Showing papers on "Differential pulse voltammetry published in 2018"

Nonenzymatic electrochemical sensor based on CuO-TiO2 for sensitive and selective detection of methyl parathion pesticide in ground water

Abstract: Detection of pesticides in ground water has become a very important and crucial research area due to the rapid expansion of agriculture and stringent environmental protection acts. In this paper, the as-prepared CuO-TiO 2 hybrid nanocomposites were decorated on the glass carbon electrode as the nonenzymatic electrochemical nanosensor for the sensitive and selective detection of methyl parathion. The electrochemical behavior of the modified electrode was investigated by cyclic voltammetry, showing that the modified electrode can be used for methyl parathion detection. Differential pulse voltammetry was applied to evaluate methyl parathion detection ability under optimized experimental conditions, and found the modified electrode can detect methyl parathion sensitively in a wide dynamic detection range from 0 ppb to 2000 ppb with a lower limit of detection (LOD) of 1.21 ppb. In addition, other interfering materials have no any influences on the detection of methyl parathion. Furthermore, the modified electrode has also been used for methyl parathion detection in the actual ground water samples, and showed efficient sensing ability. The electrochemical sensor developed would have great potentiality for methyl parathion sensing and provide new insights into the detection of other organophosphorous pesticides in the ground water.

Electrodeposition synthesis of a NiO/CNT/PEDOT composite for simultaneous detection of dopamine, serotonin, and tryptophan

Abstract: A novel NiO/carbon nanotube (CNT)/poly(3,4-ethylenedioxythiophene) (PEDOT) composite with a coaxial tubular nanostructure was successfully deposited on a glassy carbon electrode (GCE) through electrochemical processes. The outer PEDOT matrix has a high affinity for biomolecules, while the CNT inner layer has a strong electron-transport capacity. Hence, the NiO/CNT/PEDOT/GCE was used for the simultaneous determination of dopamine (DA), serotonin (5-HT), and tryptophan (Trp). Electrochemical responses of the NiO/CNT/PEDOT/GCE sensor were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. Three well-separated oxidation peaks were observed in a mixed system containing DA, 5-HT, and Trp; the 5-HT–DA and Trp–5-HT potential separations were 160 and 324 mV, respectively, owing to the synergistic effect of NiO, CNT, and PEDOT. Linear responses were obtained for DA, 5-HT, and Trp in the 0.03–20, 0.3–35, and 1–41 μM concentration ranges, with detection limits of 0.026, 0.063, and 0.210 μM, respectively. In addition, it was possible to simultaneously determine the three analytes using the NiO/CNT/PEDOT composite, which suggests that the sensor has promising applicability.

Preparation of flake hexagonal BN and its application in electrochemical detection of ascorbic acid, dopamine and uric acid

Abstract: Flake hexagonal boron nitride (h-BN) was synthesized combining low temperature combustion synthesis (LCS) and carbothermal reduction and nitridation methods. The obtained h-BN is characterized as amorphous and layered structure with high density defects and active surface groups. The electrochemical properties of the flake BN modified glassy carbon electrode were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). These results demonstrate this kind of novel electrodes exhibit excellent electrocatalytic activity and high selectivity for electrochemical detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The liner relationships between current intensities and concentrations are found to be 30–1000, 0.5–150 and 1–300 μM, with detection limits of 3.77, 0.02 and 0.15 μM for AA, DA and UA, respectively. The sensor also exhibits good anti-interference ability, high stability and reproducibility.

Sensitive electrochemical detection of cardiac troponin I in serum and saliva by nitrogen-doped porous reduced graphene oxide electrode

Abstract: Cardiovascular diseases pose one of the highest mortality risks among all diseases in developed countries, steadily increasing the burden on the health systems. Early diagnosis of cardiovascular diseases has consequently become highly important to decrease mortality and to use more adapted therapeutic decisions. We demonstrate here the utility of nitrogen-doped reduced graphene oxide (N-prGO) for detecting and quantifying of cardiac troponin I (cTnI), a key human cardiac protein biomarker, under physiologically relevant conditions. Non-covalent modification of N-prGO by 1-pyrenecarboxylic acid (py-COOH) and poly(ethylene glycol) modified pyrene (py-PEG) ligands allowed the covalent integration of Tro4 aptamer, known for its high selectivity towards cTnI. Using differential pulse voltammetry (DPV), a label-free electrochemical sensor for cTnI for concentrations down to 1 pg mL−1 in human serum could be obtained. This sensitive detection arises from the integration of a porous nanomaterial with excellent electrochemical properties being easily amendable to site-specific surface modification.

