Nerve Agent Sarin Research Articles

Computational Analysis of Sarin, Soman, and Their Water Mixtures in NU-1000: Interaction Mechanisms, Distribution Patterns, and Pairing Effects.

Due to their extraordinary structural stability under humid conditions, zirconium-based metal-organic frameworks (Zr-MOFs) have been widely investigated for the hydrolytic degradation of nerve agents. That said, mechanisms of hydrolysis in the solid state and the participation of environmental water are not well understood. This work utilizes computational techniques to evaluate the behavior of water and two organophosphorus nerve agents (sarin and soman) in NU-1000, a Zr-MOF with the characteristic attributes for hydrolytic efficiency under humid conditions. Density functional theory (DFT) calculations reveal that soman binds more favorably to NU-1000 active sites than sarin, resulting in different preferential locations of each nerve agent within the framework. The strength of nerve agent binding is also found to vary depending on the site environment, with more favorable binding of both nerve agents occurring in the c-pores of NU-1000 than in the mesopores. Molecular dynamics (MD) simulation results further illustrate that free water molecules in NU-1000 prioritize interactions with nerve agents. Given the variation in their affinity for active site interactions, the introduction of different nerve agents to the framework results in substantial differences in water distribution and behavior. The results give insight into potential variances in the functionality of NU-1000 toward the hydrolysis of each nerve agent. More importantly, they emphasize the significance of considering the role of environmental water in hydrolysis and the possibility of diverse reaction variables based on the type of nerve agent and the properties of the MOF.

Exploring the reaction mechanistic pathway for the sensing of G-Series nerve agent with Kemp's triacid derivative: A computational study

Kemp's triacid derivative have been reported as a candidate for sensing of nerve agents employing the photoinduced electron transfer (PET) processes. The sensor probe molecules were prepared with primary alcohol in very close proximity to a tertiary amine to acylate the alcohol with rapid intramolecular N-alkylation to produce quaternary ammonium salt. The reaction pathways for the formation of quaternary ammonium salt and isomethyl propyl phosphonate remain unexplored. In this report, the mechanistic pathways of G-series nerve agents sarin and its simulant diethylcholorophosphate (DCP) with Kemp's triacid derivatives has been explored computationally. The calculations performed with B3LYP-D3/6-311+G(d,p) level of theory in DCM solvent revealed that the reaction proceeds via intermolecular and intramolecular SN2 pathways. The probe molecule is sterically hindered, therefore, the frontside and backside SN2 reaction pathways have been examined. The computed results suggest that the first intermolecular SN2 reaction of Kemp's triacid derivatives (I &II) with sarin for the backside attack is energetically favored compared to the frontside attack and the following intramolecular SN2 reaction is a barrierless process. The calculations performed with simulant diethylcholorophosphate (DCP) and Kemp's triacid derivatives (I &II) show that the reactions are energetically more facile compared to the nerve agent sarin molecule. The Distortion-Interaction model and ΔNBOSteric analysis showed that the back side is energetically favored over the front side attack in such SN2 reactions. The designed Kemp's triacid derivative (II) with phosphorus center for sensing sarin and (DCP) suggests that the size of the hetero centers are important to facilitate the reaction in the probe molecule.

Precise intramolecular-charge-transfer property modulation of D-A-type fluorescent probes for bifunctional detection of phosgene and nerve agent

Chemical warfare agents such as phosgene and nerve agents pose severe threats to national defense and public safety, yet the development of bifunctional ratiometric fluorescent probes for them is still in its infancy. Aimed at this target, an intramolecular-charge-transfer (ICT) modulation strategy via incorporating donors with varied electron-donating ability, is put forward. Based on it, a series of donor(D)-acceptor(A)-type fluorescent probes are designed and synthesized. It is found that as the ICT strength of probes weakens, a ratiometric fluorescent probe with bi-analyte identification of phosgene and diethylchlorophosphate (DCP, the mimic of nerve agent sarin) is gained. Upon exposure to phosgene and DCP, 3-(benzo[d]thiazol-2-yl)-4′-(1,2,2-triphenylvinyl)-[1,1′-biphenyl]-4-amine (BTTPE), with the weakest ICT property, presents discriminative bathochromic shifts (Δλem = 58 nm for phosgene and Δλem = 152 nm for DCP) and favorable limits of detection (LODs in solution: 6.42 nM for phosgene; 6.80 µM for DCP). Besides, the prepared BTTPE-based paper test strips combined with a smartphone can detect phosgene vapor under the colorimetric-fluorescent dual-mode sensing and enable the visual recognition and quantitative detection of DCP vapor, with LODs in the vapor phase of 0.29 ppm for phosgene and 0.49 ppm for DCP. Hereby, this work not only provides the ICT modulation strategy for the first time to realize the ratiometric fluorescence detection of phosgene/DCP but also opens up a new avenue for tailoring multifunctional fluorescent probes.

