scholarly journals Synthesis of pH-responsive nanocomposites of gold nanoparticles and graphene oxide and their applications in SERS and catalysis

RSC Advances ◽  
2017 ◽  
Vol 7 (89) ◽  
pp. 56519-56527 ◽  
Author(s):  
Aihua Yao ◽  
Qingge Fu ◽  
Ling Xu ◽  
Yan Xu ◽  
Wenqi Jiang ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Graphene Oxide ◽  
Catalytic Activity ◽  
Dye Molecules ◽  
Ph Responsive ◽  
Au Nps ◽  
Sers Detection ◽  
Ph Dependent

Au NPs–GO nanocomposites, synthesized by decorating Au NPs onto P4VP-grafted GO sheets, displayed pH-dependent catalytic activity towards the reduction of 4-nitrophenol, and selective SERS detection of negatively-charged dye molecules.

scholarly journals Non-Polar and Complementary Resistive Switching Characteristics in Graphene Oxide devices with Gold Nanoparticles: Diverse Approach for Device Fabrication

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Geetika Khurana ◽  
Nitu Kumar ◽  
Manish Chhowalla ◽  
James F. Scott ◽  
Ram S. Katiyar
Keyword(s):  
Gold Nanoparticles ◽  
Graphene Oxide ◽  
Resistive Switching ◽  
Device Fabrication ◽  
Switching Behavior ◽  
Memory Devices ◽  
Bipolar Resistive Switching ◽  
Au Nps ◽  
Conducting Path ◽  
Switching Characteristics

Abstract Downscaling limitations and limited write/erase cycles in conventional charge-storage based non-volatile memories stimulate the development of emerging memory devices having enhanced performance. Resistive random-access memory (RRAM) devices are recognized as the next-generation memory devices for employment in artificial intelligence and neuromorphic computing, due to their smallest cell size, high write/erase speed and endurance. Unipolar and bipolar resistive switching characteristics in graphene oxide (GO) have been extensively studied in recent years, whereas the study of non-polar and complementary switching is scarce. Here we fabricated GO-based RRAM devices with gold nanoparticles (Au Nps). Diverse types of switching behavior are observed by changing the processing methods and device geometry. Tri-layer GO-based devices illustrated non-polar resistive switching, which is a combination of unipolar and bipolar switching. Five-layer GO-based devices depicted complementary resistive switching having the lowest current values ~12 µA; and this structure is capable of resolving the sneak path issue. Both devices show good retention and endurance performance. Au Nps in tri-layer devices assisted the conducting path, whereas in five-layer devices, Au Nps layer worked as common electrodes between co-joined cells. These GO-based devices with Au Nps comprising different configuration are vital for practical applications of emerging non-volatile resistive memories.

A facile construction of Au nanoparticles on a copolymer ligand brushes modified graphene oxide nanoplatform with excellent catalytic properties

RSC Advances ◽  
2016 ◽  
Vol 6 (69) ◽  
pp. 64937-64945 ◽  
Author(s):  
Yajiao Song ◽  
Jianhua Lü ◽  
Bingxin Liu ◽  
Changli Lü
Keyword(s):  
Graphene Oxide ◽  
Catalytic Activity ◽  
Au Nanoparticles ◽  
Catalytic Properties ◽  
High Catalytic Activity ◽  
Au Nps ◽  
Modified Graphene Oxide ◽  
Modified Graphene ◽  
Copolymer Brush

Au NPs were generated via in situ reduction on copolymer brush P(OEGMA-co-MQ) functionalized GO. MQ units in the brushes as capping agents could stabilize the Au NPs. The Au NPs–GO hybrid exhibited high catalytic activity for the reduction of 4-NP.

scholarly journals Amplified visual immunosensor integrated with nanozyme for ultrasensitive detection of avian influenza virus

2017 ◽  
Author(s):  
Syed Rahin Ahmed ◽  
Suresh Neethirajan
Keyword(s):  
Gold Nanoparticles ◽  
Influenza Virus ◽  
Catalytic Activity ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Limit Of Detection ◽  
Blue Color ◽  
Au Nps ◽  
Influenza Virus A ◽  
Practical Applications

