Subtissue thermal sensing based on neodymium-doped LaF3 nanoparticles

In this work, we report the multifunctional character of neodymium-doped LaF3 core/shell nanoparticles. Because of the spectral overlap of the neodymium emission bands with the transparency windows of human tissues, these nanoparticles emerge as relevant subtissue optical probes. For neodymium contents optimizing the luminescence brightness of Nd3+:LaF3 nanoparticles, subtissue penetration depths of several millimeters have been demonstrated. At the same time, it has been found that the infrared emission bands of Nd3+:LaF3 nanoparticles show a remarkable thermal sensitivity, so that they can be advantageously used as luminescent nanothermometers for subtissue thermal sensing. This possibility has been demonstrated in this work: Nd3+:LaF3 nanoparticles have been used to provide optical control over subtissue temperature in a single-beam plasmonic-mediated heating experiment. In this experiment, gold nanorods are used as nanoheaters while thermal reading is performed by the Nd3+:LaF3 nanoparticles. The possibility of a real single-beam-controlled subtissue hyperthermia process is, therefore, pointed out.