scholarly journals Synthesis of gold nanostar using chitosan as reductive agent by the seedless reduction method

2020 ◽  
Vol 4 (4) ◽  
pp. 760-766
Author(s):  
Khuong Quoc Vo ◽  
Hong Tong Thi ◽  
Phuong Phong Thi Nguyen ◽  
Phuc Thanh Hoàng
Keyword(s):  
Gold Nanoparticles ◽  
Structure Directing Agent ◽  
Gold Nanostars ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
Novel Method ◽  
Gold Nanostar ◽  
Average Size

The gold nanostars (AuNS) were prepared through seedless reductive method by using the natural biodegradable polymer chitosan acting both as the stabilizing and shape-directing agent, ascorbic acid as a reducting agent. This reaction synthesis was carried out at room temperature and facile conditions. In an effort to control the size and shape of AuNS, many experimental parameters were investigated for the thorough understanding the role of chitosan in the formation of gold nanostar. In this novel method, the pH condition and appropriate stabilizer concentration were crucial factors to prepare the well-defined AuNS. The obtained AuNS were characterized by many physical-chemistry analysis method such as transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, dynamic light scattering (DLS), and X-Ray diffraction (XRD). The AuNS have an average size of about 55 nm and narrow size distribution when characterized by TEM images. UV-Vis spectroscopy of the gold nanoparticles colloidal solution showed the characteristic peaks at 587-700 nm, corresponding to the surface plasmon resonance of star-shaped nanostructure. The specific interactions between the functional groups of chitosan chain and the as-prepared gold nanostars are analyzed by the FT-IR spectroscopy technique. These results provided insight into the role of biopolymer as both a protecting agent and structure-directing agent. This novel method can overcome previous limitations in controlled synthesis of star-shaped gold nanoparticles such as surfactant use and complex implementation. Besides, the gold nanostars stabilized by chitosan could be a potential material in many applications in the field of biomedical medicine.

scholarly journals Preparation and characterization of highly blue emitting fluorescent carbon nano-dots using Pongammia pinnata fresh leaves

2021 ◽  
Author(s):  
Govindaraju K ◽  
K. Vijai Anand ◽  
S. Muthamilselvan ◽  
M. Kannan ◽  
M. Elanchezhiyan
Keyword(s):  
Electron Microscopy ◽  
Water Soluble ◽  
Hydrothermal Technique ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
Average Size ◽  
Soluble Carbon ◽  
Ft Ir Spectroscopy

Abstract In this study, a simple environmental benign approach have been adopted for the preparation of highly luminescent (blue emitting) water soluble carbon nano-dots using Pongammia pinnata (Pp) leaves via hydrothermal technique. The prepared Pp-carbon nano- dots were characterized using UV-vis spectroscopy, fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. The Pp-carbon nano-dots are spherical in shape with an average size of 32 nm.

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.

BIOSYNTHESIS AND CHARACTERIZATION OF GOLD NANOPARTICLES USING THE ALGA Kappaphycus alvarezii

2010 ◽  
Vol 09 (05) ◽  
pp. 511-516 ◽  
Author(s):  
P. RAJASULOCHANA ◽  
R. DHAMOTHARAN ◽  
P. MURUGAKOOTHAN ◽  
S. MURUGESAN ◽  
P. KRISHNAMOORTHY
Keyword(s):  
Electron Microscopy ◽  
Gold Nanoparticles ◽  
Gold Nanoparticle ◽  
Kappaphycus Alvarezii ◽  
Nanoparticle Synthesis ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
Gold Nanoparticle Synthesis

As a part of our ongoing investigation into the use of algae for gold nanoparticle synthesis, we screened the marine alga Kappaphycus alvarezii, to investigate its efficiency to reduce gold ions as well as the formation of gold nanoparticles. In the present work, we report the reaction condition of the alga K. alvarezii with aqueous gold ions for gold nanoparticle synthesis within the biomass extracellularly. The formation of gold nanoparticles was characterized by UV–Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) method. Moreover, we have found that the reaction of gold ions with the K. alvarezii biomass under stationary conditions results in the rapid extracellular formation of gold nanoparticles of spherical morphology. The gold nanoparticles are not toxic to the cells that continued to grow after the biosynthesis of the gold nanoparticles.

scholarly journals Green synthesis of gold nanoparticles using cinnamon bark extract, characterization, and fluorescence activity in Au/eosin Y assemblies

