Showing papers on "Buffer solution published in 2020"
TL;DR: The electrode, CuO-rGR/1M3OIDTFB/CPE showed remarkable sensitivities towards the determination of the analytes, and well defined and clearly separated oxidation peaks were obtained during their simultaneous analysis in a buffer solution at pH 7.4.
315 citations
TL;DR: The Fe3+-sensitive carbon dots obtained by means of a microwave-assisted method using glutamic acid and ethylenediamine as reactants exhibited selective response toFe3+ ions in aqueous solution with a turn-off mode, and a good linear relationship was found between (F0-F)/F0 and the concentration of Fe3+.
Abstract: In this article, the Fe3+-sensitive carbon dots were obtained by means of a microwave-assisted method using glutamic acid and ethylenediamine as reactants. The carbon dots exhibited selective response to Fe3+ ions in aqueous solution with a turn-off mode, and a good linear relationship was found between (F0-F)/F0 and the concentration of Fe3+ in the range of 8-80 μM. As a result, the as-synthesized carbon dots can be developed as a fluorescent chemosensor for Fe3+ in aqueous solution. Moreover, the carbon dots can be applied as a fluorescent agent for fungal bioimaging since the fungal cells stained by the carbon dots were brightly illuminated on a confocal microscopy excited at 405 nm. Furthermore, an increase in the concentration of intracellular Fe3+ could result in fluorescence quenching of the carbon dots in the fungal cells when incubated in the Tris-HCl buffer solution containing Fe3+. However, due to EDTA might hinder Fe(III) to enter the fungal cells, incubation in Fe(III)-EDTA complex solution exerted negligible effect on the fluorescence of fungal cells labeled by the carbon dots. Therefore, the carbon dots can serve as a potential probe for intracellular imaging of Fe3+ inside fungal cells.
67 citations
20 Feb 2020
TL;DR: The kinetic release study showed that the curcumin release mechanism from PSS@HMS nanoparticles followed the Ritger–Peppas kinetic model, which is the non-Fickian diffusion, therefore, the PSS-decorated HMS nanoparticles demonstrate potential for pH-triggered drug release transport.
Abstract: In the current report, hollow mesoporous silica (HMS) nanoparticles were successfully prepared by means of a hard-templating method and further modified with poly(styrene sulfonate) (PSS) via radical polymerization. Structural analysis, surface spectroscopy, and thermogravimetric characterization confirmed a successful surface modification of HMS nanoparticles. A hairy PSS was clearly visualized by high-resolution transmission electron microscopy measurement, and it is grown on the surface of HMS nanoparticles. The Brunauer-Emmett-Teller surface area and average pore size of HMS nanoparticles were reduced after surface modification because of the pore-blocking effect, which indicated that the PSS lies on the surface of nanoparticles. Nevertheless, the PSS acts as a "nano-gate" to control the release of curcumin which is triggered by pH. The drug-release profile of unmodified HMS nanoparticles showed a stormed release in both pH 7.4 and 5.0 of phosphate buffer saline buffer solution. However, a slow release (9.92% of cumulative release) of curcumin was observed at pH 7.4 when the surface of HMS nanoparticles was modified by PSS. The kinetic release study showed that the curcumin release mechanism from PSS@HMS nanoparticles followed the Ritger-Peppas kinetic model, which is the non-Fickian diffusion. Therefore, the PSS-decorated HMS nanoparticles demonstrate potential for pH-triggered drug release transport.
41 citations
TL;DR: In this paper, a reagentless amperometric glucose biosensor based on nanobiocomposite consisting of poly(1,10-phenanthroline-5,6-dione), poly(pyrrole-2-carboxylic acid) (PPCA), gold nanoparticles (AuNP) and glucose oxidase (GOx) was designed.
39 citations
TL;DR: In this paper, the effect of buffer solution Na2HPO4/NaH2PO4 on buffer capacity of fermentation broth and photo-fermentation biohydrogen production (PFHP) was studied.
35 citations
TL;DR: In this article, a sensitive electrochemical sensor was developed by modifying a carbon paste electrode (CPE) with silver nanoparticles (AgNPs)/multi walled carbon nanotube (CNT)/folic acid (FA) for the improved detection of creatinine.
