Synthesis Of Ag Nanoparticles Research Articles

Silver Nanoparticle Synthesis Using Monosaccharides and Their Growth Inhibitory Activity against Gram-Negative and Positive Bacteria

Using various monosaccharides as reductant, we synthesized Ag nanoparticles (NPs) in seconds employing the household microwave method described earlier. The Ag NPs containing colloidal solution showed distinctive colors with varying λmax. The sizes of the NPs formed varied significantly from 10 to 35 nm in good agreement with the localized plasmon resonance ranged from ~300 to ~600 nm. The antimicrobial properties of these NPs were compared in Gram-negative and positive bacteria in liquid culture. Gram-positive bacteria were highly susceptible compared to Gram-negative microbes—the additional lipopolysaccharide layer covering the peptidoglycan cell wall in the latter somewhat lessens the effect. The results indicated that larger NPs produced by glucose inhibited bacterial growth better than the smallest NPs produced by ribose. This may be attributed to the higher aggregation rate for larger NPs on cell wall. SEM analysis showed accumulation of NPs on cell surface and defect in budding, further supporting the cell wall interaction with Ag NPs. These observations suggested that the growth inhibition of Ag NPs is mediated by interfering with the bacterial cell wall peptidoglycan.

Synthesis of Silver Nanoparticles in Star-Like Dextran-Graft-Polyacrylamide Matrices

Branched copolymers Dextran-graft-Polyacrylamide (D-g-PAA) with star-like architecture of macromolecules and linear Polyacrylamide (PAA) were used for in situ synthesis of Ag nanoparticles. Aqueous silver colloids were characterized by UV-vis spectroscopy, TEM and dynamic light scattering. The internal structure of polymer matrices in solution affects the Ag nanoparticle formation and stability of colloid systems. Branched structure of D-g-PAA macromolecules provides obtaining of stable silver colloids even at high temperature when linear PAA matrix is not efficient.

Synthesis of Nanoparticles Using Euphorbia prostrata Extract Reveals a Shift from Apoptosis to G0/G1 Arrest in Leishmania donovani

The aim of the present investigation was to synthesize silver (Ag) and titanium dioxide (TiO2) nanoparticles (NPs) using the aqueous leaves extract of Euphorbia prostrata as antileishmanial agents and to explore the mechanism of induced cell death. In vitro antileishmanial activity of synthesized NPs was tested against promastigotes of Leishmania donovani by alamar Blue® cell viability reagent and propidium iodide uptake assay. The effective leishmanicidal activity of synthesized Ag NPs was further confirmed by cell cycle progression, externalized phosphatidylserine, DNA fragmentation assay, reactive oxygen species (ROS) level, intracellular non-protein thiols and transmission electron microscopy (TEM) of the treated parasites. TEM analysis of the synthesized Ag NPs and TiO2 NPs showed spherical shape with an average size of 12.82 ± 2.50 and 83.22 ± 1.50 nm, respectively. Ag NPs was found to be the most active agent against Leishmania parasites after 24 h exposure with IC50 value of 14.94 μg/mL. A significant increase in G0/ G1 phase of the cell cycle with subsequent decrease in S and G2/M phases was observed when compared to control and thus confirming the growth inhibitory effect of synthesized Ag NPs. Decreased ROS level was also observed which could be responsible for caspase independent shift from apoptosis (G0/G1 arrest) to massive necrosis. High molecular weight DNA fragmentation as a positive consequence of necrotic cell death was also visualized. In the present study, the unique trypanothione/trypanothione reductase (TR) system of Leishmania cells was significantly inhibited by synthesized Ag NPs was reported. The green synthesized Ag NPs may provide promising leads for the development of cost effective and safer alternative treatment against visceral leishmaniasis.

Green synthesis, characterisation and biological studies of silver nanoparticles using Dalbergia sissoides seeds and ecofriendly reduction of 4-nitrophenol

Green synthesis of Ag nanoparticles (AgNPs) has been of great interest because of its potential nanomedical applications. In this study, Dalbergia sissoides seeds (DSS) served as a reducing as well as a stabilising agent simultaneously thereby necessitating no additional reagent or further treatment. Appearance of surface plasmon band at 432 nm within 35 sec of microwave irradiation indicated the formation of DSS-silver nanoparticles. TEM analysis showed the DSS-AgNPs to be almost spherical in shape with a size of 18 ± 2 nm. When evaluated for their in vitro antioxidant activity, the nanoparticles showed considerably better activity when compared to that of the standard and the plant extract. Evaluation of anti-inflammatory activity of DSS-AgNPs by in-vitro method at a concentration of 10 µg/ml showed considerably better activity (94.05%), when compared to that of the plant extract (85.45%). The synthesised silver nanoparticles were also found to be effective in catalytic reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP).

