scholarly journals Laser-Based Synthesis of Au Nanoparticles for Optical Sensing of Glyphosate: A Preliminary Study

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 989 ◽  
Author(s):  
Antonella Laura Sortino ◽  
Maria Censabella ◽  
Gabriella Munzi ◽  
Simona Boninelli ◽  
Vittorio Privitera ◽  
...  
Keyword(s):  
Optical Properties ◽  
Au Nanoparticles ◽  
Synthesis Methods ◽  
Colloidal Solutions ◽  
Nanosecond Pulsed Laser ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Fine Control ◽  
The Stability ◽  
Simple Economic

Nowadays, Au nanoparticles (AuNPs) capture great interest due to their chemical stability, optical properties, and biocompatibility. The success of technologies based on the use of AuNPs implies the development of simple synthesis methods allowing, also, the fine control over their properties (shape, sizes, structure). Here, we present the AuNPs fabrication by nanosecond pulsed laser ablation in citrate-solution, that has the advantage of being a simple, economic and eco-sustainable method to fabricate colloidal solutions of NPs. We characterized the stability and the absorbance of the solutions by Ultraviolet-Visible (UV-Vis) spectroscopy and the morphology of the AuNPs by Transmission Electron Microscopy. In addition, we used the AuNPs solutions as colorimetric sensor to detect the amount of glyphosate in liquid. Indeed, glyphosate is one of the most widely used herbicides which intensive use represents a risk to human health. The glyphosate presence in the colloidal AuNPs solutions determines the aggregation of the AuNPs causing the change in the color of the solution. The variation of the optical properties of the colloidal solutions versus the concentration of glyphosate is studied.

scholarly journals Catalytic performance of Ag, Au and Ag-Au nanoparticles synthesized by lichen extract

2018 ◽  
Vol 7 (5) ◽  
pp. 433-440 ◽  
Author(s):  
Zafer Çıplak ◽  
Ceren Gökalp ◽  
Bengü Getiren ◽  
Atila Yıldız ◽  
Nuray Yıldız
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fourier Transform ◽  
Catalytic Activity ◽  
Au Nanoparticles ◽  
Bimetallic Nanoparticles ◽  
Catalytic Performance ◽  
Catalytic Activities ◽  
Transmission Electron ◽  
Vis Spectroscopy

Abstract In the present study, the green chemistry approach for the biosynthesis of Ag, Au and Ag-Au bimetallic nanoparticles (NPs) was applied using lichen extract [Cetraria islandica (L.) Ach.]. The lichen extract acts both as a reducing and stabilizing agent. The monometallic and bimetallic NPs were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The results showed that NPs were successfully synthesized and the prepared structures were generally spherical. The synthesized nanostructures exhibited excellent catalytic activities towards reduction of nitrophenols (4-nitrophenol; 4-NP) to aminophenols (4-aminophenol; 4-AP) with sodium borohydride (NaBH4). It was determined that bimetallic NPs exhibit more effective catalytic activity than monometallic Ag and Au nanostructures. This is the first report on 4-NP reduction with Ag, Au and Au-Ag NP catalysts prepared by lichen extract.

scholarly journals An Electrochemical Immunosensor Based on SPA and rGO-PEI-Ag-Nf for the Detection of Arsanilic Acid

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 172
Author(s):  
Yanwei Wang ◽  
Dongdong Ma ◽  
Gaiping Zhang ◽  
Xuannian Wang ◽  
Jingming Zhou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Limit Of Detection ◽  
Electrochemical Immunosensor ◽  
Detection Range ◽  
Optimal Experiment ◽  
Arsanilic Acid ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Good Potential ◽  
The Stability

A sensitive electrochemical immunosensor was prepared for rapid detection of ASA based on arsanilic acid (ASA) monoclonal antibody with high affinity. In the preparation of nanomaterials, polyethyleneimine (PEI) improved the stability of the solution and acted as a reducing agent to generate reduced graphene oxide (rGO) with relatively strong conductivity, thereby promoting the transfer of electrons. The dual conductivity of rGO and silver nanoparticles (AgNPs) improved the sensitivity of the sensor. The synthesis of nanomaterials were confirmed by UV-Vis spectroscopy, X-ray diffraction, transmission electron microscopy and scanning electron microscopy. In the optimal experiment conditions, the sensor could achieve the detection range of 0.50–500 ng mL−1 and the limit of detection (LOD) of 0.38 ng mL−1 (S/N = 3). Moreover, the sensor exhibited excellent specificity and acceptable stability, suggesting that the proposed sensor possessed a good potential in ASA detection. Thus, the as-prepared biosensor may be a potential way for detecting other antibiotics in meat and animal-derived foods.

scholarly journals Synthesis of Silver Nanoparticles using Egg White: Dye Degradation and Antimicrobial Potential

2021 ◽  
Vol 12 (2) ◽  
pp. 2361-2372
Keyword(s):  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Dye Degradation ◽  
Egg White ◽  
Blue Dye ◽  
Second Phase ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
The Stability ◽  
And Staphylococcus Aureus

