Manganese Doped Fluorescent Paramagnetic Nanocrystals for Dual-Modal Imaging


Sharma V. K. , Gokyar S., Kelestemur Y., ERDEM T. , Unal E., Demir H. V.

SMALL, vol.10, no.23, pp.4961-4966, 2014 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 10 Issue: 23
  • Publication Date: 2014
  • Doi Number: 10.1002/smll.201401143
  • Title of Journal : SMALL
  • Page Numbers: pp.4961-4966

Abstract

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 Mn2+ 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 Mn2+ doping is confined to the core of these NCs are also presented. It is observed that with increasing Mn2+ concentration the PL intensity first increases, reaching a maximum at Mn2+ 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 (approximate to 2.95 mM(-1) s(-1)) to obtain MR contrast at 25 degrees C, 3 T. Therefore, the Mn2+ doping in these water-soluble Cd-free NCs are sufficient to produce contrast for both fluorescence and magnetic resonance imaging techniques.