The main strategy for treating solid cancers is based on the very early diagnosis of a malignant tumor, and in general the smaller the tumor, the greater the likelihood of successful treatment. Magnetic Resonance Imaging (MRI), based on the nuclear magnetic resonance phenomenon, provides the possibility of detecting early malignant tumors with the assistance of appropriate contrast agents. Hence, researchers continue to develop novel magnetic materials to achieve this aim. Superparamagnetic nanoparticles have become the focus of these studies because their superparamagnetic, biocompatible and hydrophilic properties would be revealed after modifying the particle surface by suitable surfactants. Considerable research in this area has provided valuable insights; however, suitable magnetic materials that can fulfill all the requirements of MRI application are still under investigation. Surface modification of superparamagnetic nanoparticles towards their use as MRI contrast agents has been the topic for many researchers, but implementation into fully functional in vivo procedures still remains as a challenging task. In the present study, high quality monocrystalline iron oxide nanoparticles have been synthesised and surface-modified with carboxymethylated dextran as well as polyethylene glycol (PEG). Dextran and PEG macromolecules with low and high carboxyl contents were synthesized and grafted onto dopamine-iron oxide nanoparticles. Furthermore, the coating procedure was optimised to prevent aggregation among the nanoparticles. Dextran-coated and PEG-coated nanostructures were characterised by using X- ray Photoelectron Spectroscopy (XPS), Fourier Transformer Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). Consequently, mono-dispersed dextran coated nanoparticles were obtained with an approximate hydrodynamic diameter of 50 nm. The resulting coated nanoparticles exhibited the nanostructures with an excellent colloidal stability in physiological environment even at high salt concentration. The resistance to non-specific protein adsorption was investigated in an in vitro model. Both dextran-coated and PEG-coated nanoparticles displayed low non-specific adsorption. However, the free carboxyl groups could be activated to covalently immobilize proteins. / Thesis (M.Eng.Sc.)--School of Chemical Engineering, 2006.
| Identifer | oai:union.ndltd.org:ADTP/263768 |
| Date | January 2006 |
| Creators | Shi, Yunyu |
| Source Sets | Australiasian Digital Theses Program |
| Language | en_US |
| Detected Language | English |
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