In recent years, developing nanoparticles with green processes is gaining huge attention due to its cost-effectiveness, simplicity and non–toxic precursors. The present study utilized the potential of egg white for the synthesis of stable silver nanoparticles (EW-AgNPs). In order to characterize the EW-AgNPs, various techniques have been employed. UV-vis spectroscopy (300-700nm) was used to study the λmax, which highlighted the peak at 422nm. Further, the stability of synthesized EW-AgNPs was studied using Zeta potential, the value of -16.4 mV was obtained, indicating the stability of developed EW-AgNPs in the solution. Transmission electron microscopy was used specifically to visualize the shape and size of synthesized EW-AgNPs, the images showed spherical to the diverse shape of EW-AgNPs. In the first phase, the EW-AgNPs were studied for dye degradation along with NaBH4. The enhanced dye degradation of blue dye was obtained with EW-AgNPs+NaBH4, showing 90- 100% degradation from 100- 25 mgL-1 dye solution, respectively. Further, in the second phase, antimicrobial activity (Zone of Inhibition) of EW-AgNPs was analyzed against Escherichia coli and Staphylococcus aureus. A higher ZOI was obtained for E.coli (16mm) than S. aureus (12.4mm). The present study proved egg white's ability to develop stable silver nanoparticles, which was further found to be effective for blue dye degradation and antimicrobial activity.

scholarly journals Plasmonic Sensing of Aqueous-Divalent Metal Ions by Biogenic Gold Nanoparticles

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Luisa E. Silva-De Hoyos ◽  
Victor Sánchez-Mendieta ◽  
Alfredo R. Vilchis-Nestor ◽  
Miguel A. Camacho-López ◽  
Jésica Trujillo-Reyes ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Aqueous Solutions ◽  
Metal Ions ◽  
Plasmon Resonance ◽  
Chemical Interaction ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Colloidal Solutions ◽  
Transmission Electron ◽  
Vis Spectroscopy

The chemical interaction between biogenic gold nanoparticles (AuNPs) and several metal (II) ions can be regarded as a practical, twofold, colorimetric, and plasmon resonance sensing method for the recognition of some divalent metal ions in aqueous solutions. The green synthesized AuNPs, using Camellia sinensis as a reducing agent, were characterized by a surface plasmon resonance (SPR) using UV-Vis spectroscopy, infrared spectroscopy, and transmission electron microscopy. The AuNP colloidal solutions obtained have a pink-reddish color with SPRs centered between 529 and 536 nm. AuNPs with spherical, triangular, and hexagonal shapes were found by TEM analyses. Despite their divergent morphologies, these AuNPs can be employed as colorimetric and plasmon resonance sensors for detection of Ca2+, Sr2+, Cu2+, and Zn2+, primarily, in aqueous solutions. Sensibility studies based on molar concentrations were also performed for these metal ions. Furthermore, solid biogenic AuNPs/cellulosic biocomposites were prepared with the aim of developing portable, fast, and dependable colorimetric sensors; nevertheless, these biocomposites resulted to be good adsorbent materials of metal ions.

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.

Synthesis and characterization of thermosensitive and polarity-sensitive fluorescent PNIPAM-coated gold nanoparticles

e-Polymers ◽  
2017 ◽  
Vol 17 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Chunhua Luo ◽  
Meijuan Qian ◽  
Qiujing Dong
Keyword(s):  
Photoelectron Spectroscopy ◽  
Au Nanoparticles ◽  
Synthesis And Characterization ◽  
Strong Fluorescence ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Grafting Through ◽  
Polarity Sensitive

AbstractThermosensitive PNIPAM-coated Au nanoparticles (AuNPs@P(NIPAM-co-MADMAC)) were synthesized by the radical “grafting through” copolymerization of 4-methacryloyloxy-4′-dimethylaminochalcone (MADMAC), MAEL-capped AuNPs and N-isopropylacrylamide (NIPAM) using azobisisobutyronitrile (AIBN) as the initiator. AuNPs@P(NIPAM-co-MADMAC) were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), 1H nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectroscopy. AuNPs@P(NIPAM-co-MADMAC) exhibited thermo-sensitivity from poly(NIPAM-co-MADMAC) chains and sensitive fluorescence from the MADMAC group. AuNPs@P(NIPAM-co-MADMAC) showed weak fluorescence after the temperature increased from 25°C to 45°C, or after β-cyclodextrin (β-CD) was added. Furthermore, it exhibited strong fluorescence when the solvent was changed to ethanol or chloroform.

scholarly journals One pot synthesis of silver nanoparticles using a cyclodextrin containing polymer as reductant and stabilizer

2014 ◽  
Vol 5 ◽  
pp. 380-385 ◽  
Author(s):  
Arkadius Maciollek ◽  
Helmut Ritter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silver Nanoparticles ◽  
Optical Properties ◽  
Silver Nitrate ◽  
Room Temperature ◽  
One Pot ◽  
One Pot Synthesis ◽  
Transmission Electron ◽  
Vis Spectroscopy