The general synthesis of Ag nanoparticles anchored on silver vanadium oxides: towards high performance cathodes for lithium-ion batteries

A general approach has been developed to synthesize a series of silver vanadium oxides (SVOs) anchored with Ag nanoparticles (including AgVO3, Ag2V4O11, Ag0.33V2O5 and Ag1.2V3O8), which exhibit highly improved electrochemical performances.

Nitrogen-doped carbon nanodots as a reducing agent to synthesize Ag nanoparticles for non-enzymatic hydrogen peroxide detection

Download options Please wait... Article information DOI https://doi.org/10.1039/C3RA44492A Article type Communication Submitted 20 Aug 2013 Accepted 30 Oct 2013 First published 06 Nov 2013 Download Citation RSC Adv., 2014,4, 544-548 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Nitrogen-doped carbon nanodots as a reducing agent to synthesize Ag nanoparticles for non-enzymatic hydrogen peroxide detection S. Liu, B. Yu and T. Zhang, RSC Adv., 2014, 4, 544 DOI: 10.1039/C3RA44492A To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Sen Liu Bo Yu Tong Zhang

Polymer-Mediated Formation and Assembly of Silver Nanoparticles on Silica Nanospheres for Sensitive Surface-Enhanced Raman Scattering Detection

To impart a desired optical property to metal nanoparticles (NPs) suitable for surface-enhanced Raman scattering (SERS) applications, it is crucial to assemble them in two or three dimensions in addition to controlling their size and shape. Herein, we report a new strategy for the synthesis and direct assembly of Ag NPs on silica nanospheres (AgNPs-SiNS) in the presence of poly(ethylene glycol) (PEG) derivatives such as PEG-OH, bis(amino)-PEGs (DA-PEGs), and O,O'-bis(2-aminopropyl)PEG (DAP-PEG). They exhibited different effects on the formation of Ag NPs with variable sizes (10-40 nm) and density on the silica surface. As the molecular weight (MW) of DA-PEGs increased, the number of Ag NPs on the silica surface increased. In addition, DAP-PEG (MW of 2000), which has a 2-aminopropyl moiety at both ends, promoted the most effective formation and assembly of uniform-sized Ag NPs on a silica surface, as compared to the other PEG derivatives with the same molecular weight. Finally, we demonstrated that AgNPs-SiNS bearing 4-fluorobenzenethiol on its surface induced the strong SERS signal at the single-particle level, indicating that each hybrid particle has internal hot spots. This shows the potential of AgNPs-SiNS for SERS-based sensitive detection of target molecules.

Biosynthesis of silver nanoparticles through tandem hydrolysis of silver sulfate and cellulose under hydrothermal conditions

BACKGROUND Biosynthesis of Ag nanoparticles (AgNPs) utilizing renewable materials and nontoxic chemicals has become highly desirable and is currently receiving tremendous attention. In this study, a facile and cellulose-based approach was developed to biosynthesize AgNPs through tandem hydrolysis of silver sulfate and cellulose under hydrothermal conditions. RESULTS Well-defined AgNPs of about 72.0 nm in size were biosynthesized with 0.30 g of cellulose at 200°C for 10 h. The particle sizes of the as-synthesized AgNPs were positively affected by the reaction temperature and time, but on the contrary were negatively affected by the amount of cellulose employed. The results from Fourier transform infrared spectroscopy showed that the cellulose-hydrolyzed products (saccharides or aldehydes) were accountable for the bioreduction of the Ag ions, and the C = O (C–O) groups in the aldehydes or saccharides played critical roles in capping the AgNPs. Additionally, in the presence of the as-synthesized AgNPs, enhanced surface fluorescence of methyl orange was achieved. CONCLUSION A biological and maneuverable strategy was successfully developed for the synthesis of AgNPs by a hydrothermal route through tandem hydrolysis of silver sulfate and cellulose. Thus, this environmentally friendly method is anticipated to be utilized for the biosynthesis of AgNPs and opens up avenues to prepare other metal nanoparticles from metal sulfates. © 2013 Society of Chemical Industry

