scholarly journals Graphene Oxide-Based Nanostructured DNA Sensor

Biosensors ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 74 ◽  
Author(s):  
Aditya Balaji ◽  
Songlin Yang ◽  
Jeslyn Wang ◽  
Jin Zhang
Keyword(s):  
Graphene Oxide ◽  
Fluorescence Quenching ◽  
Dna Sequence ◽  
Early Stage ◽  
Average Particle Size ◽  
Average Particle ◽  
Sensing System ◽  
Sio2 Shell ◽  
Modified Graphene Oxide ◽  
Complementary Oligonucleotide

Quick detection of DNA sequence is vital for many fields, especially, early-stage diagnosis. Here, we develop a graphene oxide-based fluorescence quenching sensor to quickly and accurately detect small amounts of a single strand of DNA. In this paper, fluorescent magnetic nanoparticles (FMNPs) modified with target DNA sequence (DNA-t) were bound onto the modified graphene oxide acting as the fluorescence quenching element. FMNPs are made of iron oxide (Fe3O4) core and fluorescent silica (SiO2) shell. The average particle size of FMNPs was 74 ± 6 nm and the average thickness of the silica shell, estimated from TEM results, was 30 ± 4 nm. The photoluminescence and magnetic properties of FMNPs have been investigated. Target oligonucleotide (DNA-t) was conjugated onto FMNPs through glutaraldehyde crosslinking. Meanwhile, graphene oxide (GO) nanosheets were produced by a modified Hummers method. A complementary oligonucleotide (DNA-c) was designed to interact with GO. In the presence of GO-modified with DNA-c, the fluorescence intensity of FMNPs modified with DNA-t was quenched through a FRET quenching mechanism. Our study indicates that FMNPs can not only act as a FRET donor, but also enhance the sensor accuracy by magnetically separating the sensing system from free DNA and non-hybridized GO. Results indicate that this sensing system is ideal to detect small amounts of DNA-t with limitation detection at 0.12 µM.

scholarly journals Characterization of dispersion strengthened copper with 3wt%Al2O3 by mechanical alloying

2004 ◽  
Vol 36 (3) ◽  
pp. 205-211 ◽  
Author(s):  
Viseslava Rajkovic ◽  
Olivera Eric ◽  
Dusan Bozic ◽  
M. Mitkov ◽  
Endre Romhanji
Keyword(s):  
Mechanical Alloying ◽  
Structural Changes ◽  
Early Stage ◽  
Structure Refinement ◽  
Average Particle Size ◽  
Copper Matrix ◽  
Alumina Powder ◽  
Average Particle ◽  
Micro Hardness ◽  
Electrolytic Copper Powder

The copper matrix has been dispersion strengthened with 3wt.%Al2O3 by mechanical alloying. Commercial alumina powder with an average particle size of 0.75mm was used for alloying. The mechanical alloying process was performed in a planetary ball mill up to 20h in air. After milling all powders were treated in H2 at 4000C for 1h, and finally hot pressing was used for compaction (800oC, 3h, Ar). Structure observations revealed a lamellar structure (Al2O3 particles largely restricted to interlamellar planes between adjacent copper lamellae) accompanied also by structure refinement. These structural changes were mostly completed in the early stage of milling, and retained after compaction. Micro hardness was found to progressively increase with milling time. So, after 5h of milling the micro hardness of the Cu+3twt%Al2O3 compact was 1540MPa, i.e. 2.5 times greater than for the as-received electrolytic copper powder (638MPa) compacted under identical conditions, while after 20h of milling it was 2370 MPa. However after exposing the tested compact at 800oC up to 5h, the achieved hardening effect vanished.

Inducing the magnetic character in reduced graphene oxide through incorporation of Fe2O3 nanoparticles

2017 ◽  
Vol 31 (15) ◽  
pp. 1750118 ◽  
Author(s):  
Abdur Rauf ◽  
Syed Sohail Ahmad Shah ◽  
Sobia Allah Rakha ◽  
Munazza Gul ◽  
Ishaq Ahmad ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Average Particle Size ◽  
Hybrid Structures ◽  
Average Particle ◽  
Multilayer Graphene ◽  
Magnetic Devices ◽  
Reduced Graphene ◽  
20 Nm

