Polymethionine modified carbon nanotube sensor for sensitive and selective determination of L-tryptophan

The electrochemically initiated catalytic oxidation of amino acid L-tryptophan (L-TPN) in phosphate buffer solution has been scrutinized using highly conductive polymethionine modified carbon nanotube paste sensor (PMETCNTPS) through cyclic voltammetry (CV) technique. Compared to the bare carbon nanotube paste sensor (BCNTPS), PMETCNTPS exhibited a quantifiable current signal by CV method. PMETCNTPS was found sensitive to L-TPN concentrations within the linear segment of detection range 1.5 - 8.0×10-5 M. By employing the calibration plot, the detection limit was determined as 6.99×10-7 M. In addition, PMETCNTPS was successfully exploited and validated in determining L-TPN in the pharmaceutical supplement.</p

Enhanced voltammetric detection of paracetamol by using carbon nanotube modified electrode as an electrochemical sensor

New aspects associated with electro-catalytic activity of poly(methyl orange) modified carbon nanotube paste electrode (PMMCNTPE)towards the detection of paracetamol (PC) which is typically used worldwide as a pain reliever, were explored through implementation of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Bare carbon nanotube paste electrode (BCNTPE) was modified by methyl orange using the electropolymerizing method. The effect of pH and influence of potential scan rate were resolved by means of CV technique. It was found that under optimized experimental conditions, PMMCNTPE imparts the analytical curve for PC in the concentration range of 2.0×10-6 – 5.0×10-5 M with detection limit of 3.8×10-8 M and limit of quantification of 1.2×10-8 M. The proposed sensor exhibited acceptable reproducibility, admirable stability, and adequate repeatability. The interference study of PC with dopamine (DA) and folic acid (FA) showed good selectivity of the designed sensor. The feasibility of the constructed electrochemical sensor to detect PC was successfully tested in some pharmaceutical formulations

Research developments in carbon materials based sensors for determination of hormones

Various carbon-based sensors (graphene, carbon nanotubes, graphite, pencil graphite, glassy carbon, etc.) have distinctive behavior and a broad range of importance for identifying sex hormones like estriol, estradiol, estrone, progesterone, and testosterone. The current review emphasizes voltammetric, amperometric, and electrochemical impedance spectroscopic methods for detecting some of these hormones. The existence, structural aspects, nature, and biological importance of each hormone were analyzed in detail and their analysis with different electroanalytical methods was considered. Unique methodologies and innovations of electrochemical sensors for hormones based on carbon materials modified by different agents were examined. In this review, the interaction among various sensor materials and analytes in different supporting electrolyte media is premeditated. The most important significances of the electroanalytical methodologies were discussed based on sensor selectivity, sensitivity, stability, the limit of detection, repeatability, and reproducibility

Research developments in carbon materials based sensors for determination of hormones

Various carbon-based sensors (graphene, carbon nanotubes, graphite, pencil graphite, glassy carbon, etc.) have distinctive behavior and a broad range of importance for identifying sex hormones like estriol, estradiol, estrone, progesterone, and testosterone. The current review emphasizes voltammetric, amperometric, and electrochemical impedance spectroscopic methods for detecting some of these hormones. The existence, structural aspects, nature, and biological importance of each hormone were analyzed in detail and their analysis with different electroanalytical methods was considered. Unique methodologies and innovations of electrochemical sensors for hormones based on carbon materials modified by different agents were examined. In this review, the interaction among various sensor materials and analytes in different supporting electrolyte media is premeditated. The most important significances of the electroanalytical methodologies were discussed based on sensor selectivity, sensitivity, stability, the limit of detection, repeatability, and reproducibility

Electrochemical analysis of indigo carmine using polyarginine modified carbon paste electrode

Suitable electrocatalytic method is established for the selective determination of indigo carmine (IC) at polyarginine modified carbon paste electrode (PAMCPE). Surface morphological study of bare carbon paste electrode (CPE) and PAMPCE is done by field emission scanning electron microscopy (FESEM). The influence of different parameters such as IC concentration, solution pH and potential scan rate on the electrode responses is studied using cyclic and differential pulse voltammetry techniques. The prepared PAMCPE shows better electrochemical response towards IC than CPE. No interference is noticed at simultaneous presence of IC and riboflavin (RF) in the solution. The electrocatalytic current of IC at PAMPCE is varied linearly with its concentration in two separate ranges, from 2×10-7 to 10-6 M, and 1.5×10-6 to 3.5×10-6 M. Limits of detection (LOD) and quantification (LOQ) are determined as 2.53×10-8 and 8.43×10-8 M, respectively. The developed PAMCPE is showing successful reproducibility and stability. It is also found sensitive and reliable for trace amounts of IC in some real water and food samples. Since preparation of PAMCPE sensor is simple and easy, it could become a part of the standard method for determination of IC in real samples

Poly (DL-valine) electro-polymerized carbon nanotube paste sensor for determination of antihistamine drug cetirizine

