title: Quasi-Instantaneous Bacterial Inactivation on Cu-Ag Nanoparticulate 3D Catheters in the Dark and Under Light: Mechanism and Dynamics.
abstract: The first evidence for Cu-Ag (50%/50%) nanoparticulate hybrid coatings is presented leading to a complete and almost instantaneous bacterial inactivation in the dark (≤5 min). Dark bacterial inactivation times on Cu-Ag (50%/50%) were observed to coincide with the times required by actinic light irradiation. This provides the evidence that the bimetal Cu-Ag driven inactivation predominates over a CuO/Cu2O and Ag2O oxides inducing a semiconductor driven behavior. Cu- or Ag-coated polyurethane (PU) catheters led to bacterial inactivation needing about ∼30 min. The accelerated bacterial inactivation by Cu-Ag coated on 3D catheters sputtered was investigated in a detailed way. The release of Cu/Ag ions during bacterial inactivation was followed by inductively coupled plasma mass-spectrometry (ICP-MS) and the amount of Cu and Ag-ions released were below the cytotoxicity levels permitted by the sanitary regulations. By stereomicroscopy the amount of live/dead cells were followed during the bacterial inactivation time. By Fourier transform infrared spectroscopy (FTIR), the systematic shift of the -(CH2) band stretching of the outer lipo-polysaccharide bilayer (LPS) was followed to monitor the changes leading to cell lysis. A hydrophobic to hydrophilic transformation of the Cu-Ag PU catheter surface under light was observed within 30 min followed concomitantly to a longer back transformation to the hydrophobic initial state in the dark. Physical insight is provided for the superior performance of Cu-Ag films compared to Cu or Ag films in view of the drastic acceleration of the bacterial inactivation observed on bimetal Cu-Ag films coating PU catheters. A mechanism of bacterial inactivation is suggested that is consistent with the findings reported in this study.
authors.affiliation: EPFL-SB-ISIC-GPAO, Ecole Polytechnique Fédérale de Lausanne , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Sami
authors.initials: S
authors.lastname: Rtimi
authors.affiliation: EPFL-SB-IPMC-LNNME, Ecole Polytechnique Fédérale de Lausanne , Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: Rosendo
authors.initials: R
authors.lastname: Sanjines
authors.affiliation: EPFL-SB-ISIC-GPAO, Ecole Polytechnique Fédérale de Lausanne , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Cesar
authors.initials: C
authors.lastname: Pulgarin
authors.affiliation: EPFL-SB-ISIC-GPAO, Ecole Polytechnique Fédérale de Lausanne , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: John
authors.initials: J
authors.lastname: Kiwi
mesh_terms: D002138:Calibration; D057785:Catheters; D003300:Copper / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008027:Light; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects*; D053758:Nanoparticles / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry; D012834:Silver / Q000494:pharmacology*; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D011140:Polyurethanes; D012834:Silver; D003300:Copper
keywords: Cu−Ag 3D surfaces; E. coli inactivation; FTIR; cell lysis; dark/light processes; photoswitching; stereomicroscopy