A chemical two-step approach based on solvothermal technique has been adopted to synthesize the reduced graphene oxide (rGO)/Fe2O3 hybrid materials. The rGO was prepurified by acidic treatment, followed by sensitization to attach the desired functional groups. The structural, compositional, morphological and magnetic analyzes of the prepared samples were carried out using various characterization techniques. The fabricated rGO/Fe2O3 heterostructures were confirmed by X-ray diffraction analysis and Fourier transform infrared spectroscopy. Raman spectroscopy evidenced the fabrication of multilayer graphene and scanning electron microscopy was carried out to study the morphology of the prepared samples. The average particle size of Fe2O3 nanoparticles (NPs) loaded on rGO was found to be [Formula: see text]20 nm, as was observed during transmission electron microscopy. Thermogravimetric analysis of rGO/Fe2O3 hybrid structures was performed to investigate their thermal behaviors. It was evidenced that the incorporation of Fe2O3 NPs into rGO enhanced its thermal stability. Vibrating sample magnetometry showed that ferromagnetic character was induced in rGO due to involvement of Fe2O3 NPs. The rGO/Fe2O3 hybrid structures can be considered as a competent material for fabrication of various magnetic devices.

scholarly journals Adsorption-Semiconductor Sensor Based on Nanosized SnO2 for Early Warning of Indoor Fires

2021 ◽  
Author(s):  
Nelli Maksymovych ◽  
Ludmila Oleksenko ◽  
George Fedorenko
Keyword(s):  
Tin Dioxide ◽  
Early Stage ◽  
Dynamic Properties ◽  
Sol Gel ◽  
Average Particle Size ◽  
High Sensitivity ◽  
Average Particle ◽  
Semiconductor Sensor ◽  
Wide Range

The paper is devoted for a solution of indoors fires prevention at early stage by determination of H2 (fire precursor gas) in air using a semiconductor sensor. A material based on Pt-containing nanosized tin dioxide with an average particle size of 10–11 nm obtained via a sol–gel method was created for a gas sensitive layer of the sensor. The developed sensor has high sensitivity to H2 micro concentration, a wide range of its detectable content in air, selectivity of H2 measuring in the presence of СО and СН4, good dynamic properties. The combination of these properties is very important for prevention of inflammations on their early stages before the open fires appearance. Economic benefit of the proposed sensor is due to a lower cost and higher reliability of the fire situation detection.

scholarly journals Unravelling the Role of Synthesis Conditions on the Structure of Zinc Oxide-Reduced Graphene Oxide Nanofillers

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2149 ◽  
Author(s):  
Zélia Alves ◽  
Cláudia Nunes ◽  
Paula Ferreira
Keyword(s):  
Zinc Oxide ◽  
Graphene Oxide ◽  
Zinc Acetate ◽  
Zinc Acetate Dihydrate ◽  
Average Particle Size ◽  
Antimicrobial Activities ◽  
Average Particle ◽  
Zno Nanostructures ◽  
Synthesis Conditions

The diversity of zinc oxide (ZnO) particles and derived composites applications is highly dependent on their structure, size, morphology, defect amounts, and/or presence of dopant molecules. In this work, ZnO nanostructures are grown in situ on graphene oxide (GO) sheets by an easily implementable solvothermal method with simultaneous reduction of GO. The effect of two zinc precursors (zinc acetate (ZA) and zinc acetate dihydrate (ZAD)), NaOH concentration (0.5, 1 or 2 M), and concentration (1 and 12.5 mg/mL) and pH (pH = 1, 4, 8, and 12) of GO suspension were evaluated. While the ZnO particle morphology shows to be precursor dependent, the average particle size length decreases with lower NaOH concentration, as well as with the addition of a higher basicity and concentration of GO suspension. A lowered band gap and a higher specific surface area are obtained from the ZnO composites with higher amounts of GO suspension. Otherwise, the low concentration and the higher pH of GO suspension induce more lattice defects on the ZnO crystal structure. The role of the different condition parameters on the ZnO nanostructures and their interaction with graphene sheets was observed to tune the ZnO–rGO nanofiller properties for photocatalytic and antimicrobial activities.

scholarly journals Glucose biosensor using fluorescence quenching with chitosan‐modified graphene oxide

2019 ◽  
Vol 14 (3) ◽  
pp. 344-348 ◽  
Author(s):  
Wenjun Li ◽  
Tingting Jiang ◽  
Yang Pu ◽  
Xudong Jiao ◽  
Wenqiang Tan ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Fluorescence Quenching ◽  
Glucose Biosensor ◽  
Modified Graphene Oxide ◽  
Modified Graphene

Facile Synthesis and Characterizations of Silver Nanoparticles-Reduced Graphene Oxide Hybrid

