Electrochemical sensor based on gum Arabic nanoparticles for rapid and in-situ detection of different heavy metals in real samples.

The key solution to combat trace metal pollution and keep the environment, ecosystem, animals, and humans safe is earlier and rapid trace metal detection. For all these reasons, we propose in this work the design of a simple electrochemical sensor functionalized with green nanoparticles for electrochemical detection of the fourth most dangerous heavy metal ions namely copper, zinc, lead, and mercury. The green nanoparticles are fabricated by a one-step, consisting of reducing platinum nanoparticles by a natural gum Arabic polymer. To guarantee the success of these nanoparticles' design, the nanoparticles have been characterized by Fourier-transform infrared spectroscopy FTIR, and thermogravimetric TGA techniques. While, for the electrochemical characterization, we have adopted cyclic voltammetry CV and electrochemical impedance spectroscopy EIS to control different steps of surface modification, and the differential pulse anodic stripping DPAS was monitored to follow up the electrochemical detection of different heavy metals. Results: have confirmed the good chemical and physical properties of the elaborated nanoparticles. As, the developed sensor showed a specific electrochemical response toward the heavy metal ions separately, with a lower limit of detection lower LOD than that recommended by the World Health Organization, in order of 9.6 ppb for Cu2+, 1.9 ppb for Zn2+, 0.9 ppb for Hg2+, and 4.2 ppb for Pb2+. Impressively, the elaborated sensor has demonstrated also high stability, outstanding sensitivity, and excellent analytical performance.In addition, the elaborated analytical tool has been successfully applied to the determination of various heavy metal ions in real samples, reflecting then its promising prospect in practical application.

Synthesis of 5-Fluorouracil Polymer Conjugate and 19F NMR Analysis of Drug Release for MRI Monitoring.

To monitor the release of fluorinated drugs from polymeric carriers, a novel 19F MRI enzyme-responsive contrast agent was developed and tested. This contrast agent was prepared by conjugation of 5-fluorouracil (5-FU) to hyperbranched poly(N,N-dimethylacrylamide) (HB-PDMA) via an enzyme-degradable peptide linker. Due to the different molecular sizes, the release of 5-FU from the 5-FU polymer conjugate resulted in a sufficiently substantial difference in spin-spin T219F NMR/MRI relaxation time that enabled differentiating between attached and released drug states. The 5-FU polymer conjugate exhibited a broad signal and short T2 relaxation time under 19F NMR analysis. Incubation with the enzyme induced the release of 5-FU, accompanied by an extension of T2 relaxation times and an enhancement in the 19F MRI signal. This approach is promising for application in the convenient monitoring of 5-FU drug release and can be used to monitor the release of other fluorinated drugs.

A Facile Approach of Fabricating Bifunctional Catalysts for Redox Applications by Uniformly Immobilized Metallic Nanoparticles on NiCr LDH.

This study discloses the development of NiCr LDH, Ag@NiCr LDH, and Pd@NiCr LDH bifunction catalysts using a hydrothermal coprecipitation method followed by sol immobilization of metallic nanoparticles. The structures and morphologies of the synthesized nanocomposites were analyzed using FTIR, XRD, XPS, BET, FESEM-EDX, and HRTEM. The catalytic effectiveness of the samples was evaluated by tracking the progression of NaBH4-mediated nitrobenzene (NB) reduction to aniline and CO oxidation using UV-visible spectrophotometry and an infrared gas analyzer, respectively. Pd@NiCr LDH displayed much higher performance for both reactions than the bare NiCr LDH. The catalyst Pd@NiCr LDH showed robust catalytic activity in both the oxidation of carbon monoxide (T50% (136.1 °C) and T100% (200.2 °C)) and NaBH4-mediated nitrobenzene reduction (98.7% conversion and 0.365 min-1 rate constant). The results disclose that the Ni2+@ Cr3+/Cr6+ @Pd° ion pairs inside the LDH act as a charge transfer center and hence significantly enhance the catalytic performance. As a result, this research offers the novel NiCr LDH catalyst as a bifunctional catalyst for air depollution control and the organic transformation process.

An Electrochemical Sensor for Sulfadiazine Determination Based on a Copper Nanoparticles/Molecularly Imprinted Overoxidized Polypyrrole Composite.

To protect consumers from risks related to overexposure to sulfadiazine, total residues of this antibacterial agent in animal-origin foodstuffs not exceed international regulations. To this end, a new electrochemical sensor based on a molecularly imprinted polymer nanocomposite using overoxidized polypyrrole and copper nanoparticles for the detection of sulfadiazine is elaborated. After optimization of the preparation of the electrochemical sensors, their differential pulse voltammetric signal exhibits an excellent stability and reproducibility at 1.05 V, with a large linear range between 10-9 and 10-5 mol L-1 and a low detection limit of 3.1 × 10-10 mol L-1. The produced sulfadiazine sensor was successfully tested in real milk samples. The combination of the properties of the electrical conduction of copper nanoparticles with the properties of the preconcentration of the molecularly imprinted overoxidized polypyrrole allows for the highly sensitive detection of sulfadiazine, even in real milk samples. This strategy is new and leads to the lowest detection limit yet achieved, compared to those of the previously published sulfadiazine electrochemical sensors.