Synthesis of L-Phenylalanine Stabilized Gold Nanoparticles and Their Thermal Stability

2006 ◽  
Vol 6 (11) ◽  
pp. 3512-3516 ◽  
Author(s):  
Nimai C. Nayak ◽  
Kwanwoo Shin
Keyword(s):  
Thermal Stability ◽  
Gold Nanoparticles ◽  
Electron Microscope ◽  
Ambient Condition ◽  
Synthesis Methods ◽  
Chloroauric Acid ◽  
Borohydride Reduction ◽  
Thermal Stabilities ◽  
Transmission Electron ◽  
Vis Spectroscopy

Here we described the two synthesis methods of L-phenylalanine (L-phe) coated gold nanoparticles through a reduction of aqueous chloroaurate ions directly by L-phe, and also the borohydride reduction of chloroauric acid followed by capping with L-phe molecules. Phenylalanine reduced gold nanoparticles and the phenylalanine capped gold nanoparticles were evaluated by transmission electron microscope and UV-vis spectroscopy, and then their thermal stabilities were compared. We found that the phenylalanine reduced gold nanoparticles were unstable and form linearly arranged aggregates on aging, while as the phenylalanine capped gold nanoparticles were stable for months in ambient condition.

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.

Seed-mediated synthesis and PEG coating of gold nanoparticles for controlling morphology and sizes

MRS Advances ◽  
2020 ◽  
Vol 5 (63) ◽  
pp. 3353-3360
Author(s):  
Susana Helena Arellano Ramírez ◽  
Perla García Casillas ◽  
Christian Chapa González
Keyword(s):  
Gold Nanoparticles ◽  
Polyethylene Glycol ◽  
Room Temperature ◽  
Colloidal Stability ◽  
Infrared Spectrometry ◽  
Ammonium Bromide ◽  
Chloroauric Acid ◽  
Vis Spectroscopy ◽  
Seed Mediated ◽  
Peg Coating

AbstractA significant area of research is biomedical applications of nanoparticles which involves efforts to control the physicochemical properties through simple and scalable processes. Gold nanoparticles have received considerable attention due to their unique properties that they exhibit based on their morphology. Gold nanospheres (AuNSs) and nanorods (AuNRs) were prepared with a seed-mediated method followed of polyethylene glycol (PEG)-coating. The seeds were prepared with 0.1 M cetyltrimethyl-ammonium bromide (CTAB), 0.005 M chloroauric acid (HAuCl4), and 0.01 M sodium borohydride (NaBH4) solution. Gold nanoparticles with spherical morphology was achieved by growth by aggregation at room temperature, while to achieve the rod morphology 0.1 M silver nitrate (AgNO3) and 0.1 M ascorbic acid solution were added. The gold nanoparticles obtained by the seed-mediated synthesis have spherical or rod shapes, depending on the experimental conditions, and a uniform particle size. Surface functionalization was developed using polyethylene glycol. Morphology, and size distribution of AuNPs were evaluated by Field Emission Scanning Electron Microscopy. The average size of AuNSs, and AuNRs was 7.85nm and 7.96 x 31.47nm respectively. Fourier transform infrared spectrometry was performed to corroborate the presence of PEG in the AuNPs surface. Additionally, suspensions of AuNSs and AuNRs were evaluated by UV-Vis spectroscopy. Gold nanoparticles were stored for several days at room temperature and it was observed that the colloidal stability increased once gold nanoparticles were coated with PEG due to the shield formed in the surface of the NPs and the increase in size which were 9.65±1.90 nm of diameter for AuNSs and for AuNRs were 29.03±5.88 and 8.39±1.02 nm for length and transverse axis, respectively.

Optimization of Gold Nanoparticles Synthesis using Design of Experiments Technique

2017 ◽  
Vol 68 (7) ◽  
pp. 1518-1423
Author(s):  
Adina Turcu Stiolica ◽  
Mariana Popescu ◽  
Maria Viorica Bubulica ◽  
Carmen Nicoleta Oancea ◽  
Claudiu Nicolicescu ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Zeta Potential ◽  
Design Of Experiments ◽  
Process Model ◽  
Sodium Citrate ◽  
Drug Carriers ◽  
Chloroauric Acid ◽  
Gold Colloids ◽  
Citrate Concentration ◽  
Vis Spectroscopy

Gold nanoparticles are considered the newest drug carriers for different diseases. Therefore it is appropriate continuous optimization of their preparation. In this study, gold colloids with an average size of 1 - 26 nm were obtained by the reduction of tetrachloroauric acid with trisodium citrate. The nanomaterials were characterized by UV-Vis spectroscopy and dynamic light scattering technique. In addition, zeta potential was measured for samples synthesized in order to determine the stability of the colloids. A Two-level Full Factorial design was chosen to determine the optimum set of process parameters (chloroauric acid concentration and sodium citrate concentration) and their effect on various gold nanoparticles characteristics (size and zeta potential). These effects were quantified using Design of Experiments (DoE) with 5 runs and 1 centerpoint. The selected objective and process model in this investigation are screening and interaction. Findings from this research show that to obtain particles larger than 35 nm, it is recommended to increase sodium citrate concentration, at low chloroauric acid values. These conditions will help to achieve smaller zeta potential, too.

