scholarly journals Crystal Growth and Kinetic Behaviour of Pseudoalteromonas espejiana Assisted Biosynthesized Gold Nanoparticles

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Rashmi Gupta ◽  
Gourav Kumar ◽  
Sabya Sachi Das ◽  
Saad Alkahtani ◽  
Abdullah Alkahtane ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Crystal Growth ◽  
Average Particle Size ◽  
Time Interval ◽  
Average Particle ◽  
Ph Profile ◽  
Maximum Production ◽  
Enzyme Substrate ◽  
Gold Precursor ◽  
Substrate Ratio

Pseudoalteromonas espejiana (P. espejiana) is a marine bacterium known for its high resistance to alkalinity. The ability of P. espejiana to reduce Au (III) and biosynthesize gold nanoparticles (AuNPs) is found positive and was confirmed using UV-VIS, EDS, SEM, and TEM studies. Previously, many studies have been reported regarding the crystalline nature of AuNPs; therefore, this research aims at studying the crystal growth behaviour of AuNPs through DLS and TEM studies. Spherically shaped and monodispersed, AuNPs ranging between 5 to 160 nm were obtained with an average particle size of 62 nm. Also, to achieve maximum production of AuNPs, the reaction kinetic study was performed using an ICP-OES method and the effect of various parameters including pH, temperature, rpm, and concentration of substrate was analyzed. During the biosynthesis process, an appropriate phase of nucleation, crystal growth, and saturation was observed and this helped to determine the rate constants and order of reaction. The parameters such as pH profile (pH 9), temperature (30°C), agitation speed (150 rpm), and enzyme substrate ratio (2 : 3) were found to be the best fits for maximum production of low size AuNPs. This demonstrates that in initial few hours, a quick conversion of the ionic gold precursor takes place into metallic gold nuclei, trailed by crystal growth via coalescence of small nuclei. Subsequently, it can be concluded that coalescence processes drive the crystal growth process of AuNPs over a time interval and finally leads to saturation and no newer particle formation in the solution.

scholarly journals Synthesis of Gold Nanoparticles by Using Green Machinery: Characterization and In Vitro Toxicity

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 808
Author(s):  
Ahmed Al Saqr ◽  
El-Sayed Khafagy ◽  
Ahmed Alalaiwe ◽  
Mohammed F. Aldawsari ◽  
Saad M. Alshahrani ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Average Particle Size ◽  
In Vitro Cytotoxicity ◽  
In Vitro Toxicity ◽  
Cervical Cancer Cell Line ◽  
Average Particle ◽  
Anticancer Activities ◽  
Tem Analysis ◽  
Benincasa Hispida

Green synthesis of gold nanoparticles (GNPs) with plant extracts has gained considerable interest in the field of biomedicine. Recently, the bioreduction nature of herbal extracts has helped to synthesize spherical GNPs of different potential from gold salt. In this study, a fast ecofriendly method was adopted for the synthesis of GNPs using fresh peel (aqueous) extracts of Benincasa hispida, which acted as reducing and stabilizing agents. The biosynthesized GNPs were characterized by UV–VIS and Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering. In addition, the in vitro antibacterial and anticancer activities of synthesized GNPs were investigated. The formation of gold nanoparticles was confirmed by the existence of a sharp absorption peak at 520 nm, corresponding to the surface plasmon resonance (SPR) band of the GNPs. TEM analysis revealed that the prepared GNPs were spherical in shape and had an average particle size of 22.18 ± 2 nm. Most importantly, the synthesized GNPs exhibited considerable antibacterial activity against different Gram-positive and Gram-negative bacteria. Furthermore, the biosynthesized GNPs exerted remarkable in vitro cytotoxicity against human cervical cancer cell line, while sparing normal human primary osteoblast cells. Such cytotoxic effect was attributed to the increased production of reactive oxygen species (ROS) that contributed to the damage of HeLa cells. Collectively, peel extracts of B. hispida can be efficiently used for the synthesis of GNPs, which can be adopted as a natural source of antimicrobial and anticancer agent.

