Towards Laser-Textured Antibacterial Surfaces

Abstract

Escherichia coli and Staphylococcus aureus bacterial retention on mirror-polished and ultrashort pulse laser-textured surfaces is quantified with a new approach based on ISO standards for measurement of antibacterial performance. It is shown that both wettability and surface morphology influence antibacterial behavior, with neither superhydrophobicity nor low surface roughness alone sufficient for reducing initial retention of either tested cell type. Surface structures comprising spikes, laser-induced periodic surface structures (LIPSS) and nano-pillars are produced with 1030 nm wavelength 350 fs laser pulses of energy 19.1 μJ, 1.01 μJ and 1.46 μJ, respectively. SEM analysis, optical profilometry, shear force microscopy and wettability analysis reveal surface structures with peak separations of 20–40 μm, 0.5–0.9 μm and 0.8–1.3 μm, average areal surface roughness of 8.6 μm, 90 nm and 60 nm and static water contact angles of 160°, 119° and 140°, respectively. E. coli retention is highest for mirror-polished specimens and spikes whose characteristic dimensions are much larger than the cell size. S. aureus retention is instead found to be inhibited under the same conditions due to low surface roughness for mirror-polished samples (Sa: 30 nm) and low wettability for spikes. LIPSS and nano-pillars are found to reduce E. coli retention by 99.8% and 99.2%, respectively, and S. aureus retention by 84.7% and 79.9% in terms of viable colony forming units after two hours of immersion in bacterial broth due to both low wettability and fine surface features that limit the number of available attachment points. The ability to tailor both wettability and surface morphology via ultrashort pulsed laser processing confirms this approach as an important tool for producing the next generation of antibacterial surfaces.

Fabricating Laser-Induced Periodic Surface Structures on Medical Grade Cobalt–Chrome–Molybdenum: Tribological, Wetting and Leaching Properties

“…The contact angles in this study were measured after seven weeks for LSFL and Grooves and after 12 days for TNP. However, a positive effect of surface texturing (irrespective of morphological class) was seen on the hydrophobic behavior of the surfaces, in line with results found in literature [12,13,15].…”

“…When anti-bacterial properties of surfaces found in nature are studied, a correlation between hydrophobicity and anti-bacterial behavior is found [2,31,32]. Since LIPSS have been found to be hydrophobic [10][11][12][13][14][15] and also anti-bacterial [15][16][17][18], hydrophobicity is used in this paper as an indication of anti-bacterial behavior.…”

“…Lutey et al [15] showed that LSFL and TNP performed best on anti-bacterial properties regarding E. coli and S. aureus on stainless steel. A bacterial count reduction of 99.8% and 99.2% was found for E. coli and 84.7% and 79.9% was found for S. aureus, for the LSFL and TNP, respectively.…”

“…Under specific conditions, this can lead to so called laser-induced periodic surface structures (LIPSS). LIPSS are nanometer sized, regular patterned surface textures and can improve tribological performance [9,10], wettability properties [10][11][12][13][14][15], anti-bacterial properties [15][16][17][18] and cell-tissue growth [11].…”

Ultrafast Laser Surface Texturing: A Sustainable Tool to Modify Wettability Properties of Marble

“…(2) the capability of processing non-planar surfaces; (3) a single-step process performed under normal ambient conditions; (4) an eco-friendly process because no chemicals or toxic waste are added to the environment and (5) the ability to process nearly all types of materials. There are several reported works on nano/micro-texturing of different materials such as the improvement of cell adhesion in metallic bio-implants or tribological properties of mechanical components, self-cleaning, corrosion protection, and other applications [25,26]. The lasers used were short-pulse lasers [27][28][29][30][31][32] as well as ultra-short pulses [31,[33][34][35][36].…”