Ac-225 is a promising isotope for targeted alpha therapy (TAT, a personalized cancer treatment) that has shown excellent patient outcomes in clinical trials. To date, all Ac-225 used in domestic clinical trials was harvested from legacy nuclear waste at Oak Ridge National Laboratory. This legacy supply of Ac-225 is so limited that only 1 in 5,500 people who qualify for the treatment are able to receive it. One bottleneck in the Ac-225 supply chain is the slow, column-based separation process that operates at a flowrate of 1 mL/min. While resin-based extractive chromatography has long been the workhorse for medical isotope production—these purification schemes are not easily scaled to support clinically relevant production. The purification of Ac-225 requires ion-selective separations to remove Th, Ra, and lanthanides; thus rapid, highly-selective and rapid-separation materials are required.<br/><br/>To fill this need, we synthesized chelating membrane adsorbers—a scalable, high-throughput alternative to extractive resins. This work spans membrane synthesis (electrospinning), diglycolamide (DGA) ligand synthesis, covalent functionalization of the electrospun membranes, and adsorption/desorption experiments with Ac-225 and relevant competitor ions. Electrospun poly(chloromethyl styrene) membranes were functionalized with amine-terminated DGA ligands via an SN2 reaction. The resulting membranes contained 36wt% DGA which is consistent with commercially available extractive resins containing physisorbed DGA ligands. Adsorption experiments conducted in 4M, 6M and 10M nitric acid with lanthanum and Ac-225 (both trivalent ions) indicate that the separation factor between Ac-225 and lanthanum is roughly 1 to 3. Rapid desorption kinetics suggest that these DGA-functionalized membranes have the potential to accelerate the Ac-225 purification process. While these chelating membranes are being studied in the context of nuclear medicine, they serve as a promising platform for other applications which require ion-ion selectivity such as rare earth element recovery and radioanalytical chemistry

Chelating membranes enable ion-ion selectivity for medical isotope production

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