Cyanide as a weapon of terror

Fluorescence-based ratiometric sensors as emerging tools for CN- detection: Chemical structures, sensing mechanisms and applications

Hazardous cyanide anions (CN-) are increasingly threatening the environment and human health due to their widespread use in industry and many other fields. Over the past three decades, a large number of probes have been reported to sensitively and selectively detect this toxic anion, while a rather limited number of ratiometric fluorescent probes have been developed. The ratiometric probes have significant potential in bio-imaging and biomedical applications because of the ability to detect CN- in a quick, convenient and affordable way. In this review, we introduce 42 ratiometric fluorescent probes reported in the past 6 years (2018-2023) for CN- detection. Our description includes the chemical structures, photo-physical properties, CN- sensing mechanisms, solution color changes, limits of detection (LODs) and/or various applications of these chemical probes. This review provides guidelines for design and development of a new ratiometric probe for effective CN- detection.

Types of Disasters

Disasters are increasing around the world. Children are greatly impacted by both natural disasters (forces of nature) and man-made (intentional, accidental) disasters. Their unique anatomical, physiological, behavioral, developmental, and psychological vulnerabilities must be considered when planning and preparing for disasters. The nurse or health care provider (HCP) must be able to rapidly identify acutely ill children during a disaster. Whether it is during a natural or man-made event, the nurse or HCP must intervene effectively to improve survival and outcomes. It is extremely vital to understand the medical management of these children during disasters, especially the use of appropriate medical countermeasures such as medications, antidotes, supplies, and equipment.

Development of magnetic carbon nanotubes for dispersive micro solid phase extraction of the cyanide metabolite, 2-aminothiazoline-4-carboxylic acid, in biological samples

2-aminothiazoline-4-carboxylic acid (ATCA) is a minor metabolite of cyanide and is suggested to be a promising biomarker for cyanide exposure due to its specificity to cyanide metabolism and its excellent short- and long-term stability during storage. In this study, magnetic carbon nanotubes, including magnetic multi-walled carbon nanotubes (Mag-MWCNT) and magnetic single-walled carbon nanotubes (Mag-SWCNT) were synthesized as a novel sorbent for dispersive micro solid phase extraction (d-μSPE) to extract ATCA from biological matrices. ATCA spiked deionized water samples with the addition of the isotopic internal standard (ATCA - ¹³C, ¹⁵N) were subjected to Mag-CNT/d-μSPE to confirm extraction efficiency of this new technique. The extracted ATCA was derivatized and quantitated using gas chromatography/mass spectrometry (GC/MS) analysis. The extraction parameters were optimized and a detection limits of 15 and 25 ng/mL were obtained for synthetic urine and bovine blood respectively with a linear dynamic range of 30-1000 ng/mL. The optimized Mag-CNT/d-μSPE method facilitated efficient extraction of ATCA using 2 mg of Mag-MWCNT with a 10-minute extraction time. The current assay was also found to be effective for the extraction of ATCA with average recoveries of 97.7 ± 4.0% (n = 9) and 96.5 ± 12.1% (n = 9) from synthetic urine and bovine blood respectively. The approach of using Mag-CNT to facilitate d-μSPE offered a novel alternative to extract ATCA from complex biological matrices.

A countermeasure development pipeline

We have developed an integrated pipeline for countermeasure discovery that, under the auspices of the National Institutes of Health Countermeasures Against Chemical Threats network, is one of the few efforts within academia that by design spans the spectrum from discovery to phase I. The successful implementation of this approach for cyanide would enable efficient proof-of-concept studies that would lay the foundation for a generalizable strategy for parallel mechanistic studies and accelerated countermeasure development in the face of new and emerging chemical threats.

Cyanide Detoxification by the Cobalamin Precursor Cobinamide

Cyanide is a highly toxic agent that inhibits mitochondrial cytochrome-c oxidase, thereby depleting cellular ATP. it contributes to smoke inhalation deaths in fires and could be used as a weapon of mass destruction. Cobalamin (vitamin B12) binds cyanide with a relatively high affinity and is used in Europe to treat smoke inhalation victims. Cobinamide, the penultimate compound in cobalamin biosynthesis, binds cyanide with about 1010 greater affinity than cobalamin, and we found It was several-fold more effective than cobalamin in (i) reversing cyanide inhibition of oxidative phosphorylation in mammalian cells; (ii) rescuing mammalian cells and Drosophila melanogaster from cyanide toxicity; and (iii) reducing cyanide inhibition of Drosophila Malpighian tubule secretion. Cobinamide could be delivered by oral ingestion, inhalation, or injection to Drosophila, and it was as effective when administered up to 5 mins post-cyanide exposure as when given preexposure. We conclude that cobinamide is an effective cyanide detoxifying agent that has potential use as a cyanide antidote, both in smoke inhalation victims and in persons exposed to cyanide used as a weapon of mass destruction.

Accelerated stability and bioassay of a new oral α-ketoglutarate formulation for treating cyanide poisoning

CONTEXT

Due to several limitations of existing cyanide antidotes, α-ketoglutarate (α-KG) has been proposed as a promising treatment for cyanide.

OBJECTIVE

This study reports the accelerated stability and bioassay of a new oral α-KG formulation.

