Detection Of Nerve Agents Research Articles

Effect of sensing material basicity on excited-state intramolecular proton transfer-based detection of G-series nerve agents

The use of G-series nerve agents represents a significant threat and there is a need for rapid and selective in-field identification. We report that sensing materials composed of ESIPT-based silyl ethers can be used to detect the hydrogen fluoride that is present in phosphonofluoridate agents such as sarin and its simulant di-iso-propyl fluorophosphate (DFP). We find that the ability of the sensing material to detect the hydrogen fluoride in DFP is dependent on the basicity of the nitrogen atom that forms part of the ESIPT moiety upon deprotection. When the pKa of the conjugate acid of the nitrogen atom was lower than that of hydrogen fluoride the ability of the sensing material to detect the acid and hence simulant was curtailed. However, when the pKa of the conjugate acid was 3 or higher, then hydrogen fluoride could be rapidly detected. The best performing sensing material could detect hydrogen fluoride concentrations as low as 3 ppb in DFP of 99 % purity in one minute. Based on sarin having the same purity level, we estimate that it would be detectable at a concentration of ≈40 ppb in one minute, which is lower than the Acute Exposure Guideline 3 (life-threatening effects) of 64 ppb for a 10-min exposure.

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.

Effect of Silyl Ether Bulk on Excited-State Intramolecular Proton Transfer-Based Sensing of Extant Hydrogen Fluoride for G-Series Nerve Agent Detection.

Luminescence-based sensing provides a method for the rapid detection of nerve agents. Previous approaches have generally focused on sensing materials containing a nucleophilic group that can react with the electrophilic phosphorus atom found in nerve agents. Herein we report an alternative approach for the detection of phosphonofluoridate-based G-series nerve agents that utilizes the fact they contain hydrogen fluoride. We have developed silylated sensing materials based on an excited-state intramolecular proton transfer (ESIPT) reporter compound, 2-[benzo[d]thiazol-2-yl]phenol. Thin films of differently silylated 2-[benzo[d]thiazol-2-yl]phenol were found to react with the hydrogen fluoride found in di-iso-propyl fluorophosphate (DFP), a simulant of sarin (G-series nerve agent), and turn on the ESIPT emission of the reporter compound. The use of the ESIPT emission reduced the impact of background fluorescence and improved the sensitivity of the detection. The effectiveness of the approach was dependent on the stability of the silyl protecting group used, with the least sterically hindered (trimethylsilyl) found to be too unstable to the ambient environment while the most sterically hindered, e.g., tri-iso-propylsilyl and tert-butyldiphenylsilyl were found to be insufficiently reactive to be useful in a real detection scenario. The sensing material composed of the tert-butyl dimethylsilyl protected 2-[benzo[d]thiazol-2-yl]phenol was found to have the best balance between stability under ambient conditions, and reactivity and selectivity to hydrogen fluoride. In a 3s exposure, it could detect hydrogen fluoride down to a concentration of around 23 ppm in DFP with 99% purity.

Porphyrin complex-based reversible fluorescent film sensor for differentiating and detecting sarin mimics vapor

This study presents a TAPP-based fluorescent sensor for diethylchlorophosphate (DCP), a surrogate for sarin, addressing the critical challenge of detecting nerve agents. The sensor can form a reversible weak bond interaction with the PO group in sarin by using the reversible weak bond complexation mechanism in the porphyrin cavity, which is the key to realize the reversible function of the sensor. In this study, we constructed a fluorescence probe that combines the advantages of physical process and chemical reaction process sensing, which not only ensures selectivity, but also realizes continuous and reversible real-time detection of DCP. The sensor demonstrates excellent photochemical stability and sensitivity, with an actual detection limit of 10 ppt and a theoretical detection limit of 1 ppt. In addition, it can differentiate challenging interferents like HCl through response kinetics, offering a practical, cost-effective, and environmentally sustainable solution for nerve agent detection in high-risk environments.

