Enzyme Cofactor Modified Electrodes

1986 ◽  
Author(s):  
Lemuel B. Wingard ◽  
Jr.
Keyword(s):  
Modified Electrodes

AFM and SEM Characterization of Chemically Modified Electrodes Based on 5-[(azulen-1-yl) methylene]-2-thioxothiazolidin-4-one

2018 ◽  
Vol 68 (12) ◽  
pp. 2799-2803
Author(s):  
Maria Daniela Pop ◽  
Oana Brincoveanu ◽  
Mihaela Cristea ◽  
George Octavian Buica ◽  
Marius Enachescu ◽  
...  
Keyword(s):  
Glassy Carbon ◽  
Roughness Parameter ◽  
Modified Electrodes ◽  
Chemically Modified Electrodes ◽  
Adhesion Properties ◽  
Chemically Modified ◽  
Controlled Potential ◽  
Constant Potential ◽  
Metal Ions Detection

Preparation and microscopy characterization of polymer modified glassy carbon electrodes based on (5-[(azulen-1-yl) methylene]-2-thioxothiazolidin-4-one (L) were reported. Atomic Force Microscopy was used to investigate the morphological and mechanical properties of the deposited polyL films onto glassy carbon. The topography images of the analyzed samples exhibited the presence of some columnar shape features onto the layer surfaces. The surface roughness of the layers deposited at constant charge calculated from topography images, increased with the more positive applied potential for controlled potential electrolysis. At different charges, the roughness parameter showed the same behavior for the layers obtained applying a constant potential without having a noticeable influence on the adhesion properties on the substrate. Analysis using scanning electron microscopy shows a relatively uniform surface arrangement of the polymer and the presence of some clusters which are disturbing the planarity. PolyL chemically modified electrodes have been used for heavy metal ions detection with best results for lead.

A Review of Voltammetric Methods for Determination of Dopamine Agonists

2020 ◽  
Vol 16 ◽  
Author(s):  
Fatma Ağin
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Biological Samples ◽  
Dopamine Agonists ◽  
Modified Electrodes ◽  
Nerve Cells ◽  
Electroanalytical Methods ◽  
Voltammetry Methods ◽  
Voltammetric Methods

Background: Dopamine agonists are useful drugs for the management of patients with Parkinson's disease in the early stages and in later stages of the disease. Parkinson's disease is a progressive neurodegenerative disease that primarily affects dopamine-producing nerve cells in the brain. They bind to dopamine receptors in nerve cells that regulate body movement and motor function. Electroanalytical methods are used in medicinal, clinical and pharmaceutical research. The voltammetry is one of the most commonly used electroanalytical methods. The aims of this review are to gather and discuss studies of voltammetric methods used in determination of dopamine agonists. Method: This review includes the use of various voltammetric methods for determination studies of dopamine agonists from pharmaceutical dosage forms and biological samples. These studies were examined in terms of used voltammetric method or methods, working electrode, buffer, pH and validation parameters. Results: Cabergoline, pramipexole, ropinirole have more studies, while bromocriptine and apomorphine have fewer studies in the literature. Differential pulse voltammetry and square wave voltammetry methods were the most applied methods for determination of dopamine agonist drugs from pharmaceuticals and biological samples. But, stripping, cyclic and lineer sweep voltammetry methods are less applied methods. In this studies, a lot of modified electrodes were developed and used to analyse of dopamine agonists. Conclusion: The voltammetric methods supply determination of therapeutic agents and/or their metabolites in clinical samples at extremely low concentrations without the necessity for the sample pre-treatment or time consuming extraction steps. Also the modified electrodes and validated voltammetric methods provide good stability, repeatability, reproducibility and high recovery for the analysis of the analyte.

