Benzimidazolium-Based Self-Assembled Fluorescent Aggregates for Sensing and Catalytic Degradation of Diethylchlorophosphate

A high-performance Calix@ZnO based bifunctional nanomaterial for selective detection and degradation of toxic azinphos methyl in environmental samples

One of the key tenets of sustainable agriculture and food safety is the removal of toxic pesticides from the environment. However, developing reliable, affordable, and efficient methods for detecting and degrading pesticides into non-toxic degradable products remains an immediate matter of concern. Herein, we attempt to develop a strategy for the detection as well as degradation of highly toxic phosphorodithioate pesticide, Azinphos methyl (AZM), using hybrid zinc oxide nanoparticles (ZnO NPs). Considering the non-selectivity of bare ZnO and receptor R1, we have fabricated the heterocalixarene-based Calix (R1) over zinc oxide (ZnO) surface in situ via the sol-gel process. The synthesized heterocaliaxrene-modified ZnO (R1@ZnO) NPs show an excellent affinity for the selective and sensitive detection of AZM with a tremendously low limit of detection (68 mg L^-1) and no interference from other pesticides. Degradation of AZM was fully supported by fluorescence spectroscopy, scanning electron microscopy (SEM), ¹H NMR titrations, FTIR spectroscopy, cyclic voltammetry, and mass spectroscopy, which unequivocally confirmed the formation of non-toxic products. According to our findings, R1@ZnO NPs are sustainable nanomaterials that can be employed for environmental remediation since they operate in an aqueous medium.

Organic Cation Receptor for Colorimetric Lateral Flow Device: Detection of Zearalenone in Food Samples

As per the WHO reports, it has been estimated that almost 25% of food crops contain mycotoxins as the major contaminant. In this work, we developed a paper-based colorimetric lateral flow device (CLFD) impregnated with an organic cation receptor (OCR) for sensitive and selective detection of zearalenone (ZEN). Various techniques such as ultraviolet (UV)-visible absorption, cyclic voltammetry, and fluorescence spectroscopy were used for the detection of mycotoxins, and it was observed that OCR shows sensitivity and selectivity toward zearalenone (ZEN) only, irrespective of any other analytes. Furthermore, the colorimetric test revealed that the developed OCR shows a change in color with the addition of ZEN from greenish-gray to blue that is visible to the naked eye. The quantification of ZEN was also achieved using RGB analysis and compared with UV-visible spectroscopy data. Further, for the on-site detection of ZEN, a paper-based CLFD was also developed and used to evaluate the spiked corn sample containing ZEN, and it provided significant results with a limit of detection (LOD) of 0.31 nM (3σ method), good linearity (R² = 0.9702), good reproducibility (SD = ±6%, triplicate), and good recovery of ZEN of 95-102% with a variation coefficient (VC) varying from 1.56 to 4.62%. Therefore, the device has the potential to check the mycotoxin toxicity in food products and is helpful in remote and developing areas.

Lighting up forensic science by aggregation-induced emission: A review

Forensic science requires a fast, sensitive, and anti-interfering imaging tool for on-site investigation and bio-analysis. The aggregation-induced emission (AIE) phenomenon exhibits remarkable luminescence properties (large Stokes shift, diverse molecular structures, and high photo-stability), which can provide a viable solution for on-site analysis, while at the same time overcoming the problem of aggregation-caused quenching (ACQ). Based on the outstanding performance in chemical analysis and bio-sensing, AIE materials have great prospects in the field of forensic science. Therefore, the application of AIE in forensic science has been summarized for the first time in this article. After a brief introduction to the concept and development of AIE, its applications in the determination of toxic or hazardous substances, based on data on poisoning deaths, has been summarized. Subsequently, besides the bio-imaging function, other applications of AIE in analyzing markers related to forensic genetics, forensic pathology, (focusing on the corpse) and clinical forensics (focusing on the living) have been discussed. In addition, applications of AIE molecules in criminal investigations, including recognition of fingerprints and blood stains, detection of explosives and chemical warfare agents, and anti-counterfeiting have also been presented. It is hoped that this review will light up the future of forensic science by stimulating more research work on the suitability of AIE materials in advancing forensic science.

Catalytic Degradation of Nerve Agents

Nerve agents (NAs) are a group of highly toxic organophosphorus compounds developed before World War II. They are related to organophosphorus pesticides, although they have much higher human acute toxicity than commonly used pesticides. After the detection of the presence of NAs, the critical step is the fast decontamination of the environment in order to avoid the lethal effect of these organophosphorus compounds on exposed humans. This review collects the catalytic degradation reactions of NAs, in particular focusing our attention on chemical hydrolysis. These reactions are catalyzed by different catalyst categories (metal-based, polymeric, heterogeneous, enzymatic and MOFs), all of them described in this review.

