Selective recognition of Ni2+ ion based on fluorescence enhancement chemosensor

A novel ratiometric fluorescent probe for the detection of nickel ions in the environment and living organisms

Nickel resources are abundant in the world, and the application of nickel in production and life is more and more extensive. However, excessive nickel entering the environment will not only cause environmental pollution but also seriously endanger plants, animals and human health. Nickel compounds are carcinogenic and have been classified as a class 1 carcinogen. Nickel mainly exists in the form of divalent ions in the environment. However, there are few simple and effective methods for the detection of nickel ions, and these methods still have certain limitations. At present, the mechanisms of nickel influence in organisms are also unclear. Therefore, we constructed a ratiometric fluorescent probe Ra-Ni, which can achieve its own self-calibration and avoid the interference of other factors, thereby realizing the specific identification of nickel ions. The probe can detect nickel ions sensitively with a detection limit as low as 26.2 nM and can respond in a short time (< 2 min), which proves the great potential of the probe in the detection of nickel ions. At the same time, Ra-Ni has also been successfully used for imaging nickel ions in living cells and zebrafish, providing an effective tool for the study of physiological and pathological processes. The detection effect of nickel ions in actual water sample is also satisfactory, which further demonstrates the practicability of Ra-Ni in environmental applications.

A New Schiff Base Organically Modified Silica Aerogel-Like Material for Metal Ion Adsorption with Ni Selectivity

Nickel has several industrial uses and is a valuable metal, making its selective separation and recycling a priority goal. A novel adsorbent, a Schiff base organically modified silica (ORMOSIL) aerogel, was prepared, for selective nickel removal from wastewater with other metal ions, by including a salen ionophore in the silica-based network. The newly developed adsorbent takes advantage of the salen’s selectivity and of the high porosity of silica aerogels. The aerogel-like adsorbent was prepared via sol-gel chemistry, using a coprecursor approach and ambient pressure drying. The inclusion of the Schiff base in the silica network was accomplished by reacting an amine-containing silica precursor with an aldehyde and confirmed by nuclear magnetic resonance (NMR) analysis. The adsorbent shrunk only 10% after evaporative drying, which resulted in a highly porous material (85% porosity, 4 cm3 g−1 specific pore volume). The low surface area of 28 m2 g-1 was due to the predominantly macroporous structure of the material (mean pore diameter of 563 nm). Adsorption isotherms and kinetic curves with single and binary mixtures of cations at room temperature were used to assess the selectivity of the adsorbent. The adsorption follows a BET (Brunauer-Emmett-Teller) trend. Due to the proximity of the oxygen and nitrogen atoms in the salen and steric hindrance from their neighboring atoms, it is likely that only the smallest hydrated cations can act as a coordination center and interact with both donor atoms. Thus, nickel was fairly removed (50 mg g-1), while other cations barely interacted with the adsorbent (cadmium adsorption maximum of 5 mg g-1). The estimated selectivity coefficient for nickel ranges from 1.8, in relation to copper, to 9.4 relatively to cadmium, which can be relevant for the separation of nickel in several industrial contexts, for instance, from electroplating sludge.

Magnetically induced self-assembly DNAzyme electrochemical biosensor based on gold-modifiedα-Fe2O3/Fe3O4heterogeneous nanoparticles for sensitive detection of Ni2

A magnetically induced self-assembly DNAzyme electrochemical biosensor based on gold-modifiedα-Fe₂O₃/Fe₃O₄heterogeneous nanoparticles was successfully fabricated to detect Nickel(II) (Ni²⁺). The phase composition and magnetic properties ofα-Fe₂O₃/Fe₃O₄heterogeneous nanoparticles controllably prepared by the citric acid (CA) sol-gel method were investigated in detail. Theα-Fe₂O₃/Fe₃O₄heterogeneous nanoparticles were modified by using trisodium citrate as reducing agent, and the magnetically induced self-assemblyα-Fe₂O₃/Fe₃O₄-Au nanocomposites were obtained. The designed Ni²⁺-dependent DNAzyme consisted of the catalytic chain modified with the thiol group (S1-SH) and the substrate chain modified with methylene blue (S2-MB). The MGCE/α-Fe₂O₃/Fe₃O₄-Au/S1/BSA/S2 electrochemical sensing platform was constructed and differential pulse voltammetry was applied for electrochemical detection. Under the optimum experimental parameters, the detection range of the biosensor was 100 pM-10μM (R² = 0.9978) with the limit of detection of 55 pM. The biosensor had high selectivity, acceptable stability, and reproducibility (RSD = 4.03%).

