Enhanced Bactericidal Activity of Silver Thin Films Deposited via Aerosol-Assisted Chemical Vapor Deposition

Silver thin films were deposited on SiO2-barrier-coated float glass, fluorine-doped tin oxide (FTO) glass, Activ glass, and TiO2-coated float glass via AACVD using silver nitrate at 350 °C. The films were annealed at 600 °C and analyzed by X-ray powder diffraction, X-ray photoelectron spectroscopy, UV/vis/near-IR spectroscopy, and scanning electron microscopy. All the films were crystalline, and the silver was present in its elemental form and of nanometer dimension. The antibacterial activity of these samples was tested against Escherichia coli and Staphylococcus aureus in the dark and under UV light (365 nm). All Ag-deposited films reduced the numbers of E. coli by 99.9% within 6 h and the numbers of S. aureus by 99.9% within only 2 h. FTO/Ag reduced bacterial numbers of E. coli to below the detection limit after 60 min and caused a 99.9% reduction of S. aureus within only 15 min of UV irradiation. Activ/Ag reduced the numbers of S. aureus by 66.6% after 60 min and TiO2/Ag killed 99.9% of S. aureus within 60 min of UV exposure. More remarkably, we observed a 99.9% reduction in the numbers of E. coli within 6 h and the numbers of S. aureus within 4 h in the dark using our novel TiO2/Ag system

(1)H NMR relaxation studies of protein-polysaccharide mixtures

International audienceNMR water proton relaxation was used to characterize the structure of plant proteins and plant protein-polysaccharide mixtures in aqueous solutions. The method is based on the mobility determination of the water molecules in the biopolymers environment in solutions through relaxation times measurements. Differences of conformation between pea globulin and alpha gliadin seem to control the water molecules mobility in their environment. As deduced from the study of complexes, the electrostatic interactions may also play a major role in the water molecule motions. The phase separation induced under specific conditions seems to promote the translational diffusion of structured water molecules whereas the rotational motion was more restricted.</p

Evaluating conditions for the formation of chitosan/gelatin microparticles

Chitosan/gelatin microparticles were prepared by complex coacervation. Three chitosan (CH) samples, with different acetylation degrees and intrinsic viscosities, were used together with commercial gelatin (G) samples. Microparticles formation was investigated at various CH/G ratios, within the pH range of 3.5 to 6.0. Reactions were carried out at 40 and 60 ºC, for 2, 4, and 6 hours. Turbidity measurements performed at 633 nm were used to monitor the process. The resulting curves revealed maximum values, which were correlated to the glucosamine content of CH samples. After isolation, yields were determined, and the microparticles were characterized by infrared spectroscopy (FTIR) and thermogravimetry (TGA). Both techniques evidenced the formation of coacervate microparticles. The highest yields in microparticles were determined for the system comprising the CH sample with the lowest degree of acetylation and intrinsic viscosity, and the gelatin sample with the lowest bloom strength