Electrochemical detection of carbidopa using a ferrocene-modified carbon nanotube paste electrode

A chemically modified carbon paste electrode (MCPE) containing ferrocene (FC) and carbon nanotubes (CNT) was constructed. The electrochemical behavior and stability of the MCPE were investigated by cyclic voltammetry. The electrocatalytic activity of the MCPE was investigated and it showed good characteristics for the oxidation of carbidopa (CD) in phosphate buffer solution (PBS). A linear concentration range of 5 to 600 μM CD, with a detection limit of 3.6±0.17 μM CD, was obtained. The diffusion coefficient of CD and the transfer coefficient () were also determined. The MCPE showed good reproducibility, remarkable long-term stability and especially good surface renewability by simple mechanical polishing. The results showed that this electrode could be used as an electrochemical sensor for the determination of CD in real samples, such as urine samples

Nanomaterials in biomedicine, drug delivery and pharmaceutical analysis

After the introduction of nanotechnology as a new science, there were tremendous changes in its application. Nanomaterials rapidly penetrate a diverse area of biomedicine and pharmaceutical research, including drug development, drug delivery, tissue engineering and medicinal chemistry. Its versatile use helps in alleviating complex difficulties faced with drug administration and absorption, controlled release, targeted delivery and cellular uptake. Due to their distinctive physico-chemical properties and ability to form various solid-state formulations, they find increased use in the preparation of new drug formulations, imaging techniques and particularly in medicinal chemistry as catalysts for the sensitive determination of drugs and other biologically active compounds. The role of nanomaterials as catalysts in the preparation of substances with pharmacological properties, the preparation of sensors, or the degradation and removal of medicinal compounds polluting the environment is undeniable

Conductometric measurements of complexation study between 4-Isopropylcalix[4]arene and Cr3+ cation in THF–DMSO binary solvents

In the present work, the conductometric measurements for complexation process between Cr3+ cation and the macrocyclic ionophore, 4-Isopropylcalix[4]arene (IPC4) were studied in tetrahydrofuran–dimethylsulfoxide (THF–DMSO) binary non-aqueous medium at different temperatures. The results reveal that the stoichiometry of the IPC4–Cr3+ complex in all binary mixed solvents is 1:1. A non-linear behavior was observed for changes of logKf of this complex versus the composition of the binary mixed solvents, which was explained on the basis of changes occurring in the structure of the mixed solvents and also the preferential solvation of the cation, ionophore and the resulting complex in the solution. The thermodynamic parameters (DH�c and DS�c) for the formation of IPC4–Cr3+ complexes were obtained from the temperature dependence of the stability constant using the van’t Hoff plots. The results obtained in this study, show that the formed complex is enthalpy destabilized, but entropy stabilized and the values of the mentioned parameters are affected strongly by the nature and composition of the binary mixed solvents. The experimental data was tested by using artificial neural network (ANN) program and was in a good agreement with the estimated data

A new nickel-based co-crystal complex electrocatalyst amplified by NiO dope Pt nanostructure hybrid; a highly sensitive approach for determination of cysteamine in the presence of serotonin.

A highly sensitive electrocatalytic sensor was designed and fabricated by the incorporation of NiO dope Pt nanostructure hybrid (NiO-Pt-H) as conductive mediator, bis (1,10 phenanthroline) (1,10-phenanthroline-5,6-dione) nickel(II) hexafluorophosphate (B,1,10,P,1,10, PDNiPF6), and electrocatalyst into carbon paste electrode (CPE) matrix for the determination of cysteamine. The NiO-Pt-H was synthesized by one-pot synthesis strategy and characterized by XRD, elemental mapping analysis (MAP), and FESEM methods. The characterization data, which confirmed good purity and spherical shape with a diameter of ⁓ 30.64 nm for the synthesized NiO-Pt-H. NiO-Pt-H/B,1,10, P,1,10, PDNiPF6/CPE, showed an excellent catalytic activity and was used as a powerful tool for the determination of cysteamine in the presence of serotonin. The NiO-Pt-H/B,1,10, P,1,10, PDNiPF6/CPE was able to solve the overlap problem of the two drug signals and was used for the determination of cysteamine and serotonin in concentration ranges of 0.003-200 µM and 0.5-260 µM with detection limits of 0.5 nM and 0.1 µM, using square wave voltammetric method, respectively. The NiO-Pt-H/B,1,10,P,1,10,PDNiPF6/CPE showed a high-performance ability for the determination of cysteamine and serotonin in the drug and pharmaceutical serum samples with the recovery data of 98.1-103.06%

Recent advances in developing optical and electrochemical sensors for analysis of methamphetamine: A review