Epigallocatechin-3-gallate-capped Ag nanoparticles: preparation and characterization

We used an aqueous leaf extract of Camellia sinensis to synthesize Ag nanoparticles (AgNPs). A layer of ca. 6 nm around a group of the AgNPs in which the inner layer is bound to the AgNPs surface via the hydroxyl groups of catechin has been observed. TEM analysis of AgNPs showed the formation of truncated triangular nanoplates and/or nanodisks and spherical with some irregular-shaped polydispersed nanoparticles in absence and presence of shape-directing cetyltrimethylammonium bromide. The polyphenolic groups of epigallocatechin-3-gallate (EGCG) are responsible for the rapid reduction of Ag(+) ions into metallic Ag(0). The free -OH groups are able to stabilize AgNPs by the interaction between the surface Ag atoms of AgNPs and oxygen atoms of EGCG molecules.

Removal and Utilization of Capping Agents in Nanocatalysis

Capping agents are frequently used in colloidal synthesis to inhibit nanoparticle overgrowth and aggregation as well as to control the structural characteristics of the resulted nanoparticles in a precise manner. Study of the effect of the residual capping agents on particle surface has unveiled various adverse and favorable behaviors in catalytic applications. In essence, while the capping agents usually act as a physical barrier to restrict the free access of reactants to catalytic nanoparticles, they can also be utilized to promote catalytic performance of nanocrystals. Due to the complexity of these effects, a general survey of capping agents in nanocatalysis is therefore necessary. This short review starts from a brief introduction of common capping agents in nanoparticle synthesis and their adverse impact on heterogeneous catalysis. Next, representative progresses in capping agent removal and surfactant-free synthesis for obtaining surface-clean nanocatalysts are summarized. Lastly, we discuss the recent advance in utilizing the capping agent effect including chiral modification, molecular recognition, adsorption regulation, surface crowding, and charge transfer at the metal–organic interface and so on to improve the catalytic performance of nanocatalysts.

Differently Environment Stable Bio-Silver Nanoparticles: Study on Their Optical Enhancing and Antibacterial Properties

Generally, limited research is extended in studying stability and applicational properties of silver nanoparticles (Ag NPs) synthesized by adopting ‘green chemistry’ protocol. In this work, we report on the synthesis of stable Ag NPs using plant-derived materials such as leaf extract of Neem (Azadirachta indica) and biopolymer pectin from apple peel. In addition, the applicational properties of Ag NPs such as surface-enhanced Raman scattering (SERS) and antibacterial efficiencies were also investigated. As-synthesized nanoparticles (NPs) were characterized using various instrumentation techniques. Both the plant materials (leaf extract and biopolymer) favored the synthesis of well-defined NPs capped with biomaterials. The NPs were spherical in shape with an average particle size between 14-27 nm. These bio-NPs exhibited colloidal stability in most of the suspended solutions such as water, electrolyte solutions (NaCl; NaNO3), biological solution (bovine serum albumin), and in different pH solutions (pH 7; 9) for a reasonable time period of 120 hrs. Both the bio-NPs were observed to be SERS active through displaying intrinsic SERS signals of the Raman probe molecule (Nile blue A). The NPs were effective against the Escherichia coli bacterium when tested in nutrient broth and agar medium. Scanning and high-resolution transmission electron microscopy (SEM and HRTEM) images confirmed cellular membrane damage of nanoparticle treated E. coli cells. These environmental friendly template Ag NPs can be used as an antimicrobial agent and also for SERS based analytical applications.

In situ and room-temperature synthesis of ultra-long Ag nanoparticles-decorated Ag molybdate nanowires as high-sensitivity SERS substrates

We report on room-temperature synthesis of Ag nanoparticles (NPs) decorated silver molybdate nanowires (SMNs) using a solution-based chemical reaction method. We show that AgxMoyOz (Ag2Mo2O7, Ag2MoO4 and Ag6Mo10O33) nanomaterials can be selectively synthesized by altering the pH value of the reaction media in the presence of silicotungstic acid at room temperature. This reaction process uses isopropyl alcohol as a free radical scavenger and occurs over a short reaction time compared to the traditional hydrothermal method. Moreover, we demonstrate that under UV-light illumination of different periods, Ag NPs of controllable distribution densities are formed in situ on the surface of SMNs in tungstosilicate acid environment. We show that the SERS sensitivity of such Ag NP–SMN complex depends on the distribution density of Ag NPs, with the best structure capable of detecting the p-aminothiophenol at a concentration as low as 1.0×10−11M. The same substrate is further used to enhance the Raman signal from 2-mercaptopyridine from which a quantitative relationship between the analyte concentration and its corresponding Raman intensity can be established.

