Monitoring of Specific Phytoestrogens by Dedicated Electrochemical Sensors: A Review.

Phytoestrogens are non-steroidal estrogens produced from plants that can bind with the human body's estrogenic receptor site and be used as a substitute for maintaining hormonal balance. They are mainly classified as flavonoids, phenolic acids, lignans, stilbenes, and coumestans; some are resocyclic acids of lactones, which are mycotoxins and not natural phytoestrogen. Phytoestrogens have many beneficial medicinal properties, making them an important part of the daily diet. Electrochemical sensors are widely used analytical tools for analysing various pharmaceuticals, chemicals, pollutants and food items. Electrochemical sensors provide an extensive platform for highly sensitive and rapid analysis. Several reviews have been published on the importance of the biological and medicinal properties of phytoestrogens. However, this review provides an overview of recent work performed through electrochemical measurements with electrochemical sensors and biosensors for all the classes of phytoestrogens done so far since 2019.

Facile Synthesis of a Crystalline Zinc Sulfide/Chitosan Biopolymer Nanocomposite: Characterization and Application for Photocatalytic Degradation of Textile Dyes and Anticancer Activity.

In the present study, we have synthesized a zinc sulfide/chitosan (ZS/CS) nanocomposite by utilizing simple, economical, and environmentally friendly methods. The synthesized nanomaterials were characterized by different analytical techniques such as XRD, FE-SEM, EDS, and FTIR to determine the phase structure, morphology, and elemental composition. FTIR spectroscopy was used to confirm the functional groups of the synthesized zinc sulfide (ZS) nanoparticles and ZS/CS composite. Besides, the optical properties of the as-synthesized nanocomposite was analyzed by a UV-visible spectrophotometer, and the estimated band gap energy is ∼3.03 eV. The photocatalytic efficiency of the synthesized ZS/CS nanocomposite was investigated against two textile dyes, Crystal Violet (CV) and Acid Red-I (AR-I), under UV-visible light irradiation. The nanocomposite showed excellent photocatalytic activity against the dyes, and photodegradation was estimated to be about 93.44 and 90.67% for CV and AR-I, respectively. The nanocomposite was reused for three consecutive cycles. The results revealed that the photocatalyst displayed good reusability during the photocatalytic decomposition and thus is considered a cost-effective and promising photocatalyst in degrading dye pollutants. The kinetic study proved that the pseudo-first-order reaction kinetics was followed by the degradation process. We also examined the anticancer activity of ZS and ZS/CS against human breast and myelogenous leukemia cancer cell lines, namely, MCF-7 and K-562, and the half minimal inhibitory concentrations were found to be less than 50 µg/mL.

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.

Synergistic effect of 1-butyl-2,3-dimethylimidazolium bis (trifluoromethanesulfonyl) imide and titanium oxide on the redox behaviour of flunarizine in solubilized media.

Titanium oxide nanoparticles and 1-butyl-2,3-dimethylimidazolium bis (trifluoromethanesulfonyl) imide modified glassy carbon electrode (TiO2/IL/GCE) has been fabricated for electrochemical sensing of flunarizine (FRH). The electrochemical properties and morphology of the prepared nanocomposite were studied by electrochemical impedance spectroscopy (EIS) and transmission electron microscopy (TEM). The response of the electrochemical sensor was found to be proportional to the concentrations of FRH in the range from 0.5 µgmL-1 to 16 µgmL-1. The detection limit obtained was 0.03 µgmL-1. The proposed method was also applied to the determination of FRH in pharmaceutical formulation and human serum with good recoveries.

Recent trends in electrochemical sensors for multianalyte detection - A review.

Voltammetric methods for screening compounds of varied interests are reviewed on the basis of the types of electrodes and analytical strategies. The scope of conventional voltammetric method has been considerably expanded in the last years due to the development of a plethora of modified electrodes, in particular, those involving nanocomposites. Voltammetric methods have distinct advantages over other existing methods regarding sensitivity, minimum detectability, applicability to biological samples without any pretreatment and time saving. Simultaneous determination of compounds by voltammetry offers the advantages of being economical and less time consuming as more than one analyte can be detected easily on the fabricated sensor at the same time. Present review article focuses on the simultaneous voltammetric detection of various compounds reported during the last five years.

