Engineered tenorite structure of barium-enriched copper oxide for on-site monitoring of cytotoxic methotrexate in environmental samples

Electrochemical sensor for selective diquat detection based on samarium-stannate-nanoparticle-anchored titanium aluminum carbide MXene nanocomposites

The persistent presence of diquat (DQ) residue poses a significant threat to human health, underscoring the need to monitor DQ levels in agricultural samples. This is crucial for both precision and post-harvest agriculture, which require non-destructive, rapid, and cost-effective analytical methods using electrochemical detection. We developed a novel nanocomposite, composed of samarium stannate (Sm2Sn2O7) nanoparticles anchored on an MXene (Ti3Al(1-x)C2-OH(x); TAC-1), for the electrochemical quantification of DQ. A three-dimensional titanium aluminum carbide MXene surface was hydroxylated and functionalized with Sm2Sn2O7 nanoparticles using a combustion method. The resulting heterogeneous TAC-1-Sm2Sn2O7 composite contained active sites that enabled selective and sensitive DQ detection owing to the synergistic effects of the enhanced electrocatalytic sites and rapid charge transfer. Under real-world conditions, a TAC-1-Sm2Sn2O7-modified screen-printed carbon electrode sensor exhibited outstanding electrochemical activity toward DQ, with good recovery (98 %) from prepared samples. Hence, the designed sensor electrode is well suited for DQ monitoring.

Biological and green remediation of heavy metal contaminated water and soils: A state-of-the-art review

Contamination of the natural ecosystem by heavy metals, organic pollutants, and hazardous waste severely impacts on health and survival of humans, animals, plants, and microorganisms. Diverse chemical and physical treatments are employed in many countries, however, the acceptance of these treatments are usually poor because of taking longer time, high cost, and ineffectiveness in contaminated areas with a very high level of metal contents. Bioremediation is an eco-friendly and efficient method of reclaiming contaminated soils and waters with heavy metals through biological mechanisms using potential microorganisms and plant species. Considering the high efficacy, low cost, and abundant availability of biological materials, particularly bacteria, algae, yeasts, and fungi, either in natural or genetically engineered (GE) form, bioremediation is receiving high attention for heavy metal removal. This report comprehensively reviews and critically discusses the biological and green remediation tactics, contemporary technological advances, and their principal applications either in-situ or ex-situ for the remediation of heavy metal contamination in soil and water. A modified PRISMA review protocol is adapted to critically assess the existing research gaps in heavy metals remediation using green and biological drivers. This study pioneers a schematic illustration of the underlying mechanisms of heavy metal bioremediation. Precisely, it pinpoints the research bottleneck during its real-world application as a low-cost and sustainable technology.

In-situ formation of niobium oxide – niobium carbide – reduced graphene oxide ternary nanocomposite as an electrochemical sensor for sensitive detection of anticancer drug methotrexate

Engineering the nanostructure of an electrocatalyst is crucial in developing a high-performance electrochemical sensor. This work exhibits the hydrothermal followed by annealing synthesis of niobium oxide/niobium carbide/reduced graphene oxide (NbO/NbC/rGO) ternary nanocomposite. The oval-shaped NbO/NbC nanoparticles cover the surface of rGO evenly, and the rGO nanosheets are interlinked to produce a micro-flower-like architecture. The NbO/NbC/rGO nanocomposite-modified electrode is presented here for the first time for the rapid and sensitive electrochemical detection of the anticancer drug methotrexate (MTX). Down-sized NbO/NbC nanoparticles and rGO's high surface area provide many active sites with a rapid electron transfer rate, making them ideal for MTX detection. In comparison to previously reported MTX sensors, the developed drug sensor exhibits a lower oxidation potential and a higher peak current responsiveness. The constructed sensors worked analytically well under optimal conditions, as shown by a low detection limit of 1.6 nM, a broad linear range of 0.1-850 µM, and significant recovery findings (∼98 %, (n = 3)) in real samples analysis. Thus, NbO/NbC/rGO nanocomposite material for high-performance electrochemical applications seems promising.