Recent Progress in the Analysis of Captopril Using Electrochemical Methods: A Review

2019 ◽  
Vol 15 (3) ◽  
pp. 198-206 ◽  
Author(s):  
Sarfaraz Ahmed Mahesar ◽  
Saeed Ahmed Lakho ◽  
Syed Tufail Hussain Sherazi ◽  
Hamid Ali Kazi ◽  
Kamran Ahmed Abro ◽  
...  
Keyword(s):  
Enzyme Inhibitor ◽  
Modified Electrodes ◽  
High Sensitivity ◽  
Pharmaceutical Formulations ◽  
Inorganic Materials ◽  
Electrochemical Methods ◽  
Nano Particles ◽  
Moderate Heart Failure ◽  
Analytical Instrumentation

Background: Captopril is the synthetic dipeptide used as an angiotensin converting enzyme inhibitor. Captopril is used to treat hypertension as well as for the treatment of moderate heart failure. Analytical instrumentation and methodology plays an important role in pharmaceutical analysis. Methods: This review presents some important applications of electrochemical modes used for the analysis of captopril. So far captopril has been analyzed by using different bare and modified working electrodes with a variety of modifiers from organic and inorganic materials to various types of nano particles/materials. Results: This paper presents some of the methods which have been published in the last few years i.e. from 2003 to 2016. This review highlights the role of the analytical instrumentation, particularly electrochemical methods in assessing captopril using various working electrodes. Conclusion: A large number of studies on voltammetry noted by means of various bare and modified electrodes. Among all of the published voltammetric methods, DPV, SWV, CV and miscellaneous modes were trendy techniques used to analyze captopril in pharmaceutical formulations as well as biological samples. Electrodes modified with nanomaterials are promising sensing tools as this showed high sensitivity, good accuracy with precision as well as selectivity. In comparison to chromatographic methods, the main advantages of electrochemical methods are its cheaper instrumentation, lower detection limit and minimal or no sample preparation.

Label-Free Electrochemical Detection of DNA Hybridization Related to Anthrax Lethal Factor by using Carbon Nanotube Modified Sensors

2019 ◽  
Vol 15 (4) ◽  
pp. 502-510 ◽  
Author(s):  
Hakan Karadeniz ◽  
Arzum Erdem
Keyword(s):  
Detection Limit ◽  
Dna Hybridization ◽  
Lethal Factor ◽  
Modified Electrodes ◽  
Label Free ◽  
Carbon Paste ◽  
Chip Technology ◽  
Anthrax Lethal Factor ◽  
Hybridization Time ◽  
Electrochemical Monitoring

Background: Anthrax Lethal Factor (ANT) is the dominant virulence factor produced by B. anthracis and is the major cause of death of infected animals. In this paper, pencil graphite electrodes GE were modified with single-walled and multi-walled carbon nanotubes (CNTs) for the detection of hybridization related to the ANT DNA for the first time in the literature. Methods: The electrochemical monitoring of label-free DNA hybridization related to ANT DNA was explored using both SCNT and MCNT modified PGEs with differential pulse voltammetry (DPV). The performance characteristics of ANT-DNA hybridization on disposable GEs were explored by measuring the guanine signal in terms of optimum analytical conditions; the concentration of SCNT and MCNT, the concentrations of probe and target, and also the hybridization time. Under the optimum conditions, the selectivity of probe modified electrodes was tested and the detection limit was calculated. Results: The selectivity of ANT probes immobilized onto MCNT-GEs was tested in the presence of hybridization of probe with NC no response was observed and with MM, smaller responses were observed in comparison to full-match DNA hybridization case. Even though there are unwanted substituents in the mixture samples containing both the target and NC in the ratio 1:1 and both the target and MM in the ratio 1:1, it has been found that ANT probe immobilized CNT modified graphite sensor can also select its target by resulting with 20.9% decreased response in comparison to the one measured in the case of full-match DNA hybridization case Therefore, it was concluded that the detection of direct DNA hybridization was performed by using MCNT-GEs with an acceptable selectivity. Conclusion: Disposable SCNT/MCNT modified GEs bring some important advantages to our assay including easy use, cost-effectiveness and giving a response in a shorter time compared to unmodified PGE, carbon paste electrode and glassy carbon electrode developed for electrochemical monitoring of DNA hybridization. Consequently, the detection of DNA hybridization related to the ANT DNA by MCNT modified sensors was performed by using lower CNT, probe and target concentrations, in a shorter hybridization time and resulting in a lower detection limit according to the SCNT modified sensors. In conclusion, MCNT modified sensors can yield the possibilities leading to the development of nucleic acid sensors platforms for the improvement of fast and cost-effective detection systems with respect to DNA chip technology.

