scholarly journals Modified Screen-Printed Potentiometric Sensors based on Man-Tailored Biomimetics for Diquat Herbicide Determination

2020 ◽  
Vol 17 (4) ◽  
pp. 1138
Author(s):  
Ayman H. Kamel ◽  
Abd El-Galil E. Amr ◽  
Nashwa S. Abdalla ◽  
Mohamed El-Naggar ◽  
Mohamed A. Al-Omar ◽  
...  
Keyword(s):  
Molecularly Imprinted Polymers ◽  
Limit Of Detection ◽  
Water Layer ◽  
Charge Transfer Resistance ◽  
Potentiometric Sensors ◽  
Layer Potential ◽  
Transfer Resistance ◽  
Commercial Pesticide ◽  
Ph Range ◽  
Screen Printed

Screen-printed platforms integrated with molecularly imprinted polymers (MIP) were fabricated and characterized as potentiometric sensors for diquat (DQ). The synthesized MIP beads were studied as sensory carriers in plasticized poly(vinyl chloride) membranes. The sensors were constructed by using poly(3,4-ethylenedioxythiophene) (PEDOT) as solid-contact material to diminish charge-transfer resistance and water layer potential. Conventional ion-selective electrodes (ISEs) with internal filling solution were used for comparison. The designed electrodes showed near Nernstian slopes of 28.2 ± 0.7 (r² = 0.999) over the concentration range of 1.0 × 10−6–1.0 × 10−2 M with the limit of detection 0.026 µg/mL over the pH range 4.2–9.0. The electrode exhibited good selectivity for diquat cations over a large number of organic and inorganic cations. The sensor was successfully introduced for direct measurement of diquat content in commercial pesticide preparations and different spiked potato samples. The results showed that the proposed electrode has a fast and stable response, good reproducibility, and applicability for direct assessment of diquat content. The proposed potentiometric method is simple and accurate in comparison with the reported HPLC methods. Besides, it is applicable to turbid and colored sample solutions.

scholarly journals Tailor-Made Specific Recognition of Cyromazine Pesticide Integrated in a Potentiometric Strip Cell for Environmental and Food Analysis

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1526 ◽  
Author(s):  
Nashwa S. Abdalla ◽  
Abd El-Galil E. Amr ◽  
Aliaa S. M. El-Tantawy ◽  
Mohamed A. Al-Omar ◽  
Ayman H. Kamel ◽  
...  
Keyword(s):  
Ion Association ◽  
Water Layer ◽  
Charge Transfer Resistance ◽  
Pvc Membrane ◽  
Official Method ◽  
Transfer Resistance ◽  
Plasticized Pvc ◽  
Specific Recognition ◽  
Novel Approach ◽  
Commercial Pesticide

Screen-printed ion-selective electrodes were designed and characterized for the assessment of cyromazine (CYR) pesticide. A novel approach is to design tailor-made specific recognition sites in polymeric membranes using molecularly imprinted polymers for cyromazine (CR) determination (sensor I). Another sensor (sensor II) is the plasticized PVC membrane incorporating cyromazine/tetraphenyl borate ion association complex. The charge-transfer resistance and water layer reached its minimal by incorporating Polyaniline (PANI) solid-contact ISE. The designed electrodes demonstrated Nernstain response over a linear range 1.0 × 10−2–5.2 × 10−6 and 1.0 × 10−2–5.7 × 10−5 M with a detection limit 2.2 × 10−6 and 8.1 × 10−6 M for sensors I and II, respectively. The obtained slopes were 28.1 ± 2.1 (r2 = 0.9999) and 36.4 ± 1.6 (r2 = 0.9991) mV/decade, respectively. The results showed that the proposed electrodes have a fast and stable response, good reproducibility, and applicability for direct measurement of CYR content in commercial pesticide preparations and soil samples sprayed with CYR pesticide. The results obtained from the proposed method are fairly in accordance with those using the standard official method.

scholarly journals Electrochemical Immunosensor for the Quantification of S100B at Clinically Relevant Levels Using a Cysteamine Modified Surface

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1929
Author(s):  
Alexander Rodríguez ◽  
Francisco Burgos-Flórez ◽  
José D. Posada ◽  
Eliana Cervera ◽  
Valtencir Zucolotto ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Surface Characterization ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Neuronal Damage ◽  
Charge Transfer Resistance ◽  
Single Frequency ◽  
Response Analysis ◽  
Transfer Resistance ◽  
Therapeutic Decisions

