ORIGINAL PAPER Synchrotron FTIR microspectroscopy of the yeast Saccharomyces cerevisiae after exposure to plasma-deposited nanosilver-containing coating C. Saulou & F. Jamme & C. Maranges & I. Fourquaux & B. Despax & P. Raynaud & P. Dumas & M. Mercier-Bonin Received: 27 July 2009 / Revised: 12 October 2009 / Accepted: 15 November 2009 / Published online: 12 December 2009 # Springer-Verlag 2009 Abstract The 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) microspec- troscopy 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 down- shift (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 C. Saulou : C. Maranges : M. Mercier-Bonin Université de Toulouse, INSA, UPS, INPT, LISBP, 135 Av. de Rangueil, 31077 Toulouse, France C. Saulou : C. Maranges : M. Mercier-Bonin INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, 31400 Toulouse, France C. Saulou : C. Maranges : M. Mercier-Bonin CNRS, UMR5504, 31400 Toulouse, France C. Saulou : B. Despax : P. Raynaud Université de Toulouse, UPS, INPT, LAPLACE, 118 route de Narbonne, 31062 Toulouse cedex 9, France C. Saulou : B. Despax : P. Raynaud CNRS, LAPLACE, 31062 Toulouse, France F. Jamme INRA-Département CEPIA, Rue de la Géraudière, BP 71627, 44316 Nantes cedex 3, France F. Jamme : P. Dumas Synchrotron SOLEIL, L ’Orme des Merisiers, BP 48, Saint Aubin, 91192 Gif-sur-Yvette, France I. Fourquaux Université Paul Sabatier, Centre de Microscopie Electronique Appliquée à la Biologie (CMEAB), Route de Narbonne, 31077 Toulouse cedex 4, France M. Mercier-Bonin (*) Laboratoire d’Ingénierie des Systèmes Biologiques et des Procédés, INSA, 135 Avenue de Rangueil, 31077 Toulouse cedex 4, France e-mail: Muriel.Mercier-Bonin@insa-toulouse.fr Anal Bioanal Chem (2010) 396:1441–1450 DOI 10.1007/s00216-009-3316-5