Polymer-embedded gold and gold/silver nanoparticle-modified electrodes and their applications in catalysis and sensors

2011 ◽  
Vol 83 (11) ◽  
pp. 2041-2053 ◽  
Author(s):  
Shanmugam Manivannan ◽  
Ramasamy Ramaraj
Keyword(s):  
Gold Nanoparticles ◽  
Silver Nanoparticles ◽  
Sol Gel ◽  
Simultaneous Detection ◽  
Modified Electrodes ◽  
Core Shell ◽  
Electrochemical Characteristics ◽  
Amine Functionalized ◽  
Gold Silver ◽  
Vis Spectroscopy

Metal nanoparticles encapsulated by silicate sol-gel matrix find numerous applications particularly in electrocatalysis and sensors. In our previous reports, we have reported the mono- and bi-metal gold, silver, and core/shell gold/silver nanoparticles embedded in functionalized silicate sol-gel matrices. Modified electrodes were fabricated using mono- and bi-metallic gold, silver, and core/shell gold/silver nanoparticles embedded in silicate sol-gel, and they were used for the electrocatalysis and sensing of H2O2 and simultaneous detection of hydrazine, sulfite, and nitrite. We have prepared the gold nanoparticles encapsulated by amine-functionalized silicate sol-gel matrix in a single step without using any external reducing agents. The gold nanoparticles were also synthesized by using amine-functionalized silane monomer in the presence of β-cyclodextrin (β-CD), resulting in metal/polymer core/shell nanostructures. This nanocomposite material showed a synergistic stabilizing effect when compared to either silicate sol-gel matrix or β-CD alone as stabilizer. The synthesized gold nanoparticles were characterized using UV–vis spectroscopy and high-resolution transmission electron microscopy. Modified electrodes were prepared by using the gold nanoparticles embedded in silicate sol-gel matrix, and their electrochemical characteristics were studied.

Sensitivity Enhancement in the Colorimetric/Spectroscopic Determination of Lysozyme Concentration in Nanomolar Level with Colloidal Citrate Capped Au@Ag Core-Shell Nanoparticles

2020 ◽  
Vol 10 ◽  
Author(s):  
Tapanendu Kamilya ◽  
Amit Kumar Bhunia ◽  
Pijus K. Samanta ◽  
Satyajit Saha ◽  
Rudra N. Mondal ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Silver Nanoparticles ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Gold And Silver Nanoparticles ◽  
Gold Silver ◽  
Lysozyme Concentration ◽  
Core Shell Nanoparticles ◽  
Silver Core ◽  
Higher Sensitivity

Background: Lysozyme level in body fluids is a significant indicator of various diseases. Cheap and simple colorimetric detection of lysozyme, in biological sample, by gold and silver nanoparticles is a field of interest of nanoparticle research for more than a decade Objective: We report here an attempt to improve the sensitivity part of the colorimetric lysozyme detection process by using citrate capped gold-silver core-shell nanoparticles without any functionalization Methods: Performance of gold-silver core-shell nanoparticles in determining of lysozyme concentration in water has been done using colorimetric/spectroscopic technique. Studies have also been done with gold nanoparticles, silver nanoparticles and mixed colloidal suspension of gold and silver nanoparticles, for comparison. Selectivity study has been done through spectroscopic analysis, red-green-blue colour component analysis and fractal dimension analysis of the nanoparticles interacted with several low and high isoelectric proteins Results: Gold-silver core-shell nanoparticles showed higher sensitivity for a wider range of lysozyme concentration compared to gold and silver nanoparticles prepared by us or reported in literatures. Gold nanoparticles showed higher sensitivity compared to the core-shell nanoparticles, but for a narrow concentration range of lysozyme. For silver nanoparticles and the mixed nanoparticle system, both sensitivity and range of determination of lysozyme concentration were much smaller compared to the core-shell nanoparticles. Core-shell nanoparticles showed better selectivity compared to gold nanoparticles in identifying aquatic solution of lysozyme from that of other proteins Conclusion: Gold-silver core-shell nanoparticles have higher sensitivity in determining wide range of lysozyme concentration in water compared to gold and silver nanoparticles reported in literatures

Development of Gold Nanoparticle Radiotracers for Investigating Multiphase System in Process Industries

2012 ◽  
Vol 545 ◽  
pp. 105-110 ◽  
Author(s):  
Mohd Amirul Syafiq Mohd Yunos ◽  
Siti Aslina Hussain ◽  
Jaafar Abdullah ◽  
Engku Mohd Fahmi Engku Chik ◽  
Noraishah Othman ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Nuclear Reactor ◽  
Gamma Ray ◽  
Sol Gel ◽  
Target Material ◽  
Multiphase System ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Process Industries ◽  
Citrate Reduction

This paper describes the development of colloidal Au-SiO2 with core-shell structure nanoparticle radioactive tracers by neutron activation in nuclear reactor that produce Au-198 (T1/2=2.7 d) emitting gamma ray of 412 keV. Using conventional citrate-reduction method, gold nanoparticles were prepared from its corresponding metal salts in aqueous solution then coated with uniform shells of amorphous silica via a sol-gel reaction. The citrate-reduction-based method provides gold nanoparticles with higher concentration and narrow size distribution. By using transmission electron microscopy (TEM), the resultant of particle size and silica coatings could be varied from tens to several hundred of nanometers by controlling the catalyzer and precipitation time. Au-SiO2 core-shell nanostructure is good to prevent the particles from getting agglomerated resulting in a big mass. In addition, silica surface offer very good chances that make the hydrophobic and hydrophilic behavior on the gold nanoparticles. EDXRF spectrum has proven that Au-SiO2 core-shell nanoparticles sample consists purely of a gold and silica particles. This target material of radiotracer application used to investigate multiphase system in process industries without disturbing the system operation.

