The invention relates to materials that exhibit biocidal activity and in particular to surfaces that exhibit novel surface topography that is lethal to cells on contact. The invention also relates to devices comprising such surfaces, to methods of producing the surfaces and to methods of eliminating or reducing cellular survival wherein cells are exposed to the surfaces. In particular the invention relates to a synthetic biocidal surface comprising an array of nanospikes that are lethal to cells on said surface due to piercing of cell membranes by said nanospikes and to a method of producing a synthetic biocidal surface comprising an array of nanospikes that are lethal to cells on said surface due to piercing of cell membranes by said nanospikes, which comprises exposing a silicon comprising substrate surface to reactive-ion etching.
