Permanganate-Based Synthesis of Semiconducting Metal Oxide Nanoparticles in the Protein Ferritin

Permanganate-Based Synthesis of Semiconducting Metal Oxide Nanoparticles in the Protein Ferritin Cameron Olsen Department of Physics and Astronomy, BYU Bachelor of Science This thesis investigates the reactions of Mn2+ and Co2+ with permanganate as a route for manganese and cobalt oxide nanoparticle synthesis in the protein ferritin. Permanganate serves as the electron acceptor and reacts with Mn2+ and Co2+ in the presence of apoferritin to form manganese and cobalt oxide cores inside the protein shell. Manganese loading into ferritin was studied under acidic, neutral, and basic conditions and the ratios of Mn2+ and permanganate were varied at each pH, while cobalt loading was studied at pH 8.5 only. The manganese and cobalt-containing ferritin samples were characterized by transmission electron microscopy, UV/Vis absorption, and by measuring the band gap energies for each sample. Manganese cores formed in both the acidic and basic conditions, while a mixed cobalt-manganese core formed at the desire pH. New manganese oxide cores formed in the acidic manganese trials and have absorption profiles and band gap energies that are different from the Mn(O)OH cores synthesized by the traditional method of using oxygen. These new manganese cores have indirect band-gap transitions ranging from 1.63 to 1.68 eV, which differ from the band gap energy of 1.53 eV for Mn(O)OH ferritin. In addition, an increased absorption around 370 nm was observed for the new manganese cores, suggestive of MnO2 formation inside ferritin. The mixed cobalt-manganese samples showed band gaps ranging from 1.48 eV up to 1.75 eV, which correlated with the final ratio of cobalt and manganese present in the material.