Synthesis and Characterization of Water-Soluble Monolayer-Protected Gold Nanoparticles

2011 ◽  
Vol 415-417 ◽  
pp. 617-620 ◽  
Author(s):  
Yan Su ◽  
Ying Yun Lin ◽  
Yu Li Fu ◽  
Fan Qian ◽  
Xiu Pei Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Gold Nanoparticles ◽  
Average Particle Size ◽  
Water Soluble ◽  
Synthesis And Characterization ◽  
Average Particle ◽  
Transmission Electron

Water-soluble gold nanoparticles (AuNPs) were prepared using 2-mercapto-4-methyl-5- thiazoleacetic acid (MMTA) as a stabilizing agent and sodium borohydride (NaBH4) as a reducing agent. The AuNPs product was analyzed by transmission electron microscopy (TEM), UV-vis absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR). The TEM image shows that the particles were well-dispersed and their average particle size is about 5 nm. The UV-vis absorption and FTIR spectra confirm that the MMTA-AuNPs was stabilized by the carboxylate ions present on the surface of the AuNPs.

Near Infrared Tunable Gold Nanoparticles for Low Power Laser Ablation of Esophageal Adenocarcinoma

2012 ◽  
Vol 1416 ◽  
Author(s):  
Guandong Zhang ◽  
Jacek Jasinski ◽  
Dhruvinkumar Patel ◽  
Kurtis James ◽  
Xinghua Sun ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Low Power ◽  
Esophageal Adenocarcinoma ◽  
Near Infrared ◽  
Average Particle Size ◽  
Sodium Thiosulfate ◽  
Molar Ratio ◽  
Average Particle ◽  
Chloroauric Acid ◽  
Nir Absorption

ABSTRACTGold nanoparticles (GNPs) with precisely controlled near infrared (NIR) absorption were synthesized by one-step reaction of chloroauric acid and sodium thiosulfate. The NIR absorption wavelengths and average particle size increase with increasing molar ratio of HAuCl4/Na2S2O3. The as-synthesized GNPs consist of different shape and size, including small spherical gold colloids and larger non-spherical gold crystals. The GNPs with good chemical and optical stability only form in a suitable range of the HAuCl4/Na2S2O3 molar ratio. High molar ratio of HAuCl4/Na2S2O3 reduces GNPs stability due to Ostwald ripening. Chitosan coating improves particle stability and allows these GNPs effective ablation for esophageal adenocarcinoma under low power NIR laser radiation.

Preparation and Characterization of Gold Nanoparticles in the Presence of Citrate and Soybean Seed Extract in an Acidic Conditions

Drug Research ◽  
2017 ◽  
Vol 67 (05) ◽  
pp. 266-270 ◽  
Author(s):  
Ebrahim Izadi ◽  
Ali Rasooli ◽  
Abolfazl Akbarzadeh ◽  
Soodabeh Davaran
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Size Distribution ◽  
Average Particle Size ◽  
Soybean Seed ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Soybean Extract ◽  
Average Size

AbstractThrough the present study, an eco-friendly method was used to synthesize the gold nanoparticles (GNPs) by using the sodium citrate and extract of the soybean seed as reducing the agents at PH 3. X-Ray diffraction (XRD) method was used to evaluate the crystal structure of as-synthesized NPs and it’s revealed that this method leads to well crystallized GNPs. In order to determine the particle size and their distribution, field emission scanning microscopy (FE-SEM) and dynamic light scattering (DLS) were used. The results showed that, the average particle size distribution of synthesized GNPs in solutions containing of the soybean extract and 1% citrate at PH 3 is about 109.6 and 140.9 nm, respectively. Also, we find that the average size of GNPs is 40 and 33 nm from solutions of citrate and soybean extract, respectively. It was concluded that using the extract of soybean seeds as reducing agent can lead to GNPs with small size and narrow size distribution.

scholarly journals Electrochemical Biosensor Based on Furosemide-Gold Nanoparticles for The Determination of Dopamine for Practical Applications

2021 ◽  
Vol 5 (1) ◽  
Keyword(s):  
Gold Nanoparticles ◽  
Average Particle Size ◽  
Average Particle ◽  
Limit Of Quantification ◽  
Strong Absorption Band ◽  
Amperometric Determination ◽  
Practical Applications ◽  
Vis Spectroscopy ◽  
The One

