IDBR: Rapid Scan Electron Paramagnetic Resonance Spectrometer

University Of Denver, Denver CO

Investigators

Abstract

A grant has been awarded to Dr. Sandra Eaton at the University of Denver to build a rapid-scan electron paramagnetic resonance (EPR) spectrometer. EPR spectroscopy is a method to study molecules with unpaired electrons including organic radicals and metal ions that play many crucial roles in healthy and diseased biological systems. In this technique a magnetic field is used to distinguish, quantitate, and measure changes in unpaired electrons in different types of molecules and in different environments. Over the approximately 60 years since the technique was discovered many important biological discoveries have been made using this type of spectroscopy. A new way of detecting the signal is proposed, which will improve the information that can be obtained for the following types of samples. In many important biological applications the concentrations of the signals change quickly, which makes it difficult to record information accurately. For other types of radicals the traditional process of detecting the signals distorts the information in the spectra. The change in the detection method will also improve sensitivity for high resolution imaging of biological samples. Furthermore, this technique permits measurements of the rate at which energy that is absorbed by the unpaired electrons is released back to the surroundings ? this measurement is hard to do with current instrumentation, but provides useful insights into motion of molecules. To make these developments as widely applicable as possible, the system will be developed for the energy range that is most widely used in commercial spectrometers. Most EPR spectrometers record the signal by changing the magnetic field at rates up to a few gauss per second while monitoring the absorption of energy by the unpaired electrons. A spectrometer system will be designed and built to record the signals while changing the magnetic field at rates of many thousands of gauss per second. The hardware to drive the fast scans and to detect the signal will be designed, built, and systematically tested. The use of a very fast device that converts the signal from the spectrometer into information that can be averaged and stored in a computer will permit recording the complete spectrum thousands of times per second. Computer processing of the signal will be used to extract the spectral information. A fully integrated hardware and software system will be developed. Where possible, components from commercially-available instruments will be incorporated into the system so that the design developed with this funding can made available to other laboratories. The capabilities of the system will be demonstrated with biological samples. The instrumentation developed with this funding will open new vistas for application of this technique in the biological community. The system will be well documented to optimize transfer to other laboratories and hopefully stimulate commercial production as an accessory to existing spectrometers. All circuit diagrams and mechanical designs will be openly available. Students at all levels from undergraduate to graduate and postdoctoral associates will be involved in this interdisciplinary projects that bridges biology, chemistry, computer science, and engineering. Results will be presented at professional conferences and the equipment will be demonstrated to visitors to the laboratory.