Protein adsorption on TiO2 nanostructures and its effects on surface topography and bactericidal performance

Bionic nanostructures have broad potential applications for achieving the surface mechano-bactericidal performance especially for titanium extensively used as implants. However, the surface topographies of these nano-structures may be changed by protein adsorption in vivo, which possibly affects the sterilization of nanostructures. Herein, two plasma proteins, bovine serum albumin (BSA) and human serum fibronectin (HFN), were adsorbed onto three typical TiO2 nanostructures respectively, and the topographies as well as the subsequent bacterial behavior of Escherichia coli and Staphylococcus aureus were investigated. The results show that after BSA adsorption, the height of the nanostructures is reduced and the radius of the nanocones is increased for three typical nanostructures, weakening the surface bactericidal performance. Whereas, after HFN adsorption, the proteins are adsorbed at different positions of nanostructures, affecting their bactericidal efficiency. Notably, the bactericidal efficiency of nanowire clusters and nanowire/sheet clusters against Escherichia coli is significantly improved from similar to 49.64% and similar to 83.25% to similar to 64.89% and similar to 93.67% due to the presence of HFN layer on the top of the nanostructures, which may cause higher stress to cell membrane by nanocones. Our results demonstrate that the bactericidal performance of implant is impacted by the combined effect of surface nanostructure and protein layer.