Synthesis, characterization and application of magnetoferritin nanoparticle by using human H chain ferritin expressed by Pichia pastoris.

Protein-based nanoparticles have developed rapidly in areas such as drug delivery, biomedical imaging and biocatalysis. Ferritin possesses unique properties that make it attractive as a potential platform for a variety of nanobiotechnological applications. Here we synthesized magnetoferritin (P-MHFn) nanoparticles for the first time by using the human H chain of ferritin that was expressed by Pichia pastoris (P-HFn). Western blot results showed that recombinant P-HFn was successfully expressed after methanol induction. Transmission electron microscopy (TEM) showed the spherical cage-like shape and monodispersion of P-HFn. The synthesized magnetoferritin (P-MHFn) retained the properties of magnetoferritin nanoparticles synthesized using HFn expressed by E. coli (E-MHFn): superparamagnetism under ambient conditions and peroxidase-like activity. It is stable under a wider range of pH values (from 5.0 to 11.0), likely due to post-translational modifications such as N-glycosylation on P-HFn. In vivo near-infrared fluorescence imaging experiments revealed that P-MHFn nanoparticles can accumulate in tumors, which suggests that P-MHFn could be used in tumor imaging and therapy. An acute toxicity study of P-MHFn in Sprague Dawley rats showed no abnormalities at a dose up to 20 mg Fe Kg body weight. Therefore, this study shed light on the development of magnetoferritin nanoparticles using therapeutic HFn expressed by Pichia pastoris for biomedical applications.