Nanothermometer for In Vivo Temperature Detection with High Spatial Resolution Based on Core–Shell Rare Earth Nanoparticles

Abstract

Temperature is a basic physical parameter in living organisms that directly relates to the physiological state of the body. The demand for in vivo temperature detection is expected to obtain accurate temperature signals with high spatial resolution. We propose a strategy of constructing and encapsulating the temperature probe (NaNdF4:7%Yb,33%Y) and high-resolution imaging probe (NaYbF4:2%Er,2%Ce) in identical rare earth nanoparticles to attain in vivo temperature detection with high spatial resolution. The temperature probe acquires temperature feedback based on the luminescence lifetime signal which is used for accurate temperature acquisition with a thermal sensitivity of 1.94% K–1 and uncertainty of 0.05 K at 25.8 °C. The intensity-based imaging probe with emission wavelength in NIR-IIb is introduced to attain a high-resolution image with a signal-to-noise ratio of 2.5 times that of the temperature probe in NIR-I. Hence, the high-resolution image serves as the luminescence location image for the temperature distribution image attained by the temperature probe. On the basis of obtaining the temperature signal and high-resolution imaging signal, the image algorithm is designed for the superposition of the temperature image and high-resolution image. Ultimately, the dual-dimensional signals acquired by optical detection are superimposed by the image algorithm to obtain high-resolution temperature mapping.