MATERIALS AND METHODS

Amber-colored PVDF bottles containing 100 ml of 10% α-KG in 70% sorbitol, preservative (sodium methyl paraben and sodium propyl paraben), sweetener (sodium saccharine), flavor (American ice-cream soda and peppermint) and color (tartrazine), at pH 7.0-8.0 were stored in stability chamber (40 ± 2 °C and 75 ± 5% humidity) for 6 months in a GMP compliant facility. Various physical (pH, color, evaporation, extractable volume and clarity), chemical (identification and quantification of active ingredient) and microbiological (total aerobic count) analyses, together with protection studies were carried periodically in mice. Acute toxicity of the formulation and bioavailability of α-KG were assessed in rats at the beginning of the experiment.

RESULTS

No physical changes and microbiological growth were observed in the formulation. After 6 months, α-KG content in the formulation diminished by ∼24% but its protective efficacy against cyanide remained at 5.9-fold. Protection was further characterized spectrophotometrically by disappearance of α-KG spectrum in the presence of cyanide, confirming cyanohydrin formation. Oral LD50 of α-KG formulation in rats was >7.0 g/kg body weight, and did not produce any acute toxicity of clinical significance. Also, an appreciable amount of α-KG was measured in blood.

CONCLUSION

As per the guidelines of International Conference on Harmonization, the new α-KG formulation exhibited satisfactory stability, bioefficacy and safety as cyanide antidote.

A disposable blood cyanide sensor

Deaths due to smoke inhalation in fires are often due to poisoning by HCN. Rapid administration of antidotes can result in complete resuscitation of the patient but judicious dosing requires the knowledge of the level of cyanide exposure. Rapid sensitive means for blood cyanide quantitation are needed. Hydroxocyanocobinamide (OH(CN)Cbi) reacts with cyanide rapidly; this is accompanied by a large spectral change. The disposable device consists of a pair of nested petri dish bottoms and a single top that fits the outer bottom dish. The top cover has a diametrically strung porous polypropylene membrane tube filled with aqueous OH(CN)Cbi. One end of the tube terminates in an amber (583nm) light emitting diode; the other end in a photodiode via an acrylic optical fiber. An aliquot of the blood sample is put in the inner dish, the assembly covered and acid is added through a port in the cover. Evolved HCN diffuses into the OH(CN)Cbi solution and the absorbance in the long path porous membrane tube cell is measured within 160 s. The LOD was 0.047, 1.0, 0.15, 5.0 and 2.2 μM, respectively, for water (1 mL), bovine blood (100 μL, 1 mL), and rabbit blood (20 μL, 50 μL). RSDs were<10% in all cases and the linear range extended from 0.5 to 200 μM. The method was validated against a microdiffusion approach and applied to the measurement of cyanide in rabbit and human blood. The disposable device permits field measurement of blood cyanide in <4 min.

Sodium Thiosulfate or Hydroxocobalamin for the Empiric Treatment of Cyanide Poisoning?

Cyanide poisoning must be seriously considered in victims of smoke inhalation from enclosed space fires; it is also a credible terrorism threat agent. The treatment of cyanide poisoning is empiric because laboratory confirmation can take hours or days. Empiric treatment requires a safe and effective antidote that can be rapidly administered by either out-of-hospital or emergency department personnel. Among several cyanide antidotes available, sodium thiosulfate and hydroxocobalamin have been proposed for use in these circumstances. The evidence available to assess either sodium thiosulfate or hydroxocobalamin is incomplete. According to recent safety and efficacy studies in animals and human safety and uncontrolled efficacy studies, hydroxocobalamin seems to be an appropriate antidote for empiric treatment of smoke inhalation and other suspected cyanide poisoning victims in the out-of-hospital setting. Sodium thiosulfate can also be administered in the out-of-hospital setting. The efficacy of sodium thiosulfate is based on individual case studies, and there are contradictory conclusions about efficacy in animal models. The onset of antidotal action of sodium thiosulfate may be too slow for it to be the only cyanide antidote for emergency use. Hydroxocobalamin is being developed for potential introduction in the United States and may represent a new option for emergency personnel in cases of suspected or confirmed cyanide poisoning in the out-of-hospital setting.

Chemical Terrorism Attacks: Update on Antidotes

There is well-founded concern that a chemical or radioactive agent will at some point be used as a weapon of terror. There are several antidotes that, if used correctly in a timely fashion, can help lessen the harm caused by these agents. This article is meant to introduce the clinician to several such agents, along with the antidotes useful in the management of exposure to these. It covers the indications, administration, and precautions for using these antidotes.

The effects of weapons of mass destruction on children

PURPOSE

Children are especially vulnerable to the effects of chemical and biological weapons of mass destruction (WMD) because of physiologic, pharmacologic, and developmental characteristics. Presentation of signs and symptoms of exposure to biological and chemical agents are similar to those seen in adults. Pediatric considerations for decontamination and treatment of child victims of biological and chemical agents are discussed.

CONCLUSION

As front-line providers, nurses need to be aware of potential agents, their uses and effects as WMD, and recommended treatments.

PRACTICE IMPLICATIONS

Understanding the additional physiologic and situational needs of children, nurses can optimize the survival and outcomes of children when disaster strikes.