33 citations
TL;DR: The release performance indicates that the proposed approach can be used to encapsulate a variety of inhibitors for the protection of steel reinforcements and shows the suitability of its use in reinforced concrete systems.
Abstract: Herein, pH-sensitive microcapsules containing NaNO2 corrosion inhibitors for protection of steel reinforced concrete were synthesized via water-in-oil-in-water (W/O/W) double emulsion using colophony as the wall material. The average microcapsule size was 79.07 μm in diameter and exhibited a high encapsulation efficiency of 83.2%. Study of the release of corrosion inhibitors from microcapsules in deionized water (DI water, pH 6.8), carbonate/bicarbonate buffer solution (CBS, pH 9.1), and simulated concrete pore solution (SCPS, pH 12.6) demonstrates that the microcapsules are sensitive to pH and display higher release in alkaline media. This is the first study of colophony as an encapsulating agent for corrosion inhibitors. Furthermore, the alkaline pH-triggered release shows the suitability of its use in reinforced concrete systems. A wide thermal stability range was also found for the colophony microcapsules up to 100 °C. These high pH environments (CBS and SCPS) present pH values above the pKa of colophony (7.2), thus triggering enhanced inhibitor release by the ionization and deprotonation of colophony shell. The higher release in CBS and SCPS is demonstrated by the increases of the corrosion inhibitor diffusion coefficient by an order of magnitude from 3.30 × 10-17 m2/s in DI water up to 1.66 × 10-16 m2/s for SCPS. The release performance indicates that the proposed approach can be used to encapsulate a variety of inhibitors for the protection of steel reinforcements. After immersion in different pH solutions, the corrosion potentials of a carbon steel substrate with microcapsules containing nitrite were more noble than when immersed without microcapsules and the corrosion current densities showed comparable values to free corrosion inhibitors. The formation of a passive ferric oxide layer was confirmed by electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy.
32 citations
TL;DR: In this paper, the quantitative performance of the electrochemical redox reaction of glucose by glucosidase and oxygen with laccase in a phosphate buffer solution at pH 7.0 was examined.
Abstract: The main objective of this study was to examine the quantitative performance of the electrochemical redox reaction of glucose by glucosidase and oxygen with laccase in a phosphate buffer solution at pH 7.0. The characterization of electrode performance was performed by using electrochemical analysis such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The use of such electrochemical analysis (CV and EIS) enables a better understanding of the redox process, the charge transfer resistance, and, hence, the potential mass transfer among the electrode materials in phosphorus buffer solution. The experimental results show that the maximum power densities of the bioanode and the biocathode electrodes were 800 µA/cm2 and 600 µA/cm2, respectively. Both the bioanode and biocathode show high internal resistance. The occurrence of peak-separation shows an excellent mass-transfer mechanism and better chemical reactivity in the electrode.
30 citations
TL;DR: In this paper, a bimetallic film of mercury and bismuth (Hg-Bi) was incorporated with poly(1,2-diaminoanthraquinone)/glassy carbon electrode (PDAAQ/GC) using applied potential method.
Abstract: In this work, bimetallic film of mercury and bismuth (Hg-Bi) was incorporated with poly(1,2-diaminoanthraquinone)/glassy carbon electrode (PDAAQ/GC) using applied potential method. The obtained Hg-Bi/PDAAQ/GC electrode was characterized by square wave voltammetry (SWV), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) techniques. The proposed electrode had been used as a highly sensitive sensor for both single and simultaneous determination of lead (Pb2+), cadmium (Cd2+) and zinc (Zn2+) ions in acetate buffer solution by anodic stripping voltammetry (ASV). The adopted ASV method was achieved by optimizing different parameters such as metal deposition method (either in-situ or ex-situ), metals pre-concentration potential, pre-concentration time and different pH of values for acetate buffer solution. The prepared sensor provided a good reproducible response, high sensitivity with a linear range of 0.0–50.0 μg/L for Cd2+ and Zn2+ with a low detection limit of 0.107 and 0.037 μg/L, respectively. The linear range of Pb2+ was 10.0–120.0 ng/L with a detection limit of 3.18 ng/L. Also, the sensor was used for the analysis of the analytes in water samples with satisfactory results in comparison with inductively coupled plasma – mass spectroscopy (ICP-MS).