2021 ◽  
Vol 317 ◽  
pp. 208-213
Author(s):  
Nurul Izrini Ikhsan ◽  
Nurul Ain Mohamed Zamri
Keyword(s):  
Silver Nanoparticles ◽  
Absorption Spectrum ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Large Scale ◽  
Average Particle Size ◽  
Modified Electrodes ◽  
Reducing Agent ◽  
Average Particle ◽  
Reduced Graphene

Here, we report the synthesis of silver nanoparticles-reduced graphene oxide (AgNPs-rGO) hybrid for simple and eco-friendly method. Silver nanoparticles (AgNPs) were successfully deposited on reduced graphene oxide (rGO) sheets to form (AgNPs-rGO) hybrid using lemon extract as a reducing and stabilizing agent. The products form a stable aqueous solution without any surfactant stabilizers and this makes it possible to produce (AgNPs-rGO) hybrid on a large scale using low-cost solution processing technique. The synthesis of nanohybrid was examed at different ratio of reducing agent (1:1, 1:2, 1:4) and characterized using UV-Visible (UV-Vis) absorption spectrum, X-ray diffraction (XRD), Raman spectroscopy analyses and transmission electron microscopy (TEM) analyses. From UV-Vis absorption spectrum, the (AgNPs-rGO) (1:1) hybrid result shows the sharp peak at 433 nm indicating the accomplishment formation of AgNPs on the surface of rGO sheets. Crystalline and spherical AgNPs with an average particle size of 21 nm were found in the (AgNPs-rGO) hybrid with the assistance of 1:1 reducing agent. Furthermore, (AgNPs-rGO) (1:1) hybrid exhibit fast electron-transfer kinetics for electrochemical reaction of Fe (CN)63-/4- redox couple compared to other controlled modified electrodes, suggesting the potential applications for electrocatalysis and electrochemical sensor.

Temperature Sensitivity of Magnetic Nanoparticle Hyperthermia Using IR Thermography

2020 ◽  
pp. 2150002
Author(s):  
Femy Francis ◽  
J. Shebha Anandhi ◽  
G. Antilen Jacob ◽  
D. Sastikumar ◽  
R. Justin Joseyphus
Keyword(s):  
Infrared Thermography ◽  
Temperature Sensitivity ◽  
Magnetite Nanoparticles ◽  
Magnetic Nanoparticle ◽  
Early Stage ◽  
Average Particle Size ◽  
Average Particle ◽  
Thermal Profile ◽  
Stage Of Development ◽  
Magnetic Nanoparticle Hyperthermia

Magnetite nanoparticles are extensively studied for their applications in magnetic nanoparticle hyperthermia. However, existing methods involve invasive methods for monitoring the thermal profile while the heat generated by the magnetite nanoparticles is utilized for cancer therapy. Tumor diagnosis utilizing thermography for monitoring the thermal profile is in the early stage of development since the temperature sensitivity is influenced by various experimental factors. Magnetite nanoparticles embedded in agar matrix which mimics the human tissues and their heating characteristics were investigated using infrared thermography. The magnetite nanoparticles with an average particle size of 10[Formula: see text]nm were subjected to heating in an applied frequency of 500[Formula: see text]kHz. The influence of concentration, area and depth on the heating characteristics of the tumor phantoms were deduced from the thermography images. The parameters that influence the therapeutical sensitivity while using infrared thermography for magnetic nanoparticle hyperthermia, have been studied for potential applications in theranostics.

scholarly journals In vivo toxicity and antitumor activity of newly green synthesized reduced graphene oxide/silver nanocomposites

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohamed M. El-Zahed ◽  
Zakaria A. Baka ◽  
Mohamed I. Abou-Dobara ◽  
Ahmed K. El-Sayed ◽  
Magy M. Aboser ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Average Particle Size ◽  
Ultrastructural Observation ◽  
Average Particle ◽  
Reduced Graphene ◽  
Silver Nanocomposites ◽  
Eac Cells

