Copper Complex-Embedded Vesicular Receptor for Selective Detection of Cyanide Ion and Colorimetric Monitoring of Enzymatic Reaction

Nanoparticles Based Sensors for Cyanide Ion Sensing, Basic Principle, Mechanism and Applications

Rapidly detecting potentially toxic ions such as cyanide is paramount to maintaining a sustainable and environmentally friendly ecosystem for living organisms. In recent years, molecular sensors have been developed to detect cyanide ions, which provide a naked-eye or fluorometric response, making them an ideal choice for cyanide sensing. Nanosensors, on the other hand, have become increasingly popular over the last two decades due water solubility, quick reaction times, environmental friendliness, and straightforward synthesis. Researchers have designed many nanosensors and successfully utilized them for the detection of cyanide ions in various environmental samples. The majority of these sensors use gold and silver-based nanosensors because cyanide ions have a high affinity for these metals ions and coordinate through covalent bonds. These metal nanoparticles are typically combined or coated with fluorescent materials, which quench their fluorescence. However, adding cyanide ions etches out the metal nanoparticles, restoring their fluorescence/color. This principle has been followed by most nanosensors used for cyanide ion sensing. In this review, different nanosensors and their sensing mechanisms are discussed in relation to cyanide ions. The primary purpose is to compare the sensing abilities of these sensors, mainly their sensitivity, advantages, application and to find out research gaps for future work. In this review paper, the development made in nanosensors in the last thirteen years (2010-2023) was discussed and the nanosensors for cyanide ions were compared with molecular sensors while the nanosensors with the excellent limit of detection were highlighted.

Liposome Based Near-Infrared Sensors for the Selective Detection of Hydrogen Sulfide

Cyanine dye-based new amphiphilic compound NIR-Amp has been synthesised. NIR-Amp was embedded with phospholipids DOPC and DPPC to form liposomes based nanoscale chemical sensors NIR-Lip1 and NIR-Lip2. Here, two different phospholipids were used to demonstrate the influence of lipid structure, composition and fluidity on sensing of nanosensors. Both the probes show NIR absorption maximum at 790 nm and emission maximum at 815 nm. H2 S-triggered thiolation resulted a remarkable change in color from green to pale yellow. A decrease in UV-Vis absorption and emission in the NIR region was observed only with H2 S. NIR-Lip1 and NIR-Lip2 are highly selective for H2 S with a LOD of 0.57 μM and 1.24 μM, respectively. It was observed that in a solid-like gel state, NIR-Lip1 is slightly more sensitive towards H2 S than fluid-like NIR-Lip2. The H2 S sensing mechanism was confirmed by ESI-mass and infrared (IR) spectroscopic analysis. Based on the high sensitivity and selectivity, NIR-Lip1 was employed to detect H2 S in vegetable samples. Further, the probes are found to be non-toxic and established for H2 S fluorescence imaging in live cells.

Multi analyte sensing of amphiphilic tridentate bis(benzimidazolyl)pyridine incorporated in liposomes and potential application in enzyme assay

A liposome based nanosensor Lipo-1 for efficient detection of copper, cyanide (CN^-) and ATP in a pure aqueous medium has been described. Lipo-1 shows a fluorescence ON-OFF response with copper. However, Lipo-1.Cu (Lipo-1 and copper ensemble) was used for the OFF-ON detection of ATP with nM and CN^- with μM detection levels, lower than the WHO permissible level for safe drinking. Lipo-1 has better and enhanced binding properties over the counter organic amphiphilic compound Bzimpy-LC, which is not soluble in water. The significant changes in the emission spectra in the presence of Cu²⁺, CN^- and ATP ions, as variable inputs, are used to construct INHIBIT and OR logic operations in a nano-scale environment. The fluorescent detection of CN^- ions with Lipo-1.Cu was used to develop an enzyme assay for β-glucosidase using amygdalin as the substrate. β-Glucosidase enzymatic activity was monitored by the emission OFF-ON signal of the probe Lipo-1.Cu by CN^- detection. This approach could be an efficient method for developing a fluorescence-based β-glucosidase enzyme assay. A switch ON luminescence response, low detection limit, fast response, 100% aqueous solution, biocompatibility, multi-analyte detection, and improved sensitivity and selectivity of Bzimpy-LC in lipid bilayer membranes are the main features of the nanoprobe Lipo-1. These properties give it a clear advantage for analytical applications.

Recent Development in Coordination Compounds as a Sensor for Cyanide Ions in Biological and Environmental Segments

Rapid detection of toxic ions has taken great attention in the last few decades due to its importance in maintaining a greener environment for human beings. The extreme toxicity of cyanide (CN-) ions is a great environmental concern as its continued industrial use generates interest in facile and sensitive methods for CN- ions detection. Since CN- ions act as a ligand in coordination chemistry which rapidly coordinates with suitable metals and forms complexes, this ability was mainly explored in its detection. It also attacks the central metal in coordination compounds and gives a fluorimetric response. Coordination compounds behave as a sensor for the detection of important ions like CN- ions and have gained great attention due to their facile synthesis, multianalyte detection, clear detection and low detection limit. Recently, considerable efforts have been devoted to the detection and quantification of hazardous multianalyte using a single probe. Cu2+ complexes are the main complexes used for CN- ions detection; however, the complexes of many other metals are also used as sensors. Four basic types of interaction have been discussed in coordination compound sensors for CN- detection. The performances of different sensors are compared with one another and the sensors which have the lowest detection limit are highlighted. This review comprises the progress made by coordination compounds as sensors for the detection of CN- ions in the last six years (2015-2021). To the best of our knowledge, there is no review on coordination compounds as a sensor for CN- ions during this period. [Figure: see text].

