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Manganese Doped Fluorescent Paramagnetic Nanocrystals for Dual‐Modal Imaging
Author(s) -
Sharma Vijay Kumar,
Gokyar Sayim,
Kelestemur Yusuf,
Erdem Talha,
Unal Emre,
Demir Hilmi Volkan
Publication year - 2014
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201401143
Subject(s) - manganese , fluorescence , paramagnetism , materials science , doping , nanocrystal , dual (grammatical number) , optoelectronics , nanotechnology , nuclear magnetic resonance , optics , physics , condensed matter physics , metallurgy , art , literature
In this work, dual‐modal (fluorescence and magnetic resonance) imaging capabilities of water‐soluble, low‐toxicity, monodisperse Mn‐doped ZnSe nanocrystals (NCs) with a size (6.5 nm) below the optimum kidney cutoff limit (10 nm) are reported. Synthesizing Mn‐doped ZnSe NCs with varying Mn 2+ concentrations, a systematic investigation of the optical properties of these NCs by using photoluminescence (PL) and time resolved fluorescence are demonstrated. The elemental properties of these NCs using X‐ray photoelectron spectroscopy and inductive coupled plasma‐mass spectroscopy confirming Mn 2+ doping is confined to the core of these NCs are also presented. It is observed that with increasing Mn 2+ concentration the PL intensity first increases, reaching a maximum at Mn 2+ concentration of 3.2 at% (achieving a PL quantum yield (QY) of 37%), after which it starts to decrease. Here, this high‐efficiency sample is demonstrated for applications in dual‐modal imaging. These NCs are further made water‐soluble by ligand exchange using 3‐mercaptopropionic acid, preserving their PL QY as high as 18%. At the same time, these NCs exhibit high relaxivity (≈2.95 mM −1 s −1 ) to obtain MR contrast at 25 °C, 3 T. Therefore, the Mn 2+ doping in these water‐soluble Cd‐free NCs are sufficient to produce contrast for both fluorescence and magnetic resonance imaging techniques.