In this research, graphitic carbon nitride (g-C3N4) was synthesized using pyrolysis of melamine and its phase, morphology, composition, and structure were characterized by using scanning electron ...microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive analysis of X-rays, and FT-IR spectroscopy. The modification of carbon paste electrode with g-C3N4/chitosan composite has been performed using the casting method. Experimental results demonstrated the superb adsorptive properties of g-C3N4/chitosan composite through Hg(II). Differential pulse voltammetry (DPV) was applied for quantitative determinations. The linear calibration curves is obtained in the ranges of 1.0 × 10–6to 8.0 × 10–5 mol L–1 and 1.0 × 10–7 to 5.0 × 10–6 mol L–1. The proposed protocol can offer a highly selective and sensitive method for the detection of Hg(II) with a detection limit of 1.0 × 10–8 mol L–1. Determination of Hg(II) was performed in the presence of Fe(II) and Cu(II). Finally, the modified electrode has been applied for sensitive determination of Hg(II) in real samples.
Nickel(II) tetradentate Schiff-base complexes of N,N′-(bis(pyridin-2-yl)formylidene)ethane-1,2-diamine (L1), N,N′-(bis(pyridin-2-yl)formylidene)cyclohexane-1,2-diamine (L2), ...N,N′-(bis(pyridin-2-yl)formylidene)benzene-1,2-diamine (L3), N,N′-(bis(pyridin-2-yl)formylidene)meso-stilben-1,2-diamine (L4), and N,N′-(bis(pyridin-2-yl)formylidene)propane-1,3-diamine (L5) were synthesized, characterized, and immobilized on sodium montmorillonite. The complexes were characterized by IR spectroscopy, diffuse reflectance spectra (DRS), and atomic absorption spectroscopy (AAS). IR and DRS data of the heterogeneous catalysts show that the Ni(II) complexes were physically entrapped within the sodium montmorillonite clay. The supported complexes show good catalytic activity for the epoxidation of cyclooctene using tert-butylhydroperoxide (TBHP) as oxygen source in acetonitrile. The Ni-catalyzed oxidation proceeds with 62.3% selectivity for epoxidation with 69% conversion for supported Ni(L5).
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Display omitted
•A Novel NiO/C@rGO nanocomposites derived from Ni(gallate) was prepared by a simple pyrolysis treatment.•The nanocomposite showed high selectivity and sensitivity toward glucose ...determination.•The proposed mechanism for non-enzymatic detection of glucose was discussed.
The development of suitable substrate materials in electrochemical sensors is essential for rapid and reliable quantification in the diagnostic and clinical fields. In this paper, NiO/C@rGO nanocomposite was synthesized through nickel (gallate) pyrolysis with graphene oxide and employed as a substrate to construct a glucose sensor with high selectivity and sensitivity. The structural characterizations of NiO/C@rGO were assessed by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, energy disperse spectroscopy, and elemental mapping. The newly fabricated biosensor (NiO/C@rGO/GCE) exhibited a high sensing performance with an extensive dynamic linear range (from 1 μM to 1115 μM) and a low limit of detection (LOD) 0.658 μM (S/N = 3) toward glucose. In addition, the NiO/C@rGO-based sensor displayed good stability, favorable repeatability, and anti-interference ability for determining glucose. It was also used to measure glucose in serum samples, and satisfactory results were attained. These results illustrated that the NiO/C@rGO nanocomposite could be applied as an excellent electrochemical sensing material with high sensitivity to diagnose glucose-related illnesses.
The electrochemical oxidation of thiocytosine on the surface of carbon-paste electrode modified with Schiff base (salophen derivatives) complexes of cobalt is studied. The effect of the substituents ...in the structure of salophen on the catalytic property of the modified electrode is investigated by using cyclic and differential pulse voltammetry. Cobalt (II)-5-nitrosalophen, because of its electrophilic functional groups, leads to a considerable enhancement in the catalytic activity, sensitivity (peak current), and a marked increase in the anodic potential of the modified electrode. The differential pulse voltammetry is applied as a very sensitive method for the detection of thiocytosine. The linear dynamic range was between 1 × 10−3 to 4 × 10−6 M with a slope of 0.0168 μA/μM, and the detection limit was 1 × 10−6 M. The modified electrode is successfully applied for the voltammetric detection of thiocytosine in human synthetic serum sample and also pharmaceutical preparations. A linear range from 1 × 10−3 to 1 × 10−5 M with a slope of 0.0175 μA/μM is resulted for the standard addition of thiocytosine spiked to the buffered human serum, which is differing from the curve in buffer solution about 4%. The electrode has a very good reproducibility (relative standard deviation for the slope of the calibration curve is less than 3.5% based on six determinations in a month), high stability in its voltammetric response and low detection limit for thiocytosine, and high electrochemical sensitivity with respect to other biological thiols such as cysteine.