26 citations
TL;DR: The proposed aptamer-sensitized sensor was also successfully applied to detect HCVcoreAg in serum samples of hepatitis C patients and the effect of reverse polarity of the biosensor response signal with change from the acidic buffer pH to the neutral one was found.
Abstract: Herein, we have demonstrated highly sensitive real-time biospecific detection of a protein marker of hepatitis C—the core antigen of hepatitis C virus (HCVcoreAg)—using a nanowire (NW) biosensor. The primary element of the NW-biosensor is a chip with p-type conductance, bearing silicon-on-insulator (SOI) nanowire structures on its surface. The nanowire structures are fabricated by gas-plasma treatment and electron beam lithography. The detection specificity was provided by sensitization of the sensor surface with aptamers against HCVcoreAg. The influence of buffer pH on the sensor response signal was studied. The effect of reverse polarity of the biosensor response signal with change from the acidic buffer pH to the neutral one was found. The lowest detectable HCVcoreAg concentration was determined to be 2.0 × 10−15 M in both acidic (pH 5.1) and neutral (pH 7.4) buffer solution. The proposed aptamer-sensitized sensor was also successfully applied to detect HCVcoreAg in serum samples of hepatitis C patients.
24 citations
TL;DR: In this article, the effect of various alcohols as vehicles on skin permeability was compared for unmodified ibuprofen (IBU) and ion pairs of ibbofen with L-valine alkyl esters [ValOR][IBU], in which the alkyls chain R was changed from C1 to C8.
Abstract: The effect of various alcohols as vehicles on skin permeability was compared for unmodified ibuprofen (IBU) and ion pairs of ibuprofen with L-valine alkyl esters [ValOR][IBU], in which the alkyl chain R was changed from C1 to C8. In vitro permeation experiments were conducted in a Franz cell with porcine skin. Methanol, ethanol, and isopropanol solutions of 70% (v/v) were chosen as vehicles for penetrants and a buffer solution of pH 5.4 or 7.4 as the acceptor phase. The comparisons of permeation profiles for various [ValOR][IBU] from different alcohols were determined. The cumulative mass, skin accumulation, steady-state flux, diffusion coefficient, and lag time were investigated and compared. It was observed that i-propanol was the best enhancer of skin permeation of both unmodified ibuprofen and its salts with L-valine alkyl esters for both acceptor phases. The permeability of the various carriers increases with increasing chain-length of the alcohol. In most cases, significantly higher cumulative mass was found in the acceptor buffer of pH 7.4. The conjugate of ibuprofen with L-valine propyl ester [ValOPr][IBU] permeated the skin to the highest degree in comparison to unmodified ibuprofen. The accumulation of ibuprofen was higher for all salts in relation to the parent acid applied onto the skin. The greatest amounts of ibuprofen were accumulated in the skin when ibuprofen was used as the ionic pair with L-valine butyl ester, [ValOBu][IBU] in the i-propanol solution and pH 7.4 buffer as the acceptor phase.
TL;DR: The findings demonstrate that the synergistic electronic coupling between multiple components can enhance the peroxidase activity, which can facilitate the development of an effective, facile, and reliable method to perform colorimetric immunoassays of H2O2 and cancer cells.
TL;DR: In this article, a simple multifunctional sensor, X, was designed and synthesized based on 8-hydroxy-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinoline-9-carbaldehyde and imidazo[2, 1-b]thiazole, which could sequentially identify Zn2+ and PPi in acetonitrile buffer solution through the presence or absence of fluorescent signals and could detect In3+ in DMF buffer solution
Abstract: A simple multifunctional sensor, X, was designed and synthesized based on 8-hydroxy-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinoline-9-carbaldehyde and imidazo[2,1-b]thiazole, which could sequentially identify Zn2+ and PPi in acetonitrile buffer solution through the presence or absence of fluorescent signals and could detect In3+ in DMF buffer solution with obvious fluorescence enhancement. The detection limit for Zn2+, PPi and In3+ were calculated to be 4.58 × 10−8 M, 1.07 × 10−8 M and 2.9 × 10−8 M, respectively. Moreover, X could quantitatively detect Zn2+, PPi and In3+ in real water samples with the satisfactory recovery rate (90.1 %–97.6 %) and RSD (0.86 %–3.09 %). In addition, the complexation ratio between X and metal ions (Zn2+ and In3+) was 1:1, which was proved by mass spectrometry titration. The binding mode and sensing mechanism of X to metal ions (Zn2+ and In3+) were verified by Gaussian calculation based on B3LYP/6-31 G(d) and B3LYP/LanL2DZ basis set.
