scholarly journals Highly Sensitive and Selective Colorimetric Sensor of Mercury (II) Based on Layer–by–Layer Deposition of Gold/Silver Bimetallic Nanoparticles

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4443
Author(s):  
Arjnarong Mathaweesansurn ◽  
Naratip Vittayakorn ◽  
Ekarat Detsri
Keyword(s):  
Bimetallic Nanoparticles ◽  
Limit Of Detection ◽  
Chemical Reduction ◽  
Colorimetric Sensor ◽  
Layer By Layer ◽  
Linear Relationships ◽  
Layer Deposition ◽  
Gold Silver ◽  
Ft Ir ◽  
Uv Visible

A new colorimetric sensor based on gold/silver bimetallic nanoparticles (Au–Ag BNPs) for the sensitive and selective detection of mercury (II) was developed. Gold nanoparticles (AuNPs) were synthesized by Turkevich method. The surface modification of AuNPs was modified by the layer–by–layer technique using poly(diallyl dimethylammonium chloride) which provided positively charged of AuNPs. Negatively charged silver nanoparticles (AgNPs) were synthesized by chemical reduction using poly(4–styrenesulfonic acid–co–maleic acid) as the stabilizing agent. The layer–by–layer assembly deposition technique was used to prepare Au–Ag BNPs of positively and negatively charged of AuNPs and AgNPs, respectively. The synthesized Au–Ag BNPs were characterized by a UV-visible spectrophotometer, zeta potential analyzer, FT–IR, TEM, XRD, and EDX. The Au–Ag BNPs sensor was able to detect mercury (II) in aqueous solution, visibly changing from brownish–orange to purple. The linear relationships of the UV-visible spectrometry demonstrate that the Au–Ag BNPs-based colorimetric sensor can be used for the quantitative analysis of mercury (II) in the range of 0.5–80 mg L−1, with the correlation coefficient, r2 = 0.9818. The limit of detection (LOD) of mercury (II) was found to be 0.526 + 0.001 mg L−1. The BNPs is also verified to have a good practical applicability for mercury (II) detection in the real samples.

Tunable Silver Leaching from Polyelectrolyte Multilayers Thin Films

2013 ◽  
Vol 701 ◽  
pp. 145-149 ◽  
Author(s):  
Sirorat Wacharanad ◽  
Stephan Thierry Dubas
Keyword(s):  
Silver Nanoparticles ◽  
Suture Material ◽  
Chemical Reduction ◽  
Layer By Layer ◽  
Capping Agent ◽  
Bacterial Reduction ◽  
Bacterial Colony ◽  
Surgical Suture ◽  
Layer Deposition ◽  
Vis Spectroscopy

Silver nanoparticles were deposited on glass slides and surgical suture as antibacterial agent. The silver nanoparticles were prepared by chemical reduction with sodium borohydride and using a synthetic polyelectrolyte as capping agent. Poly (4-styrenesulfonic acid-co-maleic acid) sodium salt PSSMA was used to stabilize the silver nanoparticles and provide an anionic surface charge which then allowed the layer-by-layer deposition method with poly (dially dimethyl ammonium chloride) PDADMAC. Various concentration of capping agent were used to prepare the silver nanoparticles which were then deposited on glass slide and surgical suture. The layer-by-layer deposition of the nanoparticles was studied using UV-Vis spectroscopy by monitoring the intensity of the characteristic Plasmon band of the nanoparticles at 400nm. The leaching of the silver nanoparticles in buffered solutions of pH 3,7 and 9 was monitored by recording the decrease in absorbance of silver nanoparticles film as a function of time for each pH solutions and each capping concentrations. Finally, suture material coated with silver nanoparticles were tested for their antibacterial activity against Staphylococcus aureus and results showed that all coated sutures had more than 99% bacterial reduction. So these suture material could be applied to use in medical products for promoted wound healing and decreased bacterial colony leading to relieve inflammation of patient.

scholarly journals Novel Highly Sensitive Protein Sensors Based on Tapered Optical Fibres Modified with Au-Based Nanocoatings

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Aitor Urrutia ◽  
Kartheka Bojan ◽  
Leonel Marques ◽  
Kevin Mullaney ◽  
Javier Goicoechea ◽  
...  
Keyword(s):  
Binding Constant ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Optical Fibres ◽  
Layer By Layer ◽  
Measured Concentration ◽  
Au Nps ◽  
Layer Deposition ◽  
Highly Sensitive ◽  
Protein Sensors