Evaluation of the SERS performances of Tabun and VX label-free detection in complex and multicomponent fluids

Nerve agents represent a serious threat to security worldwide. Chemical terrorism has become an alarming danger since the technological progresses have simplified the production of nerve agents. Therefore, there is an immediate demand for a fast and precise detection of these compounds on-site and real-time. In this perspective, Surface-Enhanced Raman Scattering (SERS) has emerged as a well-suited alternative for on-field detection.SERS performances of unfunctionalized SERS substrates were evaluated in realistic samples. Two nerve agents, Tabun and VX, were diluted in two matrix models: a contact lens solution, and a caffeine-based eye serum. The performance two research-grade instruments and two portable devices were compared. Despite the use of a small sampling volume of complex matrices without any sample pre-treatment, we achieved Tabun detection in both media, with a practical limit of detection (LOD) in the range of 7–9 ppm in contact lens liquid, and of 10.2 ppm in eye serum. VX detection turned out to be more challenging and was achieved only in contact lens solution, with a practical LOD in the range of 0.6–5 ppm.These results demonstrate the feasibility of on-field detection of nerve agents with SERS, that could be implemented when there is suspicion of chemical threat.

Visual detection and discrimination of nerve and blood agents using a dual-site fluorescent probe in living cells and mice

Of all chemical warfare agents (CWAs), only nerve and blood agents cause massive mortality at low concentrations. To better detect and discriminate nerve and blood agents, a reliable detection method is desirable. We report a series of fluorescent probes for nerve and blood agent detection. Among the tested probes, SR-Pip detected nerve and blood agents quickly (within 10 s for nerve agents and 1 min for blood agents). SR-Pip coupled with nerve agent produced a weak orange fluorescence with good sensitivity [limit of detection (LOD)= 5.5 μM]. Upon reaction with blood agent, the fluorescence of SR-Pip changed from orange fluorescence to blue fluorescence with detection limits as low as 9.6 nM. This probe effectively visualised different concentrations of nerve agents in living cells and mice. A portable test kit using SR-Pip instantly detected nerve and blood agents. To the best of our knowledge, SR-Pip is the first fluorescent probe for nerve and blood agent detection.

Trace Amount of Bi-Doped Core-Shell Pd@Pt Mesoporous Nanospheres with Specifically Enhanced Peroxidase-Like Activity Enable Sensitive and Accurate Detection of Acetylcholinesterase and Organophosphorus Nerve Agents.

The urgent need for sensitive and accurate assays to monitor acetylcholinesterase (AChE) activity and organophosphorus pesticides (OPs) arises from the imperative to safeguard human health and protect the ecosystem. Due to its cost-effectiveness, ease of operation, and rapid response, nanozyme-based colorimetry has been widely utilized in the determination of AChE activity and OPs. However, the rational design of nanozymes with high activity and specificity remains a great challenge. Herein, trace amount of Bi-doped core-shell Pd@Pt mesoporous nanospheres (Pd@PtBi2) have been successfully synthesized, exhibiting good peroxidase-like activity and specificity. With the incorporation of trace bismuth, there is a more than 4-fold enhancement in the peroxidase-like performance of Pd@PtBi2 compared to that of Pd@Pt. Besides, no significant improvement of oxidase-like and catalase-like activities of Pd@PtBi2 was found, which prevents interference from O2 and undesirable consumption of substrate H2O2. Based on the blocking impact of thiocholine, a colorimetric detection platform utilizing Pd@PtBi2 was constructed to monitor AChE activity with sensitivity and selectivity. Given the inhibition of OPs on AChE activity, a biosensor was further developed by integrating Pd@PtBi2 with AChE to detect OPs, capitalizing on the cascade amplification strategy. The OP biosensor achieved a detection limit as low as 0.06 ng mL-1, exhibiting high sensitivity and anti-interference ability. This work is promising for the construction of nanozymes with high activity and specificity, as well as the development of nanozyme-based colorimetric biosensors.

A pyrene-based chromo-fluorogenic probe for specific detection of sarin gas mimic, diethylchlorophosphate.

Nerve agents are becoming serious issues for the healthy and sustainable environment of modern civilization. Therefore, its detection and degradation are of paramount importance to the scientific community. In the present contribution, we have introduced a chromo-fluorogenic pyrene-based probe, (E)-2-methoxy-3-(pyren-1-ylimino)-3,8a-dihydro-2H-chromen-4-ol (PMCO)to detect sarin stimulant diethylchlorophosphate (DCP) in solution and gaseous phases. On inserting DCP in PMCO solution, a visual colorimetric change from yellow to clear colourless in daylight and highly intensified blue fluorescence was observed instantly under a 365 nm portable UV lamp light. PMCO has outstanding selectivity and high sensitivity with a limit of detection of 1.32 μM in dimethyl sulfoxide (DMSO) medium and 77.5nM in 20% H2O-DMSO. A handy strained paper strip-based experiment was demonstrated to recognize DCP in a mixture of similar toxic analytes. A dip-stick experiment was performed to identify DCP vapour, and may be used as an effective photonic tool. We also demonstrated real sample analysis utilizing different DCP-spiked water samples and validating DCP detection even in various types of soils such as sand, field, and mud. Therefore, this present study provides an effective chemosensor for instant and on-site detection of toxic nerve agents in dangerous circumstances.

