1. Fluorescence Imaging GroupDepartamento de Física de MaterialesFacultad de CienciasUniversidad Autónoma de Madrid 28049 Madrid Spain
2. Institute of Low Temperature and Structure ResearchPolish Academy of Sciences ul.Okolna 2 50–422 Wroclaw Poland
3. Łukasiewicz Research Network – Port Polish Center for Technology Development ul.Stablowicka 147 54–066 Wrocław Poland
4. Nanobiology GroupInstituto Ramón y Cajal de InvestigaciónSanitaria Hospital Ramón y Cajal Ctra.De Colmenar Viejo, Km. 9100 28034 Madrid Spain