One-step Synthesis Of Gold Nanoparticles Research Articles

Facile one-step synthesis of gold nanoparticles using Viscum album and evaluation of their antibacterial potential.

Nanostructure gold nanoparticles (Au NPs) are well-known biological active materials, synthesised under different environment-friendly approaches that has gained significant interest in the field of biomedicine. This study investigated a novel, fast, easy, cost-effective and the eco-friendly method to synthesise Au NPs from mediated Viscum album Linn plant extract, where the plant metabolites act as stabilising and reducing agents. The synthesised Au NPs were analysed by UV/Vis spectroscopy that gave strong signals and a sharp absorption peak at 545nm due to the presence of surface plasmon resonance (SPR) bands. In addition, energy dispersive X-ray spectroscopy (EDX) showed that strong signals of Au NPs appeared at 9.7 and 2.3keV, as the rays of light passed. X-ray diffraction recognised the crystalline material and provided information on the cell unit that the synthesised Au NPs are face-centreed cubic in structure. The diffraction of X-ray spectra showed intense peaks at 38.44°, 44.7°, 44.9° and 77.8°. The mediated V. album plant extracts and synthesised Au NPs were screened against gram-positive and gram-negative (Enterobacter, Salmonella typhi, Escheria coli and Bacillus subtilis) bacterial strains, confirming their antibacterial potential. Au NPs showed strong antibacterial activity due to its unique steric configuration. Au NPs damaged bacterial cell membrane leading to the leakage of the cytoplasm and death of the cell.

One-step synthesis of gold nanoparticles for catalysis and SERS applications using selectively dicarboxylated cellulose and hyaluronate

Properties and applications of gold nanoparticles (AuNPs) depend on their characteristics which are intrinsically connected to the reducing and capping agents used in their synthesis. Although polysaccharides are commonly used for Au salt reduction, the control over the result is often limited. Here, the selectively dicarboxylated cellulose (DCC) and hyaluronate (DCH) with adjustable composition and molecular weight are used for the first time as reducing and capping agents for AuNPs preparation in an environmental friendly one-step synthesis. Mechanism of reduction and structure-function relationships between the composition of oxidized polysaccharides and properties of formed AuNPs are elucidated and the variances in the macromolecular architecture of dicarboxypolysaccharides are applied to guide the growth of AuNPs. While the homogenous structure and high density of carboxyl groups of fully-oxidized DCC induced isotropic growth of small and uniform AuNPs with good catalytic performance (d = ~20 nm, TOF = 7.3 min−1, k = 1.47 min−1), the lower stabilizing potential and slower reduction rates of the DCH induced the anisotropic growth of larger polyhedral ~50 nm nanoparticles, which increased the Surface-Enhanced Raman Scattering efficacy (9× stronger Raman signals on average compared to AuDCC). The use of dicarboxypolysaccharides with adjustable composition and properties thus introduced a new degree of freedom for the preparation of AuNPs with desired properties.

Synthesis of Gold Nanoparticles using Endophytic streptomyces and its Bactericidal Activities against Enteric Bacterial Pathogens

The present study aimed to report the rapid and one-step synthesis of gold nanoparticles (AuNPs) using the cell-free supernatant (CFS) of an endophytic Streptomyces sp. BDUSMP S05 isolated from Solanum trilobatum. The synthesized AuNPs were characterized by using UV-visible spectroscopy (UV-vis), Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDAX) spectroscopy and X-ray diffraction (XRD). The UV-visible spectroscopy (UV-vis) absorption of colloidal AuNPs displayed a surface plasma resonance (SPR) centred at 533 nm. FESEM micrograph analysis showed that synthesized particles were predominantly spherical with a 20-30 nm size range. Dynamic light scattering (DLS) analysis showed that the average particle size varied between 2-28 nm. Zeta potential analysis indicated the negative value of -35.2 mV characteristic for stable AuNPs. The synthesized AuNPs displayed significant antimicrobial activity against Gram-negative bacteria, including Eescherichia coli, Salmonella typhi and Vibrio cholerae compared to CFS alone. The results revealed that endophytic Streptomyces sp. potential to be used for the synthesis of antibacterial gold nanobased materials.