Two-dimensional photonic crystal sensor enabled by hydrophobic hydrogen-bonded organic Frameworks@Metal-Organic frameworks for trace nerve agents detection

The development of fast and accurate sensors for nerve agents holds immense significance for homeland security and public health. However, the humidity interference from ambient environments and poor sensitivity for trace nerve agents are largely unsolved problems. To overcome the problems, a humidity-independent two-dimensional photonic crystal (2-D PC) sensor is developed by exploiting UiO-66-NH2 2-D PC with excellent sensitivity coupled to a hydrophobic hydrogen-bonded organic framework (HOFs) for detection sarin simulant dimethyl methyl phosphonate (DMMP). Selective sensing results show that the HOFs@UiO-66-NH2 2-D PC sensor presents the outstanding DMMP specificity, and the limit of detection (LOD) for DMMP response of the sensor can reach 508 ± 68 ppb at room temperature. Water-resistant experiments demonstrate that the HOFs@UiO-66-NH2 2-D PC sensor shows excellent stability even under 80% relative humidity (RH). Moreover, the sensor also exhibits a rapid response/recovery time of 1 s/3 s and can maintain excellent sensing performance under heat-treatment of 200 °C and in the long-term storage (30 days). The adsorption kinetics and the hydrogen bond interaction are conducted to elucidate the mechanism of enhanced sensing DMMP properties. These results indicate the potential application of the sensor in the trace nerve agent's detection, especially in humidity environment.

Wearable chemical gas sensors with color changeable functional dyes for detection of organophosphorus nerve agents

Wearable chemical gas sensors with color changeable functional dyes for detection of organophosphorus nerve agents

A portable and accessible Probe: Smartphone assisted colorimetric nerve agent detection

Due to the extreme toxicity and volatility of organophosphorus nerve agents, the development of colorimetric sensors plays a vital role in detecting these agents in both solution and vapors. Herein, we have developed a low-cost probe based on 2-Anilino-6-dibutylamino-3-methylfluoran (ODB-2) for the detection of nerve agents. This probe can achieve a sensitive response to diethyl chlorophosphate (DCP) in both solution and vapors. The limit of detection (LOD) for DCP in solution was determined to be 0.36 µmol/L, while the LOD for DCP in vapors was determined to be 0.13 ppb. Meanwhile, the response time to reach 80 % of the discoloration endpoint was only 5.2 s, which meet the requirements for practical application. The detection mechanism of this sensor was studied by using 1H NMR, MS, SEM-EDS, and FT-IR. Furthermore, we integrated ODB-2 into the self-assembled portable detection system, enabling on-site and real-time monitoring of DCP vapors with the LOD of 0.23 ppb. The use of this affordable detection system is highly significant for detecting nerve agents.

A Nanoporous Polymer Modified with Hexafluoroisopropanol to Detect Dimethyl Methylphosphonate.

The increasing threat of nerve agents has prompted the need for gas sensors with fast response, high sensitivity, and good stability. In this work, the hexafluoroisopropanol functional group was modified on a porous aromatic framework material, which served as a sensitive material for detecting dimethyl methylphosphonate. A nerve agent sensor was made by coating sensitive materials on a surface acoustic wave device. Lots of pores in sensitive materials effectively increase the specific surface area and provide channels for diffusion of gas molecules. The introduction of hexafluoroisopropanols enables the sensor to specifically adsorb dimethyl methylphosphonate and improves the selectivity of the sensor. As a result, the developed gas sensor was able to detect dimethyl methylphosphonate at 0.8 ppm with response/recovery times of 29.8/43.8 s, and the detection limit of the gas sensor is about 0.11 ppm. The effects of temperature and humidity on the sensor were studied. The results show that the baseline of the sensor has a linear relationship with temperature and humidity, and the temperature and humidity have a significant effect on the response of the sensor. Furthermore, a device for real-time detection of nerve agent is reported. This work provides a new strategy for developing a gas sensor for detecting nerve agents.

