scholarly journals A Sensitive Impedimetric Aptasensor Based on Carbon Nanodots Modified Electrode for Detection of 17ß-Estradiol

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1346 ◽  
Author(s):  
Mohd Hazani Mat Zaid ◽  
Jaafar Abdullah ◽  
Normazida Rozi ◽  
Aliff Aiman Mohamad Rozlan ◽  
Sharina Abu Hanifah
Keyword(s):  
Water Samples ◽  
Electrochemical Impedance ◽  
Carbon Nanodots ◽  
Visible Absorption ◽  
Transmission Electron ◽  
Relative Standard ◽  
Before And After ◽  
Average Recovery Rate ◽  
Aptamer Probe ◽  
Eis Measurements

A simple and sensitive aptasensor based on conductive carbon nanodots (CDs) was fabricated for the detection of 17ß-Estradiol (E2). In the present study, the hydrothermal synthesis of carbon nanodots was successfully electrodeposited on a screen-printed electrode (SPE) as a platform for immobilization of 76-mer aptamer probe. The morphology and structure of the nanomaterial were characterized by UV-visible absorption spectra, Fluorescence spectra, Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Moreover, cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the electrochemical performance of the prepared electrodes. Subsequently, impedimetric (EIS) measurements were employed to investigate the relative impedances changes before and after E2 binding, which results in a linear relationship of E2 concentration in the range of 1.0 × 10−7 to 1.0 × 10 −12 M, with a detection limit of 0.5 × 10−12 M. Moreover, the developed biosensor showed high selectivity toward E2 and exhibited excellent discrimination against progesterone (PRG), estriol (E3) and bisphenol A (BPA), respectively. Moreover, the average recovery rate of spiked river water samples with E2 ranged from 98.2% to 103.8%, with relative standard deviations between 1.1% and 3.8%, revealing the potential application of the present biosensor for E2 detection in water samples.

Corrosion Characteristics of an Ultrafine-Grained Al-Mg-Si Alloy (AA6082)

2008 ◽  
Vol 584-586 ◽  
pp. 988-993 ◽  
Author(s):  
Bernhard Wielage ◽  
Daniela Nickel ◽  
Thomas Lampke ◽  
Gert Alisch ◽  
Harry Podlesak ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Grain Boundaries ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Coarse Grained ◽  
Angular Pressing ◽  
Transmission Electron ◽  
Ultrafine Grained ◽  
Before And After ◽  
Eis Measurements

The corrosion behaviour of the aluminium alloy, AA6082, processed by equal-channel angular pressing (ECAP) after different passes (route E, room temperature) was studied in comparison to the coarse-grained counterpart. The results of the electrochemical investigations (cyclovoltammetry; electrochemical impedance spectroscopy, EIS) are presented in correlation with the microstructure before and after the corrosion examinations. Both, chemical (precipitations, phases) and physical (dislocations, high-angle grain boundaries, grain size, low-angle grain boundaries) inhomogeneities characterize the microstructure of this commercially used Al-Mg-Si alloy. Results indicate an improved resistance against pitting of the ECAP material expressed by a reduced pitting density of up to 50 % and lower pit depths. EIS measurements and microstructural examinations (scanning electron microscopy, transmission electron microscopy, 3D topography measurement) confirm that ECAP modifies the number, size and distribution of these inhomogeneities, which leads to a more favourable corrosion behaviour.

Synthesis of a Core-Shell Acrylate Elastomer with UV Stabilization and its Application in Polyoxymethylene

2011 ◽  
Vol 239-242 ◽  
pp. 2431-2434 ◽  
Author(s):  
Fan Yang ◽  
Gui Bo Wu ◽  
Shi Ling Zhang ◽  
Xian Cheng Ren
Keyword(s):  
Mechanical Properties ◽  
Methyl Methacrylate ◽  
Uv Irradiation ◽  
Butyl Acrylate ◽  
Core Shell ◽  
Visible Absorption ◽  
Transmission Electron ◽  
Before And After ◽  
Uv Stabilization

In this study, a core-shell structure acrylate elastomer with UV stabilization core–shell poly[methyl methacrylate-butyl acrylate-2-hydroxy-4-(3-methacryloxy-2-hydroxylproroxy) benzophenone] [poly(MMA-BA-BPMA)] was synthesized by methyl methacrylate (MMA), butyl acrylate (BA) and a polymerizable UV-stabilizer 2-hydroxy-4-(3-methacryloxy-2-hydroxylproroxy) benzophenone (BPMA) via semicontinuous seeding emulsion polymerization. The composition and characteristics of core-shell Poly (MMA-BA-BPMA) were determined by using Fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible absorption spectroscopy (UV-vis) and transmission electron microscope (TEM). Further, the obtained core-shell poly (MMA-BA-BPMA) was blended with polyoxymethylene (POM) to modify its photostabilization. The mechanical properties of POM composite were tested before and after UV-irradiation. The result showed that core-shell poly (MMA-BA-BPMA) can be dispersed well in the POM matrix, which could play a role of improving compatibility with POM and the mechanical properties of modified POM were kept well, which leaded higher impact strength and elongation at break after UV-irradiation.

