Anti bacterial hydrophilic nanopatterned silk-based material

Bacteria attachment and growth on implants can cause serious problems and even death to patient. Most materials have been using for bone implants are metallic ones which will be remained in the body for whole life and if it will be infected by any reason, it should be removed immediately. Therefore, scientists have been focused on more natural and biodegradable materials and silk can be a prominent one because of its unique properties like excellent strength, biodegradability and biocompatibility. A new strategy to kill and prevent bacteria from adherence to the implant is introducing nano topography on the surface of implant because the stress at the contact area of bacteria cell wall will be increased significantly. By introducing nano topography to the surface of materials usually the water contact angle has been increased and the surface becomes superhydrophobic. Superhydrophobicity can help to reduce bacteria attachment but at the same time cell proliferation is also prevented. To achieve a good combination of antifouling and cell proliferation, hydrophilic nanopatterned silk-based material is fabricated by oxygen plasma etching method. The fabricated cones height are about 400 nm and center-to-center distance between two cones are about 300 nm. Bacteria culturing experiments showed more than 90% reduction in attachment of bacteria (both S.aureus and E.coli) to the surface while the water contact angle after plasma treatment is about less than 20 degree.