LiAl5O8:Fe3+ and LiAl5O8:Fe3+ Nd3+ as a New Luminescent Nanothermometer Operating in 1st Biological Optical Window

摘要

New types of contactless luminescence nanothermometers, namely, LiAl O :Fe and LiAl O :Fe , Nd are presented for the first time, revealing the potential for applications in biological systems. The temperature-sensing capability of the nanocrystals was analyzed in wide range of temperature (−150 to 300 °C). The emission intensity of the Fe ions is affected by the change in temperature, which induces quenching of the T ( G) → A ( S) Fe transition situated in the 1st biological window. The highest relative sensitivity in the temperature range (0 to 50 °C) was found to be 0.82% °C (at 26 °C) for LiAl O : 0.05% Fe nanoparticles that are characterized by long luminescent lifetime of 5.64 ms. In the range of low and high temperatures the S was calculated for LiAl O :0.5% Fe to be 0.92% °C at −100 °C and for LiAl O :0.01% Fe to be 0.79% °C at 150 °C. The cytotoxicity assessment carried out on the LiAl O :Fe nanocrystals, demonstrated that they are biocompatible and may be utilized for in vivo temperature sensing. The ratiometric luminescent nanothermometer, LiAl O :Fe , Nd , which was used as a reference, possesses an S = 0.56%/°C at −80 °C, upon separate excitation of Fe and Nd ions using 266 nm and 808 nm light, respectively.