School of Chemistry - Theses

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Quantum dots for biological applications

BESTETTI, ALESSANDRA ( 2014)

The use of Quantum Dots (QDs) as an alternative to fluorescent organic dyes for the labelling of biological molecules has attracted a significant amount of interest in recent years. Due to their unique spectral and physical properties, QDs promise to overcome some of the limitations of organic dyes, such as broad emission profiles and low photobleaching thresholds. In this thesis, a flexible platform for the use of QDs in biology is presented. CdSe/ZnS core-shell QDs are rendered water-soluble and biocompatible through a polymer encapsulation technique that ensures colloidal and optical stability, low non-specific binding and that allows the nanocrystal surface to be equipped with a tunable amount of various functional groups (e.g. azides). The conjugation to biomolecules is achieved through the use of bifunctional linkers able to react via strain-promoted click-chemistry with the azide groups present on the QDs. The elements of this conjugation strategy are extremely versatile and can be used in a range of systems. As a proof-of-concept, the protein transferrin is conjugated to QDs and followed during its internalisation path in cell. Next, QDs are conjugated to antibodies and a QD-based ELISA assay is developed. Finally, the concepts are applied to a novel approach for the delivery of photodynamic therapy.