Development of dispersive solid phase extraction method for the preconcentration of parathion ethyl as a simulant of nerve agent sarin from soil, plant and water samples prior to GC-MS determination.

In the presented study, an efficient and fast analytical method was developed for the determination of parathion ethyl as sarin simulant by gas chromatography-mass spectrometry (GC-MS). Dispersive solid phase extraction (DSPE) was performed to concentrate parathion ethyl from soil, plant and water samples. Reduced graphene oxide-iron (II, III) oxide (rGO-Fe3O4) nanocomposite was used as an adsorbent to collect the target analyte from the aqueous sample solutions. After the optimization of extraction/preconcentration parameters, optimum conditions for adsorbent amount, eluent type, mixing type/period, eluent volume and initial sample volume were determined as 15mg, acetonitrile, vortex/30s, 100 µL and 10mL, respectively. Under the optimum conditions, analytical performance of the developed DSPE-GC-MS method was evaluated in terms of limit of detection (LOD), limit of quantitation (LOQ) and dynamic range. Dynamic range, LOD and LOQ values were figured out to be 0.94-235.15µg/kg, 0.41µg/kg and 1.36µg/kg (mass based), respectively. Satisfactory percent recovery results (90.3-125% for soil, 93.5-108.7% for plant, 88.5-112.9% for tap water) were achieved for soil, plant and tap water samples which proved the accuracy and applicability of the developed method. It is predicted that the DSPE-GC-MS method can be accurately used for the detection of sarin in soil, plant and water samples taken from war territories.

Construction of logic gate computation for the assay of the nerve agent sarin based on an AChE-based dual-channel sensing system.

Nerve agents have posed a huge threat to national and human security, and their sensitive detection is crucial. Herein, based on the oxidation of Ce4+ and the aggregation-induced emission (AIE) of glutathione-protected gold nanoclusters (GSH-Au NCs), a cascade reaction was designed to prepare oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB) and GSH-Au NCs crosslinked by Ce3+ (Ce3+-GSH-Au NCs). oxTMB had a broad UV-visible absorption range (500-700 nm) and was capable of quenching the fluorescence of Ce3+-GSH-Au NCs at 590 nm through the internal filtration effect (IFE). Thiocholine (TCh), the hydrolysis product of acetylthiocholine chloride (ATCl) catalyzed by acetylcholinesterase (AChE), reduced oxTMB completely, resulting in a decrease in the absorption of oxTMB and the recovery of IFE-quenched fluorescence of Ce3+-GSH-Au NCs. Nerve agent sarin (GB) hindered the production of TCh and the reduction of oxTMB by inhibiting the AChE activity, leading to the fluorescence of Ce3+-GSH-Au NCs being quenched again. The dual-output sensing system (AChE + ATCl + oxTMB + Ce3+-GSH-Au NCs) exhibited a low limit of detection to GB (2.46 nM for colorimetry and 1.18 nM for fluorimetry) and excellent selectivity toward common interferences being unable to inhibit AChE. Moreover, the intelligent logic gate constructed based on the sensing system showed promising applications in the field of smart sensing of nerve agents.

Cholesterol Oxime Olesoxime Assessed as a Potential Ligand of Human Cholinesterases.