Ionic Liquid-Functionalized Multiwalled Carbon Nanotube-Based Hydrophobic Coatings for Robust Antibacterial Applications

In recent years, the biomimetic superhydrophobic coatings have received tremendous attention, owing to their potential in fabricating self-cleaning surfaces, in environmental applications. Consequently, extensive research has been devoted to create a superhydrophobic surface using the oxidized derivatives of CNTs and graphene. Thus, the design and development of a self-cleaning/superhydrophobic surface with good biocompatibility are an effective approach to deal with the bacterial infections related to biomedical devices used in hospitals. In this context, herein, we have developed the material based on ionic liquid (IL)-functionalized multiwalled carbon nanotubes (MWCNTs) for hydrophobic coatings, which was fully characterized with various techniques such as Fourier transform infrared, powder X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. We have evaluated the synthesized ILs for their antibacterial potential against the pathogenic bacterial strains such as Gram-positive (Staphylococcus aureus and methicillin-resistant S. aureus) and Gram-negative (Escherichia coli) bacterial strains. Further, atomic force and scanning electron microscopic studies have been performed to investigate the morphological changes to unravel the mechanism of action, whereas DNA binding study indicates the binding of IL-1d@MWCNT with DNA (K_a = 2.390 × 10⁴ M^-1). Furthermore, the developed material (IL-1d@MWCNT) is coated onto the surface of polyvinyl chloride (PVC) and evaluated for hydrophobicity through water contact angle measurements and possesses long-term antibacterial efficiency against both under-investigating pathogenic strains. For the biocompatibility assay, the obtained coated PVC material has also been evaluated for its cytotoxicity, and results reveal no toxicity against viable cells. These all results are taken together, indicating that by coating with the developed material IL-1d@MWCNT, a robust self-sterilizing surface has achieved, which helps in maintaining a bacteria-free surface.

Self-assembly of imidazolium/benzimidazolium cationic receptors: their environmental and biological applications

This review highlights the applications of imidazolium based cationic receptors for sensing of biomolecules and catalysis.

IL@CQD catalyzed active ester rearrangement for the detection and removal of cyanide ions

Recognition of cyanide ion with IL@CQDs catalyzed rearranged product.

Metal-Organocatalyst for Detoxification of Phosphorothioate Pesticides: Demonstration of Acetylcholine Esterase Activity

In recent years, transition metal complexes have been developed for catalytical degradation of a phosphate ester bond, particularly in RNA and DNA; however, less consideration has been given for development of complexes for the degradation of a phosphorothioate bond, as they are the foremost used pesticides in the environment and are toxic to human beings. In this context, we have developed copper complexes of benzimidazolium based ligands for catalytical degradation of a series of organophosphates (parathion, paraoxon, methyl-parathion) at ambient conditions. The copper complexes (assigned as N1-N3) were characterized using single X-ray crystallography which revealed that all three complexes are mononuclear and distorted square planner in geometry. Further, the solution state studies of the prepared complexes were carried out using UV-visible absorption, fluorescence spectroscopy, and cyclic voltametry. The complexes N1 and N2 have benzimidazolium ionic liquid as base attached with two 2-mercapto-benzimidazole pods, whereas complex N3 contains a nonionic ligand. The synthesized copper complexes were evaluated for their catalytic activity for degradation of organophosphates. It is interesting that the complex containing the ionic ligand efficiently degrades phosphorothioate pesticides, whereas complex N3 was not found to be appropriate for degradation due to a weaker conversion rate. The organophosphate degradation studies were monitored by recording absorbance spectra of parathion in the presence of catalyst, i.e., copper complexes with respect to time. The parathion was hydrolyzed into para-nitrophenol and diethyl thiophosphate. Moreover, to analyze the inhibition activity of the pesticides toward acetylcholine esterase enzyme in the presence of prepared metal complexes, Ellman's assay was performed and revealed that, within 20 min, the inhibition of acetylcholine esterase enzyme decreases by up to 13%.

Surfactant Aggregates Encapsulating and Modulating: An Effective Way to Generate Selective and Discriminative Fluorescent Sensors

The heterogeneous structure and dynamic balancing nature of surfactant aggregates make them attractive in developing fluorescent sensors. They can provide a number of advantages, e.g., enhanced fluorescence stability and quantum yield, detection capability in aqueous solutions, and easy operation. Thus, various strategies have been used to construct surfactant aggregate-based fluorescent sensors. Surfactant aggregates play various roles in different strategies and realize multiple sensing behaviors. Many new functions have been discovered for surfactant aggregates in constructing fluorescent sensors. In this feature article, we briefly summarize the development of surfactant aggregate-based fluorescent sensors and their applications in three different types of sensing: selective sensing, multiple analyte sensing, and cross-reactive sensing. For each type of sensing, the design strategies and the roles of surfactant aggregates are particularly introduced. An understanding of these aspects will help to expand the applications of surfactant assemblies in the sensing field.

Cobalt complexes of Biginelli derivatives as fluorescent probes for selective estimation and degradation of organophosphates in aqueous medium

Bonding between metal complexes of Biginelli derivatives and organophosphates leads to enhancement of emission intensity.