Novel CNT Supported Molybdenum Catalyst for Detection of L-Cysteine in Its Natural Environment

In this study, novel carbon nanotube-supported Mo (Mo/CNT) catalysts were prepared with the sodium borohydride reduction method for the detection of L-cysteine (L-Cys, L-C). Mo/CNT catalysts were characterized with scanning electron microscopy with elemental dispersion X-ray (EDX-SEM), X-ray diffraction (XRD), UV-vis diffuse reflectance spectrometry (UV-vis), temperature-programmed reduction (TPR), temperature programmed oxidation (TPO), and temperature-programmed desorption (TPD) techniques. The results of these advanced surface characterization techniques revealed that the catalysts were prepared successfully. Electrochemical measurements were employed to construct a voltammetric L-C sensor based on Mo/CNT catalyst by voltammetric techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Further measurements were carried out with electrochemical impedance spectroscopy (EIS). Mo/CNT/GCE exhibited excellent performance for L-C detection with a linear response in the range of 0–150 µM, with a current sensitivity of 200 mA/μM cm2 (0.0142 μA/μM), the lowest detection limit of 0.25 μM, and signal-to-noise ratio (S/N = 3). Interference studies showed that the Mo/CNT/GCE electrode was not affected by D-glucose, uric acid, L-tyrosine, and L-trytophane, commonly interfering organic structures. Natural sample analysis was also accomplished with acetyl L-C. Mo/CNT catalyst is a promising material as a sensor for L-C detection.

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Electrochemical Investigation of Curcumin–DNA Interaction by Using Hydroxyapatite Nanoparticles–Ionic Liquids Based Composite Electrodes

Materials ◽

10.3390/ma14154344 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4344

Author(s):

Merve Uca ◽

Ece Eksin ◽

Yasemin Erac ◽

Arzum Erdem

Keyword(s):

Electrochemical Impedance ◽

Differential Pulse ◽

Dna Interaction ◽

Composite Electrodes ◽

Hydroxyapatite Nanoparticles ◽

Graphite Electrodes ◽

X Ray ◽

Pulse Voltammetry ◽

Polymerase Chain

Hydroxyapatite nanoparticles (HaP) and ionic liquid (IL) modified pencil graphite electrodes (PGEs) are newly developed in this assay. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and cyclic voltammetry (CV) were applied to examine the microscopic and electrochemical characterization of HaP and IL-modified biosensors. The interaction of curcumin with nucleic acids and polymerase chain reaction (PCR) samples was investigated by measuring the changes at the oxidation signals of both curcumin and guanine by differential pulse voltammetry (DPV) technique. The optimization of curcumin concentration, DNA concentration, and the interaction time was performed. The interaction of curcumin with PCR samples was also investigated by gel electrophoresis.

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Surface Characterization of W/Ni/Al2O3 Catalysts

MRS Proceedings ◽

10.1557/proc-497-243 ◽

1997 ◽

Vol 497 ◽

Author(s):

M. H. Jordão ◽

J. M. Assaf ◽

P. A. P. Nascente

Keyword(s):

Photoelectron Spectroscopy ◽

Inductively Coupled Plasma ◽

Surface Characterization ◽

Nickel Content ◽

Stable Phase ◽

Preparation Methods ◽

X Ray ◽

Inductively Coupled ◽

Temperature Programmed ◽

Two Phases

ABSTRACTCatalysts containing tungsten and nickel oxides are important in hydrodesulfurization (HDS), hydrogénation (HY), and steam reforming of hydrocarbons. A series of W/Ni/Al2O3 catalysts was prepared by two different methods: (1) coprecipitation of nickel and aluminium hydroxicarbonate from their nitrates, followed by calcination and impregnation of tungsten; (2) precipitation of boehmite from aluminium nitrate, followed by impregnations of nickel, firstly, and tungsten. The nickel content was kept constant, while the amount of tungsten varied from 2.5 to 15.5 wt-%. The resulting oxides were characterized by inductively coupled plasma spectroscopy (ICP), atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). ICP and AAS were used to determine the W, Ni, and Al concentrations. XRD detected two phases: NiO and NiAl2O4 (no phase containing metallic tungsten was detected). Increasing the amount of W, the quantity of NiAl2O4 rose, the quantity of NiO decreased, and the particle size of NiO enlarged. The TPR profiles presented three peaks: one at about 1000 °C, associated to a very stable phase; for the samples prepared by coprecipitation, the other two peaks corresponded to “free NiO” and a nonstoichiometric aluminate. For the samples prepared by impregnation, those peaks corresponded to NiO and NiAl2O4. XPS identified Al2O3, NiAl2O4, and Al2(WO4)3 for both preparation methods. Increasing the amount of tungsten in the impregnated samples, NiWO4 was also observed.