Olesoxime, a cholesterol derivative with an oxime group, possesses the ability to cross the blood-brain barrier, and has demonstrated excellent safety and tolerability properties in clinical research. These characteristics indicate it may serve as a centrally active ligand of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), whose disruption of activity with organophosphate compounds (OP) leads to uncontrolled excitation and potentially life-threatening symptoms. To evaluate olesoxime as a binding ligand and reactivator of human AChE and BChE, we conducted in vitro kinetic studies with the active metabolite of insecticide parathion, paraoxon, and the warfare nerve agents sarin, cyclosarin, tabun, and VX. Our results showed that both enzymes possessed a binding affinity for olesoxime in the mid-micromolar range, higher than the antidotes in use (i.e., 2-PAM, HI-6, etc.). While olesoxime showed a weak ability to reactivate AChE, cyclosarin-inhibited BChE was reactivated with an overall reactivation rate constant comparable to that of standard oxime HI-6. Moreover, in combination with the oxime 2-PAM, the reactivation maximum increased by 10-30% for cyclosarin- and sarin-inhibited BChE. Molecular modeling revealed productive interactions between olesoxime and BChE, highlighting olesoxime as a potentially BChE-targeted therapy. Moreover, it might be added to OP poisoning treatment to increase the efficacy of BChE reactivation, and its cholesterol scaffold could provide a basis for the development of novel oxime antidotes.

Understanding the Decomposition of Dimethyl Methyl Phosphonate on Metal-Modified TiO2(110) Surfaces Using Ensembles of Product Configurations.

The decomposition of dimethyl methyl phosphonate (DMMP), a simulant for the nerve agent sarin, was investigated on Cu4/TiO2(110) and K/Cu4/TiO2(110) surfaces using a combination of near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) and density functional theory calculations (DFT). Mass-selected Cu4 clusters and potassium (K) atoms were deposited onto TiO2(110) as a metal catalyst and alkali promoter to improve the reactivity and recyclability of the TiO2 surface after exposure to DMMP. Surface reaction products resulting from decomposition of DMMP were probed by NAP-XPS measurements of phosphorus (P) 2p and carbon 1s core-level spectra. The Cu4/TiO2(110) surface is found to be very active for DMMP decomposition with highly reduced P-species observed even at room temperature (RT). The codeposition of K atoms and Cu4 clusters further improves the reactivity with no intact DMMP detectable. Temperature-dependent measurements show that the presence of K atoms promotes the removal of residual P-species at temperatures > 600 K. Detailed DFT calculations were performed to determine the surface structures and energetically accessible pathways for DMMP decomposition on Cu4/TiO2(110) and K/Cu4/TiO2(110) surfaces. The calculations show that DMMP and P-containing reaction products preferentially bind to the TiO2 surface, while the molecular fragments, i.e., methoxy and methyl, bind to both the Cu4 clusters and TiO2. The Cu4 clusters make the P-O, O-C, and P-C bond cleavages of DMMP markedly more exothermic. The Cu4 clusters are highly fluxional with atomic structures that depend on the configuration of fragments bound to them. Finally, the manifold of P 2p chemical shifts calculated for a large number of energetically favorable configurations of decomposition products is in good agreement with the observed XPS spectra and provides an alternative way of interpreting incompletely resolved core-level spectra using an ensemble of observed structures.

Detoxification of toxic nerve agent sarin utilizing cupric oxide functionalized activated carbon fabric composite for advanced NBC Protective Clothing

ABSTRACT This investigation delves into the development of cupric oxide functionalized activated carbon fabrics (ACF@CuO) as a filter material for self-decontaminating protective clothing designed to counter chemical warfare agents (CWAs). Three variants of samples were developed by controlling functionalization levels (7.5%, 13.0%, 16.0% w/w) through optimized precursor concentrations, integrating CuO particles onto ACF surfaces. Comprehensive analysis using techniques like FTIR, BET surface area, SEM, EDX, STEM, XRD, TGA, and XPS explored the material’s properties. The studies concentrated on evaluating the performance through kinetic studies of self-detoxification of CWA Sarin (GB) using developed ACF@CuO materials analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). ACF@CuO with 16% w/w functionalization exhibited superior self-decontamination against GB, achieving 92.87% efficiency within 18 hours, in contrast to 26.55% for ACF alone. Additionally, materials were tested for tensile strength, air-permeability, and Sulfur Mustard breakthrough time (HDBTT) as per IS 17377:2020 standard. The material with 13% w/w functionalization emerged as the recommended filter layer for CWA protective clothing designed for defense and civilian safety applications. The significant improvements in the self-decontamination efficiency of the material were attributed to the synergistic effects of ACF’s adsorption capabilities combined with the decontamination properties of CuO rod-shaped crystals embedded in the surface of ACF.

