scholarly journals Reducing Efficiency of Fucoxanthin in Diatom Mediated Biofabrication of Gold Nanoparticles

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4094
Author(s):  
Piya Roychoudhury ◽  
Przemysław Dąbek ◽  
Michał Gloc ◽  
Aleksandra Golubeva ◽  
Renata Dobrucka ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Gold Nanoparticles ◽  
Room Temperature ◽  
Positive Signal ◽  
Gold Nanospheres ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Sem Study ◽  
Strong Positive Signal

In the present investigation, fucoxanthin—one of the major pigments in diatoms—has been extracted from Nanofrustulum shiloi SZCZM1342, and its reducing efficiency in the biogenesis of gold nanoparticles (GNPs) was checked. Fucoxanthin extracted from golden-brown cells of N. shiloi was compared to the healthy, growing biomass of N. shiloi and standard fucoxanthin after separate exposure to 25 mg L−1 aqueous hydrogen tetrachloroaurate solutions at room temperature. Isolated and standard fucoxanthin were found to be able to reduce gold ions within 12 h whereas, the whole biomass turned pink in color after 72 h of reaction. The synthesized particles were characterized by UV-vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). UV–vis spectroscopy of purple-colored suspensions showed the absorption band at approximately 520–545 nm, indicating a strong positive signal for GNP synthesis. The SEM study revealed the deposition of GNPs on siliceous frustules of metal-treated diatom cells. The TEM analysis confirmed the GNPs synthesized by whole biomass are triangular, spherical and hexagonal in nature, whereas the particles produced by extracted and standard fucoxanthin are all spherical in nature. This study demonstrates the involvement of fucoxanthin in the reduction of gold ions and subsequent production of gold nanospheres.

scholarly journals Effects of Different Surfactant Charges on the Formation of Gold Nanoparticles by the LASiS Method

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2937
Author(s):  
Muhammad Zulfajri ◽  
Wei-Jie Huang ◽  
Genin-Gary Huang ◽  
Hui-Fen Chen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Laser System ◽  
Synthesis Process ◽  
Au Nps ◽  
Laser Fluences ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
532 Nm

The laser ablation synthesis in solution (LASiS) method has been widely utilized due to its significant prospects in laser microprocessing of nanomaterials. In this study, the LASiS method with the addition of different surfactant charges (cationic CTAB, nonionic TX-100, and anionic SDS) was used to produce Au NPs. An Nd:YAG laser system at 532 nm excitation with some synthetic parameters, including different laser fluences, ablation times, and surfactant concentrations was performed. The obtained Au NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, and zeta potential analyzer. The Au NPs exhibited the maximum absorption peak at around 520 nm for all samples. The color of Au NPs was changed from red to reddish by increasing the laser fluence. The surfactant charges also played different roles in the Au NPs’ growth during the synthesis process. The average sizes of Au NPs were found to be 8.5 nm, 5.5 nm, and 15.5 nm with the medium containing CTAB, TX-100, and SDS, respectively. Besides, the different surfactant charges induced different performances to protect Au NPs from agglomeration. Overall, the SDS and CTAB surfactants exhibited higher stability of the Au NPs compared to the Au NPs with TX-100 surfactant.

scholarly journals Biosynthesized gold nanoparticles-doped hydroxyapatite as antibacterial and antioxidant nanocomposite

2021 ◽  
Author(s):  
Is Fatimah ◽  
Putwi Widya Citradewi ◽  
Amri Yahya ◽  
Bambang Nugroho ◽  
Habibi Hidayat ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Antioxidant Activity ◽  
Particle Size ◽  
Gold Nanoparticles ◽  
Antibacterial Activity ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Dpph Scavenging Activity ◽  
Dpph Scavenging

Abstract The composite of green synthesized gold nanoparticles (Au NPs)-doped hydroxyapatite (HA) has been prepared. The gold nanoparticles were produced via bioreduction of HAuCl4 with Clitoria ternatea flower extract, and utilized in the synthesis of hydroxyapatite using Ca(OH)2 and ammonium diphosphate as precursor. The aim of this research is to study the structural analysis of the composite and antibacterial activity test toward Eschericia coli, Staphylococcus aureus, Klebsiela pneumoniae, and Streptococcus pyogenes. In addition, the antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging method. The monitoring of gold nanoparticles formation was conducted by UV–vis spectroscopy and particle size analyses, meanwhile the synthesized composite was studied using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results showed that homogeneously dispersed gold nanoparticles in HA structure was obtained with the particle size ranging at 5-80 nm. The nanocomposite demonstrated antibacterial activity against tested bacteria. The nanocomposite expressed an antioxidant activity as shown by the DPPH scavenging activity of 66 and 58% at the concentration of 100 μg/mL and 50 μg/mL, respectively.

