Electrochemical sensing platform based on screen-printed carbon electrode modified with plasma polymerized acrylonitrile nanofilms for determination of bupropion.

A original electrochemical sensing platform, based on screen-printed electrodes modification with plasma polymerized acrylonitrile (pp-AN) nanofilms is proposed. For that purpose, plasma-enhanced chemical vapor deposition (PECVD) process was conducted in a parallel plate (13.56 MHz) plasma reactor for 2 min with discharge power of 10 W. The surface topography and electrochemical properties of prepared sensors were investigated by X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersion spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. The electrochemical characteristics of pp-AN/SPCE and pp-AN/SPAuE sensors was investigated for model redox pair [Fe(CN)6]4-/3-. Conducted research confirmed the excellent chemical stability, durability, wide potential window, high signal-to-noise (S/N) ratio, and, most importantly, the ability to standardize the sensors. The pp-AN/SPCE sensor was applied to the determination of bupropion, an antidepressant drug whose intake has increased dramatically during the COVID-19 pandemic. The voltammetric response of pp-AN/SPCE for BUP was linear in two concentration ranges of 0.63-10.0 and 10.0-50.0 µmol L-1, with a detection limit of 0.21 µmol L-1. Satisfactory recoveries (96.2-102%) and good precision (RSD below 4.1%) obtained for environmental and biological samples confirmed the usefulness of the sensor for the analysis of various kinds of samples.

A voltammetric sensor based on mixed proton-electron conducting composite including metal-organic framework JUK-2 for determination of citalopram.

A voltammetric sensor has been developed based on glassy carbon electrode (GCE) modification with nanocomposite consisting of manganese-based metal-organic framework (JUK-2), multi-walled carbon nanotubes (MWCNTs), and gold nanoparticles (AuNPs) for detection of citalopram (CIT). The composition and morphology of JUK-2-MWCNTs-AuNPs/GCE were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy dispersion spectroscopy (EDS), and scanning electron microscopy (SEM). The electrochemical properties investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) indicated that the fabricated hybrid material exhibits the properties of mixed ion-electron conductor (MIEC). Using staircase voltammetry (SCV), under optimized conditions, the fabricated sensor shows a linear response in three CIT concentration ranges, 0.05-1.0, 1.0-10.0 and 15.0-115.0 µmol L-1, with a detection limit of 0.011 µmol L-1. The JUK-2-MWCNTs-AuNPs/GCE was successfully employed for the determination of CIT in pharmaceutical, environmental waters, and biological samples with satisfactory recoveries (98.6-104.8%).

Flow manifold for chemical H-point standard addition method implemented to electrochemical analysis based on the capacitance measurements.

The paper presents a novel analytical method for electrochemical potassium determination using gold electrodes with self-assembled thiol monolayers (SATMs) deposited on its surface. The whole analytical procedure was carried out in a dedicated flow manifold using capacitance detection mode. The terminal functional groups on the surface of the dielectric monolayer interacts selectively with the analyte, changing the thickness of the layer depending on the amount of the analyte and the applied voltage, resulting in a change in the registered dielectric capacitance. New calibration approach based on the Chemical H-point Standard Addition Method (C-HPSAM), allowing both specific (proportional) and unspecific (constant) interference effects caused by sodium ions to be corrected, was applied. The calibration method is based on the registration of the calibration graphs by the standard addition method (SAM) three times in such different chemical conditions, which are able to differentiate the slope of each graph. The C-HPSAM was applied for the first time in electrochemical analysis. As a chemical parameter differentiating the sensitivity of the calibration graphs, the concentration of ionic strength stabilizer (ethylenediamine) was used. In order to improve the analytical procedure, to make it faster and automated, the dedicated flow system was applied. The constructed flow system was composed of several modules individually dedicated to the appropriate step of the whole analytical procedure: electrochemical cleaning of work electrode surface, adsorption of SATMs and analytical calibration. The calibration curves were obtained in the range of 0.1-0.9 mmol L-1 with good linearity (R2 = 0.996 ±â€¯0.001) and the LOD and LOQ of 28.6 and 85.8 µmol L-1, respectively. The proposed method was employed for potassium determination in highly mineralized water, juice and pharmaceutical samples without any special pretreatment.

