Cyanide: critical issues in diagnosis and treatment

Ratiometric detection and monitoring of cyanide in biological, environmental and food samples by a novel triphenylamine-xhantane based fluorescent probe

BACKGROUND

As cyanide (CN-) is a significant hazard to the environment and human health, it is essential to monitor cyanide levels in water and food samples. Moreover, real-time visualization of CN-could provide an additional understanding of its critical physiological and toxicological roles in living cells. The fluorescence approach based on small organic probes is an effective way for the detection of CN-. In this approach, a triphenylamine-xhantane conjugate was applied to detect in many samples such as sewage water, soil, sprouted potato, apricot seed, and living cells.

RESULTS

We report a new ratiometric near-infrared fluorescent probe based on a triphenylamine-xhantane derivative for CN-sensing in many samples. The probe displays high selectivity for only CN- ions among a series of analytes. The addition of cyanide to the dicyanovinyl moiety of the probe disrupts π-conjugation followed by the interruption of internal charge transfer. Consequently, the emission peak of the probe shifts hypsochromically from 655 to 495 nm. There is a linear correlation between the emission intensity (I495) and cyanide level, with a detection limit of 0.036 μM. The probe has many advantages over many probes, such as NIR fluorescence, ratiometric response, low cytotoxicity (85.0 % cell viability up to 50.0 μM of the probe), good membrane permeability, fast response time (4.0 min), high selectivity, good photostability, and anti-interference capability.

SIGNIFICANCE

Although various probes have been reported in the literature, the use of triphenylamine-xhantane unit as CN- probe has yet to be explored. The probe can detect trace levels of cyanide in many samples such as sewage water, soil, sprouted potatoes, and apricot seeds. Furthermore, it is successfully utilized for the ratiometric fluorescent bioimaging of cyanide in living cells.

Acute Cyanide Toxicity and Emergency Management in a Goldsmith: A Case Report

Acute cyanide toxicity is very rare but it is almost always associated with fatal outcomes. Here we describe the case of a 43-year-old healthy male who worked in a jewelry factory and presented with acute cyanide toxicity. He was successfully managed with all the supportive measures and an appropriate antidote kit containing amyl nitrite, sodium nitrite, and sodium thiosulfate. We also describe the relevant importance of knowing the history of easy access to cyanide as a part of the patient's profession, the critical nature of the patient at presentation, as well as the efforts needed to procure the antidote.

Tailored fluorophore design: Enhancing selectivity for cyanide ion sensing in water and food samples, and innovative device development

A rigid fluorophore unit of Julolidine/coumarin fused with an indolium-conjugated system was built for the immediate and effective recognition of cyanide ions in a 90 % aq. DMSO solution. The probes are capable of displaying better sensitivity/selectivity for the cyanide ion over a wide range of other interfering ions. The probe JI showed an instant colorimetric variation, whereas the modified probe JCI showed both colorimetric and fluorimetric variation with cyanide ion. The observed detection limit values indicated excellent sensitivity of the probe to the cyanide ion. HRMS and 1H NMR studies confirmed that the mechanism of detection of CN- is via the nucleophilic attack on the electron-deficient indolium moiety of the molecule. Moreover, the probes are well proficient in selective recognition of cyanide in various real time applications (test strips, electronic sensor kit, food and water sample analysis).

Efficient solid- and solution-state emissive reusable solvatochromic fluorophores for colorimetric and fluorometric detection of CN. Analyst 2024;149:1557-1570. [PMID: 38284868 DOI: 10.1039/d3an01697h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

In this work, a novel organic receptor, CPI [(E)-3-(4-(9H-carbazol-9-yl)phenyl)-2-(1H-benzo[d]imidazol-2-yl)acrylonitrile], was rationally designed and successfully fabricated for selective and sole recognition of CN- ions over other competitive anions through an obvious chromogenic and ratiometric emission change in DMSO. The distinct and prominent color change upon the addition of CN- can be attributed to the typical ICT process, which is induced by the deprotonation of acidic NH protons in the imidazole moiety. The sensor displayed strong solvatochromic effects in commonly used organic solvents such as n-hexane, toluene, diethyl ether, DCM, THF, DMF and DMSO. The chemical structure of the sensor was characterized by single-crystal X-ray diffraction, 1HNMR, 13CNMR, IR and mass spectroscopy. Significantly, the probe can function as a fluorescence-based sensor for the efficient detection of low-level water in organic solvents. The solid-state emission properties of CPI were successfully applied to recognise cyanide in a solid-state platform with naked eye-visualized distinct color change. The probe can be made reusable by adding TFA into the CN- treated probe solution. The detection limit of CPI towards CN- was determined to be 4.48 × 10-8 M. More importantly, the sensor is capable of detecting CN- in food samples and has been employed for wastewater treatment. Besides, easy-to-prepare CPI-coated test strips provide a simple, reusable and easy-to-handle protocol for the qualitative identification of CN- conveniently. Finally, density functional theory and time-dependent density functional theory were performed to verify the experimental outcomes theoretically.

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.

