ETD

• fluorescence
• functionalization
• luminescent probes
• microscopy
• photoluminescence
• rare-earth doped nanoparticles
• ratiometric luminescence thermometry
• spectroscopy

In this thesis, YF₃:Er³⁺ nanoparticles are investigated as potential probes for intracellular imaging. Their photoluminescence emission spectra are studied, and the excitation mechanism is shown to be linear based on the excitation power dependence of the emitted intensity. The ability of these nanoparticles to measure local temperature is also evaluated, as a first step towards their possible use as nanothermometers in the intracellular environment. The nanoparticles are then functionalized with poly(acrylic acid) (PAA) to improve their water dispersibility and cellular uptake in HeLa cells. Cell internalization experiments show that functionalized nanoparticles are internalized more efficiently. Confocal and wide-field microscopes are characterized through point spread function (PSF) measurements before being employed for cell imaging. Finally, time-gated imaging is found to be the most effective technique for detecting YF₃:Er³⁺ nanoparticles, especially when internalized inside cells.