This research focuses on the microwave properties of nanoparticles for use as contrast and hyperthermia agents. Currently, visible light is used for irradiation of nanoparticles as hyperthermia agents. Additionally, visible/Near-infrared light is used for photoacoustic tomography (PAT) imaging. Compared to optical wavelengths, frequencies in microwave range transmit through tissue with high penetration depth . Thus, deep cancerous cells and malignant tissue may be treated and imaged. These nanoparticles could enable the use of a hybrid microwave/acoustic technique known as thermoacoustic tomography. Here, quantitative measurements of the heat generation in super paramagnetic iron oxide nanoparticle (SPIONs), gold nanoparticles (AuNPs), and gold nanoclusters (AuNCs) induced by microwave energy at 3 GHz, are presented and compared. Based on our experiments, SPIONs are the most efficient nanoparticles for microwave heating. Very high concentrations of SPIONs are able to convert microwave energy into heat about 22° C more than DI-water. AuNPs, which support plasmon resonances, do not provide heat under microwave irradiation as predicted by our computational analysis based on Mie Theory. AuNCs are a new form of ultra-small (<2.5 nm) AuNPs which do not support plasmonic resonances and have supra-molecular properties such as sub-conduction band transitions. Interestingly, AuNCs have the potential to absorb microwave energy and may provide an alternative to SPIONs. These nanoparticles had not yet been studied before in this frequency region. In addition, the absorption coefficient of nanoparticles were calculated using complex permittivity data from a dip probe kit and a Vector Network Analyzer (VNA) in a broad band range from 500 MHZ to 10 GHz. This method allows identification of best frequency region with highest penetration depth. In the last step, the nanoparticles with different concentrations were tested as exogenous contrast agents in a Thermoacoustic Tomography (TAT) system. TAT utilizes the penetration depth of microwave energy while producing high resolution images through acoustic waves. The addition of an exogenous contrast agent improves image quality by more effectively converting microwave energy to heat. The experiment reveals that the time resolved thermoacoustic signal (TA) from SPIONs is stronger than AuNPs and AuNCs and thus, the image contrast produced by SPIONs is stronger than the two other aforementioned nanoparticles.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Despite the advances in therapies such as chemotherapy and radiotherapy, tumours have been shown to be resistant to the treatments. Gold nanoparticles (AuNPs) have been recognized as effective radiosensitizers of low energy (e.g. 200–500 kV) X-rays, leading to the emission of Auger electrons that cause highly localised ionizing damage to cells. Spherical AuNPs were synthesised via the reduction of the chloroaurate ions by sodium citrate. Characterisation of AuNPs involved UV-visible spectrophotometry, zeta (Z) potential, dynamic light scattering (DLS) and polydispersity index (PDI) measurements for determination of surface plasmon resonance (SPR), surface charge and stability, as well as transmission electron microscopy (TEM) for hydrodynamic core sizes, size distribution width and shape of AuNPs. Both the 5 and 10 nm AuNPs were found to be anionic with λmax absorbance of 525 nm and uniform size distribution. DLS measurement at 38.12 nm and 48.50 nm, respectively for 5 nm and 10 nm AuNPs, points to aggregation of the AuNPs. However, TEM measurements confirmed the core size of the 10 nm AuNPs. Non-malignant Chinese hamster ovary (CHO-K1), brain endothelial (BEnd5), breast (MCF-10A), isolated human lymphocytes and malignant breast (MCF-7) cell lines were treated with 50 μg/ml of AuNPs, and irradiated with either 1, 2 or 4 Gy X-rays or 1 or 2 Gy p(66)/Be neutron radiation. The γ-H2AX foci assay, cytokinesis-block micronucleus assay, MTT assay and fluorescence-activated cell sorting (FACS) was used to determine that amount of double stranded breaks (DSBs) in isolated lymphocytes, the presence and number of micronuclei (MNi) within binucleated cells (BNCs), cell viability and cell cycle progression, respectively. Preliminary experiments that established the reliability of the study regarding the induction of DNA damage after the bombardment of AuNPs by scattered low kV X-rays, were carried out on lymphocytes. Combined treatment (AuNPs and radiation) resulted in more endogenous foci in comparison to lymphocytes that were treated with AuNPs only. The CHO-K1 and MCF-7 cells showed higher MNi frequencies after the combination treatment of AuNPs and radiation compared to the number of MNi in samples exposed to AuNPs and radiation separately. The AuNPs alone influenced the cellular kinetics of all cell types. Interaction indices, which is the enhancement factor of AuNPs in combination with radiation, for AuNPs and 6 MV 2 Gy X-rays of 1.6 to 1.7 and 1.3 to 1.4 have respectively been determined for CHO-K1 and MCF-7 cells, whilst that for the other cell types used in the study were not different from Unity. As expected, the interaction indices between AuNPs and p(66)/Be neutrons was lower than the interaction indices after 2 Gy X-rays, as p(66)/Be neutrons interact only with the nuclei of the AuNP's atoms and the X-ray photons interact with the orbital electrons of the atoms of the AuNPs leading to Auger electron emission. The cell viability assay showed that 50 μg/ml of AuNPs had an inhibitory effect on cellular proliferation, in all four cell linnes whereas the lower concentrations (2.5, 5 and 10 μg/ml) had no effect. Results in this study, revealed an increase in the accumulation of CHO-K1 an MCF-7 cells in the G₂/M phase of the cell cycle after being treated with AuNPs followed by X-ray radiation, suggesting that the cells have possibly been sensitised to the damaging effects of radiation. Further studies are required to quantify internalised AuNPs and to then link the possible concentration differences of the AuNPs to differences in radiation damage effects observed for the different cell types.

