Unstable Reshaping of Gold Nanorods Prepared by a Wet Chemical Method in the Presence of Silver Nitrate

2006 ◽  
Vol 6 (11) ◽  
pp. 3355-3359 ◽  
Author(s):  
Muhammad Iqbal ◽  
Giyoong Tae
Keyword(s):  
Silver Nitrate ◽  
Gold Nanorods ◽  
Small Diameter ◽  
Silver Ions ◽  
Blue Shift ◽  
Aqueous Environment ◽  
Ctab Concentration ◽  
Seed Particles ◽  
The Stability ◽  
Growth Approach

We characterized the stability of the gold nanorods synthesized by means of a seed mediated growth approach in the presence of AgNO3, which consists of synthesis of small diameter seed particles (∼4 nm) and subsequent growth of these nanoparticles into nanorods by addition to gold salt solution containing cetyltrimethylammonium bromide (CTAB) in the presence of ascorbic acid. The presence of silver nitrate significantly enhanced the nanorod synthesis as previously reported. However, the synthesized nanorods were unstable and reshaped in aqueous environment; the continuous blue-shift of the 2nd plasmon bands was monitored and the changes in the nanorod morphologies were also observed by electron microscopy with increasing storage time. This reshaping was observed at wide CTAB concentration range regardless of the removal of the unreacted gold or silver ions.

Preparation of Au@Ag Core-Shell Nanorods and Investigation of its Surface Plasmon

2012 ◽  
Vol 535-537 ◽  
pp. 446-449
Author(s):  
Wei Yuan ◽  
Pei Jie Wang ◽  
Yan Fang
Keyword(s):  
Aspect Ratio ◽  
Surface Plasmon ◽  
Gold Nanorods ◽  
Chemical Reduction ◽  
Silver Ions ◽  
Blue Shift ◽  
Core Shell ◽  
Transverse Modes ◽  
Growth Method ◽  
Length Width

Different aspect ratio (length/width) gold nanorods were prepared in aqueous solution by seeding growth method. Aspect ratio of the nanorods was controlled accurately by changing the silver ions concentration. Ultraviolet-visible (UV-vis) spectra demonstrate the regularation that longitudinal plasmon resonance absorption wavelength of gold nanorods reveal red shift with the increase of aspect ratio. Gold nanorods were wrapped with Ag shells by chemical reduction silver ions on its surface. Different from gold nanorods, the transverse modes of the Au@Ag core-shell nanorods have two bands which contributed from the Ag and Au, respectively. On the other hand, centers of longitudinal surface plasmon of the core-shell nanorods exhibit blue shift with the Ag shell thickness increasing.

Removal of Cetyltrimethylammonium Bromide to Enhance the Biocompatibility of Au Nanorods Synthesized by a Modified Seed Mediated Growth Process

2008 ◽  
Vol 8 (9) ◽  
pp. 4670-4674 ◽  
Author(s):  
Byung-Sang Choi ◽  
Muhammad Iqbal ◽  
Takhee Lee ◽  
Young Ha Kim ◽  
Giyoong Tae
Keyword(s):  
Gold Nanorods ◽  
Cetyltrimethylammonium Bromide ◽  
Growth Process ◽  
Complete Removal ◽  
Au Nanorods ◽  
Nir Absorption ◽  
Seed Mediated ◽  
The Stability ◽  
Growth Approach

Previously, we reported the synthesis of stable gold nanorods with higher aspect ratio (∼15–20) and more enhanced uniformity by a modified seed mediated growth approach using a binary surfactant system consisting of CTAB and Pluronic F-127. For the in vivo application of gold nanorods, the removal of CTABs that are strongly bound on prepared Au nanorods is necessary due to their cytotoxicity. Use of heat or acid at various conditions was performed to achieve the complete removal of CTAB from the synthesized Au nanorods while maintaining their stability. Here, we report the appropriate conditions for both treatments that can remove CTAB efficiently without hampering the stability of Au nanorods. After the removal of CTAB, Pluronic F-127 was added additionally for the stabilization and further potential functionalization of Au nanorods to make useful for various applications. VIS-NIR absorption spectroscopy, SEM, TEM, and FTIR were used for characterization.

scholarly journals Complexes of Copper and Iron with Pyridoxamine, Ascorbic Acid, and a Model Amadori Compound: Exploring Pyridoxamine’s Secondary Antioxidant Activity

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 208
Author(s):  
Guillermo García-Díez ◽  
Roger Monreal-Corona ◽  
Nelaine Mora-Diez
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Rate Constant ◽  
Stable Complex ◽  
Aqueous Environment ◽  
Oh Radicals ◽  
Bidentate Ligands ◽  
Superoxide Radical Anion ◽  
Amadori Compound ◽  
The Stability

