This review discusses the roles in signaling to cells by nanochemical, nanostructural (nanotopography) and mechanical means, as well as recent work and trends in nanobioscience that are relevant to therapeutic applications. It is suggested that the mechanical results may often integrate the other two types of signal. Although the field is still in an almost embryonic but rapidly developing state, it is possible to envisage potential medical devices. Nanoparticle-based therapies are recognized as having some appreciable hazards, while those based on extended nanofeatured surfaces probably have fewer risks.