One-step synthesis of gold nanoparticles carried by boehmite

In this work, we proposed a simple method to synthesize gold nanoparticles carried by boehmite, which was made directly from Al/Au bilayer films by a one-step hydrothermal treatment. The boehmite carrier is porous with a special density-gradient structure. As a result, the embedded gold nanoparticles demonstrate good size uniformity, strong surface plasmon resonance, and good affinity for reacting solution. Such nanoparticles carried by boehmite exhibit the high potential of applications as efficient catalysts and sensitive bio-sensors.

SYNTHESIS OF GOLD NANOPARTICLES BY TETRACHLOROAURATE REDUCTION WITH CYCLODEXTRINS

One-step synthesis of gold nanoparticles functionalized with α-, β- and γ-cyclodextrins was carried out using a synthetic method of direct tetrachloroaurate reduction in alkaline solutions. The two experimental conditions studied were direct heating and microwave irradiation. This is the first publication comparing the characteristics of gold nanoparticles produced using three cyclodextrins under different conditions. The resulting nanoparticles were characterized by absorbance spectra, FTIR spectra, dynamic light scattering data and transmission electron microscopy images. The reducing ability of cyclodextrins increased in the following order: β-cyclodextrin < α-cyclodextrin < γ-cyclodextrin. Therefore, γ-cyclodextrin was the most active reductant and the only cyclodextrin that was able to reduce tetrachloroaurate at room temperature. In this case, nanoparticles were observed only after 4 days of storage. The nanoparticle size was dependent on the cyclodextrin type and correlated with the difference in the reducing ability. Using microwave irradiation, most of nanoparticles were found to be free nanoparticles. Using direct heating, aggregates formed due to the high ionic strength of the solution after prolonged boiling. Therefore, nanoparticles synthesized by direct heating were less stable during storage than those synthesized by microwave irradiation.

Rapid one-step synthesis of gold nanoparticles using the ubiquitous coenzyme NADH

Rapid one-step synthesis of gold nanoparticles using the ubiquitous coenzyme NADH

A novel green one-step synthesis of gold nanoparticles using crocin and their anti-cancer activities

Functionalized nanoparticles are specifically designed to deliver drugs at tumor cells and can potentially enhance anticancer activity of drugs such as crocin. In the present study, we have applied antioxidant crocin as a reducing agent for one pot green synthesis of controlled size gold nanoparticles (AuNPs). Spherical, stable and uniform AuNPs were synthesized using crocin. These AuNPs are characterized by UV–Vis, TEM and XRD techniques. The prepared AuNPs showed surface plasm on resonance centered at 520nm with the average particle size of about 4–10nm. The anti-cancer effect of AuNPs was determined using MTT and LDH tests. The cellular data showed that these AuNPs significantly decreased cancerous cells' growth after 24 and 48hours in a time- and dose-dependent manner (P<0.05). The results suggest that such AuNPs can be synthesized simply and quickly with invaluable clinical as well as pharmaceutical activities which can help to treat human breast cancer.

Preparation of Au-polydopamine functionalized carbon encapsulated Fe₃O₄ magnetic nanocomposites and their application for ultrasensitive detection of carcino-embryonic antigen.

A novel carbon encapsulated Fe3O4 nanoparticles embedded in two-dimensional (2D) porous graphitic carbon nanocomposites (Fe3O4@C@PGC nanocomposites) were synthesized by situ synthesis strategy, which provided a sensor platform owing to a large aspect ratio and porous structure. Polydopamine (PDA) were modified on the surface of Fe3O4@C@PGC nanocomposites through self-polymerization of dopamine, acting as both the reductant and template for one-step synthesis of gold nanoparticles. The prepared Au/PDA/Fe3O4@C@PGC nanocomposites show ferromagnetic features, extremely excellent electron transfer, large specific surface area and excellent dispersing property. These are conducive to the electrochemical signal output and the immobilization of antibody. In this work, a highly label-free sensitive magnetic immunosensor was developed based on Au/PDA/Fe3O4@C@PGC nanocomposites for the detection of carcino-embryonic antigen (CEA). The magnetic glassy carbon electrode was used to fix the Au/PDA/Fe3O4@C@PGC nanocomposites with the help of magnetic force. Under the optimal conditions, the immunosensor exhibited a wide linear range (0.001 ng/mL–20.0 ng/mL), a low detection limit (0.33 pg/mL), good reproducibility, selectivity and acceptable stability. The proposed sensing strategy may provide a potential application in the detection of other cancer biomarkers.

