Magnetic Characterization of Ferritin

Abstract

Many diseases including hemochromatosis, chronic anemia, and cirrhosis result in abnormal levels of iron stores. Due to its correspondence with different physiological conditions, iron content is often used as a disease marker. 30%-50% of iron storage within the body is performed by the protein ferritin. Currently, there are indirect methods of measuring iron content using immuno-detection of iron binding proteins. The objective of this project is to develop a highly sensitive technique that can directly measure iron content based upon the magnetic character of iron; the first step is to understand the magnetic characterization of ferritin. Magnetic force microscopy (MFM), a mode of the atomic force microscope (AFM), has been shown by other research groups and our own group to be a promising method of characterizing magnetic particles. Our research uses this method to characterize ferritin in its iron bound and unbound states (termed apoferritin). MFM uses a magnetized probe to record topographical and magnetic information from samples. We compare the widely used medium moment probe to the less widely used high moment probe for our project; high moment probes were found to detect ferritin proteins with greater sensitivity than medium moment probes. Our work also reveals that MFM can characterize and differentiate between ferritin and apoferritin. MFM phase data is used to measure the iron content of our ferritin samples. The high resolution and sensitivity of MFM makes it a promising method for measuring iron content in blood samples.