Vasculogenic and hematopoietic cellular progenitors are scattered within the prenatal mouse heart.

Vasculogenesis and hematopoiesis are co-localized in the embryonic body, but precise phenotypes of the cells contributing to these processes are not defined. The aim of this study was to characterize phenotypic profiles and location of putative vasculogenic and hematopoietic cellular progenitors in the embryonic mouse heart. Confocal microscopy, as well as ultrastructural and stereomicroscopic analyses, was performed on immunohistochemical whole-mount-stained or sectioned hearts at stages 11.5-14 dpc. A FASC analysis was conducted to quantify putative vasculogenic and hematopoietic cells. We found subepicardial blood islands in the form of foci of accumulation of cells belonging to erythroblastic and megakaryocytic lineages at various stages of maturation, exhibiting phenotypes: GATA2(+)/CD41(+), GATA2(-)/CD41(+), GATA2(+)/CD71(-), GATA2(-)/CD71(+), Fli1(+)/CD71(+), Fli1(-)/CD71(+), with a majority of cells expressing the Ter119 antigen, but none of them expressing Flk1. The subepicardium and the outflow tract endothelium were recognized to be the areas where progenitor cells were scattered or adjoining the endothelial cells. These progenitor cells were characterized as possessing the following antigens: CD45(+)/Fli1(+), CD41(+)/Flk1(+), Flk1(+)/Fli1(+). A FACS analysis demonstrated that the CD41/Flk1 double-positive population of cells constituted 2.68% of total cell population isolated from 12.5 dpc hearts. Vessels and tubules were positive for CD31, Flk1, Fli1, Tie2, including blood islands endothelia. The endocardial wall endothelia were found to function as an anchoring apparatus for megakaryocytes releasing platelets into the cardiac cavities. Phenotypic characteristics of vasculogenic (Flk1(+)/Fli1(+)) and hematopoietic (GATA2(+)/CD71(+), CD41(+)/GATA2(+)) progenitors, as well as the putative hemogenic endothelium (Flk1(+)/CD41(+)) in embryonic mouse hearts, have been presented. Cardiac blood islands, the subepicardium and endothelium of the outflow tract cushions have been defined as areas where these progenitor cells can be found.

Cardiac mouse lymphatics: developmental and anatomical update.

The adult mouse heart possesses an extensive lymphatic plexus draining predominantly the subepicardium and the outer layer of the myocardial wall. However, the development of this plexus has not been entirely explored, partially because of the lack of suitable methods for its visualization as well as prolonged lymphatic vessel formation that starts prenatally and proceeds during postnatal stages. Also, neither the course nor location of collecting vessels draining lymph from the mouse heart have been precisely characterized. In this article, we report that murine cardiac lymphatic plexus development that is limited prenatally only to the subepicardial area, postnatally proceeds from the subepicardium toward the myocardial wall with the base-to-apex gradient; this plexus eventually reaches the outer half of the myocardium with a predominant location around branches of coronary arteries and veins. Based on multiple marker immunostaining, the molecular marker-phenotype of cardiac lymphatic endothelial cells can be characterized as: Prox-1(+), Lyve-1(+), VEGFR3(+), Podoplanin(+), VEGFR2(+), CD144(+), Tie2(+), CD31(+), vWF(-), CD34(-), CD133(-). There are two major collecting vessels: one draining the right and left ventricles along the left conal vein and running upwards to the left side of the pulmonary trunk and further to the nearest lymph nodes (under the aortic arch and near the trachea), and the other one with its major branch running along the left cardiac vein and further on the surface of the coronary sinus and the left atrium to paratracheal lymph nodes. The extracardiac collectors gain the smooth muscle cell layer during late postnatal stages.