Ratiometric orange fluorescent and colorimetric highly sensitive imidazolium-bearing naphthoquinolinedione-based probes for CN- sensing in aqueous solutions and bio-samples

The widespread use of cyanide (CN^-) in industry results in contamination of various effluents such as drain, lake, and tap water, an imminent danger to the environment and human health. We prepared naphthoquinolinedione (cyclized; 1-5) and anthracenedione (un-cyclized) probes (6-7) for selective detection of CN^-. The addition of CN^- to the probe solutions (1-5) resulted in a color change from pale green to orange under 365 nm illumination. The nucleophilic addition of CN^- to C2 of the imidazolium ring of the probes is responsible for selective CN^- detection. Among all probes, 1 gave the lowest fluorescence-based LOD of 0.13 pM. In contrast, the un-cyclized probes (6 and 7) were substantially inferior to the cyclized counterparts (1 and 2, respectively) for detecting a trace amount of CN^-. The notably low LOD displayed by probe 1 was maintained in the detection of CN^- in real food samples, human fluids, and human brain cells. This is the first report studying imidazolium-bearing naphthoquinolinedione-based probes for CN^- sensing in 100% water.

Prehospital and Emergency Management

Burn care in the prehospital and emergency settings requires rapid assessment of airway, breathing, and circulation. Intubation (if indicated) and fluid resuscitation are most important in emergency burn care. Total body surface area burned and depth of burn are important early assessments that help guide resuscitation and disposition. Burn care in the emergency department further includes carbon monoxide and cyanide toxicity evaluation and management.

Fatalities in Swedish fire-related car crashes from a toxicologic perspective

Objective: Vehicle materials developments raise concerns about new patterns of vehicle fire toxic gas emissions. This study aimed to describe toxicologic components in a recent material of fatal car crashes on Swedish roads in which the vehicle caught fire and compare the results to a previous material.Methods: Retrospective registry study. All fatal car crashes with fire in Sweden 2009-2018 were extracted from the Swedish Transport Administration's In-Depth Studies Database and compared with an earlier study of the time period 1998-2008.Results: A total of 79 crashes and 94 fatalities were included. Carbon monoxide (COHb) blood levels >10% were found in 13 cases. Hydrogen cyanide (HCN) blood levels 0.1-1.7 µg/g were found in 10 cases. In 29 of the cases the person had a blood alcohol level (BAC) >0.2‰, which is the legal driving limit in Sweden. A total of 15 people died due to burn injuries and 2 individuals died due to toxic gas emissions without any other fatal traumatic injury. Total number of deaths in fire-related crashes halved from 181 (1998-2008) to 94 (2009-2018) but the percentage of fatalities in burning vehicles was unaltered (5% vs. 6%). The proportion of fatalities with HCN in the blood increased from 2% between 1998-2008 to 10% during 2009-2018 (p = 0.006). The age of the car involved in a crash increased by 0.26 years per calendar year (p = 0.001).Conclusions: The proportion of fatalities with measured levels of HCN in the blood has increased. Eleven of the 15 burn injury fatalities had high levels of alcohol, HCN, or COHb, possibly contributing to an inability to leave a burning vehicle. Faster rescue brought by improved specific education and training of ambulance and rescue services personnel may be of future importance, as may on-scene antidote administration and revised regulations of vehicle flammability.

Evaluation of prehospital hydroxocobalamin use in the setting of smoke inhalation

BACKGROUND

The indications for prehospital hydroxocobalamin are not well defined. The aim of this study was to evaluate prehospital signs and symptoms in patients who received hydroxocobalamin to improve future use.

METHODS

In this retrospective study, all patients who received prehospital Hydroxocobalamin at a tertiary care burn center from December 2012 to March 2018 were reviewed. Each case was evaluated for evidence of suspected cyanide toxicity: hypotension, syncope, CNS depression/altered mentation, seizures, respiratory or cardiac arrest. A determination was made whether or not hydroxocobalamin was indicated.

RESULTS

In this study, EMS providers administered hydroxocobalamin to 42 patients between December 2012 and March 2018. The majority (71%) of suspected cyanide exposures were from house fires. The most common prehospital findings were coma or depressed CNS (36%), followed by hypotension (16%) and cardiac arrest (12%). Sixty percent of patients treated with hydroxocobalamin had none of the six clinical indicators for potential cyanide toxicity. Carboxyhemoglobin and serum lactate were significantly different in patients that had a clinical indication for hydroxocobalamin compared to those who did not.

CONCLUSIONS

Prehospital hydroxocobalamin was used empirically however, indications are unclear. Using defined clinical indications may provide greater clarity for providers and reduce unnecessary use of hydroxocobalamin.

Inhalants

Toxic inhalants include various xenobiotics. Irritants cause upper and lower respiratory tract injuries. Highly water-soluble agents injure the upper respiratory tract, while low water-soluble inhalants injure the lower track. Asphyxiants are divided into simple asphyxiants and chemical asphyxiants. Simple asphyxiants displace oxygen, causing hypoxia, while chemical asphyxiants also impair the body's ability to use oxygen. Cyanide is a classic chemical asphyxiant. Treatment includes hydroxocobalamin. Electronic cigarette or vaping use-associated lung injury (EVALI) is a relatively new illness. Patients present with respiratory symptoms and gastrointestinal distress. EVALI appears to be associated with vaping cannabinoids. Treatment is supportive and may include steroids.

