Small and Bright Water-Protected Upconversion Nanoparticles with Long-Time Stability in Complex, Aqueous Media by Phospholipid Membrane Coating

Abstract

Chemical and colloidal stability in complex aqueous media are among the main challenges preventing nanoparticles from successfully entering into the biomedical field. Small core–shell upconversion nanoparticles (UCNPs) NaYF4:Yb,Er@NaYF4 of 12 nm in diameter with a high surface-to-volume ratio are utilized to demonstrate that self-assembling phospholipid bilayers (PLMs) have several benefits compared to common ligand-exchange and ligand-addition particle coatings such as poly­(acrylic acid) and amphiphilic polymers. An efficient hydrophobic barrier against water quenching and toward particle disintegration is formed by PLM. Particles with this functionalization have a higher upconversion luminescence in aqueous media in contrast to common surface ligands. They attract with better colloidal stability in phosphate buffer, in a wide pH range, in high ionic solutions, and in complex cell media, as is required for biological applications. Moreover, kidney cells (NRK) are not affected by these stable PLM-coated UCNPs as first cell viability tests reveal.

Understanding the Shell Passivation in Ln3+‐Doped Luminescent Nanocrystals

“…As it is known, the biosecurity assessment of Ln 3þ -doped nanocrystals for bioapplications has attracted great attention in recent years, [94] and material stability is one of the research hotspots. [95] The crux of the matter is the integrity of the material in biocompatible media [96] and different results have shown strong correlations between material stability, the type of medium, and the surface feature of the nanocrystal. [97] Several groups investigated the chemical stability of Ln 3þ -doped β-NaYF 4 in the aqueous Figure 16.…”

Boosting the Energy Migration Upconversion through Inter-Shell Energy Transfer in Tb 3+ -Doped Sandwich Structured Nanocrystals

“…The sandwich structure core@shell@shell NaLuF 4 :Yb/Gd@NaGdF 4 :Tm@NaLuF 4 :Tb EMU NCs were synthesized through a seed-mediated method, [39][40][41] which involves the growth of NaLuF 4 :Yb/Gd(49/33%) core NCs via the thermo-decomposition of lanthanide trifluoroacetates, 42,43 followed by the successive epitaxial deposition of -c), as corroborated by the incrementally narrowed powder X-ray diffraction peaks, which are well indexed as the hexagonal phase [44][45][46] of NaLuF 4 (Fig. S1).…”

Construction of NaYF4 Library for Morphology‐Controlled Multimodality Applications

“…Furthermore, all the products are in pure β‐phase as confirmed from the XRD patterns (Figure 1e), in which the diffraction peaks match well with standard β‐phase NaYF 4 (JCPDS 16‐0334). [ 23 ]…”