In this work, we report a potential optical nanothermometer (NTh) based on Nd³⁺ doped TiO₂ nanocrystals, operating within the biological windows. The Nd³⁺ emissions at around 900, 1060, and 1340 nm were used upon excitation at 808 nm. The fluorescence intensity ratio (FIR) corresponding to the emissions at 1060 nm and 1340 nm (FIR = I_{1060 nm}/I_{1340 nm}) was investigated as a function of the temperature in the range of 300−343 K. In addition, the effect of the Nd³⁺ ions concentration and influence of the crystalline phase on the luminescence and the relative thermal sensitivity were presented. As a result, it was found that TiO₂ nanocrystals doped with 10 wt% of Nd³⁺ ions and associated with the brookite phase has the highest luminescence emission and relative thermal sensitivity compared to other samples investigated here and in previous literature. The maximum value obtained to the relative thermal sensitivity was 0.86 % K⁻¹, which is high comparatively with other ones of Nd³⁺ doped systems, and minimum thermal resolution of ∼1 K. This information together with the biocompatibility of TiO₂ nanocrystals, and excitation and emissions wavelengths lying within the biological windows, favor potential applications in fluorescence and thermal imaging of biological systems.

在这项工作中，我们报告了一种基于Nd ³⁺掺杂的TiO ₂纳米晶体的潜在光学纳米温度计（NTh），其在生物窗口内运行。在808 nm激发时，使用900、1060和1340 nm附近的Nd ³⁺发射。研究了对应于1060 nm和1340 nm处的发射的荧光强度比（FIR）（FIR = I _{1060 nm} / I _{1340 nm}）作为温度在300-343 K范围内的函数。给出了Nd ³⁺离子浓度的变化，晶相对发光和相对热敏度的影响。结果发现TiO ₂与本文和以前的文献中研究的其他样品相比，掺杂有10 wt％Nd ³⁺离子并与板钛矿相结合的纳米晶体具有最高的发光发射和相对热敏性。获得的相对热敏度的最大值为0.86％％K ^-1，与其他Nd ³⁺掺杂系统相比较高，最小热分辨率约为1K 。该信息以及TiO ₂纳米晶体的生物相容性，以及位于生物窗口内的激发和发射波长，有利于在生物系统的荧光和热成像中的潜在应用。