Enhanced Electrochemical Determination of Catechol and Hydroquinone Based on Pd Nanoparticles/Poly(Taurine) Modified Glassy Carbon Electrode

Development of double-layer poly (amino acid) modified electrochemical sensor for sensitive and direct detection of betamethasone in cosmetics

Screening for illegal use of glucocorticoids (GCs) in cosmetics by electrochemical methods is extremely challenging due to the poor electrochemical activity of GCs. In this study, poly-L-Serine/poly-Taurine modified electrode (P(Tau)/P(L-Ser)/GCE) was prepared for sensitive and direct determination of betamethasone in cosmetics by a simple two-step in situ electropolymerization reaction. The relevant parameters of preparation and electroanalytical conditions were respectively studied, including the concentration of polymerization solution, the number of scanning circles and the scanning rate. The SEM and EDS mapping demonstrated successful preparation of P(Tau)/P(L-Ser)/GCE. The electro-catalytic properties of the obtained electrodes were investigated using cyclic voltammetry and differential pulse voltammetry methods, showing a remarkable improvement of sensitivity for the detection of betamethasone due to the synergic effect of both P(L-Ser) and P(Tau). In addition, we investigated the electrochemical reduction of betamethasone on the surface of modified electrode. It was found that the process was controlled by diffusion effect and involved the transfer of two electrons and two protons. Then the electrochemical sensor method based on P(Tau)/P(L-Ser)/GCE was established and delivered a linear response to betamethasone concentration from 0.5 to 20 μg mL-1 with a limit of detection of 32.2 ng mL-1, with excellent recoveries (98.1%-106.8%) and relative standard deviations (＜4.8%). Furthermore, the established electrochemical sensor method was compared with conventional HPLC method. The results showed that both of them were comparable. Moreover, the established electrochemical sensor method was with the merits of short analysis time, environmentally friendly, low cost and easy to achieve in-site detection.

Electrochemical Sensing Systems for the Analysis of Catechol and Hydroquinone in the Aquatic Environments: A Critical Review

Because of their unique physical, chemical, and biological characteristics, conductive nanomaterials have a lot of potential for applications in materials science, energy storage, environmental science, biomedicine, sensors/biosensors, and other fields. Recent breakthroughs in the manufacture of carbon materials, conductive polymers, metals, and metal oxide nanoparticles based electrochemical sensors and biosensors for applications in environmental monitoring by detection of catechol (CC) and hydroquinone (HQ) are presented in this review. To achieve this goal, we first introduced recent works that discuss the effects of phenolic compounds and the need for accurate, inexpensive, and quick monitoring, and then we focused on the use of the most important applications of nanomaterials, such as carbon-based materials, metals, and metal oxides nanoparticles, and conductive polymers, to develop sensors to monitor catechol and hydroquinone. Finally, we identified challenges and limits in the field of sensors and biosensors, as well as possibilities and recommendations for developing the field for better future applications. Meanwhile, electrochemical sensors and biosensors for catechol and hydroquinone measurement and monitoring were highlighted and discussed particularly. This review, we feel, will aid in the promotion of nanomaterials for the development of innovative electrical sensors and nanodevices for environmental monitoring.

High-performance electrochemical sensing platform based on sodium alginate-derived 3D hierarchically porous carbon for simultaneous determination of dihydroxybenzene isomers

Three-dimensional hierarchically porous carbon (denoted as SA-900) with a microporous, mesoporous and macroporous structure was facilely fabricated via direct carbonization of sodium alginate. SA-900 was fully characterized by N₂ adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction and Raman spectroscopy to confirm its structure. SA-900 was coated onto a glassy carbon electrode surface to construct an ultrasensitive electrochemical sensing platform (SA-900/GCE). Electrochemical behaviors of hydroquinone (HQ), catechol (CC) and resorcinol (RC) on the SA-900/GCE surface were investigated, and it was found that SA-900 possesses excellent electrocatalytic activity towards them. Experimental conditions including carbonization temperature, pH value, SA-900 concentration, accumulation potential and accumulation time were optimized for quantitative assay. Under optimized conditions, linear ranges for simultaneous determination of HQ, CC and RC are 0.05-1.50 μM, 0.05-1.50 μM and 0.50-15.00 μM, respectively. Detection limits for HQ, CC and RC are calculated to be 0.0183 μM, 0.0303 μM and 0.3193 μM (S/N = 3). The SA-900/GCE based electrochemical sensing platform is applied for determining HQ, CC and RC in lake water samples with satisfactory results.

Unique Host Matrix to Disperse Pd Nanoparticles for Electrochemical Sensing of Morin: Sustainable Engineering Approach

Biomass-based carbon nanospheres derived from Mimosa pudica (commonly called "Touch-me-not") smeared on carbon fiber paper have been used as a host matrix for electrochemical deposition of palladium nanoparticles. The physicochemical characterization of modified electrodes was performed by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy techniques. Cyclic voltammetry and electrochemical impedance spectroscopy were used to study the electroanalytical properties of the electrodes. The modified electrode demostrated an excellent electrocatalytic activity for the oxidation of a flavonoid, morin, which gave a sensitive anodic peak at -0.30 V (vs SCE). An ultralow-level detection limit of 572 fM with a linear dynamic range of 37.50-130 pM was achieved. The proposed electrochemical sensor was successfully employed for the analysis of morin in mulberry and guava leaves. This is a sustainable engineering approach where a perfect unique host matrix is created using carbon nanospheres from biomass.