Upconversion nanoparticles: on the way from diagnostics to theranostics

We report of surface modification approaches of nanoparticles with anti-Stokes luminescence, known as upconversion nanoparicles (UCNPs), comprised of inorganic host NaYF4 codoped with Yb3+ and Er3+ or Tm3+ . These approaches enabled the facile, lossless preparation of hybrid polymer-encapsulated UCNPs suitable for bioassays. These probes inherited UCNP properties, such as excellent photoluminescence under excitation with NIR light from the biotissue “transparency window”, as well as they were dispersible in aqueous media and physiological buffers, exhibiting chemical stability. The feasibility of the hybrid UCNPs was demonstrated for in vitro bioassay and in vivo optical whole animal imaging using a home-built epiluminescence imaging system.