Synthesis and Densification of Nanometric Ce0.8Sm0.2O1.9-δ

2006 ◽  
Vol 972 ◽  
Author(s):  
Vincenzo Esposito ◽  
Marco Fronzi ◽  
Enrico Traversa
Keyword(s):  
Electron Microscopy ◽  
Liquid Phase ◽  
Electrochemical Impedance ◽  
Liquid Phase Sintering ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Conventional Sintering ◽  
Eis Measurements ◽  
Co Precipitation

AbstractNanometric 20% molar Sm-doped ceria (SDC20) powders were synthesized by tetrametylethylen ammine (TMDA) co-precipitation method. SDC20 was sintered in several conditions to control the final microstructure. Fast firing and conventional sintering were performed. LiNO3was used as an additive to promote liquid phase sintering of ceria at low temperatures (900-1200°C). Powders and dense pellets were analysed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) measurements were performed on dense pellets in air to estimate the contribution of grain boundary and bulk to the electrical conductivity. Liquid phase sintering produced the densest samples with the highest conductivity.

scholarly journals Ultrafast and Energy-saving Synthesis of Nitrogen and Chlorine Co-doped Carbon Nanodots via Neutralization Heat for Selective Detection of Cr(VI) in Aqueous Phase

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3416 ◽  
Author(s):  
Qin Hu ◽  
Tao Li ◽  
Lu Gao ◽  
Xiaojuan Gong ◽  
Shengqi Rao ◽  
...  
Keyword(s):  
Energy Saving ◽  
Water Samples ◽  
Fluorescence Probe ◽  
Limit Of Detection ◽  
Inner Filter Effect ◽  
Fluorescence Method ◽  
Carbon Nanodots ◽  
Selective Detection ◽  
Relative Standard ◽  
Co Doped

In this work, it is presented for the first time that nitrogen and chlorine co-doped carbon nanodots (N,Cl-CDs) were synthesized by simply mixing glucose, concentrated hydrochloric acid (HCl), and 1,2-ethylenediamine (EDA). No external heat was employed; the neutralization reaction served as the heat source. The glucose served as the carbon source while EDA and HCl were the N and Cl dopants, respectively. The fluorescence of N,Cl-CDs was adequately quenched by hexavalent chromium Cr(VI) based on a combination of dynamic quenching and inner filter effect (IFE). Accordingly, an efficient N,Cl-CDs-based fluorescence probe was established for sensitive and selective detection of Cr(VI). The proposed fluorescence sensor provides a linear recognition range for Cr(VI) determination from 3 to 40 µM with a limit of detection (LOD) of 0.28 µM (14.6 µg/L). The proposed fluorescence method was successfully utilized to detect Cr(VI) in different water samples with satisfactory results. The spike recoveries vary from 97.01% to 103.89% with relative standard deviations (RSDs) of less than 0.82%. This work highlights the development of a simple, ultrafast, and energy-saving one-step synthetic route to fabricate N,Cl-CDs for highly selective and sensitive detection of Cr(VI) in real water samples. It is anticipated that the proposed fluorescence method could be further explored and widely used for Cr(VI) detection in the environmental industry.

scholarly journals An amperometric H2O2 biosensor based on hemoglobin nanoparticles immobilized on to a gold electrode

2017 ◽  
Vol 37 (4) ◽  
Author(s):  
Vinay Narwal ◽  
Neelam Yadav ◽  
Manisha Thakur ◽  
Chandra S. Pundir
Keyword(s):  
Electron Microscopy ◽  
Electrochemical Impedance ◽  
Uv Spectroscopy ◽  
Colorimetric Method ◽  
High Sensitivity ◽  
Electrochemical Impedance Spectra ◽  
Sodium Phosphate Buffer ◽  
Transmission Electron ◽  
Before And After ◽  
Optimum Response