Antidotes for childhood toxidromes

Background

Poisoning causes significant morbidity and sometimes mortality in children worldwide. The clinical skill of toxidrome recognition followed by the timely administration of an antidote specific for the poison is essential for the management of children with suspected poisoning. This is a narrative review on antidotes for toxidromes in paediatric practice.

Methods

A literature search was conducted on PubMed with the keywords “antidote”, “poisoning”, “intoxication”, “children” and “pediatric”. The search was customized by applying the appropriate filters (species: humans; age: birth to 18 years) to obtain the most relevant articles for this review article.

Results

Toxidrome recognition may offer a rapid guide to possible toxicology diagnosis such that the specific antidote can be administered in a timely manner. This article summarizes toxidromes and their respective antidotes in paediatric poisoning, with an emphasis on the symptomatology and source of exposure. The antidote and specific management for each toxidrome are discussed. Antidotes are only available for a limited number of poisons responsible for intoxication. Antidotes for common poisonings include N-acetyl cysteine for paracetamol and sodium thiosulphate for poisoning by cyanide.

Conclusion

Poisoning is a common cause of paediatric injury. Physicians should be familiar with the recognition of common toxidromes and promptly use specific antidotes for the management of childhood toxidromes.

Cyanobiphenyl-spiropyrane and -hemicyanine conjugates for cyanide detection in organic/aqueous media through reverse ICT direction: Their practical applications

Cyanide is one of the most known toxic substances. It is used in many industries and threats human health and environment through releasing with wastewater. Therefore, it is very important to detect its accurate amount, rapidly. Herein, turn-on and turn-off fluorescence sensors of hybrid cyanobiphenyl-spiropyrane and -hemicyanine were developed for the detection of CN^- ions on the basis of nuchleophilic addition to indolium moiety. Detection behavior of the both probes toward a series of anions was investigated by means of fluorescence, UV-vis, NMR and TOF-MS techniques. The results obviously indicate that both probes show remarkable spectral changes and high selectivity toward CN^- with respect to other tested anions. Cyanide levels in water samples up to 0.208 μM could be quantitatively detected as practical application. A smartphone imaging application was successfully constructed for CN^- detection. Noticeably, production of cotton kids and PSF capsules revealed that the probe could be conveniently used for on-site measurement of cyanide without complicated instruments.

A Novel Imidazophenazine-Based Stimuli Responsive Chemosensor for Highly Selective and Sensitive Fluorescence Detection of CN–

A fluorescent imidazophenazine-based derivative (S) has been successfully synthesised, and can be used as a chemsensor for relay recognition of CN– in DMSO/H2O (7:3, v/v) solution, which exhibited external stimuli-responsiveness. The sensor immediately responded with obvious colour changes (from red to purple) and fluorescent quenching when CN– was added to the S solution. Its detection limit for CN– is 2.16×10−7 M. In addition, NMR spectroscopy and density function theory calculations were also used to confirm the recognition mechanism. In particular, the fluorescence responding circle could be repeated three times by the sequential addition of CN– and CH3COO– or CN– and HSO4–. Moreover, a CN– detection test paper was prepared using S, providing a convenient method for CN– identification.

Water-Soluble α-Amino Acid Complexes of Molybdenum as Potential Antidotes for Cyanide Poisoning: Synthesis and Catalytic Studies of Threonine, Methionine, Serine, and Leucine Complexes

Water-soluble complexes are desirable for the aqueous detoxification of cyanide. Molybdenum complexes with α-amino acid and disulfide ligands with the formula K[(L)Mo₂O₂(μ-S)₂(S₂)] (L = leu (1), met (2), thr (3), and ser (4)) were synthesized in a reaction of [(DMF)₃MoO(μ-S)₂(S₂)] with deprotonated α-amino acids; leu, met, thr, and ser are the carboxylate anions of l-leucine, l-methionine, l-threonine, and l-serine, respectively. Potassium salts of α-amino acids (leu (1a), met (2a), thr (3a), and ser (4a)) were prepared as precursors for complexes 1-4, respectively, by employing a nonaqueous synthesis route. The ligand exchange reaction of [Mo₂O₂(μ-S)₂(DMF)₆](I)₂ with deprotonated α-amino acids afforded bis-α-amino acid complexes, [(L)₂Mo₂O₂(μ-S)₂] (6-8). A tris-α-amino acid complex, [(leu)₂Mo₂O₂(μ-S)₂(μ-leu + H)] (5; leu + H is the carboxylate anion of l-leucine with the amine protonated), formed in the reaction with leucine. 5 crystallized from methanol with a third weakly bonded leucine as a bridging bidentate carboxylate. An adduct of 8 with SCN^- coordinated, 9, crystallized and was structurally characterized. Complexes 1-4 are air stable and highly water-soluble chiral molecules. Cytotoxicity studies in the A549 cell line gave IC₅₀ values that range from 80 to 400 μM. Cyclic voltammetry traces of 1-8 show solvent-dependent irreversible electrochemical behavior. Complexes 1-4 demonstrated the ability to catalyze the reaction of thiosulfate and cyanide in vitro to exhaustively transform cyanide to thiocyanate in less than 1 h.

