Amidoxime Appended UiO-66 as a Potential Adsorbent in the ⁹⁹ Mo/ ^99m Tc Generator

The molybdenum technetium generator (99 Mo/99mTc generator) is a crucial device in the field of nuclear medicine, providing 99mTc for nuclear medicine diagnosis. However, low specific activity (LSA) 99 Mo, obtained from the neutron activation method, requires adsorbents with high adsorption performance for Mo. Amidoxime groups (AO) are a promising functional group for metal ion adsorption and separation, and MOFs are widely used as classic porous materials. Herein, (AO)-UiO-66 was synthesized and explored as a promising adsorbent for the 99 Mo/99mTc generator. (AO)-UiO-66 was an octahedral particle with a size of ∼100 nm, exhibiting a stable crystal structure under gamma (γ) irradiation doses ranging from 0 to 300 kGy. The maximum adsorption capacity of (AO)-UiO-66 for Mo was 145.8 mg/g. In the column adsorption/separation experiment of 99 Mo/99mTc, the radionuclidic purity of 99mTc in the eluent was ∼ 99.9%, and the elution yield of 99mTc was 77.2%. Notably, 99 Mo breakthrough was reached at 0.09%, satisfying the requirements of the International Pharmacopoeia (<0.1%). The adsorption mechanism was analyzed by X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT), and the coordination configuration between AO and MoO42– was elucidated, suggesting the great potential of (AO)-UiO-66 as an adsorbent for the 99 Mo/99mTc generator.