| Abstract [eng] |
During the past decade, lanthanide-doped upconverting nanoparticles (UCNPs) have been extensively investigated due to the advantages associated with their unique luminescent properties. In general, these nanoparticles can convert near-infrared (NIR) excitation light into the ultraviolet, visible and NIR emission light via a multiphoton process known as upconversion. Compared with traditional semiconductor quantum dots or organic fluorophores, UCNPs show superior features such as sharp emission peaks, long emission lifetime, high chemical stability, high resistance to photobleaching and low toxicity. Although these features make UCNPs promising candidates for biomedical applications, a number of limitations still need to be addressed: the small size, rational design and appropriate co-doping strategy. In this dissertation, the synthesis and characterisation of multifunctional lanthanide-doped (Yb3+ and/or Er3+) nano and micro size NaGd(Yb)F4 particles are presented. In addition, the single (NaGdF4) and double (NaYbF4@NaGdF4) shell coating was applied in order to tune and enhance the upconversion luminescence. Furthermore, the temperature-sensing and thermochromic properties of UCNPs are examined. Finally, the cellular metabolic activities as well as the distribution of nanoparticles in human breast cancer cells were evaluated. |
