Ferritin-based hybrid nanocomposites for enzyme-mimetic catalytic activity

Abstract

In this thesis natural and synthetic hybrid ferritin are studied from three different perspectives:The catalytic activity of platinum nanoparticle-apoferritin nanocomposites is characterized focusing onthe catalase and superoxide dismutase enzyme mimetic activities. The possibility of tuning the activitieswith a variety of inhibitors was studied. The interaction between the gold nanoparticles encapsulatedwithin apoferritin with no catalase activity and mercury ions is also characterized. Owing to thisinteraction, the activation on catalytic activity was observed. Subsequently, a mechanism for the catalyticreaction is proposed. In addition, the bioinorganic ferroxidase activity of encapsulated platinumnanoparticles specifically within a homopolymeric L-chain apoferritin is studied. The resulting hybridnanoparticle gains ferroxidase activity and becomes able to mineralize iron in a similar way naturalferritin does. Furthermore, a new intrinsic property of ferritin L-chain is identified and characterized. Byseparating the redox reaction of iron oxidation and reduction of Cytochrome C (Cyt-c) ferritin proteinshell, it was identified that only the L-chain allows for an efficient reduction of Cyt-c and in consequenceconduction of electrons. Finally, the demineralization of the ferritin mineral induced by illumination withlight with various wavelengths is characterized. With iron being essential for the cellular metabolism, thedemineralization effect in cell cultures once those are exposed to blue light was explained. These newfindings are considered of importance for future investigation of biochemical processes happening innature that involve ferritin.