title: Manganese doped fluorescent paramagnetic nanocrystals for dual-modal imaging.
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 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.
authors.affiliation: UNAM-Institute of Materials Science and Nanotechnology, Department of Electrical and Electronics Engineering, Department of Physics, Bilkent University, Ankara, 06800, Turkey.
authors.forename: Vijay Kumar
authors.initials: VK
authors.lastname: Sharma
authors.forename: Sayim
authors.initials: S
authors.lastname: Gokyar
authors.forename: Yusuf
authors.initials: Y
authors.lastname: Kelestemur
authors.forename: Talha
authors.initials: T
authors.lastname: Erdem
authors.forename: Emre
authors.initials: E
authors.lastname: Unal
authors.forename: Hilmi Volkan
authors.initials: HV
authors.lastname: Demir
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D008345:Manganese / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence / Q000295:instrumentation*; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D055095:Optics and Photonics; D010777:Photochemistry / Q000379:methods; D056951:Photoelectron Spectroscopy / Q000379:methods; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry; D012666:Semiconductors; D012995:Solubility; D013696:Temperature; D014867:Water / Q000737:chemistry; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D008024:Ligands; D018036:Selenium Compounds; D017967:Zinc Compounds; D014867:Water; D008345:Manganese; C044696:zinc selenide
keywords: fluorescence imaging; low-toxicity; magnetic resonance imaging; nanocrystals; water-solubility