Spherical agarose-coated magnetic nanoparticles functionalized with a new salen for magnetic solid-phase extraction of uranyl ion

A Novel Electrochemical Sensor Modified with a Computer-Simulative Magnetic Ion-Imprinted Membrane for Identification of Uranyl Ion

In this paper, a novel ion-imprinted electrochemical sensor modified with magnetic nanomaterial Fe₃O₄@SiO₂ was established for the high sensitivity and selectivity determination of UO₂²⁺ in the environment. Density functional theory (DFT) was employed to investigate the interaction between templates and binding ligands to screen out suitable functional binding ligand for the reasonable design of the ion imprinted sensors. The MIIP/MCPE (magnetic ion imprinted membrane/magnetic carbon paste electrode) modified with Fe₃O₄@SiO₂ exhibited a strong response current and high sensitivity toward uranyl ion comparison with the bare carbon paste electrodes. Meanwhile, the MCPE was fabricated simultaneously under the action of strong magnetic adsorption, and the ion imprinted membrane can be adsorbed stably on the electrode surface, handling the problem that the imprinted membrane was easy to fall off during the process of experimental determination and elution. Based on the uranyl ion imprinting network, differential pulse voltammetry (DPV) was adopted for the detection technology to realize the electrochemical reduction of uranyl ions, which improved the selectivity of the sensor. Thereafter, uranyl ions were detected in the linear concentration range of 1.0 × 10⁻⁹ mol L⁻¹ to 2.0 × 10⁻⁷ mol L⁻¹, with the detection and quantification limit of 1.08 × 10⁻⁹ and 3.23 × 10⁻¹⁰ mol L⁻¹, respectively. In addition, the sensor was successfully demonstrated for the determination of uranyl ions in uranium tailings soil samples and water samples with a recovery of 95% to 104%.

Sensitive determination of uranium using β-cyclodextrin modified graphene oxide and X-ray fluorescence techniques: EDXRF and TXRF

β-cyclodextrin/graphene oxide (GO-β-CD) was applied for dispersive micro-solid phase extraction (DMSPE) of uranyl ions (UO₂²⁺) from water samples and their determination by energy-dispersive (EDXRF) and total-reflection X-ray fluorescence spectrometry (TXRF). The structure of GO-β-CD was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The results of batch adsorption experiment indicate that the maximum recoveries for UO₂²⁺ ions are observed at pH 4.5. The Langmuir isotherm model fits the adsorption data, which stands for the chemisorption mechanism. The obtained adsorption capacity of 87.7 mg g^-1 indicates a great potential of the synthesized adsorbent in the UO₂²⁺ ions preconcentration. The GO-β-CD exhibits high resistance to high ionic strength (up to 2 mol L^-1), indicating that high salinity samples can be treated with the evaluated preconcentration procedure. The obtained limit of detection values were 0.40 μg L^-1 for the EDXRF and only 0.014 μg L^-1 for TXRF analysis. The accuracy of the method was verified by analyzing certified reference material (spring water NIST-SRM 1640a) and spiked water samples (mineral, lake, river, and artificial sea water).

Rapid Screening and Identification of BSA Bound Ligands from Radix astragali Using BSA Immobilized Magnetic Nanoparticles Coupled with HPLC-MS

Radix astragali is widely used either as a single herb or as a collection of herbs in a complex prescription in China. In this study, bovine serum albumin functionalized magnetic nanoparticles (BSA-MN) coupled with high performance liquid chromatography-mass spectrometry (HPLC-MS) were used to screen and identify bound ligands from the n-butanol part of a Radix astragali extract. The prepared BSA-MN showed sufficient magnetic response for the separation with an ordinary magnet and satisfied reusability. Fundamental parameters affecting the preparation of BSA-MN and the screening efficiency were studied and optimized. Under the optimum conditions, four bound ligands were screened out from the n-butanol part of a Radix astragali extract and identified as genistin (1), calycosin-7-O-β-d-glucoside (2), ononin (3) and formononetin (4). This effective method could be widely applied for rapid screening and identification of active compounds from complex mixtures without the need for preparative isolation.