scholarly journals The Effect of the Antioxidant Activity of Plant Extracts on the Properties of Gold Nanoparticles

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1655 ◽  
Author(s):  
Natalia Yu. Stozhko ◽  
Maria A. Bukharinova ◽  
Ekaterina I. Khamzina ◽  
Aleksey V. Tarasov ◽  
Marina B. Vidrevich ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Gold Nanoparticles ◽  
Sodium Citrate ◽  
Formation Rate ◽  
Leaf Extracts ◽  
Absolute Value ◽  
Transmission Electron ◽  
The Stability ◽  
Kinetics Of ◽  
Selection Of

Synthesis of gold nanoparticles (phyto-AuNPs) with the use of leaf extracts (phytosynthesis) is based on the concept of Green Chemistry. The present study is conducted to discuss how antioxidant activity (AOA) of extracts from plant leaves impacts on the kinetics of phytosynthesis, the size of the formed nanoparticles, and the stability of their nanosuspensions. Results show that the formation rate of phyto-AuNPs suspensions accelerate due to the increase in the AOA of the extracts. Accompanying the use of transmission electron microscopy (TEM), UV-Vis-spectrophotometry and dynamic light scattering (DLS), it also has been found that higher AOA of the extracts leads to a decrease in the size of phyto-AuNPs, an increase in the fraction of small (d ≤ 5 nm), and a decrease in the fraction of large (d ≥ 31–50 nm) phyto-AuNPs, as well as an increase in the zeta potential in absolute value. Phyto-AuNPs suspensions synthesized with the use of extracts are more resistant to destabilizing electrolytes and ultrasound, as compared to suspensions synthesized using sodium citrate. Thus, the AOA of the extract is an important parameter for controlling phytosynthesis and predicting the properties of phyto-AuNPs. The proposed approach can be applied to the targeted selection of plant extract that will be used for synthesizing nanoparticles with desired properties.

scholarly journals Biosynthesized gold nanoparticles-doped hydroxyapatite as antibacterial and antioxidant nanocomposite

2021 ◽  
Author(s):  
Is Fatimah ◽  
Putwi Widya Citradewi ◽  
Amri Yahya ◽  
Bambang Nugroho ◽  
Habibi Hidayat ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Antioxidant Activity ◽  
Particle Size ◽  
Gold Nanoparticles ◽  
Antibacterial Activity ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Dpph Scavenging Activity ◽  
Dpph Scavenging

Abstract The composite of green synthesized gold nanoparticles (Au NPs)-doped hydroxyapatite (HA) has been prepared. The gold nanoparticles were produced via bioreduction of HAuCl4 with Clitoria ternatea flower extract, and utilized in the synthesis of hydroxyapatite using Ca(OH)2 and ammonium diphosphate as precursor. The aim of this research is to study the structural analysis of the composite and antibacterial activity test toward Eschericia coli, Staphylococcus aureus, Klebsiela pneumoniae, and Streptococcus pyogenes. In addition, the antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging method. The monitoring of gold nanoparticles formation was conducted by UV–vis spectroscopy and particle size analyses, meanwhile the synthesized composite was studied using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results showed that homogeneously dispersed gold nanoparticles in HA structure was obtained with the particle size ranging at 5-80 nm. The nanocomposite demonstrated antibacterial activity against tested bacteria. The nanocomposite expressed an antioxidant activity as shown by the DPPH scavenging activity of 66 and 58% at the concentration of 100 μg/mL and 50 μg/mL, respectively.

scholarly journals On the Stability of 3C-SiC Single Crystals at High Temperatures

2012 ◽  
Vol 717-720 ◽  
pp. 493-496
Author(s):  
Deborah Dompoint ◽  
Irina G. Galben-Sandulache ◽  
Alexandre Boulle ◽  
Didier Chaussende ◽  
Dominique Eyidi ◽  
...  
Keyword(s):  
Single Crystals ◽  
Volume Fraction ◽  
Diffuse Intensity ◽  
X Ray ◽  
Partial Dislocations ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
The Stability ◽  
Kinetics Of ◽  
Evolution With Time

The 3C-6H polytypic transition in 3C-SiC single crystals is studied by means of diffuse X-ray scattering (DXS) coupled with transmission electron microscopy (TEM). TEM reveals that the partially transformed SiC crystals contain regions of significantly transformed SiC (characterized by a high density of stacking faults) co-existing with regions of pure 3C-SiC. The simulation of the diffuse intensity allows to determine both the volume fraction of transformed material and the transformation level within these regions. It is further shown that the evolution with time and temperature of the transition implies the multiplication and glide of partial dislocations, the kinetics of which are quantified by means of DXS.

