, after 18 days of immersion, the delamination process stopped and a thin strongly bounded layer remained on the stainless steel surface

Plasma Ag nanoclusters/organosilicon matrix thin films for prevention of fungal biofilm formation

International audienc

Nanocomposite films silver/plasma polymer for biological applications

International audienc

Silver nanoparticle-containing polysiloxane films for prevention of microbial colonization

International audienc

Prevention of biofilm on stainless steel: evaluation of anti-adhesive and antimicrobial properties of silver-nanocomposite thin films

International audienc

Synchrotron FTIR microspectroscopy of the yeast Saccharomyces cerevisiae after exposure to plasma-deposited nanosilver-containing coating

International audienceThe present work was focused on elucidating changes in the model yeast Saccharomyces cerevisiae (cell composition, ultrastructure) after exposure to antimicrobial plasma-mediated nanocomposite films. In order to achieve this, a nanosilver-containing coating was deposited onto stainless steel using radiofrequency HMDSO plasma deposition, combined with simultaneous silver sputtering. X-ray photoelectron spectroscopy (XPS) confirmed the presence of silver nanoparticles embedded in an organo-silicon matrix. In addition, scanning electron microscopy (SEM) demonstrated the nanoparticle-based morphology of the deposited layer. The antifungal properties towards S. cerevisiae were established, since a 1.4 log reduction in viable counts was observed after a 24-h adhesion compared to control conditions with the matrix alone. Differences in cell composition after exposure to the nanosilver was assessed for the protein region using, for the first time, synchrotron Fourier-transform infrared (FTIR) microspectroscopy of single S. cerevisiae cells, through in situ mapping with sub-cellular spatial resolution. IR spectrum of yeast cells recovered after a 24-h adhesion to the nanosilver-containing coating revealed a significant downshift (20 cm −1) of the amide I peak at 1655 cm −1 , compared to freshly harvested cells. This lower band position, corresponding to a loss in α-helix structures, is indicative of the disordered secondary structures of proteins, due to the transition between active and inactive conformations under nanosilver-induced stress conditions. No significant effect on the nucleic acid region was detected. The inhibitory action of silver was targeted against both cell wall and intracellular proteins such as enzymes. Transmission electron microscopy (TEM) observations of the yeastultrastructure confirmed serious morphological and structural damages. A homogeneous protein-binding distribution of nanosilver all over the cell was assumed, since the presence of electron-dense silver clusters was detected not only on the cell surface but also within the cell. For control experiments with the organosilicon matrix alone, no antimicrobial effect was observed, which was consistent with synchrotron FTIR results and TEM observations