Neuronal damage secondary to traumatic brain injury (TBI) is a rapidly evolving condition, which requires therapeutic decisions based on the timely identification of clinical deterioration. Changes in S100B biomarker levels are associated with TBI severity and patient outcome. The S100B quantification is often difficult since standard immunoassays are time-consuming, costly, and require extensive expertise. A zero-length cross-linking approach on a cysteamine self-assembled monolayer (SAM) was performed to immobilize anti-S100B monoclonal antibodies onto both planar (AuEs) and interdigitated (AuIDEs) gold electrodes via carbonyl-bond. Surface characterization was performed by atomic force microscopy (AFM) and specular-reflectance FTIR for each functionalization step. Biosensor response was studied using the change in charge-transfer resistance (Rct) from electrochemical impedance spectroscopy (EIS) in potassium ferrocyanide, with [S100B] ranging 10–1000 pg/mL. A single-frequency analysis for capacitances was also performed in AuIDEs. Full factorial designs were applied to assess biosensor sensitivity, specificity, and limit-of-detection (LOD). Higher Rct values were found with increased S100B concentration in both platforms. LODs were 18 pg/mL(AuES) and 6 pg/mL(AuIDEs). AuIDEs provide a simpler manufacturing protocol, with reduced fabrication time and possibly costs, simpler electrochemical response analysis, and could be used for single-frequency analysis for monitoring capacitance changes related to S100B levels.

scholarly journals Structural refinement and electrochemical properties of one dimensional (ZnO NRs)1−x(CNs)x functional hybrids for serotonin sensing studies

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sajid B. Mullani ◽  
Ananta G. Dhodamani ◽  
Annadanesh Shellikeri ◽  
Navaj B. Mullani ◽  
Anita K. Tawade ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Electrochemical Properties ◽  
Surface Area ◽  
Limit Of Detection ◽  
Zno Nanorods ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Bet Analysis ◽  
Lower Charge ◽  
Lower Charge Transfer Resistance

Abstract Herein, the efficient serotonin (5-HT) sensing studies have been conducted using the (ZnO NRs)1−x(CNs)x nanocomposites (NCs) having appropriate structural and electrochemical properties. Initially, the different compositions of ZnO nanorods (NRs), with varying content of carbon nanostructures (CNs=MWCNTs and RGO), are prepared using simple in-situ wet chemical method and thereafter these NCs have been characterized for physico-chemical properties in correlation to the 5-HT sensing activity. XRD Rietveld refinement studies reveal the hexagonal Wurtzite ZnO NRs oriented in (101) direction with space group ‘P63mc’ and both orientation as well as phase of ZnO NRs are also retained in the NCs due to the small content of CNs. The interconnectivity between the ZnO NRs with CNs through different functional moieties is also studied using FTIR analysis; while phases of the constituents are confirmed through Raman analysis. FESEM images of the bare/NCs show hexagonal shaped rods with higher aspect ratio (4.87) to that of others. BET analysis and EIS measurements reveal the higher surface area (97.895 m2/g), lower charge transfer resistance (16.2 kΩ) for the ZCNT 0.1 NCs to that of other NCs or bare material. Thereafter, the prepared NCs are deposited on the screen printed carbon electrode (SPCE) using chitosan as cross-linked agent for 5-HT sensing studies; conducted through cyclic voltammetry (CV) and square wave voltammetry (SWV) measurements. Among the various composites, ZCNT0.1 NCs based electrodes exhibit higher sensing activity towards 5-HT in accordance to its higher surface area, lower particle size and lower charge transfer resistance. SWV measurements provide a wide linear response range (7.5–300 μM); lower limit of detection (0.66 μM), excellent limit of quantification (2.19 μM) and good reproducibility to ZCNT 0.1 NCs as compared to others for 5-HT sensing studies.

scholarly journals Fabrication of 2D-MoSe2 incorporated NiO Nanorods modified electrode for selective detection of glucose in serum samples