2020 ◽  
Vol 22 (10) ◽  
Author(s):  
Omar S. ElMitwalli ◽  
Omar A. Barakat ◽  
Rabbani M. Daoud ◽  
Sultan Akhtar ◽  
Fryad Z. Henari
Keyword(s):  
Electron Microscopy ◽  
Gold Nanoparticles ◽  
Spherical Shape ◽  
Bark Extract ◽  
Eosin Y ◽  
Cinnamon Bark ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Average Size ◽  
Fluorescence Peak

Abstract This study reports the synthesis of gold nanoparticles (AuNPs) using an unconventional, eco-friendly method that utilizes cinnamon bark extract as a reducing agent and stabilizer. The synthesized AuNPs were characterized using UV–Vis spectroscopy and transmission electron microscopy (TEM). UV–Vis spectrum shows the surface plasmon resonance (SPR) peak around 535 nm. TEM shows the spherical shape of AuNPs and the particle size distribution at around 35 nm. The ability of the synthesized AuNPs as a quencher of eosin Y dye was monitored using a fluorometer. It was found that in the presence of AuNPs, the fluorescence peak of eosin is quenched. The fluorescence of the mixture of eosin and AuNPs is enhanced in the presence of bovine serum albumin (BSA) protein. TEM shows that the average size of the AuNPs is reduced from 35 to 5 nm with the addition of eosin, and the size of AuNPs then increased to 26 nm upon adding BSA to the mixture of ANPs and eosin. These fluorescence fluctuations may be used for trace identification and biosensing.

scholarly journals Effects of Different Surfactant Charges on the Formation of Gold Nanoparticles by the LASiS Method

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2937
Author(s):  
Muhammad Zulfajri ◽  
Wei-Jie Huang ◽  
Genin-Gary Huang ◽  
Hui-Fen Chen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Laser System ◽  
Synthesis Process ◽  
Au Nps ◽  
Laser Fluences ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
532 Nm

The laser ablation synthesis in solution (LASiS) method has been widely utilized due to its significant prospects in laser microprocessing of nanomaterials. In this study, the LASiS method with the addition of different surfactant charges (cationic CTAB, nonionic TX-100, and anionic SDS) was used to produce Au NPs. An Nd:YAG laser system at 532 nm excitation with some synthetic parameters, including different laser fluences, ablation times, and surfactant concentrations was performed. The obtained Au NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, and zeta potential analyzer. The Au NPs exhibited the maximum absorption peak at around 520 nm for all samples. The color of Au NPs was changed from red to reddish by increasing the laser fluence. The surfactant charges also played different roles in the Au NPs’ growth during the synthesis process. The average sizes of Au NPs were found to be 8.5 nm, 5.5 nm, and 15.5 nm with the medium containing CTAB, TX-100, and SDS, respectively. Besides, the different surfactant charges induced different performances to protect Au NPs from agglomeration. Overall, the SDS and CTAB surfactants exhibited higher stability of the Au NPs compared to the Au NPs with TX-100 surfactant.

A novel electrochemical comparative sensing interface of MgO nanoparticles synthesized by different methods

2017 ◽  
Vol 233 (3) ◽  
pp. 753-762 ◽  
Author(s):  
Utkarsh Jain ◽  
CS Pundir ◽  
Shaivya Gupta ◽  
Nidhi Chauhan
Keyword(s):  
Electrochemical Impedance ◽  
Chemical Reduction ◽  
Cost Effective ◽  
Green Technology ◽  
Mgo Nanoparticles ◽  
Transmission Electron ◽  
Impedance Spectroscopy Study ◽  
Vis Spectroscopy ◽  
Reduction Methods ◽  
Average Size

Recent advancements in nanotechnology, for the biosynthesis of metal nanoparticles through enormous techniques, showed multidimensional developments. One among many facets of nanotechnology is to procure and adopt new advancements for green technology over chemical reduction synthesis. This adaptation for acquiring green nanotechnology leads us to a new dimension of nanobiotechnology. In order to imply one such efforts, in this study the emphasis is being laid on the synthesis of MgO nanoparticles using green technology and eliminating chemical reduction methods. Different characterization techniques such as UV–Vis spectroscopy, transmission electron microscopy, and dynamic light scattering were used to carry out the experiments. The average size of MgO nanoparticles were obtained in the range of 85–95 nm, when synthesized by various sources. The extracts of plants were capable of producing MgO nanoparticles efficiently and exhibited good results during cyclic voltammetry and electrochemical impedance spectroscopy study. The electrode modified with MgO nanoparticles (plant extract) showed good stability (90 days) and high conductivity. This study reports cost-effective and environment-friendly method for synthesis of MgO nanoparticles using plant extracts. The process is rapid, simple, and convenient and can be used as an alternative to chemical method.