Novel protein sensors based on tapered optical fibres modified with Au coatings deposited using two different procedures are proposed. Au-based coatings are deposited onto a nonadiabatic tapered optical fibre using (i) a novel facile method composed of layer-by-layer deposition consisting of polycation (poly(allylamine hydrochloride), PAH) and negatively charged SiO2nanoparticles (NPs) followed by the deposition of the charged Au NPs and (ii) the sputtering technique. The Au NPs and Au thin film surfaces are then modified with biotin in order to bind streptavidin (SV) molecules and detect them. The sensing principle is based on the sensitivity of the transmission spectrum of the device to changes in the refractive index of the coatings induced by the SV binding to the biotin. Both sensors showed high sensitivity to SV, with the lowest measured concentration levels below 2.5 nM. The calculated binding constant for the biotin-SV pair was2.2×10-11 M−1when a tapered fibre modified with the LbL method was used, with a limit of detection (LoD) of 271 pM. The sensor formed using sputtering had a binding constant of1.01×10-10 M−1with a LoD of 806 pM. These new structures and their simple fabrication technique could be used to develop other biosensors.

Microwave-Hydrothermal Synthesis and Characterization of Graphene

2012 ◽  
Vol 602-604 ◽  
pp. 917-920 ◽  
Author(s):  
Zhen Hui Xiao ◽  
Shui Sheng Wu ◽  
Yan Lin Sun ◽  
Yu Lin Zhao ◽  
Ya Ming Wang
Keyword(s):  
Chemical Reduction ◽  
Visible Spectrum ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Hydrothermal ◽  
Ft Ir ◽  
Uv Visible ◽  
Scanning Electron

Graphene was synthesized by microwave-hydrothermal chemical reduction of graphite oxide using hydrazine hydrate as the reducing agent. Graphene was characterized using X-ray diffraction, UV-visible spectrum, FT-IR spectrum and scanning electron microscopy. Results indicated that the as-prepared graphene was wrinkled and comprised fewer graphenes with a highly crystalline structure.

Fabrication of Electrochemical Ceramic Membrane with Assistance of Metallization by the Electroless-plating Technique

2002 ◽  
Vol 752 ◽  
Author(s):  
Y-Y. Liu ◽  
L. Hong ◽  
Z-C. Shao ◽  
H-X. Jiang
Keyword(s):  
Structural Integrity ◽  
Ceramic Membrane ◽  
Chemical Reduction ◽  
Dip Coating ◽  
Alloy Film ◽  
Layer By Layer ◽  
Plating Bath ◽  
Layer Deposition ◽  
Pd Alloy ◽  
Membrane Processing

ABSTRACTThis work developed a metal-reinforced ceramic membrane processing approach [by using perovskite La0.2Sr0.8 CoO3-x (LSCO-80) as the model membrane] with the aim of overcoming the membrane-cracking problem. A thin layer of Ag/Pd alloy was incorporated into the LSCO-80 membrane made by dip coating and sintering. It is not viable to obtain a Pd/Ag alloy film using the co-plating method because Ag+ ion strongly inhibits chemical reduction of Pd2+ ion, and the alkaline plating bath causes severe etching of LSCO-80. This obstacle was circumvented through a layer-by-layer deposition procedure, in which Ag and Pd layers were deposited subsequently onto LSCO membrane. The Ag and Pd layers undergo alloying when the laminar structure was subjected to calcinations at 1000°C. It was found that the Pd/Ag alloy drifts beneath into pores in the LSCO layer. The resultant metal-ceramic composite membrane shows excellent structural integrity and free of micro-cracks.

scholarly journals CuAg and AuAg bimetallic nanoparticles for catalytic and heat transfer applications

2021 ◽  
Author(s):  
Anusha Dsouza ◽  
M. P. Shilpa ◽  
S. C. Gurumurthy ◽  
B. S. Nagaraja ◽  
Shridhar Mundinamani ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Rate Constant ◽  
Bimetallic Nanoparticles ◽  
Synergistic Effects ◽  
Chemical Reduction ◽  
Photocatalytic Property ◽  
Optical Absorbance ◽  
Optimum Ph ◽  
Uv Visible ◽  
Significant Attention

