Polysulfonate Cappings on Upconversion Nanoparticles Prevent Their Disintegration in Water and Provide Superior Stability in a Highly Acidic Medium.

ABSTRACT: The stability of organic cappings on hexagonal NaYF₄:Ln³⁺ upconversion nanoparticles (UCNPs) is crucial for their luminescence efficiency in aqueous solutions. The capping removal quickens as the acidity of the medium increases. We demonstrate here that polysulfonates, namely poly(2-acrylamido-2-methyl-1-propanesulfonate) (PAMPS) and poly(sodium 4-styrene sulfonate) (PSS), remain anchored to the surface of NaYF₄:Yb³⁺,Er³⁺/Tm³ UCNPs even at a pH as low as 2 due to strong acidity of the sulfonate anchoring groups (pK _a of ca. -3). Bare UCNPs progressively disintegrate into their compositional F^-, Na⁺, Y³⁺, and Ln³⁺ ions. Their disintegration is particularly worrying

SUBMITTER: Estebanez N 

PROVIDER: S-EPMC6648593 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature