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A simple and inexpensive electrochemical sensor based on a glassy carbon electrode (GCE) modified with graphene quantum dots and carbon black nanoparticles (dihydrogen phosphate polyelectrolyte) is applied to determination of the emerging contaminant  the estrogen 17‐α‐ethinylestradiol (EE2). The combination of this nanocomposite with the GCE has not yet been explored as an electrochemical sensor. Combined, these materials create a synergy that enhances the overall performance of the oxidative detection system, resulting in a more efficient and accurate detection. The analytical curve presents a linear dynamic range from 0.998 to 10.0 µmol L−1, with a detection limit of 0.998 µmol L−1. Addition and recovery studies are carried out on a lake water sample, showing a recovery of 92.3%. The accuracy of the developed method is also evaluated by determining EE2 in pharmaceutical formulation samples. The obtained results are in statistical agreement with those obtained using high‐performance liquid chromatography–diode array detector at a confidence level of 95%. Therefore, the electrochemical sensor developed presents a fast construction procedure and the electroanalytical method for EE2 determination proves to be precise and accurate, with low consumption of reagents and a low relative cost. [ABSTRACT FROM AUTHOR]

In this study, a novel electrochemical assay for determining 17-β-estradiol (E2) was proposed. The approach involves modifying a glassy carbon electrode (GCE) with a nanocomposite consisting of α-Fe2O3 nanoparticles supported on carbon nanotubes (CNTs)—denoted as α-Fe2O3-CNT/GCE. The synthesis of the α-Fe2O3-CNT nanocomposite was achieved through a simple and cost-effective hydrothermal process. Morphological and chemical characterization were conducted using scanning electron microscopy (SEM), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The presence of the α-Fe2O3-CNT film on the GCE surface resulted in an enhanced electrochemical response to E2, preventing electrode surface fouling and mitigating the decrease in peak current intensity during E2 oxidation. These outcomes substantiate the rationale behind the GCE modification. After the optimization of experimental conditions, E2 was determined by the square wave voltammetry technique using 0.1 mol L−1 KCl solution (pH = 7.0) with 20% ethanol as a supporting electrolyte. A linear concentration range of 5.0–100.0 nmol L−1 and a low limit of detection of 4.4 nmol L−1 were obtained. The electroanalytical method using α-Fe2O3-CNT/GCE was applied for E2 determination in pharmaceutical, lake water, and synthetic urine samples. The obtained results were attested by recovery tests and by high-performance liquid chromatography as a comparative technique at a 95% confidence level. Thus, the developed electrochemical sensor is simple and fast to obtain, presents high accuracy, and is viable for determining E2 in routine analysis. [ABSTRACT FROM AUTHOR]

Flow injection analysis with chronoamperometry detection using a cathodically pretreated boron-doped diamond electrode (CPT-BDDE) was employed to develop and optimize a novel method for the determination of the hormones 17-α-ethinylestradiol (EE2) and cyproterone acetate (CPA). The electrochemical properties of EE2 and CPA were evaluated by cyclic voltammetry and oxidation peaks were observed at 0.97 V and 1.60 V in 0.04 mol L−1 Britton-Robinson buffer (pH 2.0). Analytical curves were linear in the concentration range from 0.070 to 10.0 µmol L−1 for EE2 and 1.0 to 80.0 µmol L−1 for CPA with detection limits of 0.023 and 0.23 µmol L−1, respectively. The developed methods presented good precision and accuracy for EE2 and CPA quantification in commercial pharmaceutical samples. The obtained results were satisfactory and consistent compared with a reference high-performance liquid chromatography method at a confidence level of 95%. Furthermore, recovery studies carried out in synthetic urine and lake water show that these methods do not suffer any significant matrix interferences and are potentially applicable for the determination of these hormones in real samples. Thus, the developed procedure for EE2 and CPA determination are simple and fast, with an analytical frequency of ∼83 determinations per hour, and attractive for routine analysis. [ABSTRACT FROM AUTHOR]

An electrochemical sensor for simultaneous determination of Benserazide (BEZ) and levodopa (L-dopa) was successfully developed using a glassy carbon electrode (GCE) modified with multi-walled carbon nanotube and nitrogen-doped titanium dioxide nanoparticles (GCE/MWCNT/N-TiO2). Cyclic voltammetry and square wave voltammetry were employed to investigate the electrochemical behavior of different working electrodes and analytes. In comparison with unmodified GCE, the modified electrode exhibited better electrocatalytic activity towards BEZ and L-dopa and was efficient in providing a satisfactory separation for oxidation peaks, with a potential difference of 140 mV clearly allows the simultaneous determination of these compounds. Under the optimized conditions, linear ranges of 2.0–20.0 and 2.0–70.0 μmol L−1 were obtained for BEZ and L-dopa, respectively, with a limit of detection of 1.6 µmol L−1 for BEZ and 2.0 µmol L−1 for L-dopa. The method was applied in simultaneous determination of the analytes in pharmaceutical samples, and the accuracy was attested by comparison with HPLC-DAD as the reference method, with a relative error lower than 4.0%. [ABSTRACT FROM AUTHOR]

Although drugs are intended to be selective, at least some bind to several physiological targets, explaining side effects and efficacy. Because many drug-target combinations exist, it would be useful to explore possible interactions computationally. Here we compared 3,665 US Food and Drug Administration (FDA)-approved and investigational drugs against hundreds of targets, defining each target by its ligands. Chemical similarities between drugs and ligand sets predicted thousands of unanticipated associations. Thirty were tested experimentally, including the antagonism of the [β.sub.1] receptor by the transporter inhibitor Prozac, the inhibition of the 5-hydroxytryptamine (5-HT) transporter by the ion channel drug Vadilex, and antagonism of the histamine [H.sub.4] receptor by the enzyme inhibitor Rescriptor. Overall, 23 new drug-target associations were confirmed, five of which were potent (, The creation of target-specific 'magic bullets' has been a therapeutic goal since Ehrlich (1), and a pragmatic criterion in drug design for 30 years. Still, several lines of evidence suggest [...]

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A new and simple photoelectrochemical (PEC) sensor using a glassy carbon electrode (GCE) modified with bismuth vanadate (BiVO4) nanoparticles and dihexadecyl phosphate (DHP) film was useful for acetaminophen (AC) determination. In 0.2 mol L−1 phosphate buffer (pH=9), the GCE without modification exhibited the smaller photocurrent (0.86 μA) when compared with GCE modified with 1.0 mg mL−1 or 2.0 mg mL−1 BiVO4 nanoparticles suspension (5.9 and 34 μA, respectively). Based on the photocurrent signal generated through the interaction between GCE, BiVO4 and the energy of visible light a chronoamperometric method for AC determination was developed. The AC linear range concentration from 0.099 to 0.99 μmol L−1 and limits of detection and quantification of 0.027 and 0.091 μmol L−1, respectively, was obtained. The proposed method was applied to the AC determination in commercial drugs and tap water with satisfactory accuracy and precision. Moreover, the PEC construction was easy and had a short response time, which might confer higher sample throughput for the method. [ABSTRACT FROM AUTHOR]