Final Report for research grant "Development of Methods for High Specific Activity Labeling of Biomolecules Using Astatine-211 in Different Oxidation States"
- Univ. of Washington, Seattle, WA (United States)
The overall objective of this research effort was to develop methods for labeling biomolecules with higher oxidation state species of At-211. This was to be done in an effort to develop reagents that had higher in vivo stability than the present carbon-bonded At-211-labeled compounds. We were unsuccessful in that effort, as none of the approaches studied provided reagents that were stable to in vivo deastatination. However, we gained a lot of information about At-211 in higher oxidation states. The studies proved to be very difficult as small changes in pH and other conditions appeared to change the nature of the species that obtained (by HPLC retention time analyses), with many of the species being unidentifiable. The fact that there are no stable isotopes of astatine, and the chemistry of the nearest halogen iodine is quite different, made it very difficult to interpret results of some experiments. With that said, we believe that a lot of valuable information was obtained from the studies. The research effort evaluated: (1) methods for chemical oxidation of At-211, (2) approaches to chelation of oxidized At-211, and (3) approaches to oxidation of astatophenyl compounds. A major hurdle that had to be surmounted to conduct the research was the development of HPLC conditions to separate and identify the various oxidized species formed. Attempts to develop conditions for separation of iodine and astatine species by normal and reversed-phase TLC and ITLC were not successful. However, we were successful in developing conditions (from a large number of attempts) to separate oxidized forms of iodine ([I-125]iodide, [I-125]iodate and [I-125]periodate) and astatine ([At-211]astatide, [At-211]astatate, [At-211]perastatate, and several unidentified At-211 species). Information on the basic oxidation and characterization of At-211 species is provided under Objective 1. Conditions were developed to obtain new At-211 labeling method where At-211 is chelated with the DOTA and NOTA chelation reagents. However, those species were unstable to isolation. Information is provided on those studies under Objective 2. We were successful in obtaining a highly oxidized form of arylastatine, but it did not appear to be stable in vivo. Information on those studies is provided under Objective 3. While we were not successful in obtaining reagents that contained oxidized forms of At-211 that were stable to in vivo deastatination, a lot of information was gained about the oxidation of At-211 and the stability of the species produced.
- Research Organization:
- Univ. of Washington, Seattle, WA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- FG02-08ER64666
- OSTI ID:
- 1033218
- Report Number(s):
- DOE/SC64666-1
- Country of Publication:
- United States
- Language:
- English
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