Over the past decade it has been shown that very high frequency (VHF) EPR offersgreat advantages in many types of experiments. However, to date we have seen n o documented attempts to apply this technique to viable biological systems. Thereasons for this are both technical and psychological: the sample volume at W- band (95 GHz) could be 1000 fold smaller than at conventional X-band, and microwave losses are somewhat higher. In the present work we demonstrate the prospects for VHF EPR in cellular studies. The VHF EPR has a better absolute point sensi tivity, which is essentially needed in studies of small objects (like a single c ell) or surfaces, including cellular membranes. The better g-value resolution o ffered by VHF EPR enables one to separate spectroscopicallydifferent kinds of n itroxide radicals within the same system, or radicals in different molecular env ironments (e.g. to distinguish more clearly between nitroxide molecules dissolve d in lipids, membranes, and aqueous phase of the cell). Another possible application of VHF EPR spectroscopy and imaging is in cryobiology, where nitroxide spin probes could be used to follow redistribution processes in cells during the freezing.
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