Here, we have developed a sensitive electrochemical sensor for famotidine (FAT) using Cu
2
O nanoparticles and reduced graphene oxide (rGO). The Cu
2
O nanoparticles and rGO were synthesized through ...a simple process and characterized by versatile analytical techniques. The prepared Cu
2
O nanoparticles and rGO were taken to modify the carbon paste electrode (Cu
2
O/rGO/CPE) and applied for the electrochemical analysis of the FAT at pH 6.0. Cu
2
O/rGO/CPE showed superior response to determine FAT, attributed to the high surface area of rGO and the electrocatalytic properties of Cu
2
O nanoparticles. The designed FAT sensor exhibited two dynamic linear ranges from 0.1–3.0
μ
M and 3.0–50.0
μ
M with a limit of detection of 0.08
μ
M (S/N = 3) using a differential pulse voltammetry. The proposed sensor also showed a repeatable and stable response over one month with negligible interference from usual organic and inorganic species. The sensor was also validated to measure FAT in real samples (urine, serum and pharmaceutical tablet) with good recoveries from 99.6 to 110.9%.
In this study, an Au nanodendrites/broken hollow carbon spheres (Au NDs/BHCS) nanocomposite was prepared as an effective electrochemical sensor for detecting ultra-trace morphine (MPH) and exhibited ...advanced performance. The morphology, structure, and electrochemical behavior of the synthesized BHCS showed that the fractured spheres with a large specific surface area, high porosity, and good conductivity which can facilitate the transfer electrons at the sensor interface and afford an effective platform for electrochemical deposition of gold nanodendrites. Additionally, the catalytic property of Au nanodendrites is integrated with the electrochemical assay to reach high sensitivity for MPH detection. Benefiting from the synergistic effect of Au NDs and BHCS, the Au NDs/BHCS sensor demonstrated an outstanding electrochemical sensing performance toward MPH with a wider linear range of 0.01–300 µM and an ultralow detection limit of 8.3 nM. The introduced electrochemical sensor offers a promising method for highly sensitive and selective morphine sensing. Furthermore, the fabricated nanosensor was employed to determine MPH in spiked serum and saliva samples and indicated satisfactory recovery in the 97–100% range. This work supplies a new road for the expansion of validated platforms for on-site screening of illegal drugs, which is essential in clinical settings and forensics.
Display omitted
•Au nanodendrites/broken hollow carbon spheres (Au NDs/BHCS) nanosensor constructed.•The synergistic effect of Au NDs and BHCS provide the excellent electron transfer ability.•The fabricated nanosensor presented a very wide LDR from 0.01 to 300 µM for MPH assay with an ultralow LOD.•Morphine in human serum and saliva samples detected.
In this paper, a novel and highly sensitive atenolol sensor based on a poly-dopamine (PDA) is presented. PDA has been synthesized using a facile electro-deposition method. The polymer has been ...characterized with different techniques such as scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The glassy carbon modified with PDA has been applied for extraction and electrochemical sensing of atenolol. The extraction parameters such as pH, extraction time, and agitation rate were optimized. Differential pulse voltammetry has been used for quantitative determination of atenolol. The PDA thin film-based sensing platform exhibits high selectivity and sensitivity with a detection limit of 2.7×10−8M. Determination of atenolol in real samples has been demonstrated. The results suggested that the PDA modification of electrodes may provide a new strategy for atenolol concentration determination in physiological solutions.
Considering the different clinical aspects of polyps in asthmatic and nonasthmatic patients, we aimed to explore their histopathological characteristics.
Twenty-five asthmatic patients and 25 ...nonasthmatic patients with polypoid chronic rhinosinusitis (29 male, 21 female; mean age 41.3 +/- 13.27; range 15-78 years) were enrolled in the study to be compared on the basis of histopathological characteristics. They were compared according to the following seven light microscopic findings: basement membrane thickness, goblet cell hyperplasia, subepithelial edema, submucous gland formation, eosinophilic infiltration, lymphocytic infiltration, and polymorphonuclear infiltration.
Basement membrane thickening, goblet cell hyperplasia, and eosinophilic and lymphocytic infiltration were more prominent in the asthmatic compared with the nonasthmatic group (P < 0.05), whereas polymorphonuclear infiltration was more prominent in nonasthmatics (P < 0.05). No statistically significant differences were found between the two groups with regard to submucosal gland hyperplasia or subepithelial edema.
Asthmatic patients present histopathological characteristics of a marked chronic inflammatory reaction, which might explain the negative effect on chronic rhinosinusitis outcome and the severity of the disease in this group.
PDF
