A novel impedimetric sensor based on N-acetyl-L-cysteine for the determination of hydroxyl radicals in cell cultures in vitro

We report a novel impedimetric sensor based on a graphite electrode impregnated with polyethylene and paraffin under vacuum (IGE) modified with electrochemically deposited gold and a self-assembled monolayer of N-acetyl-L-cysteine (NAC/Au/IGE) for selective and sensitive determination of extracellular hydroxyl radicals (OH•) generated by living cells. The application of a sulphur-containing molecule oxidized by OH• predicts the high selectivity of the sensor, and the utilization of the non-faradaic impedance spectroscopy for recording an analytical response makes it possible to achieve superior sensitivity with a detection limit of 0.01 nM and a linear dynamic range of 0.08-8 nM. Meanwhile, NAC/Au/IGE demonstrated a strong potential of detecting OH• generated by biological objects via successful determination of extracellular hydroxyl radicals generated by normal fibroblast cells and prostate carcinoma cells.

Adsorptive stripping voltammetric determination of carbofuran in food using novel type of modified carbon-based electrode with grafted layers of nickel

A voltammetric determination of carbofuran (CBF) was developed using a novel type of carbon-containing electrode (CCE) modified with carbon ink (CI) and a chromatographic sorbent (CS) based of chromaton (Ch), polyethylene glycol and nickel acetylacetonate with grafted layers of nickel (NiCS, stands for Ni modified CS) further denoted as CI/NiCS/CCE. The surface morphology of this modified electrode was investigated by scanning electron microscopy (SEM) and by electrochemical impedance spectroscopy (EIS). CBF which is not electrochemically oxidizable was first hydrolyzed in alkaline medium to give anodically active phenolic analogue CBFP. The electrochemical reactions of CBFP at CI/NiCS/CCE were studied in phosphate buffer (PB) by cyclic voltammetry (CV) and linear sweep adsorptive stripping voltammetry (LSAdSV) using linear scan voltammetry in the first derivative mode (LSVFD). Linear concentration dependences in the concentration ranges from 0.1 to 10 μM and from 10 to 100 μM were obtained by the LSAdSV with limit of detection (LOD) and limit of quantification (LOQ) 0.06 and 0.19 μM, respectively. The novel modified CI/NiCS/CCE showed good stability and selectivity and was successfully used to determine CBF in real samples of vegetables and fruits with LOD 0.01 mg kg-1.

Graphene derivatives-based electrodes for the electrochemical determination of carbamate pesticides in food products: A review

Graphene (GR) composites have great potential for the determination of carbamates pesticides (CPs) by electrochemical methods. Since the beginning of the 20th century, GR has shown remarkable promise as electrode material for various sensors. The contamination of food products with harmful CPs is a major problem as they do not always damage human health immediately, but can be harmful after prolonged exposure. A range of advantages can be gained from their electrochemical determination, such as high sensitivity, reasonably selectivity, rapid detection, low limit of detection, and easy electrode fabrication. Furthermore, these electrochemical techniques are robust, reproducible, user-friendly, and conform to both "green" and "white" analytical chemistry. This review is focused on results published in the last ten years in the field of electrochemical determination of CPs in food products using GR and its derivatives.

Electrochemical Sensors for the Detection of Reactive Oxygen Species in Biological Systems: A Critical Review

Reactive oxygen species (ROS) involving superoxide anion, hydrogen peroxide and hydroxyl radical play important role in human health. ROS are known to be the markers of oxidative stress associated with different pathologies including neurodegenerative and cardiovascular diseases, as well as cancer. Accordingly, ROS level detection in biological systems is an essential problem for biomedical and analytical research. Electrochemical methods seem to have promising prospects in ROS determination due to their high sensitivity, rapidity, and simple equipment. This review demonstrates application of modern electrochemical sensors for ROS detection in biological objects (e.g., cell lines and body fluids) over a decade between 2011 and 2021. Particular attention is paid to sensors materials and various types of modifiers for ROS selective detection. Moreover, the sensors comparative characteristics, their main advantages, disadvantages and their possibilities and limitations are discussed.