Search

Introduction: The endothelial cells derived from the human vein cord (HUVECs) are used as in-vitro models for studying cellular and molecular pathophysiology, drug and hormones transport mechanisms, or pathways. In these studies, the proliferation and quantity of cells are important features that should be monitored and assessed regularly. So rapid, easy, noninvasive, and inexpensive methods are favorable for this purpose. Methods: In this work, a novel method based on fast Fourier transform square-wave voltammetry (FFTSWV) combined with a 3D printed electrochemical cell including two inserted platinum electrodes was developed for non-invasive and probeless rapid in-vitro monitoring and quantification of human umbilical vein endothelial cells (HUVECs). The electrochemical cell configuration, along with inverted microscope images, provided the capability of easy use, online in-vitro monitoring, and quantification of the cells during proliferation. Results: HUVECs were cultured and proliferated at defined experimental conditions, and standard cell counts in the initial range of 12 500 to 175 000 were prepared and calibrated by using a hemocytometer (Neubauer chamber) counting for electrochemical measurements. The optimum condition, for FFTSWV at a frequency of 100 Hz and 5 mV amplitude, were found to be a safe electrochemical measurement in the cell culture medium. In each run, the impedance or admittance measurement was measured in a 5 seconds time window. The total measurements were fulfilled at 5, 24, and 48 hours after the seeding of the cells, respectively. The recorded microscopic images before every electrochemical assay showed the conformity of morphology and objective counts of cells in every plate well. The proposed electrochemical method showed dynamic linearity in the range of 12 500-265 000 HUVECs 48 hours after the seeding of cells. Conclusion: The proposed electrochemical method can be used as a simple, fast, and noninvasive technique for tracing and monitoring of HUVECs population in in-vitro studies. This method is highly cheap in comparison with other traditional tools. The introduced configuration has the versatility to develop electrodes for the study of various cells and the application of other electrochemical designations. [ABSTRACT FROM AUTHOR]

This work is focused on the development of a sensitive voltammetric electrode for sulfadiazine using nanoparticles of Tb2(WO4)3 to modify a carbon paste electrode (CPE). The behavior of the modified CPE was evaluated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and fast Fourier transform square wave voltammetry (FFTSWV). The results revealed an irreversible sulfadiazine oxidation peak around 0.85 V vs. the Ag/AgCl reference electrode. The physicochemical properties of the nano-material were investigated using scanning electron microscopy (SEM), and X-ray powder diffraction (XRD). Some effective parameters such as, pH, percentage of modifier, amplitude, and frequency on sensor sensitivity were studied and optimized. The analytical curve was then obtained in the concentration ranges of 0.01-1.0 μM and 1.0-100 μM (with different sensitivity) with a detection limit of 4.10 nM by fast Fourier transform square wave voltammetry. Also, the electron transfer coefficient (α) was determined as a value of 0.66 for the sulfadiazine oxidation. The drug analysis in the pharmaceutical formulation was also carried out and recovery percentages in the range of 97-102% were recorded. The sensor presented good reproducibility and repeatability with acceptable RSD values (3.8%, 1.02% respectively) and long-term stability (almost one month). [ABSTRACT FROM AUTHOR]

Increasing application of pesticides and their toxicity made it essential to develop reliable and accurate methods of their trace quantification. This research was aimed to develop an electrochemical nanocomposite sensor based on molecularly imprinted polymer (MIP) for selective and sensitive determination of carbofuran. The proposed sensor was made based on incorporation of carbofuran MIP in the carbon paste. The square wave voltammetric (SWV) method was applied for the electrochemical measurements. The experimental design was then used to optimize parameters affecting the sensor response according to selected experimental domain. The obtained linear range after optimization of the parameters was from 1 x 10.sup.-9 to 1 x 10.sup.-6 M. The calculated detection limit was 3 x 10.sup.-10 M. Under optimized extraction and determination conditions, the proposed modified sensor indicated the considerable sensitivity and selectivity to determine carbofuran in some real samples (human urine, tap and river water) without any special sample pre-treatment before the analysis., Author(s): Monireh Khadem [sup.1], Farnoush Faridbod [sup.2], Parviz Norouzi [sup.2], Abbas Rahimi Foroushani [sup.3], Mohammad Reza Ganjali [sup.2], Rasoul Yarahmadi [sup.4], Seyed Jamaleddin Shahtaheri [sup.5] Author Affiliations: (1) grid.411705.6, 0000 [...]

Silicon (Si) is looked upon as a non-essential nutrient whose positive effects have been proved on most plant species. This study explored the impact of various types and rates of Si on some plant traits of rose (Rosa hybrida) 'Beverly Watson' in a factorial experiment based on a Randomized Complete Design with two treatments and three replications. Three Si sources (calcium silicate, potassium silicate, and sodium silicate) were used as foliar application in five rates (0, 50, 100, 150, and 200 mg L−1) during 10 wks. It was found that Si treatment improved flowering stem length and diameter, petal thickness, flower fresh and dry weight, and days to flower senescence, but it reduced days to full flower opening. Likewise, foliar application of Si increased leaf N, P, K, Ca, and Si content. Si at lower rates improved leaf Cu, Mn, and Fe content, but it reduced them at higher rates. [ABSTRACT FROM AUTHOR]