Thin colorimetric film array for rapid and selective detection of v-type nerve agent mimic in potentially contaminated areas

The expeditious detection and quantification of V-series nerve agents (VX) on potentially contaminated surfaces are crucial for the prevention of regional conflict incidents, acts of terrorism, or illicit activities. However, the low volatility and high toxicity of VX make these tasks challenging. Herein, we designed two novel colorimetric thin polymeric films to rapidly and sensitively detect demeton-S, a VX mimic, in contaminated areas. The polymeric films were specifically engineered to include a coordination site for Au (III) ions. Initially, these films were coordinated with Au (III), causing a discernible alteration in color due to enhancement in intramolecular charge transfer process. In the presence of demeton-S, the Au (III) ligands in the films are displaced with demeton-S, resulting in the restoration of the original color of the film, as the enhanced intramolecular charge transfer process is inhibited and thereby serving as an indicator of the presence of demeton-S. The polymeric films exhibit remarkable selectivity toward demeton-S compared to G-type nerve agents and other interference. The reusability of the polymeric films for demeton-S detection was achieved owing to the reversibility of the films during the alternative exposure of Au (III) and demeton-S. The polymeric films demonstrated their applicability for demeton-S detection and quantification in several contaminated areas, including different water, soil, and skin, rendering them highly suitable for on-site measurements.

Simple Chemical and Cholinesterase Methods for the Detection of Nerve Agents Using Optical Evaluation.

The extreme toxicity of nerve agents and the broad spectrum of their physical and chemical properties, enabling the use of these agents in a variety of tactical situations, is a continuing challenge in maintaining the knowledge and capability to detect them, as well as in finding new effective methods. Despite significant advances in the instrumentation of the analysis of nerve agents, relatively simple methods based on the evaluation of colour signals (absorption and fluorescence), in particular those using the cholinesterase reaction, continue to be of importance. This review provides a brief presentation of the current status of these simple methods, with an emphasis on military applications, and illustrates the high interest of the professional community in their further development. At the same time, it also contains some peculiarities (high reliability and durability, resistance to extreme climatic conditions, work in deployed means of protection, low purchase prices, economic availability especially in a state of war, etc.) that the authors believe research and development of simple methods and means for the detection of nerve agents should respect.

Discriminative detection of soman or VX exposure using europium chelated microparticle-based immunofluorescence microfluidic chip

The retrospective detection of organophosphorus nerve agents (OPNAs) exposure has been achieved by the off-site analysis of OPNA-human serum albumin (HSA) adducts using mass spectrometry-based detection approaches. However, few specific methods are accessible for on-site detection. To address this, a novel immunofluorescence microfluidic chip (IFMC) testing system combining europium chelated microparticle (EuCM) with self-driven microfluidic chip assay has been established to unambiguously determine soman (GD) and VX exposure within 20 min, respectively. The detection system was based on the principle of indirect competitive enzyme-linked immunosorbent assay. The specific monoclonal antibodies that respectively recognized the phosphonylated tyrosine 411 of GD-HSA and VX-HSA adducts were labeled by EuCM to capture corresponding adducts in the exposed samples. The phosphonylated peptides in the test line and goat-anti-rabbit antibody in the control line were utilized to bind the EuCM-labeled antibodies for signal exhibition. The developed IFMC chip could discriminatively detect exposed HSA adducts with high specificity, demonstrating a low limit of detection at exposure concentrations of 0.5 × 10−6 mol/L VX and 1.0 × 10−6 mol/L GD. The exposed serum samples can be qualitatively detected following an additional pretreatment procedure. This is a novel rapid detection system capable of discriminating GD and VX exposure, providing an alternative method for rapidly identifying OPNA exposure.

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.

Ni-rGO Sensor Combined with Human Olfactory Receptor-Embedded Nanodiscs for Detecting Gas-Phase DMMP as a Simulant of Nerve Agents.

