Abstract
The routine use of nanomaterials in the clinic is growing ever closer with the continued development of biocompatible particles for a range of biological uses. Non-invasive imaging and therapeutic modalities that utilise light are an area of particular interest for the incorporation of semiconductor nanocrystals, which exhibit unique optical properties. Nanomaterials with near infrared optical properties, whether it be absorption or photoluminescence, are critical for use in biological systems due to the minimal absorption and scattering of light in this region. As well as developing appropriate optical properties, an understanding of the behaviour of nanomaterials in vitro is vital for the eventual use of nanomaterials in medicine.This thesis explores the preparation of such biocompatible nanomaterials, focusing on copper chalcogenides for near infrared fluorescence imaging or photothermal therapy applications. A large portion of the work focused on CuInS2 quantum dots for near infrared fluorescence imaging, looking both at organic- and aqueous-phase syntheses. Materials were optimised for near infrared photoluminescence and colloidal stability in water, which involved investigation of phase transfer processes for the organic-phase particles. Biocompatibility testing of the resulting nanomaterials indicated that encapsulated organic-phase quantum dots were highly cytotoxic, whilst the aqueous synthesis method produced quantum dots suitable for in vitro imaging. The latter were subsequently used for the optical imaging of tumour-bearing mice and demonstrated potential as near infrared fluorophores.
Alongside the preparation of these quantum dots, a near infrared imaging system for the laboratory was developed, to aid rapid characterisation of materials. The simple, cheap near infrared camera allowed for the identification of fluorescent nanomaterials immediately after synthesis, for rapid verification of synthesis success. Also, the preparation of quantum dots in bubble wrap is described as a glassware-free alternative to traditional methods. The ability to synthesise nanomaterials in a cheap and accessible way could open up this chemistry to schools and resource-limited environments.
Plasmonic copper sulfide nanocrystals were also prepared by a novel, self-capping route using a dithiocarbamate single-source precursor. The resulting nanocrystals were characterised, and attempts made to elucidate the ligands present on the surface of the particles after synthesis. Preliminary biocompatibility assessment in HeLa cells proved promising and the particles were successfully used to heat water via photothermal process.
| Date of Award | 1 Oct 2019 |
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| Original language | English |
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| Supervisor | Mark Green (Supervisor) & Maya Thanou (Supervisor) |