Effect of Surface Finish on Wettability and Bacterial Adhesion of Micromachined Biomaterials

Bacterial infection is one of the major complications occurs in biomedical implants. Bacterial adhesion on the implant surfaces can form a biofilm, which leads to infection and failure at an earlier phase of implantation. So the surface properties of the implant such as surface topography, surface energy, and chemistry play a crucial role in bacterial adhesion. For decades, several surface finishing techniques have been developed to alter the surface properties in turn to reduce the bacterial adhesion. Most of these implants exhibit freeform surfaces which are difficult to finish with available finishing methods to obtain the uniform surface properties. The current paper focused on the development of a unidirectional abrasive flow finishing process used to finish biomaterials- stainless steel (SS316L) and titanium alloy (Ti-6Al-4 V ELI) with two different abrasive media and a varying number of cycles. The purpose of this study is to evaluate the effect of this finishing process on enhancing the surface characteristics like surface finish, surface topography and its role on wettability and initial bacterial adhesion. Optical profilometer and a scanning electron microscope are used to examine the surface topography and surface morphology of the finished surfaces. The goniometer is used to study the wettability of the finished samples using the sessile drop technique. Further, for the bacterial adhesion study both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) are selected because these bacterial strains were commonly found on implant-related infections. The obtained result shows that, the surface finish and topography influences on wettability and bacterial adhesion. In conclusion, these results demonstrate that the possibilities of the developed process to enhance the surface finish of the biomedical implants which in turn reduce the implant-related infections and chances of early phase implant failure.