Nerve agents are organophosphorus toxic chemicals that can inhibit acetylcholinesterase, leading to paralysis of the nervous system and death. Early detection of nerve agents is important for safety issues. Dimethyl methylphosphonate (DMMP) is widely used as a simulant of nerve agents, and many studies have been conducted using DMMP as a substitute for detecting nerve agents. Despite many studies on sensors for detecting DMMP, they have limitations in sensitivity and selectivity. To overcome these limitations, a nickel-decorated reduced graphene oxide (Ni-rGO) sensor with human olfactory receptor hOR2T7 nanodiscs was utilized to create a bioelectronic nose platform for DMMP gas detection. hOR2T7 was produced and reconstituted into nanodiscs for enhancing the sensor's stability, especially for detection in a gas phase. It could detect DMMP gas selectively and repeatedly at a concentration of 1 ppb. This sensitive and selective bioelectronic nose can be applied as a practical tool for the detection of gaseous chemical warfare agents in military and safety fields.

Fabrication of a re-useable ionic liquid-based colorimetric organo nanosensor for detection of nerve agents’ stimulants

Nerve agents are highly poisonous organophosphorus chemicals, and the possibility of being used in terrorist attacks seriously threatens public safety. Thus, developing quick and straightforward detection techniques for these dangerous substances is paramount for the scientific communities. In this contribution, we have fabricated a sensitive and easily applicable ionic liquids (ILs) based colorimetric sensor for detecting various nerve agents' stimulants in solution and gas phases, respectively, based on methyl orange (MO)-based IL ([P66614]+[MO]-) derived from MO dye and trihexyltetradecylphosphonium chloride (P66614Cl) by a simple ion exchange mechanism. The developed [P66614]+[MO]- and water-suspended [P66614]+[MO]- nanoparticles are found to be very much sensitive to detecting various nerve agents' stimulants having detection limits in the μM range in any medium and could be identified based on the response times which is found to be superior to many chemosensors available in the literature. The naked eye observed a distinct color change from yellow to fuchsia in the presence of nerve agents' stimulants, which shows better sensitivity than the free organic indicator. Furthermore, a facile test strip with [P66614]+[MO]- and water-suspended [P66614]+[MO]- NPs has been fabricated that can achieve visual detection of various nerve agents' stimulants within the stockpiles of other analogous harmful analytes. Also, a dip-stick experiment has been performed to detect harmful toxic analytes vapor. The effectiveness of [P66614]+[MO]- and water-suspended [P66614]+[MO]- NPs in identifying and quantifying various nerve agents’ stimulants demonstrated its potential for usage as a signal tool for real sample analysis.

Quantum Dot-DNA FRET Conjugates for Direct Analysis of Methylphosphonic Acid in Complex Media.

Rapid detection of nerve agents from complex matrices with minimal sample preparation is essential due to their high toxicity and bioavailability. In this work, quantum dots (QDs) were functionalized with oligonucleotide aptamers that specifically targeted a nerve agent metabolite, methylphosphonic acid (MePA). These QD-DNA bioconjugates were covalently linked to quencher molecules to form Förster resonance energy transfer (FRET) donor-acceptor pairs that quantitatively measure the presence of MePA. Using the FRET biosensor, the MePA limit of detection was 743 nM in artificial urine. A decrease in the QD lifetime was measured upon DNA binding and was recovered with MePA. The biosensor's flexible design makes it a strong candidate for the rapid detection of chemical and biological agents for deployable, in-field detectors.

Visual and Rapid Detection of Nerve Agent Mimics in Gas and Solution Phase by a Simple Fluorescent Probe.

Chemical nerve agents are highly toxic organophosphorus compounds that are easy to obtain and can be utilized by terrorists to threaten homeland security and human safety. Those organophosphorus nerve agents contain nucleophilic ability that can react with acetylcholinesterase leading to muscular paralysis and human death. Therefore, there is great importance to explore a reliable and simple method to detect chemical nerve agents. Herein, the o-phenylenediamine-linked dansyl chloride as a colorimetric and fluorescent probe has been prepared to detect specific chemical nerve agent stimulants in the solution and vapor phase. The o-phenylenediamine unit serves as a detection site that can react with diethyl chlorophosphate (DCP) in a rapid response within 2 min. A satisfied relationship line was obtained between fluorescent intensity and the concentration of DCP in the range of 0-90 μM. In the optimized conditions, we conducted the fluorescent titration to measure the limits of detection (0.082 μM) with the fluorescent enhancement up to 18-fold. Fluorescence titration and NMR studies were also conducted to explore the detection mechanism, indicating that the formation of phosphate ester causes the intensity of fluorescent change during the PET process. Finally, probe 1 coated with the paper test is utilized to detect DCP vapor and solution by the naked eye. We expect that this probe may give some admiration to design the small molecule organic probe and applied in the selectivity detection of chemical nerve agents.