Bromide-Assisted Anisotropic Growth of Gold Nanoparticles as Substrates for Surface-Enhanced Raman Scattering

We report herein a one-step synthesis of gold nanoparticles (Au NPs) of various shapes such as triangles, hexagons, and semispheres, using 5-hydroxyindoleacetic acid (5-HIAA) as the reducing agent in the presence of potassium bromide (KBr). Anisotropic Au NPs have received ever-increasing attention in various areas of research due to their unique physical and chemical properties. Numerous synthetic methods involving either top-down or bottom-up approaches have been developed to synthesize Au NPs with deliberately varied shapes, sizes, and configurations; however, the production of templateless, seedless, and surfactant-free singular-shaped anisotropic Au NPs remains a significant challenge. The concentrations of hydrogen tetrachloroaurate (HAuCl4), 5-HIAA, and KBr, as well as the reaction temperature, were found to influence the resulting product morphology. A detailed characterization of the resulting Au NPs was performed using ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy. The as-prepared Au NPs exhibited excellent surface-enhanced Raman scattering (SERS) properties, which make them very attractive for the development of SERS-based chemical and biological sensors.

Synthesis and multifunctional properties of lignosulfonate-stabilized gold nanoparticles

Various technical lignosulfonates (LSs) were used as reducing and stabilizing agents for a novel one-step synthesis of gold nanoparticles (LS–AuNPs) in aqueous solution at room temperature. As a result, stable colloids of LS–AuNPs are formed during the reaction with the particle size being the function of the LS type. The obtained LS–AuNPs were characterized by UV–vis spectrophotometry, size distribution (DLS) and transmission electron microscopy (TEM). The resulting gold colloids can be used for different purposes, e.g. as chemical probes for the presence of heavy metals, as signal amplifiers in surface enhanced Raman spectroscopy (SERS) or as electrocatalysts as evidenced by preliminary cyclic voltammetry study (CV). The obtained results clearly indicate the possibility of low-cost production of large quantities of colloidal gold–lignosulfonate nanoparticles using waste materials derived from renewable sources.

Polyphenol–gelatin nanoparticles as reductant and stabilizer for one-step synthesis of gold nanoparticles and their interfacial behavior

Polyphenol and gelatin self-assembled nanoparticles acted as a reductant for the synthesis of AuNPs and then stabilized oil–water interfaces.

A novel one-step synthesis of gold nanoparticles in an alginate gel matrix by solution plasma sputtering

We report a novel strategy to produce stable colloidal gold nanoparticles (AuNPs) in alginate aqueous solution which can be done in one step and without any chemicals. The AuNPs were produced by applying a voltage across a pair of gold electrodes which were immersed in alginate aqueous solution. Since the generation of AuNPs was caused by the sputtering of gold electrodes, the process was named the solution plasma sputtering (SPS) process. We utilize the alginate polymer in order to meet three important requirements: (1) to promote the generation of plasma in a liquid environment, (2) to endow biocompatibility to the AuNPs, and (3) to provide colloidal stability to the AuNPs-alginate aqueous suspensions. The alginate concentrations were varied as 0.2, 0.5, and 0.9 %w/v. The concentration-dependent effect on the particle size of AuNPs, the physical absorption property and the stability of the AuNPs-alginate suspensions were studied. Results indicate that preparation of chemical-free colloidal AuNPs-alginate aqueous suspension is successful by the SPS process. The obtained colloidal suspensions were stable and able to retain their strong plasmon absorption bands within a reasonable time period. As a consequence, this is a high-potential technique to produce AuNPs suspended in alginate aqueous solution appropriate for biomedical applications.

