Functional Sorbents for Selective Capture of Plutonium, Americium, Uranium, and Thorium in Blood

Abstract

Self-assembled monolayer on mesoporous supports (SAMMS™) are hybrid materials created from attachment of organic moieties onto very high surface area mesoporous silica. SAMMS with surface chemistries including three isomers of hydroxypyridinone, diphosphonic acid, acetamide phosphonic acid, glycinyl urea, and diethylenetriamine pentaacetate (DTPA) analog were evaluated for chelation of actinides ( 239 Pu, 241 Am, uranium, thorium) from blood. Direct blood decorporation using sorbents does not have toxicity or renal challenges associated with traditional chelation therapy and may have potential applications for critical exposure cases, reduction of nonspecific dose during actinide radiotherapy, and for sorbent hemoperfusion in renal insufficient patients, whose kidney clear radionuclides at very slow rate. Sorption affinity (K d ), sorption rate, selectivity, and stability of SAMMS were measured in batch contact experiments. An isomer of hydroxypyridinone (3,4-HOPO) on SAMMS demonstrated the highest affinity for all four actinides from blood and plasma and greatly outperformed the DTPA analog on SAMMS and commercial resins. In batch contact, a fifty percent reduction of actinides in blood was achieved within minutes, and there was no evidence of protein fouling or material leaching in blood after 24 hr. The engineered form of SAMMS (bead format) was further evaluated in a 100-fold scaleddown hemoperfusion device and showed no blood clotting after 2 hr. A 0.2 g quantity of SAMMS could reduce 50 wt.% of 100 ppb uranium in 50 mL of plasma in 18 min and that of 500 dpm mL −1 in 24 min. 3,4-HOPO-SAMMS has a long shelf-life in air and at room temperature for at least 8 years, indicating its feasibility for stockpiling in preparedness for an emergency. The excellent efficacy and stability of SAMMS materials in complex biological matrices suggest that SAMMS can also be used as orally administered drugs and for wound decontamination. By changing the organic groups of SAMMS, they can be used not only for actinides but also for other radionuclides. By using the mixture of these SAMMS materials, broad spectrum decorporation of radionuclides is very feasible.

Selective capture of radionuclides (U, Pu, Th, Am and Co) using functional nanoporous sorbents

“…Figure 8 shows that most of the sorbents studied demonstrated good stability across pH 2-7.5, typically experiencing less than 2% Si leaching from the sorbents. Most notable was the 3,4-HOPO-SAMMS, which displayed well below 0.4% Si leaching across the entire pH range [13]. Although Si leaching of IDAA-SAMMS was <1% at pH 3.9 and above, the leaching was increased to 2.6% at pH 2.2 and 16% at pH 0.11.…”

“…The posture of the functional organosilane leaves the active ligand at the monolayer interface, where it is able to chelate the metal ion of interest [6]. If these organosilanes contain suitable ligands at their terminus, then they can make excellent sorbent materials for heavy metals [7][8][9], transition metals [10,11], lanthanides and actinides [12][13][14][15][16][17], oxometallic anions [18,19], and cesium and thallium [20,21]. Multiple metal-ligand interactions are possible due to the close proximity of these ligands on the mesoporous silica, creating attractive strategy for capturing the actinide cations, with their high coordination numbers.…”

Investigation of Magnetic Nanoparticles for the Rapid Extraction and Assay of Alpha-Emitting Radionuclides From Urine: Demonstration of a Novel Radiobioassay Method

“…Low cost and no-to-low toxicity would also benefit sorbent properties, but these are not essential, given that very small quantities (i.e., milligrams per assay) are going to be used in a controlled fashion. This is a demanding list of criteria, but a range of advanced sorbent materials are in development and are being evaluated in the subject labs, with some work published on magnetic nanoparticles (Rutledge et al 2010;Warner et al 2008Warner et al , 2010Yantasee et al 2007) and Self-Assembled Monolayers on Mesoporous Supports (SAMMS) (Addleman et al 2005;Busche et al 2009;Fryxell et al 2007;Johnson et al 2011;Timchalk et al 2010;Yantasee et al 2010). Discussion and description of these novel materials are outside the scope of this work and will be presented elsewhere subsequently.…”

Appraisal of biochemical classes of radioprotectors: evidence, current status and guidelines for future development

“…The transdermal delivery of synthetic DTPA di-and tri-ethyl ester has been reported to enhance decorporation in a dosedependent manner (Zhang et al 2013). Different silicabased materials have also been tested to capture various radionuclides of Plutonium, Americium, Uranium, and Thorium (Yantasee et al 2010). The mechanisms of radioprotection in case of radionuclide's toxicity might be chelating, inhibiting uptake by changing chemical state, diluting, and flooding of active compounds (Dominguez-Gadea and Cerezo 2011).…”