AbstractBimetallic nanoparticles (BNPs) have drawn significant attention due to their numerous applications. They demonstrate enhanced optical, electrical, thermal, and catalytic properties due to the synergistic effects of monometals present in them. In this work, CuAg and AuAg BNPs have been synthesized using a facile and economical chemical reduction method. Optical characterization was carried out using UV–visible spectroscopy, and effect of pH on optical absorbance was studied. For CuAg and AuAg BNPs, optimum pH was observed to be at 9.4 and 6.39, respectively. Morphological investigation confirms the average diameters of CuAg and AuAg BNPs were to be 65 nm and 30 nm, respectively. Photocatalytic property illustrates the reduction of 4-nitrophenol to 4-aminophenol with a 92% conversion percentage in the presence of CuAg BNPs in 4 min, and rate constant for the reaction was measured to be 8.98 × 10–3 s−1. But for the AuAg BNPs, the conversion percentage was 97% in 8 min and rate constant was found to be 7.95 × 10–3 s−1. Thermal conductivity and viscosity measurements of the nanofluids obtained with CuAg and AuAg BNPs have ascertained them to be efficient candidates for the heat transfer and catalytic applications. Graphic abstract

AuCu, AgCu and AuAg Bimetallic Nanoparticles: Synthesis, Characterization and Water Remediation

MRS Advances ◽  
2016 ◽  
Vol 1 (36) ◽  
pp. 2525-2530
Author(s):  
Judith Tanori ◽  
Diana Vargas-Hernández ◽  
Elisa Martínez-Barbosa ◽  
Raúl Borja-Urby ◽  
Arturo García-Bórquez ◽  
...  
Keyword(s):  
Composite Material ◽  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Water Remediation ◽  
Natural Systems ◽  
Self Assembling ◽  
Transmission Electron ◽  
Gold Silver ◽  
Vis Spectroscopy

ABSTRACTSelf-assembling systems of amphiphilic molecules display structures similar to those of biomineralization natural systems. This allows to somehow mimic nature to synthesize nanomaterials with low polidispersity and with diverse morphologies. In this work we describe the synthesis and characterization of gold-copper, silver-copper, and gold-silver bimetallic nanoparticles by chemical reduction in self-assembling systems of two surfactants. The nanoparticles were characterized by Transmission Electron Microscopy and UV-Vis spectroscopy. We have prepared a composite material using mesoporous silica as support of the AuAg bimetallic nanoparticles. The system was used in photocatalysis experiments for water remediation applications. Our results show that the AuAg/SBA15 composite material degrades methyl orange in water from 17 ppm to 4 ppm in 30 minutes.

scholarly journals Effect of methyl substituent on the solubility of 1,4-benzoquinone derivatives in n-octanol/water system

2020 ◽  
Vol 23 (5) ◽  
pp. 142-146
Author(s):  
Siti Mariyah Ulfa ◽  
Fath Dwisari ◽  
Ade Cintyia Sally ◽  
Mohammad Farid Rahman
Keyword(s):  
Shake Flask ◽  
Water System ◽  
Insertion Reaction ◽  
Log P ◽  
Methyl Substituent ◽  
Promising Candidate ◽  
New Drug ◽  
Alkyl Bromides ◽  
Ft Ir ◽  
Uv Visible

The solubility of the compound is a crucial task for new drug design. Quinone is a promising candidate to develop as a new drug. In this research, the synthesis of 1,4-benzoquinone derivatives, that is, 2-(5-bromoamyl)-3,5-dimethyl-1,4-benzoquinone (2a) and 2-(5-bromoamyl)-5-methyl-1,4-benzoquinone (2b) were carried out by decarboxylation and insertion reaction of alkyl bromides. The product 2a and 2b are purified using SiO2 gel column chromatography and analyzed by UV-Visible, FT-IR, and NMR. The yield of 2a is 13.75%, and 2b is 4.04%. The solubility of 2a and 2b, expressed by log P, is measured in the n-octanol/water (3:7 (v/v)) system by the shake flask method. The log P of 2a and 2b are 2.99 and 1.36, respectively. It is showed that the log P of 2a is higher compared to 2b. The presence of two methyl substituents on the quinone ring of 2a supports the increase of hydrophobicity of the compound in the n-octanol/water system.

scholarly journals Graphite Studded with Facile-Synthesized Cu2O Nanoparticle-Based Cubes as a Novel Electrochemical Sensor for Highly Sensitive Voltametric Determination of Mebeverine Hydrochloride

Chemosensors ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 35
Author(s):  
Ahmed H. Naggar ◽  
Ahmed Kotb ◽  
Ahmed A. Gahlan ◽  
Mahmoud H. Mahross ◽  
Abd El-Aziz Y. El-Sayed ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Lower Limit ◽  
Electrochemical Behavior ◽  
Cuprous Oxide ◽  
Density Functional ◽  
Limit Of Detection ◽  
Biological Fluids ◽  
Chemical Reduction ◽  
Anodic Stripping Voltammetry ◽  
Mebeverine Hydrochloride

