Ultrasensitive NIR‐II Ratiometric Nanothermometers for 3D In Vivo Thermal Imaging

• Published in: Advanced materials (Weinheim) 2024-03, Vol.36 (11), p.e2309452-n/a
• Main Authors: Li, Dan, Jia, Mochen, Jia, Tao, Chen, Guanying
• Format: Article
• Language: English
• Subjects: 3D thermographic imaging; Animals; Biomedical materials; Energy transfer; Hot Temperature; Lanthanoid Series Elements - chemistry; Medical imaging; Metal Nanoparticles; Mice; Nanocomposites; NIR‐II; Quantum dots; Quantum Dots - chemistry; ratiometric luminescent nanothermometry; self‐calibrating program; Temperature; Thermal imaging; thermal sensitivity; Thermography
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202309452

Luminescent nanothermometry, particularly the one based on ratiometric, has sparked intense research for non‐invasive in vivo or intracellular temperature mapping, empowering their uses as diagnosis tools in biomedicine. However, ratiometric detection still suffers from biased sensing induced by wavelength‐dependent tissue absorption and scattering, low thermal sensitivity (Sr), and lack of imaging depth information. Herein, this work constructs an ultrasensitive NIR‐II ratiometric nanothermometer with self‐calibrating ability for 3D in vivo thermographic imaging, in which temperature‐insensitive lanthanide nanocrystals and strongly temperature‐quenched Ag2S quantum dots are co‐assembled to form a hybrid nanocomposite material. Precise control over the amount ratio between two sub‐materials enables the manipulation of heat‐activated back energy transfer from Ag2S to Yb3+ in lanthanide nanoparticles, thereby rendering Sr up to 7.8% °C−1 at 43.5 °C, and higher than 6.5% °C−1 over the entire physiological temperature range. Moreover, the luminescence intensity ratio between two separated spectral regions within the narrow Yb3+ emission peak is used to determine the depth information of nanothermometers in living mice and correct the effect of tissue depth on 2D thermographic imaging, and therefore allows a proof‐of‐concept demonstration of accurate 3D in vivo thermographic imaging, constituting a solid step toward the development of advanced ratiometric nanothermometry for biological applications. Ultrasensitive NIR‐II ratiometric nanothermometers with self‐calibrating ability are constructed by assembling temperature‐insensitive lanthanide nanocrystals and temperature‐sensitive Ag2S quantum dots into a hybrid nanocomposite material. The high thermal sensitivity, robust stability and calibration procedure enable accurate 3D thermographic imaging ex vivo and in vivo.