Azure B as a novel cyanide antidote: Preclinical in-vivo studies

We have determined the effects of azure B (AzB), the main demethylated metabolite of methylene blue (MB), on a model of lethal cyanide intoxication. Our rationale was the following: AzB 1- possesses redox properties very similar to those of MB, which is a potent cyanide antidote, 2- may present a higher intracellular diffusibility than MB, 3- is already present in commercially available solutions of MB, and 4- appears very quickly in the blood after MB administration. AzB could therefore be a member of the phenothiazium chromophore family of interest to treat cyanide intoxication. We found, in spontaneously breathing urethane sedated rats, that AzB mimicked the effects of MB by increasing metabolism, ventilation and cardiac contractility up to 30-40 mg/kg. AzB had a lethal toxicity when the dose of 60 mg/kg was reached. Doses of AzB were therefore chosen in keeping with these data and the doses of MB previously used against cyanide intoxication (4-20 mg/kg) in the rat - doses corresponding to those used in humans to treat methemoglobinemia. KCN, infused at the rate of 0.375 mg/kg/min iv for 13 min, was fatal within 15 min in 100 % of our un-anesthetized rats. AzB at the dose of 4 mg/kg (n = 5) or 10 mg/kg (n = 5) administered 3 min into cyanide infusion allowed 100 % of the animals to survive with no clinical sequelae. The onset of coma was also significantly delayed and no apnea or gasping occurred. At the dose of 20 mg/kg, AzB was much less effective. At 4 mg/kg, the antidotal effects of AzB were significantly better than those produced by MB at the same dose and were not different from the effects produced by 20 mg/kg MB. We conclude that AzB is a potent cyanide antidote at relatively low doses.

Role of Hemodialysis in the Management of Cyanide Intoxication From Apricot Kernels in a 3-Year-Old Child

Cyanide (CN) is one among the most potent and rapidly acting lethal poisons, and it may cause death unless immediately diagnosed and treated. We report an unusual case of pediatric CN poisoning after ingestion of apricot kernels containing amygdalin, who survived with antidotal therapy and hemodialysis. A 3-year-old girl presented with respiratory distress and coma following tonic-clonic convulsions after ingestion of 3 apricot kernels. She had severe metabolic acidosis (pH 6.91, bicarbonate [HCO3] 5.6 mEq/L, base excess -26.0 mEq/L). Her blood CN level was measured 3.15 mg/L, 3 hours after ingestion. Hydroxocobalamin could not be administered immediately because it had to be brought from a medical center 4 hours apart. Therefore, a 3-hour hemodialysis session was carried out, following which she showed some clinical improvement. In addition, when hydroxocobalamin was obtained, it was then administered. During follow-up, she was completely asymptomatic with blood pressure, and other hemodynamic parameters normalized. This case presents hemodialysis as a way to correct metabolic derangements from CN poisoning and suggests that it may have a role in select cases of pediatric CN poisoning, especially when CN-scavenging antidotes may be unavailable.

Antidotal effects of methylene blue against cyanide neurological toxicity: in vivo and in vitro studies

The aim of the present study was to determine whether methylene blue (MB) could directly oppose the neurological toxicity of a lethal cyanide (CN) intoxication. KCN, infused at the rate of 0.375 mg/kg/min intravenously, produced 100% lethality within 15 min in unanaesthetized rats (n = 12). MB at 10 (n = 5) or 20 mg/kg (n = 5), administered 3 min into CN infusion, allowed all animals to survive with no sequelae. No apnea and gasping were observed at 20 mg/kg MB (P < 0.001). The onset of coma was also significantly delayed and recovery from coma was shortened in a dose-dependent manner (median of 359 and 737 seconds, respectively, at 20 and 10 mg/kg). At 4 mg/kg MB (n = 5), all animals presented faster onset of coma and apnea and a longer period of recovery than at the highest doses (median 1344 seconds, P < 0.001). MB reversed NaCN-induced resting membrane potential depolarization and action potential depression in primary cultures of human fetal neurons intoxicated with CN. MB restored calcium homeostasis in the CN-intoxicated human SH-SY5Y neuroblastoma cell line. We conclude that MB mitigates the neuronal toxicity of CN in a dose-dependent manner, preventing the lethal depression of respiratory medullary neurons and fatal outcome.

Diagnosis of acute intoxications in critically ill patients: focus on biomarkers - part 2: markers for specific intoxications

In medical intensive care units, acute intoxications contribute to a large proportion of all patients. Epidemiology and a basic overview on this topic were presented in part one. The purpose of this second part regarding toxicological biomarkers in the ICU setting focuses on specific poisons and toxins. Following the introduction of anion and osmol gap in part one, it's relevance in toxic alcohols and other biomarkers for these poisonings are presented within this publication. Furthermore, the role of markers in the blood, urine and cerebrospinal fluid for several intoxications is evaluated. Specific details are presented, amongst others, for cardiovascular drug poisoning, paracetamol (acetaminophen), ethanol, pesticides, ricin and yew tree intoxications. Detailed biomarkers and therapeutic decision tools are shown for carbon monoxide (CO) and cyanide (CN^-) poisoning. Also, biomarkers in environmental toxicological situations such as mushroom poisoning and scorpion stings are presented.

