(323d) Characterization and Quantification of the Intrinsic Magnetization

Intrinsic magnetic susceptibility.  Whereas it is generally understood that most biological material is diamagnetic (repulsed by a magnetic gradient), it has been known since early work by Linus Pauling and coworkers in 1936 and 1937 that the chemical bonds between the Fe atom and the porphyrin ring changes from an ionic bond in the deoxygenated state to a covalent bond in the oxygenated state.  However, the relatively low level of magnetic susceptibility of the deoxygenated Hb has traditionally limited applications of this property.  A similar discussion can be made on the magnetic properties of various states of manganese, another common, magnetic element in cells.   

However, the development of ultra-high power, low cost, neodymium magnets and modern computer aided magnetic field designs and imaging technology has facilitated the development of instruments that can track the movement, on a cell-by-cell basis, of large numbers of cells and particles, including deoxyHb, oxyHb, and metHb containing red blood cells (RBCs) in specifically designed, and extremely powerful magnetic energy gradients.  This instrument is referred to as a Cell Tracking Velocimeter,  CTV . 

Using a combination of CTV, X-Ray Photoelectron Spectroscopy, XPS, and IPC-mass spectroscopy, IPC-MS, we have begun to characterize both the amount and oxidation state of Fe and Mn in a number of different cells and cell types, including human red blood cells, RBCs, plaques from coronary artery disease, algae, and human sperm.  In this presentation we will not only summarize our methodology to make these measurements, but also discuss the sensitivity and potential limits of this approach.  For example, with our current instrument, we are able to detect 1 x 10^-15 gr of Fe per cell, and increases in magnetic energy gradient designs indicate significant increases in sensitivity.