Avoiding Degradation of Upconversion Nanoparticles by Using Hydrophobic Polymer Shells

The article «Upconverting Nanoparticles in Aqueous Media: Not a Dead-End Road. Avoiding Degradation by Using Hydrophobic Polymer Shells», published in Small, 2021, 2105652https://onlinelibrary.wiley.com/doi/10.1002/smll.202105652presents a new strategy to coat and protect β-NaYF4 upconversion nanoparticles (UCNPs) against degradation in aqueous media by growing a hydrophobic polymer shell (HPS) through miniemulsion polymerization of styrene (St), or St and methyl methacrylate mixtures.

Stability studies reveal that these HPSs serve as a very effective barrier, impeding polar molecules to affect UCNPs optical properties. Even more, it allows UCNPs to withstand aggressive conditions such as high dilutions (5 μg mL−1), high phosphate concentrations (100 mm), and high temperatures (70 °C).