Bismuth (III) oxide/glassy carbon sensor for sensing of antidepressant drug escitalopram in micellar media

Computational Modelling and Sustainable Synthesis of a Highly Selective Electrochemical MIP-Based Sensor for Citalopram Detection

A novel molecularly imprinted polymer (MIP) has been developed based on a simple and sustainable strategy for the selective determination of citalopram (CTL) using screen-printed carbon electrodes (SPCEs). The MIP layer was prepared by electrochemical in situ polymerization of the 3-amino-4 hydroxybenzoic acid (AHBA) functional monomer and CTL as a template molecule. To simulate the polymerization mixture and predict the most suitable ratio between the template and functional monomer, computational studies, namely molecular dynamics (MD) simulations, were carried out. During the experimental preparation process, essential parameters controlling the performance of the MIP sensor, including CTL:AHBA concentration, number of polymerization cycles, and square wave voltammetry (SWV) frequency were investigated and optimized. The electrochemical characteristics of the prepared MIP sensor were evaluated by both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. Based on the optimal conditions, a linear electrochemical response of the sensor was obtained by SWV measurements from 0.1 to 1.25 µmol L-1 with a limit of detection (LOD) of 0.162 µmol L-1 (S/N = 3). Moreover, the MIP sensor revealed excellent CTL selectivity against very close analogues, as well as high imprinting factor of 22. Its applicability in spiked river water samples demonstrated its potential for adequate monitoring of CTL. This sensor offers a facile strategy to achieve portability while expressing a willingness to care for the environment.

Electrooxidation and Development of a Highly Sensitive Electrochemical Probe for Trace Determination of the Steroid 11-Desoxycorticosterone Drug Residues in Water

Anabolic-androgenic steroids (AASs), a class of compounds frequently misused by competitors and unfortunately by the general population, have lately attracted international attention. Thus, extraordinary demands for developing low cost, precise, rapid, and facile protocols for detection and/or determination of AAS have arisen. Hence, the current strategy explores for the first time the redox features of 21-hydroxypregn-4-ene-3, 20-dione, namely, 11-desoxycorticosterone (DCS) AA drug steroid at a glassy-carbon electrode (GCE) in a wide pH range (pH 2.0–10.0) by adsorptive differential pulse-anodic stripping voltammetry (DP- ASV) and cyclic voltammetry (CV). At pH 2, DP-ASV and CV at the optimized pH 2–3 displayed an irreversible anodic peak at 0.4 V versus Ag/AgCl electrode. The dependency of the anodic peak current of the CV at 0.4 V at various concentrations and scan rate of the DCS drug was characteristic of an electrode-coupled electron transfer of EE type mechanism. At the optimized parameters, the proposed strategy allowed quantification of DCS in the concentration range 2.5 -13.19 nM (0.83-4.36 ng mL−1) with satisfactory limits of detection (LOD) and quantization (LOQ) of 9.3 × 10−1 nM (3.1 × 10−1 ng mL−1) and 3.1 nM (1.02 ng mL−1), respectively. A relative standard deviation (RSD) of ±3.93% (n = 5) at 4.0 ng mL−1 DCS was achieved. The established probe was fruitfully employed and validated for trace determination of DCS residues in environmental water. The interference of several common diverse species on DCS sensing was insignificant revealing good selectivity. The established probe exhibited good sensitivity, selectivity, precision, and accuracy, short analytical time, and low cost compared with the reported methods, for DCS determination.

Antidepressants determination using an electroanalytical approach: A review of methods

Antidepressants are the pharmaceutical compounds used in the treatment of depression, anxiety disorders and all related disturbances promoted by genetic factors, environmental problems or modern lifestyles. Nonetheless, the inadequate ingestion of antidepressants provokes adverse effects in the human body and can contaminate the environment. For this reason, it is necessary to identify and quantify these compounds in biological fluids, natural water, wastewater, and pharmaceutical formulations. Consequently, this review presents the main electroanalytical techniques used in the analysis of antidepressants, indicating the advantages, which include low cost, suitable analytical parameters, simplified sample preparation steps, easy operation and reduced time for completion of the analysis. Reports in specialized literature, published from 2000 to 2020, are presented and some are discussed, demonstrating that the electroanalytical techniques can be employed, with success, in the determination of antidepressants, indicating alternative methodologies to improve analytical parameters and minimize the use and generation of toxic residues.

A highly Sensitive Modified Glassy Carbon Electrode with Carboxylated Multi-walled Carbon Nanotubes/Nafion Nano composite for Efficient and Cheap Voltammetric Sensing of Dianabol Steroid in Biological Fluid

The extraordinary prerequisite for the analysis of an anabolic steroid, namely dianabol (DB), has inspired towards the development of a cost-effective and high-performance sensing probe. Thus, a simple and robust electrochemical sensor (c-MWCNTs-Nafion®lGCE) for dianabol (DB), a widely used steroid, was developed using a glassy carbon electrode (GCE) modified with functionalized carboxylated multi-walled carbon nanotubes (c-MWCNT) and Nafion®. At pH 7 - 8, differential pulse-cathodic stripping voltammetry (DP-CSV) displayed two cathodic peaks at -0.85 and -1.35 V that varied linearly over a wide range (9.0 × 10-9 (2.7 μg L-1) - 9.0 × 10-6 (2.7 × 103 μg L-1) mol L-1) and 2.9 × 10-6 (8.7 × 102 μg L-1) - 8.0 × 10-5 (2.4 × 104 μg L-1) mol L-1) of DB concentrations, respectively. The low limits of detection and quantification at peak I (-0.85 V) were 2.7 × 10-9 (8.1 × 10-1 ng mL-1) and 9.0 × 10-9 (2.7 ng mL-1) mol L-1, respectively. The repeatability and reproducibility displayed relative standard deviations lower than 5%. The method was applied for DB analysis in human urine and subsequently compared with the standard HPLC method. Interference of common metabolites in biological fluids samples to DB sensing was insignificant. This method has distinctive advantages e.g. precise, short analytical time, sensitive, economical, reproducible and miniaturized sample preparation for DB analysis in biological samples of human origin.

Nanostructured materials in electroanalysis of pharmaceuticals

Basic strategies and recent developments for the enhancement of the sensory performance of nanostructures in the electroanalysis of pharmaceuticals are reviewed. A discussion of the properties of nanostructures and their application as modified electrodes for drug assays is presented. The electrocatalytic effect of nanostructured materials and their application in determining low levels of drugs in pharmaceutical forms and biofluids are discussed.