Update on hyperbaric oxygen therapy in burn treatment

Hyperbaric oxygen therapy (HBOT) has been shown to improve tissue hypoxia, neovascularization and ischemia reperfusion injury and reduce pathologic inflammation in various clinical settings and was proposed to be a game changer in treatment of burns. Improved and faster wound healing as well as a reduction of morbidity and mortality after thermal and concomitant carbon monoxide poisoning are expected. In defiance of the observed benefits for burn wounds and carbon monoxide poisoning in animal models and few randomized controlled trials there is an ongoing controversy regarding its use, indications and cost effectiveness. Furthermore, the use of HBOT, its indications and the evidence behind its efficiency are still widely unknown to most physicians involved in the treatment of burn patients. Therefore, a review of the up to date evidence-based literature was performed with a focus on available data of HBOT in burn care, to elaborate its use in acute thermal injury and carbon monoxide intoxication. Although beneficial effects of HBOT seem very likely insufficient evidence to support or disprove the routine use of HBOT in the treatment of burn care was found. Although difficult to carry out because of the high interindividual variability of burns and chronic wounds, the need for larger high-quality prospective randomized double-blinded controlled multicenter trials are necessary to be able to evaluate useful applications, expense and cost-efficiency of HBOT for burn care.

Carbon Monoxide and Cyanide Poisoning in the Burned Pregnant Patient: An Indication for Hyperbaric Oxygen Therapy

Carbon monoxide (CO) is a small molecule poison released as a product of incomplete combustion. Carbon monoxide binds hemoglobin, reducing oxygen delivery. This effect is exacerbated in the burned pregnant patient by fetal hemoglobin that binds CO 2.5- to 3-fold stronger than maternal hemoglobin. With no signature clinical symptom, diagnosis depends on patient injury history, elevated carboxyhemoglobin levels, and alterations in mental status. The standard of care for treatment of CO intoxication is 100% normobaric oxygen, which decreases the half-life of CO in the bloodstream from 5 hours to 1 hour. Hyperbaric oxygen (HBO2) is a useful adjunct to rapidly reduce the half-life of CO to 20 minutes and the incidence of delayed neurologic sequelae. Because of the slow disassociation of CO from hemoglobin in the fetus, there is a far stronger indication for HBO2 in the burned pregnant patient than in other burn patient populations.Cyanide intoxication is often a comorbid disease with CO in inhalation injury from an enclosed fire, but may be the predominant toxin. It acts synergistically with CO to effectively lower the lethal doses of both cyanide and CO. Diagnosis is best made in the presence of high lactate levels, carboxyhemoglobin concentrations greater than 10%, injury history of smoke inhalation from an enclosed fire, and alterations in consciousness. While treatment with hydroxocobalamin is the standard of care and has the effect of reducing concomitant CO toxicity, data indicate cyanide may also be displaced by HBO2.Carbon monoxide and cyanide poisoning presents potential complications impacting care. This review addresses the mechanism of action, presentation, diagnosis, and treatment of CO and cyanide poisonings in the burned pregnant patient and the use of HBO2 therapy.

Modest and variable efficacy of pre-exposure hydroxocobalamin and dicobalt edetate in a porcine model of acute cyanide salt poisoning

Background: Dicobalt edetate and hydroxocobalamin are widely used to treat hydrogen cyanide poisoning. However, comparative and quantitative efficacy data are lacking. Although post-exposure treatment is typical, it may be possible to administer these antidotes before exposure to first attenders entering a known site of cyanide release, as supplementary protection to their personal protective equipment.Methods: We established an anaesthetised Gottingen minipig model of lethal bolus potassium cyanide (KCN) injection to simulate high dose hydrogen cyanide inhalation. Doses were similar to human lethal doses of KCN. Dicobalt edetate and hydroxocobalamin were administered shortly before KCN and their effect on metabolic and cardiovascular variables and survival time were measured.Results: Increases in arterial lactate were similar after 0.08 and 0.12 mmol/kg KCN. KCN 0.08 mmol/kg was survived by 4/4 animals with moderate cardiovascular effects, while the 0.12 mmol/kg dose was lethal in 4/4 animals, with a mean time to euthanasia of 28.3 (SEM: 13.9) min. Administration of dicobalt edetate (0.021 mmol/kg, 8.6 mg/kg) or hydroxocobalamin (0.054 mmol/kg, 75 mg/kg) at clinically licenced doses had modest effect on lactate concentrations but increased survival after administration of KCN 0.12 mmol/kg (survival: dicobalt edetate 4/4, hydroxocobalamin 2/4) but not 0.15 mmol/kg (0/4 and 0/4, respectively). In a subsequent larger study, doubling the dose of hydroxocobalamin (0.108 mmol/kg, 150 mg/kg) was associated with a modest but inconsistent increased survival after 0.15 mmol/kg KCN (survival: control 0/8, 75 mg/kg 1/10, 150 mg/kg 3/10) likely due to variable pharmacokinetics.Conclusions: In this porcine study of cyanide exposure, with pre-exposure antidote administration, licenced doses of dicobalt edetate and hydroxocobalamin were effective at just lethal doses but ineffective at less than twice the estimated LD₅₀. The efficacy of a rapidly-administered double-dose of hydroxocobalamin was limited by variable pharmacokinetics. In clinical poisoning scenarios, with delayed administration, the antidotes are likely to be even less effective. New antidotes are required for treatment of cyanide exposures appreciably above the minimum lethal dose.

