|dc.description.abstract||Nanomaterials have unique physics and chemistry properties compared with their bulk
counterparts and have been widely studied in different fields ranging from energy to
biomedicines. This thesis investigates controlled synthesis of gold nanomaterials, the
heating and interactions of gold nanomaterials with external electromagnetic and
ultrasonic fields, and their potential applications in non-invasive heat-related
Gold nanomaterials have been synthesised by the citrate reduction method with the aid
of ultrasonification. Through ultrasonification, the size of obtained spherical GNPs can
be controlled between 10nm and 15nm, and the prepared nanoplates can be controlled
between 50 nm to 150 nm. Purification process has been performed through membrane
dialysis, in order to obtain pure nanoparticles for investigating the heating behavior of
nanoparticle dispersions under EM/ultrasound field and elucidating the impurity effect.
Moreover, the purified gold nanoparticles have been characterized by various means,
such as FTIR, atomic absorption spectrometer, zetasizer, SEM, TEM and UV-Vis
absorption for the purpose of fully understand the properties of gold nanoparticle in
terms of purity, concentration, size, morphology and optical properties.
The bulk heating effects of low-concentration GNPs have been investigated by using
ultrasonic field, electromagnetic (EM) field, and laser irradiation. The results have
shown that significant bulk temperature increase can be achieved for the lowconcentration
gold nanoparticle dispersions under ultrasonic field, the EM field at 200
kHz and 400 kHz, and laser irradiation. Comparatively, the purified GNPs did not show
significant heating effect under the EM fields of 13.56 MHz and 2.45 GHz.
Different mechanisms are thereby discussed to explain the heating effects. While some
can be explained by established theories, such as the ultrasonic and laser heating, it is
still unclear about the heating effect under low frequency EM field. A few possible
reasons could be attributed to the changes of the dielectric properties and the
In addition, GNP incorporated microcapsules have been fabricated through the layer-bylayer
technology, and laser treatments of the microcapsules embedded with different
shapes of gold particles have been studied. The results have shown that matching
between the laser wavelength and the absorption band of gold nanoparticles, which can
be shifted by controlling the morphology of nanoparticles, is a prerequisite to achieve
the maximum heating effect to deform the microcapsules and hence to present the
microcapsules for biomedical uses.
In vitro (B50 cell) and in vivo (fruit fly) studies of the biocompatibilities of our
synthesised GNPs have been exanimated. The results demonstrated that
high biocompatibility for B50 cells and fruit flies. GNPs assisted laser treatment of B50
cells has shown faster thermal damage to the cells in contrast to the cells without
addition of GNPs.
Keywords: nanomaterial, gold nanoparticle, capsules, hyperthermia, ablation,
electromagnetic, ultraosound, surface Plasmon resonance, biocompatibility.||en_US