The nanoparticles (NPs) of hemoglobin (Hb) were prepared by desolvation method and characterized by transmission electron microscopy (TEM), UV spectroscopy and Fourier-transform IR (FTIR) spectroscopy. An amperometric H2O2 biosensor was constructed by immobilizing HbNPs covalently on to a polycrystalline Au electrode (AuE). HbNPs/AuE were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) before and after immobilization of HbNPs. The HbNPs/AuE showed optimum response within 2.5 s at pH 6.5 in 0.1 M sodium phosphate buffer (PB) containing 100 μM H2O2 at 30°C, when operated at –0.2 V against Ag/AgCl. The HbNPs/AuE exhibited Vmax of 5.161 ± 0.1 μA cm−2 with apparent Michaelis-Menten constant (Km) of 0.1 ± 0.01 mM. The biosensor showed lower detection limit (1.0 μM), high sensitivity (129 ± 0.25 μA cm−2 mM−1) and wider linear range (1.0–1200 μM) for H2O2 as compared with earlier biosensors. The analytical recoveries of added H2O2 in serum (0.5 and 1.0 μM) were 97.77 and 98.01% respectively, within and between batch coefficients of variation (CV) were 3.16 and 3.36% respectively. There was a good correlation between sera H2O2 values obtained by standard enzymic colorimetric method and the present biosensor (correlation coefficient, R2 =0.99). The biosensor measured H2O2 level in sera of apparently healthy subjects and persons suffering from diabetes type II. The HbNPs/AuE lost 10% of its initial activity after 90 days of regular use, when stored dry at 4°C.

IN SITU TEMPLATE SYNTHESIS OF PoPD–TiO2 NANOCOMPOSITES FOR ACTIVE ANTI-CORROSIVE COATINGS ON 316L SS

2011 ◽  
Vol 10 (04n05) ◽  
pp. 1147-1152 ◽  
Author(s):  
P. MUTHIRULAN ◽  
N. RAJENDRAN
Keyword(s):  
Electron Microscopy ◽  
Electrochemical Impedance ◽  
Material Loss ◽  
Transmission Electron ◽  
Corrosion Studies ◽  
Protective System ◽  
Ft Ir ◽  
Eis Measurements ◽  
Thermal Stability Of

Corrosion is one of the major destruction processes involved in material loss, and its prevention is paramount in protecting investments. The present work shows a new contribution to the design of a new protective system based on poly(orthophenylenediamine) (PoPD)–nano- TiO2 composites. The structure and properties of PoPD– TiO2 nanocomposites were characterized by Fourier transform infrared spectroscopy (FT-IR), Cyclicvoltammetry (CV), Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. Thermal stability of the composite was studied by Thermogravimetric analysis (TGA). The anti-corrosion behavior of PoPD– TiO2 nanocomposites has been investigated in 3.5 wt.% NaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) measurements. Corrosion studies revealed that PoPD– TiO2 nanocomposites coating exhibited excellent anti-corrosive properties compared with PoPD coated and uncoated 316L SS.

scholarly journals Magnetic Graphene Oxide Composite for the Microextraction and Determination of Benzophenones in Water Samples

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 168
Author(s):  
Alejandro Medina ◽  
Francisco Antonio Casado-Carmona ◽  
Ángela I. López-Lorente ◽  
Soledad Cárdenas
Keyword(s):  
Graphene Oxide ◽  
Magnetite Nanoparticles ◽  
Water Samples ◽  
Hydrophobic Interactions ◽  
Solid Phase ◽  
Magnetic Graphene Oxide ◽  
Hybrid Nanomaterial ◽  
Transmission Electron ◽  
Relative Standard ◽  
Tandem Mass Spectrometric

Magnetite nanoparticles (Fe3O4) functionalized with graphene oxide (GO) have been synthesized through a silanization process of the magnetic nanoparticles with tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane and further coupling of GO. The synthesized nanomaterials have been characterized by several techniques, such as transmission electron microscopy (TEM), and infrared and Raman spectroscopy, which enabled the evaluation of the different steps of the functionalization process. The hybrid nanomaterial has been employed for the extraction of five benzophenones (benzophenone-1, benzophenone-3, 4-hydroxybenzophenone, benzophenone-6 and benzophenone-8) in aqueous samples by dispersive micro-solid phase extraction, combining the magnetic properties of magnetite nanoparticles with the excellent sorption capacity of graphene oxide via hydrophobic interactions with the analytes. The subsequent separation and quantification of the analytes was performed by liquid chromatography with tandem mass spectrometric detection, achieving limits of detection (LODs) in the range 2.5 to 8.2 μg·L−1, with relative standard deviations ranging from 1.3–9.8% and relative recovering in the range 86 to 105%. Positive swimming pool water samples analysed following the developed method revealed the presence of benzophenones in from 14.3 to 39 μg·L−1.

