Nature Nanotechnology 9, 1054–1062 (2014); published online 24 November 2014; corrected after print 3 December 2014.

In the version of this Article originally published, the affiliations of Hakan Eroglu, Omer Faruk Turkoglu, Seçil Caban, Oya Tagit, Niko Hildebrandt and Yilmaz Capan were incorrect; they should have appeared as shown below. This error has now been corrected in the online versions of the Article.

Hakan Eroglu4, Omer Faruk Turkoglu5, Seçil Caban4, Oya Tagit8, Niko Hildebrandt8, Yilmaz Capan4

4Department of Pharmaceutical Technology, Faculty of Pharmacy, Hacettepe University, Ankara 06100, Turkey.

5Department of Neurosurgery, Ankara Ataturk Research & Education Hospital, 06800 Bilkent Ankara, Turkey.

8NanoBioPhotonics, Institut d'Electronique Fondamentale, University of Paris-Sud XI, 91405, Orsay Cedex, France.