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.

Effect of Voltage on Colloidal Gold (Au) Nanoparticles Produced Using Electro-Dissolution-Reduction Method

2015 ◽  
Vol 1115 ◽  
pp. 386-389
Author(s):  
Haroon Haiza ◽  
I.I. Yaacob ◽  
Ahmad Zahirani Ahmad Azhar
Keyword(s):  
Gold Nanoparticles ◽  
Electron Microscope ◽  
Colloidal Gold ◽  
Reduction Process ◽  
Chloride Ions ◽  
Complex Ions ◽  
Dc Power ◽  
Colloidal Gold Nanoparticles ◽  
Transmission Electron ◽  
The Mean

Colloidal gold nanoparticles have been successfully prepared using a simple two-electrode cells connected to a DC power supply. During the electro-dissolution-reduction process, the bulk gold at the anode oxidized into gold cations which then reacted with the chloride ions to form aurochloride complex. The complex ions were then reduced by the citrate ion to form colloidal gold nanoparticles. The size and shape of the nanoparticles were modulated by varying the terminal voltages. The colloidal gold nanoparticles obtained were characterized by field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and ultraviolet-visible spectrophotometer (UV-Vis). From FESEM analysis, it was found that by increasing the voltage, the size of colloidal gold nanoparticles produced marginally decreased. The mean sizes of gold nanoparticles were roughly about 23.5 nm, 23.2 nm and 19.3 nm for 32 V, 36 V and 40 V, respectively. TEM micrograph showed that the shape of gold nanoparticles obtained is almost spherical. The characteristic peaks of UV-Vis spectra revealed that the suspension was indeed colloidal gold nanoparticles. Keywords: Gold, Nanoparticles, Electro-dissolution-reduction

scholarly journals Aggregation of Gold Nanoparticles in Presence of the Thermoresponsive Cationic Diblock Copolymer PNIPAAM48-b-PAMPTMA6

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4066
Author(s):  
David Herrera Robalino ◽  
María del Mar Durán del Amor ◽  
Carmen María Almagro Gómez ◽  
José Ginés Hernández Cifre
Keyword(s):  
Gold Nanoparticles ◽  
High Ionic Strength ◽  
Solution Temperature ◽  
Trimethylammonium Chloride ◽  
Aggregation Process ◽  
Critical Solution Temperature ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Copolymer Poly ◽  
Positively Charged

The adsorption of the thermoresponsive positively charged copolymer poly(N-isopropylacrylamide)-block-poly(3-acrylamidopropyl)trimethylammonium chloride, PNIPAAM48-b-PAMPTMA6(+), onto negatively charged gold nanoparticles can provide stability to the nanoparticles and make the emerging structure tunable by temperature. In this work, we characterize the nanocomposite formed by gold nanoparticles and copolymer chains and study the influence of the copolymer on the expected aggregation process that undergoes those nanoparticles at high ionic strength. We also determine the lower critical solution temperature (LCST) of the copolymer (around 42 °C) and evaluate the influence of the temperature on the nanocomposite. For those purposes, we use dynamic light scattering, UV-vis spectroscopy and transmission electron microscopy. At the working PNIPAAM48-b-PAMPTMA6(+) concentration, we observe the existence of copolymer structures that trap the gold nanoparticles and avoid the formation of nanoparticles aggregates. Finally, we discuss how these structures can be useful in catalysis and nanoparticles recovery.

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.

Synthesis of Uniform and High Density Silver Nanoparticles by using Peltophorum pterocarpum flower Extract

2014 ◽  
Vol 1584 ◽  
Author(s):  
Matheswaran BALAMURUGAN ◽  
Shanmugam SARAVANAN ◽  
Naoki OHTANI
Keyword(s):  
Silver Nanoparticles ◽  
Fourier Transform ◽  
Electron Microscope ◽  
Ultra Violet ◽  
Capping Agent ◽  
Nanosized Particles ◽  
Flower Extract ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Ft Ir

ABSTRACTSilver nanoparticle (AgNP) is one of the elegant material because its uses in various fields. In this study, AgNPs have been prepared by using Peltophorum pterocarpum (PP) flower extract as reducing and capping agent and aqueous silver nitrate (aq.AgNO3) as silver precursor. The synthesized nanoparticles were characterized using Ultra Violet - Visible (UV-Vis) spectroscopy, High Resolution Transmission Electron Microscope (HR-TEM) and Fourier Transform Infrared Spectroscopy (FT-IR), which reveals the formation of nanosized particles. The UV-Vis spectrum shows an absorption peak around 430nm. HR-TEM images of AgNPs with clear morphology and well dispersed prepared AgNPs.

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.

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