Antidotal Effects of the Phenothiazine Chromophore Methylene Blue Following Cyanide Intoxication

Our study was aimed at (1) determining the efficacy of the dye methylene blue (MB), following a rapidly lethal cyanide (CN) intoxication in un-sedated rats; (2) clarifying some of the mechanisms responsible for the antidotal properties produced by this potent cyclic redox dye. Sixty-nine awake rats acutely intoxicated by CN (IP, KCN 7 mg/kg) received saline, MB (20 mg/kg) or hydroxocobalamin (HyCo, 150 mg/kg) when in deep coma. Survival in this model was very low, reaching 9% at 60 min without any treatment. Methylene blue significantly increased survival (59%, p < .001) at 60 min, versus 37% with HyCo (p < .01). In addition, 8 urethane-anesthetized rats were exposed to a sublethal CN intoxication (KCN, 0.75 mg/kg/min IV for 4 min); they received MB (20 mg/kg, IV) or saline, 5 min after the end of CN exposure. All MB-treated rats displayed a significant reduction in hyperlactacidemia, a restoration of pyruvate/lactate ratio-a marker of NAD/NADH ratio-and an increase in CO2 production, a marker of the activity of the TCA cycle. These changes were also associated with a 2-fold increase in the pool of CN in red cells. Based on series of in vitro experiments, looking at the effects of MB on NADH, as well as the redox effects of MB on hemoglobin and cytochrome c, we hypothesize that the antidotal properties of MB can in large part be accounted for by its ability to readily restore NAD/NADH ratio and to cyclically re-oxidize then reduce the iron in hemoglobin and the electron chain complexes. All of these effects can account for the rapid antidotal properties of this dye following CN poisoning.

Theoretical study on the sensing mechanism of a fluorescence chemosensor for the cyanide anion

The sensing mechanism of the ratiometric fluorescence chemosensor 2-((6-(diethylamino)quinolin-2-yl)methylene)malononitrile (3A) for the cyanide anion (CN^-) has been investigated theoretically. The calculated results show that the small reaction barrier (8.58 kcal/mol) of 3A implies a rapid response speed to CN^-, and that the large interaction energy (25.75 kcal/mol) between 3A and CN^- indicates a high selectivity to CN^-. The results of condensed dual descriptor calculation confirm that CN^- attacks the C₂ site of 3A rather than other sites. The nucleophilic addition reaction of CN^- breaks the original conjugation structure of 3A and results in the redistribution of the charge. The frontier molecular orbitals (MOs) and the Hirshfeld population analysis demonstrate that the long-rang electronic transition between the diethylamino moiety and the dicyanovinyl group in 3A is cut off after the addition of CN^- and a local electronic transition between the quinoline and diethylamino moiety is formed. These changes lead to a blue shift (63 nm) of the fluorescence emission in the nucleophilic addition product (P) compare to 3A.

A novel long-alkyl-chained acylhydrazone-based supramolecular polymer gel for the ultrasensitive detection and separation of multianalytes

By rationally introducing multi-self-assembly driving forces and coordination binding sites into the same molecule, a designed functional gelator, G, was synthesized. Next, a novel supramolecular polymer material, OGV (1% DMSO), was constructed and used for the ultrasensitive detection and separation of multianalytes in gel states. Interestingly, OGV showed a fluorescent ultrasensitive response for the Hg2+ and Fe3+ ions in water. Moreover, by introducing these metal ions into the OGV, stable metal ion-coordinated supramolecular metallogels (HgG and FeG) were formed, which could sense CN- and H2PO4- in water with high selectivity and sensitivity.

Visual detection of cyanide ion in aqueous medium by a new chromogenic azo-azomethine chemosensor

A simple and new chromogenic azo-azomethine chemosensor N'-(5-((2,4-dichloro- phenyl) diazenyl)-2-hydroxylbenzylidene) picolinohydrazide (L) has been synthesized as an effective colorimetric sensor for cyanide ion. The sensing behavior of the probe L towards CN^- over other anions was examined by naked-eye, UV-vis spectroscopy and NMR studies. L exhibited a selective sensing ability to CN^- in DMSO/H₂O(6:4, v:v) binary solution and DMSO/Tris(10 mM, pH = 7.1, 6:4, v:v) buffer solution by changing color from colorless to yellow. The detection limit was calculated to be 6.4 μM. The recognition mechanism was attributed to deprotonation process according to ¹H NMR titration method. Moreover, test strips coated with L were easily fabricated with low cost and could be used to detect CN^- in aqueous solution conveniently.

