Hydrophilic Nd3+-Sensitized Upconverting Core-Shell Nanoparticles for Biomedical Applications


Hydrophilic Nd3+-Sensitized Upconverting Core-Shell Nanoparticles for Biomedical Applications

Hesse, J.; Sgarzi, M.; Stephan, H.

Currently, there is a widespread interest to use neodymium containing upconverting nanophosphors (UCNPs) for bioimaging applications. The fascination of these nanoparticles derives from their capacity for excitation in the biologically transparent window (650-950 nm), exceptional ability to convert near infrared radiation into visible light (upconversion), which prevents autofluorescence and over-heating effect of biological tissues, capability for deep tissue, and high contrast imaging [1]. Despite the fast progress in lanthanide-doped upconversion nanoparticles, the preparation of ultrasmall, monodisperse and hydrophilic UCNPs that display intense luminescence is still a challenging issue. Only a few examples of ultrasmall and hydrophilic UCNPs have been reported [2-3]. Established strategies for synthesizing UCNPs yield mainly hydrophobic particles[1]. Here, we report the, synthesis and surface modification of sub-10 nm UCNPs with an excitation wavelength of 795 nm, which are composed of a host lattice of crystalline hexagonal phased NaYF4 doped with Nd3+ and Yb3+ as sensitizers, and Er3+, Ho3+ or Tm3+ as emitter ions. Surface passivation by coating with a shell of active and also inert host material is used to enhance the overall upconversion efficiency. We also report the conversion of these into hydrophilic, colloidally-stable, and biocompatible by using mainly ligand exchange strategies and the influence of the coating on the UCNPs’ photophysical properties will also be discussed. Finally, this study will also allow establishing information about biodistribution, pharmacokinetics and formation of protein corona for ultrasmall UCNPs.

Keywords: Upconversion; lanthanide; Sub 10nm particles; surface functionalization; Bio imaging

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    6th EuCheMS Chemistry Congress, 11.-15.09.2016, Seville, Spain

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Publ.-Id: 24204