Direct Synthesis of Ag Nanoparticles Incorporated on a Mesoporous Hybrid Material as a Sensitive Sensor for the Simultaneous Determination of Dihydroxybenzenes Isomers

AbstractThis paper describes the synthesis, characterization, and applications of a mesoporous silica/ multiwalled carbon nanotube (SiO2/MWCNT) hybrid material, which was obtained by a sol–gel process and decorated with silver nanoparticles (AgNPs) ranging in size from 5 to 8 nm. The AgNPs were prepared directly on the surface of the SiO2/MWCNTs material by using N,N‐dimethylformamide (DMF) as the reducing agent, and the resulting material was designated Ag/SiO2/MWCNT. The Ag/SiO2/MWCNT material was characterized by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), high‐resolution transmission electron microscopy (HR‐TEM), and X‐ray photoelectron spectroscopy (XPS). A glassy carbon electrode, modified with the Ag/SiO2/MWCNT material, was used in the development of a sensitive electrochemical sensor for the determination of hydroquinone and catechol in the presence of resorcinol by squarewave voltammetry. Well‐defined and separate oxidation peaks were observed in phosphate buffer solution (PBS) at pH 7. The Ag/SiO2/MWCNT‐modified electrode exhibited high sensitivity for the simultaneous determination of hydroquinone and catechol in the presence of resorcinol, and the limits of detection for hydroquinone and catechol are 0.0117 and 0.0121 μM, respectively. No significant interference was seen for 2,6‐dichloroindophenol, phenol, 4‐nitrophenol, and nitrite ions in the detection of dihydroxybenzenes. Our study demonstrates that the resultant Ag/SiO2/MWCNT‐modified electrode can be used for hydroquinone and catechol detection in the presence of resorcinol and other potentially interfering materials in river water samples.

Local Electric Field Enhancement of Neighboring Ag Nanoparticles in Surface Enhanced Raman Scattering

We used a simple low-temperature hydrothermal approach to synthesize Ag nanoparticles (NPs) and demonstrated their efficiency as organic molecule detectors in surface enhanced Raman Scattering (SERS). Using finite difference time domain simulation, we described an investigation on the distribution of electric fields amplitude of the neighboring Ag NPs. The enhanced electric field is confined at the interparticle gaps and the enhancement factor can be further increased with reducing the spacing between the NPs. The theoretical simulation demonstrated good consistency with the experimental measurement results, which predicts an electric fields amplitude enhancement of 115 at the center of NPs gap and an electromagnetic SERS enhancement of 108. The evidence of clear correlations between SERS enhancement and morphology distribution offer a route to develop more effective SERS substrates.

Extracellular Biosynthesis of Ag Nanoparticles by Commercial Baker's Yeast

In this paper, we demonstrated a simple and efficient method to synthesize Ag nanoparticles (NPs) using commercial and highly active baker's yeast as a stabilizier and reducing agent, which got rid of the cumbersome steps to cultivate yeast. Ag NPs could be formed within 2 min at pH value higher than 8 when silver ion react with the yeast. The effect of pH on the extracellular synthesis of Ag NPs was investigated. The results indicated that the optimized pH value was above 8. The biosynthesized Ag NPs had absorption peaks at 413~455 nm corresponding to their surface plasmon resonance. SEM and TEM images showed that the nanoparticles were uniformly monodisperse and spherical with the size of around 5~25 nm.

One step synthesis of silver nanoparticles and discoloration of blue cotton denim garment in alkali media

In this study a simple green route was used for producing worn-look denim garments with antibacterial prop- erty. Silver nanoparticles were successfully synthesized on denim fabrics byreducingsilvernitrate usingcellulosicchains of cotton, starch and/or glucose in alkali media. Glucose had the ability to reduce indigo dye and resulted in better control of particle size and stability. Transmission electron microsco- py (TEM), dynamic light scattering (DLS) and UV-vis spec- troscopy were employed to characterize the synthesized Ag nanoparticles. The treated denim fabrics were also character- ized by scanning electron microscopy (SEM), Raman spec- troscopy and colorimetric measurements. The results indicat- ed the successful synthesis of nano silver particles with aver- age particle size of 30-40 nm on the indigo dyed cellulosic fabric along with denim color reduction. Although the fabrics showed antibacterial activity against E. coli and S. aureus, a decrease in the antibacterial feature was observed in presence of glucose as a suitable nutrient for the growth of bacteria.

