scholarly journals Electrocomposite Developed with Chitosan and Ionic Liquids Using Screen-Printed Carbon Electrodes Useful to Detect Rutin in Tropical Fruits

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2934
Author(s):  
Lili Muñoz ◽  
Verónica Arancibia ◽  
Olimpo García-Beltrán ◽  
Edgar Nagles ◽  
John Hurtado
Keyword(s):  
Modified Electrode ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Stripping Voltammetry ◽  
Carbon Electrodes ◽  
Tropical Fruits ◽  
Relative Standard ◽  
Biological Compounds ◽  
Constant Potential ◽  
The Stability

This work reports the development of a composite of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BP4) and chitosan (CS) described in previous reports through a new method using cyclic voltammetry with 10 cycles at a scan rate of 50.0 mV s−1. This method is different from usual methods such as casting, deposition, and constant potential, and it allows the development of an electroactive surface toward the oxidation of rutin by stripping voltammetry applied to the detection in tropical fruits such as orange, lemon, and agraz (Vaccinium meridionale Swartz), with results similar to those reported in previous studies. In addition, the surface was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and Raman spectroscopy. The limit of detection was 0.07 µmol L−1 and the relative standard deviation (RSD) of 10 measurements using the same modified electrode was 0.86%. Moreover, the stability of the sensor was studied for six days using the same modified electrode, where the variation of the signal using a known concentration of rutin (RT) was found to be less than 5.0%. The method was validated using a urine chemistry control spiked with known amounts of RT and possible interference was studied using ten substances including organic and biological compounds, metal ions, and dyes. The results obtained in this study demonstrated that this electrodeveloped composite was sensitive, selective, and stable.

scholarly journals A DNA biosensor for molecular diagnosis of <i>Aeromonas hydrophila</i> using zinc sulfide nanospheres

2017 ◽  
Vol 6 (2) ◽  
pp. 259-267 ◽  
Author(s):  
Masoud Negahdary ◽  
Mahnaz Jafarzadeh ◽  
Roya Rahimzadeh ◽  
Ghasem Rahimi ◽  
Hamideh Dehghani
Keyword(s):  
Zinc Sulfide ◽  
Aeromonas Hydrophila ◽  
Pathogenic Bacteria ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Dna Biosensor ◽  
Electrochemical Measurements ◽  
Dna Biosensors ◽  
Relative Standard ◽  
Constant Potential

Abstract. Today, identification of pathogenic bacteria using modern and accurate methods is inevitable. Integration in electrochemical measurements with nanotechnology has led to the design of efficient and sensitive DNA biosensors against bacterial agents. Here, efforts were made to detect Aeromonas hydrophila using aptamers as probes and zinc sulfide (ZnS) nanospheres as signal enhancers and electron transfer facilitators. After modification of the working electrode area (in a screen-printed electrode) with ZnS nanospheres through electrodeposition, the coated surface of a modified electrode with ZnS nanospheres was investigated through scanning electron microscopy (SEM). The size of synthesized ZnS nanospheres was estimated at about 20–50 nm and their shape was in the form of porous plates in microscopic observations. All electrochemical measurements were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and constant potential amperometry (CPA) techniques. The designed DNA biosensor was able to detect deoxyribonucleic acid (DNA) of Aeromonas hydrophila in the range 1.0  ×  10−4 to 1.0  ×  10−9 mol L−1; the limit of detection (LOD) in this study was 1  ×  10−13 mol L−1. This DNA biosensor showed satisfactory thermal and pH stability. Reproducibility for this DNA biosensor was measured and the relative standard deviation (RSD) of the performance of this DNA biosensor was calculated as 5 % during 42 days.

