Recent progress in the chemical attribution of chemical warfare agents and highly toxic organophosphorus pesticides

Optimizing the Schoenemann Reaction for Colorimetric Assays of VX and GD

The analysis of nerve agents is the focus of chemical warfare agent determination because of their extreme toxicity. A classical chemical colorimetric method, namely, the Schoenemann reaction, has been developed to detect G agents; however, it has not been utilized for VX analysis mainly because of its low peroxyhydrolysis rate. In this study, based on the mechanism of the Schoenemann reaction, a novel rapid quantitative determination method for VX was developed by optimizing the reaction conditions, such as concentrations of peroxide and the indicator, temperature, and reaction time. Using 2 ml 0.5 wt% sodium perborate as the peroxide source, 1 ml 0.1 wt% benzidine hydrochloride as the indicator, and 1 ml acetone as the co-solvent, VX and GD in ethanol or water solutions could be quantitatively analyzed within 15 min at 60°C. Further experiments based on ³¹P NMR spectroscopy confirmed the existence of a peroxyphosphate intermediate during the GD assay. This quantitative colorimetry system for VX and GD analysis can be developed as a portable device for the water samples in fieldwork applications.

Oxime Therapy for Brain AChE Reactivation and Neuroprotection after Organophosphate Poisoning

One of the main problems in the treatment of poisoning with organophosphorus (OPs) inhibitors of acetylcholinesterase (AChE) is low ability of existing reactivators of AChE that are used as antidotes to cross the blood-brain barrier (BBB). In this work, modified cationic liposomes were developed that can penetrate through the BBB and deliver the reactivator of AChE pralidoxime chloride (2-PAM) into the brain. Liposomes were obtained on the basis of phosphatidylcholine and imidazolium surfactants. To obtain the composition optimized in terms of charge, stability, and toxicity, the molar ratio of surfactant/lipid was varied. For the systems, physicochemical parameters, release profiles of the substrates (rhodamine B, 2-PAM), hemolytic activity and ability to cause hemagglutination were evaluated. Screening of liposome penetration through the BBB, analysis of 2-PAM pharmacokinetics, and in vivo AChE reactivation showed that modified liposomes readily pass into the brain and reactivate brain AChE in rats poisoned with paraoxon (POX) by 25%. For the first time, an assessment was made of the ability of imidazolium liposomes loaded with 2-PAM to reduce the death of neurons in the brains of mice. It was shown that intravenous administration of liposomal 2-PAM can significantly reduce POX-induced neuronal death in the hippocampus.

Array-based chemical warfare agent discrimination via organophosphorus-H2O2 reaction-regulated chemiluminescence

It has been a challenge to achieve rapid, simple, and effective discrimination of organophosphorus nerve agents (typical chemical warfare agents) due to the similar chemical properties of the targets such as sarin, soman, cyclosarin and VX. In this study, we propose a chemiluminescence sensor array that can effectively discriminate organophosphorus nerve agents by organophosphorus-H₂O₂ reaction, which produces peroxyphosphonate intermediate and regulates the chemiluminescence intensity. A simple chemiluminescence sensor array based on different chemiluminescence characteristics of the four organophosphorus nerve agents in the luminol–H₂O₂ system and layered double hydroxide–luminol–H₂O₂ system has been constructed. Four agents can be well distinguished at a concentration of 1.0 mg L⁻¹ when linear discriminant analyses and hierarchical cluster analyses are smartly combined. The high accuracy (100%) evaluation of 20 blind samples demonstrates the practicability of this proposed chemiluminescence sensor array.

A chemical warfare agent sensor array based on organophosphorus-H₂O₂ reaction-regulated chemiluminescence is proposed.