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Rees, Kelly

University of British Columbia

Luminescent nanomaterials such as colloidal semiconductor quantum dots (QDs) are promising materials for applications in bioanalysis and imaging. QDs have become a popular choice for use alongside or as a replacement to fluorescent dyes because of their generally superior properties, including high brightness, resistance to photobleaching, and potential for colour multiplexing. QD-based materials are also well suited to advancing smartphone-based point-of-care (POC) diagnostics, where brighter fluorescent labels with specific spectral properties are essential. However, effective use of QDs requires optimized surface chemistry and bioconjugation. This thesis presents original research towards the development of dextran-functionalized QDs and other nanomaterials for applications in bioanalysis and imaging. Several dextran ligands were synthesized and used to functionalize single QDs (Dex-QDs). The Dex-QDs were thoroughly characterized and proof-of-concept applications were demonstrated, including novel tetrameric antibody complex (TAC)-based immunolabelling of breast cancer cells. To develop brighter nanomaterials, amphiphilic dextran was prepared and used in a simple and rapid emulsion-based approach for forming super-nanoparticle assemblies of many hydrophobic QDs (super-QDs). The super-QDs were bright and non-blinking, outperforming Dex-QDs in TAC-based immunolabelling and imaging of cancer cells on both a traditional research-grade microscope and a smartphone-based imaging platform. Additional colours of super-QDs were prepared using mixtures of red, green, and blue QDs, which made it possible to obtain colours of super-QDs that would be difficult to obtain from individual QDs (e.g., magenta). Amphiphilic dextran was also used to stabilize conjugated polymer nanoparticles (CPNs) and super-nanoparticle assemblies of nanomaterials other than QDs, demonstrating the generality of the approach across a range of nanomaterials. Dextran-functionalization provided multiple benefits to all of the prepared nanomaterials, including good colloidal stability, low non-specific binding, and support of immunoconjugation and immunofluorescent labelling via TACs. Overall, this thesis makes important contributions to the field of bioanalysis and imaging with QDs and other nanoparticles, addressing longstanding challenges in surface chemistry and bioconjugation, while providing a materials-based approach to signal amplification. The research advances the use of QDs for cellular imaging, in vitro diagnostics, and especially point-of-care diagnostics with smartphone-based devices.

Text

2025-01-31

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87067

Chemistry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/