Breast cancer biomarker (HER2-ECD) detection using a molecularly imprinted electrochemical sensor

Abstract: The extracellular domain of the human epidermal growth factor receptor 2 (HER2-ECD) is a protein breast cancer biomarker. Its quantification in peripheral blood could provide an important contribution to diagnostics and patient follow-up. In this work an electrochemical molecularly imprinted polymer (MIP) sensor for the quantification of HER2-ECD was developed. The MIP was electropolymerized by cyclic voltammetry using a solution containing phenol and HER2-ECD on a screen-printed gold electrode (AuSPE). The sensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The analysis of HER2-ECD was performed by differential pulse voltammetry using ([Fe(CN)6]3−/4−as redox probe. The linear range was established in the concentration interval from 10 to 70 ng/mL HER2-ECD, with a limit of detection of 1.6 ng/L and a limit of quantification of 5.2 ng/mL. Through the analysis of other protein biomarkers, the MIP sensor was found to be selective. Furthermore, these proteins did not interfere in the analysis of the selected biomarker. The developed sensor was used for the analysis of spiked human serum samples, providing adequate recovery values and precise results. The outcomes of this study indicate that the developed MIP sensor could be useful in the non-invasive analysis of HER2-ECD in breast cancer patients.

Metronidazole determination with an extremely sensitive and selective electrochemical sensor based on graphene nanoplatelets and molecularly imprinted polymers on graphene quantum dots

Abstract: An extremely sensitive and selective electrochemical sensor based on a modified glassy carbon electrode (GCE) for metronidazole (MNZ) determination was developed. At first, molecularly imprinted polymers (MIPs) on the surface of graphene quantum dots (GQDs) was synthesized via sol-gel method. Then, it was dropped on the surface of GCE that modified with graphene nanoplatelets (GNPs). The excellent synergistic effect of GNPs and MIPs shows significantly enhanced electrocatalytic activity for MNZ. Electrochemical behavior of the imprinted electrochemical sensor was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Several effective parameters on the sensor response were investigated and optimized. The proposed imprinted electrochemical sensor, under the optimized conditions, showed two linear dynamic ranges from 0.005 to 0.75 μmol L−1 and 0.75–10.0 μmol L−1 with a low detection limit of 0.52 nmol L−1 for MNZ determination. Finally, the proposed sensor was used for MNZ analysis in human blood plasma samples and provided acceptable results.

EDTA-modified PANI/SWNTs nanocomposite for differential pulse voltammetry based determination of Cu(II) ions

Abstract: Differential pulse voltammetry (DPV) based electrochemical sensor dedicated for the determination of Cu(II) ion concentration is reported in this research. Sensor was based on electrochemically synthesized polyaniline (PANI) and single walled carbon nanotubes (SWNTs) nanocomposite (PANI/SWNTs), which was additionally functionalized by ethylenediaminetetraacetic acid (EDTA) in order to get structure (EDTA-PANI/SWNTs) with advanced selectivity towards Cu(II) ion. Synthesis of PANI/SWNTs nanocomposite was performed by potential cycling, dodecyl benzene sulphonic acid sodium salt (DBSA) was used as a surfactant during the synthesis of PANI/SWNTs nanocomposite to get a uniform suspension of SWNTs at room temperature. In the next step, PANI/SWNTs nanocomposite was further modified by the EDTA solution containing 1-ethyl-3(3-(dimethylamino)propyl)-carbodiimide (EDC) as activating agent, which is activating carboxyl groups, utilizing dip coating technique at room temperature. Differential pulse voltammetry (DPV) technique was applied for the electrochemical detection of Cu(II) ion. DPV based response of EDTA-PANI/SWNTs structure towards Cu(II) ion was investigated. Analytical signals reveal that EDTA-PANI/SWNTs structure is suitable for selective determination of Cu(II) ion in the presence of interfering Pb(II), Cd(II), Ni(II) and Co(II) ions.

Simultaneous and selective measurement of dopamine and uric acid using glassy carbon electrodes modified with a complex of gold nanoparticles and multiwall carbon nanotubes

Abstract: Abnormal levels of dopamine and uric acid are closely relative to some diseases of human body and can serve as key indicators for human health monitoring. As the primary products of purine metabolism, dopamine and uric acid generally coexist in the extracellular fluid of central nervous system and serum. The sensitive and simultaneous analysis of dopamine and uric acid is urgent in clinical diagnosis of some diseases. Herein, carboxylated-multiwall carbon nanotubes (MWCNTs) were functionalized with N-acetyl- l -cystein (NAC) stabilized Au clusters to generate Au@NAC- MWCNTs complex. By drop-coating the complex on glassy carbon electrode (GCE) surface, the complex-modified GCE was fabricated and used for a new working electrode for electrochemical sensing applications. Using cyclic voltammetry and differential pulse voltammetry measurements, the complex-modified GCE showed the capacity of highly sensitive, individual, and simultaneous electrochemical sensing of dopamine and uric acid. The linear detection ranges of dopamine and uric acid were 0.1–250 μM and 0.1–300 μM, respectively, accompanied by low detection limits of 30 nM of dopamine and 40 nM uric acid. In real human serum and urine samples, the complex- modified GCE exhibited a high performance for simultaneous and selective detection of dopamine and uric acid, together with high detection recoveries of 96.9–104.7% and low relative standard deviation of 1.1–3.7%.