ABSTRACTNanomaterial-based artificial enzymes or nanozymes exhibits superior properties such as stability, cost effectiveness and ease of preparation in comparison to conventional enzymes. However, the lower catalytic activity of nanozymes limits their sensitivity and thereby practical applications in the bioanalytical field. To overcome this drawback, herein we propose a very simple but highly sensitive, specific and low-cost dual enhanced colorimetric immunoassay for the detection of avian influenza virus A (H5N1) through facile in situ synthesis of gold nanoparticles and their peroxidase-like enzymatic activity. 3,3’,5,5’-Tetramethylbenzidine (TMBZ) was used as a reducing agent to produce gold nanoparticles (Au NPs) from a viral target-specific antibody-gold ion complex. The developed blue color from the sensing design was further amplified through catalytic activity of Au NPs in presence of TMBZ–hydrogen peroxide (H2O2) complex. The developed dual enhanced colorimetric immunosensor enables the detection of avian influenza virus A (H5N1) with a limit of detection (LOD) of 1.11 pg/mL. Our results further confirms that the developed assay has superior sensitivity than the conventional ELISA method, plasmonic-based bioassay and commercial flu diagnostic kits.

Decoration of Plasma-Reduced Graphene Oxide with Uniform Gold Nanoparticles and their Redox Reaction Performance

2016 ◽  
Vol 701 ◽  
pp. 47-51
Author(s):  
Khairul Anuar Wahid ◽  
M.A.S.M. Haniff ◽  
M. Ismahadi ◽  
Ishak Abdul Azid
Keyword(s):  
Gold Nanoparticles ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Effective Area ◽  
Au Nps ◽  
Sensor Platform ◽  
Reduced Graphene ◽  
Reaction Performance ◽  
Average Size ◽  
Defective Sites

This paper reports a method to enhance the electro-activity on screen printing carbon electrode (SPCE) for electrochemical sensor platform application. The method to forming uniform gold nanoparticles on reduced graphene oxide and SPCE (Au-Nps/rGO/SPCE) based on plasma-enhanced CVD process has been investigated. The results demonstrated that the Au-NPs with high density and uniform sizes were successfully introduced via CVD process where the average size and thickness are 15.9+10nm and 2.18+0.4nm respectively. A high ID/IG ratio for Au-NPs/rGO is 1.01 which 44% higher compared to GO ID/IG ratio was observed in the Raman spectrum suggesting more defective sites on the surface of Au NPS/rGO. The redox performance of Au-NPs/rGO/SPCE has also been measured and compared with rGO/SPCE and the results shown that rGO decorated with Au-NPs has a highest redox current. The peak currents of Au-NPs/rGO are significantly increased compared to the bare SPCE with increment from 0.05mA to 0.14mA. This result is proportional with the effective surface area for SPCE that has been decorated with Au-NPs/rGO where the effective area is increased from 0.126cm2 to 0.166cm2. The peak potential at 0.01V which was found to shift up to 0.4V as the scan rate increases suggested that reaction is electrochemically reversible.

scholarly journals Synthesis, characterization and functional evaluation of gold nanoparticles prepared using Dovyalis abyssinica leaf extracts as reducing and surface capping agent

2021 ◽  
Vol 14 (2) ◽  
pp. 171-190
Author(s):  
Abera Beyene Gebresilassie ◽  
Adam Mekonnen Engida
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Plant Extract ◽  
Radical Scavenging ◽  
Diffraction Spectrum ◽  
Functional Evaluation ◽  
Capping Agent ◽  
Aqueous Fraction ◽  
Au Nps ◽  
Surface Capping

