Optimization of titanium and titanium alloy surface properties by ultra-short laser processing for improved antibacterial characteristics

Abstract

The aim of the current study is to improve in a one step process the properties of Ti and Ti alloy surfaces by enhancing their bioactivity in order to provide better conditions for microbial rejection. We propose to alter the biomaterial characteristics by a method alternative to the chemical ones, namely, non-contact processing of the surface by ultra-short laser pulses. The laser-induced modification results in a surface with different topographic features and an increased presence of oxides. We performed hierarchical laser patterning of the surface inducing the formation of areas covered by nanostructures, or laser-induced periodic surface structures (LIPSS), alternating with areas covered by micropillars in their turn surmounted by LIPSS. The increased roughness achieved due to the presence of micropillars, together with a marked presence of oxides, has been proven by several studies to enhance the biocompatibility of the material by improving the surface wettability and, furthermore, promoting the cells adhesion and osseointegration, while reducing the adhesion of pathogens. The laser processed surface, consisting of a pattern of parallel lines, showed improved and anisotropic wettability. The water contact angle value decreased by â1/410° in a direction orthogonal to the lines of the pattern, and by â1/440° in a parallel direction.