Ultrasensitive detection of cancer biomarkers using conducting polymer/electrochemically reduced graphene oxide-based biosensor: Application toward BRCA1 sensing

Abstract: Breast Cancer (BRCA) is the most common threat in women worldwide. Increasing death rate of diagnosed cases is the main leading cause of designing specific genosensors for BRCA − related cancer detection. In the present study, an ultrasensitive label − free electrochemical DNA (E − DNA) sensor based on conducting polymer/reduced graphene − oxide platform has been developed for the detection of BRCA1 gene. An electrochemical method was applied as a simple and controllable technique for the electrochemical reduction of graphene oxide and also, electro − polymerization of pyrrole − 3 − carboxylic acid monomer. The results of the present work show that the polymer − coated reduced graphene − oxide provide more active sites compare to polymer − coated glassy carbon electrode for the DNA probe immobilization. The fabricated signal − off E − DNA sensor employs Cyclic Voltammetry (CV), Differential Pulse Voltammetry (DPV) and Electrochemical Impedance Spectroscopy (EIS) techniques for monitoring the electrochemical behavior of the redox probe. To survey the morphological pattern and surface structural characterizations, the Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) have been applied, respectively. The applicability of the modified surface layer toward DNA sensing was evaluated by both DPV and EIS measurements. This platform permits quantitative determination of BRCA1 in the range of 10 fM–0.1 μM with a limit of detection as low as 3 fM. The proposed genosensor showed a perfect discriminatory power between complementary, non − complementary and mismatched DNA sequences. The described method combined the outstanding features in terms of selectivity, sensitivity, repeatability, reproducibility and remarkable reusability, without demanding for labor − intensive labeling steps. Moreover, the modified electrode was successfully used for accurate determination of trace amounts of DNA target in blood plasma samples.

An ultrasensitive electrochemical bisphenol A sensor based on hierarchical Ce-metal-organic framework modified with cetyltrimethylammonium bromide

Abstract: This work constructed an ultrasensitive electrochemical bisphenol A (BPA) sensor using hierarchical Ce-metal-organic framework (Ce-MOF) modified with cetyltrimethylammonium bromide (CTAB) as a sensing platform. Ce-MOF had been successfully prepared and conveniently modified with a cationic surfactant (CTAB) via the electrostatic interaction. Ce-MOF and CTAB/Ce-MOF were characterized by scanning electron microscopy, X-ray diffraction, infrared spectrum, thermogravimetric analysis and zeta potentials analysis. CTAB/Ce-MOF suspension was dropped onto glassy carbon electrode (GCE) surface to fabricate CTAB/Ce-MOF/GCE. Combined with preconcentration of BPA of the long alkane chain in CTAB via hydrophobic interaction and electrocatalytic activity of Ce-MOF, the dual amplification made CTAB/Ce-MOF/GCE exhibit high electrochemical response toward the oxidation of BPA, and an electrochemical BPA sensor was constructed based on CTAB/Ce-MOF/GCE by differential pulse voltammetry. The designed BPA sensor had a wide linear range from 0.005 to 50 μmol L−1 and a low detection limit of 2.0 nmol L−1 (S/N = 3). The proposed sensor had excellent reproducibility, stability and anti-interference, and was successfully employed for BPA detection in real samples. This convenient and sensitive sensor proved to be a promising and reliable tool for detecting BPA in food and environmental pollution.

Determination of carbamate pesticide in food using a biosensor based on reduced graphene oxide and acetylcholinesterase enzyme

Abstract: Food safety is a major concern for human health and wellbeing all over the world. A novel and sensitive biosensor based on reduced graphene oxide (rGO) and the enzyme acetylcholinesterase (AChE) was developed and applied for the detection of carbaryl in food samples. The glassy carbon/rGO/AChE biosensor was characterized morphologically and electrochemically using scanning electron microscopy and cyclic voltammetry/electrochemical impedance spectroscopy, respectively. Optimum differential pulse voltammetry conditions led to a nanomolar detection limit, and determination of carbaryl in tomato was achieved.

Simultaneous label-free and pretreatment-free detection of heavy metal ions in complex samples using electrodes decorated with vertically ordered silica nanochannels

Abstract: In this work, indium tin oxide coated glass (ITO) decorated with vertically-ordered mesoporous silica film (VMSF/ITO) is synthesized and applied as electrochemical sensor for simultaneous label-free and pretreatment-free detection of Pb2+, Cu2+, and Cd2+ in human serum and soil leaching solution. Using differential pulse voltammetry (DPV), the electrochemical detection consists of electro-deposition of metal species and subsequent anodic stripping in the silica nanochannels. Because of the electrostatic enrichment and nano-confinement effects, VMSF/ITO is able to simultaneously detect Pb2+, Cu2+, and Cd2+ in a mixture with low detection limits (2.6 nM, 32 nM and 230 nM, respectively). Moreover, VMSF confer the electrode with excellent anti-fouling and anti-interference property through steric exclusion and electrostatic repulsion. Direct analysis of complex biological (human serum) and environmental (soil leaching solution) samples could be finished within 10 min without the usual need of tedious pretreatment. Furthermore, the VMSF/ITO sensor can be reused for several times without performance degradation.