scholarly journals PEGylated Gold Nanoparticles with Interesting Plasmonic Properties Synthesized Using an Original, Rapid, and Easy-to-Implement Procedure

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ștefan Nițică ◽  
Alin Iulian Moldovan ◽  
Valentin Toma ◽  
Cristian Silviu Moldovan ◽  
Ioana Berindan-Neagoe ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Synthesis Method ◽  
Average Diameter ◽  
Liquid Droplets ◽  
Sers Substrates ◽  
New Class ◽  
One Step ◽  
Short Synthesis ◽  
Spherical Gold Nanoparticles ◽  
Synthesis Procedure

In this letter, we report a new, one-step, rapid, and easy-to-implement method for the synthesis of PEGylated gold nanoparticles (PEG-AuNPs) having a narrow size distribution and very interesting plasmonic properties. Unmodified polyethylene glycol molecules with a molecular weight of 1000 g/mole (PEG1000) have been employed as reducing and capping agents for the synthesis of spherical gold nanoparticles having an average diameter of 35 nm, within a few minutes. The novelty of the herein proposed synthesis method consists in the fact that the synthesis takes place inside of a sealed bottle flask containing aqueous solutions of PEG1000, tetrachloroauric(III) acid (HAuCl4), and NaOH, placed in the center of a microwave oven, capable to provide a very uniform temperature environment. It turned out that, during the very short synthesis procedure (2 minutes), PEG 1000 suffers an oxidative transformation in such a manner that its terminal alcohol groups (-CH2-OH) are transformed in carboxylate ones (-COO−). The as-synthesized PEG-AuNPs possess very interesting plasmonic properties allowing the detection of different molecules by means of SER spectroscopy performed either in liquid droplets or on solid spots. As a consequence of their unique plasmonic properties, the SER spectra acquired using this new class of nanoparticles on different molecules of interest (methylene blue, rhodamine 6G, doxorubicin, and 5-fluorouracil) are highly reproducible, making them ideal candidates for further use as SERS substrates.

Preparation of Submicron Metastable Spherical β-Bi2O3 Particles by Self-Propagating High-Temperature Synthesis Method

2019 ◽  
Vol 19 (11) ◽  
pp. 7436-7441
Author(s):  
Chu Zhang ◽  
Qi-Yu Wang ◽  
Ming-De Li ◽  
Guo-Dong Zhang
Keyword(s):  
High Temperature ◽  
High Efficiency ◽  
Synthesis Method ◽  
Reaction System ◽  
Average Diameter ◽  
Spherical Particles ◽  
Molar Ratio ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
One Step

Sub-micrometer particles of β-Bi2O3 were successfully synthesized via a one-step self-propagating high-temperature synthesis (SHS) method for the first time. The experiments were carried out in the air at room temperature. The products were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). In this study, three experiments were designed to optimize the heat source, Bi source and additive for the reaction system. Results showed that the system composed of Al, Bi2O3 and Al2O3 powders could synthesize monodisperse high-purity β-Bi2O3 spherical particles with the average diameter of 369 nm and the as-prepared products kept stable after being exposed in air for one month. Then, the influences of the ratio of the three components on system were investigated. Interestingly, it was found that a slight adjustment on the ratio of Al:Bi2O3:Al2O3 had significant effects on the reactions happening in a system. Specifically, when the amount of Al2O3 exceeds the molar ratio of 2:1:1 (Al:Bi2O3:Al2O3), it is difficult to ignite the reaction system; when the amount is less than 2:1:0.5, the reaction system becomes too violent to obtain pure products. However, there are no obvious differences on the morphology and structure of final products with the two ratios because of few changes in adiabatic temperature. Preparation of β-Bi2O3 by SHS technique enjoying many advantages, such as high efficiency, inexpensive experimental equipment and simple processes, would has a promising prospect for industrial application.

scholarly journals A Hybrid Nanoplatform of Graphene Oxide/Nanogold for Plasmonic Sensing and Cellular Applications at the Nanobiointerface