Ligands as copper and nickel ionophores: Applications and implications on wastewater treatment

Modern society depends on many finite natural resources, from which metals are of great importance. Copper and nickel's relevance is due to their vast applications, resulting in high market value and demand. As such, their polluting emissions are also significant and their removal from wastewaters is imperative. Moreover, effluent treatment techniques can be used to recover the metallic cations, via selective processes. In this review, copper and nickel selective ligands in the literature are surveyed. These are most commonly Schiff bases, along with crown ethers and porphyrins. They are usually employed in ion sensing (colorimetric chemosensors or electrodes) with great success - the disruption in response of colorimetric sensors is up to 7% and binding constants are usually at least one order of magnitude greater with the desired cation than with interferents. However, modified adsorbents are also reported. The possibilities of using ionophores in wastewater cleaning, allowing the treatment of effluents and the selective recovery of valuable materials, and their implications on new green policies is discussed.

Using Smartphone APP To Determine the CN- Concentration Quantitatively in Tap Water: Synthesis of the Naked-Eye Colorimetric Chemosensor for CN- and Ni2+ Based on Benzothiazole

A naked-eye colorimetric chemosensor DK based on benzothiazole could recognize CN^- effectively. When DK interacted with CN^- in the aqueous solution, the obvious color change of the solution was directly observed by the naked eye. Other anions did not cause any interference. It is interesting that DK could also discriminate Ni²⁺ from other cations, and the possible interaction mode between them was verified based on the Job's plot, ¹H nuclear magnetic resonance titration, infrared , electrospray ionization mass spectrometry, scanning electron microscopy analysis, and density functional theory calculation methods. As a result, it is clear that the mode of action between DK and CN^- was different from that between DK and Ni²⁺. Meanwhile, the limit of detection of DK toward CN^- and Ni²⁺ was calculated to be 1.7 × 10^-8 or 7.4 × 10^-9 M, respectively. In addition, CN^- was recognized qualitatively by a test paper and silica gel plates made from DK. DK was able to detect CN^- in tap water quantitatively, rapidly, and on-site by the use of a smartphone APP. All results implied that DK has certain prospects for practical application to identify CN^- in water.

A smart chemosensor: Discriminative multidetection and various logic operations in aqueous solution at biological pH

A novel rhodamine-pyrazole based molecular probe was designed and easily synthesized. The probe could to detect several analytes in aqueous solution at biological pH (HEPES, pH = 7.2). Several heavy metal cations, including Cu²⁺, Fe³⁺, Al³⁺, Hg²⁺ and Ni²⁺ were detected discriminately by the probe. Also, the novel compound exhibited a good sensory selectivity towards S₂O₅^2- by both absorption and emission spectra. Moreover, probe/Cu²⁺ complex could to detect several anions, including F^-, CN^-, S^2-, CH₃COO^-, CO₃^2- and NO₂^-. Furthermore, the probe exhibited a high potential to work as a molecular system able to perform a number of logical operations such as AND, NAND, NOR and INHIBIT logic gates.

Novel pyridyl based azo-derivative for the selective and colorimetric detection of nickel(II)

A highly sensitive and selective pyridyl based colorimetric chemosensor (H2L) for the efficient detection of Ni(2+) has been reported. The synthesized chemosensor H2L is highly efficient in detecting Ni(2+) even in the presence of other metal ions that commonly co-exist with Ni(2+). H2L also shows distinct color change from green to deep red visible under naked eye due to specific binding with Ni(2+). This color change is due to formation of a new band at 510 nm upon gradual addition of Ni(2+). The association constant has been found to be 1.27×10(5) M(-1) with limit of detection (LOD) of 8.3×10(-7) M. Electronic structure of the H2L-Ni(2+) complex and sensing mechanism have been interpreted theoretically by DFT and TDDFT calculations.

Highly selective colorimetric and reversible fluorometric turn-off sensors based on the pyrimidine derivative: mimicking logic gate operation and potential applications

Two simple and efficient energy transfer based fluorogenic receptors exhibiting high sensitivity for the Ni²⁺ ion and its validation using DFT geometry optimization.