Self-decontaminating biocatalyst against nerve gases

Chemical warfare agents (CWA) are one of the most brutal weapons  created by mankind [1]. CWAs are inexpensive and are relatively easy to produce, even by small terrorist groups, to achieve mass casualties with small quantities. These compounds are characterized by high toxicity, imperceptibility to senses, rapidity of action after dissemination and persistency.

A group of CWAs is nerve agents that disrupt the chemical communications through the nervous system. One mechanism of disruption, utilized also by the organophophates, is blocking the acetylcholinesterase, an enzyme that normally breaks down and stops the activity of  acetylcholine, a neurotransmitter. Poisoning by these nerve agents leads to an accumulation of acetylcholine at the nerve action producing a perpetual excited state in the nerve (e.g. constant muscle contraction). The eventual exhaustion of muscles leads to respiratory failure and death. Such agents have been used even in the recent wars [2].

To fabricate a self-decontaminating agent of fast action and high specificity against organophosphates organophosphorus hydrolase, a non-toxic enzyme for hydrolyzing nerve agents, was immobilized on poly-β-cyclodextrin obrtained by crosslinking BCD with hexamethyl diisocyanate by physical entrappment [3]. The CD polymer serves not only as a support but also as a highly sorptive specific binding and detoxifying agent. Methyl paraoxon (MPO, an active metabolite of parathion, organophosphorus pesticide) was used to simulate soman. The novel self-decontaminating system was extremely stable and showed high sorption and fast degradation of MPO.

1. Ganesan, S. K. Raza, and R. Vijayaraghavan Chemical warfare agents. J. Pharm. Bioallied Sci. 2010; 2(3): 166–178. doi: [10.4103/0975-7406.68498]
2. https://en.wikipedia.org/wiki/List_of_chemical_warfare_agents
3. Moon, Y., Jafry, A.T., Kang, S.B. et al. Organophosphorus hydrolase-poly-β-cyclodextrin as a stable self-decontaminating bio-catalytic material for sorption and degradation of organophosphate pesticide. J. Hazard. Mater. 2019; 365, 361-269