Design and development of a prototype for specific naked-eye detection of blister and nerve agents

In view of the strong need to strengthen the national security arising from chemical terrorism, a rapid, specific, and onsite detection of chemical warfare agents (CWAs) employing a simple and easy-to-use kit is of utmost importance. Constant and sincere efforts are being carried out by the scientific community to find reliable techniques/methods for early warning detection. Herein, we designed a prototype technique in the form of a smart and portable chemical weapon detection kit (CWDK) to facilitate rapid and onsite detection. In this portable kit, a range of unique chemical probes were condensed to achieve the specific chromogenic and fluorogenic detection and discrimination of each member of blister and nerve agents. The embodiment of three chemical probes (Fc, SQ, and LH2) was eventually employed in a compact and flexible plastic packaging for detecting the presence of CWAs with the 'naked-eye' in the areas where laboratory services do not normally exist. The CWDK contains dye/reagent vials, sampling assembly, and a UV torch. The convenience and practicality of this technique suggest a great prospect for highly specific sensing of the complete class of CWAs with fast and accurate results in real-time scenarios with a sensitivity much below their lethal dose.

Chromo-fluorogenic sensors for chemical warfare agents in real-time analysis: journey towards accurate detection and differentiation

The existence of chemical weapons (blister and nerve agents) is an unfortunate reality of the modern world. The usage of these chemical agents by rogue states or terrorist groups has showcased their ugly faces in the past and even in recent years. Despite extensive and strenuous efforts by the Organization for the Prohibition of Chemical Weapons (OPCW) to eliminate chemical warfare agents (CWAs) by the prohibition of their production and the destruction of their stockpiles, many countries still possess them in enormous quantities. Given the potential threat from these lethal agents, it is imperative to have a foolproof chemical sensor and detection system, which should consist of readily deployable chemical probes that can operate with high specificity and sensitivity. Over the last decade, our group has been engaged in designing and developing novel field-deployable sensing techniques by exploring approaches based on supramolecular tools, which can result in excellent specificity, sensitivity, high speed, portability and low cost. In this article, I describe our group's journey and success stories in the development of chemical warfare detection protocols, detailing the range of unique chemical probes and methods explored to achieve the specific detection of individual agents under real environmental conditions. It is interesting to note that the combination of three molecular probes (SQ, Fc and LH2) could simply achieve the detection of all CWAs at room temperature in one go without the need for nonportable and expensive instruments. The ease and generality of these techniques/methods suggest great promise for the highly specific chemical sensing of almost the entire class of CWAs. In this paper, a brief introduction is first provided to present the basic chemistry related to CWAs and the importance of supramolecular chemistry in the design of new protocols with new insights. The manipulation of molecular probes is then debated towards the development of a system for the chromo-fluorogenic sensing of CWAs without interference from most relevant analytes. Finally, the outlook of open challenges and the future developments of this rapidly evolving field is discussed.

Naphthalimide based smart sensor for CN−/Fe3+ and H2S. Synthesis and application in RAW264.7 cells and zebrafish imaging

Probe R designed as tailor-fit triple action smart chemosensor for the sequential detection of CN⁻ and Fe³⁺via colorimetric and fluorometric ‘on–off’ method and H₂S through colorimetric method in semi-aqueous conditions.

A highly selective colorimetric and "turn-on" fluorimetric chemosensor for detecting CN(-) based on unsymmetrical azine derivatives in aqueous media

A novel highly selective chemosensor S1 for cyanide based on unsymmetrical azine derivative was successfully designed and synthesized, which showed both colorimetric and fluorescence turn-on responses for cyanide ions in aqueous. This structurally simple chemosensor could detect CN(-) anion over other anions in aqueous solution DMSO/H2O (v/v=3:2) undergo deprotonation reaction. Results showed that the chemosensor S1 exhibited 50 fold enhancement in fluorescence at 530nm and showed an obvious change in color from colorless to yellow that could be detected by naked eye under the UV-lamp after the addition of CN(-) in aqueous solution. Moreover, the detection limit on fluorescence response of the sensor to CN(-) is down to 6.17×10(-8)M by titration method. Test strips based on S1 were obtain, which could be used as a convenient and efficient CN(-) test kit to detect CN(-) in aqueous solution.

Chromogenic and fluorogenic multianalyte detection with a tuned receptor: refining selectivity for toxic anions and nerve agents

In the present study, a chemical probe was finely tuned for the highly selective and sensitive chromogenic and fluorogenic detection of toxic anions and a nerve agent.

A cyanide-selective colorimetric “naked-eye” and fluorescent chemosensor based on a diketopyrrolopyrrole–hydrazone conjugate and its use for the design of a molecular-scale logic device

A novel diketopyrrolopyrrole (DPP)–hydrazone based receptor was designed and synthesized as a selective fluorescent and colorimetric chemosensor for cyanide in aqueous media via deprotonation between the hydrazide moiety of the probe and cyanide.

Detection of NaCN in aqueous media using a calixarene-based fluoroionophore containing ruthenium(ii)-bipyridine as the fluorogenic unit

A new fluoroionophore containing a Ru(ii)-bipyridine unit and a calixarene moiety is synthesized. It selectively detects CN⁻ from NaCN in aqueous media; its performance has been tested successfully in real samples.

A novel phenylacetylene-indolium fluorophore for detection of cyanide by the naked eye

The compound 2 mixed α-cyclodextrin exhibits the highest CN⁻ recognition sensitivity in aqueous media with the detection limit of 1.3 μM. Test strips based on compound 2 can act as a convenient and efficient CN⁻ test kit.

Colorimetric fluorescent cyanide chemodosimeter based on triphenylimidazole derivative

In this paper, we demonstrated a highly selective colorimetric chemodosimeter for cyanide anion detection. This chemodosimeter having a triphenylimidazole group as a fluorescent signal unit and a dicyano-vinyl group as a reaction unit was synthesized by the Knoevenagel condensation of 4-(4,5-diphenyl-1H-imidazol-2-yl)benzaldehyde with malononitrile in a reasonable yield. The probe exhibited an intramolecular charge transfer (ICT) absorption band at 420 nm and emission band at 620 nm, respectively. Upon the addition of cyanide anion, the probe displayed a blue-shifted spectrum and loss in color due to the disruption of conjugation. With the aid of the fluorescence spectrometer, the chemodosimeter exhibited a detection limit of 0.11 μM (S/N=3). Interferences from other common anions associated with cyanide anion analysis were effectively inhibited.