TL;DR: In this article, the mechanism of 223Ra uptake on hydroxyapatite and titanium dioxide nanoparticles was studied as a function of pH, and the most important species playing a role in sorption on the edge-sites were RaCO3, RaPO4−, RaHPO4 and Ra(Ac−)2, and Ra2+ and RaH2PO4+ on layer-sites.
Abstract: The mechanism of 223Ra uptake on hydroxyapatite and titanium dioxide nanoparticles was studied as a function of pH. Both materials are widely used in food industry and medicine. They offer properties suitable for labelling with medicinal radionuclides, particularly for targeted radionuclide therapy. The selected isotope, 223Ra, is an alpha emitter widely used in targeted alpha particle therapy due to high-dose delivery in very small tissue volume, nevertheless the results are applicable for any radium isotope including 226Ra. The study was performed in the pH range 4.5 to 12 for hydroxyapatite nanoparticles and 2 to 12 for titanium dioxide nanoparticles in Britton–Robinson buffer solution. Both nanomaterials at pH 6 and higher showed that over 95% of the radium has been sorbed. According to the applied chemical equilibrium model, the most important species playing a role in sorption on the edge-sites were RaCO3, RaPO4−, RaHPO4 and Ra(Ac−)2, and Ra2+ and RaH2PO4+ on layer-sites. All experiments were conducted under free air conditions and no negative impact of CO2 was found. The surface complexation model was found suitable for describing radium uptake by the studied hydroxyapatite and titanium dioxide nanomaterials.
TL;DR: PEC-3 is the film with the highest drug loading capacity and drug loading efficiency values of 3.51% and 87% respectively and is the most hydrophilic surface with a contact angle value of 38.1° among all other films.
TL;DR: A double Schiff base T as acceptor for metal ions derived from thiophene-2,5-dicarboxylic acid was designed and synthesized, and showed a high selectivity for In3+ in a DMF/H2O buffer solution.
Abstract: A double Schiff base T as acceptor for metal ions derived from thiophene-2,5-dicarboxylic acid was designed and synthesized, and showed a high selectivity for In3+ in a DMF/H2O buffer solution. T exhibited a 300-fold fluorescence enhancement upon the addition of In3+, accompanying a visual color change from dark (Φ = 0.009) to bright yellow (Φ = 0.197). The complex T–In3+ could serve as a secondary sensor for PPi, which displayed recyclability upon the sequential addition of In3+ and PPi. The detection limits were calculated to be 4.48 × 10−8 M for In3+ and 4.4 × 10−6 M for PPi, respectively. According to Job's plot, T and In3+ tended to form 1 : 2 complexes with the binding affinity of 2.3 × 109 M2. The fluorescence behavior of T towards In3+ was primarily explained by the photoinduced electron transfer (PET) process based on theoretical calculations using Gaussian 09. Moreover, T could be applicable for indium detection in tap water with satisfactory recovery and RSD.
TL;DR: Under the optimum conditions, a 92-fold improvement was obtained in the detection power of the flame atomic absorption spectrometry (FAAS) and the limit of detection (LOD) and limit of quantification (LOQ) values were found to be 2.6 and 8.6 μg/L, respectively.
TL;DR: The results indicate that the galactose isomerization by Lobry de Bruyn-Alberda-van Ekenstein transformation rarely occurred at low pH due to the formation of organic acids.
TL;DR: This work reveals that the chiral MOCs material is feasible for the enantioseparation in CEC.
