Hyaluronan (HA) represents an interesting polymer for nanoparticle coating due to its biocompatibility and enhanced cell interaction via CD44 receptor. Here, we describe incorporation of oleatecapped b-NaYF 4 :Yb 3? , Er 3? nanoparticles (UCNP-OA) into amphiphilic HA by microemulsion method. Resulting structures have a spherical, micelle-like appearance with a hydrodynamic diameter of 180 nm. UCNP-OA-loaded HA micelles show a good stability in PBS buffer and cell culture media. The intensity of green emission of UCNP-OA-loaded HA micelles in water is about five times higher than that of ligand-free UCNP, indicating that amphiphilic HA effectively protects UCNP luminescence from quenching by water molecules. We found that UCNP-OA-loaded HA micelles in concentrations up to 50 lg mL -1 increase cell viability of normal human dermal fibroblasts (NHDF), while viability of human breast adenocarcinoma cells MDA-MB-231 is reduced at these concentrations. The utility of UCNP-OA-loaded HA micelles as a bio-imaging probe was demonstrated in vitro by successful labelling of NHDF and MDA-MB-231 cells overexpressing the CD44 receptor. NHDF (d) incubated with UCNP-OA-loaded oleyl-HA micelles and excess of oleyl-HA (2 mg mL -1 ) served as controls. Green and blue colours represent upconversion emission and Hoechststained cell nuclei, respectively. (Color figure online)

No abstract

Oleate-capped ZnO quantum dots were prepared by modified oxygen-deficient sol-gel synthesis. The as-prepared quantum dots exhibit 1.3-fold increase in fluorescence quantum yield compared to ZnO prepared by common synthesis. To transfer these quantum dots from organic phase into water, oleate molecules were exchanged for linear aminosiloxanes or branched siloxane-based poly(amidoamine) dendrons. The impact of ligand type on quantum yield and colloidal stability of ZnO samples was studied.