Low-temperature open-air synthesis of PVP-coated NaYF 4:Yb,Er,Mn upconversion nanoparticles with strong red emission

MacKenzie, Lewis E. and Alvarez-Ruiz, Diana and Pal, Robert (2022) Low-temperature open-air synthesis of PVP-coated NaYF 4:Yb,Er,Mn upconversion nanoparticles with strong red emission. Royal Society Open Science, 9 (1). 211508. ISSN 2054-5703 (https://doi.org/10.1098/rsos.211508)

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Abstract

Cubic (α-phase) NaYF4:Yb,Er upconversion nanoparticles (UCNPs) are uniquely suited to biophotonics and biosensing applications due to their near-infrared excitation and visible red emission (λex approx. 660 nm), enabling detection via thick overlying tissue with no bio-autofluorescence. However, UCNP synthesis typically requires high temperatures in combination with either high pressure reaction vessels or an inert atmosphere. Here, we report synthesis of α-phase NaYF4:Yb,Er,Mn UCNPs via the considerably more convenient PVP40-mediated route; a strategy that requires modest temperatures and relatively short reaction time (160°C, 2 h) in open air, with Mn2+ co-doping serving to greatly enhance red emission. The optimal Mn2+ co-doping level was found to be 35 mol %, which decreased the average maximum UCNP Feret diameter from 42 ± 11 to 36 ± 15 nm; reduced the crystal lattice parameter, a, from 5.52 to 5.45 Å; and greatly enhanced UCNP red/green emission ratio in EtOH by a factor of 5.6. The PVP40 coating enabled dispersal in water and organic solvents and can be exploited for further surface modification (e.g. silica shell formation). We anticipate that this straightforward UCNP synthesis method for producing strongly red-emitting UCNPs will be particularly beneficial for deep tissue biophotonics and biosensing applications.

ORCID iDs

MacKenzie, Lewis E. ORCID logoORCID: https://orcid.org/0000-0002-8151-0525, Alvarez-Ruiz, Diana and Pal, Robert;
  • Item type:Article
    ID code:79193
    Dates:
    Date
    Event
    1 February 2022
    Published
    19 January 2022
    Published Online
    3 December 2021
    Accepted
    24 September 2021
    Submitted
    Subjects:Science > Chemistry
    Department:Faculty of Science > Pure and Applied Chemistry
    Depositing user: Pure Administrator
    Date deposited:20 Jan 2022 11:42
    Last modified:11 Nov 2024 13:22
    URI:https://strathprints.strath.ac.uk/id/eprint/79193
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