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gayathri Jeevanandham ◽  
Kumaran Vediappan ◽  
Zeid A. ALOthman ◽  
Tariq Altalhi ◽  
Ashok K. Sundramoorthy
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Limit Of Detection ◽  
Sodium Molybdate ◽  
Charge Transfer Resistance ◽  
Serum Samples ◽  
Transfer Resistance ◽  
X Ray ◽  
Transmission Electron ◽  
Composite Formation

AbstractLayered molybdenum diselenide (MoSe2) nanosheets were formed by the weak Van der Waals forces of attraction between Se and Mo atoms. MoSe2 has a larger space between the adjacent layers and smaller band gaps in the range of 0.85 to ~ 1.6 eV. In this study, MoSe2 nanosheets decorated nickel oxide (NiO) nanorods have been synthesized by hydrothermal method using sodium molybdate and selenium metal powder. NiO/MoSe2 composite formation was confirmed by powder X-ray diffraction analysis. In addition, the presence of MoSe2 nanosheets on NiO nanorods were confirmed by field emission scanning electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The Nyquist plots of NiO/MoSe2 coated glassy carbon electrode (GCE) was indicated that it had lower charge transfer resistance compared to NiO/GCE and MoSe2/GCE. Furthermore, as-prepared NiO/MoSe2/GCE was used to detect glucose in alkaline solution by cyclic voltammetry and amperometry techniques. The NiO/MoSe2/GCE was exhibited a linear response for the oxidation of glucose from 50 µM to 15.5 mM (R2 = 0.9842) at 0.5 V by amperometry. The sensor response time and the limit of detection were found to be 2 s and 0.6 µM for glucose. Moreover, selectivity of the NiO/MoSe2 sensor was tested in the presence of common interferent molecules such as hydrogen peroxide, fructose, lactose, ascorbic acid, uric acid, and dopamine. It was found that NiO/MoSe2/GCE did not respond to these interfering biomolecules. In addition, NiO/MoSe2/GCE had shown high stability, reproducibility and repeatability. Finally, the practical application of the sensor was demonstrated by detecting glucose in human blood serum with the acceptable recovery.

scholarly journals Paper Strip and Ceramic Potentiometric Platforms Modified with Nano-Sized Polyaniline (PANi) for Static and Hydrodynamic Monitoring of Chromium in Industrial Samples

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 629
Author(s):  
Saad S. M. Hassan ◽  
Ayman H. Kamel ◽  
Abd El-Galil E. Amr ◽  
M. Abdelwahab Fathy ◽  
Mohamed A. Al-Omar
Keyword(s):  
Limit Of Detection ◽  
Water Layer ◽  
Absorption Spectrometry ◽  
Potentiometric Sensors ◽  
Pani Film ◽  
Paper Strip ◽  
Buffer Solution ◽  
Total Chromium ◽  
Potentiometric Response ◽  
Inorganic Species

Screen-printed membrane sensors based on the use of paper and ceramic substrates are fabricated, characterized, and used for rapid batch and continuous monitoring of CrIII in the form of CrO42− in some industrial products and wastewater samples. Strips of paper and ceramic platforms (15 × 5 mm) were covered with conductive carbon paint and then modified with polyaniline (PANI) film, to act as an ion-to-electron transducer, followed by a drop casting of plasticized poly (vinyl chloride) (PVC) Rhodamine-B chromate membrane as a recognition sensing material. In a 5.0 mmol L−1 Trizma buffer solution of pH ~8, the fabricated paper and ceramic based membrane sensors exhibited a near Nernstian response for CrVI ion with slopes of −29.7 ± 0.5 and −28.6 ± 0.3 mV decade−1, limit of detection 2.5 × 10−5 and 2.4 × 10−6 mol L−1 (1.3–0.12 µg mL−1), and linear concentration range 7.5 × 10−3–5.0 × 10−5 and 7.5 × 10−3–1.0 × 10−5 mol L−1 (390-0.5 µg mL−1), respectively. Both sensors exhibited fast and stable potentiometric response, excellent reproducibility, and good selectivity with respect to a number of common foreign inorganic species. Impedance spectroscopy and chronopotentiometry data revealed a small resistance and a larger double layer capacitance due to the presence of the intermediate polyaniline (PAN) conductive layer. Furthermore, the formation of a water layer between the ion selective membrane (ISM) and the underlying conductor polymer and between the conducting polymer and the carbon conducting surface was greatly reduced. The developed disposable solid-contact potentiometric sensors offer the advantages of simple design, long term potential stability, flexibility, miniaturization ability, short conditioning time, and cost effectiveness that enable mass production. The sensors were successfully used for static and hydrodynamic measurements of total chromium in some leather tanning wastewater and nickel-chrome alloy samples. The results compare favorably with data obtained by atomic absorption spectrometry.