Optical properties of core-shell gold-silver and silver-gold nanoparticles for some laser wavelengths

2008 ◽  
Author(s):  
Victor K. Pustovalov ◽  
Karsten König ◽  
Liudmila G. Astafyeva ◽  
Wolfgang Fritzsche
Keyword(s):  
Gold Nanoparticles ◽  
Optical Properties ◽  
Core Shell ◽  
Gold Silver

Synthesis of Core@Shell Composites with Gold Nanoparticles Trapped inside Ceramic Silica Shells by the Sol-Gel Method

2008 ◽  
Vol 368-372 ◽  
pp. 797-799 ◽  
Author(s):  
Chien Jung Huang ◽  
Pin Hsiang Chiu ◽  
Yeong Her Wang
Keyword(s):  
Gold Nanoparticles ◽  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Amorphous Silica ◽  
Plasmon Resonance ◽  
Sol Gel ◽  
Silica Shell ◽  
Core Shell ◽  
Gold Core ◽  
Spherical Gold Nanoparticles

This paper describes a sol-gel (SG) method for the coating of gold nanoparticles with uniform shells of amorphous silica. The thickness of silica could be conveniently controlled in the range of 10 to 120 nm by increasing the amount of water. Although spherical gold nanoparticles generally have a surface plasmon resonance (SPR) at a wavelength of about 520 nm, a spherical gold core with a silica shell offers a very highly tunable SPR wavelength depending on the thickness of the silica shell.

Core–shell gold/silver nanoparticles: Synthesis and optical properties

2013 ◽  
Vol 392 ◽  
pp. 90-95 ◽  
Author(s):  
Lu Lu ◽  
Gwendolyn Burkey ◽  
Ionel Halaciuga ◽  
Dan V. Goia
Keyword(s):  
Silver Nanoparticles ◽  
Optical Properties ◽  
Core Shell ◽  
Gold Silver ◽  
Nanoparticles Synthesis

scholarly journals Core-Shell Au@Ag Nanoparticles Synthesized with Polyphenols as Antimicrobial Agents

2021 ◽  
Author(s):  
Jesús Mauro Adolfo Villalobos-Noriega ◽  
Ericka Rodríguez Leon ◽  
César Rodríguez-Beas ◽  
Eduardo Larios-Rodríguez ◽  
Maribel Plascencia-Jatomea ◽  
...  
Keyword(s):  
Growth Kinetic ◽  
Antimicrobial Agents ◽  
Bimetallic Nanoparticles ◽  
Kinetic Curve ◽  
Core Shell ◽  
Root Extract ◽  
X Ray ◽  
Transmission Electron ◽  
Gold Silver ◽  
Vis Spectroscopy

Abstract In this work, we used a sequential method of synthesis for gold-silver bimetallic nanoparticles with core@shell structure (Au@AgNPs). Rumex hymenosepalus root extract (Rh), which presents high content in catechins and stilbenes, was used as reductor agent in nanoparticles synthesis. Size distribution obtained by Transmission Electron Microscopy (TEM) give a diameter mean of 36 nm for Au@AgNPs, and 24 nm for gold nanoparticles (AuNPs). The geometrical shapes of NPs were principally quasi-spherical. The thickness of silver shell over AuNPs are around 6 nm and covered by active biomolecules onto surface. Microstructural characterization included high angle annular dark field images (HAADF) recorded with a scanning transmission electron microscope (STEM), Energy-Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD), UV-Vis Spectroscopy, and Zeta Potential. Also, a growth kinetic curve analysis using the Gompertz model for Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Candida albicans (yeast) were carried out for Au@AgNPs and monometallic AuNPs and AgNPs. Interestingly, Gompertz analysis indicates that Au@AgNPs present a higher effect on the growth kinetic of microorganisms than shown by monometallic nanoparticles.

Influence of Oxygen on the Optical Properties of Silver Nanoparticles

2008 ◽  
Vol 8 (12) ◽  
pp. 6545-6550 ◽  
Author(s):  
V. M. Rentería-Tapia ◽  
J. García-Macedo
Keyword(s):  
Silver Nanoparticles ◽  
Optical Properties ◽  
Metallic Nanoparticles ◽  
Silver Oxide ◽  
Sol Gel ◽  
Oxygen Atmosphere ◽  
Oxide Shell ◽  
Metallic Surface ◽  
Oxidizing Atmosphere ◽  
Vis Spectroscopy

Silver nanoparticles in sol–gel silica films were obtained by annealing in hydrogen atmosphere and subsequently in oxygen atmosphere. Their properties were measured by UV-vis spectroscopy, transmission electron microscopy (TEM), high-resolution transmission electronic microscopy (HRTEM) and X-ray diffraction analysis. Samples prepared in a reducing atmosphere exhibited a surface plasmon resonance (SPR) located at 399 nm. Silver nanoparticles in an oxidizing atmosphere exhibited a red shift and damping of the SPR. These optical properties were explained due to the oxidation on the surface of silver nanoparticles to silver oxide yield in an oxygen atmosphere. Silver core–silver oxide shell nanostructures were observed by HRTEM. The average size of the metallic nanoparticles obtained by TEM was used for modeling the UV-vis spectra by using the Gans theory. Good fits to the spectra under an oxidizing atmosphere were obtained considering variable refractive indexes coming from the silver oxide shells surrounding to the nanoparticles. Therefore, the interaction between oxygen and the metallic surface of the nanoparticles, sensitively alters their optical properties.

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