In this study, by taking the advantage of the facile & controlled synthesis of furosemide derived gold nanoparticles (Fr-AuNps) for rapid and sensitive amperometric determination of dopamine (DP). The one-step synthesis of FrAuNps was carried out at room temperature without the use of strong reducing agents. The synthesized Fr-AuNps were studied by UV-Vis spectroscopy, and a strong absorption band for gold nanoparticles was observed at 520 nm. Transmission electron micrographs (TEM) revealed the average particle size below 100 nm. HRTEM showed excellent crystalline features as prepared gold nanoparticles. The electrochemical behavior of gold nanoparticles was examined by cyclic voltammetry (CV) which demonstrated the enhanced electrocatalytic kinetics activity towards the oxidation of dopamine. The presented dopamine biosensor exhibited a linear response for the dopamine in the range of 0.25 to 7 µM. The calculated the detection limit found to be 18.3 nM and limit of quantification 61.5 nM respectively. The proposed dopamine biosensor was successfully employed for the quantification of trace amount of dopamine from human serum and the obtained results are very satisfactory.

CHARACTERIZATION OF PHOTOCHEMICALLY INITIATED GOLD NANOPARTICLES SYNTHESIZED VIA INCOHERENT ULTRAVIOLET RADIATION

2016 ◽  
Vol 78 (3-2) ◽  
Author(s):  
Jia-Cherng Chong ◽  
Siew-Ling Lee ◽  
Noriah Bidin
Keyword(s):  
Gold Nanoparticles ◽  
Ultraviolet Radiation ◽  
Average Particle Size ◽  
Correlation Spectroscopy ◽  
Average Particle ◽  
Nanoparticle Growth ◽  
Particle Stability ◽  
Ultraviolet Wavelength ◽  
Post Synthesis

A modified Turkevich pathway of synthesizing water suspended gold nanoparticles using incoherent ultraviolet radiation as photochemical reaction initiator produced broader absorbance band corresponding to localised surface plasmonresonsnce around 530 nm with average particle size separated into two distinct distributions from 5 nm to 100 nm depending on ultraviolet wavelength. Presence and dynamics of nanoparticle growth was observed with photon correlation spectroscopy where aged colloids produced submicron sized agglomerated particles. Post-synthesis colloidal pH shows gradual degradation of particle stability.  

scholarly journals Development of a Colorimetric Tool for SARS-CoV-2 and Other Respiratory Viruses Detection Using Sialic Acid Fabricated Gold Nanoparticles

Pharmaceutics ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 502
Author(s):  
Haya A. Alfassam ◽  
Majed S. Nassar ◽  
Manal M. Almusaynid ◽  
Bashayer A. Khalifah ◽  
Abdullah S. Alshahrani ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Sialic Acid ◽  
Scattered Light ◽  
Average Particle Size ◽  
Respiratory Viruses ◽  
Lung Epithelial Cells ◽  
Influenza B Virus ◽  
Influenza B ◽  
Average Particle ◽  
Au Nps

Sialic acid that presents on the surface of lung epithelial cells is considered as one of the main binding targets for many respiratory viruses, including influenza and the current coronavirus (SARS-CoV-2) through the viral surface protein hemagglutinin. Gold nanoparticles (Au NPs) are extensively used in the diagnostic field owing to a phenomenon known as ‘surface plasmonic resonance’ in which the scattered light is absorbed by these NPs and can be detected via UV-Vis spectrophotometry. Consequently, sialic acid conjugated Au NPs (SA-Au NPs) were utilized for their plasmonic effect against SARS-CoV-2, influenza B virus, and Middle-East respiratory syndrome-related coronavirus (MERS) in patients’ swab samples. The SA-Au NPs system was prepared by a one-pot synthesis method, through which the NPs solution color changed from pale yellow to dark red wine color, indicting its successful preparation. In addition, the SA-Au NPs had an average particle size of 30 ± 1 nm, negative zeta potential (−30 ± 0.3 mV), and a UV absorbance of 525 nm. These NPs have proven their ability to change the color of the NPs solutions and patients’ swabs that contain SARS-CoV-2, influenza B, and MERS viruses, suggesting a rapid and straightforward detection tool that would reduce the spread of these viral infections and accelerate the therapeutic intervention.

