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UBC Theses and Dissertations

Development of glassy organic dots for biological imaging Primrose, William

Abstract

Fluorescent probes are an essential tool in the life sciences, with applications in chemical and biomolecular sensing, cellular imaging, and light-driven therapeutics. Luminescent nanoparticles can offer advantages over small molecules for such applications, including enhanced brightness and photostability and the opportunity to use one probe for multiple applications. This work centers around designing luminescent probes by describing i) the design of novel red-emissive fluorophores, ii) the optimization of a novel class of nanoparticles, and iii) the application of these nanoparticles for cellular imaging. The development of deep-red emissive thermally activated delayed fluorescence (TADF) emitters is important for these applications, as red light can better penetrate biological tissue, and the long-lived fluorescence can be resolved against the short-lived fluorescence naturally occurring in living samples using time gating. Three novel dendritic donor–acceptor TADF emitters, based on the dibenzo[a,c]dipyrido[3,2-h:20-30-j]-phenazine-12-yl (BPPZ) acceptor core were designed. These emitters exhibit yellow to deep-red emission and have long lifetimes in solution and in the solid state; the thermal, electrochemical, and photophysical properties of each emitter were also characterized and compared. One of these emitters was then used in the preparation of luminescent glassy organic dots (g-Odots), which are emerging as promising nanoparticles for bioimaging, exhibiting excellent brightness and photostability attributed to their glassy, rigid matrix. Here, we investigated methods to control g-Odot size while retaining the glassy interior of the nanoparticles. Annealing of the glassy host material was explored as a post-synthetic step to promote the glass transition of the particles. Host-to-surfactant ratios were also investigated as a simple route to tunable particle sizes. Centrifugation and size exclusion chromatography were also examined as methods to fractionate g-Odots by size after synthesis. Lastly, g-Odots made with several different state-of-the-art emitters were used as bioimaging probes to investigate the long-term stability, non-linear optical properties, and cellular localization of these particles in multiple mammalian cell lines. These were directly compared to polymeric nanoparticles in some studies and in others, cellular imaging was carried out exclusively with polymeric nanoparticles to evaluate the effects of using different nanoparticle architectures.

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Attribution-NonCommercial-NoDerivatives 4.0 International