Methanobactin-Mediated One-Step Synthesis of Gold Nanoparticles

Preparation of gold nanoparticles with a narrow size distribution has enormous importance in nanotechnology. Methanobactin (Mb) is a copper-binding small peptide that appears to function as an agent for copper sequestration and uptake in methanotrophs. Mb can also bind and catalytically reduce Au (III) to Au (0). In this study, we demonstrate a facile Mb-mediated one-step synthetic route to prepare monodispersed gold nanoparticles. Continuous reduction of Au (III) by Mb can be achieved by using hydroquinone as the reducing agent. The gold nanoparticles have been characterized by UV-visible spectroscopy. The formation and the surface plasmon resonance properties of the gold nanoparticles are highly dependent on the ratio of Au (III) to Mb in solution. X-ray photoelectron spectroscopy (XPS), fluorescence spectra and Fourier transform-infrared spectroscopy (FT-IR) spectra suggest that Mb molecules catalytically reduce Au (III) to Au (0) with the concomitant production of gold nanoparticles, and then, Mb statically adsorbed onto the surface of gold nanoparticles to form an Mb-gold nanoparticles assembly. This avoids secondary nucleation. The formed gold nanoparticles have been demonstrated to be monodispersed and uniform by transmission electron microscopy (TEM) images. Analysis of these particles shows an average size of 14.9 nm with a standard deviation of 1.1 nm. The gold nanoparticles are extremely stable and can resist aggregation, even after several months.

Saraca indica bark extract mediated green synthesis of polyshaped gold nanoparticles and its application in catalytic reduction

The bark extract of the traditional ayurvedic medicinal plant Saraca indica containing redox active polyphenolic compounds has been utilized for the one-step synthesis of gold nanoparticles at room temperature. The polyphenolic compounds acted as the reducing agent as well as the stabilizing agent without any additional capping agent. The synthesis of the gold nanoparticles of 15–23 nm size was complete in several minutes and no photo irradiation or heat treatment was necessary. Surface plasmon resonance, HRTEM, AFM, X-ray diffraction, and FTIR studies have been carried out to characterize the nanoparticles. Gold nanoparticles synthesized were of triangular, tetragonal, pentagonal, hexagonal, and spherical shapes. The synthesized gold nanoparticles have been used as a catalyst for the reduction of 4-nitrophenol to 4-aminophenol at room temperature and the kinetics of the reduction reaction has been studied spectrophotometrically.

Green and one-step synthesis of gold nanoparticles incorporated into electrospun cyclodextrin nanofibers

The green and one-step synthesis of gold nanoparticles (Au-NP) incorporated into electrospun cyclodextrin-nanofibers (CD-NF) without the use of a carrier polymer matrix was achieved in this study. Chemically modified CD (hydroxypropyl-β-cyclodextrin (HPβCD)) was used as both a reducing and stabilizing agent as well as a fiber matrix for the electrospinning of HPβCD/Au-NP-NF composite mats. Electrospinning of metallic NP incorporating CD-NF would have exclusive properties by combining the very large surface area of nanofibers with specific functionality of the metal NP and CD.

Simple one-step synthesis of gold nanoparticles with controlled size using cationic Gemini surfactants as ligands: Effect of the variations in concentrations and tail lengths

Gold nanoparticles with diameters ranging from 1.3 to 10.2nm have been synthesized by in situ reduction of HAuCl4 with NaBH4 in aqueous phase using Gemini surfactants as ligands. Their properties/behaviors were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and zeta potential spectroscopy. FTIR and zeta potential measurements suggest that surface aggregates adsorb on the nanoparticle surface at high surfactant surface coverage. Above the CMC, micelles could serve as stabilizers that lead to the formation of ultrasmall nanoparticles. It is interesting to note that at low surfactant concentrations, surface aggregates adsorbed on gold nanoparticles might bridge small particles, which results in the formation of larger nanoparticles. However, when the surfactant concentration was further reduced to 1μM, the AuNPs precipitated, indicating that 0.1mM is the lowest concentration to obtain stable nanoparticles in this study. In addition, the average particle size decreases at a given surfactant concentration as the tail length of the Gemini surfactant is increased. As a result, the particle size can be controlled by the variations in concentration and/or tail length of the Gemini surfactants.

