Cryo-irradiation

Cryo-irradiation is thus a promising method to sterilize protein solutions, as well as preparations derived from human blood. 

At 10 kGy and without excipients, the loss of human insulin in aqueous solutions is almost complete. Addition of radio-protecting excipients (free radicals scavengers) and cryo-irradiation allowed to decrease insulin degradation. The best radio-protector used was ascorbic acid in aqueous solution and oxidized glutathione in the frozen solutions. 

The EPR/ENDOR measurements described here have been performed on single crystals which are accurately oriented with an x-ray precession camera, x-ray irradiated, and observed at ca. 10 K. The schematic diagram of the X-band EPR apparatus is shown in Figure 18-1 [12], This cavity is a modification of one previously described by Weil et al. [13], The EPR cavity is essentially a cast epoxy, wire wound TE011 cylindrical cavity with external 100 kHz modulation coils. The Cryo-Tip portion of the cavity can be raised 6 cm for x-irradiation and subsequently lowered into the microwave cavity for EPR measurements [14], In the microwave cavity the lowest temperature of the sample is approximately 6 K. However in the irradiation position the lowest temperature is about 10 K because the sample is not as effectively heat-shielded from the room temperature vacuum shroud. 

EPR/ENDOR spectrometer apparatus that allows for irradiation of samples at helium temperatures. Therefore one has to use apparatus similar to the home-made Cryo-Tip arrangement as described above, or a Janis Dewar (which has irradiation ports) with a homemade EPR cavity as described by Bernhard and co-workers [15]. 

Shang TG, Smith KA, Hatton TA. 2006. Self assembly of a nonionic photoresponsive surfactant under varying irradiation conditions a small angle neutron scattering and cryo TEM study. Langmuir 22(4) 1436 1442. 

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