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Facile caffeine electrochemical detection via electrodeposited Ag nanoparticles with modifier polymers on carbon paste sensor at aqueous and micellar media

Canadian Journal of Chemistry ◽

10.1139/cjc-2019-0195 ◽

2020 ◽

Vol 98 (4) ◽

pp. 169-178 ◽

Cited By ~ 2

Author(s):

M. Shehata ◽

S.M. Azab ◽

A.M. Fekry

Keyword(s):

Ag Nanoparticles ◽

Surface Characterization ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Electrochemical Techniques ◽

Calibration Plot ◽

Micellar Media ◽

Carbon Paste ◽

Detection Range ◽

X Ray

The analysis and detection of caffeine (Caf) is very useful due to its widespread usage in several daily consumed beverages, food products, and pharmacological preparations with various physiological effects. The preparation of a newly electrodeposited Ag nanoparticles – cellulose acetate phthalate (CAP) – chitosan (Chit) modified carbon paste (ACCMCP) sensor for sensitive determination of Caf in 0.01 mol L−1 H3PO4 solution (pH 1.0–5.0) both in aqueous and micellar media (0.5 mmol L−1 SDS) was achieved. The interaction of Caf was monitored using electrochemical techniques such as cyclic voltammetry, differential pulse voltammetry, electrochemical impedance spectroscopy, and chronoamperometry, and surface characterization was carried out using X-ray diffraction, scanning electron microscope, and energy dispersive X-ray techniques. The linear detection range of Caf was between 4 and 500 μmol L−1 (r2 = 0.955) and the limit of detection obtained from the calibration plot was 0.252 μmol L−1. The sensor was applicable for detecting Caf in numerous real samples with recoveries from 98.03% to 101.60% without interference of any accompanying species, which ensures high method selectivity.

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An Amperometric Immunosensor for α-Fetoprotein Based on Antibody Coated Nano ZrO2-Au-Poly Lysine Composite Membrane Modified Electrode

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.343-344.490 ◽

2011 ◽

Vol 343-344 ◽

pp. 490-496 ◽

Cited By ~ 1

Author(s):

Yuan Zhao Wu ◽

Fu Tao Hu ◽

Ning Gan ◽

Jian Guo Hou ◽

Tian Hua Li ◽

...

Keyword(s):

Modified Electrode ◽

Composite Membrane ◽

Electrochemical Impedance ◽

Signal To Noise Ratio ◽

Cost Effective ◽

Differential Pulse ◽

Phenoxyacetic Acid ◽

Serum Samples ◽

Amperometric Immunosensor ◽

Sensitivity And Selectivity

One novel amperometric immunosensor for α-fetop- rotein was fabricated which was modified by antibody immobilized on nano ZrO2-Au-polyLysine composite membrane. Firstly, the deoxyribonucleic acid – phenoxyacetic acid isoniazid- Schiff base Co(II) complex (DNA-CoL) mixture film was casted on surface of multi carbon nanotubes(MWCNTs) modified glassy carbon electrode(GCE/CNTs/DNA-CoL). Then the composite nanoparticles (ZrO2-Au-pLL) was employed to immobilize the antibody of α-fetoprotein(AFP) to produce the probes(ZrO2-Au-pLL-anti AFP) for AFP. Finally the probes were modified on GCE/CNTs/DNA-CoL through the specific connection between DNA and ZrO2 to form a novel nanocomposite membrane immunosensor for AFP(GCE/CNTs/ DNA-CoL/ZrO2-Au–pLL-anti AFP). The function of immunosensor was investigated by scanning electron microscopy (SEM), cyclic voltammetry(CV), differential pulse voltammety (DPV) and electrochemical impedance spectroscopy experiment (EIS). The results indicated that combining the advantages of the MWNTs-DNA material and ZrO2-Au-pLL-anti AFP nano probes, the immunosensor with excellent sensitivity and selectivity to AFP was prepared successfully. The modified electrode was sensitive to AFP with a linear relationship between 0.05 and 10 ng · mL−1 and a correl- ation coefficient of 0.9905. The detection limit at a signal to noise ratio of 3 was 0.01 ng·mL−1 under the optimal conditions. The described immunosensor preparation and immunoassay methods offer promise for simple and cost-effective analysis of AFP in serum samples.

