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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

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journal contribution
posted on 21.08.2013, 00:00 by Rubel Chakravarty, Ramu Ram, Ratikant Mishra, Debasis Sen, S. Mazumder, M. R. A. Pillai, Ashutosh Dash
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.