Adsorption of DMMP and water vapor on granular activated carbon: An experimental and molecular simulation study

The adsorption behavior of Dimethyl methylphosphonate (DMMP), as a simulant of sarin nerve agent, especially in the presence of water vapor, is crucial for the design of efficient chemical protection equipment. Experimental results reveal DMMP's adsorption isotherm on granular activated carbon (GAC) as a typical type I. The adsorption process was a spontaneous and exothermic physical adsorption process, and the adsorption mechanism was in accordance with Dubinin's micropore filling theory. In the relative humidity range of 10 % ∼ 90 %, the isotherm remained I-type, and the effect of water vapor on the equilibrium adsorption capacity and apparent adsorption rate was weak. Molecular simulations also show that DMMP adsorption on GAC follows a type I isotherm, primarily driven by van der Waals forces of physical adsorption. The adsorption potential energy between DMMP and GAC surpasses that of water molecules, resulting in negligible effects from water vapor on DMMP adsorption equilibrium. Meanwhile, water molecules had minimal effect on the diffusion of DMMP molecules in the GAC pores, and the positional distribution of DMMP multilayer adsorption was consistent under different relative humidity conditions. Furthermore, the presence of polar functional groups such as hydroxyl groups significantly affects the adsorption equilibrium of DMMP.

Efficacy of a combined anti-seizure treatment against cholinergic established status epilepticus following a sarin nerve agent insult in rats

The development of refractory status epilepticus (SE) following sarin intoxication presents a therapeutic challenge. Here, we evaluated the efficacy of delayed combined double or triple treatment in reducing abnormal epileptiform seizure activity (ESA) and the ensuing long-term neuronal insult. SE was induced in rats by exposure to 1.2 LD50 sarin followed by treatment with atropine and TMB4 (TA) 1 min later. Double treatment with ketamine and midazolam or triple treatment with ketamine, midazolam and levetiracetam was administered 30 min post-exposure, and the results were compared to those of single treatment with midazolam alone or triple treatment with ketamine, midazolam, and valproate, which was previously shown to ameliorate this neurological insult. Toxicity and electrocorticogram activity were monitored during the first week, and behavioral evaluations were performed 2 weeks post-exposure, followed by biochemical and immunohistopathological analyses. Both double and triple treatment reduced mortality and enhanced weight recovery compared to TA-only treatment. Triple treatment and, to a lesser extent, double treatment significantly ameliorated the ESA duration. Compared to the TA-only or the TA+ midazolam treatment, both double and triple treatment reduced the sarin-induced increase in the neuroinflammatory marker PGE2 and the brain damage marker TSPO and decreased gliosis, astrocytosis and neuronal damage. Finally, both double and triple treatment prevented a change in behavior, as measured in the open field test. No significant difference was observed between the efficacies of the two triple treatments, and both triple combinations completely prevented brain injury (no differences from the naïve rats). Delayed double and, to a greater extent, triple treatment may serve as an efficacious delayed therapy, preventing brain insult propagation following sarin-induced refractory SE.

Decontamination coupled with dynamic adsorption of sulfur mustard (CEES) and nerve agent-sarin simulants (DMMP) on synthesized zeolite-alpha with its metal oxide composites

Chemical warfare agents (CWAs) are the most feared toxic chemicals intended to debilitate the general human population and regional civilians. Therefore, prompt and urgent decontamination is needed to protect millions of lives and the associated hazardous implications. In this present study, our main goal is to evaluate the performance of Zeolite-Alpha and its various metal oxide composites as novel adsorbents for the decontamination of CWA simulants, 2-chloroethyl ethyl sulfide (CEES), and dimethyl methyl phosphonate (DMMP). Synthesized Zeolite-Alpha and their composites were characterized by XRD, FTIR, SEM-EDS, and BET analysis techniques. The CWA simulants’ decontamination (adsorption and desorption) was monitored using GC-FID and GC-MS analysis techniques. A possible reaction mechanism toward the adsorption and destruction of CWA simulants, CEES, and DMMP was also proposed. Nanocrystalline Zeolite-Alpha and its metal oxide composites are powerful adsorbents, and they showed more significant decontamination potential toward the above CWA simulants. The Cr-O-Alpha and Ag-O-Alpha showed promising results (93–98% decontamination) among all other synthesized metal oxide composites.

