Bimetallic Cu-Rh Nanoparticles on Diazonium-Modified Carbon Powders for the Electrocatalytic Reduction of Nitrates

Electrodeposition of carbon nanotubes and conjugation of arginyl-glycyl-aspartic acid for the following of glioblastoma cells on bionanocomposites

The improvement of surface treatment methods that permit the tuning of cell adhesion on the surface of biomaterials and devices is of considerable importance. Here, multi-walled carbon nanotubes (MWCNT) were modified with 4-aminothiophenol (4ATP). Then, electrodeposition of MWCNT-4ATP was carried out on 4ATP-modified screen-printed gold electrodes (SP-Au). After conjugation of Arginyl-glycyl-aspartic acid (RGD)-peptide on Poly(MWCNT-4ATP), the adhesion of U-87MG glioblastoma cells was examined by differential pulse voltammetry (DPV) technique. The synthesized MWCNT-4ATP and the obtained Poly(MWCNT-4ATP)/RGD surfaces were characterized using Scanning Electron Microscopy-Energy Dispersive X-Ray Spectrometer (SEM-EDS), Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Photoelectron Spectrometer (XPS). The linear range for U-87MG glioblastoma cells was 102-106 cells/mL. The developed Poly(MWCNT-4ATP)/RGD cell adhesion platform provided monitoring of U-87MG glioblastoma cells using DPV technique and fluorescent imaging.

Acetylcholinesterase and butyrylcholinesterase co-immobilized on a copper containing Prussian blue modified electrode for the broad screening of insecticides

We have developed a bienzymatic biosensor that contains acetylcholinesterase together with butyrylcholinesterase co-immobilized on the same electrode modified with a stabilized copper containing Prussian blue electrodeposited on electrodes coated with 4-aminothiophenol monolayer using diazonium chemistry and copper nanoparticles for improved sensitivity. There are organophosphorus and carbamate neurotoxic insecticides that inhibit only one of the two enzymes, e.g., pirimicarb inhibits butyrylcholinesterase at much lower concentrations than acetylcholinesterase while methomyl inhibits only acetylcholinesterase. Our system is simple and in a single measurement provides a sensitive signal for insecticides' presence based on the inhibition of the enzyme with the highest affinity for each toxic compound. The limits of detection are 50 ng/mL pirimicarb for the bienzymatic biosensor in comparison with 400 ng/mL pirimicarb for the acetylcholinesterase biosensor and 6 ng/mL methomyl for the bienzymatic biosensor, while inhibition is obtained for the butyrylcholinesterase biosensor at 700 ng/mL.

Catalyst Design through Grafting of Diazonium Salts-A Critical Review on Catalyst Stability

In the pursuit of designing a reusable catalyst with enhanced catalytic activity, recent studies indicate that electrochemical grafting of diazonium salts is an efficient method of forming heterogeneous catalysts. The aim of this review is to assess the industrial applicability of diazonium-based catalysts with particular emphasis on their mechanical, chemical, and thermal stability. To this end, different approaches to catalyst production via diazonium salt chemistry have been compared, including the immobilization of catalysts by a chemical reaction with a diazonium moiety, the direct use of diazonium salts and nanoparticles as catalysts, the use of diazonium layers to modulate wettability of a carrier, as well as the possibility of transforming the catalyst into the corresponding diazonium salt. After providing descriptions of the most suitable carriers, the most common deactivation routes of catalysts have been discussed. Although diazonium-based catalysts are expected to exhibit good stability owing to the covalent bond created between a catalyst and a post-diazonium layer, this review indicates the paucity of studies that experimentally verify this hypothesis. Therefore, use of diazonium salts appears a promising approach in catalysts formation if more research efforts can focus on assessing their stability and long-term catalytic performance.

Nitrate electroreduction: mechanism insight, in situ characterization, performance evaluation, and challenges

Excessive nitrate ions in the environment break the natural nitrogen cycle and become a significant threat to human health. So far, many physical, chemical, and biological techniques have been developed for nitrate remediation, but most of them require high post-processing costs and rigorous treatment conditions. In contrast, nitrate electroreduction is promising because it utilizes green electrons as reductants under ambient conditions. The recognition and mastering of the nitrate reaction mechanism is the premise for the design and synthesis of efficient electrocatalysts for the selective reduction of nitrate. In this regard, this review aims to provide an insight into the electrocatalytic mechanism of nitrate reduction, especially combined with in situ electrochemical characterization and theoretical calculations over different kinds of materials. Moreover, the performance evaluation parameters and standard test methods for nitrate electroreduction are summarized to screen efficient materials. Finally, an outlook on the current challenges and promising opportunities in this research area is discussed. This review provides a guide for development of electrocatalysts for selective nitrate reduction with a fascinating performance and accelerates the development of sustainable nitrogen chemistry and engineering.

Recent discoveries in the reaction mechanism of heterogeneous electrocatalytic nitrate reduction

We review advances in the electrocatalytic nitrate reduction mechanism and evaluate future efforts. Existing work could be supplemented by controlling reaction conditions and quantifying active sites to determine activity on a per-site basis.