Facile synthesis of biocompatible gold nanoparticles with organosilicone-coated surface properties

In this study, a simple method for one-step synthesis of gold nanoparticles has been developed using an organosilicone surfactant, Silwet L-77, as both a reducing and capping agent. Synthesis of gold nanoparticles using this method is rapid and can be conducted conveniently at ambient temperature. Further refinement of the method, through the addition of sodium hydroxide and/or silver nitrate, allowed fine control over the size of spherical nanoparticles produced. Coated on the surface with organosilicone, the as-prepared gold nanoparticles were biocompatible and stable over the pH range from 5 to 12, and have been proven effective at transportation into MC3T3 osteoblast cells. The proposed method is simple, fast, and can produce size-controlled gold nanoparticles with unique surface properties for biomedical applications.

One-step synthesis of gold nanocatalysts on a microstructured paper matrix for the reduction of 4-nitrophenol

The one-step synthesis of gold nanoparticles (AuNPs) was achieved, in situ, on a microstructured paper composite that consisted of ceramic fibers which acted as the main frame with zinc oxide (ZnO) whiskers being used as the selective support for the AuNPs. Initially, ZnO whiskers were incorporated into a ceramic paper matrix using a high-speed and low-cost papermaking technique, and the AuNPs were then synthesized onto the embedded ZnO whiskers via a simple soaking treatment using an aqueous solution of tetrachloroauric acid (HAuCl 4). The as-prepared hybrid material has the appearance of paperboard and is denoted as AuNPs@ZnO paper. It was lightweight, flexible, sufficiently strong and easy-to-handle in practical use, and possessed a paper-like porous microstructure. In the liquid-phase reduction process of 4-nitrophenol, the AuNPs@ZnO paper demonstrated excellent catalytic performance compared with conventional Au/ZnO catalyst powders. This suggests that the unique paper structure, which has an open pore system throughout the structure, promotes the efficient transport of the reactants to the surfaces of the highly effective AuNPs. Thus, this AuNPs@ZnO paper is expected to be a promising catalytic material having a high degree of practical utility and catalytic efficiency.

One-step, size-controlled synthesis of gold nanoparticles at room temperature using plant tannin

Bayberry tannin (BT), a natural plant polyphenol, was used for one-step synthesis of gold nanoparticles (AuNPs) in aqueous solution at room temperature. During the synthetic process, BT simultaneously serves as a reducing agent and stabilizing agent, while no additional reagent (surfactant, template, and capping agent) or treatment (heat and photo-irradiation) is needed. The particle diameter and size distribution of BT-stabilized AuNPs (BT-AuNPs) can be facilely controlled by varying the concentration of BT, and the particle size of BT-AuNPs is as small as 1.8 ± 0.3 nm when the BT concentration was 800 mg L−1. Furthermore, this green approach for the auto-reduction synthesis of AuNPs can be completed in several minutes and exhibits high reproducibility, which shows great potential for practical applications.

Redox-Active Ultrathin Template of Silk Fibroin: Effect of Secondary Structure on Gold Nanoparticle Reduction

We report on an application of silk as an ultrathin redox-active template for controllable, one-step synthesis of gold nanoparticles via control over silk secondary structure. We found that both silk I and silk II molecular layers can facilitate gold nanoparticle formation at ambient conditions, indicating that tyrosine groups are available for metal ion reduction in both forms of silk. We suggest that the presence of β-sheets in silk II facilitates tyrosine ordering thereby resulting in well-dispersed, uniform nanoparticles with diameters of less than 6 nm. In addition, the mineralization does not result in transformation of the silk I secondary structure to silk II. In fact, the silk I structure is stabilized from further transformation into silk II even upon drying. These results are critical for developing a better understanding of silk interfacial behavior and offer an opportunity to design a new class of nanocomposites that combine the beneficial features of silk with those of the nanoparticles.