Showing papers by "Vi Khanh Truong published in 2010"

Impact of nanoscale roughness of titanium thin film surfaces on bacterial retention

Abstract: Two human pathogenic bacteria, Staphylococcus aureus CIP 68.5 and Pseudomonas aeruginosa ATCC 9025, were adsorbed onto surfaces containing Ti thin films of varying thickness to determine the extent to which nanoscale surface roughness influences the extent of bacterial attachment. A magnetron sputter thin film system was used to deposit titanium films with thicknesses of 3, 12, and 150 nm on glass substrata with corresponding surface roughness parameters of Rq 1.6, 1.2, and 0.7 nm (on a 4 μm × 4 μm scanning area). The chemical composition, wettability, and surface architecture of titanium thin films were characterized using X-ray photoelectron spectroscopy, contact angle measurements, atomic force microscopy, three-dimensional interactive visualization, and statistical approximation of the topographic profiles. Investigation of the dynamic evolution of the Ti thin film topographic parameters indicated that three commonly used parameters, Ra, Rq, and Rmax, were insufficient to effectively characterize the ...

Plasma-enhanced synthesis of bioactive polymeric coatings from monoterpene alcohols: A combined experimental and theoretical study

Abstract: This paper describes the synthesis and characterization of a novel organic polymer coating for the prevention of the growth of Pseudomonas aeruginosa on the solid surface of three-dimensional objects. Substrata were encapsulated with polyterpenol thin films prepared from terpinen-4-ol using radio frequency plasma enhanced chemical vapor deposition. Terpinen-4-ol is a constituent of tea tree oil with known antibacterial properties. The influence of deposition power on the chemical structure, surface composition, and ultimately the antibacterial inhibitory activity of the resulting polyterpenol thin films was studied using X-ray photoelectron spectroscopy (XPS), water contact angle measurement, atomic force microscopy (AFM), and 3-D interactive visualization and statistical approximation of the topographic profiles. The experimental results were consistent with those predicted by molecular simulations. The extent of bacterial attachment and extracellular polymeric substances (EPS) production was analyzed using scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). Polyterpenol films deposited at lower power were particularly effective against P. aeruginosa due to the preservation of original terpinen-4-ol molecules in the film structure. The proposed antimicrobial and antifouling coating can be potentially integrated into medical and other clinically relevant devices to prevent bacterial growth and to minimize bacteria-associated adverse host responses.

Bacterial attachment on optical fibre surfaces

Abstract: Optical fibres have received considerable attention as high-density sensor arrays suitable for both in vitro and in vivo measurements of biomolecules and biological processes in living organisms and/or nano-environments. The fibre surface was chemically modified by exposure to a selective etchant that preferentially erodes the fibre cores relative to the surrounding cladding material, thus producing a regular pattern of cylindrical wells of approximately 2.5 mum in diameter and 2.5 mum deep. The surface hydrophobicity of the etched and non-etched optical fibres was analysed using the sessile pico-drop method. The surface topography was characterised by atomic force microscopy (AFM), while the surface chemistry was probed by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Six taxonomically different bacterial strains showed a consistent preference for attachment to the nano-scale smoother (R(q) = 273 nm), non-etched fibre surfaces (water contact angle, theta = 106 degrees +/- 4 degrees). In comparison, the surfaces of the etched optical fibres (water contact angle, theta = 96 degrees +/- 10 degrees) were not found to be amenable to bacterial attachment. Bacterial attachment on the non-etched optical fibre substrata varied among different strains.

Bacterial Attachment Response on Titanium Surfaces with Nanometric Topographic Features

Abstract: The bacterial attachment response on titanium surfaces with various degrees of nano-roughness in the range of 14 nm to 0.6 nm has been investigated. Titanium surfaces were fabricated from commercial purity grade 2 (as-received) titanium, titanium modified by equal channel angular pressing (modified titanium) and titanium thin film of 12 nm and 150 nm obtained using a magnetron sputtering system. The chemical composition, wettability and surface architecture of Ti surfaces were characterised using X-ray photoelectron spectroscopy, contact angle measurements and atomic force microscopy. Two human pathogenic bacteria, Staphylococcus aureus CIP 68.5 and Pseudomonas aeruginosa ATCC 9025 were found to respond differently to each of the tested surfaces. The results indicate that bacteria can differentiate between surfaces with the fine (less than 1 nm) change of topographic characteristics, the number of retained cells differing by a factor of up to 2.

Bacterial attachment response to nanostructured titanium surfaces

Abstract: The effect of sub-nanometric surface roughness of Ti thin films surfaces on the attachment of two human pathogenic bacteria, Staphylococcus aureus CIP 65.8T and Pseudomonas aeruginosa ATCC 9027, was studied. A magnetron sputtering thin film deposition system was used to control the titanium thin film thicknesses of 3 nm, 12 nm and 150 nm on silicon wafers with corresponding surface roughness parameters of R q 0.14 nm, 0.38 nm and 5.55 nm (1 μm × 1 μm scanning area). Analysis of bacterial retention profiles showed that the bacteria responded differently changes in the R a and R q (Ti thin film) surface roughness parameters of a less than 1 nm, with up to 2–3 times: more cells being retained on the surface, and elevated levels of extracellular polymeric substances being secreted on the Ti thin films, in particular on the surfaces with 0.14 nm (R q ) roughness.