Cucurbit[8]uril-Assisted Nucleophilic Reaction: A Unique Supramolecular Approach for Cyanide Detection and Removal from Aqueous Solution

A unique supramolecular approach of preparing and using a cucurbit[8]uril (Q[8])-based dynamic host-guest assembly for cyanide sensing in and removal from water has been successfully developed. The dicyanovinyl-attached cationic guest (1) was designed as the fluorescent response moiety for the detection of the cyanide anion via a nucleophilic addition reaction in the assist of the Q[8]-based 2:2 quaternary complexes. Furthermore, the reaction of cyanide with 1 further switched the Q[8]-based host-guest assemblies from the 2:2 complexes to the 1:1 supramolecular polymers that precipitate in water. Thus, the macrocyclic-based dynamic host-guest assembly has potential use in applications for solving the problem of toxic anion pollutants present in aqueous environments.

Fluorene Based Ferric Complex as Colorimetric and Fluorometric Probe for Highly Selective Detection of CN- and S2- Anions

A series of new chemosensor molecules bearing benzothiazole-, quinoline- and phthalazine-functionalized fluorene derivatives were synthesized and their complexation behaviors with Fe³⁺ and Sn²⁺ ions were investigated. The sensing abilities of their complexes towards both cyanide and sulfide anions were investigated by colorimetric and fluorometric techniques in detail. The sensing mechanism was investigated by Job's and Scatchard plots evaluations, and also absorption/fluorescence titration experiments. Among the studied dye/metal binary systems, F-BT sensor to Fe³⁺ giving the detection limits of 3.1 µg has also displayed high selectivity and sensitivity towards CN^- and S^2- anions, lead to a significant color change of the solution observable by the naked eye.

Eco-friendly chitosan Schiff base as an efficient sensor for trace anion detection

Herein, a chitosan Schiff base sample (CSAN) was strategically designed and prepared via a two-step process. In the first step, an azo derivative of 1- naphthylamine namely, [2-hydroxy-5-(naphthalene-1-yldiazenyl) benzaldehyde] (HNDB) was synthesized as an aldehyde moiety. Then the condensation reaction of HNDB with chitosan afforded CSAN as the target product. Structural analyses of synthesized material were accomplished through FT-IR, ¹H NMR, UV-Vis, XRD, TGA, and SEM spectral methods. Meanwhile, the heterogeneous CSAN was able to detect the presence of hydrogen carbonate (HCO₃^-), acetate (AcO^-), and cyanide (CN^-) anions in semi-aqueous media (H₂O/DMSO; 10:90%, v/v). Moreover, the selectivity of CSAN towards CN^- anion was increased through variation in solvent mixture ratios. Thereupon, CSAN was explored as a promising sensor towards CN^- anion in an aqueous media through considerable color variation from colorless to pale yellow as well as quantitative chemical analysis. Overall, reliable CSAN chemosensor with high sensitivity for mentioned anions has a pivotal role in practical applications owing to it's reversibility ability.

Controllable and reversible sensing cyanide ion using dual-functional Cu(II)-based ensemble

In this work, a dual-functional Cu²⁺-based ensemble (2S·Cu²⁺) was well designed and characterized. Then, the successional and discriminating sensing for CN^- over other competitive species (H₂PO₄^- and biothiols) was achieved based on the disaggregation of 2S·Cu²⁺ ensemble and the deprotonation of imidazole NH of regenerated sensor S in aqueous solution, respectively. The visual sensing mechanism could be clearly demonstrated by ¹H NMR, HRMS and energy changes between the HOMO-LUMO band gaps. Furthermore, the reversibility and reusability of S and 2S·Cu²⁺ upon alternating addition of CN^-/H⁺ and CN^-/Cu²⁺ were studied. Interestingly, the sequential sensing for biothiols (cysteine, glutathione and homocysteine) and CN^- was also realized through spectroscopic methodology and test paper strips. This work may provide a feasible strategy to discriminate CN^- over H₂PO₄^- and biothiols with high selectivity and sensitivity through Cu²⁺-based ensembles.

Supramolecular AIE polymer-based rare earth metallogels for the selective detection and high efficiency removal of cyanide and perchlorate

Two novel supramolecular AIE polymer-based rare earth metallogels (PT-GEu and PT-GTb) have been rationally designed and synthesized for the efficient detection and removal of cyanide (CN⁻) and perchlorate (ClO₄⁻).

Chemosensing of neurotransmitters with selectivity and naked eye detection of l-DOPA based on fluorescent Zn(ii)-terpyridine bearing boronic acid complexes

A new range of fluorescent Zn(ii)-terpyridine complexes are described and studied in-depth as chemosensors for catecholamine-based neurotransmitters in pure water.

A fluorescent supramolecular gel and its application in the ultrasensitive detection of CN- by anion-π interactions

Supramolecular gels have been widely reported on account of their unique superiority and application prospects. In this work, we constructed a novel supramolecular gel (HD-G) by using hydroxy-naphthaldehyde decorated with naphthalimide in DMSO solution, which exhibited excellent selectivity and ultrasensitive sensing properties toward CN^- (the lowest detection limit is 1.82 × 10^-10 M). The sensing mechanism of this supramolecular gel takes advantage of π-π stacking interactions and anion-π interactions, which is different from the other familiar methods.