A rhodamine based nanosensor platform for Hg2+ sensing in near–perfect aqueous medium: Smartphone, test strip and real sample applications

A Novel Rhodamine Probe Acting as Chemosensor for Selective Recognition of Cu2+ and Hg2+ Ions: An Experimental and First Principle Studies

Copper and Mercury ions have vital role to play in biological world as their excess or deficiency can cause different type of diseases in human being as well as biological species including plants and animals. Therefore, their detection at trace level becomes very important in term of biological. The current studies embody the fabrication, structural characterization and recognition behavior of a novel rhodamine B hydrazone formed when hydrazide of rhodamine B was condensed with 5-Allyl-3-methoxy salicylaldehyde (RBMA). RBMA was found to be responsive towards the very trace level of Cu2+ and Hg2+ among other tested cations so far. The sensing procedure is based on the classical opening of the spiroatom ring of rhodamine. The limit of detection (LOD) and binding constant is 5.35 ppm, 2.06 × 104 M-1 and 5.16 ppm, 1.26 × 104 M-1 for Cu2+ and Hg2+ ions respectively. The probable mechanism correlates the specific binding of RBMA with Cu2+ and Hg2+ ions. The 1:1 stoichiometry of RBMA with Cu2+ and Hg2+ ions have been supported by HRMS, FT-IR data, Job's plot, and binding constant data. Reversibility is well exhibited by RBMA by the involvement of CO32- ions via demetallation process. The real time application is well demonstrated by the use of paper strip test. The DFT study also carried out which agrees well with the experimental findings. The results displayed the novelty of this current work towards the trace level analysis of the Cu2+ and Hg2+ of the cations which are play the crucial role in industry.

Captivating nano sensors for mercury detection: a promising approach for monitoring of toxic mercury in environmental samples

Mercury, a widespread highly toxic environmental pollutant, poses significant risks to both human health and ecosystems. It commonly infiltrates the food chain, particularly through fish, and water resources via multiple pathways, leading to adverse impacts on human health and the environment. To monitor and keep track of mercury ion levels various methods traditionally have been employed. However, conventional detection techniques are often hindered by limitations. In response to challenges, nano-sensors, capitalizing on the distinctive properties of nanomaterials, emerge as a promising solution. This comprehensive review provides insight into the extensive spectrum of nano-sensor development for mercury detection. It encompasses various types of nanomaterials such as silver, gold, silica, magnetic, quantum dot, carbon dot, and electrochemical variants, elucidating their sensing mechanisms and fabrication. The aim of this review is to offer an in-depth exploration to researchers, technologists, and the scientific community, and understanding of the evolving landscape in nano-sensor development for mercury sensing. Ultimately, this review aims to encourage innovation in the pursuit of efficient and reliable solutions for mercury detection, thereby contributing to advancements in environmental protection and public health.

Field method for preservation of total mercury in waters, including those associated with artisanal scale gold mining

Analysis of mercury (Hg) in natural water samples has routinely been impractical in many environments, for example, artisanal and small-scale gold mines (ASGM), where difficult conditions make monitoring of harmful elements and chemicals used in the processes highly challenging. Current sampling methods require the use of hazardous or expensive materials, and so difficulties in sample collection and transport are elevated. To solve this problem, a solid-phase extraction-based method was developed for the sampling and preservation of dissolved Hg in natural water samples, particularly those found around ASGM sites. Recoveries of 85% ± 10% total Hg were obtained during 4 weeks of storage in refrigerated (4 °C, dark) and unrefrigerated (16 °C, dark) conditions, and from a representative river water spiked to 1 μg L-1 Hg2+, 94% ± 1% Hg recovery was obtained. Solid-phase extraction loading flow rates were tested at 2, 5, and 10 mL min-1 with no breakthrough of Hg, and sorbent stability showed no breakthrough of Hg up to 2 weeks after functionalisation. The method was deployed across five artisanal gold mines in Kakamega gold belt, Kenya, to assess Hg concentrations in mine shaft water, ore washing ponds, and river and stream water, including drinking water sources. In all waters, Hg concentrations were below the WHO guideline limit value of 6 μg L-1, but drinking water sources contained trace concentrations of up to 0.35 μg L-1 total Hg, which may result in negative health effects from long-term exposure. The SPE method developed and deployed here is a robust sampling method that can therefore be applied in future Hg monitoring, toxicology, and environmental work to provide improved data that is representative of total dissolved Hg in water samples.

A methionine biomolecule-modified chromenylium-cyanine fluorescent probe for the analysis of Hg2+ in the environment and living cells

The objective of the study is, for the first time, to construct a new near infrared (NIR) fluorophore, spectrophotometric, colorimetric, ratiometric, and turn-on probe (CSME) based on chromenylium cyanine platform decorated with methionine biomolecule to provide an efficient solution for critical shortcoming to be encountered for analysis of hazardous Hg²⁺ in environment and living cell. The CSME structure and its interaction with Hg²⁺ ion were evaluated by NMR, FTIR, MS, UV-Vis and fluorescence methods as well as Density Functional Theory (DFT) calculations. The none fluorescence CSME having spirolactam ring only interacted with Hg²⁺ in aqueous solution including competing ions. This interaction caused the fluorescence CSME with opened spirolactam form which exhibited spectral and colorimetric changes in the NIR region. The probe based on UV-Vis and fluorescence techniques respond in 90 s, has wide linear ranges (for UV-Vis: 6.29 × 10^-8 - 1.86 × 10^-4 M; for fluorescence: 9.49 × 10^-9 - 1.13 × 10^-5 M), and has a lower Limit of Detection (LOD) value (for fluorescence: 4.93 × 10^-9 M, 0.99 ng/mL) than the value predicted by the US Environmental Protection Agency (EPA) organization. Hg²⁺ analysis was performed in drinking and tap water with low Relative Standard Deviation (RSD) values and high recovery. Smartphone and living cell applications were successfully performed for colorimetric sensing Hg²⁺ in real samples and 3T3 cells, respectively.

A novel ratiometric fluorescent and colorimetric sensor based on a 1,8-naphthalimide derivative for nanomolar Cu2+ sensing: smartphone and food applications

A novel 1,8-naphthalimide-based chemical sensor with ratiometric fluorescence behavior, as well as “naked-eye” response was developed for the sensitive and specific determination of Cu2+ at nanomolar levels.