A Facile In-Situ Development of L-Valine Film onto the Surface of Carbon Paste Electrode Towards the Detection of Environmentally Hazardous 4-Amino Phenol

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
T. Venu Gopal ◽  
Tukiakula Madhusudana Reddy ◽  
P. Shaikshavali ◽  
G. Venkataprasad ◽  
P. Gopal
Keyword(s):  
Cyclic Voltammetry ◽  
Carbon Paste Electrode ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Small Scale ◽  
Carbon Paste ◽  
Relative Standard ◽  
Paste Electrode

Abstract A small scale of environmentally hazardous 4-aminophenol can show significant impact on human health. Hence, in the present work, we have designed L-Valine film (Vf) modified carbon paste electrode (Vf/CPE) for the determination of 4-aminophenol. Herein, a facile in-situ L-Valine film was developed by electrochemical polymerization method onto the surface of bare carbon paste electrode (BCPE) with the help of cyclic voltammetry (CV) technique. A two-folds of electrochemical peak current enhancement was achieved at Vf/CPE in comparison with BCPE towards the determination of 4-aminophenol in optimum pH 7.0 of phosphate buffer solution (PBS). This was achieved due to the large surface area and conductive nature of Vf/CPE, which was concluded through the techniques of cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The effect of pH of buffer and scan rate studies were successfully studied. Morphological changes of BCPE and Vf/CPE was studied with the help of scanning electron microscopy (SEM). The formation of Vf on CPE was also analyzed by Fourier transform infrared (FTIR) spectra. Under the optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) values of 4-aminophenol were estimated with the aid of chronoamperometry (CA) technique and was found to be 9.8 μM and 32 μM, respectively. Finally the proposed method was found to have satisfactory repeatability, reproducibility and stability results with low relative standard deviation (RSD) values.

scholarly journals Sensitive and Selective Electrochemical Detection of Epirubicin as Anticancer Drug Based on Nickel Ferrite Decorated with Gold Nanoparticles

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1334
Author(s):  
Mohammad Mehmandoust ◽  
Nevin Erk ◽  
Ceren Karaman ◽  
Fatemeh Karimi ◽  
Sadegh Salmanpour
Keyword(s):  
Electron Microscopy ◽  
Gold Nanoparticles ◽  
Nickel Ferrite ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Differential Pulse ◽  
X Ray ◽  
Transmission Electron ◽  
The Stability ◽  
Electrochemical Electrode

The accurate and precise monitoring of epirubicin (EPR), one of the most widely used anticancer drugs, is significant for human and environmental health. In this context, we developed a highly sensitive electrochemical electrode for EPR detection based on nickel ferrite decorated with gold nanoparticles (Au@NiFe2O4) on the screen-printed electrode (SPE). Various spectral characteristic methods such as Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), energy-dispersive X-ray spectroscopy (EDX) and electrochemical impedance spectroscopy (EIS) were used to investigate the surface morphology and structure of the synthesized Au@NiFe2O4 nanocomposite. The novel decorated electrode exhibited a high electrocatalytic activity toward the electrooxidation of EPR, and a nanomolar limit of detection (5.3 nM) was estimated using differential pulse voltammetry (DPV) with linear concentration ranges from 0.01 to 0.7 and 0.7 to 3.6 µM. The stability, selectivity, repeatability reproducibility and reusability, with a very low electrode response detection limit, make it very appropriate for determining trace amounts of EPR in pharmaceutical and clinical preparations.

scholarly journals Multifunctional Gold Nano-Cytosensor With Quick Capture, Electrochemical Detection, and Non-Invasive Release of Circulating Tumor Cells for Early Cancer Treatment

2021 ◽  
Vol 9 ◽  
Author(s):  
Rui Zhang ◽  
Qiannan You ◽  
Mingming Cheng ◽  
Mingfeng Ge ◽  
Qian Mei ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Circulating Tumor Cells ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Treatment Options ◽  
Metastatic Tumor ◽  
Quantitative Detection ◽  
Cell Capture ◽  
Primary Tumors ◽  
Relative Standard

