Investigation of radiation damage to biological specimens at water window wavelengths

Abstract

This article reports the continuation of a series of experiments investigating the effects of soft x-ray radiation damage on the contractile elements of mammalian striated muscle (myofibrils), using their ability to contract as a functional assay. The myofibrils were exposed to 385 eV x rays. This energy is within the ‘‘water window’’ between the oxygen and carbon K edges, where the x-ray absorption coefficient of biological materials, such as protein, is about an order of magnitude greater than that for water. An exposure of 8×105 photons μm−1 was found to prevent contraction in the majority of myofibrils. Preliminary results indicate that it is possible to increase this exposure level by approximately 25% by adding the radioprotective dimethyl sulphoxide (DMSO), an OH radical scavenger to the myofibril buffer during irradiation. This suggests that OH radicals are important in the inactivation of myofibrils through irradiation.

Soft X‐ray microscopy with a cryo scanning transmission X‐ray microscope: I. Instrumentation, imaging and spectroscopy

“…Kirz et al, 1995;Thieme et al, 1998). However, as with other techniques using ionizing radiation for probing the specimen, radiation damage limits studies of hydrated specimens at room temperature (Foster et al, 1992;Williams et al, 1993). Soft X-ray imaging at 50 nm resolution typically involves a dose to the specimen of , 10 6 Gray.…”

Dose efficient Compton X-ray microscopy

“…Biological and soft-matter samples are more easily damaged by radiation than hard materials. Keeping below the tolerable X-ray exposure limits the strength of the image obtained and thus the achievable imaging resolution [18][19][20]. Current X-ray microscopy techniques operate near this limit.…”

Imaging with Electrons, X-rays, and Microwaves

“…The image was taken at the STXM developed at the Synchrotron Light Source at the Brookhaven, National Laboratory, for which Dr. Browne had designed the specimen stage. The myofibril was supported by a thin film of silicon nitride in an environmental cell (Foster et al, 1992). Wavelength in the water window: 3.2-3.5 nm corresponding to reduced oxygen absorption; pixel size: 25 nm.…”