Temperature Sensing in the Short-Wave Infrared Spectral Region Using Core-Shell NaGdF4:Yb3+, Ho3+, Er3+@NaYF4 Nanothermometers.

Daria Pominova,Oleg Uvarov,Sergei Kuznetsov,Pavel Fedorov,Victor Loschenov,Igor Romanishkin,Vera Proydakova,Anastasia Ryabova

doi:10.3390/nano10101992

Daria Pominova, Oleg Uvarov + Show 6 more

Open Access

https://doi.org/10.3390/nano10101992

Copy DOI

Abstract

The short-wave infrared region (SWIR) is promising for deep-tissue visualization and temperature sensing due to higher penetration depth and reduced scattering of radiation. However, the strong quenching of luminescence in biological media and low thermal sensitivity of nanothermometers in this region are major drawbacks that limit their practical application. Nanoparticles doped with rare-earth ions are widely used as thermal sensors operating in the SWIR region through the luminescence intensity ratio (LIR) approach. In this study, the effect of the shell on the sensitivity of temperature determination using NaGdF4 nanoparticles doped with rare-earth ions (REI) Yb3+, Ho3+, and Er3+ coated with an inert NaYF4 shell was investigated. We found that coating the nanoparticles with a shell significantly increases the intensity of luminescence in the SWIR range, prevents water from quenching luminescence, and decreases the temperature of laser-induced heating. Thermometry in the SWIR spectral region was demonstrated using synthesized nanoparticles in dry powder and in water. The core-shell nanoparticles obtained had intense luminescence and made it possible to determine temperatures in the range of 20–40 °C. The relative thermal sensitivity of core-shell NPs was 0.68% °C−1 in water and 4.2% °C−1 in dry powder.

Highlights

The development of contactless thermal sensors has attracted much attention in the last decade [1,2,3,4]
We examined the influence of NaYF4 inert shell on the luminescence intensity in short-wave infrared region (SWIR) and the thermal sensing sensitivity of Yb3+, Ho3+, Er3+ tri-doped NaGdF4 NPs
Tri-doped Yb3+, Ho3+, Er3+ core and core-shell β-NaGdF4 NPs were successfully synthesized in this study

Summary

Introduction

The development of contactless thermal sensors has attracted much attention in the last decade [1,2,3,4]. Conventional thermocouples and thermometers are unsuitable for remote temperature control [5]. Precise contactless monitoring and temperature control at the microscopic level are highly important for controlling various biological functions and their changes during thermal therapies as well as visualization of thermal changes in vivo [6,7,8,9,10,11]. Contactless luminescent nanothermometers are promising for biomedical applications. Various luminescent materials with temperature-dependent optical features have been studied as optical thermometers. The most popular are quantum dots [12,13], organic molecules [14,15,16], polymers [17,18,19], DNA or protein-conjugated systems [20], and lanthanide-doped nanophosphors [21,22]

Methods

Results

Conclusion