Mesoporous
Alumina (MA) Based Double Column Approach for Development of a Clinical
Scale <sup>99</sup>Mo/<sup>99m</sup>Tc Generator Using (n,γ)<sup>99</sup>Mo: An Enticing Application of Nanomaterial
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Abstract
This
paper describes the utility of mesoporous alumina (MA), a high capacity
nanomaterial based sorbent, for the development of a clinical grade <sup>99</sup>Mo/<sup>99m</sup>Tc generator using (n,γ)<sup>99</sup>Mo. 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 m<sup>2</sup> g<sup>–1</sup>. 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 <sup>99</sup>Mo and <sup>99m</sup>Tc ions,
Mo sorption capacity under static and dynamic conditions, <sup>99</sup>Mo adsorption pattern and <sup>99m</sup>Tc elution pattern were determined
to assess its effectiveness in the preparation of <sup>99</sup>Mo/<sup>99m</sup>Tc generator. The measured distribution ratio values indicate
that <sup>99</sup>Mo is both strongly and selectively retained by
MA at acidic pH and <sup>99m</sup>Tc 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 <sup>99</sup>Mo loaded columns were connected in series. In this method <sup>99m</sup>Tc eluted from the first column was fed to the second column
to achieve higher radioactive concentration (RAC) as well as purity
of <sup>99m</sup>Tc. A 26 GBq (700 mCi) <sup>99</sup>Mo/<sup>99m</sup>Tc generator was developed using (n,γ)<sup>99</sup>Mo having
specific activity of ∼18.5 GBq (500 mCi)/g of Mo. The <sup>99m</sup>Tc eluted from the generator possessed high radionuclidic,
radiochemical, and chemical purity and was amenable for the preparation
of <sup>99m</sup>Tc-labeled radiopharmaceuticals. The technology can
be adapted by those countries having research reactors with flux >1
× 10<sup>14</sup> n·cm<sup>–2</sup>·s<sup>–1</sup> to produce <sup>99</sup>Mo by (n,γ) route. The capacity of
the generator can be scaled up to 260 GBq (7 Ci) using (n,γ)<sup>99</sup>Mo produced from a reactor with flux >1 × 10<sup>15</sup> n·cm<sup>–2</sup>·s<sup>–1</sup>