A facile and one pot synthesis of silver nanoparticles with narrow size distributions using silver nitrate and a copolymer 1 from N-isopropylacrylamide (NIPAM) and mono-(1H-triazolylmethyl)-2-methylacryl-β-cyclodextrin acting as reductant and stabilizer without using any additional reducing agent is reported. The reduction was carried out in aqueous solution under pH neutral conditions at room temperature. The results of dynamic light scattering analysis and transmission electron microscopy show adjustable particle sizes from 30–100 nm, due to variation of silver nitrate concentration, the polymeric reducing and stabilisation agent concentration or reaction time. The spherical structure of the silver nanoparticles has been confirmed by UV–vis spectroscopy and transmission electron microscopy. The optical properties of the nanoparticles have also been characterized by fluorescence spectroscopy. The formed spherical particles are stable in aqueous medium at room temperature over a period of several weeks. Furthermore the changes in the optical properties of the nanoparticles due to thermo induced volume phase transition behavior of the thermoresponsive cyclodextrin containing polymer 1 have been characterized by UV–vis spectroscopy.

scholarly journals Optical Properties of Linoleic Acid Protected Gold Nanoparticles

2011 ◽  
Vol 2011 ◽  
pp. 1-4 ◽  
Author(s):  
Ratan Das ◽  
Siddartha S. Nath ◽  
Ramendu Bhattacharjee
Keyword(s):  
Gold Nanoparticles ◽  
Linoleic Acid ◽  
Fluorescence Spectra ◽  
Au Nanoparticles ◽  
Chemical Reduction ◽  
Colloidal Dispersion ◽  
Visible Range ◽  
Absorption Bands ◽  
Transmission Electron ◽  
Vis Spectroscopy

Linoleic acid-protected gold nanoparticles have been synthesized through the chemical reduction of tetrachloroaurate ions by ethanol in presence of sodium linoleate. The structure of these nanoparticles is investigated using transmission electron microscopy, which shows that the Au nanoparticles are spherical in shape with a narrow size distribution which ranges from 8 to 15 nm. Colloidal dispersion of gold nanoparticles in cyclohexane exhibits absorption bands in the ultraviolet-visible range due to surface plasmon resonance, with absorption maximum at 530 nm. Fluorescence spectra of gold nanoparticles also show an emission peak at 610 nm when illuminated at 450 nm. UV-Vis spectroscopy reveals that these nanoparticles remain stable for 10 days.

Nanoparticles of Pd: Synthesis by Microwave-Solvothermal Method and Optical Properties

2008 ◽  
Vol 8 (8) ◽  
pp. 3930-3935 ◽  
Author(s):  
Dongsheng Li ◽  
Sridhar Komarneni
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Pd Nanoparticles ◽  
Absorption Bands ◽  
Reaction Conditions ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Particle Size And Morphology ◽  
Particle Size And Shape ◽  
Size And Morphology

Well-dispersed Pd nanoparticles were synthesized by microwave-assisted solvothermal technique using methanol and ethanol. Particle size and morphology were controlled mainly by the reaction temperature. Particle size of Pd nanoparticles was controlled in the range of 2 to 11 nm by manipulating the reaction conditions. The Pd nanoparticles were characterized by transmission electron microscopy for particle size and shape and UV-Vis spectroscopy for optical properties. UV-Vis spectra showed that synthesized Pd nanoparticles stabilized with PVP had absorption bands at around 280 to 290 nm.

Synthesis of Fe2+ Ion Doped ZnS Nanoparticles

2014 ◽  
Vol 879 ◽  
pp. 155-163 ◽  
Author(s):  
Rahizana Mohd Ibrahim ◽  
Markom Masturah ◽  
Huda Abdullah
Keyword(s):  
Electron Microscopy ◽  
Optical Properties ◽  
Quantum Confinement Effect ◽  
Band Gap Energy ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Co Precipitation

Nanoparticles of Zn1-xFexS ( x=0.0,0.1,0.2 and 0.3) were prepared by chemical co-precipitation method from homogenous solution of zinc and ferum salt at room temperature with controlled parameter. These nanoparticles were sterically stabilized using Sodium Hexamethaphospate (SHMP). Here, a study of the effect of Fe doping on structure, morphological and optical properties of nanoparticles was undertaken. Elemental analysis, morphological and optical properties have been investigated by Fourier-Transform-Infrared spectroscopy (FT-IR), X-Ray Fluorescence (XRF), Field Emmision Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and UV-Visible Spectroscopy. FTIR measurement confirmed the presence of SHMP in the nanoparticles structure with the FESEM images depicting considerable less agglomeration of particles with the presence of SHMP. While XRF results confirm the presence of Fe2+ ion as prepared in the experiment. The particles sizes of the nanoparticles lay in the range of 2-10 nm obtained from the TEM image were in agreement with the XRD results. The absorption edge shifted to lower wavelengths with an increase in Fe concentration shown in the UV-Vis spectroscopy. The band gap energy value was in the range of 4.95 5.15 eV. The blueshift is attributed to the quantum confinement effect.

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