scholarly journals Aggregation of Gold Nanoparticles in Presence of the Thermoresponsive Cationic Diblock Copolymer PNIPAAM48-b-PAMPTMA6

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4066
Author(s):  
David Herrera Robalino ◽  
María del Mar Durán del Amor ◽  
Carmen María Almagro Gómez ◽  
José Ginés Hernández Cifre
Keyword(s):  
Gold Nanoparticles ◽  
High Ionic Strength ◽  
Solution Temperature ◽  
Trimethylammonium Chloride ◽  
Aggregation Process ◽  
Critical Solution Temperature ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Copolymer Poly ◽  
Positively Charged

The adsorption of the thermoresponsive positively charged copolymer poly(N-isopropylacrylamide)-block-poly(3-acrylamidopropyl)trimethylammonium chloride, PNIPAAM48-b-PAMPTMA6(+), onto negatively charged gold nanoparticles can provide stability to the nanoparticles and make the emerging structure tunable by temperature. In this work, we characterize the nanocomposite formed by gold nanoparticles and copolymer chains and study the influence of the copolymer on the expected aggregation process that undergoes those nanoparticles at high ionic strength. We also determine the lower critical solution temperature (LCST) of the copolymer (around 42 °C) and evaluate the influence of the temperature on the nanocomposite. For those purposes, we use dynamic light scattering, UV-vis spectroscopy and transmission electron microscopy. At the working PNIPAAM48-b-PAMPTMA6(+) concentration, we observe the existence of copolymer structures that trap the gold nanoparticles and avoid the formation of nanoparticles aggregates. Finally, we discuss how these structures can be useful in catalysis and nanoparticles recovery.

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 The Bio-fabrication of Gold Nanoparticles (AuNPs) by Green Method and Study of its Electrochemical Applications

2020 ◽  
Vol 1 (4) ◽  
pp. 22-25
Author(s):  
Azwan Morni
Keyword(s):  
Gold Nanoparticles ◽  
Ir Spectroscopy ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Green Method ◽  
Oh Groups ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

This study reports a green method for the synthesis of gold nanoparticles (AuNPs) using the aqueous extract of Salix aegyptiaca extract. The effects of gold salt concentration, extract concentration and extract quantity were investigated on nanoparticles synthesis. Novel methods of ideally synthesizing AuNPs are thus thought that are formed at ambient temperatures, neutral pH, low costs and environmentally friendly fashion. AuNPs were characterized with different techniques such as UV–vis spectroscopy, FT-IR spectroscopy, X-ray diffraction, and TEM. FT-IR spectroscopy revealed that gold nanoparticles were functionalized with biomolecules that have primary carbonyl group, -OH groups and other stabilizing functional groups. TEM experiments showed that these nanoparticles are formed with various shapes and X-ray diffraction pattern showed high purity and face centered cubic structure of AuNPs. For electrochemical properties of AuNPs, a modified glassy carbon electrode using AuNPs (AuNPs/GCE) was investigated. The results show that electronic transmission rate between the modified electrode and [Fe (CN)6]3-/4- increased.

Synthesis of Uniform and High Density Silver Nanoparticles by using Peltophorum pterocarpum flower Extract

2014 ◽  
Vol 1584 ◽  
Author(s):  
Matheswaran BALAMURUGAN ◽  
Shanmugam SARAVANAN ◽  
Naoki OHTANI
Keyword(s):  
Silver Nanoparticles ◽  
Fourier Transform ◽  
Electron Microscope ◽  
Ultra Violet ◽  
Capping Agent ◽  
Nanosized Particles ◽  
Flower Extract ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Ft Ir

ABSTRACTSilver nanoparticle (AgNP) is one of the elegant material because its uses in various fields. In this study, AgNPs have been prepared by using Peltophorum pterocarpum (PP) flower extract as reducing and capping agent and aqueous silver nitrate (aq.AgNO3) as silver precursor. The synthesized nanoparticles were characterized using Ultra Violet - Visible (UV-Vis) spectroscopy, High Resolution Transmission Electron Microscope (HR-TEM) and Fourier Transform Infrared Spectroscopy (FT-IR), which reveals the formation of nanosized particles. The UV-Vis spectrum shows an absorption peak around 430nm. HR-TEM images of AgNPs with clear morphology and well dispersed prepared AgNPs.

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