Reduced bacterial adhesion on zirconium-based bulk metallic glasses by femtosecond laser nanostructuring

As high-performing materials, bulk metallic glasses have attracted widespread attention for biomedical applications. Herein, the bacterial adhesion properties of femtosecond laser-nanostructured surfaces of four types of zirconium-based bulk metallic glasses are assessed. Laser-induced periodical surface structures and nanoparticle structures were fabricated by femtosecond laser irradiation under different energy intensities (0.23 and 2.3 J/mm²). Surface topography, roughness, wettability, and surface energy were investigated after femtosecond laser irradiation and the surface bacterial adhesion properties were explored using Escherichia coli and Staphylococcus aureus as respective representatives of Gram-negative and Gram-positive bacteria. 4',6-Diamidino-2-phenylindole fluorescence staining was used to characterize and assess the bacterial surface coverage rate. The in vitro cytotoxicity of polished and laser-nanostructured surfaces was investigated using MC3T3-E cells. The obtained results demonstrate that femtosecond laser surface nanostructuring retained the amorphous structure of zirconium-based bulk metallic glasses and led to an obvious decrease in bacterial adhesion compared with polished surfaces. The inhibition of bacterial adhesion on laser-induced periodical surface structures was greater than on nanostructured surfaces after 24 h of bacterial incubation. In addition, femtosecond laser nanostructuring did not have an apparent effect on the cytotoxicity of zirconium-based bulk metallic glasses.