Synthesis, Characterization, and Functionalization of Magnetic Iron Nanoparticles for Enhanced Biological Applications

• Main Author: Warren, Christopher
• Format: Others
• Published: VCU Scholars Compass 2013
• Subjects: Iron Nanoparticles; Chemistry; Physical Sciences and Mathematics
• Online Access: http://scholarscompass.vcu.edu/etd/3283; http://scholarscompass.vcu.edu/cgi/viewcontent.cgi?article=4282&context=etd

The transition metal ferrites of composition MFe2O4 where M is Fe, Co, or Ni are well established materials for various biological applications due to their interesting magnetic properties. Their elemental and stochiometric composition can be easily manipulated which allows further tuning of their ferrimagnetic properties. By changing the identity of M and by changing the crystallite size of the ferrites, nanocrystals with diverse magnetic properties can be systematically produced. Furthermore, ferrites are more stable in diverse chemical environments, as compared to metallic nanoparticles, which make ferrites particularly useful for a broad range of biomedical applications, especially in the field of magnetic resonance imaging and cell labeling. In this work, spinel ferrites of composition CoFe2O4, NiFe2O4, and Ni.5Co.5 Fe2O4 were synthesized by a polyol method utilizing ethylene glycol as the solvent, reducing agent, and surfactant. The nanoparticles produced were surface coated with 3-aminopropyltriethoxy silane to increase solubility as well as to serve as an anchor for further conjugation with targeting substrates such as peptides and antibodies. The first part of this dissertation was focused on using the polyol method to produce nanoparticles of various metallic compositions. In each case, the polyol method provided an easy one-pot method to produce metallic as well as metal oxide nanocrystals. Utilizing the polyol method, ferrites of CoFe2O4, NiFe2O4, and Ni.5Co.5 Fe2O4 were produced with size ranges between 20 nm and 50 nm depending on the reaction time in the polyol. The second part of this dissertation was concerned with the functionalization of the nanoparticles to serve as an anchor for further conjugation with targeting substrates in the immunoaffinity separation of food borne pathogens. These nanoparticles were functionalized using an anti-E. coli O157:H7 antibody, mixed with a food matrix, and then subsequently removed from the food matrix by an external magnet in order to be analyzed by Matrix Assisted Laser Desorption Ionization/Time of Flight (MALDI/TOF) Mass Spectrometry as a rapid identification method of bacterial pathogens. Furthermore, magnetic resonance imaging (MRI) was carried out on the polyol produced ferrites in order to measure the transverse relaxation time (T2) of the nanoparticles in order to investigate the size dependence and crystallite composition of the particles ability to affect the transverse relaxivity rarte (r2). Further understanding of how ferrite composition and crystallite size affect their magnetic properties and resulting MRI contrast abilities will provide insight into the best materials for the next generation of contrast agents. Lastly, the ability of nanoparticles to serve as a stationary phase material for reversed phase ultrahigh pressure liquid chromatography will be discussed as a novel separation technique.