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

Micromachines ◽  
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.

scholarly journals Biosynthesis and Kinetics of Silver Nanoparticles Formation by Reduction using Banana Kepok (Musa balbisiana) Peel Extract

2018 ◽  
Vol 17 (2) ◽  
pp. 77 ◽  
Author(s):  
Wara Dyah Pita Rengga ◽  
Dhimas Setiawan ◽  
Khosiatun Khosiatun
Keyword(s):  
Silver Nanoparticles ◽  
Formation Rate ◽  
Spherical Particles ◽  
Banana Peel ◽  
Musa Balbisiana ◽  
Transmission Electron ◽  
The Face ◽  
Face Centered ◽  
Kinetics Of ◽  
Peel Extract

Biosynthesis and silver nanoparticles formation during the reduction of AgNO3were carried out by using an aqueous peel extract of banana kepok (Musa balbisiana) asa stabilizing agent. The formation of the stable silver nanoparticles with differentconcentration of AgNO3 has resulted in mostly spherical particles. The Ultraviolet-Visiblespectrophotometer, Transmission Electron Microscopy, X-Ray Diffractometer were usedto characterize these biosynthesized silver nanoparticles. The spherical shapednanoparticles were uniformly distributed with the range diameter of 5 to 50 nm and theparticles were naturally crystallized with the crystal structure of the face-centered cubicgeometry. Additionally, the kinetics of the formation process of silver nanoparticles wasobserved by the UV-Vis spectrophotometer. Based on the kinetic functions, the reductionprocess of banana peel extract had a constant formation rate of the autocatalytic processat 4.35 x 10-4/s.

Microwave-Assisted Synthesis of Unmodified Gold Nanoparticles for Colorimetric Detection of Dopamine

2017 ◽  
Vol 730 ◽  
pp. 167-171 ◽  
Author(s):  
Ekarat Detsri ◽  
Kanrayasiri Kamhom ◽  
Chatsuda Detsri
Keyword(s):  
Gold Nanoparticles ◽  
Sodium Citrate ◽  
Limit Of Detection ◽  
Signal To Noise Ratio ◽  
Chemical Reduction ◽  
Colorimetric Detection ◽  
Random Coil ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Transmission Electron

Unmodified gold nanoparticles (AuNPs) have been successfully synthesized by the chemical reduction of tetrachloride gold (III) ions ([AuCl4]-) in the presence of sodium citrate based on the rapid microwave−assisted approach. The diameter of the synthesized nanoparticles was found in the range of 16.50±2.75 nm. The AuNPs were characterized using UV−vis spectrophotometer, zeta potential analyzer and transmission electron microscope (TEM). The sodium citrate protected AuNPs were found to be selective and sensitive for the detection of dopamine. It was based on the aggregation change of the nanoparticles from random coil to hairpin structure upon the addition of dopamine concentration. The red shift of the plasmonic peak wavelength of AuNPs could be used for the detection of dopamine. The response to dopamine allows for a linear range from 10 to 125 mg⋅L-1 (R2 = 0.9804) with a limit of detection (LOD) at a signal to noise ratio of 3 of 12.85±1.38 mg⋅L-1. The colorimetric sensor was evaluated with 98.0−99.9% recovery of added dopamine in urine sample. The proposed sensor was successfully applied to the determination of dopamine in biological samples.

scholarly journals Role of Surfactant in the Formation of Gold Nanoparticles in Aqueous Medium

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Abhishek Das ◽  
Ridhima Chadha ◽  
Nandita Maiti ◽  
Sudhir Kapoor
Keyword(s):  
Gold Nanoparticles ◽  
Aqueous Medium ◽  
Sodium Dodecyl ◽  
Chloroauric Acid ◽  
Synthesis Mechanism ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
The Stability ◽  
Mediated Reduction

The stability of gold nanoparticles is a major issue which decides their impending usage in nanobiotechnological applications. Often biomimetically synthesized nanoparticles are deemed useless owing to their instability in aqueous medium. So, surfactants are used to stabilize the nanoparticles. But does the surfactant only stabilize by being adsorbed to the surface of the nanoparticles and not play significantly in moulding the size and shape of the nanoparticles? Keeping this idea in mind, gold nanoparticles (GNPs) synthesized by l-tryptophan (Trp) mediated reduction of chloroauric acid (HAuCl4) were stabilized by anionic surfactant, sodium dodecyl sulphate (SDS), and its effect on the moulding of size and properties of the GNPs was studied. Interestingly, unlike most of the gold nanoparticles synthesis mechanism showing saturation growth mechanism, inclusion of SDS in the reaction mixture for GNPs synthesis resulted in a bimodal mechanism which was studied by UV-Vis spectroscopy. The mechanism was further substantiated with transmission electron microscopy. Zeta potential of GNPs solutions was measured to corroborate stability observations recorded visually.

