Tailored Nanoparticles for Nanotoxicological Investigations

Anthony Musumeci (2010). Tailored Nanoparticles for Nanotoxicological Investigations PhD Thesis, The Australian Institute for Bioengineering and Nanotechnology, The University of Queensland.

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Author Anthony Musumeci
Thesis Title Tailored Nanoparticles for Nanotoxicological Investigations
School, Centre or Institute The Australian Institute for Bioengineering and Nanotechnology
Institution The University of Queensland
Publication date 2010-02
Thesis type PhD Thesis
Supervisor Dr Darren Martin
Dr Rod Minchin
Dr ZhiPing Xu
Dr Suzanne Smith
Total pages 213
Total colour pages 19
Total black and white pages 194
Subjects 06 Biological Sciences
Abstract/Summary The production of engineered nanoparticles has experienced exponential growth over the past several decades. As a result, they are used in a number of existing consumer products and developing technologies. However, little is currently understood about their biological interactions and toxicity. The basic conundrum faced by nanotechnology researchers, is that the properties that make nanoparticles so promising (i.e. they behave very differently from bulk forms of the same material) also make their effect on human health and the environment incredibly difficult to predict. This is substantiated by regulatory and government agencies around the world who are currently scrambling to generate and implement applicable legislation for the safe manufacture, use and disposal of engineered nanoparticles and nano-products. Emerging research has suggested that the biological response of nanoparticles may be dependent on a vast number of physicochemical properties, including surface chemistry, size, shape, and chemical composition to name just a few. However a lack of comparative, robust safety assessments currently exists. A primary reason behind the lag in nanotoxicology data lies in the lack of robust and highly sensitive labelling methodologies required to perform true and accurate toxicity investigations. A key requirement in designing adequate labelling techniques is that the native physical and biological characteristics of the nanoparticles are not altered. In this thesis, the tailored synthesis and non-invasive labelling (both fluorescence and radiolabelling) for two important classes of nanomaterials; layered double hydroxide (LDH) synthetic nanoclay and titanium dioxide (TiO2) have been investigated. Synthetic LDH nanoparticles of narrow particle size distribution were synthesised through a combination of chemical coprecipitation, hydrothermal treatment and post-preparative ultracentrifugation methods. Radiolabelling of LDH nanoclay was undertaken using 57Co2+ and/or 67Ga3+ gamma emitting radioisotopes. The dissolution properties of the radiolabelled LDH nanoparticles were assessed over a range of biologically relevant pH, and showed reduced stability at acidic pH. A dual radiolabelling concept was introduced and it’s potential to follow not only nanoparticle distribution and persistence but also real-time nanoparticle dissolution in vivo was discussed. Intercalation of fluorescent anionic dye molecules into the LDH crystalline structure was investigated and yielded a series of highly fluorescent nanoparticles exhibiting negligible change in the native physicochemical characteristics. Fluorescent labelling of LDH nanoparticles by means of interlatice substitution with the rare earth lanthanide, terbium, yielded a weakly fluorescent nanoparticle dispersion. However, surprisingly tailorable morphological features were realised. These developed labelling techniques may be applicable to a host of similar nanoclay materials that are currently used in large quantities in a range of consumer products. Tailored libraries of TiO2 nanoparticles of varying shape (i.e. nanosphere, nanorod and nantoube) and size were synthesised through a combination of sol-gel and hydrothermal treatment methods. Following synthesis, stable anchoring of dihydroxybenzene ligands to the highly curved nanoparticle surface facilitated further functionalisation with fluorescent dye or bifunctional cage ligands for radiolabelling studies. An exciting surface enhanced Raman spectroscopy (SERS) phenomenon was observed from the adsorbed dihydroxybenzene ligands, which formed a charge transfer complex, and led to ~1,000-fold enhanced detection sensitivity. This phenomenon was highly unique, in that it is one of the first reported observations of SERS emanating from nanostructured metal oxide surfaces. Radiolabelling of TiO2 nanoparticles was achieved through the attachment of the bifunctional cage ligand, 1-N-(4-aminobenzyl)-2,6,10,13,16,19-hexaazabicyclo[6.6.6])eicosane-1,8-diamine to the TiO2 nanoparticle surface at a range of surface functionalisation levels. Furthermore, the developed radiolabelling method may be applicable to a host of other metal oxide nanoparticles (i.e. Fe2O3 and ZrO2) and facilitate ultrahigh sensitivity tracking with the use of positron emission tomography. The work presented in this thesis provides a solid foundation and new insights into the generation and labelling of well defined nanoparticle libraries for nanotoxicological investigations.
Keyword Nanoparticles
fluorescent labelling
Layered double hydroxide
Titanium dioxide
Additional Notes 26, 32, 35, 39, 55, 56, 73, 77, 83, 88, 89, 109, 126, 149, 150, 160, 186, 188, 192

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Created: Wed, 17 Nov 2010, 06:03:59 EST by Mr Anthony Musumeci on behalf of Library - Information Access Service