Bactericidal activity of polymeric nanopatterned surface

The bactericidal properties of most orthopedics implants are not satisfactory and bacteria can adhere onto the surface cause serious problems such as infections. Nanoparticles can be incorporated to kill bacteria but some of the more potent ones have toxicity in large quantities. A new strategy to prevent biofilm formation on implants is surface nanopatterning. In this work, a nanopatterned polymeric surface is fabricated from silk using colloidal masks and reactive ion etching (RIE). The Silk plate is used as a substrate and fabricated according a protocol based on the Bombyx mori cocoons. The silk plate is spin-coated with a solution containing polystyrene nanospheres with a colloidal mask followed by RIE to perform nanopatterning. The staphylococcus aureus (S. aureus) bacteria are cultured on the samples and the bactericidal activity is assessed by live/dead staining and fluorescence microscopy. By adjusting the etching time, the effects of the height and lateral distance between the nanocones on the bactericidal behavior of the samples are studied and the optimal height, aspect ratio, and spacing between nanocones are determined.