Yes / Lung surfactant (LS) monolayers that continuously expand and compress during breathing cycles, act as the first line barrier for inhaled nanoparticles. It is known that nanoparticles which adsorb to the surface of the surfactant layer facilitate the rearrangement of lipids and peptides at various stages of the breathing cycle. However, the structural mechanisms for this ability of the lipid rearrangement are not yet fully understood. Coarse-grained molecular dynamics simulations are performed to investigate the role of surfactant protein B (SP-B) segments (SP-B1–25) in modulating the biophysical properties of the surfactant monolayer in the presence of polydisperse gold nanoparticles (AuNPs) at different concentrations. Herein, we observe that the AuNPs significantly alter the inherent structural and dynamical properties of the monolayer and its components in three different breathing states. When adsorbed into the monolayer, the AuNPs inhibit the ability of the monolayer to recover its surface tension and other properties. The presence of SP-B1–25 in the monolayer accelerates the diffusion of the monolayer phospholipids, contrarily to the role of AuNPs on phospholipid diffusion. Also, the AuNPs and the peptides in the monolayer significantly increase their agglomeration in the presence of one another. Overall, the simulations predict that the presence of polydisperse AuNPs hampers the stability and biophysical functions of the LS in contrast to the role of the peptide. This study provides a clear view of the hydrophobic peptide role in the LS monolayer at the interface along with the interactions and the translocation of AuNPs that could have a significant impact to assess the NPs inhalation. / This work was completed with the support of University of Technology Sydney (UTS) FEIT Research Scholarship, UTS IRS (S. I. H.).

¤@¡BRole of 5-thio-(2-nitrobenzoic acid)-capped gold nanoparticles in the sensing of chromium(VI): remover and sensor This study describes a simple, rapid method for sensing Cr(VI) using 5-thio-(2-nitrobenzoic acid) modified gold nanoparticles (TNBA-AuNPs) as a remover for Cr(III) and as a sensor for Cr(VI). We discovered that TNBA-AuNPs were dispersed in the presence of Cr(VI), whereas Cr(III) induced the aggregation of TNBA-AuNPs. Due to this phenomenon, TNBA-AuNPs can be used as a sorbent material for the removal of > 90% Cr(III), without removing Cr(VI). After centrifuging a solution containing Cr(III), Cr(VI), and TNBA-AuNPs, Cr(III) and Cr(VI) were separately present in the precipitate and supernatant. In other words, TNBA-AuNPs are capable of separating a mixture of Cr(III) and Cr(VI). The addition of ascorbic acid to the supernatant resulted in a reduction of Cr(VI) to Cr(III), driving the aggregation of TNBA-AuNPs. The selectivity of this approach is more than 1000-fold for Cr(VI) over other metal ions. The minimum detectable concentration of Cr(VI) was 1 £gM using this approach. Inductively coupled plasma mass spectrometry provided an alternative for the quantification of Cr(III) and Cr(VI) after a mixture of Cr(III) and Cr(VI) had been separated by TNBA-AuNPs. The applicability of this approach was validated through the analysis of Cr(VI) in drinking and tap water. ¤G¡BFluorescent Sensing of Total, Protein-bound, Free, and Oxidized Homocysteine in Plasma through the Combination of Tris(2-carboxyethyl)Phosphine Reduction, Fluorosurfactant-Capped Gold Nanoparticles Extraction, and o-Phthaldialdehyde Derivatization This study reports a simple, selective, and sensitive method for fluorescent detection of total, protein-bound, free, and oxidized homocysteine (HCys) using tris(2-carboxyethyl)phosphine (TCEP) as a reducing agent, fluorosurfactant-capped gold nanoparticles (FSN-AuNP) as a preconcentrating probe, and o-Phthaldialdehyde (OPA) as a derivatizing agent. TCEP was used to reduce the disulfide bonds of protein-bound and oxidized HCys. FSN-AuNPs were capable of extracting HCys from a complicated complex because the FSN capping layer can stabilize the AuNPs in a high-salt solution and inhibit non-specific adsorption. HCys was selectively derivatized with OPA in the absence of a nucleophile. By taking advantage of these features, the selectivity of the proposed system is greater than 100-fold for HCys and homocystine (HCys-HCys disulfide; diHCys) compared to any aminothiols. The limits of detection (LODs) for HCys and diHCys were 4.4 and 4.6 nM, respectively. Compared to other sensors, the proposed system provides an approximately 3-300-fold improvement in the detection of HCys. Different forms of plasma HCys were determined by varying the order of disulfide reduction with TCEP. The proposed system was successfully applied to determine the total, protein-bound, free, and oxidized HCys in plasma. To the best of our knowledge, the proposed system not only provides the first method for detecting various forms of plasma HCys, but also has the lowest LOD value for HCys when compared to other sensors.