Production of brighter nanoparticles for optical imaging

Despite many promising advancements in the development of fluorescent probes for imaging studies, there still remains several optical and chemical drawbacks for using these probes in vivo; and so the search for a new generation of bioimaging probes continues. In this study, the chemical and optical properties of (i) Ruby and (ii) Silicon Vacancy (SiV) diamonds were examined to assess their suitability for future in vivo bioimaging applications. Both materials are excellent candidates due to unique optical properties in the near-infrared (NIR) spectral range. However, methods to control the ‘brightness’ of these candidates are lacking. This Thesis first describes the successful synthesis of nanoruby using microwave combustion methods. Nanoruby particles (~180nm) were produced with the desired chromium concentration in the Al2O3 crystal lattice. These particles showed the characteristic NIR fluorescence emission doublet (~692/693nm) and maximum ‘brightness’ for chromium concentrations up to 2mol%. Methods describing the isolation of SiV nanodiamonds, grown from chemical vapour deposition films, are then detailed. These single SiV nanodiamonds exhibited a narrow emission peak (~739nm). Together, the successful synthesis, isolation, and characterisation of nanoruby and SiV nanodiamond particles with desired NIR optical properties are a key step towards helping achieve a new generation of ‘brighter’ bioimaging probes.