2019 ◽  
Vol 9 (4) ◽  
pp. 676 ◽  
Author(s):  
Lorena Cucci ◽  
Irina Naletova ◽  
Giuseppe Consiglio ◽  
Cristina Satriano
Keyword(s):  
Gold Nanoparticles ◽  
Graphene Oxide ◽  
Microscopy Imaging ◽  
Human Neuroblastoma ◽  
Force Microscopy ◽  
Atomic Force ◽  
Plasmonic Sensing ◽  
One Step ◽  
Spherical Gold Nanoparticles ◽  
Species Production

In this study, nanocomposites of spherical gold nanoparticles (AuNPs) and graphene oxide (GO) nanosheets were fabricated by a simple one-step reduction method. The characterisation by UV-visible spectroscopy of the plasmonic sensing properties pointed out to a strong interaction between graphene and metal nanoparticles in the hybrid GO-AuNP, as confirmed by nuclear magnetic resonance. Moreover, atomic force microscopy analyses demonstrated that the gold nanoparticles were mostly confined to the basal planes of the GO sheets. The response of the nanoassemblies at the biointerface with human neuroblastoma SH-SY5Y cell line was investigated in terms of nanotoxicity as well as of total and mitochondrial reactive oxygen species production. Confocal microscopy imaging of cellular internalization highlighted the promising potentialities of GO-AuNP nanoplatforms for theranostic (i.e., sensing/imaging + therapy) applications.

scholarly journals Advantages of Highly Spherical Gold Nanoparticles as Labels for Lateral Flow Immunoassay

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3608
Author(s):  
Nadezhda A. Byzova ◽  
Anatoly V. Zherdev ◽  
Boris N. Khlebtsov ◽  
Andrey M. Burov ◽  
Nikolai G. Khlebtsov ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Au Nanoparticles ◽  
Troponin I ◽  
Limit Of Detection ◽  
Average Diameter ◽  
Covalent Immobilization ◽  
Lateral Flow ◽  
Antibody Immobilization ◽  
Site Testing ◽  
Spherical Gold Nanoparticles

The use of lateral flow immunoassays (LFIAs) for rapid on-site testing is restricted by their relatively high limit of detection (LoD). One possible way to decrease the LoD is to optimize nanoparticle properties that are used as labels. We compare two types of Au nanoparticles: usual quasispherical gold nanoparticles (C-GNPs), obtained by the Turkevich–Frens method, and superspherical gold nanoparticles (S-GNPs), obtained by a progressive overgrowth technique. Average diameters were 18.6–47.5 nm for C-GNPs and 20.2–90.4 nm for S-GNPs. Cardiomarker troponin I was considered as the target analyte. Adsorption and covalent conjugation with antibodies were tested for both GNP types. For C-GNPs, the minimal LoD was obtained with 33.7 nm nanoparticles, reaching 12.7 ng/mL for covalent immobilization and 9.9 ng/mL for adsorption. The average diameter of S-GNPs varied from 20.2 to 64.5 nm, which resulted in a decrease in LoD for an LFIA of troponin I from 3.4 to 1.2 ng/mL for covalent immobilization and from 2.9 to 2.0 ng/mL for adsorption. Thus, we obtained an 8-fold decrease in LoD (9.9 to 1.2 ng/mL) by using S-GNPs. This effect can be related to more effective antibody immobilization and improved S-GNP optical properties. The obtained results can improve LFIAs for various practically significant analytes.

scholarly journals Synthesis of Monodispersed Gold Nanoparticles with Exceptional Colloidal Stability with Grafted Polyethylene Glycol-g-polyvinyl Alcohol

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Alaaldin M. Alkilany ◽  
Alaa I. Bani Yaseen ◽  
Mohammed H. Kailani
Keyword(s):  
Gold Nanoparticles ◽  
Polyethylene Glycol ◽  
Polyvinyl Alcohol ◽  
Colloidal Stability ◽  
Kinetic Mechanism ◽  
Grafted Copolymer ◽  
Synthesis Parameters ◽  
Salt Addition ◽  
One Step ◽  
Spherical Gold Nanoparticles

Herein, we report the synthesis of spherical gold nanoparticles with tunable core size (23–79 nm) in the presence of polyethylene glycol-g-polyvinyl alcohol (PEG-g-PVA) grafted copolymer as a reducing, capping, and stabilizing agent in a one-step protocol. The resulted PEG-g-PVA-capped gold nanoparticles are monodispersed with an exceptional colloidal stability against salt addition, repeated centrifugation, and extensive dialysis. The effect of various synthesis parameters and the kinetic/mechanism of the nanoparticle formation are discussed.