An Electron Microscope Study of Interdiffusion and Compound Formation in Ta-Au Thin Films

1973 ◽  
Vol 31 ◽  
pp. 32-33 ◽  
Author(s):  
T. C. Tisone ◽  
S. Lau
Keyword(s):  
Electron Microscope ◽  
Electron Microscope Study ◽  
Thermally Grown Oxide ◽  
Ion Milling ◽  
Compound Formation ◽  
Technology Application ◽  
Transmission Electron ◽  
Before And After ◽  
Au Thin Films

In a study of the properties of a Ta-Au metallization system for thin film technology application, the interdiffusion between Ta(bcc)-Au, βTa-Au and Ta2M-Au films was studied. Considered here is a discussion of the use of the transmission electron microscope(TEM) in the identification of phases formed and characterization of the film microstructures before and after annealing.The films were deposited by sputtering onto silicon wafers with 5000 Å of thermally grown oxide. The film thicknesses were 2000 Å of Ta and 2000 Å of Au. Samples for TEM observation were prepared by ultrasonically cutting 3mm disks from the wafers. The disks were first chemically etched from the silicon side using a HNO3 :HF(19:5) solution followed by ion milling to perforation of the Au side.

Effect of MWCNT doping on the structural and optical properties of PVC/PVDF polymer blend

2017 ◽  
Vol 13 (2) ◽  
pp. 4640-4647
Author(s):  
A. M. Abdelghany ◽  
M.S. Meikhail ◽  
S.I. Badr ◽  
A. S. Momen
Keyword(s):  
Surface Damage ◽  
X Ray Diffraction ◽  
Dopant Content ◽  
Casting Technique ◽  
Transmission Electron ◽  
Dopant Level ◽  
Before And After ◽  
Carbon Nano Tubes ◽  
Small Band ◽  
Vibrational Bands

Thin film samples of pristine polyvinyl chloride (PVC), poly vinyldine fluoride (PVDF) in combination with their blend in addition to samples containing factorial mass fraction of multi wall carbon nano-tubes (MWCNTs) in the dopant level were prepared via routine casting technique using tetrahydrofurane (THF) as a common solvent. X-ray diffraction and transmission electron microscopy (TEM) depict the nano-scale (15-25 nm) of functionalized MWCNTs with no surface damage results from functionalization process.X-ray diffraction (XRD) shows a semi-crystalline nature of PVDF with evidence for more than one phase namely a and b phases. The fraction of b phase was calculated and correlated to the dopant content. FTIR optical absorption spectra revels a preservation of the main vibrational bands before and after addition of MWCNTs in the doping level with a presence of new small band 1151 cm-1 assigned for the interaction and complexation between constituents.

scholarly journals Influence of Nitrogen-Doped Carbon Dot and Silver Nanoparticle Modified Carbon Paste Electrodes on the Potentiometric Determination of Tobramycin Sulfate: A Comparative Study

Chemosensors ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 52
Author(s):  
Nermine V. Fares ◽  
Passant M. Medhat ◽  
Christine M. El Maraghy ◽  
Sherif Okeil ◽  
Miriam F. Ayad
Keyword(s):  
Silver Nanoparticle ◽  
Carbon Nanodots ◽  
Carbon Paste ◽  
X Ray Diffraction ◽  
Loteprednol Etabonate ◽  
Carbon Paste Electrodes ◽  
Transmission Electron ◽  
Nernstian Slope ◽  
Nitrogen Doped Carbon ◽  
Modified Carbon Paste Electrodes

Two inexpensive and simple methods for synthesis of carbon nanodots were applied and compared to each other, namely a hydrothermal and microwave-assisted method. The synthesized carbon nanodots were characterized using transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis), photoluminescence (PL), Fourier transform-infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The synthesized microwave carbon nanodots had smaller particle size and were thus chosen for better electrochemical performance. Therefore, they were used for our modification process. The proposed electrodes performance characteristics were evaluated according to the IUPAC guidelines, showing linear response in the concentration range 10−6–10−2, 10−7–10−2, and 10−8–10−2 M of tobramycin with a Nernstian slope of 52.60, 58.34, and 57.32 mV/decade for the bare, silver nanoparticle and carbon nanodots modified carbon paste electrodes, respectively. This developed potentiometric method was used for quantification of tobramycin in its co-formulated dosage form and spiked human plasma with good recovery percentages and without interference of the co-formulated drug loteprednol etabonate and excipients.

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