MULTI-COLOR UPCONVERSION FLUORESCENT NANOPARTICLES FOR CELL IMAGING

Abstract

Upconversion nanoparticles (UCNs), excited by NIR light and emit UV-visible light, have attracted a lot of interest in bioimaging, biodetection, bioencoding and therapeutic applications due to its advantages over conventional fluorescent techniques. It offers superior photostability, chemical stability, minimized autofluorescence background, reduced damage to cells / tissues and high penetration depth. Despite being the most efficient nanocrystal matrix for upconversion, NaYF4 upconversion nanocrystals still suffer from problems whcih limit their applications, such as inflexible tuning of fluorescence emission and limited emission colors. In this thesis, two methods- doping alkaline ions and fabricating sandwich architecture- had been explored to tune the emission of UCNs. To show the great potential of the multi-color UCNs in cell imaging, continuous monitoring of Her2 surface marker on SKBR3 cells for 6 hours was carried out with UCNs. Later on, a-tubulin and two types of surface receptors on 3T3 cells were selectively stained with the multi-color UCNs.