Postexposure Protection and Decontamination

To protect the warfighter from current and potential future super-toxins, the threats should be described with as much technical precision as possible. Future threats may include more sophisticated CB weapons but also entities such as prions (as weaponized proteins) or toxic nanoparticles. 

12 Cartoon illustrating desired properties for future nanomaterial for decontamination  

These results, coupled with the recent findings in solgel, aerogel, and modified aerogel syntheses of porous metal oxides, as well as the literature of zeolites, pillared clays, and mesoporous silicas, suggest that future investigations will lead to precise control of pore sizes, pore size distribution, and chemical functionality of the pore walls. 

The pores of friendly nanomaterials could be used to store strong adds, even super acids, in some cases. Likewise, weak bases or strong bases could be stored for use as needed in killing or destroying advanced enemy toxins. In addition, the nanomaterial itself could be produced with acidic sites (metal ions and/or certain proton donors) built into the pore walls and crystal faces. For example, titanium or zirconium ions can serve as acid sites if adjacent to sulfate species. Likewise, the proton forms of some transition-metal oxygen-anion clusters (polyoxometalates or POMs ), like some metal oxides, are effective superacids in commercial processes. Polyoxometalates could be physically held within the pores or could be grafted onto the pore walls or onto the outer nanocrystal faces. Basic sites can also be built into the nanostructure, such as oxide anions near a metal cation vacancy. There are many other possibilities, such as sulfide substitution for oxide anions on the surface of the nanocrystals. 

Storage of oxidizers in the pores should also be possible. The oxidizers could be incorporated as structural components of the material, physically entrapped, or immobilization by electrostatic and/or covalent bonds. POMs, in combination with friendly nanomaterials, present special promise, because POMs are versatile, reversible, and tunable oxidants and that, upon reduction by toxics, can be regenerated by air oxidation. Thus, nanomaterials will be accessible that catalyze the oxidative degradation of a range of threats and simultaneously exhibit complementary decontamination activities and other capabilities. 

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