scholarly journals Impedimetric Determination of Kanamycin in Milk with Aptasensor Based on Carbon Black-Oligolactide Composite

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4738 ◽  
Author(s):  
Tatiana Kulikova ◽  
Vladimir Gorbatchuk ◽  
Ivan Stoikov ◽  
Alexey Rogov ◽  
Gennady Evtugyn ◽  
...  
Keyword(s):  
Carbon Black ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
3D Structure ◽  
Cationic Polyelectrolyte ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Chitosan Matrix ◽  
Negative Effect

The determination of antibiotics in food is important due to their negative effect on human health related to antimicrobial resistance problem, renal toxicity, and allergic effects. We propose an impedimetric aptasensor for the determination of kanamycin A (KANA), which was assembled on the glassy carbon electrode by the deposition of carbon black in a chitosan matrix followed by carbodiimide binding of aminated aptamer mixed with oligolactide derivative of thiacalix[4]arene in a cone configuration. The assembling was monitored by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. In the presence of the KANA, the charge transfer resistance of the inner interface surprisingly decreased with the analyte concentration within 0.7 and 50 nM (limit of detection 0.3 nM). This was attributed to the partial shielding of the negative charge of the aptamer and of its support, a highly porous 3D structure of the surface layer caused by a macrocyclic core of the carrier. The use of electrostatic assembling in the presence of cationic polyelectrolyte decreased tenfold the detectable concentration of KANA. The aptasensor was successfully tested in the determination of KANA in spiked milk and yogurt with recoveries within 95% and 115%.

scholarly journals Fabrication and evaluation of potentiometric sensors of an anticancer drug (Gemcitabine)

2020 ◽  
Vol 11 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Iyad Darweesh Al-Kashef ◽  
Salman Mostafa Saadeh ◽  
Khalid Ibrahim Abed Almonem ◽  
Nasser Mohammed Abu Ghalwa ◽  
Hazem Mohammed Abu Shawish
Keyword(s):  
Anticancer Drug ◽  
Limit Of Detection ◽  
Inorganic Ions ◽  
Potentiometric Sensors ◽  
Pvc Membrane ◽  
Carbon Paste ◽  
Curve Method ◽  
Nernstian Slope ◽  
Ph Range

Accurate, rapid and inexpensive determination of gemcitabine, an anticancer drug, is of high interest. This manuscript describes the use of potentiometric sensors as a basis for this work given their known attractive characteristics that meet our needs. Potentiometric sensors were comprised of carbon paste S1, coated wire S2 and PVC membrane S3, of gemcitabine (an anticancer drug) were fabricated, studied and evaluated. The calibration plots for these electrodes showed a Nernstian slope of 58.4±0.3, 59.5±0.3 and 58.3±0.3 mV per decade with the limit of detection: 6.50×10-5, 7.20×10-5 and 4.60×10-5 for sensors S1, S2 and S3, respectively. The electrodes have a short and stable response time of ~5 seconds and good reproducibility in a pH range of 2.5-9.5. The present sensors show distinct selectivity toward the drug ion in comparison to several inorganic ions, sugars, amino acids and some common drug excipients. Gemcitabine was determined successfully in ampoules and urine using these sensors by the calibration curve method.

scholarly journals Label-Free Electrochemical Detection of S. mutans Exploiting Commercially Fabricated Printed Circuit Board Sensing Electrodes

Micromachines ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 575 ◽  
Author(s):  
Gorachand Dutta ◽  
Abdoulie A. Jallow ◽  
Debjani Paul ◽  
Despina Moschou
Keyword(s):  
Electrochemical Detection ◽  
Printed Circuit Board ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Charge Transfer Resistance ◽  
Circuit Board ◽  
Label Free ◽  
Electrochemical Impedance Spectra ◽  
Transfer Resistance ◽  
Printed Circuit