Graphene based Mo6 cluster hybrid for detecting simulant nerve agent DMMP

Nerve agents are highly toxic chemical compounds that pose significant threats to human health and safety. Detecting and identifying these agents quickly is crucial for preventing their exposure and providing timely treatment. This study proposes the use of nanohybrids comprising crystalline octahedral molybdenum iodide cluster material supported on graphene (Mo6@Graphene) as a novel sensing material for the detection of dimethyl methylphosphonate (DMMP), a simulant of sarin nerve agent. The electrical sensing performance towards different concentrations of DMMP and at room temperature demonstrated fast and sensitive responses to DMMP, with almost full recovery of the sensor baseline in a few minutes. The calibration curve obtained showed a linear relationship between the sensor response and DMMP concentration, enabling the estimation of the limit of detection (LOD) of 270 ppb. The robustness of the Mo6@Graphene nanomaterial towards DMMP was assessed using various techniques, including Raman spectroscopy, X-ray diffraction and photoelectron spectroscopy. The binding energies (BEs) between DMMP and the supported Mo6 clusters determined by DFT calculations revealed H-bonding interactions involved in the sensing mechanism. The excellent sensing performance of the Mo6@Graphene film, combined with its low power consumption and high stability, makes it a promising candidate for the detection of nerve agents and their simulants.

Molecular docking and toxicity studies of nerve agents against acetylcholinesterase (AChE)

Acetylcholinesterase (AChE) is a cholinergic enzyme that plays an essential role in the autonomic nervous system. This enzyme is often the target of many nerve agents. When this enzyme is inhibited, its function to hydrolyze acetylcholine is stopped, accumulating the acetylcholine in the tissue and causing prolonged stimulation. Some of the significant nerve agents include sarin (GB), soman (GD), tabun (GA), and venomous agent (VX). In order to determine which compound is the most stable and has the best affinity, the nerve agent venomous agent (VX), sarin (GB), soman (GD), and tabun (GA) are docked to the acetylcholinesterase (AChE) enzyme. After that, toxicity tests will be performed on 17 targets for the compound that was chosen. Autodock Vina 1.2.0 is the software used for the docking procedure. should use the Pymol program version 2.5.4 for analysis and the Ligplot software version 2.2 for visualization of the docking findings. The 'Tox Prediction’ algorithm from Insilico was used to determine the toxicity of various substances. Based on the results of molecular docking, the free binding energy of Donepezil, sarin (GB), soman (GD), tabun (GA), and venomous agent (VX) in kcal/mol are −12,3, −4.8, −6.0, −5,1, and −6.3 respectively. Finally, four ligands bind strongly to the receptor Donepezil at RMSD 0.327 Å, and the venomous agent (VX) compound binds the most strongly compared to the other test ligands. Furthermore, in the toxicity test of Compound VX, which exhibits neurotoxic activity, no toxic activity was observed on specific organs and targets.

Evaporation of sulphur mustard (HD) from common matrices with comparison to nerve agents

ABSTRACT The use of chemical warfare agents (CWAs) in terrorist attacks remains a potential threat. Therefore, an updated wide-ranging database that contains details on the fate of CWAs on environmental surfaces is required, especially for the persistent blister agent sulphur mustard (HD). For this purpose, long-period evaporation rates measurements of HD from various common urban matrices were conducted from our specialised laboratory-designed wind tunnel. Small HD droplets were dispersed on each matrix surface, and then placed in the evaporation chamber. Samples of the target material were collected by continuous sampling on SPE (solid-phase extraction) tubes and analysed by GC (gas-chromatography) analytical method. Profiles of the air vapour concentrations as a function of time (up to four orders of magnitude) and the total mass balances were calculated at two temperatures. The results indicated fast clearance of HD together with a nearly full mass balance from stainless steel and smooth surface tiles, as these matrices are relatively inert. On the other hand, asphalt blocks relatively conserve HD, exhibiting a slow-release mode of action over 7–11 days until matching the GPL (General Population Limit) for HD. The concentration profile of commercial sidewalk bricks showed a moderate decay that characterises a semi-conserving matrix. These findings were compared to the evaporation profiles of the nerve agents sarin (GB) and VX from the same surfaces at the same experimental conditions. We can conclude that HD contamination can cause a secondary risk by a slow release into the atmosphere, especially from surfaces exhibiting conserving characteristics.

