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 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.

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.

One-pot synthesis of gold nanoparticles by using 4-aminoantipyrine as a novel reducing and capping agent for simultaneous colorimetric sensing of four triptan-family drugs

2014 ◽  
Vol 6 (15) ◽  
pp. 5972-5980 ◽  
Author(s):  
Karuna A. Rawat ◽  
Kiran R. Surati ◽  
Suresh Kumar Kailasa
Keyword(s):  
Gold Nanoparticles ◽  
Color Change ◽  
Capping Agent ◽  
Colorimetric Sensing ◽  
One Pot ◽  
Au Nps ◽  
One Pot Synthesis

We prepared Au NPs using 4-aminoantipyrine as a novel reagent and the Au NPs aggregation was induced by triptan-family drugs independently, resulting a color change from pink to blue.

scholarly journals Green Method for Synthesis of Gold Nanoparticles Using Polyscias scutellaria Leaf Extract under UV Light and Their Catalytic Activity to Reduce Methylene Blue

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Yoki Yulizar ◽  
Tresye Utari ◽  
Harits Atika Ariyanta ◽  
Digha Maulina
Keyword(s):  
Methylene Blue ◽  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Leaf Extract ◽  
Uv Light ◽  
Reduction Rate ◽  
Hydroxyl Groups ◽  
Face Centered Cubic ◽  
Pseudo First Order Reaction ◽  
Aqueous Fraction

The aqueous fraction of Polyscias scutellaria leaf extract (PSE) has been used as a reducing agent and stabilizer in the green synthesis of gold nanoparticles (AuNPs). UV-Vis spectrophotometry, particle size analyzer (PSA), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy-selected area electron diffraction (TEM-SAED), and X-ray diffraction (XRD) were used to characterize AuNPs. The AuNPs have a size of 5–20 nm and have a face centered cubic (fcc) crystal structure and are stable for 21 days. Phenolic compounds, which are secondary metabolites of PSE, act as an active compound to reduce Au3+ ion to Au0, as well as stabilize the AuNPs through their surface interaction with carbonyl and hydroxyl groups of phenols. AuNPs exhibit excellent catalytic activity for the reduction of methylene blue with NaBH4. The reduction of methylene blue using AuNPs catalysts is a pseudo-first-order reaction with a reduction rate constant (kobs) of 0.0223 min−1.

Facile synthesis of thermo-responsive episulfide group-containing diblock copolymers as robust protecting ligands of gold nanoparticles for catalytic applications

RSC Advances ◽  
2016 ◽  
Vol 6 (44) ◽  
pp. 37487-37499 ◽  
Author(s):  
Dongmei Wang ◽  
Bingxin Liu ◽  
Jianhua Lü ◽  
Changli Lü
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Diblock Copolymers ◽  
Colloidal Stability ◽  
High Catalytic Activity ◽  
Facile Synthesis ◽  
Au Nps ◽  
Catalytic Applications

Well-defined novel thermo-responsive diblock copolymers containing episulfide ligand stabilized Au NPs show interesting assembly morphologies, excellent colloidal stability and high catalytic activity for the reduction of 4-nitrophenol.

scholarly journals Porous Wood Decorated with Gold Nanoparticles as Flow-through Membrane Reactor for Catalytic Hydrogenation of Methylene Blue and 4-Nitrophenol

2021 ◽  
Author(s):  
Yuanyuan Yu ◽  
Qingtong Zhang ◽  
Mingchao Chi ◽  
Hongrui Jiang ◽  
Xi Liu ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Catalytic Hydrogenation ◽  
Organic Contaminants ◽  
Low Cost ◽  
Three Dimensional ◽  
Wood Chip ◽  
Flow Process ◽  
Au Nps

Abstract In this study, gold nanoparticles (Au NPs) were decorated into Paulownia Sieb. et Zucc. chip. Lignin, as one main component of wood, contains the reducing groups e.g. hydroxyl, carbonyl and aldehyde groups. Under sunlight irradiation, Au (III) diffused into wood was in situ reduced by lignin to form gold nanoparticles. Therefore, the Au NPs/Wood was successfully fabricated by this facile and green procedure. Meanwhile, the three-dimensional interpenetrating network of wood prevented the aggregation of Au NPs which retained its catalytic activity. Methylene blue and 4-nitrophenol were adopted as model organic contaminants to evaluate the catalytic hydrogenation ability of the Au NPs/Wood. The analyses of XRD, SEM, ICP-MS and XPS indicated that Au NPs were successfully immobilized in wood chip. The degradation results revealed that the Au NPs/Wood has excellent catalytic activity for methylene blue and 4-nitrophenol hydrogenation under batchwise and continuous flow process. Meanwhile, the Au NPs/Wood also exhibited excellent recyclability. The hydrogenation efficiency of MB and 4-NP still reaches more than 90% after 8 cycles. This study provides a new solution for green and low-cost fabrication of Au NPs/Wood which has broad application prospects in wastewater treatment.

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 Mycosynthesis of biocompatible gold nanoparticles using Penicillium sp for bromothymol blue degradation

Biomedicine ◽  
2020 ◽  
Vol 39 (2) ◽  
pp. 346-352
Author(s):  
B. S. Srinath ◽  
S. Gowda Ganesh ◽  
P Shastry Rajesh ◽  
K. Byrappa
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Color Change ◽  
Bromothymol Blue ◽  
Fungal Culture ◽  
Visible Spectroscopy ◽  
Au Nps ◽  
Penicillium Sp ◽  
Haemolytic Assay ◽  
Uv Visible

Introduction and Aim: The Biosynthesis of Gold nanoparticles (Au NPs) is an eco-friendly, cost effective and nontoxic alternative to chemical and physical methods. In the present study synthesis of Au NPs was performed by using a fungi Penicillium sp. isolated from agriculture soil. Materials and Methods: Fungi was isolated from the agricultural field and inoculated into Sabouraud Dextrose broth and incubated at 28º C in a shaker at 180 rpm for 96 to 120 hours. After incubation, the fungal culture was filtered and centrifuged, obtained fungal cell free extracts treated with 1mM gold salt (HAuCl4). The synthesis of Au NPs was confirmed by UV–visible spectroscopy and particles size was measured using Dynamic Light Scattering (DLS). Haemolytic assay of Au NPs was carried out using Chicken RBCs and results measured at 540 nm in UV-visible spectrophotometer. To study catalytic activity, Bromothymol blue (BB) was subjected to reduction by using sodium borohydride (NaBH4, 5.28X10-2 M) in the presence of Au NPs. Then the color change was monitored by visual observation. Results: The synthesis of Au NPs was preliminary observed by a color change from yellow to purple and confirmed by a peak at 560 nm using a UV–visible spectroscopy. The DLS analysis showed that the Au NPs were poly-dispersed and size ranges from 130 to 150 nm. The biosynthesised Au NPs was studied  for their biocompatibility and dye degradation properties. Conclusion: The obtained results revealed that biosynthesized Au NPs shows a minimum level of toxicity to chicken erythrocytes and good catalytic activity towards the degradation of hazardous dye bromothymol blue. These nanoparticles could be potentially useful in various applications in medical and environmental fields.  

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