Use of upconversion fluorescence nanoparticles in biomedical applications

Abstract

This thesis explores the characterization and biomedical applications of a new variety of fluorescent upconverting nanoparticles (UCN), PEI/NaYF44:Er,Yb, with a focus on cancer. These are 60 nm spherical particles of uniform shape and size, positive surface charge, stably soluble in de-ionized water, biocompatible with two different human cell lines and emit green and red fluorescence when excited with 980nm laser with strong photostability. The UCN conjugated to a folic acid were used for targeted imaging of live human cancer cells in vitro with high signal-to-background ratios and good detection sensitivity. The nanoparticles were imaged inside animals by injecting into various tissues of live, anaesthetized rats and illuminating with NIR laser. Human cancer cells tagged with UCN were imaged by real-time in vivo confocal microscopy after subcutaneous injection in live anaesthetized mice. UCN with zinc phthalocyanine (ZnPC) photosensitizer was used for simultaneous imaging and photodynamic therapy of cancer cells.