Abstract: Since some metal-organic cages (MOCs) have been synthesized in past several years, the applications of MOCs such as drug delivery, molecular recognition, separation, catalysis, and gas storage, etc. have been witnessed with a significant increase. However, to the best of our knowledge, so far no one has used MOCs as chiral stationary phase to separate chiral compounds in CEC. In this study, three MOCs were developed as the stationary phase for CEC separation of enantiomers. The MOCs coated capillary column showed good chiral recognition ability for some chiral compounds, including amine, alcohols, ketone, etc. The influence of buffer concentration, applied voltage, pH of buffer solution on the chiral separations was also investigated. The RSDs of run-to-run, day-to-day, and column-to-column for retention time were 2.1-4.67%, 1.2-4.36%, and 3.62-6.43%, respectively. This work reveals that the chiral MOCs material is feasible for the enantioseparation in CEC.
TL;DR: In this paper, the effects of different supporting electrolytes on the electrochemical behavior of vitamin B2 (VB2), vitamin B6 (VB6), and vitamin C (VC) using a common screen-printed carbon electrode (SPCE) to achieve simultaneous detection.
Abstract: To provide new choices and to replace the complicated steps of synthesizing modified electrodes, this research reports the systematic investigation of the effects of different supporting electrolytes on the electrochemical behavior of vitamin B2 (VB2), vitamin B6 (VB6), and vitamin C (VC) using a common screen-printed carbon electrode (SPCE) to achieve simultaneous detection The roles of various well-known supporting electrolytes, including Britton–Robinson buffer solution (BRBS), acetate buffer solution (ABS), and phosphate buffer solution (PBS), in the electrochemical oxidation of VB2, VB6, and VC were carefully evaluated by square wave voltammetry (SWV) From a successive investigation based on the ionic conductivity of the species contained in the supporting electrolytes, PBS at pH 35 was selected as a suitable supporting electrolyte for the simultaneous detection of VB2, VB6, and VC Under the optimized conditions, the simultaneous detection of VB2, VB6, and VC provided satisfactory sensitivity, selectivity, and reproducibility even when using a common electrode To demonstrate the practicality and reliability of the proposed analytical procedure, the simultaneous detection of VB2, VB6, and VC was performed in mixed vegetable and fruit juice samples and urine samples by SWV, and the results were compared with those obtained by chromatographic detection Therefore, this method was found to be simple and may be a new alternative for the simultaneous determination of VB2, VB6, and VC in practical applications
TL;DR: In this article, an easy and general synthesis procedure for the formation of Ce(IV)-MOFs was reported, which achieved highly homogeneous topology, nano-sized crystals, stable oxidation states Ce(III) and Ce (IV) at room temperature, significant surface area and thermal stability up to 320°C.
Abstract: We report on the applicability of an easy and general synthesis procedure for the formation of Ce(IV)-MOFs. Cerium-based metal–organic frame (Ce-MOF) was successfully synthesized by a simple, cost-effective and green route. Highly homogeneous topology, nano-sized crystals, stable oxidation states Ce(III) and Ce(IV) at room temperature, significant surface area and thermal stability up to 320°C are the notable properties achieved by Ce-MOF. Electron transferability of the cerium electrode was used for the detection of methylene blue (MB) analyte in acidic buffer solution. Also the effect of different pH buffer solutions on electrode response has been studied. Photocatalytic performance of nano-Ce-MOF was studied on the degradation of MB analyte under visible light.
TL;DR: In this paper, an environment-friendly method is used to prepare lysozyme coated fluorescent copper nanoclusters (CuNCs) of size 2.87 ± 0.09 nm.
TL;DR: Overall, acetic acid buffer is more environmental friendly, efficient, and cost effective than other solvents, thus, offering an improved extraction method for phytochemicals as valuable ingredients for nutraceutical applications, from underutilized dried blackcurrant skins (DBS).
