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 R(q) 1.6, 1.2, and 0.7 nm (on a 4 microm x 4 microm 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, R(a), R(q), and R(max), were insufficient to effectively characterize the nanoscale rough/smooth surfaces. Two additional parameters, R(skw) and R(kur), which describe the statistical distributions of roughness character, were found to be useful for evaluating the surface architecture. Analysis of bacterial retention profiles indicated that bacteria responded differently to the surfaces on a scale of less than 1 nm change in the R(a) and R(q) Ti thin film surface roughness parameters by (i) an increased number of retained cells by a factor of 2-3, and (ii) an elevated level of secretion of extracellular polymeric substances.

The Effect of Polyterpenol Thin Film Surfaces on Bacterial Viability and Adhesion

“…The 25 W polymer layer is smooth on the sub-nano-scale roughness level compared to unmodified substrate; therefore the current -attachment point‖ theory [46][47] that suggests that bacterial cells prefer microscopic surface irregularities as the starting point for their attachment as these provide shelter from unfavorable environmental influences clearly also cannot explain the attachment behavior. Our recent studies found that nano-scale surface roughness may have a notable effect on bacterial attachment and adhesion, with nano-scale fluctuations in roughness exerting a significant influence on the cellular response to certain surfaces [18,42,48]. The results presented here show that a higher number of bacterial cells were able to colonize the nano-smooth 25 W polymer coated substrates, whereas less smooth, unmodified glass substrates sustained a significantly lower level of cellular attachment.…”

Multi-directional electrodeposited gold nanospikes for antibacterial surface applications

“…22,25 More importantly, this process appears to be independent of surface chemistry, meaning that bacteria are unable to develop a protective response. 1,2,[15][16][17][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Such surface nanostructuring provides a viable replacement for conventional antibacterial surface technologies that involve the incorporation of antibiotics or additive chemicals. A comparative analysis of biocidal nanostructures has suggested that short, sharp nanofeatures tend to exhibit greater biocidal behavior;…”

Antimicrobial performance of mesoporous titania thin films: role of pore size, hydrophobicity, and antibiotic release

“…1,20 For example, decreased adhesion of Staphylococcus aureus and Pseudomonas aeruginosa on Ti films has been reported when the nanoroughness was increased. 21 An effective approach to prevent BAIs would be to combine an antimicrobial release coating with a low bacterial adhesive material, for example, by introducing a specific nanoroughness. 22 One promising coating in this respect is mesoporous thin films, since they have roughness values in the nano regime combined with the ability to host and deliver antimicrobial drugs.…”