Electroanalysis of Catecholamine Drugs using Graphene Modified Electrodes

2019 ◽  
Vol 15 (4) ◽  
pp. 443-466 ◽  
Author(s):  
Mahya Karami Mosammam ◽  
Mohammad Reza Ganjali ◽  
Mona Habibi-Kool-Gheshlaghi ◽  
Farnoush Faridbod
Keyword(s):  
Electrochemical Sensors ◽  
Modified Electrodes ◽  
Electrochemical Methods ◽  
High Signal ◽  
Signal To Noise ◽  
Low Level ◽  
Biological Studies

Background: Catecholamine drugs are a family of electroactive pharmaceutics, which are widely analyzed through electrochemical methods. However, for low level online determination and monitoring of these compounds, which is very important for clinical and biological studies, modified electrodes having high signal to noise ratios are needed. Numerous materials including nanomaterials have been widely used as electrode modifies for these families during the years. Among them, graphene and its family, due to their remarkable properties in electrochemistry, were extensively used in modification of electrochemical sensors. Objective: In this review, working electrodes which have been modified with graphene and its derivatives and applied for electroanalyses of some important catecholamine drugs are considered.

Electroanalysis of Tricyclic Psychotropic Drugs using Modified Electrodes

2019 ◽  
Vol 15 (4) ◽  
pp. 423-442 ◽  
Author(s):  
Mona Habibi-Kool-Gheshlaghi ◽  
Farnoush Faridbod ◽  
Mahya Karami Mosammam ◽  
Mohammad Reza Ganjali
Keyword(s):  
Psychotropic Drugs ◽  
Analytical Methods ◽  
Electrochemical Techniques ◽  
Modified Electrodes ◽  
Electroanalytical Methods ◽  
Drug Assays ◽  
Medical Importance ◽  
Tricyclic Rings ◽  
Easy Operation

Background: Tricyclic psychotropic drugs are defined as a tricyclic rings of the dibenzazepine group with the presence of sulfur and nitrogen atoms. They have been prescribed for antidepressive therapy over the years. Due to their medical importance, many analytical methods have been developed for their monitoring. However, benefits of electrochemical techniques such as costeffectiveness, fast, easy operation and non-destructiveness make them appropriate analytical methods for drug assays. Electrochemical determinations of pharmaceuticals require suitable working electrodes. During years, many electrodes are modified by a variety of modifiers and several sensors were developed based on them. In this regard, nanomaterials, due to their remarkable properties, are one of the most important choices. Objective: Here, the application of electroanalytical methods in the determination of electroactive tricyclic psychotropic drugs will be reviewed and the nanomaterials which are used for improvements of the working electrodes will be considered.

scholarly journals Ultrasensitive and label free electrochemical immunosensor for detection of ROR1 as an oncofetal biomarker using gold nanoparticles assisted LDH/rGO nanocomposite

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rozita Abolhasan ◽  
Balal Khalilzadeh ◽  
Hadi Yousefi ◽  
Sahar Samemaleki ◽  
Forough Chakari-Khiavi ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Flexible Structures ◽  
Modified Electrodes ◽  
Electrochemical Immunosensor ◽  
Lymphocytic Leukemia ◽  
Orphan Receptor ◽  
Detection Sensitivity ◽  
Label Free ◽  
Serum Samples ◽  
Limit Of Quantification

AbstractIn the present article, we developed a highly sensitive label-free electrochemical immunosensor based on NiFe-layered double hydroxides (LDH)/reduced graphene oxide (rGO)/gold nanoparticles modified glassy carbon electrode for the determination of receptor tyrosine kinase-like orphan receptor (ROR)-1. In this electrochemical immunoassay platform, NiFe-LDH/rGO was used due to great electron mobility, high specific surface area and flexible structures, while Au nanoparticles were prepared and coated on the modified electrodes to improve the detection sensitivity and ROR1 antibody immobilizing (ROR1Ab). The modification procedure was approved by using cyclic voltammetry and differential pulse voltammetry based on the response of peak current to the step by step modifications. Under optimum conditions, the experimental results showed that the immunosensor revealed a sensitive response to ROR1 in the range of 0.01–1 pg mL−1, and with a lower limit of quantification of 10 attogram/mL (10 ag mL−1). Furthermore, the designed immunosensor was applied for the analysis of ROR1 in several serum samples of chronic lymphocytic leukemia suffering patients with acceptable results, and it also exhibited good selectivity, reproducibility and stability.

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