Authors:	Baki, Abdulkader
Title:	Continuous synthesis of iron oxide nanoparticles for biomedical applications
Online publication date:	24-Oct-2022
Year of first publication:	2022
Language:	english
Abstract:	Within the exciting area of nanotechnology, magnetic nanoparticles constitute an important subclass of smart materials with a huge number of applications in industry, life science, and medicine. Controlled synthesis approaches and reliable characterization of the magnetic nanoparticles are key factors for the development of novel magnetic nanoparticle systems. Numerous synthesis routes for batch production of magnetic nanoparticles have been established each exhibiting specific advantages and disadvantages. Quite often, batch-to-batch variations and broad size distributions of the resulting magnetic nanoparticles lead to a reduced performance in the envisaged applications. An alternative approach provides the continuous micromixer synthesis of magnetic nanoparticles with promising higher reproducibility and scalability compared to conventional methods. In this approach, spatial and temporal separation between nucleation and growth of the particles, beneficial high heat and mass transfer, and the capability to separately control reaction parameters such as temperature and residence time can be achieved. Due to their huge magnetic moments, single core magnetic nanoparticles with core sizes larger than 20 nm are of particular interest for several biomedical applications. However, to synthesize magnetic nanoparticles of these sizes that remain stable in physiological environment, is very challenging due to the strong interparticle interactions. Even though great efforts of numerous researchers have been made, stably dispersed single-core magnetic nanoparticles with average core sizes above 20 nm are so far not accessible neither by conventional batch methods nor by continuous synthesis approaches. In this work, the continuous micromixer synthesis of magnetic single core iron oxide nanoparticles with core diameters up to 40 nm stably dispersed in aqueous environment has been established. The synthesis route relies on modifications of the synthesis method by Sugimoto and Matijević, where ferrous hydroxide is precipitated and then oxidized to obtain magnetic nanoparticles. The influence of the two main parameters in micromixer synthesis, the reaction temperature and the residence time, ABSTRACT VII was thoroughly characterized. To avoid agglomeration or further oxidation, the magnetic nanoparticles were stabilized with tannic acid. Additional protein coating of the nanoparticle surface with bovine serum albumin was successfully achieved to further improve their stability in physiological environments. The resulting physicochemical and magnetic properties as well as the reproducibility of continuous micromixer synthesis in comparison to conventional batch synthesis were determined. To this end, core and hydrodynamic sizes, size distribution, and particle morphology were investigated by transmission electron microscopy and differential centrifugal sedimentation. The crystal structure of MNP was studied using X-ray diffraction. To study the changes in particle surface, zeta potential measurements and gel electrophoresis were carried out. AC-susceptibility measurements of the linear magnetic susceptibility, reflecting changes in the hydrodynamic properties of the MNP systems were investigated. The colloidal stability and changes in the magnetic and physicochemical properties of the synthesized magnetic nanoparticles were analysed in the presence of physiological NaCl concentrations. The capability of the micromixer synthesized magnetic nanoparticles as tracer for magnetic particle imaging was determined by magnetic particle spectroscopy measurements. Nuclear magnetic resonance relaxivity measurements were carried out to assess the performance of the magnetic nanoparticles as contrast agent in magnetic resonance imaging. Finally, the heat generation capacity of the magnetic nanoparticles in magnetic fluid hyperthermia as a therapeutic approach for cancer treatment was determined by AC magnetic loss measurements.
DDC:	500 Naturwissenschaften 500 Natural sciences and mathematics 540 Chemie 540 Chemistry and allied sciences 610 Medizin 610 Medical sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-7777
URN:	urn:nbn:de:hebis:77-openscience-ec08bfcb-057f-4ca7-b899-89289737da2d9
Version:	Original work
Publication type:	Dissertation
License:	CC BY-ND
Information on rights of use:	https://creativecommons.org/licenses/by-nd/4.0/
Extent:	IX, 257 Seiten ; Diagramme
Appears in collections:	JGU-Publikationen