Experimental and chemical kinetic modeling study of high-temperature oxidation of diisopropyl methylphosphonate (DIMP) - A sarin simulant

Chemical warfare (CW) agent simulants are used in laboratory experiments to study the combustion characteristics of CW agents due to their high toxicity. A crucial CW agent simulant with a chemical structure similar to the deadly nerve agent Sarin (GB) is diisopropyl methylphosphonate (DIMP), an organophosphate compound (OPC). In this study, the high-temperature oxidation of DIMP is investigated in a shock tube at temperatures between 1440 K and 1710 K and a pressure of 1–2 atm. The carbon monoxide mole fraction time histories near 4.9 µm were obtained using laser absorption spectroscopy. The rate parameters for DIMP's H-abstraction reactions with O, and OH radicals were determined using molecular simulations. The rates of reactions involving smaller phosphorous species were also calculated at the CBS-QB3 level. These reactions along with the isopropanol sub-mechanism from the literature were added to the LLNL model to obtain an improved chemical kinetic mechanism for DIMP. Since isopropanol was a major intermediate in DIMP decomposition, validations were conducted with CO time histories during the oxidation of isopropanol. The new model predicted CO during isopropanol oxidation reasonably well. Both the LLNL model and the model developed in this work could predict CO time histories during DIMP oxidation satisfactorily. To comprehend the CO formation pathways and sensitive reactions during DIMP oxidation, reaction path analysis and sensitivity analysis were also carried out. The reaction mechanism developed here will help in the design, development, and optimization of efficient, effective and secure CW destruction techniques.

Penetrating the Blood-Brain Barrier for Targeted Treatment of Neurotoxicant Poisoning by Nanosustained-Released 2-PAM@VB1-MIL-101-NH2(Fe).

It is very important to establish a sustained-release pralidoxime chloride (2-PAM) drug system with brain targeting function for the treatment of neurotoxicant poisoning. Herein, Vitamin B1 (VB1), also known as thiamine, which can specifically bind to the thiamine transporter on the surface of the blood-brain barrier, was incorporated onto the surface of MIL-101-NH2(Fe) nanoparticles with a size of ∼100 nm. Pralidoxime chloride was further loaded within the interior of the above resulted composite by soaking, and a resulting composite drug (denoted as 2-PAM@VB1-MIL-101-NH2(Fe)) with a loading capacity of 14.8% (wt) was obtained. The results showed that the drug release rate of the composite drug was increased in PBS solution with the increase of pH (2-7.4) and a maximum drug release rate of 77.5% at pH 4. Experiments on the treatment of poisoning by gavage with the nerve agent sarin in mice combined with atropine revealed that sustained release of 2-PAM from the composite drug was achieved for more than 72 h. Sustained and stable reactivation of poisoned acetylcholinesterase (AChE) was observed with an enzyme reactivation rate of 42.7% in the ocular blood samples at 72 h. By using both zebrafish brain and mouse brain as models, we found that the composite drug could effectively cross the blood-brain barrier and restore the AChE activity in the brain of poisoned mice. The composite drug is expected to be a stable therapeutic drug with brain targeting and prolonged drug release properties for nerve agent intoxication in the middle and late stages of treatment.

Phosphonylated tyrosine and lysine residues as biomarkers of local exposure of human hair to the organophosphorus nerve agents sarin and VX.

