High-sensitivity lanthanide ratiometric nanothermometers in the second biological window through bidirectional thermal response engineering†
a
Guanying
Chen
*b
Abstract
In recent years, lanthanide-doped nanothermometers have made significant progress as non-contact temperature sensing tools in a variety of biological fields. However, limited successes have been met in high-sensitivity nanothermometers operating in the second near-infrared (NIR-II) biological window, which can enable sub-centimeter tissue penetration at micrometer-level imaging resolutions. Here, we adopted a core–shell structure to develop a high-sensitivity lanthanide ratiometric nanothermometer through a bidirectional thermal response of two emissions peaks in the NIR-II window. We showed that, under 808 nm excitation, the emission intensity at 1330 nm from neodymium ions exhibited a quenching effect, while the one at 1565 nm from erbium ions showed an enhancement at elevated temperatures. This contrasted temperature dependency endows the nanothermometer with a high relative sensitivity above 2.3% °C−1, with a maximum of 2.5% °C−1, throughout the entire physiological temperature range (30–45 °C). This high-sensitivity nanothermometer enables reliable differentiation of temperature differences in both normal and inflamed mice, highlighting its promising uses for in vivo applications.
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