Antibacterial Properties of Superhydrophilic Textured Copper in Contact with Bacterial Suspensions.

The method of pulsed laser processing with a nanosecond pulse duration was employed to obtain a nanotexture on the surface of copper alloys. The effect of the obtained micro- and nanotexture on the bactericidal properties of the surface upon its contact with suspensions containing of E. coli K12 C600 or K. pneumoniae 811 cells in a nutrient medium were studied. The evolution of cell morphology after on the nanotextured surface was analyzed using scanning electron microscopy, and changes in biological fluid during this contact were studied by mass spectrometry. It was shown that massive death of bacterial cells both in the suspension and on the nanotextured surface was determined by combined toxic effects of the hierarchically textured surface and high concentration of Cu2+ ions in the medium.

Spreading of biologically relevant liquids over the laser textured surfaces.

HYPOTHESIS: The distribution of biological objects upon the spreading of biologically relevant dispersions over laser textured surfaces is affected by the dispersion composition and substrate chemistry and roughness. EXPERIMENTS: To examine the role of the substrate texture in biologically relevant liquid spreading, the dynamic behavior of droplets of water and dispersions of bacterial cells and viruses and dynamic behavior of droplet/air surface tension were addressed. A new procedure to simultaneously distinguish three different spreading fronts was developed. FINDINGS: The study of spreading of water and the biologically relevant liquids over the laser textured substrate indicate the development of three spreading fronts associated with the movement of bulk droplet base, the flow along the microchannels, and the nanotexture impregnation. The anisotropy of spreading for all types of liquid fronts was found. Despite the expected difference in the rheological behavior of water and the biologically relevant liquids, the spreading of all tested liquids was successfully described by power-law fits. The droplet base spreading for all tested liquids followed the Tanner law. The advancing of water and dispersions in the microchannels along both fast and slow axes was described by Washburn type behavior. The impregnation of the nanotexture by water and biologically relevant liquids demonstrated universality in power fit description with an exponent n = 0.23.

Development of a Bacteriophage Complex with Superhydrophilic and Superhydrophobic Nanotextured Surfaces of Metals Preventing Healthcare-Associated Infections (HAI).

We studied antibacterial properties of organo-inorganic hybrid coatings on the AMg2 aluminum alloy including superhydrophilic and superhydrophobic nanotextured metal substrates with applied bacteriophage particles. Bactericidal activity of surfaces after artificial contamination with a bacterial suspension was evaluated. To increase bactericidal effect of the plates, bacteriophage was sorbed on their surface. In the experiments simulating possible spreading of HAI pathogens, higher bactericidal activity of superhydrophilic surfaces in comparison with superhydrophobic ones. Application of bacteriophage particles did not prevent primary colonization of textured metal surfaces by strains used in the experiment, but in some cases increases their bactericidal activity.

Experimental Application of Organic-Inorganic Hybrid Coatings with Adsorbed Bacteriophages for Reducing the Risk of STEC Infections.

A new approach to prevention of STEC infection is based on the synergic effect of combined bactericidal activity of bacteriophages and organic-inorganic hybrid coating of metals. The coatings are characterized by superhydrophilic or superhydrophobic properties and multimodal granularity with the texture incorporating metal oxide nanoparticles and bacteriophages. Superhydrophilic surfaces are characterized by significantly higher bactericidal activity than superhydrophobic ones. The cytotoxicity of superhydrophobic surfaces can be increased due to antibacterial activity of bacteriophages combined with the superhydrophobic characteristics of the materials.