Ag/lamellar hosts composites: a route to morphology-controllable synthesis of Ag nanoparticles

An easy and novel routine are reported for the preparation of metallic silver nanoparticles (AgNPs) with controlled morphology, using Na+–magadiite swelled with hexadecyltrimethylammonium bromide (CTA+–magadiite) and a layered aluminophosphate with kanemite-type structure modified with n-dodecylammonium and n-butylammonium (but,dod-AlPO-kan) as hosts. For the preparation of the metallic AgNPs (Ag0) in the interlamellar space, the CTA+–magadiite and but,dod-AlPO-kan hosts were dispersed in N,N-dimethylformamide (DMF) solution with different AgNO3 concentrations. DMF acts as reducing agent of Ag+ ions leading to nanoparticles with disk-like morphology of magadiite silicate; these were characterized by TEM and UV–Vis spectroscopy. On the other hand, the AgNPs are intercalated in but,dod-AlPO-kan showing spherical-like morphology. The UV–Vis spectra of the nanocomposites based on Ag0 and magadiite silicate show bands at 565 nm that can be attributed to Ag0 nanodisks. The Ag-but,dod-AlPO-kan-based nanocomposites present a band at 422 nm attributed to the surface plasmon resonance of Ag0 nanospheres. The results of transmission electron microscopy agree very well with XRD and UV–Vis analysis, indicating the formation of AgNPs with different morphologies using the two kinds of lamellar materials. The magadiite host has an important role in the synthesis of Ag nanodisks, because it controls the growth of nanoparticles inside the interlayer region with disk-like morphology due the high interlayer interactions of the silicate, leading to the growth of nanoparticles in only two directions (xy plane). On the other hand, when but,dod-AlPO-kan is used a sphere-like morphology is preferred due the best accommodation of AgNPs between the layers of aluminophosphate host.

White Light Assisted Photosensitized Synthesis of Ag Nanoparticles: Excited-State Hydrogen Bonding Roles

Ag nanoparticles (NPs) with different surface morphologies can be synthesized through white light irradiation of photochemically prepared Ag nanoseeds within 20 min. The fundamental photophysical and photochemical properties of benzil in deaerated solvents at room temperature are investigated through analyzing nanosecond absorption spectra. In ethanol, after the single photon excitation of benzil by 355 nm nanosecond laser pulses, one kind of reactive intermediate with a long-lived lifetime of 375.83 ± 93.70 μs is generated and capable of reducing the coexisted Ag+ to generate Ag nanoseeds with their diameters in the range from 3 to 12 nm. Theoretical calculations indicate that the reactive intermediate is benzil-ethanol hydrogen-bonded complex biradical (ben-eth biradical). Furthermore, the excited-state hydrogen bonding dynamics and its influence on the photophysical and photochemical properties are discussed. White light irradiation under air can make these Ag nanoseeds grow in size with a speed of 10 ...

Development of novel catalytically active polymer-metal-nanocomposites based on activated foams and textile fibers.

In this paper, we report the intermatrix synthesis of Ag nanoparticles in different polymeric matrices such as polyurethane foams and polyacrylonitrile or polyamide fibers. To apply this technique, the polymer must bear functional groups able to bind and retain the nanoparticle ion precursors while ions should diffuse through the matrix. Taking into account the nature of some of the chosen matrices, it was essential to try to activate the support material to obtain an acceptable value of ion exchange capacity. To evaluate the catalytic activity of the developed nanocomposites, a model catalytic reaction was carried out in batch experiments: the reduction of p-nitrophenol by sodium borohydride.

The effect of carbon nanotubes as a support on morphology and size of silver nanoparticles

In this study, direct precipitation technique was used to synthesize Ag nanoparticles supported by carbon nanotubes. After distinguishing the best situation in the synthesis of Ag nanoparticles, carbon nanotubes as the support were used to control the Ag nanoparticle size. The prepared carbon nanotubes and Ag nanoparticles were investigated by using X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The results showed that carbon nanotubes can play an important role in controlling the morphology and size of the obtained powders, and the size of Ag nanoparticles synthesized on the carbon nanotubes is smaller.