An inhalational swine model for the characterization of physiological effects and toxicological profile associated with cyanide poisoning

Cyanides are highly toxic compounds that have been used as weapons of terrorism throughout history. Cyanide (CN) is acutely toxic by all routes of administration; however, inhalation is the main exposure route. To adequately test effective countermeasures against inhalational CN threats, robust and well-characterized animal models are needed. This paper describes the initial development of a hydrogen cyanide (HCN) exposure swine model for documenting the physiological effects and toxicological profile during and after HCN inhalation exposure. Animals were implanted with telemetry transmitters for heart rate (HR), blood pressure, and electrocardiogram monitoring, and vascular access ports for serial blood collections. Nine female swine were exposed to HCN concentrations of 500 ± 6 ppm while breathing parameters were monitored real-time. Inhaled HCN doses ranged from 2.02 to 2.83 mg/kg. Clinical signs included vocalization, agitation, salivation, respiratory distress and apnea. After HCN exposure initiation, systemic arterial pressure fell dramatically with a concomitant increase in HR. Blood samples were collected to determine CN blood levels using LC-MS/MS and blood gas analysis. In summary, the developed HCN inhalation swine model permitted documentation of the physiological effects associated with CN poisoning. This model could be used to evaluate potential CN medical countermeasures in the event of a public health emergency stemming from inhalational CN threats.

Carbon Nanotube Chemical Sensors

Carbon nanotubes (CNTs) promise to advance a number of real-world technologies. Of these applications, they are particularly attractive for uses in chemical sensors for environmental and health monitoring. However, chemical sensors based on CNTs are often lacking in selectivity, and the elucidation of their sensing mechanisms remains challenging. This review is a comprehensive description of the parameters that give rise to the sensing capabilities of CNT-based sensors and the application of CNT-based devices in chemical sensing. This review begins with the discussion of the sensing mechanisms in CNT-based devices, the chemical methods of CNT functionalization, architectures of sensors, performance parameters, and theoretical models used to describe CNT sensors. It then discusses the expansive applications of CNT-based sensors to multiple areas including environmental monitoring, food and agriculture applications, biological sensors, and national security. The discussion of each analyte focuses on the strategies used to impart selectivity and the molecular interactions between the selector and the analyte. Finally, the review concludes with a brief outlook over future developments in the field of chemical sensors and their prospects for commercialization.

Sensitive colorimetric detection of CN− and AcO− anions in a semi-aqueous environment through a coumarin–naphthalene conjugate azo dye

An efficient colorimetric chemosensor to detect anions in an aqueous medium.

Electron-deficient tripodal amide based receptor: An exclusive turn-on fluorescent and colorimetric chemo sensor for cyanide ion

Here in, we have designed, synthesized and isolated sensor L, as an exclusive selective turn-on fluorescent chemo sensor for cyanide ion. The acetonitrile solution contains L with tetrabutyl ammonium cyanide, results sudden color change from colorless to yellowish-brown. Chemosensor L produced a strong fluorescence response with an enhancement of very high fluorescence intensity while addition of CN^- ion and the strength of the chemosensor L towards cyanide binding is found to be 3.9813×10⁴M^-1. In order to use this sensor in practical application, we also prepared a cassette which is fabricated with sensor L and we succeeded to sense cyanide ion.

Oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor: Sensing ability, TD-DFT calculations and its application as an efficient solid state sensor

An oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor 3 T-2CN was reported. Sensor 3 T-2CN showed both naked-eye recognition and ratiometric fluorescence response for CN^- with an excellent selectivity and high sensitivity. The sensing mechanism based on the nucleophilic attack of CN^- on the vinyl CC bond has been successfully confirmed by the optical measurements, ¹H NMR titration, FT-IR spectra as well as the DFT/TD-DFT calculations. Moreover, the detection limit was calculated to be 0.19μM, which is much lower than the maximum permission concentration in drinking water (1.9μM). Importantly, test strips (filter paper and TLC plates) containing 3 T-2CN were fabricated, which could act as a practical and efficient solid state optical sensor for CN^- in field measurements.

Revisiting the physiological effects of methylene blue as a treatment of cyanide intoxication

BACKGROUND

Although methylene blue (MB) had long been proposed to counteract the effects of cyanide (CN) intoxication, research on its mechanisms of action and efficacy has been abandoned for decades. Recent studies on the benefits of MB in post-anoxic injuries have prompted us to reexamine the relevance of this historical observation.