scholarly journals Exploration of the Antimicrobial and Catalytic Properties of Gold Nanoparticles Greenly Synthesized by Cryptolepis buchanani Roem. and Schult Extract

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Kamonpan Wongyai ◽  
Phitchayapak Wintachai ◽  
Rasimate Maungchang ◽  
Parawee Rattanakit
Keyword(s):  
Staphylococcus Aureus ◽  
Gold Nanoparticles ◽  
Analytical Techniques ◽  
Average Diameter ◽  
Face Centered Cubic ◽  
Tem Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Face Centered

A green, simple, and rapid synthesis of gold nanoparticles using plant extract, Cryptolepis buchanani Roem. and Schult, and their applications are first described in this paper. The formation of gold nanoparticles was visually observed by the appearance of a ruby red color, which was further indicated by an absorption peak at 530 nm in UV-Vis spectroscopy. Optimization of reaction parameters for the gold nanoparticles was also investigated. Various analytical techniques were employed as part of the process of characterizing the resulting gold nanoparticles. Fourier transform infrared (FTIR) analysis revealed that the phenol compounds present in the extract were responsible for gold(III) reduction and stabilization of gold nanoparticles. Transmission electron microscopy (TEM) analysis showed that the gold nanoparticles were spherical in shape with an average diameter of 11 nm. Powder X-ray diffraction (XRD) pattern indicated that the green synthesis approach produced highly crystalline, face-centered cubic gold nanoparticles. Energy-dispersive X-ray spectroscopy (EDS) measurements confirmed the presence of elemental gold in the prepared nanoparticles. The negative zeta potential value of gold nanoparticles was found to be -30.28 mV. The green synthesized gold nanoparticles expressed effective antibacterial activity against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Acinetobacter baumannii and exhibited an excellent catalytic property in terms of its reduction ability of methylene blue.

Imaging of Buried Si and Si:Ge Surface Structure Under Amorphous Ge Films by Plan View Transmission Electron Microscopy

1994 ◽  
Vol 332 ◽  
Author(s):  
Olof C. Hellman
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Shift ◽  
Room Temperature ◽  
Real Space ◽  
Interfacial Structure ◽  
Tem Analysis ◽  
Plan View ◽  
Transmission Electron ◽  
Reconstructed Surface

ABSTRACTReal space plan-view Transmission Electron Microscopy (TEM) of the interfacial structure at the amorphous-Ge / Si (111) interface is presented. Ge is deposited at between room temperature and 150°C on either a 5×5 or 7×7 reconstructed surface. Conventional Plan-view TEM analysis reveals microstructural details such as surface steps, reconstruction phase shift boundaries and the reconstruction itself buried under the amorphous film, features which have previously been seen only as clean surfaces in UHV. Also imaged are small regions where Ge grows epitaxially on the Si surface above room temperature. These are seen to appear preferentially at steps and phase shift boundaries.

scholarly journals Synthesis of Gold Nanoparticles and Association of DNA-Gold Nanoparticles

2016 ◽  
Vol 11 (2) ◽  
pp. 77
Author(s):  
Weon Bae Ko ◽  
Young Min Lee ◽  
Sung Kyu Hong ◽  
Sung Sook Choi ◽  
Sang Jin Lee
Keyword(s):  
Electron Microscopy ◽  
Gold Nanoparticles ◽  
Gel Electrophoresis ◽  
Bos Taurus ◽  
Ionic Surfactant ◽  
Polysorbate 80 ◽  
Specific Primer ◽  
Binding Ability ◽  
Transmission Electron ◽  
Vis Spectroscopy

<p>This study examined the synthesis of gold nanoparticles using a non-ionic surfactant, polysorbate 80, and KAuCl<sub>4 </sub>in water. The gold nanoparticles, which were well dispersed in water, were analyzed by UV-vis spectroscopy and transmission electron microscopy (TEM). In addition, the SRY(sex-determining region Y) gene of the Bos taurus specific primer was designed, and this primer solution was mixed with the aqueous gold nanoparticles solution. The binding ability of DNA and gold nanoparticles was identified by polyacryllamide gel electrophoresis. The products of DNA linked with gold nanoparticles were also characterized by UV-vis spectroscopy and TEM.</p>

TEM analysis of core/shell latex morphology

1987 ◽  
Vol 45 ◽  
pp. 502-503
Author(s):  
O.L. Shaffer ◽  
M.S. El-Aasser ◽  
J.W. Vanderhoff
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Particle Morphology ◽  
Core Shell ◽  
Tem Analysis ◽  
Cold Stage ◽  
Transmission Electron ◽  
Complex Sample ◽  
Excellent Method