Adsorptive stripping voltammetric behavior and determination of anticholinergic agent oxybutynin chloride on a mercury electrode.

Oxybutynin chloride is an antispasmodic, anticholinergic agent indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency. Its electrochemical behavior in phosphate buffers of pH range 2-10 at a hanging mercury drop electrode has been investigated using cyclic voltammetry, differential pulse cathodic adsorptive stripping voltammetry (DPCAdSV), and squarewave cathodic adsorptive stripping voltammetry (SWCAdSV). Voltammograms of the drug in phosphate buffer of pH 2-10 exhibited a single two-electron wave and it may be attributed to the reduction of the C[triple bond]C center. Based on the high adsorptive character of oxybutynin chloride onto the mercury electrode, a validated direct squarewave cathodic adsorptive stripping voltammetric and differential pulse cathodic adsorptive stripping voltammetric procedure has been developed for the determination of drug in bulk form and pharmaceutical formulation. The proposed SWCAdS and DPCAdS voltammetric methods allow quantitation over the range 1-18 and 1-17.6 microg mL(-1) with detection limits of 0.1 and 0.23 microg mL(-1), respectively. Precision and accuracy were also checked and were within the limits.

Cathodic adsorptive stripping voltammetric studies on lamivudine: an antiretroviral drug.

The electrochemical reduction and adsorption of lamivudine, a systemic antiviral drug, were studied in a phosphate buffer medium at a hanging mercury drop electrode (HMDE). Cyclic voltammetry studies showed one well-defined reduction peak in the potential range from -1.2 to -1.8 V under different pH conditions, but the best results were obtained at pH 3.4. The reduction was irreversible and exhibited diffusion-controlled adsorption. The response was evaluated with respect to preconcentration time, pH effect, accumulation potential, accumulation time, and scan rate. The number of electrons transferred in the reduction process was calculated and the probable reduction mechanism was proposed. A systemic study of the experimental parameters that affect the square-wave stripping response was carried out and experimental conditions were optimized.

Determination of antihelminthic drug pyrantel pamoate in bulk and pharmaceutical formulations using electro-analytical methods.

Electrochemical behaviour of pyrantel pamoate has been studied by using different voltammetric and polarographic techniques in Britton Robinson buffer system. Differential pulse polarographic and cyclic voltammetric methods have been developed for the determination of drug in pharmaceutical formulation. A well-defined cathodic wave and one anodic peak were observed for the pyrantel pamoate in the entire pH range. Number of electrons transferred in the reduction process was calculated and the reduction mechanism postulated. The results indicate that the electrode process is reversible and diffusion controlled. The proposed method has been validated. The peak current is found to be linear over the concentration range 4x10(-4) to 2x10(-2)molL(-1). The lower detection limit (LOD) and lower limit of quantitation (LOQ) is found to be 2.45x10(-5) and 8x10(-5)molL(-1).

Analytical method development and validation of mianserin hydrochloride and its metabolite in human plasma by LC-MS.

Mianserin is a tetracyclic antidepressant drug and administered as racemate of R (-) and S (+) mianserin hydrochloride in a dose of 30-90 mg/day in divided doses. Liquid chromatography-mass spectroscopy (LC-MS) is a tool, which is widely used for determination of drug and their metabolites in biological fluids because of its high sensitivity and precision. Here we describe a liquid chromatography mass spectroscopy method for simultaneous determination of mianserin and its metabolite, N-desmethylmianserin, from human plasma using a liquid-liquid extraction with hexane:isoamylalcohol (98:2) and back extraction with 0.005 M formic acid solution. This method is specific and linear over the concentration range of 1.00-60.00 ng/ml for mianserin and 0.50-14.00 ng/ml for N-desmethylmianserin in human plasma. The lowest limits of quantification (LLQ) is 1.00 ng/ml for mianserin and 0.50 ng/ml for N-desmethylmianserin. Intraday and interday precision (%C.V.) is <10% for both mianserin and N-desmethylmianserin. The accuracy ranges from 94.44 to 112.33% for mianserin and 91.85-100.13% for N-desmethylmianserin. The stability studies showed that mianserin and N-desmethylmianserin in human plasma are stable during short-term period for sample preparation and analysis. The method was used to assay mianserin and its metabolite, N-desmethylmianserin, in human plasma samples obtained from subjects who had been given an oral tablet of 30 mg of mianserin.