Poster abstracts
Poster number 29 submitted by Kevin Walsh
Magnetic force microscopy of ferritin(iron) and its clusters
Kevin J. Walsh (OSU Biophysics Program), Stavan Shah (OSU Department of Biomedical Engineering), Ping Wei (OSU Department of Neuroscience), Douglas Scharre (OSU Center for Cognitive and Memory Disorders), Dana McTigue (OSU Department of Neuroscience), Gunjan Agarwal (OSU Department of Biomedical Engineering)
Abstract:
Iron (Fe) is an essential metal involved in a spectrum of physiological functions. The oxidation state, mineral composition and storage of iron play a crucial role in health and disease. Ferritin is the major iron storage protein in the body consisting of an iron core primarily in the form of ferrihydrite. Encapsulation of ferritin(iron) by the surrounding protein shell, consisting of L- and H-ferritin, keep the iron core in a mono-disperse state. However, breakdown of the protein shell in lysosomes results in clustering and fusion of the iron cores into larger iron deposits and transformation of its ferrihydrite phase to biogenic magnetite. Histochemical staining, the routinely used approach to characterize tissue iron distribution, offers limited insight into the size and composition of tissue iron. One of the properties of iron which has not been adequately exploited in histology is the magnetic behavior of tissue iron.
In this study, we demonstrate the ability of Magnetic Force Microscopy (MFM), an atomic force microscopy-based technique, to distinguish between physiological and pathological iron. Superparamagnetic nanoparticles were used to determine the capability of detecting mono-dispersed and clustered iron. Additionally, ferritin(iron) was studied in-vitro in physiological and pathological rodent spleen tissue and pathological human brain tissue obtained from patients with Alzheimer’s disease. Magnetic mapping using MFM revealed regions larger in size and exhibited greater heterogeneity in magnetic signals in the pathological rodent spleen and brain tissue as compared to control tissues. Transmission electron microscopy was used to verify the distribution and size of ferritin(iron) deposits in lysosomes. The ability to describe how clustering of ferritin(iron) in health and disease influences magnetic signal can help establish MFM as a label-free tool to characterize iron which will lead to a thorough understanding of iron processes within the body.
Keywords: Magnetic Force Microscopy, Iron