Herein, a feasible chemical reduction method followed by intensive mixing was applied for the preparation of an attractive material based on graphite studded with cuprous oxide nanoparticle-based cubes (Cu2ONPs–C@G). Transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV) were utilized for characterization. Cuprous oxide nanoparticles (Cu2ONPs), with a diameter range mainly distributed from 4 to 20 nm, aggregate to form microcubes (Cu2ONPs–C) with an average diameter of about 367 nm. Paste electrode was prepared using Cu2ONPs–C@G (Cu2ONPs–C@G/PE) for voltametric quantification of the musculotropic antispasmodic drug: mebeverine hydrochloride (MEB). The electrochemical behavior of MEB was studied using CV, and the optimum analytical parameters were investigated using square wave adsorptive anodic stripping voltammetry (SWAdASV). Moreover, density functional theory (DFT) was used to emphasize the ability of MEB to form a complex with Cu2+, confirming the suggested electrochemical behavior of MEB at Cu2ONPs–C@G/PE. With good stability and high reproducibility, SWAdASV of Cu2ONPs–C@G/PE shows successful quantification of MEB over the concentration range of 5.00 × 10−11–1.10 × 10−9 M with lower limit of detection (LOD) and lower limit of quantification (LOQ) values of 2.41 × 10−11 M and 8.05 × 10−11 M, respectively. Finally, accurate quantification of MEB in dosage forms (tablets) and biological fluids (spiked human urine and plasma samples) was achieved using Cu2ONPs-C@G/PE.

scholarly journals A Novel Thiosemicarbazide-Based Fluorescent Chemosensor for Hypochlorite in Near-Perfect Aqueous Solution and Zebrafish

Chemosensors ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 65
Author(s):  
Minji Lee ◽  
Donghwan Choe ◽  
Soyoung Park ◽  
Hyeongjin Kim ◽  
Soomin Jeong ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Reactive Oxygen Species ◽  
Aqueous Solution ◽  
Fluorescence Quenching ◽  
Limit Of Detection ◽  
Fluorescent Sensor ◽  
Ionization Mass ◽  
Oxygen Species ◽  
Marked Selectivity ◽  
Uv Visible

A novel thiosemicarbazide-based fluorescent sensor (AFC) was developed. It was successfully applied to detect hypochlorite (ClO−) with fluorescence quenching in bis-tris buffer. The limit of detection of AFC for ClO− was analyzed to be 58.7 μM. Importantly, AFC could be employed as an efficient and practical fluorescent sensor for ClO− in water sample and zebrafish. Moreover, AFC showed a marked selectivity to ClO− over varied competitive analytes with reactive oxygen species. The detection process of AFC to ClO− was illustrated by UV–visible and fluorescent spectroscopy and electrospray ionization–mass spectrometry (ESI–MS).

scholarly journals Removal of hexavalent chromium from wastewater by Cu/Fe bimetallic nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jien Ye ◽  
Yi Wang ◽  
Qiao Xu ◽  
Hanxin Wu ◽  
Jianhao Tong ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Particle Surface ◽  
Zerovalent Iron ◽  
Order Model ◽  
X Ray ◽  
Nanoscale Zerovalent Iron

AbstractPassivation of nanoscale zerovalent iron hinders its efficiency in water treatment, and loading another catalytic metal has been found to improve the efficiency significantly. In this study, Cu/Fe bimetallic nanoparticles were prepared by liquid-phase chemical reduction for removal of hexavalent chromium (Cr(VI)) from wastewater. Synthesized bimetallic nanoparticles were characterized by transmission electron microscopy, Brunauer–Emmet–Teller isotherm, and X-ray diffraction. The results showed that Cu loading can significantly enhance the removal efficiency of Cr(VI) by 29.3% to 84.0%, and the optimal Cu loading rate was 3% (wt%). The removal efficiency decreased with increasing initial pH and Cr(VI) concentration. The removal of Cr(VI) was better fitted by pseudo-second-order model than pseudo-first-order model. Thermodynamic analysis revealed that the Cr(VI) removal was spontaneous and endothermic, and the increase of reaction temperature facilitated the process. X-ray photoelectron spectroscopy (XPS) analysis indicated that Cr(VI) was completely reduced to Cr(III) and precipitated on the particle surface as hydroxylated Cr(OH)3 and CrxFe1−x(OH)3 coprecipitation. Our work could be beneficial for the application of iron-based nanomaterials in remediation of wastewater.

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