The thermodynamic stability of 11 complexes of Cu(II) and 26 complexes of Fe(III) is studied, comprising the ligands pyridoxamine (PM), ascorbic acid (ASC), and a model Amadori compound (AMD). In addition, the secondary antioxidant activity of PM is analyzed when chelating both Cu(II) and Fe(III), relative to the rate constant of the first step of the Haber-Weiss cycle, in the presence of the superoxide radical anion (O2•−) or ascorbate (ASC−). Calculations are performed at the M05(SMD)/6-311+G(d,p) level of theory. The aqueous environment is modeled by making use of the SMD solvation method in all calculations. This level of theory accurately reproduces the experimental data available. When put in perspective with the stability of various complexes of aminoguanidine (AG) (which we have previously studied), the following stability trends can be found for the Cu(II) and Fe(III) complexes, respectively: ASC < AG < AMD < PM and AG < ASC < AMD < PM. The most stable complex of Cu(II) with PM (with two bidentate ligands) presents a ΔGf0 value of −35.8 kcal/mol, whereas the Fe(III) complex with the highest stability (with three bidentate ligands) possesses a ΔGf0 of −58.9 kcal/mol. These complexes can significantly reduce the rate constant of the first step of the Haber-Weiss cycle with both O2•− and ASC−. In the case of the copper-containing reaction, the rates are reduced up to 9.70 × 103 and 4.09 × 1013 times, respectively. With iron, the rates become 1.78 × 103 and 4.45 × 1015 times smaller, respectively. Thus, PM presents significant secondary antioxidant activity since it is able to inhibit the production of ·OH radicals. This work concludes a series of studies on secondary antioxidant activity and allows potentially new glycation inhibitors to be investigated and compared relative to both PM and AG.

scholarly journals Effective replacement of cetyltrimethylammonium bromide (CTAB) by mercaptoalkanoic acids on gold nanorod (AuNR) surfaces in aqueous solutions

Nanoscale ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 658-668 ◽  
Author(s):  
Rafael del Caño ◽  
Jose M. Gisbert-González ◽  
Jose González-Rodríguez ◽  
Guadalupe Sánchez-Obrero ◽  
Rafael Madueño ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Gold Nanorods ◽  
Ligand Exchange ◽  
Cetyltrimethylammonium Bromide ◽  
Gold Nanorod ◽  
Experimental Conditions ◽  
Seed Mediated ◽  
The Stability

The highly packed cetyltrimethylammonium bromide bilayer on the surface of gold nanorods synthesized by the seed-mediated procedure hampers the complete ligand exchange under experimental conditions that preserves the stability of the dispersions.

Technology and Effectiveness of Cast Iron Treatment by Gas Injection

2010 ◽  
Vol 457 ◽  
pp. 459-464
Author(s):  
Edis B. Ten
Keyword(s):  
Cast Iron ◽  
Gas Injection ◽  
Small Diameter ◽  
Multiple Use ◽  
Positive Effects ◽  
Injection Treatment ◽  
The Stability ◽  
Injection Technology ◽  
Stability Regime ◽  
Structure Stabilization

In this work the development of the technology and equipment for gas injection treatment of cast iron by inert gas (nitrogen) is presented. The equipment includes the plunging lance as a lined steel pipe with nozzles. The nozzles are thin channels, which are lined by ceramic tubes with small-diameter. The lance has a multiple use, as it has calibrated channel sizes, and provide the stability regime of gas injection treatment. The characteristic of the gas injection technology consists of blowing of melt by gas, which is injected into the liquid cast iron through thin jet with a speed near to the velocity of sound. In this case, the dispersion of gas jets in small-sized bubbles is reached, therefore the refining effectiveness increases. The gas injection treatment shows the promotion of casting properties, improvement of homogeneity and fineness of structure, stabilization or increasing of mechanical properties, decreasing of casting defectiveness. The positive effects of the gas injection treatment is the result of complex action of the injecting gas into the cast iron melt. Together with refining and homogenizing action at specified conditions, it offers the modifying and alloying effects also.