Recognition of misused stimulant drugs has always been a hot topic from a medical and judicial perspective. Methamphetamine (MAMP) is an addictive and illegal drug that profoundly affects the central nervous system. Like other illicit drugs, the detection of MAMP in biological and street samples is vital for several organizations such as forensic medicine, anti-drug headquarters and diagnostic clinics. By emerging nanotechnology and exploiting nanomaterials in sensing applications, a great deal of attention has been given to the design of analytical sensors in MAMP tracing. For the first time, this study has briefly reviewed all the optical and electrochemical sensors in MAMP detection from earlier so far. How various receptors with engineering nanomaterials allow developing novel approaches to measure MAMP have been studied. Fundamental concepts related to optical and electrochemical recognition assays in which nanomaterials have been used and relevant MAMP sensing applications have been comprehensively covered. Challenges, opportunities and future outlooks of this field have also been discussed at the end. (C) 2021 Elsevier Ltd. All rights reserved

NiO/CNTs Nanocomposite Modified Ionic Liquid Carbon Paste Electrode as a Voltammetric Sensor for Determination of Quercetin

A high sensitive carbon paste electrode modified with NiO/CNTs and ionic liquid (ILs/NiO/CNT/CPE) was describe for voltammetric determination of quercetin. Compared to unmodified carbon paste electrode, the electrochemical response was greatly improved for quercetin electrooxidation. Result shows, the oxidation peak current was increased to about 6.5 times at the surface of ILs/NiO/CNT/CPE compared to CPE. The linear response range and detection limit were found to be 0.08–400 µM and 0.03 µM, respectively. ILs/NiO/CNT/CPE was successfully applied for the determination of quercetin in real samples such as onions, apple and capsule. The results showed that the proposed method is highly selective, sensitive with a fast response for quercetin analysis

Modified Carbon Nanotube Paste Electrode for Voltammetric Determination of Carbidopa, Folic Acid, and Tryptophan

A simple and convenient method is described for voltammetric determination of carbidopa (CD), based on its electrochemical oxidation at a modified multiwall carbon nanotube paste electrode. Under optimized conditions, the proposed method exhibited acceptable analytical performances in terms of linearity (over the concentration range from 0.1 to 700.0 μM), detection limit (65.0 nM), and reproducibility (RSD = 2.5%) for a solution containing CD. Also, square wave voltammetry (SWV) was used for simultaneous determination of CD, folic acid (FA), and tryptophan (TRP) at the modified electrode. To further validate its possible application, the method was used for the quantification of CD, FA, and TRP in urine samples

Current development and future challenges in microplastic detection techniques: a bibliometrics-based analysis and review.

Microplastics have been considered a new type of pollutant in the marine environment and have attracted widespread attention worldwide in recent years. Plastic particles with particle size less than 5 mm are usually defined as microplastics. Because of their similar size to plankton, marine organisms easily ingest microplastics and can threaten higher organisms and even human health through the food chain. Most of the current studies have focused on the investigation of the abundance of microplastics in the environment. However, due to the limitations of analytical methods and instruments, the number of microplastics in the environment can easily lead to overestimation or underestimation. Microplastics in each environment have different detection techniques. To investigate the current status, hot spots, and research trends of microplastics detection techniques, this review analyzed the papers related to microplastics detection using bibliometric software CiteSpace and COOC. A total of 696 articles were analyzed, spanning 2012 to 2021. The contributions and cooperation of different countries and institutions in this field have been analyzed in detail. This topic has formed two main important networks of cooperation. International cooperation has been a common pattern in this topic. The various analytical methods of this topic were discussed through keyword and clustering analysis. Among them, fluorescent, FTIR and micro-Raman spectroscopy are commonly used optical techniques for the detection of microplastics. The identification of microplastics can also be achieved by the combination of other techniques such as mass spectrometry/thermal cracking gas chromatography. However, these techniques still have limitations and cannot be applied to all environmental samples. We provide a detailed analysis of the detection of microplastics in different environmental samples and list the challenges that need to be addressed in the future

Voltammetric determination of hydroxylamine in water and waste water samples using a NiO nanoparticle/new catechol derivative modified carbon paste electrode

A (9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)-4-ethylbenzene-1,2-diol (DED) mo­di­fied NiO/NPs carbon paste electrode “(DED/NiO nanoparticle (NiO/NPs)/CPE) was constructed for determination of hydroxylamine (HX). The cyclic voltammogram showed that the electro­catalytic oxidation of HX at the surface of DED/NiO/NPs/CPE occurs at a potential of about 800 mV less positive than with an unmodified electrode. Square-wave voltammetry results presented that the electrocatalytic oxidation peak currents of HX in pH 8.0 had two linear dynamic ranges in the range of 0.1 to 2.0 and 2.0 to 400.0 µM HX, with a detection limit of 0.07 µM. The kinetic parameters such as electron transfer coefficient a (0.47) and rate constant (2.454 × 103 M-1 s-1) were determined for the chemical reaction between HX and DED. Finally, this method was evaluated for the determination of HX in water and waste water samples