Circulating tumor cells (CTCs) are metastatic tumor cells that shed into the blood from solid primary tumors, and their existence significantly increases the risk of metastasis and recurrence. The timely discovery and detection of CTCs are of considerable importance for the early diagnosis and treatment of metastasis. However, the low number of CTCs hinders their detection. In the present study, an ultrasensitive electrochemical cytosensor for specific capture, quantitative detection, and noninvasive release of EpCAM-positive tumor cells was developed. The biosensor was manufactured using gold nanoparticles (AuNPs) to modify the electrode. Three types of AuNPs with controllable sizes and conjugated with a targeting molecule of monoclonal anti-EpCAM antibody were used in this study. Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) of the cytosensors were performed to evaluate the cell capture efficiency and performance. The captured 4T1 cells by the AuNPs hindered electron transport efficiency, resulting in increased EIS responses. The cell capture response recorded using EIS or DPV indicated that the optimal AuNPs size should be 17 nm. The cell capture response changed linearly with the concentration range from 8.0 × 10 to 1 × 107 cells/mL, and the limit of detection was 50 cells/mL. After these measurements, glycine-HCl (Gly-HCl) was used as an antibody eluent to destroy the binding between antigen and antibody to release the captured tumor cells without compromising their viability for further clinical research. This protocol realizes rapid detection of CTCs with good stability, acceptable assay precision, significant fabrication reproducibility with a relative standard deviation of 2.09%, and good recovery of cells. Our results indicate that the proposed biosensor is promising for the early monitoring of CTCs and may help customize personalized treatment options.

scholarly journals Development Method for Spectrophotometric Analysis of Sulfamethoxazole Using Vanilline Reagent

2020 ◽  
pp. 41-49
Author(s):  
Nidhal Sher Mohammed ◽  
Theia'a N. Al- Sabha ◽  
Payman Abdul- Jabar
Keyword(s):  
Acidic Medium ◽  
Limit Of Detection ◽  
Accurate Method ◽  
Spectrophotometric Analysis ◽  
Schiff’S Base ◽  
Development Method ◽  
Spectrophotometric Methods ◽  
Relative Standard ◽  
The Stability ◽  
Concentration Levels

This study involves a development method for spectrophotometric analysis of sulfamethoxazole (SMZ) with vanillin reagent in acidic medium. The reaction mechanism was proposed by Schiff's base reaction of the amine group in SMZ with the carbonyl group in vanillin. The spectrum of SMZ complex showed high absorbance at 399.09 nm following the Beer–Lambert law in the concentration levels ranging from 5 to 80 µg.mL-1 with good sensitivity. The stability constant of the product was determined. The values of relative standard deviation (≤ 6.63) and recovery (> 98.73%) indicated a reasonably precise and accurate method with a good limit of detection and quantification. The present method was compared with other spectrophotometric methods in the literature. The procedure of the method showed to be simple since no need for temperature control and solvent extraction. The suggested method was used to determine of SMZ in commercial pharmaceutical drops and compared with the certified method.

Validated stability indicating HPLC method to quantify lamivudine and dolutegravir in tablets

2020 ◽  
Vol 11 (4) ◽  
pp. 5082-5088
Author(s):  
Rama Kumar Kandula ◽  
Raja Sundararajan
Keyword(s):  
Limit Of Detection ◽  
Hplc Method ◽  
Array Detector ◽  
Limit Of Quantification ◽  
Method Performance ◽  
Therapy Regimen ◽  
Stability Indicating ◽  
Stability Indicating Method ◽  
Relative Standard ◽  
The Stability

Dovato tablets (lamivudine and dolutegravir combination) are full therapy regimen for the Type 1 human immunodeficiency virus (HIV-1) infection in adults without history of antiretroviral therapy. The aim of present research focused on development of validated stability indicating method for the quantification of lamivudine and dolutegravir in combined dosage form.The separation was achieved on a Cosmicsil C18 column. The mobile phase consisted of 0.1% orthophosphoric acid (pH 3.5) – acetonitrile (50:50, v/v). Photodiode array detector was used to detect the analytes at 258 nm. The method performance was validated in compliance with the recommendations of the International Conference on Harmonization.The method was validated with selectivity, limit of detection (0.262 μg/ml for lamivudine and 0.238 μg/ml for dolutegravir), linearity (150-450 μg/ml for lamivudine and 25-75 μg/ml for dolutegravir), limit of quantification (0.874 μg/ml for lamivudine and 0.793 μg/ml for dolutegravir), accuracy (percent recovery was nearer to 100%), precision (percent relative standard deviation was less than 2.0%) and robustness (system suitability values are within limits). The stability indicating method was performed by under the various stress conditions. Degradants did not interfere with lamivudine and dolutegravir detection. The developed method can suggest that quantification of lamivudine and dolutegravir in quality control of analytical laboratories.

