1. Laboratory for Inorganic and Analytical ChemistryDepartment of Chemical EngineeringMünster University of Applied Sciences Stegerwaldstr. 39 D‐48565 Steinfurt Germany
2. Wellman Center for PhotomedicineMassachusetts General Hospital/Harvard Medical School 50 Blossom Street Boston MA 02114 USA
3. Functional Nanomaterials RGUniversity of Osnabrück Barbarastr. 7 D‐49076 Osnabrück Germany
4. Institute for Biomedical OpticsUniversity of Lübeck Peter ‐Monnik‐Weg 4 D‐23562 Lübeck Germany