Synthesis of Mesoporous Silica Nanocomposites for Preparation of Gold Nanoparticles

2014 ◽  
Vol 925 ◽  
pp. 233-237 ◽  
Author(s):  
Mohamad Azani Jalani ◽  
Leny Yuliati ◽  
Salasiah Endud ◽  
Hendrik Oktendy Lintang
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Mesoporous Silica ◽  
Sol Gel ◽  
Average Particle Size ◽  
Silica Film ◽  
Cubic Phase ◽  
Average Particle ◽  
Interpore Distance ◽  
Sol Gel Synthesis

Gold nanoparticles (AuNPs) having particle size less than 10 nm can exhibit enhancement of surface area to give high activity such as in catalytic reaction. However, it is hard to synthesize AuNPs with small particle size due to the strong agglomeration. Herein we report that channels of mesoporous silica synthesized via the template sol-gel synthesis can be used to prepare AuNPs by calcination method. Mesoporous silica with an interpore distance of 4.1 nm was successfully fabricated as transparent thin film by using an amphiphilic trinuclear gold (I) pyrazolate complex as a template for the sol-gel synthesis. Upon calcination at 450 °C for 3 h, silica film nanocomposites showed red-shifting of surface plasmon resonance (SPR) bands from 518 (AuNPs from the bulk) to 544 nm owing to decreasing of the average particle size. The formation of AuNPs was also supported by the appearance of diffraction peaks of d111 at 2θ = 38.20° having a cubic phase. Moreover, transmission electron microscope (TEM) images and X-ray diffraction (XRD) peaks also showed smaller and more homogenous distribution of AuNPs.

scholarly journals BIO-NANOPARTICLES: GREEN SYNTHESIS OF GOLD NANOPARTICLES AND ASSESSMENT OF BIOLOGICAL EVALUATION

2019 ◽  
pp. 133-138
Author(s):  
RATIH DYAH PERTIWI ◽  
SUWALDI ◽  
ERNA PRAWITA SETYOWATI ◽  
RONNY MARTIEN
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Zeta Potential ◽  
Absorption Spectra ◽  
Biological Activities ◽  
Average Particle Size ◽  
Antioxidant Properties ◽  
Biological Evaluation ◽  
Nano Particles ◽  
Average Particle

Objective: The design like bio-nano particles are beneficial over chemical and physical composition due to the eco-friendly and lower-cost synthesis of nanoparticles. The current study was purposed for the biosynthesis of gold nanoparticles (GNPs) and their antioxidant evaluation. Methods: Aqua extract of Muntingia calabura, Linn was applied for the synthesis of GNPs and confirmed by UV visible and ATR-Fourier Transform Infra-Red (ATR-FTIR) spectroscopy. Transmission Electron Microscope and Particle Size Analyser were used for the shape zeta potential and determination of size. Antioxidant activity was examined by DPPH (1,1 diphenyl-2-picryl-hydrazyl) radical scavenging method. Results: The result showed that UV–vis absorption spectra of H Au Cl4 at 290 nm while absorption spectra of biosynthesis gold nanoparticles at 540 nm. The forming of nanoparticles were spherical, having an average particle size of 88 nm, and the result of zeta potential was 9.5 mV. Analysis of ATR-FTIR revealed the possible involvement of phytochemical constituents in gold nanoparticles of aqua extract. Green synthesized nanoparticles showed enhanced antioxidant properties. Conclusion: Green synthesized GNPs showed enhanced biological activities. Present results also support the benefit of using the biosynthesis method for the production of gold nanoparticles that have the potential of antioxidant and biology activities.

scholarly journals In SituSynthesis and Deposition of Gold Nanoparticles with Different Morphologies on Glass and ITO Substrate by Ultrasonic Spray Pyrolysis

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
María de la Garza ◽  
Israel López ◽  
Idalia Gómez
Keyword(s):  
Gold Nanoparticles ◽  
Spray Pyrolysis ◽  
Indium Tin Oxide ◽  
Average Particle Size ◽  
Ultrasonic Spray Pyrolysis ◽  
Average Particle ◽  
Particle Sizes ◽  
Ultrasonic Spray ◽  
Ito Film

Gold nanoparticles were synthesized and depositedin situby ultrasonic spray pyrolysis on glass and indium tin oxide (ITO) substrates. This technique led to the formation of gold nanoparticles with different morphologies without the use of any capping agent. The gold nanoparticles deposited on glass substrate were obtained as nanospheres with an average particle size of 30 nm with some agglomerates; however, the nanoparticles deposited on ITO substrate were obtained with different morphologies, such as triangular nanoprisms, nanorods, nanocubes, and nanorhombus, with particle sizes between 40 and 100 nm. The ITO substrate influenced the morphology of the gold nanoparticles obtained due to changes in the deposition temperature, which also change the crystalline structure of the ITO film on the substrate.

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