METHODS

Our study was performed in adult male Sprague-Dawley rats and on HEK293T epithelial cells. First, the effects and toxicity of MB (0-80 mg/kg) on circulation and metabolism were established in four urethane-anesthetized rats. Then nine rats received a lethal infusion of a solution of KCN (0.75 mg/kg/min) and were treated by either saline or MB, at 20 mg/kg, a dose that we found to be innocuous in rat and to correspond to a dose of about 4 mg/kg in humans. MB was also administered 5 min after the end of a sub-lethal exposure to CN in a separate group of 10 rats. In addition, ATP/ADP ratio, ROS production, mitochondrial membrane potential (Δψm) and cellular O₂ consumption rate (OCR) were determined in HEK293T cells exposed to toxic levels of CN (200 µM for 10 min) before and after applying a solution containing MB (1-100 µM for 10 min).

RESULTS

Methylene blue was found to be innocuous up to 50 mg/kg. KCN infusion (0.75 mg/kg/min) killed all animals within 7-8 min. MB (20 mg/kg) administered at the same time restored blood pressure, cardiac contractility and limited O₂ deficit, allowing all the animals to survive, without any significant methemoglobinemia. When administered 5 min after a non-lethal CN intoxication, MB sped up the recovery of lactate and O₂ deficit. Finally, MB was able to decrease the production of ROS and restore the ATP/ADP ratio, Δψm as well as OCR of epithelial cells intoxicated by CN.

CONCLUSIONS

The present observations should make us consider the potential interest of MB in the treatment of CN intoxication. The mechanisms of the antidotal properties of MB cannot be accounted for by the creation of a cyanomethemoglobinemia, rather its protective effects appears to be related to the unique properties of this redox dye, which, depending on the dose, could directly oppose some of the consequences of the metabolic depression produced by CN at the cellular level.

Behavioral toxicity of sodium cyanide following oral ingestion in rats: Dose-dependent onset, severity, survival, and recovery

Sodium cyanide (NaCN) is a commonly and widely used industrial and laboratory chemical reagent that is highly toxic. Its availability and rapid harmful/lethal effects combine to make cyanide a potential foodborne/waterborne intentional-poisoning hazard. Thus, laboratory studies are needed to understand the dose-dependent progression of toxicity/lethality following ingestion of cyanide-poisoned foods/liquids. We developed an oral-dosing method in which a standard pipette was used to dispense a sodium cyanide solution into the cheek, and the rat then swallowed the solution. Following poisoning (4-128 mg/kg), overt toxic signs were recorded and survival was evaluated periodically up to 30 hours thereafter. Toxic signs for NaCN doses higher than 16 mg/kg progressed quickly from head burial and mastication, to lethargy, convulsions, gasping/respiratory distress, and death. In a follow-on study, trained operant-behavioral performance was assessed immediately following cyanide exposure (4-64 mg/kg) continuously for 5 h and again the following day. Onset of behavioral intoxication (i.e., behavioral suppression) occurred more rapidly and lasted longer as the NaCN dose increased. This oral-consumption method with concomitant operantbehavioral assessment allowed for accurate dosing and quantification of intoxication onset, severity, and recovery, and will also be valuable in characterizing similar outcomes following varying medical countermeasure drugs and doses.

A novel supramolecular AIE gel acts as a multi-analyte sensor array

Supramolecular gelator WJ could form a stable supramolecular organogel (WJG) with strong aggregation-induced emission (AIE). Utilizing the AIE gel, we successfully developed a multi-analyte sensor array which could accurately identify CN⁻, Al³⁺, and Fe³⁺ and l-Cys.

A reusable cyanide sensor via activation of C–H group: trifluoromethylcarbinol-directed meta-C–H cyanomethylation of naphthalimide

A fluorescent and colorimetric anion sensor based on the activated C–H group has been developed, and its reusability and ability to selectively detect cyanides have been demonstrated.

Case Files of the University of Massachusetts Toxicology Fellowship: Does This Smoke Inhalation Victim Require Treatment with Cyanide Antidote?

Cyanide toxicity is common after significant smoke inhalation. Two cases are presented that provide framework for the discussion of epidemiology, pathogenesis, presenting signs and symptoms, and treatment options of inhalational cyanide poisoning. An evidence-based algorithm is proposed that utilizes point-of-care testing to help physicians identify patients who benefit most from antidotal therapy.

Pediatric inhalation injury

Smoke inhalation injury can cause severe physiologic perturbations. In pediatric patients, these perturbations cause profound changes in cardiac and pulmonary physiology. In this review, we examine the pathology, early management options, ventilator strategy, and long-term outcomes in pediatric patients who have suffered a smoke inhalation injury.

A new azine derivative colorimetric and fluorescent dual-channel probe for cyanide detection

A novel azine derivative colorimetric and fluorescent dual-channel probe salicylaldehyde hydrazine-3,5-dibromosalicylaldehyde (1) has been designed, synthesized and characterized. The probe 1 is confirmed to have especial selectivity and good sensitivity on detecting CN^- via UV-vis absorption and fluorescence spectrum in aqueous solution (H₂O/DMSO, 1:4, v/v). This colorimetric and fluorescent dual-channel probe response to CN^- owed to the deprotonation process and established the mechanism by using ¹H NMR spectroscopy. Further researches showed that the detection limit of the probe 1 to CN^- anions is 8.01×10^-9M, significantly lower than the maximum level 1.9×10^-6M in potable water from WHO guidelines.