Aqueous synthesis and bio-imaging application of highly luminescent and low cytotoxicity Mn2+-doped ZnSe nanocrystals

In this paper, Mn2+-doped ZnSe quantum dots (Mn:ZnSe d-dots) are synthesized successfully by a nucleation–doping method in aqueous solution with 3-Mercaptopropionic acid as the stabilizer and sodium selenite as the Se source for the first time in contrast to the use of oxygen-sensitive NaHSe or H2Se as Se source. The obtained quantum dots performed strong band-edge luminescence, narrow size distribution and weak trap emission without post-treatments. The results of transmission electron microscopy and X-ray diffraction demonstrated the small particle size (3–4 nm), good monodispersity and ZnSe(S) alloyed structure of as-prepared quantum dots. Finally, the biological application of luminescent Mn2+-doped ZnSe nanocrystals to PK 15 cell imaging was also illustrated, which showed excellent biocompatibility and low cytotoxicity, implying their potential as a new generation of fluorescent labels for biological assays, tissues, and even in vivo investigations.