Abstract: The aim of this study was to investigate the effects of different solvent and extraction temperatures on the free and bound phenolic compounds and antioxidant activity of dried blackcurrant skins (DBS). Apart from acetic acid buffer solution, different solvent systems including water, methanol, and mixtures of methanol/water were also employed and the effects of solvent and temperature (30 °C and 50 °C) on the free and bound forms of anthocyanins, hydroxycinnamic acids and flavonols yield were assessed. The results showed that amongst all solvents, acetic acid buffer resulted in the highest free anthocyanin content (1712.3 ± 56.1 mg/100 g) (p < 0.05) after 2 h extraction at 50 °C from DBS, while lower amounts of bound anthocyanins and anthocyanidins were detected after acid hydrolysis. Acetic acid buffer extracts exhibited the highest free hydroxycinnamic acid content (268.0 ± 4.5 mg/100 g), total phenolic content (3702.2 ± 259.3 mg GAE/100 g) and DPPH activity (60.7 ± 2.0 % of inhibition). However, their free flavonol content was slightly lower (60.2 ± 0.8 mg/100 g) compared to 100% methanol at 30 °C and 50 °C, 71.4 ± 1.5 mg/100 g and 71.5 ± 6.2 mg/100 g, respectively. Two-way ANOVA indicated interactions between solvent and temperatures (p < 0.05), which suggested that the relationship between solvent and phenolic compounds depends on the extraction temperature.
TL;DR: In this paper, a low cost, easy to make, disposable and paper-based soil pH sensor was used for measuring the soil pH using three electrode-based electrochemical platform, which is printed using screen-printing technique on a non-tearable hydrophobic paper.
Abstract: This paper for the first time demonstrates a low cost, easy to make, disposable and paper-based soil pH sensor. The measurement of soil pH is performed using three electrode based electrochemical platform. The sensor is printed using screen-printing technique on a non-tearable hydrophobic paper. Carbon paste is modified with pH sensitive quinone moiety, alizarin, which shows 2e−/2H+ redox process. The detection is carried out using square wave voltammetry at 25 ± 1°C. Eleven different kinds of soil have been collected from three different provinces in India. Samples are prepared using the standard protocol viz . 1M KCl and 0.01M CaCl2. The sensitivity is 60.61 mV/pH and 65.16 mV/pH for buffer solution containing 1M KCl and 0.01M CaCl2, respectively. Two consecutive scans are taken for accurately measuring the soil pH. The first scan shows two peaks which correspond to different types of redox behaviour of alizarin. The second scan shows the actual pH behavior which is demonstrated for the first time. Soil samples prepared using KCl solution show the relative error within 4.9%. For CaCl2 samples the relative error is within 2.9% for soil pH less than 7.3 and within 7.9% for pH greater than 7.3.
TL;DR: In this paper, the synthesis and characterization of a cocrystal formed by norfloxacin (NOR) and nicotinic acid (NCA) was reported, and the crystalline structure and the coordination sites were obtained through Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRPD).
TL;DR: In this paper, the GNB-modified carbon felt (CF) was used for the trace determination of radioactive waste, especially Ce3+, by electrochemical methods. But the results of the analysis were limited to 2.60 μM.
Abstract: Trace determination of radioactive waste, especially Ce3+, by electrochemical methods has rarely been attempted. Ce3+ is (i) a fluorescence quencher, (ii) an antiferromagnet, and (iii) a superconductor, and it has been incorporated into fast scintillators, LED phosphors, and fluorescent lamps. Although Ce3+ has been utilized in many industries due to its specific properties, it causes severe health problems to human beings because of its toxicity. Nanomaterials with fascinating electrical properties can play a vital role in the fabrication of a sensor device to detect the analyte of interest. In the present study, surfactant-free 1,8-diaminonaphthalene (DAN)-functionalized graphene quantum dots (DAN-GQDs) with nanobud (NB) morphology were utilized for the determination of Ce3+ through electrochemical studies. The working electrode, graphene nanobud (GNB)-modified-carbon felt (CF), was developed by a simple drop-coating method for the sensitive detection of Ce3+ in acetate buffer solution (ABS, pH 4.0 ± 0.05) at a scan rate of 50 mV s−1 using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. CV and DPV studies validated the existence of distinctive peaks at approximately +0.20 and +0.93 V (vs. SCE), respectively, with a limit of detection of approximately 2.60 μM. Furthermore, electrochemical studies revealed that the GNB-modified-CF electrode was (i) stable even after fifteen cycles, (ii) reproducible, (iii) selective towards Ce3+, (iv) strongly pH-dependent, and (v) favored Ce3+ sensing only at pH 4.0 ± 0.05. Impedance spectroscopy results indicated that the GNB-modified-CF electrode was more conductive (1.38 × 10−4 S m−1) and exhibited more rapid electron transfer than bare CF, which agrees with the attained Randles equivalent circuit. Microscopy (AFM, FE-SEM, and HR-TEM), spectroscopy (XPS and Raman), XRD, and energy-dispersive X-ray (EDX) analyses of the GNB-modified-CF electrode confirmed the adsorption of Ce3+ onto the electrode surface and the size of the electrode material. Ce3+ nanobuds increased from 35–40 to 50–55 nm without changing their morphology. The obtained results provide an insight into the determination of Ce3+ to develop an electrochemical device with low sensitivity.
