TiO2 Decorated Low-Molecular Chitosan a Microsized Adsorbent for a 68Ge/68Ga Generator System

We report column material for a 68Ge/68Ga generator with acid resistance and excellent adsorption and desorption capacity of 68Ge and 68Ga, respectively. Despite being a core element of the 68Ge/68Ga generator system, research on this has been insufficient. Therefore, we synthesized a low molecular chitosan-based TiO2 (LC-TiO2) adsorbent via a physical trapping method as a durable 68Ge/68Ga generator column material. The adsorption/desorption studies exhibited a higher separation factor of 68Ge/68Ga in the concentration range of HCl examined (0.01 M to 1.0 M). The prepared LC-TiO2 adsorbent showed acid resistance capabilities with >93% of 68Ga elution yield and 1.6 × 10−4% of 68Ge breakthrough. In particular, the labeling efficiency of DOTA and NOTA, by using the generator eluted 68Ga, was quite encouraging and confirmed to be 99.65 and 99.69%, respectively. Accordingly, the resulting behavior of LC-TiO2 towards 68Ge/68Ga adsorption/desorption capacity and stability with aqueous HCl exhibited a high potential for ion-exchange solid-phase extraction for the 68Ge/68Ga generator column material.

Development of a fast characterization setup for radionuclide generators demonstrated by a 227Ac-based generator

The development of a setup for a fast online characterization of radionuclide generators is reported. A generator utilizing the mother nuclide 227Ac sorbed on a cation exchange resin is continuously eluted by using a peristaltic pump. To allow continuous and pulse-free elution of a large volume over extended time periods a 3D-printed interface designed to remove pressure-oscillations induced by the pump was placed between pump and generator column to ensure undisturbed generator elution. The eluate of the generator is passed through a 3D printed flow cell placed inside a borehole Na(Tl)-scintillation detector for high counting efficiency. Alternatively, a HPGe detector suitable for nuclide identification was used to demonstrate the validity of the online method. The detection system combines conventional gamma-ray spectrometry with fast list mode data acquisition in the Matlab software package. Elution experiments were performed at different flow rates of hydrochloric acid, separating 211Bi (t 1/2 = 2.14 min) free from its parent nuclides. In addition, to prove the versatility of the setup, experiments at different hydrochloric acid concentrations were performed resulting in the elution of pure 211Pb (t 1/2 = 36.1 min) and 223Ra (t 1/2 = 11.43 d), respectively.

Arsenic-72, 77 as a matched pair radiopharmaceutical for imaging and radiotherapy

Radiopharmaceuticals deliver radionuclides to specific target sites via the bifunctional chelate approach, where the radionuclides are chelated with a ligand and linked to a targeting biomolecule. They can be categorized as imaging or therapeutic agents based on the physical properties of the radionuclides. Matched pair radionuclides have advantages because of identical chemistry of the imaging and therapy counterparts and true matched pair radionuclides are rare (e.g., 64,67Cu, 44,47Sc, 135,131I). Radioimmunoimaging and therapy commonly use antibodies (or antibody fragments) as targeting biomolecules, and may take a few days to accumulate in tumor cells. Thus they require radionuclides with longer half-lives. Arsenic-72 ([beta]+, 26 hour half-life) and 77As ([beta]- emitter, 38.8 hour half-life) have suitable physical properties as a true matched pair for radioimaging and therapy. This dissertation focuses on the development of 72,77As matched pair for potential PET imaging and radiotherapy. ... The production and separation of no carrier added (nca) 72,77As will be discussed in Chapter 2. No carrier added 77As separation was improved based on the reported method by decreasing the operation time and increasing capacity based on reported method.[1] The parameters for a 72Se/72As generator were evaluated and nca 72Se was produced via the 70Ge([alpha], 2n)72Se nuclear reaction, separated and loaded onto a generator column. Further evaluations are underway. Radiochemistry of nca 72,77As will be discussed in Chapters 3 and 4 since two chelating approaches were evaluated. The aryl dithiol approach incorporates an aryl ring to nca radioarsenic and complexes it with dithiol ligands. After various modifications and optimizations, radiolabeling nca 72,77As affording dithioarylarsines were accomplished in high yields. The trithiol approach complexes nca 72,77As with a trithiol chelate. Its in vivo stability was evaluated by conjugating the trithiol chelate to a Bombesin receptor targeting peptide and investigating its biodistribution in normal mice. An improved trithiol chelate was proposed and synthesized based on the high in vivo stability but poor targeting efficacy of the initial trithiol complex.