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Determination of Methyldopa and Paracetamol in Pharmaceutical Samples by a Low Cost Genipa americana L. Polyphenol Oxidase Based Biosensor

Advanced Pharmaceutical Bulletin ◽

10.15171/apb.2019.049 ◽

2019 ◽

Vol 9 (3) ◽

pp. 416-422

Author(s):

Rafael Souza Antunes ◽

Douglas Vieira Thomaz ◽

Luane Ferreira Garcia ◽

Eric de Souza Gil ◽

Vernon Sydwill Sommerset ◽

...

Keyword(s):

Electrochemical Impedance ◽

Low Cost ◽

Differential Pulse ◽

Pharmaceutical Samples ◽

Polyphenol Oxidases ◽

Voltammetric Techniques ◽

Relative Standard ◽

Pulse Voltammetry ◽

Phenolic Drugs

Purpose: Jenipapo fruit (Genipa americana L) is a natural source of polyphenol oxidases (PPOs) whose potential in pharmaceutical analysis is noteworthy. Henceforth, this work reports the electrochemical study of a low-cost PPO-based biosensor produced from the crude extract of Jenipapo fruits and accounts a practical approach to employ this biosensor in the determination of methyldopa and paracetamol in pharmaceutical samples. Methods: In order to investigate the electrochemical properties of the biosensor, theoretical and practical approaches were employed, and both samples and the biosensor were analyzed through electrochemical impedance spectroscopy (EIS) and voltammetric techniques, namely: differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Results: showcased that the biosensor presented good analytical features, as well as low detection limits (8 μmol L-1 for methyldopa and 5 μmol L-1 for paracetamol). The relative standard deviation was less than 5% mid-assay. Conclusion: The use of this biosensor is a reliable, low cost and useful alternative in the pharmaceutic determination of phenolic drugs (e.g. methyldopa and paracetamol).

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Sonochemically Prepared GdWNFs/CNFs Nanocomposite As An Electrode Material For The Electrochemical Detection of Antibiotic Drug in Water Bodies

10.21203/rs.3.rs-1158022/v1 ◽

2021 ◽

Author(s):

Manikanta P ◽

Hari Prasad B R ◽

Sanjay B P ◽

Sandeep S ◽

Santhosh A S ◽

...

Keyword(s):

Electrochemical Impedance ◽

Differential Pulse ◽

Electrochemical Sensing ◽

Pencil Graphite Electrode ◽

X Ray Diffraction ◽

Standard Samples ◽

Tem Analysis ◽

X Ray ◽

Transmission Electron ◽

Antibiotic Drug

Abstract The work demonstrates the development of an electrochemical sensor for quantification of Chloramphenicol (CA) using pencil graphite electrode (PGE) modified with Gadolinium tungstate nano flakes and carbon nano fibers composite (PGE/GWNfs/CNFs). The composite was further characterized and confirmed by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) analysis. The prepared GWNfs/CNFs nano composite was fabricated by drop casting method to get PGE/GWNfs/CNFs working electrode. The modified electrode is then analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) methods for its electrochemical and electrocatalytic property. The electrochemical investigation of developed sensor shows enhanced activity towards electro-oxidation of CA. The DPV studies revealed high efficacy characteristics such as sensitivity in the range 0.03984 µA µM-1cm-2, selectivity, good linear range (5-50 μM), and low detection limit (0.4 μM). The study benchmarks the use of GWNfs/CNFs as an excellent transducer material in electrochemical sensing of CA in standard samples thus, it finds an efficient potential application in the analysis of CA in environment sample analysis.

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

Micromachines ◽

10.3390/mi12111334 ◽

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.