scholarly journals The Types of Polysaccharide Coatings and Their Mixtures as a Factor Affecting the Stability of Bioactive Compounds and Health-Promoting Properties Expressed as the Ability to Inhibit the α-Amylase and α-Glucosidase of Chokeberry Extracts in the Microencapsulation Process

Foods ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1994
Author(s):  
Kamil Haładyn ◽  
Karolina Tkacz ◽  
Aneta Wojdyło ◽  
Paulina Nowicka
Keyword(s):  
Antioxidant Activity ◽  
Sodium Alginate ◽  
Guar Gum ◽  
Polyphenolic Compounds ◽  
Alginate Solution ◽  
Polyphenolic Content ◽  
Negative Effect ◽  
Health Promoting ◽  
The Stability ◽  
Selection Of

This study aimed to evaluate the feasibility of microencapsulating chokeberry extract by extrusion, and assess the effects of the selected carrier substance on the contents of polyphenolic compounds, antioxidant activity, color of microspheres, and ability of microspheres to inhibit α-amylase and α-glucosidase, after 14 and 28 days of storage. The results showed that appropriate selection of the polysaccharide coating is of great importance for the proper course of the microencapsulation process, the polyphenolic content of chokeberry capsules, and their antioxidant and antidiabetic properties. The addition of guar gum to a sodium alginate solution significantly increased the stability of polyphenolic compounds in microspheres during storage, whereas the addition of chitosan had a significantly negative effect on the stability of polyphenols. The coating variant composed of sodium alginate and guar gum was also found to be the most favorable for the preservation of the antioxidant activity of the capsules. On the other hand, capsules composed of sodium alginate, guar gum, and chitosan showed the best antidiabetic properties, which is related to these tricomponent microspheres having the best α-glucosidase inhibition.

Sunlight-Driving Formation and Characterization of Size-Controlled Gold Nanoparticles

2007 ◽  
Vol 7 (2) ◽  
pp. 708-711 ◽  
Author(s):  
Yonglan Luo
Keyword(s):  
Gold Nanoparticles ◽  
Sodium Citrate ◽  
Noble Metal Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron Microcopy ◽  
Uv Visible ◽  
Size Controlled

Exposing a sodium citrate-HAuCl4 aqueous solution to sunlight results in the formation of size-controlled, citrate-capped gold nanoparticles. The gold nanoparticles were characterized by UV-visible, transmission electron microscopy (TEM), scanning electron microcopy (SEM), and X-ray diffraction (XRD) spectroscopic methods. It provides a general methodologyfor the economic, convenient, mild preparation of citrate-capped noble metal nanoparticles.

scholarly journals Thermokinetics and rheology of agarose gel applied to bioprinting technology

2020 ◽  
Vol 24 (1 Part A) ◽  
pp. 347-353
Author(s):  
Boris Pokusaev ◽  
Andrey Vyazmin ◽  
Nikolay Zakharov ◽  
Sergey Karlov ◽  
Dmitry Nekrasov ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Point Of View ◽  
Gel Formation ◽  
Operating Modes ◽  
Preliminary Preparation ◽  
Immobilized Microorganisms ◽  
The Stability ◽  
And Storage ◽  
Kinetics Of ◽  
Selection Of

The paper presents new results on the study of thermokinetics of gel system based on agarose in the process of transition from solution to gel and opposite. This issue is extremely relevant, since the stability and predictability of thermophysical and rheological properties in such transformations, especially in the presence of components of the nutrient medium and immobilized microorganisms, come to the fore in terms of design and selection of modes of operation of the printing device promising 3-D bioprinters, as well as the system of preparation and storage of the presence of the hysteresis effect, both from the point of view of the kinetics of gel formation and from the point of view of the dependence of rheological properties on temperature, at different concentrations of modifying components, is shown. The obtained results allow to draw a conclusion about the possibility of using the scheme with preliminary preparation of the initial biogel for the implementation of bioprinting technology based on agarose, and to recommend the obtained values for modeling the operating modes of devices of this type.

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