Science and technology policy is increasingly becoming subject to public scrutiny and to the mechanisms of public participation and debate. New and emerging techniques in the domain of nano-enabled technologies for medical applications are no exception to this trend. Public commitment initiatives are valuable in terms of advancing communication, yet democratic deliberation and reflection exercises are challenging also from an ethical and a regulatory perspective, as it is not immediately clear how actors in these fields may proceed from them. The outcomes of a citizens' panel, held in the Flemish participatory technology assessment project “Nanotechnologies for Tomorrow's Society”, illustrate that citizens' reflections express enthusiasm, scepticism and anxiety - and thus ambivalence - towards nano-enabled developments in future health care. The authors first demonstrate these ambivalent responses by means of a contextual ethical analysis based on a limited set of principles and on typologies of differing value perspectives. They then analyze the attempts by regulatory agents and law-makers to limit the possibilities of inconsistent interpretations and to create a climate of “certainty” in which technological innovation can thrive. The article concludes by exploring potential venues of more effective and inspirational knowledge transfer from public participation exercises to regulatory bodies and law-makers. Knowledge transfer, the authors argue, should build on interdisciplinary rather than on multidisciplinary knowledge production and participation.