TL;DR: In this article, the conjugated polymer PHCQE/AuNPs/GOx biosensor showed a linear response for glucose in the concentration range between 0.75 and 3.4.
TL;DR: This study demonstrates the versatility of the BDD-Q pH electrode for real-time ex-vivo biological tissue measurements, in both the absence and presence of pharmacological agents aimed at altering acid/bicarbonate production.
Abstract: Ex vivo pH profiling of the upper gastrointestinal (GI) tract (of a mouse), using an electrochemical pH probe, in both the absence and presence of pharmacological agents aimed at altering acid/bicarbonate production, is reported. Three pH electrodes were first assessed for suitability using a GI tract biological mimic buffer solution containing 0.5% mucin. These include a traditional glass pH probe, an iridium oxide (IrOx)-coated electrode (both operated potentiometrically), and a quinone (Q) surface-integrated boron-doped diamond (BDD-Q) electrode (voltammetric). In mucin, the time scale for both IrOx and glass to provide a representative pH reading was in the ∼100's of s, most likely due to mucin adsorption, in contrast to 6 s with the BDD-Q electrode. Both the glass and IrOx pH electrodes were also compromised on robustness due to fragility and delamination (IrOx) issues; contact with the GI tissue was an experimental requirement. BDD-Q was deemed the most appropriate. Ten measurements were made along the GI tract, esophagus (1), stomach (5), and duodenum (4). Under buffer only conditions, the BDD-Q probe tracked the pH from neutral in the esophagus to acidic in the stomach and rising to more alkaline in the duodenum. In the presence of omeprazole, a proton pump inhibitor, the body regions of the stomach exhibited elevated pH levels. Under melatonin treatment (a bicarbonate agonist and acid inhibitor), both the body of the stomach and the duodenum showed elevated pH levels. This study demonstrates the versatility of the BDD-Q pH electrode for real-time ex vivo biological tissue measurements.
01 Jun 2020
TL;DR: In this paper, the effect of ozonation time on the decolorization of azo dye has been examined, and the results were analyzed in terms of color removal efficiency.
Abstract: The efficiency of ozonation for the removal of color from textile azo dye solution containing Acid Red 14 by ozone was studied. The effect of ozonation time on the decolorization of azo dye has been examined, and the results were analyzed in terms of color removal efficiency. The high color removal efficiency of 93% was obtained after 25 min of ozonation. The effect of buffer solution on the ozonation was also studied, and the results demonstrated in terms of treatability effect for the removal of color from azo dye solutions.
TL;DR: In this paper, a copper film electrode (CuFE) was used as a simple and environmentally-friendly sensor for adsorptive stripping voltammetric detection of trace Ni(II).
Abstract: In this work, we present a copper film electrode (CuFE) as a simple and environmentally-friendly sensor for adsorptive stripping voltammetric detection of trace Ni(II). The CuFE was prepared directly in-situ on a supporting glassy carbon electrode, and revealed excellent electroanalytical performance in a 0.01 M ammonia buffer solution (pH 9.2), without using any stabilizing agent for copper ions. The sensor was used in combination with nioxime as a ligand for Ni(II). After the optimization of several key operational parameters, such as concentration of copper ions, accumulation potential, and accumulation time, the CuFE exhibited good linear response in the examined low concentration range of 1–10 μg L−1 Ni(II) (r2 of 0.995), and low limit of detection (3σ criterion) of 0.2 μg L−1. Finally, its applicability was successfully demonstrated by measuring Ni(II) in a real sample of seawater.