Voltammetric determination of the endocrine disruptor diethylstilbestrol by using a glassy carbon electrode modified with a composite consisting of platinum nanoparticles and multiwalled carbon nanotubes

Sulfide-Doped Magnetic Carbon Nanotubes Developed as Adsorbent for Uptake of Tetracycline and Cefixime from Wastewater

In this study, a magnetic solid-phase extraction method was developed based on multi-wall carbon nanotubes decorated by magnetic nanoparticles (Fe₃O₄) and cadmium sulfide nanoparticles (Fe₃O₄@MWCNT-CdS) for trace extraction of cefixime and tetracycline antibiotics from urine and drug company wastewater. The adsorbent features were characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), and energy dispersive X-ray analysis (EDX). Various effective parameters on the sorption and desorption cycle, such as sorption time, the mass of adsorbent, pH, salt addition, and material ratio, were investigated and optimized. The data were evaluated using isotherm models, and experimental data were well-fitted to both Langmuir (R² = 0.975) and Freundlich (R² = 0.985) models. Moreover, kinetic of reaction was agreement with pseudo-second-order (R² = 0.999) as compared pseudo-first-order (R² = 0.760). The maximum adsorption capacity for tetracycline and cefixime was achieved at 116.27 and 105.26 mg·g^-1, respectively. Hence, the prepared adsorbent can be used as an alternative material for enhanced determination of pharmaceutical substances in biological fluids.

Platinum nanoparticles-embedded raspberry-liked SiO2 for the simultaneous electrochemical determination of eugenol and methyleugenol

Based on platinum nanoparticle-embedded raspberry-liked SiO₂, a sensitive and selective electrochemical sensor was developed for simultaneous determination of eugenol (EU) and methyleugenol (MEU). Raspberry-liked SiO₂ (RL-SiO₂) was characterized with open pores on the surface, which can be used as a path for utilizing the inner space fully. So, platinum nanoparticles (Pt NPs) could be embedded in the inner and outer surface of RL-SiO₂. As a carrier, RL-SiO₂ not only avoided the agglomeration of the Pt NPs but also improved the catalytic performance. Therefore, the prepared Pt NPs@RL-SiO₂/GCE exhibited excellent electrocatalytic activity for simultaneous determination of EU and MEU; the linearity ranges were 0.50 ~ 60 μmol/L for EU at a working potential of 0.65 V (vs. saturated calomel electrode) and 0.50 ~ 50 μmol/L for MEU at a working potential of 1.10 V; the detection limits were 0.12 μmol/L and 0.16 μmol/L (S/N=3); and the relative standard deviations (RSDs) were 3.2% and 4.5%, respectively. In addition, Pt NPs@RL-SiO₂/GCE was successfully applied to the analysis of fish samples; the obtained recoveries were between 92.0 and 107%. Notably, the results conducted on samples were highly consistent with those obtained from high-performance liquid chromatography. It can be concluded that the study provided a simple method for simultaneous electrochemical determination of EU and MEU in fish samples. Schematic illustration of the preparation of RL-SiO2@Pt NPs/GCE for simultaneous determination of eugenol and methyleugenol in fish samples.

New trends in the electrochemical detection of endocrine disruptors in complex media

Endocrine disruptors (EDCs) are substances existing in the environment which affect animal and human endocrine functions and cause diseases. A small quantity of EDCs can have a serious impact on the body. Currently, enzyme-linked immunosorbent assay (ELISA), high-performance liquid chromatography (HPLC), and other traditional methods are used to detect EDCs. Although their sensitivity and reliability are good, these methods are complex, expensive, and not feasible to use in the field. Electrochemical techniques present good potential for the detection of EDCs owing to their low cost, simple, and wearable instrumentation. This paper presents the new trends in this field over the last 3 years. Some simple materials can allow some EDCs to be directly detected. New designs of biosensors, such as aptasensors, allow a femtomolar limit of detection to be reached. Many types of nanomaterial-based sensors were tested; carbonaceous nanomaterials, such as multiwalled carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO), associated or not with other types of nanoparticles were included in numerous designs. Molecularly imprinted polymer (MIP)-based sensors constitute an emerging field. All the presented electrochemical sensors were successfully tested for the detection of EDCs in different types of real samples.

Voltammetric sensing based on the use of advanced carbonaceous nanomaterials: a review

This review (with 210 references) summarizes recent developments in the design of voltammetric chemical sensors and biosensors based on the use of carbon nanomaterials (CNMs). It is divided into subsections starting with an introduction into the field and a description of its current state. This is followed by a large section on various types of voltammetric sensors and biosensors using CNMs with subsections on sensors based on the use of carbon nanotubes, graphene, graphene oxides, graphene nanoribbons, fullerenes, ionic liquid composites with CNMs, carbon nanohorns, diamond nanoparticles, carbon dots, carbon nanofibers and mesoporous carbon. The third section gives conclusion and an outlook. Tables are presented on the application of such sensors to voltammetric detection of neurotransmitters, metabolites, dietary minerals, proteins, heavy metals, gaseous molecules, pharmaceuticals, environmental pollutants, food, beverages, cosmetics, commercial goods and drugs of abuse. The authors also describe advanced approaches for the fabrication of robust functional carbon nano(bio)sensors for voltammetric quantification of multiple targets. Graphical Abstract Featuring execellent electrical, catalytic and surface properies, CNMs have gained enormous attention for designing voltammetric sensors and biosensors. Functionalized CNM-modified electrode interfaces have demonstrated their prominent role in biological, environmental, pharmaceutical, chemical, food and industrial analysis.