Poly (DL-valine) modified multiwalled carbon nanotube paste sensor (PVLMCNTPS) was prepared by electro-polymerization route. PVLMCNTPS and bare multiwalled carbon nanotube paste sensor (BMCNTPS) morphologies and sensing properties for cetirizine (CTZ) were confirmed through a field emission scanning electron microscope (FE-SEM) and electrochemical studies, respectively. In contrast to BMCNTPS, PVLMCNTPS surface composite creates an electrocatalytic impact on the oxidation of CTZ. PVLMCNTPS properties were optimized using parameters such as accumulation time, number of polymerization cycles, solution pH, and scan rate. The optimized PVLMCNTPS was applied for the determination of cetirizine in 0.1 M phosphate buffer solution (PBS) of pH 7.0, using cyclic voltammetry (CV). It is shown that PVLMCNTPS provided analytical linearity from 2.0 to 80 µM, with a detection limit of 0.11 µM for CTZ determination. PVLMCNTPS is found highly selective for CTZ in presence of some interfering organic molecules. The stable and selective PVLMCNTPS was applied for CTZ determination in pharmaceutical pills with satisfactory results

Fabrication of Efficient and Selective Modified Graphene Paste Sensor for the Determination of Catechol and Hydroquinone

An electrochemical sensor, based on a graphene paste electrode (GPE), was modified with a polymerization method, and the electrochemical behavior of catechol (CC) and hydroquinone (HQ) was investigated using electroanalytical methods like cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The effect of CC at the modified electrode was evidenced by the positive shift of the oxidation peak potential of CC at the poly (rosaniline)-modified graphene paste electrode (PRAMGPE) and the nine-fold enhancement of the peak current, as compared to a bare graphene paste electrode (BGPE). The sensitivity of CC investigated by DPV was more sensitive than CV for the analysis of CC. The DPV method showed the two linear ranges of 2.0 &times; 10&minus;6&ndash;1.0 &times; 10&minus;5 M and 1.5 &times; 10&minus;5&ndash;5 &times; 10&minus;5 M. The detection limit and limit of quantification were determined to be 8.2 &times; 10&minus;7 and 27.6 &times; 10&minus;7 M, respectively. The obtained results were compared successfully with respect to those obtained using the official method. Moreover, this sensor is applied for the selective determination of CC in the presence of HQ. The high sensitivity, good reproducibility, and wide linear range make the modified electrode suitable for the determination of CC in real samples. The practical application of the sensor was demonstrated by determining the concentration of CC in water samples with acceptable recoveries (97.5&ndash;98%)

Surfactant modified carbon nanotube paste electrode for the sensitive determination of mitoxantrone anticancer drug

Surfactant modified carbon nanotube paste electrode is prepared as electrochemical sensor with high sensitivity in responding to Mitoxantrone (MTX). Electrochemical oxidation of MTX is investigated in buffered solution by cyclic voltammetry that is found very sensitive method for detection of MTX. It is shown that the sodium dodecyl sulfate modified carbon nanotube paste electrode (SDSMCNTPE) gives enhanced current response for MTX compared to the bare carbon nanotube paste electrode (BCNTPE). Different parameters were tested to optimize the conditions for MTX determination. The effects of different surfactant and surfactant concentration, pH, scan rate, detection limit (LOD), limit of quantification (LOQ) and concentration of MTX on the oxidation peak current values were determined. Excellent results were obtained by cyclic voltammetry using SDSMCNTPE, where two MTX oxidation peaks appeared at 367 and 596 mV vs. SCE. Detailed analysis of the second voltammetric peak showed the linear dynamic range between 2×10−7 and 7×10−6 M MTX with the slope of co-relation coefficient of 0.99271. LOD and LOQ were determined as 3.5 ×10−8 M and 11×10−8 M, respectively. The SDSMCNTPE showed very good reproducibility, high stability in its voltammetric response, high electrochemical sensitivity and low detection limit for MTX

Carbon-Based Composite Materials for Electrodes

Carbon-Based Composite Materials for Electrodes is a new open Special Issue of Materials, which has the goal of publishing original research and review articles focused on carbon nanotubes, graphene, activated carbon, graphite, pencil graphite, graphene oxide, graphene nanoplatelets, pyrolytic graphite, organic mass derived carbon, fullerenes, diamond, glassy carbon, carbon fibers, and other composites for electrode preparation and its applications [...

An overview of recent developments of carbon-based sensors for the analysis of drug molecules

This review summarizes some recent developments in the fabrication of modified sensors and biosensors using carbon-based materials. The great potential of carbon-based electrodes as sensing platforms is exciting due to their unique electrical and chemical properties, high accessibility and high biocompatibility. Carbon-based materials are particularly interesting due to almost infinite possibility of their functionalization with a wide variety of organic molecules, biologically important compounds and pharma­ceuticals. This review is specifically focused on recent developments in the utilization of various carbon-based electrodes as sensing devices for the electrochemical investigation of drug molecules. Various voltammetric techniques considered in this effort include linear sweep voltammetry (LSV), cyclic voltammetry (CV), differential pulse voltammetry (DPV), square wave voltam­metry (SWV), and square wave adsorptive stripping voltammetry (SWAdSV). The carbon-based electrode materials considered in this review comprise carbon paste, carbon nanotubes, graphite, graphene, and glassy carbon. The analytes chosen are some routinely used drugs such as paracetamol (PC), diclofenac sodium (DCF), 5-fluorouracil (5-FU), cetirizine (CTZ) and salbutamol (SAL). All here reported sensing electrodes produced very good results in electrochemical investigations of these drug molecules