Improving the stability of chondroitinase ABC I via interaction with gold nanorods

2018 ◽  
Vol 107 ◽  
pp. 297-304 ◽  
Author(s):  
Mina Sadat Naderi ◽  
Tahereh Tohidi Moghadam ◽  
Khosro Khajeh ◽  
Bijan Ranjbar
Keyword(s):  
Gold Nanorods ◽  
Chondroitinase Abc ◽  
The Stability

scholarly journals Gel Formation in Low Concentrated Solutions of Glycyram and Amino Acids in the Presence of Silver Nitrate

2021 ◽  
Vol 7 (11) ◽  
pp. 11-21
Keyword(s):  
Amino Acids ◽  
Silver Nitrate ◽  
Food Industry ◽  
Silver Ions ◽  
Electrolyte Solutions ◽  
Low Molecular Weight ◽  
Gel Formation ◽  
Recent Past ◽  
Concentrated Solutions ◽  
Low Concentrations

Abstract. Research relevance: low molecular weight supramolecular hydrogels are unique objects that can solve many pressing problems in medicine, food industry and other sectors of the national economy. Research objectives: in recent past, it was discovered that low-concentration solutions of L-cysteine and silver nitrate (CSN) can form, when electrolyte solutions are added to hydrogels. We were faced with the task of obtaining hydrogels from dilute solutions of glycyram (GC) by adding CSN, since GC, due to its poor solubility, has low bioavailability. Materials and research methods: using the method of isomolar series, a comparative study of the formation of hydrogels by dilute GC solutions with the addition of CSN and GCP was carried out. It has been found that most durable hydrogels were obtained using CSN. Thus, GC hydrogels were obtained at a concentration of 10−3 M after adding CSN and GCP, which have a supramolecular character and combine the properties of GC, amino acids, and silver ions. Research results: glycyram hydrogels were obtained at its concentration equal to 10−3 M by mixing it with silver amino acids L-cysteine (CSN) and L-glutamic acid (GCP) solutions in same low concentrations. Conclusions: hydrogels with glycyram form silver solutions of those amino acids that are capable of giving frame structures at a ratio of amino acid: silver nitrate of 1.25.

Pretreated Lignocellulosic Waste Mediated Biosynthesis of Silver Nanoparticles Under Room Temperature

2016 ◽  
Vol 15 (05n06) ◽  
pp. 1660001 ◽  
Author(s):  
V. P. Manjamadha ◽  
Karuppan Muthukumar
Keyword(s):  
Silver Nanoparticles ◽  
Silver Nitrate ◽  
Room Temperature ◽  
Nitrate Solution ◽  
Silver Ions ◽  
Silver Nitrate Solution ◽  
Morphological Characterization ◽  
Alternative Source ◽  
X Ray ◽  
Antibacterial Performance

The current work elucidates the utilization of biowaste as a valuable reducing agent for the synthesis of silver nanoparticles. In this study, the wastewater generated during the alkaline pretreatment of lignocellulosic wastes (APLW) was used as a bioreductant to reduce silver nitrate under room temperature. Synthesis of stable silver nanoparticles (AgNPs) was achieved rapidly on addition of APLW into the silver nitrate solution (1[Formula: see text]mM). The morphological characterization of AgNPs was performed using field emission scanning electron microscopy (FESEM). The micrograph clearly depicted the presence of spherical AgNPs. The presence of elemental silver along with biomoilties was determined using energy dispersive X-ray spectroscopy (EDAX) analysis. The X-ray diffraction (XRD) study proved the crystalline form of stable AgNPs. The AgNPs exhibited excellent antibacterial performance against Gram negative organism. The immediate bioreduction of silver ions using APLW was well illustrated in the present study. Thus, APLW serve as an alternative source for reducing agents instead of utilizing valuable medicinal plants for nanoparticles synthesis.

scholarly journals Two Modes of Nanoleakage Expression in Single-step Adhesives

2002 ◽  
Vol 81 (7) ◽  
pp. 472-476 ◽  
Author(s):  
F.R. Tay ◽  
D.H. Pashley ◽  
M. Yoshiyama
Keyword(s):  
Silver Nitrate ◽  
Silver Ions ◽  
Single Step ◽  
Mineral Dissolution ◽  
Resin Infiltration ◽  
Transmission Electron ◽  
Hybrid Layers ◽  
Self Etch ◽  
Ammoniacal Silver ◽  
Spotted Pattern

Self-etch adhesives that etch, prime, and bond simultaneously should not exhibit incomplete resin infiltration within hybrid layers. We hypothesized that nanoleakage patterns in these systems are artifacts caused by mineral dissolution in mildly acidic silver nitrate. Resin-dentin interfaces bonded with four single-step, self-etch adhesives were examined for nanoleakage by conventional (pH 4.2) and basic ammoniacal (pH 9.5) silver nitrate and prepared for transmission electron microscopy. All adhesives exhibited a reticular mode of nanoleakage within hybrid layers when conventional silver nitrate was used. With ammoniacal silver nitrate, an additional spotted pattern of nanoleakage was observed within adhesive and hybrid layers. The reticular mode of nanoleakage in self-etch adhesives probably represents sites of incomplete water removal that leads to regional suboptimal polymerization. The spotted pattern identified with the use of ammoniacal silver nitrate probably represents potentially permeable regions in the adhesive and hybrid layers that result from the interaction of the basic diamine silver ions with acidic/hydrophilic resin components.

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