scholarly journals One-Step Synthesis of PEG-Coated Gold Nanoparticles by Rapid Microwave Heating

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Seung Kwon Seol ◽  
Daeho Kim ◽  
Sunshin Jung ◽  
Won Suk Chang ◽  
Ji Tae Kim
Keyword(s):  
Gold Nanoparticles ◽  
Microwave Heating ◽  
Homogeneous Nucleation ◽  
Growth Parameters ◽  
Average Diameter ◽  
Gold Particles ◽  
Initial Stage ◽  
High Uniformity ◽  
One Step ◽  
Primary Gold

Polyethylene Glycol- (PEG-) coated gold nanoparticles (PEG-AuNPs) are synthesized by a one-step route with rapid microwave heating. Homogeneous nucleation of the primary gold particles is enhanced by increasing the applied microwave power during the initial stage of the synthesis, increasing the temperature ramping rate (Rr) and resulting in decreased size and improved uniformity of the synthesized PEG-AuNPs. Using rapid microwave heating, we successfully produce uniform colloidal PEG-AuNPs with an average diameter of14.3±2.5 nm within a few minutes. By appropriate tuning of the growth parameters, microwave synthesis can produce largely colloidal PEG-AuNPs with high uniformity.

scholarly journals Raman Activity of HS-(CH2 ) –NH-Coumarin Molecule Adsorbed on the Surface of Gold Nanostructures with various Morphologies

2021 ◽  
Vol 4 (3) ◽  
Keyword(s):  
Gold Nanoparticles ◽  
Enhancement Factor ◽  
Surface Adsorption ◽  
Average Diameter ◽  
Gold Nanostructures ◽  
Average Particle ◽  
Gold Nanowires ◽  
Particle Sizes ◽  
Nucleation Process ◽  
Spherical Gold Nanoparticles

Synthesis of gold nanowires with an average diameter of 10 nm and length of up to 20 µm was achieved through a three-step heterogeneous nucleation process. Gold nanowires were formed through coalescence of spherical nanocrystals leading to grain growth and subsequently uneven nanowires. Furthermore, the uneven gold nanowires experienced thinning driven by thermodynamics to form relatively even nanowires with smaller diameters. Gold nanowires showed enhanced Raman activity in respect to enhancement factor than respective spherical gold nanoparticles with average particle sizes of 14 nm, 30 nm and 40 nm. The better Raman activity of gold nanowires with respect to spherical morphology was attributed to how they adsorb Raman active molecules, which are surface adsorption and network entanglement.

scholarly journals One-Step Synthesis of Silver Nanowires with Ultra-Long Length and Thin Diameter to Make Flexible Transparent Conductive Films

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 401 ◽  
Author(s):  
Yuxiu Li ◽  
Ximin Yuan ◽  
Hongwei Yang ◽  
Yunxiu Chao ◽  
Shuailong Guo ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Sheet Resistance ◽  
Silver Nanowires ◽  
Average Length ◽  
Synthesis Method ◽  
Average Diameter ◽  
Hydroxyethyl Cellulose ◽  
Molar Ratio ◽  
Conductive Film ◽  
One Step

High aspect ratio silver nanowires (AgNWs) with ultra-long length and thin diameter were synthesized through bromine ion (Br−)-assisted one-step synthesis method. The bromine ions were used as pivotal passivating agent. When the molar ratio of Br−/Cl− was 1:4, the average diameter of AgNWs was as low as ~40 nm, the average length was as high as ~120 μm, and the aspect ratio reached 2500. Networks of AgNWs were fabricated using as-prepared high-quality AgNWs as conducting material and hydroxyethyl cellulose (HEC) as the adhesive polymer. As a result, a low sheet resistance down to ~3.5 Ω sq−1 was achieved with a concomitant transmittance of 88.20% and a haze of 4.12%. The ultra-low sheet resistance of conductive film was attributed to the long and thin AgNWs being able to form a more effective network. The adhesion of the AgNWs to the substrate was 0/5B (ISO/ASTM). The insights given in this paper provide the key guidelines for bromine ion-assisted synthesis of long and thin AgNWs, and further designing low-resistance AgNW-based conductive film for optoelectronic devices.

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