Electrochemical Reduction of 6-Benzylaminopurine at Mercury Electrodes and Its Analytical Application

2003 ◽  
Vol 68 (6) ◽  
pp. 1076-1093 ◽  
Author(s):  
Danuše Tarkowská ◽  
Milan Kotouček ◽  
Karel Doležal
Keyword(s):  
Electrochemical Behaviour ◽  
Reduction Process ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Exchange Chromatography ◽  
Spectrometric Analysis ◽  
Relative Standard ◽  
Essential Components ◽  
Constant Potential

The commercial exploitation of modern, in vitro plant micropropagation methods, featuring synthetic cytokinins as essential components of the cultivation media, is rapidly increasing. Thus, development of rapid, inexpensive and less labour-intensive methods for monitoring cytokinin levels could help to optimise media consumption and reduce costs. Therefore, we studied the electrochemical behaviour of the highly active and widely used cytokinin, 6-benzylaminopurine (BAP), in aqueous solutions by DC polarography, cyclic and differential pulse voltammetry and constant potential coulometry. The BAP molecule undergoes a six-electron irreversible reduction process that starts with four-electron reduction of the protonated pyrimidine skeleton. As a result of elimination of the amine from the side chain, the N1=C6 electrochemically active bond is re-established and the last two-electron step follows. The intermediates of constant potential electrolysis were identified using mass spectrometric analysis. The dissociation constant (pKa) of BAP was found, spectrophotometrically, to be 4.16. BAP concentrations were measured using two voltammetric techniques, fast-scan differential pulse (FSDPV) and adsorptive stripping voltammetry (AdSV). The relative standard deviations for these two methods were lower than 4.5% (c < 28.7 ng ml-1) and 1.2% (c < 20 ng ml-1), while the detection limits were 7.88 and 0.80 ng ml-1, respectively. Using these techniques, BAP was determined in two types of nutrition media used for the micropropagation of plants in vitro (Gerbera and banana media). In the case of media samples containing the interfering agent adenine (i.e. Gerbera plant medium), the analyte was preconcentrated by ion-exchange chromatography and immunoaffinity chromatography. This preconcentration process gives 92% recovery. In contrast, it was possible to determine BAP levels in simple banana cultivation medium directly, without any pre-purification process. Both methods, reported here (FSDPV and AdSV), were found to be useful for rapidly monitoring BAP consumption by plants during their growth under in vitro conditions.

scholarly journals Determination of Lead Desorption from G. fisheri Seaweed Using Edible Eluents by Voltammetry at the Hanging Mercury Drop Electrode

2016 ◽  
Vol 855 ◽  
pp. 3-8 ◽  
Author(s):  
Charuwan Khamkaew ◽  
Sontaya Manaboot
Keyword(s):  
Deposition Time ◽  
Ethylenediaminetetraacetic Acid ◽  
Limit Of Detection ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Hanging Mercury Drop Electrode ◽  
Mercury Drop Electrode ◽  
Desorption Efficiency ◽  
Relative Standard

A simple, rapid, selective and sensitivity approach for the determination of Pb(II) in G. fisheri seaweed is described. The method is based on differential pulse anodic stripping voltammetry (DPASV) at hanging mercury drop electrode (HMDE) vs. Ag/AgCl in 0.2 M ammonium acetate (NH4OAc) pH 7.5. The operating analytical conditions; deposition potential (Edep) of -0.4 V, peak potential of -0.78 V, and mercury dropped size of 3 were performed. To see the sensitivity of Pb(II) measurement, the influences of deposition time and stirring speed were investigated. From the findings, the optimal parameters; deposition time of 90 s, and stirring speed of 2000 rpm were obtained. In these conditions, the limit of detection (3σ) of 0.60 µgL-1 and the linear range extended to 12.50 µgL-1 (r2=0.9999) were obtained. The relative standard deviation (RSD) of triplicate measurements using 1.8 µgL-1 of Pb(II) was 1.22%. The method was then applied to measure Pb(II) in real samples. In this study, the desorption efficiency of edible eluents by batch method was determined. The method is based on Pb(II) desorption using different types of edible eluents; acetic acid (HOAc), citric acid (CTA), sodium chloride (NaCl), sodium bicarbonate (NaHCO3), ethylenediaminetetraacetic acid (EDTA), and chitosan (CTS). Batch desorption of Pb(II) from seaweed soaked in individual eluent was performed by shaking at 100 rpm for 2 h at ambient temperature. Results show that the most effective eluent in desorbing the contaminated Pb(II) from G. fisheri with up to 82% of desorption efficiency for bound Pb(II) was EDTA solution.

