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Erbium Single‐Band Nanothermometry in the Third Biological Imaging Window: Potential and Limitations
Author(s) -
Hazra Chanchal,
Skripka Artiom,
Ribeiro Sidney J. L.,
Vetrone Fiorenzo
Publication year - 2020
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.202001178
Subject(s) - materials science , photoluminescence , photon upconversion , erbium , luminescence , emission intensity , ion , band gap , radiative transfer , nanoparticle , doping , analytical chemistry (journal) , optoelectronics , optics , nanotechnology , chemistry , physics , organic chemistry , chromatography
Near‐infrared (NIR) nanothermometers are sought after in biomedicine when it comes to measuring temperatures subcutaneously. Yet, temperature sensing within the third biological imaging window (BW‐III), where the highest contrast images can be obtained, remains relatively unexplored. Here, LiErF 4 /LiYF 4 rare‐earth nanoparticles (RENPs) are studied as NIR nanothermometers in the BW‐III. Under 793 nm excitation, LiErF 4 /LiYF 4 RENPs emit around 1540 nm, corresponding to the 4 I 13/2 → 4 I 15/2 radiative transition of Er 3+ . The fine Stark structure of this transition allows to delineate intensity regions within the emission band that can be used for single‐band ratiometric nanothermometry. These nanothermometers have a relative temperature sensitivity of ≈0.40% °C −1 . The temperature‐dependent energy transfer to the surrounding solvent molecules plays a significant role in the thermometric properties of the RENPs. In addition, Ce 3+ ions are doped in the core of the RENPs to examine whether it affects the NIR emission and temperature sensitivity. Ce 3+ at 1 mol% marginally influences the downshifting emission intensity of the RENPs, yet increases the relative thermal sensitivity to ≈0.45% °C −1 . Furthermore, Ce 3+ quenches the visible upconversion emission of the RENPs. Together, LiErF 4 :Ce 3+ /LiYF 4 RENPs enable single‐band photoluminescence nanothermometry in the BW‐III, with the future possibility of its integration within multifunctional decoupled theranostic nanostructures.