This paper reports for the first time printed-circuit-board (PCB)-based label-free electrochemical detection of bacteria. The demonstrated immunosensor was implemented on a PCB sensing platform which was designed and fabricated in a standard PCB manufacturing facility. Bacteria were directly captured on the PCB sensing surface using a specific, pre-immobilized antibody. Electrochemical impedance spectra (EIS) were recorded and used to extract the charge transfer resistance (Rct) value for the different bacteria concentrations under investigation. As a proof-of-concept, Streptococcus mutans (S. mutans) bacteria were quantified in a phosphate buffered saline (PBS) buffer, achieving a limit of detection of 103 CFU/mL. Therefore, the proposed biosensor is an attractive candidate for the development of a simple and robust point-of-care diagnostic platform for bacteria identification, exhibiting good sensitivity, high selectivity, and excellent reproducibility.

Electrochemical Impedance Spectroscopy of Zinc Oxide Nanoparticles After Deposition on Screen Printed Electrode

2021 ◽  
Vol 21 (10) ◽  
pp. 5207-5214
Author(s):  
Kailai Wang ◽  
Wenyu Zhang ◽  
Edward P. C. Lai
Keyword(s):  
Zno Nanoparticles ◽  
Electrochemical Impedance ◽  
Aqueous Dispersion ◽  
Charge Transfer Resistance ◽  
Deionized Water ◽  
Analytical Sensitivity ◽  
Screen Printed Electrode ◽  
Transfer Resistance ◽  
Small Aliquot ◽  
Screen Printed

A small aliquot (10–14 μL) of ZnO nanoparticles dispersed in deionized water was deposited by evaporation to produce a dry residue on the working area of a screen-printed electrode. An electrochemical test solution containing K3Fe(CN)6 and KCl was added to the electrode surface for analysis by electrochemical impendence spectroscopy (EIS). Using this deposition analysis technique, a new relationship between the charge transfer resistance (Rct) and the amount of ZnO nanoparticles has been explored. Based on the trend of increasing Rct value with an increase of ZnO nanoparticles, a quantitative analysis method can be established to determine the mass of nanoparticles (0.01–1.00 μg) deposited from an unknown dispersion. To study the matrix effect, addition of Nafion solution to the aqueous dispersion resulted in a change of the linear range to 0.3–0.5 μg nanoparticles. Addition of methanol (10% by volume) to the aqueous dispersion changes the analysis range to 0.2–0.6 μg nanoparticles, while additional methanol (50% by volume) changes the analysis range to 0.06–1.00 μg nanoparticles. The analytical sensitivity, as indicated by the slope of each standard calibration curve, ranked as: aqueous dispersion > Nafion/aqueous dispersion > 10% methanol/aqueous dispersion > 50% methanol/aqueous dispersion. Altogether these results verify that deionized water is the best dispersion medium for EIS analysis of ZnO nanoparticles.

scholarly journals Electrochemical DNA Sensor Based on the Copolymer of Proflavine and Azure B for Doxorubicin Determination

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 924
Author(s):  
Anna Porfireva ◽  
Gennady Evtugyn
Keyword(s):  
Polymer Film ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Polymer Surface ◽  
Charge Transfer Resistance ◽  
Dna Sensor ◽  
Transfer Resistance ◽  
Redox Probe ◽  
Azure B

A DNA sensor has been developed for the determination of doxorubicin by consecutive electropolymerization of an equimolar mixture of Azure B and proflavine and adsorption of native DNA from salmon sperm on a polymer film. Electrochemical investigation showed a difference in the behavior of individual drugs polymerized and their mixture. The use of the copolymer offered some advantages, i.e., a higher roughness of the surface, a wider range of the pH sensitivity of the response, a denser and more robust film, etc. The formation of the polymer film and its redox properties were studied using scanning electron microscopy and electrochemical impedance spectroscopy. For the doxorubicin determination, its solution was mixed with DNA and applied on the polymer surface. After that, charge transfer resistance was assessed in the presence of [Fe(CN)6]3−/4− as the redox probe. Its value regularly grew with the doxorubicin concentration in the range from 0.03 to 10 nM (limit of detection 0.01 nM). The DNA sensor was tested on the doxorubicin preparations and spiked samples mimicking blood serum. The recovery was found to be 98–106%. The DNA sensor developed can find application for the determination of drug residues in blood and for the pharmacokinetics studies.

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