Recent advances in sensing toxic nerve agents through DMMP model simulant using diverse nanomaterials-based chemical sensors

Recent terrorist assaults have demonstrated the need for the exploration and design of sustainable and stable chemical sensors with quick reaction times combined with great sensitivity. Among several classes of chemical warfare agents, nerve agents have been proven to be the most hazardous. Even short-term exposure to them can result in severe toxic effects. Human beings inadvertently face the after-effects of these chemicals even several years after these chemicals were used. Due to the extreme toxicity and difficulty in handling, dimethyl methylphosphonate (DMMP), a simulant of nerve agents with much lesser toxicity, is frequently used in laboratories as a substitute. Having a chemical structure almost identical to those of nerve agents, DMMP can mimic the properties of nerve agents. Through this paper, authors have attempted to introduce the evolution of several chemical sensors used to detect DMMP in recent years, including field-effect transistors, chemicapacitors, chemiresistors, and mass-sensitive sensors. A detailed discussion of the role of nanomaterials as chemical sensors in the detection of DMMP has been the main focus of the work through a comprehensive overview of the research on gas sensors that have been reported making use of the properties of a wide range of nanomaterials.

Graphene-based nanomaterials as potential candidates for environmental mitigation of pesticides

Over the years, bioaccumulation of hazardous chemicals in the food chain has become a critical issue, resulting in numerous health risks. Environmental mitigation aims to clean up contaminated sites and eliminate hazardous materials from the air, water, or soil to restore the site to its original and safe condition. Pesticides constitute one of the most dangerous environmental pollutants which are generally used to increase crop production. Addressing the removal or treatment of pesticides has become pivotal in mitigating environmental threats. Diverse remediation methods are employed to protect the environment and public health. Graphene-based materials have emerged as promising candidates with exceptional properties, including excellent adsorption capacity due to their high surface area, strong hydrophilicity, and tunable properties. Owing to these properties, they have been attracting major research attention in the field of design and fabrication of materials for the mitigation of pesticides from the environment such as from contaminated food, water and other samples. Various physical, chemical and biological extraction techniques are adopted to remove pesticides. This review article provides an insight into the potential role of graphene-based materials in the environmental remediation of pesticides. We have focused on the removal of Organophosphates, Organochlorines, Carbamates and Pyrethroids present in water, fruit, vegetable and other samples, highlighting the urgent need for environmental remediation. While graphene-based materials hold potential for pesticide remediation, addressing challenges in scalable production, assessing long-term sustainability, and mitigating potential environmental impacts are critical steps for successful large-scale applications.

Unravelling groundwater contamination and health-related implications in semi-arid and cold regions of India

Groundwater, a vital global resource, is essential for sustaining life and various human activities. However, its quality and availability face increasing threats from both natural and human-induced factors. Widespread contamination, arising from both natural origins and human activities such as agriculture, industry, mining, improper waste disposal, and wastewater release, poses significant risks to human health and water security. India, known for its dense population and pronounced groundwater challenges, serves as a prominent case study. Notably, in most of its regions, groundwater resources have been found to be severely contaminated by various chemical, biological, and radioactive contaminants. This review presents an examination of contamination disparities across various states of semi-arid and cold regions, encompassing diverse assessment methods. The studies conducted in semi-arid regions of North, South, West, and East India highlight the consistent presence of fluorides and nitrates majorly, as well as heavy metals in some areas, with values exceeding the permissible limits recommended by both the Bureau of Indian Standards (BIS) and the World Health Organization (WHO). These contaminants pose skeletal and dental threats, methemoglobinemia, and even cancer. Similarly, in cold regions, nitrate exposure and pesticide residues, reportedly exceeding BIS and WHO parameters, pose gastrointestinal and other waterborne health concerns. The findings also indicated that the recommended limits of several quality parameters, including pH, electrical conductivity, total dissolved solids (TDS), total hardness, and total alkalinity majorly surpassed. Emphasising the reported values of the various contaminant levels simultaneously with addressing the challenges and future perspectives, the review unravels the complex landscape of groundwater contamination and its health-related implications in semi-arid and cold regions of India.

A comprehensive review on recent advances toward sequestration of levofloxacin antibiotic from wastewater

Among various classes of antibiotics, fluoroquinolones, especially Levofloxacin, are being administered on a large scale for numerous purposes. Being highly stable to be completely metabolized, residual quantities of Levofloxacin get accumulated into the food chain proving a great global threat for aquatic as well as terrestrial ecosystems. Various removal techniques including both conventional and advanced methods have been reported for this purpose. This review is a novel attempt to make a critical analysis of the recent advances made exclusively toward the sequestration of Levofloxacin from wastewater through an extensive literature survey (2015-2021). Adsorption and advanced oxidation processes especially photocatalytic degradation are the most tested techniques in which assorted nanomaterials play a significant role. Several photocatalysts exhibited up to 100% degradation of LEV which makes photocatalytic degradation the best method among other tested methods. However, the degraded products need to be further monitored in terms of their toxicity. Biological degradation may prove to be the most environment-friendly with the least toxicity, unfortunately, not much research is reported in the field. With these key findings and knowledge gaps, authors suggest the scope of hybrid techniques, which have been experimented on other antibiotics. These can potentially minimize the disadvantages of the individual techniques concurrently improving the efficiency of LEV removal. Besides, techniques like column adsorption, membrane treatment, and ozonation, being least reported, reserve good perspectives for future research. With these implications, the review will certainly serve as a breakthrough for researchers working in this field to aid their future findings.

Guar gum based nanocomposites: Role in water purification through efficient removal of dyes and metal ions

Researchers nowadays are relentlessly on a race exploring sustainable materials and techniques for the sequestration of toxic dyes and metal ions from water bodies. Biopolymers such as guar gum, owing to its high abundance, low cost and non-toxicity, are potential candidates in this field. Plenty of hydroxyl groups in the polymer backbone enable guar gum to be functionalised or grafted in a versatile manner proving itself as an excellent starting substance for fabricating upgraded materials meant for diverse applications. This review offers a comprehensive coverage of the role of guar gum-based nanocomposites in removal of dyes and heavy metal ions from waste water through adsorption and photo-catalytic degradation. Isotherm and kinetics models, fabrication routes, characterisation techniques, swelling properties and reusability as well as adsorption and degradation mechanisms are outlined. A detailed analysis with convincing results suggests a good future perspective of implementation of these materials in real-time wastewater treatment technology.

The selection of wild-type revertants from methotrexate permeability mutants

In a previous report, we described the selection and partial characterization of three distinct classes of methotrexate (Mtx)-resistant Chinese hamster ovary cells (CHO) (1). Class I cells contained a structural alteration in dihydrofolate reductase. Class II cells showed a alteration affecting the permeability of the drug. Class III cells, selected from class I cells, had an increased activity of the altered enzyme. In the work described here, the sensitivity of these lines to the diaminopyrimidines has been investigated. Class I cells are as sensitive, class II cells are 5- to 10-fold more sensitive, and class III cells are 10- to 30-fold more resistant than wild-type cells. The increased sensitivity of the class II cells provided an opportunity to select for revertants of these mutants and such phentotypic wild-type revertant cells have been selected using one diaminopyrimidine, pyrimethamine. Such cells have drug sensitivities and permeability characteristics similar to wild-type cells. A second class has been identified which has wild-type drug sensitivities to the diaminopyrimidines but Mtx class II resistance to Mtx, and drug permeabilities characteristic of Mtx-resistant class II cells.