ABSTRACT
A radiation-sensitive compound 2,4-hexadiyn-1,6-bis(n-butyl urethane) (HDDBU) was synthesized, characterized by FTIR spectroscopy, and introduced into a thin polyvinyl butyral film to form a radiation dosimeter for industrial irradiation facilities. The monomer polymerizes under gamma radiation, inducing change in the film spectrum in the range of 200-400 nm. According to XRD spectroscopy, the film contains monomeric HDDBU in a non-crystalline state. The dose response function, radiation sensitivity, and dependences of the response on environmental factors were studied. Uncertainty of dose measurements with the proposed dosimetry system was analyzed in detail.
ABSTRACT
Sonolysis of aqueous solutions produces H. and HO. that lead to Co-C bond cleavage in methylcob-(III)alamin (CH3-CblIII) and 2-[4-[4'-[bis(2-chloroethyl)amino]phenyl]butyroxy]ethylcob (III)alamin (Chl-HE-CblIII). Under anaerobic conditions, H. reduces CH3-CblIII to the unstable 19 e-CH3-CblII that dissociates to the alkane and CblII. Under aerobic conditions, O2 scavenges H. and Co-C bond cleavage occurs via a HO.-mediated process along with modification of the corrin ring by HO.. When H. and HO. are scavenged, there is no evidence of Co-C bond cleavage. This suggests no direct sonolysis of the Co-C bond occurs, in spite of the fact that the Co-C bond is 80 kcal/mol weaker than the H-OH bond. A bioconjugate of cob(III)alamin and the alkylating agent chlorambucil has been synthesized to give 2-[4-[4'-[bis(2-chloroethyl)amino]phenyl]butyroxy]ethylcob(I II)alamin. The chlorambucil-cobalamin complex also undergoes Co-C bond cleavage in a manner similar to that of methylcob-(III)alamin. Sonorelease of an active alkylating agent from the bioconjugate may provide a new method for the selective release of anticancer drugs and thus potentially reduce systemic toxicity.