Transmission electron microscopy is an excellent method to study particle size and particle morphology of latexes. Special sample techniques are utilized in the study of latexes and often more than one technique is needed to answer questions concerning the structure of the particle. If the latex is of a core/shell type the study becomes more complex. Sample preparation for studying latexes include staining with osmium tetroxide to crosslink and stain unsaturated polymers, cold stage if the latex is too soft to examine at room temperature, negative staining to increase contrast shadowing to determine the sag of the particle at room temperature, ultramicrotoming, cryoultramicrotoming or a combination of techniques such as staining and cold stage.The latex investigated was the first stage seed latex of poly (butylacrylate - butadiene) and the final latex a core-shell of poly(butylacrylate - butadiene)/poly(methyl methacrylate). Because of its unsaturation, poly(butadiene) can be preferentially stained with osmium tetroxide.

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 The Investigation of Microwave-Assisted Greener Synthesis of Ag/Ti/Zn Trimetallic Nanoparticles and Carbon Quantum Dots Nanocomposites in the Application of Solar Cell

2021 ◽  
Vol 11 (1) ◽  
pp. 3102-3110
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Solar Cell ◽  
Carbon Quantum Dots ◽  
Copper Plate ◽  
Tem Analysis ◽  
Microwave Assisted ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Greener Synthesis

In this communication, we report a greener microwave method for synthesizing Ag/Ti/Zn trimetallic nanoparticles and carbon quantum dots nanocomposites (Ag/Ti/Zn TNPs and CQDs NCs). The morphology, topography, and size of the Ag/Ti/Zn TNPs and CQDs nanocomposites were determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The optical properties of the as-synthesized Ag/Ti/Zn TNPs and CQDs NCs were examined using UV–Vis spectroscopy and bandgap analysis. Finally, the Ag/Ti/Zn TNPs and CQDs NCs were fabricated by microwave-assisted greener synthesis, which was used as a photosensitizer, the copper plate as a counter electrode, and polysulfide as an electrolyte was assembled into the solar cell. The natural pigments extracted from the fruit of Solanum lycopersicium extract were used in Ag/Ti/Zn TNPs and CQDs NCs based solar cells. The as-fabricated solar cell's conversion efficiency was 5.47% with a Voc of 0.74 V, Jsc of 12.1 mA/cm2, and an FF of 0.60. Thus, this study highlights that the use of Ag/Ti/Zn TNPs and CQDs NCs has the great potential to be used as a photosensitizer.

Synthesis of Chitosan-Stabilized Gold Nanorod Using Tripolyphosphate

2013 ◽  
Vol 652-654 ◽  
pp. 250-253
Author(s):  
Hua Nan Guan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Chemical Synthesis ◽  
Gold Nanorods ◽  
Gold Nanorod ◽  
Gold Salt ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Seed Mediated

An improvement in the previously reported seed-mediated chemical synthesis of gold nanorods (GNRs) is reported. Gold nanoparticles were prepared by reducing gold salt with a polysaccharide, chitosan, in the presence of tripolyphosphate (TPP). The obtained gold nanoparticles were characterized with UV-vis spectroscopy and transmission electron microscopy. The study shows that TPP plays an important role in the formation of GNRs.

scholarly journals Biocide Activity of Green Quercetin-Mediated Synthesized Silver Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 909 ◽  
Author(s):  
Federico Tasca ◽  
Riccarda Antiochia
Keyword(s):  
Electron Microscopy ◽  
Silver Nanoparticles ◽  
Room Temperature ◽  
Inhibitory Concentration ◽  
Toxic Chemicals ◽  
Candida Sp ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
20 Nm ◽  
Mic Value

The development of new nanomaterials is gaining increasing attention due to their extensive applications in fields ranging from medicine to food and cultural heritage. Green nanoparticles provide advantages compared to conventional nanoparticles as their synthesis is environmentally-friendly and does not require the use of high temperatures, pressure, or toxic chemicals. In this paper, green silver nanoparticles (AgNPs) have been synthesized according to a new method using quercetin as a reducing agent at room temperature. The synthesized AgNPs were characterized using UV-Vis spectroscopy, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and dynamic light scattering (DLS) techniques and successively tested for biocide activity by studying their effects in the inhibition of bacterial growth. The results demonstrated that the smaller the AgNPs size, the greater their biocide activity. In particular, AgNPs with a diameter of 8 nm showed a minimum inhibitory concentration (MIC) value of 1.0 μg/mL against Streptococcus sp., Escherichia coli and Candida sp. microorganisms, while AgNPs with a larger diameter of about 20 nm were able to inhibit microbial of all selected pathogens at a higher MIC value of 2.5 μg/mL.

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