We herein present for the first time a micro liquid chromatography-electrospray ionization high-resolution tandem-mass spectrometry (μLC-ESI MS/HR MS) procedure to detect phosphonylated tyrosine (Tyr) and lysine (Lys) residues obtained from human hair exposed to organophosphorus nerve agents (OPNA). In general, toxic OPNA react with endogenous blood proteins causing the formation of adducts representing well-known targets for biomedical analysis to prove exposure. In contrast, no protein-derived biomarker has been introduced so far to document local exposure of hair. Accordingly, we developed and characterized a μLC-ESI MS/HR MS method for the analysis of scalp hair exposed to OPNA in vitro. Type I and Type II keratin from hair was dissolved during lysis, precipitated and subjected to pronase-catalyzed hydrolysis yielding single adducted Lys and in a much higher amount Tyr residues. Exposure to sarin caused the adduction of an isopropyl methylphosphonic acid moiety and exposure to VX yielded adducts of ethyl methylphosphonic acid, well suited as biomarkers of exposure. These were of appropriate stability in the autosampler for 24 h. The biomarker yield obtained from hair of six individuals as well as from hair of six different parts of the body of one individual (armpit, beard, leg, arm, scalp, and pubic) differed reasonably indicating the variable individual protein composition and structure of hair. Exposed hair stored at ambient temperature for 9weeks with contact to air and daylight showed stability of all adducts and therefore their suitability for verification of exposure.

Application of Cotton Swab–Ag Composite as Flexible Surface-Enhanced Raman Scattering Substrate for DMMP Detection

It is both important and required to quickly and accurately detect chemical warfare agents, such as the highly toxic nerve agent sarin. Surface-enhanced Raman scattering (SERS) has received considerable attention due to its rapid results, high sensitivity, non-destructive data acquisition, and unique spectroscopic fingerprint. In this work, we successfully prepared SERS cotton swabs (CSs) for the detection of the sarin simulant agent dimethyl methyl phosphonate (DMMP) by anchoring N1-(3-trimethoxysilylpropyl) diethylenetriamine (ATS)/silver nanoparticle (AgNP) nanocomposites on CSs using ATS as the stabilizer and coupling agent. Simultaneously, the binding mode and reaction mechanics between the AgNP, ATS, and CS were confirmed by XPS. The modified CSs exhibited good uniformity, stability, and adsorption capability for SERS measurements, enabling the adsorption and detection of DMMP residue from an irregular surface via a simple swabbing process, with a detection limit of 1 g/L. The relative standard deviations (RSDs) of RSD710 = 5.6% had high reproducibility. In this research, the fabrication method could easily be extended to other cellulose compounds, such as natural fibers and paper. Furthermore, the versatile SERS CSs can be used for the on-site detection of DMMP, particularly in civil and defense applications, to guarantee food security and the health of the population.

A chemodosimetric approach for the visual detection of nerve agent simulant diethyl chlorophosphate (DCP) in liquid and vapour phase.

In this work, a novel fluorescent ratiometric switch, 8-((6-(1H-benzo[d]imidazol-2-yl)pyridin-2-yl)methoxy)quinoline (BIPQ), has been introduced for sensing an organophosphorus (OP) chemical vapor threat, diethyl chlorophosphate (DCP), the low-toxic mimic of the real nerve agent sarin (GB). BIPQ is efficient at detecting DCP in both solution and gaseous phase and has potential practical application with high sensitivity and selectivity. The probe shows significant ratiometric emission in the presence of DCP along with a distinct color change from blue to cyan under UV light. The sensing mechanism of the chemodosimeter is based on the generation of a new adduct, BIPQ-DCP, through a nucleophilic substitution reaction with DCP followed by a ring-closure process to form the final product. The detection limit of BIPQ for DCP was determined to be in the order of 10-8 (M) in the liquid state. DFT and TDDFT computational techniques were carried out in order to interpret the electronic properties theoretically.

Luminescent lanthanide-based chemodosimeter for selective detection of G-series nerve agent simulant with multiple reactive sites

The strongly chelated luminescent LnIII-based optical probes: [Ln(dipicOH)3]3- [Ln = EuIII (1), TbIII (2)], decorated with multiple reactive peripheral hydroxyl groups were strategically designed for the selective detection of diethyl chlorophosphate (DCP), a simulant of sarin (GB) nerve agent. Their reaction results in the modulation of antenna effect and/or ligand-exchange reactions as reflected in the quenching of the 5DJ-7FJ transitions of respective LnIII probes.