# Toward Rapid Actinium-225 Purification via Membrane Adsorbers with Covalently Tethered Diglycolamide Ligands

## TL;DR

Researchers developed a new membrane material for quickly purifying Actinium-225, a radioactive element used in cancer therapy, using a special ligand that binds efficiently and releases it rapidly.

## Contribution

The study introduces a membrane adsorber with covalently tethered DGA ligands for efficient and rapid Actinium-225 purification.

## Key findings

- The membrane adsorber showed a La(III)/Ac-225 selectivity of 57 in 10 M nitric acid.
- Ac-225 was rapidly desorbed from the membrane in under 20 minutes.
- The membrane preserved surface area and porosity after functionalization.

## Abstract

Extractive diglycolamide (DGA) resins are used in several
state-of-the-art
techniques for purifying 225Ac, a promising radiometal
for targeted alpha therapy. Unfortunately, separation processes that
rely on resins are often limited to slow flow rates, high elution
volumes, and long processing times. Membrane adsorbers functionalized
with DGA ligands are an alternative separation material that may overcome
these challenges. This work presents (1) the synthesis of an aminated
tetrahexyldiglycolamide ligand, (2) the covalent tethering of the
ligand to electrospun poly­(vinylbenzyl chloride) fiber mats, and (3)
the adsorption and desorption of La­(III) and 225Ac. Chemical
and physical characterization supports the covalent tethering of the
ligand to the fiber mat, as well as the preservation of the fiber
surface area and porosity after functionalization. Equilibrium adsorption
experiments were performed with stable La­(III) and radioactive 225Ac. Trends in affinity are consistent between commercial
resins and the synthesized membrane adsorbers; however, the Langmuir
constants and the maximum binding capacity of the membrane adsorbers
were generally lower than the resins. Despite these differences, the
modeled selectivity for an equimolar solution of La­(III)/225Ac in 10 M nitric acid is 57. Furthermore, 225Ac is rapidly
desorbed from the fibers in 10 M nitric acid (<20 min). The La­(III)/225Ac selectivity and rapid 225Ac desorption indicate
this class of materials is promising for rapid radioanalytical separations.