THESIS_JADAVPUR UNIVERSITY_2016
Soumya BhattacharyaThe current thrust toward the so called intelligent materials relies on the precise interplay among structures, organization, and dynamics in determining functional response. It is on the “nanoscale” that all the natural sciences meet and intertwine. This inherent interdisciplinary nature of nanotechnology poses a challenge and offers enormous potential for fruitful cross fertilization in specialist areas. Alongside this, is the growing realization that the traditional methods of “heat and beat” will not be able to address the requirements of future advanced materials. Future technological advances are becoming increasingly dependent on our ability to design and customize materials. Advances in our ability to probe materials down to their atomic structures have fueled a renewed interest in imitating natural processes, initially in the laboratory, and ultimately, at the industrial scale. The field of “Biomimetics” basically deals with the ways in which the transfer of knowledge from biology to technology is possible. Identical copying from nature to technology is not feasible; instead, “Biomimetics” encompasses a creative conversion into technology that is often „new invention‟ than a blueprint of nature. More precisely, this thesis focuses more on “biomineralization” i.e., insights into the scope and nature of materials chemistry at the organic-inorganic interface. General principles that can be applied by physicists who are not at all involved in biology are integration instead of additive construction, optimization of the whole instead of maximization of a single component feature, multi-functionality instead of mono-functionality, energy efficiency and development via trialand- error processes. Based on the above, this thesis has attempted to biomimetically synthesize, at ambient conditions, the very important system of nanosized iron oxide (magnetite, maghemite) with a very precise control of its morphology using first a synthetic template and then a combination of proteins and polymer to harness better bio medical advantage. These different iron oxides have been well characterized using a variety of characterization techniques like X-ray Diffraction, Transmission Electron Microscopy, Atomic Force Microscopy, Confocal Microscopy, Dynamic Light Scattering, Circular Diachroism, Magnetometry, Fourier Transform Infrared Spectroscopy Fluorescence Spectroscopy, Raman Spectroscopy, X-ray Photoelectron Spectroscopy, Circular Diachroism, Mossbauer Spectroscopy and Positron Annihilation Spectroscopy. Two biomedical applications: magnetic hyperthermia and magnetic resonance imaging (MRI) have been studied and the best template identified. Of the two systems studied, the mice liver and the brain, the MRI results show only enhanced liver contrast. It was in this connection that we decided toincorporate graphene to iron oxide, just to see whether the hydrophobicity of graphene enables crossing of the predominantly hydrophobic blood brain barrier. For this, a method was developed to exfoliate natural graphite directly to graphene using collagen protein; a few reports did exist of researchers using genetically modified proteins to do the same. This collagen modified graphene when used for the synthesis of iron oxide changed the phase of iron oxide from the above mentioned magnetite and maghemite to epsilon iron oxide. This led to some deviation from the planning of the thesis and this phase was studied in some depth. Three-dimensional tissue heating has been simulated using COMSOL Multiphysics using the Penne‟s bioheat transfer model which however needs to be validated with in vivo results. In short, this thesis has attempted a complete package of synthesis of nanosized iron oxides at ambient condition, its prospective applications and modelling to continuously improve on. It opens up further research areas mainly in the area of spintronics and energy applications because of the presence of graphene.
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