A Solid-State Support for Separating Astatine-211 from Bismuth

Abstract

Increasing access to the short-lived α-emitting radionuclide astatine-211 (211At) has the potential to advance targeted α-therapeutic treatment of disease and to solve challenges facing the medical community. For example, there are numerous technical needs associated with advancing the use of 211At in targeted α-therapy, e.g., improving 211At chelates, developing more effective 211At targeting, and characterizing in vivo 211At behavior. There is an insufficient understanding of astatine chemistry to support these efforts. The chemistry of astatine is one of the least developed of all elements on the periodic table, owing to its limited supply and short half-life. Increasing access to 211At could help address these issues and advance understanding of 211At chemistry in general. We contribute here an extraction chromatographic processing method that simplifies 211At production in terms of purification. It utilizes the commercially available Pre-Filter resin to rapidly (<1.5 h) isolate 211At from irradiated bismuth targets (Bi decontamination factors ≥876 000), in reasonable yield (68–55%) and in a form that is compatible for subsequent in vivo study. We are excited about the potential of this procedure to address 211At supply and processing/purification problems.

211At on gold nanoparticles for targeted radionuclide therapy application

“…Research is also underway on other methods, which have the potential to increase the yield of 211 At. 55,56 Another method to obtain 211 At is by irradiating 209 Bi with heavy-ions such as Li to create 211 Rn, with the equations given as follows 209 Bi( 7 Li,5n) 211 Rn…”

“…Currently, developments are taking place on both fronts and hopefully, this issue can be remedied in the next few years. 48,55,56 Fig. 6 LDOS plot of (a) At on Au (111) and (b) At on Au(211).…”

“…Research is also underway on other methods, which have the potential to increase the yield of 211 At. 55,56…”

Overview of the Most Promising Radionuclides for Targeted Alpha Therapy: The “Hopeful Eight”

“…Nevertheless, even if an automated process was recently developed for wet extraction, dry distillation is still widely used for purification of 211 At. It is important to note that alternative methods based on the wet chemistry route were recently reported for purification and isolation of 211 At, as purification on a tellurium-packed column [ 93 ], a solid-state support inert polymer resin [ 94 ] or strong anion exchange SPE spin column [ 95 ] or extraction with organic solvents such as 3-octanone or methyl isobutyl ketone [ 96 ].…”

Ion exchange behavior of astatine and bismuth

“…[42][43][44][45] However, some research studies after the target dissolution again apply elevated temperatures to evaporate the solution to dryness as a required step to convert their matrix to hydrochloric medium. 46 Keeping in mind the At volatility and corresponding radiation safety concerns, a new approach to remotely separate At from Bi in nitric acid media was developed by our team. 14,45,47 The principal difference is that the target dissolution solution (nitric acid) without any chemical manipulation is loaded onto a column, selectively sensitive only to At, while Bi and radioimpurities ( 18 F, 24 Na, 58 Co, 66,67 Ga, 109,111 In, 170 Lu) pass through the column.…”