Green synthesis of nanoparticles using plants and microorganisms is biologically safe, cost effective, and environmentally friendly technology. Gold nanoparticles (Au NPs) were synthesized using aqueous extracts of leaves of Dovyalis abyssinica as reducing and surface capping agent and the catalytic activity, antibacterial action and antioxidant potential of the synthesized AU NPs were evaluated. Firstly, HAuCl4 was synthesized in the laboratory from metallic gold and hydrochloric acid using a predesigned method. Secondly, Au NPs was synthesized by mixing HAuCl4 and the plant extract at 45 oC with a digestion time of 1 h. The size of the nanoparticles was modulated by varying the ratio of the plant extract and HAuCl4 with known concentrations. The synthesized Au NPs showed strong absorption around 540 nm which lies in the characteristic absorption region of Au metal nanoparticles (520–580 nm). The X-ray diffraction spectrum of the synthesized Au NPs showed characteristic crystalline structures of gold. The scanning electron spectroscopy images of the synthesized Au NPS revealed the presence of mixed shapes predominantly of irregular shapes and a particle size analyzer displayed an average size of 63.13 nm. The fourier-transform infrared spectrum of Au NPS confirmed the presence of amine, carbonyl and hydroxyl functional groups as surface capping molecules. Although the synthesized Au NPs showed poor bacterial growth inhibition activity on two selected bacteria, it demonstrated excellent free radical scavenging activity against 2, 2-Diphenyl-2-picrylhydrazyl (DPPH) radical and good catalytic activity for degrading bromothymol blue and methyl red compounds. In contrast to the hexane and ethyl acetate extracts, the aqueous fraction was identified as powerful reducing fraction for the synthesis of Au NPs in this experiment. 

scholarly journals Real-time dynamic SERS detection of galectin using glycan-decorated gold nanoparticles

2017 ◽  
Vol 205 ◽  
pp. 363-375 ◽  
Author(s):  
Judith Langer ◽  
Isabel García ◽  
Luis M. Liz-Marzán
Keyword(s):  
Gold Nanoparticles ◽  
Fast Time ◽  
Specific Detection ◽  
Natural Conditions ◽  
Au Nps ◽  
Time Dynamic ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Sers Detection ◽  
Enhanced Raman Scattering

We present the application of surface-enhanced Raman scattering (SERS) spectroscopy for the fast, sensitive and highly specific detection of the galectin-9 (Gal-9) protein in binding buffer (mimicking natural conditions). The method involves the use of specifically designed nanotags comprising glycan-decorated gold nanoparticles encoded with 4-mercaptobenzoic acid. At fast time scales Gal-9 can be detected down to a concentration of 1.2 nM by monitoring the SERS signal of the reporter, driven by aggregation of the functionalized Au NPs tags, induced by Gal-9 recognition. We additionally demonstrate that the sensitivity and concentration working range of the sensor can be tuned via control of aggregation dynamics and cluster size distribution.

Synthesis of a hierarchical SiO2/Au/CeO2 rod-like nanostructure for high catalytic activity and recyclability

RSC Advances ◽  
2015 ◽  
Vol 5 (44) ◽  
pp. 34549-34556 ◽  
Author(s):  
Yuanmei Xu ◽  
Yiwei Zhang ◽  
Yuming Zhou ◽  
Zewu Zhang ◽  
Sanming Xiang ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
High Catalytic Activity ◽  
Au Nps

Uniform hierarchical SiO2/Au/CeO2 rod-like nanostructures were successfully fabricated by combining three individual synthesis steps, in which sub-5 nm gold nanoparticles (Au NPs) were coated with a mesoporous CeO2 shell.

Gold nanoparticles supported on magnesium ferrite and magnesium oxide for the selective oxidation of benzyl alcohol

RSC Advances ◽  
2015 ◽  
Vol 5 (20) ◽  
pp. 15035-15041 ◽  
Author(s):  
Edmilson M. de Moura ◽  
Marco A. S. Garcia ◽  
Renato V. Gonçalves ◽  
Pedro K. Kiyohara ◽  
Renato F. Jardim ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Benzyl Alcohol ◽  
Magnesium Oxide ◽  
Selective Oxidation ◽  
Magnesium Ferrite ◽  
Au Nps ◽  
Oxidation Of Benzyl Alcohol

The presence of K2CO3 significantly increased the catalytic activity and stability of Au NPs supported on magnesium oxide-based supports.

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