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Effect of temperature and pressure on mechanical, surface and electrochemical properties of Al-1.5Cu-5.5Zn-2.5Mg (Alumix-431)

Anti-Corrosion Methods and Materials ◽

10.1108/acmm-03-2018-1909 ◽

2018 ◽

Vol 65 (6) ◽

pp. 558-571 ◽

Cited By ~ 2

Author(s):

Ayşe Nur Acar ◽

Rasiha Nefise Mutlu ◽

Abdul Kadir Ekşi ◽

Ahmet Ekicibil ◽

Birgül Yazıcı

Keyword(s):

Electrochemical Properties ◽

Surface Characterization ◽

Electrochemical Impedance ◽

Effect Of Temperature ◽

Corrosion Properties ◽

Content Type ◽

X Ray ◽

Good Surface ◽

Mechanical Properties And Corrosion ◽

Mechanical Surface

Purpose The purpose of this paper is to examine new alloys created from Alumix 431 powder and investigate their mechanical and electrochemical properties. Design/methodology/approach In this study; Alumix-431 alloy samples were prepared using the powder metallurgy (P/M) method applying cold (RT) and warm (50°C and 80°C) compaction methods under pressures of 200 and 250 MPa and were sintered at 600°C in N2(g) atmosphere. Hardness and density of the samples were measured, and corrosion properties were determined by electrochemical impedance spectroscopy charting polarization curves. Surface characterization was determined by contact angle, scanning electron microscopy/mapping, energy dispersive X-ray spectrometry and X-ray diffractometry images. Findings Alumix-431 alloys obtained upon compaction at 250 MPa/50 °C had the highest mechanical properties and corrosion resistance and good surface properties. On the surfaces of Alumix-431 alloys, α-Al, MgZn2, Al2,CuMg, Al2,O3, Al2MgO4 phases were recorded. Originality/value This study aimed to construct a correlation between mechanical and electrochemical properties of the newly created alloys (prepared under special conditions).

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Croton lechleri Extracts as Green Corrosion Inhibitors of Admiralty Brass in Hydrochloric Acid

Molecules ◽

10.3390/molecules26247417 ◽

2021 ◽

Vol 26 (24) ◽

pp. 7417

Author(s):

Carlos Cevallos-Morillo ◽

Pablo Cisneros-Pérez ◽

Roxana Llive ◽

Marvin Ricaurte ◽

Carlos Reinoso ◽

...

Keyword(s):

Natural Products ◽

Photoelectron Spectroscopy ◽

Surface Characterization ◽

Corrosion Inhibitors ◽

Electrochemical Impedance ◽

Transfer Resistance ◽

X Ray ◽

Chemical Structures ◽

Green Corrosion Inhibitors ◽

Croton Lechleri

Croton lechleri, commonly known as Dragon’s blood, is a tree cultivated in the northwest Amazon rainforest of Ecuador and Peru. This tree produces a deep red latex which is composed of different natural products such as phenolic compounds, alkaloids, and others. The chemical structures of these natural products found in C. lechleri latex are promising corrosion inhibitors of admiralty brass (AB), due to the number of heteroatoms and π structures. In this work, three different extracts of C. lechleri latex were obtained, characterized phytochemically, and employed as novel green corrosion inhibitors of AB. The corrosion inhibition efficiency (IE%) was determined in an aqueous 0.5 M HCl solution by potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopy, measuring current density and charge transfer resistance, respectively. In addition, surface characterization of AB was performed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy techniques. Chloroform alkaloid-rich extracts resulted in IE% of 57% at 50 ppm, attributed to the formation of a layer of organic compounds on the AB surface that hindered the dezincification process. The formulation of corrosion inhibitors from C. lechleri latex allows for the valorization of non-edible natural sources and the diversification of the offer of green corrosion inhibitors for the chemical treatment of heat exchangers.

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In situ observation of charge transfer and crystal field formation via high energy resolution X-ray spectroscopy during temperature programmed oxidation

Physical Chemistry Chemical Physics ◽

10.1039/d0cp01974g ◽

2020 ◽

Vol 22 (26) ◽

pp. 14731-14735

Author(s):

Anna Wach ◽

Wojciech Błachucki ◽

Joanna Czapla-Masztafiak ◽

Daniel Luis Abreu Fernandes ◽

Dariusz Banaś ◽

...

Keyword(s):

Charge Transfer ◽

Energy Resolution ◽

High Energy ◽

High Energy Resolution ◽

In Situ Observation ◽

X Ray ◽

Temperature Programmed Oxidation ◽

Temperature Programmed ◽

Charge Transfer Dynamics ◽

Field Formation

In this paper, we demonstrated how high energy resolution resonant X-ray emission spectroscopy can be employed to study the charge transfer dynamics in real-time during the temperature-induced oxidation of metallic tungsten.

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