Electrochemical Separation: Promises, Opportunities, and Challenges To Develop Next-Generation Radionuclide Generators To Meet Clinical Demands

This review provides a comprehensive summary of the role of the electrochemical separation process to develop next-generation radionuclide generators to meet future research and clinical demands. This innovative technology paradigm, straddling the disciplines of electrochemistry and separation science, is poised to serve as a springboard to spur new breakthroughs and bring evolutionary progress in radionuclide generator technology. Without doubt, the major impetus for the advancement in radionuclide generator technology stems from nuclear medicine requirements, as a means of obtaining short-lived radionuclides on demand for the formulation of a gamut of diagnostic and therapeutic radiopharmaceuticals. The tremendous prospects associated with the use of electrochemical radionuclide generators in nuclear medicine dictate that a holistic consideration should given to all governing factors that determine their success. The purpose of this paper is to present a concise and comprehensive review of the latest research and development activities in the utility of electrochemical separation process in development of radionuclide generators that have already established footholds of acceptance in nuclear medicine and are expected to change the future landscape of radionuclide generator technology. This review provides a summary of the principle, factors that govern the electrochemical separation, desirable characteristics of the generator systems developed with typical examples, critical assessment of recent developments, contemporary status, key challenges, and apertures to the near future

Mesoporous Alumina (MA) Based Double Column Approach for Development of a Clinical Scale ⁹⁹Mo/^99mTc Generator Using (n,γ)⁹⁹Mo: An Enticing Application of Nanomaterial

This paper describes the utility of mesoporous alumina (MA), a high capacity nanomaterial based sorbent, for the development of a clinical grade ⁹⁹Mo/^99mTc generator using (n,γ)⁹⁹Mo. Synthesis of MA was performed using a glucose template in an aqueous system. Structural characterization of the nanosorbent was carried out by analytical techniques such as X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), scanning electron miscroscopy (SEM), transmission electron microscopy (TEM), thermogravimetry-differential thermal analysis (TG-DTA), Fourier transform infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller (BET) surface area analysis. The material synthesized was mesoporous and nanocrystalline, with average crystallite size of 2–3 nm with a large surface area of 230 ± 10 m² g^–1. In order to evaluate the surface charge of MA in aqueous solution, the zeta potential was determined at different pH environments. Adsorption characteristics of the sorbent such as time course of the adsorption, distribution ratios of ⁹⁹Mo and ^99mTc ions, Mo sorption capacity under static and dynamic conditions, ⁹⁹Mo adsorption pattern and ^99mTc elution pattern were determined to assess its effectiveness in the preparation of ⁹⁹Mo/^99mTc generator. The measured distribution ratio values indicate that ⁹⁹Mo is both strongly and selectively retained by MA at acidic pH and ^99mTc could be readily eluted from it, using 0.9% NaCl solution. The static sorption capacity and practical sorption capacity under dynamic conditions of MA was determined to be 225 ± 20 and 168 ± 12 mg Mo per gram of sorbent, respectively. With a view to realize the scope of developing clinical scale generator, a novel tandem column generator concept was used in which two ⁹⁹Mo loaded columns were connected in series. In this method ^99mTc eluted from the first column was fed to the second column to achieve higher radioactive concentration (RAC) as well as purity of ^99mTc. A 26 GBq (700 mCi) ⁹⁹Mo/^99mTc generator was developed using (n,γ)⁹⁹Mo having specific activity of ∼18.5 GBq (500 mCi)/g of Mo. The ^99mTc eluted from the generator possessed high radionuclidic, radiochemical, and chemical purity and was amenable for the preparation of ^99mTc-labeled radiopharmaceuticals. The technology can be adapted by those countries having research reactors with flux >1 × 10¹⁴ n·cm^–2·s^–1 to produce ⁹⁹Mo by (n,γ) route. The capacity of the generator can be scaled up to 260 GBq (7 Ci) using (n,γ)⁹⁹Mo produced from a reactor with flux >1 × 10¹⁵ n·cm^–2·s^–1