scholarly journals Surface Enhanced CdSe/ZnS QD/SiNP Electrochemical Immunosensor for the Detection of Mycobacterium Tuberculosis by Combination of CFP10-ESAT6 for Better Diagnostic Specificity

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 149 ◽  
Author(s):  
Noremylia Mohd Bakhori ◽  
Nor Azah Yusof ◽  
Jaafar Abdullah ◽  
Helmi Wasoh ◽  
Siti Khadijah Ab Rahman ◽  
...  
Keyword(s):  
Modified Electrode ◽  
Limit Of Detection ◽  
Active Surface ◽  
Differential Pulse ◽  
Electrochemical Immunosensor ◽  
Enzyme Linked Immunosorbent Assay ◽  
Active Surface Area ◽  
High Electron ◽  
Relative Standard ◽  
Antigen Antibody

In this study, an electrochemical immunosensor was introduced for the detection of tuberculosis (TB) via utilization of a modified electrode containing a quantum dot (CdSe/ZnS QD) and functionalized silica nanoparticles (SiNPs) on screen-printed carbon electrode (SPCE) CdSe/ZnS QD/SiNPs/SPCE, by employing indirect enzyme-linked immunosorbent assay (ELISA). Here, the fabricated electrode was linked to the biocatalytic action of enzyme catalase through antigen–antibody binding for the detection of the antigen (CFP10–ESAT6) by means of producing a differential pulse voltammetry (DPV) current. The characterization and cyclic voltammetry (CV) of the modified electrode showed good electrochemical behavior and enhanced high electron transfer between the electrode and analyte. Moreover, the active surface area was 4.14-fold higher than the bare SPCE. The developed method showed high selectivity towards CFP10–ESAT6 compared with the other TB proteins. The detection of CFP10–ESAT6 also showed a linear response towards different concentrations of CFP10–ESAT6 with R2 = 0.9937, yielding a limit of detection (LOD) of as low as 1.5 × 10−10 g/mL for a linear range of 40 to 100 ng/mL of CFP10–ESAT6 concentration. The proposed method showed good reproducibility of target analyte with a relative standard deviation of 1.45%.

scholarly journals Voltammetric Determination of Uric Acid in Clinical Serum Samples Using DMF Modified Screen Printed Carbon Electrodes

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Melaku Metto ◽  
Samrawit Eramias ◽  
Bekele Gelagay ◽  
Alemayehu P. Washe
Keyword(s):  
Uric Acid ◽  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Clinical Samples ◽  
Carbon Electrodes ◽  
Current Response ◽  
Serum Samples ◽  
Relative Standard ◽  
Screen Printed

Screen printed carbon electrodes (SPCEs) provide attractive opportunity for sensitive and selective determination target analytes in clinical samples. The aim of the current work was to develop SPCEs based sensor for the determination of uric acid in clinical serum samples. The electrodes were pretreated by soaking in N,N-dimethylformamide for 5 minutes followed by drying in an oven at 100°C for 20 mins. The effect of surface pretreatment was characterized using cyclic voltammetry. The current response of uric acid detection was improved by a factor of 3.5 in differential pulse voltammetric measurement compared to unmodified electrode. Under the optimized conditions, the sensor displayed two dynamic linear ranges 5-100 μM and 100-500 μM with correlation coefficient, R2, values of 0.98782 and 0.97876, respectively. The limit of detection and limit of quantification calculated using the dynamic linear range 5-100 μM were 1.9 x 10−7 M and 6.33 x 10−7 M, respectively. The developed sensor displayed well separated and discerned peaks for UA in presence of the potential interferent (ascorbic acid and citric acid). The electrode was successfully applied for the detection of very low level of UA in clinical serum samples in a phosphate buffer solution (pH = 7). The proposed sensor showed a very high reproducibility and repeatability with the relative standard deviation of 0.9%. In conclusion, a simple and low cost sensor based on SPCEs is developed for sensitive and selective detection of uric acid in clinical samples.

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