AbstractA novel biosynthesis of dual reduced graphene oxide/silver nanocomposites (rGO/AgNC) using the crude metabolite of Escherichia coli D8 (MF06257) strain and sunlight is introduced in this work. Physicochemical analysis of these rGO/AgNC revealed that they are sheet-like structures having spherically shaped silver nanoparticles (AgNPs) with an average particle size of 8 to 17 nm, and their absorption peak ranged from 350 to 450 nm. The biosynthesized rGO/AgNC were characterized by UV–vis and FT-IR spectra, X-ray diffraction, Zeta potential and transmission electron microscopy. After the injection of these nanocomposites to mice, their uptake by the kidney and liver has been proven by the ultrastructural observation and estimation of the hepatic and renal silver content. These nanocomposites caused a moderate toxicity for both organs. Changes in the liver and kidney functions and histopathological effects had been observed. The rGO/AgNC revealed a remarkable antitumor effect. They showed a dose-dependent cytotoxic effect on Ehrlich ascites carcinoma (EAC) cells in vitro. Treatment of mice bearing EAC tumors intraperitoneally with 10 mg/kg rGO/AgNC showed an antiproliferative effect on EAC cells, reduced ascites volume, and maintained mice survival. The results indicate that this green synergy of silver nanoparticles with reduced graphene oxide may have a promising potential in cancer therapy.

scholarly journals Synthesis and Characterization of a Silver Nanoparticles-Reduced Graphene Oxide Nanohybrid by using ‘Zingiber Officinale’ Extract as a Reducing and Stabilizing Agent

2019 ◽  
Vol 7 (4.14) ◽  
pp. 498
Author(s):  
Nurul Izrini Ikhsan ◽  
Nur Farahah Jaffar
Keyword(s):  
Silver Nanoparticles ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Large Scale ◽  
Low Cost ◽  
Average Particle Size ◽  
Zingiber Officinale ◽  
Average Particle ◽  
Stabilizing Agent ◽  
Reduced Graphene

An eco-friendly solution-based chemical approach has been used to prepare silver nanoparticles-reduced graphene oxide (AgNPs-rGO) nanohybrid using Zingiber officinale extract as a reducing and stabilizing agent. The products form a stable aqueous solution without any surfactant stabilizers and hence makes it possible to produce AgNPs-rGO nanohybrid on a large scale using low-cost solution processing technique. The nanohybrid was monitored at different concentration of GO solution (0.1 mg/ml, 0.5 mg/ml and 1.0 mg/ml) and characterized using UV- visible (UV-Vis) absorption spectrum, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy analyses. From the UV-Vis analysis, the formation of silver nanoparticles (AgNPs) was confirmed and showed a surface plasmon resonance (SPR) absorption band at 420 nm for nanohybrids with GO concentration of 0.5 mg/ml. Raman spectra shows an increase in ID/IG ratio for rGO with values of 1.007 corresponding to the concentration of GO (0.5mg/ml) as compared to GO (0.88). Completely spherical Ag nanoparticles (NPs) were found at a nanohybrid with 0.5 mg/ml of GO with an average particle size of 20 nm. The AgNPs-rGO(0.5) nanohybrid exhibit fast electron-transfer kinetics for electrochemical reaction of Fe (CN)63-/4- redox couple, suggesting the potential applications for electrocatalysis and electrochemical sensor.  

Electrocatalytic Reduction of Hydrogen Peroxide and Its Non-Enzymatic Electrochemical Detection Using Silver Nanoparticles Anchored on Reduced Graphene Oxide

2019 ◽  
Vol 19 (11) ◽  
pp. 7054-7063 ◽  
Author(s):  
Nurul Izrini Ikhsan ◽  
Perumal Rameshkumar ◽  
Norazriena Yusoff ◽  
Nay Ming Huang
Keyword(s):  
Hydrogen Peroxide ◽  
Silver Nanoparticles ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Electrochemical Detection ◽  
Average Particle Size ◽  
Slight Modification ◽  
Cyclic Voltammograms ◽  
Average Particle ◽  
Reduced Graphene

Silver-reduced graphene oxide (Ag-rGO) nanohybrid was synthesized by applying a slight modification to the Turkevich method using trisodium citrate as a reducing and stabilizing agent to catalyze the non-enzymatic electrochemical detection of hydrogen peroxide (H2O2). Spherical silver nanoparticles (AgNPs) with an average particle size of 2.2 nm surfaced on reduced graphene oxide (rGO) sheets. Cyclic voltammograms (CV) obtained from glassy carbon (GC) electrode coated with Ag-rGO nanohybrid (4 mM) exhibited a peak at an overpotential of -0.52 V, with a larger faradaic current for the reduction of H2O2. Using the modified electrode for the linear sweep voltammetry (LSV) detection of H2O2, the detection limit and sensitivity were determined to be 4.8 μM (S/N ═ 3) and 0.0262 μA μM−1, respectively. The sensor appeared selective and stable towards H2O2 in the presence of possible interference, and it also demonstrated good recoveries of H2O2 concentration in real water samples.

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